Recognition Specificity and RAR1/SGT1 Dependence in Barley <i>Mla</i> Disease Resistance Genes to the Powdery Mildew Fungus

Shen, Qian‐Hua; Zhou, Fangjian; Bieri, Stéphane; Haizel, Thomas; Shirasu, Ken; Schulze‐Lefert, Paul

doi:10.1105/tpc.009258

Cited by 230 publications

(251 citation statements)

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“…The necrotrophic fungus Botrytis cinerea can manipulate the plant signal transduction pathway via the activation of the EDS1 and SGT1 genes, thus triggering cell death [96]. In A. thaliana, SGT1 (the suppressor of the G2 allele of skp1) seems to affect the regulation of resistance processes that are initiated both by TIR-NBS-LRR proteins such as RPP2 and RPP4, conditioning resistance to P. parasitica, as well as non-TIR-NBS-LRR such as RPP7 and MLA, conditioning the resistance of barley to Blumeria graminis [93,94]. Furthermore, an interaction of SGT1 protein with HSP90 (heat-shock protein 90), which is necessary for the resistance response, was shown.…”

Section: R Proteins-mediated Signaling Pathwaymentioning

confidence: 99%

R proteins as fundamentals of plant innate immunity

Głowacki

Macioszek

Kononowicz

2011

Cellular and Molecular Biology Letters

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Abstract:Plants are attacked by a wide spectrum of pathogens, being the targets of viruses, bacteria, fungi, protozoa, nematodes and insects. Over the course of their evolution, plants have developed numerous defense mechanisms including the chemical and physical barriers that are constitutive elements of plant cell responses locally and/or systemically. However, the modern approach in plant sciences focuses on the evolution and role of plant protein receptors corresponding to specific pathogen effectors. The recognition of an invader's molecules could be in most cases a prerequisite sine qua non for plant survival. Although the predicted three-dimensional structure of plant resistance proteins (R) is based on research on their animal homologs, advanced technologies in molecular biology and bioinformatics tools enable the investigation or prediction of interaction mechanisms for specific receptors with pathogen effectors. Most of the identified R proteins belong to the NBS-LRR family. The presence of other domains (including the TIR domain) apart from NBS and LRR is fundamental for the classification of R proteins into subclasses. Recently discovered additional domains (e.g. WRKY) of R proteins allowed the examination of their localization in plant cells and the role they play in signal transduction during the plant resistance response to biotic stress factors. This review focuses on the current state of knowledge about the NBS-LRR family of plant R proteins: their structure, function and evolution, and the role they play in plant innate immunity.

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Section: R Proteins-mediated Signaling Pathwaymentioning

confidence: 99%

R proteins as fundamentals of plant innate immunity

Głowacki

Macioszek

Kononowicz

2011

Cellular and Molecular Biology Letters

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“…ATP binding appears to be essential for NBS-LRR signaling, because mutations in the NBS domain that block ATP binding also block function (14). The LRR domain is a key determinant of protein-protein interactions (15) and was shown to determine recognition specificity for a number of plant NBS-LRR proteins (16)(17)(18) and thus represents a likely domain for binding pathogen proteins or modified host proteins.…”

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confidence: 99%

Indirect activation of a plant nucleotide binding site–leucine-rich repeat protein by a bacterial protease

