1
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Herold L, Choi S, He SY, Zipfel C. The conserved AvrE family of bacterial effectors: functions and targets during pathogenesis. Trends Microbiol 2024:S0966-842X(24)00222-1. [PMID: 39278787 DOI: 10.1016/j.tim.2024.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/22/2024] [Accepted: 08/22/2024] [Indexed: 09/18/2024]
Abstract
The AvrE family of type III secreted effectors are highly conserved among many agriculturally important phytopathogenic bacteria. Despite their critical roles in the pathogenesis of phytopathogenic bacteria, the molecular functions and virulence mechanisms of these effectors have been largely unknown. However, recent studies have identified host-interacting proteins and demonstrated that AvrE family effectors can form water-permeable channels in the plant plasma membrane (PM) to create a hydrated and nutrient-rich extracellular space (apoplast) required for disease establishment. Here, we summarize these recent discoveries and highlight open questions related to AvrE-targeted host proteins.
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Affiliation(s)
- Laura Herold
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sera Choi
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA; Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | - Cyril Zipfel
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland; The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK.
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2
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Kharadi RR, Hsueh BY, Waters CM, Sundin GW. pGpG-signaling regulates virulence and global transcriptomic targets in Erwinia amylovora. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.12.575434. [PMID: 38260453 PMCID: PMC10802605 DOI: 10.1101/2024.01.12.575434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Cyclic-di-GMP (c-di-GMP) is a critical bacterial second messenger that enables the physiological phase transition in Erwinia amylovora, the phytopathogenic bacterium that causes fire blight disease. C-di-GMP generation is dependent on diguanylate cyclase enzymes while the degradation of c-di-GMP can occur through the action of phosphodiesterase (PDE) enzymes that contain an active EAL and/or a HD-GYP domain. The HD-GYP-type PDEs, which are absent in E. amylovora, can directly degrade c-di-GMP into two GMP molecules. PDEs that contain an active EAL domain, as found in all active PDEs in E. amylovora, degrade c-di-GMP into pGpG. The signaling function of pGpG is not fully understood in bacterial systems. A transcriptomic approach revealed that elevated levels of pGpG in E. amylovora impacted several genes involved in metabolic and regulatory functions including several type III secretion and extracellular appendage related genes. The heterologous overexpression of an EAL or HD-GYP-type PDE in different background E. amylovora strains with varying c-di-GMP levels revealed that in contrast to the generation of pGpG, the direct breakdown of c-di-GMP into GMP by the HD-GYP-type PDE led to an elevation in amylovoran production and biofilm formation despite a decrease in c-di-GMP levels. The breakdown of c-di-GMP into pGpG (as opposed to GTP) also led to a decrease in virulence in apple shoots. The expression of hrpS was significantly increased in response to the breakdown of c-di-GMP into pGpG. Further, our model suggests that a balance in the intracellular ratio of pGpG and c-di-GMP is essential for biofilm regulation in E. amylovora.
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Affiliation(s)
- Roshni R. Kharadi
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
| | - Brian Y. Hsueh
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Christopher M. Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - George W. Sundin
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
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3
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water- and solute-permeable channels to plant cells. Nature 2023; 621:586-591. [PMID: 37704725 PMCID: PMC10511319 DOI: 10.1038/s41586-023-06531-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 08/10/2023] [Indexed: 09/15/2023]
Abstract
Many animal- and plant-pathogenic bacteria use a type III secretion system to deliver effector proteins into host cells1,2. Elucidation of how these effector proteins function in host cells is critical for understanding infectious diseases in animals and plants3-5. The widely conserved AvrE-family effectors, including DspE in Erwinia amylovora and AvrE in Pseudomonas syringae, have a central role in the pathogenesis of diverse phytopathogenic bacteria6. These conserved effectors are involved in the induction of 'water soaking' and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in inward and outward currents, permeability to water and osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine dendrimers as inhibitors of the DspE/AvrE channels. Notably, polyamidoamines broadly inhibit AvrE and DspE virulence activities in Xenopus oocytes and during E. amylovora and P. syringae infections. Thus, we have unravelled the biochemical function of a centrally important family of bacterial effectors with broad conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC, USA.
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA.
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA.
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4
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Geraffi N, Gupta P, Wagner N, Barash I, Pupko T, Sessa G. Comparative sequence analysis of pPATH pathogenicity plasmids in Pantoea agglomerans gall-forming bacteria. FRONTIERS IN PLANT SCIENCE 2023; 14:1198160. [PMID: 37583594 PMCID: PMC10425158 DOI: 10.3389/fpls.2023.1198160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/10/2023] [Indexed: 08/17/2023]
Abstract
Acquisition of the pathogenicity plasmid pPATH that encodes a type III secretion system (T3SS) and effectors (T3Es) has likely led to the transition of a non-pathogenic bacterium into the tumorigenic pathogen Pantoea agglomerans. P. agglomerans pv. gypsophilae (Pag) forms galls on gypsophila (Gypsophila paniculata) and triggers immunity on sugar beet (Beta vulgaris), while P. agglomerans pv. betae (Pab) causes galls on both gypsophila and sugar beet. Draft sequences of the Pag and Pab genomes were previously generated using the MiSeq Illumina technology and used to determine partial T3E inventories of Pab and Pag. Here, we fully assembled the Pab and Pag genomes following sequencing with PacBio technology and carried out a comparative sequence analysis of the Pab and Pag pathogenicity plasmids pPATHpag and pPATHpab. Assembly of Pab and Pag genomes revealed a ~4 Mbp chromosome with a 55% GC content, and three and four plasmids in Pab and Pag, respectively. pPATHpag and pPATHpab share 97% identity within a 74% coverage, and a similar GC content (51%); they are ~156 kb and ~131 kb in size and consist of 198 and 155 coding sequences (CDSs), respectively. In both plasmids, we confirmed the presence of highly similar gene clusters encoding a T3SS, as well as auxin and cytokinins biosynthetic enzymes. Three putative novel T3Es were identified in Pab and one in Pag. Among T3SS-associated proteins encoded by Pag and Pab, we identified two novel chaperons of the ShcV and CesT families that are present in both pathovars with high similarity. We also identified insertion sequences (ISs) and transposons (Tns) that may have contributed to the evolution of the two pathovars. These include seven shared IS elements, and three ISs and two transposons unique to Pab. Finally, comparative sequence analysis revealed plasmid regions and CDSs that are present only in pPATHpab or in pPATHpag. The high similarity and common features of the pPATH plasmids support the hypothesis that the two strains recently evolved into host-specific pathogens.
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Affiliation(s)
- Naama Geraffi
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Priya Gupta
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Naama Wagner
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Isaac Barash
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Tal Pupko
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Guido Sessa
- School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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5
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water/solute-permeable channels as a virulence strategy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.29.547699. [PMID: 37546725 PMCID: PMC10402153 DOI: 10.1101/2023.07.29.547699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Many animal and plant pathogenic bacteria utilize a type III secretion system to deliver effector proteins into the host cell 1,2 . Elucidation of how these effector proteins function in the host cell is critical for understanding infectious diseases in animals and plants 3-5 . The widely conserved AvrE/DspE-family effectors play a central role in the pathogenesis of diverse phytopathogenic bacteria 6 . These conserved effectors are involved in the induction of "water-soaking" and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE/DspE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE/DspE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in (i) inward and outward currents, (ii) permeability to water and (iii) osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine (PAMAM) dendrimers as inhibitors of the DspE/AvrE channels. Remarkably, PAMAMs broadly inhibit AvrE/DspE virulence activities in Xenopus oocytes and during Erwinia amylovora and Pseudomonas syringae infections. Thus, we have unraveled the enigmatic function of a centrally important family of bacterial effectors with significant conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
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6
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Li C, Wang L, Cseke LJ, Vasconcelos F, Huguet-Tapia JC, Gassmann W, Pauwels L, White FF, Dong H, Yang B. Efficient CRISPR-Cas9 based cytosine base editors for phytopathogenic bacteria. Commun Biol 2023; 6:56. [PMID: 36646768 PMCID: PMC9842757 DOI: 10.1038/s42003-023-04451-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Phytopathogenic bacteria play important roles in plant productivity, and developments in gene editing have potential for enhancing the genetic tools for the identification of critical genes in the pathogenesis process. CRISPR-based genome editing variants have been developed for a wide range of applications in eukaryotes and prokaryotes. However, the unique mechanisms of different hosts restrict the wide adaptation for specific applications. Here, CRISPR-dCas9 (dead Cas9) and nCas9 (Cas9 nickase) deaminase vectors were developed for a broad range of phytopathogenic bacteria. A gene for a dCas9 or nCas9, cytosine deaminase CDA1, and glycosylase inhibitor fusion protein (cytosine base editor, or CBE) was applied to base editing under the control of different promoters. Results showed that the RecA promoter led to nearly 100% modification of the target region. When residing on the broad host range plasmid pHM1, CBERecAp is efficient in creating base edits in strains of Xanthomonas, Pseudomonas, Erwinia and Agrobacterium. CBE based on nCas9 extended the editing window and produced a significantly higher editing rate in Pseudomonas. Strains with nonsynonymous mutations in test genes displayed expected phenotypes. By multiplexing guide RNA genes, the vectors can modify up to four genes in a single round of editing. Whole-genome sequencing of base-edited isolates of Xanthomonas oryzae pv. oryzae revealed guide RNA-independent off-target mutations. Further modifications of the CBE, using a CDA1 variant (CBERecAp-A) reduced off-target effects, providing an improved editing tool for a broad group of phytopathogenic bacteria.
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Affiliation(s)
- Chenhao Li
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA ,grid.27871.3b0000 0000 9750 7019Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu P. R. China
| | - Longfei Wang
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA
| | - Leland J. Cseke
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA
| | - Fernanda Vasconcelos
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA
| | - Jose Carlos Huguet-Tapia
- grid.15276.370000 0004 1936 8091Department of Plant Pathology, University of Florida, Gainesville, Florida USA
| | - Walter Gassmann
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA
| | - Laurens Pauwels
- grid.5342.00000 0001 2069 7798Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium ,grid.511033.5Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium
| | - Frank F. White
- grid.15276.370000 0004 1936 8091Department of Plant Pathology, University of Florida, Gainesville, Florida USA
| | - Hansong Dong
- grid.27871.3b0000 0000 9750 7019Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu P. R. China
| | - Bing Yang
- grid.134936.a0000 0001 2162 3504Division of Plant Science and Technology, Bond Life Sciences Center, University of Missouri, Columbia, Missouri USA ,grid.34424.350000 0004 0466 6352Donald Danforth Plant Science Center, St. Louis, Missouri USA
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Gaucher M, Righetti L, Aubourg S, Dugé de Bernonville T, Brisset MN, Chevreau E, Vergne E. An Erwinia amylovora inducible promoter for improvement of apple fire blight resistance. PLANT CELL REPORTS 2022; 41:1499-1513. [PMID: 35385991 PMCID: PMC9270298 DOI: 10.1007/s00299-022-02869-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/18/2022] [Indexed: 06/14/2023]
Abstract
pPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes. Intragenesis is an important alternative to transgenesis to produce modified plants containing native DNA only. A key point to develop such a strategy is the availability of regulatory sequences controlling the expression of the gene of interest. With the aim of finding apple gene promoters either inducible by the fire blight pathogen Erwinia amylovora (Ea) or moderately constitutive, we focused on polyphenoloxidase genes (PPO). These genes encode oxidative enzymes involved in many physiological processes and have been previously shown to be upregulated during the Ea infection process. We found ten PPO and two PPO-like sequences in the apple genome and characterized the promoters of MdPPO16 (pPPO16) and MdKFDV02 PPO-like (pKFDV02) for their potential as Ea-inducible and low-constitutive regulatory sequences, respectively. Expression levels of reporter genes fused to these promoters and transiently or stably expressed in apple were quantified after various treatments. Unlike pKFDV02 which displayed a variable activity, pPPO16 allowed a fast and strong expression of transgenes in apple following Ea infection in a Type 3 Secretion System dependent manner. Altogether our results does not confirmed pKFDV02 as a constitutive and weak promoter whereas pPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes.
