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Huang J, Zhou H, Zhou M, Li N, Jiang B, He Y. Functional Analysis of Type III Effectors in Xanthomonas campestris pv. campestris Reveals Distinct Roles in Modulating Arabidopsis Innate Immunity. Pathogens 2024; 13:448. [PMID: 38921746 PMCID: PMC11206781 DOI: 10.3390/pathogens13060448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 05/19/2024] [Accepted: 05/23/2024] [Indexed: 06/27/2024] Open
Abstract
Xanthomonas campestris pv. campestris (Xcc) is a significant phytopathogen causing black rot disease in crucifers. Its virulence relies heavily on the type III secretion system (T3SS), facilitating effector translocation into plant cells. The type III effectors (T3Es) disrupt cellular processes, promoting pathogen proliferation. However, only a few T3Es from Xcc have been thoroughly characterized. In this study, we further investigated two effectors using the T3Es-deficient mutant and the Arabidopsis protoplast system. XopE2Xcc triggers Arabidopsis immune responses via an unidentified activator of the salicylic acid (SA) signaling pathway, whereas XopLXcc suppresses the expression of genes associated with patterns-triggered immunity (PTI) and the SA signaling pathway. These two effectors exert opposing effects on Arabidopsis immune responses. Additionally, we examined the relationship between the specific domains and functions of these two effector proteins. Our findings demonstrate that the N-myristoylation motif and N-terminal domain are essential for the subcellular localization and virulence of XopE2Xcc and XopLXcc, respectively. These novel insights enhance our understanding of the pathogenic mechanisms of T3Es and contribute to developing effective strategies for controlling bacterial disease.
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Affiliation(s)
- Jing Huang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
| | - Hao Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
- Guangxi Key Laboratory for Polysaccharide Materials and Modifications, Guangxi Minzu University, Nanning 530006, China
| | - Min Zhou
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
| | - Nana Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
| | - Bole Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
| | - Yongqiang He
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530005, China; (J.H.); (B.J.)
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Fernandes AS, Campos KF, de Assis JCS, Gonçalves OS, Queiroz MVD, Bazzolli DMS, Santana MF. Investigating the impact of insertion sequences and transposons in the genomes of the most significant phytopathogenic bacteria. Microb Genom 2024; 10. [PMID: 38568199 DOI: 10.1099/mgen.0.001219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
Abstract
Genetic variability in phytopathogens is one of the main problems encountered for effective plant disease control. This fact may be related to the presence of transposable elements (TEs), but little is known about their role in host genomes. Here, we performed the most comprehensive analysis of insertion sequences (ISs) and transposons (Tns) in the genomes of the most important bacterial plant pathogens. A total of 35 692 ISs and 71 transposons were identified in 270 complete genomes. The level of pathogen-host specialization was found to be a significant determinant of the element distribution among the species. Some Tns were identified as carrying virulence factors, such as genes encoding effector proteins of the type III secretion system and resistance genes for the antimicrobial streptomycin. Evidence for IS-mediated ectopic recombination was identified in Xanthomonas genomes. Moreover, we found that IS elements tend to be inserted in regions near virulence and fitness genes, such ISs disrupting avirulence genes in X. oryzae genomes. In addition, transcriptome analysis under different stress conditions revealed differences in the expression of genes encoding transposases in the Ralstonia solanacearum, X. oryzae, and P. syringae species. Lastly, we also investigated the role of Tns in regulation via small noncoding regulatory RNAs and found these elements may target plant-cell transcriptional activators. Taken together, the results indicate that TEs may have a fundamental role in variability and virulence in plant pathogenic bacteria.
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Goettelmann F, Koebnik R, Roman-Reyna V, Studer B, Kölliker R. High genomic plasticity and unique features of Xanthomonas translucens pv. graminis revealed through comparative analysis of complete genome sequences. BMC Genomics 2023; 24:741. [PMID: 38053038 DOI: 10.1186/s12864-023-09855-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023] Open
Abstract
BACKGROUND Xanthomonas translucens pv. graminis (Xtg) is a major bacterial pathogen of economically important forage grasses, causing severe yield losses. So far, genomic resources for this pathovar consisted mostly of draft genome sequences, and only one complete genome sequence was available, preventing comprehensive comparative genomic analyses. Such comparative analyses are essential in understanding the mechanisms involved in the virulence of pathogens and to identify virulence factors involved in pathogenicity. RESULTS In this study, we produced high-quality, complete genome sequences of four strains of Xtg, complementing the recently obtained complete genome sequence of the Xtg pathotype strain. These genomic resources allowed for a comprehensive comparative analysis, which revealed a high genomic plasticity with many chromosomal rearrangements, although the strains were highly related. A high number of transposases were exclusively found in Xtg and corresponded to 413 to 457 insertion/excision transposable elements per strain. These mobile genetic elements are likely to be involved in the observed genomic plasticity and may play an important role in the adaptation of Xtg. The pathovar was found to lack a type IV secretion system, and it possessed the smallest set of type III effectors in the species. However, three XopE and XopX family effectors were found, while in the other pathovars of the species two or less were present. Additional genes that were specific to the pathovar were identified, including a unique set of minor pilins of the type IV pilus, 17 TonB-dependent receptors (TBDRs), and 11 plant cell wall degradative enzymes. CONCLUSION These results suggest a high adaptability of Xtg, conferred by the abundance of mobile genetic elements, which could play a crucial role in pathogen adaptation. The large amount of such elements in Xtg compared to other pathovars of the species could, at least partially, explain its high virulence and broad host range. Conserved features that were specific to Xtg were identified, and further investigation will help to determine genes that are essential to pathogenicity and host adaptation of Xtg.
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Affiliation(s)
- Florian Goettelmann
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Ralf Koebnik
- Plant Health Institute of Montpellier, University of Montpellier, CIRAD, INRAE, Institut Agro, IRD, Montpellier, France
| | - Veronica Roman-Reyna
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA, USA
| | - Bruno Studer
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland
| | - Roland Kölliker
- Molecular Plant Breeding, Institute of Agricultural Sciences, ETH Zurich, Zurich, Switzerland.
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Kim B, Kim I, Yu W, Li M, Kim H, Ahn YJ, Sohn KH, Macho AP, Segonzac C. The Ralstonia pseudosolanacearum effector RipE1 is recognized at the plasma membrane by NbPtr1, the Nicotiana benthamiana homologue of Pseudomonas tomato race 1. MOLECULAR PLANT PATHOLOGY 2023; 24:1312-1318. [PMID: 37310613 PMCID: PMC10502825 DOI: 10.1111/mpp.13363] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/07/2023] [Accepted: 05/22/2023] [Indexed: 06/14/2023]
Abstract
The bacterial wilt disease caused by soilborne bacteria of the Ralstonia solanacearum species complex (RSSC) threatens important crops worldwide. Only a few immune receptors conferring resistance to this devastating disease are known so far. Individual RSSC strains deliver around 70 different type III secretion system effectors into host cells to manipulate the plant physiology. RipE1 is an effector conserved across the RSSC and triggers immune responses in the model solanaceous plant Nicotiana benthamiana. Here, we used multiplexed virus-induced gene silencing of the nucleotide-binding and leucine-rich repeat receptor family to identify the genetic basis of RipE1 recognition. Specific silencing of the N. benthamiana homologue of Solanum lycopersicoides Ptr1 (confers resistance to Pseudomonas syringae pv. tomato race 1) gene (NbPtr1) completely abolished RipE1-induced hypersensitive response and immunity to Ralstonia pseudosolanacearum. The expression of the native NbPtr1 coding sequence was sufficient to restore RipE1 recognition in Nb-ptr1 knockout plants. Interestingly, RipE1 association with the host cell plasma membrane was necessary for NbPtr1-dependent recognition. Furthermore, NbPtr1-dependent recognition of RipE1 natural variants is polymorphic, providing additional evidence for the indirect mode of activation of NbPtr1. Altogether, this work supports NbPtr1 relevance for resistance to bacterial wilt disease in Solanaceae.
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Affiliation(s)
- Boyoung Kim
- Department of Agriculture, Forestry and BioresourcesSeoul National UniversitySeoulRepublic of Korea
- Plant Immunity Research CenterSeoul National UniversitySeoulRepublic of Korea
| | - Injae Kim
- Department of Agriculture, Forestry and BioresourcesSeoul National UniversitySeoulRepublic of Korea
- Plant Immunity Research CenterSeoul National UniversitySeoulRepublic of Korea
| | - Wenjia Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Meng Li
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Haseong Kim
- Plant Immunity Research CenterSeoul National UniversitySeoulRepublic of Korea
| | - Ye Jin Ahn
- Department of Life SciencesPohang University of Science and TechnologyPohangRepublic of Korea
| | - Kee Hoon Sohn
- Plant Immunity Research CenterSeoul National UniversitySeoulRepublic of Korea
- Department of Agricultural BiotechnologySeoul National UniversitySeoulRepublic of Korea
- Research Institute of Agriculture and Life SciencesSeoul National UniversitySeoulRepublic of Korea
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghaiChina
| | - Cécile Segonzac
- Department of Agriculture, Forestry and BioresourcesSeoul National UniversitySeoulRepublic of Korea
- Plant Immunity Research CenterSeoul National UniversitySeoulRepublic of Korea
- Research Institute of Agriculture and Life SciencesSeoul National UniversitySeoulRepublic of Korea
- Plant Genomics and Breeding InstituteSeoul National UniversitySeoulRepublic of Korea
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Nielsen TK, Winther-Have CS, Thomsen IM, Jackson RW, Rabiey M, Hennessy RC, Bak F, Kot W, Nicolaisen MH, Carstens AB, Hansen LH. Genetic rearrangements in Pseudomonas amygdali pathovar aesculi shape coronatine plasmids. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023; 113:105486. [PMID: 37541538 DOI: 10.1016/j.meegid.2023.105486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/23/2023] [Accepted: 08/01/2023] [Indexed: 08/06/2023]
Abstract
Plant pathogenic Pseudomonas species use multiple classes of toxins and virulence factors during host infection. The genes encoding these pathogenicity factors are often located on plasmids and other mobile genetic elements, suggesting that they are acquired through horizontal gene transfer to confer an evolutionary advantage for successful adaptation to host infection. However, the genetic rearrangements that have led to mobilization of the pathogenicity genes are not fully understood. In this study, we have sequenced and analyzed the complete genome sequences of four Pseudomonas amygdali pv. aesculi (Pae), which infect European horse chestnut trees (Aesculus hippocastanum) and belong to phylogroup 3 of the P. syringae species complex. The four investigated genomes contain six groups of plasmids that all encode pathogenicity factors. Effector genes were found to be mostly associated with insertion sequence elements, suggesting that virulence genes are generally mobilized and potentially undergo horizontal gene transfer after transfer to a conjugative plasmid. We show that the biosynthetic gene cluster encoding the phytotoxin coronatine was recently transferred from a chromosomal location to a mobilizable plasmid that subsequently formed a co-integrate with a conjugative plasmid.
