Advancement in Melatonin Research in Plants

Abiotic stresses such as drought, salinity and temperature fluctuation are serious environmental constraints to achieve maximum crop production. From last few decades, melatonin ( N -acetyl-5-methoxytryptamine) has been found as a novel plant growth regulator having diverse physiological actions in crop plants. Phytomelatonin has been identified in more than 140 species in different concentrations depending upon environmental conditions, genotype and plant developmental stage. Melatonin application in crop plants strengthens plant defense mechanism against abiotic stresses by enhancing the activities of catalase (CAT), peroxidases (POD) and superoxide dismutase (SOD), protecting photosystem II, decreasing membrane leakage, chloroplast damage and improving cell expansion and leaf thickness. Moreover, melatonin plays a vital role in improving the germination, seedling growth and regulation of flowering in crop plants. This chapter discusses the role of melatonin as a plant growth regulator. Moreover, functions of melatonin in plant vegetative and reproductive development and its role as antioxidant under drought, heat and cold stress and salinity has also been described.