Effects of CaCl₂ Treatment Alleviates Chilling Injury of Loquat Fruit (Eribotrya japonica) by Modulating ROS Homeostasis

The effects of calcium chloride (CaCl₂) treatment on chilling injury (CI), reactive oxygen species (ROS) metabolism, and ascorbate-glutathione (AsA-GSH) cycle in loquat fruit at 1 °C storage for 35 d were investigated. The results indicated that CaCl₂ treatment remarkably suppressed the increase in browning index and firmness as well as the decrease in extractable juice rate. CaCl₂ treatment also decreased the production of superoxide radical (${\mathrm{O}}_2^{•-}$), hydrogen peroxide (H₂O₂) content, but increased the 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical (${\mathrm{OH}}^{•}$) scavenging ability, the activities of superoxide dismutase (SOD), catalase (CAT), and their gene expressions. Moreover, compared to the control loquat fruit, CaCl₂-treated fruit maintained higher contents of AsA, GSH, higher levels of activities of ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductase (DHAR), and monodehydroascorbate reductase (MDHAR) and expressions of EjAPX, EjGR, EjMDHAR, and EjDHAR, but exhibited lower glutathione disulfide (GSSG) content. These results suggested that CaCl₂ treatment alleviated CI in loquat fruit through enhancing antioxidant enzymes activities and AsA-GSH cycle system to quench ROS.