Signal recognition and transduction involved in plant disease resistance

Abstract

Gene-for-gene relationships, in which plant disease resistance involves a single resistance (R) gene in the plant which responds specifically to a single avirulence (avr) gene in the pathogen, have been described in numerous plant-pathogen interactions. R genes encode proteins that appear to be involved in both recognition of the pathogen and in signal transduction. Physical interaction of R gene products and Avr proteins provides an explanation for the molecular basis of some gene-for-gene interactions. Multiple signalling pathways lie downstream of R gene products and lead to the hypersensitive response and activation of specific defence-related genes. Plants use diverse mechanisms to defend themselves from pathogens including the generation of active oxygen species, cell wall strengthening, production of defence-related proteins and localized cell death.