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Affiliation(s)
- Matthieu Gaucher
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000, Angers, France
| | - Laura Righetti
- Research Centre for Cereal and Industrial Crops (CREA-CI), Council for Agricultural Research and Agricultural Economics Analysis, Via di Corticella 133, 40128, Bologna, Italy
| | - Sébastien Aubourg
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000, Angers, France
| | - Thomas Dugé de Bernonville
- EA2106 Biomolécules et Biotechnologies Végétales, UFR Sciences Pharmaceutiques, Université François Rabelais, 31 avenue Monge, 37200, Tours, France
| | | | - Elisabeth Chevreau
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000, Angers, France
| | - Emilie Vergne
- Univ Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000, Angers, France.
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Launay A, Jolivet S, Clément G, Zarattini M, Dellero Y, Le Hir R, Jossier M, Hodges M, Expert D, Fagard M. DspA/E-Triggered Non-Host Resistance against E. amylovora Depends on the Arabidopsis GLYCOLATE OXIDASE 2 Gene. Int J Mol Sci 2022; 23:ijms23084224. [PMID: 35457046 PMCID: PMC9029980 DOI: 10.3390/ijms23084224] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 12/04/2022] Open
Abstract
DspA/E is a type three effector injected by the pathogenic bacterium Erwinia amylovora inside plant cells. In non-host Arabidopsis thaliana, DspA/E inhibits seed germination, root growth, de novo protein synthesis and triggers localized cell death. To better understand the mechanisms involved, we performed EMS mutagenesis on a transgenic line, 13-1-2, containing an inducible dspA/E gene. We identified three suppressor mutants, two of which belonged to the same complementation group. Both were resistant to the toxic effects of DspA/E. Metabolome analysis showed that the 13-1-2 line was depleted in metabolites of the TCA cycle and accumulated metabolites associated with cell death and defense. TCA cycle and cell-death associated metabolite levels were respectively increased and reduced in both suppressor mutants compared to the 13-1-2 line. Whole genome sequencing indicated that both suppressor mutants displayed missense mutations in conserved residues of Glycolate oxidase 2 (GOX2), a photorespiratory enzyme that we confirmed to be localized in the peroxisome. Leaf GOX activity increased in leaves infected with E. amylovora in a DspA/E-dependent manner. Moreover, the gox2-2 KO mutant was more sensitive to E. amylovora infection and displayed reduced JA-signaling. Our results point to a role for glycolate oxidase in type II non-host resistance and to the importance of central metabolic functions in controlling growth/defense balance.
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Affiliation(s)
- Alban Launay
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Sylvie Jolivet
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Gilles Clément
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Marco Zarattini
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Younes Dellero
- Université Paris-Saclay, CNRS, INRAE, Université Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France; (Y.D.); (M.J.); (M.H.)
- Université Paris Cité, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France
| | - Rozenn Le Hir
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Mathieu Jossier
- Université Paris-Saclay, CNRS, INRAE, Université Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France; (Y.D.); (M.J.); (M.H.)
- Université Paris Cité, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France
| | - Michael Hodges
- Université Paris-Saclay, CNRS, INRAE, Université Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France; (Y.D.); (M.J.); (M.H.)
- Université Paris Cité, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), 91190 Gif sur Yvette, France
| | - Dominique Expert
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
| | - Mathilde Fagard
- Université Paris-Saclay, INRAE, AgroParisTech, Institut Jean-Pierre Bourgin (IJPB), 78000 Versailles, France; (A.L.); (S.J.); (G.C.); (M.Z.); (R.L.H.); (D.E.)
- Correspondence:
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9
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Chavonet E, Gaucher M, Warneys R, Bodelot A, Heintz C, Juillard A, Cournol R, Widmalm G, Bowen JK, Hamiaux C, Brisset MN, Degrave A. Search for host defense markers uncovers an apple agglutination factor corresponding with fire blight resistance. PLANT PHYSIOLOGY 2022; 188:1350-1368. [PMID: 34904175 PMCID: PMC8825249 DOI: 10.1093/plphys/kiab542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/25/2021] [Indexed: 06/12/2023]
Abstract
Pathenogenesis-related (PR) proteins are extensively used as molecular markers to dissect the signaling cascades leading to plant defense responses. However, studies focusing on the biochemical or biological properties of these proteins remain rare. Here, we identify and characterize a class of apple (Malus domestica) PR proteins, named M. domestica AGGLUTININS (MdAGGs), belonging to the amaranthin-like lectin family. By combining molecular and biochemical approaches, we show that abundant production of MdAGGs in leaf tissues corresponds with enhanced resistance to the bacterium Erwinia amylovora, the causal agent of the disease fire blight. We also show that E. amylovora represses the expression of MdAGG genes by injecting the type 3 effector DspA/E into host cells and by secreting bacterial exopolysaccharides. Using a purified recombinant MdAGG, we show that the protein agglutinates E. amylovora cells in vitro and binds bacterial lipopolysaccharides at low pH, conditions reminiscent of the intercellular pH occurring in planta upon E. amylovora infection. We finally provide evidence that negatively charged polysaccharides, such as the free exopolysaccharide amylovoran progressively released by the bacteria, act as decoys relying on charge-charge interaction with the MdAGG to inhibit agglutination. Overall, our results suggest that the production of this particular class of PR proteins may contribute to apple innate immunity mechanisms active against E. amylovora.
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Affiliation(s)
- Erwan Chavonet
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Matthieu Gaucher
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Romain Warneys
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Antoine Bodelot
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Christelle Heintz
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Anthony Juillard
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Raphaël Cournol
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Göran Widmalm
- Arrhenius Laboratory, Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden
| | - Joanna K Bowen
- The New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1025, New Zealand
| | - Cyril Hamiaux
- The New Zealand Institute for Plant and Food Research Limited, Mount Albert Research Centre, Auckland 1025, New Zealand
| | - Marie-Noëlle Brisset
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
| | - Alexandre Degrave
- Institut Agro, University of Angers, INRAE, IRHS, SFR QUASAV, F-49000 Angers, France
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10
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Moretti C, Rezzonico F, Orfei B, Cortese C, Moreno‐Pérez A, van den Burg HA, Onofri A, Firrao G, Ramos C, Smits THM, Buonaurio R. Synergistic interaction between the type III secretion system of the endophytic bacterium Pantoea agglomerans DAPP-PG 734 and the virulence of the causal agent of olive knot Pseudomonas savastanoi pv. savastanoi DAPP-PG 722. MOLECULAR PLANT PATHOLOGY 2021; 22:1209-1225. [PMID: 34268839 PMCID: PMC8435235 DOI: 10.1111/mpp.13105] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 06/09/2021] [Accepted: 06/16/2021] [Indexed: 05/29/2023]
Abstract
The endophytic bacterium Pantoea agglomerans DAPP-PG 734 was previously isolated from olive knots caused by infection with Pseudomonas savastanoi pv. savastanoi DAPP-PG 722. Whole-genome analysis of this P. agglomerans strain revealed the presence of a Hypersensitive response and pathogenicity (Hrp) type III secretion system (T3SS). To assess the role of the P. agglomerans T3SS in the interaction with P. savastanoi pv. savastanoi, we generated independent knockout mutants in three Hrp genes of the P. agglomerans DAPP-PG 734 T3SS (hrpJ, hrpN, and hrpY). In contrast to the wildtype control, all three mutants failed to cause a hypersensitive response when infiltrated in tobacco leaves, suggesting that P. agglomerans T3SS is functional and injects effector proteins in plant cells. In contrast to P. savastanoi pv. savastanoi DAPP-PG 722, the wildtype strain P. agglomerans DAPP-PG 734 and its Hrp T3SS mutants did not cause olive knot disease in 1-year-old olive plants. Coinoculation of P. savastanoi pv. savastanoi with P. agglomerans wildtype strains did not significantly change the knot size, while the DAPP-PG 734 hrpY mutant induced a significant decrease in knot size, which could be complemented by providing hrpY on a plasmid. By epifluorescence microscopy and confocal laser scanning microscopy, we found that the localization patterns in knots were nonoverlapping for P. savastanoi pv. savastanoi and P. agglomerans when coinoculated. Our results suggest that suppression of olive plant defences mediated by the Hrp T3SS of P. agglomerans DAPP-PG 734 positively impacts the virulence of P. savastanoi pv. savastanoi DAPP-PG 722.
