Expression of the Pseudomonas syringae avirulence protein AvrB in plant cells alleviates its dependence on the hypersensitive response and pathogenicity (Hrp) secretion system in eliciting genotype-specific hypersensitive cell death.

ABSTRACT Pseudomonas syringae translocates effector proteins into plant cells via an Hrp1 type III secretion system (T3SS). T3SS components HrpB, HrpD, HrpF, and HrpP were shown to be pathway substrates and to contribute to elicitation of the plant hypersensitive response and to translocation and secretion of the model effector AvrPto1.

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Pseudomonas syringae Lytic Transglycosylases Coregulated with the Type III Secretion System Contribute to the Translocation of Effector Proteins into Plant Cells

Journal of Bacteriology ◽

10.1128/jb.00998-07 ◽

2007 ◽

Vol 189 (22) ◽

pp. 8277-8289 ◽

Cited By ~ 50

Author(s):

Hye-Sook Oh ◽

Brian H. Kvitko ◽

Joanne E. Morello ◽

Alan Collmer

Keyword(s):

Pseudomonas Syringae ◽

Hypersensitive Response ◽

Type Iii Secretion ◽

Plant Cells ◽

Type Iii Secretion System ◽

Secretion System ◽

Effector Proteins ◽

Dominant Negative Effect ◽

Lytic Transglycosylases ◽

Type Iii

ABSTRACT Pseudomonas syringae translocates virulence effector proteins into plant cells via a type III secretion system (T3SS) encoded by hrp (for hypersensitive response and pathogenicity) genes. Three genes coregulated with the Hrp T3SS system in P. syringae pv. tomato DC3000 have predicted lytic transglycosylase domains: PSPTO1378 (here designated hrpH), PSPTO2678 (hopP1), and PSPTO852 (hopAJ1). hrpH is located between hrpR and avrE1 in the Hrp pathogenicity island and is carried in the functional cluster of P. syringae pv. syringae 61 hrp genes cloned in cosmid pHIR11. Strong expression of DC3000 hrpH in Escherichia coli inhibits bacterial growth unless the predicted catalytic glutamate at position 148 is mutated. Translocation tests involving C-terminal fusions with a Cya (Bordetella pertussis adenylate cyclase) reporter indicate that HrpH and HopP1, but not HopAJ1, are T3SS substrates. Pseudomonas fluorescens carrying a pHIR11 derivative lacking hrpH is poorly able to translocate effector HopA1, and this deficiency can be restored by HopP1 and HopAJ1, but not by HrpH(E148A) or HrpH1-241. DC3000 mutants lacking hrpH or hrpH, hopP1, and hopAJ1 combined are variously reduced in effector translocation, elicitation of the hypersensitive response, and virulence. However, the mutants are not reduced in secretion of T3SS substrates in culture. When produced in wild-type DC3000, the HrpH(E148A) and HrpH1-241 variants have a dominant-negative effect on the ability of DC3000 to elicit the hypersensitive response in nonhost tobacco and to grow and cause disease in host tomato. The three Hrp-associated lytic transglycosylases in DC3000 appear to have overlapping functions in contributing to T3SS functions during infection.

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Nitric oxide Does Not Trigger Early Programmed Cell Death Events but May Contribute to Cell-to-Cell Signaling Governing Progression of the Arabidopsis Hypersensitive Response

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2003.16.11.962 ◽

2003 ◽

Vol 16 (11) ◽

pp. 962-972 ◽

Cited By ~ 77

Author(s):

Chu Zhang ◽

Kirk J. Czymmek ◽

Allan D. Shapiro

Keyword(s):

Nitric Oxide ◽

Cell Death ◽

Pseudomonas Syringae ◽

Hypersensitive Response ◽

Plasma Membranes ◽

No Production ◽

Post Inoculation ◽

Hypersensitive Cell Death ◽

Synthase Inhibitor ◽

Kinetics Of

Nitric oxide (NO) has been suggested to play a role in the hypersensitive response (HR). Single- and double-label fluorescence microscopy experiments were conducted using Arabidopsis leaves infected with Pseudomonas syringae pv. tomato DC3000 carrying either avrB or avrRpt2. Kinetics of NO production were followed by measurement of green 4-amino-5-methylamino-2′,7′-difluorofluorescein (DAF-FM) triazole fluorescence in leaves coinfiltrated with DAF-FM diacetate. Kinetics of hypersensitive cell death were followed by measurement of cytoplasmic red fluorescence following internalization of coinfiltrated propidium iodide through compromised plasma membranes. Neither NO accumulation nor cell death was seen until approximately 3 h postinoculation of Columbia leaves with DC3000·avrB or approximately 5.5 h post-inoculation with DC3000·avrRpt2. Subsequent NO accumulation kinetics closely paralleled HR progression in both Columbia and ndr1-1 mutant plants. These data established that NO accumulation does not happen sufficiently early for NO to be a signaling component controlling HR triggering. NO accumulation did contribute to the HR, as proven by an approximately 1-h delay in cell death kinetics caused by an NO scavenger or an NO synthase inhibitor. NO was first seen as punctate foci at the cell surface. Subsequent NO accumulation patterns were consistent with NO being an intercellular signal that functions in cell-to-cell spread of the HR.

