An Abstract for the Thesis Of
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AN ABSTRACT FOR THE THESIS OF Robin L. Mulvey for the degree of Master of Science in Botany and Plant Pathology presented on March 2, 2010. Title: Castilleja and Pedicularis are Confirmed as Telial Hosts for White Pine Blister Rust in Whitebark Pine Ecosystems of Oregon and Washington. Abstract approved: Everett M. Hansen The primary objective of this research was to determine if native species within the genera Castilleja and Pedicularis are naturally infected by white pine blister rust (Cronartium ribicola) in whitebark pine ecosystems of the Oregon and Washington Cascade Range. Secondary objectives were to monitor the phenology of aecial and telial hosts to determine if there is sufficient time for C. ribicola to complete its lifecycle within high-elevation stands, and to evaluate the extent and variety of susceptible native hosts within these genera through field and growth chamber inoculation. These objectives were approached through fieldwork in 2008 and 2009 in whitebark pine ecosystems at Mt. Rainier, Mt. Adams, Mt. Hood, Mt. Bachelor, Tumalo Mtn. and Crater Lake. Forty-nine observational study plots were established (28 in 2008 and 21 in 2009) and monitored three to si x times per season. Natural C. ribicola infection was detected on 84 Pedicularis racemosa plants and five Castilleja plants (C. applegatei, C. miniata, and C. parviflora). Field observations provided evidence that there is sufficient time for C. ribicola to complete its lifecycle on hosts within high-elevation whitebark pine stands. In 2009, 18 field inoculation plots were established at Mt. Rainier and Crater Lake. Field inoculation confirmed the susceptibility of two additional species within these genera, C. arachnoidea and P. bracteosa. The species identity of the rust on field specimens was verified through PCR and genetic sequencing of the ITS1-5.8S-ITS2 region of DNA. All four Castilleja species inoculated in the growth chamber developed infection, with an overall infection incidence of 62% (167 out of 270 plants). Improved understanding of the role of these newly recognized hosts in white pine blister rust epidemiology should be used to prioritize sites for the restoration of ecologically-valuable whitebark pine. © Copyright by Robin L. Mulvey March 2, 2010 All Rights Reserved Castilleja and Pedicularis are Confirmed as Telial Hosts for White Pine Blister Rust in Whitebark Pine Ecosystems of Oregon and Washington by Robin L. Mulvey A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Presented March 2, 2010 Commencement June 2010 Master of Science thesis of Robin L. Mulvey presented on March 2, 2010. APPROVED: Major Professor, representing Botany and Plant Pathology Chair of the Department of Botany and Plant Pathology Dean of the Graduate School I understand that my thesis will become part of the permanent collection of Oregon State University libraries. My signature below authorizes release of my thesis to any reader upon request. Robin L. Mulvey, Author ACKNOWLEDGEMENTS The author expresses sincere appreciation to Everett Hansen, Dave Shaw, Pat Muir and Joe Beatty for serving on her graduate committee. Everett Hansen acted as an inspiring mentor, with tremendous insight, patience and kindness. Wendy Sutton provided invaluable assistance with laboratory methodology and genetic sequencing techniques, and Paul Reeser and Jeff Stone also offered help with lab protocol. Mark Wil so n was a collaborator in the development of field sampling methods. Isabelle Visnadi, Carolyn Choquette and Steven Mulvey provided exceptional field assistance and were conscientious and eager workers with incredible attention to detail. Richard Sniezko, Angelia Kegley and Robert Danchok (Dorena Genetic Resource Center), Kristin Chadwick (Forest Health Protection), Chris Jensen (Reforestation and Genetics) and Robert Progar (Forest Health Protection) of the USDA Forest Service were enthusiastic sources of information, support and resources. Bryce Richardson (USDA Forest Service) supplied information on Castilleja and Pedicularis as hosts for white pine blister rust based on his work with these hosts in Idaho. The author is grateful to Mac Brock, Laura Hud so n, Lia Vella, Linda Hilligoss, Elena Thomas and other staff at Crater Lake National Park, and to Lou Whiteaker and Bret Christoe of Mt. Rainier National Park for promoting and encouraging this research in whitebark pine ecosystems within National Park boundaries. Michael Murray (Bristish Columbia Forest Service) and Regina Rochefort (North Cascades National Park Service Complex) shared field data from whitebark pine ecosystems at Crater Lake National Park and Mt. Rainier National Park, respectively, which aided initial reconnaissance