Abstract: Agrobacterium tumifaciens-mediated transformation for leaf disc of Betula platyphylla containing GUS was investigated and factors on Agrobacterium tumefaciens-mediated gene transfer is also discussed in detail. The optimal concentration of kanamycin to strain fungus is 50mg/l and of carbenicillin and cefotaxime is 500mg/l. Regeneration ratio of adventitious buds will improve 3-fold by adding of 100μM AS to regeneration medium. The optimal pre-cultivation period for leaf disc transformation is 3~4 days, the ideal time for leaf disc dipping in Agrobacterium is 10~20 minutes, and the optimal co-cultivation is 4 days. Transformed plants of white birch were obtained under above conditions and the transformation rate is 2.8%.

Key words: White birch, Leaf disc, GUS gene, Gene transformation, Agrobacterium tumifaciens