Integrated genomic and transcriptomic analysis identifies novel candidate genes affecting carcass backfat thickness...

The carcass backfat thickness (BFT) provides a valuable indication of fat deposition and carcass leanness, which are essential for the determination of carcass grading and pricing. Identifying genetic loci and crucial genes related to BFT using integrated multi-omics methods offers significant contributions to the genetic advancement of pig. In the present study, 418 Chinese Suhuai pigs were slaughtered, and carcass BFT were subsequently measure. We conducted a genome-wide association study (GWAS) based on SNP chip data and imputed whole-genome sequencing data (iWGS), respectively. Significant quantitative trait loci (QTL) correlated with carcass BFT were identified on Sus scrofa chromosome (SSC) 2, SSC4, and SSC14, with the most significant single-nucleotide polymorphisms (SNPs) explaining 6.58 %-9.91 % of the phenotypic variance. Bayesian fine mapping validated two previously reported quantitative trait loci (QTLs), narrowing the most refined confidence interval to 3 kb (SSC2, 37.337-37.340 Mb and SSC4, 75.407-77.006 Mb), while identifying two novel QTLs (SSC14, 137.086-138.863 Mb and SSC4, 95.237-96.894 Mb) associated with carcass BFT. Furthermore, transcriptome analysis identified 322 differentially expressed genes (DEGs) and several critical regulatory pathways related to lipid and energy metabolism, including fatty acid and pyruvate metabolism. The integration of genomic and transcriptomic data identified three pivotal candidate genes, S100A12, XKR4 and PENK, which are typically associated with BFT. Transcriptome-wide association study (TWAS) and Phenome-wide association study (PheWAS) provided further evidence that these three genes were significantly associated with BFT and fatty acid composition. This study uncovers novel insights into the important genes and molecular markers related to carcass BFT in pig.