TABLE CONTENTS

Manganese Superoxide Dismutase in Meloidogyne incognita Isolates
Selected for Virulence on Tomato
Molinari, S. (1), L. Rosso (1) & C. Ornat Longaron (2)
(1) Institute of Plant Protection, National Council of Research (C.N.R.), Via G. Amendola 122/D – 70126 Bari,
Italy; (2) Departament d'Enginyeria Agroalimentària i Biotecnologia, Universitat Politecnica de Catalunya,
08860 Castelldefels – Barcelona, Spain
Root knot nematodes (Meloidogyne spp.) are important pests of a wide range of crops,
including tomato. Resistance of tomato to root-knot nematodes is conferred by the single
dominant gene Mi-1, which is present in all commercially available resistant tomato cultivars,
at present. However, several resistance-breaking populations are being collected world-wide.
Two isolates coming from the same standard population of Meloidogyne incognita, one
selected for virulence against Mi-1 and the other left avirulent, have been used in this study.
Manganese superoxide dismutase activity (Mn-SOD) was higher in virulent infective
juveniles compared with avirulent counterparts. m-RNA was extracted from those two
isolates and converted into cDNA. Species-specific primers of Mn-SOD were used for PCR
and one single PCR product was generated from each isolate (EMBL accessions nos.
AM285679 and AM285680). Such products were sequenced and the deduced amino-acid
sequence recognized as a mitochondrial dimeric manganese SOD. The amount of transcripts
was quantified by realtime-PCR. The virulent isolate showed an amount of transcripts 4-fold
higher than that present in the avirulent isolate. The up-regulation of manganese SOD gene,
which was associated with a high activity of the enzyme, has been found to be a characteristic
of pre-parasitic juveniles of M. incognita isolates selected for virulence on tomato.
Expression Analysis of Plant Defensin Genes in Nematode Induced Feeding
Sites
Siddique, S., D. Szakasits, K. Wieczorek, F.M.W. Grundler & H. Bohlmann
Institute of Plant Protection, Department of Applied Plant Sciences and Plant Biotechnology, University of
Natural Resources and Applied Life Sciences, Vienna, Austria.
Arabidopsis thaliana is a host for the sugar beet cyst nematode Heterodera schachtii.
Juvenile nematodes invade the roots and induce the development of a syncytium which
functions as a feeding site for the nematode. Transcriptome analysis of syncytia induced in
the roots of Arabidopsis by Heterodera schachtii was performed with Affymetrix GeneChips
using microaspiration to isolate pure syncytium material. Initial data analysis has shown that
defense gene expression is repressed similar to the results obtained for galls induced by the
root knot nematode Meloidogyne incognita in Arabidopsis roots (Jammes et al., 2005).
However, an exception is the expression of a group of plant defensin genes. Pdf2.2 and
Pdf2.3 were strongly expressed both in control root sections and in syncytia, and Pdf2.1 was
among the most strongly upregulated genes in syncytia. The expression pattern of these genes
in Arabidopsis plants and their response to infection by H. schachtii, H. glycines and M.
incognita has been studied using GUS-lines, in situ RT-PCR and RT-PCR.
5 th International Congress of Nematology, 2008 248