Effects of ozone treatment on gene profiling involved in ASA-GSH cycle in postharvest cantaloupe

Ozone has been proven to be an environmental-friendly method in postharvest storage of cantaloupe with the elimination of reactive oxygen species (ROS), but the mechanism is not clear. In this study, the activity of key enzymes, transcriptomics, and the content of Ascorbic acid(ASA), Reduced glutathione (GSH), H2O2, and Malondialdehyde (MDA) were measured as typical indicators to investigate the effect of ozone treatment on the ascorbic acid-glutathione (ASA-GSH) cycle metabolism of the antioxidant defense system of cantaloupe after harvest. The results showed that the formation of H2O2 and MDA and the accumulation of ASA and GSH in cantaloupe were reduced and increased in the ozone treatment group (OT), respectively. Ozone promoted the activity of the key enzymes of the ASA-GSH cycle in cantaloupe during storage, particularly Ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and glutathione reductase (GR), which was confirmed with the variation of H2O2, MDA, ASA, and GSH. The 14 genes associated with the ASA-GSH cycle were identified using transcriptomics, and the FPKM in GR-2, MDHAR-3, and MDHAR-4 were greater in OT than in the control group (CK) on the 10th day, all AO genes were stimulated in OT compared to CK on the 30th day, indicating that AO and MDHAR genes of ASA-GSH cycle may be the target genes induced by ozone treatment in the postharvest cantaloupe. Correlation analysis indicated that the ability of ozone-treated cantaloupe to regulate ROS was a synergistic effect of enzyme activity and gene expression related to the ASA-GSH cycle. This study was to lay a foundation for future studies on the possible effects of ozone on the ASA-GSH cycle of many fruit and vegetable.