liI.i 111112.8 2 5 2 5 1.0 li.lI. ,~ 11111 . 1.0 ~IIIII~ 11111 . ~ ~II~ 2.2 I~ ~III~ 2.2 Ibl . 1:.1 .;, I~ ~ I~ ~ ~ :i lri.\l ..~ ~~ ... " I.;. " 1.1 .,;,a..:. .... 1.1 I.,a.", I I 111I[L25 111111.4 111111.6 111111.25 111111.4 111111.6 MICROCOPY RESOLUTION TEST CHART MICROCOPY RESOLUTION TEST CHART NATIONAL aURlAU OF S[,\NDAIlDS·196J,·A NAIIONAl nUHlAU or STANDARDS·I%3·A Genetic and Cytological Studies With Camellia and Related Genera By William L. Ackerman I; Technical Bulletin No. 1427 Agricultural Research Service UNITED STATES DEPARTMENT OF AGRICULTURE ACKNOWLEDGMENTS The major portion of the work shown here on interspecific and intergeneric hybridization and chromosome numbers waS done in partial fulfillment of the requirements for the Ph. D. degree at the University of Maryland, College Park. The dissertation research was accomp1ished under the guidance of Delbert T. Morgan, Professor of Botany. Trade names are used in this publication solely for the purpose of providing specific information. Mention of a trade name does not constitute a guarantee or \varranty of the product by the U.S. Depart­ ment of Agriculture 01' an endorsement by the Department over other products not mentioned. III CONTENTS Introduction ______________________________________________________-- Page1 ~aterials and methods _______________________________.--____________ 3 Parental specie.s of Camellia and related genera_______________________ 3 Experimental procedures _____________________________-_____________ 4 HybrirUzation ________..•_ _________ _________________________ _____ 4 ~ethods of pollination • ____ . _________________ ____________________ 4 Embryo culture _. __ .. __ . __ ._ •. ___.. ____________ ____________________ 7 General culture ______ ~ ______ • __ . _________ .._____________________ 8 Morphological comparisons of parents and hybrids _... ___ .. _ .__________ 9 Determination of pollen abortion ___ ._. ___ . __________ . _____ .. ____. 9 Cytological methods . _ ... _____ . __________ . ____ .__ .. ___ .. _.. ____ .__ 9 Results . ______ --______________________. _.______________________________ 12 Interspecific hybridization _.-_-_ .__ _________________________________ 12 Morphological comparisont1 ________ . ________________.. _____________ 12 D(;termination of pollen abortion __ ._______________________________ 27 Intergeneric hybridization ... __ • __________ •___ ..______________________ 39 ~orphological comparisons ___ . ___ .. ______________________________ 39 Determination of pollen abortion ____ . __________________________ ___ 47 Species compatibility relationships ___ • ____________________________ -- 48 Chromosome numbers __ ._________ . ___________ ._____________________ 51 Chromosome numbers of parents. ______ •.___• __ .___________________ 51 Chromosome numbers of interspecific hybrids ________ • __ . __________ 55 Chromosome numbers of intergeneric hybrid~; • _____• __________ .___ 64 Chromosome morphology .___ ___ . ____ . ______ • _______ . _______ 69 Discussion and conclusions . __ ..__ .. _____ . ______________ ._______ . 78 Summary _______ • _______.___________________________________________ 86 Literature cited ._ • _"_" .. __ ... _ .•___ . __________________________ ._______ 89 Appendix ____________________________• __________ .___________________ 93 Washington, D.C. Issued September 1971 For 8."11c by the SUPCl'intcndcnl or Documents, U.S. Govcrnment Printing Omec \Vnshin).!ton, D.C. 20402-Pl'icc 70 cents. IV Genetic and Cytological Studies With Camellia and Rela'ted Genera By WILL1AM L. ACKERMAN, research hm·ti(ntltm-ist, Plant Science Rcsea1·ch Division, Ag1·icultural Resea1·ch Service INTRODUCTION Interest in the genus Camellia was during the latter part of the L. has been largely concerned 18th century. with species of economic signifi­ During Victorian times, camel­ cance. In the Orient, camellias lias were grown as conservatory are important as ornamentals, for plants in both Europe and North­ the oil of the seeds of certain ern United States and as garden species, and as the source of tea. specimens in Southeastern United In both Europe and the United States. Popularity of camellias States, camellias are important waned near the turn of the cen­ only as ornamentals. Introduction tury, and not until after World of species of Camellia into Eu­ War II did they again gain prom­ rope from the Orient is generally inence as ornamentals. Pres­ accepted to have been about 1740 ently, the many cultivars of C. ja­ and was closely associated with ponica and C. sasanqua Thunberg the tea industry, based on C. si­ are grown rather widely as hardy nensis (L.) O. Kuntze. A report evergreens in southern and by Meyer (1959) 1 indicates a Pacific coastal regions and, to a much earlier introduction into limited extent, in greenhouses in Europe by Portuguese traders the North. C. hiemalis Nakai, C. who brought C. iaponica L. to reticulcda.. Lindley, C. sal7tenensis Oporto, Portugal, about 1550. In­ Stapt ex Bean, and C. ve?