Identifying QTL For Fiber Quality Traits With Three Upland Cotton (Gossypium Hirsutum L.) Populations

Cotton (Gossypium spp.), one of the most economically important crops worldwide, is an important natural textile fiber and oil crop. Conventional breeding has played an important role in yield and fiber quality improvement of upland cotton, however, the quantitative inheritance and unfavorable correlations between yield and fiber quality greatly limited the efficiency of conventional breeding efforts in upland cotton improvement. So it needs to develop more effective strategies for cotton breeding programs in the future. The development of molecular markers makes it possible for plant breeders to find a rapid and precise alternative approach to conventional selection schemes for improving crop agronomic and economic traits. Using the closely-linked marker with QTL to select traits will be more effective in cotton improvement. The identification of stable QTL affecting fiber traits across different generations will be greatly helpful to improve fiber quality in cotton molecular marker-assisted selection in the future.A total of11055SSR primer pairs were used to detect polymorphism primers, and972(8.8%) polymorphic primer pairs were obtained. Among them,343(3.1%) primer pairs showed polymorphism between Yumian1and Acala Maxxa,340(3.1%) between Yumian1and CA3084, and289(2.6%) betwen Yumian1and TAM94L-25, respectively.The343polymorphic primer pairs produced346loci in population (Yumian1×Acala Maxxa),340(3.1%) polymorphism primer pairs produced343polymorphic loci in population (Yumian1×CA3084), and289(2.6%) polymorphism primer pairs amplified292loci in population (Yumian1×TAM94L-25).The x2test showed that59(17.1%) markers deviated from segregation ratio in population (Yumian1×Acala maxxa),33(9.6%) in population (Yumian1×CA3084) and24(8.2%) in population (Yumian1×TAM94L-25), respectively.Intraspecific linkage mapsThe genetic map of population (Yumian1×Acala maxxa) spanned1639.9cM, and included57groups and319locis, leaving27unlinked loci. The distance between adjacent markers is5.1cM. Fifty-seven linkage groups were assigned to26chromosomes, and one group named as "un" was not found the corresponding chromosome.The genetic map of population population (Yumian1×CA3084) covered a length of1687.4cM, and included55groups and305locis, leaving38unlinked loci. All55groups were assigned to26chromosomes.The genetic map of population (Yumian1×TAM94L-25) covered1428.9cM, and and included45groups and259locis, leaving33unlinked loci. All45groups were assigned to26chromosomes.QTL mapping for. fiber quality traitsA total of34QTL were detected for five fiber quality traits in population (Yumian1×Acala maxxa). Six QTL for fiber length explained9.5%-18.1%phenotypic variation. Six QTL for fiber uniformity explained10.8%-26.3%of phenotypic variation. Six QTL for fiber micronaire explained13.2%-29.7%of phenotypic variation. Ten QTL for fiber elongation explained9.2%-20.9%of phenotypic variation. Six QTL for fiber strength explained9.2%-10.4%of phenotypic variation. Among these QTL, one anchored on Chr.15were detected in three environments, and two of them were detected in two environments.Thirty-eight QTL were detected in population (Yumian1×CA3084).9QTL for fiber length explained7.0%-20.9%of phenotypic variation.5QTL for fiber uniformity explained9.1%-15.1%of phenotypic variation.8QTL for fiber micronaire explained7.5%-20.0%of phenotypic variation.9QTL for fiber elongation explained10.7%-52.7%of phenotypic variation.7QTL for fiber strength explained8.7%-25.1%of phenotypic variation. Otherwise, Two QTL (qFS21.2and qFE18.1) were detected in two environments.A total of27QTL for five fiber quality traits were indentified in population (Yumian1xTAM94L-25).7QTL for fiber length explained7.1%-42.6%of phenotypic variation. 4QTL for fiber uniformity explained11.0%-22.2%of phenotypic variation.5QTL for fiber micronaire explained10.8%-21.5%of phenotypic variation.6QTL for fiber elongation explained8.7%-26.7%of phenotypic variation.5QTL for fiber strength explained9.8%-28.6%of phenotypic variation. One fiber length QTL was detected in three environments, and one QTL for fiber elongation and one fiber strength QTL was detected in two environments.