Gossypium barbadense possesses a superior fiber quality because of its fiber length and strength. An in-depth analysis of the underlying genetic mechanism could aid in filling the gap in research regarding fiber strength and could provide helpful information for Gossypium barbadense breeding. Three quantitative trait loci related to fiber strength were identified from a Gossypium barbadense recombinant inbred line (PimaS-7 × 5917) for further analysis. RNA sequencing was performed in the fiber tissues of PimaS-7 × 5917 0–35 days postanthesis. Four specific modules closely related to the secondary wall-thickening stage were obtained using the weighted gene coexpression network analysis. In total, 55 genes were identified as differentially expressed from 4 specific modules. Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes were used for enrichment analysis, and Gbar_D11G032910, Gbar_D08G020540, Gbar_D08G013370, Gbar_D11G033670, and Gbar_D11G029020 were found to regulate fiber strength by playing a role in the composition of structural constituents of cytoskeleton and microtubules during fiber development. Quantitative real-time PCR results confirmed the accuracy of the transcriptome data. This study provides a quick strategy for exploring candidate genes and provides new insights for improving fiber strength in cotton.

This study aims to reveal the genetic variation of fruit branch angle (FBA) in upland cotton, thereby providing a scientific basis and practical guidance for cotton architecture breeding. We explored the genetic variation pattern of FBA in 300 upland cottons from different regions and different periods, respectively. Cluster analysis and principal component analysis were used to comprehensively evaluate the plant architecture traits and yield traits in 300 upland cottons. The results demonstrated that the range of variation of FBA in cotton was 43.59–69.32°, the coefficient of variation ranged from 6.06% to 7.42%, and the broad-sense heritability was 75.50%. The order of FBA in different regions was as follows: Foreign Germplasm (FG; 56.77°) > Yellow River Region (YRR; 56.24°) > Yangtze River Region (YZRR; 56.16°) > Liaoning Special Maturing Region (LSMR; 55.35°) > Northwest Inland Region (NIR; 55.25), which is rich in genetic diversity. FBA in cotton in different periods had obvious differences. FBA was the largest before 1960, and as the period progressed, FBA showed an overall fluctuating decrease, whose coefficient of variation and genetic diversity index tended to increase. In this study, it was found that when the range of FBA was 50.46–55.31°, cotton had the best overall performance, with compact architecture, fewer empty fruit branches, more bells, and higher yield, which can be further developed and utilized as an excellent cotton germplasm resource.