FUNCTION OF THE OXIDATIVE BURST IN HYPERSENSITIVE DISEASE RESISTANCE

Microbial elicitors or attempted infection with an avirulent pathogen strain causes the rapid production of reactive oxygen intermediates, R ecent findings indicate that H2O2 from this oxidative burst plays a ce ntral role in the orchestration of the hypersensitive response: (i) as the substrate driving the cross-linking of cell wall structural prote ins to slow microbial ingress prior to the deployment of transcription -dependent defenses and to trap pathogens in cells destined to undergo hypersensitive cell death, (ii) as a local threshold trigger of this programmed death in challenged cells, and (iii) as a diffusible signal for the induction in adjacent cells of genes encoding cellular protec tants such as glutathione S-transferase and glutathione peroxidase, Th ese findings provide the basis for an integrated model for the orchest ration of the localized hypersensitive resistance response to attack b y an avirulent pathogen.