Overexpression of SmSCR1 Promotes Tanshinone Accumulation and Hairy Root Growth in Salvia miltiorrhiza.

Wei Zhou,Shuai Wang,Itay Maoz,Guoyin Kai,Yunhui Liu,Tingyao Liu,Chengan Chen,Xiankui Gao,Can Wang,Yafang Shen

doi:10.3389/fpls.2022.860033

Abstract

Lipid-soluble tanshinone is one of the main bioactive substances in the medicinal plant Salvia miltiorrhiza, and its medicinal demand is growing rapidly. Yeast extract (YE) modulates the tanshinone biosynthesis, but the underlying regulatory network remains obscure. In this study, a YE-responsive transcriptional factor Scarecrow1 (SCR1) was identified in S. miltiorrhiza from the YE-induced transcriptome dataset. SmSCR1 is located in the nucleus. Overexpression of SmSCR1 in S. miltiorrhiza roots resulted in a significantly higher accumulation of tanshinone than the control, with the highest 1.49-fold increase. We also detected upregulation of tanshinone biosynthetic genes, SmSCR1 and SmHMGR1, and distinct alteration of growth and development of the hairy roots in the overexpression lines compared to the control. An inverse phenotype was observed in SmSCR1-SRDX suppression expression lines. We found that SmSCR1 can bind to the promoter of SmCPS1 to induce its expression. This study provides new insight into the regulatory mechanism on the growth and development of hairy roots, tanshinone accumulation, and the metabolic engineering of bioactive compounds in S. miltiorrhiza.

Highlights

Salvia miltiorrhiza Bunge is a Chinese herbal medicine that belongs to the Salvia genus in the Lamiaceae family (Jia et al, 2019; Jung et al, 2020)
The two genes were drastically downregulated in the three SRDX lines (i.e., 2, 4, and 6), with the SmSCR1-SRDX-6 line exhibiting the lowest decrease compared to the control (Figure 5B). These findings showed that SmSCR1 stimulated copalyl diphosphate synthase 1 (CPS1) and 3-hydroxy-3-methylglutaryl-CoA-reductase I (HMGR1) together, resulting in increased production in transgenic hairy roots of S. miltiorrhiza
The GRAS transcription factors (TFs) family is an important TF class involved in regulating plant growth, development, environmental stress response, and growth signal transduction (Sun et al, 2011)

Summary

Introduction

Salvia miltiorrhiza Bunge is a Chinese herbal medicine that belongs to the Salvia genus in the Lamiaceae family (Jia et al, 2019; Jung et al, 2020). In Asian countries, dried roots and stems of S. miltiorrhiza are a common treatment for cardiovascular system-related diseases (Hao et al, 2015). The bioactivity of S. miltiorrhiza is associated with lipid-soluble tanshinones, including tanshinone I (TA-I), cryptotanshinone (CT), dihydrotanshinone (DT), and tanshinone IIA (TA-II) (Fu et al, 2020). Increasing attention has been given to the abovementioned compounds in recent years, mainly focusing on improving the yield of tanshinone in S. miltiorrhiza.

Methods

Results

Conclusion