Tissue-specific expression, functional analysis, and polymorphism of the KRT2 gene in sheep horn

Horn is a defensive weapon of sheep, consisting of a horny sheath and a bony core. The KRT2 gene is related to keratinization of the epidermis, so it is likely to be one of the contributor genes affecting horn type in sheep. In this study, we first analyzed the species-specific and tissue-specific expression of the KRT2 gene using transcriptome sequencing data. Then, by comparing the protein sequences of 20 species, we identified 28 specific amino acid sites in Artiodactyla animals, constructed a phylogenetic tree of the KRT2 gene, and predicted its three-dimensional protein structure. Finally, whole genome sequencing data was used and mined 4 functional SNP sites of KRT2 gene, and use KASP assay to verify the loci. In addition, we explored the relationship between the KRT2 gene and the evolution of Artiodactyla animals, and predicted the possible mechanism by which the KRT2 gene affects the horn type of sheep.