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

A major fi ber strength quantitative trait locus (QTL) has been identifi ed 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 confi rmed the effects of this QTL by crossing Suyuan 7235 with two U.S. germplasm lines with different fi ber strength. This QTL 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 fi ber strength appear to be greater in Suyuan 7235 × ‘Sealand 883’ (Pop-883) than in Suyuan 7235 × ‘Sealand 542’ (Pop-542) despite the Sealand 883 parent having stronger fi ber than the Sealand 542 parent. Deoxyribonucleic acid fi ngerprinting 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 fi ber strength QTL could signifi cantly improve the economic value of Upland cottons in the United States. The identifi cation of 27 novel markers tightly linked in this region adds additional tools to allow this QTL to be more effi ciently deployed in breeding cultivars with improved fi ber strength.