Cotton (Gossypium) is a worldwide natural fiber crop. Fiber quality improvement lags far behind that of fiber yield. Although interspecific hybridization contributes significantly to improve fiber quality, the mechanism of alien genomic introgression to improve fiber quality has rarely been reported. In this study, a superior fiber-strength line (J02−508) derived from interspecific hybridization was used to dissect the genetic and genomic bases for fiber quality by forward-genetics technologies. Both F₂ and F_2:5 populations were developed from a cross between superior line J02−508 and a weak fiber-quality line (ZRI015). Based on the linkage map constructed from the F_2:5 population, 27 stable quantitative trait loci (QTL) were detected for fiber yield and quality. Unexpectedly, an abnormally high segregation distortion ratio was found for all chromosomes (reaching an average of 83.13 % for each chromosome), and the highest ratio of segregation distortion markers (SDMs) was on chromosome D08, reaching 99.39 %. Taking the SDMs into account, a distinct genome region on chromosome D08 was identified, which had a sizeable physical interval (∼53 Mb length) with low recombination frequency and was significantly associated with fiber strength (named qFS_D08, LOD value = 11.49). Additionally, by integrating different approaches, we initially confirmed that this region was an alien fragment introgressed from wild diploid cotton, G. thurberi (D₁), accounting for nearly 77 % of the length of chromosome D08 in the J02−508 genome. We provided molecular evidence for fiber strength improvement caused by introgression. This study is also beneficial to understand the importance of interspecific hybridization for improving fiber strength during cotton breeding.

棉花（棉）是世界范围内的天然纤维作物。纤维质量的改善远远落后于纤维产量。尽管种间杂交对改善纤维质量做出了重要贡献，但鲜有报道外源基因组渗入改善纤维质量的机制。在这项研究中，通过种间杂交获得了优良的纤维强度谱线（J02-508），通过正向遗传学技术解析了纤维质量的遗传和基因组基础。F ₂和F _2：5种群均由上品系J02-508与较弱纤维品质品系（ZRI015）之间的杂交得到。基于F _2：5构造的链接图人群中，检测到27个稳定的定量性状基因座（QTL）的纤维产量和品质。出乎意料的是，发现所有染色体的分离畸变率异常高（每个染色体平均达到83.13％），并且分离畸变标记（SDMs）的最高比率出现在D08染色体上，达到99.39％。考虑到SDM，在D08染色体上发现了一个独特的基因组区域，该区域具有相当大的物理间隔（〜53 Mb长），重组频率低，并且与纤维强度显着相关（名为qFS_D08，LOD值= 11.49）。此外，通过整合不同的方法，我们最初确认该区域是野生二倍体棉花苏铁（G. thurberi）的外来片段（D ₁），约占J02-508基因组中D08染色体长度的77％。我们提供了因渗入而提高纤维强度的分子证据。这项研究也有助于了解种间杂交对提高棉花育种过程中纤维强度的重要性。