Citrus Genetic Resources in California
Analysis and Recommendations for Long-Term Conservation
Report of the Citrus Genetic Resources Assessment Task Force
T.L. Kahn, R.R. Krueger, D.J. Gumpf, M.L. Roose, M.L. Arpaia, T.A. Batkin, J.A. Bash, O.J. Bier, M.T. Clegg, S.T. Cockerham, C.W. Coggins Jr., D. Durling, G. Elliott, P.A. Mauk, P.E. McGuire, C. Orman, C.O. Qualset, P.A. Roberts, R.K. Soost, J. Turco, S.G. Van Gundy, and B. Zuckerman
Report No. 22 June 2001
Published by Genetic Resources Conservation Program Division of Agriculture and Natural Resources UNIVERSITY OF CALIFORNIA
i This report is one of a series published by the University of California Genetic Resources Conservation Program (technical editor: P.E. McGuire) as part of the public information function of the Program. The Program sponsors projects in the collection, inventory, maintenance, preservation, and utilization of genetic resources important for the State of California as well as research and education in conservation biology. Further information about the Program may be obtained from: Genetic Resources Conservation Program University of California One Shields Avenue Davis, CA 95616 USA
(530) 754-8501 FAX (530) 754-8505 e-mail: [email protected] Website: http://www.grcp.ucdavis.edu/ Additional copies of this report may be ordered from this address.
Citation: Kahn TL, RR Krueger, DJ Gumpf, ML Roose, ML Arpaia, TA Batkin, JA Bash, OJ Bier, MT Clegg, ST Cockerham, CW Coggins Jr, D Durling, G Elliott, PA Mauk, PE McGuire, C Orman, CO Qualset, PA Roberts, RK Soost, J Turco, SG Van Gundy, and B Zuckerman. 2001. Citrus genetic resources in California: Analysis and recommendations for long-term conservation. Report No. 22. University of California Division of Agriculture and Natural Resources, Genetic Resources Conserva- tion Program, Davis CA USA.
© 2001 Regents of the University of California
Cover photograph: Assemblage of citrus fruits. Photo credit: Eric Sander, 10558 Putney Rd, Los Angeles, CA 90064, http://www.ericsander.com, used by permission.
Inside front cover: Top row, from left: Washington navel orange (CRC #1241) and Delta Valencia (Delta seedless) or- ange (CRC #3963); Second row, from left: Vainiglia pink-fleshed sweet orange (CRC #3801) and Moro blood orange (CRC #3830); Third row, from left: Mexican lime (CRC #1710), Variegated pink-fleshed Eureka lemon (CRC #2367), and Citrus hystrix (CRC #2454); Bottom row, from left: Frost Nucellar #1 (Owari) Satsuma mandarin orange (CRC #3178) and Gold Nugget mandarin orange (CRC #3913) Photo credit: All individual photographs by Ottillia J. Bier.
Inside back cover: Sliced fruits demonstrating diversity in the Citrus Variety Collection. Photo credit: William S. Myerchin
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ii TABLE OF CONTENTS
Preface ...... v 3. Citrus genetic resources in California ...... 15 Citrus Genetic Resources Assessment • Citrus Variety Collection (CVC) ...... 15 Task Force membership...... vii • Citrus Evaluation Blocks (CEBs) ...... 16 Charge to Task Force ...... ix • Citrus Clonal Protection Program (CCPP) ...... 17 Abbreviations and acronyms used in • National Clonal Germplasm Repository this report ...... x for Citrus and Dates (NCGRCD) ...... 18 Executive summary ...... xiii • Interrelationships among CVC, 1. Introduction ...... 1 CEBs, CCPP, and NCGRCD ...... 19 2. Background ...... 3 4. US citrus genetic resources outside California ...... 23 • History of citrus in California ...... 3 • Economic value of citrus to California ...... 4 5. International citrus genetic resources ...... 25 • Taxonomy of citrus ...... 5 6. Analysis and recommendations in support • Biology of citrus ...... 5 of citrus genetic resources in California ...... 29 • Origin and distribution of citrus ...... 6 Literature cited ...... 37 • Domestication of citrus ...... 6 Appendix. Holdings of the University of California, • Genetic diversity of citrus ...... 6 Riverside Citrus Variety Collection (CVC) ...... 43 • Utilization of genetic resources in California...... 8 • Importance of citrus genetic resources conservation ...... 11 • Acquisition of citrus genetic resources ...... 12 • Conservation of citrus genetic resources ...... 14
iii LIST OF TABLES AND FIGURES Tables Figure 7. Fruit and branch of Australian finger lime (Microcitrus australasica CRC #1484)...... 8 Executive summary table 1. Costs of personnel, equipment, supplies, and facility requirements Figure 8. Example of diversity at the molecular level. .. 9 for the CVC...... xii Figure 9. Howard B. Frost (l.), first citrus breeder Table 1. Summary of taxa in subgenus Citrus...... 6 at UC Riverside (beginning in 1914) and Robert K. Soost, who succeeded Frost as citrus breeder in 1949 Table 2. Chronology of UCR Citrus Variety and was a curator of the CVC from 1982 until 1986. ... 9 Collection supervision...... 15 Figure 10. Fruit and branch of Gold Nugget Table 3. Type and number of accessions in the CVC. 17 mandarin orange (CRC #3913)...... 10 Table 4. Research projects utilizing accessions Figure 11. Trunk of root-stock showing damage in the CVC (1997–2001)...... 32 from Phytophthora infection...... 10 Table 5. Costs of personnel, equipment, supplies, Figure 12. Trunk with bark removed to reveal and facility requirements for the CVC...... 35 damage caused by the citrus tristeza virus (CTV)...... 11 Figure 13. Successful graft...... 11 Figures Figure 14. An incompatible graft shown with Executive summary figure 1. Movement of bark stripped away...... 11 citrus genetic resources into, within, and out of Figure 15. Hiryu (Flying Dragon trifoliate orange, the California system for conservation and Poncirus trifoliata, CRC #3795)...... 12 utilization of citrus genetic resources...... xv Figure 16. W.P. Bitters, curator of the Citrus Figure 1. December 23, 1914 headlines from Variety Collection from 1946 to 1982...... 16 the Riverside Daily Press...... 4 Figure 17. Budwood source trees for the Citrus Figure 2. Original Citrus Experiment Station Clonal Protection Program in a screenhouse- staff on the steps of the main office-laboratory protected planting at the Lindcove Research building ca. 1916...... 4 and Extension Center...... 18 Figure 3. A cultivation demonstration at Figure 18. Seedlings of indicator plants for Riverside ca. 1917...... 5 indexing, growing in cool-temperature chamber Figure 4. Microscopic cross-section of developing of NCGRCD greenhouse facilities...... 19 seed revealing the multiple nucellar embryos Figure 19. Movement of citrus genetic resources contained within (polyembryony)...... 7 into, within, and out of the California system Figure 5. Germinating seeds revealing the for conservation and utilization of citrus genetic multiple nucellar seedlings emerging from the resources...... 20 seed at the left (polyembryony)...... 7 Figure 20. Headstand of furrow irrigation system...... 31 Figure 6. The strikingly distinct fruits of Buddha’s Figure 21. The squashed, softened stigma, hand citron (Fingered citron, Citrus medica, one day after pollination, reveals germinating CRC #3768)...... 8 viable pollen grains...... 34
iv PREFACE
CITRUS CROPS IN CALIFORNIA mean primarily navel Variety Collection (CVC) at the UC Riverside campus, and valencia oranges, lemons, grapefruit, and tangerines, the task force undertaking this analysis was comprised of tangelos, and tangors. By the most recent figures avail- representatives from all components. The role of citrus able (1998–1999) at the time of this writing, the Califor- in California’s economy and the history of citrus in nia Agricultural Statistics Service reports the following southern California were driving forces for the establish- total values for these crops: navel oranges $227 million; ment of the University of California Citrus Experiment valencia oranges $188 million; lemons $214 million; Station in 1906, and ultimately the UC Riverside cam- grapefruit $81 million; and tangerines et al. $23 million. pus, now a major university in its own right. However, Altogether that’s about a three-quarter-billion-dollar there were concerns that the current and long-term fi- citrus industry, placing citrus in the top ten of California nancial and facility status of the CVC was not adequate crops. Three of these—oranges, lemons, and grapefruit— to allow it to continue as the primary collection of citrus are individually also among the top 30 California export genetic resources for California. No organization is in crops. To sustain this productivity and competitiveness the position to single-handedly resolve this situation. in the US by creating new varieties, maintaining the The UC Genetic Resources Conservation Program, with diversity of citrus crops, ensuring healthy trees in the its mission of facilitating genetic resources collections for field, and desirable fruit in the marketplace, it is impera- species important to California, and the UC Riverside tive that breeders, researchers, and the industry have College of Natural and Agricultural Sciences together access to reliable collections of citrus genetic resources. convened this task force as a first step in addressing this As this report shows, this has been possible by virtue of concern for the CVC. The major objective of this task an unofficial state ‘system’ for conserving and utilizing force was to obtain a clear statement of the value of the citrus genetic resources. This system is comprised of Uni- collection, the role it plays, and the resources necessary versity of California, state, and federal organizations and to sustain and enhance it. With the findings of this re- their interrelationships are documented herein. port as motivation and its recommendations as a strat- The reliance on ex situ collections of genetic diver- egy, we hope the targeted organizations will find it im- sity for crop improvement is typical for most California perative to contribute to the solution of this crisis in sup- crops. Of the 350 agricultural commodities produced in port of citrus genetic resources for the good of California California, less than 10 percent are either species indig- citrus production and citrus research in general. enous to California or related to California indigenous species. The vast majority are introduced from outside Calvin O. Qualset, Director California and usually from outside the US as well. This Genetic Resources Conservation Program puts a premium on the existing ex situ collections main- Division of Agriculture and Natural Resources tained in California. Generating a collection from the University of California areas of a given crop’s genetic diversity is increasingly difficult, if not impossible, for most crops. Michael T. Clegg, Professor As effective as it has been, the current situation for Dept. of Botany & Plant Sciences citrus is a decentralized system that has been driven by Former Dean (1994–2000) need and opportunity, not by careful planning involving College of Natural and Agricultural Sciences all components. While this report has focused primarily University of California, Riverside on the University of California component—the Citrus
v vi CITRUS GENETIC RESOURCES ASSESSMENT TASK FORCE MEMBERSHIP
Mary Lu Arpaia, Cooperative Extension Sub- Robert R. Krueger, Curator, USDA-ARS National tropical Horticulturist, Dept. of Botany and Plant Clonal Germplasm Repository for Citrus and Sciences, University of California, Riverside CA Dates, Riverside CA Ted A. Batkin, President, Citrus Research Board, Patrick E. McGuire, Associate Director, Genetic Visalia CA Resources Conservation Program, Div. of Agri- culture and Natural Resources, University of John A. Bash, Staff Research Associate, Citrus California, Davis CA Clonal Protection Program, Dept. of Plant Pa- thology, University of California, Riverside CA Peggy A. Mauk, Cooperative Extension Sub- tropical Horticultural Advisor, Riverside and San Ottillia J. Bier, Staff Research Associate, Citrus Bernardino Counties, University of California Variety Collection, Dept. of Botany and Plant Sciences, University of California, Riverside CA Chuck Orman, Director of Science and Tech- nology, Sunkist Growers, Ontario CA Michael T. Clegg, ex officio, Professor of Genet- ics, Dept. of Botany and Plant Sciences and Calvin O. Qualset, ex officio, Director, Genetic Former Dean (1994–2000), College of Natural Resources Conservation Program, Div. of Agri- and Agricultural Sciences, University of Califor- culture and Natural Resources, University of nia, Riverside CA California, Davis CA Stephen T. Cockerham, Superintendent, Agri- Philip A. Roberts, Associate Dean, Agricultural cultural Operations, University of California, Riv- Experiment Station and Cooperative Extension, erside CA College of Natural and Agricultural Sciences and Professor of Nematology, Dept. of Nema- Charles W. Coggins Jr., Professor Emeritus of tology, University of California, Riverside CA Plant Physiology, Dept. of Botany and Plant Sci- ences, University of California, Riverside CA Mikeal L. Roose, Professor of Genetics, Dept. of Botany and Plant Sciences, University of Califor- Don Durling, Durling Nursery, Inc., Fallbrook CA nia, Riverside CA Georgia Elliott, Executive Director of Corporate Robert K. Soost, Professor Emeritus of Genetics, and Foundation Relations, Development Of- Dept. of Botany and Plant Sciences, University fice, University of California, Riverside CA of California, Riverside CA David J. Gumpf, Director, Citrus Clonal Protec- John Turco, Corotto/Turco Farms, San Jose CA tion Program and Professor, Dept. of Plant Pa- thology, University of California, Riverside CA Seymour D. Van Gundy, Professor Emeritus of Nematology, Dept. of Nematology, University Tracy L. Kahn, Task Force chair, Curator, Citrus of California, Riverside CA Variety Collection; Senior Museum Scientist, Dept. of Botany and Plant Sciences; and Lec- Bob Zuckerman, B&Z Nursery Inc., Porterville CA turer, Dept. of Biology, University of California, Riverside CA
vii viii CHARGE TO THE TASK FORCE
EVALUATE THE CURRENT STATUS of the Citrus Variety documenting these findings and include recommenda- Collection (CVC) at the University of California, River- tions for organizational, fiscal, and administrative steps side campus with regard to its contents, utilization, and necessary to ensure the long-term security of the CVC as value and its interrelationships with other California, a dynamic genetic resources conservation facility serving federal, and international citrus genetic resources and the California citrus industry and University of Califor- research organizations and activities. Prepare a report nia research, teaching, and extension objectives.
ix ABBREVIATIONS AND ACRONYMS USED IN THIS REPORT
APHIS Animal and Plant Health Inspection Ser- IOCV International Organization of Citrus Vi- vice of the US Dept. of Agriculture rologists ARS Agricultural Research Service of the US IPGRI International Plant Genetic Resources In- Dept. of Agriculture stitute CCPP Citrus Clonal Protection Program LREC UC Lindcove Research and Extension Center CDFA California Department of Food and Agri- culture NCGRCD National Clonal Germplasm Repository for Citrus and Dates CEB Citrus Evaluation Block NPGS National Plant Germplasm System CNAS College of Natural and Agricultural Sci- ences, University of California, Riverside PI Plant Introduction, USDA NPGS CRB Citrus Research Board RAPD random amplified polymorphic DNA CRC-AES Citrus Research Center and Agricultural RFLP restriction fragment length polymorphism Experiment Station SCREC UC South Coast Research and Extensions CSIRO Commonwealth Scientific and Industrial Center Research Organization TAMUK Texas A&M University, Kingsville CTV citrus tristeza virus UC University of California CVARS UCR Coachella Valley Agricultural Re- UCR University of California, Riverside search Station USDA United States Department of Agriculture CVC Citrus Variety Collection USHRL United States Horticultural Research Labo- CVIP Citrus Variety Improvement Program ratory, USDA ELISA enzyme-linked immuno-sorbant assay VI Variety Introduction FAO Food and Agriculture Organization of the WFFVC A.H. Whitmore Foundation Farm Variety United Nations Collection GCGN Global Citrus Germplasm Network GRIN Genetic Resources Information Network, a unit of the National Genetic Resources Program
x EXECUTIVE SUMMARY FINDINGS Because of the integration of the CVC with the CCPP and NCGRCD, there are no major impediments to im- The California citrus genetic resources portation of citrus genetic resources into California. conservation and utilization system Citrus genetic resources are not native to California, meaning that ex situ conservation in California of ac- CITRUS CROPS (especially oranges, lemons, and grape- quired accessions is the only way to ensure their avail- fruit) are a significant component of California’s agricul- ability for continued use. In addition, access to citrus tural production. To maintain or increase their value, genetic resources from native habitats is increasingly un- commercial citrus varieties must be available to meet the dependable, putting a premium on conservation of what needs of the diverse citrus producing regions in Califor- has already been collected. nia and consumer preferences. Ensuring continued vari- ety development, healthy trees in the field, and desirable Expanded use of molecular techniques such as marker- fruit in the marketplace means continued research, breed- assisted selection and transformation in breeding pro- ing, and product development. All of this requires reli- grams will increase the value of genetic resources for able availability in California of citrus genetic resources. crop improvement and allow the use of more distantly related species as gene sources for cultivated species. California maintains one of the largest and most diverse This means that increasingly the concept of genetic re- assemblages of citrus genetic resources in the world with sources will expand to include cDNA and genomic a functional conservation and utilization system com- DNA libraries, and the probes, clones, and sequences prising three primary units: the Citrus Variety Collection derived from them. (CVC) and the Citrus Clonal Protection Program (CCPP) at the University of California, Riverside and The Citrus Variety Collection the USDA National Clonal Germplasm Repository for Citrus and Dates (NCGRCD). Closely collaborating ✦ The CVC, with 865 accessions, is the key component with these three units are the UC Riverside Citrus of the California system for maintaining citrus genetic Breeding Program and the California Citrus Research resources. Board. ✦ The CVC is the oldest component, initiated in 1910 This California citrus genetic resources system is unique with a focus on establishing a broad representation of among organized collections throughout the world and accessions from all citrus-growing regions of the serves as a model for conservation, utilization, and world. teaching. The system maintains a broad cross-section of genetic diversity along with complementary programs ✦ The collection presents a long-standing investment of that provide virus-free budwood for commercial use, pro- human resource efforts and considerable investment grams for distributing genetic resources for research uses, of public funds through the University of California, and research programs for crop improvement, physiology, State of California, US Dept. of Agriculture as well as biochemistry, phylogeny, genetics, and molecular biol- funds and donations of plant materials from private ogy. Executive summary figure 1 illustrates the flow of and commercial resources. Clearly, this genetic re- genetic resources into and out of the system and among sources collection could not be developed if it were to these units, the Citrus Evaluation Blocks (CEBs), and be initiated today. the UC Riverside Citrus Breeding Program.
xi Citrus clonal Citrus seed and pollen material from from outside California outside California and the US and the US
Imported into California directly to Imported into California directly to the the CCPP under US federal and CVC or the NCGRCD under US federal California regulations and California regulations.
Citrus Clonal Protection Program (CCPP) Movement of citrus UC Riverside genetic resources Citrus Breeding within California Program
Citrus Evaluation Blocks (CEBs) Citrus Variety National Clonal Germplasm Collection Repository for Citrus and (CVC) Dates (NCGRCD)
Citrus genetic resources move to California citrus nurseries as virus-free budwood from the CCPP and to national and international citrus researchers as virus-free budwood from the NCGRCD and as seed and pollen from the CVC and NCGRCD.
Commercial citrus National and nurseries international citrus researchers
California Consumers citrus growers
Executive summary figure 1. Movement of citrus genetic resources into, within, and out of the Californa system for conservation and utilization of citrus genetic resources.
xii ✦ The security of CVC accessions and the extent of its USDA financial support to the operations of the activities to enhance the scope and value of the ac- CVC has been provided in the past two years through cessions are impaired by the piece-meal, transient, a short-term cooperative agreement. and undependable nature of its current funding. Only partial support for the curator position is secure on a ✦ Integrated pest management techniques are not opti- reasonably long-term basis. mally employed in the management of CVC plantings. ✦ The full range of tasks necessary for curating and ad- ministering the CVC require at a minimum a full- ✦ The current rootstock status of the CVC collection time curator, a full-time technical assistant, and sea- appears to be adequate with respect to resistance to sonal part-time employees. These tasks cannot be met known disease threats. with the current levels of support without impairing the integrity of the collection for current and future ✦ Information on the accessions of the CVC has been uses. maintained on a computer database since 1996, re- placing a handwritten index card system initiated at ✦ Increasing requests for educational outreach programs the inception of the CVC. from the CVC is a sign of public interest in genetic resources, especially citrus. Meeting these requests ✦ Electronic access to some information about the CVC limits the time that can be devoted to critical aspects is at the CVC website (http://cnas.ucr.edu/~citrus/ of maintenance and evaluation of the accessions in index.htm). In addition, some information about the the CVC. There is no funding dedicated to these ac- CVC collection is available from the USDA GRIN tivities. database (http://www.ars-grin.gov/).
✦ Immediate facility and equipment needs appear to be ✦ Greenhouse facilities are inadequate for the CVC to met through availability of space through the UCR carry out propagation and maintenance of accessions. Dept. of Botany and Plant Sciences and loans of some specialized equipment. However, there is no long- RECOMMENDATIONS term commitment to these space arrangements and no plans to accommodate CVC growth. The California citrus genetic resources ✦ Normal care of a citrus genetic resources collection is conservation and utilization system considerably more complex and expensive than the maintenance of plants in a commercial grove. CVC 1. No changes in the management structure of the currently receives horticultural management services CVC, the CCPP, or the NCGRCD are advocated. The from the UC Riverside Agricultural Operations de- continued close collaboration among the three units is partment. However, the trend is for reduction of ser- essential to the functioning of a citrus genetic resources vices that can be provided and this impacts the long- conservation and utilization system for California. term security of the CVC. It may be necessary for the CVC budget to accommodate these management 2. The establishment of a California Citrus Genetic costs. Resources Advisory Committee (CACGRAC) is rec- ommended. This committee, composed of research and ✦ Few granting agencies will fund baseline genetic re- extension workers, agency and University administra- sources conservation activities. Some successful pro- tors, growers, processors, marketers, consumers, and oth- posals by the curator have furnished indirect support ers, will provide guidance to the staffs of the units that for the CVC. However, short-term (annual) grants comprise the California citrus genetic resources conser- cannot be a successful long-term strategy for conser- vation and utilization system to assure the acquisition of vation activities. critical genetic resources and their long-term conserva- tion and efficient distribution. ✦ The value of the CVC to the US National Plant Germplasm System, operated by the US Dept. of Ag- 3. The dependence of the NCGRCD on the CVC for riculture, is reflected by several points: (1) seed and seed and field evaluation facilities should be officially pollen requests to the NCGRCD are filled from mate- recognized by the parent organization of each unit and rial maintained by the CVC, (2) the CVC provides enhanced by a long-term commitment of support for the field evaluation opportunities and vegetative material CVC by the USDA NPGS. for the NCGRCD, and (3) about 70% of the citrus accessions listed publicly as available in the NPGS 4. Citrus genetic resource management for California are available only at the CVC. Some temporary should expand to include resources such as DNA librar-
xiii ies, probes, and clones. The appropriate unit and ad- Activities: Dissemination of information. equate funding for the effort should be topics for consid- eration by the proposed California Citrus Genetic Re- 12. The CVC website is a potentially valuable distribu- sources Advisory Committee. (Rec. 2 above). tion point for CVC collection characterization and evaluation data. It may need relocation from its current The Citrus Variety Collection status on the UCR College of Natural and Agricultural Sciences server. The website should include contact in- Activities: Acquisition formation for the staff.
5. There should be continued and enhanced linkages Personnel with other national and international citrus genetic re- sources collections. 13. Positions and staffing levels needed are a full-time curator, full-time technical assistant/assistant curator, 6. Acquisition of new accessions, both from within and part-time seasonal assistants, and a part-time database/ outside California and of wild or naturally occurring cit- website specialist. rus relatives from their native habitats, is an important function for the CVC. Acquisitions should be guided by a plan developed with assistance of the recommended Facilities and equipment advisory committee. Every effort should be made to ac- quire accessions for the CVC that are not currently 14. The CVC should have at least two up-to-date, net- available in California, taking full advantage of the Cali- worked computers and at least one laser-quality printer, fornia system that allows importation of citrus genetic devoted to such activities as accessioning, data analysis resources. and exchange, equipment and budget monitoring, and preparation of outreach materials. Activities: Documentation and data- 15. Facilities and equipment needs include research base management equipment, a vehicle, and a greenhouse/headhouse struc- ture on or near the orchard site to facilitate propagation 7. The CVC database should be enhanced to include of new or replacement accessions and field evaluation digital representations of important accession character- activities, house equipment and tools, and offer a recep- istics such as photographs of flower, leaf, and fruit mor- tion point for CVC visitors and tours. phology, gels of biochemical and molecular genetic ana- lyses, and disease susceptibility or resistance symptoms. Financial resources 8. There should be continued exchange of information 16. The CVC needs an annual budget for operating ex- between the CVC and the USDA NPGS GRIN data- penses and outreach that reflects the full costs of these bases. activities including maintenance on facilities and equip- ment and depreciation on equipment (Executive sum- Activities: Maintenance mary table 1).
9. Full implementation of integrated pest management 17. The CVC needs funding for first-time and one-time techniques should be deployed in the CVC plantings expenses to bring its physical facilities to a level ad- which, along with the full installation of the low-volume equate to meet its needs as a California repository of cit- irrigation system, would not only increase the efficiency rus genetic resources (Executive summary table 1). of tree cultivation in the CVC, but would also enhance the unit as a showcase for California citrus. 18. Funding to enhance and sustain the CVC’s role in conservation and utilization of citrus genetic resources 10. The CVC needs to monitor information about citrus for California properly involves the US Government, pathogens and keep in contact with citrus specialists to the State of California, the University of California, and anticipate disease threats to the collection. the citrus industry.
Activities: Evaluation, characterization, 19. An endowment fund should be established with in- and research terest earned being dedicated to meet annual operations costs of the CVC. The fund should be organized under 11. Users of the CVC should be encouraged to contrib- the auspices of the UC Riverside campus with contribu- ute to the maintenance of its collections. tions from the diverse enterprises comprising the Califor- nia citrus industry and individual donors. A committee
xiv composed of representatives of USDA NPGS, UC, CDFA, and CRB and individuals having strong interest in the preservation of citrus varieties and diversity should be convened to develop this fund.
Administration
20. The relationship of the management of the CEBs to management of the CVC should be formalized and the extent of the effort required by the CVC curator to man- age the CEBs needs to be defined to ensure that these activities do not come at the expense of CVC activities.
Executive summary table 1. Costs of personnel, equipment, and facility requirements for the CVC. Initial and replacement Category cost (dollars) Annual cost (dollars) Personnel Curator (1.0 FTE) 65,000a,b Technical Assistant (1.0 FTE) 40,000a,b Database/website specialist (0.5 FTE) 21,000a,c Temporary assistance 10,000a,d Supplies Nursery and lab supplies 5,000 Acquisition, research, & evaluation 25,000e Equipment Vehicle: minivan 20,000 Vertical illuminator and filter sets (Zeiss) 5,000 Computers (2) 5,000 Printer 600 Electric cart 5,000 Services received Annual tree maintenancef 24,000 Annual tree pruning 2,000 Annual fruit reduction 7,000 Annual vehicle maintenance 2,000 Facility Greenhouse (36’x60')/headhouse (20’x36') 200,000 Utilities for field facilities 2,000 Subtotal 235,600 203,000 Contingency fund reserve 12% of annual budget 24,360 Total 235,600 227,360 aincludes benefits; dWork-study and summer students; bestimate, actual amount will depend on job title; eReserved for supplies, travel, and staffing cbased on Computer Resource Specialist II title, fPerformed currently by UCR Agricultural entry level; Operations, does not include pruning.
xv xvi
INTRODUCTION
CITRUS IS THE MOST IMPORTANT subtropical fruit crop citrus and citrus relatives. This diversity is manifested in North America. In California, citrus has been pro- visually by types with fruits of unusual shapes, sizes, col- duced commercially since the mid-1800s. Currently ap- ors, and flavors growing on trees of varying heights, proximately 275,000 acres in California are devoted to forms, and foliage characteristics. In addition, in this citrus, yielding about 4.5 billion pounds of fruit annually. material there is great variation in the chemical com- In 1999, the gross on-farm value of California citrus was pounds of the rind and flesh manifested by variation in about $734 million. In 1997, the export value for Cali- flavor, texture, and aroma. Underlying this visible and fornia citrus was approximately $454 million. Collec- tangible diversity is genetic diversity which can be ma- tively, citrus is one of the top ten crops in the state. To nipulated, combined, and transferred for improvement of create new varieties, maintain a large diversity of com- citrus crops for productivity, flavor, and disease and envi- mercial citrus varieties, and ensure healthy trees in the ronmental tolerance and for development of new food field and desirable fruit in the marketplace, reliable and horticultural crops. sources of citrus genetic resources are required. In addi- The primary users of the CVC are research scien- tion, reliable collections of citrus genetic diversity are tists, plant breeders, nurserymen, growers, and citrus in- crucial for the development of new compounds for hu- dustry representatives. This collection was established in man use, especially since wild citrus populations are rare 1910 to provide genetic resources for citrus research in and habitat destruction threatens those that still exist. California. In recognition of the perpetual need for ge- One of the largest and most diverse assemblages of citrus netic resources, the USDA National Plant Germplasm genetic resources in the world is maintained in Califor- System (NPGS) established the NCGRCD at UC River- nia by what is, in essence, a conservation and utilization side in 1987 adjacent to the CVC. The CVC also pro- system comprising three primary units: the Citrus Vari- vides genetic resources for the UC CCPP which cur- ety Collection (CVC) and the Citrus Clonal Protection rently provides the California citrus industry and re- Program (CCPP) at the University of California and the searchers with a clean primary vegetative propagation USDA National Clonal Germplasm Repository for Cit- tissue (budwood) source of important citrus scion and rus and Dates (NCGRCD). Closely collaborating with rootstock varieties. these three units are the UC Riverside Citrus Breeding This report reviews and summarizes the roles and Program and the California Citrus Research Board. interrelationships of the programs in California (CVC, The UC CVC is one of the most extensive collec- CCPP, and NCGRCD) to recommend continued acqui- tions of citrus diversity in the world, encompassing ap- sition, conservation, and availability of citrus genetic proximately 1,720 trees representing 865 accessions of materials for California.
