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Howe GA, Major IT, Koo AJ. Modularity in Jasmonate Signaling for Multistress Resilience. ANNUAL REVIEW OF PLANT BIOLOGY 2018; 69:387-415. [PMID: 29539269 DOI: 10.1146/annurev-arplant-042817-040047] [Citation(s) in RCA: 413] [Impact Index Per Article: 59.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The plant hormone jasmonate coordinates immune and growth responses to increase plant survival in unpredictable environments. The core jasmonate signaling pathway comprises several functional modules, including a repertoire of COI1-JAZ (CORONATINE INSENSITIVE1-JASMONATE-ZIM DOMAIN) coreceptors that couple jasmonoyl-l-isoleucine perception to the degradation of JAZ repressors, JAZ-interacting transcription factors that execute physiological responses, and multiple negative feedback loops to ensure timely termination of these responses. Here, we review the jasmonate signaling pathway with an emphasis on understanding how transcriptional responses are specific, tunable, and evolvable. We explore emerging evidence that JAZ proteins integrate multiple informational cues and mediate crosstalk by propagating changes in protein-protein interaction networks. We also discuss recent insights into the evolution of jasmonate signaling and highlight how plant-associated organisms manipulate the pathway to subvert host immunity. Finally, we consider how this mechanistic foundation can accelerate the rational design of jasmonate signaling for improving crop resilience and harnessing the wellspring of specialized plant metabolites.
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Affiliation(s)
- Gregg A Howe
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA; ,
- Department of Biochemistry and Molecular Biology, and Plant Resilience Institute, Michigan State University, East Lansing, Michigan 48824, USA
| | - Ian T Major
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA; ,
| | - Abraham J Koo
- Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, USA;
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102
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The role of chloroplasts in plant pathology. Essays Biochem 2018; 62:21-39. [PMID: 29273582 DOI: 10.1042/ebc20170020] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 11/22/2017] [Accepted: 11/28/2017] [Indexed: 12/13/2022]
Abstract
Plants have evolved complex tolerance systems to survive abiotic and biotic stresses. Central to these programmes is a sophisticated conversation of signals between the chloroplast and the nucleus. In this review, we examine the antagonism between abiotic stress tolerance (AST) and immunity: we propose that to generate immunogenic signals, plants must disable AST systems, in particular those that manage reactive oxygen species (ROS), while the pathogen seeks to reactivate or enhance those systems to achieve virulence. By boosting host systems of AST, pathogens trick the plant into suppressing chloroplast immunogenic signals and steer the host into making an inappropriate immune response. Pathogens disrupt chloroplast function, both transcriptionally-by secreting effectors that alter host gene expression by interacting with defence-related kinase cascades, with transcription factors, or with promoters themselves-and post-transcriptionally, by delivering effectors that enter the chloroplast or alter the localization of host proteins to change chloroplast activities. These mechanisms reconfigure the chloroplast proteome and chloroplast-originating immunogenic signals in order to promote infection.
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103
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Shaban M, Miao Y, Ullah A, Khan AQ, Menghwar H, Khan AH, Ahmed MM, Tabassum MA, Zhu L. Physiological and molecular mechanism of defense in cotton against Verticillium dahliae. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 125:193-204. [PMID: 29462745 DOI: 10.1016/j.plaphy.2018.02.011] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/08/2018] [Accepted: 02/10/2018] [Indexed: 05/19/2023]
Abstract
Cotton, a natural fiber producing crop of huge importance for textile industry, has been reckoned as the backbone in the economy of many developing countries. Verticillium wilt caused by Verticillium dahliae reflected as the most devastating disease of cotton crop in several parts of the world. Average losses due to attack of this disease are tremendous every year. There is urgent need to develop strategies for effective control of this disease. In the last decade, progress has been made to understand the interaction between cotton-V. dahliae and several growth and pathogenicity related genes were identified. Still, most of the molecular components and mechanisms of cotton defense against Verticillium wilt are poorly understood. However, from existing knowledge, it is perceived that cotton defense mechanism primarily depends on the pre-formed defense structures including thick cuticle, synthesis of phenolic compounds and delaying or hindering the expansion of the invader through advanced measures such as reinforcement of cell wall structure, accumulation of reactive oxygen species (ROS), release of phytoalexins, the hypersensitive response and the development of broad spectrum resistance named as, systemic acquired resistance (SAR). Investigation of these defense tactics provide valuable information about the improvement of cotton breeding strategies for the development of durable, cost effective, and broad spectrum resistant varieties. Consequently, this management approach will help to reduce the use of fungicides and also minimize other environmental hazards. In the present paper, we summarized the V. dahliae virulence mechanism and comprehensively discussed the cotton molecular mechanisms of defense such as physiological, biochemical responses with the addition of signaling pathways that are implicated towards attaining resistance against Verticillium wilt.
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Affiliation(s)
- Muhammad Shaban
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Yuhuan Miao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Abid Ullah
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Anam Qadir Khan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Hakim Menghwar
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Aamir Hamid Khan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Muhammad Mahmood Ahmed
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China
| | - Muhammad Adnan Tabassum
- Department of Agronomy, College of Agriculture and Environmental Sciences, The Islamia University of Bahawalpur, Punjab, Pakistan
| | - Longfu Zhu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei 430070, PR China.
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104
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He X, Zhu L, Wassan GM, Wang Y, Miao Y, Shaban M, Hu H, Sun H, Zhang X. GhJAZ2 attenuates cotton resistance to biotic stresses via the inhibition of the transcriptional activity of GhbHLH171. MOLECULAR PLANT PATHOLOGY 2018; 19:896-908. [PMID: 28665036 PMCID: PMC6638010 DOI: 10.1111/mpp.12575] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 05/29/2017] [Accepted: 06/26/2017] [Indexed: 05/19/2023]
Abstract
Plants have evolved effective mechanisms to protect themselves against multiple stresses, and employ jasmonates (JAs) as vital defence signals to defend against pathogen infection. The accumulation of JA, induced by signals from biotic and abiotic stresses, results in the degradation of Jasmonate-ZIM-domain (JAZ) proteins, followed by the de-repression of JAZ-repressed transcription factors (such as MYC2) to activate defence responses and developmental processes. Here, we characterized a JAZ family protein, GhJAZ2, from cotton (Gossypium hirsutum) which was induced by methyl jasmonate (MeJA) and inoculation of Verticillium dahliae. The overexpression of GhJAZ2 in cotton impairs the sensitivity to JA, decreases the expression level of JA-response genes (GhPDF1.2 and GhVSP) and enhances the susceptibility to V. dahliae and insect herbivory. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that GhJAZ2 may be involved in the regulation of cotton disease resistance by interaction with further disease-response proteins, such as pathogenesis-related protein GhPR10, dirigent-like protein GhD2, nucleotide-binding site leucine-rich repeat (NBS-LRR) disease-resistant protein GhR1 and a basic helix-loop-helix transcription factor GhbHLH171. Unlike MYC2, overexpression of GhbHLH171 in cotton activates the JA synthesis and signalling pathway, and improves plant tolerance to the fungus V. dahliae. Molecular and genetic evidence shows that GhJAZ2 can interact with GhbHLH171 and inhibit its transcriptional activity and, as a result, can restrain the JA-mediated defence response. This study provides new insights into the molecular mechanisms of GhJAZ2 in the regulation of the cotton defence response.
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Affiliation(s)
- Xin He
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Longfu Zhu
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Ghulam Mustafa Wassan
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Yujing Wang
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Yuhuan Miao
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Muhammad Shaban
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Haiyan Hu
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Heng Sun
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic ImprovementHuazhong Agricultural UniversityWuhanHubei430070China
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105
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Rufián JS, Macho AP, Corry DS, Mansfield JW, Ruiz‐Albert J, Arnold DL, Beuzón CR. Confocal microscopy reveals in planta dynamic interactions between pathogenic, avirulent and non-pathogenic Pseudomonas syringae strains. MOLECULAR PLANT PATHOLOGY 2018; 19:537-551. [PMID: 28120374 PMCID: PMC6638015 DOI: 10.1111/mpp.12539] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/12/2017] [Accepted: 01/17/2017] [Indexed: 05/04/2023]
Abstract
Recent advances in genomics and single-cell analysis have demonstrated the extraordinary complexity reached by microbial populations within their hosts. Communities range from complex multispecies groups to homogeneous populations differentiating into lineages through genetic or non-genetic mechanisms. Diversity within bacterial populations is recognized as a key driver of the evolution of animal pathogens. In plants, however, little is known about how interactions between different pathogenic and non-pathogenic variants within the host impact on defence responses, or how the presence within a mixture may affect the development or the fate of each variant. Using confocal fluorescence microscopy, we analysed the colonization of the plant apoplast by individual virulence variants of Pseudomonas syringae within mixed populations. We found that non-pathogenic variants can proliferate and even spread beyond the inoculated area to neighbouring tissues when in close proximity to pathogenic bacteria. The high bacterial concentrations reached at natural entry points promote such interactions during the infection process. We also found that a diversity of interactions take place at a cellular level between virulent and avirulent variants, ranging from dominant negative effects on proliferation of virulent bacteria to in trans suppression of defences triggered by avirulent bacteria. Our results illustrate the spatial dynamics and complexity of the interactions found within mixed infections, and their potential impact on pathogen evolution.
