Getting to the roots of parasitism by nematodes.

Most phytoparasitic nematodes infect plant roots and some species have evolved sophisticated interactive relationships with host cells to sustain a sedentary parasitic habit. The recent isolation of multiple 'parasitism genes' expressed specifically within the esophageal gland cells of sedentary phytonematodes suggests that an arsenal of different secreted parasitism proteins from the nematode might have direct effects on recipient host cells. These include cell wall modifications and potential interactions with signal transduction receptors in the extracellular space, as well as direct introduction of proteins into host cells that might influence cellular metabolism, the cell cycle, selective protein degradation, a localized defense response and regulatory activity within the host cell nucleus.