A genome resequencing-based genetic map reveals the recombination landscape of an outbred parasitic nematode in the presence of polyploidy and polyandry

Doyle, S. R. et al. (2018) A genome resequencing-based genetic map reveals the recombination landscape of an outbred parasitic nematode in the presence of polyploidy and polyandry. Genome Biology and Evolution, 10(2), pp. 396-409. (doi: 10.1093/gbe/evx269) (PMID:29267942) (PMCID:PMC5793844)

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The parasitic nematode Haemonchus contortus is an economically and clinically important pathogen of small ruminants, and a model system for understanding the mechanisms and evolution of traits such as anthelmintic resistance. Anthelmintic resistance is widespread and is a major threat to the sustainability of livestock agriculture globally; however, little is known about the genome architecture and parameters such as recombination that will ultimately influence the rate at which resistance may evolve and spread. Here we performed a genetic cross between two divergent strains of H. contortus, and subsequently used whole-genome re-sequencing of a female worm and her brood to identify the distribution of genome-wide variation that characterises these strains. Using a novel bioinformatic approach to identify variants that segregate as expected in a pseudo-testcross, we characterised linkage groups and estimated genetic distances between markers to generate a chromosome-scale F1 genetic map. We exploited this map to reveal the recombination landscape, the first for any parasitic helminth species, demonstrating extensive variation in recombination rate within and between chromosomes. Analyses of these data also revealed the extent of polyandry, whereby at least eight males were found to have contributed to the genetic variation of the progeny analysed. Triploid offspring were also identified, which we hypothesise are the result of nondisjunction during female meiosis or polyspermy. These results expand our knowledge of the genetics of parasitic helminths and the unusual life-history of H. contortus, and enhance ongoing efforts to understand the genetic basis of resistance to the drugs used to control these worms and for related species that infect livestock and humans throughout the world. This study also demonstrates the feasibility of using whole-genome resequencing data to directly construct a genetic map in a single generation cross from a non-inbred non-model organism with a complex lifecycle.

Item Type:Articles
Keywords:F1 genetic map, Haemonchus contortus, ploidy, polyandry, pseudo-testcross, recombination landscape.
Glasgow Author(s) Enlighten ID:Cotton, Professor James and Devaney, Professor Eileen and Mable, Professor Barbara and Britton, Professor Collette and Tait, Professor Andy and Laing, Dr Roz and Maitland, Ms Kirsty
Authors: Doyle, S. R., Laing, R., Bartley, D. J., Britton, C., Chaudhry, U., Gilleard, J. S., Holroyd, N., Mable, B. K., Maitland, K., Morrison, A. A., Tait, A., Tracey, A., Berriman, M., Devaney, E., Cotton, J. A., and Sargison, N. D.
College/School:College of Medical Veterinary and Life Sciences > School of Infection & Immunity
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Genome Biology and Evolution
Publisher:Oxford University Press
ISSN (Online):1759-6653
Published Online:18 December 2017
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Genome Biology and Evolution 10(2):396-409
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
636401The BUG consortium Building Upon the Genome: using H. contortus genomic resources to develop novel interventions to control endemic GI parasitesEileen DevaneyBiotechnology and Biological Sciences Research Council (BBSRC)BB/M003949/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED