RESUMO
Steroidal saponins are efficacious substances wildly existed in the herbs，and consist of glycosyl and steroid sapogenin. The biosynthesis pathways of steroidal saponins mainly include the cytosolic mevalonate （MVA） pathway and the plastidial methylerythritol 4-phosphate （MEP） pathway，with the MVA pathway as the main pathway. The key enzymes are involved in the biosynthetic pathway, including 3-hydroxy-3-methyl glutaryl coenzyme A reductase（HMGR），1-deoxy-D-xylulose 5-phosphate synthase（DXS），1-deoxy-D-xylulose-5-phosphatereduetoisomerase（DXR），farnesyl pyrophosphate synthase（FPS），squalene synthase（SS），squalene epoxidase（SE），cycloartenol synthase（CAS），cytochrome P450（CYP450），and steroidalglycosyltransferase（SGTase）. In the paper，the biosynthesis roadmap of steroidal saponins was optimized based on previous studies. According to a comprehensive analysis on studies of key enzymes for the past five years, genes, like HMGR，SS，CYP450 and UGT，were studied more，while other genes，like FPS，SE，CAS，were known less. In conclusion， current studies still focus on the primary stage，but lack direct evidence for the roles of key enzymes. This paper would provide a reference and theoretical support for subsequent studies.