1 2
BACKGROUND
HISTORY OF CITRUS IN CALIFORNIA they established in Pomona in 1890 devoted only two acres to citrus and contained only 28 varieties. THE FIRST CITRUS TREES IN CALIFORNIA are believed to Faced with insufficient citrus research at the have been planted from seed in 1769 with the founding Pomona station, citrus growers in Riverside founded the of the Mission San Diego de Acalá. With the establish- Riverside Horticultural Club to conduct cooperative re- ment of additional missions, plantings of citrus trees in search (REED 1895). In addition, they lobbied the mission gardens extended the presence of citrus through- USDA to send citrus researchers to Riverside. In 1904, out southern California (WEBBER et al. 1967). During USDA pomologist G. Harold Powell arrived to study these early years, there were no commercial plantings of fruit decay (SHAMEL 1921). In 1905, the California Leg- citrus in California. In fact, it was reported that the mis- islature appointed three commissioners to represent the sion padres refused to allow citrus to be planted outside Regents of the University of California in selecting a the mission orchards (LUGO 1950). citrus experimentation site (STATUTES OF CALIFORNIA However, with the secularization of the missions in 1905). Riverside was selected, the Citrus Experiment 1833, citrus became more available and small groves Station was established in 1906, and the station at Po- were established outside the missions. In 1841, William mona was closed. The original site for the station, called Wolfskill planted the first commercial orchard in Los the Rubidoux Laboratory, was 23 acres on the eastern Angeles (EVANS 1874, DOWNEY 1874, WILSON 1965). slope of Mount Rubidoux near downtown Riverside. A With the ceding of California to the United States in collection of citrus species and varieties was initiated at 1848 and the gold rush of 1849, the population of Cali- this location in 1910. fornia increased dramatically, and with it, the demand In 1912, Herbert John Webber, a former USDA for fruit. By 1867, the USDA reported 15,000 orange researcher, was appointed director of the Citrus Experi- trees and 2,300 lemon trees in the Los Angeles area. In ment Station. Charged with selecting a site for an ex- 1873, the first Washington navel orange trees were panded Citrus Experiment Station, Webber inspected planted at Riverside where a thriving citrus industry de- many locations in California, but favored keeping the veloped. Riverside groves contained more than 200,000 station at Riverside. Many communities in southern citrus trees by 1882 (ROE 1932). Inspired by the success California competed for the station, but ultimately a new of citrus growers in Riverside, early California settlers 475-acre site at Riverside was selected (UNIVERSITY OF extended commercial citrus plantings to other suitable CALIFORNIA REGENTS 1914, Figure 1). Webber assem- regions of the state (LAWTON and WEATHERS 1989). bled what became known as the ‘original staff’ of the During these early years, individual citrus growers experiment station, many of whom are regarded today as conducted their own research on cultural and pest prob- pioneers in their field (LAWTON and WEATHERS 1989, lems. However, with the rapid expansion of the citrus Figure 2). In June 1917, various experimental plots were industry came the need for more extensive agricultural established at the new site (Figure 3), including 65 acres research. In 1868, the University of California was estab- of oranges for studies in cultivation and fertilization and lished as a land grant institution under the provisions of a five-acre collection containing 500 types of citrus from the Morrill Act of 1862 (FERRIER 1930). In 1874, the all over the world. Types from the original Rubidoux UC Agricultural Experiment Station was founded with Laboratory collection (WEBBER 1918, METCALF 1963) Eugene W. Hilgard as its first director. The passage of the were included. Hatch Act in 1887 and the second Morrill Act of 1890 By its many contributions, the Citrus Experiment provided additional support for agricultural science Station established an international reputation for citrus (TRUE 1937). Hilgard and the Regents of the University research. By act of the Regents of the University of Cali- of California decided to establish four ‘regional culture’ fornia, the Riverside campus was declared a general cam- stations in the state’s four main climatic regions (STADT- pus in 1959 and graduate and professional programs were MAN 1970, NYE 1983). However, the experiment station added in 1960. In 1961, the Regents changed the name
3 of the Citrus Experiment Station to the Citrus Research rank 5th, 17th, and 30th, respectively, among the top 50 Center and Agricultural Experiment Station (CRC- California agricultural export commodities. The total AES). Today, the CRC-AES makes the largest commit- 1997 export value for oranges, lemons, and grapefruit ment of any organization in California to citrus genetics, was about $454 million (CALIFORNIA DEPT. OF FOOD breeding, physiology, and postharvest research. AND AGRICULTURE 2000). California enjoys a distinct advantage over other ECONOMIC VALUE OF CITRUS TO citrus-producing areas of the world in terms of being able CALIFORNIA to deliver fresh fruit to the market virtually every day of the year. This is by virtue of California’s diversity of THE COMMERCIAL PRODUCTION OF citrus in California mesoclimates, allowing a mix of citrus varieties to be has grown tremendously since the mid-1800s. Today, grown successfully in several distinct areas which are almost 275,000 acres are devoted to citrus, yielding scattered from the Sacramento Valley in the north to about 4.5 billion pounds of fruit annually. California ac- San Diego County in the south. counts for 82 percent of the lemons produced in the The five main areas of production are: 1) the United States and is second only to Florida in the pro- southern and central San Joaquin Valley, which encom- duction of other major citrus types which include the passes portions of Kern, Tulare, Fresno, and Madera oranges, grapefruits, mandarin, mandarin hybrids, and counties; 2) the coastal counties of San Diego, Orange, limes. In 1999, the most recent year for which compre- Ventura, Santa Barbara, and, to a lesser extent, San Luis hensive data are available, the gross on-farm value of Obispo and Monterey); 3) an inland area including California citrus was about $734 million (CALIFORNIA western Riverside and San Bernardino counties; 4) low AGRICULTURAL STATISTICS SERVICE 2000). elevation desert areas of Coachella, Palo Verde, and Im- The leading types of citrus produced in California perial Valleys; and 5) a relatively small northern Califor- are oranges, lemons, and grapefruit, but mandarins and nia area that includes parts of Butte, Glenn, and Yolo hybrids including tangelos and tangors are also gaining counties in the Sacramento Valley. in importance. Oranges and lemons ranked 14th and The combination of low humidity and varied cli- 22nd, respectively, in 1999 among California agricultural matic conditions enables growers in California to pro- commodities. Figures from 1999 put the gross on-farm duce citrus which is consistently good in terms of both value of navel and Valencia oranges combined at $416 eating quality and appearance. Accordingly, the crop is million, followed by lemons at $214 million, grapefruit grown primarily for fresh consumption, but excess fruit at $81 million, and mandarins and hybrids at about $23 or fruit not meeting fresh fruit standards is utilized for million. (CALIFORNIA AGRICULTURAL STATISTICS SER- juice and other processed products. VICE 2000). California is the sixth largest exporter of agricul- tural products in the world and citrus is a major con- tributor to that volume. Oranges, lemons, and grapefruit
Figure 2. Original Citrus Experiment Station staff on the steps of the Rubidoux Laboratory building ca. 1916. This was the first home of the Citrus Experiment Sta- tion. Front row from left: C.O. Smith, J.T. Barrett, L.D. Figure 1. December 23, 1914 headlines from the River- Batchelor, H.S. Reed, W.P. Kelley, and H.J. Webber; side Daily Press announcing that the expanded Citrus Back row from left: H.J. Quayle, E.E. Thomas, W.M. Experiment Station was awarded to Riverside, Califor- Mertz, H.B. Frost, H.S. Fawcett, W.D. Drew, and R.S. nia. Photo courtesy of Special Collections, Tomás Rivera Vaile. Photo courtesy of Special Collections, Tomás Library, University of California, Riverside. Rivera Library, University of California, Riverside.
4 polymorphism (RFLP) and random amplified polymor- phic DNA (RAPD) molecular markers shows that citrus accessions of hybrid origin can be identified, likely par- ents of hybrids can be identified, instances of gene intro- gression can be identified, and some differences between the Swingle and Tanaka systems can be resolved (FEDE- RICI et al. 1998). The motivation for studies on citrus species definition and relationships is not limited to un- derstanding phylogeny. Accurate knowledge about phy- logenetic relationships can guide searches of genetic resources collections for specific genes. An example is a Figure 3. A cultivation demonstration at Riverside, ca. recent successful search of citrus accessions for new 1917. The structures in the background are the main sources of resistance to the citrus tristeza virus (CTV) laboratory and south wing of the Citrus Experiment Sta- (MESTRE et al. 1997b) which causes one of the most tion building made possible by the expansion of the CES damaging diseases in citrus crops worldwide. to its new location authorized in 1914. Photo courtesy of Special Collections, Tomás Rivera Library, University of BIOLOGY OF CITRUS California, Riverside. CITRUS IS WIDELY CULTIVATED throughout the tropical, TAXONOMY OF CITRUS subtropical, and borderline subtropical-temperate cli- matic regions of the world, and is one of the world’s ma- FOR THE GENUS CITRUS, there are several taxonomic jor fruit crops. Most of the fruits commonly referred to as treatments defining and ordering the component species. citrus are classified in the genus Citrus. The genus Citrus The Swingle system (SWINGLE 1943, SWINGLE and and 32 related genera belong to the subfamily Auranti- REECE 1967) recognizes 16 species. There are also modi- oideae of the Rutaceae plant family. Diploid Citrus spe- fications which recognize varying numbers of species: 17 cies have 9 pairs of chromosomes (2x=2n=18) and there species (BHATTACHARYA and DUTTA 1956, STONE are some tetraploid (4x=2n=36) and triploid (3x=27) 1994), 36 species (HODGSON 1961), or 31 species accessions. (SINGH and NATH 1969). The Tanaka system recognizes Most citrus species are diploid, that is, they have up to 162 species (TANAKA 1977). It has also been sug- two genomes (sets of chromosomes), one genome inher- gested that there are only three valid species of culti- ited from each parent. In citrus a genome consists of vated citrus (C. medica, C. reticulata, and C. maxima) nine chromosomes, therefore a diploid species will have (SCORA 1975, BARRETT and RHODES 1976). 18 chromosomes. However, a low percentage of citrus The Swingle system is more widely accepted than seedlings are polyploid, that is, they have more than two the Tanaka system and will be used in this report. Ac- genomes. For example, a species with four genomes is cording to the Swingle system, the genus Citrus is di- referred to as tetraploid. Very few citrus cultivars are vided into the subgenera Papeda, with six species, and polyploid, but those that are have been exploited by Citrus, with 10 species. Subgenus Citrus includes the cul- plant breeders in attempts to produce seedless fruit. tivated types commonly referred to as citron, grapefruit When a tetraploid seed parent is crossed with a diploid (or pomelo), lemon, lime, mandarin, pummelo (or shad- pollen parent, the anticipated result is triploid progeny dock), sour orange, and sweet orange. (three genomes) which produce seedless fruit due to the The lack of agreement on a single taxonomic sys- lack of functional gametes. Seedless fruit is possible be- tem reflects the complexity of citrus-type species. Opin- cause a number of citrus types are parthenocarpic which ions differ as to what justifies species status and whether means they have the ability to produce fruit without pol- or not supposed hybrids among naturally occurring forms lination and/or seed development. Much of the informa- should be assigned species status. It also is a manifesta- tion about the genetics and crossing relationships in the tion of taxonomic treatments that must rely on morpho- genus Citrus is a result of knowledge accumulated over logical and biochemical characters (phenotype) without the 80 plus years that citrus breeding has been con- having data on the genetic relationships of the organ- ducted at UC Riverside. isms being classified. Features of citrus biology have pro- Nearly all cultivars within the orange, grapefruit, duced an array of actual and apparent genetic diversity. and lemon groups are believed to have originated either Molecular techniques that reveal the genetic relation- by selection of budsports, which are mutations that arise ships of genes and genotypes from one individual or type in single somatic cells in a branch, or by selection of nu- to another are providing the genetic evidence that will cellar seedlings (SOOST and ROOSE 1996). Nucellar enable the development of taxonomic systems that more seedlings are derived from somatic embryos which origi- clearly reflect phylogeny and evolutionary history. For nate from cell division in the ovary, outside the embryo example, a recent study using restriction fragment length sac (Figures 4 and 5). Since these nucellar embryos de-
5 velop asexually, with no male cells contributing to their trifoliate orange and kumquat are found in a line cross- formation, they are expected to be genetically identical ing south-central China in an east-west direction. More to the seed parent. This means that, despite having recently, GMITTER and HU (1990) have proposed that many named cultivars, there is relatively little genetic Yunnan, China, through which the Tanaka line runs, is diversity within the orange, grapefruit, and lemon itself a major center of origin for citrus. Some related groups. In contrast, in the mandarin, pummelo, and, to a Aurantioideae genera are native to Asia, Africa, and lesser extent, citron groups, many cultivars have arisen Australia. by sexual hybridization and levels of genetic diversity within these groups are much higher (ROOSE et al. DOMESTICATION OF CITRUS 1995). Table 1 summarizes our current understanding of the origin, mode of reproduction, and level of genetic THERE IS LITTLE EVIDENCE for the timing of the domesti- diversity within these commercially important taxa. Un- cation of citrus. Where ‘natural’ populations are located, der Swingle’s taxonomic system, some of these ‘species’ it is often difficult to determine whether they represent include cultivars derived from several different interspe- wild ancestors or are derived from naturalized forms of cific hybrids. Thus, the lemon group includes the culti- introduced varieties. Most authorities agree that citron, vated lemon in which most cultivars are derived from a mandarin, and pummelo are most similar to the ances- single ancestor by mutation, but many others within the tors of modern cultivated types. These species all repro- group are hybrids, possibly having at least one parent in duce sexually and if different cultivars within these spe- common with the cultivated lemon. These hybrids in- cies are hybridized, the progeny are relatively similar to clude rough lemon, Meyer lemon, the limettas, karna, their parents. The other important cultivated types, in- and others. In addition, there are many citrus species cluding orange, grapefruit, lemon, and lime, are believed that are more distantly related to the cultivated groups, to have originated by one or more generations of hybrid- and which represent additional genetic diversity. Such ization among these ancestral types (ROOSE et al. 1995). groups include C. ichangensis, other subgenus Papeda spe- The precise ancestry of these groups is not known. cies, and C. halimii. GENETIC DIVERSITY OF CITRUS ORIGIN AND DISTRIBUTION OF CITRUS ONE GOAL OF CONSERVATION is to capture and maintain CITRUS AND RELATED GENERA are native to southeast genes responsible for traits important for human use. Asia (northeastern India, southern China, and the The visible or tangible diversity in plants (phenotypic Indochinese peninsula). This is the center of diversity diversity) usually reflects underlying genetic diversity. and most probable area of origin for these species What may not be apparent, however, is the complexity (DAVIES and ALBRIGO 1994). TANAKA (1954) proposed of the genetics governing specific observable pheno- a theoretical line (the Tanaka line) which runs south- types. Highly diverse phenotypes may be closely related eastwardly from the northwest border of India, above genetically, with the divergence due to one or two criti- Burma, through the Yunnan province of China, to south cal gene differences. Phenotypic diversity is still the cri- of the island of Hainan. Citron, lemon, lime, sweet or- terion most often used to characterize genetic resource ange, sour orange, and pummelo originated south of this collections, however, molecular technologies to define, line, while mandarin, kumquat, and trifoliate orange determine, and monitor genetic diversity are rapidly be- originated north of the line. Mandarin apparently devel- ing adopted for citrus and other crops. oped along a line northeast of the Tanaka line, along the The most obvious traits for which phenotypic di- east China coast, through Taiwan, and to Japan, while versity is apparent in citrus and citrus relatives is fruit
Table 1. Summary of taxa in subgenus Citrus. Known age Seed Genetic Common name Species name (years) Probable origin reproduction diversity Citron C. medica 2300 nonhybrid sexual moderate Grapefruit C. paradisi 200 hybrid nucellar low Lemon C. limon 800 hybrid partly sexual moderate* Lime C. aurantifolia 700 hybrid partly sexual moderate* Mandarin C. reticulata unknown nonhybrid variable high Pummelo C. maxima unknown nonhybrid sexual high Sour orange C. aurantium 900 hybrid nucellar low Sweet orange C. sinensis 500 hybrid nucellar low *This extent of genetic diversity is due to combining different interspecific hybrids under a single species name.
6 size and morphology (Figure 6). For example, fruit ranges Diversity within citrus and citrus relatives can also in size from that of the pummelo which may be as large be illustrated by the differences in disease resistance as a person’s head and weigh many pounds to that of the among them. For example, mandarins are symptom-less Chinese box orange, Severinia buxifolia, which is as small carriers of CTV. In contrast, limes are so susceptible to as a pea and weighs only a fraction of an ounce. Most this virus that they are used as indicator plants for the fruits are either round, slightly flattened, or elongated in disease. Trifoliate orange is a source of genetic resistance shape, but those of the orange jessamine (Murraya pani- to CTV. culata) are oblong and small and those of the Australian In addition to the use of molecular techniques to finger lime (Microcitrus australasica, Figure 7) are very elucidate phylogeny as described above, several tech- long and banana shaped. niques have been successfully applied to citrus to deter- Although most trees of citrus and citrus relatives mine the genetic architecture of citrus genomes, evalu- are evergreen, the trifoliate orange, Poncirus trifoliata, ate the genetic basis for traits, determine the extent of sheds its leaves during the winter. There is tremendous genetic variability within and between citrus types, iden- variation in leaf size and shape among the species of the tify specific genotypes, and link phenotypic traits to mo- subfamily. Most types have a simple, single leaf which lecular markers. may be long and narrow, but others have compound It is important for plant breeding, genetic resource leaves with three or more leaflets. maintenance, and commercial production of crops to be Diversity is also apparent in the variety of uses of able to unequivocally identify important genotypes and citrus and citrus relatives by humans. The flesh of citrus to distinguish them from others that may be phenotypi- such as lemons, limes, oranges, and pummelos are com- cally similar. Molecular markers are useful for these pur- monly consumed as fresh fruit or juice, but the flesh of poses (ROOSE 1988, Figure 8). Inter-simple sequence re- citrons is very acidic and generally not consumed. How- peat markers were recently shown to distinguish among ever, the rind is commonly used to make candied citron several closely related citrus cultivars (FANG and ROOSE peel and fruitcake ‘fruit’. In contrast, the leaves of Citrus 1997). These markers, in conjunction with isozymes and hystrix (see inside front cover) are consumed as herbs for RFLPs, will provide the needed tools to ‘fingerprint’ cit- cooking in the Philippines and Thailand due to their rus accessions (FANG et al. 1997b), even closely related highly aromatic and volatile oils. Both the leaves and ones that differ by mutations in a few genes. DNA fin- flesh of the sour orange have numerous medicinal uses in gerprinting techniques are also proving to be valuable for Asia and South America. In Japan and China, immature defining and monitoring genetic diversity in the citrus and mature fruits of sour orange are common medicinals subfamily and in citrus genetic resource collections considered to regulate vital energy and remove phlegm. (HERRERO et al. 1996a,b, FANG et al. 1997b). In Haiti, sour orange leaves and fruits are also used in One example of the use of markers is the current food preparation, agriculture, construction, and voodoo understanding of the genetics of resistance to CTV in as well as for 10 different medicinals (PAUL and COX trifoliate orange, which was initially thought to be con- 1995). These are just a few of the many uses of citrus and trolled by a single dominant gene. Genetic linkage maps citrus relatives around the world. of the region surrounding the CTV resistance gene have been developed (GMITTER et al. 1996, FANG et al. 1998) and recent work with RAPD molecular markers indi- cates that at least one other gene is involved (MESTRE et
Figure 4. Microscopic cross-section of developing seed Figure 5. Germinating seeds revealing the multiple nu- revealing the multiple nucellar embryos contained cellar seedlings emerging from the seed at the left (poly- within (polyembryony). Photo credit: Joseph L. Kepiro. embryony). Photo credit: Joseph L. Kepiro.
7 al. 1997a). Molecular markers will enhance the use of low-acid pummelo accession (CRC #2240) was the par- these resistance genes in citrus rootstocks and cultivars ent of two early-maturing, triploid pummelo-grapefruit and may ultimately be used to clone and sequence genes. hybrids, ‘Oroblanco’ (1980) and ‘Melogold’ (1985), and Molecular markers were used to discover CTV resistance a hybrid pummelo ‘Chandler’ (1961). See SOOST and in Fortunella crassifolia which is much more closely re- ROOSE (1996) for a review of citrus breeding. lated to commercial citrus species than trifoliate orange Development of these low-acid varieties provides is, promising a route for gene transfer by sexual hybrid- an excellent example of the value of genetic resources ization (MESTRE et al. 1997b). Another example of a and their use in crop improvement. The low-acid pum- molecular marker involves a gene that controls fruit melo parent accumulates virtually no citric acid in juice acidity, a highly variable, commercially important phe- vesicles, and consequently has flavor that many consider notypic citrus trait. Three RAPD markers were found to ‘insipid’, although such fruit are prized in some cultures. be tightly linked to this gene and will allow early selec- Hybrids between the pummelo CRC #2240 and high- tion for this trait in citrus breeding programs (FANG et acid varieties such as grapefruit, orange, or pummelo al. 1997a). have intermediate acidity levels and early maturity. Thus, genetic resource accessions that have little com- UTILIZATION OF GENETIC RESOURCES IN mercial value can be valuable as parents in breeding new CALIFORNIA cultivars. Rootstock breeding was initiated in the 1950s at THE DEVELOPMENT OF NEW VARIETIES through breeding UC Riverside. Trifoliate orange has been the source of is the major direct use of citrus genetic resources. Breed- resistance to citrus nematode and Phytophthora root rot ing at the UC Citrus Research Center, Riverside was and gummosis (Figure 11). During the 1950s, CTV be- begun in 1914 by H.B. Frost (Figure 9). Of the several came widespread in southern California and killed mil- species and varieties used, ‘King’ mandarin proved to be lions of trees on sour orange rootstock. Hundreds of ac- an outstanding parent. Three King hybrids, ‘Kara’ (= cessions in the CVC were tested for their performance as ‘Owari’ Satsuma × King), ‘Kinnow’ (= King × ‘Willow- rootstocks for scions infected with CTV (Figure 12). leaf’), and ‘Wilking’(= King × Willowleaf) were intro- Many accessions with acceptable tolerance were identi- duced in 1935. These and other hybrids from the first series of crosses were used in further breeding. Beginning in the late 1940s crossing was expanded in three areas: 1) use of mandarin hybrids such as tangelos and tangors as parents, 2) crossing tetraploids with diploids to pro- duce triploids (which are seedless), and 3) crosses of pummelos with mandarins, grapefruit, and other pum- melos. Two mandarin hybrids, ‘Encore’ and ‘Pixie’, were introduced in 1965 and most recently, in 1999, the man- darin hybrid ‘Gold Nugget’ was released (Figure 10). A
Figure 6. The strikingly distinct fruits of Buddha’s hand citron (Fingered citron, Citrus medica, CRC #3768) is highly valued in Japan and China where it is used for Figure 7. Fruit and branch of Australian finger lime perfuming rooms and clothing and as an offering on al- (Microcitrus australasica, CRC #1484). The species is en- tars. The fruit is a horticultural curiosity due to its shape demic to the subtropical coastal region of eastern Aus- which resembles a human hand, lack of flesh, and fra- tralia and is used as ‘bushfood’. It has been investigated grant peel which can be candied for use in fruit cakes or for its contribution to rootstock breeding. Photo credit: J. as a garnish. Photo credit: Ottillia J. Bier. Rick Martin.
8 fied and some are used either as rootstocks or parents for Recent crosses for scion breeding involve various tetrap- rootstock breeding (Figures 13 and 14). These experi- loid mandarins, oranges, and grapefruit crossed with dip- ments also resulted in identification of ‘Flying Dragon’ loid mandarins and pummelos. There is a continued effort trifoliate orange (Figure 15) as a dwarfing rootstock for to develop early maturing cultivars with low fruit acidity citrus, another example of the value of a well-character- using the gene originally found in pummelo CRC #2240. ized genetic resources collection. Two citranges from the In the future, development of new cultivars will UCR breeding program, C32 and C35, were released for involve a wide range of techniques that will enhance our trial as rootstocks in 1986. Both have resistance to citrus ability to manipulate citrus genetic resources. The cre- nematode, Phytophthora, and CTV. C35 is currently ation of new hybrids by performing crosses and the selec- widely used in California because of its combination of tion of promising hybrids from these crosses will con- excellent disease resistance, moderate tree size, and high tinue to be used to create varieties with novel combina- productivity relative to tree size. tions of traits. The power of this method will be in- A smaller-scale citrus breeding program was devel- creased by marker-aided selection of hybrid seedlings oped starting in 1948 at the USDA Date and Citrus Sta- that are likely to have desirable traits. In this technique, tion in Indio, California. The objectives were the pro- hybrids are selected at the seedling stage based on their duction of high-quality mandarin types; an early matur- genotype for molecular markers that are inherited with ing, high-quality sweet orange; cold-hardy varieties; red desired genes. For example, DNA markers that allow grapefruit of improved color; a virus-free ‘Temple’ orange marker-aided selection for the low-acid gene have been type; and rootstocks with particular characteristics, such identified (FANG et al. 1997a). A high proportion of as tolerance to saline soils and Phytophthora root rot (FURR et al. 1963, FURR 1969). This program was sup- ported by a collection of over 200 accessions, the most valuable of which were incorporated into the CVC or other UCR plantings when the Indio station closed in 1982. This program lead to the release of ‘Fairchild’, ‘Fremont’, and ‘Fortune’ mandarins (FURR 1964), ‘Rein- king’ pummelo, ‘Schaub’ rough lemon, ‘African shad- dock × Rubidoux trifoliate’, and ‘Rangpur × Troyer’ rootstocks. Breeding new cultivars is an ongoing effort at UC Riverside in California and by researchers in Arizona and Florida. Many crosses are made using accessions within the CVC. In addition, field trials are presently being conducted on many rootstock and scion hybrids from the breeding program. Recent crosses for rootstock breeding include pummelo × trifoliate, taiwanica × trifo- liate, trifoliate orange selfed, crosses between trifoliate hybrids, and crosses between trifoliate hybrids and citrus.
Figure 8. Example of diversity at the molecular level: Each vertical lane contains DNA from a different germ- Figure 9. Howard B. Frost (l.), first citrus breeder at UC plasm accession. A short DNA sequence was amplified, Riverside (beginning in 1914) and Robert K. Soost, who hybridized with the DNA of these accessions, and visual- succeeded Frost as citrus breeder in 1949 and was a cura- ized by tagging with a fluorescent dye. The fragments of tor of the CVC from 1982 until 1986. Frost’s hybrid cit- different sizes that the dye reveals are the dark areas rus varieties and nucellar budlines revitalized the Cali- (bands) in the lanes. Among these accessions there are fornia citrus industry. Soost worked on nucellar embry- five different bands revealed by this analysis. Differences ony and citrus cytology and released several commer- in number and pattern of bands from lane to lane indi- cially successful citrus varieties. Photo courtesy of Spe- cate genetic diversity among the accessions. Photo credit: cial Collections, Tomás Rivera Library, University of Noelle A. Barkley. California, Riverside.
9 progeny having this gene can be identified without impossible by hybridization-selection methods because of growing the hybrids to fruiting, a long and costly process. the long generation time and high heterozygosity of Marker-aided selection is already used in citrus breeding most citrus. Each individual has two copies of each gene, programs and will become more important as markers one received from each parent. If both copies are the linked to additional genes are identified. It increases the same, the individual is said to be homozygous for that efficiency of breeding programs because those hybrids gene. If they are different, the individual is heterozygous grown into trees for evaluation can be preselected for for that gene. The greater the number of genes for which one or more desirable traits, increasing the likelihood an individual has differing copies, the more heterozygous that hybrids with commercially acceptable combinations that individual is. Many citrus cultivars are highly het- of traits will be identified. erozygous because they originated by interspecific hybri- The direct introduction of DNA (transformation) dization. Consequently, each parent contributes quite is also beginning to be used for citrus improvement different versions of many genes and few progeny from (GMITTER et al. 1992, BOND and ROOSE 1998). Specific such crosses are similar to their parents. Thus it is ex- genes can be added to existing cultivars using genetic tremely difficult to develop new orange varieties or correct engineering methods that are now established for some defects in existing ones by hybridization and selection. important citrus varieties. This technique can be used to Transformation increases the economic impor- correct defects in existing cultivars with minimal alter- tance of citrus genetic resources because it allows breed- ation of other characters, an objective that is difficult or ers to use genes from accessions that are difficult to use as parents because of sterility or cross incompatibility or because they contribute commercially undesirable traits to hybrids. A good example of the difficulties encoun- tered in such projects are attempts to develop cold-hardy citrus by hybridization with a cold-hardy relative, the
Figure 10. Fruit and branch of Gold Nugget mandarin orange (CRC #3913) released by M.L. Roose in 1999, resulting from work initiated by R.K. Soost and J.W. Cameron with a selection made in 1975. It is one of Figure 11. Trunk of root-stock showing damage from many successes of the Citrus Breeding Program at UCR Phytophthora infection: blistering and cracking of bark to which accessions maintained in the CVC have con- caused by damage in the active growing layer (cam- tributed. Photo credit: J. Rick Martin. bium). Photo credit: Ottillia J. Bier.
10 trifoliate orange. Breeders have been crossing trifoliate sources are in reality biological information passed down orange with citrus and selecting among the progeny to through generations in an unbroken chain (WILKES develop cold-hardy citrus varieties since about 1900. In 1988). Once this chain is broken that unique resource is 1988, the USDA program in Orlando, Florida released a lost forever. This has lead to the necessity of protecting backcross hybrid considered to have ‘moderate edibility’ and preserving plant genetic diversity for current and (BARRETT 1990). Additional generations will be re- future use. quired to achieve commercially acceptable fruit. If the The success of fruit and nut breeding programs in individual genes responsible for cold-hardiness can be the US has largely been due to the accessibility of a wide identified and cloned, it should be possible to transfer range of genetic resources. Since much of the world’s them to citrus cultivars. Other targets for transformation valuable fruit and nut genetic resources originated as are the genes for disease and insect resistance, salinity wild species outside the US, it is important that breeders tolerance, and many other important traits that exist in have access to these important resources through impor- citrus relatives, but cannot currently be exploited for tation and maintenance in collections. For California, cultivars by hybridization-selection methods. Research the optimum situation is to have the genetic resources by the UC Riverside citrus breeding program is under- accessible from collections maintained in the state. way to identify and clone a trifoliate orange gene for re- Readily available genetic resources have enhanced the sistance to CTV. progress of citrus breeding in California as described above. The CVC accessions have provided parents and IMPORTANCE OF CITRUS GENETIC sources of individual genes used in the breeding program. RESOURCES CONSERVATION The more well-characterized the accessions are, the more efficient it is to select parents for crosses. Projects THE GENETIC DIVERSITY OF PLANTS, developed by evo- such as investigating the phylogeny of citrus taxa lution, hybridization, and manipulation by humans, pro- (FEDERICI et al. 1998) could not have been done if the vides the basis for the food production which supports researchers had not had at hand the diversity of genetic the world’s population. This diversity is threatened by material maintained in the CVC. numerous complex factors including human encroach- ‘Wild’ citrus populations are relatively rare. Most ment on natural ecosystems and the shift to cultivation often wild citrus exists as scattered trees in remote areas, of a smaller number of advanced lines. Plant genetic re- as opposed to pure-stand populations. Citrus trees incur
Figure 12. Trunk with bark removed to reveal damage caused by the citrus Figure 13. Successful graft: the scion (up- tristeza virus (CTV): per part) is the desired fruit variety and the lower grooved the rootstock (lower part) is a genotype and scarred region is selected for specific disease or pest resis- Figure 14. An incompatible graft shown the damaged root- tance, environmental tolerance, or horti- with bark stripped away: the scion has stock. Photo credit: cultural characteristics. Photo credit: overgrown the rootstock at the graft junc- Ottillia J. Bier. Ottillia J. Bier. ture. Photo credit: Ottillia J. Bier.
