Effects of Some Cryopreservation Procedures on Recalcitrant Zygotic Embryos of Ammocharis coranica

BACKGROUND: Cryopreservation, the most promising method for the long-term conservation of recalcitrant (desiccation-sensitive) seed germplasm, is often associated with high viability losses. Cryo-procedures involve a sequence of steps which must be optimised to reduce the impact of the stresses. OBJECTIVE: This study reports on the effects of some of the steps of cryopreservation on the recalcitrant zygotic embryos of the amaryllid, Ammocharis coranica. MATERIALS AND METHODS: Embryos were subjected to cryoprotection with glycerol and/or DMSO, rapid (flash) drying, and rapid (>100°C s^-1) or slow (1°C s^-1) cooling. RESULTS: Rapid dehydration (from c. 2.7 to 0.9 g g^-1 over 60 min) and cooling had a detrimental effect on the viability of the embryos, which was exacerbated when these steps were applied sequentially. After cooling, seedling production (30%) was obtained only from embryos that had been cryoprotected with glycerol prior to drying and rapid cooling, while 30% of non-treated embryos and 70% of those that had undergone cathodic protection during flash drying produced callus. CONCLUSION: Noting that no post-cryo survival of A. coranica embryos had previously been obtained, this study identified cryoprotection with glycerol and the incorporation of cathodic protection during flash drying as promising intervention points for future studies.