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Affiliation(s)
- José S. Rufián
- Instituto de Hortofruticultura Subtropical y Mediterranea “La Mayora”Universidad de Malaga‐Consejo Superior de Investigaciones Cientificas (IHSM‐UMA‐CSIC), Departamento Biologia Celular, Genetica y Fisiologia, Campus de Teatinos, Malaga E‐29071, Spain
| | - Alberto P. Macho
- Instituto de Hortofruticultura Subtropical y Mediterranea “La Mayora”Universidad de Malaga‐Consejo Superior de Investigaciones Cientificas (IHSM‐UMA‐CSIC), Departamento Biologia Celular, Genetica y Fisiologia, Campus de Teatinos, Malaga E‐29071, Spain
- Present address:
Shanghai Center for Plant Stress Biology, Shanghai Institutes of Biological SciencesChinese Academy of SciencesShanghai201602China
| | - David S. Corry
- Centre for Research in Bioscience, Faculty of Health and Applied SciencesUniversity of the West of England, Frenchay CampusBristolBS16 1QYUK
| | | | - Javier Ruiz‐Albert
- Instituto de Hortofruticultura Subtropical y Mediterranea “La Mayora”Universidad de Malaga‐Consejo Superior de Investigaciones Cientificas (IHSM‐UMA‐CSIC), Departamento Biologia Celular, Genetica y Fisiologia, Campus de Teatinos, Malaga E‐29071, Spain
| | - Dawn L. Arnold
- Centre for Research in Bioscience, Faculty of Health and Applied SciencesUniversity of the West of England, Frenchay CampusBristolBS16 1QYUK
| | - Carmen R. Beuzón
- Instituto de Hortofruticultura Subtropical y Mediterranea “La Mayora”Universidad de Malaga‐Consejo Superior de Investigaciones Cientificas (IHSM‐UMA‐CSIC), Departamento Biologia Celular, Genetica y Fisiologia, Campus de Teatinos, Malaga E‐29071, Spain
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106
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Üstün S, Hafrén A, Liu Q, Marshall RS, Minina EA, Bozhkov PV, Vierstra RD, Hofius D. Bacteria Exploit Autophagy for Proteasome Degradation and Enhanced Virulence in Plants. THE PLANT CELL 2018; 30:668-685. [PMID: 29500318 PMCID: PMC5894834 DOI: 10.1105/tpc.17.00815] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/09/2018] [Accepted: 03/01/2018] [Indexed: 05/21/2023]
Abstract
Autophagy and the ubiquitin-proteasome system (UPS) are two major protein degradation pathways implicated in the response to microbial infections in eukaryotes. In animals, the contribution of autophagy and the UPS to antibacterial immunity is well documented and several bacteria have evolved measures to target and exploit these systems to the benefit of infection. In plants, the UPS has been established as a hub for immune responses and is targeted by bacteria to enhance virulence. However, the role of autophagy during plant-bacterial interactions is less understood. Here, we have identified both pro- and antibacterial functions of autophagy mechanisms upon infection of Arabidopsis thaliana with virulent Pseudomonas syringae pv tomato DC3000 (Pst). We show that Pst activates autophagy in a type III effector (T3E)-dependent manner and stimulates the autophagic removal of proteasomes (proteaphagy) to support bacterial proliferation. We further identify the T3E Hrp outer protein M1 (HopM1) as a principle mediator of autophagy-inducing activities during infection. In contrast to the probacterial effects of Pst-induced proteaphagy, NEIGHBOR OF BRCA1-dependent selective autophagy counteracts disease progression and limits the formation of HopM1-mediated water-soaked lesions. Together, we demonstrate that distinct autophagy pathways contribute to host immunity and bacterial pathogenesis during Pst infection and provide evidence for an intimate crosstalk between proteasome and autophagy in plant-bacterial interactions.
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Affiliation(s)
- Suayib Üstün
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Anders Hafrén
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Qinsong Liu
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Richard S Marshall
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Elena A Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Peter V Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
| | - Richard D Vierstra
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130
| | - Daniel Hofius
- Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 75007 Uppsala, Sweden
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107
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Zhang T, Meng L, Kong W, Yin Z, Wang Y, Schneider JD, Chen S. Quantitative proteomics reveals a role of JAZ7 in plant defense response to Pseudomonas syringae DC3000. J Proteomics 2018; 175:114-126. [DOI: 10.1016/j.jprot.2018.01.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/15/2017] [Accepted: 01/02/2018] [Indexed: 12/11/2022]
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108
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Patra B, Pattanaik S, Schluttenhofer C, Yuan L. A network of jasmonate-responsive bHLH factors modulate monoterpenoid indole alkaloid biosynthesis in Catharanthus roseus. THE NEW PHYTOLOGIST 2018; 217:1566-1581. [PMID: 29178476 DOI: 10.1111/nph.14910] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/21/2017] [Indexed: 05/07/2023]
Abstract
The pharmaceutically valuable monoterpene indole alkaloids (MIAs) in Catharanthus roseus are derived from the indole and iridoid pathways that respond to jasmonate (JA) signaling. Two classes of JA-responsive bHLH transcription factor (TF), CrMYC2 and BIS1/BIS2, are known to regulate the indole and iridoid pathways, respectively. However, upregulation of either one of the TF genes does not lead to increased MIA accumulation. Moreover, little is known about the interconnection between the CrMYC2 and BIS transcriptional cascades and the hierarchical position of BIS1/BIS2 in JA signaling. Here, we report that a newly identified bHLH factor, Repressor of MYC2 Targets 1 (RMT1), is activated by CrMYC2 and BIS1, and acts as a repressor of the CrMYC2 targets. In addition, we isolated and functionally characterized the core C. roseus JA signaling components, including CORONATINE INSENSITIVE 1 (COI1) and JASMONATE ZIM domain (JAZ) proteins. CrMYC2 and BIS1 are repressed by the JAZ proteins in the absence of JA, but de-repressed by the SCFCOI1 complex on perception of JA. Our findings suggest that the repressors, JAZs and RMT1, mediate crosstalk between the CrMYC2 and BIS regulatory cascades to balance the metabolic flux in MIA biosynthesis.
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Affiliation(s)
- Barunava Patra
- Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, 1401 University Drive, Lexington, KY, 40546, USA
| | - Sitakanta Pattanaik
- Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, 1401 University Drive, Lexington, KY, 40546, USA
| | - Craig Schluttenhofer
- Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, 1401 University Drive, Lexington, KY, 40546, USA
| | - Ling Yuan
- Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, 1401 University Drive, Lexington, KY, 40546, USA
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China
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109
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Abstract
Pseudomonas syringae is one of the best-studied plant pathogens and serves as a model for understanding host-microorganism interactions, bacterial virulence mechanisms and host adaptation of pathogens as well as microbial evolution, ecology and epidemiology. Comparative genomic studies have identified key genomic features that contribute to P. syringae virulence. P. syringae has evolved two main virulence strategies: suppression of host immunity and creation of an aqueous apoplast to form its niche in the phyllosphere. In addition, external environmental conditions such as humidity profoundly influence infection. P. syringae may serve as an excellent model to understand virulence and also of how pathogenic microorganisms integrate environmental conditions and plant microbiota to become ecologically robust and diverse pathogens of the plant kingdom.
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110
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Khan M, Seto D, Subramaniam R, Desveaux D. Oh, the places they'll go! A survey of phytopathogen effectors and their host targets. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:651-663. [PMID: 29160935 DOI: 10.1111/tpj.13780] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/03/2017] [Accepted: 11/07/2017] [Indexed: 05/09/2023]
Abstract
Phytopathogens translocate effector proteins into plant cells where they sabotage the host cellular machinery to promote infection. An individual pathogen can translocate numerous distinct effectors during the infection process to target an array of host macromolecules (proteins, metabolites, DNA, etc.) and manipulate them using a variety of enzymatic activities. In this review, we have surveyed the literature for effector targets and curated them to convey the range of functions carried out by phytopathogenic proteins inside host cells. In particular, we have curated the locations of effector targets, as well as their biological and molecular functions and compared these properties across diverse phytopathogens. This analysis validates previous observations about effector functions (e.g. immunosuppression), and also highlights some interesting features regarding effector specificity as well as functional diversification of phytopathogen virulence strategies.
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Affiliation(s)
- Madiha Khan
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Derek Seto
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Rajagopal Subramaniam
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
- Agriculture and Agri-Food Canada/Agriculture et Agroalimentaire Canada, KW Neatby bldg, 960 Carling Ave., Ottawa, ON, K1A 0C6, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
- Centre for the Analysis of Genome Function and Evolution, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
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111
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Plett JM, Martin FM. Know your enemy, embrace your friend: using omics to understand how plants respond differently to pathogenic and mutualistic microorganisms. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:729-746. [PMID: 29265527 DOI: 10.1111/tpj.13802] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Revised: 12/04/2017] [Accepted: 12/07/2017] [Indexed: 05/21/2023]
Abstract
Microorganisms, or 'microbes', have formed intimate associations with plants throughout the length of their evolutionary history. In extant plant systems microbes still remain an integral part of the ecological landscape, impacting plant health, productivity and long-term fitness. Therefore, to properly understand the genetic wiring of plants, we must first determine what perception systems plants have evolved to parse beneficial from commensal from pathogenic microbes. In this review, we consider some of the most recent advances in how plants respond at the molecular level to different microbial lifestyles. Further, we cover some of the means by which microbes are able to manipulate plant signaling pathways through altered destructiveness and nutrient sinks, as well as the use of effector proteins and micro-RNAs (miRNAs). We conclude by highlighting some of the major questions still to be answered in the field of plant-microbe research, and suggest some of the key areas that are in greatest need of further research investment. The results of these proposed studies will have impacts in a wide range of plant research disciplines and will, ultimately, translate into stronger agronomic crops and forestry stock, with immune perception and response systems bred to foster beneficial microbial symbioses while repudiating pathogenic symbioses.
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Affiliation(s)
- Jonathan M Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Francis M Martin
- Institut National de la Recherche Agronomique (INRA), Unité Mixte de Recherche, 1136 INRA-Université de Lorraine, Interactions Arbres/Microorganismes, Laboratoire d'excellence ARBRE, Centre INRA-Grand Est-Nancy, 54280, Champenoux, France
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112
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Stahl E, Hilfiker O, Reymond P. Plant-arthropod interactions: who is the winner? THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:703-728. [PMID: 29160609 DOI: 10.1111/tpj.13773] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 10/27/2017] [Accepted: 10/31/2017] [Indexed: 05/17/2023]
Abstract
Herbivorous arthropods have interacted with plants for millions of years. During feeding they release chemical cues that allow plants to detect the attack and mount an efficient defense response. A signaling cascade triggers the expression of hundreds of genes, which encode defensive proteins and enzymes for synthesis of toxic metabolites. This direct defense is often complemented by emission of volatiles that attract beneficial parasitoids. In return, arthropods have evolved strategies to interfere with plant defenses, either by producing effectors to inhibit detection and downstream signaling steps, or by adapting to their detrimental effect. In this review, we address the current knowledge on the molecular and chemical dialog between plants and herbivores, with an emphasis on co-evolutionary aspects.