efforts in these parks. Thank you to the USDA Forest Service for allowing research and plant collection on National Forest land. Seven Oaks Native Plant Nursery (Albany, Oregon) donated Castilleja and Penstemon seed to this project, while Kim Hummer and Daniel Dalton of the Department of Horticulture at OSU and the Agricultural Research Service National Clonal Germplasm Repository donated Ribes nigrum plants. Tom Kaye from the Ecological Research Institute (Corvallis, OR) also donated several Castilleja plants. The author would like to express gratitude to the Louis F. Roth Endowment Fund in the Department of Botany and Plant Pathology for supporting her Graduate Research Assistantship and the Hardman Award for Native Plant Research for contributing to field research costs. Lastly, the author extends thanks to friends and colleagues in the Department of Botany and Plant Pathology at Oregon State University. TABLE OF CONTENTS Page Thesis Introduction and Literature Review…..……………………….. 2 Study Objectives and Thesis Format…………......................... 3 White Pine Blister Rust in North America……………………. 3 Castilleja and Pedicularis as hosts for C. ribicola in Asia and North America……………........................................................ 6 Whitebark Pine: Ecology and Threats……………………….... 9 Summary of Approach………………………………………... 11 Castilleja and Pedicularis Confirmed as Telial Hosts for Cronartium ribicola in Whitebark Pine Ecosystems of the Oregon and Washington Ca scade Range………………………………………………………… 13 Introduction…………………………………………………… 13 Site Descriptions………………………………………………. 17 Geology……………………………………………….. 18 Climate……………………………………………….. 19 Plots within Major Field Locations…………………… 20 Species Composition………………………………….. 20 Methods……………………………………………………….. 25 Observational Study…………………………………… 25 Field Inoculation……………………………………… 28 Genetic Diagnostics…………………………………… 31 Results…………………………………………………………. 33 Observational Study…………………………………... 33 TABLE OF CONTENTS (Continued) Page C. ribicola Infection on Telial Hosts…………. 33 2008 Field Season……………………. 33 2009 Field Season……………………. 34 Phenology of Aecial and Telial Hosts………… 37 Spore Phenology on Pine…………….. 40 Alternate Host Phenology……………. 42 2008 Field Season……………. 42 2009 Field Season……………. 43 Field Inoculation……………………………………… 47 Genetic Diagnostics…………………………………… 50 Discussion…………………………………………………….. 53 Observational Study………………………………….. 53 Field Inoculation……………………………………… 58 Genetic Diagnostics…………………………………… 59 Conclusion…………………………………………………….. 59 Literature Cited……………………………………………….. 61 Susceptibility to Cronartium ribicola of Four Castilleja sp. f r o m Whitebark Pine Ecosystems of the Cascade Range Confirmed through Growth Chamber Inoculation………………………….……................ 66 Introduction…………………………………………………… 66 Methods……………………………………………………….. 71 Plant Propagation……………………………………… 71 TABLE OF CONTENTS (Continued) Page Aeciospore Collection…………………………………. 73 Inoculation Protocol…………………………………… 73 Aeciospore Germination………………………………. 75 Plant Monitoring………………………………………. 76 Data Presentation and Analysis………………………... 77 Results…………………………………………………………. 78 Aeciospore Germination………………………………. 78 Inoculation Experiment I……………………………… 79 Inoculation Experiment II……………………………... 84 Discussion……………………………………………………… 88 Conclusion……………………………………………………… 92 Literature Cited………………………………………………… 93 Thesis Discussion and Conclusion…..…………………………………. 97 Cronartium ribicola Infection……………….…………............ 97 Phenology: Disease Progression on Aecial and Telial Hosts….. 99 The Role of Environment and Senescence in Infection….......... 102 Management Implications: Are Castilleja or Pedicularis Important Hosts? ………………. 104 Follow-up Work and Future Research…………………………. 106 Conclusion……………………………………………………… 108 Literature Cited…………………………………………………………. 110 TABLE OF CONTENTS (Continued) Page Appendices……………………………………………………………... 116 Appendix A. Percent cover of species in 10m-radius tree and 5m-radius shrub and herbaceous plots ………………………… 116 Appendix B. Cronartium ribicola-infected specimens from observational and inoculation study plots in 2008 & 2009.…… 125 Appendix C. Cronartium ribicola-infected specimens from growth chamber inoculation experiments.…………………….. 126 LIST OF FIGURES Figure Page 2.1 Study locations in the OR and WA Cascade Range…………….... 18 2.2 Pedicularis, Castilleja and Ribes species that grow in association with whitebark pine in the Cascade Range…………………………….. 22 2.3 Locations of observational plots in the OR and WA …………….. 26 2.4 Aeciospore collection at CLNP and P. racemosa inoculation at MRNP……………………………………………………………… 29 2.5 Number of aeciospores per ml of spore suspension....................... 31 2.6 P. racemosa and C. parviflora leaves infected with telial lesions of C. ribicola………………………................................