Red and blond Mangalitza pigs display a signature of divergent directional selection in the SLC45A2 gene

The Mangalitza lard-type pig breed is well known for its fat appearance and curly hair, and it is mainly distributed in Eastern Europe. Four main lines were created in the nineteenth century by artificial selection: Blond Mangalitza, Black Mangalitza, Swallow-Belly Mangalitza and Red Mangalitza. The Swallow-Belly line has a black coat combined with yellow-blond throat and underbelly. In the current work, we aimed to investigate if the colourations of Mangalitza pigs are genetically determined by one or a few loci whose frequencies have been modified by artificial selection. The results of selection scans, with HapFLK and BayeScan, and of a GWAS for coat colour highlighted the existence of one region on SSC16 (18–20 Mb) with potential effects on hair pigmentation (Red vs. Blond contrast). The analysis of the gene content of this region allowed us to detect the solute carrier family 45 member 2 (SLC45A2) locus as a candidate gene for this trait. The polymorphism of the SLC45A2 locus has been associated with reduced levels or the absence of melanin in several mammalian species. The genotyping of four missense polymorphisms evidenced that rs341599992:G > A and rs693695020:G > A SNPs are strongly but not fully associated with the red and blond coat colours of Mangalitza pigs, a result that was confirmed by performing a haplotype association test. The near fixation of alternative SLC45A2 genotypes in Red and Blond Mangalitza pigs provides a compelling example of the consequences of a divergent directional selection for coat colour in a domestic species.
Part of the research presented in this publication was funded by grant AGL2013–48742-C2–1-R awarded by the Spanish Ministry of Economy and Competitivity, and by projects TKISSE and TGENRE supported by the Hungarian Ministry of Agriculture. We also acknowledge the support of the Spanish Ministry of Economy and Competitivity for the Centre of Excellence Severo Ochoa 2016-2019 (SEV-2015-0533) grant awarded to the Centre for Research in Agricultural Genomics. Tainã Figueiredo Cardoso was funded with a fellowship from the CAPES Foundation-Coordination of Improvement of Higher Education, Ministry of Education of the Federal Government of Brazil. Maria Gracia Luigi-Sierra was funded with a fellowship Formación de Personal Investigador (BES-2017-079709) awarded by the Spanish Ministry of Economy and Competitivity. Thanks also to the CERCA Programme of the Generalitat de Catalunya.