ORCID Profile
0000-0001-5416-4295
Current Organisation
CNRS Délégation Midi-Pyrénées
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Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-12-2017
Abstract: The fungal pathogen Ug99 (named for its identification in Uganda in 1999) threatens wheat crops worldwide. Ug99 can kill entire fields of wheat and is undeterred by many of the disease-resistance genes that otherwise protect wheat crops. Two papers describe two peptides secreted by the fungus as it attacks the wheat (see the Perspective by Moscou and van Esse). Chen et al. show that fungal AvrSr50 binds to the plant's immune receptor Sr50, and Salcedo et al. show that fungal AvrSr35 binds to Sr35. Successful binding activates the plant's immune defenses. Removing or inactivating these Avr effectors leaves the plant defenseless and susceptible to disease. Science , this issue p. 1607 , p. 1604 see also p. 1541
Publisher: Frontiers Media SA
Date: 25-11-2014
Publisher: Proceedings of the National Academy of Sciences
Date: 03-02-2017
Abstract: Toll/interleukin-1 receptor/resistance protein (TIR) domains are present in plant and animal innate immunity receptors and appear to play a scaffold function in defense signaling. In both systems, self-association of TIR domains is crucial for their function. In plants, the TIR domain is associated with intracellular immunity receptors, known as nucleotide-binding oligomerization domain-like receptors (NLRs). Previous studies from several plant NLRs have identified two distinct interfaces that are required for TIR:TIR dimerization in different NLRs. We show that the two interfaces previously identified are both important for self-association and defense signaling of multiple TIR–NLR proteins. Collectively, this work suggests that there is a common mechanism of TIR domain self-association in signaling across the TIR–NLR class of receptor proteins.
Publisher: Annual Reviews
Date: 04-08-2017
DOI: 10.1146/ANNUREV-PHYTO-080516-035250
Abstract: The first plant disease resistance (R) genes were identified and cloned more than two decades ago. Since then, many more R genes have been identified and characterized in numerous plant pathosystems. Most of these encode members of the large family of intracellular NLRs (NOD-like receptors), which also includes animal immune receptors. New discoveries in this expanding field of research provide new elements for our understanding of plant NLR function. But what do we know about plant NLR function today? Genetic, structural, and functional analyses have uncovered a number of commonalities and differences in pathogen recognition strategies as well as how NLRs are regulated and activate defense signaling, but many unknowns remain. This review gives an update on the latest discoveries and breakthroughs in this field, with an emphasis on structural findings and some comparison to animal NLRs, which can provide additional insights and paradigms in plant NLR function.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Proceedings of the National Academy of Sciences
Date: 24-07-2020
Abstract: Animal NLRs form wheel-like structures called inflammasomes upon perception of pathogen-associated molecules. The induced proximity of the signaling domains at the center of the wheel is hypothesized to recruit caspases for the first step of immune signal transduction. We expressed a plant-animal NLR fusion to demonstrate that induced proximity of TIR signaling domains from plant NLRs is sufficient to activate plant immune signaling. This demonstrates that a signaling-competent inflammasome can be formed from known, minimal components. The intrinsic NADase activity of plant TIRs is necessary for immune signaling, but fusions to a bacterial or a mammalian TIR domain with NADase activity, which also lead to accumulation of NAD + hydrolysis products (e.g. cyclic ADP-ribose), were unable to activate immune signaling.
Publisher: Oxford University Press (OUP)
Date: 08-2008
Abstract: Bacterial wilt, a disease impacting cultivated crops worldwide, is caused by the pathogenic bacterium Ralstonia solanacearum. PopP2 (for Pseudomonas outer protein P2) is an R. solanacearum type III effector that belongs to the YopJ/AvrRxv protein family and interacts with the Arabidopsis thaliana RESISTANT TO RALSTONIA SOLANACEARUM 1-R (RRS1-R) resistance protein. RRS1-R contains the Toll/Interleukin1 receptor–nucleotide binding site–Leu-rich repeat domains found in several cytoplasmic R proteins and a C-terminal WRKY DNA binding domain. In this study, we identified the Arabidopsis Cys protease RESPONSIVE TO DEHYDRATION19 (RD19) as being a PopP2-interacting protein whose expression is induced during infection by R. solanacearum. An Arabidopsis rd19 mutant in an RRS1-R genetic background is compromised in resistance to the bacterium, indicating that RD19 is required for RRS1-R–mediated resistance. RD19 normally localizes in mobile vacuole-associated compartments and, upon coexpression with PopP2, is specifically relocalized to the plant nucleus, where the two proteins physically interact. No direct physical interaction between RRS1-R and RD19 in the presence of PopP2 was detected in the nucleus as determined by Förster resonance energy transfer. We propose that RD19 associates with PopP2 to form a nuclear complex that is required for activation of the RRS1-R–mediated resistance response.
