1
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Herold L, Choi S, He SY, Zipfel C. The conserved AvrE family of bacterial effectors: functions and targets during pathogenesis. Trends Microbiol 2024:S0966-842X(24)00222-1. [PMID: 39278787 DOI: 10.1016/j.tim.2024.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/22/2024] [Accepted: 08/22/2024] [Indexed: 09/18/2024]
Abstract
The AvrE family of type III secreted effectors are highly conserved among many agriculturally important phytopathogenic bacteria. Despite their critical roles in the pathogenesis of phytopathogenic bacteria, the molecular functions and virulence mechanisms of these effectors have been largely unknown. However, recent studies have identified host-interacting proteins and demonstrated that AvrE family effectors can form water-permeable channels in the plant plasma membrane (PM) to create a hydrated and nutrient-rich extracellular space (apoplast) required for disease establishment. Here, we summarize these recent discoveries and highlight open questions related to AvrE-targeted host proteins.
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Affiliation(s)
- Laura Herold
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sera Choi
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA; Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | - Cyril Zipfel
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zurich, Switzerland; The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, UK.
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2
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Su GM, Chu LW, Chien CC, Liao PS, Chiu YC, Chang CH, Chu TH, Li CH, Wu CS, Wang JF, Cheng YS, Chang CH, Cheng CP. Tomato NADPH oxidase SlWfi1 interacts with the effector protein RipBJ of Ralstonia solanacearum to mediate host defence. PLANT, CELL & ENVIRONMENT 2024. [PMID: 39132878 DOI: 10.1111/pce.15086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 05/30/2024] [Accepted: 07/31/2024] [Indexed: 08/13/2024]
Abstract
Reactive oxygen species (ROS) play a crucial role in regulating numerous functions in organisms. Among the key regulators of ROS production are NADPH oxidases, primarily referred to as respiratory burst oxidase homologues (RBOHs). However, our understanding of whether and how pathogens directly target RBOHs has been limited. In this study, we revealed that the effector protein RipBJ, originating from the phytopathogenic bacterium Ralstonia solanacearum, was present in low- to medium-virulence strains but absent in high-virulence strains. Functional genetic assays demonstrated that the expression of ripBJ led to a reduction in bacterial infection. In the plant, RipBJ expression triggered plant cell death and the accumulation of H2O2, while also enhancing host defence against R. solanacearum by modulating multiple defence signalling pathways. Through protein interaction and functional studies, we demonstrated that RipBJ was associated with the plant's plasma membrane and interacted with the tomato RBOH known as SlWfi1, which contributed positively to RipBJ's effects on plants. Importantly, SlWfi1 expression was induced during the early stages following R. solanacearum infection and played a key role in defence against this bacterium. This research uncovers the plant RBOH as an interacting target of a pathogen's effector, providing valuable insights into the mechanisms of plant defence.
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Affiliation(s)
- Guan-Ming Su
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Li-Wen Chu
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chih-Cheng Chien
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
- Institute of Ecology and Evolutionary Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Pei-Shan Liao
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yu-Chuan Chiu
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chi-Hsin Chang
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Tai-Hsiang Chu
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chien-Hui Li
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chien-Sheng Wu
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Jaw-Fen Wang
- Bacteriology Unit, AVRDC-The World Vegetable Center, Tainan, Taiwan
| | - Yi-Sheng Cheng
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
- Department of Life Science, College of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chuan-Hsin Chang
- Department of Research, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City, Taiwan
| | - Chiu-Ping Cheng
- Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, Taiwan
- Department of Life Science, College of Life Science, National Taiwan University, Taipei, Taiwan
- Global Agriculture Technology and Genomic Science Master Program, International College, National Taiwan University, Taipei, Taiwan
- Master Program for Plant Medicine, College of Bio-Resources & Agriculture, National Taiwan University, Taipei, Taiwan
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3
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Gong S, Gan H, Chu J, Wang Z, Sun J. A chromosome-level genome assembly provides insights into the local adaptation of Tamarix austromongolica in the Yellow River Basin, China. DNA Res 2024; 31:dsae021. [PMID: 38946223 PMCID: PMC11306577 DOI: 10.1093/dnares/dsae021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 06/06/2024] [Accepted: 06/29/2024] [Indexed: 07/02/2024] Open
Abstract
Tamarix austromongolica is endemic to the Yellow River Basin and has adapted to diverse ecological settings in the region, including the arid areas of northwestern China and the saline soil regions of the Yellow River Delta. However, the genetic basis of its local adaptation remains unclear. We report a chromosome-level assembly of the T. austromongolica genome based on PacBio high-fidelity sequencing and Hi-C technology. The 12 pseudochromosomes cover 98.44% of the 1.32 Gb assembly, with a contig N50 of 52.57 Mb and a BUSCO score of 98.2%. The genome comprises 913.6 Mb (68.83%) of repetitive sequences and 22,374 protein-coding genes. Genome evolution analyses suggest that genes under positive selection and significantly expanded gene families have facilitated T. austromongolica's adaptability to diverse environmental factors and high resistance to diseases. Using genotyping-by-sequencing, we conducted population structure and selection analyses of 114 samples from 15 sites. Two genetic groups were identified, and 114 and 289 candidate genes were assigned to the populations of the northwestern and eastern parts of the Yellow River, respectively. Furthermore, we discovered numerous candidate genes associated with high-altitude adaptability and salt tolerance. This research provides valuable genomic resources for the evolutionary study and genetic breeding of tamarisk.
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Affiliation(s)
- Shuai Gong
- Coastal Forestry Research Center of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China
| | - Honghao Gan
- Coastal Forestry Research Center of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China
| | - Jianmin Chu
- Coastal Forestry Research Center of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China
- Experimental Center of Desert Forestry, Chinese Academy of Forestry, Dengkou 015200, PR China
| | - Zhaoshan Wang
- Coastal Forestry Research Center of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China
| | - Jia Sun
- Coastal Forestry Research Center of National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, PR China
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4
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Ikram AU, Jing Y, Chen H, Chen J. Bacteria deploy water channels to aid infection in plants. TRENDS IN PLANT SCIENCE 2024; 29:620-622. [PMID: 38158301 DOI: 10.1016/j.tplants.2023.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/15/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024]
Abstract
Plant pathogens deliver effector proteins into the plant cell to cause disease. Recently, Nomura et al. discovered that the AvrE family of effectors serve as water channels to release water into the apoplast, causing a phenomenon known as 'water soaking'. A chemical called PAMAM G1 blocks these channels and prevents disease symptoms.
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Affiliation(s)
- Aziz Ul Ikram
- International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Yanping Jing
- International Genome Center, Jiangsu University, Zhenjiang 212013, China
| | - Huan Chen
- Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
| | - Jian Chen
- International Genome Center, Jiangsu University, Zhenjiang 212013, China.
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5
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Roussin-Léveillée C, Mackey D, Ekanayake G, Gohmann R, Moffett P. Extracellular niche establishment by plant pathogens. Nat Rev Microbiol 2024; 22:360-372. [PMID: 38191847 DOI: 10.1038/s41579-023-00999-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2023] [Indexed: 01/10/2024]
Abstract
The plant extracellular space, referred to as the apoplast, is inhabited by a variety of microorganisms. Reflecting the crucial nature of this compartment, both plants and microorganisms seek to control, exploit and respond to its composition. Upon sensing the apoplastic environment, pathogens activate virulence programmes, including the delivery of effectors with well-established roles in suppressing plant immunity. We posit that another key and foundational role of effectors is niche establishment - specifically, the manipulation of plant physiological processes to enrich the apoplast in water and nutritive metabolites. Facets of plant immunity counteract niche establishment by restricting water, nutrients and signals for virulence activation. The complex competition to control and, in the case of pathogens, exploit the apoplast provides remarkable insights into the nature of virulence, host susceptibility, host defence and, ultimately, the origin of phytopathogenesis. This novel framework focuses on the ecology of a microbial niche and highlights areas of future research on plant-microorganism interactions.
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Affiliation(s)
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, USA.
- Department of Molecular Genetics, The Ohio State University, Columbus, OH, USA.
- Center for Applied Plant Sciences, The Ohio State University, Columbus, OH, USA.
| | - Gayani Ekanayake
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, USA
| | - Reid Gohmann
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH, USA
| | - Peter Moffett
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec, Canada.
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6
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Liu Y, Hou S. Bacteria manipulate host cells with channel-forming effectors. Trends Microbiol 2024; 32:8-9. [PMID: 37953153 DOI: 10.1016/j.tim.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 10/30/2023] [Accepted: 10/31/2023] [Indexed: 11/14/2023]
Abstract
Bacterial pathogens deliver effectors into host cells mostly to manipulate signaling and metabolic molecules, thereby subverting host immunity. A recent study by Nomura et al. demonstrates that certain effectors create membrane channels in host cells, enabling bacteria to access water and solutes for multiplication.
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Affiliation(s)
- Yukun Liu
- College of Forestry, Southwest Forestry University, 300 Bailong Si, Kunming, Yunnan 650224, China.
| | - Shuguo Hou
- Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agriculture Sciences in Weifang, Weifang, Shandong 261325, China.
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7
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Duque-Jaramillo A, Ulmer N, Alseekh S, Bezrukov I, Fernie AR, Skirycz A, Karasov TL, Weigel D. The genetic and physiological basis of Arabidopsis thaliana tolerance to Pseudomonas viridiflava. THE NEW PHYTOLOGIST 2023; 240:1961-1975. [PMID: 37667565 DOI: 10.1111/nph.19241] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/15/2023] [Indexed: 09/06/2023]
Abstract
The opportunistic pathogen Pseudomonas viridiflava colonizes > 50 agricultural crop species and is the most common Pseudomonas in the phyllosphere of European Arabidopsis thaliana populations. Belonging to the P. syringae complex, it is genetically and phenotypically distinct from well-characterized P. syringae sensu stricto. Despite its prevalence, we lack knowledge of how A. thaliana responds to its native isolates at the molecular level. Here, we characterize the host response in an A. thaliana - P. viridiflava pathosystem. We measured host and pathogen growth in axenic infections and used immune mutants, transcriptomics, and metabolomics to determine defense pathways influencing susceptibility to P. viridiflava infection. Infection with P. viridiflava increased jasmonic acid (JA) levels and the expression of ethylene defense pathway marker genes. The immune response in a susceptible host accession was delayed compared with a tolerant one. Mechanical injury rescued susceptibility, consistent with an involvement of JA. The JA/ethylene pathway is important for suppression of P. viridiflava, yet suppression capacity varies between accessions. Our results shed light on how A. thaliana can suppress the ever-present P. viridiflava, but further studies are needed to understand how P. viridiflava evades this suppression to spread broadly across A. thaliana populations.
