Mapping and Validation of Fiber Strength Quantitative Trait Loci on Chromosome 24 in Upland Cotton

A major fiber strength quantitative trait locus (QTL) has been identified on chromosome 24 in the Chinese germplasm line 'Suyuan 7235'; however, the effects of this QTL have not been tested in different genetic backgrounds. In this study, we confirmed the effects of this QTL by crossing Suyuan 7235 with two U.S. germplasm lines with different fiber strength. This OIL was consistently expressed over generations and years in both populations. The Suyuan 7235 allele explained up to 40% of the total phenotypic variation and accounted for an increase of up to 22.8 kN m kg(-1). The effects on fiber strength appear to be greater in Suyuan 7235 x 'Sealand 883' (Pop-883) than in Suyuan 7235 x 'Sealand 542' (Pop-542) despite the Sealand 883 parent having stronger fiber than the Sealand 542 parent. Deoxyribonucleic acid fingerprinting on a collection of elite cotton (Gossypium hirsutum L.) lines indicated that this QTL is not present in a survey of elite U.S. public germplasm. These results indicate that this fiber strength QTL could significantly improve the economic value of Upland cottons in the United States. The identification of 27 novel markers tightly linked in this region adds additional tools to allow this QTL to be more efficiently deployed in breeding cultivars with improved fiber strength.