Update Of Genetic Map From G. Hirsutum × G. Mustelinum And Analysis Of Chromosome Structural Variation

Cotton is the most vital natural fiber crop in the world,and it is also an important oil and food crop.The construction of genetic map of cotton is a basal task for cotton molecular breeding.It can mark important agronomic trait genes and lay a foundation for QTL mapping,map location cloning and marker assisted selection?MAS?,etc.The map is also the main way to understand the cotton genome structure and explain cotton gene formation and variation during cotton evolution.Gossypium mustelinum L.,a heterotetraploid wild cotton species,has the longest genetic relationship with the cultivar Gossypium hirsutum in five wild tetraploid cotton species.In addition to its agronomic characteristics of resistance to verticillium wilt and insect resistance,its fiber quality is rich in genetic variation.China's cotton production is currently facing the problems of single genetic variety and narrow genetic base.In order to utilize the rich genetic diversity among cotton species and introduce the high quality genes of Gossypium mustelinum into the cultivar Gossypium hirsutum.,we constructed a backcross population between G.hirsutum and G.mustelinum,which was conducive to enriching cotton germplasm resources and find out more favorable alleles.At the same time,it provided the basis for chromosome and genomic structure research of G.mustelinum.A genetic map consisting of 1200 marker loci had been constructed using BC₁population derived from an interspecific cross of G.hirsutum×G.mustelinum by our laboratory formerly.The genetic map was encrypted based on previous experiments to obtain a new genetic linkage map,which is the highest density genetic map of G.hirsutum×G.mustelinum so far.The linear relationship between the genetic map and the physical map,constructed using the results of cotton genome sequencing,was compared.The results lay the foundation for the further construction of the wild cotton chromosome segment substitution line,the excavation and localization of the excellent trait alleles,and the discussion of the origin and evolution of allotetraploid cotton.It is important for the improvement of the reality of cotton in China.Simultaneously,that has important theoretical and practical value to ameliorate the reality of the narrowing of genetic basis of cotton in China.The detailed research results are as follows:1.Genetic linkage map encryptionIn this study,more than 14,200 pairs of SSR from different SSR collections were screened to detect polymorphisms between G.hirsutum and G.mustelinum.And a new genetic linkage map was developed by using the newly obtained 1251 polymorphic primers and 1179 pre-existing polymorphic loci.The map consisted of 2588 marker loci distributed across all the 26 chromosomes and covered 4091.58 cM of cotton genome with an average inter-marker distance of 1.58 cM.Among them,there were 1141 loci in A sub-genome,covering a length of 2061.28 cM and an average marker spacing of 1.81 cM;the D sub-genome contained 1447 loci,covering a length of 2030.30 cM,and the average distance between markers was 1.40 cM.2.Analysis of linear relationships among chromosomes on genetic mapsThe collinearity analysis of the shared markers between homologous chromosomes on this genetic map showed that the linear homologous relationship was good overall except for that three pairs of partial homologous chromosomes had the better collinearity.Using the genetic map data of G.hirsutum×G.barbadense in the laboratory,we performed a linear relationship analysis on the same chromosome of these two genetic maps.Studies had shown that the genetic relationship between this genetic map and the genetic map of G.hirsutum×G.barbadense performed well overall.3.Analysis of genome structure variationBy comparing the linear relationship between the genetic map and G.ramondii physical map,it was found that relative to G.ramondii physical map,there were four reciprocal translocations,seven simple translocations and nine inversions.With respect to G.hirsutum physical map and the genetic map,only four inversions were discovered on the genetic map.