·nalis troduction into the United States (Makino) Makino are less frequently cultivated species CamelUa belongs to the family 1 References to Li';erature Cited, p. 89, are herein il1dic>!t<!d by the name cf the Theaceae, tribe Gordonieae, along author or authors followed by the year with eight other genera including of publication in italic. F?·anklinia, Gordonia, Laplacea, 1 2 TECHNICAL BULLETIN 1427, U.S. DEPT. OF AGRICULTURE PYl'ena?'ia, Schima, Stewa?·tia, solid colors and variegated pat­ Tutche?'ia, and Y~mnanea. Camel­ terns. No yellow or blue camellias lia is the largest of the genera appear among the commonly within Gordonieae. Index JKewen­ grown species. Most varieties i'e­ sis (Hooker and Jackso:1, 1890) tain old withered flowers. Except lists 80 species, whereas Sealy for a few faintly scented culti­ (1958) describes 82 recognized vars, particularly of C. sascmqua, species and 16 others still too im­ floral scent is lacking. Efforts to perfectly known for their status intensify this scent through in­ to be decided. A wide variation in traspecific hybridization have floral characters reflects a great been disappointing. The natural diversity between species. In Sea­ flowering sea&on for the culti­ ly's (1958) revision of Camellia vated species is limited to the he divided the genus into 12 sec­ spring for C. iaponica and C. ?'eti­ tions plus a miscellaneous group culata and the fall for C. sasan­ called Dubiae. Sealy's taxonomic qua. Improved cold hardiness is classification is used as the basis desirable because outdoor culture of species separation in this is now (1971) confined mostly to study. the Southeastern and West Coast Extensive programs have been States. undertaken in intraspecific hy­ Lesser known species have all bridization, particularly with C. of the characters presently lack­ japom:ca. Until recently, little at­ ing in the cultivated species with tention was given to interspecific the exception of blue flowers, al­ and inhH'generic crosses. Ander­ though purple-flowered species do son (1961) and Savige (1967) exist. Diversity within the genus have both said that much of the and numbers of indigenous species useful intraspecific genetic varia­ suggest the center of origin to be tion has been exploited in C. ia­ in the region of southern China ponica. Although interspecific and and North Vietnam. Many species intergeneric hybridizations are described by early taxonomists frequently difficult or unsuccess­ were never successfully exported ful, a program of wide crosses from this region and so are not was inWated in 1960 at the U.S. presently available for hybddiza­ Plant Introduction Station, Glenn tion. However, Hilsman (1966) Dale, Md., in an attempt to de­ states that approximately 25 to velop hybrids with wider genetic 30 species have been introduced variation. into the United States. The Glenn Vegetative and floral limita­ Dale station has 26 species of tions occur in C. iaponica and C. CamellicL in its collection, 20 of sasanqua,. Flower color in the which have flowered and have wild C. ,ia}Jonica is confined to been used as parents. red, but in the horticultural vari­ The basic chromosome number eties to white through red in both in the genus is 15. Chromosome STUDIES WITH CAMELLIA AND RELATED GENERA 3 numbers of 30, 45, 60, 75, and 90 Camellia species and species of ha ve been r€ported for different related genera in our collection by species. SUI' "ess in the devalop­ obtaining interspecific and inter­ ment of new forms will depend generic hybrids, (2) to determine upon the (!stablishment of hybrids the chromosome numbers of spe­ between species with different cies and hybrids, (3) to determine chromosome numbers as well as the chromosome morphology of between species with the same Canwllia species where possible, number. Therefore, crosses have and (4) to determine the breeu­ been made to obtain as many in­ ing potential of interspecific and terspecific combinations as possi­ intergeneric hybrids. Previous re­ ble without consideration of the ports on this subject have been chomosome numbers of the par­ made by the writer (1963, 1970a, ents. The chromosome numbers 197·Ob).~ of interspecific hybrids can be variable, particularly if one or both parents are polyploids. "Also, ACKERMAN, W. L. INTERSPE­ The purposes of this study CIFIC AND INTERGENERIC HYBRIDIZATION OF CAMELLIAS. 1969. (Unpublished Ph. were: (1) To investigate the com­ D. thesis. Copy on file Univ. of Md. patibility relationships of various library, College Parle) MATERIALS AND METHODS Parental Species