A plant defense response effector induces microbial apoptosis

Osmotin is a tobacco PR-5 protein that has antifungal activity and is impli cated in host-plant defense. We show here that osmotin induces apoptosis in Saccharomyces cerevisiae. Induction of apoptosis was correlated with intra cellular accumulation of reactive oxygen species and was mediated by RAS2, but not RAS1. Osmotin treatment resulted in suppression of transcription of stress-responsive genes via the RAS2/cAMP pathway. It was therefore conclu ded that osmotin induced proapoptotic signaling in yeast. The results indic ate that the ability of antimicrobial proteins to induce microbial apoptosi s could be an important factor in determining a pathogen's virulence and co uld therefore be targeted for the design of new antifungal drugs.