Methyl jasmonate attenuates chilling injury of prune fruit by maintaining ROS homeostasis and regulating GABA metabolism and energy status

Cold storage is an important means to prolong the storage life of postharvest fruits. However, prunes are prone to chilling injury (CI) at low temperatures, which in turn reduces their marketability. In this study, methyl jasmonate (MeJA) effectively inhibited the occurrence of CI, and reduced internal browning index and electrolyte leakage of prune fruit under low temperature (1 ± 1 °C), with the most significant inhibitory effect observed at the concentration of 10 μM. Also, MeJA alleviated the overproduction of reactive oxygen species (ROS) by promoting the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase) and the expression level of their coding genes, thereby maintaining the integrity of the mitochondrial structure of prune fruit. Moreover, MeJA maintained higher content of γ-aminobutyric acid (GABA) through stimulating glutamate decarboxylase activity and retained higher energy levels by promoting the activity of succinate dehydrogenase, cytochrome C oxidase, H⁺-ATPase, Ca²⁺-ATPase, GABA transaminase, and succinic semialdehyde dehydrogenase and expression level of the corresponding gene of prune fruit. Our findings not only shed light on the inhibitory effect of MeJA on CI of prune fruit from the perspective of reducing ROS-induced oxidative damage to maintain mitochondrial structure, activating GABA shunt, and maintaining energy supply but also provide means of alleviating CI of prune fruit during postharvest storage.