PgERF13 and PgbHLH14 mediate jasmonate-induced protopanaxadiol-biased ginsenoside biosynthesis in Panax ginseng.

چکیده اصلی

Ginsenosides are the major bioactive triterpene saponins in ginseng (Panax ginseng) and are important determinants of its medicinal value. In vitro propagation of ginseng adventitious roots enables large-scale production of ginseng biomass under controlled culture conditions, and methyl jasmonate (MeJA) is widely used to enhance ginsenoside accumulation in this system. However, how jasmonate signaling activates ginsenoside biosynthesis and reshapes ginsenoside composition remains unclear. Here, we found that MeJA treatment markedly increased total saponin content and shifted ginsenoside composition toward protopanaxadiol (PPD)-type compounds in bioreactor-cultured ginseng adventitious roots. Time-course transcriptomic analysis identified 2 early MeJA-responsive transcription factors, PgERF13 and PgbHLH14, whose overexpression in transgenic ginseng calli enhanced ginsenoside accumulation. Mechanistically, PgbHLH14 recognized E-box motifs in a distinct set of promoters and enhanced both PPD- and protopanaxatriol (PPT)-type ginsenosides, while increasing the PPD/PPT ratio. In contrast, PgERF13 bound DRE/CRT promoter elements in multiple biosynthetic gene promoters, broadly increasing pathway output with little effect on the PPD/PPT ratio. Moreover, PgERF13 and PgbHLH14 independently activated PgNAC72, a known positive regulator of ginsenoside biosynthesis, through distinct DRE/CRT and E-box promoter elements. Thus, the PgERF13/PgbHLH14-PgNAC72 module links jasmonate signaling to coordinated activation of dammarane-type ginsenoside biosynthesis and PPD-biased accumulation. This study provides insight into the transcriptional network controlling MeJA-induced ginsenoside biosynthesis in ginseng.

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