Abstract Detail

Conservation Biology

Pradhan, Namrata [1], Martini, Francesco [2], Yang, Mei [1], Khoddamzadeh, Amir [3], Cao, Kun-Fang [1], Manage Goodale, Uromi [4].

Comprehensive approach for seed banking of Bletilla striata, an endangered terrestrial orchid: recommendations for research and conservation.

Owing to their minute size and lightweight, seed banking is an ideal ex-situ conservation technique for preserving the genetic diversity of the Orchidaceae plant family, which contains the highest number of species threatened with extinction. However, orchid seed banking is challenging due to species-specific storage behavior and storage temperature- and methodology-based variation in longevity. This calls for comprehensive species level assessment of storage conditions most suitable for their successful seed conservation. We investigated the storage temperature and durations, and cryopreservation methodology on the seed banking success of Bletilla striata, an orchid exploited for commercial interest and endangered with extinction. We subjected B. striata seeds to four storage conditions: 1) refrigeration at 5 °C for eight weeks, 2) freezing at -18 °C for eight weeks, and 3) Direct cryopreservation and 4) Vitrification cryopreservation in liquid nitrogen at -196 °C for one hour, one day and eight weeks. Post-cryopreservation, the seeds were subjected to two thawing conditions; rapid and slow thawing. The effect of storage temperature and durations, and cryopreservation methodology were assessed by comparing pre- and post-storage characteristics in: 1) seed morphology (eight seed and embryo traits), 2) seed functional integrity (two enzymatic seed viability tests --Tetrazolium [TTC] and Fluorescein diacetate [FDA] tests and the non-enzymatic seed viability test --Evans blue test), and 3) the germination speed and probability of success under asymbiotic in-vitro conditions. Seed morphology was measured in 30 replicates and viability and germination tests were replicated four times, for all pre- and post-storage treatments. Data were analyzed in R, using Beta-Binomial models, accounting for overdispersed binomial data. Direct cryopreservation was the best method for seed storage because it preserved seed morphology, functional integrity as well as germinability under all storage durations. Storage in the fridge or freezer resulted in lower preservation of morpho-functionality of seeds as compared to the Direct cryopreservation. Vitrification cryopreservation was the least suitable method for seed storage; seeds maintained higher viability and germinability when stored for an hour or a day, but not when stored for eight weeks. The germination speed of the seeds of B. striata increased with the increase in storage duration in liquid nitrogen, indicating that long-term cryopreservation is beneficial for seed banking of B. striata. Direct cryopreservation is the most suitable method for both short- and long-term storage of B. striata seeds compared to the other storage methods evaluated here. The analysis to determine the most suitable viability test for this species, an essential pre-requisite for developing seed conservation protocols, showed that the EB test is the most reliable viability test that could closely predict germinability of B. striata seeds. The recommendations provided here on the best conditions for seed banking, by comprehensively investigating the factors that contribute to storage success of B. striata, can aid in the conservation and research of this valuable but endangered orchid species. The thorough protocol followed here for storage assessment of this species’ seeds can be used as a blue print for developing seed conservation strategies for other orchid species.

1 - Guangxi University, Forestry College, Daxuedonglu 100, Nanning , 45, 530005, China, (+91)7679210129
2 - Czech University Of Life Sciences Prague, Department Of Forest Ecology, Kamýcká 129, Prague, PR, 16500, Czech Republic
3 - Florida International University, Earth & Environment, 11200 SW 8th St., AHC-5 391, Miami, FL, 33199, United States
4 - Guangxi University, Forestry College, Daxuedonglu 100, Nanning, Guangxi, 530005, China, (+86)18174128535

Keywords:
orchid seeds
seed banking
seed morphology
seed viability test
Tetrazolium test
Fluorescein diacetate test
Evans blue test
Direct cryopreservation
Vitrification cryopreservation
in-vitro germination.

Presentation Type: Oral Paper
Number: CB4006
Abstract ID:304
Candidate for Awards:None