TABLE CONTENTS

developed agricultural systems. The morphological and physiological variation of Nacobbus
spp. populations along its geographical distribution range have been studied using
morphometrics, physiological (i.e. response to a set of differential plants) and molecular
approaches in order to identify species, ‘groups’ or races of the nematode. However, little
attention has been paid to Nacobbus spp. biogeography, biology, host-nematode-environment
relationships, or to explore co-evolution patterns with host plants and crops. To understand
Nacobbus spp. speciation processes and their geographical distribution patterns, it is
necessary to consider geological events, biological traits, and ecological conditions for both
the nematodes and their native hosts as grown in the agro-ecosystems where nematodes have
thrived with and without human interference. In this poster the biogeography for both host
and parasite, and differences in the life cycle of the nematodes in different Solanaceae hosts,
are examined for selected North and South American populations of the species N. aberrans
s.s. and N. bolivians.
Investigation of a Model System to Develop Controls for Plant-parasitic
Nematodes
Paeper, C.S. (1), S.C. Trowell (2), U. Mathesius (1) & C.A. Behm (1)
(1) The School of Biochemistry and Molecular Biology, The Australian National University, Canberra,
Australia; (2) CSIRO Entomology, Canberra, Australia
Plant-parasitic nematodes infect vast numbers of economically important crop plants causing
severe ecological and economic losses worldwide costing a minimum of US$125 billion
(2003) annually. Broad-acre control measures such as soil treatment or use of resistant
cultivars are limited and increasingly ineffective. Other agronomic practices, such as annual
crop rotation, are of limited utility. Thus, new options must be explored in order to regulate
plant-parasitic nematode populations and reduce the ecological damage and economic losses.
As plant-parasitic nematodes have a slow-life cycle (1-3 months) and are obligate parasites,
functional investigation in the laboratory is difficult. In this study, we are evaluating a model
system for controlling parasitic nematodes using RNA interference (RNAi) technology. The
model system comprises the fungal feeding nematode Aphelenchus avenae and Botrytis
cinerea. This approach will mimic the biology of plant-parasitic nematodes and potentially
allow for a quick turnover of experiments, thus allowing us to identify and validate effective
nematode-specific target genes.
We identified 48 potential nematode-specific target genes by combining a database screen of
reported C. elegans RNAi phenotypes and comparing nematode genomic and EST databases
with those of plants and other non-target species. We have demonstrated that A. avenae
ingests material directly from solution, as shown by FITC uptake, and that in vitro silencing
of the gene rpt-3 by dsRNA appears to reduce sensitivity to the acetylcholinesterase inhibitor
aldicarb. B. cinerea has successfully been transformed with a GFP-expression construct and
cloning strategies for an RNAi construct have been devised.
5 th International Congress of Nematology, 2008 206