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Affiliation(s)
| | - Nina Ulmer
- Max Planck Institute for Biology Tübingen, Tübingen, 72076, Germany
| | - Saleh Alseekh
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Ilja Bezrukov
- Max Planck Institute for Biology Tübingen, Tübingen, 72076, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
| | - Aleksandra Skirycz
- Max Planck Institute of Molecular Plant Physiology, Potsdam-Golm, 14476, Germany
- Boyce Thompson Institute, Cornell University, Ithaca, 14850, USA
| | - Talia L Karasov
- Max Planck Institute for Biology Tübingen, Tübingen, 72076, Germany
- School of Biological Sciences, University of Utah, Salt Lake City, 84112, USA
| | - Detlef Weigel
- Max Planck Institute for Biology Tübingen, Tübingen, 72076, Germany
- Institute for Bioinformatics and Medical Informatics, University of Tübingen, Tübingen, 72074, Germany
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8
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Bhandari DD, Ko DK, Kim SJ, Nomura K, He SY, Brandizzi F. Defense against phytopathogens relies on efficient antimicrobial protein secretion mediated by the microtubule-binding protein TGNap1. Nat Commun 2023; 14:6357. [PMID: 37821453 PMCID: PMC10567756 DOI: 10.1038/s41467-023-41807-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 09/19/2023] [Indexed: 10/13/2023] Open
Abstract
Plant immunity depends on the secretion of antimicrobial proteins, which occurs through yet-largely unknown mechanisms. The trans-Golgi network (TGN), a hub for intracellular and extracellular trafficking pathways, and the cytoskeleton, which is required for antimicrobial protein secretion, are emerging as pathogen targets to dampen plant immunity. In this work, we demonstrate that tgnap1-2, a loss-of-function mutant of Arabidopsis TGNap1, a TGN-associated and microtubule (MT)-binding protein, is susceptible to Pseudomonas syringae (Pst DC3000). Pst DC3000 infected tgnap1-2 is capable of mobilizing defense pathways, accumulating salicylic acid (SA), and expressing antimicrobial proteins. The susceptibility of tgnap1-2 is due to a failure to efficiently transport antimicrobial proteins to the apoplast in a partially MT-dependent pathway but independent from SA and is additive to the pathogen-antagonizing MIN7, a TGN-associated ARF-GEF protein. Therefore, our data demonstrate that plant immunity relies on TGNap1 for secretion of antimicrobial proteins, and that TGNap1 is a key immunity element that functionally links secretion and cytoskeleton in SA-independent pathogen responses.
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Affiliation(s)
- Deepak D Bhandari
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA
| | - Dae Kwan Ko
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA
| | - Sang-Jin Kim
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Kinya Nomura
- Department of Biology, Duke University, Durham, NC, 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC, 27708, USA
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC, 27708, USA
| | - Federica Brandizzi
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
- Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA.
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.
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9
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Beattie GA. Bacteria deliver water channels to infect plants. Nature 2023; 621:478-479. [PMID: 37704843 DOI: 10.1038/d41586-023-02767-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
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10
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water- and solute-permeable channels to plant cells. Nature 2023; 621:586-591. [PMID: 37704725 PMCID: PMC10511319 DOI: 10.1038/s41586-023-06531-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 08/10/2023] [Indexed: 09/15/2023]
Abstract
Many animal- and plant-pathogenic bacteria use a type III secretion system to deliver effector proteins into host cells1,2. Elucidation of how these effector proteins function in host cells is critical for understanding infectious diseases in animals and plants3-5. The widely conserved AvrE-family effectors, including DspE in Erwinia amylovora and AvrE in Pseudomonas syringae, have a central role in the pathogenesis of diverse phytopathogenic bacteria6. These conserved effectors are involved in the induction of 'water soaking' and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in inward and outward currents, permeability to water and osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine dendrimers as inhibitors of the DspE/AvrE channels. Notably, polyamidoamines broadly inhibit AvrE and DspE virulence activities in Xenopus oocytes and during E. amylovora and P. syringae infections. Thus, we have unravelled the biochemical function of a centrally important family of bacterial effectors with broad conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC, USA.
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC, USA.
- Howard Hughes Medical Institute, Duke University, Durham, NC, USA.
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11
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Nomura K, Andreazza F, Cheng J, Dong K, Zhou P, He SY. Bacterial pathogens deliver water/solute-permeable channels as a virulence strategy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.29.547699. [PMID: 37546725 PMCID: PMC10402153 DOI: 10.1101/2023.07.29.547699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Many animal and plant pathogenic bacteria utilize a type III secretion system to deliver effector proteins into the host cell 1,2 . Elucidation of how these effector proteins function in the host cell is critical for understanding infectious diseases in animals and plants 3-5 . The widely conserved AvrE/DspE-family effectors play a central role in the pathogenesis of diverse phytopathogenic bacteria 6 . These conserved effectors are involved in the induction of "water-soaking" and host cell death that are conducive to bacterial multiplication in infected tissues. However, the exact biochemical functions of AvrE/DspE-family effectors have been recalcitrant to mechanistic understanding for three decades. Here we show that AvrE/DspE-family effectors fold into a β-barrel structure that resembles bacterial porins. Expression of AvrE and DspE in Xenopus oocytes results in (i) inward and outward currents, (ii) permeability to water and (iii) osmolarity-dependent oocyte swelling and bursting. Liposome reconstitution confirmed that the DspE channel alone is sufficient to allow the passage of small molecules such as fluorescein dye. Targeted screening of chemical blockers based on the predicted pore size (15-20 Å) of the DspE channel identified polyamidoamine (PAMAM) dendrimers as inhibitors of the DspE/AvrE channels. Remarkably, PAMAMs broadly inhibit AvrE/DspE virulence activities in Xenopus oocytes and during Erwinia amylovora and Pseudomonas syringae infections. Thus, we have unraveled the enigmatic function of a centrally important family of bacterial effectors with significant conceptual and practical implications in the study of bacterial pathogenesis.
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Affiliation(s)
- Kinya Nomura
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
| | | | - Jie Cheng
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ke Dong
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Pei Zhou
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Sheng Yang He
- Department of Biology, Duke University, Durham, NC 27708, USA
- Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA
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12
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Jiménez-Guerrero I, López-Baena FJ, Medina C. Multitask Approach to Localize Rhizobial Type Three Secretion System Effector Proteins Inside Eukaryotic Cells. PLANTS (BASEL, SWITZERLAND) 2023; 12:plants12112133. [PMID: 37299112 DOI: 10.3390/plants12112133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/25/2023] [Accepted: 05/25/2023] [Indexed: 06/12/2023]
Abstract
Rhizobia can establish mutually beneficial interactions with legume plants by colonizing their roots to induce the formation of a specialized structure known as a nodule, inside of which the bacteria are able to fix atmospheric nitrogen. It is well established that the compatibility of such interactions is mainly determined by the bacterial recognition of flavonoids secreted by the plants, which in response to these flavonoids trigger the synthesis of the bacterial Nod factors that drive the nodulation process. Additionally, other bacterial signals are involved in the recognition and the efficiency of this interaction, such as extracellular polysaccharides or some secreted proteins. Some rhizobial strains inject proteins through the type III secretion system to the cytosol of legume root cells during the nodulation process. Such proteins, called type III-secreted effectors (T3E), exert their function in the host cell and are involved, among other tasks, in the attenuation of host defense responses to facilitate the infection, contributing to the specificity of the process. One of the main challenges of studying rhizobial T3E is the inherent difficulty in localizing them in vivo in the different subcellular compartments within their host cells, since in addition to their low concentration under physiological conditions, it is not always known when or where they are being produced and secreted. In this paper, we use a well-known rhizobial T3E, named NopL, to illustrate by a multitask approach where it localizes in heterologous hosts models, such as tobacco plant leaf cells, and also for the first time in transfected and/or Salmonella-infected animal cells. The consistency of our results serves as an example to study the location inside eukaryotic cells of effectors in distinct hosts with different handling techniques that can be used in almost every research laboratory.
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Affiliation(s)
- Irene Jiménez-Guerrero
- Departamento de Microbiología, Universidad de Sevilla, Avenida de Reina Mercedes, 6, 41012 Sevilla, Spain
| | | | - Carlos Medina
- Departamento de Microbiología, Universidad de Sevilla, Avenida de Reina Mercedes, 6, 41012 Sevilla, Spain
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13
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Tee E, Johnston M, Papp D, Faulkner C. A PDLP-NHL3 complex integrates plasmodesmal immune signaling cascades. Proc Natl Acad Sci U S A 2023; 120:e2216397120. [PMID: 37068237 PMCID: PMC10151459 DOI: 10.1073/pnas.2216397120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 03/20/2023] [Indexed: 04/19/2023] Open
Abstract
The plant immune system relies on the perception of molecules that signal the presence of a microbe threat. This triggers signal transduction that mediates a range of cellular responses via a collection of molecular machinery including receptors, small molecules, and enzymes. One response to pathogen perception is the restriction of cell-to-cell communication by plasmodesmal closure. We previously found that while chitin and flg22 trigger specialized immune signaling cascades in the plasmodesmal plasma membrane, both execute plasmodesmal closure via callose synthesis at the plasmodesmata. Therefore, the signaling pathways ultimately converge at or upstream of callose synthesis. To establish the hierarchy of signaling at plasmodesmata and characterize points of convergence in microbe elicitor-triggered signaling, we profiled the dependence of plasmodesmal responses triggered by different elicitors on a range of plasmodesmal signaling machinery. We identified that, like chitin, flg22 signals via RESPIRATORY BURST OXIDASE HOMOLOGUE D (RBOHD) to induce plasmodesmal closure. Further, we found that PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1), PDLP5, and CALLOSE SYNTHASE 1 (CALS1) are common to microbe- and salicylic acid (SA)-triggered responses, identifying PDLPs as a candidate signaling nexus. To understand how PDLPs relay a signal to CALS1, we screened for PDLP5 interactors and found NON-RACE SPECIFIC DISEASE RESISTANCE/HIN1 HAIRPIN-INDUCED-LIKE protein 3 (NHL3), which is also required for chitin-, flg22- and SA-triggered plasmodesmal responses and PDLP-mediated activation of callose synthesis. We conclude that a PDLP-NHL3 complex acts as an integrating node of plasmodesmal signaling cascades, transmitting multiple immune signals to activate CALS1 and plasmodesmata closure.