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Affiliation(s)
- Elia Stahl
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Olivier Hilfiker
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
| | - Philippe Reymond
- Department of Plant Molecular Biology, University of Lausanne, Biophore Building, 1015, Lausanne, Switzerland
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113
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Hassan JA, de la Torre‐Roche R, White JC, Lewis JD. Soil mixture composition alters Arabidopsis susceptibility to Pseudomonas syringae infection. PLANT DIRECT 2018; 2:e00044. [PMID: 31245710 PMCID: PMC6508533 DOI: 10.1002/pld3.44] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/08/2018] [Accepted: 01/23/2018] [Indexed: 05/25/2023]
Abstract
Pseudomonas syringae is a gram-negative bacterial pathogen that causes disease on more than 100 different plant species, including the model plant Arabidopsis thaliana. Dissection of the Arabidopsis thaliana-Pseudomonas syringae pathosystem has identified many factors that contribute to successful infection or immunity, including the genetics of the host, the genetics of the pathogen, and the environment. Environmental factors that contribute to a successful interaction can include temperature, light, and the circadian clock, as well as the soil environment. As silicon-amended Resilience soil is advertised to enhance plant health, we sought to examine the extent to which this soil might affect the behavior of the A. thaliana-P. syringae model pathosystem and to characterize the mechanisms through which these effects may occur. We found that plants grown in Si-amended Resilience soil displayed enhanced resistance to bacteria compared to plants grown in non-Si-amended Sunshine soil, and salicylic acid biosynthesis and signaling were not required for resistance. Although silicon has been shown to contribute to broad-spectrum resistance, our data indicate that silicon is not the direct cause of enhanced resistance and that the Si-amended Resilience soil has additional properties that modulate plant resistance. Our work demonstrates the importance of environmental factors, such as soil in modulating interactions between the plant and foliar pathogens, and highlights the significance of careful annotation of the environmental conditions under which plant-pathogen interactions are studied.
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Affiliation(s)
- Jana A. Hassan
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
| | | | - Jason C. White
- Department of Analytical ChemistryThe Connecticut Agricultural Experiment StationNew HavenCTUSA
| | - Jennifer D. Lewis
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
- Plant Gene Expression CenterUnited States Department of AgricultureAlbanyCAUSA
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114
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Büttner D. Behind the lines-actions of bacterial type III effector proteins in plant cells. FEMS Microbiol Rev 2018; 40:894-937. [PMID: 28201715 PMCID: PMC5091034 DOI: 10.1093/femsre/fuw026] [Citation(s) in RCA: 193] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/31/2016] [Accepted: 07/03/2016] [Indexed: 01/30/2023] Open
Abstract
Pathogenicity of most Gram-negative plant-pathogenic bacteria depends on the type III secretion (T3S) system, which translocates bacterial effector proteins into plant cells. Type III effectors modulate plant cellular pathways to the benefit of the pathogen and promote bacterial multiplication. One major virulence function of type III effectors is the suppression of plant innate immunity, which is triggered upon recognition of pathogen-derived molecular patterns by plant receptor proteins. Type III effectors also interfere with additional plant cellular processes including proteasome-dependent protein degradation, phytohormone signaling, the formation of the cytoskeleton, vesicle transport and gene expression. This review summarizes our current knowledge on the molecular functions of type III effector proteins with known plant target molecules. Furthermore, plant defense strategies for the detection of effector protein activities or effector-triggered alterations in plant targets are discussed.
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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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115
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Kunkel BN, Harper CP. The roles of auxin during interactions between bacterial plant pathogens and their hosts. JOURNAL OF EXPERIMENTAL BOTANY 2018; 69:245-254. [PMID: 29272462 DOI: 10.1093/jxb/erx447] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Plant pathogens have evolved several strategies to manipulate the biology of their hosts to facilitate colonization, growth to high levels in plant tissue, and production of disease. One of the less well known of these strategies is the synthesis of plant hormones and hormone analogs, and there is growing evidence that modulation of host hormone signaling is important during pathogenesis. Several plant pathogens produce the auxin indole-3-acetic acid (IAA) and/or virulence factors that modulate host auxin signaling. Auxin is well known for being involved in many aspects of plant growth and development, but recent findings have revealed that elevated IAA levels or enhanced auxin signaling can also promote disease development in some plant-pathogen interactions. In addition to stimulating plant cell growth during infection by gall-forming bacteria, auxin and auxin signaling can antagonize plant defense responses. Auxin can also act as a microbial signaling molecule to impact the biology of some pathogens directly. In this review, we summarize recent progress towards elucidating the roles that auxin production, modification of host auxin signaling, and direct effects of auxin on pathogens play during pathogenesis, with emphasis on the impacts of auxin on interactions with bacterial pathogens.
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Affiliation(s)
- Barbara N Kunkel
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
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116
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Tripathi D, Zhang T, Koo AJ, Stacey G, Tanaka K. Extracellular ATP Acts on Jasmonate Signaling to Reinforce Plant Defense. PLANT PHYSIOLOGY 2018; 176:511-523. [PMID: 29180381 PMCID: PMC6108377 DOI: 10.1104/pp.17.01477] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 11/22/2017] [Indexed: 05/20/2023]
Abstract
Damaged cells send various signals to stimulate defense responses. Recent identification and genetic studies of the plant purinoceptor, P2K1 (also known as DORN1), have demonstrated that extracellular ATP is a signal involved in plant stress responses, including wounding, perhaps to evoke plant defense. However, it remains largely unknown how extracellular ATP induces plant defense responses. Here, we demonstrate that extracellular ATP induces plant defense mediated through activation of the intracellular signaling of jasmonate (JA), a well-characterized defense hormone. In Arabidopsis (Arabidopsis thaliana) leaves, ATP pretreatment induced resistance against the necrotrophic fungus, Botrytis cinerea The induced resistance was enhanced in the P2K1 receptor overexpression line, but reduced in the receptor mutant, dorn1-3 Mining the transcriptome data revealed that ATP induces a set of JA-induced genes. In addition, the P2K1-associated coexpression network contains defense-related genes, including those encoding jasmonate ZIM-domain (JAZ) proteins, which play key roles as repressors of JA signaling. We examined whether extracellular ATP impacts the stability of JAZ1 in Arabidopsis. The results showed that the JAZ1 stability decreased in response to ATP addition in a proteasome-dependent manner. This reduction required intracellular signaling via second messengers-cytosolic calcium, reactive oxygen species, and nitric oxide. Interestingly, the ATP-induced JAZ1 degradation was attenuated in the JA receptor mutant, coi1, but not in the JA biosynthesis mutant, aos, or upon addition of JA biosynthesis inhibitors. Immunoprecipitation analysis demonstrated that ATP increases the interaction between COI1 and JAZ1, suggesting direct cross talk between extracellular ATP and JA in intracellular signaling events. Taken together, these results suggest that extracellular ATP signaling directly impacts the JA signaling pathway to maximize plant defense responses.
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Affiliation(s)
- Diwaker Tripathi
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164
| | - Tong Zhang
- Divisions of Plant Sciences and Biochemistry, University of Missouri, Columbia, Missouri 65211
| | - Abraham J Koo
- Divisions of Plant Sciences and Biochemistry, University of Missouri, Columbia, Missouri 65211
| | - Gary Stacey
- Divisions of Plant Sciences and Biochemistry, University of Missouri, Columbia, Missouri 65211
| | - Kiwamu Tanaka
- Department of Plant Pathology, Washington State University, Pullman, Washington 99164
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Liu F, Sun T, Wang L, Su W, Gao S, Su Y, Xu L, Que Y. Plant jasmonate ZIM domain genes: shedding light on structure and expression patterns of JAZ gene family in sugarcane. BMC Genomics 2017; 18:771. [PMID: 29020924 PMCID: PMC5637078 DOI: 10.1186/s12864-017-4142-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Accepted: 10/02/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Sugarcane smut caused by Sporisorium scitamineum is one of the most severe fungal diseases in the sugarcane industry. Using a molecular biological technique to mine sugarcane resistance genes can provide gene resources for further genetic engineering of sugarcane disease-resistant breeding. Jasmonate ZIM (zinc-finger inflorescence meristem) domain (JAZ) proteins, which involved in the responses to plant pathogens and abiotic stresses, are important signaling molecules of the jasmonic acid (JA) pathway. RESULTS Seven differentially expressed sugarcane JAZ genes, ScJAZ1-ScJAZ7, were mined from the transcriptome of sugarcane after inoculation with S. scitamineum. Bioinformatic analyses revealed that these seven ScJAZ genes encoded basic proteins that contain the TIFY and CCT_2 domains. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis demonstrated that the ScJAZ1-ScJAZ7 genes were tissue specific and differentially expressed under adverse stress. During S. scitamineum infection, the transcripts of ScJAZ4 and ScJAZ5 were both upregulated in the susceptible genotype ROC22 and the resistant genotype Yacheng05-179; ScJAZ1, ScJAZ2, ScJAZ3, and ScJAZ7 were downregulated in Yacheng05-179 and upregulated in ROC22; and the expression of ScJAZ6 did not change in ROC22, but was upregulated in Yacheng05-179. The transcripts of the seven ScJAZ genes were increased by the stimuli of salicylic acid and abscisic acid, particularly methyl jasmonate. The expression of the genes ScJAZ1-ScJAZ7 was immediately upregulated by the stressors hydrogen peroxide, sodium chloride, and copper chloride, whereas slightly induced after treatment with calcium chloride and polyethylene glycol. In addition, the expression of ScJAZ6, as well as seven tobacco immunity-associated marker genes were upregulated, and antimicrobial activity against Pseudomonas solanacearum and Fusarium solani var. coeruleum was observed during the transient overexpression of ScJAZ6 in Nicotiana benthamiana, suggesting that the ScJAZ6 gene is associated with plant immunity. CONCLUSIONS The different expression profiles of the ScJAZ1-ScJAZ7 genes during S. scitamineum infection, the positive response of ScJAZ1-ScJAZ7 to hormones and abiotic treatments, and the function analysis of the ScJAZ6 gene revealed their involvement in the defense against biotic and abiotic stresses. The findings of the present study facilitate further research on the ScJAZ gene family especially their regulatory mechanism in sugarcane.
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Affiliation(s)
- Feng Liu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Tingting Sun
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Ling Wang
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Weihua Su
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Shiwu Gao
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Yachun Su
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Liping Xu
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Youxiong Que
- Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Crop Science, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
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Rizzi YS, Cecchini NM, Fabro G, Alvarez ME. Differential control and function of Arabidopsis ProDH1 and ProDH2 genes on infection with biotrophic and necrotrophic pathogens. MOLECULAR PLANT PATHOLOGY 2017; 18:1164-1174. [PMID: 27526663 PMCID: PMC6638284 DOI: 10.1111/mpp.12470] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 08/12/2016] [Accepted: 08/14/2016] [Indexed: 05/05/2023]
Abstract
Arabidopsis contains two proline dehydrogenase (ProDH) genes, ProDH1 and ProDH2, encoding for homologous and functional isoenzymes. Although ProDH1 has been studied extensively, especially under abiotic stress, ProDH2 has only started to be analysed in recent years. These genes display distinctive expression patterns and show weak transcriptional co-regulation, but are both activated in pathogen-infected tissues. We have demonstrated previously that Arabidopsis plants with silenced ProDH1/2 expression fail to trigger defences against the hemibiotrophic bacterial pathogen Pseudomonas syringae pv. tomato AvrRpm1 (Pst-AvrRpm1), and that ProDH1 and ProDH2 are differentially regulated by salicylic acid (SA). In the current work, we used prodh1 and prodh2 single-mutant plants to assess the particular contribution of each gene to resistance against Pst-AvrRpm1 and the necrotrophic fungal pathogen Botrytis cinerea. In addition, we studied the sensitivity of ProDH1 and ProDH2 to the jasmonic acid (JA) defence pathway. We found that ProDH1 and ProDH2 are both necessary to achieve maximum resistance against Pst-AvrRpm1 and B. cinerea. However, ProDH2 has a major effect on early restriction of B. cinerea growth. Interestingly, ProDH1 is up-regulated by SA and JA, whereas ProDH2 is only activated by JA, and both genes display transcriptional inter-regulation at basal and infection conditions. These studies provide the first evidence of the contribution of ProDH2 to disease resistance, and describe the differential regulation and non-redundant but complementary function of both enzyme isoforms in infected tissues, providing support for a fundamental role of ProDH in the control of biotrophic and necrotrophic pathogens.
