Mapping QTL Of Fiber Traits With Composite Cross Population In Upland Cotton (Gossypium Hirsutum L.)

Cotton is the leading natural fiber crop,and fiber is the main resource of the textile manufacture.The world cotton production was supplied by two tetraploid species,G hirsutum L.and G.barbadense L.,and G.hirsutum L.accounted for 90%of the total production.However,as the basic raw materials of textile industry,upland cotton generally has lower quality fibers than sea-island cotton.With the advances in spinning technology and the needs of the people,the better fiber quality will be required.These requirements of fiber quality have attracted a lot of efforts of governments and scientists to improve cotton fiber quality,especially that of upland cotton.Conventional genetic strategies have been employed to enhance the fiber properties of upland cotton for over half a century.Recent advances in DNA markers offer plant breeders a rapid and precise alternative approach to conventional selection schemes to improve quantitative traits.Using the markers which were close linked with fiber quality QTLs to conduct marker assited selection will be helpful to improve fiber quality of cotton in China.A composite cross population derived from the cross between(Yumian 1×CRI 35) F₁ and(Yumian 1×Belshinuo) F₁ was used to construct a genetic linkage map with SSR markers which have stable polymorphism,and the linkage map was used to detect and map QTLs affecting fiber quality.The mainly results were as following:1.Fiber quality of mapping parents and composite populationThe fiber strength of Yumian 1 was better than that of Zhong 35 and Belshinuo obviously,and the fiber length and length uniformity of Belshinuo were better than that of Yumian 1 and CIR 35.The mironaire and elongation are the same for three parents. Five fiber quality traits show segregation beyond three parents. 2.Primer pair polymorphism between three parentsA total of 6,565 primer pairs were used to screen the polymorphic primers between CRI 35,Yumian 1 and Belshinuo,and 92 polymorphic primer pairs were obtained,accountings for 1.4%of the total primer pairs.3.Genotyping Composite populationThe polymorphic primer pairs were used to genotype the 172 individual plants of composite population and 96 loci were obtained.Four out of 92 primer pairs produced two loci.4.Construction of upland cotton genetic linkage mapA linkage map with 63 loci and 19 linkage groups was constructed.Out of these linkage groups,17 were assigned on 17 chromosomes,while the other 2 were not assigned on any chromosomes.The linkage groups spanned from 7.0 cM to 67.2 cM. The linkage map covered a whole length of 656 cM with an average interval of 10.41 cM between two markers,accounting for 14.8%of the cotton genome.5.QTL mapping of fiber qualityBased on the linkage map and the fiber quality determined,ten QTL controlling fiber quality traits were identified by using MapQTL5.0.Three fiber length QTL explained phenotypic variance from 7.8%to 26.5%,two fiber uniformity QTL explained 7.4%and 10.9%of phenotypic variance,two fiber micro QTL explained phenotypic variance from 9.5%to 10.0%,one fiber elongation QTL explained 6.4%of phenotypic variance,and two fiber strength QTL explained 13.9%and 14.2%of phenotypic variance.