Cryopreservation of grapevine (Vitis spp.) embryogenic cell suspensions by encapsulation-vitrification

Embryogenic cell suspensions of two grapevine rootstocks: 110 Ritcher (V. berlandieri x V. rupestris), 41B (V. vinifera x V. berlandieri) and several table grape and wine cultivars (Vitis vinifera) were successfully cryopreserved by the encapsulation - vitrification method. Embryogenic cell suspensions were precultured for 3 days in liquid MGN medium supplemented with daily increasing sucrose concentrations of 0.25, 0.5, 0.75 M. Precultured cells were encapsulated and directly dehydrated with a highly concentrated vitrification solution prior to immersion in liquid nitrogen for 1 h. After rewarming at 40degreesC for 3 min, cryopreserved cells were post-cultured on solid MGN medium supplemented with 2.5 g l(-1) activated charcoal. Surviving cells were transferred to solid MGN medium for regrowth or solid MG medium for embryo development and then to solid WPM for plant regeneration. Optimal viability was 42 - 76% of cryopreserved cells when cell suspensions were precultured with a final sucrose concentration of 0.75 M and dehydrated with PVS2 at 0degreesC for 270 min. Biochemical analysis showed that sucrose preculture caused changes in levels of total soluble protein and sugars in cell suspensions. Although the increase in fresh weight was significantly lower in cryopreserved cells than in control cells, the growth pattern of the cryopreserved cells and control cells was the same after two subcultures, following re-establishment in cell suspensions. Protocol developed in this study suggests a universal and highly efficient cryopreservation system suitable for several genetically diversed Vitis species.