ABSTRACT
Serotonin and melatonin are the essential indoleamines present in animals and plants. Melatonin is involved in multiple plant developmental processes and various stress responses. Melatonin has been shown to play important roles in the regulation of plant growth, development and responses to environmental stresses. However, the mechanism underlying the melatonin/serotonin-mediated signaling pathway in plant stress responses has not been established. Melatonin has been shown to increase its abiotic stress tolerance in response to stresses such as drought, salt stress, extreme temperature, chemical stresses, radiation and chilling stress. Stress signals can cause a higher accumulation of serotonin and melatonin. Moreover, the protective effect of exogenous MEL in plants has also been used to demonstrate its possible role as a cellular antioxidant. Exogenous melatonin or serotonin treatment conferred improved stress tolerance in crop plants. This chapter describes the protective role of SER and MEL in plants during various abiotic stresses viz. drought stress, salt stress, cold stress, metal stress, chemical stress, radiation, etc.