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Affiliation(s)
- Estee E. Tee
- Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Matthew G. Johnston
- Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Diana Papp
- Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Christine Faulkner
- Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
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14
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Jeon H, Segonzac C. Manipulation of the Host Endomembrane System by Bacterial Effectors. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:208-217. [PMID: 36645655 DOI: 10.1094/mpmi-09-22-0190-fi] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The endomembrane system, extending from the nuclear envelope to the plasma membrane, is critical to the plant response to pathogen infection. Synthesis and transport of immunity-related proteins and antimicrobial compounds to and from the plasma membrane are supported by conventional and unconventional processes of secretion and internalization of vesicles, guided by the cytoskeleton networks. Although plant bacterial pathogens reside mostly in the apoplast, major structural and functional modifications of the endomembrane system in the host cell occur during bacterial infection. Here, we review the dynamics of these cellular compartments, briefly, for their essential contributions to the plant defense responses and, in parallel, for their emerging roles in bacterial pathogenicity. We further focus on Pseudomonas syringae, Xanthomonas spp., and Ralstonia solanacearum type III secreted effectors that one or both localize to and associate with components of the host endomembrane system or the cytoskeleton network to highlight the diversity of virulence strategies deployed by bacterial pathogens beyond the inhibition of the secretory pathway. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Hyelim Jeon
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Republic of Korea
| | - Cécile Segonzac
- Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea
- Plant Immunity Research Center, Seoul National University, Seoul 08826, Republic of Korea
- Plant Genomics and Breeding Institute, Seoul National University, Seoul, 08826, Republic of Korea
- Agricultural and Life Science Research Institute, Seoul National University, Seoul, 08826, Republic of Korea
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15
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Madina MH, Santhanam P, Asselin Y, Jaswal R, Bélanger RR. Progress and Challenges in Elucidating the Functional Role of Effectors in the Soybean- Phytophthora sojae Interaction. J Fungi (Basel) 2022; 9:12. [PMID: 36675833 PMCID: PMC9866111 DOI: 10.3390/jof9010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Phytophthora sojae, the agent responsible for stem and root rot, is one of the most damaging plant pathogens of soybean. To establish a compatible-interaction, P. sojae secretes a wide array of effector proteins into the host cell. These effectors have been shown to act either in the apoplastic area or the cytoplasm of the cell to manipulate the host cellular processes in favor of the development of the pathogen. Deciphering effector-plant interactions is important for understanding the role of P. sojae effectors in disease progression and developing approaches to prevent infection. Here, we review the subcellular localization, the host proteins, and the processes associated with P. sojae effectors. We also discuss the emerging topic of effectors in the context of effector-resistance genes interaction, as well as model systems and recent developments in resources and techniques that may provide a better understanding of the soybean-P. sojae interaction.
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16
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Yamazaki A, Battenberg K, Shimoda Y, Hayashi M. NDR1/HIN1-Like Protein 13 Interacts with Symbiotic Receptor Kinases and Regulates Nodulation in Lotus japonicus. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2022; 35:845-856. [PMID: 36107197 DOI: 10.1094/mpmi-11-21-0263-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lysin-motif receptor-like kinases (LysM-RLKs) are involved in the recognition of microbe-associated molecular patterns to initiate pattern-triggered immunity (PTI). LysM-RLKs are also required for recognition of microbe-derived symbiotic signal molecules upon establishing mutualistic interactions between plants and microsymbionts. A LysM-RLK CHITIN ELICITOR RECEPTOR KINASE1 (CERK1) plays central roles both in chitin-mediated PTI and in arbuscular mycorrhizal symbiosis, suggesting the overlap between immunity and symbiosis, at least in the signal perception and the activation of downstream signal cascades. In this study, we screened for the interacting proteins of Nod factor Receptor1 (NFR1), a CERK1 homolog in the model legume Lotus japonicus, and obtained a protein orthologous to NONRACE-SPECIFIC DISEASE RESISTANCE1/HARPIN-INDUCED1-LIKE13 (NHL13), a protein involved in the activation of innate immunity in Arabidopsis thaliana, which we named LjNHL13a. LjNHL13a interacted with NFR1 and with the symbiosis receptor kinase SymRK. LjNHL13a also displayed positive effects in nodulation. Our results suggest that NHL13 plays a role both in plant immunity and symbiosis, possibly where they overlap. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Akihiro Yamazaki
- Center for Sustainable Resource Science, RIKEN 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Kai Battenberg
- Center for Sustainable Resource Science, RIKEN 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
| | - Yoshikazu Shimoda
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan
| | - Makoto Hayashi
- Center for Sustainable Resource Science, RIKEN 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa 230-0045, Japan
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization 3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan
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17
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Bundalovic-Torma C, Lonjon F, Desveaux D, Guttman DS. Diversity, Evolution, and Function of Pseudomonas syringae Effectoromes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2022; 60:211-236. [PMID: 35537470 DOI: 10.1146/annurev-phyto-021621-121935] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Pseudomonas syringae is an evolutionarily diverse bacterial species complex and a preeminent model for the study of plant-pathogen interactions due in part to its remarkably broad host range. A critical feature of P. syringae virulence is the employment of suites of type III secreted effector (T3SE) proteins, which vary widely in composition and function. These effectors act on a variety of plant intracellular targets to promote pathogenesis but can also be avirulence factors when detected by host immune complexes. In this review, we survey the phylogenetic diversity (PD) of the P. syringae effectorome, comprising 70 distinct T3SE families identified to date, and highlight how avoidance of host immune detection has shaped effectorome diversity through functional redundancy, diversification, and horizontal transfer. We present emerging avenues for research and novel insights that can be gained via future investigations of plant-pathogen interactions through the fusion of large-scale interaction screens and phylogenomic approaches.
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Affiliation(s)
| | - Fabien Lonjon
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - David S Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada; ,
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
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18
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Hu Y, Ding Y, Cai B, Qin X, Wu J, Yuan M, Wan S, Zhao Y, Xin XF. Bacterial effectors manipulate plant abscisic acid signaling for creation of an aqueous apoplast. Cell Host Microbe 2022; 30:518-529.e6. [PMID: 35247331 DOI: 10.1016/j.chom.2022.02.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/05/2021] [Accepted: 02/02/2022] [Indexed: 01/23/2023]
Abstract
Phytopathogens like Pseudomonas syringae induce "water soaking" in the apoplastic space of plant leaf tissue as a key virulence mechanism. Water soaking is commonly observed in diverse pathosystems, yet the underlying physiological basis remains largely elusive. Here, we show that one of the strong P. syringae water-soaking inducers, AvrE, alters the regulation of abscisic acid (ABA) to induce ABA signaling, stomatal closure, and, thus, water soaking. AvrE binds and inhibits the function of Arabidopsis type one protein phosphatases (TOPPs), which negatively regulate ABA by suppressing SnRK2s, a key node of the ABA signaling pathway. The topp12537 quintuple mutants display significantly enhanced water soaking after P. syringae inoculation, whereas the loss of the ABA pathway dampens P. syringae-induced water soaking and disease. Our study uncovers the hijacking of ABA signaling and stomatal closure by P. syringae effectors as key mechanisms of disease susceptibility.
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Affiliation(s)
- Yezhou Hu
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yanxia Ding
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Boying Cai
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaohui Qin
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jingni Wu
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Minhang Yuan
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Shiwei Wan
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Yang Zhao
- Shanghai Center for Plant Stress Biology and CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Xiu-Fang Xin
- National key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China; Chinese Academy of Sciences (CAS) and John Innes Centre, Centre of Excellence for Plant and Microbial Sciences, Shanghai 200032, China.
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19
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Roussin-Léveillée C, Lajeunesse G, St-Amand M, Veerapen VP, Silva-Martins G, Nomura K, Brassard S, Bolaji A, He SY, Moffett P. Evolutionarily conserved bacterial effectors hijack abscisic acid signaling to induce an aqueous environment in the apoplast. Cell Host Microbe 2022; 30:489-501.e4. [PMID: 35247330 PMCID: PMC9012689 DOI: 10.1016/j.chom.2022.02.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/04/2021] [Accepted: 02/08/2022] [Indexed: 11/26/2022]
Abstract
High atmospheric humidity levels profoundly impact host-pathogen interactions in plants by enabling the establishment of an aqueous living space that benefits pathogens. The effectors HopM1 and AvrE1 of the bacterial pathogen Pseudomonas syringae have been shown to induce an aqueous apoplast under such conditions. However, the mechanisms by which this happens remain unknown. Here, we show that HopM1 and AvrE1 work redundantly to establish an aqueous living space by inducing a major reprogramming of the Arabidopsis thaliana transcriptome landscape. These effectors induce a strong abscisic acid (ABA) signature, which promotes stomatal closure, resulting in reduced leaf transpiration and water-soaking lesions. Furthermore, these effectors preferentially increase ABA accumulation in guard cells, which control stomatal aperture. Notably, a guard-cell-specific ABA transporter, ABCG40, is necessary for HopM1 induction of water-soaking lesions. This study provides molecular insights into a chain of events of stomatal manipulation that create an ideal microenvironment to facilitate infection.
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Affiliation(s)
| | - Gaële Lajeunesse
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Méliane St-Amand
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | | | | | - Kinya Nomura
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI, USA; Department of Biology, Duke University, Durham, NC, USA; Howard Hughes Medical Institute, Durham, NC, USA
| | - Sandrine Brassard
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Ayooluwa Bolaji
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Sheng Yang He
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI, USA; Department of Biology, Duke University, Durham, NC, USA; Howard Hughes Medical Institute, Durham, NC, USA
| | - Peter Moffett
- Centre SÈVE, Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
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20
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Huong DDT, Rajalingam N, Lee YH. Characterization of Virulence Function of Pseudomonas cichorii Avirulence Protein E1 (AvrE1) during Host Plant Infection. THE PLANT PATHOLOGY JOURNAL 2021; 37:494-501. [PMID: 34847636 PMCID: PMC8632607 DOI: 10.5423/ppj.nt.07.2021.0108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/17/2021] [Accepted: 08/29/2021] [Indexed: 06/13/2023]
Abstract
Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from Pseudomonas syringae pv. tomato DC3000 (PstDC3000). Overall, our results indicate that avrE1 contributes to cell death during early infection, which consequently increases disease development in host plants. The roles of PcJBC1 AvrE1 in host cells remain to be elucidated.
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Affiliation(s)
| | | | - Yong Hoon Lee
- Division of Biotechnology, Jeonbuk National University, Iksan 54596, Korea
- Advanced Institute of Environment and Bioscience, Plant Medical Research Center, and Institute of Bio-industry, Jeonbuk National University, Iksan 54596, Korea
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21
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Du JX, Li Y, Ur-Rehman S, Mukhtar I, Yin Z, Dong H, Wang H, Zhang X, Gao Z, Zhao X, Xin X, Ding X. Synergistically promoting plant health by harnessing synthetic microbial communities and prebiotics. iScience 2021; 24:102918. [PMID: 34430808 PMCID: PMC8365361 DOI: 10.1016/j.isci.2021.102918] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Soil-borne diseases cause serious economic losses in agriculture. Managing diseases with microbial preparations is an excellent approach to soil-borne disease prevention. However, microbial preparations often exhibit unstable effects, limiting their large-scale application. This review introduces and summarizes disease-suppressive soils, the relationship between carbon sources and the microbial community, and the application of human microbial preparation concepts to plant microbial preparations. We also propose an innovative synthetic microbial community assembly strategy with synergistic prebiotics to promote healthy plant growth and resistance to disease. In this review, a new approach is proposed to improve traditional microbial preparations; provide a better understanding of the relationships among carbon sources, beneficial microorganisms, and plants; and lay a theoretical foundation for developing new microbial preparations.
