| Cotton is the most important natural fiber crop in the world,and it is also a significant industrial crop which provides a mass of plant oil and protein.Gossypium hirsutum also known as upland cotton is the most widely planted species because of its good adapt ability and yielding ability.However,the fiber quality of upland cotton is relatively poor compared with G.barbadense and the genetic diversity is low.Demands on fiber yield and quality are increased along with the continuous development of modern textile industry.Improving the fiber quality and yield at the same time has always been the goal of cotton breeders.G.hirsutum races are characterized with resistance to insect,disease,salt,alkali and drought.Furthermore,G.hirsutum races also showed the ability to improve yield and fiber quality.Therefore,it is important to identify the favorable alleles of yield and fiber quality traits for broadening the upland cotton germplasm and molecular marker assisted selection（MAS）.In this study,G.hirsutum lines Jinnong07 and G.hirsutum race punctatum accession TX-230 were used as parents to produce an F2 population.The genetic map linkage map constructed from F2 population,and QTL for yield and fiber quality traits were identified in F2,F2:3 and F2:4 populations.The main results are as follows,1.Detection of Polymorphic primers and Population GenotypingA total of 14864 pairs of SSR primers were used to screen the polymorphic primers between Jinnong07 and TX-230,and 747 pairs of polymorphic primers were obtained,with a polymorphic ratio of 5.03%.The polymorphic primers were used to genotye the F2 individuals,and 755 loci were obtained.Eight primer pairs produced two loci.2.Genetic map and Segregation distortion of markersAll 755 loci were performed on linkage analysis,and a genetic linkage map consisting of 41 linkage groups was constructed.The map covered 3428cM with the average distance of 4.54cM between markers and occupied approximately 76.9%of G.hirsutum genome.A-sub-genome contained twenty-one linkage groups and 287 loci with a total length of 162.25cM and an average genetic distance of 5.65cM between markers.Eighty of these 287 loci displayed segregation distortion,accounting for 27.9%loci on A-sub-genome.The D-sub-genome consisted of 20 linkage groups and 465 loci and covered a length of 1805.5cM with an average genetic distance of 3.88cM between markers.Eighty loci showed the segregation distortion accounting for 27.9%on A-sub-genome,whereas 123 showed the segregation distortion accounting for 26.5%in D-sub-genome.3.Yield and fiber quality trait QTLA total of 118 QTLs were identified,including 41 yield QTLs and 77 fiber quality QTLs.Among them,12 QTLs were detected in two environments and two were detected in all three generations.The QTL detected in two or three generations were considered to be stable QTL,and can be used for further fine-mapping and map-based cloning. |
