Multi-omics reveals novel CYP450s and transcription factors regulating triterpenoid biosynthesis in Aralia elata

Aralia elata, a medicinal plant rich in oleanane-type triterpenes, relies on cytochrome P450 monooxygenases (CYP450s) for sapogenin formation. In this study, we identified three novel CYP450 genes: AeCYP716U6, AeCYP72A1298, and AeCYP72A760 combining multi-omics analysis. Heterologous expression in yeast demonstrated that AeCYP716U6 possessed C-28 oxidation activity on β-amyrin, resulting in the biosynthesis of oleanolic acid, whereas AeCYP72A1298 and AeCYP72A760 mediated the C-23 oxidation of oleanolic acid, leading to hederagenin formation. Overexpression in A. elata leaves and calli enhanced oleanolic acid and hederagenin levels. Y1H assays and dual-luciferase analyses confirmed that an ERF-type transcription factor AeERF12 could bind to the AeCYP716U6 promoter, activating its expression and promoting oleanolic acid biosynthesis. In contrast, AeWRKY28 and AeMYB44 suppressed AeCYP72A1298 expression, thereby reducing hederagenin accumulation. Additionally, ABA, GA, and MeJA were identified to regulate the saponin biosynthesis by inducing the expressions of these CYP450s and transcription factors.