Construction of genetic map and QTL analysis of fiber quality traits for Upland cotton ( Gossypium hirsutum L.)

Cotton fiber quality traits are controlled by multiple genes of minor effect. Identification of significant and stable quantitative trait loci (QTL) across environments and populations lays foundation for marker-assisted selection for fiber quality improvement and studies of its molecular regulation. Here, a detailed genetic map is constructed and QTL are detected based on an intraspecific recombinant inbred line population derived from a cross between Upland cotton cultivar/line Yumian 1 and 7235. A total of 25,313 SSR primer pairs, including 5,000 developed from G. raimondii BAC-ends sequences, were used to construct the genetic map which finally contained 1,540 loci, spanning 2,842.06 cM, with an average of 1.85 cM between adjacent markers. With 4 year fiber quality traits data, variance analysis revealed that they were significantly affected by genetic and environmental factors. Significant correlations were also detected between them. A total of 62 QTL were identified with combined analysis and single environment analysis. These QTL explain phenotypic variation from 5.0 to 28.1 %. For each trait, favorable alleles were conferred by both parents. Seventeen QTL were detected in more than one environment. The genetic map and stable QTL are valuable for Upland cotton genome research and breeding projects to improve fiber quality.