Expression And Regulation Of Key Genes In Ethylene Signaling Pathway During Storage Of Grape

Grape(Vitis vinifera L.)is a perennial deciduous vine that belongs to Vitis of Vitaceae.It is one of the main economic fruit trees in China which can be used in raisins,wine making and eaten fresh.The storage period of grape is limited,rachis browning,fruit shedding and decay were common problem during storage,which seriously affects the appearance quality and storage life of grape.Ethylene plays an important role in grape storage and is the key factor to promote the ripening and senescence of rachis.ERF(ethylene-response factor)is ethylene responsive transcription genes downstream in ethylene signal transduction pathway,which is involved in the regulation of ethylene synthesis and response to exogenous genes in plants.However,the mechanism of their role in regulating the browning and senescence of rachis in non-climacteric grape rachis has not been reported.In this study,the effects of ethylene on senescence and browning of grape rachis were determined by analyzing the physiological changes of grape postharvest storage with different treatments,and the key ERF transcription factors that affects ethylene synthesis were identified by transcriptome analysis.Interaction between transcription factor VvERF77,VvERF90 and VvACS5,VvACS8,VvACO1,VvAC02 promoters were analyzed,and the mechanism of VvERF77 and VvERF90 involved in ethylene synthesis regulation was explored.The main research results are as follows:1.Effect of ethylene on postharvest storage of‘Shine Muscat’grape was studied by treatment of 1-MCP and ETH.The results indicated that 1-MCP treatment significantly reduced the fruit decay,fruit falling rate and rachis browning index were significantly reduced by 80%,90%and 95%,respectively.In addition,ethylene release rate decreased from 2 μL*Kg-1h-1 to 0.8 μL*Kg-1h-1.On the contrary,ETH treatment significantly increased the fruit decay rate by 33%,the peak of ethylene release rate appeared one week earlier and increased from 2μL*Kg-1h-1 to 4μL*Kg-1h-1.2.The results of transcriptome analysis of 1-MCP treatment and control showed that:expression of VvACS2,VvACS5,VvACO1,VvACO2 and VvACO3 were key functional genes regulating ethylene synthesis.the up-regulations of VvERF75,VvERF95,VvERF98 and VvERF111 were 4,48.5,2.8,and 14.9,respectively,consistent with the release of ethylene,showing an upward trend.Tt’s a key gene in the ethylene signal transduction pathway.3.The interaction between VvERF and VvACS,VvACO were detected by yeast one hybrid and Dual-LUC activity analysis.Strong interaction between VvERF90 and VvACS5,significant interaction between VvERF77 and VvACO1,VvERF90 and VvACO1,weak interaction between VvERF90 and VvACS8,VvACO2,VvERF77 and VvACS5,VvACO1,VvACO2 were detected.VvERF77 negatively regulates VvACS1 and VvACS8 promoter activities,and positively regulates VvACO1 promoter activity;VvERF90 negatively regulates VvACS1 promoter activity and positively regulates VvACO1 promoter activity.4.In Arabidopsis thaliana,over expression of VvERF77 increased the ethylene release rate of Arabidopsis 2.5-fold,and the expression levels of functional genes AtACS1,AtACS6,AtACO1,AtACO2,and AtACO3 were decreased,and the fold reductions were 7.8,6.8,6.1,3.8,and 2.9,respectively.The over expression of VvERF90 in Arabidopsis thaliana was increased by 2-fold,and the expression levels of AtACS1,AtACS6,AtACO1,AtACO2 and AtACO3 were increased,and the folds were 2.6,2.3,3.1,177,6.5,respectively.In conclusion,1-MCP treatment could significantly inhibit rachis browning and senescence,VvERF75,VvERF95,VvERF98 and VvERF111 were the key genes in ethylene signaling pathway,VvERF77 negatively regulated the activity of VvACS8 promoter and VvERF90 positively regulated the activity of VvACO1 promoter,VvERF77and VvERF90 have a regulatory effect on ethylene release.