Abstract: Lycoris sprengeri was used to study the effects of exogenous sucrose concentrations on bulblet formation in vitro，from morphological，histocytological，physiological，biochemical and molecular levels. The results showed that the presence of exogenous sucrose is a necessary condition for the formation of bulblets in vitro，while sucrose concentration（30 g ? L-1 or 60 g ? L-1）had little effect on the number of bulblets. Acting as both carbon and energy source，exogenous sucrose was a key factor for bulblet formation. When exogenous sucrose was present，sucrose and soluble sugar accumulated before the formation of axillary buds，and the accumulation of starch granules at the base of the scale provided a material basis for bulblet formation here. In addition，the presence of sucrose promoted the accumulation of MeJA in plants and inhibited the abnormal increase in the expression of LsWIP1，LsERS2 and LsEIN2 genes levels，which may mean that sucrose initiated a damage protection mechanism as a signaling molecule and promoted the formation of bulblet.

Key words: Lycoris sprengeri, in vitro culture, sucrose, bulblet formation