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Affiliation(s)
- Tue Kjærgaard Nielsen
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Caroline S Winther-Have
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark; Globe Institute, University of Copenhagen, 1350 Copenhagen, Denmark
| | - Iben Margrete Thomsen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, 1958 Frederiksberg C, Denmark
| | - Robert W Jackson
- School of Biosciences and the Birmingham Institute of Forest Research, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Mojgan Rabiey
- School of Biosciences and the Birmingham Institute of Forest Research, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | | | - Frederik Bak
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Witold Kot
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Mette Haubjerg Nicolaisen
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Alexander Byth Carstens
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark
| | - Lars Hestbjerg Hansen
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark.
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Kumar J, Ramlal A, Kumar K, Rani A, Mishra V. Signaling Pathways and Downstream Effectors of Host Innate Immunity in Plants. Int J Mol Sci 2021; 22:ijms22169022. [PMID: 34445728 PMCID: PMC8396522 DOI: 10.3390/ijms22169022] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Phytopathogens, such as biotrophs, hemibiotrophs and necrotrophs, pose serious stress on the development of their host plants, compromising their yields. Plants are in constant interaction with such phytopathogens and hence are vulnerable to their attack. In order to counter these attacks, plants need to develop immunity against them. Consequently, plants have developed strategies of recognizing and countering pathogenesis through pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Pathogen perception and surveillance is mediated through receptor proteins that trigger signal transduction, initiated in the cytoplasm or at the plasma membrane (PM) surfaces. Plant hosts possess microbe-associated molecular patterns (P/MAMPs), which trigger a complex set of mechanisms through the pattern recognition receptors (PRRs) and resistance (R) genes. These interactions lead to the stimulation of cytoplasmic kinases by many phosphorylating proteins that may also be transcription factors. Furthermore, phytohormones, such as salicylic acid, jasmonic acid and ethylene, are also effective in triggering defense responses. Closure of stomata, limiting the transfer of nutrients through apoplast and symplastic movements, production of antimicrobial compounds, programmed cell death (PCD) are some of the primary defense-related mechanisms. The current article highlights the molecular processes involved in plant innate immunity (PII) and discusses the most recent and plausible scientific interventions that could be useful in augmenting PII.
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Affiliation(s)
- Jitendra Kumar
- Bangalore Bioinnovation Centre, Life Sciences Park, Electronics City Phase 1, Bengaluru 560100, India;
| | - Ayyagari Ramlal
- Division of Genetics, Indian Agricultural Research Institute (IARI), Pusa Campus, New Delhi 110012, India;
| | - Kamal Kumar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110066, India;
| | - Anita Rani
- Department of Botany, Dyal Singh College, University of Delhi, Delhi 110003, India;
| | - Vachaspati Mishra
- Department of Botany, Dyal Singh College, University of Delhi, Delhi 110003, India;
- Correspondence:
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Viana F, Peringathara SS, Rizvi A, Schroeder GN. Host manipulation by bacterial type III and type IV secretion system effector proteases. Cell Microbiol 2021; 23:e13384. [PMID: 34392594 DOI: 10.1111/cmi.13384] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 01/08/2023]
Abstract
Proteases are powerful enzymes, which cleave peptide bonds, leading most of the time to irreversible fragmentation or degradation of their substrates. Therefore they control many critical cell fate decisions in eukaryotes. Bacterial pathogens exploit this power and deliver protease effectors through specialised secretion systems into host cells. Research over the past years revealed that the functions of protease effectors during infection are diverse, reflecting the lifestyles and adaptations to specific hosts; however, only a small number of peptidase families seem to have given rise to most of these protease virulence factors by the evolution of different substrate-binding specificities, intracellular activation and subcellular targeting mechanisms. Here, we review our current knowledge about the enzymology and function of protease effectors, which Gram-negative bacterial pathogens translocate via type III and IV secretion systems to irreversibly manipulate host processes. We highlight emerging concepts such as signalling by protease cleavage products and effector-triggered immunity, which host cells employ to detect and defend themselves against a protease attack. TAKE AWAY: Proteases irreversibly cleave proteins to control critical cell fate decisions. Gram-negative bacteria use type III and IV secretion systems to inject effectors. Protease effectors are integral weapons for the manipulation of host processes. Effectors evolved from few peptidase families to target diverse substrates. Effector-triggered immunity upon proteolytic attack emerges as host defence.
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Affiliation(s)
- Flávia Viana
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Shruthi Sachidanandan Peringathara
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Arshad Rizvi
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Gunnar N Schroeder
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
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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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9
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Mooney BC, Mantz M, Graciet E, Huesgen PF. Cutting the line: manipulation of plant immunity by bacterial type III effector proteases. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3395-3409. [PMID: 33640987 DOI: 10.1093/jxb/erab095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Pathogens and their hosts are engaged in an evolutionary arms race. Pathogen-derived effectors promote virulence by targeting components of a host's innate immune system, while hosts have evolved proteins that sense effectors and trigger a pathogen-specific immune response. Many bacterial effectors are translocated into host cells using type III secretion systems. Type III effector proteases irreversibly modify host proteins by cleavage of peptide bonds and are prevalent among both plant and animal bacterial pathogens. In plants, the study of model effector proteases has yielded important insights into the virulence mechanisms employed by pathogens to overcome their host's immune response, as well as into the mechanisms deployed by their hosts to detect these effector proteases and counteract their effects. In recent years, the study of a larger number of effector proteases, across a wider range of pathogens, has yielded novel insights into their functions and recognition. One key limitation that remains is the lack of methods to detect protease cleavage at the proteome-wide level. We review known substrates and mechanisms of plant pathogen type III effector proteases and compare their functions with those of known type III effector proteases of mammalian pathogens. Finally, we discuss approaches to uncover their function on a system-wide level.
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Affiliation(s)
- Brian C Mooney
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Melissa Mantz
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
| | - Emmanuelle Graciet
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
- Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Pitter F Huesgen
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
- Institute for Biochemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
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Vandelle E, Colombo T, Regaiolo A, Maurizio V, Libardi T, Puttilli MR, Danzi D, Polverari A. Transcriptional Profiling of Three Pseudomonas syringae pv. actinidiae Biovars Reveals Different Responses to Apoplast-Like Conditions Related to Strain Virulence on the Host. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:376-396. [PMID: 33356409 DOI: 10.1094/mpmi-09-20-0248-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Pseudomonas syringae pv. actinidiae is a phytopathogen that causes devastating bacterial canker in kiwifruit. Among five biovars defined by genetic, biochemical, and virulence traits, P. syringae pv. actinidiae biovar 3 (Psa3) is the most aggressive and is responsible for the most recent reported outbreaks; however, the molecular basis of its heightened virulence is unclear. Therefore, we designed the first P. syringae multistrain whole-genome microarray, encompassing biovars Psa1, Psa2, and Psa3 and the well-established model P. syringae pv. tomato, and analyzed early bacterial responses to an apoplast-like minimal medium. Transcriptomic profiling revealed i) the strong activation in Psa3 of all hypersensitive reaction and pathogenicity (hrp) and hrp conserved (hrc) cluster genes, encoding components of the type III secretion system required for bacterial pathogenicity and involved in responses to environmental signals; ii) potential repression of the hrp/hrc cluster in Psa2; and iii) activation of flagellum-dependent cell motility and chemotaxis genes in Psa1. The detailed investigation of three gene families encoding upstream regulatory proteins (histidine kinases, their cognate response regulators, and proteins with diguanylate cyclase or phosphodiesterase domains) indicated that cyclic di-GMP may be a key regulator of virulence in P. syringae pv. actinidiae biovars. The gene expression data were supported by the quantification of biofilm formation. Our findings suggest that diverse early responses to the host apoplast, even among bacteria belonging to the same pathovar, can lead to different virulence strategies and may explain the differing outcomes of infections. Based on our detailed structural analysis of hrp operons, we also propose a revision of hrp cluster organization and operon regulation in P. syringae.[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)
- Elodie Vandelle
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | - Teresa Colombo
- National Research Council of Italy (CNR), Institute of Molecular Biology and Pathology (IBPM) c/o Department of Biochemical Sciences "A. Rossi Fanelli", "Sapienza" University of Rome, Rome, 00185, Italy
| | - Alice Regaiolo
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | - Vanessa Maurizio
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | - Tommaso Libardi
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | | | - Davide Danzi
- Department of Biotechnology, University of Verona, Verona, 37134, Italy
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Sang Y, Yu W, Zhuang H, Wei Y, Derevnina L, Yu G, Luo J, Macho AP. Intra-strain Elicitation and Suppression of Plant Immunity by Ralstonia solanacearum Type-III Effectors in Nicotiana benthamiana. PLANT COMMUNICATIONS 2020; 1:100025. [PMID: 33367244 PMCID: PMC7747989 DOI: 10.1016/j.xplc.2020.100025] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 12/12/2019] [Accepted: 01/16/2020] [Indexed: 05/11/2023]
Abstract
Effector proteins delivered inside plant cells are powerful weapons for bacterial pathogens, but this exposes the pathogen to potential recognition by the plant immune system. Therefore, the effector repertoire of a given pathogen must be balanced for a successful infection. Ralstonia solanacearum is an aggressive pathogen with a large repertoire of secreted effectors. One of these effectors, RipE1, is conserved in most R. solanacearum strains sequenced to date. In this work, we found that RipE1 triggers immunity in N. benthamiana, which requires the immune regulator SGT1, but not EDS1 or NRCs. Interestingly, RipE1-triggered immunity induces the accumulation of salicylic acid (SA) and the overexpression of several genes encoding phenylalanine-ammonia lyases (PALs), suggesting that the unconventional PAL-mediated pathway is responsible for the observed SA biosynthesis. Surprisingly, RipE1 recognition also induces the expression of jasmonic acid (JA)-responsive genes and JA biosynthesis, suggesting that both SA and JA may act cooperatively in response to RipE1. We further found that RipE1 expression leads to the accumulation of glutathione in plant cells, which precedes the activation of immune responses. R. solanacearum secretes another effector, RipAY, which is known to inhibit immune responses by degrading cellular glutathione. Accordingly, RipAY inhibits RipE1-triggered immune responses. This work shows a strategy employed by R. solanacearum to counteract the perception of its effector proteins by plant immune system.