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Affiliation(s)
- Yanina Soledad Rizzi
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química BiológicaFacultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad UniversitariaCórdobaX5000HUAArgentina
| | - Nicolás Miguel Cecchini
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química BiológicaFacultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad UniversitariaCórdobaX5000HUAArgentina
| | - Georgina Fabro
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química BiológicaFacultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad UniversitariaCórdobaX5000HUAArgentina
| | - María Elena Alvarez
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química BiológicaFacultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad UniversitariaCórdobaX5000HUAArgentina
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119
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Panchal S, Melotto M. Stomate-based defense and environmental cues. PLANT SIGNALING & BEHAVIOR 2017; 12:e1362517. [PMID: 28816601 PMCID: PMC5640185 DOI: 10.1080/15592324.2017.1362517] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/25/2017] [Accepted: 07/27/2017] [Indexed: 05/24/2023]
Abstract
Environmental conditions play crucial roles in modulating immunity and disease in plants. For instance, many bacterial disease outbreaks occur after periods of high humidity and rain. A critical step in bacterial infection is entry into the plant interior through wounds or natural openings, such as stomata. Bacterium-triggered stomatal closure is an integral part of the plant immune response to reduce pathogen invasion. Recently, we found that high humidity compromises stomatal defense, which is accompanied by regulation of the salicylic acid and jasmonic acid pathways in guard cells. Periods of darkness, when most stomata are closed, are effective in decreasing pathogen penetration into leaves. However, coronatine produced by Pseudomonas syringae pv. tomato (Pst) DC3000 cells can open dark-closed stomata facilitating infection. Thus, a well-known disease-promoting environmental condition (high humidity) acts in part by suppressing stomatal defense, whereas an anti-stomatal defense factor such as coronatine, may provide epidemiological advantages to ensure bacterial infection when environmental conditions (darkness and insufficient humidity) favor stomatal defense.
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Affiliation(s)
- Shweta Panchal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, CA, USA
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120
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Lu H, McClung CR, Zhang C. Tick Tock: Circadian Regulation of Plant Innate Immunity. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:287-311. [PMID: 28590878 DOI: 10.1146/annurev-phyto-080516-035451] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Many living organisms on Earth have evolved the ability to integrate environmental and internal signals to determine time and thereafter adjust appropriately their metabolism, physiology, and behavior. The circadian clock is the endogenous timekeeper critical for multiple biological processes in many organisms. A growing body of evidence supports the importance of the circadian clock for plant health. Plants activate timed defense with various strategies to anticipate daily attacks of pathogens and pests and to modulate responses to specific invaders in a time-of-day-dependent manner (gating). Pathogen infection is also known to reciprocally modulate clock activity. Such a cross talk likely reflects the adaptive nature of plants to coordinate limited resources for growth, development, and defense. This review summarizes recent progress in circadian regulation of plant innate immunity with a focus on the molecular events linking the circadian clock and defense. More and better knowledge of clock-defense cross talk could help to improve disease resistance and productivity in economically important crops.
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Affiliation(s)
- Hua Lu
- Department of Biological Sciences, University of Maryland-Baltimore County, Baltimore, Maryland 21052;
| | - C Robertson McClung
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755
| | - Chong Zhang
- Department of Biological Sciences, University of Maryland-Baltimore County, Baltimore, Maryland 21052;
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121
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Shigenaga AM, Berens ML, Tsuda K, Argueso CT. Towards engineering of hormonal crosstalk in plant immunity. CURRENT OPINION IN PLANT BIOLOGY 2017. [PMID: 28624670 DOI: 10.1016/j.pbi.2017.04.021] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Plant hormones regulate physiological responses in plants, including responses to pathogens and beneficial microbes. The last decades have provided a vast amount of evidence about the contribution of different plant hormones to plant immunity, and also of how they cooperate to orchestrate immunity activation, in a process known as hormone crosstalk. In this review we highlight the complexity of hormonal crosstalk in immunity and approaches currently being used to further understand this process, as well as perspectives to engineer hormone crosstalk for enhanced pathogen resistance and overall plant fitness.
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Affiliation(s)
- Alexandra M Shigenaga
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA
| | - Matthias L Berens
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany
| | - Kenichi Tsuda
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.
| | - Cristiana T Argueso
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA.
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122
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Nakano M, Oda K, Mukaihara T. Ralstonia solanacearum novel E3 ubiquitin ligase (NEL) effectors RipAW and RipAR suppress pattern-triggered immunity in plants. MICROBIOLOGY (READING, ENGLAND) 2017; 163:992-1002. [PMID: 28708051 DOI: 10.1099/mic.0.000495] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Ralstonia solanacearum is the causal agent of bacterial wilt in solanaceous crops. This pathogen injects more than 70 effector proteins into host plant cells via the Hrp type III secretion system to cause a successful infection. However, the function of these effectors in plant cells, especially in the suppression of plant immunity, remains largely unknown. In this study, we characterized two Ralstonia solanacearum effectors, RipAW and RipAR, which share homology with the IpaH family of effectors from animal and plant pathogenic bacteria, that have a novel E3 ubiquitin ligase (NEL) domain. Recombinant RipAW and RipAR show E3 ubiquitin ligase activity in vitro. RipAW and RipAR localized to the cytoplasm of plant cells and significantly suppressed pattern-triggered immunity (PTI) responses such as the production of reactive oxygen species and the expression of defence-related genes when expressed in leaves of Nicotiana benthamiana. Mutation in the conserved cysteine residue in the NEL domain of RipAW completely abolished the E3 ubiquitin ligase activity in vitro and the ability to suppress PTI responses in plant leaves. These results indicate that RipAW suppresses plant PTI responses through the E3 ubiquitin ligase activity. Unlike other members of the IpaH family of effectors, RipAW and RipAR had no leucine-rich repeat motifs in their amino acid sequences. A conserved C-terminal region of RipAW is indispensable for PTI suppression. Transgenic Arabidopsis plants expressing RipAW and RipAR showed increased disease susceptibility, suggesting that RipAW and RipAR contribute to bacterial virulence in plants.
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Affiliation(s)
- Masahito Nakano
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
| | - Kenji Oda
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
| | - Takafumi Mukaihara
- Research Institute for Biological Sciences, Okayama (RIBS), 7549-1 Yoshikawa, Kibichuo-cho, Okayama 716-1241, Japan
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123
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Henry E, Toruño TY, Jauneau A, Deslandes L, Coaker G. Direct and Indirect Visualization of Bacterial Effector Delivery into Diverse Plant Cell Types during Infection. THE PLANT CELL 2017; 29:1555-1570. [PMID: 28600390 PMCID: PMC5559743 DOI: 10.1105/tpc.17.00027] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 05/22/2017] [Accepted: 06/08/2017] [Indexed: 05/04/2023]
Abstract
To cause disease, diverse pathogens deliver effector proteins into host cells. Pathogen effectors can inhibit defense responses, alter host physiology, and represent important cellular probes to investigate plant biology. However, effector function and localization have primarily been investigated after overexpression in planta. Visualizing effector delivery during infection is challenging due to the plant cell wall, autofluorescence, and low effector abundance. Here, we used a GFP strand system to directly visualize bacterial effectors delivered into plant cells through the type III secretion system. GFP is a beta barrel that can be divided into 11 strands. We generated transgenic Arabidopsis thaliana plants expressing GFP1-10 (strands 1 to 10). Multiple bacterial effectors tagged with the complementary strand 11 epitope retained their biological function in Arabidopsis and tomato (Solanum lycopersicum). Infection of plants expressing GFP1-10 with bacteria delivering GFP11-tagged effectors enabled direct effector detection in planta. We investigated the temporal and spatial delivery of GFP11-tagged effectors during infection with the foliar pathogen Pseudomonas syringae and the vascular pathogen Ralstonia solanacearum Thus, the GFP strand system can be broadly used to investigate effector biology in planta.
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Affiliation(s)
- Elizabeth Henry
- Department of Plant Pathology, University of California, Davis, California 95616
| | - Tania Y Toruño
- Department of Plant Pathology, University of California, Davis, California 95616
| | - Alain Jauneau
- Institut Fédératif de Recherche 3450, Université de Toulouse, CNRS, UPS, Plateforme Imagerie TRI-Genotoul, Castanet-Tolosan 31326, France
| | - Laurent Deslandes
- LIPM, Université de Toulouse, INRA, CNRS, UPS, Castanet-Tolosan, France
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, California 95616
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124
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Melotto M, Zhang L, Oblessuc PR, He SY. Stomatal Defense a Decade Later. PLANT PHYSIOLOGY 2017; 174:561-571. [PMID: 28341769 PMCID: PMC5462020 DOI: 10.1104/pp.16.01853] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/22/2017] [Indexed: 05/18/2023]
Abstract
A decade has passed since the discovery of stomatal defense, and the field has expanded considerably with significant understanding of the basic mechanisms underlying the process.
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Affiliation(s)
- Maeli Melotto
- Department of Plant Sciences, University of California, Davis, California 95616 (M.M., P.R.O.);
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.);
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.); and
- Plant Resilience Institute, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824 (S.Y.H.)
| | - Li Zhang
- Department of Plant Sciences, University of California, Davis, California 95616 (M.M., P.R.O.)
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.)
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.); and
- Plant Resilience Institute, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824 (S.Y.H.)
| | - Paula R Oblessuc
- Department of Plant Sciences, University of California, Davis, California 95616 (M.M., P.R.O.)
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.)
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.); and
- Plant Resilience Institute, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824 (S.Y.H.)
| | - Sheng Yang He
- Department of Plant Sciences, University of California, Davis, California 95616 (M.M., P.R.O.);
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.);
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (L.Z., S.Y.H.); and
- Plant Resilience Institute, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824 (S.Y.H.)
