Regulation of ascorbate-glutathione cycle in peaches via nitric oxide treatment during cold storage

The accumulation of reactive oxygen species (ROS) under stress conditions has great potential to damage fruit. The ascorbate-glutathione cycle is an essential metabolic pathway that eliminates hydrogen peroxide (H2O2) and maintains redox equilibrium. Nitric oxide (NO) could delay senescence of fruit through the ascorbate-glutathione cycle. Peaches were treated with NO (10 mu L L-1) or 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO) solution (100 mu mol L-1) and stored at 0 degrees C to characterize the effects of exogenous NO on antioxidant production via ascorbate-glutathione (AsA-GSH) metabolism. The results show that exogenous NO slowed the decrease in fresh firmness and the increase in contents of soluble solids and malondialdehyde (MDA) of peach fruits during storage. Moreover, at the same time, it increased the activities of dehydroascorbate reductase (DHAR), ascorbate peroxidase (APX), glutathione-S-transferase (GT) and glutathione reductase (GR). NO treatment also maintained the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH center dot) and increased the ratios of GSH:GSSG and AsA:DHA. The results revealed that exogenous NO could enhance the reducing ability of the AsA-GSH cycle and maintain a high antioxidant capacity of peaches during storage.