MYC2b Enhances Tanshinone Accumulation in by Activating Pathway Genes and Promoting Lateral Root Development.

Bunge (Lamiaceae) is an economically important medicinal plant as well as an emerging model plant. Our previous studies indicate that MYC2b is a positive transcription factor that can affect the biosynthesis of phenolic acids and tanshinones in Moreover, MYC2s are well known to induce the development of lateral roots. As tanshinones are mainly distributed in the periderm, the promotion of lateral root development probably leads to increased accumulation of tanshinones. In this paper, we firstly discovered that MYC2b played a dual regulatory role in effectively enhancing the tanshinone accumulation by activating tanshinone biosynthetic pathway and promoting lateral root development. The expression levels of the previously studied pathway genes , , , , and dramatically increased. In addition, MYC2b was proved to exhibit a similar function as other homologs in promoting lateral root development, which increased the tanshinone produced tissue and further enhanced the biosynthesis of tanshinones. RNA-seq assays revealed that MYC2b-regulated genes comprised 30.6% (1,901 of 6,210) of JA-responsive genes, confirming that MYC2b played a crucial role in transcriptional regulation of JA-regulated genes. Overall, we concluded that MYC2b could enhance tanshinone accumulation by activating the tanshinone biosynthetic pathway and promoting lateral root development. Our study provides an effective approach to enhance the production of desired tanshinones and enriches our knowledge of the related regulatory network.