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125
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Zhang L, Zhang F, Melotto M, Yao J, He SY. Jasmonate signaling and manipulation by pathogens and insects. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1371-1385. [PMID: 28069779 PMCID: PMC6075518 DOI: 10.1093/jxb/erw478] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/01/2016] [Indexed: 05/18/2023]
Abstract
Plants synthesize jasmonates (JAs) in response to developmental cues or environmental stresses, in order to coordinate plant growth, development or defense against pathogens and herbivores. Perception of pathogen or herbivore attack promotes synthesis of jasmonoyl-L-isoleucine (JA-Ile), which binds to the COI1-JAZ receptor, triggering the degradation of JAZ repressors and induction of transcriptional reprogramming associated with plant defense. Interestingly, some virulent pathogens have evolved various strategies to manipulate JA signaling to facilitate their exploitation of plant hosts. In this review, we focus on recent advances in understanding the mechanism underlying the enigmatic switch between transcriptional repression and hormone-dependent transcriptional activation of JA signaling. We also discuss various strategies used by pathogens and insects to manipulate JA signaling and how interfering with this could be used as a novel means of disease control.
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Affiliation(s)
- Li Zhang
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
| | - Feng Zhang
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824
- Laboratory of Structural Sciences and Laboratory of Structural Biology and Biochemistry, Van Andel Research Institute, Grand Rapids, MI 49503
- College of Plant Protection, Nanjing Agricultural University, No. 1 Weigang, 210095, Nanjing, Jiangsu Province, China
| | - Maeli Melotto
- Department of Plant Sciences, University of California, Davis, CA 95616
| | - Jian Yao
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI 49008
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI 48824
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824
- Plant Resilience Institute, Michigan State University, East Lansing, MI 48824
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI 48824
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Huang H, Liu B, Liu L, Song S. Jasmonate action in plant growth and development. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1349-1359. [PMID: 28158849 DOI: 10.1093/jxb/erw495] [Citation(s) in RCA: 359] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Phytohormones, including jasmonates (JAs), gibberellin, ethylene, abscisic acid, and auxin, integrate endogenous developmental cues with environmental signals to regulate plant growth, development, and defense. JAs are well- recognized lipid-derived stress hormones that regulate plant adaptations to biotic stresses, including herbivore attack and pathogen infection, as well as abiotic stresses, including wounding, ozone, and ultraviolet radiation. An increasing number of studies have shown that JAs also have functions in a remarkable number of plant developmental events, including primary root growth, reproductive development, and leaf senescence. Since the 1980s, details of the JA biosynthesis pathway, signaling pathway, and crosstalk during plant growth and development have been elucidated. Here, we summarize recent advances and give an updated overview of JA action and crosstalk in plant growth and development.
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Affiliation(s)
- Huang Huang
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Bei Liu
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Liangyu Liu
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Susheng Song
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
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Wasternack C, Song S. Jasmonates: biosynthesis, metabolism, and signaling by proteins activating and repressing transcription. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1303-1321. [PMID: 27940470 DOI: 10.1093/jxb/erw443] [Citation(s) in RCA: 179] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 11/07/2016] [Indexed: 05/21/2023]
Abstract
The lipid-derived phytohormone jasmonate (JA) regulates plant growth, development, secondary metabolism, defense against insect attack and pathogen infection, and tolerance to abiotic stresses such as wounding, UV light, salt, and drought. JA was first identified in 1962, and since the 1980s many studies have analyzed the physiological functions, biosynthesis, distribution, metabolism, perception, signaling, and crosstalk of JA, greatly expanding our knowledge of the hormone's action. In response to fluctuating environmental cues and transient endogenous signals, the occurrence of multilayered organization of biosynthesis and inactivation of JA, and activation and repression of the COI1-JAZ-based perception and signaling contributes to the fine-tuning of JA responses. This review describes the JA biosynthetic enzymes in terms of gene families, enzymatic activity, location and regulation, substrate specificity and products, the metabolic pathways in converting JA to activate or inactivate compounds, JA signaling in perception, and the co-existence of signaling activators and repressors.
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Affiliation(s)
- Claus Wasternack
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Palacký University, Institute of Experimental Botany AS CR, Šlechtitelu 11, CZ 78371 Olomouc, Czech Republic
| | - Susheng Song
- Beijing Key Laboratory of Plant Gene Resources and Biotechnology for Carbon Reduction and Environmental Improvement, College of Life Sciences, Capital Normal University, Beijing 100048, China
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Cui H, Gobbato E, Kracher B, Qiu J, Bautor J, Parker JE. A core function of EDS1 with PAD4 is to protect the salicylic acid defense sector in Arabidopsis immunity. THE NEW PHYTOLOGIST 2017; 213:1802-1817. [PMID: 27861989 DOI: 10.1111/nph.14302] [Citation(s) in RCA: 183] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 09/23/2016] [Indexed: 05/19/2023]
Abstract
Plant defenses induced by salicylic acid (SA) are vital for resistance against biotrophic pathogens. In basal and receptor-triggered immunity, SA accumulation is promoted by Enhanced Disease Susceptibility1 with its co-regulator Phytoalexin Deficient4 (EDS1/PAD4). Current models position EDS1/PAD4 upstream of SA but their functional relationship remains unclear. In a genetic and transcriptomic analysis of Arabidopsis autoimmunity caused by constitutive or conditional EDS1/PAD4 overexpression, intrinsic EDS1/PAD4 signaling properties and their relation to SA were uncovered. A core EDS1/PAD4 pathway works in parallel with SA in basal and effector-triggered bacterial immunity. It protects against disabled SA-regulated gene expression and pathogen resistance, and is distinct from a known SA-compensatory route involving MAPK signaling. Results help to explain previously identified EDS1/PAD4 regulated SA-dependent and SA-independent gene expression sectors. Plants have evolved an alternative route for preserving SA-regulated defenses against pathogen or genetic perturbations. In a proposed signaling framework, EDS1 with PAD4, besides promoting SA biosynthesis, maintains important SA-related resistance programs, thereby increasing robustness of the innate immune system.
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Affiliation(s)
- Haitao Cui
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Enrico Gobbato
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Barbara Kracher
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jingde Qiu
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jaqueline Bautor
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
| | - Jane E Parker
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, Carl-von-Linné Weg 10, 50829, Cologne, Germany
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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: 102] [Impact Index Per Article: 12.8] [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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130
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Huysmans M, Lema A S, Coll NS, Nowack MK. Dying two deaths - programmed cell death regulation in development and disease. CURRENT OPINION IN PLANT BIOLOGY 2017; 35:37-44. [PMID: 27865098 DOI: 10.1016/j.pbi.2016.11.005] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/28/2016] [Accepted: 11/03/2016] [Indexed: 05/18/2023]
Abstract
Programmed cell death (PCD) is a fundamental cellular process that has adopted a plethora of vital functions in multicellular organisms. In plants, PCD processes are elicited as an inherent part of regular development in specific cell types or tissues, but can also be triggered by biotic and abiotic stresses. Although over the last years we have seen progress in our understanding of the molecular regulation of different plant PCD processes, it is still unclear whether a common core machinery exists that controls cell death in development and disease. In this review, we discuss recent advances in the field, comparing some aspects of the molecular regulation controlling developmental and pathogen-triggered PCD in plants.
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Affiliation(s)
- Marlies Huysmans
- VIB Department of Plant Systems Biology, 9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
| | - Saul Lema A
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Valles 08193, Catalonia, Spain
| | - Nuria S Coll
- Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB-UB), Bellaterra-Cerdanyola del Valles 08193, Catalonia, Spain.
| | - Moritz K Nowack
- VIB Department of Plant Systems Biology, 9052 Gent, Belgium; Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium.
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131
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Wu D, Qi T, Li WX, Tian H, Gao H, Wang J, Ge J, Yao R, Ren C, Wang XB, Liu Y, Kang L, Ding SW, Xie D. Viral effector protein manipulates host hormone signaling to attract insect vectors. Cell Res 2017; 27:402-415. [PMID: 28059067 DOI: 10.1038/cr.2017.2] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/07/2016] [Accepted: 10/24/2016] [Indexed: 12/12/2022] Open
Abstract
Some plant and animal pathogens can manipulate their hosts to cause them to release odors that are attractive to the pathogens' arthropod vectors. However, the molecular mechanism underlying this process is largely unexplored, and the specific effectors the pathogens employ as well as the pathways within the hosts they target are currently unknown. Here we reveal that the aphid-borne cucumber mosaic virus (CMV) employs its 2b protein, a well-characterized viral suppressor of host RNA interference (VSR), to target the host's jasmonate (JA) hormone pathway, thus acting as a viral inducer of host attractiveness to insect vectors (VIA). 2b inhibits JA signaling by directly interacting with and repressing JA-induced degradation of host jasmonate ZIM-domain proteins, instead of using its VSR activity. Our findings identify a previously defined VSR protein as a VIA and uncover a molecular mechanism CMV uses to manipulate host's attractiveness to insect vectors by targeting host hormone signaling.
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Affiliation(s)
- Dewei Wu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tiancong Qi
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wan-Xiang Li
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - Haixia Tian
- College of Bioscience and Biotechnology, Crop Gene Engineering Key Laboratory of Hunan Province, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Hua Gao
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiaojiao Wang
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jin Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Ruifeng Yao
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Chunmei Ren
- College of Bioscience and Biotechnology, Crop Gene Engineering Key Laboratory of Hunan Province, Hunan Agricultural University, Changsha, Hunan 410128, China
| | - Xian-Bing Wang
- State Key Laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yule Liu
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shou-Wei Ding
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA 92521, USA
| | - Daoxin Xie
- Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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132
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Kondo M, Hirai H, Furukawa T, Yoshida Y, Suzuki A, Kawaguchi T, Che FS. Frameshift Mutation Confers Function as Virulence Factor to Leucine-Rich Repeat Protein from Acidovorax avenae. FRONTIERS IN PLANT SCIENCE 2017; 7:1988. [PMID: 28101092 PMCID: PMC5209373 DOI: 10.3389/fpls.2016.01988] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 12/15/2016] [Indexed: 06/06/2023]
Abstract
Many plant pathogens inject type III (T3SS) effectors into host cells to suppress host immunity and promote successful infection. The bacterial pathogen Acidovorax avenae causes brown stripe symptom in many species of monocotyledonous plants; however, individual strains of each pathogen infect only one host species. T3SS-deleted mutants of A. avenae K1 (virulent to rice) or N1141 (virulent to finger millet) caused no symptom in each host plant, suggesting that T3SS effectors are involved in the symptom formation. To identify T3SS effectors as virulence factors, we performed whole-genome and predictive analyses. Although the nucleotide sequence of the novel leucine-rich repeat protein (Lrp) gene of N1141 had high sequence identity with K1 Lrp, the amino acid sequences of the encoded proteins were quite different due to a 1-bp insertion within the K1 Lrp gene. An Lrp-deleted K1 strain (KΔLrp) did not cause brown stripe symptom in rice (host plant for K1); by contrast, the analogous mutation in N1141 (NΔLrp) did not interfere with infection of finger millet. In addition, NΔLrp retained the ability to induce effector-triggered immunity (ETI), including hypersensitive response cell death and expression of ETI-related genes. These data indicated that K1 Lrp functions as a virulence factor in rice, whereas N1141 Lrp does not play a similar role in finger millet. Yeast two-hybrid screening revealed that K1 Lrp interacts with oryzain α, a pathogenesis-related protein of the cysteine protease family, whereas N1141 Lrp, which contains LRR domains, does not. This specific interaction between K1 Lrp and oryzain α was confirmed by Bimolecular fluorescence complementation assay in rice cells. Thus, K1 Lrp protein may have acquired its function as virulence factor in rice due to a frameshift mutation.
