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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-076 - The paired NLRs RGA4 and RGA5 from rice form an inactive hetero-complex that blocks resistosome assembly

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Crop resistance genetics and genomics

    Presenting Author(s)

  • FB

    Francois Brunisholz

    INRAE
    MONTPELLIER CEDEX X, Languedoc-Roussillon, France

    • Author(s)

  • LC

    Léo Chillard

    PhD student
    CBS - CNRS
    Montpellier, Languedoc-Roussillon, France

  • DL

    Danming Liu

    CBS - CNRS
    Montpellier, Languedoc-Roussillon, France

  • TR

    Tristan Rollo

    INRAE
    Montpellier, Languedoc-Roussillon, France

  • TK

    Thomas Kroj

    Plant Health Institute of Montpellier
    Montpellier, Languedoc-Roussillon, France

  • ND

    Nathalie Declerck

    Centre de Biologie Structurale, Montpellier, Univ Montpellier, CNRS UMR 5048, INSERM U 1054, Montpellier, France
    Montpellier, Languedoc-Roussillon, France

The rice nucleotide-binding and leucine-rich repeat domain (NLR) proteins RGA4 and RGA5 confer resistance against the blast fungus Magnaporthe oryzae by detecting its effectors AVR-Pia and AVR1-CO39. RGA4 acts by activating immunity, while RGA5 senses the effectors by direct binding and, in their absence, suppresses the activity of RGA4. Based on the hypothesis that RGA4 and RGA5 form hetero-complexes in the repressed state and that RGA4 forms a multimeric resistosome upon activation, we built three-dimensional models of RGA4/RGA5 hetero complexes and of RGA4 homo multimers using Alpha Fold (AF) and other in silico approaches. These models highlight a critical role of the CC domain in the formation of the homo and hetero complexes and suggest that in the repressed complex RGA5 blocks RGA4 surfaces critical for resistosome formation. To test these models, we designed mutants of both NLRs with substitutions or deletions in the predicted binding surfaces for analysis in Nicotiana benthamiana cell death assays, co-immunoprecipitation experiments and Gal4-Ruby in-planta two hybrid assays as well as interaction assays with isolated domains. First results confirm the AF models and indicate that RGA5 inhibits RGA4 by the formation of inactive hetero-dimers where surfaces critical for resistosome assembly are inaccessible.