Regulation mechanism of transcription factor WRKY on SE gene, a key enzyme in triterpenoid saponin synthesis of Panax japonicum

In this study, a cDNA library from the rhizomes of P. japonicus was first constructed. Using yeast one-hybrid technology with the W-box cis-acting element in the SE gene promoter as bait, candidate PjWRKY transcription factors interacting with it were screened and cloned. The sequence characteristics of the candidate PjWRKYs were analyzed bioinformatically, and their expression patterns in different tissues (root, stem, leaf, fruit) of P. japonicus were detected using quantitative real-time PCR (qRT-PCR). Furthermore, through Agrobacterium-mediated genetic transformation, the screened PjWRKY gene was heterologously overexpressed in the medicinal plant Gynostemma pentaphyllum. By measuring the expression level of the SE gene and the accumulation of saponins in transgenic materials, the transcriptional regulatory function of the PjWRKY transcription factor on the SE gene and its promoting effect on saponin biosynthesis were verified, thereby elucidating the synergistic mechanism between PjWRKY and SE in the saponin synthesis pathway of P. japonicus. The research successfully cloned and obtained WRKY transcription factors regulating TS synthesis from P. japonicus, clarifying their transcriptional activity and tissue-specific expression characteristics. This study will provide key genetic resources and a theoretical basis for in-depth revelation of the transcriptional regulatory network of TS biosynthesis in P. japonicus, laying the foundation for subsequent metabolic engineering or molecular breeding to increase the content of medicinal components in P. japonicus and achieve its genetic improvement and sustainable resource utilization.