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Affiliation(s)
- Chiaraluce Moretti
- Dipartimento di Scienze Agrarie, Alimentari e AmbientaliUniversità degli Studi di PerugiaPerugiaItaly
| | - Fabio Rezzonico
- Environmental Genomics and Systems Biology Research GroupInstitute of Natural Resource SciencesZurich University of Applied Sciences ZHAWWädenswilSwitzerland
| | - Benedetta Orfei
- Dipartimento di Scienze Agrarie, Alimentari e AmbientaliUniversità degli Studi di PerugiaPerugiaItaly
| | - Chiara Cortese
- Dipartimento di Scienze Agrarie, Alimentari e AmbientaliUniversità degli Studi di PerugiaPerugiaItaly
| | - Alba Moreno‐Pérez
- Área de GenéticaFacultad de CienciasUniversidad de MálagaMálagaSpain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”Universidad de Málaga‐Consejo Superior de Investigaciones CientíficasMálagaSpain
| | - Harrold A. van den Burg
- Molecular Plant PathologySwammerdam Institute for Life SciencesUniversity of AmsterdamAmsterdamNetherlands
| | - Andrea Onofri
- Dipartimento di Scienze Agrarie, Alimentari e AmbientaliUniversità degli Studi di PerugiaPerugiaItaly
| | - Giuseppe Firrao
- Dipartimento di Scienze Agroalimentati Ambientali e AnimaliUniversità degli Studi di UdineUdineItaly
| | - Cayo Ramos
- Área de GenéticaFacultad de CienciasUniversidad de MálagaMálagaSpain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”Universidad de Málaga‐Consejo Superior de Investigaciones CientíficasMálagaSpain
| | - Theo H. M. Smits
- Environmental Genomics and Systems Biology Research GroupInstitute of Natural Resource SciencesZurich University of Applied Sciences ZHAWWädenswilSwitzerland
| | - Roberto Buonaurio
- Dipartimento di Scienze Agrarie, Alimentari e AmbientaliUniversità degli Studi di PerugiaPerugiaItaly
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11
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Cui Z, Huntley RB, Schultes NP, Kakar KU, Yang CH, Zeng Q. Expression of the Type III Secretion System Genes in Epiphytic Erwinia amylovora Cells on Apple Stigmas Benefits Endophytic Infection at the Hypanthium. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:1119-1127. [PMID: 34698527 DOI: 10.1094/mpmi-06-21-0152-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Erwinia amylovora causes fire blight on rosaceous plants. One of the major entry points of E. amylovora into hosts is flowers, where E. amylovora proliferates epiphytically on stigmatic and hypanthium surfaces and, subsequently, causes endophytic infection at the hypanthium. The type III secretion system (T3SS) is an important virulence factor in E. amylovora. Although the role of T3SS during endophytic infection is well characterized, its expression during epiphytic colonization and role in the subsequent infection is less understood. Here, we investigated T3SS gene expression in epiphytic E. amylovora on stigma and hypanthium of apple flowers under different relative humidities (RH). On stigma surfaces, T3SS was expressed in a high percentage of E. amylovora cells, and its expression promoted epiphytic growth. On hypanthium surfaces, however, T3SS was expressed in fewer E. amylovora cells than on the stigma, and displayed no correlation with epiphytic growth, even though T3SS expression is essential for infection. E. amylovora cells grown on stigmatic surfaces and then flushed down to the hypanthium displayed a higher level of T3SS expression than cells grown on the hypanthium surface alone. Furthermore, E. amylovora cells precultured on stigma had a higher potential to infect flowers than E. amylovora cells precultured in a T3SS-repressive medium. This suggests that T3SS induction during the stigmatic epiphytic colonization may be beneficial for subsequent infection. Finally, epiphytic expression of T3SS was influenced by RH. Higher percentage of stigmatic E. amylovora cells expressed T3SS under high RH than under low RH.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Zhouqi Cui
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
| | - Regan B Huntley
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
| | - Neil P Schultes
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
| | - Kaleem U Kakar
- Department of Microbiology, Faculty of Life Sciences and Informatics, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS), Quetta, 87300, Pakistan
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, U.S.A
| | - Quan Zeng
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT 06504, U.S.A
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12
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Kharadi RR, Schachterle JK, Yuan X, Castiblanco LF, Peng J, Slack SM, Zeng Q, Sundin GW. Genetic Dissection of the Erwinia amylovora Disease Cycle. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:191-212. [PMID: 33945696 DOI: 10.1146/annurev-phyto-020620-095540] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Fire blight, caused by the bacterial phytopathogen Erwinia amylovora, is an economically important and mechanistically complex disease that affects apple and pear production in most geographic production hubs worldwide. We compile, assess, and present a genetic outlook on the progression of an E. amylovora infection in the host. We discuss the key aspects of type III secretion-mediated infection and systemic movement, biofilm formation in xylem, and pathogen dispersal via ooze droplets, a concentrated suspension of bacteria and exopolysaccharide components. We present an overall outlook on the genetic elements contributing to E. amylovora pathogenesis, including an exploration of the impact of floral microbiomes on E. amylovora colonization, and summarize the current knowledge of host responses to an incursion and how this response stimulates further infection and systemic spread. We hope to facilitate the identification of new, unexplored areas of research in this pathosystem that can help identify evolutionarily susceptible genetic targets to ultimately aid in the design of sustainable strategies for fire blight disease mitigation.
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Affiliation(s)
- Roshni R Kharadi
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
| | - Jeffrey K Schachterle
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
- Floral and Nursery Plants Research Unit, US National Arboretum, USDA-ARS, Beltsville, Maryland 20705, USA
| | - Xiaochen Yuan
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
| | - Luisa F Castiblanco
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
| | - Jingyu Peng
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
| | - Suzanne M Slack
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
| | - Quan Zeng
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06511, USA
| | - George W Sundin
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan 48824, USA;
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13
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Yuan X, Hulin MT, Sundin GW. Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review. JOURNAL OF PLANT PATHOLOGY 2021; 103:25-39. [PMID: 0 DOI: 10.1007/s42161-020-00623-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/23/2020] [Indexed: 05/20/2023]
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14
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Zhang WB, Yan HL, Zhu ZC, Zhang C, Du PX, Zhao WJ, Li WM. Genome-wide identification of the Sec-dependent secretory protease genes in Erwinia amylovora and analysis of their expression during infection of immature pear fruit. J Zhejiang Univ Sci B 2020; 21:716-726. [PMID: 32893528 DOI: 10.1631/jzus.b2000281] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The general secretory (Sec) pathway represents a common mechanism by which bacteria secrete proteins, including virulence factors, into the extracytoplasmic milieu. However, there is little information about this system, as well as its associated secretory proteins, in relation to the fire blight pathogen Erwinia amylovora. In this study, data mining revealed that E. amylovora harbors all of the essential components of the Sec system. Based on this information, we identified putative Sec-dependent secretory proteases in E. amylovora on a genome-wide scale. Using the programs SignalP, LipoP, and Phobius, a total of 15 putative proteases were predicted to contain the N-terminal signal peptides (SPs) that might link them to the Sec-dependent pathway. The activities of the predicted SPs were further validated using an Escherichia coli-based alkaline phosphatase (PhoA) gene fusion system that confirmed their extracytoplasmic property. Transcriptional analyses showed that the expression of 11 of the 15 extracytoplasmic protease genes increased significantly when E. amylovora was used to inoculate immature pears, suggesting their potential roles in plant infection. The results of this study support the suggestion that E. amylovora might employ the Sec system to secrete a suite of proteases to enable successful infection of plants, and shed new light on the interaction of E. amylovora with host plants.
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Affiliation(s)
- Wang-Bin Zhang
- College of Plant Science, Tarim University, Alar 843300, China.,Southern Xinjiang Key Laboratory of Integrated Pest Management, Tarim University, Alar 843300, China
| | - Hai-Lin Yan
- College of Plant Science, Tarim University, Alar 843300, China.,Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Zong-Cai Zhu
- College of Plant Science, Tarim University, Alar 843300, China.,Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Chao Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Pei-Xiu Du
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Wen-Jun Zhao
- Chinese Academy of Inspection and Quarantine, Beijing 100176, China
| | - Wei-Min Li
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
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15
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Yadav V, Wang Z, Wei C, Amo A, Ahmed B, Yang X, Zhang X. Phenylpropanoid Pathway Engineering: An Emerging Approach towards Plant Defense. Pathogens 2020; 9:pathogens9040312. [PMID: 32340374 PMCID: PMC7238016 DOI: 10.3390/pathogens9040312] [Citation(s) in RCA: 174] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/11/2020] [Accepted: 04/17/2020] [Indexed: 11/23/2022] Open
Abstract
Pathogens hitting the plant cell wall is the first impetus that triggers the phenylpropanoid pathway for plant defense. The phenylpropanoid pathway bifurcates into the production of an enormous array of compounds based on the few intermediates of the shikimate pathway in response to cell wall breaches by pathogens. The whole metabolomic pathway is a complex network regulated by multiple gene families and it exhibits refined regulatory mechanisms at the transcriptional, post-transcriptional, and post-translational levels. The pathway genes are involved in the production of anti-microbial compounds as well as signaling molecules. The engineering in the metabolic pathway has led to a new plant defense system of which various mechanisms have been proposed including salicylic acid and antimicrobial mediated compounds. In recent years, some key players like phenylalanine ammonia lyases (PALs) from the phenylpropanoid pathway are proposed to have broad spectrum disease resistance (BSR) without yield penalties. Now we have more evidence than ever, yet little understanding about the pathway-based genes that orchestrate rapid, coordinated induction of phenylpropanoid defenses in response to microbial attack. It is not astonishing that mutants of pathway regulator genes can show conflicting results. Therefore, precise engineering of the pathway is an interesting strategy to aim at profitably tailored plants. Here, this review portrays the current progress and challenges for phenylpropanoid pathway-based resistance from the current prospective to provide a deeper understanding.
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Affiliation(s)
- Vivek Yadav
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
| | - Zhongyuan Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
| | - Chunhua Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
| | - Aduragbemi Amo
- College of Agronomy, Northwest A&F University, Xianyang 712100, China;
| | - Bilal Ahmed
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
| | - Xiaozhen Yang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
| | - Xian Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of horticulture, Northwest A&F University, Xianyang 712100, China; (V.Y.); (Z.W.); (C.W.); (B.A.); (X.Y.)
- Correspondence: ; Tel.: +86-029-8708-2613
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16
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Pompili V, Dalla Costa L, Piazza S, Pindo M, Malnoy M. Reduced fire blight susceptibility in apple cultivars using a high-efficiency CRISPR/Cas9-FLP/FRT-based gene editing system. PLANT BIOTECHNOLOGY JOURNAL 2020; 18:845-858. [PMID: 31495052 PMCID: PMC7004915 DOI: 10.1111/pbi.13253] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 05/20/2023]
Abstract
The bacterium Erwinia amylovora, the causal agent of fire blight disease in apple, triggers its infection through the DspA/E effector which interacts with the apple susceptibility protein MdDIPM4. In this work, MdDIPM4 knockout has been produced in two Malus × domestica susceptible cultivars using the CRISPR/Cas9 system delivered via Agrobacterium tumefaciens. Fifty-seven transgenic lines were screened to identify CRISPR/Cas9-induced mutations. An editing efficiency of 75% was obtained. Seven edited lines with a loss-of-function mutation were inoculated with the pathogen. Highly significant reduction in susceptibility was observed compared to control plants. Sequencing of five potential off-target sites revealed no mutation event. Moreover, our construct contained a heat-shock inducible FLP/FRT recombination system designed specifically to remove the T-DNA harbouring the expression cassettes for CRISPR/Cas9, the marker gene and the FLP itself. Six plant lines with reduced susceptibility to the pathogen were heat-treated and screened by real-time PCR to quantify the exogenous DNA elimination. The T-DNA removal was further validated by sequencing in one plant line. To our knowledge, this work demonstrates for the first time the development and application of a CRISPR/Cas9-FLP/FRT gene editing system for the production of edited apple plants carrying a minimal trace of exogenous DNA.
