SUMMARY Some plant endoparasitic nematodes are biotrophic and induce remarkable changes in their hosts in order to ensure a continuous supply of food.
Proteins secreted from oesophageal gland cells have been implicated in this pathogenic process. A potentially secreted
chorismate mutase has been isolated from the potato
cyst nematode Globodera pallida. The gene encoding this
protein is expressed in the subventral oesophageal gland cells of the nematode, and the
mRNA derived from this gene is only present in the early parasitic stages. Sequence analysis of this gene shows that, like other genes involved in the host-parasite interaction of plant parasitic nematodes, it is likely to have been acquired by horizontal gene transfer from bacteria. The presence of a
signal peptide in the deduced amino acid sequence of the G. pallida
chorismate mutase and its expression in the subventral oesophageal gland cells suggest that it is secreted from the nematode, pointing to a role for the
protein in the host-parasite interaction. The
shikimate pathway, of which
chorismate mutase is normally a part, is not found in animals but is present in plants and bacteria. In plants it gives rise to a variety of compounds which are important in
amino acid synthesis and defence signalling pathways, as well as
auxins, which have been implicated in the early development of nematode feeding sites. The potential roles of a nematode
chorismate mutase are discussed.