Cryopreservation of Desiccation-Tolerant Seeds

The cryopreservation of desiccation-tolerant seeds depends on two key steps: specimen dehydration in an environment that ensuresthe attainment of water contents below the high-moisture freezing limit; and transfer and maintenance at a subzero temperaturethat may be optimized in relation to the seed-lot moisture content and species. Temperatures about 70�C below the glass transitiontemperature (Tg–70) or lower are recommended for seed storage. For fully desiccation-tolerant (type I) seeds, cryopreservationsuccess tends to be independent of cooling regime and subzero (�C) temperature treatment when the seeds are dry. However,to maximize recovery of partially desiccation-tolerant (type II) seeds there can be a requirement for slowcooling, avoidanceof storage at certain subzero temperatures, and controlled imbibition following cryopreservation, particularly for endospermicseeds that are high in lipid.