Researchers at the Max Planck Institute for Plant Breeding Research (MPIZ), Cologne, report on the role of physical pressure exerted by an invading fungus. This pressure serves as a signal to trigger plant defense responses (PNAS Vol. 95, No 14, 7 July 1998).
Plants serve as food not only for animals and
insects, but also for a variety of microbes. That's why
microbes, such as bacteria, nematodes, and fungi constantly
attack plants. To protect themselves from being devour plants
have developed broad-acting defense mechanisms. To identify
such threats, plants must be able to perceive signals from a
large variety of potential pathogens to trigger this general
"nonhost" resistance. In recent years, a set of
biological signal molecules (referred to as elicitors) from
different pathogens, have been identified and characterized
with respect to the defense responses induced in plant cells.
Basic knowledge of plant-defense mechanisms can help to
improve crop plants so that they will be better protected
against pathogens.
Scientists in the MPIZ Department of Biochemistry, headed by
Klaus Hahlbrock, use cell-suspension cultures of parsley
(Petroselinum crispum) as a system for studying the nonhost
resistance responses to Phytophthora sojae and Phytophthora
infestans, two important fungal pathogens. Recently,
coworkers of this department purified a glycoprotein from the
mycelium cell wall of P. sojae that was shown to act as an
elicitor in this nonhost system. Incubation of parsley cells
with the elicitor resulted in dramatic biochemical changes in
the affected plant cells, e.g., the generation of reactive
oxygen intermediates (ROI), increased ion fluxes across the
plasma membrane, and changes in gene activity. Researchers
observed the same processes upon infecting parsley cells with
P. infestans.
Contact: Sabine Gus-Mayer, Elmon Schmelzer
gusmayer@mpiz-koeln.mpg.de
49-221-5062-307
Max-Planck-Gesellschaft
14-Jul-1998