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133
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Toum L, Torres PS, Gallego SM, Benavídes MP, Vojnov AA, Gudesblat GE. Coronatine Inhibits Stomatal Closure through Guard Cell-Specific Inhibition of NADPH Oxidase-Dependent ROS Production. FRONTIERS IN PLANT SCIENCE 2016; 7:1851. [PMID: 28018388 PMCID: PMC5155495 DOI: 10.3389/fpls.2016.01851] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 11/23/2016] [Indexed: 05/19/2023]
Abstract
Microbes trigger stomatal closure through microbe-associated molecular patterns (MAMPs). The bacterial pathogen Pseudomonas syringae pv. tomato (Pst) synthesizes the polyketide toxin coronatine, which inhibits stomatal closure by MAMPs and by the hormone abscisic acid (ABA). The mechanism by which coronatine, a jasmonic acid-isoleucine analog, achieves this effect is not completely clear. Reactive oxygen species (ROS) are essential second messengers in stomatal immunity, therefore we investigated the possible effect of coronatine on their production. We found that coronatine inhibits NADPH oxidase-dependent ROS production induced by ABA, and by the flagellin-derived peptide flg22. This toxin also inhibited NADPH oxidase-dependent stomatal closure induced by darkness, however, it failed to prevent stomatal closure by exogenously applied H2O2 or by salicylic acid, which induces ROS production through peroxidases. Contrary to what was observed on stomata, coronatine did not affect the oxidative burst induced by flg22 in leaf disks. Additionally, we observed that in NADPH oxidase mutants atrbohd and atrbohd/f, as well as in guard cell ABA responsive but flg22 insensitive mutants mpk3, mpk6, npr1-3, and lecrk-VI.2-1, the inhibition of ABA stomatal responses by both coronatine and the NADPH oxidase inhibitor diphenylene iodonium was markedly reduced. Interestingly, coronatine still impaired ABA-induced ROS synthesis in mpk3, mpk6, npr1-3, and lecrk-VI.2-1, suggesting a possible feedback regulation of ROS on other guard cell ABA signaling elements in these mutants. Altogether our results show that inhibition of NADPH oxidase-dependent ROS synthesis in guard cells plays an important role during endophytic colonization by Pst through stomata.
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Affiliation(s)
- Laila Toum
- Instituto de Ciencia y Tecnología Dr. César Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Pablo S. Torres
- Instituto de Ciencia y Tecnología Dr. César Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Susana M. Gallego
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos AiresBuenos Aires, Argentina
| | - María P. Benavídes
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos AiresBuenos Aires, Argentina
| | - Adrián A. Vojnov
- Instituto de Ciencia y Tecnología Dr. César Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
| | - Gustavo E. Gudesblat
- Instituto de Ciencia y Tecnología Dr. César Milstein, Fundación Pablo Cassará, Consejo Nacional de Investigaciones Científicas y TécnicasBuenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada, Departamento de Biodiversidad y Biología Experimental, Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos AiresBuenos Aires, Argentina
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134
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Martin F, Kohler A, Murat C, Veneault-Fourrey C, Hibbett DS. Unearthing the roots of ectomycorrhizal symbioses. Nat Rev Microbiol 2016; 14:760-773. [PMID: 27795567 DOI: 10.1038/nrmicro.2016.149] [Citation(s) in RCA: 208] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
During the diversification of Fungi and the rise of conifer-dominated and angiosperm- dominated forests, mutualistic symbioses developed between certain trees and ectomycorrhizal fungi that enabled these trees to colonize boreal and temperate regions. The evolutionary success of these symbioses is evident from phylogenomic analyses that suggest that ectomycorrhizal fungi have arisen in approximately 60 independent saprotrophic lineages, which has led to the wide range of ectomycorrhizal associations that exist today. In this Review, we discuss recent genomic studies that have revealed the adaptations that seem to be fundamental to the convergent evolution of ectomycorrhizal fungi, including the loss of some metabolic functions and the acquisition of effectors that facilitate mutualistic interactions with host plants. Finally, we consider how these insights can be integrated into a model of the development of ectomycorrhizal symbioses.
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Affiliation(s)
- Francis Martin
- Institut national de la recherche agronomique (INRA), Unité Mixte de Recherche 1136 Interactions Arbres/Microorganismes, Laboratoire d'excellence Recherches Avancés sur la Biologie de l'Arbre et les Ecosystèmes Forestiers (ARBRE), Centre INRA-Lorraine, 54280 Champenoux, France
| | - Annegret Kohler
- Institut national de la recherche agronomique (INRA), Unité Mixte de Recherche 1136 Interactions Arbres/Microorganismes, Laboratoire d'excellence Recherches Avancés sur la Biologie de l'Arbre et les Ecosystèmes Forestiers (ARBRE), Centre INRA-Lorraine, 54280 Champenoux, France
| | - Claude Murat
- Institut national de la recherche agronomique (INRA), Unité Mixte de Recherche 1136 Interactions Arbres/Microorganismes, Laboratoire d'excellence Recherches Avancés sur la Biologie de l'Arbre et les Ecosystèmes Forestiers (ARBRE), Centre INRA-Lorraine, 54280 Champenoux, France
| | - Claire Veneault-Fourrey
- Université de Lorraine, Unité Mixte de Recherche 1136 Interactions Arbres/Microorganismes, Laboratoire d'excellence Recherches Avancées sur la Biologie de l'Arbre et les Ecosystèmes Forestiers (ARBRE), 54500 Vandoeuvre-lès-Nancy, France
| | - David S Hibbett
- Biology Department, Clark University, Lasry Center for Bioscience, 950 Main Street, Worcester, Massachusetts 01610, USA
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135
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YopJ Family Effectors Promote Bacterial Infection through a Unique Acetyltransferase Activity. Microbiol Mol Biol Rev 2016; 80:1011-1027. [PMID: 27784797 DOI: 10.1128/mmbr.00032-16] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Gram-negative bacterial pathogens rely on the type III secretion system to inject virulence proteins into host cells. These type III secreted "effector" proteins directly manipulate cellular processes to cause disease. Although the effector repertoires in different bacterial species are highly variable, the Yersinia outer protein J (YopJ) effector family is unique in that its members are produced by diverse animal and plant pathogens as well as a nonpathogenic microsymbiont. All YopJ family effectors share a conserved catalytic triad that is identical to that of the C55 family of cysteine proteases. However, an accumulating body of evidence demonstrates that many YopJ effectors modify their target proteins in hosts by acetylating specific serine, threonine, and/or lysine residues. This unique acetyltransferase activity allows the YopJ family effectors to affect the function and/or stability of their targets, thereby dampening innate immunity. Here, we summarize the current understanding of this prevalent and evolutionarily conserved type III effector family by describing their enzymatic activities and virulence functions in animals and plants. In particular, the molecular mechanisms by which representative YopJ family effectors subvert host immunity through posttranslational modification of their target proteins are discussed.
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136
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Pfeilmeier S, Caly DL, Malone JG. Bacterial pathogenesis of plants: future challenges from a microbial perspective: Challenges in Bacterial Molecular Plant Pathology. MOLECULAR PLANT PATHOLOGY 2016; 17:1298-313. [PMID: 27170435 PMCID: PMC6638335 DOI: 10.1111/mpp.12427] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/08/2016] [Accepted: 05/10/2016] [Indexed: 05/03/2023]
Abstract
Plant infection is a complicated process. On encountering a plant, pathogenic microorganisms must first adapt to life on the epiphytic surface, and survive long enough to initiate an infection. Responsiveness to the environment is critical throughout infection, with intracellular and community-level signal transduction pathways integrating environmental signals and triggering appropriate responses in the bacterial population. Ultimately, phytopathogens must migrate from the epiphytic surface into the plant tissue using motility and chemotaxis pathways. This migration is coupled with overcoming the physical and chemical barriers to entry into the plant apoplast. Once inside the plant, bacteria use an array of secretion systems to release phytotoxins and protein effectors that fulfil diverse pathogenic functions (Fig. ) (Melotto and Kunkel, ; Phan Tran et al., ). As our understanding of the pathways and mechanisms underpinning plant pathogenicity increases, a number of central research challenges are emerging that will profoundly shape the direction of research in the future. We need to understand the bacterial phenotypes that promote epiphytic survival and surface adaptation in pathogenic bacteria. How do these pathways function in the context of the plant-associated microbiome, and what impact does this complex microbial community have on the onset and severity of plant infections? The huge importance of bacterial signal transduction to every stage of plant infection is becoming increasingly clear. However, there is a great deal to learn about how these signalling pathways function in phytopathogenic bacteria, and the contribution they make to various aspects of plant pathogenicity. We are increasingly able to explore the structural and functional diversity of small-molecule natural products from plant pathogens. We need to acquire a much better understanding of the production, deployment, functional redundancy and physiological roles of these molecules. Type III secretion systems (T3SSs) are important and well-studied contributors to bacterial disease. Several key unanswered questions will shape future investigations of these systems. We need to define the mechanism of hierarchical and temporal control of effector secretion. For successful infection, effectors need to interact with host components to exert their function. Advanced biochemical, proteomic and cell biological techniques will enable us to study the function of effectors inside the host cell in more detail and on a broader scale. Population genomics analyses provide insight into evolutionary adaptation processes of phytopathogens. The determination of the diversity and distribution of type III effectors (T3Es) and other virulence genes within and across pathogenic species, pathovars and strains will allow us to understand how pathogens adapt to specific hosts, the evolutionary pathways available to them, and the possible future directions of the evolutionary arms race between effectors and molecular plant targets. Although pathogenic bacteria employ a host of different virulence and proliferation strategies, as a result of the space constraints, this review focuses mainly on the hemibiotrophic pathogens. We discuss the process of plant infection from the perspective of these important phytopathogens, and highlight new approaches to address the outstanding challenges in this important and fast-moving field.
