Melatonin a Key Regulator of Cold Stress in Plants

Cold stress is one of the major abiotic factors which adversely affects plant growth and development, subsequently reducing productivity particularly, in temperate areas. Cold stress negatively induces various plant physiological, biochemical, and molecular processes by affecting photosynthetic activity, antioxidant defence mechanisms, and nutrient and water uptake, it ultimately alters crop developmental stages from seed germination to maturation. Therefore, applying melatonin can be considered an effective way to ameliorate cold stress for sustainable crop production. Melatonin is a multifunctional bio-stimulant which plays important role in enhancing plant performance by mitigating cold stress. Melatonin application improves plant growth and regulates metabolic activities by increasing photosynthetic efficiency, protecting cell structure, protecting plants from oxidative damage via the reduction in ROS levels, enhancing seed germination, and improving plant growth attributes, thus improving crop growth and productivity. However, the role of melatonin in cold stress is not well studied in plants and to our knowledge, there are only a few reports where melatonin has been used as cold stress alleviator. Hence, it is essential to understand the mechanisms of melatonin in mitigating cold stress tolerance. Such mechanisms can be greatly exploited to benefit agriculture production. In our chapter, we elaborated on the synthesis and regulation of melatonin and various physiological and molecular responses for inducing cold tolerance in plants.