Analysis of pooled genome sequences from Djallonke and Sahelian sheep of Ghana reveals co-localisation of regions of reduced heterozygosity with candidate genes for disease resistance and adaptation to a tropical environment

Abstract

BackgroundThe Djallonke sheep is well adapted to harsh environmental conditions, and is relatively resistant to Haemonchosis and resilient to animal trypanosomiasis. The larger Sahelian sheep, which cohabit the same region, is less well adapted to these disease challenges. Haemonchosis and Trypanosomiasis collectively cost the worldwide animal industry billions of dollars in production losses annually.ResultsHere, we separately sequenced and then pooled according to breed the genomes from five unrelated individuals from each of the Djallonke and Sahelian sheep breeds (sourced from Ghana), at greater than 22-fold combined coverage for each breed. A total of approximately 404 million (97%) and 343 million (97%) sequence reads from the Djallonke and Sahelian breeds respectively, were successfully mapped to the sheep reference genome Oar v3.1. We identified approximately 11.1 million and 10.9 million single nucleotide polymorphisms (SNPs) in the Djallonke and Sahelian breeds, with approximately 15 and 16% respectively of these not previously reported in sheep. Multiple regions of reduced heterozygosity were also found; 70 co-localised within genomic regions harbouring genes that mediate disease resistance, immune response and adaptation in sheep or cattle. Thirty- three of the regions of reduced heterozygosity co-localised with previously reported genes for resistance to haemonchosis and trypanosomiasis.ConclusionsOur analyses suggest that these regions of reduced heterozygosity may be signatures of selection for these economically important diseases.

Signatures of selection reveal candidate genes involved in economic traits and cold acclimation in five Swedish cattle breeds

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Effect of LPS and LTA stimulation on the expression of TLR-pathway genes in PBMCs of Akkaraman lambs in vivo

“…Therefore, it was concluded that the responses of different breeds to the pathogen agent may be different and more studies are needed in the development of breed resistance against diseases (Hadfield et al 2018). In genome sequence analysis of Djallonke and Sahelian sheep resistance to diseases and adaptation to the environment, it was reported that detection of heterozygous diminishing the regions related to these characters may be a sign for selection of economically important diseases (Yaro et al 2019). In our study, it was thought that this study on Akkaraman sheep should be compared in different breeds to determine susceptibility or resistance to different diseases.…”

Genomic scan of selective sweeps in Djallonké (West African Dwarf) sheep shed light on adaptation to harsh environments

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