The effects of single and epistatic quantitative trait loci for fatty acid composition in a Meishan x Duroc crossbred population

We performed a whole genome QTL analysis to confirm the existence of QTL affecting fatty acid composition and to investigate the effects of additive, dominance, imprinting, and epistatic interactions between QTL in an F(2) resource population. The F(2) population, comprising 166 pigs, was obtained by crossing a Duroc boar and a Meishan sow. The F(2) population was measured for fatty acid composition and was used for whole genome QTL analysis, using a total of 180 microsatellite markers. The suggestive and significant thresholds were equivalent to likelihood ratio test statistics (LRT) of 13.7 and 20.5, respectively. For single QTL analysis, 2 suggestive QTL and 1 significant QTL were detected. Suggestive QTL for C14:0 and C16:1 were identified on chromosomes 12 and 7, respectively, and a significant QTL for C18:2 was detected on chromosome 5 with the greatest LRT of 22.9. For C14:0, a significant QTL with paternal imprinting effect was also detected on chromosome 12, where the locus was in the same region as an additive QTL effect, with a large LRT of 24.2. The suggestive QTL on chromosome 7 was not significant when correction for backfat thickness was included. For epistatic QTL analysis, a total of 5 epistatic pairs were located on chromosomes 4, 5, 9, and 16. The same epistatic pairs were significant when correction for backfat thickness was included. The individual QTL identified in the single QTL analysis and in the epistatic QTL analysis were not the same loci, except for C18:2. For C14:0, an epistatic QTL pair was detected on chromosome 16, with the least P-value of 4.9 x 10(-12). The present study constitutes one of the first reports on the mapping of imprinted QTL and epistatic pairs of QTL affecting fatty acid composition in a swine population.