Advances in biosynthesis of triterpenoid saponins in medicinal plants

In recent years, biosynthesis of triterpenoid saponins in medicinal plants has been widely studied because of their active ingredients with diverse pharmacological activities. Various oxidosqualene cyclases, cytochrome P450 monooxygenases, uridine diphosphate glucuronosyltransferases, and transcription factors related to triterpenoid saponins biosynthesis have been explored and identified. In the biosynthesis of triterpenoid saponins, the progress of gene mining by omics-based sequencing, gene screening, gene function verification, catalyzing mechanism of key enzymes and gene regulation are summarized and discussed. By the progress of the biosynthesis pathway of triterpenoid saponins, the large-scale production of some triterpenoid saponins and aglycones has been achieved through plant tissue culture, transgenic plants and engineered yeast cells. However, the complex biosynthetic pathway and structural diversity limit the biosynthesis of triterpenoid saponins in different system. Special focus can further be placed on the systematic botany information of medicinal plants obtained from omics large dataset, and triterpenoid saponins produced by synthetic biology strategies, gene mutations and gene editing technology.