QTL Mapping And Candidate Genes Analysis Of Labrusca Flavor Grape Aromatic Compounds

Grape aroma is an important quality trait of grape and wine.It is a quantitative trait controlled by multiple genes.It is influenced by cultivation techniques,environment and other factors,and is more related to coltivar.In this study,an F1 grape hybrid of 177 individuals derived from a cross between ‘Zhuosexiang'(V.vinifera × V.labrusca.)and ‘Victoria'(Vitis vinifera L.)were used as mapping population,and RAD sequencing was used to construct grape molecular genetic map;An F1 grape hybrid of 140 individuals derived from a cross between ‘Red Globe'(Vitis vinifera L.)and‘Venus seedless'(V.vinifera × V.labrusca.)were used for QTL mapping of labrusca flavor grape aromatic compounds.Candidate genes related to labrusca flavor grape aromatic compounds were identified and their functions were verified by q RT-PCR.The main results are as follows:1.The genetic maps of female parent ‘Zhuosexiang'?male parent ‘Victoria' and the integrated genetic map were constructed respectively.the genetic map of female parent ‘Zhuosexiang' formed 19 linkage groups,including 2501 SNP markers,with a total map distance of 3121.07 c M and an average map distance of 1.25 c M;Male parent ‘Victoria' formed 19 linkage groups,including 4110 SNP markers,with a total map distance of 3179.28 c M and an average map distance of 0.77 c M.The total number of icons on the integrated map was 6249,which were distributed on 19 linkage groups.The total map coverage distance was 3118.13 c M and the average distance between markers was 0.5 c M.2.The determination of 6 aroma compounds of ‘Concord'(V.labrusca),‘Zhuosexiang'(V.vinifera × V.labrusca.)and ‘Venus Seedless'(V.vinifera × V.labrusca.),‘Victoria'(Vitis vinifera L.),‘Red Globe'(Vitis vinifera L.)and ‘Rose Fragrance'(Vitis vinifera L.)was completed,and labrusca flavor grape aromatic compounds were preliminarily determined by combining aroma threshold(OT): Methyl anthranilate?.alpha.-Terpineol?Eugenol?Benzoic acid,2-amino-,ethyl ester?Ethanone,1-(4-methylphenyl)-and Butanoic acid,ethyl ester.Through the analysis of the content of aroma compounds in two hybrid combinations,it is found that the content distribution of the same aroma compounds in the two hybrid combinations is different,and the content of different aroma compounds in the same combination is also different,the contents of 6 aroma compounds were widely separated in the two hybrid populations.3.Based on the established genetic maps,Map QTL5.0 was used to select QTL loci for labrusca flavor grape aromatic compounds.A total of 17 QTL were obtained in 2 groups.Among them,10 QTL were detected in the genetic map of ‘Zhuosexiang' ? ‘Victoria',which were distributed on LG3,LG8,LG9,LG11 and LG18 in 2017 and LG9,LG10,LG12,LG16 and LG18 in 2018.7 QTL were found on the genetic map of ‘Red Globe' ? ‘Venus Seedless',which were distributed in LG1,LG6,LG7,LG13,LG16 and LG19 linkage groups.4.According to QTL mapping results of aroma compounds,combined with grape reference genome information,the candidate gene GST of labrusca flavor grape aromatic compounds were selected.QRT-PCR was used to analyze the expression levels of the candidate gene in different mature stages of ‘Concord',‘Zhuosexiang' and ‘Victoria'.It was found that the expression levels of GST gene in ‘Concord' were significantly higher than that in ‘Victoria'.These results suggest that GST gene may be one of the important genes involved in the synthesis of labrusca flavor grape aromatic compounds Methyl anthranilate.