Effect Of No And 1-MCP On Sucrose Metabolism And Gene Expression Of Peach Fruit During Storage

Peach(Prunus persica.L cv.Xiahui 6)are favored by most consumers owing to its rich nutrition and delicious taste.However,peach fruit belong totypical climacteric fruit,are very easy to maturity and senescence after harvest at room temperature.Besides,peach fruit is very vulnerable to damage because of its thin skin and abundant juice,so peach fruit are easy to mature and are not easy to storage,which shorten shelf life of peach fruits.Therefore,it is important to postpone the maturity and senescence of peach fruit and keep higher quality,which has become a important subject for the storage and preser'vation of peach-Nitric oxide and 1-methylpropylene have been verified as a kind of non-toxic,safe and efficient preservative,which can effectively keep the storage quality of fruits and vegetables and postpone the maturity and senescence of fruits and vegetables.Besides,the varieties and contents of sugar have an important influence on the formation of fruit internal quality,which determine the flavor and sweetness of the fruits.So,in order to explore the molecular mechanism of sugar metabolism,the effect of nitric oxide and 1-MCP treatments on postharvest 'Xiahui 6' peach fruit were investigated in this paper.The main research results are as follows:1.Peach fruits were treated by 10 ?L L-1 nitric oxide for 3 h under 25? condition and then stored at 4±1? for 24 d.In order to research the effect of nitric oxide treatment on the influence and regulation mechanism of the sugar metabolism ofpostharvest peach fruits in molecular level,respiration rate,ethylene,firmness,soluble sugar,sucrose metabolism related enzymes and sucrose metabolism related gene expression were determined every six days.The research results indicated that:nitric oxide treatment decreased the respiration rate of peach fruits,reduced obviously the biosynthesis of ethylene production and postpone significantly the advent of ethylene burst;nitric oxide treatment enhanced the SPS activity,inhibited significantly the activity of sucrose hydrolase AI and SS-C during the end of storage,slowed the conversion of sucrose,maintained a higher sucrose content.Real-time fluorescent quantitative PCR analysis showed that nitric oxide treatment inhibited significantly the transcription level of PpaSS1,PpaSS3,PpaAIl,PpaNI1 and PpaNI2 in the end of storage,up-regulated the expression of PpaSPS2 at the end of storage,so maintained a higher sucrose content at the end of storage.2.Peach fruits were treated by 10 ?L L-1 1-MCP for 12 h under 20? condition and then stored at 20±1? for 7 d.In order to research the effect of 1-MCP treatment on the influence and regulation mechanism of the sugar metabolism of postharvest peach fruits in molecular level,respiration rate,firmness,soluble sugar and sucrose metabolism related gene expression were determined during storage.The research results showed that:1-MCP treatment decreased significantly the respiration rate of peach fruits and delayed the onset of climacteric,postponed the decrease of firmness.1-MCP treatment inhibited the increase of glucose and fructose contents and the decrease of sucrose content,slowed the conversion of sugar.RNA-seq detected a total of 14 genes related sucrose metabolism during storage.Compared with PpaAI,there were a higher transcription level of PpaSPS,PpaSS and PpaNI.1-MCP treatment down-regulated the expression level of PpaSPS1/2/3 at the first and middle storage and up-regulated significantly their expression at the end of storage.The expression of PpaSPS4 was up-regulated significantly and the transcriptions of PpaNI3 and PpaNI4 were down-regulated by 1-MCP treatment in the whole storage,so the soluble sugar content of peach were regulated by 1-MCP.3.There were a different regulation mechanism for sugar metabolism of posthavest peach fruit both NO and 1-MCP.NO treatment up-regulated the transcript of PpaSPSl/2 and down-regulated the expressions of PpaAI1 and PpaNI1/2,whereby regulating sugar metabolism of peach fruit during cold storage.However,1-MCP could regulate sugar metabolism of peach fruit,mainly through enhancing the transcription level of PpaSPSl/2/3 and PpaSPS4 expression level in the whole storage and down-regulating the expression level of PpaNI4/5 and PpaSS3.