Melatonin Treatment Mitigates Chilling Injury in “Keitt” Mango Fruit Through Its Inhibition of Membrane Lipid Degradation and Peroxidation

Mango fruit is vulnerable to chilling injury (CI) when kept below 13°C, primarily due to cell membrane damage. In this study, the effects of melatonin (MLT) treatment on regulating membrane lipid degradation and peroxidation associated with CI alleviation in mango fruit ( Mangifera indica L. cv. “Keitt”) were investigated after the fruit were dipped in 0 (as the CK) and 0.1 mM MLT solution for 30 min and then stored at 5°C for 21 days, followed by 7 days of shelf life (25°C). The results indicated that MLT treatment effectively prevented CI development in mangoes, as evidenced by a lower CI index in MLT‐treated fruit compared to the CK. MLT treatment suppressed the activities of membrane lipid‐degrading enzymes, including phospholipase C (PLC), phospholipase D (PLD), and lipase (LIPS). Lipidomics analysis detected 87 lipids in both MLT‐treated and CK mango exocarp tissues. Compared to the CK, MLT treatment exhibited lower levels of phosphatidic acid (PA), lysophospholipids (LPLs), and diglyceride (DG) during storage. Moreover, MLT treatment modulated the fruit’s fatty acid profile by increasing the content of unsaturated fatty acids (USFAs) such as palmitoleic acid and oleic acid (except 21 + 7 days) while reducing the content of saturated fatty acids (SFA) such as arachidonic acid (except 21 + 7 days) and heneicosanoic acid (except 21 days) and decreased lipoxygenase activity and malondialdehyde level in the fruit during storage. Collectively, these findings suggested that MLT treatment reduced membrane lipid degradation and peroxidation, which benefited membrane integrity and, in turn, alleviated CI in mango fruit during postharvest.