Advances in the function of cytochrome P450 in structural modifications of triterpenoid and sterol skeletons in plants

Plant triterpenes play important roles in plant growth and development, stress tolerance, pest and disease resistance, biological interactions, and signal transduction. Plant sterols possess important medicinal properties. Cytochrome P450 monooxygenase (CYP450) is the largest family of enzymes involved in plant metabolism, and the members of this family play keys role in the diversification and functional modifications of triterpenoid and sterol skeletons. To date, research has identified nearly 80 CYP450 enzymes involved in triterpene metabolism in plants, including the subfamilies CYP51H, CYP71A, D, CYP72A, CYP81Q, CYP87D, CYP88D, L, CYP93E, CYP705A, CYP708A, and CYP716A, C, E, S, U, Y. Together, they participate in the metabolism of triterpenoids and their saponins as well as chemical defense functions and pharmacological activities against specific pathogens. Enzymes in the subfamilies CYP51G, CYP85A, CYP90B-D, CYP710A, CYP724B, and CYP734A are generally involved in biosyntheses of sterols and steroidal hormones. In this article, we summarized modification functions of different CYP450 gene loci in biosyntheses of triterpenes and sterols, focusing on the evolution of 11 CYP450 gene subfamilies in terrestrial plants and their roles in biosyntheses of pentacyclic triterpenoids of dicotyledonous and monocotyledonous plants. We aim to provide a theoretical basis for the comprehensive use of anti-tumor and anti- acquired immunodeficiency syndrome triterpenoids in synthetic biology and metabolic regulation.