OBJECTIVETo establish the transformation system of mulberry, and test its ability of quercetin biosynthesis.

METHODHairy roots of mulberry were obtained through infecting etiolated seedlings with Agrobacterium tumefaciens strain C58C1. The culture condition of hairy roots was optimized. The transformation of T-DNA was examined by PCR assay and quercetin content was determined by HPLC.

RESULTWhen infecting stem cutting of etiolated seedlings via C58C1 strain, the optimal transformation conditions were as follows: 10 minutes' infection, two-days pre-culture and co-culture, additional hydroxylacetosyringone (As) 100 mg x L(-1). The PCR examination result showed that rolB and rolC genes could be inserted into the hairy roots of mulberry. Hairy roots appeared in 10 days after infecting, the frequency of stems explants was up to 92% after 30 days culturing. After 50 days culturing in 1/2MS + 0.05 mg x L(-1) IBA liquid medium, the content of quercetin increased by 8. 5-fold.

CONCLUSIONHairy root culture system of Moraceae plants was established successfully for the first time. In addition, it also provides a foundation for further industrial production of active compounds such as quercetin.