11 mutations and many types hybridize readily. Some types CENTER FOR PLANT CONSERVATION 1991, NATIONAL reproduce true-to-type from seed due to nucellar embry- RESEARCH COUNCIL 1993). Similar losses have occurred ony. In addition, for thousands of years humans have in existing plant collections through inadequate mainte- selected lines with desirable characteristics and preser- nance. ved them by vegetative propagation. These factors have In the future, the need for maintenance of citrus led to the perpetuation of ‘elite’ lines, frequently at the genetic resources will become even greater because de- expense of the progenitor wild types. velopment and habitat loss in the tropical and subtropi- Aurantioideae genera other than the genus Citrus cal areas where citrus is native will continue to erode are utilized much less frequently and therefore exist most genetic diversity. Obtaining previously collected genetic often as wild, unselected types. These 32 genera, mostly resources from other countries is also becoming more tropical, are generally not sexually compatible with Cit- difficult as genetic resources are increasingly seen as rus and are of limited commercial importance. Conse- commodities that should only benefit the nation in quently, they have received little attention except from which they are native or be made available to other local inhabitants. It is in these genera, located in more countries at a price. remote areas, that the threat of loss of genetic diversity through habitat destruction is greatest. ACQUISITION OF CITRUS GENETIC It is generally conceded that there is much genetic RESOURCES erosion in both wild and cultivated members of the Aur- antioideae, but there are few hard facts available to illus- WHILE THE DIVERSITY OF CITRUS genetic resources al- trate this and in most cases there is no clear insight into ready maintained in California is great, there are several how much genetic variability has been lost and what the reasons that new material needs to be acquired. For ex- value of the lost materials may be. This lack of knowl- ample, specific genotypes (e.g., with disease resistance or edge should not preclude the collection and preservation environmental tolerances) or cultivars may not be pres- of threatened materials. ent in California and thus need to be imported. Ex- Preservation of the genetic diversity represented in change of materials with other collections outside of plant ecosystems throughout the world has become a California is one route that may produce new genetic major issue of international concern. The loss of increas- resources. Collection expeditions to sites of wild citrus ingly large numbers of plant species through habitat de- diversity is another. In general, new material may poten- struction threatens the availability of a diverse plant ge- tially be obtained from existing collections, from com- netic resource base which will be needed for future gen- mercial sources, or from wild or semi-wild populations. erations (HOLDEN and WILLIAMS 1984, RAVEN 1988, An important concern when moving genetic re- sources from one location to another is the potential of inadvertently introducing associated pathogens into a geographic area where they were originally absent. There are different amounts of risk associated with different sources of materials. There generally is less risk associ- ated with obtaining materials from an established collec- tion or certification program than from a commercial source or the wild. However, a number of scientific and ethical issues need to considered and addressed when plant exploration is to take place (BENNETT 1970, HAWKES 1980, NAMKOONG 1988, PLANT EXPLORATION OFFICE 1990, GUARINO et al. 1995, and HOAGLAND and ROSSMAN 1997). The USDA Animal and Plant Health Inspection Service (APHIS) is responsible for preventing pests from foreign sources from entering the US (USDA-APHIS 1977, 1988, 2000). The general guidelines and proce- dures for importing plant materials into the US are out- lined by PARLIMAN and WHITE (1985) and FOSTER (1988). Suggestions specific to citrus are detailed in KNORR (1977), ROISTACHER et al. (1977), FRISON and Figure 15. Hiryu (Flying Dragon trifoliate orange, TAHER 1991, and NAVARRO (1993). Poncirus trifoliata, CRC #3795) is a dwarfing rootstock in For citrus, the need for pathogen-free and/or tested citrus production and is a source of genetic resistance to propagative budwood has long been recognized as crucial citrus tristeza virus and other citrus pathogens. Photo to the establishment and maintenance of a viable citrus credit: Ottillia J. Bier. industry. Virus, viroid, and mycoplasma pathogens in
12 propagative budwood can be deleterious to tree survival be found in USDA-ARS (1968), ROISTACHER (1991, and fruit production. These pathogens can be easily dis- 1998), and IOCV (nd). The Rubidoux Quarantine Fa- tributed by infected plants, infected budwood, or vectors cility includes laboratory facilities and an insect-proof to areas free of them, where they become a potential greenhouse with temperature and light controls which hazard to existing and future plantings. Consequently, are required for biological indexing. This facility is lo- any new varieties introduced must be thoroughly tested cated in the city of Riverside but isolated from the near- for the presence of pests and pathogens before being re- est commercial orchards and the UCR experimental or- leased to the public. Because of these factors, citrus ma- chards by about three miles. terials are one of the most highly regulated plant materi- Typically, when a new import is received by CCPP, als in respect to international exchange, or even ex- four propagations are made of that budline on Rough change between different states. Lemon rootstock to preserve the budline and produce The introduction of new citrus varieties to Califor- budwood for future indexing and/or therapy. The re- nia is a cooperative venture involving federal, state, and maining portion of the import budline is used to graft county departments of agriculture and the University of inoculate indicator seedlings in a screening called the California. The CCPP has an import permits issued by pre-index, which will indicate if the import budline is APHIS and the California Dept. of Food and Agricul- infected with CTV, psorosis, or citrus viroids. A very ture (CDFA) which allow, with specific requirements, high percentage of new imports arrive infected with one the importation of citrus budwood. The Federal and or more of these diseases. State requirements are enforced by APHIS, CDFA, and If the pre-index shows that the newly introduced California County Agricultural Commissioners. variety is infected, it must be subjected to therapy proce- Foreign citrus material entering the US passes dures which can eliminate the disease or diseases from through Beltsville, Maryland and is inspected by APHIS the budline (ROISTACHER 1991, NAVARRO 1992). The for the presence of soil and pests. If clean, the material is CCPP employs two methods of therapy: thermal therapy sent on. Seeds may be sent directly to any requestor, and shoot-tip-micrografting. Thermal therapy (CALA- such as the UCR Citrus Breeding Program, CVC, or VAN et al. 1972, ROISTACHER 1977) involves subjecting NCGRCD, but all vegetative materials entering Califor- infected buds to high temperatures (40ºC) for several nia must be sent to CCPP and quarantined there before months. This has proven to eliminate some graft-trans- being released to the public. In the past, quarantining of missible diseases from an infected budline. Shoot-tip- citrus vegetative materials was done in Glenn Dale, micrografting (MURASHIGE et al. 1972, NAVARRO et al. Maryland, at the Plant Germplasm Quarantine Office, 1975, NAVARRO and JUAREZ 1977, NAVARRO 1981a,b) which was recently relocated to Beltsville. This facility is is a procedure in which several apical meristems from responsible for all plant introductions to the US, and is new growth tips are taken from an infected import plant overburdened with a large backlog of materials that require and grafted into a healthy seedling grown under aseptic testing and cleanup. Consequently, it has evolved over the conditions, and subsequently grown in vitro until it is years that almost all citrus vegetative materials entering large enough to graft onto a conventional rootstock the US are sent directly to CCPP for quarantining. seedling. If small enough when removed, the apical mer- The CCPP procedure for importation and distribu- istem does not contain the disease. This method has tion of disease-free propagative citrus materials starts proven superior to thermal therapy in eliminating some with a comprehensive indexing program to detect graft- pathogens, particularly the viroids. However, some transmissible diseases which may arrive in an imported pathogens are better eliminated by thermal therapy, so budline. Detection of graft-transmissible diseases of cit- often both techniques are used. rus is based primarily on biological indexing by grafting Following therapy, the material must again un- tissue from the import test source to specific citrus indi- dergo thorough indexing to determine the presence or cator seedlings. Specific indicator seedlings are used to absence of disease. If subsequent testing shows that dis- detect specific diseases and have been selected over the ease is still present, then the plant material must again years for sensitivity to disease and ability to express dis- be subjected to therapy. When a budline tests negative ease symptoms. In each index, adequate positive and in the pre-index or after therapy, it enters the Variety healthy control seedlings of each indicator variety are Introduction (VI) Index. All materials are indexed for held under the same environmental conditions as the cachexia, Citrus-associated viroids, citrus exocortis, test source seedlings, and are used for comparison with CTV, concave gum, greening, infectious variegation, the test source. Complementing this biological testing psorosis, stubborn, tatterleaf, and vein enation/woody are laboratory test techniques including: enzyme-linked gall. Depending upon the country of origin various other immuno-sorbant assay (ELISA) for the detection of diseases may be assigned. For instance, materials enter- CTV, sequential polyacrylamide gel electrophoresis for ing from Australia are also tested for blight. the detection of citrus viroids (exocortis/cachexia), and If a budline is shown to be free of known diseases culture in growth media for detection of stubborn dis- in the VI Index, it is considered to be ready for release ease. More detailed information on these procedures may from quarantine. CCPP will then apply for its release
13 from both state and federal quarantine. The CCPP must citrus seeds is still rare (MUMFORD and GROUT 1979), first obtain release from CDFA by outlining the testing however, progress has been made and preliminary guide- procedures and test results. Once released by the State of lines are forthcoming (C. VERTUCCI-WALTERS, 1995 California, an application for federal quarantine release personal communication). is sent to USDA-APHIS, containing a copy of the letter Trees such as citrus are considered to be ‘clonal’ of approval from the State of California for release from crops because they are usually propagated from vegeta- state quarantine. The distribution of citrus material re- tive tissues since individual trees are often highly het- leased from quarantine is also a highly regulated and erozygous and do not reproduce true-to-type from seeds. carefully executed procedure that involves close interac- Preservation of genetic resources of clonal crops presents tion between CDFA, CCPP, and citrus nurserymen. Af- a different set of challenges and techniques than does ter a variety is released from quarantine, it becomes preservation of seed crops (SAKAI 1984, 1995; TOWILL available to the commercial citrus industry or, in the 1988, 1989; TOWILL and ROOS 1989; BAJAJ 1995). case of citrus genetic resources, it becomes part of one or There are only a few reports of successful cryopreser- more of the three major collections of citrus genetic re- vation of embryonic axes (RADHAMANI and CHANDEL sources in California. 1992), embryos (MARÍN and DURÁN-VILA 1992, MARÍN et al. 1993), ovules (BAJAJ 1984), and cells (KOBAYASHI CONSERVATION OF CITRUS GENETIC et al. 1990, DURÁN-VILA 1995, SAKAI 1995). Pollen RESOURCES storage has been marginally successful in citrus (SAHAR and SPIEGEL-ROY 1980) but newer research (NIEDZ et al. IN GENERAL, PLANT GENETIC RESOURCES can be main- 1992) shows greater storage success using freeze-drying tained as living plants in nurseries (ex situ) or in their and cryostorage. DURÁN-VILA (1995) has reviewed natural habitat (in situ), as ex situ seed collections, or as cryopreservation of citrus genetic resources in general. ex situ collections of vegetative propagules or other tis- Cryopreservation has not yet proved to be a practical sues. The maintenance conditions for seed, vegetative conservation method for citrus. Trifoliate orange is likely propagules, and tissues vary greatly according to the biol- to be the first citrus genetic resource that will be success- ogy of the organism. Typically, seeds are kept at low tem- fully stored at cryogenic temperatures (L TOWILL, 1996 peratures with low humidity, although the use of cryo- personal communication). preservation for seed is increasing. Cryopreservation is The maintenance technique of choice for citrus becoming a viable option for maintenance of vegetative genetic resources continues to be ex situ plantings of liv- propagules and tissue cultures for many species. The ing trees in orchards or in more controlled environments choice of an appropriate method is guided by the biology such as greenhouses or screenhouses. Horticultural chal- of the species in question, the costs of the various viable lenges to this procedure include pest control, irrigation, techniques, and a consideration of the genetic changes fertilization, pruning, and appropriate repropagation. that can occur over time in a collection. These latter Field trees are necessary for evaluation purposes and as a include mutation, chromosomal aberrations, genetic seed source, but are subject to the vagaries of weather shifts, and genetic damage (ROOS 1988). The goal of and must be considered to be of unknown disease-status genetic resource maintenance is to minimize genetic unless rigorously tested at regular intervals. Trees main- change and maximize long-term viability. tained in greenhouses are more secure from an environ- While methods for the handling of citrus seeds in mental standpoint and may be more readily kept in a genebanks have been considered (ELLIS et al. 1985), tra- disease-free state, but are not suitable for evaluation and ditional seed storage techniques are seldom used. The must of necessity remain rather small in size. Mainte- extended preservation of citrus genetic resources as seed nance of a collection in a screenhouse represents a com- has certain genetic implications since the variable occur- promise between a field collection and a greenhouse col- rence of nucellar embryony among species precludes lection. Ideally, a citrus genetic resources collection general recommendations for seed preservation (FROST should include both a field planting, for evaluation pur- and SOOST 1968). Other problems with seed storage in- poses and as a seed source, and a protected block for the cluding loss of viability in low temperature have been production of virus-free budwood. reported (ROBERTS 1975). Successful cryopreservation of
14
CITRUS GENETIC RESOURCES IN CALIFORNIA
ONE OF THE LARGEST AND most diverse assemblages of USDA researchers soon after the establishment of the citrus genetic resources in the world is maintained in Citrus Experiment Station (CES) at the original site in California by a de facto conservation and utilization sys- Riverside on the slopes of Mount Rubidoux. In June of tem that involves the federal government, the state gov- 1917, Webber, the first director of the CES, guided the ernment, the University of California, and the Califor- installation of the Citrus Variety Collection on five acres nia citrus industry as represented by the Citrus Research of land adjacent to the new site of the CES in what is Board (CRB). The three primary components of this now the UC Riverside campus. The purposes of the system are the UC Citrus Variety Collection, the UC CVC are threefold: 1) to conserve and evaluate true- Citrus Clonal Protection Program, and the National ness-to-type of citrus and citrus relatives; 2) to provide a Clonal Germplasm Repository for Citrus and Dates. The resource of citrus genetic diversity for research; and 3) to federal government is represented by the USDA ARS extend knowledge about citrus diversity. research units and individual scientists who work with Over the 87 years since its founding, the collection citrus, the USDA NPGS which maintains repositories of has been supervised by 11 persons with some overlap in citrus (see below for details on the NCGRCD), the tenure between 1982 and 1995 (Table 2). From 1912 to USDA National Research Initiative which awards re- 1936, under the direction of Webber, budwood was freely search funds to competitive research proposals that have introduced into the collection from virtually all the cit- included citrus research, and the USDA APHIS office rus-growing regions of the world. Since 1910, when the which establishes and enforces US plant import and ex- collection began, it has included a total of approximately port regulations. The state government is represented by 4,000 citrus accessions. These field plantings were lo- the California Dept. of Food and Agriculture which en- cated adjacent to what is now UC Riverside. Initially forces for California the APHIS and California plant most of the accessions were propagated on sour orange material import regulations (see below for details on the rootstock. In 1951, under the direction of W.P. Bitters, CCPP), administers the citrus marketing order under the the collection was consolidated and repropagated onto California Marketing Act, and administers pathogen sweet orange rootstock due to the failure of certain geno- testing facilities. The University of California is repre- types on sour orange rootstock (Figure 16). These new sented by individual faculty scientists, the Division of trees, as well as all new accessions on sweet orange root- Agriculture and Natural Resources and the Agricultural stock added to the collection, were planted adjacent to Experiment Station, the UC Riverside CNAS and sev- eral member departments, the CVC and CEBs (see be- Table 2. Chronology of UCR Citrus Variety Collection low for details), and the UC Citrus Breeding Program. supervision. The CRB is the panel of growers and researchers who Curator Date Title establish research priorities and direct funds raised by a R. Smith 1909–1911 Superintendent of Whittier and Rubidoux Labs California marketing order on citrus production toward those priorities. The goal of the CRB is to enhance the E. Coit 1911–1912 Superintendent of Whittier and Rubidoux Labs production and marketing of highest quality citrus fruits H.J. Webber 1912–1936 Director of Citrus Experiment Station while being totally competitive in the domestic and in- L.D. Batchelor 1936–1946 Director of Citrus Experiment Station ternational marketplace. W.P. Bitters 1946–1982 Professor of Horticulture R.K. Soost 1982–1986 Professor of Genetics CITRUS VARIETY COLLECTION (CVC) E.M. Nauer 1982–1989 Specialist M.L. Roose 1986–1995 Professor of Genetics The CVC, curated by T.L. Kahn, is the oldest compo- nent of the de facto California citrus conservation and R.W. Scora 1986–1995 Professor of Botany utilization system. It was initiated in 1910 (SOOST et al. K.D. Bowman 1990–1992 Senior Museum Scientist 1977) by staff of the Citrus Experiment Station and T.L. Kahn 1995–present Senior Museum Scientist
15 the older trees. In the mid-1950s, WALLACE (1956) in- into their current locations in Fields 12A, 12B, 18A, and dexed certain trees in the CVC and found CTV present 18B. Additional land was allocated in these fields for in six trees (ROISTACHER 1981b). This presence of CTV expansion. Throughout the history of the CVC, new and a later indexing of 98 trees from the collection by accessions have been added to the collection and others C.N. Roistacher and E.C. Calavan in 1963 precipitated have been removed because they were very similar to the repropagation of the collection again in 1966 onto other types present. A few were lost due to tree death. CTV-resistant, appropriate rootstocks including Troyer At the time of Bitters retirement in 1982, the CVC con- citrange and Carrizo citrange (ROISTACHER 1981b). tained approximately 1,200 accessions. Since then some During the mid- to late-1960s, seedling yellows, a severe 400 accessions have been lost to attrition and selective isolate of CTV probably began to move within the CVC removal of apparent duplication. and into some of the field trees surrounding the CVC Currently, the CVC occupies 22.3 acres on the (ROISTACHER 1982). Annual inspections by Bitters of UCR campus, 2 acres at the UC South Coast Research all the trees in the CVC determined that the number of and Extension Center (SCREC) in Irvine, California, trees declining each year was increasing at an exponen- and 2 acres at the UC Riverside Coachella Valley Agri- tial rate even though they were on CTV-tolerant cultural Research Station (CVARS) in Thermal, Cali- rootstocks. This dramatic spread of seedling yellows be- fornia. The Citrus Variety Collection contains 865 ac- tween 1970 and 1980 was found to be due to a change in cessions (identified in Appendix) within the genus Cit- the transmissibility of CTV (ROISTACHER 1981a). rus and within 27 of the 33 related genera in the subfam- In 1981, with support of the UC Riverside CNAS, ily Aurantioideae of the Rutaceae. Approximately 670 of the CRB, and the State of California Employment De- the 865 accessions are within the subgenus Citrus and velopment Funds, a committee of UCR researchers ap- encompass virtually all of the commercially important pointed by the CNAS Dean initiated an intensive effort and historic citrus varieties of the world (Table 3 and to index all citrus trees at the Citrus Research Center Appendix). The majority (98%) of the accessions in the and remove those found positive for seedling yellows. CVC have been assigned PI numbers by the USDA The collection was again consolidated and repropagated, NPGS, either before or after inclusion in the CVC. About this time onto Carrizo citrange, C35, or another appro- 580 of the those accessions (68%) exist only in the CVC. priate rootstock. These new trees were planted in 1983 Thus, the CVC is a key resource for the NPGS.
CITRUS EVALUATION BLOCKS (CEBS)
THERE ARE THREE COLLECTIONS of commercially impor- tant citrus varieties maintained in California, currently under the direction of the curator of the CVC. These Citrus Evaluation Blocks (CEBs, also known as Demon- stration Blocks) are each collections of approximately 200 trees which include varieties that are also present in the CVC. One is located at the UC Lindcove Research and Extension Center (LREC), the second at SCREC, and the third at CVARS. The CEBs serve as demonstra- tion material for periodic field days that allow industry representatives to evaluate new varieties. In addition, along with the CVC, they serve as sources of fruit for research conducted by the CVC curator to evaluate fruit quality traits for trueness-to-type and commercial poten- tial and for fruit displays as part of CVC outreach activi- ties. Funding for fruit evaluations comes from annual grants from the CRB. These grant funds cover the cost of a Staff Research Associate position whose duties in- clude assistance with management of the CVC to the extent such activities are relevant to the objectives of both units. Figure 16. W.P. Bitters, curator of the Citrus Variety The CEBs are maintained by the staffs of their re- Collection from 1946 to 1982, holding Ponderosa lem- spective centers or station. The CEBs at LREC and ons (CRC #0294), ca. 1950. During his tenure, the CVC SCREC are projects subject to approval by the Research collection was greatly increased in number and diversity Advisory Committee for each center. Approved projects of accessions. Photo courtesy of Special Collections, are allocated specific numbers of hours of care by staff at Tomás Rivera Library, University of California, Riverside. that center.
16 CITRUS CLONAL PROTECTION PROGRAM use of infested budwood and mechanically on pruning (CCPP) tools. In 1937, a voluntary program to provide growers with a source of psorosis-free budwood produced under THE CCPP, DIRECTED BY D.J. Gumpf, has a two-fold CDFA regulations in cooperation with UC was initiated. mission: 1) it provides a safe mechanism for the intro- In 1939, quick decline (CTV), the devastating duction of citrus varieties from other citrus-growing ar- bud-transmitted infection, was discovered in California. eas of the world for research, variety improvement, or Spread by certain aphids as well as by humans, this dis- commercial production and 2) it provides the California ease wiped out millions of trees in the 1930s and 1940s. citrus industry and researchers with a collection of im- The danger of psorosis proved to be less than that of portant fruit and rootstock varieties which are tested and CTV (and stubborn disease), and use of the psorosis-free maintained free of bud-transmitted diseases. The history program declined. of the CCPP mirrors the development of our knowledge By the early 1950s, it had become increasingly of citrus virus and viroid diseases (NAUER et al. 1967, clear that many conclusions drawn from earlier citrus REUTHER et al. 1972, CALAVAN et al. 1978, REUTHER production experiments, especially rootstock trials and 1981, GUMPF et al. 1997, BASH 1999, KRUEGER 1999b, those involving orange scions, were not valid due to un- DUNLAP 2000). Before 1930, no viral diseases of citrus determined and random viral infections. Experimental had been identified. However, they existed and were plantings by J.W. Cameron and R.K. Soost of the Citrus common in citrus production areas in California and Experiment Station comparing nucellar strains and old around the world. These viral diseases caused decreases lines of commercial varieties generally showed that the in tree vigor, yields, and fruit quality. One of the most nucellar strains which were virus-free were superior in severe citrus virus diseases present in California was cit- vigor and yield. rus psorosis virus, which greatly reduced the profitability It was becoming abundantly clear that a reliable of citriculture. In 1932, H.S. Fawcett of the Citrus Experi- source of virus-free, true-to-type budwood would be of ment Station, the father of citrus pathology, showed that great value to both researchers and growers. This led the psorosis was due to a virus and could be transmitted by the Citrus Research Advisory Committee (a forerunner of today’s CRB, composed largely of prominent growers and nurserymen) to request in 1957 that UC assume primary Table 3. Type and number of accessions in the CVC. responsibility for developing and maintaining healthy Type Number citrus genetic resources, which were called ‘primary Mandarin 107 foundation blocks’ and to provide this material under Lemon, lemon-type 91 regulations promulgated by CDFA. This led to the establishment of the Citrus Variety Sweet orange and hybrid 75 Improvement Program (CVIP) in 1958. This was ini- Pummelo (shaddock) 62 tially a cooperative project between the UC Riverside Navel orange 48 Depts. of Plant Pathology and Horticulture. The project Trifoliate 48 leaders were initially Professors E.C. Calavan and W. Sour orange and hybrid 47 Reuther. The CVIP was renamed the Citrus Clonal Pro- Trifoliate hybrid 43 tection Program in 1977 to indicate its functions more Citron and hybrid 39 precisely and to make clear that the program is not con- cerned with variety testing and breeding, except to pro- Lime, lime-type 32 vide and maintain healthy plants. In 1979, Calavan re- Grapefruit 30 tired and was replaced by D.J. Gumpf. In 1992, the Dept. Citrus subgenus Papeda and hybrid 27 of Plant Pathology took over sole responsibility for Pummelo hybrid 25 CCPP (see website at http://www.ccpp.ucr.edu/ Tangelo 20 index.html). Valencia orange 18 The CCPP citrus collection, often referred to as the Lindcove Foundation Block, is a field planting of Blood orange 17 about 14.5 acres located at LREC in Tulare County in Kumquat and hybrid 17 the San Joaquin Valley of California. This block con- Tangor 14 tains over 1,000 trees of about 200 different scion and Rangpur type 11 rootstock varieties of commercial importance. In 1996, a Miscellaneous Citrus species 10 special CRB subcommittee charged with seeking a way Calamondin and hybrid 6 to protect CCPP budwood sources recommended that Grapefruit hybrid 6 the collection should be maintained in a screenhouse facility constructed to meet CDFA quarantine standards. Miscellaneous species, not genus Citrus 72 The facility was completed during the summer of 1998 Total accessions 865 (Figure 17). It is anticipated that the trees propagated for
17 the new screenhouse facility will be mature enough to genetic diversity within Citrus, the 32 related Auranti- start serving as a replacement for the Foundation Block oideae genera, and date palms and their relatives (Phoe- as the primary source of budwood in 2001. Newly im- nix species) and to do research which supports these ob- ported varieties are added to the collection each year jectives (WILLIAMS 1990, 1992a,b, KRUEGER 1999a). after having been released from quarantine and fruited. The NCGRCD is a part of the USDA NPGS and is a The trees are registered by the CDFA and are retested cooperative effort between USDA-ARS and the UC for the presence of diseases at regular intervals. Any trees Agricultural Experiment Station. testing positive are pulled from the block. Evaluations of The NPGS emerged in 1974 as an umbrella system the trees and fruit produced on the trees are also done which incorporated genetic resource-related activities regularly. which had previously been parts of a wide range of agen- The Lindcove Foundation Block is currently the cies within and outside of ARS. Components incorpo- primary source of budwood for the California citrus in- rated into the NPGS included New Crops Research dustry. Budwood from registered citrus trees in this col- Branch, the Regional Plant Introduction Stations, the lection is available for sale in limited quantities by UC Plant Introduction Office, and other entities. The NPGS in accordance with CDFA regulations for citrus registra- was established with the goal of collecting, evaluating, tion and certification. Potential purchasers are supplied maintaining, and preserving plant genetic resources with a list of available cultivars, order forms, cutting (SHANDS et al. 1988, WHITE et al. 1991, SHANDS 1995). date, and deadline for submitting orders. Budwood is cut Guidelines were developed for this system incorporating three times each year. Individual nurseries or growers ideas suggested by RAVEN (1976), NATIONAL RESEARCH may use the trees produced from buds to propagate addi- COUNCIL (1978), and others culminating in an opera- tional trees for 18 months (24 if the trees are re-tested tional program for the United States (SHANDS et al. 1988, during the first year). They may also register their own NATIONAL RESEARCH COUNCIL 1991, SHANDS 1995). trees and then use those trees to propagate additional The NCGRCD was established in 1987 on the trees from them in a similar manner if CDFA require- UCR campus (see website at http://www.ars-grin.gov/ ments are met. Any citrus trees for commercial sale in riv/). This location was chosen to take advantage of the California must be certified by CDFA as having met cer- resources available at the Citrus Experiment Station, tain requirements before sale. These regulations and the particularly the CCPP and the CVC. D.J. Gumpf of the CCPP have resulted in California having overall the CCPP was largely responsible for the conceptualization lowest disease incidence and highest fruit quality of any and specifications which resulted in the design of the citrus producing area in the world. facilities, and served as the University’s chief contact and liaison with ARS. The first NCGRCD curator was NATIONAL CLONAL GERMPLASM T.E. Williams, who served from 1987 through 1993. He REPOSITORY FOR CITRUS AND DATES was succeeded by R.R. Krueger in 1994. (NCGRCD) One of the NCGRCD’s primary purposes is to ex- change genetic resources with scientists all over the THE MISSION OF THE NCGRCD, directed by R.R. world. The stated mission of the NPGS is to facilitate Krueger, is to acquire, preserve, distribute, and evaluate and encourage the free exchange of genetic resources. Consequently, the NCGRCD distributes materials free of charge to qualified scientists, as do other units of the NPGS. Exchange of citrus genetic resources is highly regulated. Most citrus-producing countries have restric- tions on the introduction of new citrus materials to pre- vent the concurrent introduction of new pathogens or strains of pathogens. Most countries will accept only pathogen-free citrus budwood. Therefore, the NCGRCD maintains a screenhouse collection of over 700 virus-free trees which represent nearly 350 accessions. These are the primary source of budwood for distribution. Approxi- mately 55 accessions of citrus relatives are also maintained in greenhouse or screenhouse chambers (Figure 18). There are several ways that the NCGRCD obtains new virus-free genetic resources. The CCPP was desig- nated to be the primary vehicle for introduction and Figure 17. Budwood source trees for the Citrus Clonal quarantine of new accessions which are received as Protection Program in a screenhouse-protected planting clonal (vegetative) materials from sources outside Cali- at the Lindcove Research and Extension Center. Photo fornia. The NCGRCD also receives material directly as credit: David J. Gumpf. seed after inspection in Beltsville, Maryland. Material
18 received as seed is generally undeveloped or semi-wild INTERRELATIONSHIPS AMONG CVC, material, primarily citrus relatives, which usually come CEBS, CCPP, AND NCGRCD true-to-type from seed. Finally, to increase the genetic diversity of its virus-free collection, the NCGRCD is THE UNIQUE WORKING RELATIONSHIPS among the introducing accessions from the CVC into the screen- CVC, CCPP, CEBs, and NCGRCD have evolved to pro- house collection. This is done by an internal quarantine duce a comprehensive citrus genetic resource conserva- process similar to the one outlined above for the intro- tion and utilization system for the State of California. duction of foreign materials. This allows the acquisition Their individual goals are very closely interrelated but of noncommercial types which are difficult to obtain and are not duplicative. Figure 19 illustrates the flow of ge- have a low priority for processing by CCPP. NCGRCD netic resources into and out of the system and among has submitted applications to APHIS to be permitted as these four units and the UC Riverside Citrus Breeding a quarantine program. If approved, this would alleviate Program which maintains some accessions used for some of the pressure on the CCPP quarantine program breeding that are not in any of the other collections. and also increase the capacity to acquire new germplasm. New introductions that are to be incorporated into any NCGRCD collaborates and interacts formally and one of the collections and which are imported as bud- informally with CCPP, CVC, and other researchers on a wood must be introduced to the California system by regular basis. Collaborative projects have included horti- way of the CCPP to prevent the inadvertent introduc- cultural and molecular characterization of accessions in tion of pathogens or pests not found in California. CCPP the CVC, development of improved anti-serum for in- quarantines incoming clonal material and supplies bud- creased sensitivity of ELISA testing, and varietal trials. wood to the commercial industry in California. New cul- This continues a productive association between the tivars entering California that appear to have direct USDA and the Citrus Experiment Station that started commercial value are kept in the CCPP collection for with the activities of G.H. Powell and A.D. Shamel in evaluation and possible distribution. The same materials the early 1900s (LAWTON and WEATHERS 1989). may be added to the CVC and NCGRCD collections depending on their specific needs and requests. Materials that are solely for germplasm enhancement are not kept by the CCPP, but are moved directly after quarantine to the CVC and NCGRCD facilities for maintenance. The NCGRCD distributes clonal materials to the national and international citrus research community. The CVC, which maintains the largest number of accessions and the largest amount of genetic diversity, is used as a re- source for a myriad of research projects, extension activi- ties, evaluation and characterization of accessions, as well as a source of materials for indexing/clean-up and nonclonal materials, and serves as a backup to the virus- free collections. The CVC collection is a field planting exposed to natural infections of a number of diseases, notably CTV, which is pervasive in the area. Trees in the CVC are not registered by CDFA and so cannot serve as a budwood source for trees for commercial or experimental purposes or for national or international distribution. However, a permit was granted by the CDFA in 1996 to allow repro- pagation of citrus trees in the CVC that need to be re- tained in the collection from untested source trees in the CVC since many of the accessions present in the collec- tion are found nowhere else in North America. Seed and pollen from CVC accessions can be distributed to re- searchers outside of California and the US, since seed and pollen generally do not transmit diseases critical to citrus production. The CVC also has been a source for accessions maintained in the NCGRCD virus-free genetic resource Figure 18. Seedlings of indicator plants for indexing, collection. The CVC serves as a source of seeds, pollen, growing in cool-temperature chamber of NCGRCD flowers, etc. for distribution by NCGRCD and as a field greenhouse facilities. Photo credit: Polly M. Balance. planting for NCGRCD accession evaluation and charac-
19 Citrus clonal Citrus seed and pollen material from from outside California outside California and the US and the US
Imported into California directly to Imported into California directly to the the CCPP under US federal and CVC or the NCGRCD under US federal California regulations and California regulations.
