Abstract:In order to establish induction system of hairy roots of Sedum alfredii, the leaves infected by Agrobacterium rhizogenes A4 as explants, the effect factors, such as pre-culture time, infection time and co-culture time, on induction rate of hairy roots were studied. The results showed that the hairy roots could be induced after 48 h pre-culture, infection for 6 min and 48 h co-culture with the highest induction rate of 85%. Furthermore, the rolB gene could be detected in induced hairy roots by PCR, which confirmed that the transgenic system of S. alfredii mediated by A. rhizogenes A4 was successful. So, it was the first time for induction system establishment of hairy roots in S. alfredii with A. rhizogenes A4.