Comparative role of oxidative balance, alkaloid production, and metabolites in exposure to red-to-blue light in Catharanthus roseus.

Light quality is a critical regulator of plant morphology and physiological metabolism, with spectral optimization emerging as a key strategy for enhancing bioactive compound production in medicinal plants. Catharanthus roseus, valued for its alkaloid content, exhibits significant metabolic plasticity in response to light conditions. This study examined the effects of two red-to-blue light ratios [2:1 (R2B1) and 7:1 (R7B1)] on morphophysiological responses, metabolite profiles, and alkaloid accumulation in C. roseus, using white light as a control. Both R2B1 and R7B1 altered plant morphology and enhanced alkaloid synthesis. R2B1 notably increased antioxidant enzyme activity, while R7B1 boosted non-enzymatic antioxidants and phenolic compounds. The Integrative Biomarker Response version 2 analysis identified R7B1 as the optimal treatment for promoting the accumulation of bioactive compounds. Untargeted metabolomics revealed that R7B1 enhanced sugar levels and induced tissue-specific changes in organic acid metabolism. Correlation analysis suggested that red-to-blue light promotes alkaloid biosynthesis by modulating antioxidant systems and key metabolic pathways. These findings highlight the potential of red-to-blue light optimization to enhance alkaloid production in C. roseus, providing valuable insights into the regulation of secondary metabolism and practical strategies for improving bioactive compound yields in medicinal plants.