Pratylenchus vulnus Allen & Jensen, 1951
Root Lesion Nematode
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Feeds mainly in cortex; may penetrate xylem, but
rarely the phloem.
The nematode is readily cultured on carrot disks on 1% agar for
detailed study of life cycle and other biological aspects (Moody et al.,
Over 80 hosts, including fruits, nuts, peaches, grapevines,
soybeans and others.
Many hosts are woody perennials.
Males and females are present, P. vulnus is amphimictic. The
haploid chromosome number n=6 (Roman and Triantaphyllou, 1969).
Nematicides: Preplant treatment of
(1,3-D) followed by
2.5 gal/acre DBCP
annually in tree crops was very effective,
however DBCP is no longer available. Postplant treatments with Nemacur
(phenamiphos) can be effective.
Hot water treatments: (5 min at 51.7 C) eradicates
this species from grapevine roots.
Tolerant Rootstocks: Some walnut rootstocks are
reputed to show tolerance. e.g., hybrids of Juglans hindsii
and Juglans regia - cv Paradox.
Experiment by M.V. McKenry
at Kearney Agricultural Center, Parlier, California.
Rootstocks: There is a large rootstock
screening and development program at the USDA Fresno station for
resistance and tolerance to P. vulnus (Dr. Craig
The Paradox diversity study recognizes that Paradox hybrids (J. regia
x J. hindsii hybrids are all genetically different seedlings. Some
may be more resistant or tolerant than others to P. vulnus. The
hybrids are sterile, so if useful rootstocks are found in the project, the
development of vegetative propagation will be critical.
Consider transgenic options with rootstocks:
Mycogen corp. (San Diego) reportedly isolated Bacillus thuringiensis (Bt)
strains effective against
Pratylenchus spp. and later transferred the rights to Monsanto
Corporation. The Bt gene responsible for toxin production effective
against certain insect pests has been transgenically inserted into the genome of
some plants; a similar strategy would probably work against nematodes with the
nematode-effective Bt gene. The toxic crystal molecules coded by the Bt
gene are large; they range in molecular mass from 40 to >70 kDa (Wei et al,
2003). Crystals would need to be ingested by the plant-feeding nematode
and there has been some speculation that stylet-aperture exclusion would be a problem.
However, Meloidogyne incognita, Globodera rostochiensis and
Rotylenchulus reniformis are able to ingest green flourescent protein
molecules of >28 kDa size from plant cells (Goverse et al, 1998; Urwin et al,
1997; Urwin et al, 2000). The size of the Bt crystal is 40-70 kDa and
there is currently no evidence to suggest that crystals of that size would be
excluded by the stylet aperture.
The inability of Heterodera schachtii to
digest proteins >40 kDa has been attributed to the a zone of exclusion
established in the cytoplasm when these nematodes feed in plant cells (Bockenhoff and Grundler,
1994; Urwin, et al, 1997).
Researchers at the University of California
attempted to obtain the nematode-effective Bt gene from Monsanto for development
of transgenic walnut rootstocks.
However, the walnut nursery market was considered too small by industry to
justify costs of development. Research efforts have been focused on large-acreage crops but
the Monsanto Corp. abandoned this
approach for lesion nematodes in cotton in the late 1990s.
Other potential transgenic approaches: Chitinase
genes (only effective against eggs?)- Dr. Gale McGranahan, (Pomology, UC Davis).
Snowdrop lectin - Dr. Dandekar (Pomology, UC Davis)
Studies with trichosanthin (ribosome inhibiting protein).
Host Plant Resistance, Non-hosts
Suggested Alternatives to Methyl Bromide for Replanting
Walnut Orchards Infested with Pratylenchus vulnus
M.V. McKenry - Seminar at UC Davis, 4/26/2004
Bockenhoff, A. and F.M.W. Grundler. 1994. Studies on the nutrient uptake by the
beet cyst nematode Heterodera schachtii by in situ microinjection of fluorescent
probes into the feeding structures in Arabidopsis thaliana. Parasitology,
Goverse, A., et al. 1998. In planta monitoring of the activity of two constitutive
promoters, CaMV 35S and TR2', in developing feeding cells induced by Globodera
rostochiensis using green fluorescent protein in combination with confocal laser
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E.H., Lownsbery, D.F., Ahmed, J.M. 1973. Culture of the root-lesion nematode Pratylenchus vulnus
on carrot disks. J. Nematology 5:225-226.
D.J. 1986 Plant-parasitic nematodes that attack grapes. Pp
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grapes and tobacco. Union Carbide Corp.
Roman, J., Triantaphyllou, A.C. 1969. Gametogenesis oand reproduction of
seven species of Pratylenchus. J. Nematology 1:357-362.
Urwin, P.E., et al. 1997. Continual green-fluorescent protein monitoring of
cauliflower mosaic virus 35S promoter activity in nematode-induced feeding cells
in Arabidopsis thaliana. Mol Plant Microbe Interact, 10:394-400.
Urwin, P.E., et al. 2000. Transgenic resistance to the nematode Rotylenchulus
reniformis conferred by Arabidopsis thaliana plants expressing proteinase
inhibitors. Molecular Breeding, 6:257-264.
Wei, J-Z., K. Hale, L. Carta, E. Platzer, C. Wong, S-C Fang, and R.V. Aroian.
2003. Bacillus thuringiensis crystal proteins that target nematodes. PNAS
Zunke, U. 1990. Ectopic feeding behaviour of the root lesion nematode,
Pratylenchus penetrans, on root hairs of different host plants. Revue