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Affiliation(s)
- Valerio Pompili
- Department of Genomics and Biology of Fruit CropsResearch and Innovation CentreFondazione Edmund MachSan Michele all'AdigeItaly
- Department of Agricultural, Food, Environmental and Animal SciencesUniversità degli Studi di UdineUdineItaly
| | - Lorenza Dalla Costa
- Department of Genomics and Biology of Fruit CropsResearch and Innovation CentreFondazione Edmund MachSan Michele all'AdigeItaly
| | - Stefano Piazza
- Department of Genomics and Biology of Fruit CropsResearch and Innovation CentreFondazione Edmund MachSan Michele all'AdigeItaly
| | - Massimo Pindo
- Department of Genomics and Biology of Fruit CropsResearch and Innovation CentreFondazione Edmund MachSan Michele all'AdigeItaly
| | - Mickael Malnoy
- Department of Genomics and Biology of Fruit CropsResearch and Innovation CentreFondazione Edmund MachSan Michele all'AdigeItaly
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17
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Daudu D, Kisiala A, Werner Ribeiro C, Mélin C, Perrot L, Clastre M, Courdavault V, Papon N, Oudin A, Courtois M, Dugé de Bernonville T, Gaucher M, Degrave A, Lanoue A, Lanotte P, Schouler C, Brisset MN, Emery RN, Pichon O, Carpin S, Giglioli-Guivarc’h N, Crèche J, Besseau S, Glévarec G. Setting-up a fast and reliable cytokinin biosensor based on a plant histidine kinase receptor expressed in Saccharomyces cerevisiae. J Biotechnol 2019; 289:103-111. [DOI: 10.1016/j.jbiotec.2018.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 11/14/2018] [Accepted: 11/16/2018] [Indexed: 12/21/2022]
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18
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Gimenez-Ibanez S, Hann DR, Chang JH, Segonzac C, Boller T, Rathjen JP. Differential Suppression of Nicotiana benthamiana Innate Immune Responses by Transiently Expressed Pseudomonas syringae Type III Effectors. FRONTIERS IN PLANT SCIENCE 2018; 9:688. [PMID: 29875790 PMCID: PMC5974120 DOI: 10.3389/fpls.2018.00688] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 05/04/2018] [Indexed: 05/13/2023]
Abstract
The plant pathogen Pseudomonas syringae injects about 30 different virulence proteins, so-called effectors, via a type III secretion system into plant cells to promote disease. Although some of these effectors are known to suppress either pattern-triggered immunity (PTI) or effector-triggered immunity (ETI), the mode of action of most of them remains unknown. Here, we used transient expression in Nicotiana benthamiana, to test the abilities of type III effectors of Pseudomonas syringae pv. tomato (Pto) DC3000 and Pseudomonas syringae pv. tabaci (Pta) 11528 to interfere with plant immunity. We monitored the sequential and rapid bursts of cytoplasmic Ca2+ and reactive oxygen species (ROS), the subsequent induction of defense gene expression, and promotion of cell death. We found that several effector proteins caused cell death, but independently of the known plant immune regulator NbSGT1, a gene essential for ETI. Furthermore, many effectors delayed or blocked the cell death-promoting activity of other effectors, thereby potentially contributing to pathogenesis. Secondly, a large number of effectors were able to suppress PAMP-induced defense responses. In the majority of cases, this resulted in suppression of all studied PAMP responses, suggesting that these effectors target common elements of PTI. However, effectors also targeted different steps within defense pathways and could be divided into three major groups based on their suppressive activities. Finally, the abilities of effectors of both Pto DC3000 and Pta 11528 to suppress plant immunity was conserved in most but not all cases. Overall, our data present a comprehensive picture of the mode of action of these effectors and indicate that most of them suppress plant defenses in various ways.
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Affiliation(s)
- Selena Gimenez-Ibanez
- The Sainsbury Laboratory, Norwich, United Kingdom
- Plant Molecular Genetics Department, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Dagmar R Hann
- The Sainsbury Laboratory, Norwich, United Kingdom
- Department of Environmental Sciences, Botanical Institute, University of Basel, Basel, Switzerland
- Institute of Genetics, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jeff H Chang
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, United States
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, United States
| | - Cécile Segonzac
- The Sainsbury Laboratory, Norwich, United Kingdom
- Department of Plant Science, Plant Genomics and Breeding Institute and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Thomas Boller
- Department of Environmental Sciences, Botanical Institute, University of Basel, Basel, Switzerland
| | - John P Rathjen
- The Sainsbury Laboratory, Norwich, United Kingdom
- Research School of Biology, Australian National University, Acton, ACT, Australia
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19
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Hamdoun S, Gao M, Gill M, Kwon A, Norelli JL, Lu H. Signalling requirements for Erwinia amylovora-induced disease resistance, callose deposition and cell growth in the non-host Arabidopsis thaliana. MOLECULAR PLANT PATHOLOGY 2018; 19:1090-1103. [PMID: 28756640 PMCID: PMC6638093 DOI: 10.1111/mpp.12588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 07/11/2017] [Accepted: 07/25/2017] [Indexed: 05/11/2023]
Abstract
Erwinia amylovora is the causal agent of the fire blight disease in some plants of the Rosaceae family. The non-host plant Arabidopsis serves as a powerful system for the dissection of mechanisms of resistance to E. amylovora. Although not yet known to mount gene-for-gene resistance to E. amylovora, we found that Arabidopsis activated strong defence signalling mediated by salicylic acid (SA), with kinetics and amplitude similar to that induced by the recognition of the bacterial effector avrRpm1 by the resistance protein RPM1. Genetic analysis further revealed that SA signalling, but not signalling mediated by ethylene (ET) and jasmonic acid (JA), is required for E. amylovora resistance. Erwinia amylovora induces massive callose deposition on infected leaves, which is independent of SA, ET and JA signalling and is necessary for E. amylovora resistance in Arabidopsis. We also observed tumour-like growths on E. amylovora-infected Arabidopsis leaves, which contain enlarged mesophyll cells with increased DNA content and are probably a result of endoreplication. The formation of such growths is largely independent of SA signalling and some E. amylovora effectors. Together, our data reveal signalling requirements for E. amylovora-induced disease resistance, callose deposition and cell fate change in the non-host plant Arabidopsis. Knowledge from this study could facilitate a better understanding of the mechanisms of host defence against E. amylovora and eventually improve host resistance to the pathogen.
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Affiliation(s)
- Safae Hamdoun
- Department of Biological SciencesUniversity of Maryland Baltimore County1000 Hilltop CircleBaltimore, MD 21250USA
| | - Min Gao
- Department of Biological SciencesUniversity of Maryland Baltimore County1000 Hilltop CircleBaltimore, MD 21250USA
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A & F UniversityYangling 712100ShaanxiChina
| | - Manroop Gill
- Department of Biological SciencesUniversity of Maryland Baltimore County1000 Hilltop CircleBaltimore, MD 21250USA
| | - Ashley Kwon
- Department of Biological SciencesUniversity of Maryland Baltimore County1000 Hilltop CircleBaltimore, MD 21250USA
| | - John L. Norelli
- United States Department of Agriculture, Agricultural Research Service, Appalachian Fruit Research Station2217 Wiltshire RoadKearneysville, WV 25430USA
| | - Hua Lu
- Department of Biological SciencesUniversity of Maryland Baltimore County1000 Hilltop CircleBaltimore, MD 21250USA
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20
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Castiblanco LF, Triplett LR, Sundin GW. Regulation of Effector Delivery by Type III Secretion Chaperone Proteins in Erwinia amylovora. Front Microbiol 2018; 9:146. [PMID: 29472907 PMCID: PMC5809446 DOI: 10.3389/fmicb.2018.00146] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/23/2018] [Indexed: 11/16/2022] Open
Abstract
Type III secretion (TTS) chaperones are critical for the delivery of many effector proteins from Gram-negative bacterial pathogens into host cells, functioning in the stabilization and hierarchical delivery of the effectors to the type III secretion system (TTSS). The plant pathogen Erwinia amylovora secretes at least four TTS effector proteins: DspE, Eop1, Eop3, and Eop4. DspE specifically interacts with the TTS chaperone protein DspF, which stabilizes the effector protein in the cytoplasm and promotes its efficient translocation through the TTSS. However, the role of E. amylovora chaperones in regulating the delivery of other secreted effectors is unknown. In this study, we identified functional interactions between the effector proteins DspE, Eop1, and Eop3 with the TTS chaperones DspF, Esc1 and Esc3 in yeast. Using site-directed mutagenesis, secretion, and translocation assays, we demonstrated that the three TTS chaperones have additive roles for the secretion and translocation of DspE into plant cells whereas DspF negatively affects the translocation of Eop1 and Eop3. Collectively, these results indicate that TTS chaperone proteins exhibit a cooperative behavior to orchestrate the effector secretion and translocation dynamics in E. amylovora.
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Affiliation(s)
- Luisa F Castiblanco
- Department of Plant, Soil and Microbial Sciences, Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI, United States
| | - Lindsay R Triplett
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - George W Sundin
- Department of Plant, Soil and Microbial Sciences, Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI, United States
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Aksoy HM, Kaya Y, Tengku Abdul Hamid TH. Expression of the dspA/E gene of Erwinia amylovora in non-host plant Arabidopsis thaliana. BIOTECHNOL BIOTEC EQ 2017. [DOI: 10.1080/13102818.2016.1246202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Affiliation(s)
- Hasan Murat Aksoy
- Department of Plant Protection, Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey
| | - Yilmaz Kaya
- Department of Agricultural Biotechnology, Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey
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Jin L, Ham JH, Hage R, Zhao W, Soto-Hernández J, Lee SY, Paek SM, Kim MG, Boone C, Coplin DL, Mackey D. Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins. PLoS Pathog 2016; 12:e1005609. [PMID: 27191168 PMCID: PMC4871590 DOI: 10.1371/journal.ppat.1005609] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 04/12/2016] [Indexed: 11/19/2022] Open
Abstract
Bacterial AvrE-family Type-III effector proteins (T3Es) contribute significantly to the virulence of plant-pathogenic species of Pseudomonas, Pantoea, Ralstonia, Erwinia, Dickeya and Pectobacterium, with hosts ranging from monocots to dicots. However, the mode of action of AvrE-family T3Es remains enigmatic, due in large part to their toxicity when expressed in plant or yeast cells. To search for targets of WtsE, an AvrE-family T3E from the maize pathogen Pantoea stewartii subsp. stewartii, we employed a yeast-two-hybrid screen with non-lethal fragments of WtsE and a synthetic genetic array with full-length WtsE. Together these screens indicate that WtsE targets maize protein phosphatase 2A (PP2A) heterotrimeric enzyme complexes via direct interaction with B' regulatory subunits. AvrE1, another AvrE-family T3E from Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), associates with specific PP2A B' subunit proteins from its susceptible host Arabidopsis that are homologous to the maize B' subunits shown to interact with WtsE. Additionally, AvrE1 was observed to associate with the WtsE-interacting maize proteins, indicating that PP2A B' subunits are likely conserved targets of AvrE-family T3Es. Notably, the ability of AvrE1 to promote bacterial growth and/or suppress callose deposition was compromised in Arabidopsis plants with mutations of PP2A genes. Also, chemical inhibition of PP2A activity blocked the virulence activity of both WtsE and AvrE1 in planta. The function of HopM1, a Pto DC3000 T3E that is functionally redundant to AvrE1, was also impaired in specific PP2A mutant lines, although no direct interaction with B' subunits was observed. These results indicate that sub-component specific PP2A complexes are targeted by bacterial T3Es, including direct targeting by members of the widely conserved AvrE-family.
