Integrative Analyses of Metabolome and Transcriptome Reveal Regulatory Network of Puerarin Biosynthesis in Pueraria montana var. lobata

Kudzu, scientifically known as <i>Pueraria montana</i> var. <i>lobata</i> (Willd.) Maesen & S.M.Almeida ex Sanjappa & Predeep (<i>P. lobata</i>), is a perennial vine belonging to the family Leguminosae. Puerarin, a unique constituent and primary active ingredient of this genus, exhibits a broad spectrum of pharmacological activities. This study started with several practical questions: Why is the root the main medicinal part? Why is it not peeled for medicinal purposes? Why is the harvest period usually from December to February? Although the puerarin biosynthesis pathway has been investigated, the stage at which the 8-C glycosylation reaction occurs remains controversial. In this study, metabolomics and transcriptomics analyses were performed on <i>P. lobata</i> organs and tissues, including leaves, young stems, mature stems, tuberous cortices, and cortex-excised tubers of roots. Two modules containing genes associated with puerarin biosynthesis were identified by WGCNA. The final selection of important candidate UDP-glucosyltransferases (UGTs) that may be involved in the puerarin biosynthesis pathway included two 8-C-GTs, three 7-O-GTs, and key transcription factors. On this basis, the regulatory network of puerarin biosynthesis was constructed and laid the foundation for the cultivation of high-quality medicinal kudzu with high puerarin content.