Citrus Clonal Protection Program (CCPP) Movement of citrus UC Riverside genetic resources Citrus Breeding within California Program
Citrus Evaluation Blocks (CEBs) Citrus Variety National Clonal Germplasm Collection Repository for Citrus and (CVC) Dates (NCGRCD)
Citrus genetic resources move to California citrus nurseries as virus-free budwood from the CCPP and to national and international citrus researchers as virus-free budwood from the NCGRCD and as seed and pollen from the CVC and NCGRCD.
Commercial citrus National and nurseries international citrus researchers
California Consumers citrus growers
Figure 19. Movement of citrus genetic resources into, within, and out of the Californa system for conservation and utilization of citrus genetic resources.
20 terization activities. Materials obtained by the NCGRCD does not distribute directly to citrus growers except un- via exchange for incorporation into the virus-free collec- der unusual circumstances. The long-range goal of the tion need to be established in the field. Thus, both a vi- NCGRCD is increasing the number of disease-free ac- rus-free collection maintained under screen and a field cessions of unimproved, wild-type genetic resources, collection will continue to be necessary for NCGRCD in breeding lines, and other nonelite material that it main- the future. Through the NCGRCD, the CVC has con- tains, rather than concentrating on varieties of potential tributed to studies of cryopreservation of citrus seeds, commercial importance, leaving that to the CCPP. pollen, and vegetative tissue; citrus taxonomy and genet- The small size of the NCGRCD trees and limited ics; and blight-associated proteins. Thus, the CVC plays amount of screenhouse space also makes distribution of an important role in fulfilling the NCGRCD mission commercial quantities of budwood infeasible. The CCPP, and in contributing to citrus research world-wide. on the other hand, is a field planting of mature trees The NCGRCD screenhouse collection is a pro- which are capable of supplying commercial amounts of tected and tested collection that may serve directly as a budwood. The number of trees planted in the Founda- source for filling requests for budwood. NCGRCD dis- tion Block of the CCPP can also be increased readily if tributes materials to scientists, scientific organizations, demand increases. and governmental agencies throughout the world but
21 22
US CITRUS GENETIC RESOURCES OUTSIDE CALIFORNIA
WHILE CALIFORNIA IS HOME to the largest and most di- The USDA-ARS National Germplasm Reposi- verse collection of citrus genetic resources in the US, tory–Miami, located at the Subtropical Horticulture there are several other collections of interest outside of Research Laboratory, maintains a limited number of ac- California. None of the collections described below ap- cessions in the Aurantioideae. This collection is notable proach the CVC in size or breadth of genetic diversity, for the age and size of some of accessions of genera re- and none of them can supply virus-free budwood, as can lated to Citrus. There is also a small collection of Citrus CCPP and NCGRCD. Additionally, the majority of the and other Aurantioideae genetic resources maintained collections are more vulnerable to pests, diseases, and at the USDA-ARS Tropical Horticulture Laboratory in adverse weather conditions such as freezes and hurri- Mayagüez, Puerto Rico. Accessions maintained here are canes than are the California collections. not available as virus-free materials. The Florida State Dept. of Plant Industry main- Florida. The largest collection of citrus genetic resources tains the Florida Citrus Arboretum at Winterhaven. in Florida is the USDA-ARS A.H. Whitmore Founda- This is a well-maintained and attractive collection of tion Farm Variety Collection (WFFVC). The WFFVC is over 250 accessions, and includes a good representation administered by the USDA-ARS-USHRL. The collec- of citrus relatives. However, most accessions are repre- tion was started in the late 1950s by consolidation of sented by only one tree; virus-free materials are not avail- several other USDA collections (primarily in Florida, able; and the area is vulnerable to freezes and hurricanes. but also including Indio, California) to support citrus Breeding collections are maintained by the citrus breeding programs at USHRL. The WFFVC, on its breeders at the University of Florida Citrus Research Groveland, Florida site, served as a field facility for and Education Center in Lake Alfred. These collections USHRL breeders before being incorporated into the contain some unique and valuable accessions such as NPGS in 1987 as a repository. It was decommissioned in recently described introduced species and polyploid ac- 1992 and reverted to its previous status of a breeding col- cessions. However these collections are not generally lection. There were approximately 250 accessions main- accessible, cannot supply virus-free material, and are not tained at the WFFVC Groveland site, about half of always available for distribution or exchange. There is which are not duplicated in any California collection. also a small collection of Citrus and other Aurantioi- Yet the WFFVC has few representatives of genera re- deae genetic resources maintained without regard to lated to Citrus and virus-free materials are unavailable. virus status at the University of Florida Tropical Re- The USHRL moved from Orlando to Fort Pierce, search and Education Center in Homestead. Florida in 1999. Accessions of the WFFVC testing nega- tive or having only mild strains of CTV will be Texas. The Texas A&M University, Kingsville Citrus repropagated at Fort Pierce, but accessions testing posi- Center (TAMUK) at Weslaco has a collection of over tive for severe strains of CTV will not be. There are no 200 accessions. Some of these accessions are not present plans for virus elimination via thermal therapy or shoot- in California, but overall this collection does not have tip grafting at this point. Therefore, virus-free materials the diversity present in California. There are few citrus will still not be available from this collection. The Fort relatives in this collection. Pierce WFFVC collection is thus initially smaller than The Rio Farms Citrus Variety Collection is lo- the original Groveland WFFVC collection, but addi- cated approximately 10 miles from Weslaco in Monte tional accessions will be added over time. The Fort Alto. This collection was originally established by the Pierce site should be less subject to destructive freezes USDA in the 1960s and was taken over by Rio Farms, a than the original Groveland site, but it is also subject to private organization, when the USDA discontinued cit- many endemic citrus diseases that may threaten the rus research in Texas in the 1970s. There are over 100 phytosanitory status of many accessions. accessions in the Rio Farms collection, some of which are not present in the California collections. This col-
23 lection has suffered more than the TAMUK collection of the more valuable accessions are in the process of be- from freezes, and was recently damaged by gummosis. ing incorporated into the CVC, CCPP, and NCGRCD Rio Farms is less interested in citrus production than in collections. the past, and this collection will probably be lost. Some
24
INTERNATIONAL CITRUS GENETIC RESOURCES
THE CENTER OF ORIGIN and diversity of citrus is in In the southern and southeastern Asian countries southeast Asia. Consequently, this is where the greatest to which Citrus and related genera are indigenous, devel- amount and diversity of citrus genetic resources may be opment and consequent habitat loss is occurring due to expected to be found, particularly in situ (REUTHER deforestation, population pressure, fire, and hydroelec- 1977, IBPGR 1982). Assessment of the genetic vulner- tric, agricultural, and other development pressures. Hab- ability of any species requires knowledge of the extent itat loss results in a loss of genetic diversity. Efforts are and distribution of genetic diversity. Unfortunately, in- being made at habitat preservation in these areas, how- formation on natural and semi-natural citrus genetic re- ever, ex situ preservation of genetic resources has become sources is limited. The information that is available is imperative due to the rapidity of habitat loss. Ex situ col- often simply a catalog of plants present in an area, with lections also make genetic resources more readily avail- little more than names and phenotypic descriptions. Of- able to users and facilitate characterization and evalua- ten even information on the frequency of occurrence is tion. What follows are brief descriptions of the status of lacking. More detailed characterization and evaluation in situ and ex situ collections of citrus and citrus relatives data are needed to assess adequately the actual amount in selected countries and regions. of genetic diversity present. These data should include both descriptive information and molecular level genetic China. Southern China is one of the centers of diversity analyses. for Citrus and related genera, and a wide range of genetic The report, The State of the World’s Plant Ge- diversity is apparently still present in situ (GMITTER and netic Resources for Food and Agriculture (accessible at HU 1990, ZHENG 1995, DENG et al. 1997, CHEN 1997). http://web.icppgr.fao.org/wrlmap_e.htm), was pre- However, some, although not all, areas are threatened pared for the International Technical Conferences on with habitat degradation or lack of proper management Plant Genetic Resources in Leipzig Germany in 1996. In that could result in decreases in genetic diversity. Chi- this report the number of citrus accessions worldwide nese governmental surveys during the 1970s uncovered a were listed at 6,000 which included a mixture of wild number of putative new species, including C. honghensis, species, old cultivars, and advanced cultivars and breed- C. mangshanensis, C. daoxianensis, and Poncirus polyan- ing lines. In an effort to better understand the nature of dra. These putative species are mostly unknown outside these collections and promote conservation of citrus and of China and some may be endemic. There is use of in- related genera, a global network on citrus genetic re- digenous genetic resources in China, and some attempts sources conservation and utilization was formally consti- at in situ preservation have been made. However, conser- tuted under the aegis of the FAO in 1997. The Global vation of citrus genetic resources in China consists Citrus Germplasm Network (GCGN) will function on a mostly of ex situ collections at present. Beginning in the voluntary basis and will involve national institutions early 1960s, a National Citrus Germplasm Repository and existing regional and inter-regional citrus networks. was established at Chongqing, Sichuan province, and The purpose of the network is to link different initiatives regional citrus genetic resources repositories were estab- in different parts of the world that deal with genetic re- lished in Huangyan, Zhejiang province; Guiling, Guang- sources exploration, conservation, and utilization. The xi province; Zhangsa, Hunan province; and Guangzhou, GCGN is chaired by a General Coordinator and guided Guangdong province. As of 1996, the National Citrus by Coordinating Board. Within the GCGN four working Germplasm Repository had 1,041 accessions, while the groups were defined to conduct the scientific and techni- Huangyan, Guiling, Zhangsa, and Guangzhou regional cal work of the global network focused on genetic re- repositories had 128, 216, 40, and 140 accessions, respec- source characterization; establishment of a global com- tively. These current numbers represent substantial re- puterized citrus genetic resource information system; ductions in accessions since the repositories were estab- conservation strategies; and utilization of citrus genetic lished. The reductions were due to such factors as lack of resources. funds, disease, and freezing weather. The exact contents
25 of these collections is unknown, but a high percentage is Although not as large as some collections, these South- indigenous, and undoubtedly represents a substantial east Asian collections have notable genetic diversity, amount of diversity not present in collections elsewhere particularly in the pummelos and some of the related in the world. Some of the accessions, indigenous and non-Citrus genera, and appear to be fairly well main- otherwise, consist of advanced lines or selections. The tained and curated. collections in the repositories have had received only a Asia’s largest collections, outside of the centers of limited amount of characterization and evaluation. origin discussed above, are in Japan (OMURA 1997). Cit- rus entered Japan in ancient times and some types be- India. Northeast India is a center of origin and diversity came semi-naturalized. The federal Fruit Tree Research for Citrus and related genera. Genetic diversity of indig- Station in Tsukuba has a large collection maintaining a enous Citrus species in this region is gradually eroding number of citrus relatives. This station has been active (RAI et al. 1997) and the area is experiencing civil un- in collecting in Nepal (1983–1985) and Vietnam (1996) rest, making evaluation of genetic diversity and plant in IPGRI-coordinated cooperative programs. Accessions exploration difficult. There are apparently a few stands collected from these ventures are maintained in Japan. of wild citrus in these areas, but many of the wild popu- The accessions at Tsukuba and in various other, smaller lations consist of dooryard plantings. A long history of collections total approximately 1,200 (OMURA 1997). cultivation and selection have produced many genotypes and landraces, which are difficult to distinguish from Australia. Indigenous citrus relatives include taxa in the wild citrus populations. Still, a wide range of genetic di- genera Eremocitrus and Microcitrus, for which Australia is versity undoubtedly exists in these areas (SINGH 1981, the center of origin. These taxa probably served as ab- CHADHA 1995, SINGH and UMA 1995, RAI et al. 1997). original foods. Organized ex situ citrus genetic resource There is an in situ gene sanctuary for citrus in the Garo maintenance and utilization is conducted today by state Hills in the northeast of the state of Assam, which is a government departments of agriculture and primary in- field genebank with 627 accessions (SINGH 1981). Other dustries, the federal Commonwealth Scientific and In- regions of diversity include the central and northwest dustrial Research Organization (CSIRO), and various Himalayas, Maharashtra, and the southern peninsula. Ex arboreta, botanical gardens, and university plant collec- situ conservation of citrus genetic resources began in the tions (SYKES 1997). In total, these collections include 1950s in India, but the number of accessions maintained about 500 accessions and are rich in diversity of culti- has declined due to lack of maintenance and disease. Ex vated types. Most accessions are backed up by duplica- situ collections consist of 451 or 521 accessions (depend- tion in different sites. Acquisition of new material by ing on the source of the estimate) at eight sites (Chetal- budwood is limited due to quarantine concerns, but seed li, Bangalore, Rahuri, Tirupati, Abohar, Bhatinda, Yer- importation and subsequent characterization and evalua- caud, and Delhi). The ex situ collections in India are tion of Citrus relatives from other Southeast Asian coun- mostly of rootstock varieties and a few local cultivars, tries and materials with rootstock potential has been an with not much diversity represented. There is a plan to ongoing activity, especially of CSIRO as part of a pro- concentrate the various collections at the National Re- gram of genetic resources enhancement. search Centre for Citrus in Nagpur. However, as of Janu- ary 1996, there were only a small number of accessions Elsewhere. Outside of the centers of origin and diversity, planted at Nagpur. collections consist mostly of advanced lines and com- mercial varieties in countries with citrus production and Other Southeast Asian countries. The area is rich in citrus breeding programs. ROUSE (1988) and BETTEN- indigenous Aurantioideae genetic resources, with chance COURT et al. (1992) have summarized the world citrus seedlings, semi-wild, and wild types. There are three col- collection situation identifying major and minor ex situ lections in Malaysia (JONES 1991, SAAMIN and KO citrus collections. Large ex situ collections of citrus are 1996), the main one being the Malaysia Botanical Gar- found in Argentina, Brazil, Corsica, Morocco, New Zea- den (over 100 accessions), three in Indonesia (498 ac- land, South Africa, Spain, and Turkey. Although the cessions), three in Thailand (585 accessions), and two in number of accessions reported for some of these collec- the Philippines (107 accessions). There are also some in tions exceeds the number maintained by the CVC in situ conservation efforts. In the period 1983 to 1988, the California, the amount of genetic diversity present is International Plant Genetic Resources Institute (IPGRI, generally less than in the CVC. For example, some of then the International Board for Plant Genetic Resourc- the larger collections contain many selections of the es) coordinated four collecting missions to Thailand, same variety, and so the genetic diversity is less than Malaysia, Indonesia, and Brunei resulting in the addition might be expected from the number of accessions. Rep- of 391 new accessions (these are maintained in Japan, resentatives of genera related to Citrus are particularly the organizer of the missions). In 1986, IPGRI invited lacking in most of these collections. On the other hand, Malaysia to accept responsibility for maintaining a field some of the smaller collections worldwide may not offer collection of Southeast Asian species of Aurantioideae. a large number of varieties or much diversity, but may be
26 important for indigenous local variation in Citrus or for tended for the preservation of diverse species encompass- endemic species. For instance, BETTENCOURT et al. ing the genus Citrus as well as related genera exist in (1992) list Cameroon as having some indigenous only a few places in the world besides the CVC. Most Citropsis species in their collection. collections in other countries consist of field plantings, These collections vary as to the purposes they and, with a few notable exceptions, virus-free budwood serve. Most of the collections are located in countries is not available. The Citrus Germplasm Bank, Instituto where citrus is not native, so they serve a multiplicity of Valenciano de Investigaciones Agrarias in Valencia, functions including limited genetic resources mainte- Spain is one of those exceptions and virus-free material nance for crop enhancement and breeding and as is available. Spain’s quarantine and certification pro- mother trees for the production of trees for a commercial grams are among the world’s best and most respected fruit industry. Large genetic resources collections in- (NAVARRO et al. 1988).
27 28
ANALYSIS AND RECOMMENDATIONS IN SUPPORT OF CITRUS GENETIC RESOURCES IN CALIFORNIA
THE CALIFORNIA CITRUS GENETIC Recommendation 1. No changes in the management struc- RESOURCES CONSERVATION AND ture of the CVC, the CCPP, or the NCGRCD are advo- UTILIZATION SYSTEM cated. The continued close collaboration among the three units is essential to the functioning of a citrus genetic re- THE THREE PRIMARY COMPONENTS of the California sys- sources conservation and utilization system for California. tem for maintaining and providing citrus genetic resour- Recommendation 2. The establishment of a California ces are the UC Citrus Variety Collection (CVC), the Citrus Genetic Resources Advisory Committee UC Citrus Clonal Protection Program (CCPP), and the (CACGRAC) is recommended. This committee, composed National Clonal Germplasm Repository for Citrus and of research and extension workers, agency and University Dates (NCGRCD). Each unit has a different history and administrators, growers, processors, marketers, consumers, origin and the interrelationships among them have been and others, will provide guidance to the staffs of the units that ad hoc. However, this situation has been functioning comprise the California citrus genetic resources conservation well in service to the California citrus industry and citrus and utilization system to assure the acquisition of critical ge- researchers providing one of the largest and most diverse netic resources and their long-term conservation and efficient assemblages of citrus genetic resources in the world. distribution. Each of these three components has distinctly dif- ferent organizational and administrative structures. The Recommendation 3. The dependence of the NCGRCD on CCPP is managed within the Department of Plant Pa- the CVC for seed and field evaluation facilities should be offi- thology, while the CVC is managed within the Depart- cially recognized by the parent organization of each unit and ment of Botany and Plant Sciences, both within College enhanced by a long-term commitment of support for the of Natural and Agricultural Sciences, UC Riverside. The CVC by the USDA NPGS. NCGRCD is managed for the NPGS by ARS staff re- Recommendation 4. Citrus genetic resource management porting to the Pacific West Area office in Albany, Cali- for California should expand to include resources such as fornia. Each unit may also have responsibilities in addi- DNA libraries, probes, and clones. The appropriate unit and tion to the focus on genetic resources for California. For adequate funding for the effort should be topics for consider- example, academic priorities may redirect staff activities ation by the proposed California Citrus Genetic Resources for the two UC units. For the NCGRCD, its role in the Advisory Committee. (Rec. 2 above). NPGS gives it national responsibilities and its mission also includes another crop entirely—dates (Phoenix spp.). While this document focuses primarily on live tree THE CITRUS VARIETY COLLECTION conservation, it is becoming increasingly apparent that Activities citrus genetic resource management will need to expand to include such resources as DNA libraries (both cDNA Acquisition. With no budget directed to this activity, and genomic DNA libraries), molecular probes, and the addition of new accessions into the CVC is slow, de- clones. It is not clear what unit in the California citrus pending upon research collaborations and serendipity. genetic resources system should initiate such collections, There is recognition that acquisition should be a con- but concern for such material is put forward here as a tinuing activity, but there is no strategy in place for recommendation. evaluating the collection for underrepresented taxa, The remainder of this chapter consists of an analy- genotypes, or geographic origins and actively seeking out sis for the CVC of the operational aspects of a genetic acquisitions. Even with some new accessions, the collec- resources operation and recommendations to enhance tion has grown smaller overall since its peak size of some and facilitate the continued success of the CVC in con- 1,200 accessions in the early 1980s. This was primarily serving citrus genetic resources for California. due to attrition loss and selective removal of duplicates.
29 Recommendation 5. There should be continued and en- phasized and pesticide usage kept to a minimum is a hanced linkages with other national and international citrus long-term goal for the CVC, but progress is slow with genetic resources collections. available funding. Care for the trees in the 22.3 acre portion of the Recommendation 6. Acquisition of new accessions, both CVC located at UCR is done by UCR Agricultural Op- from within and outside California and of wild or naturally erations personnel. The Agricultural Operations office occurring citrus relatives from their native habitats, is an im- estimated the annual costs of its services for the CVC at portant function for the CVC. Acquisitions should be guided about $24,000. In addition during 1997–98, the staff of by a plan developed with assistance of the recommended advi- the CVC obtained voluntary assistance from the River- sory committee. Every effort should be made to acquire ac- side County UC Cooperative Extension Master Garden- cessions for the CVC that are not currently available in Cali- ers in fruit reduction and pruning in the CVC. The esti- fornia, taking full advantage of the California system that mated annual costs for these services without volunteer allows importation of citrus genetic resources. assistance are $2,000 for pruning and $7,000 for fruit reduction. Documentation and database management. Each acces- Care for the three CEBs and the collection of cit- sion in the CVC generates data beginning with the pass- rus relatives at SCREC is conducted by the staff at the port data from the acquisition stage and ultimately in- respective location. The number of hours needed to cluding evaluation and characterization data accumu- maintain the trees and funds for their care at LREC and lated as the accession is utilized. Maps and records of the SCREC are allocated by the Reseach Advisory Commit- varieties present in the CEBs are maintained separately tees for each center. If the amount of care needed ex- from those of the accessions in the CVC. Prior to 1996, ceeds the amount of funds allocated, the excess cost is records for the CVC were kept solely on 4 × 6-inch charged to the CVC budget and funded projects associ- cards. This procedure, maintaining a card for each acces- ated with the CEBs. sion, had been followed since the inception of the col- lection. In 1996, the information was transferred to a Rootstock status. When an accession is represented by computer database which permits easy updating of infor- two trees (which is the case with most of the 865 acces- mation and manipulation of the data for record keeping sions), two different rootstocks are used: one instance of (see Appendix). From 1996 to 1998, the CVC received the accession would be on Carrizo citrange and the other funding to update and expand its database and to de- would be on C-35 citrange or another appropriate root- velop links between the CVC and other databases in- stock. creasing its usefulness to a wider range of researchers and other interested parties. CVC accessions are also entered Irrigation. All trees in the CVC will be on a low volume in the USDA Genetic Resources Information Network micro-sprinkler irrigation system such as is used by most (GRIN) database (http://www.ars-grin.gov). commercial citrus operations in California. Although furrow irrigation provides adequate water (Figure 20), a Recommendation 7. The CVC database should be en- low-volume irrigation system offers many advantages: it hanced to include digital representations of important acces- can save water and labor and allows fertilizers to be in- sion characteristics such as photographs of flower, leaf, and jected into the irrigation water when needed (STATE- fruit morphology, gels of biochemical and molecular genetic WIDE INTEGRATED PEST MANAGEMENT PROJECT 1991). analyses, and disease susceptibility or resistance symptoms. During 1998, one-third of the trees were converted to such a system with financial support ($1,000) from CVC Recommendation 8. There should be continued exchange funds in combination with a donation of available irriga- of information between the CVC and the USDA NPGS tion supplies and 285 hours of labor from UCR Agricul- GRIN databases. tural Operations. The remaining two-thirds of the trees are being converted with funds from a one-year grant Maintenance. The CVC maintains at least two trees per awarded in 2000 from the California Citrus Nursery Ad- accession for each of the 865 accessions currently in the visory Board. collection. The cultural practices required for the trees include: irrigation, fertilizer applications, pest control, Recommendation 9. Full implementation of integrated pest weed control, pruning, fruit reduction, tree care, and management techniques should be deployed in the CVC frost control. Minimizing pesticide use in the collection plantings which, along with the full installation of the low- orchards is essential for a collection that is often used by volume irrigation system, would not only increase the effi- researchers and visitors who may consume fruit samples ciency of tree cultivation in the CVC, but would also en- as a means of evaluating new and commercial cultivars hance the unit as a showcase for California citrus. in the collection. Full implementation of integrated pest management techniques by which release and mainte- nance of beneficial insects and predatory snails is em-
30 Recommendation 10. The CVC needs to monitor informa- representatives in advance of crisis-driven needs. Infor- tion about citrus pathogens and keep in contact with citrus mation for such characteristics is available in the litera- specialists to anticipate disease threats to the collection. ture for some of the CVC accessions, but further confir- mation and characterization is increasingly necessary as Evaluation, characterization, and research. Evaluation the range of techniques available to manipulate citrus and characterization of CVC accessions is driven by ob- genetic resources increases. jectives of externally funded research projects, often cri- The CVC serves as a resource for a myriad of re- sis driven. For example, evaluation of a portion of the search projects from scion and rootstock breeding for the accessions for resistance to a specific disease could only improvement of commercial varieties to the study of the be accomplished in conjunction with a funded project to biological activities of citrus limonoids as anticancer work on that characteristic. Several of the research agents. Since 1997, 38 different projects have used CVC projects described below are of this nature. Ideally, main- materials, conducted by researchers at UC Riverside, tenance of a field collection needs to be coupled with University of Arizona, Auburn University, University of periodic evaluations of accessions for trueness-to-type Florida, and USDA (Table 4). These projects covered a and characterizations for traits of value to researchers range of topics: eight focused on scion and rootstock and the citrus industry. Information on traits such as dis- breeding; 11 involved characterization of accessions for ease resistance/susceptibility, monoembryonic or polyem- commercially important traits such as disease resistance/ bryonic seed production, pollen viability, self-compat- susceptibility and anticarcinogenic activity of citrus ibility, cross-incompatibility relationships, and root- limonoids; eight focused on isolating, mapping, and stock-scion incompatibilities would be valuable for re- transferring specific genes; four investigated the phylog- searchers, citrus growers, nurserymen and other industry eny and genetic diversity of citrus and citrus relatives; two focused on cryopreservation; and five others in- volved research on pathogens of citrus, stress reactions, or biochemistry of citrus extracts. The CVC staff directly conducts research: two projects utilize accessions in the CVC and the CEBs and the third is a mandarin variety trial for the California desert, being conducted at CVARS.
Recommendation 11. Users of the CVC should be encour- aged to contribute to the maintenance of its collections.
Dissemination of information. The CVC is used exten- sively as a resource for educational extension activities on the UC Riverside campus. California citrus growers, nurserymen, and other industry representatives as well as students from University of California and California State University campuses visit the CVC each year to evaluate potential commercial citrus varieties and learn about citrus diversity. Many visitors from other states and countries also tour the CVC since it is internation- ally renowned for citrus diversity. In addition to tours of the CVC, since 1995, the staff has provided numerous fruit displays and oral presentations to disseminate infor- mation on the performance of various citrus cultivars and on citrus diversity. From March 1999 to March 2000, the staff con- ducted twenty-five off-campus presentations including four oral presentations to growers groups sponsored by the Citrus Research Board, fruit displays for the Sunkist Annual Meeting, the Tulare Farm Equipment Show, and the for members of the US Congress and their aides in Washington DC, field days at the three evaluation Figure 20. Headstand of furrow irrigation system once blocks, and poster presentations at the Orange Show and used at the CVC, now replaced by the more efficient low a two-day citrus diversity fruit display and poster session volume micro-sprinkler irrigation system, typical of most at the Riverside Orange Blossom Festival where over commercial citrus operations. Photo credit: Michael J. 150,000 visitors to the Festival had the opportunity to Elderman. ask questions about and taste 30 different types of citrus
31 Table 4. Research projects utilizing accessions in the CVC (1997–2001).
Project description Investigator Institution/Department Citrus variety evaluation for trueness-to-type and commercial potential. T.L. Kahn, M.L. Roose UCR Botany & Plant Sciences Preliminary evaluation of parthenocarpy of new Clementine mandarin selections. T.L. Kahn UCR Botany & Plant Sciences Evaluation of new citrus selections–Sensory evaluation. T.L. Kahn, M.L. Arpaia UCR Botany & Plant Sciences Characterization of lime accessions T.L. Kahn, M. Harris UCR Botany & Plant Sciences Development of a detailed genetic map of citrus, including genes for resistance to citrus tristeza M.L. Roose UCR Botany & Plant Sciences virus, Phytophthora tolerance, apomixis, and fruit acidity. Identification and cloning of a gene that controls citric acid accumulation in citrus fruit. M.L. Roose UCR Botany & Plant Sciences Inheritance and molecular genetic analysis of apomixis (nucellar embryony) in citrus. M.L. Roose UCR Botany & Plant Sciences Positional cloning of a trifoliate orange gene that confers immunity to citrus tristeza virus. M.L. Roose UCR Botany & Plant Sciences Use of molecular markers including RFLPs, RAPDs, ISSRs, and SSRs to understand phylogeny M.L. Roose UCR Botany & Plant Sciences and genetic diversity of citrus. Current work emphasizes lemons. A project initiated to identify a core collection of about 100 accessions, which represent a M.L. Roose; UCR Botany & Plant Sciences; large proportion of the genetic diversity present in citrus. First phase will involve screening the R.R. Krueger USDA-ARS-NCGRCD. Riverside CA entire germplasm collection for SSR (single sequence repeat or microsatellite) markers. Development of improved methods for genetic transformation of citrus and their application M.L. Roose UCR Botany & Plant Sciences to develop cultivars resistant to citrus tristeza virus. Development of new, early maturing grapefruit cultivars and seedless mandarins by hybridization M.L. Roose UCR Botany & Plant Sciences and mutation breeding. Development of new rootstock cultivars which reduce tree size, have improved disease M.L. Roose UCR Botany & Plant Sciences resistance, broader soil adaptation, and desirable effects on fruit quality. Development of citrus cultivars with enhanced characters using the tools of molecular genetics. L. Walling UCR Botany & Plant Sciences Current efforts focus on reducing seed set and enhancing tolerance to pathogens and pests. Regulation of flowering in sweet oranges L. Pillitteri, C. Lovatt, UCR Botany & Plant Sciences L. Walling Explorations of stress proteins as indicators of freeze damage in oranges. T.J. Close UCR Botany & Plant Sciences Screening of citrus lines for susceptibility to Agrobacterium rhizogenes. O. Becker UCR Nematology Detection and characterization of citrus tristeza virus strains in Field 12B, with emphasis A. Dodds, D. Matthews UCR Plant Pathology on severe strains. Characterization of basic morphological and fruit quality factors for the entire NCGRCD collection. R.R. Krueger USDA-ARS-NCGRCD, Riverside CA Characterization of trifoliate accessions for basic morphological characteristics and seasonal R.R. Krueger USDA-ARS-NCGRCD, Riverside CA growth characteristics. Screening sour orange hybrids and newer accessions for CTV tolerance and other characteristics. R.R. Krueger USDA-ARS-NCGRCD, Riverside CA Screening rootstocks for micronutrient and salt uptake. R.R. Krueger USDA-ARS-NCGRCD, Riverside CA Pathogen screening of CVC accessions. R.R. Krueger USDA-ARS-NCGRCD, Riverside CA Development of efficient genetic transformation procedures for one or several commercially A. Dandekar, D. Burger UCD Pomology important citrus cultivars in California. Development of new rootstock cultivars for the desert citrus growing areas that are suitable G. Wright; Univ. of Arizona, Tucson AZ; for lemons. K. Bowman USDA-ARS-USHRL, FL Development of hybrid mandarin cultivars for the desert with excellent fruit quality, yield, size, G. Wright Univ. of Arizona, Tucson AZ and consumer acceptance. Revision of the taxonomy of the subfamily Aurantioideae of the Rutaceae based upon C. Morton Auburn Univ., Auburn AL analysis of the chloroplast and nuclear genomes. Genetic improvement of lemon cultivars for fresh and processed use. B. Nielsen, B. Castle Univ. of Florida, Lake Alfred FL Evaluation of unique lime oils for commercial utilization. M. Morris A.M. Todd Company, Jefferson OR Project initiated to increase the diversity of germplasm used in breeding Citrus scions. J. Chaparro USDA-ARS-USHRL, FL Development of new rootstock cultivars. K. Bowman USDA-ARS-USHRL, FL Studies on Citrus genetics K. Bowman USDA-ARS-USHRL, FL
