Extreme Resistance as a Host Counter-counter Defense against Viral Suppression of RNA Silencing

PLoS Pathogens

Mathieu Langlois¹  Raphaël Sansregret¹  Vanessa Dufour¹  Kamal Bouarab²  Fouad Daayf³  Olivier Voinnet⁴  Patrice Dunoyer⁴ 

[1] Centre SEVE, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;Department of Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland;Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada;Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg, France

关键词: Genetically modified plants;    Leaves;    Small interfering RNAs;    Nicotiana;    Antimicrobial resistance;    RNA interference;    Agrobacterium tumefaciens;    Plant viral pathogens;   

DOI  :  10.1371/journal.ppat.1003435

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

RNA silencing mediated by small RNAs (sRNAs) is a conserved regulatory process with key antiviral and antimicrobial roles in eukaryotes. A widespread counter-defensive strategy of viruses against RNA silencing is to deploy viral suppressors of RNA silencing (VSRs), epitomized by the P19 protein of tombusviruses, which sequesters sRNAs and compromises their downstream action. Here, we provide evidence that specific Nicotiana species are able to sense and, in turn, antagonize the effects of P19 by activating a highly potent immune response that protects tissues against Tomato bushy stunt virus infection. This immunity is salicylate- and ethylene-dependent, and occurs without microscopic cell death, providing an example of “extreme resistance” (ER). We show that the capacity of P19 to bind sRNA, which is mandatory for its VSR function, is also necessary to induce ER, and that effects downstream of P19-sRNA complex formation are the likely determinants of the induced resistance. Accordingly, VSRs unrelated to P19 that also bind sRNA compromise the onset of P19-elicited defense, but do not alter a resistance phenotype conferred by a viral protein without VSR activity. These results show that plants have evolved specific responses against the damages incurred by VSRs to the cellular silencing machinery, a likely necessary step in the never-ending molecular arms race opposing pathogens to their hosts.

【 授权许可】

CC BY