Melatonin: A biomolecule for mitigating postharvest chilling injury in fruits and vegetables

The best strategy to extend the shelf life of fresh horticultural produce is to keep it at a low temperature. However, storing fruits and vegetables at a temperature lower than their recommended storage temperature and above the freezing point for a prolonged time leads to the development of chilling injury (CI). Melatonin (MT) being a versatile biological signal has been reported to possess antioxidant properties that aid in mediating stress response and extending the postharvest storage life of horticultural crops. Among CI‐induced mechanisms, MT substantially reduces oxidative stress by elevating the reactive oxygen species scavenging and triggering the phenol accumulation in association with 2, 2‐diphenyl‐1 picryl hydrazyl scavenging activity. Besides, MT increases intracellular energy by maintaining a proper ratio of unsaturated to saturated fatty acid and improving cellular fluidity. Additionally, MT regulates arginine metabolism by maintaining the γ‐aminobutyric acid synthesis. Furthermore, MT encodes the mitogen‐activated protein kinases, and calcium‐dependent protein kinases cascade and acclimate to cold stress by activating C‐repeat binding factors and helps in maintaining postharvest quality. This review reports the recent progress of MT‐induced physiological, biochemical, and molecular mechanisms for enhancing chilling tolerance, which can elevate the marketability and earnings from postharvest horticultural crops. Chilling injury during storage is a common problem in fruits and vegetables. Melatonin plays a vital role in mitigating postharvest chilling injury. Melatonin increases intracellular energy by maintaining a proper ratio of unsaturated to saturated fatty acid. Melatonin imparts chilling tolerance via reactive oxygen species, arginine pathway, GABA, and proline accumulation.