The SmMYB36-SmERF6/SmERF115 module regulates the biosynthesis of tanshinones and phenolic acids in salvia miltiorrhiza hairy roots

Abstract

Tanshinone and phenolic acids are the most important active substances of Salvia miltiorrhiza, and the insight into their transcriptional regulatory mechanisms is an essential process to increase their content in vivo. SmMYB36 has been found to have important regulatory functions in the synthesis of tanshinone and phenolic acid; paradoxically, its mechanism of action in S. miltiorrhiza is not clear. Here, we demonstrated that SmMYB36 functions as a promoter of tanshinones accumulation and a suppressor of phenolic acids through the generation of SmMYB36 overexpressed and chimeric SmMYB36-SRDX (EAR repressive domain) repressor hairy roots in combination with transcriptomic-metabolomic analysis. SmMYB36 directly down-regulate the key enzyme gene of primary metabolism, SmGAPC, up-regulate the tanshinones biosynthesis branch genes SmDXS2, SmGGPPS1, SmCPS1 and down-regulate the phenolic acids biosynthesis branch enzyme gene, SmRAS. Meanwhile, SmERF6, a positive regulator of tanshinone synthesis activating SmCPS1, was up-regulated and SmERF115, a positive regulator of phenolic acid biosynthesis activating SmRAS, was down-regulated. Furthermore, the seven acidic amino acids at the C-terminus of SmMYB36 are required for both self-activating domain and activation of target gene expression. As a consequence, this study contributes to reveal the potential relevance of transcription factors synergistically regulating the biosynthesis of tanshinone and phenolic acid.

Acknowledgements

We thank Ningjuan Fan, Xiyan Chen and Hui Duan of the Center for Teaching and Research Equipment, College of Life Sciences, Northwest A&F University for their technical support. This work was supported by the National Natural Science Foundation of China (Project No. 32270278).

Author contributions

P.M. and J.D. conceived the idea of the review and made the final modification. Q.L., X.F., and Y.Z. performed the experiments and data processing. R.C.provided assistance in the qPCR experiments. Q.L. and P.M. wrote the manuscript. All authors approved the final manuscript.

Data availability

Detailed data supporting the findings of this study can be found in the supplementary material.

Conflict of interest

The authors have no conflicts of interest to declare.

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