Nitric oxide fumigation maintains cantaloupe fruit quality by regulating the production of reactive oxygen species

Cantaloupe (Cucumis melo L.) is a major crop cultivated in Northwest China. However, with the extension of storage periods, cantaloupes are increasingly prone to post-ripening senescence, quality deterioration, rot, and other phenomena, which in turn seriously limit shelf life. During postharvest storage, the quality of cantaloupes is affected by a large increase in ROS in the fruit. Herein, the effects of exogenous NO fumigation treatment on the quality of Xizhoumi NO.17 cantaloupe were investigated, with a focus on ROS generation and removal. NO fumigation treatment effectively reduced the rate of cantaloupe decay, inhibited fruit water loss and better maintained fruit firmness and relative conductivity. NO treatment induced O2·– and H2O2 production during early storage (within 24 h), whereas their accumulation decreased during later storage. NOX activity and expression of related genes in the treatment group were higher than those in the control group during the early storage but lower during later storage. NO fumigation also induced the antioxidant capacity of enzymatic and non-enzymatic systems in cantaloupe and helped to inhibit the accumulation of ROS. Taken together, NO fumigation triggers H2O2 production via the NOX/SOD system, activating the antioxidant response of cantaloupe to overcome excessive ROS production in the late stage of storage, thus maintaining fruit quality.