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Pseudomonas syringae Strains Naturally Lacking the Classical P. syringae hrp/hrc Locus Are Common Leaf Colonizers Equipped with an Atypical Type III Secretion System

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-23-2-0198 ◽

2010 ◽

Vol 23 (2) ◽

pp. 198-210 ◽

Cited By ~ 69

Author(s):

Christopher R. Clarke ◽

Rongman Cai ◽

David J. Studholme ◽

David S. Guttman ◽

Boris A. Vinatzer

Keyword(s):

Pseudomonas Syringae ◽

Type Iii Secretion ◽

Plant Cells ◽

Type Iii Secretion System ◽

Ice Nucleation ◽

Secretion System ◽

Effector Proteins ◽

Population Densities ◽

Type Iii ◽

Effector Genes

Pseudomonas syringae is best known as a plant pathogen that causes disease by translocating immune-suppressing effector proteins into plant cells through a type III secretion system (T3SS). However, P. syringae strains belonging to a newly described phylogenetic subgroup (group 2c) are missing the canonical P. syringae hrp/hrc cluster coding for a T3SS, flanking effector loci, and any close orthologue of known P. syringae effectors. Nonetheless, P. syringae group 2c strains are common leaf colonizers and grow on some tested plant species to population densities higher than those obtained by other P. syringae strains on nonhost species. Moreover, group 2c strains have genes necessary for the production of phytotoxins, have an ice nucleation gene, and, most interestingly, contain a novel hrp/hrc cluster, which is only distantly related to the canonical P. syringae hrp/hrc cluster. This hrp/hrc cluster appears to encode a functional T3SS although the genes hrpK and hrpS, present in the classical P. syringae hrp/hrc cluster, are missing. The genome sequence of a representative group 2c strain also revealed distant orthologues of the P. syringae effector genes avrE1 and hopM1 and the P. aeruginosa effector genes exoU and exoY. A putative life cycle for group 2c P. syringae is discussed.

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The Arabidopsis aberrant growth and death2 mutant shows resistance to Pseudomonas syringae and reveals a role for NPR1 in suppressing hypersensitive cell death

The Plant Journal ◽

10.1046/j.0960-7412.2001.1075umedoc.x ◽

2001 ◽

Vol 27 (3) ◽

pp. 203-211 ◽

Cited By ~ 89

Author(s):

Debra N. Rate ◽

Jean T. Greenberg

Keyword(s):

Cell Death ◽

Pseudomonas Syringae ◽

Hypersensitive Cell Death

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Pectobacterium carotovorum Elicits Plant Cell Death with DspE/F but the P. carotovorum DspE Does Not Suppress Callose or Induce Expression of Plant Genes Early in Plant–Microbe Interactions

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-06-10-0143 ◽

2011 ◽

Vol 24 (7) ◽

pp. 773-786 ◽

Cited By ~ 29

Author(s):

Hye-Sook Kim ◽

Phanit Thammarat ◽

Steven A. Lommel ◽

Clifford S. Hogan ◽

Amy O. Charkowski

Keyword(s):

Gene Expression ◽

Cell Death ◽

Pseudomonas Syringae ◽

Plant Cell ◽

Expression Profiles ◽

Gene Expression Profiles ◽

Secretion System ◽

Broad Host Range ◽

Pectobacterium Carotovorum ◽

Callose Deposition

The broad-host-range bacterial soft rot pathogen Pectobacterium carotovorum causes a DspE/F-dependent plant cell death on Nicotiana benthamiana within 24 h postinoculation (hpi) followed by leaf maceration within 48 hpi. P. carotovorum strains with mutations in type III secretion system (T3SS) regulatory and structural genes, including the dspE/F operon, did not cause hypersensitive response (HR)-like cell death and or leaf maceration. A strain with a mutation in the type II secretion system caused HR-like plant cell death but no maceration. P. carotovorum was unable to impede callose deposition in N. benthamiana leaves, suggesting that P. carotovorum does not suppress this basal immunity function. Within 24 hpi, there was callose deposition along leaf veins and examination showed that the pathogen cells were localized along the veins. To further examine HR-like plant cell death induced by P. carotovorum, gene expression profiles in N. benthamiana leaves inoculated with wild-type and mutant P. carotovorum and Pseudomonas syringae strains were compared. The N. benthamiana gene expression profile of leaves infiltrated with Pectobacterium carotovorum was similar to leaves infiltrated with a Pseudomonas syringae T3SS mutant. These data support a model where Pectobacterium carotovorum uses the T3SS to induce plant cell death in order to promote leaf maceration rather than to suppress plant immunity.