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Affiliation(s)
- Jianfeng X. Du
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
| | - Yang Li
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
| | - Saif- Ur-Rehman
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
| | - Irum Mukhtar
- Institute of Oceanography, Minjiang University, Fuzhou 350108, China
| | - Ziyi Yin
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
| | - Hansong Dong
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
| | - Hongfeng Wang
- Shandong Pengbo Biotechnology Co., LTD, Taian 271018, China
| | - Xiaoying Zhang
- Shandong Pengbo Biotechnology Co., LTD, Taian 271018, China
| | - Zheng Gao
- College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, P.R. China
| | - Xiangyu Zhao
- College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong 271018, P.R. China
| | - Xiufang Xin
- Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Science and Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences (CAS) and CAS John Innes Centre of Excellence for Plant and Microbial Sciences, Shanghai, China
| | - Xinhua Ding
- State Key Laboratory of Crop Biology, Shandong Provincial Key Laboratory for Biology of Vegetable Diseases and Insect Pests, College of Plant Protection, Shandong Agricultural University, Taian, Shandong 271018, P. R. China
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22
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Yuan Y, Qin L, Su H, Yang S, Wei X, Wang Z, Zhao Y, Li L, Liu H, Tian B, Zhang X. Transcriptome and Coexpression Network Analyses Reveal Hub Genes in Chinese Cabbage ( Brassica rapa L. ssp. pekinensis) During Different Stages of Plasmodiophora brassicae Infection. FRONTIERS IN PLANT SCIENCE 2021; 12:650252. [PMID: 34447397 PMCID: PMC8383047 DOI: 10.3389/fpls.2021.650252] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 07/20/2021] [Indexed: 05/15/2023]
Abstract
Clubroot, caused by the soil-borne protist Plasmodiophora brassicae, is one of the most destructive diseases of Chinese cabbage worldwide. However, the clubroot resistance mechanisms remain unclear. In this study, in both clubroot-resistant (DH40R) and clubroot-susceptible (DH199S) Chinese cabbage lines, the primary (root hair infection) and secondary (cortical infection) infection stages started 2 and 5 days after inoculation (dai), respectively. With the extension of the infection time, cortical infection was blocked and complete P. brassica resistance was observed in DH40R, while disease scales of 1, 2, and 3 were observed at 8, 13, and 22 dai in DH199S. Transcriptome analysis at 0, 2, 5, 8, 13, and 22 dai identified 5,750 relative DEGs (rDEGs) between DH40R and DH199S. The results indicated that genes associated with auxin, PR, disease resistance proteins, oxidative stress, and WRKY and MYB transcription factors were involved in clubroot resistance regulation. In addition, weighted gene coexpression network analysis (WGCNA) identified three of the modules whose functions were highly associated with clubroot-resistant, including ten hub genes related to clubroot resistance (ARF2, EDR1, LOX4, NHL3, NHL13, NAC29, two AOP1, EARLI 1, and POD56). These results provide valuable information for better understanding the molecular regulatory mechanism of Chinese cabbage clubroot resistance.
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Affiliation(s)
- Yuxiang Yuan
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Liuyue Qin
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Henan Su
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Shuangjuan Yang
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Xiaochun Wei
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Zhiyong Wang
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Yanyan Zhao
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Lin Li
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
| | - Honglei Liu
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Baoming Tian
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
| | - Xiaowei Zhang
- Institute of Horticulture, Henan Academy of Agricultural Sciences, Graduate T&R Base of Zhengzhou University, Zhengzhou, China
- School of Life Sciences, Zhengzhou University, Zhengzhou, China
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23
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Yuan X, Hulin MT, Sundin GW. Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review. JOURNAL OF PLANT PATHOLOGY 2021; 103:25-39. [PMID: 0 DOI: 10.1007/s42161-020-00623-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/23/2020] [Indexed: 05/20/2023]
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24
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Foix L, Nadal A, Zagorščak M, Ramšak Ž, Esteve-Codina A, Gruden K, Pla M. Prunus persica plant endogenous peptides PpPep1 and PpPep2 cause PTI-like transcriptome reprogramming in peach and enhance resistance to Xanthomonas arboricola pv. pruni. BMC Genomics 2021; 22:360. [PMID: 34006221 PMCID: PMC8132438 DOI: 10.1186/s12864-021-07571-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/23/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rosaceae species are economically highly relevant crops. Their cultivation systems are constrained by phytopathogens causing severe losses. Plants respond to invading pathogens through signaling mechanisms, a component of which are of them being plant elicitor peptides (Peps). Exogenous application of Peps activates defense mechanisms and reduces the symptoms of pathogen infection in various pathosystems. We have previously identified the Rosaceae Peps and showed, in an ex vivo system, that their topical application efficiently enhanced resistance to the bacterial pathogen Xanthomonas arboricola pv. pruni (Xap). RESULTS Here we demonstrate the effectiveness of Prunus persica peptides PpPep1 and PpPep2 in protecting peach plants in vivo at nanomolar doses, with 40% reduction of the symptoms following Xap massive infection. We used deep sequencing to characterize the transcriptomic response of peach plants to preventive treatment with PpPep1 and PpPep2. The two peptides induced highly similar massive transcriptomic reprogramming in the plant. One hour, 1 day and 2 days after peptide application there were changes in expression in up to 8% of peach genes. We visualized the transcriptomics dynamics in a background knowledge network and detected the minor variations between plant responses to PpPep1 and PpPep2, which might explain their slightly different protective effects. By designing a P. persica Pep background knowledge network, comparison of our data and previously published immune response datasets was possible. CONCLUSIONS Topical application of P. persica Peps mimics the PTI natural response and protects plants against massive Xap infection. This makes them good candidates for deployment of natural, targeted and environmental-friendly strategies to enhance resistance in Prunus species and prevent important biotic diseases.
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Affiliation(s)
- Laura Foix
- Institute for Agricultural and Food Technology, Universitat de Girona, Campus Montilivi (EPS-1), 17003, Girona, Spain
| | - Anna Nadal
- Institute for Agricultural and Food Technology, Universitat de Girona, Campus Montilivi (EPS-1), 17003, Girona, Spain
| | - Maja Zagorščak
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000, Ljubljana, Slovenia
| | - Živa Ramšak
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000, Ljubljana, Slovenia
| | - Anna Esteve-Codina
- CNAG-CRG, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 08028, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Kristina Gruden
- Department of Biotechnology and Systems Biology, National Institute of Biology, Večna pot 111, 1000, Ljubljana, Slovenia
| | - Maria Pla
- Institute for Agricultural and Food Technology, Universitat de Girona, Campus Montilivi (EPS-1), 17003, Girona, Spain.
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25
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Schreiber KJ, Chau-Ly IJ, Lewis JD. What the Wild Things Do: Mechanisms of Plant Host Manipulation by Bacterial Type III-Secreted Effector Proteins. Microorganisms 2021; 9:1029. [PMID: 34064647 PMCID: PMC8150971 DOI: 10.3390/microorganisms9051029] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/03/2021] [Accepted: 05/04/2021] [Indexed: 01/05/2023] Open
Abstract
Phytopathogenic bacteria possess an arsenal of effector proteins that enable them to subvert host recognition and manipulate the host to promote pathogen fitness. The type III secretion system (T3SS) delivers type III-secreted effector proteins (T3SEs) from bacterial pathogens such as Pseudomonas syringae, Ralstonia solanacearum, and various Xanthomonas species. These T3SEs interact with and modify a range of intracellular host targets to alter their activity and thereby attenuate host immune signaling. Pathogens have evolved T3SEs with diverse biochemical activities, which can be difficult to predict in the absence of structural data. Interestingly, several T3SEs are activated following injection into the host cell. Here, we review T3SEs with documented enzymatic activities, as well as T3SEs that facilitate virulence-promoting processes either indirectly or through non-enzymatic mechanisms. We discuss the mechanisms by which T3SEs are activated in the cell, as well as how T3SEs modify host targets to promote virulence or trigger immunity. These mechanisms may suggest common enzymatic activities and convergent targets that could be manipulated to protect crop plants from infection.
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Affiliation(s)
- Karl J. Schreiber
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
| | - Ilea J. Chau-Ly
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
| | - Jennifer D. Lewis
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94710, USA; (K.J.S.); (I.J.C.-L.)
- Plant Gene Expression Center, United States Department of Agriculture, University of California, Berkeley, CA 94710, USA
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Dunker F, Oberkofler L, Lederer B, Trutzenberg A, Weiberg A. An Arabidopsis downy mildew non-RxLR effector suppresses induced plant cell death to promote biotroph infection. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:718-732. [PMID: 33063828 PMCID: PMC7853606 DOI: 10.1093/jxb/eraa472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 10/13/2020] [Indexed: 05/11/2023]
Abstract
Our understanding of obligate biotrophic pathogens is limited by lack of knowledge concerning the molecular function of virulence factors. We established Arabidopsis host-induced gene silencing (HIGS) to explore gene functions of Hyaloperonospora arabidopsidis, including CYSTEINE-RICH PROTEIN (HaCR)1, a potential secreted effector gene of this obligate biotrophic pathogen. HaCR1 HIGS resulted in H. arabidopsidis-induced local plant cell death and reduced pathogen reproduction. We functionally characterized HaCR1 by ectopic expression in Nicotiana benthamiana. HaCR1 was capable of inhibiting effector-triggered plant cell death. Consistent with this, HaCR1 expression in N. benthamiana led to stronger disease symptoms caused by the hemibiotrophic oomycete pathogen Phytophthora capsici, but reduced disease symptoms caused by the necrotrophic fungal pathogen Botrytis cinerea. Expressing HaCR1 in transgenic Arabidopsis confirmed higher susceptibility to H. arabidopsidis and to the bacterial hemibiotrophic pathogen Pseudomonas syringae. Increased H. arabidopsidis infection was in accordance with reduced PATHOGENESIS RELATED (PR)1 induction. Expression of full-length HaCR1 was required for its function, which was lost if the signal peptide was deleted, suggesting its site of action in the plant apoplast. This study provides phytopathological and molecular evidence for the importance of this widespread, but largely unexplored class of non-RxLR effectors in biotrophic oomycetes.
