MiR408- Module Participates in Salvianolic Acid B Synthesis in .

MicroRNAs (miRNAs) are important regulators of gene expression involved in plant development and abiotic stress responses. Recently, miRNAs have also been reported to be engaged in the regulation of secondary plant metabolism. However, there are few functional studies of miRNAs in medicinal plants. For this study, we obtained -miR408 interference lines to investigate the function of -miR408 in a medicinal model plant (). It was found that inhibiting the expression of -miR408 could increase the content of salvianolic acid B and rosmarinic acid in the roots. The and -miR408 expression patterns were analyzed by qRT-PCR. A 5' RLM-RACE assay confirmed that -miR408 targets and negatively regulates . Moreover, the overexpression of in promoted the accumulation of salvianolic acids in the roots. Furthermore, the lignin content of the roots in overexpressed lines was decreased. Taken together, these findings indicated that -miR408 modulates the accumulation of phenolic acids in by targeting expression levels.