Effects of polymorphisms in the 3' untranslated region of the porcine PPARGC1A gene on muscle fiber characteristics and meat quality traits

Abstract

Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) is a transcriptional coactivator that is involved in a variety of biological processes including muscle fiber type composition. Here, we identified two single nucleotide polymorphisms (SNPs; *2690T > C and *2864T > C) and one insertion/deletion in the 3' untranslated region of porcine PPARGC1A. These SNPs were genotyped by direct sequencing in a total of 439 pigs representing three different pig breeds (Berkshire, n = 156; Yorkshire, n = 163; Landrace, n = 120). We evaluated the effects of diplotypes of individual PPARGC1A 3'UTR SNPs on muscle fiber characteristics and meat quality traits. The *2690T > C polymorphism was significantly associated with the percentage of type I and IIb fibers for both muscle fiber number and area composition (P < 0.05), and also showed a significant association with muscle pH, a parameter of meat quality (P = 0.0188). The *2864T > C polymorphism was also associated with meat quality traits including muscle pH (P = 0.0071), drip loss (P = 0.0006), and lightness (P = 0.0702), but showed no significant association with muscle fiber characteristics. Interestingly, each SNP affected PPARGC1A expression significantly at the protein level but not at the mRNA level, thereby accounting for phenotypic variability among genotypes. Taken together, our data suggest that the *2690T > C and *2864T > C polymorphisms can be used as genetic markers for selection toward improved meat quality.