Novel Genomic Regions Associated with Intramuscular Fatty Acid Composition in Rabbits

[EN] A divergent selection experiment on intramuscular fat (IMF) content was carried out during nine generations in rabbits. The IMF content was successfully improved through generations. Besides, selection for IMF content generated a correlated response on its composition. Association analyses were performed to understand the genetic background of IMF composition using two rabbit lines divergently selected for IMF content. Several genomic regions and genes were identified, revealing the polygenic nature of the intramuscular fatty acid composition in rabbits. Intramuscular fat (IMF) content and its composition affect the quality of meat. Selection for IMF generated a correlated response on its fatty acid composition. The increase of IMF content is associated with an increase of its saturated (SFA) and monounsaturated (MUFA) fatty acids, and consequently a decrease of polyunsaturated fatty acids (PUFA). We carried out a genome wide association study (GWAS) for IMF composition on two rabbit lines divergently selected for IMF content, using a Bayes B procedure. Association analyses were performed using 475 individuals and 90,235 Single Nucleotide Polymorphisms (SNPs). The main objectives were to identify genomic regions associated with the IMF composition and to generate a list of candidate genes. Genomic regions associated with the intramuscular fatty acid composition were spread across different rabbit chromosomes (OCU). An important region at 34.0-37.9 Mb on OCU1 was associated with C14:0, C16:0, SFA, and C18:2n6, explaining 3.5%, 11.2%, 11.3%, and 3.2% of the genomic variance, respectively. Another relevant genomic region was found to be associated at 46.0-48.9 Mb on OCU18, explaining up to 8% of the genomic variance of MUFA/SFA. The associated regions harbor several genes related to lipid metabolism, such as SCD, PLIN2, and ERLIN1. The main genomic regions associated with the fatty acids were not previously associated with IMF content in rabbits. Nonetheless, MTMR2 is the only gene that was associated with both the IMF content and composition in rabbits. Our study highlighted the polygenic nature of the fatty acids in rabbits and elucidated its genetic background. The work was funded by project AGL2014-55921-C2-1-P and AGL2017-86083-C2-P1 from Plan Nacional de Investigacion Cientifica of Spain-Project I+D. B. Samuel Sosa-Madrid was supported by a FPI grant from Ministerio de Ciencia e Innovacion of Spain (BES-2015-074194). Houda Laghouaouta was supported