Emerging roles of melatonin in mitigating salinity stress of legumes.

• Melatonin is a multifunctional molecule that performs essential roles in environmental stress tolerance. • Exogenous melatonin plays a magnificent role in alleviating salt stresses by regulating oxidative damage, increasing chlorophyll content and photosynthetic rate, triggering plant hormones, accelerating antioxidants, and modulating transcription factors and stress-related genes in legumes. • Several transcription factors and regulatory genes that are responsible for melatonin-mediated salinity tolerance in legumes are highlighted. • For sustainability and food security, melatonin-mediated crop improvement in legumes can be explored to its fullest. Melatonin (N-acetyl-5‑methoxy tryptamine) is a multi-functional molecule that is distributed in all living organisms and it performs essential roles in environmental stress tolerance. Salt stress enhances the rapid accumulation of melatonin in plants. Melatonin provides resistance to salt stress by manipulating various regulatory mechanisms at the biochemical and molecular levels throughout different plant developmental stages. Conventionally, legumes are consumed along with cereal-based staples to ensure wholesome nutritional intake. After confirming their nutritional and health-promoting effects, recently their demand is constantly increasing. This has guided the researchers to focus on developing legumes to cope with the changing climate scenario. In legumes, melatonin concentration varies from crop to crop under salt stress. This review emphasizes melatonin biosynthesis in plants with a special focus on legumes and their responses to endogenous and exogenous melatonin application. This manuscript also throws light on the physiological, biochemical, and molecular basis of melatonin-mediated salinity stress tolerance in legumes. The future directions for enhancing the salt stress tolerance in legumes are also discussed. As, Melatonin promotes germination potential, seedling biomass, photosynthesis rate, pod number, and yield of legumes under the influence of salinity stress, this review can provide insights for using melatonin to develop salt stress tolerant legumes for sustainable food production. [ABSTRACT FROM AUTHOR]