TABLE CONTENTS

Radopholus similis: Exploring the Transcriptome and RNAi Applications
Jacob, J. (1), A. Haegeman (1), S. Joseph (1), S. Windelinckx (2), S. Remy (2), R. Swennen
(2), M. Mitreva (3), B. Vanholme (1) & G. Gheysen (1)
(1) Department of Molecular Biotechnology, Ghent University, 9000 Ghent Belgium; (2), Laboratory of
Tropical Crop Improvement, Catholic University of Leuven, 3001 Leuven Belgium; (3) Genome Sequencing
Center, Washington University School of Medicine, 4444 Forest Park Boulevard, St. Louis, Missouri, USA
Radopholus similis is an important pest on fruit crops in the tropics, but only few molecular
studies have been performed on this nematode. Unravelling the transcriptome of this
migratory plant-parasitic nematode can provide insight in the parasitic process and lead to
more efficient control measures. A total of 7007 ESTs from a mixed stage population
representing approximately 3200 genes were analysed. The mean G+C content of the
nucleotides at the third codon position was calculated to be as high as 64.8%, the highest for
nematodes reported to date. Remarkably, no evidence was found for the presence of spliced
leader sequences commonly occurring in nematodes, despite the use of various approaches.
Interestingly, tags most likely derived from Wolbachia were found, providing a molecular
indication for the presence of this endosymbiont in R. similis. Several ESTs were found with
significant similarity to nematode mitochondrial genes. An analysis of the mitochondrial
genome of R. similis is in progress.
The parasitic life style of this nematode is reflected in the presence of tags derived from
genes with a putative role in parasitism, such as genes coding for cell wall degrading
enzymes, and proteins involved in detoxification of reactive oxygen species and host
recognition. In addition, several unigenes had homology to parasitism genes with unknown
function of other parasitic nematode species. We have selected endoglucanases and several
housekeeping genes as target for RNAi. In vitro RNAi treatment of R. similis with dsRNA for
an endoglucanase gene resulted in significantly lower infectivity of the nematodes.
Constructs have been made for plant transformation and the generation of transgenic banana
is in progress.
EST Analysis of Bursaphelenchus xylophilus and Functional Analysis of
Parasitism Genes in this Species
Kikuchi, T. (1) & J.T. Jones (2)
(1) Forestry and Forest Products Research Institute, Japan; (2) PPI Programme, Scottish Crop Research Institute,
UK
The pine wood nematode Bursaphelenchus xylophilus is the causal agent of pine wilt which
causes extensive forest death in Japan and East Asia. B. xylophilus has recently been found
for the first time in the EU, in Portugal, and strict controls are in place to prevent spread of
the pathogen. B. xylophilus is also a scientifically interesting pathogen as it has the almost
unique feature of being able to parasitise woody parts of trees. In addition, the lifestyle and
taxonomic position of B. xylophilus offer opportunities for comparative genomics studies
with C. elegans and with other plant parasitic nematodes including cyst and root knot
nematodes. Previous molecular studies on B. xylophilus were, until recently, very limited and
focused mainly on development of tools for diagnostics and detection of the pathogen.
However, the application of expressed sequence tag (EST) analysis has greatly expanded the
5 th International Congress of Nematology, 2008 62