Mechanism Of P-coumaric Acid Regulation On Postharvest Senescence Of Kiwifruit

Kiwifruit is a typical climacteric fruit with large planting area and great potential for industrial development in China.However,the postharvest kiwifruit is perishable softed after harvest,which greatly limits the storage and transportation of the fruit,leading to a rapid decline in its economic value.Therefore,it is essential to seek a safe and effective method to delay the senescence of kiwifruit and maintain its postharvest fruit quality and nutritional value.In this paper,"Xu xiang"kiwifruit was used as a research material.The objective of this study was to investigate the effect of p-CA treatment on senescence of kiwifruit during ambient storage,with special focus on ascorbate-glutathione（AsA-GSH）cycle,phenolic metabolism and energy level.The main results are as follows:1.The kiwifruit of p-CA treated and control were used as materials to study the change of firmness,soluble solid content（SSC）,weight loss rate,respiration rate,hydrogen peroxide（H₂O₂）and superoxide Anion(O₂^·-),malondialdehyde（MDA）contents and ion leakge during ambient storage.The results showed that p-CA treatment effectively inhibited the increase of firmness and weight loss rate,declayed the increse of respiration rate and SSC,decreased the ion leakage and the accumulation of H₂O₂,O₂^·-,and MDA.This indicated that p-CA treatment could effectively delay senescence and maintain the quality of kiwifruit.2.The kiwifruit of p-CA treated and control were used as materials to study the change of ascorbic acid（AsA）,dehydroascorbic acid（DHA）,reduced glutathione（GSH）and oxidized glutathione（GSSG）and their related enzyme activities during ambient storage.The results showed that p-CA treatment could effectively increase the activity of key enzymes in AsA-GSH cycle,such as ascorbate peroxidase（APX）and glutathione reductase（GR）,which contributes to promoting the accumulation of AsA,DHA,GSH and GSSG in p-CA treated fruit.These results showed that p-CA treatment could mediate the AsA-GSH cycle to effectively delay the kiwifruit senescence.3.The kiwifruit of p-CA treated and control were used as materials to study the changes of total pHenol,endogenous p-CA and salicylic acid（SA）content and related enzyme activities during ambient storage.The results showed that p-CA treatment significantly enhanced the activities of shikimate dehydrogenase（SKDH）,L-phenylalanine ammonia-lyase（PAL）,cinnamate-4-hydroxylase（C4H）and4-coumarate:coenzyme A ligase（4CL）,inhibited the activity of polyphenol oxidase（PPO）.Meanwhile,p-CA treatment effectively inhibited the decrease of total phenolic,endogenous p-CA and SA content in kiwifruit.These results indicated that p-CA treatment could effectively delay the kiwifruit senescence by regulating the metabolism of phenolic compounds.4.The kiwifruit of p-CA treated and control were used as materials to study the change of adenosine triphosphate（ATP）and energy charge（EC）and related enzyme activities during ambient storage.The results showed that p-CA treatment could effectively inhibit the decrease of ATP content,maintain a high EC state,and significantly enhance the activities of succinate dehydrogenase（SDH）,cytochrome C oxidase（CCO）,H⁺-ATPase and Ca²⁺-ATPase.These results indicated that p-CA treatment could effectively delay the kiwifruit senescence by regulating energy metabolism.In conclusion,this study showed that p-CA treatment could regulate the AsA-GSH cycle,phenolic compounds metabolism,and energy metabolism in kiwifruit during ambient storage of kiwifruit,and thus,delaying senescence and maintaining the postharvest quality of kiwifruit.