Alleviation of chilling injury in cold-stored Chinese olive (Canarium album Lour.) fruit by γ-aminobutyric acid treatment in relation to ROS metabolism

Chinese olives are susceptible to chilling injury (CI) during refrigeration. Exploring economical and convenient approaches to suppress CI development is important for preserving fruit quality and prolonging postharvest shelf-life of Chinese olives. In this study, the effects of 1.0 mM gamma-aminobutyric acid (GABA) treatment on CI development and ROS metabolism in cold-stored Chinese olives at 2 degrees C for 100 d were evaluated. The results demonstrated that, compared to control Chinese olives, GABA treatment observably alleviated CI development, remarkably suppressed the increased CI index, O-2(-.) production rate, and MDA amount, but retained higher SOD, CAT and APX activities, higher values of GSH and AsA, higher abilities of scavenging DPPH radical, and higher reducing power. On the last day of storage (day 100), CI index, O-2(-.) production rate, and MDA content in control Chinese olives were 2.06-, 1.28, 1.48-fold higher compared with those of GABA-treated fruits. In contract, SOD, CAT and APX activities in GABA-treated fruits were 1.54-, 3.24, 1.57-fold higher than in that of control Chinese olives. The GSH and AsA contents, DPPH scavenging ability and reducing power were 64.7%, 128.4%, 51.8% and 35.0% higher in GABA-treated olives, as compared to control fruits. Together, these findings indicate that 1.0 mM GABA shows a potential application in improving antioxidant capacity and alleviating CI development of Chinese olives during cold storage.