Crioconservazione di gemme incapsulate di Quercus robur L.: analisi di parametri biochimici correlati allo stress da disidratazione e congelamento.

Cryopreservation plays a role of great importance in ex situ conservation of plants that produce recalcitrant seeds, like oaks. During the research, a protocol of micropropagation of Q. robur, based on the axillary bud proliferation of plantlets obtained by seed, was developed. Furthermore, freezing tests in liquid nitrogen were carried out by applying the incapsulation-vitrification technique. This consists in the inclusion of the buds in alginate beads and in their dehydration using a vitrification solution (PVS2) to protect the explants from lethal injury caused by the direct immersion in liquid nitrogen. In order to monitor possible damages to biological membranes due to the pre-treatments of chilling, dehydration and PVS2-loading, the levels of malondialdehyde, one of the metabolites derived from lipid peroxidation and the electrolyte leakage from the encapsulated buds were evaluated after each step of the protocol. Malondialdehyde values progressively increased after every treatment. Similar results were obtained following the trend of conductivity. Dehydration phase seems to be critical for oak buds. Based on these preliminary results, the study will continue with the aim to reduce cell injury and ensure an optimal recovery of oak explants after cryopreservation.