Publisher: International Union of Crystallography (IUCr)
Date: 30-10-2013
Publisher: Wiley
Date: 16-11-2017
DOI: 10.1111/MPP.12597
Publisher: Public Library of Science (PLoS)
Date: 18-11-2010
Publisher: Proceedings of the National Academy of Sciences
Date: 23-08-2016
Abstract: Stem rust caused by the fungus Puccinia graminis f. sp. tritici ( Pgt ) remains the major disease threat to wheat production. The Sr33 and Sr50 resistance proteins protect wheat against a broad spectrum of field isolates of Pgt and are closely related to the barley powdery mildew-resistance protein MLA10. Like MLA10, Sr33 and Sr50 possess signaling N-terminal domains that self-associate in planta and initiate cell-death signaling from the cytosol. However, Sr33 induces disease-resistance signaling from the cytosol but not from the nucleus of wheat cells, suggesting cytosolic activation of both cell death and stem rust resistance.
Publisher: EMBO
Date: 14-07-2014
Abstract: Plant resistance proteins of the class of nucleotide‐binding and leucine‐rich repeat domain proteins ( NB ‐ LRR s) are immune sensors which recognize pathogen‐derived molecules termed avirulence ( AVR ) proteins. We show that RGA 4 and RGA 5, two NB ‐ LRR s from rice, interact functionally and physically to mediate resistance to the fungal pathogen Magnaporthe oryzae and accomplish different functions in AVR recognition. RGA 4 triggers an AVR ‐independent cell death that is repressed in the presence of RGA 5 in both rice protoplasts and Nicotiana benthamiana . Upon recognition of the pathogen effector AVR ‐Pia by direct binding to RGA 5, repression is relieved and cell death occurs. RGA 4 and RGA 5 form homo‐ and hetero‐complexes and interact through their coiled‐coil domains. Localization studies in rice protoplast suggest that RGA 4 and RGA 5 localize to the cytosol. Upon recognition of AVR ‐Pia, neither RGA 4 nor RGA 5 is re‐localized to the nucleus. These results establish a model for the interaction of hetero‐pairs of NB ‐ LRR s in plants: RGA 4 mediates cell death activation, while RGA 5 acts as a repressor of RGA 4 and as an AVR receptor.
Publisher: Wiley
Date: 03-04-2023
DOI: 10.1111/TPJ.16195
Abstract: Recent work shed light on how plant intracellular immune receptors of the nucleotide‐binding leucine‐rich repeat (NLR) family are activated upon pathogen effector recognition to trigger immune responses. Activation of Toll‐interleukin‐1 receptor (TIR) domain‐containing NLRs (TNLs) induces receptor oligomerization and close proximity of the TIR domain, which is required for TIR enzymatic activity. TIR‐catalyzed small signaling molecules bind to EDS1 family heterodimers and subsequently activate downstream helper NLRs, which function as Ca 2+ permeable channel to activate immune responses eventually leading to cell death. Subcellular localization requirements of TNLs and signaling partners are not well understood, although they are required to understand fully the mechanisms underlying NLR early signaling. TNLs show erse subcellular localization while EDS1 shows nucleocytosolic localization. Here, we studied the impact of TIR and EDS1 mislocalization on the signaling activation of different TNLs. In Nicotiana benthamiana , our results suggest that close proximity of TIR domains isolated from flax L6 and Arabidopsis RPS4 and SNC1 TNLs drives signaling activation from different cell compartments. Nevertheless, both Golgi‐membrane anchored L6 and nucleocytosolic RPS4 have the same requirements for EDS1 subcellular localization in Arabidopsis thaliana . By using mislocalized variants of EDS1, we found that autoimmune L6 and RPS4 TIR domain can induce seedling cell death when EDS1 is present in the cytosol. However, when EDS1 is restricted to the nucleus, both induce a stunting phenotype but no cell death. Our data point out the importance of thoroughly investigating the dynamics of TNLs and signaling partners subcellular localization to understand TNL signaling fully.
Publisher: Public Library of Science (PLoS)
Date: 29-11-2012
Publisher: Oxford University Press (OUP)
Date: 2016
DOI: 10.1105/TPC.15.00303
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.SEMCDB.2009.04.010
Abstract: As in nearly every discipline of plant biology, new insights are constantly changing our understanding of plant immunity. It is now clear that plant immunity is controlled by two layers of inducible responses: basal responses triggered by conserved microbial features and specific responses triggered by gene-for-gene recognition of pathogen effector proteins by host resistance (R) proteins. The nucleotide-binding domain leucine-rich repeat (NB-LRR) class of R proteins plays a major role in the combat against a wide range of plant pathogens. The variation that has been generated and is maintained within these conserved proteins has ersified their specificity, subcellular localisations, activation and recognition mechanisms, allowing them to specifically adapt to different plant-pathogen interaction systems. This review addresses recent advances in the molecular role of NB-LRR proteins in pathogen recognition and activation of plant defence responses.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 18-04-2014
Abstract: Certain pathogen effectors are detected in plants by cytoplasmic receptors. First solving the crystal structures of Arabidopsis receptors, Williams et al. (p. 299 see the Perspective by Nishimura and Dangl ) discovered that in the resting state, the structures form a heterodimer that readies the complex for effector binding and keeps the signaling domains from firing too early. Once the pathogen effector binds, the structure of the complex shifts such that the signaling domains can form a homodimer to initiate downstream signaling. Similarities between these plant-pathogen receptors and Toll-like receptors in animals suggest the molecular mechanisms may translate broadly.
Publisher: Elsevier BV
Date: 03-2011
No related grants have been discovered for Maud Bernoux.