Comparative Transcriptome Profile between Iberian Pig Varieties Provides New Insights into Their Distinct Fat Deposition and Fatty Acids Content

Abstract

The high deposition of intramuscular fat and the content of oleic fatty acid are characteristic of the Iberian pig. These two parameters present great variability and are differentiated amongst the varieties that make up the Iberian pig population. Although previous studies generated evidence for causal genes and polymorphisms associated to the adipogenic potential of the Iberian pig, there is little information about how genetic expression influences this trait’s variability. The aim of this study was to analyses the expression profile between two varieties of Iberian pig (Torbiscal and Retinto) and their reciprocal crosses differentiated in their intramuscular fat (IMF) content and fatty acid (FA) composition in the Longissimus thoracis muscle using an RNA-seq approach. Our results corroborate that the Retinto variety is the fattiest amongst all studied varieties as its upregulated genes, such as FABP3 and FABP5, SLC27A1 and VEGFA among others, contribute to increasing adiposity. In its turn, Torbiscal pigs showed an upregulation of genes associated with the inhibition of fat deposition such as ADIPOQ and CPT1A. Further genetic variation analysis in these Iberian varieties showed relevant associations for SNP located within the differentially expressed genes with IMF and FA content. Thus, the differences found in the genetic architecture and the muscle transcriptome of these Iberian varieties might explain the variability in their fat content and composition and hence, their meat quality.

Differences in Muscle Lipogenic Gene Expression, Carcass Traits and Fat Deposition among Three Iberian Pig Strains Finished in Two Different Feeding Systems

“…Clemente et al (2006) and Dieguez (2000) [ 39 , 40 ] studied the genetic origin of the Iberian strains, and several authors [ 14 , 15 , 16 , 41 ] compared fat deposition and lipid metabolism among different strains within the Iberian breed, with some differences in their findings that were not fully coherent. Additionally, differences in the expression of genes related to lipid metabolism have previously been studied comparing pure Iberian vs. Duroc x Iberian crossbreeds [ 23 ], pure Iberian vs. pure Duroc [ 22 ], and among Iberian strains and their crossbreeds [ 24 ]. In the present study, not only genotype, but also feeding system significantly affected fat deposition and fatty acid profiles, as also reported by Daza et al (2007), Martins et al (2015), and Rey et al (2006) [ 4 , 21 , 42 ], as well as the expression of relevant genes involved in muscle lipogenic processes.…”

“…The SCD (stearoyl-CoA desaturase) gene, responsible for the biosynthesis of MUFA, was upregulated in Iberian pigs when compared with pure Duroc pigs [ 22 ], and also when compared with the Duroc x Iberian F1 genotype [ 23 ]. Moreover, when comparing Iberian R and T strains and their diallelic crosses, Villaplana-Velasco et al (2021) [ 24 ] found that the R genotypes had the highest content of PUFA and SFA because the genes related to fatty acid catabolism were downregulated in this genotype.…”

Meta-analysis of genome-wide association studies uncovers shared candidate genes across breeds for pig fatness trait

“…Second, PPARD is recognized as an important gene associated with fat deposition traits in gene and gene expression layers [17,43,44], which was detected in our study in QTL on SSC7 and annotated by all the databases. Third, SLC27A1 was another detected important genes that showed multiple evidence associated with fat deposition [45][46][47]. In addition, we identified seven promising candidate genes, PHLPP1, NUDT3, ILRUN, RELCH, KCNQ5, ITPR3, and U3.…”

Differences in histomorphology and expression of key lipid regulated genes of four adipose tissues from Tibetan pigs

“…FABP4 exists primarily in adipose tissue, which is vital for lipid metabolism in adipocytes ( Falcao-Pires et al, 2012 ). FABP5, a lipid chaperone, regulates fatty acid transport, metabolism, and storage ( Liu et al, 2018 ; Villaplana-Velasco et al, 2021 ; Xing et al, 2021 ). FABPs are candidate genes that regulate porcine fat deposition in many other studies.…”