32 Table 4. Continued.
Project description Investigator Institution/Department Creation of transgenic citrus trees that have fruits free from limonoid bitterness and S. Hasegawa USDA-ARS, increased concentrations of limonoid glucosides that have pharmacological activity. G. Manners Western Regional Research Center, Albany CA Isolation and characterization of new limonoids from the Rutaceae plant family. S. Hasegawa USDA-ARS, G. Manners Western Regional Research Center, Albany CA Evaluation of Citrus and its closely related genera using limonoids as chemotaxonomic markers. S. Hasegawa USDA-ARS, G. Manners Western Regional Research Center, Albany CA Evaluation and isolation of natural products from citrus seeds which inhibit Aspergillus G. Takeoka USDA-ARS growth and aflatoxin production. Western Regional Research Center, Albany CA Anticarcinogenic activity of citrus limonoids. S. Hasegawa USDA-ARS G. Manners Western Regional Research Center, Albany CA Evaluation of the cyropreservation of seeds of Citrus and Citrus relatives. C. Walters USDA-ARS, National Seed Storage Laboratory, Fort Collins CO Evaluation of the cyropreservation of vegetative materials of Poncirus trifoliata. L. Towill USDA-ARS National Seed Storage Laboratory, Fort Collins CO
and citrus relatives. Increasing demand for oral presenta- document), photographs of common citrus varieties, and tions and fruit displays, especially labor-intensive dis- a list of the CVC accessions (Appendix, this document). plays such as the Riverside Orange Blossom Festival have necessitated hiring students as well as assembling a Recommendation 12. The CVC website is a potentially group of volunteers from the Riverside County UC Co- valuable distribution point for CVC collection characteriza- operative Extension Master Gardeners program to help tion and evaluation data. It may need relocation from its cur- conduct large fruit displays. Volunteers provided over rent status on the UCR College of Natural and Agricultural 100 person-hours collecting and washing fruit in addi- Sciences server. The website should include contact informa- tion to hours spent setting up and taking down tents and tion for the staff. tables, cleaning the booth, and providing questions and answers to the general public. Personnel The staff of the CVC also receives numerous The current curator of the CVC and the three CEBs is phone calls, letters, and email messages from local and employed as a Senior Museum Scientist (67% time) in international growers, nurserymen, industry representa- the Dept. of Botany and Plant Sciences. This position is tives, state officials, and the general public requesting currently held by T.L. Kahn. access to its database on characteristics, genetic identity, The other members of the CVC staff are a Staff and history of specific cultivars and strains of citrus and Research Associate (100% time) and work-study stu- citrus relatives. The staff also provides fruits, and other dents who are employed 5 to 10 hours a week during the materials to UC faculty, specialists, and advisors as a school year and full time during the summer. The num- source of demonstration materials for their activities. In bers of students employed varies from year to year. The March of 2000, the staff of the CVC provided support Staff Research Associate position (held by O. Bier) has for a two-day Citrus Celebration, which culminated in a been supported on a yearly basis since 1992 by grants reception and dinner which honored 23 UCR research- from the CRB. Grants were to M.L. Roose from 1992 to ers and two programs, the CCPP and the CVC, for their 1995, since then, grants have been to T.L. Kahn and commitment to furthering science and the advancement M.L. Roose. The on-going objective of these grants is to of California’s Citrus Industry. evaluate trueness-to-type and commercial potential of A website (http://cnas.ucr.edu/~citrus/index. citrus varieties distributed by the CCPP, therefore, the htm) has been established through the auspices of the SRA position only supports the CVC to the extent the UCR CNAS and consists of multiple pages of basic in- duties of evaluation coincide with CVC objectives. The formation about the CVC including, history, goals, re- major evaluation emphasis of the CRB-supported work is search projects utilizing the collection (Table 4, this on fruit quality traits of varieties in the major production
33 regions of the state. The short-term nature of work-study Financial resources employment (and subsequent high turnover) and the indirect service of the SRA position are not optimal ar- Office space, laboratory, greenhouse space, screenhouse, rangements for technical support for the CVC. administrative support, and a budget of $3,000 per year for operating expenses for the CVC are provided by the Recommendation 13. Positions and staffing levels needed Dept. of Botany and Plant Sciences, UC Riverside. Mis- are a full-time curator, full-time technical assistant/assistant cellaneous administrative expenses such as phone calls, curator, part-time seasonal assistants, and a part-time data- photocopying, and FAX charges are paid by the CVC by base/website specialist. recharge. Vehicles needed for travel to and from the lab, CVC, greenhouses, and CEBs are rented by the CVC Facilities and equipment from the Dept. of Botany and Plant Sciences. These ve- Computers accessible for work of the CVC are one hicles are expensive and only available on a first-come- Pentium 100MHz computer at the curator’s desk that first served basis limiting planned use. The modest oper- must serve her other activities as well and a Pentium ating expense budget limits the quality of maintenance 133MHz computer in the laboratory space provided to and the scope of evaluation and extension activities that the CVC by the Dept. of Botany and Plant Sciences. can be undertaken each year. Each machine has a copy of the CVC database on it, but For most of its existence, the CVC was supported each is maintained separately. Currently the CVC web almost entirely by the host institution, the University of page is housed on a server belonging to the UCR CNAS California. In the past, there were small amounts of ad- and staff of the CVC do not have direct access to it. ditional indirect support from research grants to E. Nauer, D.J. Gumpf, and M.L. Roose from the CRB for Recommendation 14. The CVC should have at least two projects that utilized the CVC. Since T.L. Kahn became up-to-date, networked computers and at least one laser-qual- curator of the CVC and the CEBs, the University of ity printer, devoted to such activities as accessioning, data California has provided direct support to the CVC as analysis and exchange, equipment and budget monitoring, salary (to T.L. Kahn, now as a 67% time Senior Museum and preparation of outreach materials. Scientist), as operating expenses, as office and laboratory facilities, as administrative services, as tree maintenance Laboratory facilities for the CVC are provided by the services via the UCR Agricultural Operations and the Dept. of Botany and Plant Sciences. Equipment comes field stations, and as funds to update and expand the from the Dept. or was purchased by T.L. Kahn with re- search start-up funds. However, some CVC activities require other arrangements for equipment. For example, for evaluations of pollen viability (Figure 21), CVC staff currently borrows a Zeiss epifluorescent microscope from the Dept. of Botany and Plant Sciences that is otherwise used for teaching courses in the department. If there were funds, a vertical illuminator could be purchased that would update the standard microscope in the CVC laboratory for use in fluorescence microscopy. The main CVC field plantings are physically lo- cated about 2 miles (and 5 minutes by vehicle) from the offices of the curator and technical assistant and the lab facilities used by them in the Dept. of Botany and Plant Sciences. The secondary sites (2 acres each) at Irvine and Thermal are 1 and 1.5 hours away, respectively. Any tools and field equipment must be stored in the labora- tory and carried to the field for each use. The laboratory size is 288 sq. ft. and not much storage is possible. Figure 21. The squashed, softened stigma, one day after pollination, reveals germinating viable pollen grains. Recommendation 15. Facilities and equipment needs in- Pollen tube growth can be used as a measure of pollen clude research equipment, a vehicle, and a greenhouse/ viability. Abnormal growth of the pollen tube structure headhouse structure on or near the orchard site to facilitate would be indicative of pollen-stigma incompatibility. propagation of new or replacement accessions and field evalu- The pollen tubes are stained with aniline blue that is ation activities, house equipment and tools, and offer a recep- specific for the callose which lines the walls of pollen tion point for CVC visitors and tours. tubes. They are visualized with fluorescence microscopy, a technique for which the CVC should be equipped. Photo credit: Tracy L. Kahn.
34 computer database of CVC accessions ($1,500) via a T.L. Kahn and O. Bier to provide ideas and review of 1997–98 award from the UC Genetic Resources Conser- plans developed by the Walt Disney Imagineering staff vation Program. produced $1,000 for CVC activities. A donation of In addition, direct extramural support for CVC $8,000 (1999–01) from the A.M. Todd Company was activities has come from funds awarded to T.L. Kahn received in support of the CVC’s research program on from USDA ARS as a Specific Cooperative Agreement the characterization of lime varieties. While the fund with the NCGRCD (1997: $10,000; 1998: $4,000) to currently has only $7,378, it could serve as seed money assist in the conservation and evaluation activities of for an endowment fund in support of the CVC. CVC and from the California Citrus Nursery Advisory Board (a one-year grant in 2000 to complete conversion Recommendation 16. The CVC needs an annual budget of the CVC main plantings to a low-volume irrigation for operating expenses and outreach that reflects the full costs system and to provide remedial fruit removal and prun- of these activities including maintenance on facilities and ing and development of a brochure in preparation for an equipment and depreciation on equipment (Table 5). endowment fund-raising campaign). The absence of other direct extramural support is primarily a reflection Recommendation 17. The CVC needs funding for first- of the fact that there are not funding sources whose mis- time and one-time expenses to bring its physical facilities to a sion entails support of genetic resources acquisition and level adequate to meet its needs as a California repository of maintenance directly on a time scale that facilitates citrus genetic resources (Table 5). long-term conservation. Other extramural funds indi- Table 5. Costs of personnel, equipment, and facility requirements for rectly support activities of the CVC. the CVC. The CRB awards that support the SRA position for evaluation of ac- Initial and replacement cessions were described above. For Category cost (dollars) Annual cost (dollars) the 1998–99 season ($12,010) and Personnel 1999–00 season ($16,841), T.L. Curator (1.0 FTE) 65,000a,b Kahn and M.L. Arpaia received Technical Assistant (1.0 FTE) 40,000a,b CRB funding for a related project Database/website specialist (0.5 FTE) 21,000a,c that provides a sensory evaluation of Temporary assistance 10,000a,d a selection of new varieties (see Supplies Table 4). The CVC serves as one source of fruit for these taste panels. Nursery and lab supplies 5,000 The CVC is also the site of research Acquisition, research, & evaluation 25,000e conducted by T.L. Kahn to evaluate Equipment factors controlling seedlessness in Vehicle: minivan 20,000 new Clementine mandarin selec- Vertical illuminator and filter sets (Zeiss) 5,000 tions (see Table 4). This project Computers (2) 5,000 which is funded by the California Citrus Nursery Advisory Board Printer 600 (1998–99: $3,365, 1999–00: $4,125, Electric cart 5,000 2000–01: $4,215) provides funding Services received for work-study students who are Annual tree maintenancef 24,000 members of the CVC staff. Another Annual tree pruning 2,000 cooperative CRB-funded mandarin Annual fruit reduction 7,000 variety trial, being conducted by T.L. Annual vehicle maintenance 2,000 Kahn and P. Mauk to provide the industry with information on tree Facility growth, fruit quality characteristics, Greenhouse (36’x60')/headhouse (20’x36') 200,000 and timing of legal maturity for se- Utilities for field facilities 2,000 lected mandarin varieties in the Subtotal 235,600 203,000 California desert, also indirectly sup- Contingency fund reserve ports the CVC. 12% of annual budget 24,360 Finally, a UC Riverside Foun- Total 235,600 227,360 dation account for the CVC was es- a d tablished in the 1980s and has re- includes benefits; Work-study and summer students; bestimate, actual amount will depend on job title; eReserved for supplies, travel, and staffing ceived donations in support of the cbased on Computer Resource Specialist II title, fPerformed currently by UCR Agricultural CVC. For example, participation by entry level; Operations, does not include pruning.
35 Recommendation 18. Funding to enhance and sustain the pus, at the Research and Extension Centers (South CVC’s role in conservation and utilization of citrus genetic Coast and Lindcove), and at the Coachella Valley resources for California properly involves the US Govern- Agricultural Research Station. For the UCR campus, ment, the State of California, the University of California, grant requests for land, labor, and facilities, and and the citrus industry. progress reports must be submitted annually. For the Research and Extension Centers, research project Recommendation 19. An endowment fund should be es- proposals must be submitted for each collection at tablished with interest earned being dedicated to meet annual three-year intervals and project review reports must operations costs of the CVC. The fund should be organized be submitted annually. under the auspices of the UC Riverside campus with contri- ✦ Providing the general direction and guidance for the butions from the diverse enterprises comprising the California physical maintenance of CVC trees and accessions citrus industry and individual donors. A committee composed maintained in portions of two greenhouses on the of representatives of USDA NPGS, UC, CDFA, and CRB UCR campus. and individuals having strong interest in the preservation of ✦ Providing the curation, accessioning, and guidance citrus varieties and diversity should be convened to develop for the physical maintenance of the CEBs. this fund. ✦ Facilitating research projects which utilize accessions Administration from the CVC. The CVC is administered by a curator employed by the ✦ Conducting research directly. Department of Botany and Plant Sciences in the UC ✦ Coordinating and, in most cases, conducting outreach Riverside College of Natural and Agricultural Sciences. activities related to the collection and citrus genetic The curator has direct responsibility for the CVC collec- diversity in general. The time required from the cura- tions. Close collaboration with the curators of the CCPP tor necessitated by this task has significantly in- and the NCGRCD provides mutual guidance for genetic creased in recent years. resource management issues, however, a more formal advisory arrangement would benefit the curator. Recommendation 20. The relationship of the management The curator’s responsibilities include: of the CEBs to management of the CVC should be formal- ✦ Organizing, applying for, and reporting on the project ized and the extent of the effort required by the CVC curator support that allows for the physical maintenance of to manage the CEBs needs to be defined to ensure that these trees in the CVC and CEB acreage on the UCR cam- activities do not come at the expense of CVC activities.
36
LITERATURE CITED
BAJAJ YPS 1984. Induction of growth in frozen embryos of coconut and CHEN Z 1997. Conservation and identification of genetic resources of citrus ovules of citrus. Curr Sci 53:1215–1216. and its relatives. p 11–17 in: LG ALBRIGO (ed). Identification and conservation BAJAJ YPS 1995. Cryopreservation of plant cell, tissue, and organ culture for of genetic resources of citrus and its relatives. Proc. Symp. held during VIII the preservation of germplasm and biodiversity. p 3–28 in: YPS BAJAJ Congress Int. Soc. of Citriculture, Sun City, South Africa, 13 May 1996. UN FAO. (ed) Biotechnology in agriculture and forestry. Vol 32. Cryopreservation DAVIES FS and LG ALBRIGO 1994. Citrus. Crop production science in horticulture of plant germplasm I. Springer-Verlag, Berlin GERMANY. 2. CAB International, Wallingford UK. BARRETT HC 1990. US119, an intergeneric hybrid citrus scion breeding line. DENG XX, WW GUO, and WC ZHANG 1997. Citrus germplasm and its utilization. HortSci 25:1670–1671. p 18–25 in: LG ALBRIGO (ed). Identification and conservation of genetic BARRETT HC an d AM RHODES 1976. A numerical taxonomic study of the affin- resources of citrus and its relatives. Proc. Symp. held during VIII Congress ity relationships in cultivated Citrus and its close relatives. Syst Bot Int. Soc. of Citriculture, Sun City, South Africa, 13 May 1996. UN FAO. 1:105–136. DOWNEY JG 1874. More about orange culture. Overland Mon 12:560–62. BASH JA 1999. The California Citrus Clonal Protection Program. p 323–327 in: DUNLAP L 2000. Roots. Fiat Lux 10(1):10–11. Proc Fifth World Congress, 1997, Int Soc Citrus Nurserymen. DURÁN-VILA N 1995. Cryopreservation of germplasm of citrus. p 70–86 in: BENNETT E 1970. Tactics of plant exploration. p 157–179 in: OH FRANKEL and E YPS BAJAJ (ed) Biotechnology in agriculture and forestry. Vol 32. Cryo- BENNETT (eds) Genetic resources in plants–Their exploration and conserva- preservation of plant germplasm I. Springer-Verlag, Berlin GERMANY. tion. Blackwell, Oxford UK. ELLIS RH, TD HONG, and EH ROBERTS 1985. Handbook of seed technology for BETTENCOURT E, T HAZEKAMP, and MC PERRY 1992. Directory of germplasm collec- genebanks. II. Compendium of specific germination information and test tions. 6.1. Tropical and subtropical fruits and tree Nuts. IBPGR, Rome ITALY. recommendations. IBPGR, Rome ITALY. BHATTACHARYA SC and S DUTTA 1956. Classification of citrus fruits of Assam. EVANS L 1874. The story of the Mission Bridge brand and the George Gobruegge Government of India Press, Delhi. family in California citrus. Published by the author, Riverside CA USA. BOND JE and ML ROOSE 1998. Agrobacterium-mediated transformation of the FANG DQ, CT FEDERICI, and ML ROOSE 1997a. Development of molecular markers commercially important citrus cultivar Washington navel orange. Plant linked to a gene controlling fruit acidity in citrus. Genome 40:842–849. Cell Rep 18:229–234. FANG DQ, CT FEDERICI, and ML ROOSE 1998. A high resolution linkage map of CALAVAN EC, SM MATHER, and EH MCEACHERN 1978. Registration, certification, the citrus tristeza virus gene region in Poncirus trifoiata (L.) Raf. Genetics and indexing of citrus trees. p 185–222 in: W REUTHER, EC CALAVAN, and GE 150:883–890. CARMAN (eds) The citrus industry, Rev ed, vol IV. Crop protection. Univ of FANG DQ and ML Roose 1997. Identification of closely related citrus cultivars California Div of Agricultural Sciences, Berkeley CA USA. with inter-simple sequence repeat markers. Theor Appl Genet 95:408–417. CALAVAN EC, CN ROISTACHER, and EM NAUER 1972. Thermotherapy of citrus for FANG DQ, ML ROOSE, RR KRUEGER, and CT FEDERICI 1997b. Fingerprinting trifoli- inactivation of certain viruses. Plant Disease Rep 56:976–980. ate orange germplasm accessions with isozymes, RFLPs, and inter- CALIFORNIA AGRICULTURAL STATISTICS SERVICE 2000. California Agricultural Statis- simple sequence repeat markers. Theor Appl Genet 95:211–219. tics, Crop Years 1990–99. http://www.nass.usda.gov/ca/bul/agstat/ FEDERICI CT, DQ FANG, RW SCORA, and ML ROOSE 1998. Phylogenetic relation- indexcas.htm. ships within the genus Citrus (Rutaceae) and related genera as revealed CALIFORNIA DEPT. OF FOOD AND AGRICULTURE 2000. Agricultural Exports. http:// by RFLP and RAPD analysis. Theor Appl Genet 96:812–822. www.cdfa.ca.gov/statistics/export.html. FERRIER WW 1930. Origin and development of the University of California. CENTER FOR PLANT CONSERVATION 1991. Endangered species: The plight of plants. The Sather Gate Book Shop, Berkeley CA USA. Missouri Botanical Garden, St. Louis MO USA. FOSTER JA 1988. Regulatory actions to exclude pests during the international CHADHA KL 1995. Status report on tropical fruit species in South Asia. p 45– exchange of plant germplasm. HortSci 23:60–66. 60 in: RK ARORA and VR RAO (eds) Expert consultation on tropical fruit FRISON EA and MM TAHER 1991. FAO/IBPGR Technical guidelines for the safe species of Asia. IPGRI Office for South Asia, New Delhi INDIA. movement of citrus germplasm. IOCV/FAO, Rome ITALY.
37 FROST HB and RK SOOST 1968. Seed reproduction: development of gametes KOBAYASHI S, S SAKAI, and A OIYAMA 1990. Cryopreservation in liquid nitrogen and embryos. p 290–320 in: W REUTHER, LD BATCHELOR, and HJ WEBBER (eds) of cultured navel orange (Citrus sinensis Osb.) nucellar cells and subse- The citrus industry, Rev ed, vol. II. Anatomy, physiology, genetics, and repro- quent plant regeneration. Plant Cell Tissue Organ Cult 23:15–20. duction. Univ of California Div of Agricultural Sciences, Berkeley CA USA. KRUEGER RR 1999a. National Clonal Repository at Riverside, California, pro- FURR JR 1964. New tangerines for the desert. Calif Citrograph 49:266, 276. tects and provides unique citrus and date palm collections. Diversity FURR JR 1969. Citrus breeding for the arid southwestern United States. Proc 15(3):19–21. 1st Int Citrus Symp 1:191–197. KRUEGER RR 1999b. The California citrus certification program. p 303–305 in: FURR JR, JB CARPENTER, and AA HEWITT 1963. Breeding new varieties of citrus Proc Fifth World Congress, 1997, Int Soc Citrus Nurserymen. fruits and rootstocks for the southwest. J Rio Grande Valley Hort Soc LAWTON HW and LG WEATHERS 1989. The origins of citrus research in Califor- 17:90–107. nia. p 281–335 in: W REUTHER, EC CALAVAN, and GE CARMAN (eds) The citrus GMITTER Jr FG, JW GROSSER, and GA MOORE 1992. Citrus. p 335–369 in: FA industry, vol V. Crop protection, postharvest technology, and early history HAMMERSCHLAG and RE LITZ (eds) Biotechnology of perennial fruit crops. of citrus research in California. Univ of California Div of Agricultural Sci- CAB International, Wallingford UK. ences, Berkeley CA USA. GMITTER F and X HU 1990. The possible role of Yunnan, China, in the origin of LUGO J del C 1950. Vida de un ranchero, dictated to Thomas Savage for HH contemporary Citrus species (Rutaceae). Economic Bot 44:267–277. Bancroft, in October 1877. Translated by Helen Pruitt Beattie. Typewrit- ten manuscript. (Original manuscript in Bancroft Library, Univ of Califor- GMITTER F, SY XIAO, S HUANG, SM GARNSEY, Z DENG, and X HU 1996. A localized nia, Berkeley CA USA.) linkage map of the citrus tristeza virus resistance gene region. Theor Appl Genet 92:688–695. MARÍN ML and N DURÁN-VILA 1992. Cryopreservation of somatic embryos of ‘Washington Navel’ sweet orange. Proc Int Soc Citriculture 1:313–317. GUARINO L, VR RAO, and R REED 1995. Collecting plant genetic diversity: Techni- cal guidelines. CAB International, Cambridge UK. MARÍN ML, Y GOGORCENA, J ORTIZ, and N DURÁN-VILA 1993. Recovery of whole plants of sweet orange from somatic embryos subjected to freezing- GUMPF DJ, JS SEMANCIK, JA BASH, G GREER, J DIAZ, R SERNA, and R GONZALES 1997. thawing treatments. Plant Cell Tissue Organ Cult 34:17–33. The California Citrus Clonal Protection Program. Proc Int Soc Citriculture 1:445–447. MESTRE PF, MF ASÍNS, EA CARBONELL, and L NAVARRO 1997a. New gene(s) in- volved in the resistance of Poncirus trifoliata (L.) Raf. to citrus tristeza HAWKES JG 1980. Crop genetic resources field collection manual. International virus. Theor Appl Genet 95:691–695. Board for Plant Genetic Resources (IBPGR) and European Assoc for Re- search on Plant Breeding (EUCARPIA). Druk Co PUDOC, Wageningen MESTRE PF, MF ASÍNS, JA PINA, and L NAVARRO 1997b. Efficient search for new NETHERLANDS. resistant genotypes to the citrus tristeza closterovirus in the orange subfamily Aurantioideae. Theor Appl Genet 95:1282–1288. HERRERO R, MJ ASÍNS, EA CARBONELL, and L NAVARRO 1996a. Genetic diversity in the orange subfamily Aurantioideae. I. Intraspecies and intragenus METCALF RL 1963. The University of California Citrus Research and Agricul- genetic variability. Theor Appl Genet 92:599–609. tural Experiment Station. World Rev Pest Control 2(2):7–15. HERRERO R, MJ ASÍNS, JA PINA, EA CARBONELL, and L NAVARRO 1996b. Genetic MUMFORD PM and WW GROUT 1979. Desiccation and low temperature (- diversity in the orange subfamily Aurantioideae. II. Genetic relation- 196°C) tolerance of Citrus limon seeds. Seed Sci Technol 7:407–410. ships among genera and species. Theor Appl Genet 93:1327–1334. MURASHIGE T, WP BITTERS, TS RANGAN, EM NAUER, CN ROISTACHER, and PB HOLLIDAY HOAGLAND KE and AY ROSSMAN (eds) 1997. Global genetic resources: Access, 1972. A technique of shoot apex grafting and its utilization towards ownership, and intellectual property rights. Assoc of Systematics Collec- recovering virus-free Citrus clones. HortSci 7:118–119. tions, Washington DC USA. NAMKOONG G 1988. Sampling for germplasm collection. p 79–81. Proc XXII HODGSON RW 1961. Taxonomy and nomenclature in citrus. p 1–7 in: WC Price Int Hort Cong/83rd Am Soc Hort Sci Ann Mtg. (ed) Proc. 2nd Conf. Int. Org. of Citrus Virologists. Univ of Florida Press, NATIONAL RESEARCH COUNCIL 1978. Conservation of germplasm resources—An Gainesville. imperative. National Academy of Sciences, Washington DC USA. HOLDEN JHW and JT WILLIAMS 1984. Crop genetic resources: Conservation and NATIONAL RESEARCH COUNCIL 1991. Managing global genetic resources: The U.S. evaluation. George Allen and Unwin, London UK. National Plant Germplasm System. National Academy of Sciences, Wash- IBPGR 1982. Genetic resources of citrus. IBPGR, Rome ITALY. ington DC USA. IOCV nd A supplement to the handbook: ‘Indexing procedures for 15 virus NATIONAL RESEARCH COUNCIL 1993. Managing global genetic resources: Agricul- diseases of citrus trees’. Mimeographed sheet. tural crop issues and policies. National Academy of Sciences, Washington DC USA. JONES DT 1991. A background for the utilization of citrus genetic resources in Southeast Asia: II. Germplasm collection, documentation, and research. NAUER EM, EC CALAVAN, CN ROISTACHER, RL BLUE, and JH GOODALE 1967. The Citrus p 61–64 in: Proc Int Citrus Symp, Guangzhou PR CHINA. Variety Improvement Program in California. Calif Citrograph 52:133, 144, 145, 146, 148, 151, 152. KNORR LC 1977. Citrus. p 111–118 in: WB HEWITT and L CHIARAPPA (eds) Plant health and quarantine in international transfer of genetic resources. CRC NAVARRO L 1981a. Citrus shoot-tip grafting in vitro (stg) and its applications: Press Inc, Cleveland OH USA. A review. Proc Int Soc Citriculture 2:452–456. NAVARRO L 1981b. Handbook of therapy procedures for elimination of virus and virus-like diseases in fruit crops. IOCV/FAO, Rome ITALY.