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Inhibition of Rust-induced Hypersensitive Response in Flax Cells by the Microtubule Inhibitor Oryzalin

Functional Plant Biology ◽

10.1071/pp97060 ◽

1997 ◽

Vol 24 (6) ◽

pp. 733 ◽

Cited By ~ 17

Author(s):

Issei Kobayashi ◽

Yuhko Kobayashi ◽

Adrienne R. Hardham

Keyword(s):

Cell Death ◽

Hypersensitive Response ◽

Rust Fungus ◽

Specific Interaction ◽

Differential Sensitivity ◽

Incompatible Interaction ◽

Microtubule Inhibitor ◽

Mesophyll Cells ◽

Hypersensitive Cell Death ◽

Linum Usitatissimum L

Interactions between the flax rust fungus Melampsora lini and flax Linum usitatissimum L. are governed by a gene-for-gene relationship which determines pathogen virulence or avirulence and host resistance or susceptibility. The present study demonstrates differential sensitivity of M. lini and flax to the microtubule depolymerising drug, oryzalin, such that microtubule depolymerisation in flax cells but not in fungal cells could be obtained. Normally, in an incompatible interaction, a rapid hypersensitive response about 24 h after inoculation inhibits fungal development and invasion. However, in an incompatible interaction in the presence of oryzalin, the occurrence of hypersensitive cell death was delayed and its frequency reduced. This allowed a normally avirulent race of M. lini to form haustoria in living host mesophyll cells at a rate and efficiency similar to that achieved by a virulent race in a compatible interaction during the first 36 h after inoculation. After that time, the incidence of hypersensitive cell death increased and further development of the pathogen was arrested. The results indicate that microtubules play a role in effecting rapid and efficient hypersensitive response in the race–cultivar specific interaction between flax and the flax rust fungus.

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Expression of the Hypersensitive Response-assisting Protein in Arabidopsis Results in Harpin-dependent Hypersensitive Cell Death in Response to Erwinia carotovora

Plant Molecular Biology ◽

10.1007/s11103-005-1002-3 ◽

2005 ◽

Vol 59 (5) ◽

pp. 771-780 ◽

Cited By ~ 19

Author(s):

Ajay-Kumar Pandey ◽

Mang-Jye Ger ◽

Hsiang-En Huang ◽

Mei-Kuen Yip ◽

Jiqing Zeng ◽

...

Keyword(s):

Cell Death ◽

Hypersensitive Response ◽

Erwinia Carotovora ◽

Hypersensitive Cell Death

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A Survey of the Pseudomonas syringae pv. tomato DC3000 Type III Secretion System Effector Repertoire Reveals Several Effectors That Are Deleterious When Expressed in Saccharomyces cerevisiae

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-21-4-0490 ◽

2008 ◽

Vol 21 (4) ◽

pp. 490-502 ◽

Cited By ~ 34

Author(s):

Kathy R. Munkvold ◽

Michael E. Martin ◽

Philip A. Bronstein ◽

Alan Collmer

Keyword(s):

Saccharomyces Cerevisiae ◽

Cell Death ◽

Pseudomonas Syringae ◽

Type Iii Secretion ◽

Type Iii Secretion System ◽

Secretion System ◽

Dependent Manner ◽

Tomato Dc3000 ◽

Type Iii ◽

Pathogen Effector

The injection of nearly 30 effector proteins by the type III secretion system underlies the ability of Pseudomonas syringae pv. tomato DC3000 to cause disease in tomato and other host plants. The search for effector functions is complicated by redundancy within the repertoire and by plant resistance (R)-gene sentinels, which may convert effector virulence activities into a monolithic defense response. On the premise that some effectors target universal eukaryotic processes and that yeast (Saccharomyces cerevisiae) lacks R genes, the DC3000 effector repertoire was expressed in yeast. Of 27 effectors tested, HopAD1, HopAO1, HopD1, HopN1, and HopU1 were found to inhibit growth when expressed from a galactose-inducible GAL1 promoter, and HopAA1-1 and HopAM1 were found to cause cell death. Catalytic site mutations affecting the tyrosine phosphatase activity of HopAO1 and the cysteine protease activity of HopN1 prevented these effectors from inhibiting yeast growth. Expression of HopAA1-1, HopAM1, HopAD1, and HopAO1 impaired respiration in yeast, as indicated by tests with ethanol glycerol selective media. HopAA1-1 colocalized with porin to yeast mitochondria and was shown to cause cell death in yeast and plants in a domain-dependent manner. These results support the use of yeast for the study of plant-pathogen effector repertoires.

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