Efficiency of aluminum cryo-plates for cryopreservation of Dendrobium signatum Rchb. f. pollinia

Abstract

The efficiency of V cryo-plate and D cryo-plate methods for cryopreservation of pollinia of Dendrobium signatum Rchb. f., a Thai orchid was investigated. Pollinia were collected from flowers and then placed on the aluminum cryo-plate containing 12 wells embedded with 3% sodium alginate gel. In V cryo-plate method, cryo-plates with pollinia were immersed in 0.6 M sucrose + 2 M glycerol loading solution (LS) for 15 min, then dehydrated with PVS2 solution for 40 min at room temperature (29±2°C). In D cryo-plate method, cryo-plates with pollinia were treated with LS for 15 min, then dehydrated in a laminar air-flow cabinet for 3 h at room temperature (29±2°C). In both methods, cryo-plates were directly plunged into liquid nitrogen for 40 min, and rapidly warmed in 1.2 M sucrose for 15 min. The cryopreserved and non-cryopreserved pollinia were used to pollinate flowers of the same species. The results showed that cryopreserved pollinia retained fertilizing ability, and had similar pod formation as those pollinated with non-cryopreserved pollinia. The pod formation from cryopreserved pollinia in V cryo-plate and D cryo-plate methods were 55.6 and 50%, respectively. Seeds from non-cryopreserved and cryopreserved pollinia were successfully produced and germinated into plantlets with well-formed leaves and roots. Multiple stems (4.8 stems plant(-1)) produced from one plantlet when cultured on modified VW agar medium (1949) supplemented with 100 g L(-1) banana, 150 mL coconut water, 50 g L(-1) potato, and 20 g L(-1) sucrose for 120 d at 25±2°C. Cryopreserved pollinia using aluminum cryo-plate can be used successfully for pollination.