TABLE CONTENTS

Uncovering the Parasitic Interaction between Meloiodgyne hapla and
Pasteuria penetrans
Deighton, N. (1), N.J. Glassbrook (1), J.E. Schaff (1), M. Burke (2), C.H. Opperman (2) &
K.G. Davies (3)
(1) Genomic Sciences Laboratory, NC State University, Raleigh, NC 27606; (2) Centre for the Biology of
Nematode Parasitism, NC State University, Raleigh, NC, 27606; (3) Rothamsted Research, Harpenden, Herts.,
UK AL5 2JQ
Pasteuria penetrans is an endospore producing, Gram-positive bacterium that is an obligate
parasite of root-knot nematodes (Meloidogyne spp.), which are themselves obligate parasites
of plants. This bacterium has been associated with nematode suppressive soils and also
shown to have tremendous potential for the biological control of root-knot nematodes.
However, the fastidious nature of the organism and the lack of ability to perform forward
genetic experiments have hindered our ability to make progress on culturing, host range
expansion, and mass production techniques. With the completion of the genome sequences
of both organisms, Pasteuria penetrans (Davies et al, 2008) and Meloidogyne hapla
(Opperman et al, 2008) experiments investigating global gene expression, proteomics and
indeed metabolomics studies of this parasitic interaction have become possible. Here we
describe our experimental approach to studying these difficult organisms and present
preliminary results from our studies.
Interactions between Nematodes and Rhizobia: from Proteomics to Plant
Distribution
Costa, S.R. (1,2), Freitas, H. (1) & Mathesius, U. (2)
(1) Centre for Functional Ecology, University of Coimbra, 3000-345 Coimbra, Portugal; (2) School of
Biochemistry and Molecular Biology, Australian National University, Canberra, ACT 0200, Australia
The establishment of legumes depends on mutualistic interactions with rhizobial bacteria, but
plant performance can be affected by plant-parasitic nematodes (PPN). Previous studies
indicate that PPN may reduce nodule formation and that rhizobial strains can induce plant
resistance against PPN. Nematodes and rhizobia share biochemical pathways of infection and
interact in the rhizosphere, but the outcomes of their interactions for plant performance and
distribution are still not clear. We aim to assess the role of these interactions in the
distribution of legumes in their native and exotic habitats. The model legume Medicago
truncatula and laboratory cultures of the root-knot nematode Meloidogyne javanica and the
rhizobial bacteria Sinorhizobium melioti were used in controlled experiments. The axenically
grown legumes were inoculated with PPN and rhizobia, alone or in combination, at distinct
time lags (0, 1 and 3 days). Root and shoot fresh weight, nodulation and gall formation were
determined after 3 weeks. The nematodes significantly stimulated nodulation and rhizobia
significantly reduced nematode infection (p