AbstractsBiology & Animal Science

Begonia is one of the most speciose genera of angiosperms, with over 1500 species distributed throughout tropical and subtropical regions; it is also a very important ornamental group of plants displaying a high degree of morphological diversity. This genus is a priority for conservation and germplasm development at the Ornamental Plant Germplasm Center located at The Ohio State University, which currently holds approximately 200 accessions, maintained primarily as clonal plants. In an effort to expand germplasm work in seed storage of Begonia , and in response to a scarcity of published information about begonia seed biology we initiated a project to develop baseline information about germination, dormancy, and stress tolerance of begonia seeds. Because of the extremely small size of begonia seeds (ca. 200 µm) I adapted germination and viability testing protocols typical of Arabidopsis research, to develop relatively efficient quantitative protocols for seed studies. Using this methodology seeds can be routinely germinated on 1% agar plates at 25°C and 16 hours light. To examine the variation in seed characteristics among Begonia accessions in the collection, I selected six species from diverse environments and from different sections of the genus for which we had abundant seed and compared their germination patterns in response to temperature and light, tolerance to high humidity/high temperature stress, and dormancy. I have determined that begonia seeds are desiccation-tolerant (orthodox), require light for germination (photoblastic), germinate under a wide range of temperatures, and mostly appear to lack any strong dormancy — depending on species, and are tolerant of various level(s) of stress. I found that Begonia ulmifolia , B. fischeri , and B. dregei are tolerant to high levels of stress (120 hours at 41°C) whereas B. boliviensis, B. grandis subsp. evansiana and B. subvillosa are less so. In addition, B. dregei appears to have some dormancy, which was observed through extended dark treatments (2-52 weeks) and exposure to low temperatures (12 and 15°C). Furthermore, B. grandis subsp. evansiana appears to show secondary dormancy as a response to extended dark treatments (2-52 weeks). Overall, I was able to establish a quantitative germination protocol that allowed for examination of different species to various environments. Tetrazolium testing was also possible after treatment of seeds with sodium hypochlorite. This work has established baseline information about seeds of Begonia that can be applicable to other physiological and conservation studies and useful for maintaining and characterizing a seed collection at the OPGC.