Variability of ACOX1 Gene Polymorphisms across Different Horse Breeds with Regard to Selection Pressure

Simple Summary The genetic mechanisms occurring in organisms are shaped by selection pressure. Features that ought to be useful under given conditions leave their marks on the genome in the form of mutations, thereby creating different alleles. In this study, five different horse breeds were examined to find the connection between an individual's lifestyle and the presence of the peroxisomal acyl-coenzyme A oxidase 1 (ACOX1) gene, which is necessary for some metabolic pathways. Results indicated that different ACOX1 gene alleles play various roles in primitive breeds and domesticated horses. This led to the conclusion that the DNA profile can be rated on the basis of adaptation to living conditions, opening the gate for further investigation. The ACOX1 gene encodes peroxisomal acyl-coenzyme A oxidase 1, the first enzyme in the fatty acid beta-oxidation pathway, which could be significant for organisms exposed to long periods of starvation and harsh living conditions. We hypothesized that variations within ACOX1, revealed by RNA Sequencing (RNA-Seq), might be based on adaptation to living conditions and had resulted from selection pressure. There were five different horse breeds used in this study, representing various utility types: Arabian, Thoroughbred, Polish Konik, draft horses, and Hucul. The single-nucleotide polymorphism (SNP) located in the ACOX1 (rs782885985) was used as a marker and was identified using the PCR restriction fragment length polymorphism method (PCR-RFLP). Results indicated extremely different genotype and allele distributions of the ACOX1 gene across breeds. A predominance of the G allele was exhibited in horses that had adapted to difficult environmental conditions, namely, Polish Konik and Huculs, which are considered to be primitive breeds. The prevalence of the T allele in Thoroughbreds indicated that ACOX1 is significant in energy metabolism during flat racing.