Positive Regulatory Role of Melatonin in Conferring Drought Resistance to Plants

Drought stress negatively affects the physiology, biochemistry, and morphology of plants. This leads to leaf rolling, leaf scorching, stunning plants, and permanent wilting. Plants adapt different strategies to build stress tolerance by enhancing the production of certain phytohormones. Melatonin is synthesized in plants in response to biotic and abiotic stresses, performing an important role as a plant growth regulator under environmental stresses Melatonin, a natural hormone, is widely found in animals, plants, protists, bacteria, and fungi. It is present in the roots, stems, leaves, fruits, and seeds of the plant in varying concentrations. The presence of melatonin has been revealed in coffee, corn, rice, barley, wheat, and oats. The role of melatonin in plant growth, development, and photosynthesis is well known. Melatonin potentially gives protection to the plants by improving reactive oxygen species (ROS) scavenging efficiency thereby safeguarding photosynthetic apparatus from drought led oxidative stress. In this chapter, the role of melatonin in plant stress tolerance during drought through the cascade of physiological and molecular mechanisms will be discussed.