Polymorphism of Keratin Gene KRT71 and Its Relationship with Wool Properties in Gansu Alpine Fine-Wool Sheep

Keratin plays a crucial role in wool formation. Conducting polymorphism studies on key keratin genes is helpful in identifying key SNP sites that might influence wool traits. In this research, kompetitive allele-specific PCR (KASP) genotyping and protein immunofluorescence techniques were used to explore the polymorphisms of the KRT71 gene in Gansu alpine fine-wool sheep, analyze the relationship between the gene polymorphisms and wool production traits, and examine the expression and localization of the KRT71 protein in the hair follicles of fine-wool sheep. The results indicated that there were two single-nucleotide polymorphisms (SNPs) in the 5' UTR and exon 9 of the KRT71 gene, named SNP1 (C.-7G/C) and SNP2 (C.1500G/A), respectively. Regarding SNP1, the mean stable length (MSL) of GG genotype individuals was significantly longer than that of GC genotype individuals (p < 0.05). Similarly, for SNP2, the MSL of GG genotype individuals was significantly greater than that of GA genotype individuals (p < 0.05). Moreover, the KRT71 protein showed moderate positive expression in the cuticle, outer root sheath, and sebaceous gland. It had strong positive expression in the inner root sheath, while no positive expression was detected in the hair medulla and hair papilla. In summary, the sheep KRT71 gene could be an important candidate gene for improvements in wool length.