Signatures of Admixture and Genetic Uniqueness in the Autochthonous Greek Black Pig Breed Deduced from Gene Polymorphisms Affecting Domestication-Derived Traits

SIMPLE SUMMARY: Autochthonous pig breeds are important genetic resources, well adapted to local climatic conditions, environments, and traditional production systems, where they are associated with local and niche markets. The Greek Black Pig breed is the only local pig breed recognized in Greece. In this study, we started a population genetic characterization of this breed by analyzing a few gene markers associated with morphological and production traits and that usually differentiate wild boars from domestic breeds. The obtained results showed that, in the past, this breed experienced genetic admixture from two sources, wild boars and cosmopolitan breeds. On the one hand, this situation might raise some concerns for the genetic integrity of this animal genetic resource. On the other hand, this might contribute to within-population genetic variability reducing the problem of inbreeding of the small breed population. In this breed, we also identified a novel allele in the melanocortin 1 receptor (MC1R) gene, resulting in a new hypothesis on the function of the encoded protein in regulating the cascade signals and leading to the production of different pigmentation. This result showed that local untapped breeds can be the reservoir of interesting genetic variants useful to better understanding underlying basic biological functions in mammals. ABSTRACT: The Greek Black Pig (or Greek Pig) is the only recognized autochthonous pig breed raised in Greece, usually in extensive or semi-extensive production systems. According to its name, the characteristic breed coat color is solid black. In this study, with the aim to start a systematic genetic characterization of the Greek Black Pig breed, we investigated polymorphisms in major genes well known to affect exterior and production traits (MC1R, KIT, NR6A1, VRTN and IGF2) and compared these data with population genetic information available in other Mediterranean and Western Balkan pig breeds and wild boars. None of the investigated gene markers were fixed for one allele, suggesting that, in the past, this breed experienced introgression from wild boars and admixture from cosmopolitan pig breeds, enriching the breed genetic pool that should be further investigated to design appropriate conservation genetic strategies. We identified a new MC1R allele, containing two missense mutations already reported in two other independent alleles, but here present in the same haplotype. This allele might be useful to disclose biological information that can lead to better understanding the cascade transmission of signals to produce melanin pigments. This study demonstrated that autochthonous genetic resources can be an interesting reservoir of unexpected genetic variants.