Zusammenfassungen der Arbeitskreisbeiträge - Die DPG

sugars that were both locally and systemically strongly
enriched after nematode infection is trehalose. A. thaliana
trehalose 6-phosphate synthase genes (AtTPS), which play
a role in catalysing trehalose, were significantly up regulated
in H. schachtii infected plants. On the plant parasitic
nematode (PPN) side, there is only little information about
the TPS genes. Analysis of TPS genes of M. incognita
(MINC) and M. hapla (Mh) showed an over-representation
of TPS in comparison with the TPS from free-living nematodes
(FLN) and animal-parasitic nematodes (APN). We
identified 6 MINC-TPS and their Mh-TPS homologues while
FLN-TPS have typically two TPSs, TPS-1 and TPS-2. TPS
phylogenetic tree, which was formed using the available
nematode TPS showed that there is only one of MINC-TPS
and its M. hapla homologue that clustered with FLN- and
APN-TPS-2. All other MINC- and Mh-TPS clustered in a
separate branch. We conclude that the latter TPS have
evolved in Meloidogyne spp. or generally in PPN species to
fulfil functions related to pathogenicity. The gene that clustered
with TPS-2 might still represent the ancestral TPS
functions in FLN and APN. Furthermore, our analysis
showed that two MINC-TPS have a predicted signal peptide.
Interestingly, these MINC-TPS genes were included under
the PPN specific branch. We expect that further studies on
the PPN-TPS genes can help us gaining more understanding
about evolutionary processes in PPN.
Damage and reproduction potentials of Egyptian
populations of Heterodera avenae on wheat
Mohamed Baklawa 1,2 & Björn Niere 1
1 Julius Kühn Institute, Institute for National and
International Plant Health, Messeweg 11/12,
38401 Braunschweig, Germany;
2 Technical University, Faculty of Life Science,
Braunschweig, Germany,
mohamed.baklawa@jki.bund.de
The cereal cyst nematode Heterodera avenae has been reported
on wheat and other cereals in many countries with
different climatic types throughout the world. Management
of these nematodes based on cultivar resistance is considered
a valuable method for nematode control in cereal
production. Breeding and use of resistance need knowledge
on the virulence spectrum of H. avenae in order to establish
an effective and durable control of these nematode populations.
In Egypt, little is known about the occurrence of
cereal cyst nematode on wheat and no information is available
about the resistance levels in the Egyptian wheat genotypes
to H. avenae. Therefore, this study was carried out to
characterise the virulence of six H. avenae populations (five
J.Plant Dis.Protect. 3/4/2011
��
XXX: XXX 145
Egyptian populations and one German population) based
on their reproduction potentials on different wheat cultivars
and to assess the resistance levels in ten wheat cultivars
(nine Egyptian cultivars, one German cultivar) using five
wheat genotypes from the International Test Assortment
(NordGen, Alnarp, Sweden). On the other hand, the damage
potentials of different H. avenae populations on several
growth parameters of wheat cultivars (shoot dry weight;
root dry weight; spike weight and grain yield) were recorded.
Al Qassaseen and Al Sharq populations showed the
highest reproduction factors (Rf) on wheat cultivars while
the lowest were reordered by Abu Sawyer and Abu Khalifa
populations. Most of the tested wheat cultivars from Egypt
were found to be susceptible to H. avenae populations. All
H. avenae populations suppressed several recorded plant
growth parameters, the highest reduction in grain yield was
recorded by Al Qassaseen and Al Sharq populations on the
wheat variety ‘Troll’ with 40.7 and 44%, respectively.
Pathogenicity to Meloidogyne hapla of ninety fungi isolated
from Meloidogyne spp. egg masses from three regions in
Chile
Caroline Eberlein 1, N. Andrade 2 & L. Böhm 2
1 Julius Kühn Institute, Institute for Plant Protection
in Field Crops and Grassland, Toppheideweg 88,
48161 Münster, Germany;
2 Universidad Austral de Chile, Producción y Sanidad
Vegetal, Independencia 641, 5110566 Valdivia, Chile,
caroline.eberlein@jki.bund.de
Ninety fungi were evaluated in vitro for their pathogenicity
to eggs and juveniles of the root-knot nematode Meloidogyne
hapla. These fungi were isolated from Meloidogyne spp.
egg masses associated to roots from infested plants from
three regions in Chile. Fusarium spp., Paecilomyces spp.,
Acremonium spp., Verticillium spp., and Murogenella spp.,
were the most frequent isolated genera. The egg and juvenile
mortality, as well as the egg hatch rate were determined.
Pathogenicity varied among isolates, being all of
them able to infect healthy eggs and juveniles. Two fungi
that belong to the genera Murogenella, showed an egg
mortality of 100%, while thirty four fungi reached over 80%
egg mortality. Of these thirty four fungi, seven belong to the
genera Fusarium, seven to fungi that only produced chlamydospores,
six to Murogenella, three to Paecilomyces, two
to Verticillium, two to Cladosporium, two to Acremonium,
two to Alternaria, one to Trichocladium, one to Trichoderma,
and one to a non-sporulating fungus. This study provides a
useful step in the selection of a potential biological control
agent for this nematode pest.