Heterologous Expression of MYB Gene (Rosea1) or bHLH Gene (Delila) from Antirrhinum Increases the Phenolics Pools in Salvia miltiorrhiza

Phenolic acids have health-promoting properties, however, but their low concentrations in <i>Salvia miltiorrhiza</i> limit broader medicinal applications. MYB and bHLH transcription factors activate multiple target genes involved in phenylpropanoid metabolism, thereby enhancing the production of various secondary metabolites. We introduced the MYB transcription factor <i>Antirrhinum Rosea1</i> (<i>AmROS1</i>) or <i>Delila</i> (<i>AmDEL</i>) into <i>S. miltiorrhiza</i> and observed that antioxidant activity in transgenic plants increased by 1.40 to 1.80-fold. The total content was significantly higher in transformants compared to the controls. Furthermore, heterologous expression of <i>AmROS1</i> or <i>AmDEL</i> triggered moderate accumulations of rosmarinic acid and salvianolic acid at various growth stages. Levels of total phenolics, total flavonoids, and anthocyanins were significantly elevated. These biological and phytochemical alterations were correlated with the upregulated expression of genes involved in phenolic acid biosynthesis. Our findings demonstrate that <i>AmROS1</i> and <i>AmDEL</i> function as a transcriptional activator in phenolic acids biosynthesis. This study offers further insights into the heterologous or homologous regulation of phenolics production, potentially enabling its engineering in <i>S. miltiorrhiza</i>.