QTL Mapping Of Yield、Fiber Quality And Resistance To Verticillium Wilt In Lumianyan15Recombinant Inbred Lines

As the most important economic crop in the world, cotton has been playing an important role in the economy of China. Cotton is the leading natural fiber source, and slso the daily necessities for people, which has a very important influence on the development of the national economy. With the development of spinning technology and increase of social demands, the more cotton yield and better fiber quality will be required. Breeding and cultivation of cotton varieties with fine quality, high yield and disease resistance become more and more important.In this research, a RIL population with303lines of Lumianyanl5which was widely cultivated in China was developed from the upland cotton cross of R55and613. These lines were used to analysis the correlation between yield and fiber quality related traits; in this study, genetic linkage map was constructed with the polymorphic SSR markers. Based on the map, the QTLs for yield, fiber quality and resistance to Verticillium Wilt were identified with Composite Interval Mapping (CIM) method. Using marker assisted-selection which is closely linked with cotton yield, fiber quality and Verticillium Wilt Resistance QTLs, and this could be very useful in the molecular marker assisted selection (MAS) breeding programs.The correlation analysis showed that Micronaire was significant negative correlation with fiber length, elongation and strength, but significant positive correlation with uniformity; Fiber Length showed a highly significant positive correlation with uniformity and strength, but very significant negative correlation with elongation; Elongation was very significant negative correlation with the other fiber quality traits; Fiber strength showed a highly significant negative correlation with Micronaire and elongation, but indicated very significant positive correlation with the other fiber quality traits; Boll weight was very significant positive correlation with Micronaire and highly significant negative correlation with strength, but was not correlation with the other fiber quality traits; Lint percent showed a very significant negative correlation with fiber length, uniformity and strength, but was in a significant positive correlation with elongation.Path analysis indicated that, Boll number per plant showed the highest path coefficient (0.5493) for seed cotton yield per plant, then was the Boll weight (0.3150).Regression analysis showed that, Boll weight was positively correlated wiht seed cotton yield per plant and has the biggest correlation. In cotton breeding, we should focus on the bigger boll and more boll number per plant, in order to get the purpose of breeding as quickly as possible.A total of7187pairs of SSR primers were used to screen the polymorphism between R55and613,86pairs of polymorphic primers were obtained, and together with another120pairs of polymorphic primers for genotyping its RIL population, which produced216polymorphic loci. The software of Joinmap3.0with LOD of4.0was used to analyze data, and a genetic linkage map with174loci were constructed, which comprised of38linkage groups covering1266.53cM with an average interval of7.28cM, and approximately28.46%of the whole genome.32linkage groups were assigned to22chromosomes.A total of14QTLs for fiber quality and13QTLs for yield traits and1QTLs for resistance to Verticillium wilt were identified with Composite Interval Mapping (CIM) method in the Iumianyan15RIL population, explaining22.97%and14.39%phenotypic variation and distributed in12chromosomes or linkage groups. A total of3QTLs for boll weight,3QTLs for seed index,2QTLs for micronaire and2QTLs for fiber length could be detected in different generations. These stable QTLs should be useful in the molecular marker assisted selection (MAS) breeding programs.