ABSTRACT
Melatonin is a pleiotropic molecule with many diverse actions in plants. It is involved in multiple physiological processes including growth, rooting, seed germination, photosynthesis, osmoregulation, and protection against biotic and abiotic stressors including salinity. Salinity alone leads to multitudinous damage in plants. Plants respond to salt stress via several biochemical and molecular mechanisms that operate at the cellular and whole-plant levels. Many investigations revealed that melatonin can increase salt tolerance in plants. Melatonin regulation and function in plants have recently been intensively and profoundly explored, and regulatory systems connected to melatonin have been revealed in increasing numbers. Endogenous production and exogenous application of melatonin ameliorate the harmful aspects of salinity-induced stress and activate various kinds of defensive strategies. Melatonin can also influence salt-protective compounds like sugar, proline, malonaldehyde, antioxidant enzymes, etc. It promotes some physiological processes in plants associated with growth responses and recovery from salt injury. Melatonin can also act as a signalling molecule and interact with several signalling pathways associated with salt tolerance. In this chapter, we have critically discussed the role of melatonin on salt tolerance in plants from the seed germination stage to the maturation stage.
