Simultaneous promotion of tanshinone and phenolic acid biosynthesis in Salvia miltiorrhiza hairy roots by overexpressing Arabidopsis MYC2

Tanshinones and phenolic acids are two major groups of natural bioactive compounds in Salvia miltiorrhiza which exert excellent pharmacological activities. Due to low content in S.miltiorrhiza , it is urgent to enhance the production of the two compounds to meet the increasing need. The Arabidopsis basic helix-loop-helix (bHLH) transcription factor MYC2 was introduced into S. miltiorrhiza hairy roots. In the best transgenic line AtMYC2-3 , tanshinone yield was 14.06 mg/g dw which was increased by 5.45-fold more than that in the control line, while phenolic acid production was enhanced to 95.9 mg/g dw, a 3.3-fold increase compared with the control. Transcript levels of some genes involved in biosynthesis of tanshinones and phenolic acids were noticeably upregulated. Dual-luciferase assay revealed that AtMYC2 activated the expression of biosynthetic genes including SmDXS2 and SmTAT . These results revealed that AtMYC2 plays a positive role in accumulation of both tanshinones and phenolic acids which provides a promising strategy for engineering tanshinone and phenolic acid production in S. miltiorrhiza .