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Affiliation(s)
- Yuying Sang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Wenjia Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Haiyan Zhuang
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Yali Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Lida Derevnina
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich NR4 7UH, UK
| | - Gang Yu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Jiamin Luo
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
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Laflamme B, Dillon MM, Martel A, Almeida RND, Desveaux D, Guttman DS. The pan-genome effector-triggered immunity landscape of a host-pathogen interaction. Science 2020; 367:763-768. [PMID: 32054757 DOI: 10.1126/science.aax4079] [Citation(s) in RCA: 110] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 10/18/2019] [Accepted: 01/17/2020] [Indexed: 12/24/2022]
Abstract
Effector-triggered immunity (ETI), induced by host immune receptors in response to microbial effectors, protects plants against virulent pathogens. However, a systematic study of ETI prevalence against species-wide pathogen diversity is lacking. We constructed the Pseudomonas syringae Type III Effector Compendium (PsyTEC) to reduce the pan-genome complexity of 5127 unique effector proteins, distributed among 70 families from 494 strains, to 529 representative alleles. We screened PsyTEC on the model plant Arabidopsis thaliana and identified 59 ETI-eliciting alleles (11.2%) from 19 families (27.1%), with orthologs distributed among 96.8% of P. syringae strains. We also identified two previously undescribed host immune receptors, including CAR1, which recognizes the conserved effectors AvrE and HopAA1, and found that 94.7% of strains harbor alleles predicted to be recognized by either CAR1 or ZAR1.
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Affiliation(s)
- Bradley Laflamme
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Marcus M Dillon
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Alexandre Martel
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Renan N D Almeida
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada.
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada. .,Center for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON M5S 3B2, Canada
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13
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Jeon H, Kim W, Kim B, Lee S, Jayaraman J, Jung G, Choi S, Sohn KH, Segonzac C. Ralstonia solanacearum Type III Effectors with Predicted Nuclear Localization Signal Localize to Various Cell Compartments and Modulate Immune Responses in Nicotiana spp. THE PLANT PATHOLOGY JOURNAL 2020; 36:43-53. [PMID: 32089660 PMCID: PMC7012579 DOI: 10.5423/ppj.oa.08.2019.0227] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 11/19/2019] [Accepted: 11/19/2019] [Indexed: 05/11/2023]
Abstract
Ralstonia solanacearum (Rso) is a causal agent of bacterial wilt in Solanaceae crops worldwide including Republic of Korea. Rso virulence predominantly relies on type III secreted effectors (T3Es). However, only a handful of Rso T3Es have been characterized. In this study, we investigated subcellular localization of and manipulation of plant immunity by 8 Rso T3Es predicted to harbor a nuclear localization signal (NLS). While 2 of these T3Es elicited cell death in both Nicotiana benthamiana and N. tabacum, only one was dependent on suppressor of G2 allele of skp1 (SGT1), a molecular chaperone of nucleotide-binding and leucine-rich repeat immune receptors. We also identified T3Es that differentially regulate flg22-induced reactive oxygen species production and gene expression. Interestingly, several of the NLS-containing T3Es translationally fused with yellow fluorescent protein accumulated in subcellular compartments other than the cell nucleus. Our findings bring new clues to decipher Rso T3E function in planta.
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Affiliation(s)
- Hyelim Jeon
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Wanhui Kim
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826,
Korea
| | - Boyoung Kim
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Sookyeong Lee
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
| | - Jay Jayaraman
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673,
Korea
- New Zealand Institute for Plant & Food Research Limited (PFR), Mt Albert Auckland 1025,
New Zealand
| | - Gayoung Jung
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673,
Korea
| | - Sera Choi
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673,
Korea
| | - Kee Hoon Sohn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673,
Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673,
Korea
| | - Cécile Segonzac
- Department of Plant Science, Plant Genomics and Breeding Institute, Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 08826,
Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826,
Korea
- Corresponding author: Phone) +82-2-880-2229, FAX) +82-2-873-2056, E-mail)
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14
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Nissan G, Gershovits M, Morozov M, Chalupowicz L, Sessa G, Manulis‐Sasson S, Barash I, Pupko T. Revealing the inventory of type III effectors in Pantoea agglomerans gall-forming pathovars using draft genome sequences and a machine-learning approach. MOLECULAR PLANT PATHOLOGY 2018; 19:381-392. [PMID: 28019708 PMCID: PMC6638007 DOI: 10.1111/mpp.12528] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 12/06/2016] [Accepted: 12/14/2016] [Indexed: 05/03/2023]
Abstract
Pantoea agglomerans, a widespread epiphytic bacterium, has evolved into a hypersensitive response and pathogenicity (hrp)-dependent and host-specific gall-forming pathogen by the acquisition of a pathogenicity plasmid containing a type III secretion system (T3SS) and its effectors (T3Es). Pantoea agglomerans pv. betae (Pab) elicits galls on beet (Beta vulgaris) and gypsophila (Gypsophila paniculata), whereas P. agglomerans pv. gypsophilae (Pag) incites galls on gypsophila and a hypersensitive response (HR) on beet. Draft genome sequences were generated and employed in combination with a machine-learning approach and a translocation assay into beet roots to identify the pools of T3Es in the two pathovars. The genomes of the sequenced Pab4188 and Pag824-1 strains have a similar size (∼5 MB) and GC content (∼55%). Mutational analysis revealed that, in Pab4188, eight T3Es (HsvB, HsvG, PseB, DspA/E, HopAY1, HopX2, HopAF1 and HrpK) contribute to pathogenicity on beet and gypsophila. In Pag824-1, nine T3Es (HsvG, HsvB, PthG, DspA/E, HopAY1, HopD1, HopX2, HopAF1 and HrpK) contribute to pathogenicity on gypsophila, whereas the PthG effector triggers HR on beet. HsvB, HsvG, PthG and PseB appear to endow pathovar specificities to Pab and Pag, and no homologous T3Es were identified for these proteins in other phytopathogenic bacteria. Conversely, the remaining T3Es contribute to the virulence of both pathovars, and homologous T3Es were found in other phytopathogenic bacteria. Remarkably, HsvG and HsvB, which act as host-specific transcription factors, displayed the largest contribution to disease development.
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Affiliation(s)
- Gal Nissan
- Department of Molecular Biology and Ecology of Plants, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
- Department of Plant Pathology and Weed ResearchAgricultural Research Organization, The Volcani CenterRishonLeZion7528809Israel
| | - Michael Gershovits
- Department of Cell Research and Immunology, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
| | - Michael Morozov
- Department of Molecular Biology and Ecology of Plants, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
- Department of Plant Pathology and Weed ResearchAgricultural Research Organization, The Volcani CenterRishonLeZion7528809Israel
| | - Laura Chalupowicz
- Department of Plant Pathology and Weed ResearchAgricultural Research Organization, The Volcani CenterRishonLeZion7528809Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
| | - Shulamit Manulis‐Sasson
- Department of Plant Pathology and Weed ResearchAgricultural Research Organization, The Volcani CenterRishonLeZion7528809Israel
| | - Isaac Barash
- Department of Molecular Biology and Ecology of Plants, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
| | - Tal Pupko
- Department of Cell Research and Immunology, Faculty of Life SciencesTel‐Aviv UniversityTel‐Aviv69978Israel
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15
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Yang L, Teixeira PJPL, Biswas S, Finkel OM, He Y, Salas-Gonzalez I, English ME, Epple P, Mieczkowski P, Dangl JL. Pseudomonas syringae Type III Effector HopBB1 Promotes Host Transcriptional Repressor Degradation to Regulate Phytohormone Responses and Virulence. Cell Host Microbe 2017; 21:156-168. [PMID: 28132837 PMCID: PMC5314207 DOI: 10.1016/j.chom.2017.01.003] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 11/02/2016] [Accepted: 12/19/2016] [Indexed: 01/29/2023]
Abstract
Independently evolved pathogen effectors from three branches of life (ascomycete, eubacteria, and oomycete) converge onto the Arabidopsis TCP14 transcription factor to manipulate host defense. However, the mechanistic basis for defense control via TCP14 regulation is unknown. We demonstrate that TCP14 regulates the plant immune system by transcriptionally repressing a subset of the jasmonic acid (JA) hormone signaling outputs. A previously unstudied Pseudomonas syringae (Psy) type III effector, HopBB1, interacts with TCP14 and targets it to the SCFCOI1 degradation complex by connecting it to the JA signaling repressor JAZ3. Consequently, HopBB1 de-represses the TCP14-regulated subset of JA response genes and promotes pathogen virulence. Thus, HopBB1 fine-tunes host phytohormone crosstalk by precisely manipulating part of the JA regulon to avoid pleiotropic host responses while promoting pathogen proliferation.