38 NAVARRO LN 1992. Citrus shoot tip grafting in vitro. p 327–338 in: YPS BAJAJ HAWKES (eds) Crop genetic resources for today and tomorrow. Cambridge (ed) Biotechnology in agriculture and forestry. Vol 18. High-tech and Univ Press, Cambridge UK. micropropagation II. Springer-Verlag, Berlin GERMANY. ROE JH 1932. Notes on early history of Riverside, California. On file in the NAVARRO L 1993. Citrus sanitation, quarantine and certification programs. p Local History Collection, Riverside Public Library, Riverside CA USA. 383–391. Proc Int Org Citrus Virologists. (Typescript.). NAVARRO L and J JUAREZ 1977. Elimination of citrus pathogens in propagative ROISTACHER CN 1977. Elimination of citrus pathogens in propagative budwood. II. In vitro propagation. Proc Int Soc Citriculture 3:973–987. budwood. I. Budwood selection, indexing and thermotherapy. Proc Int NAVARRO L, J JUAREZ, JA PINA, JF BALLESTER, and JM ARREGUI 1988. The citrus Soc Citriculture 3:965–972. variety improvement program in Spain after eleven years. p 400–406. ROISTACHER CN 1981a. Changes in transmissibility of seedling yellows. A Proc Int Org Citrus Virologists. blueprint for disaster. (part 2). Citrograph 67(2):28–32 NAVARRO L, CN ROISTACHER, and T MURASHIGE 1975. Improvement of shoot-tip ROISTACHER CN 1981b. The history of seedling yellows disease. A blueprint for grafting in vitro for virus-free citrus. J Am Soc Hort Sci 100:471–479. disaster. (part 1). Citrograph 67(1):4–5, 24. NIEDZ RP, M. BAUSCHER, and CJ HEARN 1992. Use of stored pollen to hybridize a ROISTACHER CN 1982. The destructive potential for seedling yellows. A blue- mandarin hybrid and Citrus tachibana. HortSci 27:43–44. print for disaster (part 3). Citrograph 67(3):48–53 NYE RL 1983. Federal vs. State agricultural research policy: The case of ROISTACHER CN 1991. Graft-transmissible diseases of citrus: Handbook for de- California’s Tulare experiment station, 1888–1909. Agric Hist tection and diagnosis. IOCV/FAO, Rome ITALY. 57(4):436–449. ROISTACHER CN 1998. Indexing for viruses in citrus. p 301–3119 in: A Hadidi, OMURA M 1997. Genetic resources of citrus in Japan: a summary. p 70–72 in: RK Khetarpal, H Koganezawa (eds). Plant virus disease control. APS Press, LG ALBRIGO (ed). Identification and conservation of genetic resources of St Paul MN USA. citrus and its relatives. Proc. Symp. held during VIII Congress Int. Soc. of ROISTACHER CN, EC CALAVAN, and L NAVARRO 1977. Concepts and procedures for Citriculture, Sun City, South Africa, 13 May 1996. UN FAO. importation of citrus budwood. Proc Int Soc Citriculture 1:133–136. PARLIMAN BJ and GA WHITE 1985. The plant introduction and quarantine ROOS EE 1988. Genetic changes in a collection over time. p 86–90. Proc XXII system of the United States. Plant Breeding Rev 3:361–434. Int Hort Cong/83rd Am Soc Hort Sci Ann Mtg. PAUL A and P COX 1995. An ethnobotanical survey of the uses of C. aurantium ROOSE ML 1988. Isozymes and DNA restriction fragment length polymor- (Rutaceae) in Haiti. Econ Botany 49:249–256. phisms in citrus breeding and systematics. p 155–165 in: R Goren and K PLANT EXPLORATION OFFICE 1990. Code of conduct for foreign plant explora- Mendel (eds) Proc 6th Int Citrus Congr, vol 1. Balaban Publishers, Rehovot tions. USDA Plant Exploration Office, Washington DC USA. Photocopied. ISRAEL. RADHAMANI J and KPS CHANDEL 1992. Cryopreservation of embryonic axes of ROOSE ML, RK SOOST, and JW CAMERON 1995. Citrus. p 443–448 in: J SMARTT and trifoliate orange (Poncirus trifoliata (L.) RAF) Plant Cell Rep 11:204–206. NW SIMMONDS (eds) Evolution of crop plants (2nd ed), Longman, UK. RAI M, KPS CHANDEL, and PN GUPTA 1997. Occurrence, distribution, and diver- ROUSE RE 1988. Major citrus cultivars of the world as reported from selected sity in the genus Citrus in the Indian gene centre. p 26–39 in: LG ALBRIGO countries. HortSci 23:680–684. (ed). Identification and conservation of genetic resources of citrus and its SAAMIN S and WW KO 1996. Biodiversity and conservation of Citrus and its relatives. Proc. Symp. held during VIII Congress Int. Soc. of Citriculture, relatives in Malaysia and vicinity. Proc Int Soc Citriculture 2:1221–1227. Sun City, South Africa, 13 May 1996. UN FAO. SAHAR N and P SPIEGEL-ROY 1980. Citrus pollen storage. HortSci 15:81–82. RAVEN PH 1976. Ethics and attitudes. p 155–179 in: JB SIMMONS, RI BEYER, PE SAKAI A 1984. Cryopreservation of apical meristems. Hort Rev 6:357–372. BRANDHAM, GL LUCAS, and VTH PARRY (eds) Conservation of threatened plants. Plenum Press, New York NY USA. SAKAI A 1995. Cryopreservation of germplasm of woody plants. p 53–69 in: YPS BAJAJ (ed) Biotechnology in agriculture and forestry. Vol 32. RAVEN PH 1988. Our diminishing tropical forests. p 119–122 in: EO Wilson and Cryopreservation of plant germplasm I. Springer-Verlag, Berlin GERMANY. FM Peter (eds) Biodiversity. National Academy Press, Washington DC USA. SCORA RW 1975. On the history and origin of citrus. Bull Torrey Bot Club REED JH 1895. Work of the Riverside Horticultural Club. Pacific Rural Press 102:369–375. 50(20):310–311. SHAMEL AD 1921. It pays to be decent: An appreciation of Ethan Allen Chase. REUTHER W 1977. Genetic resources conservation of citrus species and near Calif Citrograph 7(2):47, 55. relatives from the international viewpoint. Proc Int Soc Citriculture 2:604–606. SHANDS HL 1995. The U.S. National Plant Germplasm System. Can J Plant Sci 75:9–15. REUTHER W 1981. The Citrus Clonal Protection Program. Calif Agriculture 35:30–32. SHANDS HL, PJ FITZGERALD, and S EBERHART 1988. Program for plant germplasm preservation in the United States. p 37–116 in: L KNUTSON and AK STONER REUTHER W, EC CALAVAN, EM NAUER, and CN ROISTACHER 1972. The California (eds) Biotic diversity and germplasm preservation, Global imperatives. Citrus Variety Improvement Program after twelve years. p 271–278 in: Kluwer Academic Pub, Wageningen NETHERLANDS. WC PRICE (ed) Proc Int Org Citrus Virologists. Univ of Florida Press, Gainesville FL USA. SINGH B 1981. Establishment of first gene sanctuary in India for Citrus in Garo Hills. Concept Publishing Co, New Delhi INDIA. ROBERTS EH 1975. Problems of long-term storage of seed and pollen for genetic resources conservation. p 265–295, 316 in: OH FRANKEL and JG
39 SINGH HP and S UMA 1995. Genetic resources of tropical fruits (citrus, banana, TRUE AC 1937. A history of agricultural experimentation and research in the papaya, pineapple and sapota). All India Coordinated Research Project United States, 1607–1925. USDA Misc. Pub. 251:1–321. (Tropical Fruits) Tech Doc No 59. IIHR, Bangalore INDIA. UNIVERSITY OF CALIFORNIA REGENTS 1914. Minutes of the Regents of the Univer- SINGH R and N NATH 1969. Practical approach to the classification of citrus. sity of California, December 22, 1914. Vol. 18:154–160. On file, Office of Proc First Int Citrus Symp 1:435–440. the Secretary of the Regents, Univ of California, Berkeley CA USA. SOOST RK, JW CAMERON, and WP BITTERS 1977. Citrus germplasm collection is USDA-APHIS 1977. Shipping foreign plants home. USDA-APHIS, Plant Pro- widely used. Calif Agriculture 31(9):38–39. tection and Quarantine. Program Aid 1162. GPO, Washington DC USA. SOOST RK and ML ROOSE 1996. Citrus, p 257–323 in: J JANICK and JN MOORE USDA-APHIS 1988. Plant importing procedures and responsibilities of plant (eds) Fruit breeding, Vol. I: Tree and tropical fruits, Wiley, USA. importers. USDA-APHIS, Plant Protection and Quarantine. GPO, Wash- STADTMAN VA 1970. The University of California, 1868–1968. McGraw-Hill ington DC USA. Book Co., New York NY USA. USDA-APHIS 2000. Code of Federal Regulations: Title 7 – Agriculture. GPO, STATEWIDE INTEGRATED PEST MANAGEMENT PROJECT 1991. Integrated Pest Man- Washington DC USA. agement for Citrus. 2nd Edition. Univ of California Statewide Integrated USDA-ARS 1968. Indexing procedures for 15 virus diseases of citrus trees. Pest Project Publication 3303. Agriculture Handbook No 333. GPO, Washington DC USA. STATUTES OF CALIFORNIA 1905. Chapter 278. Statutes and amendments to the Wallace JM 1956. The search for new citrus varieties. Calif Citrograph code of California. 36th Session, 1905. Supt. State Printing, Sacramento 41(7):252,269. CA USA. WEBBER HJ 1918. The Citrus Experiment Station and the Graduate School of STONE BC 1994. Citrus fruits of Assam: A new key to species, and remarks on C Tropical Agriculture. Univ Calif Chron 20(4):487–502. assamensis Bhattacharya and Dutta, 1956. Gard Bull Sing 46:105–112. WEBBER HJ, W REUTHER, and HW LAWTON 1967. History and development of SWINGLE WT 1943. The botany of citrus and its wild relatives of the orange the citrus industry. p 1–39 in: W REUTHER, HJ WEBBER, and LD BATCHELOR (eds) subfamily. p 129–474 in: HJ WEBBER and LD BATCHELOR (eds) The citrus The citrus industry, Rev ed, vol. I. History, world distribution, botany, and industry. vol I. History, botany, and breeding. Univ of California Press, varieties. Univ of California Div of Agricultural Sciences, Berkeley CA USA. Berkeley CA USA. WHITE GA, HL SHANDS, and GR LOVELL 1991. History and operation of the Na- SWINGLE WT and PC REECE 1967. The botany of Citrus and its wild relatives, p tional Plant Germplasm System. Plant Breeding Rev 7:5–54. 190–430 in: W REUTHER, HJ WEBBER, and LD BATCHELOR (eds) The citrus WILKES G 1988. Germplasm preservation: Objectives and needs. p 13–42 in: L industry, Rev ed, vol. I. History, world distribution, botany, and varieties. KNUTSON and AK STONER (eds) Biotic diversity and germplasm preserva- Univ of California Div of Agricultural Sciences, Berkeley CA USA. tion, Global imperatives. Kluwer Academic Pub, Wageningen NETHER- SYKES SR 1997. Citrus germplasm resources in Australia. p 50–55 in: LG LANDS. ALBRIGO (ed). Identification and conservation of genetic resources of citrus WILSON IH 1965. William Wolfskill, 1798–1886: Frontier trapper to California and its relatives. Proc. Symp. held during VIII Congress Int. Soc. of Citricul- ranchero. Arthur H Clark Co, Glendale CA USA. ture, Sun City, South Africa, 13 May 1996. UN FAO. WILLIAMS TE 1990. Preservation and maintenance of virus-free clonal citrus Tanaka T 1954. Species problem in citrus. Tokyo: Japanese Society for the germplasm at the National Clonal Germplasm Repository for Citrus, Promotion of Science. Riverside, California. p 172–178 in: Proc 26th Ann Mtg Caribbean Food TANAKA T 1977. Fundamental discussion of citrus classification. Studia Crops Soc. Citrologia 14:1–6. WILLIAMS TE 1992a. Ex-situ preservation, evaluation, and maintenance of TOWILL L 1988. Genetic considerations for germplasm preservation of clonal pathogen-free clonal germplasm of Citrus and related genera: The materials. Proc XXII Int Hort Cong/83rd Am Soc Hort Sci Ann Mtg. USDA-ARS National Clonal Germplasm Repository for Citrus. p 44–47 in: TOWILL LE 1989. Biotechnology and germplasm conservation. Plant Breeding Proc Int Soc Citriculture. Rev 7:159–182. WILLIAMS TE 1992b. The USDA-ARS National Germplasm Repository program TOWILL LE and EE ROOS 1989. Techniques for preserving of plant germplasm. for ‘clean-stock’ citrus germplasm. p 148–154 in: Proc Workshop Citrus p 379–403 in: L KNUTSON and AK STONER (eds) Biotic diversity and Tristeza Virus and Toxoptera citricidus in Central America. germplasm preservation, Global imperatives. Kluwer Academic Pub, ZHENG X 1995. Genetic resources of tropical fruit species in China. p 103–111 Wageningen NETHERLANDS. in: RK ARORA and VR RAO (eds) Expert consultation on tropical fruit species of Asia. IPGRI Office for South Asia, New Delhi INDIA.
40 41 42 APPENDIX
HOLDINGS OF THE UNIVERSITY OF CALIFORNIA, RIVERSIDE CITRUS VARIETY COLLECTION (CVC)
THE TABLE ON THE FOLLOWING PAGES lists the 865 ac- 5. Tangor cessions currently maintained in the CVC. The acces- 6. Tangelo sions are identified in the CVC by a unique Citrus Re- 7. Calamondin and hybrid search Center (CRC) number. In addition to an Acces- 8. Rangpur type sion name or description field, the table also provides a Variety Introduction (VI) number given to accessions 9. Navel orange cleaned by the Citrus Clonal Protection Program 10. Valencia orange (CCPP) and a Plant Introduction (PI) number assigned 11. Blood orange to accessions listed in the US Dept. of Agriculture’s Ge- 12. Other sweet orange and hybrid netic Resource Information Network (USDA GRIN) database. The Source field provides information on the 13. Sour orange and hybrid source, intermediary, and geographic origin when 14. Pummelo (shaddock) known. The Date field identifies the year in which the 15. Pummelo hybrid accession was acquired by the CVC. 16. Grapefruit The accessions are grouped by the major citrus type to which they are assigned and ordered by CRC 17. Grapefruit hybrid number within these groups. The groups are presented in 18. Miscellaneous Citrus species the following order: 19. Citrus subgenus Papeda and hybrid 20. Kumquat and hybrid 1. Citron and hybrid 21. Trifoliate 2. Lemon, lemon-type 22. Trifoliate hybrid 3. Lime, lime-type 23. Miscellaneous species, not genus Citrus 4. Mandarin
43 44 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 1. Citron and hybrid 0138-A Indian citron (ops) 539413 India 1912 0138-B Indian citron (ops) 539414 India 1912 0294 Ponderosa “lemon” (probable Citron ´ lemon hybrid) 409 539491 Fawcett’s #127, Florida collection 1914 0648 Orange-citron-hybrid 539238 Mr. Flippen, between Fullerton and Placentia CA 1915 0661 Indian sour citron (ops) (Zamburi) 31981 USDA, Chico Garden 1915 1795 Corsican citron 539415 W.T. Swingle, USDA 1924 2456 Citron or citron hybrid (came in as Djerok which is Dutch word for “citrus” 539416 From CPB 1930 2847 Yemen citron 105957 Bureau of Plant Introduction 3055 Bengal citron (ops) (citron hybrid?) 539417 Ed Pollock, NSW, Australia 1954 3174 Unnamed citron 230626 H. Chapot, Rabat, Morocco 1955 3190 Dabbe (ops) 539418 H. Chapot, Rabat, Morocco 1959 3241 Citrus megaloxycarpa (ops) (Bor-tenga) (hybrid) 539446 Fruit Research Station, Burnihat Assam, India 1957 3487 Kulu “lemon” (ops) 539207 A.G. Norman, Botanical Garden, Ann Arbor MI 1963 3518 Citron of Commerce (ops) 539419 John Carpenter, USDCS, Indio CA 1966 3519 Citron of Commerce (ops) 539420 John Carpenter, USDCS, Indio CA 1966 3520 Corsican citron (ops) 539421 John Carpenter, USDCS, Indio CA 1966 3521 Corsican citron (ops) 539422 John Carpenter, USDCS, Indio CA 1966 3522 Diamante citron (ops) 539423 John Carpenter, USDCS, Indio CA 1966 3523 Diamante citron (ops) 539424 John Carpenter, USDCS, Indio CA 1966 3526 Etrog citron (ops) 539425 John Carpenter, USDCS, Indio CA 1966 3527 Hiawassie citron (ops) 539426 John Carpenter, USDCS, Indio CA 1966 3529 Indian citron (ops) 539427 John Carpenter, USDCS, Indio CA 1966 3530 Italian citron (ops) 539428 John Carpenter, USDCS, Indio CA 1966 3531 Mexican citron (ops) 539429 John Carpenter, USDCS, Indio CA 1966 3532 Papuan citron (ops) 539430 John Carpenter, USDCS, Indio CA 1966 3533 Philippine citron (ops) 539431 John Carpenter, USDCS, Indio CA 1966 3534 Sicily citron (ops) 539432 John Carpenter, USDCS, Indio CA 1966 3535 Spadifora citron (ops) (Citrus medica var. Spadifora) 539433 John Carpenter, USDCS, Indio CA 1966 3536 Yemen citron (ops) 539434 John Carpenter, USDCS, Indio CA 1966 3546 South Coast Field Station citron 539435 SCFS 25-3-17 1966 3654 Dulcia citron (ops) 539436 John Carpenter, USDCS, Indio CA 1968 3655 Odorata citron (ops) (Tihi-Tihi) 539437 John Carpenter, USDCS, Indio CA 1968 3723 Badhri “lemon” (ops) 539438 L.C. Knorr, US-AID, Punjab Agr. Univ., Ludhiana, India 1969 3755 Limau Mata Susu (ops) 539439 Richard A. Hamilton, University of Hawaii 1971 3768 Fingered citron (Buddha’s Hand citron) 369 539445 Budwood import from Hawaii, via CCPP 1975 3798 Citrus medica var. Yunnanensis 600630 Prof. Tsuin Shen, Peking Agric. Univ., Peking, China 1980 3819 Citron type 539440 3878 Arizona 861 S-1 citron seedling (Etrog type) 357 600651 Selected seedling of Ariz. 861 citron 3891 Ethrog citron 426 508265 Israel, via Glenn Dale & CCPP 1983 2. Lemon, lemon type 0280 Villafranca lemon 539292 Fawcett’s #128, Florida collection 1914 0390 Villafranca lemon 600625 Grove in Glendora CA 1914 0400 Florida rough lemon (ops) 76 539268 Fawcett’s #175. Seed rec’d from A. Melson, Florida 1914 0565 Genoa lemon (Eureka type) 539313 J.W. Mills, Pomona CA 1914 0569 Millsweet lemon 539281 J.W. Mills, Pomona CA buds from tree 1195 1914 0599 Eureka variegated lemon 539325 Chase lemon grove, Corona CA 1914 0710 Chinese lemon 539211 Riverside Station grounds (see notes below) 1909 1222 Mazoe lemon (ops) 539257 A.C. Turner, Salisbury, Rhodesia 1919 2317 Limon Real 539193 Philippine Islands (via CPB) 1930 2322 India- lemon 539204 CPB 1930 2323 India lemon 539287 CPB 1930 2325 South African rough lemon 539258 South Africa? 2367 Variegated Pink Fleshed Eureka lemon 486 539315 Home garden, D.W. Field, Burbank CA 1931 2429 Amber lemon (Eureka type) 539316 Detweiler grove, Alta Loma CA 1932 2477 Khobs-el-arsa 539288 M.H. Brayard, Marrakech, Morocco 1933 2489 Rhobs-el-arsa (ops) 539289 Rabat, Morocco 1935 2544 Indian rough lemon (ops) 539290 Simla Hills, India (via CPB & Florida) 1932 2557 Gomiri rough lemon (ops) 77 103496 India (via PI, USDA) 1933 2695 Faris sweet lemon 539444 Beverly Hills CA 1938 2703 Cascade Eureka lemon 539317 Cascade Ranch 8-16-1 1939 2881 Bergamot 420 539179 UCLA 1951 2899 Italian pink fleshed lemon 133875 Fd 21, R-47, CRC, Riverside 3001 Seedless Lisbon 492 133731 Lasscock’s Nursery, South Australia 3005 Frost nucellar Eureka lemon 21 539318 2nd budded generation from sdlg of o.l. Rubidoux No. RT 765 3007 Allen Variegated Eureka (Sloop) 539319 Sloop, Oceanside 1953 3009 Messina lemon 539293 Mr. Kipp, Upland CA 1953
45 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 2. Lemon, lemon type (cont.) 3010 Kaweah #1 Lisbon lemon (1-1-1) 539326 Kaweah Lemon Co., Lemon Cove CA 1953 3013 Lupe Lisbon lemon (ops). 347 539327 Claremont CA 1953 3043 Corona (Foothill) old budline Eureka lemon 539320 Foothill Ranch, Corona CA. R-25, T-1, Hill St. 1954 3045 Kulu lemon seedling (Gombru) 539294 J.F.L. Childs, USDA Station, Orlando FL 1954 3050 Volckamer lemon (ops) 407 539335 Acireale, Sicily 1955 3060 Citrus jambhiri (ops) 539259 Dept. of Agric., Lyallpur, Punjab, India 1954 3063 Jullundri Khatti (ops) 539260 Dept. of Agric., Lyallpur, Punjab, India 1954 3093 Sweet lemon (ops) 539278 H.S. Gentry, Shiroz, Iran 1955 3154 Citrus species (ops) (Lemon- Morocco) 230834 Vientiane (Laos) Indo China through Rabat, Morocco 1956 3155 Citrus species (ops) (lemon type) 230832 Vientiane (Laos) Indo China through Rabat, Morocco 1956 3159 Lunario lemon (ops) 218009 Frank Russo, Acireale, Sicily Italy 1956 3162 Iran lemon 539295 Joe Furr, USDCS, Indio CA 1957 3173 Citrus assamensis (lemon ´ citron?) 235991 Mr. Mawsing Rharasti, Shilbong, Assam 1956 3176 Frost nucellar Lisbon lemon 280 539328 Seedling clone from Rubidoux Tract old-line Lisbon 1917 3185 Stow red rough lemon 539261 Stow Ranch, Goleta, CA 1959 3193 Paak ling mung lemon (ops) 93379 Seeds from fruit grown at plant introd. GH, Riverside 1958 3194 Kusner lemon 119828 UCLA Variety block, originally from Russia 1960 3199 Soh long lemon (ops) 254729 Fruit Exp. Sta., Shillong, India 1959 3200 Limoui sangui (ops) 539214 H. Chapot, Rabat, Morocco 1959 3261 Soh synteng lemon (ops) 254730 Govt. Fruit Exp. Sta., Shillong, India 1959 3265 Bitrouni lemon (ops) 539297 H. Chapot, Rabat, Morocco 1959 3300 Wild lemon (ops) 241118 Drs. Grassl & Warner, Kusawun, near Wewak, N. Guinea 1957 3385 Florida rough lemon “A” (ops) 539262 Harry Ford, Cit. Exp. Station, Lake Alfred FL 1963 3386 Estes rough lemon (ops) (Florida ro. lem. “B”) 539263 Harry Ford, Cit. Exp. Station, Lake Alfred FL 1961 3387 Arancino (Coccuzzaro) lemon (ops) 539298 Acireale, Sicily, Italy (via L.J. Klotz, CRC) 1962 3388 Femminello Ovale lemon (ops) 539299 Acireale, Sicily, Italy (via L.J. Klotz, UCR) 1962 3389 Femminello Sfusato lemon (ops) (elongate) 539300 Acireale, Sicily, Italy (via L.J. Klotz, UCR) 1962 3390 Lo Porto lemon (ops) 539301 Acireale, Sicily, Italy (via L.J. Klotz, UCR) 1962 3392 Monachello lemon (ops) 539302 Acireale, Sicily, Italy (via L.J. Klotz, CRC) 1962 3396 Milam lemon (ops) (Clone X- rough lemon type) 539264 Harry Ford, Lake Alfred FL 1959 3491 Primofiore lemon (ops) 539303 Joe Furr, USDCS, Indio CA B1-5-1-3 1965 3492 Iraq lemon (ops) (Sweet) 539314 Bagdad, Iraq, via Beltsville as cuttings. 1963 3496 Allen-Newman #4 op Eureka seedling 539304 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3498 Cascade op Eureka seedling #1 539321 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3499 Blanchard op Eureka seedling 539322 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3500 Femminello (ops) (Lisbon type) 346 539329 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3501 Limoneira Olivelands 8-A Lisbon (ops) 68 539305 Domingo Hardison, Olivelands 4-B, R-7, T-28, Limoneira R. 1966 3504 Dr. Strong Lisbon (ops) #28 345 539306 Domigno Hardison, La Campana Ranch Fillmore CA 1966 3505 Prior Lisbon (ops) #1 539330 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3506 Bergamotto (ops) #18 (Lisbon type) 539180 Domingo Hardison, La Campana Ranch, Fillmore CA 1966 3590 Berna lemon (ops) 539307 Joe Furr, USDCS, Indio CA 1965 3591 Corpaci lemon (ops) 539308 Joe Furr, USDCS, Indio CA B1-5, R-1, T-7 1968 3593 Interdonato lemon (ops) 230373 Joe Furr, USDCS, Indio CA 5-1-11 1965 3737 Improved Meyer lemon 319 539447 CCPP VI 319 stock plant at Rubidoux screenhouse. 1971 3748 Citrus species (ops), lemon type 539208 John Carpenter, USDCS, Indio CA 1971 3834 Limoneira rough lemon (ops) 539265 Lindcove Field Station 3835 Galligan Lisbon lemon (ops) 194 539331 Santa Barbara C.V.O. via CCPP 1962 3836 Foothill Lisbon (ops) 232 539332 Willits & Newcomb, Thermal, via CCPP 1963 3837 Cook Eureka (ops) 228 539323 Willits & Newcomb, Thermal, via CCPP 1963 3838 Ross Eureka (ops) 108 539324 Hardison Ranch, Santa Paula, via CCPP 1960 3839 Monroe Lisbon (ops) 113 539333 Limoneira Olivelands, via CCPP 1960 3840 Rosenberger Lisbon, old budline 372 539334 Utt Development Co., Oxnard CA, via CCPP 1978 3841 Nicaraguan lemon 539209 Import by W. Reuther, probably from Nicaragua 1976 3879 Schaub rough lemon 406 539266 “Mother” tree, J. Carpenter, USDCS, Indio CA 1983 3885 Local variety of lemon from Iran 423 431462 Iran, via Glenn Dale & CCPP 1979 3892 Mesero lemon 209862 Spain, via Glenn Dale & CCPP 1955 3893 Ricote lemon 209863 Spain, via Glenn Dale & CCPP 1955 3894 Santa Teresa #1 lemon 227692 Sicily, via Glenn Dale & CCPP 1959 3924 Peretta 444 539210 Glenn Dale Quarantine Facility, import from Italy 1984 3925 Lumia 445 539310 Glenn Dale Quarantine Facility import from Italy 1984 3970 Limonero Fino 480 539311 Spain? 1987 3989 Limonette de Marrakech (Marrakech Limonette) 573 539280 Morocco 1987 3996 Vangasay rough lemon 493 539267 Florida - Budwood Registration Program- Winter Haven 1988 4005 “Local” lemon from Cyprus (Lapithiotiki lemon) 512A 539312 N. Vakis, Ministry of Agric., Cyprus 1989 4014 Taylor Eureka lemon 528 600661 Australia 1989
46 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 3. Lime, lime type 0363 Sweet lime 539285 Fawcett’s #15 sel.-F.S. Earle, Herradura, Cuba 1914 0391 Tahiti lime 539273 Hart’s grove, San Dimas CA 1914 0449 Ponds seedless lime 539274 Webber’s #17, from garden of Mr. Damon, Moanalua Gardens, Honolulu 1914 0450 Wilder seedless lime 539275 Webber’s #18, from Garrett Wilder, Honolulu 1914 0919 Citrus limettoides (sweet lime) 539286 Fortunato da Silva’s grove, Cabulla, Bahia (thru USDA) 1916? 0921 Citrus limettoides- Risso (sweet lime) 37772 from USDA 1916? 1482 Palestine sweet lime (Indian sweet lime) 81 539283 W.T. Swingle, USDA 1924 1684 Weirick sweet-red lime 539284 Mrs. W.C. Weirick, Box 254, Lincoln CA (Placer County) 1927 1710 Mexican lime (West Indian, Key) 419 539151 Mel Anderson, Fruit Growers Supply Co. 1927 1813 West Indian lime (Mexican, Key) 539152 Tree on ranch S.W. of Indio CA 1928 2188 Key lime (ops) (Stow #7) (West Indian, Mexican) 539153 Harvey grove, West Palm Beach FL 1928 2315 Page lime (Tahiti type) 539271 Residence of Mrs. A.D. Page of Fallbrook CA 1932 2449 Everglade lime (West Indian type) 539154 From CPB 1931 2450 India lime 539155 From CPB 1930 2458 Perrine lemon (lemonime) 539205 From CPB 1931 2459 Lemonime 539206 From CPB 1931 2484 Sniff sweet red lime 539282 Sniff Date Gardens, Indio CA 1933 2683 Thornless Mexican lime 539156 Marcy Ranch, Tustin CA 1937 2709 Otaheite red acidless lime (Citrus tahitensis) 539343 1937? 2883 Egyptian lime (ops) 185427 Y.Carmon, Tel Aviv, Israel 1949 3051 Mitha-Tulia 539277 Dept. of Agric., Lyallpur, India 1943? 3069 Warren limequat 539802 Mavro Warren Ranch, Foothill Rd., Ventura CA 1956 3070 India lime sport 539213 Sport lime from India lime, Fld. 18A R-33 T-2, CRC 1957 3072 Addanimma (ops) 539212 Ed Pollock, Parkes, N.S.W., Australia 1956 3172 Tavares limequat 539804 Lyndon Maxwell, Sunnymead CA 1957 3603 Eustis limequat (ops) 175 539806 Joe Furr, USDCS, Indio CA 1968 3604 Lakeland limequat (ops) 539807 Joe Furr, USDCS, Indio CA 1968 3762 Abhayapuri lime 539157 Richard A. Hamilton, Univ. of Hawaii 1971 3772 Bearss lime 358 539272 Willits & Newcomb, Thermal, via STG and CCPP 1977 3776 Bakrai (acidless lime) 539279 Kaserun, Iran 1975 3822 Mexican lime type 600629 Tree in UCR Field 21D 3997 Rangpur lime ´ Troyer citrange [814-12-47-X-E] 483 539267 Florida - Budwood Registration Program, Winter Haven 1988 4. Mandarin 0279 Clementine (Algerian) mandarin 9 539183 Fawcett’s #134, Florida collection 1914 0300 Parson’s special mandarin 539497 Fawcett’s #106, Florida collection 1914 0303 King mandarin (tangor?) 539456 Fawcett’s #90, Florida collection 1914 0602 Dancy mandarin (Weshart nucellar) 13005 Chico Gardens, Chico CA 1914 0696 Kinokuni mandarin (ops) (Citrus kinokuni) 539270 P.J. Wester, Lamao, Bataan, Philippine Islands 1915 1851 Kawano Wase Satsuma mandarin 539688 French Gilman, Banning, CA 1928 2331 Unnamed mandarin 539493 PR China (via CPB) 1930 2376 Tien Chieh mandarin 539494 From CPB 1930 2448 Citrus depressa (C. pectinifera) (Shekwasha) 109754 From CPB 1930 2485 Citrus amblycarpa seedling (Nasnaran) 93602 From Beltsville MD 1932? 2590 Tien Chieh mandarin seedling 539495 USDA, Washington DC 1935 2692 Tim Kat mandarin (Timkat, Citrus oleocarpa?) 14007-A USDA, Torrey Pines CA 1938? 2710 Citrus depressa (C. pectinifera) (Shekwasha) 539189 1937? 2893 Laranja Cravo (Tangerine Cravo, Cravo) 154 539496 Plant Introduction growing in Fld. 12 nursery 3019 Kara mandarin 2 539498 Hybrid produced at CRC 3020 Wilking mandarin 66 539499 Hybrid produced at CRC 3021 Kinnow mandarin 1 539500 Hybrid produced at CRC 3022 Frua mandarin 539501 Hybrid produced at CRC 3026 Dancy mandarin (Frost nucellar) 32 539683 Nucellar produced at CRC 3085 Szinkom mandarin (ops) 539502 Bureau of Plant Industry, Manila, Philippines 1954 3143 Citrus sunki mandarin (ops) 539678 Hiroshi Yoshimura, Univ. of Osaka, Japan 1956 3144 Citrus keraji (ops) 539269 Hiroshi Yoshimura, Univ. of Osaka, Japan 1956 3147 Citrus leiocarpa (ops) (Koji) 539276 Hiroshi Yoshimura, Univ. of Osaka, Japan 1956 3150 Citrus tachibana (ops) 539679 Ted Frolich, UCLA 1958 3177 Honey mandarin 133 539503 H.B. Frost hybrid of King ´ Willowleaf 1915 3178 Satsuma, Frost nucellar #1 (Owari) 33 539689 H.B. Frost seedling from Rubidoux Tract old-line Satsuma 1916 3226 Scarlet Emperor mandarin (ops) Pankan Ted Frolich, UCLA 1960 3228 Citrus nippokoreana (ops) (Korai Tachibana) 539454 Y. Tanaka, Shizuka Pref., Japan 1957 3239 Citrus reticulata (ops) 254732 Govt. Fruit Exp. Sta., Shillong, India 1959 3260 Soh niamtra mandarin (ops) 254779 Govt. Fruit Exp. Sta., Shillong, India 1959 3280 Citrus succosa (ops) (Jimikan) 539675 Ted Frolich, UCLA 1960 3292 Citrus erythrosa (ops) (Kobeni-mikan) 539190 Ted Frolich, UCLA, originally from Japan as seed. 1960 3297 Citrus tardiva (ops) (Giri-mikan) 539684 Ted Frolich, UCLA, originally from Japan 1960
