Effects Of Nitric Oxide Fumigation On Redox Homeostasis Of Postharst Cantaloupe

Cantaloupe（Cucumis melo L.）is one of the main cultivated cash crops in Xinjiang.Its unique flavor,crisp and refreshing taste is loved by consumers at home and abroad.However,the harvest period of cantaloupe mostly concentrated in hot and hot seasons,and the fruit is prone to mature,aging,deterioration of quality and decay due to vigorous physiological metabolism,which not only limits the storage and shelf life of cantaloupe,but also seriously affects the foreign trade of xinjiang characteristic melon and fruit industry.The quality decline is closely related to the imbalance of ROS homeostasis.As a redox active molecule,NO has been proved to significantly improve postharvest fruit storage.In order to explore the antioxidant effect of NO on the post-harvest storage period of cantaloupe,“Xizhoumi NO.17”was used as test material,and 60μL/L exogenous NO was accurately fumigated to analyze and determine the physiological indicators of cantaloupe S-nitrogenation related indicators As A-GSH cycle key enzymes and substrate NOX/SOD system related indicators four pairs of redox coupling The effects of NO on storage quality of cantaloupe were investigated from the perspectives of ROS generation,ROS clearance and ROS homeostasis.The main results are as follows:（1）The effect of NO fumigation on postharst quality of cantaloupe was analyzed.The hardness and TSS TA content of the treatment group were significantly higher than that of the control group,and the weight loss rate and decay rate and relative conductivity of the treatment group were significantly lower than that of the control group,indicating that the quality index of the cantaloupe treated with NO was better than that of the control group,and NO maintained the storage quality of the cantaloupe after harves.（2）The effect of NO fumigation on the ASA-GSH cycle of cantaloupe was studied.He content of endogenous NO,SNO in treatment group was significantly higher than that in control group,and the activity of GSNOR was significantly lower than that in control group,indicating that NO increased the S-nitrosylation level of cantaloupe.The ratio of As A/DHA,GSH/GSSG in treatment group was significantly higher than that in control group,the activities of APX,MDHAR,DHAR and GR were significantly higher than that in control group,while the content of H₂O₂,MDA was lower than that in control group.It indicated that NO increased the As A-GSH cycle of cantaloupe.In conclusion,NO can activate the activity of key enzymes in the As A-GSH cycle,improve the efficiency of scavenging H₂O₂and alleviate lipid peroxidation by increasing the S-nitrogenation level of cantaloupe fruits.（3）The effects of NO fumigation on the activities of antioxidant enzymes in cantaloupe after harvest were studied.In the early stage of storage,O₂^·-yield,H₂O₂content and NOX activity in treatment group were significantly higher than those in control group,while in the late stage of storage,O₂^·-yield,H₂O₂content,NOX activity and relative gene expression in treatment group were significantly lower than those in control group.In the middle and late storage period,SOD activity and relative gene expression POD and CAT activity in treatment group were significantly higher than those in control group.In conclusion,NO can induce NOX to produce transient O₂^·-and H₂O₂ in the early stage of storage,while O₂^·-and H₂O₂as upstream signal molecules activate antioxidant enzyme activity,improve antioxidant effect of cantaloupe,and inhibit the accumulation of O₂^·-and H₂O₂in the later stage of storage.（4）The effect of NO fumigation on REDOX stability of hami melon after harvest was confirmed.The As A,GSH,NADP⁺and NAD⁺contents and GR,APX activity in treatment group were significantly higher than those in control group,while the GSSG,DHA,NADPH and NADH contents of were significantly lower than those in control group.The ratios of As A/DHA,GSH/GSSG NADP⁺/NADPH and NAD⁺/NADH in treatment group were significantly higher than those in control group,and the contents of H₂O₂and MDA were significantly lower than those in control group.In conclusion,NO decreased lipid peroxidation of cantaloupe by improving postharpostharble redox homeostasis and antioxidant enzyme activity...