Meloidogyne chitwoodi is a quarantine pathogen and a severe problem of potato. Intraspecific variation and genetic structure are not well characterised for M. chitwoodi, but are critical to avoid misidentification and to optimise management strategies. The objective of this study was to analyse the morphological and molecular variation of four M. chitwoodi isolates, representing all races and pathotypes currently known in the USA. Despite statistically significant morphological variation among adult females, morphometrics were not able reliably to distinguish M. chitwoodi isolates. In contrast to morphology, molecular traits that are determined by nuclear ribosomal genes were stable across all isolates. Malate dehydrogenase, esterase and superoxide dismutase isozyme phenotypes were conserved in all isolates, which is an important finding for diagnostics. To gain insight into the genetic structure of M. chitwoodi, we analysed a mitochondrial DNA segment including a partial region of COII, tRNA-His and 16S rRNA genes. Genetic structure was weak and marked by high haplotype and low nucleotide diversity. We found a high level of mitochondrial heteroplasmy in M. chitwoodi. Taken together, our results indicate that there is significant intraspecific morphological and molecular variation in M. chitwoodi. Consequences for resistance breeding in potato and directions for phylogeographic studies to trace the origin of M. chitwoodi are discussed.
Molecular diagnostic key for identification of single juveniles of seven common and economically important species of root-knot nematode (Meloidogyne spp.).
Comparison of sequences from the ribosomal DNA intergenic region of Meloidogyne mayaguensis and other major tropical root-knot nematodes.
Journal of Nematology29,
Development and evaluation of potato breeding lines with introgressed resistance to Columbia root-knot nematode (Meloidogyne chitwoodi).
American Journal of Potato Research83,
Independent resistant reactions expressed in root and tuber of potato breeding lines with introgressed resistance to Meloidogyne chitwoodi.
CuevasO.J. (1995). Distribución, rango de hospedantes y determinación de las razas de Meloidogyne chitwoodi Golden, O’Bannon & Finley, 1980 (Nematoda: Meloidogyninae) en el Valle de Huamantla, Tlaxcala. M.S. thesis, Chapingo, Mexico, Universidad Autónoma Chapingo, 89 pp.
Identification and genetic diversity of Meloidogyne chitwoodi in potato production areas of Turkey.
Description and SEM observations of Meloidogyne chitwoodi n. sp. (Meloidogynidae). A root-knot nematode on potato in the Pacific Northwest.
Journal of Nematology12,
Genetic structure of Xiphinema pachtaicum and X. index populations based on mitochondrial DNA variation.
HoltermanM.KarssenG.van den ElsenS.van MegenH.BakkerJ.HelderJ. (2009).
Small subunit rDNA-based phylogeny of the Tylenchida sheds light on relationships among some high-impact plant-parasitic nematodes and the evolution of plant feeding.
Population genetic structure of the sugar beet cyst nematode Heterodera schachtii: a gonochronistic and amphimictic species with highly inbred but weakly differentiated populations.
Molecular genetic classification of central European Meloidogyne chitwoodi and M. fallax populations.
Nachrichtenblatt des Deutschen Pflanzenschutzdienstes50,
MEGA5: Molecular Evolutionary Genetics Analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods.
Molecular Biology and Evolution28,
van der BeekJ.G.MaasP.W.T.H.JanssenG.J.W.ZijlstraC.van SilfhoutC.H. (1999).
A pathotype system to describe intraspecific variation in pathogenicity of Meloidogyne chitwoodi.
Journal of Nematology31,
VillateL.EsmenjaudD.van HeldenM.StoeckelS.PlantardO. (2010).
Genetic signature of amphimixis allows for the detection and fine scale localization of sexual reproduction events in a mainly parthenogenetic nematode.