Silicon-mediated drought tolerance in Vigna mungo through coordinated regulation of aquaporin genes, plant water relations and photosynthetic processes.
TL;DR
Investigation of the role of silicon in mitigating drought-induced damage in two mash bean cultivars found it significantly enhances drought tolerance in mash bean by improving photosynthesis efficiency, antioxidant capacity, and molecular regulation of water transport.
Abstract
Drought stress restricts growth and productivity in grain legumes, yet the integrative mechanisms underlying silicon-mediated drought tolerance in Vigna mungo (mash bean) remain poorly understood. The present study aimed to investigate the role of silicon in mitigating drought-induced damage in two mash bean cultivars. To evaluate this effect, plants were subjected to different drought regimes with and without silicon. Data on growth traits, biomass accumulation, reproductive attributes, photosynthetic gas exchange parameters, water relations, antioxidant enzyme activities, phenolic compounds, nutrient dynamics, and expression of drought-responsive genes were collected and statistically analyzed. Multivariate analyses, including PCA and structural equation modeling (SEM), were used to elucidate relationships among measured variables. Drought significantly reduced plant growth, biomass production, and reproductive traits, accompanied by marked declines in net assimilation rate (up to 35-40%), stomatal conductance, and transpiration under 25% field capacity (FC). In contrast, drought increased WUE (49.7-56.2 µmol CO₂ mmol⁻1 H₂O), antioxidant enzyme activities, and phenolic accumulation. Silicon supplementation substantially improved plant growth, restored photosynthetic performance, and enhanced antioxidant defense under drought conditions. Si-treated plants exhibited increased activities of SOD, CAT, and APX, higher phenolic content, improved water status, and upregulated expression of DREB2A, PIP2-1, and TIP4-1 compared with non-supplemented plants. Multivariate analyses clearly separated drought and Si treatments, while SEM revealed strong relationships linking gene expression, biochemical defense systems, physiological processes, and plant growth responses. In conclusion, silicon supplementation significantly enhances drought tolerance in mash bean by improving photosynthetic efficiency, antioxidant capacity, and molecular regulation of water transport.