Cryopreservation of In Vitro-Grown Plant Apical Shoot Tips by Vitrification and Encapsulation-Vitrification

In vitro-grown apical shoot tips of Gentiana were successfully cryopreserved by vitrification (V) and encapsulation-vitrification (EV) protocols. We optimized and compared the V and EV protocols. Although both protocols resulted in a relatively high survival rate, the EV protocol seemed to have several distinct advantages. First, the survival rate of shoot tips cryopreserved by the EV protocol was much greater than that by the V protocol under optimized conditions. Second, the range of optimum treatment period by vitrification solution (PVS2 solution) was considerably wider with the EV protocol than with the V protocol. Third, after rewarming from liquid nitrogen temperature, the cryopreserved shoot tips showed more vigorous growth for the EV protocol than the V protocol. With the optimum EV protocol, we succeeded to cryopreserve shoot tips from 10 different lines of Gentiana and uniformly obtained high survival rate. Thus, the EV protocol appears to be promising for cryopreservation of a wide range of plant germplasm