MYB transcription factors play vital roles in plant growth and metabolism.The phytohormone methyl jasmonate(MeJA)promotes phenolic acid accumulation in the medicinal herb Salvia miltiorrhiza,but the regulatory mechanism is poorly understood.Here,we identified the MeJA-responsive R2R3-MYB transcription factor gene 5mMYB2 from a transcriptome library produced from MeJAtreated S.mi'/horr/ifza hairy roots.Sm/VIYB2 expression was tightly correlated with the expression of key salvianolic acid biosynthetic genes including CYP^8Ai^.5mMYB2 was highly expressed in the periderm of S.miltiorrhiza and SmMYB2 localized to the nucleus.Overexpressing Sml\AYB2 in S.miltiorrhiza hairy roots significantly increased the levels of salvianolic acids(including rosmarinic acid and salvianolic acid B)by upregulating salvianolic acid biosynthetic genes such as CYP98A14.SmMYB2 binds to the MYB-binding motifs in the promoter of CYP98A14,as confirmed by a dual-luciferase assay and electrophoretic mobility shift assays.Anthocyanin contents were significantly higher in Sm/ViyB2-overexpressing hairy root lines than the control,primarily due to the increased expression of CHI,DFR,and ANS.These findings reveal the novel regulatory role of SmMYB2 in MeJA-mediated phenolic acid biosynthesis,providing a useful target gene for metabolic engineering and shedding light on the salvianolic acid regulatory network.
Changping DengYao WangFenfen HuangSunjie LuLimei ZhaoXingyuan MaGuoyin Kai