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Affiliation(s)
- Florian Dunker
- Faculty of Biology, Genetics, Biocenter Martinsried, LMU Munich, Planegg-Martinsried, Germany
| | - Lorenz Oberkofler
- Faculty of Biology, Genetics, Biocenter Martinsried, LMU Munich, Planegg-Martinsried, Germany
| | - Bernhard Lederer
- Faculty of Biology, Genetics, Biocenter Martinsried, LMU Munich, Planegg-Martinsried, Germany
| | - Adriana Trutzenberg
- Faculty of Biology, Genetics, Biocenter Martinsried, LMU Munich, Planegg-Martinsried, Germany
| | - Arne Weiberg
- Faculty of Biology, Genetics, Biocenter Martinsried, LMU Munich, Planegg-Martinsried, Germany
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Li Z, Variz H, Chen Y, Liu SL, Aung K. Plasmodesmata-Dependent Intercellular Movement of Bacterial Effectors. FRONTIERS IN PLANT SCIENCE 2021. [PMID: 33959138 DOI: 10.1101/2020.12.10.420240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Pathogenic microorganisms deliver protein effectors into host cells to suppress host immune responses. Recent findings reveal that phytopathogens manipulate the function of plant cell-to-cell communication channels known as plasmodesmata (PD) to promote diseases. Several bacterial and filamentous pathogen effectors have been shown to regulate PD in their host cells. A few effectors of filamentous pathogens have been reported to move from the infected cells to neighboring plant cells through PD; however, it is unclear whether bacterial effectors can traffic through PD in plants. In this study, we determined the intercellular movement of Pseudomonas syringae pv. tomato (Pst) DC3000 effectors between adjoining plant cells in Nicotiana benthamiana. We observed that at least 16 Pst DC3000 effectors have the capacity to move from transformed cells to the surrounding plant cells. The movement of the effectors is largely dependent on their molecular weights. The expression of PD regulators, Arabidopsis PD-located protein PDLP5 and PDLP7, leads to PD closure and inhibits the PD-dependent movement of a bacterial effector in N. benthamiana. Similarly, a 22-amino acid peptide of bacterial flagellin (flg22) treatment induces PD closure and suppresses the movement of a bacterial effector in N. benthamiana. Among the mobile effectors, HopAF1 and HopA1 are localized to the plasma membrane (PM) in plant cells. Interestingly, the PM association of HopAF1 does not negatively affect the PD-dependent movement. Together, our findings demonstrate that bacterial effectors are able to move intercellularly through PD in plants.
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Affiliation(s)
- Zhongpeng Li
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, United States
| | - Haris Variz
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, United States
| | - Yani Chen
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, United States
| | - Su-Ling Liu
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, United States
| | - Kyaw Aung
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, United States
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28
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Li Z, Variz H, Chen Y, Liu SL, Aung K. Plasmodesmata-Dependent Intercellular Movement of Bacterial Effectors. FRONTIERS IN PLANT SCIENCE 2021; 12:640277. [PMID: 33959138 PMCID: PMC8095247 DOI: 10.3389/fpls.2021.640277] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 03/01/2021] [Indexed: 05/03/2023]
Abstract
Pathogenic microorganisms deliver protein effectors into host cells to suppress host immune responses. Recent findings reveal that phytopathogens manipulate the function of plant cell-to-cell communication channels known as plasmodesmata (PD) to promote diseases. Several bacterial and filamentous pathogen effectors have been shown to regulate PD in their host cells. A few effectors of filamentous pathogens have been reported to move from the infected cells to neighboring plant cells through PD; however, it is unclear whether bacterial effectors can traffic through PD in plants. In this study, we determined the intercellular movement of Pseudomonas syringae pv. tomato (Pst) DC3000 effectors between adjoining plant cells in Nicotiana benthamiana. We observed that at least 16 Pst DC3000 effectors have the capacity to move from transformed cells to the surrounding plant cells. The movement of the effectors is largely dependent on their molecular weights. The expression of PD regulators, Arabidopsis PD-located protein PDLP5 and PDLP7, leads to PD closure and inhibits the PD-dependent movement of a bacterial effector in N. benthamiana. Similarly, a 22-amino acid peptide of bacterial flagellin (flg22) treatment induces PD closure and suppresses the movement of a bacterial effector in N. benthamiana. Among the mobile effectors, HopAF1 and HopA1 are localized to the plasma membrane (PM) in plant cells. Interestingly, the PM association of HopAF1 does not negatively affect the PD-dependent movement. Together, our findings demonstrate that bacterial effectors are able to move intercellularly through PD in plants.
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29
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Yuan X, Yu M, Yang CH. Innovation and Application of the Type III Secretion System Inhibitors in Plant Pathogenic Bacteria. Microorganisms 2020; 8:microorganisms8121956. [PMID: 33317075 PMCID: PMC7764658 DOI: 10.3390/microorganisms8121956] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/05/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
Many Gram-negative pathogenic bacteria rely on a functional type III secretion system (T3SS), which injects multiple effector proteins into eukaryotic host cells, for their pathogenicity. Genetic studies conducted in different host-microbe pathosystems often revealed a sophisticated regulatory mechanism of their T3SSs, suggesting that the expression of T3SS is tightly controlled and constantly monitored by bacteria in response to the ever-changing host environment. Therefore, it is critical to understand the regulation of T3SS in pathogenic bacteria for successful disease management. This review focuses on a model plant pathogen, Dickeyadadantii, and summarizes the current knowledge of its T3SS regulation. We highlight the roles of several T3SS regulators that were recently discovered, including the transcriptional regulators: FlhDC, RpoS, and SlyA; the post-transcriptional regulators: PNPase, Hfq with its dependent sRNA ArcZ, and the RsmA/B system; and the bacterial second messenger cyclic-di-GMP (c-di-GMP). Homologs of these regulatory components have also been characterized in almost all major bacterial plant pathogens like Erwiniaamylovora, Pseudomonassyringae, Pectobacterium spp., Xanthomonas spp., and Ralstonia spp. The second half of this review shifts focus to an in-depth discussion of the innovation and development of T3SS inhibitors, small molecules that inhibit T3SSs, in the field of plant pathology. This includes T3SS inhibitors that are derived from plant phenolic compounds, plant coumarins, and salicylidene acylhydrazides. We also discuss their modes of action in bacteria and application for controlling plant diseases.
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Affiliation(s)
- Xiaochen Yuan
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA;
| | - Manda Yu
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
- Correspondence: (M.Y.); (C.-H.Y.)
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30
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Bhandari DD, Brandizzi F. Plant endomembranes and cytoskeleton: moving targets in immunity. CURRENT OPINION IN PLANT BIOLOGY 2020; 58:8-16. [PMID: 33099211 DOI: 10.1016/j.pbi.2020.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 08/28/2020] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
Pathogens attack plant cells to divert resources toward pathogen proliferation. To resist pathogens, plant cells rely on multilayered signaling pathways that hinge upon the secretory pathway for the synthesis and trafficking of pathogen sensors and defense molecules. In recent years, significant strides have been made in the understanding of the functional relationship between pathogen response and membrane traffic. Here we discuss how the plant cytoskeleton and endomembranes are targeted by pathogen effectors and highlight an emerging role of membrane contact sites in biotic stress responses.
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Affiliation(s)
- Deepak D Bhandari
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
| | - Federica Brandizzi
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA; Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, USA.
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31
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The Role of Chloroplast Gene Expression in Plant Responses to Environmental Stress. Int J Mol Sci 2020; 21:ijms21176082. [PMID: 32846932 PMCID: PMC7503970 DOI: 10.3390/ijms21176082] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/16/2022] Open
Abstract
Chloroplasts are plant organelles that carry out photosynthesis, produce various metabolites, and sense changes in the external environment. Given their endosymbiotic origin, chloroplasts have retained independent genomes and gene-expression machinery. Most genes from the prokaryotic ancestors of chloroplasts were transferred into the nucleus over the course of evolution. However, the importance of chloroplast gene expression in environmental stress responses have recently become more apparent. Here, we discuss the emerging roles of the distinct chloroplast gene expression processes in plant responses to environmental stresses. For example, the transcription and translation of psbA play an important role in high-light stress responses. A better understanding of the connection between chloroplast gene expression and environmental stress responses is crucial for breeding stress-tolerant crops better able to cope with the rapidly changing environment.
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Islam MT, Gan HM, Ziemann M, Hussain HI, Arioli T, Cahill D. Phaeophyceaean (Brown Algal) Extracts Activate Plant Defense Systems in Arabidopsis thaliana Challenged With Phytophthora cinnamomi. FRONTIERS IN PLANT SCIENCE 2020; 11:852. [PMID: 32765538 PMCID: PMC7381280 DOI: 10.3389/fpls.2020.00852] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/27/2020] [Indexed: 06/11/2023]
Abstract
Seaweed extracts are important sources of plant biostimulants that boost agricultural productivity to meet current world demand. The ability of seaweed extracts based on either of the Phaeophyceaean species Ascophyllum nodosum or Durvillaea potatorum to enhance plant growth or suppress plant disease have recently been shown. However, very limited information is available on the mechanisms of suppression of plant disease by such extracts. In addition, there is no information on the ability of a combination of extracts from A. nodosum and D. potatorum to suppress a plant pathogen or to induce plant defense. The present study has explored the transcriptome, using RNA-seq, of Arabidopsis thaliana following treatment with extracts from the two species, or a mixture of both, prior to inoculation with the root pathogen Phytophthora cinnamomi. Following inoculation, five time points (0-24 h post-inoculation) that represented early stages in the interaction of the pathogen with its host were assessed for each treatment and compared with their respective water controls. Wide scale transcriptome reprogramming occurred predominantly related to phytohormone biosynthesis and signaling, changes in metabolic processes and cell wall biosynthesis, there was a broad induction of proteolysis pathways, a respiratory burst and numerous defense-related responses were induced. The induction by each seaweed extract of defense-related genes coincident with the time of inoculation showed that the plants were primed for defense prior to infection. Each seaweed extract acted differently in inducing plant defense-related genes. However, major systemic acquired resistance (SAR)-related genes as well as salicylic acid-regulated marker genes (PR1, PR5, and NPR1) and auxin associated genes were found to be commonly up-regulated compared with the controls following treatment with each seaweed extract. Moreover, each seaweed extract suppressed P. cinnamomi growth within the roots of inoculated A. thaliana by the early induction of defense pathways and likely through ROS-based signaling pathways that were linked to production of ROS. Collectively, the RNA-seq transcriptome analysis revealed the induction by seaweed extracts of suites of genes that are associated with direct or indirect plant defense in addition to responses that require cellular energy to maintain plant growth during biotic stress.
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Affiliation(s)
- Md Tohidul Islam
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds Campus, Geelong, VIC, Australia
- Department of Plant Pathology, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh
| | - Han Ming Gan
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds Campus, Geelong, VIC, Australia
| | - Mark Ziemann
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds Campus, Geelong, VIC, Australia
| | | | - Tony Arioli
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds Campus, Geelong, VIC, Australia
- Seasol International R&D Department, Bayswater, VIC, Australia
| | - David Cahill
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds Campus, Geelong, VIC, Australia
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33
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Huang D, Tian W, Feng J, Zhu S. Interaction between nitric oxide and storage temperature on sphingolipid metabolism of postharvest peach fruit. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 151:60-68. [PMID: 32200191 DOI: 10.1016/j.plaphy.2020.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/23/2020] [Accepted: 03/09/2020] [Indexed: 06/10/2023]
Abstract
Both nitric oxide (NO) and cold storage have positive effects on the maintenance of fruit quality during storage. However, the roles of NO and storage temperatures in regulating the responses of sphingolipids metabolism to chilling injury of peach fruit during storage remain unknown. Peaches were treated by immersion in distilled water and 15 μmol L-1 NO solution, then stored at 25 °C and 0 °C, respectively. The effects of NO-treatment and storage temperature on the activities of enzymes in sphingolipid metabolism and the contents of sphingolipids in peach fruits were studied. NO maintained higher activities of acid phosphatase (AP) and alkaline phosphatase (ALP) in peach fruits at 25 °C, but promoted the decrease in the activities of AP and ALP at 0 °C, suggesting the regulation by NO on AP and ALP could be modulated by temperature. Compared with the storage at 25 °C, cold storage at 0 °C decreased the activities of phospholipase A (PLA), alkaline phosphatase (ALP), 3-ketodihydrosphingosine reductase (KDSR), sphingosine kinase (SPHK), ceramide synthase (CERS), ceramide kinase (CERK), and the contents of sphingosine (SPH), ceramide (CER), sphingosine-1-phosphate (S1P), ceramide-1-phosphate (C1P), sphingomyelin (SM), and increased the activities of phospholipase C (PLC), phospholipase D (PLD), sphingomyelin synthase (SMS). NO significantly increased the contents of sphingolipid metabolites, and the activities of PLA, KDSR, SPHK, CERS, CERK, but decreased the activities of PLC, PLD, SMS of peaches. The results suggested that NO could maintain sphingolipid metabolism to relieve the response of the postharvest fruit to low temperature.