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Affiliation(s)
- Lin Jin
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jong Hyun Ham
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America
| | - Rosemary Hage
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Wanying Zhao
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jaricelis Soto-Hernández
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Sang Yeol Lee
- Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Seung-Mann Paek
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Min Gab Kim
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
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Degrave A, Siamer S, Boureau T, Barny MA. The AvrE superfamily: ancestral type III effectors involved in suppression of pathogen-associated molecular pattern-triggered immunity. MOLECULAR PLANT PATHOLOGY 2015; 16:899-905. [PMID: 25640649 PMCID: PMC6638435 DOI: 10.1111/mpp.12237] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The AvrE superfamily of type III effectors (T3Es) is widespread among type III-dependent phytobacteria and plays a crucial role during bacterial pathogenesis. Members of the AvrE superfamily are vertically inherited core effectors, indicating an ancestral acquisition of these effectors in bacterial plant pathogens. AvrE-T3Es contribute significantly to virulence by suppressing pathogen-associated molecular pattern (PAMP)-triggered immunity. They inhibit salicylic acid-mediated plant defences, interfere with vesicular trafficking and promote bacterial growth in planta. AvrE-T3Es elicit cell death in both host and non-host plants independent of any known plant resistance protein, suggesting an original interaction with the plant immune system. Recent studies in yeast have indicated that they activate protein phosphatase 2A and inhibit serine palmitoyl transferase, the first enzyme of the sphingolipid biosynthesis pathway. In this review, we describe the current picture that has emerged from studies of the different members of this fascinating large family.
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Affiliation(s)
- Alexandre Degrave
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), 49045, Angers, France
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
| | - Sabrina Siamer
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056, Basel, Switzerland
| | - Tristan Boureau
- UMR1345, IRHS, Institut National de la Recherche Agronomique (INRA), 49071, Beaucouzé, France
- UMR1345, IRHS, Université d'Angers, SFR 4207 QUASAV, PRES l'UNAM, 49045, Angers, France
| | - Marie-Anne Barny
- UMR1392, INRA, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât á 7ème Etage Case 237, 7 Quai St.-Bernard, 75252, Paris, France
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24
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Inheritance of Pantoea type III secretion systems through both vertical and horizontal transfer. Mol Genet Genomics 2015; 290:2075-88. [DOI: 10.1007/s00438-015-1062-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 05/03/2015] [Indexed: 11/26/2022]
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25
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Asselin JAE, Lin J, Perez-Quintero AL, Gentzel I, Majerczak D, Opiyo SO, Zhao W, Paek SM, Kim MG, Coplin DL, Blakeslee JJ, Mackey D. Perturbation of maize phenylpropanoid metabolism by an AvrE family type III effector from Pantoea stewartii. PLANT PHYSIOLOGY 2015; 167:1117-35. [PMID: 25635112 PMCID: PMC4348765 DOI: 10.1104/pp.114.253120] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/24/2015] [Indexed: 05/20/2023]
Abstract
AvrE family type III effector proteins share the ability to suppress host defenses, induce disease-associated cell death, and promote bacterial growth. However, despite widespread contributions to numerous bacterial diseases in agriculturally important plants, the mode of action of these effectors remains largely unknown. WtsE is an AvrE family member required for the ability of Pantoea stewartii ssp. stewartii (Pnss) to proliferate efficiently and cause wilt and leaf blight symptoms in maize (Zea mays) plants. Notably, when WtsE is delivered by a heterologous system into the leaf cells of susceptible maize seedlings, it alone produces water-soaked disease symptoms reminiscent of those produced by Pnss. Thus, WtsE is a pathogenicity and virulence factor in maize, and an Escherichia coli heterologous delivery system can be used to study the activity of WtsE in isolation from other factors produced by Pnss. Transcriptional profiling of maize revealed the effects of WtsE, including induction of genes involved in secondary metabolism and suppression of genes involved in photosynthesis. Targeted metabolite quantification revealed that WtsE perturbs maize metabolism, including the induction of coumaroyl tyramine. The ability of mutant WtsE derivatives to elicit transcriptional and metabolic changes in susceptible maize seedlings correlated with their ability to promote disease. Furthermore, chemical inhibitors that block metabolic flux into the phenylpropanoid pathways targeted by WtsE also disrupted the pathogenicity and virulence activity of WtsE. While numerous metabolites produced downstream of the shikimate pathway are known to promote plant defense, our results indicate that misregulated induction of phenylpropanoid metabolism also can be used to promote pathogen virulence.
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Affiliation(s)
- Jo Ann E Asselin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Jinshan Lin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Alvaro L Perez-Quintero
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Irene Gentzel
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Doris Majerczak
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Stephen O Opiyo
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Wanying Zhao
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Seung-Mann Paek
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Min Gab Kim
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - David L Coplin
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - Joshua J Blakeslee
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
| | - David Mackey
- Department of Horticulture and Crop Science (J.E.A., J.L., A.L.P.-Q., Do.M., W.Z., J.J.B., Da.M.), Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center (J.L., S.O.O., J.J.B.), Translational Plant Sciences Graduate Program (I.G.), Center for Applied Plant Sciences (I.G., Da.M.), Department of Plant Pathology (D.L.C.), and Department of Molecular Genetics (Da.M.), Ohio State University, Columbus, Ohio 43210; andCollege of Pharmacy, Research Institute of Pharmaceutical Science, Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-751, Republic of Korea (S.-M.P., M.G.K.)
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Buonaurio R, Moretti C, da Silva DP, Cortese C, Ramos C, Venturi V. The olive knot disease as a model to study the role of interspecies bacterial communities in plant disease. FRONTIERS IN PLANT SCIENCE 2015; 6:434. [PMID: 26113855 PMCID: PMC4461811 DOI: 10.3389/fpls.2015.00434] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/27/2015] [Indexed: 05/03/2023]
Abstract
There is an increasing interest in studying interspecies bacterial interactions in diseases of animals and plants as it is believed that the great majority of bacteria found in nature live in complex communities. Plant pathologists have thus far mainly focused on studies involving single species or on their interactions with antagonistic competitors. A bacterial disease used as model to study multispecies interactions is the olive knot disease, caused by Pseudomonas savastanoi pv. savastanoi (Psv). Knots caused by Psv in branches and other aerial parts of the olive trees are an ideal niche not only for the pathogen but also for many other plant-associated bacterial species, mainly belonging to the genera Pantoea, Pectobacterium, Erwinia, and Curtobacterium. The non-pathogenic bacterial species Erwinia toletana, Pantoea agglomerans, and Erwinia oleae, which are frequently isolated inside the olive knots, cooperate with Psv in modulating the disease severity. Co-inoculations of these species with Psv result in bigger knots and better bacterial colonization when compared to single inoculations. Moreover, harmless bacteria co-localize with the pathogen inside the knots, indicating the formation of stable bacterial consortia that may facilitate the exchange of quorum sensing signals and metabolites. Here we discuss the possible role of bacterial communities in the establishment and development of olive knot disease, which we believe could be taking place in many other bacterial plant diseases.
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Affiliation(s)
- Roberto Buonaurio
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
- *Correspondence: Roberto Buonaurio, Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Via Borgo XX Giugno, 74 06121 Perugia, Italy,
| | - Chiaraluce Moretti
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
| | | | - Chiara Cortese
- Dipartimento di Scienze Agrarie, Alimentari e Ambientali, Università degli Studi di Perugia, Perugia, Italy
| | - Cayo Ramos
- Instituto de Hortofruticultura Subtropical y Mediterránea La Mayora, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Vittorio Venturi
- Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
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Siamer S, Guillas I, Shimobayashi M, Kunz C, Hall MN, Barny MA. Expression of the bacterial type III effector DspA/E in Saccharomyces cerevisiae down-regulates the sphingolipid biosynthetic pathway leading to growth arrest. J Biol Chem 2014; 289:18466-77. [PMID: 24828506 DOI: 10.1074/jbc.m114.562769] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Erwinia amylovora, the bacterium responsible for fire blight, relies on a type III secretion system and a single injected effector, DspA/E, to induce disease in host plants. DspA/E belongs to the widespread AvrE family of type III effectors that suppress plant defense responses and promote bacterial growth following infection. Ectopic expression of DspA/E in plant or in Saccharomyces cerevisiae is toxic, indicating that DspA/E likely targets a cellular process conserved between yeast and plant. To unravel the mode of action of DspA/E, we screened the Euroscarf S. cerevisiae library for mutants resistant to DspA/E-induced growth arrest. The most resistant mutants (Δsur4, Δfen1, Δipt1, Δskn1, Δcsg1, Δcsg2, Δorm1, and Δorm2) were impaired in the sphingolipid biosynthetic pathway. Exogenously supplied sphingolipid precursors such as the long chain bases (LCBs) phytosphingosine and dihydrosphingosine also suppressed the DspA/E-induced yeast growth defect. Expression of DspA/E in yeast down-regulated LCB biosynthesis and induced a rapid decrease in LCB levels, indicating that serine palmitoyltransferase (SPT), the first and rate-limiting enzyme of the sphingolipid biosynthetic pathway, was repressed. SPT down-regulation was mediated by dephosphorylation and activation of Orm proteins that negatively regulate SPT. A Δcdc55 mutation affecting Cdc55-PP2A protein phosphatase activity prevented Orm dephosphorylation and suppressed DspA/E-induced growth arrest.
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Affiliation(s)
- Sabrina Siamer
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Isabelle Guillas
- Sorbonne Universités, UMR1166, Institut National de la Santé et de la recherche médicale-UPMC, Pitié-Salpétrière University Hospital, F75013, Paris, France
| | | | - Caroline Kunz
- Sorbonne Universités, UPMC University Paris 06, UFR 927, F-75005 Paris, France, and Muséum National d'Histoire Naturelle, UMR7245, Molécules de Communication et Adaptation des Micro-organismes, F-75005 Paris, France
| | - Michael N Hall
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Marie-Anne Barny
- From the Institut National de la Recherche Agronomique UMR1392, Institut d'Ecologie et des Sciences de l'Environnement, Université Pierre et Marie Curie (UPMC), Bât A 7ème Etage Case 237, 7 Quai St.-Bernard, 75252 Paris, France,
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28
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Gaucher M, Dugé de Bernonville T, Guyot S, Dat JF, Brisset MN. Same ammo, different weapons: enzymatic extracts from two apple genotypes with contrasted susceptibilities to fire blight (Erwinia amylovora) differentially convert phloridzin and phloretin in vitro. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 72:178-89. [PMID: 23561298 DOI: 10.1016/j.plaphy.2013.03.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 03/13/2013] [Indexed: 05/14/2023]
Abstract
The necrogenic bacterium Erwinia amylovora responsible for the fire blight disease causes cell death in apple tissues to enrich intercellular spaces with nutrients. Apple leaves contain large amounts of dihydrochalcones (DHCs), including phloridzin and its aglycone phloretin. Previous work showed an important decrease in the constitutive DHCs stock in infected leaves, probably caused by transformation reactions during the infection process. At least two flavonoid transformation pathways have been described so far: deglucosylation and oxidation. The aim of the present study was to determine whether DHCs are differentially converted in two apple genotypes displaying contrasted susceptibilities to the disease. Different analyses were performed: i) enzymatic activity assays in infected leaves, ii) identification/quantification of end-products obtained after in vitro enzymatic reactions with DHCs, iii) evaluation of the bactericidal activity of end-products. The results of the enzymatic assays showed that deglucosylation was dominant over oxidation in the susceptible genotype MM106 while the opposite was observed in the resistant genotype Evereste. These data were confirmed by LC-UV/Vis-MS analysis of in vitro reaction mixtures, especially because higher levels of o-quinoid oxidation products of phloretin were measured by using the enzymatic extracts of Evereste infected leaves. Their presence correlated well with a strong bactericidal activity of the reaction mixtures. Thus, our results suggest that a differential transformation of DHCs occur in apple genotypes with a potential involvement in the establishment of the susceptibility or the resistance to fire blight, through the release of glucose or of highly bactericidal compounds respectively.
