Abstract: On different conditions, Stephania delavayi was infected by four kinds of Agrobacterium rhizogenes strains R1000, 15834, 1855, 8196, and hairy roots were induced by the strain R1000 in light from young plant tissues. In MS liquid medium, the growth of hairy roots tended to be stable after they had been cultured for 42 days. The content of isoquinoline alkaloid came up to the summit on the 28th day, which was 1104pg / gFW. Both growth and isoquinoline alkaloid content of hairy roots were very different in six kinds of media. Among different media, hairy roots grew fastest in Bs medium, and the content of isoquinoline alkaloids was the highest in Nitsch medium.Phenylalanine inhibited both biosynthesis of isoquinoline alkaloids and growth of the hairy roots in B5 medium.

Key words: Stephania delavayi