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Affiliation(s)
- Li Yang
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Paulo José Pereira Lima Teixeira
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Surojit Biswas
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Omri M Finkel
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yijian He
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Isai Salas-Gonzalez
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Marie E English
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Petra Epple
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Piotr Mieczkowski
- Carolina Center for Genome Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeffery L Dangl
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Carolina Center for Genome Science, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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16
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Choi S, Jayaraman J, Segonzac C, Park HJ, Park H, Han SW, Sohn KH. Pseudomonas syringae pv. actinidiae Type III Effectors Localized at Multiple Cellular Compartments Activate or Suppress Innate Immune Responses in Nicotiana benthamiana. FRONTIERS IN PLANT SCIENCE 2017; 8:2157. [PMID: 29326748 PMCID: PMC5742410 DOI: 10.3389/fpls.2017.02157] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/06/2017] [Indexed: 05/15/2023]
Abstract
Bacterial phytopathogen type III secreted (T3S) effectors have been strongly implicated in altering the interaction of pathogens with host plants. Therefore, it is useful to characterize the whole effector repertoire of a pathogen to understand the interplay of effectors in plants. Pseudomonas syringae pv. actinidiae is a causal agent of kiwifruit canker disease. In this study, we generated an Agrobacterium-mediated transient expression library of YFP-tagged T3S effectors from two strains of Psa, Psa-NZ V13 and Psa-NZ LV5, in order to gain insight into their mode of action in Nicotiana tabacum and N. benthamiana. Determining the subcellular localization of effectors gives an indication of the possible host targets of effectors. A confocal microscopy assay detecting YFP-tagged Psa effectors revealed that the nucleus, cytoplasm and cell periphery are major targets of Psa effectors. Agrobacterium-mediated transient expression of multiple Psa effectors induced HR-like cell death (HCD) in Nicotiana spp., suggesting that multiple Psa effectors may be recognized by Nicotiana spp.. Virus-induced gene silencing (VIGS) of several known plant immune regulators, EDS1, NDR1, or SGT1 specified the requirement of SGT1 in HCD induced by several Psa effectors in N. benthamiana. In addition, the suppression activity of Psa effectors on HCD-inducing proteins and PTI was assessed. Psa effectors showed differential suppression activities on each HCD inducer or PTI. Taken together, our Psa effector repertoire analysis highlights the great diversity of T3S effector functions in planta.
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Affiliation(s)
- Sera Choi
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Jay Jayaraman
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Cécile Segonzac
- Plant Science Department, 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
| | - Hye-Jee Park
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Hanbi Park
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Sang-Wook Han
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Kee Hoon Sohn
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, South Korea
- *Correspondence: Kee Hoon Sohn,
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17
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Popa C, Coll NS, Valls M, Sessa G. Yeast as a Heterologous Model System to Uncover Type III Effector Function. PLoS Pathog 2016; 12:e1005360. [PMID: 26914889 PMCID: PMC4767418 DOI: 10.1371/journal.ppat.1005360] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Type III effectors (T3E) are key virulence proteins that are injected by bacterial pathogens inside the cells of their host to subvert cellular processes and contribute to disease. The budding yeast Saccharomyces cerevisiae represents an important heterologous system for the functional characterisation of T3E proteins in a eukaryotic environment. Importantly, yeast contains eukaryotic processes with low redundancy and are devoid of immunity mechanisms that counteract T3Es and mask their function. Expression in yeast of effectors from both plant and animal pathogens that perturb conserved cellular processes often resulted in robust phenotypes that were exploited to elucidate effector functions, biochemical properties, and host targets. The genetic tractability of yeast and its amenability for high-throughput functional studies contributed to the success of this system that, in recent years, has been used to study over 100 effectors. Here, we provide a critical view on this body of work and describe advantages and limitations inherent to the use of yeast in T3E research. “Favourite” targets of T3Es in yeast are cytoskeleton components and small GTPases of the Rho family. We describe how mitogen-activated protein kinase (MAPK) signalling, vesicle trafficking, membrane structures, and programmed cell death are also often altered by T3Es in yeast and how this reflects their function in the natural host. We describe how effector structure–function studies and analysis of candidate targeted processes or pathways can be carried out in yeast. We critically analyse technologies that have been used in yeast to assign biochemical functions to T3Es, including transcriptomics and proteomics, as well as suppressor, gain-of-function, or synthetic lethality screens. We also describe how yeast can be used to select for molecules that block T3E function in search of new antibacterial drugs with medical applications. Finally, we provide our opinion on the limitations of S. cerevisiae as a model system and its most promising future applications.
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Affiliation(s)
- Crina Popa
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Núria S. Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
| | - Marc Valls
- Genetics Department, Universitat de Barcelona, Barcelona, Catalonia, Spain
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra, Catalonia, Spain
- * E-mail: (GS); (MV)
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, Israel
- * E-mail: (GS); (MV)
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18
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Identification of Critical Amino Acids Conferring Lethality in VopK, a Type III Effector Protein of Vibrio cholerae: Lessons from Yeast Model System. PLoS One 2015; 10:e0141038. [PMID: 26488395 PMCID: PMC4619451 DOI: 10.1371/journal.pone.0141038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 09/28/2015] [Indexed: 12/15/2022] Open
Abstract
VopK, a type III effector protein, has been implicated in the pathogenesis of Vibrio cholerae strains belonging to diverse serogroups. Ectopic expression of this protein exhibits strong toxicity in yeast model system. In order to map critical residues in VopK, we scanned the primary sequence guided by available data on various toxins and effector proteins. Our in silico analysis of VopK indicated the presence of predicted MCF1-SHE (SHxxxE) serine peptidase domain at the C-terminus region of the protein. Substitution of each of the predicted catalytic triad residues namely Ser314, His353 and Glu357 with alanine resulted in recombinant VopK proteins varying in lethality as evaluated in yeast model system. We observed that replacement of glutamate357 to alanine causes complete loss in toxicity while substitutions of serine314 and histidine353 with alanine exhibited partial loss in toxicity without affecting the stability of variants. In addition, replacement of another conserved serine residue at position 354 (S354) within predicted S314H353E357 did not affect toxicity of VopK. In essence, combined in silico and site directed mutagenesis, we have identified critical amino acids contributing to the lethal activity of VopK in yeast model system.
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19
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The bacterial effector HopX1 targets JAZ transcriptional repressors to activate jasmonate signaling and promote infection in Arabidopsis. PLoS Biol 2014; 12:e1001792. [PMID: 24558350 PMCID: PMC3928049 DOI: 10.1371/journal.pbio.1001792] [Citation(s) in RCA: 177] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 01/09/2014] [Indexed: 11/19/2022] Open
Abstract
Pathogenicity of Pseudomonas syringae is dependent on a type III secretion system, which secretes a suite of virulence effector proteins into the host cytoplasm, and the production of a number of toxins such as coronatine (COR), which is a mimic of the plant hormone jasmonate-isoleuce (JA-Ile). Inside the plant cell, effectors target host molecules to subvert the host cell physiology and disrupt defenses. However, despite the fact that elucidating effector action is essential to understanding bacterial pathogenesis, the molecular function and host targets of the vast majority of effectors remain largely unknown. Here, we found that effector HopX1 from Pseudomonas syringae pv. tabaci (Pta) 11528, a strain that does not produce COR, interacts with and promotes the degradation of JAZ proteins, a key family of JA-repressors. We show that hopX1 encodes a cysteine protease, activity that is required for degradation of JAZs by HopX1. HopX1 associates with JAZ proteins through its central ZIM domain and degradation occurs in a COI1-independent manner. Moreover, ectopic expression of HopX1 in Arabidopsis induces the expression of JA-dependent genes, represses salicylic acid (SA)-induced markers, and complements the growth of a COR-deficient P. syringae pv. tomato (Pto) DC3000 strain during natural bacterial infections. Furthermore, HopX1 promoted susceptibility when delivered by the natural type III secretion system, to a similar extent as the addition of COR, and this effect was dependent on its catalytic activity. Altogether, our results indicate that JAZ proteins are direct targets of bacterial effectors to promote activation of JA-induced defenses and susceptibility in Arabidopsis. HopX1 illustrates a paradigm of an alternative evolutionary solution to COR with similar physiological outcome.
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20
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Jalan N, Kumar D, Andrade MO, Yu F, Jones JB, Graham JH, White FF, Setubal JC, Wang N. Comparative genomic and transcriptome analyses of pathotypes of Xanthomonas citri subsp. citri provide insights into mechanisms of bacterial virulence and host range. BMC Genomics 2013; 14:551. [PMID: 23941402 PMCID: PMC3751643 DOI: 10.1186/1471-2164-14-551] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/06/2013] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Citrus bacterial canker is a disease that has severe economic impact on citrus industries worldwide and is caused by a few species and pathotypes of Xanthomonas. X. citri subsp. citri strain 306 (XccA306) is a type A (Asiatic) strain with a wide host range, whereas its variant X. citri subsp. citri strain A(w)12879 (Xcaw12879, Wellington strain) is restricted to Mexican lime. RESULTS To characterize the mechanism for the differences in host range of XccA and Xcaw, the genome of Xcaw12879 that was completed recently was compared with XccA306 genome. Effectors xopAF and avrGf1 are present in Xcaw12879, but were absent in XccA306. AvrGf1 was shown previously for Xcaw to cause hypersensitive response in Duncan grapefruit. Mutation analysis of xopAF indicates that the gene contributes to Xcaw growth in Mexican lime but does not contribute to the limited host range of Xcaw. RNA-Seq analysis was conducted to compare the expression profiles of Xcaw12879 and XccA306 in Nutrient Broth (NB) medium and XVM2 medium, which induces hrp gene expression. Two hundred ninety two and 281 genes showed differential expression in XVM2 compared to in NB for XccA306 and Xcaw12879, respectively. Twenty-five type 3 secretion system genes were up-regulated in XVM2 for both XccA and Xcaw. Among the 4,370 common genes of Xcaw12879 compared to XccA306, 603 genes in NB and 450 genes in XVM2 conditions were differentially regulated. Xcaw12879 showed higher protease activity than XccA306 whereas Xcaw12879 showed lower pectate lyase activity in comparison to XccA306. CONCLUSIONS Comparative genomic analysis of XccA306 and Xcaw12879 identified strain specific genes. Our study indicated that AvrGf1 contributes to the host range limitation of Xcaw12879 whereas XopAF contributes to virulence. Transcriptome analyses of XccA306 and Xcaw12879 presented insights into the expression of the two closely related strains of X. citri subsp. citri. Virulence genes including genes encoding T3SS components and effectors are induced in XVM2 medium. Numerous genes with differential expression in Xcaw12879 and XccA306 were identified. This study provided the foundation to further characterize the mechanisms for virulence and host range of pathotypes of X. citri subsp. citri.