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Affiliation(s)
- Sebastian Pfeilmeier
- The Sainsbury Laboratory, Norwich Research Park, Norwich, NR4 7UH, UK
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Delphine L Caly
- Université de Lille, EA 7394, ICV - Institut Charles Viollette, Lille, F-59000, France
| | - Jacob G Malone
- John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK.
- University of East Anglia, Norwich, NR4 7TJ, UK.
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Sundin GW, Wang N, Charkowski AO, Castiblanco LF, Jia H, Zhao Y. Perspectives on the Transition From Bacterial Phytopathogen Genomics Studies to Applications Enhancing Disease Management: From Promise to Practice. PHYTOPATHOLOGY 2016; 106:1071-1082. [PMID: 27183301 DOI: 10.1094/phyto-03-16-0117-fi] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The advent of genomics has advanced science into a new era, providing a plethora of "toys" for researchers in many related and disparate fields. Genomics has also spawned many new fields, including proteomics and metabolomics, furthering our ability to gain a more comprehensive view of individual organisms and of interacting organisms. Genomic information of both bacterial pathogens and their hosts has provided the critical starting point in understanding the molecular bases of how pathogens disrupt host cells to cause disease. In addition, knowledge of the complete genome sequence of the pathogen provides a potentially broad slate of targets for the development of novel virulence inhibitors that are desperately needed for disease management. Regarding plant bacterial pathogens and disease management, the potential for utilizing genomics resources in the development of durable resistance is enhanced because of developing technologies that enable targeted modification of the host. Here, we summarize the role of genomics studies in furthering efforts to manage bacterial plant diseases and highlight novel genomics-enabled strategies heading down this path.
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Affiliation(s)
- George W Sundin
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
| | - Nian Wang
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
| | - Amy O Charkowski
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
| | - Luisa F Castiblanco
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
| | - Hongge Jia
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
| | - Youfu Zhao
- First and fourth authors: Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing; second and fifth authors: Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Lake Alfred; third author: Department of Plant Pathology, University of Wisconsin-Madison; sixth author: Department of Crop Sciences, University of Illinois at Urbana-Champaign
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Toruño TY, Stergiopoulos I, Coaker G. Plant-Pathogen Effectors: Cellular Probes Interfering with Plant Defenses in Spatial and Temporal Manners. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:419-41. [PMID: 27359369 PMCID: PMC5283857 DOI: 10.1146/annurev-phyto-080615-100204] [Citation(s) in RCA: 423] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Plants possess large arsenals of immune receptors capable of recognizing all pathogen classes. To cause disease, pathogenic organisms must be able to overcome physical barriers, suppress or evade immune perception, and derive nutrients from host tissues. Consequently, to facilitate some of these processes, pathogens secrete effector proteins that promote colonization. This review covers recent advances in the field of effector biology, focusing on conserved cellular processes targeted by effectors from diverse pathogens. The ability of effectors to facilitate pathogen entry into the host interior, suppress plant immune perception, and alter host physiology for pathogen benefit is discussed. Pathogens also deploy effectors in a spatial and temporal manner, depending on infection stage. Recent advances have also enhanced our understanding of effectors acting in specific plant organs and tissues. Effectors are excellent cellular probes that facilitate insight into biological processes as well as key points of vulnerability in plant immune signaling networks.
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Affiliation(s)
- Tania Y Toruño
- Department of Plant Pathology, University of California, Davis, California; , ,
| | | | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, California; , ,
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139
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Goossens J, Fernández-Calvo P, Schweizer F, Goossens A. Jasmonates: signal transduction components and their roles in environmental stress responses. PLANT MOLECULAR BIOLOGY 2016; 68:1333-1347. [PMID: 27927998 DOI: 10.1093/jxb/erw440] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Jasmonates, oxylipin-type plant hormones, are implicated in diverse aspects of plant growth development and interaction with the environment. Following diverse developmental and environmental cues, jasmonate is produced, conjugated to the amino acid isoleucine and perceived by a co-receptor complex composed of the Jasmonate ZIM-domain (JAZ) repressor proteins and an E3 ubiquitin ligase complex containing the F-box CORONATINE INSENSITIVE 1 (COI1). This event triggers the degradation of the JAZ proteins and the release of numerous transcription factors, including MYC2 and its homologues, which are otherwise bound and inhibited by the JAZ repressors. Here, we will review the role of the COI1, JAZ and MYC2 proteins in the interaction of the plant with its environment, illustrating the significance of jasmonate signalling, and of the proteins involved, for responses to both biotic stresses caused by insects and numerous microbial pathogens and abiotic stresses caused by adverse climatic conditions. It has also become evident that crosstalk with other hormone signals, as well as light and clock signals, plays an important role in the control and fine-tuning of these stress responses. Finally, we will discuss how several pathogens exploit the jasmonate perception and early signalling machinery to decoy the plants defence systems.
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Affiliation(s)
- Jonas Goossens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Patricia Fernández-Calvo
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Fabian Schweizer
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Alain Goossens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium.
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium.
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140
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Goossens J, Fernández-Calvo P, Schweizer F, Goossens A. Jasmonates: signal transduction components and their roles in environmental stress responses. PLANT MOLECULAR BIOLOGY 2016; 91:673-89. [PMID: 27086135 DOI: 10.1007/s11103-016-0480-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 04/09/2016] [Indexed: 05/20/2023]
Abstract
Jasmonates, oxylipin-type plant hormones, are implicated in diverse aspects of plant growth development and interaction with the environment. Following diverse developmental and environmental cues, jasmonate is produced, conjugated to the amino acid isoleucine and perceived by a co-receptor complex composed of the Jasmonate ZIM-domain (JAZ) repressor proteins and an E3 ubiquitin ligase complex containing the F-box CORONATINE INSENSITIVE 1 (COI1). This event triggers the degradation of the JAZ proteins and the release of numerous transcription factors, including MYC2 and its homologues, which are otherwise bound and inhibited by the JAZ repressors. Here, we will review the role of the COI1, JAZ and MYC2 proteins in the interaction of the plant with its environment, illustrating the significance of jasmonate signalling, and of the proteins involved, for responses to both biotic stresses caused by insects and numerous microbial pathogens and abiotic stresses caused by adverse climatic conditions. It has also become evident that crosstalk with other hormone signals, as well as light and clock signals, plays an important role in the control and fine-tuning of these stress responses. Finally, we will discuss how several pathogens exploit the jasmonate perception and early signalling machinery to decoy the plants defence systems.
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Affiliation(s)
- Jonas Goossens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Patricia Fernández-Calvo
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Fabian Schweizer
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium
| | - Alain Goossens
- Department of Plant Systems Biology, Flanders Institute for Biotechnology, Technologiepark 927, 9052, Ghent, Belgium.
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium.
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141
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Ma KW, Ma W. Phytohormone pathways as targets of pathogens to facilitate infection. PLANT MOLECULAR BIOLOGY 2016; 91:713-25. [PMID: 26879412 PMCID: PMC4932134 DOI: 10.1007/s11103-016-0452-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 02/07/2016] [Indexed: 05/18/2023]
Abstract
Plants are constantly threatened by potential pathogens. In order to optimize the output of defense against pathogens with distinct lifestyles, plants depend on hormonal networks to fine-tune specific responses and regulate growth-defense tradeoffs. To counteract, pathogens have evolved various strategies to disturb hormonal homeostasis and facilitate infection. Many pathogens synthesize plant hormones; more importantly, toxins and effectors are produced to manipulate hormonal crosstalk. Accumulating evidence has shown that pathogens exert extensive effects on plant hormone pathways not only to defeat immunity, but also modify habitat structure, optimize nutrient acquisition, and facilitate pathogen dissemination. In this review, we summarize mechanisms by which a wide array of pathogens gain benefits from manipulating plant hormone pathways.
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Affiliation(s)
- Ka-Wai Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA, 92521, USA.
- Center for Plant Cell Biology, University of California, Riverside, CA, 92521, USA.
| | - Wenbo Ma
- Department of Plant Pathology and Microbiology, University of California, Riverside, CA, 92521, USA.
- Center for Plant Cell Biology, University of California, Riverside, CA, 92521, USA.
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142
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Rai A, Umashankar S, Rai M, Kiat LB, Bing JAS, Swarup S. Coordinate Regulation of Metabolite Glycosylation and Stress Hormone Biosynthesis by TT8 in Arabidopsis. PLANT PHYSIOLOGY 2016; 171:2499-515. [PMID: 27432888 PMCID: PMC4972274 DOI: 10.1104/pp.16.00421] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 06/21/2016] [Indexed: 05/18/2023]
Abstract
Secondary metabolites play a key role in coordinating ecology and defense strategies of plants. Diversity of these metabolites arises by conjugation of core structures with diverse chemical moieties, such as sugars in glycosylation. Active pools of phytohormones, including those involved in plant stress response, are also regulated by glycosylation. While much is known about the enzymes involved in glycosylation, we know little about their regulation or coordination with other processes. We characterized the flavonoid pathway transcription factor TRANSPARENT TESTA8 (TT8) in Arabidopsis (Arabidopsis thaliana) using an integrative omics strategy. This approach provides a systems-level understanding of the cellular machinery that is used to generate metabolite diversity by glycosylation. Metabolomics analysis of TT8 loss-of-function and inducible overexpression lines showed that TT8 coordinates glycosylation of not only flavonoids, but also nucleotides, thus implicating TT8 in regulating pools of activated nucleotide sugars. Transcriptome and promoter network analyses revealed that the TT8 regulome included sugar transporters, proteins involved in sugar binding and sequestration, and a number of carbohydrate-active enzymes. Importantly, TT8 affects stress response, along with brassinosteroid and jasmonic acid biosynthesis, by directly binding to the promoters of key genes of these processes. This combined effect on metabolite glycosylation and stress hormones by TT8 inducible overexpression led to significant increase in tolerance toward multiple abiotic and biotic stresses. Conversely, loss of TT8 leads to increased sensitivity to these stresses. Thus, the transcription factor TT8 is an integrator of secondary metabolism and stress response. These findings provide novel approaches to improve broad-spectrum stress tolerance.
