Effect of methyl jasmonate on the quality and antioxidant capacity by modulating ascorbate-glutathione cycle in peach fruit

We investigated the effect of methyl jasmonate (MeJA) on the quality and antioxidant capacity in ‘Xiahui 8’ peach fruit during storage at 20°C and 90–95% relative humidity (RH) for 7 days. Exogenous MeJA maintained better fruit quality during storage, as indicated by reduced weight loss, respiration rate, ethylene production and total soluble solids, as well as maintained appearance and firmness. MeJA treatment significantly improved the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in peach fruit, therefore, reducing the accumulation of superoxide anion (O2−), hydrogen peroxide (H2O2) and malondialdehyde (MDA). Additionally, MeJA treatment enhanced the metabolic intensity of AsA-GSH cycle, as key enzyme activities involved in AsA-GSH cycle were markedly increased. These MeJA-promoting effect increased the content of reduced ascorbate (AsA) and glutathione (GSH), and the ratios of reduced to oxidized forms of AsA and GSH, contributing to higher redox status in peach fruit. Collectively, these results suggest that MeJA can maintain better fruit quality and improve antioxidant ability through enhancing AsA-GSH cycle, thus suitable for postharvest application.