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Affiliation(s)
- Neha Jalan
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
| | - Dibyendu Kumar
- Waksman Genomics Core Facility, Rutgers University Busch Campus, Piscataway, NJ 08854, USA
| | - Maxuel O Andrade
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
| | - Fahong Yu
- ICBR, University of Florida, Gainesville, FL 32611, USA
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL 32611, USA
| | - James H Graham
- Department of Soil and Water Science, Citrus Research and Education Center, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
| | - Frank F White
- Department of Plant Pathology, Kansas State University, 4024 Throckmorton Hall, Manhattan, KS 66506, USA
| | - João C Setubal
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24060-0477, USA
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, FL 33850, USA
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21
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Dunger G, Garofalo CG, Gottig N, Garavaglia BS, Rosa MCP, Farah CS, Orellano EG, Ottado J. Analysis of three Xanthomonas axonopodis pv. citri effector proteins in pathogenicity and their interactions with host plant proteins. MOLECULAR PLANT PATHOLOGY 2012; 13:865-76. [PMID: 22435635 PMCID: PMC6638619 DOI: 10.1111/j.1364-3703.2012.00797.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Xanthomonas axonopodis pv. citri, the bacterium responsible for citrus canker, uses effector proteins secreted by a type III protein secretion system to colonize its hosts. Among the putative effector proteins identified for this bacterium, we focused on the analysis of the roles of AvrXacE1, AvrXacE2 and Xac3090 in pathogenicity and their interactions with host plant proteins. Bacterial deletion mutants in avrXacE1, avrXacE2 and xac3090 were constructed and evaluated in pathogenicity assays. The avrXacE1 and avrXacE2 mutants presented lesions with larger necrotic areas relative to the wild-type strain when infiltrated in citrus leaves. Yeast two-hybrid studies were used to identify several plant proteins likely to interact with AvrXacE1, AvrXacE2 and Xac3090. We also assessed the localization of these effector proteins fused to green fluorescent protein in the plant cell, and observed that they co-localized to the subcellular spaces in which the plant proteins with which they interacted were predicted to be confined. Our results suggest that, although AvrXacE1 localizes to the plant cell nucleus, where it interacts with transcription factors and DNA-binding proteins, AvrXacE2 appears to be involved in lesion-stimulating disease 1-mediated cell death, and Xac3090 is directed to the chloroplast where its function remains to be clarified.
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Affiliation(s)
- Germán Dunger
- Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario, Suipacha 531 (S2002LRK) Rosario, Argentina
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22
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Salomon D, Bosis E, Dar D, Nachman I, Sessa G. Expression of Pseudomonas syringae type III effectors in yeast under stress conditions reveals that HopX1 attenuates activation of the high osmolarity glycerol MAP kinase pathway. MICROBIOLOGY-SGM 2012; 158:2859-2869. [PMID: 22977090 DOI: 10.1099/mic.0.062513-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The Gram-negative bacterium Pseudomonas syringae pv. tomato (Pst) is the causal agent of speck disease in tomato. Pst pathogenicity depends on a type III secretion system that delivers effector proteins into host cells, where they promote disease by manipulating processes to the advantage of the pathogen. Previous studies identified seven Pst effectors that inhibit growth when expressed in yeast under normal growth conditions, suggesting that they interfere with cellular processes conserved in yeast and plants. We hypothesized that effectors also target conserved cellular processes that are required for yeast growth only under stress conditions. We therefore examined phenotypes induced by expression of Pst effectors in yeast grown in the presence of various stressors. Out of 29 effectors tested, five (HopX1, HopG1, HopT1-1, HopH1 and AvrPtoB) displayed growth inhibition phenotypes only in combination with stress conditions. Viability assays revealed that the HopX1 effector caused loss of cell viability under prolonged osmotic stress. Using transcription reporters, we found that HopX1 attenuated the activation of the high osmolarity glycerol (HOG) mitogen-activated protein kinase (MAPK) pathway, which is responsible for yeast survival under osmotic stress, while other MAPK pathways were mildly affected by HopX1. Interestingly, HopX1-mediated phenotypes in yeast were dependent on the putative transglutaminase catalytic triad of the effector. This study enlarges the pool of phenotypes available for the functional analysis of Pst type III effectors in yeast, and exemplifies how analysis of phenotypes detected in yeast under stress conditions can lead to the identification of eukaryotic cellular processes affected by bacterial effectors.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Eran Bosis
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Daniel Dar
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Iftach Nachman
- Department of Biochemistry and Molecular Biology, Tel Aviv University, 69978 Tel Aviv, Israel
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, 69978 Tel Aviv, Israel
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23
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The molecular basis of ubiquitin-like protein NEDD8 deamidation by the bacterial effector protein Cif. Proc Natl Acad Sci U S A 2012; 109:E1830-8. [PMID: 22691497 DOI: 10.1073/pnas.1112107109] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cycle inhibiting factors (Cifs) are a family of translocated effector proteins, found in diverse pathogenic bacteria, that interfere with the host cell cycle by catalyzing the deamidation of a specific glutamine residue (Gln40) in NEDD8 and the related protein ubiquitin. This modification prevents recycling of neddylated cullin-RING ligases, leading to stabilization of various cullin-RING ligase targets, and also prevents polyubiquitin chain formation. Here, we report the crystal structures of two Cif/NEDD8 complexes, revealing a conserved molecular interface that defines enzyme/substrate recognition. Mutation of residues forming the interface suggests that shape complementarity, rather than specific individual interactions, is a critical feature for complex formation. We show that Cifs from diverse bacteria bind NEDD8 in vitro and conclude that they will all interact with their substrates in the same way. The "occluding loop" in Cif gates access to Gln40 by forcing a conformational change in the C terminus of NEDD8. We used native PAGE to follow the activity of Cif from the human pathogen Yersinia pseudotuberculosis and selected variants, and the position of Gln40 in the active site has allowed us to propose a catalytic mechanism for these enzymes.
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24
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Bocsanczy AM, Schneider DJ, DeClerck GA, Cartinhour S, Beer SV. HopX1 in Erwinia amylovora functions as an avirulence protein in apple and is regulated by HrpL. J Bacteriol 2012; 194:553-60. [PMID: 22123252 PMCID: PMC3264070 DOI: 10.1128/jb.05065-11] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Accepted: 11/14/2011] [Indexed: 12/30/2022] Open
Abstract
Fire blight is a devastating disease of rosaceous plants caused by the Gram-negative bacterium Erwinia amylovora. This pathogen delivers virulence proteins into host cells utilizing the type III secretion system (T3SS). Expression of the T3SS and of translocated and secreted substrates is activated by the alternative sigma factor HrpL, which recognizes hrp box promoters upstream of regulated genes. A collection of hidden Markov model (HMM) profiles was used to identify putative hrp boxes in the genome sequence of Ea273, a highly virulent strain of E. amylovora. Among potential virulence factors preceded by putative hrp boxes, two genes previously known as Eop3 and Eop2 were characterized. The presence of functionally active hrp boxes upstream of these two genes was confirmed by β-glucuronidase (GUS) assays. Deletion mutants of the latter candidate genes, renamed hopX1(Ea) and hopAK1(Ea), respectively, did not differ in virulence from the wild-type strain when assayed in pear fruit and apple shoots. The hopX1(Ea) deletion mutant of Ea273, complemented with a plasmid overexpressing hopX1(E)(a), suppressed the development of the hypersensitivity response (HR) when inoculated into Nicotiana benthamiana; however, it contributed to HR in Nicotiana tabacum and significantly reduced the progress of disease in apple shoots, suggesting that HopX1(Ea) may act as an avirulence protein in apple shoots.
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Affiliation(s)
- A. M. Bocsanczy
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA
| | - D. J. Schneider
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA
- United States Department of Agriculture, Agricultural Research Service, Ithaca, New York, USA
| | - G. A. DeClerck
- Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York, USA
| | - S. Cartinhour
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA
- United States Department of Agriculture, Agricultural Research Service, Ithaca, New York, USA
| | - S. V. Beer
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, USA
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25
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Jaciani FJ, Ferro JA, Ferro MIT, Vernière C, Pruvost O, Belasque J. Genetic Diversity of a Brazilian Strain Collection of Xanthomonas citri subsp. citri Based on the Type III Effector Protein Genes. PLANT DISEASE 2012; 96:193-203. [PMID: 30731808 DOI: 10.1094/pdis-04-11-0357] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Exclusion and eradication or management based on an integrated approach with less susceptible varieties, copper-based bactericides, and windbreaks are the two main strategies used to prevent or control citrus canker. Field tolerance or resistance to citrus canker is not found in the most important commercial sweet orange cultivars, and pathogen-derived resistance has been developed and applied in different crops to obtain resistant genotypes to plant pathogens. We describe the development of DNA primers and probes based on the type III effector genes avrXacE1, avrXacE2, avrXacE3, avrBs2, pthA4, hpaF, and XAC3090 (leucine rich protein), and their application in the evaluation of the genetic diversity of the pathogen. A total of 49 haplotypes were identified in 157 strains by Southern blot analysis. No genetic polymorphism was detected by BOX elements - and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) analysis, nor with the genes avrBs2, XAC3090, and hpaF. Nei's genetic diversity indexes varied from 0.65 to 0.96 for subcollections of the pathogen. One or few haplotypes were most frequent in the strain collection, but several haplotypes were represented by solely one or few strains. The PthA4 probe resulted in the higher number of haplotypes identified in the Brazilian subcollections. Greater variation in the frequency of haplotypes occurred within subcollections (93.7%) than among subcollections. Only some haplotypes were genetically distant from all others, especially those originated from Rio Grande do Sul and Santa Catarina states. These bacterial effectors are widely spread in the collections and are useful for a better understanding of the host-pathogen interaction and the search for resistance genes in host and nonhost plants.
