Construction Of Cotton Single Segment Introgression Lines And QTL Mapping Of Fiber Quality In Chr7

High yield,good quality,strong resistance and wide adaptability have becomed the goals by most breeders,however yield and quality traits were negatively correlated,thus limiting the exploration and utilization of cotton excellent materials.High yield of upland cotton,sea island cotton fiber has wide adaptability,good quality,high resistance to Verticillium wilt.Upland cotton as the recurrent parent and island cotton as the donor parent,the construction of chromosome segment introgression lines,break the linkage between unfavorable genes become an important way to solve these problems,as it provides excellent new material analysis for the QTL mapping,fine mapping and gene cloning,QTL interaction and mechanism of heterosis Research.This study utilizes a set of sea chromosome segment introgression lines as female parent and recurrent parent CCRI 36,hybridizated to construct a BC₇F₂ segregating population,combined with molecular markers and traits of single segment table,selected single fragment plant of superior fiber quality,constructed single chromosome introgression lines and QTL mapping.The main results are as follows: 1.Analysis on yield characters and fiber quality in the chromosome segment1.Analysis on yield characters and fiber quality in the chromosome segment introgression lines of BC₇F₂ With 1 set of CSSL,fiber yield and quality traits in the population of BC₇F₂ were evaluated and analyzed using partial correlation.The average values of the traits in the population were near to that of the recurrent parent CCRI36 with abundant genetic variations.The transgressive segregation over the recurrent parent CCRI36 is 30.25%,71.25%,29.38% for fiber length,fiber strength and lint percentage,respectively.Boll weight was very significantly positively correlated with fiber micronaire,fiber uniformity.Lint percentage was significantly negatively correlated with fiber length,fiber strength,was very significantly positively correlated with boll weight.2.Construction of single segment introgression lines The genetic background is detected by using 21 pairs of polymorphic SSR primers,and combined with the yield and fiber quality traits,constructed Chr7,Chr8,Chr20,Chr22 single segment introgression lines.The results showed that,the mean of single boll weight of per plant and line were lower than the recurrent parent,and the mean performance of strain was higher than the recurrent parent,0.79g⁰.84 g.In the plant,the mean of lint percentage were lower than the recurrent parent.The mean performance of line were higher than the recurrent parent in lint percentage,while the mean of all strains were not consistent.At the same time,the variation coefficient of yield traits in different strains was lower?<15%?,Boll weight was max?8.55%¹2.00%?,the lint percentage was min?7.24%¹1.24%?.The transgressive segregation over the recurrent parent CCRI36 of 4 strains?chr7,chr8,chr20,chr22?was higher than 90% in the single boll weight,3 strains?chr8,chr20,chr22?in the lint percentage was higher than the 30%.The fiber length,fiber strength and micronaire of plant,line and strain were superior to the recurrent parent CCRI 36,fiber uniformity was close and parts of trait is not consistent.In chr7,chr8,chr20,chr22 lines,the trend of variation coefficient about quality traits were consistently.The variation coefficient of micronaire?4.88%⁶.37%?> fiber strength?4.20%⁶.52%?> fiber length?3.27%⁴.09%?>fiber uniformity?0.88%¹.93%?,and maximum variation coefficient was only 6.52,indicated that multiple backcross promotted the quality traits of introgression lines to be stable.And the transgressive segregation over the recurrent parent CCRI36 of 4 strains of 4 strains?Chr7,Chr8,Chr20,Chr22?in the fiber length,fiber strength were more than 50%,micronaire was second and fiber uniformity was smaller.So the quality traits of Chr7,Chr8,Chr20,Chr22 tend to be stable,fiber length and fiber strength were significantly higher than the recurrent parent CCRI 36,while its skewness and kurtosis were less than 1,which showed continuous distribution and consistented with the characteristics of quantitative traits.3.QTL mapping of fiber quality in chr7 single segment substitution lines F2 segregating population was detected by 17 SSR polymorphism markers,combined with fiber quality traits.QTL mapping results showed that,the QTL controled fiber length,q FL-7-1,located between markers MBR025 and MBR021,LOD value is 7.27,the phenotypic variation was 41.70%,additive the effect was 1.03.The QTL controled fiber strength,q FS-7-1,located between markers MBR021 and MBR044,LOD value is 9.96,the phenotypic variation was 54.93%,additive effect was 2.32.The QTL controled micronaire,q FM-7-1,one of which is located between the markers MBR025 and MBR021,LOD value is 7.60,the phenotypic variation was 22.14%,additive effect was-0.28.Another is located between the markers D07₉66 and HAU1763,LOD value is 7.51,explained phenotypic variation were 25.87%,the additive effect was-0.21.