Analysis Of Genetic Variation Fiber Length Of Interspecific Hybrid Between Gossypium Hirsutum L. And G. Barbadense L. And Its Backcross Populations

In this study, genetic linkage maps for tetraploid cotton were constructed by means of DNA-basedmarkers based on two segregation populations. Cotton agronomic trait and fiber quality were investigatedin the population of F₂individuals and corresponding F_2:3families and High backcross generations(BC₄F₂and BC₄F_2:3). On the basis of genetic map constructed; quantitative traits analysis and QTLs detection wasperformed. The purpose of this study was to find the genetic loci associated significantly with fiber length,so the further research and application （such as marker-aided selection, map-based cloning） could beconducted. The results obtained in this study were as follows.1. The high yielding fine, strong resistance of xi9and good fiber quality traits of xinhai16and itsoffspring produced by group a comparative study. Results showed that fiber length between xi9andxinhai16is fit for cross breeding parent matching principle; And fiber length properties presented normaldistribution, can detect QTL.2. Upland cotton and island cotton as material, the use of the experimental set up and optimizedmolecular marker system, analysis of48cotton resources and based on this experiment is a newdevelopment of cotton fiber series of applicability of93EST-SSR detection, the results show that thesystem can have as a foundation for upland cotton germplasm characteristics; New sea16representativewith sea island cotton. This experiment optimized molecular marker technology system is feasible.3.An interspecific F2population consisted of297plants, which was developed from the cross betweenXi9（characterized as high fiber yield） and Xinhai16（characterized as excellent fiber quality）, wasgenotyped with SSR, SRAP and EST-SSR markers. Over1200（pairs of） primers （combinations） were usedto survey the polymorphism between the parents, and the result showed that245pairs of SSR primers（67.1%）,88EST-SSR primers （24.1.3%）,32SRAP primer combinations （8.8%） could amplifypolymorphic bands.4.The marker data were subsequently analyzed using QTL-IcIMapping2.3. Among the229pairs ofSSR primers,88EST-SSR primers,29SRAP primer were arranged into22linkage groups. The linkagemap covered4307.73cM with an average distance of12.45cM between two markers.5.The F₂plants and corresponding F_2:3families （arranged in2replicates in a random block design）were used for scoring the phenotypes of fiber length. The present genetic linkage map and traits data wasused to identify and map the quantitative trait loci （QTLs） affecting fiber length traits in297F_2:3familylines. The method of composite interval mapping was applied to search for QTLs by QTL-ICIMappingV2.3. The log odds-ratio threshold of QTL detection was3.0, on the basis of which this analysis yielded34QTLs: two QTLs controlling fiber length are significant marks in linkage4th,explained17.30729%（NAU3207/me4em5）and13.7922%（me3em10/B3171） of phenotypic variation （PVE）.6.An advanced-generation population was developed by first crossing G. hirsutum cv.xi9and G.barbadense cv. Xinhai16（characterized as excellent fiber quality）,then single seed descent to BC₄F₂generation. This population consisted of234BC₄F₂lines, which containing chromatin segmentintrogressived from xinhai16to xi9background. 7.Field experiment was carried out for234BC₄F_2:3families in2009（arranged in3replicates in arandom block design）, and the phenotypes of fiber quality were scored. The phenotypic distribution of theindividual introgression lines for five traits indicated the trend of regression of individual lines to xinhai16and the wide variance for each trait. The result from correlation analysis among the five traits showed that:trait combinations were significantly correlated except the combinations of micronaire and elongation, butthe coefficients were different.Following the order and primers of a linkage map developed from the F₂populationfrom the same cross, several hundred of SSR markers were used in this study to detect genotypes.278primers were arranged into19linkage groups. The linkage map covered4351.65cM with an averagedistance of15.65cM between two markers.8.The method of composite interval mapping was applied to search for QTLs by QTL-ICIMappingV2.3. The log odds-ratio threshold of QTL detection was3.0, on the basis of which this analysis yielded74QTLs: seven QTLs controlling fiber length are significant marks in linkage all,explained from9.1078%to13.6005%of phenotypic variation （PVE）.And there are the dominant gain dominant, That said thesea-land fiber length of the hybrid offspring traits has a strong advantage, enhancing the use in breeding...