47 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 4. Mandarin (cont.) 3329 Richard’s Special mandarin (ops) (Ponkan) 539504 Ted Frolich, UCLA 1962 3346 Kunembo mandarin (ops) 539455 Variety Coll., USDA Station, Orlovista, Florida 1960 3363 Beledy mandarin (ops) 120523 Ted Frolich, UCLA Var. Coll. R-5, T-2 1960 3367 Mandarine sanguine seedling 105006 Ted Frolich, UCLA Var. Coll. R-2, T-10 1960 3405 Mandarinette, (ops) 263547 John Carpenter, USDCS, Indio CA 1960 3466 Citrus yatsushiro (ops) 539712 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3558 Fremont mandarin 247 539507 Joe Furr, USDCS, Indio CA 1966 3559 Fairchild mandarin 246 539508 Joe Furr, USDCS, Indio CA 1966 3560 Fortune mandarin 248 539509 Joe Furr, USDCS, Indio CA 1966 3564 Citrus lycopersicaeformis (ops) (Monkey orange) 539347 D. Singh, Indian Agr. Research Inst. New Delhi, India 1962 3568 Pixie mandarin 10 539510 CRC 12D-2-7, new cultivar dev. At CRC 1966 3569 Encore mandarin 156 539511 Hybrid of King ´ Willowleaf produced at CRC, Riverside 1966 3576 Canton mandarin 133733 Ted Frolich, UCLA Var. Block R-6, T-16. 1960 3577 Changsha mandarin (ops) 539512 John Cree, Jr., Texas AES #19, Crystal City TX 1963 3613 Empress mandarin (ops) 539513 South Africa, Dept. of Agric., Nelspruit 1964 3615 Nova mandarin (ops) 282 539514 Joe Furr, USDCS, Indio CA 1968 3616 Page mandarin 58 539710 Joe Furr, USDCS, Indio CA 1968 3649 Bower mandarin hybrid seedling 281 539515 Joe Furr, USDCS, Indio CA 1968 3659 Batangas mandarin (ops) 539516 Seedling from CRC 2333, 8A-26-29 1966 3727 Nagpur “orange” (Ponkan) 49851 Nagpur, Central Provinces, India (via Glenn Dale & CCPP) 1969 3731 Clementine ´ Silverhill Satsuma 539517 USDCS, Indio CA 1971 3738 Necked “orange”, seedling #1 (Som-Chuk) 539518 Thailand – Imported as seed by W. Reuther, CRC 1971? 3752 Som Keowan (ops) 539519 Dept. of Agric., Bangkok, Thailand 1970 3773 Clementine Monreal mandarin 360 247751 Import from Sicily, via Glenn Dale and CCPP 1977 3794 Dobashi Beni Satsuma mandarin 366 358061 Budwood import from Japan, via Glenn Dale, Thrmo, CCPP 1979 3809 Sunburst mandarin 377 539520 Florida, via CCPP 1979 3812 Citrus reticulata (ops) 433931 PR China, via Glenn Dale 1979 3813 Citrus reticulata (ops) 433932 PR China, via Glenn Dale 1979 3816 Kinkoji Unshiu 392 433260 Japan, via Glenn Dale & CCPP 1979 3817 Kobayashi Mikan 393 433261 Japan, via Glenn Dale & CCPP 1979 3820 Okitsu-wase Satsuma mandarin 389 436688 Japan, via Glenn Dale & CCPP 1980 3843 Willowleaf mandarin nucellar 118 539188 Nucellar seedling budline produced at CRC 1933 3844 Cleopatra mandarin (ops) 329 539492 Seedling derived from CRC 1461 1961 3845 King tangor (mandarin) (ops) 235 539457 Seedling produced by Plant Breeding at CRC 1931 3846 Murcott mandarin (ops) 147 539521 USDCS Indio CA – via CCPP 1961 3847 Hill mandarin (ops) 539522 Seed import, probably from India 1965 3848 Nepolitana Satsuma mandarin 365 539690 Seed import from Colombia, South America, via W. Reuther 1967 3849 Ponkan mandarin (ops) (Swatow) 311 539523 Seedling from Ponkan, CRC 2593 1961 3850 Robinson mandarin (Clementine x Orlando) 200, 416 539524 Florida 1962 3851 Lee mandarin (Clementine ´ Orlando) 198 539525 Florida 1962 3852 Som Kaeo II (Crystal mandarin) 539526 Thailand, via W. Reuther, CRC 1970 3853 Som Saa mandarin 539527 Thailand, via W. Reuther, CRC 1970 3880 Citrus yatsushiro 395 433272 Japan, via Glenn Dale & CCPP 1979 3887 Citrus kinokuni - ‘Mukakukishu’ (Kinokuni mandarin) 402 433259 Japan, via Glenn Dale & CCPP 1979 3895 “Yellow Rind” mandarin 539528 PR China, via R. Scora, CRC 1984 3897 Huang Yen Man Chieh mandarin 539529 Seedling of PI 71233, an import from China 1970 3906 Seedless Kishu 433 539530 Japan via Glenn Dale (requested by W.P. Bitters) 1983 3910 Daisy mandarin (Fortune ´ Fremont) 382 539531 USDCS (Fortune ´ Fremont) 1980 3913 Gold nugget mandarin (6D-32-1, Pixie-like) 422 539532 CRC – Budwood supplied by J.W. Cameron 3953 W. Murcott (Afourer) mandarin 462 539533 Morocco 1985 3956 Novelty ´ Ellendale mandarin 523 539534 South Africa 1985 3958 Koster mandarin (Ellendale?, Ellendale Beauty?) (tangor?) 499 539535 South Africa 3960 Ellendale mandarin (tangor?) 464 539536 Australia 1985 3965 NISSV E (mandarin hybrid) 482 539216 South Africa 1985 3972 (Temple ´ Dancy) ´ Encore— JWC Priority #1 485 539537 UCR breeding plot: 6D-11-14 1987 3973 (Temple ´ Dancy) ´ Encore— JWC Priority #2 490 539538 UCR breeding plot: 6D-12-6 1987 3974 (Temple ´ Dancy) ´ Encore— JWC Priority #3 506 539539 UCR breeding plot: 6D-12-2 1987 3975 (Temple ´ Dancy) ´ Encore— JWC Priority #4 509 539540 UCR breeding plot: 6D-11-21 1987 3986 Citrus erythrosa (Kobeni-mikan) 539191 PR China 1987 3987 Clementine Caffin mandarin 491 539184 Morocco 1987 3988 Clementine Sidi Aissa 508 539185 Morocco 1987 3990 Fallglo mandarin (USDA 88-1) 484 539541 Florida – A.H. Whitmore Foundation Farm, Leesburg 1988 3991 Lee ´ Nova (USDA 88-2) 501 539542 Florida – A.H. Whitmore Foundation Farm, Leesburg 1988 3992 Robinson ´ Lee (USDA 88-3) 488 539543 Florida – A.H. Whitmore Foundation Farm- Leesburg 1988 3999 Clementina Fina (Sodea) 498 539186 Morocco (sent by Ray Copeland) 1987 4003 Sun Chu Sha mandarin 497 539544 Florida (Jack Hearn, Orlando) 1989
48 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 4. Mandarin (cont.) 4010 Clementina Oroval 517A 600644 Luis Navarro, Valencia, Spain IVIA 8-34 1990 4011 Clementina Fina 518B 600645 Luis Navarro, Valencia, Spain IVIA 39-3 1990 4012 Clausellina 516A 600646 Luis Navarro, Valencia, Spain IVIA 19-3 1990 4019 Temple ´ Minneola 545 600655 Thermal Plaza 4020 Clementine ´ Pearl 546 600654 Thermal Plaza 4021 Temple ´ Dancy 547 600653 Thermal Plaza 4030 Kuno Wase Satsuma 555 600666 4031 Rubidoux mandarin 572 600664 5. Tangor 2224 Tankan tangor (also considered a mandarin) 539239 Received from CPB 1930 2598 Temple tangor (called Temple orange and 330 539685 F. Heiney, Brawley CA 1935 Royal mandarin in commercial trade) 2792 Altoona 149464 Glenn Dale MD 1945 3018 Dweet tangor 412 539240 Hybrid produced at CRC 3096 H-56 tangor (Willowleaf mand. x Valencia or.) 539241 CRC, Riverside 1957 3149 Citrus benikojii (ops) (tangor) 539178 H. Yoshimura, Univ. of Osaka, Japan 1956 3183 Mency tangor (Mediterranean swt ´ Dancy mandarin) 539242 H.B. Frost hybrid 1915 3274 Citrus funadoko (ops) 539195 Ted Frolich, UCLA 1960 3368 Ortanique tangor seedling 343 539243 Ted Frolich, UCLA 1960 3810 Sue Linda Temple tangor 370 539244 Florida, via CCPP 1978 3875 Tankan tangor 539245 Seed from CRC 2224, old budline Tankan 1958 3946 Miyauchi Iyo (Citrus iyo, Iyo, Miyauchi Iyokan) 455 539256 Japan 1984 3952 Kiyomi tangor H-12 461 539246 Japan 1985 3980 Iyo (Iyomikan tangor) 538 539247 Japan 1987 6. Tangelo 2011 San Jacinto tangelo 539695 Date Gardens, Indio CA 1930 2012 Wekiwa tangelo 539696 Date Gardens, Indio CA 1930 2013 Thornton tangelo 539697 Date Gardens, Indio CA 2418 Sampson tangelo seedling 201 539698 Gordon Wallace, Nurseryman 1933 2543 Sexton tangelo (ops) 539699 Sexton place, Vero Beach FL 1932 2559 Yalaha tangelo 539700 CPB, USDA 1934 2560 Early tangelo 600633 CPB, USDA 1934 2586 Siamelo seedling 138 539701 USDA, WashingtonDC 1937 2603 Clement tangelo 539702 USDA, Sacaton AZ 1936 2604 Seminole tangelo 539703 USDA, Torrey Pines CA 1936 2606 Sunrise tangelo 539704 USDA, Sacaton AZ 1936 2609 Sacaton tangelo 539705 USDA, Sacaton AZ 1936 2746 Webber tangelo 539706 Collected by H.J. Webber 1937 2780 Ugli tangelo (ops) 132372 Jamaica 1942 2787 Williams tangelo 149429 Glenn Dale MD 1945 2788 Sunshine tangelo 149430 Glenn Dale MD 1945 2849 Pearl tangelo 128 539707 Hybrid produced at UCR 3331 Sacaton tangelo (ops) 539708 Originally from USDA, Sacaton AZ. See CRC 2610 1960 3340 Minneola tangelo seedling 174 539709 John Carpenter, USDCS, Indio CA 1961 3874 Orlando tangelo nucellar 19 539711 USDCS, Indio CA, via CCPP 1958 7. Calamondin and hybrid 2592 Calamondin seedling (Citrus mitis, Chi Chieh) 408 539349 USDA, Washington DC 1935 2619 Citraldin (trifoliate ´ Calamondin) 539840 USDA, Sacaton AZ 1936 2867 Calashu (ops) 539215 W.C. Cooper, Weslaco TX 1946 3073 Philippine Calamandarin (ops) 539803 Bureau of Plant Industry, Manila, Philippines 1954 3087 Variegated calamondin 475 539350 Paul Peters, Altadena CA 1954 3656 Calamondin sport 539351 Budsport from CRC 2592, 12D-24-13 1968? 8. Rangpur type 0131 Santa Barbara Rangpur lime 539338 Hale’s ranch, Santa Barbara CA 1912 0452 Kusaie lime 539345 Webber’s #20, from Garrett Wilder, Honolulu 1914 0712 Santa Barbara red lime 539158 J. Sexton, Santa Barbara CA 1915 2318 Philippine red lime (Rangpur type) 539339 From CPB 1930 2319 Australian red lime (Rangpur type) 600626 New South Wales, Australia (via CPB) 1930 2424 Borneo Rangpur lime 539341 From CPB 1930 2451 Bishop red lime (Rangpur type) 539342 Roy K. Bishop, Orange CA 1930? 2875 Japansche citroen (ops). (Rangpur lime type) 600631 G.J.A. Terra, Buitanzorg, Java 1948 3919 Citrus limonia 539336 1975? 3920 Citrus limonia 539337 Import, probably from Turkey 1975? 3932 Citrus limonia V. hangleson 539344 PR China 1985
49 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 9. Navel orange 0065 Seedy navel orange (ops) 539584 Pomona Experiment Station 1910 0287 Navelencia orange 539601 Fawcett’s #100, Florida collection 1914 0574 Smith’s early navel orange 600659 Rubidoux Tract variety block buds from tree 1125 1914 0588 Golden Buckeye navel orange 539582 Rubidoux Tract variety block- buds from tree 53 1914 0609 McFadden ribbed navel 539583 T.L. McFadden, RFD #2, Fullerton CA 1914 0956 Washington navel seedling (seedy) 539585 1916? 0969 Thomson navel orange 539586 USDA #2—thru A.D. Shamel, Agt., Riverside 1916? 0983 Thomson navel orange 539587 USDA #16—thru A.D. Shamel. Agt., Riverside 1916? 1203 Vari navel orange 539558 George C. Roeding 1919 1241-A Parent Washington navel 539559 Buds taken from Parent Washington navel tree (see below) 1918 1241-B Parent Washington navel 376 539560 Buds taken from Parent Washington navel tree (see below) 1920 1379 Golden Nugget navel 539561 A.D. Shamel, USDA 1923 1381 Corrigated Thomson navel orange 539562 A.D. Shamel, USDA 1923 2008 Carter navel orange 15 539563 Armstrong Nurseries 1930 2853 Paradise navel orange 146569 Plant Introduction 1945 3014 Newhall Navel 387 539564 Newhall Ranch 1954 3017 Gillette navel orange (Washington) 381 539565 Fay Gillette, Hemet 1953 3033 Frost Washington navel orange, nucellar 27 539566 Seedling produced at CRC 3135 Fischer navel orange (aka Fisher navel) 106 539567 Armstrong Nurseries, Ontario CA 1958 3181 Ruvel orange (Frost nucellar line) (Rubidoux navel) 539604 Seedling from Rubidoux Tract tree of unknown origin 1915 3305 Navel orange (ops) [44944-A] 539568 William Cooper, USDA, Weslaco FL 1959 3306 Navel orange (ops) [44944-B] 539569 William Cooper, USDA, Weslaco FL 1959 3307 Dream navel (ops) 350 539570 Phillip Reece, USDA, Orlando FL (2-10-7) 1960 3315 Rio Grande navel (ops) 437 539571 William Cooper, USDA, Weslaco TX (Source: TAES 9-13) 1959 3320 Workman navel (ops) (Summernavel) 348 539572 East Highlands Orange, Co. East Highlands CA 1959 3328 Solid Scarlet mandarin (ops) 539505 Ted Frolich, UCLA Variety Block R-8, T-2a 1960 3354 Dry navel orange (seedling of Navelencia) 539573 Variety block, Rubidoux – tree 52. See CRC #585, dead file 1960 3406 Bey navel orange (ops) 262348 John Carpenter, USDCS, Indio CA 1960 3645 Fischer navel (ops) 539574 Seedling from CRC, 8A-26-11 1968 3732 Cluster navel sport 338 539575 CRC Field 7D, R-32, T-9 1967 3791 Atwood navel, old budline 363 600627 Russ Davis, Ivanhoe, via STG & CCPP 1978 3792 Robertson navel, old budline 364 539576 Cairns orchard via STG & CCPP 1978 3803 Lane Late navel 352 362329 Australia, via Glenn Dale & CCPP 1973 3808 Leng navel 353 362330 Australia, via Glenn Dale & CCPP 1973 3903 Fukumoto navel orange 430 539577 Japan via Glenn Dale (requested by W.P. Bitters 1983 3964 Palmer navel (nucellar) 507 539578 Import from South Africa 1985 3971 Skaggs Bonanza navel 515 539579 Lindcove plot – originally from Willits & Newcomb 1988 3994 Cara Cara pink fleshed navel [104 (STG S-1-11)] 471 539580 Florida (originally came to FL from Venezuela from: 1988 Budwood Registration Prog., Winter Haven) 4013 Palmer navel orange 526 600662 South Africa 1985 4015 Navelina navel orange 532 600660 Spain 1990 4022 Navelate navel orange 548 600652 Spain 4023 Robertson navel 563 600672 4024 Spring navel 567 600673 4037 Autumn Gold Australia via B&Z Nursery 4038 Barnfield Australia via B&Z Nursery 4039 Chislett Australia via B&Z Nursery 4040 Powell Australia via B&Z Nursery 4041 Summer Gold Australia via B&Z Nursery 10. Valencia orange 0272 Valencia orange (probably) 339655 Fawcett’s #105, Florida collection 1914 0314 Hart’s late Valencia orange 539662 Fawcett’s #86, Florida collection 1914 0570 Hart’s Tardiff (Valencia) orange 539668 J.W. Mills, Pomona CA buds from tree 1199 1914 1240 Fuzzy Valencia orange-bud sport 539652 Laidlaw grove between Ontario & Pomona Ca 1918? 1518 Valencia coarse orange 539653 Limoneira Ranch, Santa Paula Ca 1925 2689 San Marino Valencia orange 539654 San Marino Ranch, San Marino CA 1938 2750 Olinda Valencia orange seedling 539656 Ollie Smith Olinda, CA (Carbon Canyon) 1939 2776 Seedless Valencia orange 539657 Buds from tree east of Director’s residence 1942 3025 Lue Gim Gong sweet orange (ops) (Valencia) 539658 Seedling produced at CRC 3030 Cutter Valencia nucellar seedling 30 539659 Riverside, CA 3031 Frost nucellar Valencia 240 539660 Seedling produced at CRC 3032 Campbell Valencia seedling 28 539661 Earl Campbell, Fairhaven Street, Orange CA 1942? 3339 Werley Valencia orange o.p seedling 539663 J.C. Werley, Bailey Flats CA 1960 3872 D. Joao (Don Juan) sweet orange (Valencia type) 301 210341 Portugal, imported by J.W. Cameron via Glenn Dale 1963 3955 Midknight Valencia 460 539664 Import from South Africa 1985 3963 Delta Valencia (Delta Seedless) 474 539665 Import from South Africa 1985
50 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 10. Valencia orange (cont.) 3995 Rhode Red Valencia 487 539666 Florida - Budwood Registration Program, Winter Haven 1988 4001 Variegated Valencia orange 539667 UCR Field 5B-3-1 – sport on high southeast 1989 11. Blood orange 2561 Burris blood Valencia orange 539547 Burris grove, Riverside CA 1933 3152 Doble Fina blood orange (ops) 238796 Inst. Nacional de Investigaciones Agronomicas, Spain 1957 3242 Vaccaro blood orange (ops) 218019 Plant Introduction greenhouse, Riverside (CRC) 1959 3401 Sanguine grosse ronde (ops) 539548 Field 6A, R-6, T-9, CRC 1960 3596 Tarocco blood orange (ops) #7 384 539549 Seedling from CRC #2796, produced at CRC 1967 3627 Vaccaro blood orange (ops) 230388 Joe Furr, USDCS, Indio CA 1968 3650 Entre Fina blood orange (ops) 229987 Joe Furr, USDCS, Indio CA 1968 3801 Vainiglia Pink fleshed sweet orange 442 539620 USDCS, Indio CA 1981? 3811 Moro blood orange 539550 Seedling budline grown by W.P. Bitters at CRC 3827 Ruby blood orange (ops) 272 539551 USDCS, via CCPP 1965 3828 Sanguinelli blood orange (ops) 413 539552 USDCS, Indio CA, via CCPP 1960? 3829 Sanguinello a pignu (ops) 265 539553 USDCS, Indio CA, via CCPP 1965 3830 Moro blood orange (ops) 362 539554 USDCS, Indio CA, via CCPP 1975 3977 Washinton Sanguine (Doublefina Amelioree) 521 539556 Morocco (sent by Ray Copeland) 1987 4000 Sanguina Doble Fina 510 539557 Morocco (sent by Ray Copeland) 1987 4018 Tarocco blood orange 544 600656 4032 Bream Tarroco blood orange 576 600665 12. Other sweet orange and hybrid 0071 Jaffa orange 539651 C.D. Hubbard, San Fernando CA 1910 0245 Bessie sweet orange 539594 Fawcett’s #70, Florida collection 1914 0274 Maltese oval sweet orange 539597 Fawcett’s #96, Florida collection 1914 0281 Joppa late sweet orange 539599 Fawcett’s #89, Florida collection 1914 0292 Homosassa sweet orange 539602 Fawcett’s #87, Florida collection 1914 0321 Imperial variegated sweet orange 539606 Fawcett’s #55, Florida collection 1914 0366 Star sweet orange 539615 Fawcett’s #58, from Soar’s nursery, Miami FL 1914 0371 Orange of Heaven (Laranga de Ciel) (acidless orange) 539616 Fawcett’s #63, from Heintz, City Point FL 1914 0590 Maltese Oval orange 539649 Rubidoux Tract variety block- buds from tree 55 1914 0591 St. Michael Paperrind sweet orange 539650 Rubidoux Tract variety block- buds from tree 63 1914 0950 Lima sweet orange (acidless) 428 37793 Col. J. de Tieve e Argollo, Agua Comprida, Bahia, Brazil – through USDA 1916? 1045 Selecta sweet orange (Laranja selecta) 37782 Miguel de Teives e Argollo’s grove, Roma, Bahia, Brazil – through USDA 1916? 1106 Koethen sweet orange 539588 E.R. Koethen grove, Brockton Ave., Riverside 1917 1512 Bidwells Bar sweet orange seedling (Oroville sweet) 539589 H.E. Drobish, County Agent, Oroville CA 1925 1693 Bessie sweet orange seedling 539590 From progeny in 1924 nursery 1927 1696 Homosassa sweet orange seedling 539591 From progeny in 1924 nursery. 1927 2369 East Highlands sweet orange 539592 East Highlands Orange Co.- Winn 58-7 1931 2373 Dalandan sweet orange 539593 Philippine Islands (via CPB) 1930 2550 Wetumpka sweet orange (ops) 539595 Wetumpka Fruit Co., Lowell FL 1932 2602 Dillar sweet orange 539596 USDA, Sacaton AZ 1936 2802 Argentina sweet orange (ops) 539598 Santa Ana Mission, North Argentina 1940 2856 Cadenera Fina sweet orange 539600 UCLA 1945? 3083 Sathgudi sweet orange (ops) 539603 Ed Pollock, Parkes, N.S.W., Australia 1954 3182 Trovita strain A (Early sweet orange) 116 539605 Seedling from the Rubidoux Tract “Washington navel” 1915 3245 Capucin sweet orange 539607 Ted Frolich, UCLA Variety Coll. R-1, T-6 1960 3246 Cadena Punchosa sweet orange 105009 Ted Frolich, UCLA Variety Coll. R-2, T-4 1960 3249 Espagnole sans pepins sweet orange (ops) 123983 Ted Frolich, UCLA Variety Coll. R-7, T-9 1960 3251 Khailily (white) sweet orange 539608 Ted Frolich, UCLA 1960 3272 Berna sweet orange (ops) 539609 Ted Frolich, UCLA Variety Coll. R-4, T-6 1960 3347 Curry early sweet orange seedling 539610 John Carpenter, USDCS, Indio CA 1961 3373 Precoce de Valence? (ops) 105008 Cooper, Delta Lake TX 1958 3403 Aziza sweet orange (ops) 262347 John Carpenter, USDCS, Indio CA 1960 3467 Citrus ujukitsu (ops) 539687 Shizuoka Prefecture, Japan (via W.P. Bitters, CRC) 1963 3476 Citrus shunkokan (ops) 539546 Shizuoka pref., Shimizu-shi, Japan (via W.P. Bitters, CRC) 1963 3584 Shamouti seedling (seedling of Sarah) 539611 Joe Furr, USDCS, Indio CA 1962 3599 Perao orange #1 (ops) 539612 De Citricos De ICA Tulio, Ospina, Medellin, Colombia 1967 3624 Orange de Nice (ops) 539613 Seedling of CRC #3276, 8A-12-39 1966 3625 Ovale orange (ops) 539614 Alfredo Ferrand, Peru 1966 3630 Biondo Riccio sweet orange (ops) 230379 Joe Furr, USDCS, Indio CA 1968 3632 Cadenera orange (ops) 284 230080 Joe Furr, USDCS, Indio CA 1968 3746 Shamouti orange, Israeli seedling #1 316 539617 Budwood importation from Israel via Glenn Dale & CCPP 1971? 3754 Selecta orange (ops) 539618 Seedling from 8A-5-21, CRC 1045 1970 3787 Fuya Menuda sweet orange (ops) 539619 Guillermo Colon, Majorca, Baleric Is., SPAIN via Beltsville 1978 3802 Akcay Sekeri orange (Crescent) 394 539621 Turkey, via W. Reuther 1968
51 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 12. Other sweet orange and hybrid (cont.) 3807 Verna orange (ops) 244968 Spain, via Glenn Dale & CCPP 1961 3814 Citrus sinensis (ops) 433933 PR China, via Glenn Dale 1979 3858 Pineapple sweet orange (ops) 222 539622 USDCS, Indio CA 1963 3859 Indian River sweet orange (ops) 539623 Seedling from CRC 3555, old budline Indian River 1958 3860 Catlin sweet orange (ops) 494 539624 Seedling of CRC 1414, old budline Catlin 1961 3861 Madam Vinous sweet orange (ops) 307 539625 John Carpenter, USDCS, Indio CA 1967 3862 Hamlin orange (ops) (Norris) 539626 USDCS, Indio CA 1961 3863 Olivelands sweet orange (ops) 539627 Seedling from CRC 2884, old budline Olivelands sweet 1960 3864 Pera orange (ops) 539628 Seedling from CRC 2696, old budline Pera 1960 3865 Marr’s Early sweet orange (ops) 173 539629 USDCS, Indio CA, via CCPP 1962 3866 Biondo Comune sweet orange (ops) 539630 Frank Russo, Sicily, via Glenn Dale & CCPP 1961 3867 Rotuma Island sweet orange (ops) 317 539631 Rotuma Island, via Capt. Polkinghorn & W. Reuther, CRC 1961 3868 Salustiana orange (ops) 221 539632 USDCS, Indio CA, via CCPP 1963 3869 Tahiti sweet orange (ops) 539633 Seed from Tahiti 1964 3870 Finike sweet orange (ops) 539634 Seed supplied by W.P. Bitters 1963 3871 Macetera sweet orange (ops) 285 539635 John Carpenter, USDCS, Indio CA, via CCPP 1966 3873 Parson Brown sweet orange (ops) 539636 Seed from USDCS 54-81, Indio CA 1961 3896 Cipo orange (ops) 539637 Brazil via John Carpenter & George Quesada, Novato CA 1984 3898 Blanca Macetera orange 244965 Seedling of PI 244965, an import from Spain 1970 3921 Ovale o Calabrese orange 539638 Import, country of origin not known. 1975? 3933 Citrus sinensis 539639 PR China 1985 3934 Citrus sinensis 539640 PR China 1985 3935 Citrus sinensis “:Jincheng” 539641 PR China 1985 3936 Citrus sinensis “Xuegan” 539642 PR China 1985 3937 Citrus sinensis “Xinhuicheng” 539643 PR China 1985 3982 Xianfengcheng 495 539644 PR China 1987 3983 Jincheng 500 539645 PR China 1987 3984 Xuegan 574 539646 PR China 1987 3985 Xinhuicheng 575 539647 PR China 1987 3998 US 119 (Duncan gft ´ trifol.) ´ Succory sweet orange 489 539832 Florida (brought back by D. Gumpf) 1988 4002 Ambersweet orange 496 539648 Jack Hearn, Orlando FL 1989 13. Sour orange and hybrid 0571 Bouquet des Fleurs sour orange 539174 Buds from hedge in rear of building of Old Station 1914 0622 Variegated sour orange 539175 Murphy Oil CO. nursery, Whittier CA 1914 0628 Standard sour orange 95 539176 Murphy Oil CO. nursery, Whittier CA 1914 0656 Daidai-double calyx sour orange 539681 C.C. Chapman grove, Fullerton CA 1915 0660 Paraguay bittersweet orange 31881 USDA, Chico Garden 1915 0693 Orogold sour orange hybrid (ops) 539237 Oroville CA 1915 0760 Citrus vulgaris (ops) (Japanese orange) 539177 P.J. Wester, Lamao, Bataan, Philippine Islands 1916 1588 Orlando bittersweet orange seedling 539159 W.W. Youthers, USDA, Orlando FL 1926 1689 Brazilian sour orange seedling 539161 From progeny in 1924 nursery. 1927 2192 Stow #20 bittersweet orange (ops) 539162 J.W. Porter grove near Hypoluxo, Palm Beach Co. FL 1928 2375-B Chinotto orange 539451 From CPB 1930 2438 Tunisian sour orange (ops), Nabeul 85728 Nabeuil, SE of Tunis, collected by Fawcett (No. 45) 1930 2541 Dummett bittersweet orange (ops) 539160 Florida 1932 2588 Citrus taiwanica (Nansho daidai) 539680 USDA, Washington DC 1935 2624 Keen sour orange #1-10 539163 Bonita CA 1936 2715 Granitos sour orange seedling, op, Argentina 124169 Fawcett #425, Bella Vista, Argentina 1937 2717 Olivelands Sour orange 539164 Faw. #363 Olivelands Jensen 6C-54-3 3059 Citrus Kharna (ops) 213224 H.S. Gentry, Wandriker Farms, Poona, Mahhamaristra State (India?) 1954 3079 Gabbuchinee (ops) 539225 Ed Pollock, Parkes, N.S.W., Australia 1954 3225 Citrus maderaspatana (ops) (Kichili) 539348 Ted Frolich, UCLA Blk D, R-28, T-1. 1959 3235 Citrus natsudaidai (Kawano Strain) (ops) 539453 Hiroshi Yoshimura, Tanaka Inst., Univ. of Osaka, Japan 1957 3257 Citrus sulcata (ops) (Sanbokan) 539677 Ted Frolich, UCLA 1960 3289 Citrus aurantium var. Salicifolia 539166 12D-22-6, CRC 3290 Myrtifolia sour orange 539450 12D-22-15, CRC 3473 Citrus rokugatsu (ops) (Rokugatsu-mikan) 539545 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3565 Citrus canaliculata (ops) (Kikudaidai) 539181 Ted Frolich, UCLA 1962 3578 Pursha lime ´ Chinotto 539226 Joe Furr, USDCS, Indio CA 1962 3607 Tosu (ops) (Citrus neo-aurantium) 316538 Hort. Res. Sta., Okitsu, Japan (via W.P. Bitters, CRC) 1966 3611 Konejime (ops) (Citrus neo-aurantium) 316537 Hort. Res. Sta., Okitsu, Japan (via W.P. Bitters) 1966
3681 (53-1-16 Clem ´ Hamlin) ´ Chinotto, F1 539227 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3683 (53-1-16 Clem ´ Hamlin) ´ Chinotto, F1 539228 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3684 (53-1-16 Clem ´ Hamlin) ´ Chinotto, F1 539229 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3702 (53-1-16 Clem ´ Hamlin) ´ Chinotto, F1 539230 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3703 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539231 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
52 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 13. Sour orange and hybrid (cont.)
3705 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539232 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3706 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539233 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3709 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539234 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3712 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539235 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968?
