Fine Mapping The Freezing Tolerance Gene And Development Of Linkage Markers On Chromosome 2 Of Wild Potato S.commersonii

As a grain and vegetable crop,potato plays a very important role in ensuring food security.The development of winter fallow fields in southern China has become the key to realize the main grain of potato in China,but the existing potato cultivars do not have the ability of direct cold resistance or domestication and cold resistance,and low temperature frost has become the main limiting factor for the development of winter fallow fields in southern China.At present,there are few studies on cold resistance gene mapping and molecular marker development of potato at home and abroad.In this study,the F1 generation of potato diploid wild species S.commersonii and bridge species S.verrucosum were used,and then backcrossed with S.commersonii to obtain character segregation populations.on the basis of BSA+DNA-seq sequencing,the following results were obtained:1.Phenotypic identification of isolated populations: 286 population materials were identified by field natural frost method.combined with the phenotypic data of the previous3 years,112 population materials(53 cold resistant materials and 59 sensitive materials)were determined.2.Marker development: 770 pairs of SSR primers were designed on 23～48 Mb of chromosome 2,and 271 pairs of In Del primers were designed by 36～40 Mb.62 pairs of markers linked to direct cold resistance traits were screened by t-test,34 pairs of SSR markers and 28 pairs of In Del markers were screened.3.Correlation between markers and phenotype: 62 pairs of markers were analyzed by Kruskal-Wallis using Map QTL software,and 32 stable linkage markers were found to be significantly different from those of 4-year-old plants at α = 0.05 level.4.Direct cold resistance QTLs mapping: based on the phenotypic data,32 stable linkage markers and direct cold resistance genetic map analysis of chromosome 2,two direct cold resistance QTLs,were located on chromosome 2.It is inferred that there may be two major genes controlling direct cold resistance on chromosome 2,which are located in the 160 kb interval near 36 Mb and in the 2.4 Mb interval of 39～41 Mb.5.Candidate genes: there are 12 reference genes in the 160 kb region near 36 Mb on chromosome 2.Four genes that may be related to cold resistance were selected for quantitative PCR,and there was no significant difference in the expression level of genes in resistant and susceptible plants.There are 256 reference genes in the 2.4 Mb region of39～41 Mb,and the range of segment 2 candidate genes is large,which needs to be further determined.