Abstract : Methoxylated flavones in Artemisia argyi , especially eupatilin, are important bioactive components with antibacterial, anti-inflammatory, and anti-tumor activities. Exogenous treatment with methyl jasmonate (MeJA) significantly promoted the contents of methoxylated flavones in A. argyi . However, the molecular regulatory mechanism underlying MeJA-induced methoxylated flavone biosynthesis remains largely unclear in A. argyi . In this study, transcriptional analysis following MeJA treatment revealed that key genes involved in the flavonoid biosynthetic pathway, including PAL , CHI , and CHS , as well as the critical flavonoid O -methyltransferase gene AYFOMT2 , were significantly induced. Meanwhile, the MYB transcription factor family exhibited the most pronounced response to MeJA induction. Based on expression profiling, three key candidate genes, AYMYB13 , AYMYB15 , and AYMYB16 , were screened and identified. To further characterize their regulatory mechanism in methoxylated flavones biosynthesis, yeast one-hybrid and dual-luciferase assays confirmed that AYMYB13, AYMYB15, and AYMYB16 directly bind to the promoter of AYFOMT2 , thereby promoting the accumulation of eupatilin. Futhermore, overexpression of these three MYB transcription factors in A. argyi calli significantly increased the content of eupatilin. Our study demonstrated that AYMYB13 , AYMYB15 , and AYMYB16 were key regulators for activating the expression of AYFOMT2 in MeJA-induced methoxylated flavones accumulation. These findings will provide a theoretical foundation for improving eupatilin content and biosynthetic efficiency in A. argyi . • Three MeJA-responsive MYB transcription factors were identified and characterized. • AYMYB13, AYMYB15 and AYMYB16 can directly bind to and activate the promoter of AYFOMT2. • Overexpression of AYMYBs significantly increases eupatilin accumulation in transgenic calli.
Peng et al. (Fri,) studied this question.