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Affiliation(s)
- Amit Rai
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
| | - Shivshankar Umashankar
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
| | - Megha Rai
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
| | - Lim Boon Kiat
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
| | - Johanan Aow Shao Bing
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
| | - Sanjay Swarup
- Metabolites Biology Lab, Department of Biological Sciences, National University of Singapore, Singapore 117543 (A.R., S.U., M.R., L.B.K., J.A.S.B., S.S.);Synthetic Biology Research Consortium (A.R., S.S.) and Singapore Centre for Environmental Life Science Engineering (S.U., S.S.), National University of Singapore, Singapore 117456;NUS Environmental Research Institute, National University of Singapore, Singapore 117411 (S.U., M.R., L.B.K., S.S.); andSingapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551 (S.S.)
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Mukhtar M, McCormack M, Argueso C, Pajerowska-Mukhtar K. Pathogen Tactics to Manipulate Plant Cell Death. Curr Biol 2016; 26:R608-R619. [DOI: 10.1016/j.cub.2016.02.051] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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145
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Lowe-Power TM, Jacobs JM, Ailloud F, Fochs B, Prior P, Allen C. Degradation of the Plant Defense Signal Salicylic Acid Protects Ralstonia solanacearum from Toxicity and Enhances Virulence on Tobacco. mBio 2016; 7:e00656-16. [PMID: 27329752 PMCID: PMC4916378 DOI: 10.1128/mbio.00656-16] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/09/2016] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Plants use the signaling molecule salicylic acid (SA) to trigger defenses against diverse pathogens, including the bacterial wilt pathogen Ralstonia solanacearum SA can also inhibit microbial growth. Most sequenced strains of the heterogeneous R. solanacearum species complex can degrade SA via gentisic acid to pyruvate and fumarate. R. solanacearum strain GMI1000 expresses this SA degradation pathway during tomato pathogenesis. Transcriptional analysis revealed that subinhibitory SA levels induced expression of the SA degradation pathway, toxin efflux pumps, and some general stress responses. Interestingly, SA treatment repressed expression of virulence factors, including the type III secretion system, suggesting that this pathogen may suppress virulence functions when stressed. A GMI1000 mutant lacking SA degradation activity was much more susceptible to SA toxicity but retained the wild-type colonization ability and virulence on tomato. This may be because SA is less important than gentisic acid in tomato defense signaling. However, another host, tobacco, responds strongly to SA. To test the hypothesis that SA degradation contributes to virulence on tobacco, we measured the effect of adding this pathway to the tobacco-pathogenic R. solanacearum strain K60, which lacks SA degradation genes. Ectopic addition of the GMI1000 SA degradation locus, including adjacent genes encoding two porins and a LysR-type transcriptional regulator, significantly increased the virulence of strain K60 on tobacco. Together, these results suggest that R. solanacearum degrades plant SA to protect itself from inhibitory levels of this compound and also to enhance its virulence on plant hosts like tobacco that use SA as a defense signal molecule. IMPORTANCE Plant pathogens such as the bacterial wilt agent Ralstonia solanacearum threaten food and economic security by causing significant losses for small- and large-scale growers of tomato, tobacco, banana, potato, and ornamentals. Like most plants, these crop hosts use salicylic acid (SA) both indirectly as a signal to activate defenses and directly as an antimicrobial chemical. We found that SA inhibits growth of R. solanacearum and induces a general stress response that includes repression of multiple bacterial wilt virulence factors. The ability to degrade SA reduces the pathogen's sensitivity to SA toxicity and increases its virulence on tobacco.
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Affiliation(s)
- Tiffany M Lowe-Power
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Jonathan M Jacobs
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA Institut de Recherche pour le Développement, UMR Interactions Plantes Microorganismes Environnement, Montpellier, France
| | - Florent Ailloud
- UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-INRA, Saint-Pierre, La Réunion, France Laboratoire de la Santé des Végétaux, Agence Nationale Sécurité Sanitaire Alimentaire Nationale, Saint-Pierre, La Réunion, France
| | - Brianna Fochs
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Philippe Prior
- UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-INRA, Saint-Pierre, La Réunion, France
| | - Caitilyn Allen
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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146
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Shigenaga AM, Argueso CT. No hormone to rule them all: Interactions of plant hormones during the responses of plants to pathogens. Semin Cell Dev Biol 2016; 56:174-189. [PMID: 27312082 DOI: 10.1016/j.semcdb.2016.06.005] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/01/2016] [Accepted: 06/07/2016] [Indexed: 11/17/2022]
Abstract
Plant hormones are essential regulators of plant growth and immunity. In the last few decades, a vast amount of information has been obtained detailing the role of different plant hormones in immunity, and how they work together to ultimately shape the outcomes of plant pathogen interactions. Here we provide an overview on the roles of the main classes of plant hormones in the regulation of plant immunity, highlighting their metabolic and signaling pathways and how plants and pathogens utilize these pathways to activate or suppress defence.
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Affiliation(s)
- Alexandra M Shigenaga
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA
| | - Cristiana T Argueso
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA.
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147
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Serrano I, Audran C, Rivas S. Chloroplasts at work during plant innate immunity. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:3845-54. [PMID: 26994477 DOI: 10.1093/jxb/erw088] [Citation(s) in RCA: 135] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The major role played by chloroplasts during light harvesting, energy production, redox homeostasis, and retrograde signalling processes has been extensively characterized. Beyond the obvious link between chloroplast functions in primary metabolism and as providers of photosynthesis-derived carbon sources and energy, a growing body of evidence supports a central role for chloroplasts as integrators of environmental signals and, more particularly, as key defence organelles. Here, we review the importance of these organelles as primary sites for the biosynthesis and transmission of pro-defence signals during plant immune responses. In addition, we highlight interorganellar communication as a crucial process for amplification of the immune response. Finally, molecular strategies used by microbes to manipulate, directly or indirectly, the production/function of defence-related signalling molecules and subvert chloroplast-based defences are also discussed.
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Affiliation(s)
- Irene Serrano
- LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
| | - Corinne Audran
- LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
| | - Susana Rivas
- LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
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148
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Sun Y, Guo H, Ge F. Plant-Aphid Interactions Under Elevated CO2: Some Cues from Aphid Feeding Behavior. FRONTIERS IN PLANT SCIENCE 2016; 7:502. [PMID: 27148325 PMCID: PMC4829579 DOI: 10.3389/fpls.2016.00502] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/29/2016] [Indexed: 05/18/2023]
Abstract
Although the increasing concentration of atmospheric carbon dioxide (CO2) accelerates the accumulation of carbohydrates and increases the biomass and yield of C3 crop plants, it also reduces their nitrogen concentration. The consequent changes in primary and secondary metabolites affect the palatability of host plants and the feeding of herbivorous insects. Aphids are phloem feeders and are considered the only feeding guild that positively responds to elevated CO2. In this review, we consider how elevated CO2 modifies host defenses, nutrients, and water-use efficiency by altering concentrations of the phytohormones jasmonic acid, salicylic acid, ethylene, and abscisic acid. We will describe how these elevated CO2-induced changes in defenses, nutrients, and water statusfacilitate specific stages of aphid feeding, including penetration, phloem-feeding, and xylem absorption. We conclude that a better understanding of the effects of elevated CO2 on aphids and on aphid damage to crop plants will require research on the molecular aspects of the interaction between plant and aphid but also research on aphid interactions with their intra- and inter-specific competitors and with their natural enemies.
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Affiliation(s)
| | | | - Feng Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijing, China
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149
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Macho AP. Subversion of plant cellular functions by bacterial type-III effectors: beyond suppression of immunity. THE NEW PHYTOLOGIST 2016; 210:51-7. [PMID: 26306858 DOI: 10.1111/nph.13605] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 07/10/2015] [Indexed: 05/20/2023]
Abstract
Most bacterial plant pathogens employ a type-III secretion system to inject type-III effector (T3E) proteins directly inside plant cells. These T3Es manipulate host cellular processes in order to create a permissive niche for bacterial proliferation, allowing development of the disease. An important role of T3Es in plant pathogenic bacteria is the suppression of plant immune responses. However, in recent years, research has uncovered T3E functions different from direct immune suppression, including the modulation of plant hormone signaling, metabolism or organelle function. This insight article discusses T3E functions other than suppression of immunity, which may contribute to the modulation of plant cells in order to promote bacterial survival, nutrient release, and bacterial replication and dissemination.
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Affiliation(s)
- Alberto P Macho
- Shanghai Center for Plant Stress Biology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
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150
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Teper D, Burstein D, Salomon D, Gershovitz M, Pupko T, Sessa G. Identification of novel Xanthomonas euvesicatoria type III effector proteins by a machine-learning approach. MOLECULAR PLANT PATHOLOGY 2016; 17:398-411. [PMID: 26104875 PMCID: PMC6638362 DOI: 10.1111/mpp.12288] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The Gram-negative bacterium Xanthomonas euvesicatoria (Xcv) is the causal agent of bacterial spot disease in pepper and tomato. Xcv pathogenicity depends on a type III secretion (T3S) system that delivers effector proteins into host cells to suppress plant immunity and promote disease. The pool of known Xcv effectors includes approximately 30 proteins, most identified in the 85-10 strain by various experimental and computational techniques. To identify additional Xcv 85-10 effectors, we applied a genome-wide machine-learning approach, in which all open reading frames (ORFs) were scored according to their propensity to encode effectors. Scoring was based on a large set of features, including genomic organization, taxonomic dispersion, hypersensitive response and pathogenicity (hrp)-dependent expression, 5' regulatory sequences, amino acid composition bias and GC content. Thirty-six predicted effectors were tested for translocation into plant cells using the hypersensitive response (HR)-inducing domain of AvrBs2 as a reporter. Seven proteins (XopAU, XopAV, XopAW, XopAP, XopAX, XopAK and XopAD) harboured a functional translocation signal and their translocation relied on the HrpF translocon, indicating that they are bona fide T3S effectors. Remarkably, four belong to novel effector families. Inactivation of the xopAP gene reduced the severity of disease symptoms in infected plants. A decrease in cell death and chlorophyll content was observed in pepper leaves inoculated with the xopAP mutant when compared with the wild-type strain. However, populations of the xopAP mutant in infected leaves were similar in size to those of wild-type bacteria, suggesting that the reduction in virulence was not caused by impaired bacterial growth.
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Affiliation(s)
- Doron Teper
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
| | - David Burstein
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Dor Salomon
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Michael Gershovitz
- Department of Cell Research and Immunology, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Tal Pupko
- Department of Earth and Planetary Science, UC Berkeley, Berkeley, CA, 94720, USA
| | - Guido Sessa
- Department of Molecular Biology and Ecology of Plants, Tel Aviv University, Tel Aviv, 69978, Israel
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