SmKSL overexpression combined with elicitor treatment enhances tanshinone production from Salvia miltiorrhiza hairy roots

Tanshinones are compounds of diterpenoid, which are used in the treatment of cardiovascular diseases; however there is an urgent need to improve their production using biotechnological methods. In the present study, Agrobacterium-mediated transformation was used to produce hairy roots of Salvia miltiorrhiza expressing kaurene synthase-like (SmKSL), a tanshinone biosynthesis gene. The results revealed that the yield of total tanshinone increased by a maximum of 2.7-fold in the transgenic Salvia miltiorrhiza hairy roots overexpressing SmKSL as compared with wild-type control lines. Treatment with elicitors further increased the total tanshinone production in the SmKSL-overexpressing lines. Yeast extract treatment of line p35S::SmKSL-15 produced the highest total tanshinone content (4.2 mg/g dry weight), representing an increase of 3.5-fold compared with that in the wild-type control lines. M the same time, qRT-PCR analysis indicated that tanshinone accumulation correlated positively with the transcriptional level of the two pathway genes.