| Peach,as a sweet,delicious and juicy seasonal fruit,is widely favored by consumers.Peach is a kind of climacteric respiration fruit,it is prone to senescence and rot if the fresh-keeping treatment and storage are unreasonable after harvest;the skin of peach fruit is thin,the juice is rich,and it is prone to microbial infection after mechanical injury,which seriously affects the commodity and sales,so how to delay the senescence process of peach fruit,prolong the shelf life and maintain its high quality have become the key research directions of post-harvest peach preservation.1-Methylcyclopropene（1-MCP）,as a proven high-efficiency ethylene inhibitor,has been widely used in the field of postharvest preservation of fruits and vegetables.In this thesis,"Xiahui No.8"peach fruit was used as the experimental research material to study the effects of ethylene synthesis and related genes of two maturity peach fruits under the storage conditions of 20℃and 4℃with 1-MCP treatment.The main research results are as follows:1.Fumigate the peach fruits with 10mL/L 1-MCP at 20°C for 12 hours and store them at 20±1°C for 6 days.Take samples every 2 days to determine the hardness,TSS,respiration rate,and ethylene release of the peach fruits.Quantity,EL,MDA,ethylene synthesis-related enzymes and ethylene synthesis-related gene expression.The results showed that during storage at 20℃,1-MCP treatment could maintain peach fruit firmness and inhibit the rapid increase of EL and MDA.At the end of storage,the MDA content of low maturity treatment and control group were 2.35 and2.54μmol·g-1FW,respectively.At the same time,1-MCP reduced the respiration rate and ethylene release of two-ripe peach fruits,and delayed the emergence of ethylene peak in high-ripe peach fruits.On the 4th day of storage,the respiration intensity of fruits in the low and high two-ripeness treatment groups were 12.16 mg·kg-1·h-1and12.82 mg·kg-1·h-1lower than the control,and the peak ethylene release was 18.43%and 15.88%lower than the control.In addition,1-MCP treatment also inhibited the activities of ACS and ACO.The maximum activity of the two in the high-maturity treatment group was 0.91 times and 0.95 times that of the control group.In terms of gene expression,1-MCP treatment down-regulated the expression of Ppa ACS5 in high-maturity fruits and Ppa ACS1/4 in low-maturity fruits.Also 1-MCP treatment up-regulated the expression of Ppa ACO1 at the end of storage for high-maturity fruits and down-regulated the expression of Ppa ACO2 at the end of storage for two-maturity fruits.2.Fumigate the post-harvest peach fruits with 10mL/L 1-MCP at 20°C for 12hours and store them at 4±1°C for 20 days（low maturity group）and 10 days（high maturity group）,and a 2-day shelf life experiment was carried out to detect peach fruit firmness,TSS,respiration rate,ethylene release,EL,MDA,ethylene synthesis-related enzymes,and ethylene synthesis-related gene expression during low-temperature storage and shelf life.The results showed that during low-temperature storage,1-MCP treatment had a better maintenance effect on low-maturity fruit firmness,TSS,and RASA.On the 20th day of storage,the fruit firmness of the treatment group and the control group were 23.46N and 9.71N.1-MCP can better inhibit the rapid increase of MDA in the early storage period;while the 1-MCP treatment of high-maturity fruits is more obvious in reducing the respiration rate,EL,PG activity and ethylene release,and the fruits are treated in the middle of storage（day 4）.The respiration rate and ethylene release were 23.96 mg·kg-1·h-1and 27.90μL·kg-1·h-1,which were significantly lower than those of the control group of 30.30 mg·kg-1·h-1and 72.65μL·kg-1·h-1.In addition,1-MCP induced down-regulation of Ppa ACS1 and Ppa ACO1gene expression in two-maturity fruits,increased the Ppa ACS5 transcription level of high-maturity fruits in the early storage period,and reduced ethylene release and ACS and ACO activities during low-temperature storage;at the same time,1-MCP treatment reduced the transcription levels of Ppa ACS1 and Ppa ACO1 in the early shelf life of the two-maturity fruits,slightly increased the expression of Ppa ACO2 in the mid-storage period of the low-maturity fruits,and delayed the maturity and senescence of peach fruits. |
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