SmWD40-2 functions as a positive regulator of both tanshinones and phenolic acids biosynthesis in Salvia miltiorrhiza Bunge hairy roots

Salvia miltiorrhiza Bunge, one of the most commonly used traditional Chinese medicine, whose target bioactive compounds are tanshinones and phenolic acids. However, the regulation of tanshinones and phenolic acids biosynthesis seems like a very complicated process, its molecular mechanism still remains to be elucidated. Here, we isolated and identified a novel transcription factor in the WD40 family of S. miltiorrhiza, SmWD40-2, which was screened from an S. miltiorrhiza cDNA library for the first time. Bioinformatic analysis found SmWD40-2 is most homologous to SsWD40 in Salvia splendens. We functionally analyzed SmWD40-2 through overexpressed and silenced it in the S. miltiorrhiza hairy roots system. The results showed that overexpression of SmWD40-2 increased both the two groups of bioactive ingredients. Among them, T-I content reached peak to 40.5 mg/g and SAB contents reached peak to 6.0 mg/g in OW-2 and OW-3 lines respectively. Besides, silencing of SmWD40-2 by RNAi lead to a lower bioactive ingredients content. Additionally, the inside pathway genes in tanshinones and phenolic acids biosynthesis were detected in both SmWD40-2 transgenic lines. SmWD40-2 regulated most key genes expression in the two target compounds (typically PAL1, C4H1, CYP98A14, RAS, DXS2, HMGR, GGPPS, CPS1, CPS5, KSL1 and CYP76AH1). Taken together, SmWD40-2 may be a suitable candidate for positive regulator in gene metabolic engineering of S. miltiorrhiza.

Automated summary

This study identified a novel transcription factor, SmWD40-2, in Salvia miltiorrhiza, which plays an important role in the biosynthesis of tanshinones and phenolic acids. Overexpression of SmWD40-2 increased the content of bioactive compounds, while silencing SmWD40-2 reduced the content of bioactive compounds.