SmMYB98b positive regulation to tanshinones in Salvia miltiorrhiza Bunge hairy roots

Abstract

Tanshinones are major secondary metabolites in Salvia miltiorrhiza Bunge, the traditional Chinese medicinal plant Danshen. Increasing the production of tanshinones is important because of their significant economic value in human medicine, for the treatment of cardiovascular and cerebrovascular diseases and for their anti-tumor properties. Phosphate (Pi) starvation can change secondary metabolism in plants. MYB transcription factors (TFs) have been reported to be involved in both Pi starvation signaling and secondary metabolism regulation, enabling plants to build a relationship between the Pi starvation signal and secondary metabolism. In the present study, a nucleus-located R2R3 MYB TF, SmMYB98b, was found in S. militorrhiza. SmMYB98b was shown to belong to subgroup 20 of R2R3-MYB TFs, and expression could be induced by low-Pi conditions. The overexpression of SmMYB98b in S. militorrhiza hairy roots stimulated tanshinone accumulation. Plants overexpressing SmMYB98b exhibited Pi-starvation responses, such as decreased Pi concentration and activation of genes inducible by phosphate starvation, whereas transgenic plants with the SmMYB98b-RNA interference (RNAi) construct showed the opposite phenotype. In summary, the present study highlighted the role of SmMYB98b as a regulator of tanshinone biosynthesis and its potential function in Pi-starvation signaling. These results might have wider implications for studying the crosstalk between Pi stress responses and secondary metabolism pathways in plants. This study highlights the role of SmMYB98b as a positive regulator of tanshinone biosynthesis and its potential function in Pi-starvation signaling in Salvia miltiorrhiza.