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Abstract
Mitochondrial DNA (mtDNA) encodes the genes for respiratory chain sub-units that determine the efficiency of oxidative phosphorylation in mitochondria. The aim of this study was to determine if there were any haplogroups and variants in mtDNA that could be associated with athletic performance of Thoroughbred horses. The whole mitochondrial genomes of 53 maternally unrelated Australian Thoroughbred horses were sequenced and an association study was performed with the competition histories of 1123 horses within their maternal lineages. A horse mtDNA phylogenetic tree was constructed based on a total of 195 sequences (including 142 from previous reports). The association analysis showed that the sample groups with poor racing performance history were enriched in haplogroup L3b (p = .0003) and its sub-haplogroup L3b1a (p = .0007), while those that had elite performance appeared to be not significantly associated with haplogroups G2 and L3a1a1a (p > .05). Haplogroup L3b and L3b1a bear two and five specific variants of which variant T1458C (site 345 in 16s rRNA) is the only potential functional variant. Furthermore, secondary reconstruction of 16s RNA showed considerable differences between two types of 16s RNA molecules (with and without T1458C), indicating a potential functional effect. The results suggested that haplogroup L3b, could have a negative association with elite performance. The T1458C mutation harboured in haplogroup L3b could have a functional effect that is related to poor athletic performance.
Acknowledgements
This work was supported by the Key technology of horse speed and endurance performance (Provincial/Municipal level general project, 2012BAD44B01-03), National Natural Science Foundation of China (foundation code: 31271275), Riding Horse and Science (Tianjin Science and Technology Popularization Project, 14KPXM01SY0018) and the Relevance between mtDNA polymorphism and endurance performance of thoroughbred horses (National Natural Science Foundation of China, International/Regional Cooperation Project, 30910241). All funders contributed to the study design, data collection and analysis, and preparation of the manuscript.
Disclosure statement
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.
