Mengying Jiao, Yaqi Cui, Junjin Ma, Xueying Zhao, Chenran Feng, Jingwen Ding, Yuehong Long, Zhaobin Xing
As the principal bioactive constituents of Eleutherococcus senticosus , triterpenoid saponins exhibit diverse pharmacological activities. The E . senticosus ethylene responsive factor ( Es ERF) critically regulates triterpenoid saponin biosynthesis; however, the specific EsERF TFs modulating this process in E. senticosus and their underlying mechanisms remain uncharacterized. This study identified four EsERF TFs associated with saponin synthesis. Among them, Es ERF66, Es ERF127, and Es ERF130 promoted saponin synthesis by upregulating the expression of the key biosynthetic enzymes EsFPS , EsSS , and EsSE , whereas Es ERF138 suppressed saponin synthesis by downregulating these enzymes . All four TFs were localized to the nucleus, and only Es ERF66 had self-transcriptional activation activity, the promoting efficacy of which was affected by light quality and DNA methylation. In addition, the four Es ERFs dynamically modulated the binding stability to their target genes by forming complexes with interacting proteins. Specifically, Es ERF66– Es CPI1, Es ERF127– Es IL1, and Es ERF130– Es ERFBP3 complexes enhanced the transcriptional activity of Es ERFs, whereas Es ERF127– Es IL1 and Es ERF138– Es CS1 complexes attenuated the regulatory effects of Es ERFs on target genes. In summary, Es ERFs can synergistically regulate triterpenoid saponin biosynthesis in E. senticosus through three mechanisms: direct binding to target genes, DNA methylation modification, and formation of Es ERF–protein interaction complexes.