Research Projects

Plant-specialized metabolites are biosynthesized and stored in various locations, including cells, subcellular organelles, and long-distance transport. Triterpenes, a major class of specialized metabolites, accumulate on the plant surface, particularly in the cuticular wax, suggesting their potential role in biotic and abiotic stress response. The triterpene transport mechanism is poorly understood, with oxididosqualene cyclases (OSCs) and cytochrome P540 monooxygenases (P450s) being crucial scaffold-diversifying enzymes in the triterpene pathway. The study identifies OSCs (ObAS1/ObAS2) and P450s (CYP716A252/CYP716A253) involved in the biosynthesis of medicinally-important triterpenes ursolic acid (UA) and oleanolic acid (OA) in basil (Ocimum basilicum). UA and OA are biosynthesized in leaf epidermal cells and stored on the plant surface. The active transport of metabolites across the plasma membrane requires transporters, but the mechanism of UA/OA transport from the site of biosynthesis to the site of storage is not well understood. The study aims to understand the kinetics of UA/OA transport across the plasma membrane to provide insight into the active transport of UA/OA. The study also identifies seven MeJA-inducible transcripts encoding transporters, including ATP-binding cassette (ABC) and nitrate/peptide (NPF) family transporters. Functional characterization of candidate transporters is planned to understand their involvement in UA/OA transport across the cell membrane. In conclusion, this study will provide fundamental knowledge of triterpene transport, which can be applied to plant improvement and triterpene production in heterologous hosts.