Melatonin-Mediated Coordination of ROS Signaling, Physiological, and Hormonal Networks under Drought Stress

Abstract

: Drought stress stands out as a main abiotic factor that adversely influences the development, yield, and quality of plants. With the increasing prevalence of water scarcity driven by climate change, urban expansion, and industrial activities, understanding plant responses to limited water availability has become critically important. Among stress-related molecules, melatonin has gained recognition as a multipurpose regulator with a central role in strengthening plant tolerance to drought. The synthesis and accumulation of melatonin are influenced by environmental stressors and vary across plant species and tissue types. Whether synthesized internally or applied externally, melatonin contributes to drought mitigation by neutralizing reactive oxygen species (ROS), boosting the activity of enzymatic antioxidants, and modulating levels of non-enzymatic defense compounds. Additionally, it regulates stress-responsive genes and activates defense pathways intermediated by key phytohormones such as abscisic acid (ABA), salicylic, and gibberellins. Melatonin’s interaction with other hormonal signals including auxins, cytokinins, jasmonates, and ethylene creates a dynamic network of hormonal crosstalk that further strengthens plant tolerance mechanisms. Its beneficial effects are evident in improved photosynthetic efficiency, optimized stomatal behavior, enhanced seed germination, and stimulated root development. This review focus on the effects of melatonin in plants under drought conditions, highlighting its interplay with other signaling molecules and hormonal pathways. It further highlights recent progress and strategic approaches for utilizing melatonin in developing drought-resilient cultivars and enhancing agricultural sustainability.