Crioconservazione di gemme di portinnesto Kober 5BB (Vitis Berlandieri x Vitis riparia): aspetti anatomici.

Micropropagated buds of the grape rootstock Kober 5BB were cryopreserved with the vitrification technique. The procedure involved the use of cryprotectant substances, dehydration by vitrifying solution, quick freezing in liquid nitrogen, and finally regeneration. The critical points of the procedure were the time of contact of explants with PVS2, which can result toxic on explants if they are exposed to it for too long time, and sucrose concentration in preculture media (hardening). Histological analyses were carried out to evaluate any modifications determined by treatments and to locate the damage within the bud. PAS-Amido Black staining showed that with the increasing of contact time with the vitrifying solution bud peripheral cells appear degenerated following plasmolysis; however, the meristematic tip remains vital after undergoing cryopreservation. The problem of lack of regeneration after liquid nitrogen seems instead to be due to the isolation of the meristematic zone, which ends up encapsulated in a thick layer of degenerated cells.