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Affiliation(s)
- Matthieu Gaucher
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071 Angers, France; Université d'Angers, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071 Angers, France; Agrocampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, F-49071 Angers, France
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29
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Siamer S, Gaubert S, Boureau T, Brisset MN, Barny MA. Mutational analysis of a predicted double β-propeller domain of the DspA/E effector of Erwinia amylovora. FEMS Microbiol Lett 2013; 342:54-61. [PMID: 23421848 DOI: 10.1111/1574-6968.12108] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 02/07/2013] [Accepted: 02/18/2013] [Indexed: 12/11/2022] Open
Abstract
The bacterium Erwinia amylovora causes fire blight, an invasive disease that threatens apple trees, pear trees and other plants of the Rosaceae family. Erwinia amylovora pathogenicity relies on a type III secretion system and on a single effector DspA/E. This effector belongs to the widespread AvrE family of effectors whose biological function is unknown. In this manuscript, we performed a bioinformatic analysis of DspA/E- and AvrE-related effectors. Motif search identified nuclear localization signals, peroxisome targeting signals, endoplasmic reticulum membrane retention signals and leucine zipper motifs, but none of these motifs were present in all the AvrE-related effectors analysed. Protein threading analysis, however, predicted a conserved double β-propeller domain in the N-terminal part of all the analysed effector sequences. We then performed a random pentapeptide mutagenesis of DspA/E, which led to the characterization of 13 new altered proteins with a five amino acids insertion. Eight harboured the insertion inside the predicted β-propeller domain and six of these eight insertions impaired DspA/E stability or function. Conversely, the two remaining insertions generated proteins that were functional and abundantly secreted in the supernatant suggesting that these two insertions stabilized the protein.
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Hogan CS, Mole BM, Grant SR, Willis DK, Charkowski AO. The type III secreted effector DspE is required early in solanum tuberosum leaf infection by Pectobacterium carotovorum to cause cell death, and requires Wx(3-6)D/E motifs. PLoS One 2013; 8:e65534. [PMID: 23755246 PMCID: PMC3670860 DOI: 10.1371/journal.pone.0065534] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/29/2013] [Indexed: 11/23/2022] Open
Abstract
Pectobacterium species are enterobacterial plant-pathogens that cause soft rot disease in diverse plant species. Unlike hemi-biotrophic plant pathogenic bacteria, the type III secretion system (T3SS) of Pectobacterium carotovorum subsp. carotovorum (P. carotovorum) appears to secrete only one effector protein, DspE. Previously, we found that the T3SS regulator HrpL and the effector DspE are required for P. carotovorum pathogenesis on leaves. Here, we identified genes up-regulated by HrpL, visualized expression of dspE in leaves, and established that DspE causes host cell death. DspE required its full length and WxxxE-like motifs, which are characteristic of the AvrE-family effectors, for host cell death. We also examined expression in plant leaves and showed that hrpL is required for the expression of dspE and hrpN, and that the loss of a functional T3SS had unexpected effects on expression of other genes during leaf infection. These data support a model where P. carotovorum uses the T3SS early in leaf infection to initiate pathogenesis through elicitation of DspE-mediated host cell death.
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Affiliation(s)
- Clifford S. Hogan
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Beth M. Mole
- Department of Biology and Curriculum in Molecular Biology and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sarah R. Grant
- Department of Biology and Curriculum in Molecular Biology and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David K. Willis
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Vegetable Crops Research Unit, United States Department of Agriculture – Agricultural Research Service, Madison, Wisconsin, United States of America
| | - Amy O. Charkowski
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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Degrave A, Moreau M, Launay A, Barny MA, Brisset MN, Patrit O, Taconnat L, Vedel R, Fagard M. The bacterial effector DspA/E is toxic in Arabidopsis thaliana and is required for multiplication and survival of fire blight pathogen. MOLECULAR PLANT PATHOLOGY 2013; 14:506-17. [PMID: 23634775 PMCID: PMC6638835 DOI: 10.1111/mpp.12022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The type III effector DspA/E is an essential pathogenicity factor of the phytopathogenic bacterium Erwinia amylovora. We showed that DspA/E was required for transient bacterial growth in nonhost Arabidopsis thaliana leaves, as an E. amylovora dspA/E mutant was unable to grow. We expressed DspA/E in A. thaliana transgenic plants under the control of an oestradiol-inducible promoter, and found that DspA/E expressed in planta restored the growth of a dspA/E mutant. DspA/E expression in these transgenic plants led to the modulation by at least two-fold of the expression of 384 genes, mostly induced (324 genes). Both induced and repressed genes contained high proportions of defence genes. DspA/E expression ultimately resulted in plant cell death without requiring a functional salicylic acid signalling pathway. Analysis of A. thaliana transgenic seedlings expressing a green fluorescent protein (GFP):DspA/E fusion indicated that the fusion protein could only be detected in a few cells per seedling, suggesting the degradation or absence of accumulation of DspA/E in plant cells. Consistently, we found that DspA/E repressed plant protein synthesis when injected by E. amylovora or when expressed in transgenic plants. Thus, we conclude that DspA/E is toxic to A. thaliana: it promotes modifications, among which the repression of protein synthesis could be determinant in the facilitation of necrosis and bacterial growth.
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Affiliation(s)
- Alexandre Degrave
- INRA, Laboratoire des Interactions Plantes Pathogènes, UMR217 Paris, France
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Vrancken K, Holtappels M, Schoofs H, Deckers T, Valcke R. Pathogenicity and infection strategies of the fire blight pathogen Erwinia amylovora in Rosaceae: State of the art. Microbiology (Reading) 2013; 159:823-832. [DOI: 10.1099/mic.0.064881-0] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- K. Vrancken
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Agoralaan gebouw D, 3590 Diepenbeek, Belgium
| | - M. Holtappels
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Agoralaan gebouw D, 3590 Diepenbeek, Belgium
| | - H. Schoofs
- Pomology department, PCFruit Research Station, Fruittuinweg 1, 3800 Sint-Truiden, Belgium
| | - T. Deckers
- Pomology department, PCFruit Research Station, Fruittuinweg 1, 3800 Sint-Truiden, Belgium
| | - R. Valcke
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Agoralaan gebouw D, 3590 Diepenbeek, Belgium
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Iakimova ET, Sobiczewski P, Michalczuk L, Węgrzynowicz-Lesiak E, Mikiciński A, Woltering EJ. Morphological and biochemical characterization of Erwinia amylovora-induced hypersensitive cell death in apple leaves. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 63:292-305. [PMID: 23321023 DOI: 10.1016/j.plaphy.2012.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 12/19/2012] [Indexed: 05/20/2023]
Abstract
In attached apple leaves, spot-inoculated with Erwinia amylovora, the phenotypic appearance of the hypersensitive response (HR) and the participation of ethylene, reactive oxygen species (ROS) and of vacuolar processing enzyme (VPE) (a plant caspase-1-like protease) were analysed. The HR in both the resistant and susceptible genotypes expressed a similar pattern of distinguishable micro HR lesions that progressed into confined macro HR lesions. The HR symptoms in apple were compared to those in non-host tobacco. The morphology of dead cells (protoplast shrinkage and retraction from cell wall) in apple leaves resembled necrotic programmed cell death (PCD). Lesion formation in both cv. Free Redstar (resistant) and cv. Idared (highly susceptible) was preceded by ROS accumulation and elevation of ethylene levels. Treatment of infected leaves with an inhibitor of ethylene synthesis led to a decrease of ethylene emission and suppression of lesion development in both cultivars. In the resistant but not in the susceptible apple cultivar an early and late increase in VPE gene expression was detected. This suggests that VPE might be an underlying component of the response to E. amylovora in resistant apple cultivars. The findings show that in the studied pathosystem the cell death during the HR proceeds through a signal transduction cascade in which ROS, ethylene and VPE pathways play a role.
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Global small RNA chaperone Hfq and regulatory small RNAs are important virulence regulators in Erwinia amylovora. J Bacteriol 2013; 195:1706-17. [PMID: 23378513 DOI: 10.1128/jb.02056-12] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Hfq is a global small RNA (sRNA) chaperone that interacts with Hfq-regulated sRNAs and functions in the posttranscriptional regulation of gene expression. In this work, we identified Hfq to be a virulence regulator in the Gram-negative fire blight pathogen Erwinia amylovora. Deletion of hfq in E. amylovora Ea1189 significantly reduced bacterial virulence in both immature pear fruits and apple shoots. Analysis of virulence determinants in strain Ea1189Δhfq showed that Hfq exerts pleiotropic regulation of amylovoran exopolysaccharide production, biofilm formation, motility, and the type III secretion system (T3SS). Further characterization of biofilm regulation by Hfq demonstrated that Hfq limits bacterial attachment to solid surfaces while promoting biofilm maturation. Characterization of T3SS regulation by Hfq revealed that Hfq positively regulates the translocation and secretion of the major type III effector DspE and negatively controls the secretion of the putative translocator HrpK and the type III effector Eop1. Lastly, 10 Hfq-regulated sRNAs were identified using a computational method, and two of these sRNAs, RprA and RyhA, were found to be required for the full virulence of E. amylovora.
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Dugé De Bernonville T, Gaucher M, Flors V, Gaillard S, Paulin JP, Dat JF, Brisset MN. T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 188-189:1-9. [PMID: 22525238 DOI: 10.1016/j.plantsci.2012.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 02/13/2012] [Accepted: 02/14/2012] [Indexed: 05/13/2023]
Abstract
Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea.
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Affiliation(s)
- Thomas Dugé De Bernonville
- Institut de Recherche en Horticulture et Semences, UMR INRA/Agrocampus Ouest/Université d'Angers, F-49071 Angers, France.
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Pester D, Milčevičová R, Schaffer J, Wilhelm E, Blümel S. Erwinia amylovora expresses fast and simultaneously hrp/dsp virulence genes during flower infection on apple trees. PLoS One 2012; 7:e32583. [PMID: 22412891 PMCID: PMC3295760 DOI: 10.1371/journal.pone.0032583] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2011] [Accepted: 01/28/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Pathogen entry through host blossoms is the predominant infection pathway of the gram-negative bacterium Erwinia amylovora leading to manifestation of the disease fire blight. Like in other economically important plant pathogens, E. amylovora pathogenicity depends on a type III secretion system encoded by hrp genes. However, timing and transcriptional order of hrp gene expression during flower infections are unknown. METHODOLOGY/PRINCIPAL FINDINGS Using quantitative real-time PCR analyses, we addressed the questions of how fast, strong and uniform key hrp virulence genes and the effector dspA/E are expressed when bacteria enter flowers provided with the full defense mechanism of the apple plant. In non-invasive bacterial inoculations of apple flowers still attached to the tree, E. amylovora activated expression of key type III secretion genes in a narrow time window, mounting in a single expression peak of all investigated hrp/dspA/E genes around 24-48 h post inoculation (hpi). This single expression peak coincided with a single depression in the plant PR-1 expression at 24 hpi indicating transient manipulation of the salicylic acid pathway as one target of E. amylovora type III effectors. Expression of hrp/dspA/E genes was highly correlated to expression of the regulator hrpL and relative transcript abundances followed the ratio: hrpA>hrpN>hrpL>dspA/E. Acidic conditions (pH 4) in flower infections led to reduced virulence/effector gene expression without the typical expression peak observed under natural conditions (pH 7). CONCLUSION/SIGNIFICANCE The simultaneous expression of hrpL, hrpA, hrpN, and the effector dspA/E during early floral infection indicates that speed and immediate effector transmission is important for successful plant invasion. When this delicate balance is disturbed, e.g., by acidic pH during infection, virulence gene expression is reduced, thus partly explaining the efficacy of acidification in fire blight control on a molecular level.
