Cryopreservation of forest species by vitrification of organs and tissues from in vitro cultures

The cryopreservation of different material from in vitro culture was successfully obtained for several plant species following a one-step vitrification procedure. Best survival rate (90%) was achieved when white poplar shoot tips were exposed to the PVS2 vitrification solution for 60 min at 0°C, colled to -196°C by directly plugging into liquid nitrogen, and twaed in water bath at 40°C. Lower survival rates were obtained with shoot tips of grey and black poplar (54 and 22%, respectively). As regards horse chestnut embryogenic tissue, best survival and regrowth (75%) were observed when clusters of torpedo-stage somatic embryos were exposed to the vitrification solution for 90 min, prior to be plugged directly into liquid nitrogen and thawed at 40°C. With the same procedure, promising survival and proliferation of cryopreserved somatic embryos of narrowleaf ash were achieved as well.