Format: ORAL

Dustin Wolkis1*,Natalie Blum2, Makoa Elgin2, CecilyEltringham1, Seana Walsh1,Alina Wood1

1Department of Science and Conservation, National Tropical Botanical Garden, Kalaheo, USA 2School of Life Sciences, University of Hawai?i at Manoa, Honolulu, HI, USA * corresponding and presenting author; dwolkis@ntbg.org

Storage of pollen allows for gene exchange between geographically isolated individuals, and for controlled pollination when flowering of staminate and pistillate flowers or individual plants are asynchronous. Desiccation of pollen is essential for the retention of high longevity, yet research into pollen storage behavior is infrequently performed. Hibiscus clayiand Pritchardia minorareKauai single island endemic plant species assessed as Critically Endangered and Endangered, respectively, by the IUCN Red List of Threatened Species. With respect to these species we ask; 1) How does pollen germination respond to varying sucrose concentrations (5-40%) and substrates (liquid/solid); 2) What is the pollen germination temperature niche breadth; 3) How does pollen viability respond after desiccating to the international genebank standard of 15-25% RH? If desiccation tolerant, 4) how does viability of previously desiccated then hermetically sealed pollen respond to freezing at conventional (-18ºC) and -80ºC temperatures? Finally, in order to understand relative storage lifespan and the influence of moisture relations, we ask, 5) How does pollen longevity respond to periods of time stored in varying RH environments. To answer these questions, we will collect pollen from the National Tropical Botanical Garden’s living collections. We will desiccate pollen to a range of RHs at ambient temperature (~25°C), hermetically seal, and store at -18 and -80ºC, then test viability via a germination test at each stage. To assess pollen longevity, survival curves will be determined and compared using p50 (the time for viability to decrease to 50%). Research into optimal pollen storage methods by species is needed to better understand the effects of desiccation, freezing, and time on pollen viability and longevity. Considering the current rate of plant extinction in Hawai‘i, pollen storage is an important conservation tool for conducting controlled crosses that might otherwise not be possible.