chitwoodi is an major pest of potato crops in the USA, which
has been recently discovered in Europe. In Washington, USA, M.
chitwoodii has become widespread. Infected potatoes cannot
be sold and 70% of growers now use nematicide fumigants. It is
localised in Europe, but seems to be spreading. Current diagnostics
are not 100% certain, however.
objective is to develop modern diagnostic tests for M.
chitwoodi. The project will survey the potato nematodes
of Europe, looking for quarantine organisms M. chitwoodi
and M. fallax and its close relatives (hapla, arenaria,
javanica, incognita). It will improve diagnostic techniques(classic
and biotech), and produce detailed reports on the situation. Occurrence
of biological races means that characterisation to the species
level is not always sufficient. Host range tests have to be performed
to check which races have been imported into Europe, using the
same hosts that are used in the USA but which are also found in
Europe. Further identification of the variants and/or related
species, found in the Netherlands, needs to be conducted and their
host ranges carefully studied, if effective limitation and control
is to be achieved.
identification and characterisation of M. chitwoodi and
related species is vital, not only for the future success of the
European potato crop but also for the trade in ornamental and
research activity comprises six tasks:
collecting European and American populations;
morphological and cytological studies;
assessment of virulence within Meloidogyne chitwoodi
and related species;
identification of differentials, mainly in the genus Solanum;
isoenzyme typing, 2DE, RAPD-PCR, ITS, mtDNA, satDNA, specific
antibodies and development of diagnostic assays;
preparation of reports and dissemination of results.
A large collection of population is available to all participants.
This includes i) numerous American populations of M. chitwoodi
belonging to the different races and pathotypes described for
their ability to develop on different plant and resistant genotypes
of potato, ii) numerous European populations of M. chitwoodi
and M. fallax found before and during the four years research
contract, iii) numerous populations and clones of others species,
such as M. incognita, M. javanica, M. arenaria, M. hapla, M.
mayaguensis, M. naasi, M. artiella.
Morphological studies did not reveal useful differences between
M. chitwoodi and M. fallax, looking
at the juveniles. Perineal patterns of M. chitwoodi
showed faint specific characters in the shape of the surrounding
ridges, but M. fallax looks exactly like a smaller
M. incognita type.
reproduction was shown to be meiotical, with fertile hybridisation
when male is present, which is generally the case. Thus, high
variability is expected in these two species, compared to the
mitotic species, such as M. incognita.
Differences in virulence and in aggressiveness were found, either
against known genes of resistance, or in different plants belonging
to the Cruciferous family. Some populations of M. chitwoodi
are able to break the resistance, found in some Solanum
genotypes as ex-S. fendleri and ex-S. bulbocastanum.
In these cases, contrary to the case of M. incognita,
all the progeny is virulent. With plants belonging to Cruciferous,
interaction population x genotype is significant, with some of
thee testes populations always appearing more aggressive than
Genes of resistance were detected in S. bulbocastanum, S. hougasii,
S. fendleri, S. stoloniferum, S. chacoense; S. sparsipilum, S.
schenkii. In the cases of S. bulbocastanum, S. hougasii
and S. fendleri, the resistance is monogenic,
with S. fendleri, resistance acting against M. chitwoodi,
and M. fallax does not act against M. hapla.
With S. stoloniferum and S. chacoense, resistance
appears polygenic and some clones of S. chacoense are resistant
only to M. fallax and not to M. chitwoodi.
Numerous tools were obtained, characterising M. chitwoodi
and M. fallax, alone or together, from other species.
Isoenzym patterns, mainly esterase and malatedehydrogenase separate
both species from all others and from each other. Serological
antibodies extracted from specific proteins found by two-dimensional
electrophoresis distinguished both species from the others but
not from each other. The same results were obtained using satDNA.
Specific primers were designed and validated by a common test
made by the different partners, which allows characterisation
of both species between themselves and from others.
All annual reports, apart from the last one, were sent to the
European Commission. Results were presented as full papers, during
international congresses. The main conclusions were freely presented
in February 2000 in Paris to European agents of European Plant
- Centre de Recherches de Rennes
de la Motte au Vicomte
Le Rheu Cedex
+33 2 23 48 51 59
+33 2 23 48 51 50
Institut Francais de Recherche Scientifique pour le Développement
Tel.: +33 4 67 61 71 15
Fax: +33 4 67 61 55 81
The Scottish Crop Research Institute
UK-DD2 5DA Dundee
Tel.: +44 1382 56 27 31
Fax: +44 1382 56 24 26
CPRO - DLO - Centre for Plant Breedingand Reproduction Research
P.O. BOX 16
NL-6700 AA Wageningen
Tel.: +31 317 47 70 16
Fax: +31 317 41 80 94
IPO - DLO - Research Institute for Plant Protection
P.O. BOX 9060
NL-6700 GW Wageningen
Tel.: +31 317 47 61 55
Fax: +31 317 41 01 13