An aldehyde dehydrogenase gene, , positively regulates fiber strength in upland cotton ( L.).

High fiber strength (FS) premium cotton has significant market demand. Consequently, enhancing FS is a major objective in breeding quality cotton. However, there is a notable lack of known functionally applicable genes that can be targeted for breeding. To address this issue, our study used specific length-amplified fragment sequencing combined with bulk segregant analysis to study FS trait in an F population. Subsequently, we integrated these results with previous quantitative trait locus mapping results regarding fiber quality, which used simple sequence repeat markers in F, F, and recombinant inbred line populations. We identified a stable quantitative trait locus associated with FS located on chromosome A06 (90.74-90.83 Mb). Within this interval, we cloned a gene, , which harbored a critical mutation site in coding sequences that is distinct in the two parents of the tested cotton line. In the paternal parent Ji228, the gene is normal and referred to as ; however, there is a nonsense mutation in the maternal parent Ji567 that results in premature termination of protein translation, and this gene is designated as truncated . Validation using recombinant inbred lines and gene expression analysis revealed that this mutation site is correlated with cotton FS. Virus-induced gene silencing of in cotton caused significant decreases in FS and fiber micronaire. Conversely, overexpression in boosted cell wall component contents in the stem. The findings of our study provide a candidate gene for improving cotton fiber quality through molecular breeding.