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Affiliation(s)
- Dandan Huang
- College of Chemistry and Material Science, Shandong Agricultural University, Taian, Shandong, 271018, China
| | - Wen Tian
- College of Chemistry and Material Science, Shandong Agricultural University, Taian, Shandong, 271018, China; Department of Horticulture, College of Agriculture, Shihezi University, Shihezi, Xinjiang, 832000, China
| | - Jianrong Feng
- Department of Horticulture, College of Agriculture, Shihezi University, Shihezi, Xinjiang, 832000, China.
| | - Shuhua Zhu
- College of Chemistry and Material Science, Shandong Agricultural University, Taian, Shandong, 271018, China.
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Plant Cells under Attack: Unconventional Endomembrane Trafficking during Plant Defense. PLANTS 2020; 9:plants9030389. [PMID: 32245198 PMCID: PMC7154882 DOI: 10.3390/plants9030389] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/16/2020] [Accepted: 03/19/2020] [Indexed: 12/12/2022]
Abstract
Since plants lack specialized immune cells, each cell has to defend itself independently against a plethora of different pathogens. Therefore, successful plant defense strongly relies on precise and efficient regulation of intracellular processes in every single cell. Smooth trafficking within the plant endomembrane is a prerequisite for a diverse set of immune responses. Pathogen recognition, signaling into the nucleus, cell wall enforcement, secretion of antimicrobial proteins and compounds, as well as generation of reactive oxygen species, all heavily depend on vesicle transport. In contrast, pathogens have developed a variety of different means to manipulate vesicle trafficking to prevent detection or to inhibit specific plant responses. Intriguingly, the plant endomembrane system exhibits remarkable plasticity upon pathogen attack. Unconventional trafficking pathways such as the formation of endoplasmic reticulum (ER) bodies or fusion of the vacuole with the plasma membrane are initiated and enforced as the counteraction. Here, we review the recent findings on unconventional and defense-induced trafficking pathways as the plant´s measures in response to pathogen attack. In addition, we describe the endomembrane system manipulations by different pathogens, with a focus on tethering and fusion events during vesicle trafficking.
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35
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Aung K, Kim P, Li Z, Joe A, Kvitko B, Alfano JR, He SY. Pathogenic Bacteria Target Plant Plasmodesmata to Colonize and Invade Surrounding Tissues. THE PLANT CELL 2020; 32:595-611. [PMID: 31888968 PMCID: PMC7054039 DOI: 10.1105/tpc.19.00707] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/25/2019] [Accepted: 12/18/2019] [Indexed: 05/03/2023]
Abstract
A hallmark of multicellular organisms is their ability to maintain physiological homeostasis by communicating among cells, tissues, and organs. In plants, intercellular communication is largely dependent on plasmodesmata (PD), which are membrane-lined channels connecting adjacent plant cells. Upon immune stimulation, plants close PD as part of their immune responses. Here, we show that the bacterial pathogen Pseudomonas syringae deploys an effector protein, HopO1-1, that modulates PD function. HopO1-1 is required for P. syringae to spread locally to neighboring tissues during infection. Expression of HopO1-1 in Arabidopsis (Arabidopsis thaliana) increases the distance of PD-dependent molecular flux between neighboring plant cells. Being a putative ribosyltransferase, the catalytic activity of HopO1-1 is required for regulation of PD. HopO1-1 physically interacts with and destabilizes the plant PD-located protein PDLP7 and possibly PDLP5. Both PDLPs are involved in bacterial immunity. Our findings reveal that a pathogenic bacterium utilizes an effector to manipulate PD-mediated host intercellular communication for maximizing the spread of bacterial infection.
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Affiliation(s)
- Kyaw Aung
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Panya Kim
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Zhongpeng Li
- Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011
| | - Anna Joe
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Brian Kvitko
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
| | - James R Alfano
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68588
| | - Sheng Yang He
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824
- Howard Hughes Medical Institute, Michigan State University, East Lansing, Michigan 48824
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
- Plant Resilience Institute, Michigan State University, East Lansing, Michigan 48824
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Ying X, Wan M, Hu L, Zhang J, Li H, Lv D. Identification of the Virulence Factors of Candidatus Liberibacter asiaticus via Heterologous Expression in Nicotiana benthamiana using Tobacco Mosaic Virus. Int J Mol Sci 2019; 20:E5575. [PMID: 31717281 PMCID: PMC6888081 DOI: 10.3390/ijms20225575] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 10/31/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022] Open
Abstract
Huanglongbing (HLB), also known as citrus greening, is the most destructive disease of citrus worldwide. HLB is associated with the non-culturable bacterium, Candidatus Liberibacter asiaticus (CaLas) in the United States. The virulence mechanism of CaLas is largely unknown, partly because of the lack of a mutant library. In this study, Tobacco mosaic virus (TMV) and Nicotiana benthamiana (N. benthamiana) were used for large-scale screening of the virulence factors of CaLas. Agroinfiltration of 60 putative virulence factors in N. benthamiana led to the identification of four candidates that caused severe symptoms in N. benthamiana, such as growth inhibition and cell death. CLIBASIA_05150 and CLIBASIA_04065C (C-terminal of CLIBASIA_04065) could cause cell death in the infiltrated leaves at five days post infiltration. Two low-molecular-weight candidates, CLIBASIA_00470 and CLIBASIA_04025, could inhibit plant growth. By converting start codon to stop codon or frameshifting, the four genes lost their harmful effects to N. benthamiana. It indicated that the four virulence factors functioned at the protein level rather than at the RNA level. The subcellular localization of the four candidates was determined by confocal laser scanning microscope. CLIBASIA_05150 located in the Golgi apparatus; CLIBASIA_04065 located in the mitochondrion; CLIBASIA_00470 and CLIBASIA_04025 distributed in cells as free GFP. The host proteins interacting with the four virulence factors were identified by yeast two-hybrid. The host proteins interacting with CLIBASIA_00470 and CLIBASIA_04025 were overlapping. Based on the phenotypes, the subcellular localization and the host proteins identified by yeast two-hybrid, CLIBASIA_00470 and CLIBASIA_04025, functioned redundantly. The hypothesis of CaLas virulence was proposed. CaLas affects citrus development and suppresses citrus disease resistance, comprehensively, in a complicated manner. Ubiquitin-mediated protein degradation might play a vital role in CaLas virulence. Deep characterization of the interactions between the identified virulence factors and their prey will shed light on HLB. Eventually, it will help in developing HLB-resistant citrus and save the endangered citrus industry worldwide.
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Affiliation(s)
- Xiaobao Ying
- Gulf Coast Research and Education Center, University of Florida, Wimauma, FL 33598, USA;
| | - Mengyuan Wan
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, Chongqing 400715, China
| | - Linshuang Hu
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China; (L.H.); (J.Z.)
| | - Jinghua Zhang
- Heilongjiang Academy of Agricultural Sciences, Harbin 10086, China; (L.H.); (J.Z.)
| | - Hui Li
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
| | - Dianqiu Lv
- College of Agronomy and Biotechnology, Southwest University, Beibei, Chongqing 400715, China;
- State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, Chongqing 400715, China
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37
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Brassica napus Infected with Leptosphaeria maculans. Genes (Basel) 2019; 10:genes10040296. [PMID: 30979089 PMCID: PMC6523698 DOI: 10.3390/genes10040296] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 04/10/2019] [Accepted: 04/10/2019] [Indexed: 01/07/2023] Open
Abstract
Alternative splicing (AS) is a post-transcriptional regulatory process that enhances transcriptome diversity, thereby affecting plant growth, development, and stress responses. To identify the new transcripts and changes in the isoform-level AS landscape of rapeseed (Brassica napus) infected with the fungal pathogen Leptosphaeria maculans, we compared eight RNA-seq libraries prepared from mock-inoculated and inoculated B. napus cotyledons and stems. The AS events that occurred in stems were almost the same as those in cotyledons, with intron retention representing the most common AS pattern. We identified 1892 differentially spliced genes between inoculated and uninoculated plants. We performed a weighted gene co-expression network analysis (WGCNA) to identify eight co-expression modules and their Hub genes, which are the genes most connected with other genes within each module. There are nine Hub genes, encoding nine transcription factors, which represent key regulators of each module, including members of the NAC, WRKY, TRAF, AP2/ERF-ERF, C2H2, C2C2-GATA, HMG, bHLH, and C2C2-CO-like families. Finally, 52 and 117 alternatively spliced genes in cotyledons and stems were also differentially expressed between mock-infected and infected materials, such as HMG and C2C2-Dof; which have dual regulatory mechanisms in response to L. maculans. The splicing of the candidate genes identified in this study could be exploited to improve resistance to L. maculans.
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Guo B, Wang H, Yang B, Jiang W, Jing M, Li H, Xia Y, Xu Y, Hu Q, Wang F, Yu F, Wang Y, Ye W, Dong S, Xing W, Wang Y. Phytophthora sojae Effector PsAvh240 Inhibits Host Aspartic Protease Secretion to Promote Infection. MOLECULAR PLANT 2019; 12:552-564. [PMID: 30703565 DOI: 10.1016/j.molp.2019.01.017] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 12/20/2018] [Accepted: 01/18/2019] [Indexed: 05/27/2023]
Abstract
Plants secrete defense molecules into the extracellular space (the apoplast) to combat attacking microbes. However, the mechanisms by which successful pathogens subvert plant apoplastic immunity remain poorly understood. In this study, we show that PsAvh240, a membrane-localized effector of the soybean pathogen Phytophthora sojae, promotes P. sojae infection in soybean hairy roots. We found that PsAvh240 interacts with the soybean-resistant aspartic protease GmAP1 in planta and suppresses the secretion of GmAP1 into the apoplast. By solving its crystal structure we revealed that PsAvh240 contain six α helices and two WY motifs. The first two α helices of PsAvh240 are responsible for its plasma membrane-localization and are required for PsAvh240's interaction with GmAP1. The second WY motifs of two PsAvh240 molecules form a handshake arrangement resulting in a handshake-like dimer. This dimerization is required for the effector's repression of GmAP1 secretion. Taken together, these data reveal that PsAvh240 localizes at the plasma membrane to interfere with GmAP1 secretion, which represents an effective mechanism by which effector proteins suppress plant apoplastic immunity.
