Mapping Of Cold Resistance QTL And Screening Of Candidate Genes In Grape Based On High Density Genetic Map

In this study,the grape variety ‘Cabernet Sauvignon' × ‘Zuoyouhong' and their 200 hybrid offsprings were used as test materials,SSR molecular markers were used to identify true or false hybrids,181 strains of true hybrids were obtained.Using this population and its hybrid progeny by differential thermal analysis(DTA)system for chilling phenotypic identification of grape branches.Then these branches were subjected to simplified genomic RAD sequencing,a large number of SNP markers were obtained to construct a high-density SNP molecular genetic map.The main QTL intervals were screened and analyzed,and the cold resistance related QTLs of grapes were obtained,and the contribution rate of each related QTL to cold resistance was calculated.The test obtained the following main results:1.SSR molecular markers were used to identify the hybrids of ‘Cabernet Sauvignon' × ‘Zuoyouhong' hybrids.Two pairs of clear and ab×cd bands primers were screened and used.The two pairs of primers were used to identify the hybrids of 200 offsprings,and 181 true hybrids were obtained.The true hybrid rate was 90.5 %.2.Low temperature exothermic(LTE)was used to analyze the cold resistance of the hybrid offsprings of ‘Cabernet Sauvignon' × ‘Zuoyouhong',the branch temperature-injury(LT-I)regression line was obtained,and the relationship between the damage degree of the branches and the temperature was analyzed.Combined with the membership analysis method,the cold resistance of the grapes was comprehensively evaluated.The results showed that the kurtosis and absolute skewness of the three-year cold resistance data were less than 1 normal distribution,and the cold resistance of the offspring population was continuous,which accorded with the genetic characteristics of quantitative traits.The cold resistance of grape branches is divided into high resistance,resistance,medium resistance,low resistance and non-resistance,and the percentage of branches with different degrees of cold resistance in each group is obtained.3.Simplified genome sequencing analysis of ‘Cabernet Sauvignon' × ‘Zuoyouhong' and its 181 hybrid progenies was carried out by simplified genomic RAD sequencing method.The molecular genetic map of high-density SNP of grape was constructed.The female ‘Cabernet Sauvignon' contained 16075 markers,longs 1548.11 c M,and the average distance between the loci is 11642 c M;1790.21 are the total number of the male ‘Zuoyouhong' covered 25917 c M and the average distance between the loci is 0.16 c M,and 25917 markers are obtained in the integrated map,the total map distance was 1780.48 c M,and the average distance between the markers is 0.07 c M;4.By combining the identification results cold-resistant phenotypes with the constructed high-density molecular genetic map,using R/qtl software to locate cold-resistance-related QTLs which LOD?3.0,then 8 QTLs were distributed in LG1,LG3,LG4,LG14,LG15 and LG16 linkage groups with contribution rates ranging from 2.2 % to 10.1 %.5.All genes in the QTLs locus were found and 9 candidate genes that may be associated with cold resistance of the grape were screened based on the gene annotation.