Polymorphisms of the 5' regulatory region of the porcine PPARGC1A gene and the effects on muscle fiber characteristics and meat quality

Abstract

The purpose of this study was to determine the structure of the porcine PPARGC1A 5' upstream region, and to find suitable molecular markers for improved meat quality and good lean meat production. Ten DNA polymorphisms, including 7 SNPs, 2 microsatellites, and 1 insertion or deletion were newly found in the 5' upstream region of PPARGC1A. Three SNPs that had restriction enzyme site were evaluated for associations with muscle fiber characteristics and production traits. Two hundred fifty-two pigs (Yorkshire and Landrace) were used in this analysis. The c.-2894G > A genotypes was significantly associated with muscle fiber characteristics, including the number of fiber type I and IIb composition (P < 0.05), mean cross-sectional area of fibers (P < 0.01), and fiber number per unit area (P < 0.05). The animals with the GG genotype had a higher percentage of type I fibers and a lower percentage of type IIb fibers with better meat quality [higher pH value (P < 0.05) and lower drip loss (P < 0.05)] and lean meat production [larger loin eye area (P < 0.05)]. Moreover, the mRNA expression levels of PPARGC1A among genotypes were significantly different with the highest level of GG genotype. The c.-2885G > T and c.-1402A > T sites showed similar results that had significant effects on the mean cross-sectional area (CSA; P < 0.05), fiber number per unit area (P < 0.05) and loin eye area (P < 0.01). Therefore, we suggest that the c.-2894G > A polymorphism in the 5' upstream region of the porcine PPARGC1A gene can be used as a meaningful molecular marker for simultaneous improvement of lean meat production and quality traits.