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Affiliation(s)
- Baodian Guo
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Haonan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Bo Yang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Wenjing Jiang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Maofeng Jing
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Haiyang Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Yeqiang Xia
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Yuanpeng Xu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Qinli Hu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201204, China
| | - Fangfang Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201204, China
| | - Feng Yu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, No. 239 Zhangheng Road, Shanghai 201204, China
| | - Yan Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Suomeng Dong
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China
| | - Weiman Xing
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201204, China.
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing 210095, China.
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Lawaju BR, Lawrence KS, Lawrence GW, Klink VP. Harpin-inducible defense signaling components impair infection by the ascomycete Macrophomina phaseolina. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2018; 129:331-348. [PMID: 29936240 DOI: 10.1016/j.plaphy.2018.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 05/23/2023]
Abstract
Soybean (Glycine max) infection by the charcoal rot (CR) ascomycete Macrophomina phaseolina is enhanced by the soybean cyst nematode (SCN) Heterodera glycines. We hypothesized that G. max genetic lines impairing infection by M. phaseolina would also limit H. glycines parasitism, leading to resistance. As a part of this M. phaseolina resistance process, the genetic line would express defense genes already proven to impair nematode parasitism. Using G. max[DT97-4290/PI 642055], exhibiting partial resistance to M. phaseolina, experiments show the genetic line also impairs H. glycines parasitism. Furthermore, comparative studies show G. max[DT97-4290/PI 642055] exhibits induced expression of the effector triggered immunity (ETI) gene NON-RACE SPECIFIC DISEASE RESISTANCE 1/HARPIN INDUCED1 (NDR1/HIN1) that functions in defense to H. glycines as compared to the H. glycines and M. phaseolina susceptible line G. max[Williams 82/PI 518671]. Other defense genes that are induced in G. max[DT97-4290/PI 642055] include the pathogen associated molecular pattern (PAMP) triggered immunity (PTI) genes ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1), NONEXPRESSOR OF PR1 (NPR1) and TGA2. These observations link G. max defense processes that impede H. glycines parasitism to also potentially function toward impairing M. phaseolina pathogenicity. Testing this hypothesis, G. max[Williams 82/PI 518671] genetically engineered to experimentally induce GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 expression leads to impaired M. phaseolina pathogenicity. In contrast, G. max[DT97-4290/PI 642055] engineered to experimentally suppress the expression of GmNDR1-1, EDS1-2, NPR1-2 and TGA2-1 by RNA interference (RNAi) enhances M. phaseolina pathogenicity. The results show components of PTI and ETI impair both nematode and M. phaseolina pathogenicity.
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Affiliation(s)
- Bisho R Lawaju
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, College of Agriculture and Life Sciences, Mississippi State, MS, 39762, USA.
| | - Kathy S Lawrence
- Department of Entomology and Plant Pathology, Auburn University, 209 Life Science Building, Auburn, AL, 36849, USA.
| | - Gary W Lawrence
- Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, College of Agriculture and Life Sciences, Mississippi State University, Mississippi State, MS, 39762, USA.
| | - Vincent P Klink
- Department of Biological Sciences, College of Arts and Sciences, Mississippi State University, Mississippi State, MS, 39762, USA.
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El Kasmi F, Horvath D, Lahaye T. Microbial effectors and the role of water and sugar in the infection battle ground. CURRENT OPINION IN PLANT BIOLOGY 2018; 44:98-107. [PMID: 29597139 DOI: 10.1016/j.pbi.2018.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 06/08/2023]
Abstract
Phytopathogenic microbes multiply in the apoplast-a plant's intercellular spaces-of infected plants, and hence their success relies on the conditions in this habitat. Despite being extracellular parasites, most microbes translocate effectors into host cells that promote disease by acting inside cells. Initial studies suggested that effectors act predominantly as suppressors of plant immunity. These pioneering studies were trend-setting, causing a strong bias in the functional investigation of effectors. Yet, recent studies on bacterial model pathogens have identified effectors that promote disease by causing either increased sugar or water levels in the apoplast. These studies are likely to initiate a new era of effector research that will clarify the disease-promoting rather than defense-suppressing function of effectors, a molecular rather than genetic distinction.
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Affiliation(s)
- Farid El Kasmi
- ZMBP-Plant Physiology, University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany
| | - Diana Horvath
- 2Blades Foundation, Suite 1901, 1630 Chicago Avenue, Evanston, IL 60201, USA
| | - Thomas Lahaye
- ZMBP-General Genetics, University of Tübingen, Auf der Morgenstelle 32, D-72076 Tübingen, Germany.
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Wei H, Collmer A. Defining essential processes in plant pathogenesis with Pseudomonas syringae pv. tomato DC3000 disarmed polymutants and a subset of key type III effectors. MOLECULAR PLANT PATHOLOGY 2018; 19:1779-1794. [PMID: 29277959 PMCID: PMC6638048 DOI: 10.1111/mpp.12655] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 11/10/2017] [Accepted: 12/20/2017] [Indexed: 05/22/2023]
Abstract
Pseudomonas syringae pv. tomato DC3000 and its derivatives cause disease in tomato, Arabidopsis and Nicotiana benthamiana. The primary virulence factors include a repertoire of 29 effector proteins injected into plant cells by the type III secretion system and the phytotoxin coronatine. The complete repertoire of effector genes and key coronatine biosynthesis genes have been progressively deleted and minimally reassembled to reconstitute basic pathogenic ability in N. benthamiana, and in Arabidopsis plants that have mutations in target genes that mimic effector actions. This approach and molecular studies of effector activities and plant immune system targets have highlighted a small subset of effectors that contribute to essential processes in pathogenesis. Most notably, HopM1 and AvrE1 redundantly promote an aqueous apoplastic environment, and AvrPtoB and AvrPto redundantly block early immune responses, two conditions that are sufficient for substantial bacterial growth in planta. In addition, disarmed DC3000 polymutants have been used to identify the individual effectors responsible for specific activities of the complete repertoire and to more effectively study effector domains, effector interplay and effector actions on host targets. Such work has revealed that AvrPtoB suppresses cell death elicitation in N. benthamiana that is triggered by another effector in the DC3000 repertoire, highlighting an important aspect of effector interplay in native repertoires. Disarmed DC3000 polymutants support the natural delivery of test effectors and infection readouts that more accurately reveal effector functions in key pathogenesis processes, and enable the identification of effectors with similar activities from a broad range of other pathogens that also defeat plants with cytoplasmic effectors.
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Affiliation(s)
- Hai‐Lei Wei
- School of Integrative Plant ScienceSection of Plant Pathology and Plant–Microbe Biology, Cornell UniversityIthacaNY14853USA
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of AgricultureInstitute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural SciencesBeijing100081China
| | - Alan Collmer
- School of Integrative Plant ScienceSection of Plant Pathology and Plant–Microbe Biology, Cornell UniversityIthacaNY14853USA
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BAS2 Is Required for Conidiation and Pathogenicity of Colletotrichum gloeosporioides from Hevea brasiliensis. Int J Mol Sci 2018; 19:ijms19071860. [PMID: 29941774 PMCID: PMC6073657 DOI: 10.3390/ijms19071860] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 05/28/2018] [Accepted: 06/13/2018] [Indexed: 02/04/2023] Open
Abstract
The hemibiotrophic fungi Colletotrichum gloeosporioides can cause anthracnose in rubber trees. By searching the genome of the fungal pathogen, the BAS2 encoding a biotrophy-associated secreted protein was identified. In the present study, the knockout mutants of BAS2 were constructed and the functions of BAS2 were investigated. The in vitro assays showed that BAS2 was not necessary for vegetative growth but was important for normal asexual reproduction in C. gloeosporioides. Pathogenicity assays suggested that BAS2 was involved in the process of the pathogen penetrating into the host tissue. Subcellular localization analysis revealed that BAS2 showed secretional characteristics in the fungi, and BAS2 mainly function as a cytoplasmic protein after being secreted into the host cell. Extracellular proteomics analysis revealed that BAS2 was required for the secretion of a series of proteins, which were important for the pathogenicity of C. gloeosporioides. These data lead to a better understanding of the biotrophy-associated secreted protein in regulating the pathogenesis of C. gloeosporioides.
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Deb D, Mackey D, Opiyo SO, McDowell JM. Application of alignment-free bioinformatics methods to identify an oomycete protein with structural and functional similarity to the bacterial AvrE effector protein. PLoS One 2018; 13:e0195559. [PMID: 29641586 PMCID: PMC5895030 DOI: 10.1371/journal.pone.0195559] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Accepted: 03/23/2018] [Indexed: 11/23/2022] Open
Abstract
Diverse plant pathogens export effector proteins to reprogram host cells. One of the most challenging goals in the molecular plant-microbe field is to functionally characterize the complex repertoires of effectors secreted by these pathogens. For bacterial pathogens, the predominant class of effectors is delivered to host cells by Type III secretion. For oomycetes, the predominant class of effectors is defined by a signal peptide that mediates secretion from the oomycete and a conserved RxLR motif. Downy mildew pathogens and Phytophthora species maintain hundreds of candidate RxLR effector genes in their genomes. Although no primary sequence similarity is evident between bacterial Type III effectors (T3Es) and oomycete RXLR effectors, some bacterial and oomycete effectors have convergently evolved to target the same host proteins. Such effectors might have evolved domains that are functionally similar but sequence-unrelated. We reasoned that alignment-free bioinformatics approaches could be useful to identify structural similarities between bacterial and oomycete effectors. To test this approach, we used partial least squares regression, alignment-free bioinformatics methods to identify effector proteins from the genome of the oomycete Hyaloperonospora arabidopsidis that are similar to the well-studied AvrE1 effector from Pseudomonas syringae. This approach identified five RxLR proteins with putative structural similarity to AvrE1. We focused on one, HaRxL23, because it is an experimentally validated effector and it is conserved between distantly related oomycetes. Several experiments indicate that HaRxL23 is functionally similar to AvrE1, including the ability to partially rescue an AvrE1 loss-of-function mutant. This study provides an example of how an alignment-free bioinformatics approach can identify functionally similar effector proteins in the absence of primary sequence similarity. This approach could be useful to identify effectors that have convergently evolved regardless of whether the shared host target is known.
