The NB-LRR proteins RGA4 and RGA5 interact functionally and physically to confer disease resistance

EMBO J. 2014 Sep 1;33(17):1941-59. doi: 10.15252/embj.201487923. Epub 2014 Jul 14.

Abstract

Plant resistance proteins of the class of nucleotide-binding and leucine-rich repeat domain proteins (NB-LRRs) are immune sensors which recognize pathogen-derived molecules termed avirulence (AVR) proteins. We show that RGA4 and RGA5, two NB-LRRs from rice, interact functionally and physically to mediate resistance to the fungal pathogen Magnaporthe oryzae and accomplish different functions in AVR recognition. RGA4 triggers an AVR-independent cell death that is repressed in the presence of RGA5 in both rice protoplasts and Nicotiana benthamiana. Upon recognition of the pathogen effector AVR-Pia by direct binding to RGA5, repression is relieved and cell death occurs. RGA4 and RGA5 form homo- and hetero-complexes and interact through their coiled-coil domains. Localization studies in rice protoplast suggest that RGA4 and RGA5 localize to the cytosol. Upon recognition of AVR-Pia, neither RGA4 nor RGA5 is re-localized to the nucleus. These results establish a model for the interaction of hetero-pairs of NB-LRRs in plants: RGA4 mediates cell death activation, while RGA5 acts as a repressor of RGA4 and as an AVR receptor.

Keywords: Magnaporthe oryzae; pathogen recognition; plant immunity; resistance protein; rice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Death
  • Disease Resistance*
  • Magnaporthe / growth & development*
  • Magnaporthe / immunology*
  • Models, Biological
  • Oryza / immunology*
  • Oryza / microbiology*
  • Plant Proteins / immunology*
  • Plant Proteins / metabolism*
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Interaction Mapping
  • Protoplasts / physiology
  • Tobacco / immunology
  • Tobacco / microbiology

Substances

  • Plant Proteins