RAR1 Positively Controls Steady State Levels of Barley MLA Resistance Proteins and Enables Sufficient MLA6 Accumulation for Effective Resistance

Bieri, Stéphane; Mauch, Stefan; Shen, Qian‐Hua; Peart, Jack R.; Devoto, Alessandra; Casais, Catarina; Ceron, Francesca; Schulze, Sabine; Steinbiß, Hans‐Henning; Shirasu, Ken; Schulze‐Lefert, Paul

doi:10.1105/tpc.104.026682

Cited by 256 publications

(271 citation statements)

References 59 publications

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“…Consistent with this, reduction of both RAR1 and SGT1 levels results in additive susceptibility for some R proteins (Austin et al, 2002;Azevedo et al, 2002). Thus, while the RAR1-SGT1 interaction is not required for resistance triggered by some R proteins (Figure 4) (Bieri et al, 2004), the SGT1-HSP90 interaction is essential ( Figure 5) (Peart et al, 2002). In the presence of RAR1, the CS domain of SGT1 can simultaneously associate with HSP90-NTD and the CHORD II domain of RAR1 (Figures 6 and 9B).…”

Section: Rar1 Functions To Enhance the Hsp90-sgt1 Interactionsupporting

confidence: 61%

“…This interaction should occur between the CS domain and HSP90-NTD. In rar1 mutants, R protein levels are reduced, but not completely (Tornero et al, 2002;Bieri et al, 2004;Holt et al, 2005). Thus, in the absence of RAR1, R proteins can accumulate as a consequence of the HSP90-SGT1 interaction (Azevedo et al, 2006).…”

Section: Rar1 Functions To Enhance the Hsp90-sgt1 Interactionmentioning

confidence: 99%

“…Unlike bE119G, none of the DN mutants in SGSb was able to confer recovery of Rx protein accumulation to wild-type levels (see Supplemental Figure 7 online). The SGS domain is predicted to be the interaction domain for certain LRR proteins, including NBS-LRR proteins Mla1 from barley and human Nod1 (Dubacq et al, 2002;Bieri et al, 2004;da Silva Correia et al, 2007). Thus, we are currently investigating how these SGS mutations affect the formation and/or activation of R protein complexes.…”

Section: Cs and Sgs Domains Are Required For Rx Resistancementioning

confidence: 99%

“…SGT1 and RAR1 are highly conserved eukaryotic proteins that interact with each other, but their precise roles in HSP90 function have remained elusive. Like HSP90, both SGT1 and RAR1 are required for the stabilization of many R proteins (Tornero et al, 2002;Bieri et al, 2004;Azevedo et al, 2006). Similarly, both HSP90 and SGT1 are required for the stabilization and assembly of the yeast CBF3 (for centromere binding factor3) and the human kinetochore complexes (Bansal et al, 2004;Lingelbach and Kaplan, 2004;Steensgaard et al, 2004;Niikura et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Structural and Functional Analysis of SGT1 Reveals That Its Interaction with HSP90 Is Required for the Accumulation of Rx, an R Protein Involved in Plant Immunity

et al. 2007

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SGT1 (for suppressor of G2 allele of skp1) and RAR1 (for required for Mla12 resistance) are highly conserved eukaryotic proteins that interact with the molecular chaperone HSP90 (for heat shock protein90). In plants, SGT1, RAR1, and HSP90 are essential for disease resistance triggered by a number of resistance (R) proteins. Here, we present structural and functional characterization of plant SGT1 proteins. Random mutagenesis of Arabidopsis thaliana SGT1b revealed that its CS (for CHORD-SGT1) and SGS (for SGT1 specific) domains are essential for disease resistance. NMR-based interaction surface mapping and mutational analyses of the CS domain showed that the CHORD II domain of RAR1 and the N-terminal domain of HSP90 interact with opposite sides of the CS domain. Functional analysis of the CS mutations indicated that the interaction between SGT1 and HSP90 is required for the accumulation of Rx, a potato (Solanum tuberosum) R protein.Biochemical reconstitution experiments suggest that RAR1 may function to enhance the SGT1-HSP90 interaction by promoting ternary complex formation.

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Section: Rar1 Functions To Enhance the Hsp90-sgt1 Interactionsupporting

confidence: 61%

Section: Rar1 Functions To Enhance the Hsp90-sgt1 Interactionmentioning

confidence: 99%

Section: Cs and Sgs Domains Are Required For Rx Resistancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and Functional Analysis of SGT1 Reveals That Its Interaction with HSP90 Is Required for the Accumulation of Rx, an R Protein Involved in Plant Immunity

et al. 2007

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“…That is, when destabilized in rar1 mutant background, RAR1-independent proteins like Pi5 might accumulate at relatively high steady-state levels that are above the threshold required for efficient defense responses (Bieri et al, 2004). In contrast, RAR1-dependent proteins like Pib might be present at relatively lower levels than this critical threshold in rar1 mutants.…”

