CRYOPRESERVATION AS A TOOL FOR PRESERVING GENETIC VARIABILITY: ITS USE WITH SPANISH WILD SPECIES WITH POSSIBLE LANDSCAPING VALUE

Abstract

Plant cryopreservation is the storage of plant material at ultra-low temperatures (-196°C to -150°C) which can be achieved using liquid nitrogen. Under such conditions metabolism comes to a halt thus avoiding physiological and genetic deterioration. Cryopreservation procedures have been studied with a number of endemic Spanish or autochthonous species with potential landscaping purposes. Cryopreservation of orthodox seeds (3.4 to 10.8% moisture content) of twenty one endemic species, by direct immersion and recovery from liquid nitrogen, did not decrease germination. Other treatments, including dormancy breaking, humidification or fast thawing, did not negatively interact with cryopreservation. Recalcitrant seeds cannot be desiccated without losing their viability. However, cryopreservation of embryonic axes of Quercus faginea, a species with moderate recalcitrant seeds, has been achieved by previous physical dehydration followed by direct immersion in liquid nitrogen. Vegetative material (nodal explants) of two endemic species were successfully cryopreserved when they had been previously encapsulated in alginate beads, cultured in a sucrose-rich medium and physically desiccated.