Construction Of A Interspecific High Density Genetic Map In (Gossypium Hirsutum L.×Gossypium Tomentosum L.) Population

Cotton is one of important natural fiber crop,and also is the source of vegetable protein and oil.With the increase of global demand for textiles,the improvement of fiber yield and quality has been the focus of cotton breeders.Upland cotton?G.hirsutum?is widely planted all over the world due to its wide adaptability and high yield,but the genetic deversity of G.hirsutum is poor.In contrast,G.tomentosum has the characteristics that G.hirsutum does not have,such as drought resistance,saline-alkali resistance and so on.The construction of a high-density genetic map using G.hirsutum and wild cotton G.tomentosum will be inportant for identifying favorable QTL allelles of G.tomentosum and marker-assisted selection.A genetic map from?G.hirsutum×G.tomentosum?BC₁ population was updated.In addition,the collinearity analysis was performed between genetic map and the physical maps of G.hirsutum,G.raimondii and G.arboreum.The main results are as follows:1.Polymorphism of primersA total of 21426 pairs of SSR primers were used to screen the polymorphisms between G.hirsutum and G.tomentosum.A total of 962 pairs of SSR pimers showed polymorphisms with a polymorphic ratio of 4.90%.2.Densification of genetic linkage map and segregation distortion analysisThe polymorphic primers were used to genotype?CCRI35×P0601211?BC₁population and 962 polymorphic loci were produced.A new high-density genetic map with 1915 loci was constructed,which covered 4069 cM of cotton genome,with an average inter-marker distance of 2.12 cM.1915 loci were used for segregation distortion analysis,the result revealed that 223showed segregation distortion,accounting for 11.64%of all loci.Among them,there were 94 loci on subgenome A and 129 loci on subgenome D.3.Collinearity analysis of genetic mapsComparing the two genetic linkage maps of G.hirsutum×G.tomentosum and G.hirsutum×G.barbadense,we found that most SSR markers present collinearity between the two genetic linkage maps.Meanwhile,part of the non linear relationship appeared on the individual Chromosome,which include one inversion fragments on Chr.01.4.Collinear analysis between genetic map and physical mapsCollinearity analysis was performed on G.hirsutum×G.tomentosum genetic linkage map and G.hirsutum physical map.The results showed that,the overall loci order on the genetic map was in agreement with the order of the corresponding sequences on the At and Dt sub-genomes of G.hirsutum.The genetic map of G.hirsutum×G.tomentosum covered a total of 2.12 Gb genome,which accounts for97.77%size of total Chromosome for G.hirsutum.In the At sub-genome?C01-C13?of G.hirsutum,1.34 GB was anchored to 2044.82 cM of G.hirsutum×G.tomentosum,whereas in the Dt sub-genome?C14-C26?,829 Mb was equivalent to 2024.18 cM.By comparing the linear relationship between the genetic map and the physical map of G.hirsutum,one inversions were identified on Chr.01.Most of the loci showed good collinearity between the genetic map and physical map.By comparing the linear relationship between the genetic map and the physical map of G.raimondii,it indicated that relative to G.raimondii physical map,two major reciprocal translocations,three simple translocations and four inverted positions were detected.By comparing the linear relationship between the genetic map and the physical map of G.arboreum,it indicated that relative to G.arboreum physical map,two major reciprocal translocations,three simple translocations and eleven inverted positions were detected.