Ade

DeYoung

Golstein

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

375

404

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Nucleotide binding site-leucine-rich repeat (NBS-LRR) proteins mediate pathogen recognition in both mammals and plants. The molecular mechanisms by which pathogen molecules activate NBS-LRR proteins are poorly understood. Here we show that RPS5, a NBS-LRR protein from Arabidopsis, is activated by AvrPphB, a bacterial protease, via an indirect mechanism. When transiently expressed in Nicotiana benthamiana leaves, full-length RPS5 protein triggered programmed cell death, but only when coexpressed with AvrPphB and a second Arabidopsis protein, PBS1, which is a specific substrate of AvrPphB. Using coimmunoprecipitation analysis, we found that PBS1 is in a complex with the N-terminal coiled coil (CC) domain of RPS5 before exposure to AvrPphB. Deletion of the RPS5 LRR domain caused RPS5 to constitutively activate programmed cell death, even in the absence of AvrPphB and PBS1, and this activation depended on both the CC and NBS domains. The LRR and CC domains both coimmunoprecipitate with the NBS domain but not with each other. Thus, the LRR domain appears to function in part to inhibit RPS5 signaling, and cleavage of PBS1 by AvrPphB appears to release RPS5 from this inhibition. An amino acid substitution in the NBS site of RPS5 that is known to inhibit ATP binding in other NBS-LRR proteins blocked activation of RPS5, whereas a substitution thought to inhibit ATP hydrolysis constitutively activated RPS5. Combined, these data suggest that ATP versus ADP binding functions as a molecular switch that is flipped by cleavage of PBS1.B oth plants and animals employ nucleotide binding siteleucine-rich repeat (NBS-LRR) proteins to mediate detection of pathogen molecules (1). There appear to be at least two distinct mechanisms by which NBS-LRR proteins detect pathogens: either by binding pathogen-derived molecules directly or by sensing the modification of host proteins by pathogen-derived molecules (2). It is presently unclear how either mechanism causes activation of signaling by NBS-LRR proteins. We have been investigating these processes by using the plant NBS-LRR protein RPS5, which mediates detection of the protease AvrPphB from the bacterial pathogen Pseudomonas syringae (3-6).In plants, NBS-LRR proteins were first identified as the products of classically defined disease-resistance genes (R genes) (7-9), which are genes that confer resistance to infection by specific pathogen strains. R gene-mediated resistance is typically manifested by activation of a programmed cell death response referred to as the hypersensitive response (HR) that is localized to the site of pathogen ingress (10). In the last decade, R genes have been cloned from a large range of plant species, with the majority being found to encode NBS-LRR proteins (11). Plant NBS-LRR proteins can be subdivided into two broad categories defined by the presence of a Toll-interleukin receptor (TIR) domain or a non-TIR domain, most often a coiled-coil (CC) domain, at the amino terminus. The function of the CC and TIR domains in pathogen perception and signaling is un...

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“…Pathogen recognition in barley-Bgh interactions is triggered in a pathogen race-specific manner by genes designated Ml (for Mildew resistance locus; Jørgensen, 1994). Approximately 30 distinct resistance specificities have been identified at the Mla locus; all cloned Mla alleles isolated so far encode coiled-coil, nucleotide-binding site, Leu-rich repeat (CC-NBS-LRR) resistance proteins (Wei et al, 2002;Shen et al, 2003;Halterman and Wise, 2004) that recognize, either directly or indirectly, corresponding fungal effector (AVR) proteins (Ridout et al, 2006). Programmed cell death mediated by MLA proteins occurs after fungal penetration, when primordial haustoria are presumed to secrete AVR a proteins.…”

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confidence: 99%

Blufensin1Negatively Impacts Basal Defense in Response to Barley Powdery Mildew

2008

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Plants have evolved complex regulatory mechanisms to control the defense response against microbial attack. Both temporal and spatial gene expression are tightly regulated in response to pathogen ingress, modulating both positive and negative control of defense. BLUFENSIN1 (BLN1), a small peptide belonging to a novel family of proteins in barley (Hordeum vulgare), is highly induced by attack from the obligate biotrophic fungus Blumeria graminis f. sp. hordei (Bgh), casual agent of powdery mildew disease. Computational interrogation of the Bln1 gene family determined that members reside solely in the BEP clade of the Poaceae family, specifically, barley, rice (Oryza sativa), and wheat (Triticum aestivum). Barley stripe mosaic virus-induced gene silencing of Bln1 enhanced plant resistance in compatible interactions, regardless of the presence or absence of functional Mla coiled-coil, nucleotide-binding site, Leu-rich repeat alleles, indicating that BLN1 can function in an R-gene-independent manner. Likewise, transient overexpression of Bln1 significantly increased accessibility toward virulent Bgh. Moreover, silencing in plants harboring the Mlo susceptibility factor decreased accessibility to Bgh, suggesting that BLN1 functions in parallel with or upstream of MLO to modulate penetration resistance. Collectively, these data suggest that the grass-specific Bln1 negatively impacts basal defense against Bgh.

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Recognition Specificity and RAR1/SGT1 Dependence in Barley Mla Disease Resistance Genes to the Powdery Mildew Fungus

Cited by 230 publications

References 50 publications

R proteins as fundamentals of plant innate immunity

R proteins as fundamentals of plant innate immunity

Indirect activation of a plant nucleotide binding site–leucine-rich repeat protein by a bacterial protease

Blufensin1Negatively Impacts Basal Defense in Response to Barley Powdery Mildew

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