Dissecting the biosynthesis, regulation, and metabolic engineering of steroidal glycoalkaloids in tomato

Steroidal glycoalkaloids (SGAs) are predominantly found in Solanaceous plants, including tomato (Solanum lycopersicum). In addition to their roles in resistance to herbivores, pathogens, and environmental stresses, SGAs exert antifungal, antibacterial, and anticancer effects. Over the past 15 years, the biosynthesis pathway of SGAs in tomato has been progressively investigated. A growing number of intermediate compounds and novel biosynthetic enzymes have been identified. In addition, various regulatory factors and their underlying regulatory mechanisms governing SGAs biosynthesis have been increasingly elucidated. Building upon these advances in understanding the SGAs biosynthetic pathway and its regulatory network, metabolic engineering of the SGAs pathway in tomato has been achieved using techniques such as gene editing. This mini review summarizes the current understanding of SGAs biosynthesis and regulatory mechanisms in tomato, and provides an overview of recent progress and future perspectives in metabolic engineering applications targeting this pathway.