Perception and response in plant disease resistance.

Plants express sophisticated mechanisms for recognizing pathogens. The functionally defined repertoire of non-self perception is large; the number and nature of subsequent molecular events required for resistance is unknown. Recent cloning of disease resistance genes, and genetic identification of loci required for their function, allows dissection of the structure, evolution, and deployment within populations of pathogen-perception mechanisms. Roles for reactive oxygen species and programmed cell death in resistance have also been suggested recently. New results document a role for salicylic acid as a lynchpin in the establishment and maintenance of the 'effector functions' of disease resistance, and strategies for engineered plant protection are moving closer to reality.