Section: Discussionmentioning

confidence: 99%

Differential Requirement of Oryza sativa RAR1 in Immune Receptor-Mediated Resistance of Rice to Magnaporthe oryzae

Song

Kim

Han

et al. 2013

Molecules and Cells

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The required for Mla12 resistance (RAR1) protein is essential for the plant immune response. In rice, a model monocot species, the function of Oryza sativa RAR1 (OsRAR1) has been little explored. In our current study, we characterized the response of a rice osrar1 T-DNA insertion mutant to infection by Magnaporthe oryzae, the causal agent of rice blast disease. osrar1 mutants displayed reduced resistance compared with wild type rice when inoculated with the normally virulent M. oryzae isolate PO6-6, indicating that OsRAR1 is required for an immune response to this pathogen. We also investigated the function of Os-RAR1 in the resistance mechanism mediated by the immune receptor genes Pib and Pi5 that encode nucleotide binding-leucine rich repeat (NB-LRR) proteins. We inoculated progeny from Pib/osrar1 and Pi5/osrar1 heterozygous plants with the avirulent M. oryzae isolates, race 007 and PO6-6, respectively. We found that only Pib-mediated resistance was compromised by the osrar1 mutation and that the introduction of the OsRAR1 cDNA into Pib/osrar1 rescued Pib-mediated resistance. These results indicate that OsRAR1 is required for Pib-mediated resistance but not Pi5-mediated resistance to M. oryzae.

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Powdery Mildews

Ridout

2009

Encyclopedia of Life Sciences

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Powdery mildews are an important group of parasitic fungi causing disease in over 7600 species of host plants. They are obligate biotrophic parasites, obtaining their nutrients from the host through intracellular feeding structures known as haustoria. Many species of powdery mildews have a high degree of host specialization, infecting only one or a few closely related host genera. Some powdery mildews have well‐documented gene‐for‐gene (GFG) resistance interactions with their host plant, revealing information about the nature of host specificity. This article focuses on the interactions between powdery mildews and the host plant. Events in the establishment of haustoria and biotrophy are reviewed and their influence of infection on host metabolism described. GFG, durable mlo and nonhost‐resistance mechanisms are also described. Key Concepts Importance of powdery mildews : Powdery mildews are extremely successful fungal parasites. Over 700 species have been described infecting over 7600 species of host plants, many of which are important crops species. Chemicals (fungicides) and resistance genes are used against them, but powdery mildews have the ability to rapidly adapt and defeat these control measures. Obligate biotrophy : All powdery mildews are obligate biotrophs, requiring a living host to grow and reproduce. Haustoria : The feeding structures produced by powdery mildews to obtain nutrients from epidermal cells of the host plants. Host specificity : Many powdery mildews have a high degree of host specialization, and can only grow on one or a few closely related plant genera. Infection can even be restricted to single genotypes of a specific host, as typified by gene‐for‐gene (GFG) resistance. GFG resistance : GFG resistance has been extensively investigated in the interaction between barley powdery mildew ( Blumeria graminis f. sp. hordei ) and the host plant, barley. In GFG resistance, an avirulence ( avr ) gene in the parasite matches a resistance ( R ) gene in the host causing a recognition event that triggers defence responses and prevents infection by the parasite. If either the avr gene or the R gene is lacking, the parasite is not recognized and can become established as a parasite. In barley, over 85 powdery mildew R genes have been described, and over 25 avr gene loci have been mapped in Bgh. mlo resistance : A loss‐of‐function mutation in the barley MLO protein results in failure of Bgh to establish a successful infection. mlo resistance has been widely used in barley breeding, and has so far proved to be durable. Nonhost resistance : Plants are resistant to most invading pathogens, a feature described as nonhost resistance (NHR). Only those adapted microbes that are able to overcome this NHR are able to infect and become pathogens. The extreme specificity of some powdery mildew/host interactions has enabled investigation into the basis of NHR. A series of pen Arabidopsis mutants with enhanced penetration by nonadapted Bgh have been defined. Genes coding for pen1‐pen3 have been identified, enabling key proteins required for NHR to be identified.

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RAR1 Positively Controls Steady State Levels of Barley MLA Resistance Proteins and Enables Sufficient MLA6 Accumulation for Effective Resistance

Cited by 256 publications

References 59 publications

Structural and Functional Analysis of SGT1 Reveals That Its Interaction with HSP90 Is Required for the Accumulation of Rx, an R Protein Involved in Plant Immunity

Structural and Functional Analysis of SGT1 Reveals That Its Interaction with HSP90 Is Required for the Accumulation of Rx, an R Protein Involved in Plant Immunity

Differential Requirement of Oryza sativa RAR1 in Immune Receptor-Mediated Resistance of Rice to Magnaporthe oryzae

Powdery Mildews

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