Physiological and metabolomic profiling reveal key metabolic pathway responses in lentil (Lens culinaris Medikus) under alkali stress condition

Our study identified metabolite signatures associated with alkali tolerance in lentil. These metabolites represent promising candidate biomarkers and targets for future functional validation to determine their causal roles in alkali stress tolerance. Alkali stress greatly hinders the crop production and food security due to NaHCO 3 and Na 2 CO 3 toxicities. Lentil is a important and nutritious food legumes which is widely cultivated in the world. However, the physiological and metabolomics responses that enable lentil to tolerate alkaline conditions is poorly understood. In this study, two contrasting cultivars, L-4076 (alkali-sensitive) and PSL-9 (alkali-tolerant) were selected for profiling of physiological and metabolomic responses at the seedling stage under alkali stress condition. Tolerant cultivar exhibited less salt injury and performed better due to lesser reduction of root and shoot length and fresh and dry weight of roots and shoots, lower accumulation of Na + and greater accumulation of K⁺ compared to sensitive one. The relative water content and membrane stability index, activities of antioxidant enzyme, accumulation of osmolytes, and abscisic acid levels were higher in tolerant cultivar as compared to sensitive one under alkali stress. Metabolomic profile revealed a total of 75 metabolites in roots and shoots under alkali stress that include carbohydrates, sugar alcohols, amino acids, secondary metabolites and fatty acids. The ABC transporters, biosynthesis of plant secondary metabolites, galactose metabolism and unsaturated fatty acid biosynthesis pathways were the key pathways modulated under alkali stress condition. Our findings suggest that metabolites associated with carbohydrates, sugar alcohols, amino acids, secondary metabolites and fatty acids may serve as candidate biomarker for alkali tolerant cultivars of lentil.