Cryopreservation of Bletilla formosana seeds (Orchidaceae) by desiccation

Cryopreservation of Orchid Genetic Resources by Desiccation: A Case Study of Bletilla formosana

“…praetermissa, Diuris fragrantissima, Diuris laxiflora, Diuris magnifica, Eulophia gonychlia, Eulophia stenophylla, Gymnadenia conopsea, Microtis media spp. media, Orchis coriophora (Anacamptis coriophora), Orchis morio (Anacamptis morio), Paphiopedilum rothschildianum, Pterostylis recurva, Pterostylis sanguinea, Thelymitra crinita, Thelymitra macrophylla, and Dendrobium candidum (Dendrobium moniliforme) are all most successfully preserved through the desiccation method [21,[31][32][33][34][35] (Table 1).…”

“…Therefore, those desiccation methods are recommended for long term storage of B. formosana. Fresh seeds of orchid pretreated in sucrose solution or vitrification before LN treatment are unsuitable for cryopreservation in our previous study [35]. Seedlings derived from the seeds desiccated by these two methods and then preserved in LN grew well 6 weeks after seed sowing ( Figure 2).…”

“…For most orchid species, for example, Bletilla striata, B. formosana, D. candidum (D. moniliforme), and Vanda tricolor [22,35,43,45], preserving tissue immersed directly in LN without any pretreatment results in high mortality rates because of formation of intracellular ice nucleation and growth in the cells [4,20,21,38]. Only a few examples were exceptions, for example, fresh pollens of English walnut (Juglans regia L.) described above [23].…”

“…E. cochleata seeds sealed in cryovials with a 24% WC could be cryopreserved without any loss in viability [36]. Fresh mature seeds of B. formosana, an endangered Taiwanese orchid, reached a 68% germination rate after being airdried for 24 h to a 25% WC and cryopreserved through direct immersion in LN [35]. These studies reveal that the WC of orchid seeds required for successful cryopreservation clearly varies among the species.…”

“…The effect of longer seed desiccation durations remains to be determined. For example, the seeds of P. tancarvilleae are difficult to preserve with a low WC (2-5%) at 4 and 25°C [4]; however, the germination rates of B. formosana dried seeds with a low WC are 68.5% after cryopreservation [35]. Thus, the appropriate WC that orchid seeds require for successful cryopreservation varies among the species.…”