Investigation of Hanwoo-specific structural variations using whole-genome sequencing data

Abstract

Background

The total length of the cattle genome is approximately ~ 3 billion base pairs. About half of the bovine genome (46.5%) is composed of transposable elements (TEs). The TEs could be a major source of genomic structural variations (SVs) between cattle breeds. These SVs have led to genomic fluidity and rearrangements between interspecies.

Objective

TE-mediated insertion and deletion events could have a strong influence on the bovine genome. This study aimed to investigate TE-mediated deletion events that are common to 12 Hanwoo genome resequencing data.

Results

We compared 12 Hanwoo genome resequencing data with the cattle reference genome (Bos taurus_UMD_3.1.1) and six other open source data (2 Jersey, 2 Holstein, 2 Angus). By using BreakDancer program, the common SVs to the 12 Hanwoo genomes were detected. A total of 299 Hanwoo-specific SV candidates were detected. Among them, 56 Hanwoo-specific TE-mediated deletion candidate loci were validated by PCR and Sanger sequencing. Finally, we identified one locus, DEL_96, which is an authentic Hanwoo-specific deletion. The DEL_96 event occurred by nonallelic homologous end-joining between LINE (BovB) and unique sequence with 1 bp microhomology. The 370 bp deletion event appeared to be only in the Hanwoo individuals after the divergence of Hanwoo and Holstein lineages.

Conclusion

Our study showed that one of the SVs, TE-mediated deletion, could be utilized as a molecular maker to distinguish between Hanwoo and Holstein.

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