Identification And Functional Analysis Of Candidate Genes For Grape Texture Formation Based On Fine QTL Mapping And Transcriptional

Fruit ripening and softening is a complicated biological process,and its physiological and molecular mechanisms is one of the hot issue.Grapevine is a typical non-climacteric fruit,the characteristics and mechanism of ripening and softening are different from those of climacteric fruit.Moreover,grape fruits of different cultivated varieties lead to different texture changes and softening properties during the ripening process.At present,the research on the ripening and softening mechanism of grape fruit are still very limited.In this study,grape cultivar ‘Red Globe'(V.vinifera L.)and ‘Muscat Hamburg'(V.vinifera L.)which showed significant difference in fruit texture were selected as the plant material,transcriptome analysis was conducted for grape fruit of the two cultivars at different developmental stages,the two cultivars were also used for the hybrid population construction and fruit texture QTL mapping.The main results are as follows:1.Through the research on the fruit texture and content of ‘Red Globe' and ‘Muscat Hamburg' at different development stages,it was found that the propectin was converted into water-soluble pectin(WSP),and the pericarp puncture hardness and arcocarp firmness were positively correlated with the content of propectin.The content of protopectin in ‘Red Globe' was always higher than that in the ‘Muscat Hamburg'.The results Indicated that different degrees of degradation of pectin were critical reasons for different textures of different grape cultivars.2.Through the analysis of grape fruit RNA-seq,124 Gb clean data were obtained.A total of 4559 significantly differentially expressed genes(DEGs)were identified between the two cultivars,including 302 transcription factors(TFs),and 21 DEGs were enriched in the galactose metabolism pathway,and 27 DEGs were enriched in pentose and glucuronic acid conversion.Through WGCNA analysis and q PCR verification,it was believed that Vv WAK and Vv GATL10 genes may be the key factors for maintaining firm texture of grape fruit,and Vv PG,Vv PL,Vv PE,Vv XTH,Vv EXP,Vv?-Gal and Vvb HLH genes may promote softening and the formation of different textures directly or indirectly.3.Through the genetic analysis of the fruit texture of the two grape hybrid groups ‘Red Globe'× ‘Muscat Hamburg' and ‘Red Globe'× ‘Venus Seedless',grape pericarp puncture hardness,arcocarp firmness and pericarp break distance of hybrid offspring showed continuous variation,which are typical quantitative traits controlled by multiple genes.According to the broad sense heritability analysis,grape fruit texture of these hybrid populations were major controlled by genetic factor.4.151 hybrid offspring and parents of the combination of ‘Red Globe'× ‘Muscat Hamburg' were used for whole genome re-sequenced and a high-density genetic linkage map was constructed,which containing a set of 2725 binmarkers(93,127 SNPs)spanning 1613.17 c M with an average inter-marker distance of 0.59 c M.5.QTL mapping analysis was used for 3 main indicators of grape fruit texture,and 15 QTL loci were located on LG1,LG6,LG9,LG10,LG16,LG17 and LG18,the explained phenotypic variation of them were ranged from 14.2% to 21%.Combined with the different expression data of RNA-seq,2 genes may be related to fruit texture were screened out.It was believed that these genes might participate in cell wall degradation and the formation of fruit texture.