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Affiliation(s)
- F J Jaciani
- Faculdade de Ciências Agrárias e Veterinárias, UNESP - Univ. Estadual Paulista, Campus de Jaboticabal, Departamento de Tecnologia, Jaboticabal, SP, Brazil
| | - J A Ferro
- Faculdade de Ciências Agrárias e Veterinárias, UNESP - Univ. Estadual Paulista, Campus de Jaboticabal, Departamento de Tecnologia, Jaboticabal, SP, Brazil
| | - M I T Ferro
- Faculdade de Ciências Agrárias e Veterinárias, UNESP - Univ. Estadual Paulista, Campus de Jaboticabal, Departamento de Tecnologia, Jaboticabal, SP, Brazil
| | - C Vernière
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical CIRAD-Université de la Réunion, Pôle de Protection des Plantes, 7, chemin de l'Irat, 97410 Saint Pierre, Réunion, France
| | - O Pruvost
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical CIRAD-Université de la Réunion, Pôle de Protection des Plantes, 7, chemin de l'Irat, 97410 Saint Pierre, Réunion, France
| | - J Belasque
- Fundo de Defesa da Citricultura, Araraquara, SP, Brazil
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26
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Type three effector gene distribution and sequence analysis provide new insights into the pathogenicity of plant-pathogenic Xanthomonas arboricola. Appl Environ Microbiol 2011; 78:371-84. [PMID: 22101042 DOI: 10.1128/aem.06119-11] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Xanthomonas arboricola is a complex bacterial species which mainly attacks fruit trees and is responsible for emerging diseases in Europe. It comprises seven pathovars (X. arboricola pv. pruni, X. arboricola pv. corylina, X. arboricola pv. juglandis, X. arboricola pv. populi, X. arboricola pv. poinsettiicola, X. arboricola pv. celebensis, and X. arboricola pv. fragariae), each exhibiting characteristic disease symptoms and distinct host specificities. To better understand the factors underlying this ecological trait, we first assessed the phylogenetic relationships among a worldwide collection of X. arboricola strains by sequencing the housekeeping gene rpoD. This analysis revealed that strains of X. arboricola pathovar populi are divergent from the main X. arboricola cluster formed by all other strains. Then, we investigated the distribution of 53 type III effector (T3E) genes in a collection of 57 X. arboricola strains that are representative of the main X. arboricola cluster. Our results showed that T3E repertoires vary greatly between X. arboricola pathovars in terms of size. Indeed, X. arboricola pathovars pruni, corylina, and juglandis, which are responsible for economically important stone fruit and nut diseases in Europe, harbored the largest T3E repertoires, whereas pathovars poinsettiicola, celebensis, and fragariae harbored the smallest. We also identified several differences in T3E gene content between X. arboricola pathovars pruni, corylina, and juglandis which may account for their differing host specificities. Further, we examined the allelic diversity of eight T3E genes from X. arboricola pathovars. This analysis revealed very limited allelic variations at the different loci. Altogether, the data presented here provide new insights into the evolution of pathogenicity and host range of X. arboricola and are discussed in terms of emergence of new diseases within this bacterial species.
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27
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Jalan N, Aritua V, Kumar D, Yu F, Jones JB, Graham JH, Setubal JC, Wang N. Comparative genomic analysis of Xanthomonas axonopodis pv. citrumelo F1, which causes citrus bacterial spot disease, and related strains provides insights into virulence and host specificity. J Bacteriol 2011; 193:6342-57. [PMID: 21908674 PMCID: PMC3209208 DOI: 10.1128/jb.05777-11] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Accepted: 08/30/2011] [Indexed: 11/20/2022] Open
Abstract
Xanthomonas axonopodis pv. citrumelo is a citrus pathogen causing citrus bacterial spot disease that is geographically restricted within the state of Florida. Illumina, 454 sequencing, and optical mapping were used to obtain a complete genome sequence of X. axonopodis pv. citrumelo strain F1, 4.9 Mb in size. The strain lacks plasmids, in contrast to other citrus Xanthomonas pathogens. Phylogenetic analysis revealed that this pathogen is very close to the tomato bacterial spot pathogen X. campestris pv. vesicatoria 85-10, with a completely different host range. We also compared X. axonopodis pv. citrumelo to the genome of citrus canker pathogen X. axonopodis pv. citri 306. Comparative genomic analysis showed differences in several gene clusters, like those for type III effectors, the type IV secretion system, lipopolysaccharide synthesis, and others. In addition to pthA, effectors such as xopE3, xopAI, and hrpW were absent from X. axonopodis pv. citrumelo while present in X. axonopodis pv. citri. These effectors might be responsible for survival and the low virulence of this pathogen on citrus compared to that of X. axonopodis pv. citri. We also identified unique effectors in X. axonopodis pv. citrumelo that may be related to the different host range as compared to that of X. axonopodis pv. citri. X. axonopodis pv. citrumelo also lacks various genes, such as syrE1, syrE2, and RTX toxin family genes, which were present in X. axonopodis pv. citri. These may be associated with the distinct virulences of X. axonopodis pv. citrumelo and X. axonopodis pv. citri. Comparison of the complete genome sequence of X. axonopodis pv. citrumelo to those of X. axonopodis pv. citri and X. campestris pv. vesicatoria provides valuable insights into the mechanism of bacterial virulence and host specificity.
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Affiliation(s)
- Neha Jalan
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
| | - Valente Aritua
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
| | - Dibyendu Kumar
- Interdisciplinary Center for Biotechnology Research, 2033 Mowry Road, University of Florida, Gainesville, Florida 32611
| | - Fahong Yu
- Interdisciplinary Center for Biotechnology Research, 2033 Mowry Road, University of Florida, Gainesville, Florida 32611
| | - Jeffrey B. Jones
- Department of Plant Pathology, University of Florida, Gainesville, Florida 32611
| | - James H. Graham
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
| | - João C. Setubal
- Virginia Bioinformatics Institute and Department of Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060-0477
| | - Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, University of Florida, 700 Experiment Station Road, Lake Alfred, Florida 33850
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28
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Sarris PF, Gao S, Karademiris K, Jin H, Kalantidis K, Panopoulos NJ. Phytobacterial type III effectors HopX1, HopAB1 and HopF2 enhance sense-post-transcriptional gene silencing independently of plant R gene-effector recognition. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:907-17. [PMID: 21469938 PMCID: PMC3788636 DOI: 10.1094/mpmi-01-11-0010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Plant- and animal-pathogenic bacteria deploy a variable arsenal of type III effector proteins (T3EP) to manipulate host defense. Specific biochemical functions and molecular or subcellular targets have been demonstrated or proposed for a growing number of T3EP but remain unknown for the majority of them. Here, we show that transient expression of genes coding certain bacterial T3EP (HopAB1, HopX1, and HopF2), which did not elicit hypersensitive response (HR) in transgenic green fluorescent protein (GFP) Nicotiana benthamiana 16C line, enhanced the sense post-transcriptional gene silencing (S-PTGS) triggered by agrodelivery of a GFP-expressing cassette and the silencing enhancement could be blocked by two well-known viral silencing suppressors. Further analysis using genetic truncations and site-directed mutations showed that the receptor recognition domains of HopAB1 and HopX1 are not involved in enhancing silencing. Our studies provide new evidence that phytobacterial pathogen T3EP manipulate the plant small interfering RNA pathways by enhancing silencing efficiency in the absence of effector-triggered immunity signaling and suggest that phytopathogenic bacterial effectors affect host RNA silencing in yet other ways than previously described.
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Affiliation(s)
- Panagiotis F Sarris
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Hellas, Crete, Greece
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29
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Pothier JF, Vorhölter FJ, Blom J, Goesmann A, Pühler A, Smits THM, Duffy B. The ubiquitous plasmid pXap41 in the invasive phytopathogen Xanthomonas arboricola pv. pruni: complete sequence and comparative genomic analysis. FEMS Microbiol Lett 2011; 323:52-60. [PMID: 21732961 DOI: 10.1111/j.1574-6968.2011.02352.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The complete DNA sequence of the 41 102-bp plasmid pXap41 from the invasive plant pathogen Xanthomonas arboricola pv. pruni CFBP 5530 was determined and its 44 coding regions were annotated. Comparative analysis with 15 Xanthomonas plasmids and 19 complete genomes revealed that nearly one-fourth of this plasmid has high sequence identity to plasmid pXAC64 and an 8.8-kb chromosomal region of Xanthomonas axonopodis pv. citri strain 306 carrying genes that encode type III effectors and helper proteins. The presence of pXap41 in all X. arboricola pv. pruni genotypes was confirmed for eight strains by plasmid profiling and for 35 X. arboricola pv. pruni isolates with a new plasmid multiplex PCR assay. This plasmid was not detected in any other X. arboricola pathovars (n=12), indicating the potential for the application of the pXap41 PCR method as a pathovar-level detection and identification tool.
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Affiliation(s)
- Joël F Pothier
- Agroscope Changins-Wädenswil ACW, Plant Protection Division, Wädenswil, SwitzerlandCeBiTec, Bielefeld University, Bielefeld, Germany
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30
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Salomon D, Dar D, Sreeramulu S, Sessa G. Expression of Xanthomonas campestris pv. vesicatoria type III effectors in yeast affects cell growth and viability. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:305-14. [PMID: 21062109 DOI: 10.1094/mpmi-09-10-0196] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The gram-negative bacterium Xanthomonas campestris pv. vesicatoria is the causal agent of spot disease in tomato and pepper. X. campestris pv. vesicatoria pathogenicity depends on a type III secretion system delivering effector proteins into the host cells. We hypothesized that some X. campestris pv. vesicatoria effectors target conserved eukaryotic cellular processes and examined phenotypes induced by their expression in yeast. Out of 21 effectors tested, 14 inhibited yeast growth in normal or stress conditions. Viability assay revealed that XopB and XopF2 attenuated cell proliferation, while AvrRxo1, XopX, and XopE1 were cytotoxic. Inspection of morphological features and DNA content of yeast cells indicated that cytotoxicity caused by XopX and AvrRxo1 was associated with cell-cycle arrest at G0/1. Interestingly, XopB, XopE1, XopF2, XopX, and AvrRxo1 that inhibited growth in yeast also caused phenotypes, such as chlorosis and cell death, when expressed in either host or nonhost plants. Finally, the ability of several effectors to cause phenotypes in yeast and plants was dependent on their putative catalytic residues or localization motifs. This study supports the use of yeast as a heterologous system for functional analysis of X. campestris pv. vesicatoria type III effectors, and sets the stage for identification of their eukaryotic molecular targets and modes of action.
