1. Introduction
Plants have antagonistic associations with a wide range of parasitic
biotrophic organisms. A common feature of biotrophs is that
they extract their nutrients only from living plant tissues.
Therefore, it is quite conceivable that during evolution these interactions
might have evolved certain common core components
affecting cellular functions such as suppression of plant defence,
cytoskeleton rearrangements, cell-wall reorganisation, membrane
synthesis or metabolite fluxes (Parniske, 2000). Plant parasitic
nematodes predominantly exploit the root as their only source of
nutrients. These microscopic worms may be ectoparasitic spending
their whole life cycle outside the root and feeding from the surface
or deeper tissues, or may be endoparasitic invading the root tissues.
Among endoparasitic nematodes, sedentary nematodes have
a highly evolved association with their hosts and include the most
economically important group of plant-parasitic nematodes worldwide,
the root-knot nematodes (RKNs) Meloidogyne species
(Trudgill and Blok, 2001). Three remarkable features of RKNs are