Micropropagation of carnivorous plants

A simple, efficient system for seed surface disinfestation and in vitro germination was developed for the carnivorous pitcher plants Darlingtonia californica and Sarracenia leucophylla. Of the disinfectants tested, hydrogen peroxide or 10% Clorox® were most effective for disinfesting seeds of D. californica, while concentrated sulfuric acid worked best for S. leucophylla. Differences in the effectiveness of sterilants were associated by differences in seed coat morphology. Seeds of D. californica imbibed at 4-7°C in sterile deionized water with surfactant and gibberellin germinated earlier than seeds without exposure to gibberellin. Unimbibed seeds of S. leucophylla germinated rapidly in sterile water after treatment in concentrated sulfuric acid. Scanning electron microscopy of D. californica seed coats revealed waxy trichomes covering the seed surface. In contrast, the seed coats of S. leucophylla were pitted with surface and sub-surface cells possessing heavily thickened cell walls. These cells were devoid of contents. Fungal hyphae were observed on the seed surface and within empty cells of the integuments. Scanning electron microscopy observations and comparison of seed coat morphology of the carnivorous plant genera Drosera, Dionaea, Sarracenia and Darlingtonia revealed a wide range of differences in structure and ornamentation, which may suggest a species specific approach to surface disinfestation. A simple effective system for the in vitro growth, multiplication and rooting of axenically germinated seedlings of D. californica was developed. Seedlings grown on solid Yi strength Murashige and Skoog medium produced more biomass and more and longer pitcher leaves than seedlings grown on other solid media assayed. Root development on solid media was minimal and usually limited to the seminal root regardless of the medium. Seeds stimulated by gibberellic acid prior to germination and exposed to auxin and cytokinin during early seedling development produced multiple offshoots as well as fibrous root systems when transferred to Y2 strength liquid medium containing charcoal. Similarly treated seedlings transferred to Yi strength liquid media without charcoal produced multiple offshoots but fewer root systems. Seedlings cultured in medium without charcoal produced more but smaller pitchers than seedlings cultured in medium containing charcoal. Multiplication did not occur on solid media, and seedling growth was stunted. Seedling multiplication through offshoots occurred in all liquid media and was both prolific and rapid. Darlingtonia californica was regenerated from whole, in vitro germinated seedlings and excised segments from in vitro generated juvenile pitchers. When incubated on solid Phytomax Orchid Multiplication Medium, seedlings produced protocorm-like bodies and green leafy callus When divided and subcultured in liquid Phytomax Orchid Multiplication Medium, explants of both protocorm-like bodies and green, leafy callus gave rise to multiple shoots as well as more protocorm-like bodies and green, leafy callus. These could be further divided and subcultured. Transverse segments of excised pitcher leaves from axenically-grown seedlings produced shoots and protocorm-like bodies when subcultured in liquid Phytomax Orchid Multiplication Medium. Unlike D. californica, seedlings of S. leucophylla did not readily produce offshoots when incubated on solid media. A protocol for extraction of embryos from selected Sarracenia species was developed. ACKNOWLEDGEMENTS I especially thank my major professor Dr. Alison Roberts for her guidance, patience and vision in helping me bring this project to fruition. I thank her for believing in me, and for keeping me focused during difficult times (of which there were many). This must not have been easy for her. I thank the members of my committee, Dr. Richard Koske for his guidance and advice throughout the years, Dr. Joanna Norris for her exceptional patience, and Dr. Carl Beckman whose spirituality has left its mark on me. I also thank Dr. Larry Englander for acting as chair of my defense. I thank Chris Nerone, Veronica Masson, Marybeth Able, Stacie Paquette, Jane Leary, my sons Kenneth and icklaus Uhnak, John Phillip Jr. , and Judy Gould. I thank Ranger Hall graduate students Ryan Tainsh and Mike Budziszek for helping with statistics and computer problems, Alissa Neill for support, and Mary Beth Hanley for kindly leaving food in the refrigerator on nights I worked until dawn. I thank Dr. Eric Roberts for generously saving me from certain destruction during the final hours. I thank the Alley family for believing in me enough to offer their prayers of support. I thank William Alley, Janice Alley, and William Alley Jr. I also thank Claudia, Becky, Ron and Nana Franke for their much appreciated support and prayers. I thank my parents Dominic and Bernadette for their love and support. A special thank-you is due to my wife, Leslie Anne Uhnak, who not only typed much of this dissertation (more than once), but also endured a somewhat chaotic life during its completion. I also thank her and my stepdaughter, Kelsey Desrosiers, for their support and belief in me during this remarkable ordeal.