Construction Of Chromosome Segment Introgression Lines And QTL Mapping Of Fiber Quality In D Sub-genome Of Gossypium Barbadense

Cotton is not only a natural fiber crop but also an oil crop,as well as a high-protein food crop.Gossypium genus contain four cultivated species,and G.hirsutum and G.barbadense produced about 97%of the world?s cotton.G.hirsutum has the advantages of high yield,whereas G.barbadense has the best fiber quality but an undesirable yield.With the aim of breeding high yield and superior quality germplasm,breeders had pay their attention on transferring the superior gene controlling fiber quality from G.barbadense into G.hirsutum.In this study,a set of chromosome segment introgression lines?CSILs?was developed from an interspecific cross between G.hirsutum cultivar CCRI35 and G.barbadense cultivar Pima S-7.Subsequely,QTL controlling fiber quality were identified through BC₃F₂ and BC₃F_2:3:3 population.The main results were as follows:1.Genotypes of CSILsA total of 192 SSR markers evenly distributed on the D sub-genome were used to genotype 591 BC₃F₂ individuals,and 589 CSILs were detected.The background chromosome recovery rate of CSILs ranged from 67%to 99.4%,with an average of91.5%.The introgresssion segment number of CSILs ranged from 1 to 23,with an average number of 7.4.The length of introgresssion segments ranged from 11.4 cM to628.8 cM,with an average length of 146.7 cM and the average introgresssion rate of7.4%.2.Genotype of CSIL chromosomeThe average length of recurrent parent segments on each chromosome ranged from 101.0 cM to 201.5 cM with an average of 136.3 cM.The recurrent parent recovery rate of each chromosome ranged from 88.9%to 93.5%,with an average of91.6%.The average length of the homozygous introgresssion segments on each chromosome ranged from 0.9 cM to 4.0 cM.Chr21 has the longest homozygous introgresssion segments,and Chr23 has the shortest homozygous introgresssion segments.The average length of the hybrid introgresssion segments ranged from 7.2cM to 13.6 cM.Chr19 has the longest hybrid introgresssion segments,and Chr21 has the shortest hybrid introgresssion segments.The average length of the total introgresssion segments on each chromosome ranged from 8.9 cM to 16.5 cM.For total introgresssion segments,Chr19 has the longest and Chr23 has the shortest.3.QTL mapping of fiber qualityA total of 24 QTL for fiber quality were detected,including 7 QTL for fiber length,7 QTL for fiber micronaire,8 QTL for fiber strength,1 QTL for fiber uniformity,and 1 QTL for fiber elongation.These QTL located on all chromosomes of D subgenome,and they explained phenotypic variation ranged from 1.7%to 7.2%.Among these QTL,thirteen favorable alleles derived from Pima S-7,and eleven from CCRI35.