Melatonin as plant growth regulator in sustainable agriculture.

• Melatonin maintains redox equilibrium (removing ROS and RNS), is a stress reduction agent, promotes root growth and development. • Encourages plant development, influences flowering and fruit ripening, prevents leaf senescence. • Improves gene expression and activity of enzymes, improves photosynthesis. • Shields plants from pathogen attack and influences other biochemical and physiological processes. Melatonin (N-acetyl-5-methoxytryptamine) is a biological indolamine. It is biologically synthesized in plants and can be used to promote sustainable agriculture. This molecule has multiple effects and a wide range of actions that are beneficial to plants. It plays an important role in plants as a modulatory agent (a bio-stimulator and plant growth regulator) that improves the plants tolerance to both biotic and abiotic stress (drought, waterlogging, severe temperatures, salt, alkalinity, chemical contaminants in soils (such as heavy metals, pesticides, and others), UV radiation). It acts as a stress-relieving hormone (regulates anti stress reactions) and as a bio-stimulator of plant growth. Melatonin maintains redox equilibrium (removing ROS and RNS), is a stress reduction agent, promotes root growth and development, encourages plant development, influences flowering and fruit ripening, prevents leaf senescence, improves gene expression and activity of enzymes, improves photosynthesis, shields plants from pathogen attack (regulates plant innate immunity, initiate defense responses) and influences other biochemical and physiological processes. This review explores these special functions of melatonin and how it impacts different plant systems specifically. Research is already ongoing in this field and through this compilation we can conclude that melatonin, a bio stimulator, is a crucial molecule that can be essential in increasing crop yields and nutraceutical values useful for addressing global food security issues. [ABSTRACT FROM AUTHOR]