Abstract: An efficient and stable Agrobacterium -genetic transformation system for Torenia was established through investigating the factors influencing the transformation efficiency. The results showed that leaf explants are more sensitive to Agrobacterium infection, preculture of explants had an adverse effect on transformation efficiency, induction of vir gene with AS greatly imp roved the transformation effects. In addition, the concentration of bacteria, the time of infection and cocultivation, as well as the regeneration methods have effects on the transformation. By using the optimized conditions, hygromycin resistant plants could be obtained within 70 days from the infection of the explants with Agrobacterium. GUS staining, PCR and Southern-blot analysis confirmed that transgene were integrated into the Torenia genome with a transformation frequency of 7% - 8%.

Key words: Torenia, Agrobacterium tumefaciens, Transformation system