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Affiliation(s)
- Dor Salomon
- Department of Molecular Biology, Tel-Aviv University, Tel-Aviv, Israel
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31
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Moreira LM, Almeida NF, Potnis N, Digiampietri LA, Adi SS, Bortolossi JC, da Silva AC, da Silva AM, de Moraes FE, de Oliveira JC, de Souza RF, Facincani AP, Ferraz AL, Ferro MI, Furlan LR, Gimenez DF, Jones JB, Kitajima EW, Laia ML, Leite RP, Nishiyama MY, Rodrigues Neto J, Nociti LA, Norman DJ, Ostroski EH, Pereira HA, Staskawicz BJ, Tezza RI, Ferro JA, Vinatzer BA, Setubal JC. Novel insights into the genomic basis of citrus canker based on the genome sequences of two strains of Xanthomonas fuscans subsp. aurantifolii. BMC Genomics 2010; 11:238. [PMID: 20388224 PMCID: PMC2883993 DOI: 10.1186/1471-2164-11-238] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 04/13/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Citrus canker is a disease that has severe economic impact on the citrus industry worldwide. There are three types of canker, called A, B, and C. The three types have different phenotypes and affect different citrus species. The causative agent for type A is Xanthomonas citri subsp. citri, whose genome sequence was made available in 2002. Xanthomonas fuscans subsp. aurantifolii strain B causes canker B and Xanthomonas fuscans subsp. aurantifolii strain C causes canker C. RESULTS We have sequenced the genomes of strains B and C to draft status. We have compared their genomic content to X. citri subsp. citri and to other Xanthomonas genomes, with special emphasis on type III secreted effector repertoires. In addition to pthA, already known to be present in all three citrus canker strains, two additional effector genes, xopE3 and xopAI, are also present in all three strains and are both located on the same putative genomic island. These two effector genes, along with one other effector-like gene in the same region, are thus good candidates for being pathogenicity factors on citrus. Numerous gene content differences also exist between the three cankers strains, which can be correlated with their different virulence and host range. Particular attention was placed on the analysis of genes involved in biofilm formation and quorum sensing, type IV secretion, flagellum synthesis and motility, lipopolysacharide synthesis, and on the gene xacPNP, which codes for a natriuretic protein. CONCLUSION We have uncovered numerous commonalities and differences in gene content between the genomes of the pathogenic agents causing citrus canker A, B, and C and other Xanthomonas genomes. Molecular genetics can now be employed to determine the role of these genes in plant-microbe interactions. The gained knowledge will be instrumental for improving citrus canker control.
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Affiliation(s)
- Leandro M Moreira
- Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Campus Morro do Cruzeiro, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Nalvo F Almeida
- Faculdade de Computação, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS, Brazil
| | - Neha Potnis
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Luciano A Digiampietri
- Escola de Artes, Ciências, e Humanidades, Universidade de São Paulo, São Paulo, SP, Brazil
- Laboratório de Bioinformática, Instituto de Computação, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Said S Adi
- Faculdade de Computação, Universidade Federal do Mato Grosso do Sul, Campo Grande, MS, Brazil
| | - Julio C Bortolossi
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | | | - Aline M da Silva
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Fabrício E de Moraes
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Julio C de Oliveira
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
- Departamento de Ciências Biológicas, Campus de Diadema, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Robson F de Souza
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Agda P Facincani
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - André L Ferraz
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Maria I Ferro
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Luiz R Furlan
- Departamento de Melhoramento e Nutrição Animal, Faculdade de Medicina Veterinária e Zootecnia de Botucatu, UNESP - Univ. Estadual Paulista, SP, Brazil
| | - Daniele F Gimenez
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Jeffrey B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL, USA
| | - Elliot W Kitajima
- Núcleo de apoio à pesquisa em microscopia eletrônica aplicada à pesquisa agropecuária, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, Brazil
| | - Marcelo L Laia
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
- Departamento de Engenharia Florestal, Centro de Ciências Agroveterinárias, Universidade do Estado de Santa Catarina, Lages, SC, Brazil
| | - Rui P Leite
- Instituto Agronômico do Paraná, Londrina, PR, Brazil
| | - Milton Y Nishiyama
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Julio Rodrigues Neto
- Laboratório de Bacteriologia Vegetal, Instituto Biológico Campinas, Campinas, SP, Brazil
| | - Letícia A Nociti
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - David J Norman
- Institute of Food and Agricultural Sciences, Mid-Florida Research & Education Center, University of Florida, Gainesville, FL, USA
| | - Eric H Ostroski
- Laboratório de Bioinformática, Instituto de Computação, Universidade Estadual de Campinas, Campinas, SP, Brazil
| | - Haroldo A Pereira
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Brian J Staskawicz
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Renata I Tezza
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Jesus A Ferro
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, UNESP - Univ. Estadual Paulista, Jaboticabal, SP, Brazil
| | - Boris A Vinatzer
- Department of Plant Pathology, Physiology and Weed Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
| | - João C Setubal
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
- Department of Computer Science, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA
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Yeam I, Nguyen HP, Martin GB. Phosphorylation of the Pseudomonas syringae effector AvrPto is required for FLS2/BAK1-independent virulence activity and recognition by tobacco. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 61:16-24. [PMID: 19793077 DOI: 10.1111/j.1365-313x.2009.04028.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The type III effector protein AvrPto from Pseudomonas syringae pv. tomato is secreted into plant cells where it promotes bacterial growth and enhances symptoms of speck disease on susceptible tomato plants. The virulence activity of AvrPto is due, in part, to its interaction with components of host pattern recognition receptor complexes, which disrupts pathogen-associated molecular pattern-triggered immunity. This disruption mechanism requires a structural element of the AvrPto protein, the CD loop, which is also required for triggering Pto/Prf-mediated resistance in tomato. We have shown previously that the carboxyl-terminal domain (CTD) of AvrPto is phosphorylated and also contributes to bacterial virulence. Here we report that phosphorylation of the CTD on S147 and S149 promotes bacterial virulence in an FLS2/BAK1-independent manner, which is mechanistically distinct from the CD loop. In a striking corollary with Pto recognition of the CD loop in tomato, the tobacco species Nicotiana sylvestris and Nicotiana tabacum have a recognition mechanism that specifically detects the phosphorylation status of the CTD. Thus different species in the Solanaceae family have evolved distinct recognition mechanisms to monitor the same type III effector.
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Affiliation(s)
- Inhwa Yeam
- Boyce Thompson Institute for Plant Research, Ithaca, NY 14853, USA
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Abstract
A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence and structural similarity searches of genomic data. We propose that the effectors and suspected effectors should be distributed into 39 so-called Xop groups reflecting sequence similarity. Some groups have structural motifs for putative enzymatic functions, and recent studies have provided considerable insight into the interaction with host factors in their function as mediators of virulence and elicitors of resistance for a few specific T3 effectors. Many groups are related to T3 effectors of plant and animal pathogenic bacteria, and several groups appear to have been exploited primarily by Xanthomonas species based on available data. At the same time, a relatively large number of candidate effectors remain to be examined in more detail with regard to their function within host cells.
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Affiliation(s)
- Frank F White
- Department of Plant Pathology, 4024 Throckmorton Hall, Kansas State University, Manhattan, KS 66506-550, USA.
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Jiang W, Jiang BL, Xu RQ, Huang JD, Wei HY, Jiang GF, Cen WJ, Liu J, Ge YY, Li GH, Su LL, Hang XH, Tang DJ, Lu GT, Feng JX, He YQ, Tang JL. Identification of six type III effector genes with the PIP box in Xanthomonas campestris pv. campestris and five of them contribute individually to full pathogenicity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:1401-1411. [PMID: 19810809 DOI: 10.1094/mpmi-22-11-1401] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Xanthomonas campestris pv. campestris is the pathogen of black rot of cruciferous plants. The pathogenicity of the pathogen depends on the type III secretion system (T3SS) that translocates directly effector proteins into plant cells, where they play important roles in the molecular interaction between the pathogen and its hosts. The T3SS of Xanthomonas spp. is encoded by a cluster of hypersensitive response and pathogenicity (hrp) genes. It has been demonstrated that the expression of hrp genes and some type III secreted (T3S)-effector genes is coactivated by the key hrp regulatory protein HrpX. The regulation by HrpX can be mediated by the binding of HrpX protein to a cis-regulatory element named the plant-inducible promoter (PIP) box present in the promoter region of HrpX-regulated genes. A genome screen revealed that X. campestris pv. campestris 8004 possesses 56 predicted genes with the PIP box. Nine of these genes have been shown to encode T3S effectors, Hrp, and Hrp-associated proteins. In this study, we employed an established T3S effector translocation assay with the hypersensitive-reaction-inducing domain of X. campestris pv. campestris AvrBs1 as a reporter to characterize the remaining 47 genes with the PIP box and showed that 6 of them, designated as XopXccE1, XopXccP, XopXccQ, XopXccR1, XopXccLR, and AvrXccB, harbor a functional translocation signal in their N-terminal regions, indicating that they are T3S effectors of X. campestris pv. campestris. We provided evidence to demonstrate that all these effectors are expressed in an HrpX-dependent manner and their translocation into plant cells relies on the translocon protein HrpF and the chaperone HpaB. Mutational analyses demonstrated that all these effectors, except AvrXccB, are individually required for full virulence and growth of X. campestris pv. campestris in the host plant Chinese radish.
