The Mechanism Analysis Of Banana Transcription Factor MabZIPs Regulating The Expression Of Genes Involved In Aroma Synthesis

Bananas are popular because of its good flavor quality and commodity value.Banana is a typical climacteric fruit,and a large number of characteristic aroma substances were produced during the ripening process,including aldehydes and esters.however,banana is cold sensitive and chilling injury symptoms appear when temperature is lower than 13?,leading to fruit ripening abnormally and reducing the flavor quality greatly.It is reported that transcription factor Mab ZIP is responsive to cold stress and ripening.In this experiment,‘Brazil' Banana was used as experimental material to study the formation of volatiles during fruit ripening and effect of low temperature,meanwhile,the expression and characterization of Mab ZIP and volatile-formed genes were also studied.O ur study will give theoretical basis for the aroma formation and regulation in banana fruit.The main results were as follows:1.Using headspace solid-phase extraction(HS-SPME),gas chromatography-mass spectrometry(GC-MS)and external standard qualitative and quantitative,the aromas' variety and content of the two treatments(Ethylene ripening,Ethylene ripening after 3 days' chilling injury with 7 degrees C)were determined.Results show that banana fruit has different characteristic aroma at different maturity stages,aldehydes exhibited at green hard stage,while,much acetate esters,butyrate esters and some branched esters were formed in the ripening stage,in addition,a large number of esters,with less raw materials appeared in the over ripening stage.2.Chilling injury delays the ripening of banana,and seriously affect the appearance and sensory quality of banana.Low temperature has little effect on the types of banana aroma,but significantly inhibited the production of esters during fruit ripening.3.Two b ZIP transcription factors and the aroma synthesis genes were screened,and q RT-PCR was used to analyze the gene expression profiles during fruit ripening,The results showed that the expression of banana transcription factor Mab ZIP30/37 and the aroma synthesis pathway related genes(Ma ACY,Ma AGT,Ma GT,Ma BCAT,Ma OMT and Ma MT1)were all up-regulated during banana ripening,however,low temperature reduced the expression of above-mentioned genes.4.According to the banana genome sequence,we clone the full-length sequence of banana transcription factor Mab ZIP30/37 and the promoter sequence of Ma ACY,Ma AGT,Ma GT,Ma BCAT,Ma OMT and Ma MT1.Subcellular localization experiments showed that Mab ZIP30/37 was nuclear-localized and Mab ZIP30/37 has transcriptional activity and both are transcriptional activators.In addition,Dual luciferase reporter assay system(Dual-LUC)showed that banana transcription factor Mab ZIP30/37 can bind and activate the activity of promoter Ma ACY,Ma AGT,Ma GT,Ma BCAT,Ma OMT and Ma MT1 to regulate the expression of aroma genes and the production of banana aroma compounds.