QTL fine mapping for intramuscular fat and fatty acid composition using high-density SNP chip array on SSC12 in Korean native pig x Yorkshire F2 population

Intramuscular fat (IMF) and fatty acid composition are characteristics that are used as important indicators of evaluating high quality pork and contribute to the economic benefits of the pig farming industry. In this study, quantitative trait loci (QTL) fine mapping of chromosome 12 was performed in a population of F2 intercross between Yorkshire (YS) and Korean native pigs (KNPs) by adopting combined linkage and linkage disequilibrium method using high-density SNP chips. QTLs for IMF (H3GA0034813 to H3GA0034965) and oleic acid (C18:1) (ASGA0054380 to ALGA0066299) were located at 120 cM (54.112-57.610 kb) and 85 cM (36.097-38.601 kb), respectively, within chromosome 12 (Sscrofa11.1 genomic reference). In addition, 31 candidate genes present within the IMF QTL region and 28 candidate genes existing within C18:1 QTL region were chosen. In order to understand the function of these candidate genes at the molecular level, these candidate genes were functionally categorized by studying gene ontology and analyzing network and pathway. Among the 59 candidate genes within the region of IMF QTL and C18:1 QTL, five (MYH1, MYH2, MYH4, ACACA, and RPS6KB1) directly interacting candidate genes were found. Furthermore, the RPS6KB1 gene was assumed to be an important candidate gene that is involved in leptin and insulin signaling pathway and participates in controlling adipogenic differentiation, fat deposition, and fatty acid composition, which is related to obesity of pigs.