Tanshinone and salvianolic acid biosynthesis are regulated by SmMYB98 in Salvia miltiorrhiza hairy roots

Abstract

<i>Salvia miltiorrhiza</i> Bunge is an herb rich in bioactive tanshinone and salvianolic acid compounds. It is primarily used as an effective medicine for treating cardiovascular and cerebrovascular diseases. Liposoluble tanshinones and water-soluble phenolic acids are a series of terpenoids and phenolic compounds, respectively. However, the regulation mechanism for the simultaneous promotion of tanshinone and salvianolic acid biosynthesis remains unclear. This study identified a R2R3-MYB subgroup 20 transcription factor (TF), <i>SmMYB98</i>, which was predominantly expressed in <i>S. miltiorrhiza</i> lateral roots. The accumulation of major bioactive metabolites, tanshinones, and salvianolic acids, was improved in <i>SmMYB98</i> overexpression (OE) hairy root lines, but reduced in <i>SmMYB98</i> knockout (KO) lines. The qRT-PCR analysis revealed that the transcriptional expression levels of tanshinone and salvianolic acid biosynthesis genes were upregulated by <i>SmMYB98-OE</i> and downregulated by <i>SmMYB98-KO</i>. Dual-Luciferase (Dual-LUC) assays demonstrated that <i>SmMYB98</i> significantly activated the transcription of <i>SmGGPPS1</i>, <i>SmPAL1</i>, and <i>SmRAS1</i>. These results suggest that <i>SmMYB98-OE</i> can promote tanshinone and salvianolic acid production. The present findings illustrate the exploitation of R2R3-MYB in terpenoid and phenolic biosynthesis, as well as provide a feasible strategy for improving tanshinone and salvianolic acid contents by MYB proteins in <i>S. miltiorrhiza</i>.