An alpha/beta-hydrolase-like gene (GhABH) is identified to be responsible for fiber quality from a multi-effect quantitative trait locus (QTL) on chromosome A06 of upland cotton.

Key message: GhABH was fine-mapped to a stable multi-effect fiber QTL on chromosome A06 through KASP genotyping and RNA-seq analysis. SNPs in GhABH showed significant associations with fiber traits. GhABH-VIGS simultaneously enhanced fiber length, strength, and fineness by regulating cell wall thickness and helical growth. Arabidopsis overexpression lines exhibited shortened root hairs and reduced stem cell wall thickness. Transcriptome profiling of GhABH-silenced fibers implicated GhNAC and other candidate genes in the GhABH regulatory network. Cotton fiber strength (FS), length (FL), and fineness/micronaire (FM) are economically critical traits, yet the genetic basis for their coordinated regulation remains unclear. Here, we identified a stable quantitative trait locus (QTL) on chromosome A06 associated with both FS and FL. Using KASP markers in a 229-line F_2:3 population derived from the near-isogenic recombinant inbred lines A_dh (exhibiting long, strong fibers) and A_dl (with short, weak fibers), we fine-mapped the QTL to an interval of 11.41 Mb containing 244 genes, including 16 genes differentially expressed during fiber development. Two candidate genes, GhABH and GhMBF1c, showed expression changes with distinct patterns during fiber development. Notably, single-nucleotide polymorphisms in GhABH showed significant associations with FS and FL, underscoring the relevance of this gene for fiber quality. Silencing GhABH in A_dh reduced the fiber diameter but enhanced helix formation and cell wall thickness, ultimately improving FL, FS, and fineness (i.e., reduction in FM). Conversely, GhABH overexpression in Arabidopsis led to shortened root hairs, thinner cell walls in the stem, and fewer vascular bundles. Transcriptomic analysis of GhABH-VIGS fibers revealed potential genes involved in the GhABH regulatory pathway. Collectively, the findings revealed that GhABH is a crucial regulator that simultaneously regulates FL, FS, and fineness and thus represents a promising target for molecular breeding to improve cotton fiber quality.