Time-resolved analysis of UV-B-induced secondary metabolite biosynthesis and gene expression in Plantago major L.

The medicinal plant Plantago major L. is known for its rich secondary metabolite content, which plays a critical role in its therapeutic properties. This study investigates the impact of UV-B radiation on the biosynthesis of secondary metabolites, including phenolic compounds, flavonoids, terpenes, carotenoids, and lycopene, as well as the expression of key biosynthetic genes (PAL, DAHP synthase, HMGR, COMT, and Epoxidase) in Plantago major. Plants were exposed to UV-B radiation for 1 and 2 h, and metabolite content and gene expression were measured at intervals of 3, 6, 9, and 12 h post-exposure. Results revealed a significant increase in secondary metabolite accumulation under UV-B stress, with phenolic and terpenoid content showing the highest elevation after 12 h of exposure. Gene expression analysis indicated that PAL and HMGR exhibited the most pronounced upregulation, correlating with increased metabolite production. These findings suggest that controlled UV-B exposure can be used to enhance the production of valuable secondary metabolites in Plantago major, potentially benefiting medicinal plant cultivation and pharmaceutical applications.