Genetic Dissection Of Fiber Quality QTL In Upland Cotton (Gossypium Hirsutum L.) Germplasm With Introgression Genetic Elements From Island Cotton (G. Barbadense L.)

Cotton is an important cash crops, occupy a very important position in the national economy.High yield, high quality and disease-resistant have been important goal of cotton breeding. Withthe constant progress of textile technology, fiber quality requirements are also rising. Over the pastdecade, with the development of molecular marker technology, as well as a range of mappingsoftware, cotton genetic mapping and QTL mapping has made an important breakthrough. Layinga solid foundation for important agronomic traits and fiber quality traits of gene cloning andmolecular marker assisted breeding.On the basis of previous studies, with two high-quality secondary introgression lines R472,R497and transgenic cotton Lumianyan22as parents to establish a secondary mapping population,the two groups were named as group B and C, each containing514and544plants.Use screened group B101pairs of polymorphic primers amplified514F2populations, Cgroups,112pairs of polymorphic primers amplified544F2populations. Using mapping softwareJoinMap4.0mark linkage analysis, LOD=6.5. B groups,92polymorphic loci derived from101primer pairs could be mapped into18linkage groups, covering516.2cM, cotton accounted for11.6%of the total genome. By chromosomal localization,18linkage groups positioned on the15chromosomes, the average distance between the marks is5.61cM. C group,105polymorphic lociderived from112primer pairs could be mapped into19linkage groups, covering822.4cM,positioned on the15chromosomes, about accounting for18.48%of total cotton genome. Eachlinkage group average of seven markers, the average distance between the marks is7.83cM.After testing, the introgression fragments of group B distributed on seven chromosomes,respectively Chr.16, Chr.19, Chr.18, Chr.3, Chr.13, Chr.7, Chr.15. Covering a total geneticdistance of80.13cM, approximately21.4percent of cotton genome; group C, introgressionmarkers distributed on eight chromosomes, respectively Chr.21, Chr.19, Chr.3, Chr.18, Chr.25,Chr.23, Chr.7, Chr.5. Introgression fragments cover a total genetic distance of98.66cM, approximately17.51percent of cotton genome.In group B,20QTLs associated with fiber quality were detected with software Windows QTLCartographer2.5in three data sets, F2,F2：3LQ and F2：3HN.4QTLs were associated with fiberlength,4QTLs were related to fiber uniformity,2of the QTLs were for fiber micronaire,4QTLsfor lint fiber strength and6were for fiber elongation. In group C,27QTLs associated with fiberquality were detected with software Windows QTL Cartographer2.5in three data sets, F2,F2：3LQand F2：3HN.5QTLs were associated with fiber length,4QTLs were related to fiber uniformity,8of the QTLs were for fiber micronaire,4QTLs for lint fiber strength and4were for fiberelongation,2QTLs for lint percentage. In this study, two positioning group R472x LMY22(B)group and R497x LMY22(B) group have found a phenomenon of the distribution of QTL clusters.There are18fiber quality traits QTLs can stable in different groups and different environment.In group B, one fiber strength of interaction QTL was detected by QTLNetwork-2.2; In groupC, one fiber elongation and two pairs of micronaire interaction QTLs were detected byQTLNetwork-2.2; Analysis of fiber quality traits in three environments showed that the geneticeffects of fiber length is much greater than environmental effects, gene action is mainly additiveeffects; fiber strength heritability is larger, main mode of gene action were additive; Theenvironmental impact of fiber uniformity, fiber elongation and fineness greater than genetic effects.Heritability of fiber fineness minimum, environmental effect is greater, Vulnerable toenvironmental impact.Completion of the experiment not only has important theoretical implications forunderstanding the genetic mechanism of gene introgression excellent fiber properties of theformation, but also molecular marker-assisted cotton fiber quality and yield traits and evenimproved synchronization excellent fiber introgression major QTL candidate gene map-basedcloning has important application value.