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Affiliation(s)
- Doris Pester
- Institute of Plant Health, Austrian Agency for Health and Food Safety (AGES), Vienna, Austria.
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Malnoy M, Martens S, Norelli JL, Barny MA, Sundin GW, Smits THM, Duffy B. Fire blight: applied genomic insights of the pathogen and host. ANNUAL REVIEW OF PHYTOPATHOLOGY 2012; 50:475-94. [PMID: 22702352 DOI: 10.1146/annurev-phyto-081211-172931] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The enterobacterial phytopathogen Erwinia amylovora causes fire blight, an invasive disease that threatens a wide range of commercial and ornamental Rosaceae host plants. The response elicited by E. amylovora in its host during disease development is similar to the hypersensitive reaction that typically leads to resistance in an incompatible host-pathogen interaction, yet no gene-for-gene resistance has been described for this host-pathogen system. Comparative genomic analysis has found an unprecedented degree of genetic uniformity among strains of E. amylovora, suggesting that the pathogen has undergone a recent genetic bottleneck. The genome of apple, an important host of E. amylovora, has been sequenced, creating new opportunities for the study of interactions between host and pathogen during fire blight development and for the identification of resistance genes. This review includes recent advances in the genomics of both host and pathogen.
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Affiliation(s)
- Mickael Malnoy
- Department of Biology and Genomics of Fruit Plants, FEM IASMA Research and Innovation Center, Foundation Edmund Mach di San Michele all'Adige, Trento, Italy.
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Siamer S, Patrit O, Fagard M, Belgareh-Touzé N, Barny MA. Expressing the Erwinia amylovora type III effector DspA/E in the yeast Saccharomyces cerevisiae strongly alters cellular trafficking. FEBS Open Bio 2011; 1:23-8. [PMID: 23650572 PMCID: PMC3642059 DOI: 10.1016/j.fob.2011.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/02/2011] [Accepted: 11/03/2011] [Indexed: 11/18/2022] Open
Abstract
Erwinia amylovora is responsible for fire blight, a necrotic disease of apples and pears. E. amylovora relies on a type III secretion system (T3SS) to induce disease on host plants. DspA/E belongs to the AvrE family of type III effector. Effectors of the AvrE family are injected via the T3SS in plant cell and are important to promote bacterial growth following infection and to suppress plant defense responses. Their mode of action in the plant cells is unknown. Here we study the physiological effects induced by dspA/E expression in the yeast Saccharomyces cerevisiae. Expression of dspA/E in the yeast inhibits cell growth. This growth inhibition is associated with perturbations of the actin cytoskeleton and endocytosis.
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Affiliation(s)
- Sabrina Siamer
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Oriane Patrit
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Mathilde Fagard
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
| | - Naïma Belgareh-Touzé
- FRE 3354 CNRS/UPMC, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Marie-Anne Barny
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- UPMC, Université Paris VI, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
- Corresponding author at: AgroParisTech, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France. Fax: +33 1 44 08 16 98.
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Zhao Y, Qi M. Comparative Genomics of Erwinia amylovora and Related Erwinia Species-What do We Learn? Genes (Basel) 2011; 2:627-39. [PMID: 24710213 PMCID: PMC3927617 DOI: 10.3390/genes2030627] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 08/30/2011] [Accepted: 09/08/2011] [Indexed: 01/26/2023] Open
Abstract
Erwinia amylovora, the causal agent of fire blight disease of apples and pears, is one of the most important plant bacterial pathogens with worldwide economic significance. Recent reports on the complete or draft genome sequences of four species in the genus Erwinia, including E. amylovora, E. pyrifoliae, E. tasmaniensis, and E. billingiae, have provided us near complete genetic information about this pathogen and its closely-related species. This review describes in silico subtractive hybridization-based comparative genomic analyses of eight genomes currently available, and highlights what we have learned from these comparative analyses, as well as genetic and functional genomic studies. Sequence analyses reinforce the assumption that E. amylovora is a relatively homogeneous species and support the current classification scheme of E. amylovora and its related species. The potential evolutionary origin of these Erwinia species is also proposed. The current understanding of the pathogen, its virulence mechanism and host specificity from genome sequencing data is summarized. Future research directions are also suggested.
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Affiliation(s)
- Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
| | - Mingsheng Qi
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL 61801, USA.
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Kim HS, Thammarat P, Lommel SA, Hogan CS, Charkowski AO. 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 : MPMI 2011; 24:773-86. [PMID: 21469936 DOI: 10.1094/mpmi-06-10-0143] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
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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Affiliation(s)
- Hye-Sook Kim
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
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Boureau T, Siamer S, Perino C, Gaubert S, Patrit O, Degrave A, Fagard M, Chevreau E, Barny MA. The HrpN effector of Erwinia amylovora, which is involved in type III translocation, contributes directly or indirectly to callose elicitation on apple leaves. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:577-84. [PMID: 21463207 DOI: 10.1094/mpmi-09-10-0212] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Erwinia amylovora is responsible for fire blight of apple and pear trees. Its pathogenicity depends on a type III secretion system (T3SS) mediating the translocation of effectors into the plant cell. The DspA/E effector suppresses callose deposition on apple leaves. We found that E. amylovora and Pseudomonas syringae DC3000 tts mutants or peptide flg22 do not trigger callose deposition as strongly as the dspA/E mutant on apple leaves. This suggests that, on apple leaves, callose deposition is poorly elicited by pathogen-associated molecular patterns (PAMPs) such as flg22 or other PAMPs harbored by tts mutants and is mainly elicited by injected effectors or by the T3SS itself. Callose elicitation partly depends on HrpW because an hrpW-dspA/E mutant elicits lower callose deposition than a dspA/E mutant. Furthermore, an hrpN-dspA/E mutant does not trigger callose deposition, indicating that HrpN is required to trigger this plant defense reaction. We showed that HrpN plays a general role in the translocation process. Thus, the HrpN requirement for callose deposition may be explained by its role in translocation: HrpN could be involved in the translocation of other effectors inducing callose deposition. Furthermore, HrpN may also directly contribute to the elicitation process because we showed that purified HrpN induces callose deposition.
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Affiliation(s)
- Tristan Boureau
- INRA, UMR217, LIPP, 16 rue Claude Bernard, 75231 Paris cedex 05, France
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Sensing and adhesion are adaptive functions in the plant pathogenic xanthomonads. BMC Evol Biol 2011; 11:67. [PMID: 21396107 PMCID: PMC3063832 DOI: 10.1186/1471-2148-11-67] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 03/11/2011] [Indexed: 11/26/2022] Open
Abstract
Background Bacterial plant pathogens belonging to the Xanthomonas genus are tightly adapted to their host plants and are not known to colonise other environments. The host range of each strain is usually restricted to a few host plant species. Bacterial strains responsible for the same type of symptoms on the same host range cluster in a pathovar. The phyllosphere is a highly stressful environment, but it provides a selective habitat and a source of substrates for these bacteria. Xanthomonads colonise host phylloplane before entering leaf tissues and engaging in an invasive pathogenic phase. Hence, these bacteria are likely to have evolved strategies to adapt to life in this environment. We hypothesised that determinants responsible for bacterial host adaptation are expressed starting from the establishment of chemotactic attraction and adhesion on host tissue. Results We established the distribution of 70 genes coding sensors and adhesins in a large collection of xanthomonad strains. These 173 strains belong to different pathovars of Xanthomonas spp and display different host ranges. Candidate genes are involved in chemotactic attraction (25 genes), chemical environment sensing (35 genes), and adhesion (10 genes). Our study revealed that candidate gene repertoires comprised core and variable gene suites that likely have distinct roles in host adaptation. Most pathovars were characterized by unique repertoires of candidate genes, highlighting a correspondence between pathovar clustering and repertoires of sensors and adhesins. To further challenge our hypothesis, we tested for molecular signatures of selection on candidate genes extracted from sequenced genomes of strains belonging to different pathovars. We found strong evidence of adaptive divergence acting on most candidate genes. Conclusions These data provide insight into the potential role played by sensors and adhesins in the adaptation of xanthomonads to their host plants. The correspondence between repertoires of sensor and adhesin genes and pathovars and the rapid evolution of sensors and adhesins shows that, for plant pathogenic xanthomonads, events leading to host specificity may occur as early as chemotactic attraction by host and adhesion to tissues.
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Darrasse A, Darsonval A, Boureau T, Brisset MN, Durand K, Jacques MA. Transmission of plant-pathogenic bacteria by nonhost seeds without induction of an associated defense reaction at emergence. Appl Environ Microbiol 2010; 76:6787-96. [PMID: 20729326 PMCID: PMC2953029 DOI: 10.1128/aem.01098-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Accepted: 07/28/2010] [Indexed: 11/20/2022] Open
Abstract
An understanding of the mechanisms involved in the different steps of bacterial disease epidemiology is essential to develop new control strategies. Seeds are the passive carriers of a diversified microbial cohort likely to affect seedling physiology. Among seed-borne plant-pathogenic bacteria, seed carriage in compatible situations is well evidenced. The aims of our work are to determine the efficiency of pathogen transmission to seeds of a nonhost plant and to evaluate bacterial and plant behaviors at emergence. Bacterial transmission from flowers to seeds and from seeds to seedlings was measured for Xanthomonas campestris pv. campestris in incompatible interactions with bean. Transmissions from seeds to seedlings were compared for X. campestris pv. campestris, for Xanthomonas citri pv. phaseoli var. fuscans in compatible interactions with bean, and for Escherichia coli, a human pathogen, in null interactions with bean. The induction of defense responses was monitored by using reverse transcription and quantitative PCR (RT-qPCR) of genes representing the main signaling pathways and assaying defense-related enzymatic activities. Flower inoculations resulted in a high level of bean seed contamination by X. campestris pv. campestris, which transmitted efficiently to seedlings. Whatever the type of interaction tested, dynamics of bacterial population sizes were similar on seedlings, and no defense responses were induced evidencing bacterial colonization of seedlings without any associated defense response induction. Bacteria associated with the spermosphere multiply in this rich environment, suggesting that the colonization of seedlings relies mostly on commensalism. The transmission of plant-pathogenic bacteria to and by nonhost seeds suggests a probable role of seeds of nonhost plants as an inoculum source.
