Synergistic enhancement of biomass and pharmacologically active metabolites in Isatis tinctoria L. via optimized...

Isatis tinctoria L., a medicinal plant predominantly distributed across China and East Asia, exhibits significant demand due to its extensive pharmacological applications. The optimal supplemental light environment promotes plant growth and metabolic processes. However, the effects of different supplemental light environments on the growth, metabolism, and medicinal quality of I. tinctoria remain poorly understood. This study employed LED supplemental lighting with red light (R), blue light (B), and different combinations of Red and Blue light (3R:1B, 1R:1B, and 1R:3B) on I. tinctoria seedlings, while utilizing non-supplemented lighting conditions as a control (CK). The results showed that: 1) 3R:1B significantly enhanced photosynthesis and growth of I. tinctoria, while exhibiting superior efficacy in mitigating membrane lipid peroxidation-induced damage. 2) 3R:1B resulted in the accumulation of alkaloids ((R,S)-goitrin, indigo and indirubin) and nucleosides (uridine, guanosine, and adenosine), which are pharmacologically active metabolites of I. tinctoria. 3) Composite lights elevated primary metabolites (sugars, amino acids, organic acids), with 3R:1B specifically enhancing sugars biosynthesis and 1R:3B increasing amino acids and organic acids. Metabolite accumulation correlated with the TCA cycle, glycolytic pathway, and other pathways, promoting growth and pharmacologically active metabolites synthesis. 4) 3R:1B exhibits broad adaptability to diverse cultivation objectives, achieving the highest quality-yield index through synergistic optimization of agronomic and phytochemical metrics. Overall, 3R:1B lighting synergistically improves both biomass and pharmacologically active metabolite yields in I. tinctoria. This will increase the agricultural productivity of I. tinctoria, providing an efficient cultivation strategy to meet pharmaceutical demands.