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 E-D1 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 E-D1 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 E-D1/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.

Automated summary

In this study, we identified four missense mutations that could affect MC1R protein function for eumelanin synthesis by comparing MC1R gene sequences. Using CRISPR-mediated homologous recombination, we successfully mutated the e allele in Duroc pigs to the dominant E-D1 allele at the MC1R locus, leading to uniform black coat color. The modified pigs carried a heterozygous E-D1/e allele at the MC1R locus and retained the genetic background of Duroc breed. Our work provides a gene editing method for pig coat color manipulation.