It is assumed that once
the R proteins recognize, directly or indirectly, the Avr proteins they
activate signaling networks that lead to resistance responses. Although several
components of the signaling network have been identified, the mechanisms by
which the R gene products and the so-far identified signaling components
activate the host plant defense responses are still poorly understood.
The fact that R
proteins share structural similarities suggests that, following recognition of
the pathogen protein, the host plant use the common signal transduction
pathways. This is supported by the fact that responses activated by various R
proteins are similar. Such responses commonly include rapid ion fluxes,
generation of superoxide and nitric oxide, and a hypersensitive response that
includes localized cell death. It is also known that there are several signaling
components that are utilized by more than one R proteins.
Tags
Plant Pathology