The SmERF1b-like regulates tanshinone biosynthesis in Salvia miltiorrhiza hairy root

The ethylene response factor family genes are involved in the regulation of secondary metabolism in Salvia miltiorrhiza, but the mechanism underlying this regulation remains elusive. In the present study, based on the cDNA library of S. miltiorrhiza, an AP2/ERF gene was cloned and named SmERF1b-like. This gene exhibited a significant response to exogenous ethylene supply, such that ethylene remarkably upregulated SmERF1b-like expression levels in the leaves of S. miltiorrhiza. Subcellular localization showed that SmERF1b-like is located in the nucleus. Furthermore, SmERF1b-like showed a binding affinity with a GCC-box motif in the promoter region of genes associated with tanshinone biosynthesis in S. miltiorrhiza. Overexpression of SmERF1b-like in hairy roots of S. miltiorrhiza substantially upregulated SmCPS1 and SmKSL1 expression levels, resulting in increased biosynthesis of tanshinone I and cryptotanshinone contents. This finding provides valuable theoretical support for the utilization of a plant genetic engineering strategy to enhance S. miltiorrhiza resources.