SmMYC2b Enhances Tanshinone Accumulation in Salvia miltiorrhiza by Activating Pathway Genes and Promoting Lateral Root Development

• Published in: Frontiers in plant science Vol. 11; p. 559438
• Main Authors: Zhou, Yangyun, Feng, Jingxian, Li, Qing, Huang, Doudou, Chen, Xiao, Du, Zenan, Lv, Zongyou, Xiao, Ying, Han, Yonglong, Chen, Junfeng, Chen, Wansheng
• Format: Journal Article
• Language: English
• Published: Frontiers Media S.A 11.09.2020
• Subjects: lateral root development; Plant Science; Salvia miltiorrhiza; SmMYC2b; tanshinone biosynthesis; transcriptome
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2020.559438

Salvia miltiorrhiza Bunge (Lamiaceae) is an economically important medicinal plant as well as an emerging model plant. Our previous studies indicate that Sm MYC2b is a positive transcription factor that can affect the biosynthesis of phenolic acids and tanshinones in S. miltiorrhiza. 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 Sm 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 SmCPS1 , SmKSL1 , SmCYP76AH1 , SmCYP76AH3 , and SmCYP76AK1 dramatically increased. In addition, Sm 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 Sm MYC2b-regulated genes comprised 30.6% (1,901 of 6,210) of JA-responsive genes, confirming that Sm MYC2b played a crucial role in transcriptional regulation of JA-regulated genes. Overall, we concluded that Sm 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.