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Affiliation(s)
- Wei Jiang
- Guangxi Key Laboratory of Subtropical Bioresources Conservation and Utilization, The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering, and College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China
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Abstract
Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide. Successful infection and bacterial multiplication in the host tissue often depend on the virulence factors secreted including adhesins, polysaccharides, LPS and degradative enzymes. One of the key pathogenicity factors is the type III secretion system, which injects effector proteins into the host cell cytosol to manipulate plant cellular processes such as basal defense to the benefit of the pathogen. The coordinated expression of bacterial virulence factors is orchestrated by quorum-sensing pathways, multiple two-component systems and transcriptional regulators such as Clp, Zur, FhrR, HrpX and HpaR. Furthermore, virulence gene expression is post-transcriptionally controlled by the RNA-binding protein RsmA. In this review, we summarize the current knowledge on the infection strategies and regulatory networks controlling secreted virulence factors from Xanthomonas species.
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Affiliation(s)
- Daniela Büttner
- Genetics Department, Institute of Biology, Martin-Luther University Halle-Wittenberg, Halle (Saale), Germany.
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Mucyn TS, Wu AJ, Balmuth AL, Arasteh JM, Rathjen JP. Regulation of tomato Prf by Pto-like protein kinases. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:391-401. [PMID: 19271954 DOI: 10.1094/mpmi-22-4-0391] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Tomato Prf encodes a nucleotide-binding domain shared by Apaf-1, certain R proteins, and CED-4 fused to C-terminal leucine-rich repeats (NBARC-LRR) protein that is required for bacterial immunity to Pseudomonas syringae and sensitivity to the organophosphate fenthion. The signaling pathways involve two highly related protein kinases. Pto kinase mediates direct recognition of the bacterial effector proteins AvrPto or AvrPtoB. Fen kinase is required for fenthion sensitivity and recognition of bacterial effectors related to AvrPtoB. The role of Pto and its association with Prf has been characterized but Fen is poorly described. We show that, similar to Pto, Fen requires N-myristoylation and kinase activity for signaling and interacts with the N-terminal domain of Prf. Thus, the mechanisms of activation of Prf by the respective protein kinases are similar. Prf-Fen interaction is underlined by coregulatory mechanisms in which Prf negatively regulates Fen, most likely by controlling kinase activity. We further characterized negative regulation of Prf by Pto, and show that regulation is mediated by the previously described negative regulatory patch. Remarkably, the effectors released negative regulation of Prf in a manner dependent on Pto kinase activity. The data suggest a model in which Prf associates generally with Pto-like kinases in tightly regulated complexes, which are activated by effector-mediated disruption of negative regulation. Release of negative regulation may be a general feature of activation of NBARC-LRR proteins by cognate effectors.
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A bacterial type III effector family uses the papain-like hydrolytic activity to arrest the host cell cycle. Proc Natl Acad Sci U S A 2009; 106:3716-21. [PMID: 19225106 DOI: 10.1073/pnas.0900212106] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Pathogenic bacteria deliver effector proteins into host cells through the type III secretion apparatus to modulate the host function. We identify a family of proteins, homologous to the type III effector Cif from enteropathogenic Escherichia coli, in pathogens including Yersinia, Photorhabdus, and Burkholderia that contain functional type III secretion systems. Like Cif, this family of proteins is capable of arresting the host cell cycle at G(2)/M. Structure of one of the family members, Cif homolog in Burkholderia pseudomallei (CHBP), reveals a papain-like fold and a conserved Cys-His-Gln catalytic triad despite the lack of primary sequence identity. For CHBP and Cif, only the putative catalytic Cys is susceptible to covalent modification by E-64, a specific inhibitor of papain-like cysteine proteases. Unlike papain-like enzymes where the S2 site is the major determinant of cleavage-site specificity, CHBP has a characteristic negatively charged pocket occupying surface areas corresponding to the S1/S1' site in papain-like proteases. The negative charge is provided by a conserved aspartate, and the pocket best fits an arginine, as revealed by molecular docking analysis. Mutation analysis establishes the essential role of the catalytic triad and the negatively charged pocket in inducing cell cycle arrest in host cells. Our results demonstrate that bacterial pathogens have evolved a unique papain-like hydrolytic activity to block the normal host cell cycle progression.
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Kay S, Bonas U. How Xanthomonas type III effectors manipulate the host plant. Curr Opin Microbiol 2009; 12:37-43. [PMID: 19168386 DOI: 10.1016/j.mib.2008.12.006] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 12/11/2008] [Accepted: 12/11/2008] [Indexed: 11/15/2022]
Affiliation(s)
- Sabine Kay
- Institute of Biology, Department of Genetics, Martin-Luther-University Halle-Wittenberg, Weinbergweg 10, D-06120 Halle (Saale), Germany
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Shindo T, Van der Hoorn RAL. Papain-like cysteine proteases: key players at molecular battlefields employed by both plants and their invaders. MOLECULAR PLANT PATHOLOGY 2008; 9:119-25. [PMID: 18705889 PMCID: PMC6640327 DOI: 10.1111/j.1364-3703.2007.00439.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Papain-like cysteine proteases (PLCPs) play crucial roles in plant-pathogen/pest interactions. During these parasitic interactions, PLCPs act on non-self substrates, provoking the selection of counteracting inhibitors and other means to evade proteolysis. We review examples of PLCPs acting on molecular battlefields in the extracellular space, plant cytoplasm and herbivore gut. Examples are maize Mir1 (Maize inbred resistance 1), tomato Rcr3 (Required for Cladosporium resistance-3), Pseudomonas AvrRpt2 and AurPphB, insect DvCAL1 (Diabrotica virgifera cathepsin L-like protease-1) and nematode MiCpl1 (Meloidogyne incognita cathepsin L-like protease 1). The data suggest that PLCPs cleave specific proteins and that their translocation, activation and inhibition of PLCPs are tightly regulated.
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Affiliation(s)
- Takayuki Shindo
- Plant Chemetics Laboratory, Max Planck Institute for Plant Breeding Research, Carl-von-Linne Weg 10, 50829 Cologne, Germany
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40
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Göhre V, Robatzek S. Breaking the barriers: microbial effector molecules subvert plant immunity. ANNUAL REVIEW OF PHYTOPATHOLOGY 2008; 46:189-215. [PMID: 18422429 DOI: 10.1146/annurev.phyto.46.120407.110050] [Citation(s) in RCA: 216] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Adaptation to specialized environments allows microorganisms to inhabit an enormous variety of ecological niches. Growth inside plant tissues is a niche offering a constant nutrient supply, but to access this niche, plant defense mechanisms ranging from passive barriers to induced defense reactions have to be overcome. Pathogens have to break several, if not all, of these barriers. For this purpose, they secrete effector molecules into plant cells to interfere with individual defense responses. Plant defense is organized in multiple layers, and therefore the action of effectors likely follows this same order, leading to a hierarchy in effector orchestration. In this review we summarize the latest findings regarding the level at which effectors manipulate plant immunity. Particular attention is given to those effectors whose mechanism of action is known. Additionally, we compare methods to identify and characterize effector molecules.
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Affiliation(s)
- Vera Göhre
- Max-Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.
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Thieme F, Szczesny R, Urban A, Kirchner O, Hause G, Bonas U. New type III effectors from Xanthomonas campestris pv. vesicatoria trigger plant reactions dependent on a conserved N-myristoylation motif. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1250-61. [PMID: 17918627 DOI: 10.1094/mpmi-20-10-1250] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Pathogenicity of the gram-negative plant pathogen Xanthomonas campestris pv. vesicatoria depends on a type III secretion system, which translocates bacterial effector proteins into the plant cell. In this study, we identified two novel type III effectors, XopE1 and XopE2 (Xanthomonas outer proteins), using the AvrBs3 effector domain as reporter. XopE1 and XopE2 belong to the HopX family and possess a conserved putative N-myristoylation motif that is also present in the effector XopJ from X. campestris pv. vesicatoria 85-10. XopJ is a member of the YopJ/AvrRxv family of acetyltransferases. Confocal laser scanning microscopy and immunocytochemistry revealed that green fluorescent protein fusions of XopE1, XopE2, and XopJ localized to the plant cell plasma membrane. Targeting to the membrane is probably due to N-myristoylation, because a point mutation in the putative myristoylated glycine residue G2 in XopE1, XopE2, and XopJ resulted in cytoplasmic localization of the mutant proteins. Results of hydroxylamine treatments of XopE2 protein extracts suggest that the proteins are additionally anchored in the host cell plasma membrane by palmitoylation. The membrane localization of the effectors strongly influences the phenotypes they trigger in the plant. Agrobacterium-mediated expression of xopE1 and xopJ in Nicotiana benthamiana led to cell-death reactions that, for xopJ, were dependent on the N-myristoylation motif. In the case of xopE1(G2A), cell death was more pronounced with the mutant than with the wild-type protein. In addition, XopE2 has an avirulence activity in Solanum pseudocapsicum.
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Affiliation(s)
- Frank Thieme
- Institut für Biologie, Bereich Genetik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle/Saale, Germany
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da Cunha L, Sreerekha MV, Mackey D. Defense suppression by virulence effectors of bacterial phytopathogens. CURRENT OPINION IN PLANT BIOLOGY 2007; 10:349-57. [PMID: 17625953 DOI: 10.1016/j.pbi.2007.04.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 04/19/2007] [Accepted: 04/25/2007] [Indexed: 05/16/2023]
Abstract
Phytopathogenic bacteria and plants are locked in molecular struggles that determine the outcome of an infection. Bacteria make effector molecules that can induce defenses if recognized by specific host resistance (R) proteins. In susceptible hosts, however, effectors frequently promote virulence by suppressing host defenses. Defense-inducing and defense-suppressing activities are often related, as virulence-associated host modifications can elicit R protein activation. Thus, understanding of how an effector elicits defenses can translate into understanding of how it promotes virulence and vice versa. To control host cell functions, such as defense gene expression and vesicle trafficking, effectors use various biochemical activities, including protein modification, transcriptional regulation, and hormone mimicry. Progress with individual effectors will lead to an integrated view of how the activities of a collection of effectors intersect with genetically variable host plants to regulate susceptibility and resistance.
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Affiliation(s)
- Luis da Cunha
- Department of Horticulture and Crop Science, Program in Plant Molecular Biology and Biotechnology, The Ohio State University, Columbus, OH 43210, USA
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