Fine Mapping Of Cold Tolerance Gene In Cucumber CG0080

Cucumber(Cucumis sativus L.)is a day-neutral and warm plant of Cucurbitaceae genusand widely planted in the world.However,in the production of cucumbers,low temperature in winter will seriously affect the yield and quality of cucumber,and greenhouse warming measures will increase the farmer’s planting cost.Cold tolerance trait is one of the important agronomic traits in cucumber breeding,and finding the gene controling the cold tolerance of cucumber,exploringing the genetic law of cold tolerance,and revealing the mechanism of cold tolerance will accelerate the selection of cold tolerance varieties.In this study,F2 segregation population and BC3S2 generation plants,constructed by near isogenic lines IL019-8 and germplasm 404,and germplasm CG0080 and 404 respectively,were used.The genetic analysis of cold tolerance traits of IL019-8,first mapping and fine mapping of cold tolerance gene,and prediction and analysis of the candidate gene were performed.The main results were as follows:(1)The genetic analysis of cold tolerance trait.The nearly isogenic lines IL019-8 and 404 germplasm were used as materials to build F1 and F2 genetic population.The results showed that the phenotypic expression of the hybrid F1 generation was the intermediate type of two parents.The F2 population included 179 cold-tolerance plants and 78 cold-sensitive plants,which was fit the Mendelian 3:1 ratio.The result showed that cold-tolerance phenotype is controlled by a single gene,with incompletly dominant character.(2)First mapping of cold tolerance gene.The BC3S2 generation plants of core germplasm CG0080 and 404 were analyzed by chip-analysis,showing that IL019-8 lines had closest relationship to the background of 404,and contained CG0080 specific fragments.At the same time,the CT gene was narrowed down to the interval of 24 Mb～28 Mb on Chromosome.1.Then alinkage analysis was done and CT gene was narrowed down to 3 Mb interval between 25.20 Mb and 28.14 Mb with InDel markers and F2 segregating population constructed by nearly isogenic lines IL019-8 and 404.(3)Fine mapping of cold tolerance gene.According to resequencing information in CT gene mapping interval of two parents,new InDel,SNP and dCAPS markers were developed,and a linkage analysis was performed with F2 population by constructed with lines IL019-8 and germplasm 404.CT gene was mapped in a physical range of 300 kb between the marker InDel-28 and SNP-37,namely between 25.85 Mb and 26.15 Mb on Chr.1.(4)The candidate gene prediction and analysis.According to cucumber genome information and genome annotation information,a total of 22 cucumber genes in the fine mapping 300 kb region were found,which were phosphatidylethanolamine family proteins,acetolactate synthase gene,NAC domain protein et al.Further work will need to do for the cloning of cold tolerance-related gene.