Pig Coat Color Manipulation by MC1R Gene Editing.

Black coat color in pigs is determined by the dominant E allele at the MC1R locus. Through comparing MC1R gene sequences between recessive e and dominant ED1 alleles, we identified four missense mutations that could affect MC1R protein function for eumelanin synthesis. With the aim of devising a genetic modification method for pig coat color manipulation, we mutated the e allele in the Duroc breed to the dominant ED1 allele using CRISPR-mediated homologous recombination for the four mutation substitutions at the MC1R locus. The MC1R-modified Duroc pigs generated using the allele replacement strategy displayed uniform black coat color across the body. A genotyping assay showed that the MC1R-modified Duroc pigs had a heterozygous ED1/e allele at the MC1R locus; in addition, the pigs remained in the Duroc genetic background. Our work offers a gene editing method for pig coat color manipulation, which could value the culture of new pig varieties meeting the needs of diversified market.