Potential role of glutathione peroxidase gene family in peach fruit ripening under combined postharvest treatment with heat and 1-MCP

Abstract

Glutathione peroxidases (GPXs) are central members in the antioxidant system and play an important role in response to oxidant stress. To understand the role of the major molecular players in peach fruit ripening, the GPX gene family was investigated in this study. Eight Glutathione peroxidase genes (PpaGPX1-8) in peach fruit were isolated from genome databases and characterized using bioinformatics analysis. The expression patterns of GPX genes were analyzed in peach fruit harvested at three different maturity classes and treated with heat+1-MCP (HM). The unripe fruit were found to have both higher enzymatic and transcriptional capacity compared with the more mature fruit, and the ripe fruit were more sensitive to HM treatment. PpaGPX6 and PpaGPX8 were the most abundantly expressed genes at all three maturity classes of peach fruit. All the PpaGPX genes (except PpaGPX1) showed up-regulated expression in the late stage of ripening (after the peak of respiratory climacteric). Moreover, HM treatment dramatically delayed the postharvest ripening process of peach fruit, by postponing the climacteric peak in respiration, enhancing firmness, increasing GPX activity and up-regulating PpaGPXs expression. These data indicated that PpaGPXs had a more important regulating function in the late stage of peach fruit ripening.