Fuente: PubMed "smart farming" Genet Sel Evol. 2026 Jul 12. doi: 10.1186/s12711-026-01067-4. Online ahead of print.ABSTRACTBACKGROUND: Chicken skin colour is an economically important trait influenced by consumer preferences across different markets. Previous studies established that white skin is dominant over yellow skin, with the β, β-carotene-9',10'-dioxygenase (BCO2) identified as the candidate gene. However, the precise causal mutation within this gene region has remained unidentified for over a decade, limiting the development of reliable molecular markers for breeding programs.RESULTS: Through genome-wide association analysis of 381 chickens, we confirmed that the BCO2 gene region on chromosome 24 was the major locus associated with skin colour. Transcriptome analysis revealed approximately 590-fold higher BCO2 expression in white-skinned than yellow-skinned chickens. By integrating whole-genome sequencing data from 63 individuals with high-quality genome assemblies, we identified a 24-bp insertion that showed near-complete co-segregation with the yellow skin phenotype in a backcross family of 180 individuals. Electrophoretic mobility shift assays revealed an insertion-dependent DNA-protein interaction, and DNA pull-down coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) prioritised lymphoid enhancer-binding factor 1 (LEF1) as a leading candidate interactor. Chromatin profiling revealed elevated trimethylation of histone H3 at lysine 27 (H3K27me3) and reduced chromatin accessibility at the gene locus in yellow-skinned chickens. Functional experiments revealed that knockdown of LEF1 or inhibition of enhancer of zeste homologue 2 (EZH2) significantly increased BCO2 expression, supporting a model in which the insertion is associated with LEF1/EZH2-sensitive, polycomb repressive complex 2 (PRC2)-linked repression and transcriptional silencing.CONCLUSION: The 24-bp insertion in the BCO2 regulatory region is a candidate causal variant for yellow skin in chickens, refining the genetic model of chicken skin colour variation and supporting a LEF1-PRC2-associated regulatory mechanism potentially involved in avian carotenoid metabolism. This finding enables the development of a reliable PCR-based diagnostic marker for skin colour, facilitating marker-assisted selection in poultry breeding and providing new insights into the genetic regulation of avian pigmentation.PMID:42437876 | DOI:10.1186/s12711-026-01067-4