Abstract
Panax japonicus C. A. Mey. var. major (Burk.) C. Y. Wu et K. M. Feng is an essential medicinal plant in the genus Panax of the family Araliaceae. Research on the triterpenoid saponin biosynthesis pathway in P. japonicus var. major is currently limited. This study employed widely targeted metabolomics technology based on UPLC-MS/MS to detect 384 metabolites in the rhizomes, internodes, leaves, petioles, and stems of P. japonicus var. major. Triterpenoid saponins exhibited tissue-specific accumulation: the underground parts mostly contained oleanane-type saponins. In contrast, the aboveground parts mostly contained dammarane-type saponins. Transcriptome sequencing of rhizomes and leaves in P. japonicus var. major identified 26,988 differentially expressed genes and 87 key enzyme genes involved in triterpenoid saponin biosynthesis. β-AS was remarkably upregulated in rhizomes, confirming the specific accumulation of oleanane-type triterpenoid saponins in underground rhizomes, which was corroborated by metabolomic data. This study reveals the tissue-specific regulatory characteristics of oleanane-type triterpenoid saponin biosynthesis, laying a theoretical foundation for further research on related metabolic pathways.