Melatonin treatment alleviates chilling injury and maintains quality attributes in cold-stored Chinese olives via modulating energy metabolism

Abstract Chinese olive, a fruit of significant economic and nutritional value in South China, is susceptible to chilling injury (CI) during cold storage, which is a primary factor leading to substantial postharvest fruit losses. The purpose of this exploration is to enunciate the impacts of 0.4 mM exogenous melatonin (MT) treatment on fruit quality attributes and CI occurrence in Chinese olive during 120 d of storage at 2 °C, with a particular focus on energy metabolism. The outcomes displayed that, compared to the control fruit, the MT-treated fruit showed a lower CI index, reduced weight loss, and decreased carotenoid content, while maintaining a higher percentage of commercially acceptable fruit, as well as higher L*, h°, and b* values and chlorophyll content. Furthermore, MT treatment sustained higher levels of total soluble solids, total phenolics, flavonoid, and tannin. Additionally, MT application alleviated the drops of energy charge, adenosine diphosphate, and adenosine triphosphate contents, and maintained higher activities of H+-ATPase, Ca2+-ATPase, and Mg2+-ATPase in the membranes of mitochondria, vacuoles, and plasma. Collectively, these data imply that 0.4 mM MT treatment elevated the activities of enzymes associated with energy metabolism, and sustained a higher energy status (energy charge and adenosine triphosphate), thereby mitigating quality deterioration and suppressing CI development in Chinese olive during cold storage.