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

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

Author information

1
INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France CSIRO Plant Industry, Canberra, ACT, Australia.
2
Iwate Biotechnology Research Center, Kitakami Iwate, Japan.
3
Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, Takayama Ikoma, Japan.
4
CSIRO Plant Industry, Canberra, ACT, Australia.
5
INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France.
6
INRA UMR BGPI, Montpellier, France CIRAD UMR BGPI, Montpellier, France thomas.kroj@supagro.inra.fr.

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

PMID:
25024433
PMCID:
PMC4195788
DOI:
10.15252/embj.201487923
[Indexed for MEDLINE]
Free PMC Article

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