Melatonin-mediated regulation of fruit quality and physicochemical attributes: current advances and future perspectives.

Fruit composition and quality vary widely with environmental conditions and postharvest handling, with substantial losses occurring during harvest, transport, and storage. Melatonin (MT), a multifunctional indoleamine, has recently gained attention as a natural, eco-friendly treatment to enhance fruit quality and extend storage life. This review summarizes recent studies on MT applications in various horticultural fruits, including peach, grape, strawberry, mango, kiwifruit, apple, cherry, jujube, pomegranate, banana, tomato, and citrus. MT is typically applied via immersion, spraying, or dipping, frequently in combination with refrigerated or controlled-atmosphere storage conditions. Across fruit types, MT consistently improves firmness, total soluble solids, and titratable acidity, while preserving bioactive compounds and reducing weight loss, respiration rate, ethylene production, and oxidative stress indicators such as malondialdehyde and electrolyte leakage. Protective effects are linked to enhanced defense enzyme activities (SOD, CAT, POD, APX), improved membrane stability, regulation of phenylpropanoid metabolism and the ascorbate-glutathione cycle, and suppression of senescence-related gene expression. Overall, evidence supports MT as a promising, sustainable postharvest treatment to improve fruit quality and prolong shelf life in commercial supply chains.