Positive regulation Asperosaponin VI accumulation by DaERF9 through JA signaling in Dipsacus asper

The ERF transcription factor can regulate the biosynthesis of various secondary metabolites, including triterpenoid saponins, in plants. DaERF9 has been found to be a potential regulatory factor in the accumulation of asperosaponin VI in Dipsacus asper. However, its underlying molecular mechanisms remain unclear. Here, we cloned the transcription factor DaERF9, which promotes the accumulation of asperosaponin VI in D.asper. Metabolomic analysis showed that wound stress significantly increased the content of asperosaponin VI and jasmonic acid, while the expression level of DaERF9 was markedly enhanced during this process, suggesting that DaERF9 plays a regulatory role in the wound-induced synthesis of asperosaponin VI by JA signaling pathway. Transgenic DaERF9 promoted the synthesis of precursor compounds of asperosaponin VI in Arabidopsis, activating the triterpenoid saponin biosynthesis pathway. MeJA induction enhanced the expression of the key enzyme gene DaHMGCR, which is involved in the synthesis of asperosaponin VI in transgenic DaERF9. Wound treatment markedly increased the transcriptional level of DaERF9 and the content of JA, and DaERF9 was able to interact with the DaHMGCR promoter, activating the activity of DaHMGCR. Overall, our findings suggest that DaERF9 plays a crucial role in the synthesis of asperosaponin VI in D. asper and elucidate the transcriptional regulatory mechanism of JA-induced accumulation of asperosaponin VI.