High-efficiency somatic embryogenesis and plant regeneration from suspension cultures of grapevine

Embryogenic suspensions of grapevine (Vitis vinifera L.) were initiated fro m somatic embryos of 'Thompson Seedless' and 'Chardonnay'. Suspension cultu res consisted of proembryonic masses (PEM) that proliferated without differ entiation in a medium containing 2,4-dichlorophenoxyacetic acid (2,4-D). 'C hardonnay' somatic embryos developed fully from PEMs following subculture i n medium without 2,4-D; however, somatic embryo development did not advance beyond the heart stage in 'Thompson Seedless' suspension cultures. Highly synchronized development of somatic embryos was obtained by inoculating <96 0-mu m PEMs into liquid medium without 2,4-D. Somatic embryos were also pro duced in large numbers from suspension-derived PEMs of both cultivars on se misolid medium lacking 2,4-D. Somatic embryos matured and regenerated into plants in MS basal medium containing 3% sucrose. Using this method more tha n 60% of the somatic embryos regenerated plants. More than 90% of the regen erated plants were successfully transferred to the greenhouse.