title: Evolution of plant parasitism in the phylum Nematoda.
abstract: Within the species-rich and trophically diverse phylum Nematoda, at least four independent major lineages of plant parasites have evolved, and in at least one of these major lineages plant parasitism arose independently multiple times. Ribosomal DNA data, sequence information from nematode-produced, plant cell wall-modifying enzymes, and the morphology and origin of the style(t), a protrusible piercing device used to penetrate the plant cell wall, all suggest that facultative and obligate plant parasites originate from fungivorous ancestors. Data on the nature and diversification of plant cell wall-modifying enzymes point at multiple horizontal gene transfer events from soil bacteria to bacterivorous nematodes resulting in several distinct lineages of fungal or oomycete-feeding nematodes. Ribosomal DNA frameworks with sequence data from more than 2,700 nematode taxa combined with detailed morphological information allow for explicit hypotheses on the origin of agronomically important plant parasites, such as root-knot, cyst, and lesion nematodes.
authors.affiliation: Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands; email: hans.helder@wur.nl , casper.quist@wur.nl , geert.smant@wur.nl.
authors.forename: Casper W
authors.initials: CW
authors.lastname: Quist
authors.forename: Geert
authors.initials: G
authors.lastname: Smant
authors.forename: Johannes
authors.initials: J
authors.lastname: Helder
mesh_terms: D000818:Animals; D005075:Biological Evolution; D018556:Crops, Agricultural / Q000469:parasitology; D004275:DNA, Ribosomal / Q000235:genetics; D015801:Helminth Proteins / Q000235:genetics; D009348:Nematoda / Q000145:classification / Q000235:genetics / Q000502:physiology*; D010944:Plants / Q000469:parasitology*; D017422:Sequence Analysis, DNA
chemical_list: D004275:DNA, Ribosomal; D015801:Helminth Proteins
keywords: Bursaphelenchus; Longidoridae; Meloidogyne; Pratylenchus; Trichodoridae; Tylenchida; convergent evolution; horizontal gene transfer; phylogeny; ribosomal DNA; trophic ecology