Dehydration in cryopreservation of moist plant tissues and seed maturation

The feasibility of long-term cryopreservation of plant objects depends on their moisture content. In orthodox seed, dehydration takes place at the late stage of maturation and is accompanied by accumulation of protective sugars and proteins. Such seed easily withstand cryopreservation. Moist objects such as meristems and recalcitrant seed must be desiccated in the presence of sucrose before freezing. In both naturally dry and dehydrated tissues, differential scanning calorimetry and electron paramagnetic resonance reveal intracellular vitrification; this glassy state is supposed to determine the success of cryostorage. Methodical approaches to cryopreservation of moist plant tissues are reviewed.