Genome-wide re-sequencing reveals regulatory genes and variants involved in the regulation of intermittent fertilization intensity in Wenchang chickens

Intermittent fertilization intensity (IFI) is closely related to higher fertilization in chickens, but the genetic basis of IFI is not clearly understood. Here, we sampled a total of 939 Wenchang chickens with IFI. The IFI traits had negative correlation with the fertilization rate and exhibited huge phenotypic variations among individuals of the same strain. Based on SNPs derived from a subset of 499 whole genome data, a genome-wide association study with mixed linear model and further linkage disequilibrium analysis were performed to test potential associations between IFI traits and genomic variants. We identified 35 SNP variants and a 19.82 kb linkage disequilibrium block on chr8 significantly associated with IFI. This block is in the intron of LOC101750715, which shows significant homology with the human LMO4. Therefore, LOC101750715 and LMO4 may regulate IFI. The oviduct's immune regulation is crucial for fertilization. LMO4, activated by IL-6 and IL-23, promotes inflammation in epithelial cells. Thus, LOC101750715 and LMO4 may affect fertilization by regulating oviductal inflammation, impacting IFI. Our findings will provide targets for molecular-marker selection and genetic manipulation for lines of chickens with lower IFI.