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Science 338 (6107): 659-662

Copyright © 2012 by the American Association for the Advancement of Science

Tricking the Guard: Exploiting Plant Defense for Disease Susceptibility

J. Lorang,1 T. Kidarsa,1,* C. S. Bradford,1,{dagger} B. Gilbert,1 M. Curtis,1 S.-C. Tzeng,2 C. S. Maier,2 T. J. Wolpert1,{ddagger}

Abstract: Typically, pathogens deploy virulence effectors to disable defense. Plants defeat effectors with resistance proteins that guard effector targets. We found that a pathogen exploits a resistance protein by activating it to confer susceptibility in Arabidopsis. The guard mechanism of plant defense is recapitulated by interactions among victorin (an effector produced by the necrotrophic fungus Cochliobolus victoriae), TRX-h5 (a defense-associated thioredoxin), and LOV1 (an Arabidopsis susceptibility protein). In LOV1’s absence, victorin inhibits TRX-h5, resulting in compromised defense but not disease by C. victoriae. In LOV1’s presence, victorin binding to TRX-h5 activates LOV1 and elicits a resistance-like response that confers disease susceptibility. We propose that victorin is, or mimics, a conventional pathogen virulence effector that was defeated by LOV1 and confers virulence to C. victoriae solely because it incites defense.

1 Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR 97331, USA.
2 Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
* Present address: Horticultural Crops Research Lab, USDA-ARS, Corvallis, OR 97331, USA.
{dagger} Present address: Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA.

{ddagger} To whom correspondence should be addressed. E-mail: wolpertt{at}science.oregonstate.edu


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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PLANT CELL 24, 5177-5192
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