| Cotton is one of the most important economic crops in the world.Cotton fiber is an important material for textile industry,and for human daily life.Along with the progress of technologies in textile industry and improvement of human living standard,the demand for cotton fiber supply not only increase in quantity,but also in diverse combination of various qualities such as high-strength fiber,natural color fiber,various length and fineness fiber.In this study,231 F6:8recombinant inbred lines（RILs）,derived from a G.hirsutum intraspecific cross between Lumianyan28,a cultivar with wide adaptability and high yield potential,and Xinluzao24,a cultivar with elite fiber quality were genotyped using the SNP markers which were harbored in Cotton SNP80K array and the SSR markers which were originated from various sources.The genetic linkage map was thus constructed and the QTLs for fiber quality traits detected by the composite interval mapping（CIM）method.The results of this study could play essential roles in future breeding programs through maker assisted selection and in candidate gene functional studies.In this study,the phenotypic data of fiber quality traits across 9 environments were statistically analyzed.The results showed that the absolute values of the skewness coefficients of each fiber quality traits were less than 1,which indicated that they fitted the normal distribution,and that these traits were controled by the multiple minor genes.The correlation analysis showed that fiber length was significantly or extremely significantly positively correlated to fiber strength;fiber micronaire were significantly or extremely significantly negative correlation to fiber length,and fiber strength.It indicated the possibilities of simultaneous improvement of both fiber length and fiber strength,and the impossibilities or difficulties of simultaneous improvement of fiber micronaire and fiber length/strength.The 231 RILs,together with their parental cultivars,Xiluzao 24 and Lumianyan 28,were genotyped using Cotton SNP80K arrays,and eventually 5202 SNP markers were obtained.The polymorphisms between Xiluzao 24 and Lumianyan 28 were also screened with a set of 9668 SSR primer pairs and totally187 polymorphic SSR primer pairs were obtained.Genotyping the RILs with these polymorphic primer pairs generated 193 SSR marker loci.The linkage analysis of these 5202 SNP loci and 193 SSR loci were constructed using the High Map software,and a genetic linkage map which contained 4851 marker,including 4729 SNP loci and 122 SSR loci,was constructed.The genetic map spanned 2477.99 c M of upland cotton genome with an average adjacent marker interval of 0.51 c M and 26 linkage groups being allocated on all the chromosomes of hirsutm cotton.In these linkage groups,the maximum number of markers contained one group was 481（chr08）,and the minimum number of markers was 19（chr17）.Atsubgenome totally contained 3300 markers with a genetic distance of 1474.63 c M and an average adjacent marker interval of 0.45 c M;while Dtsubgenome contained 1551 markers with a genetic distance of1003.36 c M and an average adjacent marker interval of 0.65 c M.Windows QTL Cartographer2.5 software was used to detect QTLs for fiber quality traits across 9environments（from the year 2013 to 2015）by CIM method.A total of 232 QTL for fiber quality traits were identified,39 of which were stable ones that could be identified across at least two environments:7 QTL were for fiber length,10 for fiber strength,15 for micronaire,3 for fiber uniformity,and 4 for fiber elongation.Comparing with previous studies,94 were repeatedly identified common QTLs,and the remaining ones were possibly new QTLs.In these new QTLs,19 were identified in at least two environments.A total of 106 QTL were identified to form 45 QTL clusters on 20 chromosomes.The QTL clusters containing at least two stable QTLs were cluster-chr07-2,cluster-chr11-3,cluster-chr13-1,cluster-chr16-3,cluster-chr19-1,cluster-chr24-3.Comparing analysis revealed that 9 clusters were congruent with previous studies,namely cluster-chr05-2,cluster-chr07-1,cluster-chr07-2,cluster-chr13-3,cluster-chr15-2,cluster-chr15-3,cluster-chr20-2,and cluster-chr24-1,the remaining could be the new QTL cluster.These QTL clusters,especially the ones containing stable QTLs,are of great significance for gene functional studies and molecular assisted selection in future breeding programs. |
