Lipidomic signatures of heat tolerance in mungbean [Vigna radiata(L.) Wilczek] reveal reduced fatty acid unsaturation

Heat stress is a major environmental constraint limiting plant growth and productivity, including in mungbean (Vigna radiata). Although physiological, biochemical, and molecular responses of mungbean to elevated temperature have been widely investigated, the role of heat stress-induced leaf lipidome reconfiguration in thermotolerance remains insufficiently understood. In this study, we examined physiological, biochemical, and lipid metabolic responses to heat stress in two contrasting mungbean genotypes: PI425243 (heat-tolerant) and PI223002 (heat-sensitive), grown under non-stress (34/25 °C day/night) and heat stress (42/30 °C day/night) conditions. Heat stress significantly affected physiological traits, including chlorophyll index (SPAD), relative leaf water content, and electrolyte leakage, and altered biochemical responses, including proline accumulation, malondialdehyde content, and antioxidant enzyme activities (superoxide dismutase, peroxidase, and catalase). Lipidomic profiling identified 178 lipid species spanning major membrane lipid classes, including phospholipids and glycolipids, across both genotypes and treatments. Heat stress induced distinct lipid remodeling patterns between genotypes, with the heat-tolerant genotype PI425243 showing reduced membrane lipid unsaturation, reflected by lower proportions of polyunsaturated linolenic acid (18:3)-containing lipid species and increased abundance of less unsaturated and saturated fatty acids, particularly oleic (18:1) and linoleic (18:2)-containing species. Responsive lipid classes included major membrane phospholipids and chloroplast-associated glycolipids, indicating differential membrane adaptation under thermal stress. These findings suggest that heat-associated lipid remodeling is linked with enhanced membrane stability and improved heat adaptation in mungbean and highlight lipid signatures as potential biomarkers for screening climate-resilient genotypes.