3715 (53-1-16 Clem ´ Hamlin) ´ Chinotto F1 539236 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3728 Chinotto hybrid 539167 Joe Furr, USDCS, Indio CA (Furr’s Salt plot) 1970 3855 Rubidoux sour orange (ops) 539168 Seedling from CRC 711, old budline Rubidoux sour 1961 3856 Seville sour orange 539169 Seedling budline from CRC 1589, old budline Seville 1961 3857 Chinotto sour orange (ops) 427 539452 Seedling of CRC 2375, old budline Chinotto 1961 3929 Citrus aurantium “Goutoucheng” (Leather-head sour) 539170 PR China 1985 3930 Citrus aurantium “Zhuluan” 539171 PR China 1985 3981 Zhuluan 554 539172 PR China 1987 4004 Gou Tou sour orange (Leather-head sour) (Goutoucheng) 539173 1981 14. Pummelo (shaddock) 0302 Tresca “grapefruit” pummelo 539386 Fawcett’s #125, Florida collection 1914 0448 Moanalua pummelo 539407 Webber’s #16, from Mr. Damon, Moanalua Gardens, Honolulu 1914 0578 Fleming’s shaddock 539408 Rubidoux Tract variety block – buds from tree 1187 1914 0640 Siamese pummelo 600632 USDA Plant Introduction Garden, Chico 1915 0644 Philipine pummelo (ops) 539409 P.J. Wester, Lamao Bataan, Phillipine Islands 1915 1208 Roeding’s Pink pummelo 539352 George C. Roeding’s nursery 1919 1212 Chinese pummelo 46132 Ichang, Hupeh, China 1919 1224 Chinese pummelo 46121 Frank N. Meyer, FHB #23783, Hupeh, China 1919 1225 Hunan pummelo (ops) 539353 American Consul, Changsha, China- FHB #15097 1919 2236 Sunshine pummelo 159 539354 Sunshine Ranch, San Fernando CA 1930? 2240 Siamese pummelo (acidless) (aka Siamese Sweet) 443 539355 From CPB 1930 2241 Unnamed pummelo (Siam) 161 539356 From CPB 1929? 2242 Kao Panne pummelo (Kao Pan) 539357 Siam (via CPB) 1930 2243 Kao Panne pummelo (Kao Pan) 539358 Siam (via CPB) 1930 2244 Pink pummelo (Java) 539359 From CPB 1929/30 2245 Red pummelo (Java) 539360 From CPB 1929 2246 Pink pummelo 160 539361 From CPB 1930 2248 Unnamed pummelo 539362 From CPB 1930 2249 Kao Panne pummelo 539363 Siam (via CPB) 1930 2338 Red Fleshed pummelo 539364 From CPB 1930 2340 Citrus grandis- Unnamed 539365 From CPB 2341 Karn Lau Yau pummelo 539366 From CPB 1930 2342 Pong Yau pummelo 539367 From CPB 1930 2346 African pummelo 539369 From CPB 1930 2347 Deep red pummelo 539370 From CPB 1930 2348 Pin Shan Kong Yau pummelo 539371 From CPB 1930 2349 Kao Panne pummelo (Kao Pan) 539372 Siam (via CPB) 1930 2350 Kao Ruan Tia pummelo 539373 From CPB 1930 2351 Kau Ruan Tia pummelo From CPB 1930 2352 Kao Phuang pummelo 539375 From CPB 1930 2353 Nakon Chaisi pummelo 539376 From CPB 1930 2355 Unnamed pummelo, Siam 539377 From CPB 1930 2356 Kao Panne pummelo, Siam 539378 From CPB 1930 2421 Siamese pummelo 539379 From CPB 1930 2453 Citrus grandis- Unnamed 539380 From CPB 1930 2487 Alemoen pummelo (ops) 97930 Suriname, South America? 1932 2583 Tau Yau pummelo 539382 USDA, Washington DC 1935 2596 Arajon pummelo 539383 F. Heiney, Brawley CA 1935 2752 PanDan Pummelo 539385 Source: Robinson 1938? 3067 Sweet pummelo (ops) 539388 Ed Pollock, Molong Road, N.S.W. Australia 1954 3148 Citrus sino-grandis (ops) (Otomikan) 539669 H. Yoshimura, Univ. of Osaka, Japan 1956 3224 Chandler pink pummelo 11 539389 CRC 11B-5-4, A hybrid of Siamese Pink ´ Siamese Sweet 1959 prod. at CRC, Riverside 3282 Citrus grandis? (unknown) (ops)- New Guinea 539390 Dept. Agr, Stock & Fisheries, Port Moresby, Papua New Guinea 1956 3805 Reinking pummelo 274 539391 USDCS, Indio CA, via CCPP 1965 3806 Tahitian pummelo 342 539392 Hawaii, via CCPP 1971 3926 Kao Phuang pummelo 446 539393 Import from Hawaii (Special permit from Sacramento 1984 3927 Thong Dee pummelo 447 539394 Import from Hawaii (Special permit from Sacramento) 1984 3928 Itoshima Bankan 448 539395 Glenn Dale Quarantine Facility, import from Japan 1984 3940 Haiku B pummelo 449 539369 Import from Hawaii (Special permit from Sacramento) 1984 3944 Kawachi-bankan pummelo 453 539397 Import from Japan 1984 3945 Mato Buntan (Mato) pummelo 454 539398 Import from Japan 1984
53 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 14. Pummelo (shaddock) (cont.) 3947 Suisho Buntan (Suisho) pummelo 456 539399 Import from Japan 1984 3948 Kao Pan pummelo 457 539400 Import from Hawaii (Special permit from Sacramento) 1984 3949 Pauthel pummelo 458 539401 Import from Hawaii (Special permit from Sacramento) 1984 3950 Banokan 459 539402 Import from Japan 1983 3951 Hirado Buntan (Hirado) pummelo 467 539403 Import from Japan 1983 3959 Egami Buntan (Egami, Ogami) pummelo 477 539404 Import from Japan 1985 3961 Banpeiyu (Pai You from Taiwan) pummelo 478 539405 Improt from Japan 1985 3978 Kinokawa Buntan 522 539406 Japan 1987 3979 Anseikan 479 539673 Japan 1987 4027 US 145 Thong Dee pummelo 569 600670 Florida 4028 Rubidoux pummelo 570 600663 15. Pummelo hybrid 0042 Shaddock x St. Michael or. seedling 539224 F. M. Reed, Riverside CA 1910 0579 Moli Kurikuri (Citrus grandis ´ C. macroptera?) (Citrus vitiensis?) 539691 Rubidoux Tract variety block – buds from tree 1188 1914 1462 Cuban shaddock 539410 W.T. Swingle, USDA 1924 1481 Lemelo 539411 W.T. Swingle, USDA 1924 1775 Lemon shaddock seedling (Lemelo) 539412 N/A 1927 2343 Philippine pummelo hybrid 539368 From CPB 1930 2608 Red Aranyan pummelo 539384 USDA, Torrey Pines Station CA 1936 3066 Sour pummelo (ops) 539387 Ed Pollock, Molong Road, N.S.W., Australia 1954 3092 Citrus tamurana (ops) (Hyuganatsu) (New Summer or.) 539682 J.R. Creech, Kurume, Kyushu, Japan 1955 3133 Gadadehi (Pummelo or pummelo hybrid?) 539165 Dept. of Agric., Lyallpur, India 1954 3275 Citrus hiroshimana (ops) (Natsuzabon) hybrid 539201 Ted Frolich, UCLA 1960 3464 Citrus tengu (ops) (Shigetomi, Kinkunebu) 539686 Shizuoka Prefecture, Japan (via W.P. Bitters (CRC)) 1963 3465 Citrus obovoidea (ops) (Marumero, Kinkoji) 539458 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3470 Citrus otachibana (ops) (large tachibana) 539459 Shizuoka Prefecture, Japan (via W.P. Bitters, CRC) 1963 3488 Yuma Ponderosa “lemon” 410 539218 Yuma Mesa Citrus Exp. Station, Yuma AZ 1964 3555 Frua mandarin x low acid pummelo hybrid (Cocktail grapefruit) 127 539219 Hybrid developed at CRC, original code: 11C-38-4 1966 3556 Citrus rugulosa (Attani) 214012 India via Plant Intro. Station, Glenn Dale MD 1954 3781 Tahitian pummelo ´ Star Ruby grapefruit 539221 Joe Furr, USDCS. Indio CA. ? 1974 3904 Citrus hiroshimana (Natsuzabon) 431 539200 Japan via Glenn Dale (requested by W.P. Bitters) 1983 3905 Asahikan 432 539150 Japan via Glenn Dale (requested by W.P. Bitters) 1983 3907 Hassaku (Citrus hassaku, Beni Hassaku) 434 539199 Japan via Glenn Dale (requested by W.P. Bitters) 1983 3941 Puma hybrid (Pummelo ´ grapefruit) 450 539222 Import from Hawaii (Special permit from Sacramento) 1984 3942 Hassaku 451 539223 Japan 1984 4026 Pomlit pummelo hybrid (Djeroek Deleema Kopjor) 566 600667 South Africa 4029 Unnamed grapefruit/pummelo hybrid 571 16. Grapefruit 0248 Royal grapefruit 539465 Fawcett’s #123, Florida collection 1914 0297 Triumph grapefruit 539469 Fawcett’s #124, Florida collection 1914 0343 Grapefruit seedling 245 539475 Fawcett’s #44, Florida collection 1914 0596 Imperial grapefruit 539488 Rubidoux Tract variety block – buds from tree 68 1914 1198 Foster Pink grapefruit 539460 George Roeding Nurseries 1919 1565 Marsh seedy grapefruit 539461 Dixon Ranch 1925 2010 Marsh pink grapefruit 539462 Date Gardens, Indio CA 1930 2014 Cecily grapefruit 539463 Date Gardens, Indio CA 1930 2784 Jochimsen grapefruit (ops) 539466 Mr. Jochimsen, Baseline Ave., La Verne FL 1942 2850 Redblush grapefruit (ops) #3 31 539467 Texas 2885 Wheeny grapefruit 539468 New Zealand 1943 3068 Hall grapefruit 539470 Hall Orchard, Upland CA 1955 3128 Reed Marsh grapefruit (ops) 142 539471 J.F. Reed, Taft CA 1958 3139 Camulos grapefruit 539472 12C-15-1, CRC (Shoot from root) 1957 3184 Frost nucellar Marsh grapefruit 29 539473 H.B. Frost nucellar seedling 1915? 3398 Nicholson “navel” grapefruit (ops) 539474 D.J. Nicholson, Orlando FL 1960 3637 Cecily grapefruit (ops) 539476 Seedling of CRC #2014, 8A-2-29 1966 3638 Hudson Foster grapefruit (ops) 308 539477 Joe Furr, USDCS, Indio CA 1968 3770 Star Ruby grapefruit 355 539478 USDCS, Indio CA via CCPP 1977 3774 “Genetic Dwarf” grapefruit 361 539479 Limb sport of Marsh, found at Yuma AZ 1977 3804 Whitney Marsh grapefruit, old budline 148 539480 Whitney Ranch, Oasis CA, via CCPP 1961 3831 Shambar grapefruit (ops) 269 539481 Willits & Newcomb, Thermal CA 1965 3832 Duncan grapefruit 539482 Florida, via W. Reuther, UCR 1962? 3883 Perlis #2 grapefruit 398 433294 Hawaii, via Glenn Dale & CCPP 1979 3886 Perlis #1 grapefruit 401 433293 Hawaii, via Glenn Dale & CCPP 1979 3914 Henderson Ruby grapefruit 465 539483 Texas 1985 3915 Ray Ruby grapefruit 466 539484 Texas – see note on CRC 3914 card. 1985 3916 Rio Red Grapefruit 440 539485 Texas – see note on CRC 3914 card. 1985
54 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 16. Grapefruit (cont.) 3968 Tetraploid grapefruit 539486 CRC Breeding project- Field 6E, Stand 25, tree 3 1987 3993 Flame grapefruit seedling [800-1-26-71] 470 539487 Florida - Budwood Registration Program, Winter Haven 1988 17. Grapefruit hybrid 2381 Poorman orange (Cudebeck strain) (New Zealand gft.) 539464 From CPB 1930 3602 Oroblanco grapefruit hybrid (Patented by U.C.) 309 539202 Hybrid developed at CRC, original source: 6C-26-20 1968 3764 Melogold (UC patented hybrid) 323 539203 Hybrid produced at CRC, original designation: 6C-26-18 1975 3769 New Zealand grapefruit (Poorman orange) 354 372058 Import from New Zealand, via Glenn Dale & CCPP (budwood) 1977 3909 Chironja 436 539489 Puerto Rico via Glenn Dale (request, W.P. Bitters) 1983 3962 Rex Union 511 539490 South Africa 1985 18. Miscellaneous Citrus species 2434 Citrus pennivesiculata (C. moi, Gajanimma) 38388 From CPB 1930 3146 Citrus yuko (ops) 539713 Hiroshi Yoshimura, Univ. of Osaka, Japan 1956 3163 Citrus indica (ops) (hybrid) 539254 Ted Frolich, UCLA 1958 3175 Citrus species (ops) 213349 H.S. Gentry, Chettalli, Coorg State, India 1954 3469 Citrus hanayu (ops) 539198 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3474 Citrus intermedia (ops) (Yamamikan) 539255 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3574 Citrus miaray (ops) 539448 Phil Reece, Orlavista Field Sta., Orlando FL 1962 3780 Citrus halimii 539196 Malaysia, via R. Scora, CRC 1971 3797 Citrus hongheensis (ops) (Honghe papeda) 539672 Prof. Tsuin Shen, Peking Agric. Univ., Peking, PR China 1980 3900 Citrus halimii 539197 BOH Plantation, Fairley Estates, Cameron Highlands, West Malaysia 1985 19. Citrus subgenus Papeda and hybrid 0432 Citrus hystrix, Cabuyao 539250 P.J. Wester, Philippine Islands 1914 0767 Citrus webberii var. Montana (Weeping Philippine hybrid) (ops) 539449 P.J. Wester, Lamao, Bataan, Philippine Islands 1916 1215 Ichang lemon (ops) (Shangyuan) 187 45534 Frank N. Meyer, FHB #23067, PR China 1919 1216 Citrus junos (Yuzu or Kansu) 45945 Frank N. Meyer, FHB #23721 & 23942, PR China, 1919 in Hubei Prov. along Yangtze river. 1219 Ichang lemon seedling 46128 Frank N. Meyer, FHB #23790, PR China 1919 1455 Citrus webberii (Kalpi, Nogapog) (cutting A) 539692 W.T. Swingle, USDA 1456 Citrus webberii (Kalpi, Nogapog) (cutting A) 539693 W.T. Swingle, USDA 1924 2316 Citrus excelsa 539192 Philippine Islands (via CPB) 1930 2320 Citrus longispina (Talamisan) (probably not C. longispina) 539346 Philippine Islands (via CPB) 1930 2327 Citrus ichangensis 539251 From CPB 1930 2427 Davao lemon (Citrus davoensis) 539187 From CPB 1930 2431 Citrus ichangensis 539252 PR China (via CPB) 1930 2454 Citrus hystrix 539248 From CPB 1930 2892 Citrus excelsa?, Philippines 539194 F.E. Gardner, Orlando FL 1947 3052 Citrus latipes (ops) (Khasi papeda) 230987 Khasi Hills, Assam, India 1954 3056 Citrus species (ops) (Papeda type) 214467 Rupchand, Mawknland via Schillang, Assam, India 1954 3103 Citrus hystrix 539249 Punjab Agr. College, Lyallpur, Pakistan 1955 3203 Soh niangrang (ops)? 254733 Fruit Exp. Sta., Shillong, India 1959 3471 Citrus sudachi (ops) 539676 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3605 Samuyao (microcarpa (ops)) 539694 College of Agric., College, Laguna, Philippines 1967 3612 Kulobot (ops) (Papeda hybrid) 539217 Phil. Coll. of Agric., Los Banos, Philippine Islands 1966 3765 Citrus excelsa 539670 Dick Hamilton, University of Hawaii 1972 3793 Unknown species of papeda 539671 Dick Hamilton, Hawaii 1978 3842 Citrus macrophylla seedling 313 539182 Willits & Newcomb, Thermal CA, via CCPP 1968 3931 Citrus ichangensis 539253 PR China 1985 3943 Kabosu 452 539674 Japan 1984 4016 Unknown species of papeda (papeda hybrid) Dick Hamilton, Hawaii 1978 20. Kumquat and hybrid 0132 Nagami kumquat 539728 Hale’s ranch, Santa Barbara CA 1912 1044 unnamed-probably a kumquat hybrid 539725 USDA 1916? 1440 Thomasville citrangequat 539849 W.T. Swingle, USDA 1924 1471 Meiwa kumquat seedling (F. crassifolia) 539721 W.T. Swingle, USDA 1924 3237 Fortumella japonica (ops) (Marumi, Maru-kinkan) 539727 John Carpenter, USDCS, Indio CA 1957 3259 Citrangequat 19-15-7 539851 Joe Furr, USDCS, Indio CA. From Yuma NF 1958 3295 Procimequat? 539805 John Carpenter, USDCS, Indio CA 1957 3360 Nippon orangequat seedling 149453 Ted Frolich, UCLA Var. Coll. R-5, T-13 1960 3475 Fortunella obovata (ops) (Fukushu kumquat, Chojukinkan) 539730 Okitsu, Shizuoka Pref., Japan (via W.P. Bitters, CRC) 1963 3642 Sinton citrangequat (ops) 539853 Joe Furr, USDCS, Indio CA 1968 3759 Nagami cross (with Dancy?) AKA: Indio mandarinquat 355? 539726 John Carpenter, USDCS, Indio CA 1972 3789 Fortunella hindsii 539723 W.B. Chapman, League City TX 1975 3790 Fortunella hindsii 539724 Bruce Bartholomew, Berkeley Botanic Garden, CA 1978 3818 Fortunella crassifolia (Meiwa) 433934 PR China, via Glenn Dale 1979 3833 Meiwa kumquat (ops) 306 539722 USDCS, Indio CA, via CCPP 1967
55 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 20. Kumquat and hybrid (cont.) 3877 Nagami kumquat 276 539729 John Carpenter’s yard, Indio CA, via CCPP 1965 3901 Fortunella polyandra 539731 Botanic Garden, Univ. of Kuala Lumpur, Malaysia 1985 21. Trifoliate 0838 Rubidoux trifoliate orange 83 539791 Rubidoux Experiment Station 1916 1498 USDA trifoliate ( lf ) 539750 W.T. Swingle, USDA 1924 1717 Pomeroy trifoliate seedling (lf) 84 539751 Pomeroy’s 1927 2552 Webber-Fawcett #22 trifoliate orange seedling 539572 Experiment Station, Gainesville FL 1932 2554 Barnes trifoliate orange seedling (sf) 164 539573 L.B. Barnes grove, Gainesville FL 1932 2861 Texas trifoliate (ops) (sf) 539755 E. Mortensen, Winter Haven TX 2862 Florida trifoliate (ops) 539756 F.E. Gardner, Orlando FL 3151 Australian trifoliate (ops) 240121 Dept. Agr. Sydney, N.S.W. Australia 1957 3206 Argentina trifoliate (lf) 539757 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3207 Towne G trifoliate (lf) 539758 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3209 Rich 12-2 trifoliate (lf) 539759 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3210 Kryder 16-6 trifoliate 539760 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3211 Rich 22-2 trifoliate (sf) 539761 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3212 Kryder medium trifoliate (lf) 539762 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3213 Kryder 60-2 trifoliate (lf) 539763 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3215 Kryder 55-5 trifoliate 539764 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3217 Kryder 15-3 trifoliate (lf) 539765 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3218 Kryder 8-5 trifoliate (lf) 539766 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3219 Kryder 28-3 trifoliate (lf) 539767 Joe Furr, USDCS, Indio CA from Yuma AZ 1958 3330-A Flying Dragon trifoliate (ops) (Poncirus trifoliata var. Monstrosa) 383 539768 Hiroshi Yoshimura, Univ. of Osaka, Japan 1958 3330-B Flying Dragon trifoliate variant (ops) (Poncirus trifoliata var. Monstrosa) 539769 Hiroshi Yoshimura, Univ. of Osaka, Japan 1958 3338 Benecke (Beneckie) trifoliate (ops) (lf) 539770 Domingo Hardison, Santa Paula CA 1958 3345 Christiansen trifoliate (ops) (lf) 539771 Domingo Hardison, Santa Paula CA 1958 3411 Jacobson trifoliate (ops) (sf) 539773 L. Jacobson Ranch, Placentia CA 1961 3412 Yamaguchi trifoliate (ops) (lf) 539774 Yamaguchi grove, Ontario CA 1961 3484 Frost tetraploid 4x trifoliate 539775 SCFS Bl. 24, R-23, T-3 1965 3485 Rich 16-6 trifoliate 539776 SCFS Bl. 24, R-20, T-6 1965 3486 Kryder 55-1 trifoliate (lf) 539777 SCFS Blk 24, R-21 T-2 1965 3547 Benoit trifoliate orange 539778 SCFS 24-23-12 1965 3548 English large trifoliate orange (sf) 539779 SCFS 24-20-25 1965 3549 Simmons trifoliate seedling 539780 SCFS 24-23-24 1965 3570 Ronnse trifoliate (sf) 539781 SCFS 24-20-22 1965 3571 Taylor trifoliate (sf) 539782 SCFS 24-21-24 1965 3572 Towne “F” trifoliate (lf) 539783 SCFS 24-20-14 1965 3586 Kryder 5-5 trifoliate (lf) 539784 SCFS 24-21-5 1965 3587 Rich 7-5 trifoliate (lf) 539785 SCFS 24-22-3 1965 3588 Marks trifoliate 539786 SCFS 24-23-11 1965 3795 Hiryo (Flying Dragon trifoliate) 539671 Iwamassa, Saga, 840, Japan 1978 3876 English Dwarf trifoliate (ops) 539788 English Ranch, Lindsay CA 1958 3882 Poncirus trifoliata var. Hiryo (Flying Dragon) 397 433262 Japan, via Glenn Dale & CCPP 1979 3888 Monoembryonic Poncirus trifoliata 403 433263 Japan, via Glenn Dale & CCPP 1979 3938 Poncirus trifoliata #27 539789 PR China 1985 3939 Poncirus trifoliata #26 “Nanjing” 539790 PR China 1985 4006 “Big-leaf” trifoliate 600647 Hunan Horticultural Institute, PR China 1989 4007 “Little-leaf” trifoliate 600648 Hunan Horticultural Institute, PR China 1989 4008 “Little-leaf” trifoliate 600649 Hunan Horticultural Institute, PR China 1989 4009 Trifoliate (open pollinated) 600650 Guandong, PR China 1989 4017 Small Leaf trifoliate 541 600657 PR China 1990 22. Trifoliate hybrid 0271 Cunningham citrange 539812 Fawcett’s #142, Florida collection 1914 0275 Savage citrange 249 539813 Fawcett’s #135, Florida collection 1914 0276 Sanford citrange 539814 Fawcett’s #141, Florida collection 1914 0301 Rusk citrange 13002 Fawcett’s #137, Florida collection 1914 1436 Citradia hybrid (cutting A) 539833 W.T. Swingle, USDA 1924 1437 Citradia hybrid (cutting A) 233 539834 W.T. Swingle, USDA 1924 1438 Citradia hybrid (cutting A) 539835 W.T. Swingle, USDA 1924 1441 Rusk citrange 539809 W.T. Swingle, USDA 1924 1447 Citrangor seedling 539836 W.T. Swingle, USDA 1924 1448 Citremon 539837 W.T. Swingle, USDA 1924 1449 Citremon (cutting B) 150 539838 W.T. Swingle, USDA 1924 1452 Citrumelo seedling 105 539822 W.T. Swingle, USDA 1924 1459 Troyer citrange (Citruvel) seedling 86,88 539810 W.T. Swingle, USDA 1924
56 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 22. Trifoliate hybrid (cont.) 1463 Morton citrange 539811 W.T. Swingle, USDA 1924 2618 Citrandarin (Trifoliate ´ mandarin) 539839 USDA, Sacaton AZ 1936 2748 Morton citrange 539754 CPB? 1940 2863 Carrizo citrange (ops) 97 150916 Plant Introduction 1945? 2865 Uvalde citrange 150917 Plant Introduction 1943 2866 Citrange #1416 (ops) 539815 W.C. Cooper, Weslaco TX 1947 3205 Yuma citrange 539816 Joe Furr, USDCS, Indio CA. Originally from Yuma AZ 1958 3336 Spanish sweet orange ´ Poncirus trifoliata seedling 539817 Albert Newcomb Ranch, Thermal CA 1962 3337 Sacaton citrumelo seedling 539823 Albert Newcomb Ranch, Thermal CA 1962 3341 Citrumelo, CPB 4475? (Swingle?) 143 539824 John Carpenter, USDCS, Indio CA 1961 3348 Citrumelo 539825 John Carpenter, USDCS, Indio CA 1961 3351 Fairhope trifoliate seedling 539772 Ted Frolich, UCLA 1960 3414 Sacaton citrumelo (ops) 539826 Del Rio Farms, Weslaco TX 1962 3415 Citranguma (ops) (S-302) 539841 Albert Newcomb, Thermal CA 1962 3417 Sacaton citrumelo (ops) 539827 Texas sub-station #19, Winter Haven TX 1962 3552 Citrangelo seedling (S-281) 539842 A. Newcomb Ranch, Thermal CA 1962 3566 Microcitrus ´ trifoliate or. 539854 Domingo Hardison, La Campana Ranch Fillmore CA 1966 3573 Glen citrangedin (ops) (Altamaha) 539843 W.C. Cooper, 2120 Camden Rd., Orlando FL 1962 3767 Swingle (?) citrumelo 539844 John Carpenter, USDCS, Indio CA 1975 3771 Swingle citrumelo 356 539828 USDCS, Indio CA via CCPP 1977 3821 Citrumelo (Hall grapefruit ´ trifoliate) 539845 Hybrid seedling produced at CRC 1978? 3881 Poncirus trifoliata x Satsuma (citrondarin) 396 433930 Russia via Glenn Dale & CCPP 1979 3889 Hall gft. x Rubidoux trifoliate (Code C-190) 539829 Hybrid produced at CRC 1983 3908 Benton citrange 435 539819 Australia via Glenn Dale (request by W.P. Bitters) 1983 3911 C-32 citrange 287 539820 CRC 11C-80-7 (trif. ´ Ruby orange) 3912 C-35 citrange 293 539821 CRC 8C-15-7 (trif. ´ Ruby orange) 3954 Minneola ´ trifoliate (MXT or Trifeola) 468 539846 Import from South Africa 1985 3957 Cleopatra mandarin ´ trifoliate (X639) 469 539847 Import from South Africa 1985 3969 African shaddock ´ Rubidoux trifoliate 476 539830 USDCS 1988 4025 Hamlin + Flying Dragon 533 600676 23. Miscellaneous species, not genus Citrus 1260 Geijera parviflora 52801 George Walder, Dir. of Agric., Sydney, NSW, Australia 1921? 1430 Atlantia citroides 539145 W.T. Swingle, USDA (cutting A) 1924 1460 Clausena lansium seedling (Wampee) 539716 W.T. Swingle, USDA 1924 1466 Faustrimedin (Microcitrus australasica ´ Calamondin) 539855 W.T. Swingle, USDA 1924 1484 Microcitrus australasica var. sanguinea seedling (Finger lime) 539734 W.T. Swingle, USDA 1485 Microcitrus virgata seedling (Sydney hybrid) 539740 W.T. Swingle, USDA 1924 1491 Severinia buxifolia (Chinese box orange)- cutting A 539793 W.T. Swingle, USDA 1924 1492 Severinia buxifolia (nearly spineless)- cuttings E & F 539794 W.T. Swingle, USDA 1924 1494 Severinia buxifolia seedling 539795 W.T. Swingle, USDA 1924 1495 Severinia buxifolia seedling 539796 W.T. Swingle, USDA 1924 1497 Severinia buxifolia (brachytic) seedling 539797 W.T. Swingle, USDA 1924 1637 Murraya paniculata (Orange Jessamine) 539746 W.T. Swingle, Date Garden, Indio CA 1926 2439 Eremocitrus glauca hybrid 539801 From CPB to Indio 1930 2878 Aeglopsis chevalieri seedling 539143 F.E. Gardner, Orlando FL 1950 2879 Hesperethusa crenulata 539748 F.E. Gardner, Orlando FL 1950? 2891 Faustrime 539808 F.E. Gardner, Orlando FL 1948? 3117 Pleiospermium species (ops) 231073 Ted Frolich, UCLA 1957 3126 Citropsis schweinfurthii (ops) 231240 H. Chapot, Rabat, Morocco 1956 3140 Aegle marmelos (ops) (Bael fruit) 539142 Charles Knowlton, Fullerton CA 1954 3165 Murraya koenigii seedling 539745 Bill Stewart, Arboretum, PasadenaCA 3166 Clausena excavata (ops) 235419 Ed Pollock, Malong Rd., Parkes N.S.W., Australia 1956 3171 Murraya paniculata (ops) (Hawaiian Mock orange) 539747 Hort. Dept., Hawaii Agr. Exp. Station 1955 3284 Clymenia polyandra (ops) 263640 Harold Winters, Beltsville MD 1960 3285 Glycosmis pentaphylla (ops) 127866 USDA Plant Introd. Station, Glenn Dale, MD 1960 3286 Citropsis gabunensis (ops) 246335 Yangambi State of INEAC, Belgium 1958 3287 Atalantia ceylanica (ops) 539144 John Carpenter, USDCS, Indio CA 1957 3288 Swinglea glutinosa (ops) 231241 H. Chapot, Ravat, Morocco 1956 3294 Citropsis daweana (ops) 247137 G.R. Bates, Causeway, Salisbury, Rhodesia 1958 3296 Citropsis gilletiana (ops) 539149 John Carpenter, USDCS, Indio CA 1960 3298 Microcitrus warburgiana (ops) 266043 Dept. of Agric., Port Moresby, Papua New Guinea 1960 3299 Feronia limonia (Wood Apple) 236991 E. Pollock, Parkes, N.S.W., Australia 1957 3463 Eremocitrus glauca 539717 Joe Furr, USDCS, Indio CA 1962 3507 Triphasia trifolia 539800 Henry Nakasone, Univ. of Hawaii 1956 3508 Ruta graveolens 600674 Oscar Clark, CRC 1961 3509 Paramygnia scandens (?) 109758 U.S. Plant Introd. Garden, Glenn Dale MD 1965
57 Appendix. Holdings of the University of California, Riverside Citrus Variety Collection Category Other identifiers CRC VI PI numbera Accession name or descriptionb numberc numberd Sourcee Datef 23. Miscellaneous species, not genus Citrus (cont.) 3510 Feroniella oblata (ops) 539720 Agric. Exp. Sta., Rio Piedros, Puerto Rico 1964 3511 Pamburus missionis 539749 U.S. Plant Introduction Station, Miami FL 1964 3514 Balsamocitrus daweii 539147 Prof. K. Mendel, Volcani Institute Rehovoth, Israel 1966 3517 Calodendron capense (Cape Chestnut) Wishing Well Nursery, Riverside 1965 3538 Esenbeckia runyoni Dave Dryer, Fruit & Veg. Lab., Pasadena CA 1967 3661 Microcitrus australasica 306115 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3663 Microcitrus australis 306117 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3664 Microcitrus australasica 306117 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3665 Microcitrus australis 306118 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3666 Microcitrus australis 306118 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3667 Microcitrus australis 306118 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3668 Microcitrus australis 306118 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3669 Microcitrus australis 306119 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3670 Microcitrus australasica 539736 3671 Microcitrus australasica 312873 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3672 Microcitrus australasica 312872 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3673 Microcitrus australis 312881 Joe Furr, USDCS, Indio CA (from Yuma AZ) 1968? 3724 Severinia buxifolia 539798 Republic of China 1967 3725 Atalantia zeylanica 539146 Royal Botanic Gardens, Peradeniya, Ceylon 1967 3726 Severinia buxifolia? 539799 Royal Botanic Gardens, Peradeniya, Ceylon 1967 3782 Microcitrus warburgiana 539743 D.J. Hutchinson, Orlando FL 1976 3784 Microcitrus inodora 539741 D.J. Hutchinson, Orlando FL 1976 3785 Microcitrus inodora 539742 New Guinea via John Carpenter, USDCS, Indio CA 1977 3786 Merrillia caloxylon 539733 1969? 3788 Clausena anisata 358849 Ag. Tech. Serv., Pretoria, South Africa, via Plant Intro Office 1977 3800 Atalantia monophylla 109613 China, via Glenn Dale & CCPP 1960 3824 Esenbeckia hartmanii 3899 Clausena excavata 539715 Lohan, Sabah, Borneo, via R. Scora 1985 3902 Micromelum minutum 539744 Kampong (Village), Takutan, Sabah, Borneo 1985 3917 Clymenia ´ Procimequat 539848 Hybrid produced at UCR 1966? 3918 Hardshelled Citrus relative 539732 3966 Wenzelia dolichophylla 277411 New Guinea via Glenn Dale 1983 3967 Clausena lansium, “Kai Sum Wampee” 296321 Glenn Dale Quarantine Facility 1983 4033 Afraegle paniculata 607466 4034 Clausena hardmandiana 4035 Glycosmis perakensis 4036 Severinia disticha 607467 aThe CRC (Citrus Research Center) number is the identification number used for CVC purposes. b(ops)=open pollinated seedling. cA VI (Virus Introduction) index number is assigned to an accession by the CCPP after it has been cleaned. dThe PI (Plant Introduction) number is assigned by the US NPGS for items it has accessioned. eSource of accession, intermediary, and origin, if known. Glenn Dale is the location in Maryland of a USDA quarantine facility. Abbreviations used: CPB=Crop Plant Breeding-USDA. fDate the accession was received by the CVC.
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