Analysis of PRKAG3 gene polymorphisms in Italian local pig breeds

he PRKAG3 gene encodes for the regulatory gamma 3 subunit of adenosine monophosfate-activated protein kinase (AMPK) protein that plays a relevant role as regulator of carbohydrate and fat metabolism in mammalian skeletal muscle cells. Several single nucleotide polymorphisms (SNPs) in the porcine PRKAG3 gene have been previously identified. Two missense mutations (c.595A>G and c.599G>A, giving p.I199V and p.R200Q aminoacid substitutions, respectively) were the most studied in different pig breeds and populations and have been associated with meat and carcass traits. Pigs that carry the dominant c.599A allele (p.200Q or allele RN-) have excessive skeletal muscle glycogen content and give the so-called acid meat (also referred to as Hampshire type meat). So far, the p.200Q allele has been identified in Hampshire and Hampshire derived lines. The c.595A>G SNP has been associated with variation of numerous traits including water holding capacity, pH, colour, carcass composition, and several quality traits of dry-cured ham. In this study, we investigated the distribution of the c.595A>G and c.599G>A PRKAG3 SNPs in five Italian local pig breeds: Apulo-Calabrese (64 pigs), Casertana (28), Cinta Senese (77), Mora Romagnola (22) and Nero Siciliano (109). Sampled pigs were from different herds and registered to the Anagraphic Book of the National Pig Breeders Association (ANAS). Genomic DNA was extracted from hair roots or blood and SNP genotyping was performed by PCRRFLP. None of the animals of the Apulo-Calabrese, Casertana, Cinta Senese and Mora Romagnola carried the c.599A (p.200Q) allele. This allele was carried by only 3 Nero Siciliano pigs, suggesting that Hampshire or Hampshire-derived lines could have contributed to shaping Nero Siciliano genetic pool, as in part supported by other studies on coat colour. All breeds were polymorphic at the c.595A>G site. In agreement with studies performed in other breeds, the c.595G (p.Ile199) allele was the less frequent in all analysed local breeds with minor allele frequency >0.10. Based on identified allele frequencies, the c.595A>G SNP can be useful in association studies with meat, carcass and ham quality traits in the Italian local pig breeds.