QTL Mapping for Fiber Quality and Yield Traits Based on Introgression Lines Derived from Gossypium hirsutum x G-tomentosum

The tetraploid species Gossypium hirsutum is cultivated widely throughout the world with high yield and moderate fiber quality, but its genetic basis is narrow. A set of 107 introgression lines (ILs) was developed with an interspecific cross using G. hirsutumacc. 4105 as the recurrent parent and G. tomentosum as the donor parent. A specific locus amplified fragment sequencing (SLAF-seq) strategy was used to obtain high-throughput single nucleotide polymorphism (SNP) markers. In total, 3157 high-quality SNP markers were obtained and further used for identification of quantitative trait loci (QTLs) for fiber quality and yield traits evaluated in multiple environments. In total, 74 QTLs were detected that were associated with five fiber quality traits (30 QTLs) and eight yield traits (44 QTLs), with 2.02-30.15% of the phenotypic variance explained (PVE), and 69 markers were found to be associated with these thirteen traits. Eleven chromosomes in the A sub-genome (At) harbored 47 QTLs, and nine chromosomes in the D sub-genome (Dt) harbored 27 QTLs. More than half (44 QTLs = 59.45%) showed positive additive effects for fiber and yield traits. Five QTL clusters were identified, with three in the At, comprised of thirteen QTLs, and two in the Dt comprised of seven QTLs. The ILs developed in this study and the identified QTLs will facilitate further molecular breeding for improvement of Upland cotton in terms of higher yield with enhanced fiber quality.