Effect Of Exogenous Putrescine Treatments On Chilling Injury And Polyamine Metabolism Of Postharvest Melon

Muskmelon(Cucumis melo L.)belongs to the Cucurbitaceae family and the genus Muskmelon.Melon was classified as thick-skinned melons and thin-skinned melons of Xinjiang.Yellow-skinned melons pertain to thick-skinned melons.its crisp taste,special flavor,and high nutrient content,deeply loved by consumers at home and abroad.For melons that have the characteristics of concentrated production season and high water content,melons easily deteriorate and rot during storage and transportation after harvest.Low-temperature refrigeration or cold-chain logistics is the main way to extend the life of melons in production,but yellow-skin melons are more sensitive to low temperatures.5?and below is very easy to cause chilling injury,which limits the application and promotion of low-temperature storage technology in the post-harvest production of muskmelons in our region.Our team's previous studies have confirmed that the occurrence of postharvest cold damage in melon fruits is positively correlated with the endogenous putrescine(Put)content in the peel.Whether the application of exogenous Put treatment can induce the postharvest cold resistance of the fruit needs further investigation.Therefore,this paper uses‘Xinmi No.3'yellow-skin melon as the test material to study exogenous putrescine(Put)treatment on the chilling injury,reactive oxygen species,and polyamine metabolism under 5±0.5?induction conditions,to provide new ideas and theoretical basis for the directional control of postharvest cold injury of yellow-skin melon.The main findings are as follows:1.‘Xinmi No.3'yellow-skin melon fruit treated with exogenous Put(0,1.0,2.0,and 4.0 mmol/L).The CI index,weight loss rate,and quality indicators of fruit were evaluated.The results showed that the exogenous Put treatment can delay the occurrence of chilling injury on‘Xinmi No.3'yellow-skin melon after harvest by 7 days,alleviate the symptoms of chilling injury,and maintain high levels of fruit firmness,soluble solids,the skin brightness and brightness The yellowness is maintained well,and the effect of2.0mmol/L Put is the most obvious.After 49 days of storage,the chilling injury index is only 0.3,and the weight loss rate is only 4.59%.2.Treatment with 2.0 mmol/L exogenous Put on postharvest chilling injury and active oxygen metabolism of yellow-skin melon were studied.Compared with the control group(CK),2.0 mmol/L exogenous Put treatment can significantly increase the activity of superoxide dismutase(SOD)and ascorbate peroxidase(APX)in the peel of‘Xinmi No.3'yellow-skin melon during cold storage.Inhibit the activity of polyphenol oxidase(PPO)and lipoxygenase(LOX),reduce the accumulation of hydrogen peroxide(H₂O₂),superoxide anion(O₂.-),and malondialdehyde(MDA),thereby increasing the resistance of the fruit Coldness.3.Treatment with 2.0 mmol/L exogenous Put on postharvest chilling injury and endogenous polyamine metabolism of yellow-skin melon were studied.The results showed that during cold storage,Treatment with2.0 mmol/L exogenous Put regulated arginine decarboxylase(ADC),ornithine decarboxylase(ODC),N-carbamoyl putrescine hydrolase(CPA),S-adenosylmethionine decarboxylase(SAMDC),diamine oxidase(DAO),polyamine oxidase(PAO)and the content of spermidine(Spd)to improves the cold resistance of yellow-skin melon after harvest.