Abstract: The effects of different concentrations of melatonin（0，1.0，2.0，3.0 mg ? L-1）on the induction efficiency in Vitis vinifera‘Thompson Seedless’via somatic embryogenesis were investigated with unopened flower buds as explants. The results showed that the callus induction rate was 73.67%–89.10% when subcultured on the medium of MS + 1.0–3.0 mg ? L-1 melatonin + 2.0 mg ? L-1 6-BA + 30 g ? L-1 sucrose + 3 g ? L-1 phytagel for 30 days，which was significantly higher than that of 2,4-D treatment. Concurrently，the callus formation time on the above-mentioned medium was shortened by 14 days compared to the corresponding control medium with 2,4-D. At 120 days after callus induction，somatic embryos appeared in different concentrations of melatonin，among which the highest incidence was on themedium of MS + 1.0 mg ? L-1 melatonin + 2.0 mg ? L-1 6-BA + 30 g ? L-1sucrose，reaching 12.05% at 180 d. After 30 days of germination，the cotyledon embryos on X6 medium with MS + 60 g ? L-1 sucrose + 0.5 g ? L-1 activated carbon were transferred to the seedling medium with MS + 0.2 mg ? L-1 6-BA + 0.1 mg ? L-1 NOA + 30 g ? L-1 sucrose + 0.5 g ? L-1 activated carbon. Among them，1.0 mg ? L-1 melatonin induced a large number of normal somatic embryogenesis，and the induction rate was 14.84%. The results also demonstrated that the induction rate of somatic embryos treated with different concentrations of melatonin increased rapidly after 180 d，and low concentrations of melatonin was beneficial to somatic embryos germination and normal development，whereas the 2,4-D-induced callus had no somatic embryos formation.

Key words: grape, melatonin, somatic embryogenesis, plant regeneration