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Front. Plant Sci. | doi: 10.3389/fpls.2019.01367

SmGRAS1 and SmGRAS2 Regulate the Biosynthesis of Tanshinones and Phenolic Acids in Salvia miltiorrhiza

Wenrui Li1, 2,  Zhenqing Bai3,  Tianlin Pei3, Dongfeng Yang4,  Renjun Mao3, Bingxue Zhang1, 2, Chuangfeng Liu3 and  Zongsuo Liang1, 4*
  • 1Institute of Soil and Water Conservation (CAS), China
  • 2University of Chinese Academy of Sciences, China
  • 3Northwest A&F University, China
  • 4Zhejiang Sci-Tech University, China

Salvia miltiorrhiza is one of the most widely used traditional Chinese medicinal plants because of its excellent performance in treating heart disease. Tanshinone and phenolic acid are two important metabolites, and their biosynthesis has attracted widespread interest. Here, we functionally characterized SmGRAS1 and SmGRAS2, two GRAS family transcription factors (TFs) from S. miltiorrhiza. SmGRAS1/2 were highly expressed in the root periderm, where tanshinones mainly accumulated in S. miltiorrhiza. Overexpression (OE) of SmGRAS1/2 upregulated tanshinones accumulation and downregulated GA and phenolic acids content and root biomass. However, antisense expression (AE) of SmGRAS1/2 reduced the tanshinones accumulation and increased the GA and phenolic acids contents and root biomass. The expression patterns of biosynthesis genes were consistent with the changes in compounds accumulation. GA treatment increased tanshinones, phenolic acids and GA contents in the OE lines, and restored the root growth inhibited by overexpressing SmGRAS1/2. Subsequently, yeast one-hybrid (Y1H) and electrophoretic mobility shift assays (EMSA) showed SmGRAS1/2 promoted tanshinone biosynthesis by directly binding to the GARE motif in the SmKSL1 promoter in a GA-independent pathway. Taken together, the results revealed that SmGRAS1/2 acted as repressors in GA-mediated root growth and phenolic acid biosynthesis but as positive regulators in tanshinone biosynthesis. Overall, our findings revealed the potential value of SmGRAS1/2 in genetically engineering changes in secondary metabolism.

Keywords: Salvia miltiorrhiza, SmGRAS1/2, GA, tanshinines, phenolic acids, biosynthesis

Received: 22 Jun 2019; Accepted: 04 Oct 2019.

Copyright: © 2019 Li, Bai, Pei, Yang, Mao, Zhang, Liu and Liang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Zongsuo Liang, Institute of Soil and Water Conservation (CAS), Yangling, 712100, Shanxi, China, zongsuoliang16@126.com