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Affiliation(s)
- Devdutta Deb
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
| | - David Mackey
- Departments of Horticulture and Crop Science and Molecular Genetics, Ohio State University, Columbus, Ohio, United States of America
| | - Stephen O. Opiyo
- Molecular and Cellular Imaging Center-Columbus, Ohio Agricultural Research and Development Center, Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (SOO); (JMM)
| | - John M. McDowell
- Department of Plant Pathology, Physiology and Weed Science, Virginia Tech, Blacksburg, Virginia, United States of America
- * E-mail: (SOO); (JMM)
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Park E, Nedo A, Caplan JL, Dinesh-Kumar SP. Plant-microbe interactions: organelles and the cytoskeleton in action. THE NEW PHYTOLOGIST 2018; 217:1012-1028. [PMID: 29250789 DOI: 10.1111/nph.14959] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/10/2017] [Indexed: 05/06/2023]
Abstract
Contents Summary 1012 I. Introduction 1012 II. The endomembrane system in plant-microbe interactions 1013 III. The cytoskeleton in plant-microbe interactions 1017 IV. Organelles in plant-microbe interactions 1019 V. Inter-organellar communication in plant-microbe interactions 1022 VI. Conclusions and prospects 1023 Acknowledgements 1024 References 1024 SUMMARY: Plants have evolved a multilayered immune system with well-orchestrated defense strategies against pathogen attack. Multiple immune signaling pathways, coordinated by several subcellular compartments and interactions between these compartments, play important roles in a successful immune response. Pathogens use various strategies to either directly attack the plant's immune system or to indirectly manipulate the physiological status of the plant to inhibit an immune response. Microscopy-based approaches have allowed the direct visualization of membrane trafficking events, cytoskeleton reorganization, subcellular dynamics and inter-organellar communication during the immune response. Here, we discuss the contributions of organelles and the cytoskeleton to the plant's defense response against microbial pathogens, as well as the mechanisms used by pathogens to target these compartments to overcome the plant's defense barrier.
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Affiliation(s)
- Eunsook Park
- Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Alexander Nedo
- Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE, 19711, USA
| | - Jeffrey L Caplan
- Department of Biological Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE, 19711, USA
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19711, USA
| | - Savithramma P Dinesh-Kumar
- Department of Plant Biology and The Genome Center, College of Biological Sciences, University of California, Davis, CA, 95616, USA
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Chen Q, Tian Z, Jiang R, Zheng X, Xie C, Liu J. StPOTHR1, a NDR1/HIN1-like gene in Solanum tuberosum, enhances resistance against Phytophthora infestans. Biochem Biophys Res Commun 2018; 496:1155-1161. [PMID: 29407171 DOI: 10.1016/j.bbrc.2018.01.162] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 01/26/2018] [Indexed: 11/18/2022]
Abstract
A family of NDR1/HIN1-like (NHL) genes that shows homology to the nonrace-specific disease resistance (NDR1) and the tobacco (Nicotiana tabacum) harpin-induced (HIN1) genes is reported to be involved in defense. However, little information about NHL genes is available for the potato (Solanum tuberosum). Here, we report that the expression of StPOTHR1, a member of the NHL gene family, is associated with resistance in potato against Phytophthora infestans, and is specifically induced in inoculation sites. Overexpression of StPOTHR1 enhances resistance against P. infestans via restricting rapid pathogen proliferation. Further, suppression of StPOTHR1 does not compromise R-mediated cell death. Subcellular localization and posttranscription modifications (PTMs) analysis reveals that StPOTHR1 is localized in plasma membrane (PM) and undergoes multiple PTMs. Moreover, StPOTHR1 interacts with NbMKK5L, a component of the MAP kinase signaling cascade. Taken together, our results suggest that the PM-localized StPOTHR1 contributes to potato immunity against P. infestans and may be associated with the MAP kinase signaling cascade.
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Affiliation(s)
- Qiansi Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China; Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou 450001, PR China
| | - Zhendong Tian
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China
| | - Rui Jiang
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China
| | - Xueao Zheng
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China
| | - Conghua Xie
- Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China
| | - Jun Liu
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Potato Biology and Biotechnology, Ministry of Agriculture, Wuhan 430070, PR China.
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Aung K, Xin X, Mecey C, He SY. Subcellular Localization of Pseudomonas syringae pv. tomato Effector Proteins in Plants. Methods Mol Biol 2017; 1531:141-153. [PMID: 27837488 PMCID: PMC5643156 DOI: 10.1007/978-1-4939-6649-3_12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Animal and plant pathogenic bacteria use type III secretion systems to translocate proteinaceous effectors to subvert innate immunity of their host organisms. Type III secretion/effector systems are a crucial pathogenicity factor in many bacterial pathogens of plants and animals. Pseudomonas syringae pv. tomato (Pst) DC3000 injects a total of 36 protein effectors that target a variety of host proteins. Studies of a subset of Pst DC3000 effectors demonstrated that bacterial effectors, once inside the host cell, are localized to different subcellular compartments, including plasma membrane, cytoplasm, mitochondria, chloroplast, and Trans-Golgi network, to carry out their virulence functions. Identifying the subcellular localization of bacterial effector proteins in host cells could provide substantial clues to understanding the molecular and cellular basis of the virulence activities of effector proteins. In this chapter, we present methods for transient or stable expression of bacterial effector proteins in tobacco and/or Arabidopsis thaliana for live cell imaging as well as confirming the subcellular localization in plants using fluorescent organelle markers or chemical treatment.
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Affiliation(s)
- Kyaw Aung
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Xiufang Xin
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Christy Mecey
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA.
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48
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Xin XF, Nomura K, Aung K, Velásquez AC, Yao J, Boutrot F, Chang JH, Zipfel C, He SY. Bacteria establish an aqueous living space in plants crucial for virulence. Nature 2016; 539:524-529. [PMID: 27882964 DOI: 10.1038/nature20166] [Citation(s) in RCA: 266] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 10/17/2016] [Indexed: 12/26/2022]
Abstract
High humidity has a strong influence on the development of numerous diseases affecting the above-ground parts of plants (the phyllosphere) in crop fields and natural ecosystems, but the molecular basis of this humidity effect is not understood. Previous studies have emphasized immune suppression as a key step in bacterial pathogenesis. Here we show that humidity-dependent, pathogen-driven establishment of an aqueous intercellular space (apoplast) is another important step in bacterial infection of the phyllosphere. Bacterial effectors, such as Pseudomonas syringae HopM1, induce establishment of the aqueous apoplast and are sufficient to transform non-pathogenic P. syringae strains into virulent pathogens in immunodeficient Arabidopsis thaliana under high humidity. Arabidopsis quadruple mutants simultaneously defective in a host target (AtMIN7) of HopM1 and in pattern-triggered immunity could not only be used to reconstitute the basic features of bacterial infection, but also exhibited humidity-dependent dyshomeostasis of the endophytic commensal bacterial community in the phyllosphere. These results highlight a new conceptual framework for understanding diverse phyllosphere-bacterial interactions.
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Affiliation(s)
- Xiu-Fang Xin
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - Kinya Nomura
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - Kyaw Aung
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.,Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824, USA
| | - André C Velásquez
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - Jian Yao
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA
| | - Freddy Boutrot
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Jeff H Chang
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331, USA
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Sheng Yang He
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824, USA.,Howard Hughes Medical Institute-Gordon and Betty Moore Foundation, Michigan State University, East Lansing, Michigan 48824, USA.,Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824, USA.,Plant Resilience Institute, Michigan State University, East Lansing, Michigan 48824, USA
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Reverchon S, Muskhelisvili G, Nasser W. Virulence Program of a Bacterial Plant Pathogen: The Dickeya Model. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 142:51-92. [PMID: 27571692 DOI: 10.1016/bs.pmbts.2016.05.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The pectinolytic Dickeya spp. are Gram-negative bacteria causing severe disease in a wide range of plant species. Although the Dickeya genus was initially restricted to tropical and subtropical areas, two Dickeya species (D. dianthicola and D. solani) emerged recently in potato cultures in Europe. Soft-rot, the visible symptoms, is caused by plant cell wall degrading enzymes, mainly pectate lyases (Pels) that cleave the pectin polymer. However, an efficient colonization of the host requires many additional elements including early factors (eg, flagella, lipopolysaccharide, and exopolysaccharide) that allow adhesion of the bacteria and intermediate factors involved in adaptation to new growth conditions encountered in the host (eg, oxidative stress, iron starvation, and toxic compounds). To facilitate this adaptation, Dickeya have developed complex regulatory networks ensuring appropriate expression of virulence genes. This review presents recent advances in our understanding of the signals and genetic circuits impacting the expression of virulence determinants. Special attention is paid to integrated control of virulence functions by variations in the superhelical density of chromosomal DNA, and the global and specific regulators, making the regulation of Dickeya virulence an especially attractive model for those interested in relationships between the chromosomal dynamics and gene regulatory networks.
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Affiliation(s)
- S Reverchon
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France.
| | - G Muskhelisvili
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France
| | - W Nasser
- Department of Biology, University of Lyon, INSA-Lyon, Villeurbanne, Lyon, France
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Jin L, Ham JH, Hage R, Zhao W, Soto-Hernández J, Lee SY, Paek SM, Kim MG, Boone C, Coplin DL, Mackey D. Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins. PLoS Pathog 2016; 12:e1005609. [PMID: 27191168 PMCID: PMC4871590 DOI: 10.1371/journal.ppat.1005609] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 04/12/2016] [Indexed: 11/19/2022] Open
Abstract
Bacterial AvrE-family Type-III effector proteins (T3Es) contribute significantly to the virulence of plant-pathogenic species of Pseudomonas, Pantoea, Ralstonia, Erwinia, Dickeya and Pectobacterium, with hosts ranging from monocots to dicots. However, the mode of action of AvrE-family T3Es remains enigmatic, due in large part to their toxicity when expressed in plant or yeast cells. To search for targets of WtsE, an AvrE-family T3E from the maize pathogen Pantoea stewartii subsp. stewartii, we employed a yeast-two-hybrid screen with non-lethal fragments of WtsE and a synthetic genetic array with full-length WtsE. Together these screens indicate that WtsE targets maize protein phosphatase 2A (PP2A) heterotrimeric enzyme complexes via direct interaction with B' regulatory subunits. AvrE1, another AvrE-family T3E from Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), associates with specific PP2A B' subunit proteins from its susceptible host Arabidopsis that are homologous to the maize B' subunits shown to interact with WtsE. Additionally, AvrE1 was observed to associate with the WtsE-interacting maize proteins, indicating that PP2A B' subunits are likely conserved targets of AvrE-family T3Es. Notably, the ability of AvrE1 to promote bacterial growth and/or suppress callose deposition was compromised in Arabidopsis plants with mutations of PP2A genes. Also, chemical inhibition of PP2A activity blocked the virulence activity of both WtsE and AvrE1 in planta. The function of HopM1, a Pto DC3000 T3E that is functionally redundant to AvrE1, was also impaired in specific PP2A mutant lines, although no direct interaction with B' subunits was observed. These results indicate that sub-component specific PP2A complexes are targeted by bacterial T3Es, including direct targeting by members of the widely conserved AvrE-family.
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Affiliation(s)
- Lin Jin
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jong Hyun Ham
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America
| | - Rosemary Hage
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Wanying Zhao
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Jaricelis Soto-Hernández
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
| | - Sang Yeol Lee
- Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Seung-Mann Paek
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Min Gab Kim
- College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea
| | - Charles Boone
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David L. Coplin
- Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America
| | - David Mackey
- Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States of America
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