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Macho AP, Guidot A, Barberis P, Beuzón CR, Genin S. A competitive index assay identifies several Ralstonia solanacearum type III effector mutant strains with reduced fitness in host plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1197-205. [PMID: 20687809 DOI: 10.1094/mpmi-23-9-1197] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Ralstonia solanacearum, the causal agent of bacterial wilt, is a soil bacterium which can naturally infect a wide range of host plants through the root system. Pathogenicity relies on a type III secretion system which delivers a large set of approximately 75 type III effectors (T3E) into plant cells. On several plants, pathogenicity assays based on quantification of wilting symptoms failed to detect a significant contribution of R. solanacearum T3E in this process, thus revealing the collective effect of T3E in pathogenesis. We developed a mixed infection-based method with R. solanacearum to monitor bacterial fitness in plant leaf tissues as a virulence assay. This accurate and sensitive assay provides evidence that growth defects can be detected for T3E mutants: we identified 12 genes contributing to bacterial fitness in eggplant leaves and 3 of them were also implicated in bacterial fitness on two other hosts, tomato and bean. Contribution to fitness of several T3E appears to be host specific, and we show that some known avirulence determinants such as popP2 or avrA do provide competitive advantages on some susceptible host plants. In addition, this assay revealed that the efe gene, which directs the production of ethylene by bacteria in plant tissues, and hdfB, involved in the biosynthesis of the secondary metabolite 3-hydroxy-oxindole, are also required for optimal growth in plant leaf tissues.
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Affiliation(s)
- Alberto P Macho
- Instituto de Hortifruticultura Subtropical y Mediterranea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Depto. Biología Celular, Genética y Fisiología, Campus de Teatinos, Málaga E-29071, Spain
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Triplett LR, Wedemeyer WJ, Sundin GW. Homology-based modeling of the Erwinia amylovora type III secretion chaperone DspF used to identify amino acids required for virulence and interaction with the effector DspE. Res Microbiol 2010; 161:613-8. [PMID: 20600860 DOI: 10.1016/j.resmic.2010.05.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 05/21/2010] [Accepted: 05/24/2010] [Indexed: 01/02/2023]
Abstract
The structure of DspF, a type III secretion system (T3SS) chaperone required for virulence of the fruit tree pathogen Erwinia amylovora, was modeled based on predicted structural homology to characterized T3SS chaperones. This model guided the selection of 11 amino acid residues that were individually mutated to alanine via site-directed mutagenesis. Each mutant was assessed for its effect on virulence complementation, dimerization and interaction with the N-terminal chaperone-binding site of DspE. Four amino acid residues were identified that did not complement the virulence defect of a dspF knockout mutant, and three of these residues were required for interaction with the N-terminus of DspE. This study supports the significance of the predicted beta-sheet helix-binding groove in DspF chaperone function.
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Affiliation(s)
- Lindsay R Triplett
- Department of Plant Pathology, Michigan State University, 103 Center for Integrated Plant Systems, East Lansing, MI 48824, USA
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Smits THM, Rezzonico F, Kamber T, Blom J, Goesmann A, Frey JE, Duffy B. Complete genome sequence of the fire blight pathogen Erwinia amylovora CFBP 1430 and comparison to other Erwinia spp. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:384-393. [PMID: 20192826 DOI: 10.1094/mpmi-23-4-0384] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Fire blight, caused by the enterobacterium Erwinia amylovora, is a devastating disease of rosaceous plants that has global economic importance for apple and pear production and trade. The complete genome of E. amylovora CFBP 1430 was sequenced, annotated, and compared with the genomes of other Erwinia spp. Several singleton and shared features of the E. amylovora CFBP 1430 genome were identified that offer a first view into evolutionary aspects within the genus Erwinia. Comparative genomics identified or clarified virulence and fitness determinants and secretion systems. Novel insights revealed in the genome of E. amylovora CFBP 1430 hold potential for exploitation to improve the design of more effective fire blight control strategies.
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Affiliation(s)
- Theo H M Smits
- Agroscope Changins-Wädenswil ACW, Division of Plant Protection, Swiss National Competence Center for Fire Blight, Wädenswil, Switzerland
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Oh CS, Carpenter SCD, Hayes ML, Beer SV. Secretion and translocation signals and DspB/F-binding domains in the type III effector DspA/E of Erwinia amylovora. MICROBIOLOGY (READING, ENGLAND) 2010; 156:1211-1220. [PMID: 20110301 DOI: 10.1099/mic.0.027144-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
DspA/E is a type III effector of Erwinia amylovora, the bacterial pathogen that causes fire blight disease in roseaceous plants. This effector is indispensable for disease development, and it is translocated into plant cells. A DspA/E-specific chaperone, DspB/F, is necessary for DspA/E secretion and possibly for its translocation. In this work, DspB/F-binding sites and secretion and translocation signals in the DspA/E protein were determined. Based on yeast two-hybrid assays, DspB/F was found to bind DspA/E within the first 210 amino acids of the protein. Surprisingly, both DspB/F and OrfA, the putative chaperone of Eop1, also interacted with the C-terminal 1059 amino acids of DspA/E; this suggests another chaperone-binding site. Secretion and translocation assays using serial N-terminal lengths of DspA/E fused with the active form of AvrRpt2 revealed that at least the first 109 amino acids, including the first N-terminal chaperone-binding motif and DspB/F, were required for efficient translocation of DspA/E, although the first 35 amino acids were sufficient for its secretion and the presence of DspB/F was not required. These results indicate that secretion and translocation signals are present in the N terminus of DspA/E, and that at least one DspB/F-binding motif is required for efficient translocation into plant cells.
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Affiliation(s)
- Chang-Sik Oh
- Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA
| | - Sara C D Carpenter
- Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA
| | - Marshall L Hayes
- Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA
| | - Steven V Beer
- Department of Plant Pathology and Plant Microbe-Biology, Cornell University, Ithaca, NY 14853, USA
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Wang D, Korban SS, Zhao Y. Molecular signature of differential virulence in natural isolates of Erwinia amylovora. PHYTOPATHOLOGY 2010; 100:192-8. [PMID: 20055653 DOI: 10.1094/phyto-100-2-0192] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
ABSTRACT Erwinia amylovora, the causal agent of fire blight, is considered to be a genetically homogeneous species based on physiological, biochemical, phylogenetic, and genetic analysis. However, E. amylovora strains exhibiting differential virulence are isolated from nature. The exopolysaccharide amylovoran and type III secretion system (T3SS) are two major yet separate virulence factors in E. amylovora. The objective of this study was to investigate whether there is a correlation between E. amylovora virulence and levels of virulence gene expression. Four wild-type strains (Ea1189, Ea273, Ea110, and CFBP1430), widely used in studies of E. amylovora pathogenesis, have been analyzed and compared. E. amylovora strains Ea273 and Ea110 elicited higher severity of disease symptoms than those of Ea1189 and CFBP1430 on apple cv. Golden Delicious and G16 apple root stock plants but not on susceptible Gala plants. In addition, Ea273 and Ea110 elicited severe hypersensitive responses within shorter periods of time at lower inoculum concentrations than those of Ea1189 and CFBP1430 on tobacco plants. Further molecular analyses have revealed that amylovoran production and expression of both amylovoran (amsG) and T3SS (dspE and hrpL) genes were significantly higher in Ea273 and Ea110 than those in Ea1189 and CFBP1430. Other phenotypes such as swarming motility in these four strains also differed significantly. These results indicate that E. amylovora strains of different origin can be divided into subgroups based on molecular signatures of virulence gene expression. Therefore, these molecular signatures may be used to differentiate E. amylovora strains, which may have taxonomical and evolutionary implications.
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Affiliation(s)
- Dongping Wang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana 61801, USA
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Smits THM, Jaenicke S, Rezzonico F, Kamber T, Goesmann A, Frey JE, Duffy B. Complete genome sequence of the fire blight pathogen Erwinia pyrifoliae DSM 12163T and comparative genomic insights into plant pathogenicity. BMC Genomics 2010; 11:2. [PMID: 20047678 PMCID: PMC2827408 DOI: 10.1186/1471-2164-11-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 01/04/2010] [Indexed: 11/10/2022] Open
Abstract
Background Erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on Asian (Nashi) pear and is geographically restricted to Eastern Asia. Relatively little is known about its genetics compared to the closely related main fire blight pathogen E. amylovora. Results The genome of the type strain of E. pyrifoliae strain DSM 12163T, was sequenced using both 454 and Solexa pyrosequencing and annotated. The genome contains a circular chromosome of 4.026 Mb and four small plasmids. Based on their respective role in virulence in E. amylovora or related organisms, we identified several putative virulence factors, including type III and type VI secretion systems and their effectors, flagellar genes, sorbitol metabolism, iron uptake determinants, and quorum-sensing components. A deletion in the rpoS gene covering the most conserved region of the protein was identified which may contribute to the difference in virulence/host-range compared to E. amylovora. Comparative genomics with the pome fruit epiphyte Erwinia tasmaniensis Et1/99 showed that both species are overall highly similar, although specific differences were identified, for example the presence of some phage gene-containing regions and a high number of putative genomic islands containing transposases in the E. pyrifoliae DSM 12163T genome. Conclusions The E. pyrifoliae genome is an important addition to the published genome of E. tasmaniensis and the unfinished genome of E. amylovora providing a foundation for re-sequencing additional strains that may shed light on the evolution of the host-range and virulence/pathogenicity of this important group of plant-associated bacteria.
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Affiliation(s)
- Theo H M Smits
- Swiss National Competence Center for Fire Blight, Division of Plant Protection, Agroscope Changins-Wädenswil ACW, Wädenswil, Switzerland
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Triplett LR, Melotto M, Sundin GW. Functional analysis of the N terminus of the Erwinia amylovora secreted effector DspA/E reveals features required for secretion, translocation, and binding to the chaperone DspB/F. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1282-92. [PMID: 19737101 DOI: 10.1094/mpmi-22-10-1282] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
DspA/E is a type III secreted effector protein required for pathogenicity in the apple and pear pathogen Erwinia amylovora, and DspB/F is a small chaperone protein involved in DspA/E secretion. While the secretion and translocation signals of many type III secretion effector proteins in human enteric pathogens have been characterized extensively, relatively little is known about the translocation requirements of many effectors in plant pathogens, including large DspE-like proteins. In this study, we report a functional analysis of the N terminus of DspE. The minimal requirements for secretion, translocation, and chaperone binding were characterized. Translocation assays using an adenylate cyclase (CyaA) reporter indicated that the first 51 amino acids of DspE were sufficient for translocation and that 150 amino acids were required for optimal translocation levels. The minimal translocation signal corresponded with the requirements for secretion into culture media. Mutations of conserved regions in amino acids 2 through 10 and 31 through 40 were found to influence translocation levels of an N-terminal DspE-CyaA fusion. Yeast two-hybrid and in-vitro pull-down assays revealed a chaperone-binding site within amino acids 51 through 100 of DspE and binding to DspF in this region was disrupted by specific mutations. However, neither disruption of the chaperone-binding domain nor deletion of the dspF gene had a significant impact on translocation levels of N-terminal DspE-CyaA fusions. Our results indicate that the minimal translocation signal of DspE is not coincident with the signal for DspF binding and that translocation of the N terminus of DspE is not dependent on the N-terminal DspF-binding domain.
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Affiliation(s)
- Lindsay R Triplett
- Department of Plant Pathology, Michigan State University, East Lansing, MI 48824, USA
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