Melatonin as Master Regulator in Plant Growth, Development and Stress Alleviator for Sustainable Agricultural Production: Current Status and Future Perspectives

Abstract

Melatonin, a multifunctional signaling molecule, is ubiquitously distributed in different parts of a plant and responsible for stimulating several physiochemical responses against adverse environmental conditions in various plant systems. Melatonin acts as an indoleamine neurotransmitter and is primarily considered as an antioxidant agent that can control reactive oxygen and nitrogen species in plants. Melatonin, being a signaling agent, induces several specific physiological responses in plants that might serve to enhance photosynthesis, growth, carbon fixation, rooting, seed germination and defense against several biotic and abiotic stressors. It also works as an important modulator of gene expression related to plant hormones such as in the metabolism of indole-3-acetic acid, cytokinin, ethylene, gibberellin and auxin carrier proteins. Additionally, the regulation of stress-specific genes and the activation of pathogenesis-related protein and antioxidant enzyme genes under stress conditions make it a more versatile molecule. Because of the diversity of action of melatonin, its role in plant growth, development, behavior and regulation of gene expression it is a plant’s master regulator. This review outlines the main functions of melatonin in the physiology, growth, development and regulation of higher plants. Its role as anti-stressor agent against various abiotic stressors, such as drought, salinity, temperatures, UV radiation and toxic chemicals, is also analyzed critically. Additionally, we have also identified many new aspects where melatonin may have possible roles in plants, for example, its function in improving the storage life and quality of fruits and vegetables, which can be useful in enhancing the environmentally friendly crop production and ensuring food safety.

The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

“…Melatonin is a pleiotropic signal molecule that is known to maintain balance between the different physiological processes and protection of plants besides numerous abiotic stresses responses [ 10 , 11 ] both through endogenous manipulation or exogenous application [ 8 , 12 , 13 , 14 ]. It works as an antioxidative molecule to scavenge ROS [ 15 ] and protects photosynthesis [ 16 ].…”

“…It works as an antioxidative molecule to scavenge ROS [ 15 ] and protects photosynthesis [ 16 ]. It is referred to work by means of an antioxidant that regulates abiotic stress tolerance [ 14 ]. Melatonin changes the cell layer penetrability arbitrated through ion transporters, which regulates the stomatal opening and closing in plants.…”

“…Melatonin changes the cell layer penetrability arbitrated through ion transporters, which regulates the stomatal opening and closing in plants. Melatonin improves photosynthetic capacity of plants and upgrades the photosystem (PS) I and PS II, incites higher nitrogen and chlorophyll content and higher substance of dissolvable proteins and Rubisco [ 14 , 17 ]. Melatonin improved antioxidant system for enhancing tolerance to high temperature in tomato [ 18 , 19 ] and in wheat [ 9 ] by increasing transcription of stress-responsive genes that helped in enduring photosynthetic machinery and increasing resistance to heat stress.…”

The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

“…Melatonin changes the cell layer penetrability arbitrated through ion transporters, which regulates the stomatal opening and closing in plants. Melatonin improves photosynthetic capacity of plants and upgrades the photosystem (PS) I and photosystem II, incites higher nitrogen and chlorophyll content and higher substance of dissolvable proteins and Rubisco [14,17]. Melatonin improved antioxidant system for enhancing tolerance to high temperature in tomato [18][19] and in wheat [9] by increasing transcription of stress-responsive genes that helped in enduring photosynthetic machinery and increasing resistance to heat stress.…”

“…Melatonin improved antioxidant system for enhancing tolerance to high temperature in tomato [18][19] and in wheat [9] by increasing transcription of stress-responsive genes that helped in enduring photosynthetic machinery and increasing resistance to heat stress. In view of its diverse roles, melatonin is considered as a master regulator [14,20]. Moreover, melatonin shows interaction with different phytohormones and signalling molecules [17,21].…”