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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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2
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Goto Y, Maki N, Sklenar J, Derbyshire P, Menke FLH, Zipfel C, Kadota Y, Shirasu K. The phagocytosis oxidase/Bem1p domain-containing protein PB1CP negatively regulates the NADPH oxidase RBOHD in plant immunity. THE NEW PHYTOLOGIST 2024; 241:1763-1779. [PMID: 37823353 DOI: 10.1111/nph.19302] [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: 08/08/2023] [Accepted: 09/11/2023] [Indexed: 10/13/2023]
Abstract
Perception of pathogen-associated molecular patterns (PAMPs) by surface-localized pattern recognition receptors activates RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD) through direct phosphorylation by BOTRYTIS-INDUCED KINASE 1 (BIK1) and induces the production of reactive oxygen species (ROS). RBOHD activity must be tightly controlled to avoid the detrimental effects of ROS, but little is known about RBOHD downregulation. To understand the regulation of RBOHD, we used co-immunoprecipitation of RBOHD with mass spectrometry analysis and identified PHAGOCYTOSIS OXIDASE/BEM1P (PB1) DOMAIN-CONTAINING PROTEIN (PB1CP). PB1CP negatively regulates RBOHD and the resistance against the fungal pathogen Colletotrichum higginsianum. PB1CP competes with BIK1 for binding to RBOHD in vitro. Furthermore, PAMP treatment enhances the PB1CP-RBOHD interaction, thereby leading to the dissociation of phosphorylated BIK1 from RBOHD in vivo. PB1CP localizes at the cell periphery and PAMP treatment induces relocalization of PB1CP and RBOHD to the same small endomembrane compartments. Additionally, overexpression of PB1CP in Arabidopsis leads to a reduction in the abundance of RBOHD protein, suggesting the possible involvement of PB1CP in RBOHD endocytosis. We found PB1CP, a novel negative regulator of RBOHD, and revealed its possible regulatory mechanisms involving the removal of phosphorylated BIK1 from RBOHD and the promotion of RBOHD endocytosis.
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Affiliation(s)
- Yukihisa Goto
- RIKEN Center for Sustainable Resource Science (CSRS), Plant Immunity Research Group, Suehiro-cho 1-7-22 Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
- Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, Zurich, CH-8008, Switzerland
| | - Noriko Maki
- RIKEN Center for Sustainable Resource Science (CSRS), Plant Immunity Research Group, Suehiro-cho 1-7-22 Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Jan Sklenar
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Paul Derbyshire
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Frank L H Menke
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Cyril Zipfel
- Institute of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, Zurich, CH-8008, Switzerland
- The Sainsbury Laboratory, University of East Anglia, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Yasuhiro Kadota
- RIKEN Center for Sustainable Resource Science (CSRS), Plant Immunity Research Group, Suehiro-cho 1-7-22 Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
| | - Ken Shirasu
- RIKEN Center for Sustainable Resource Science (CSRS), Plant Immunity Research Group, Suehiro-cho 1-7-22 Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan
- Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8654, Japan
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3
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Tomar V, Rikkerink EHA, Song J, Sofkova-Bobcheva S, Bus VGM. Structure-Function Characterisation of Eop1 Effectors from the Erwinia-Pantoea Clade Reveals They May Acetylate Their Defence Target through a Catalytic Dyad. Int J Mol Sci 2023; 24:14664. [PMID: 37834112 PMCID: PMC10572645 DOI: 10.3390/ijms241914664] [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: 08/25/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
The YopJ group of acetylating effectors from phytopathogens of the genera Pseudomonas and Ralstonia have been widely studied to understand how they modify and suppress their host defence targets. In contrast, studies on a related group of effectors, the Eop1 group, lag far behind. Members of the Eop1 group are widely present in the Erwinia-Pantoea clade of Gram-negative bacteria, which contains phytopathogens, non-pathogens and potential biocontrol agents, implying that they may play an important role in agroecological or pathological adaptations. The lack of research in this group of YopJ effectors has left a significant knowledge gap in their functioning and role. For the first time, we perform a comparative analysis combining AlphaFold modelling, in planta transient expressions and targeted mutational analyses of the Eop1 group effectors from the Erwinia-Pantoea clade, to help elucidate their likely activity and mechanism(s). This integrated study revealed several new findings, including putative binding sites for inositol hexakisphosphate and acetyl coenzyme A and newly postulated target-binding domains, and raises questions about whether these effectors function through a catalytic triad mechanism. The results imply that some Eop1s may use a catalytic dyad acetylation mechanism that we found could be promoted by the electronegative environment around the active site.
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Affiliation(s)
- Vishant Tomar
- Mt Albert Research Centre, The New Zealand Institute for Plant and Food Research Limited, Auckland 1025, New Zealand
- School of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand;
| | - Erik H. A. Rikkerink
- Mt Albert Research Centre, The New Zealand Institute for Plant and Food Research Limited, Auckland 1025, New Zealand
| | - Janghoon Song
- Pear Research Institute, National Institute of Horticultural & Herbal Science, Rural Development Administration, Naju 58216, Republic of Korea
| | - Svetla Sofkova-Bobcheva
- School of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand;
| | - Vincent G. M. Bus
- Hawkes Bay Research Centre, The New Zealand Institute for Plant and Food Research Limited, Havelock North 4130, New Zealand;
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Diplock N, Baudin M, Harden L, Silva CJ, Erickson-Beltran ML, Hassan JA, Lewis JD. Utilising natural diversity of kinases to rationally engineer interactions with the angiosperm immune receptor ZAR1. PLANT, CELL & ENVIRONMENT 2023. [PMID: 37157998 DOI: 10.1111/pce.14603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 04/13/2023] [Accepted: 04/24/2023] [Indexed: 05/10/2023]
Abstract
The highly conserved angiosperm immune receptor HOPZ-ACTIVATED RESISTANCE1 (ZAR1) recognises the activity of diverse pathogen effector proteins by monitoring the ZED1-related kinase (ZRK) family. Understanding how ZAR1 achieves interaction specificity for ZRKs may allow for the expansion of the ZAR1-kinase recognition repertoire to achieve novel pathogen recognition outside of model species. We took advantage of the natural diversity of Arabidopsis thaliana kinases to probe the ZAR1-kinase interaction interface and found that A. thaliana ZAR1 (AtZAR1) can interact with most ZRKs, except ZRK7. We found evidence of alternative splicing of ZRK7, resulting in a protein that can interact with AtZAR1. Despite high sequence conservation of ZAR1, interspecific ZAR1-ZRK pairings resulted in the autoactivation of cell death. We showed that ZAR1 interacts with a greater diversity of kinases than previously thought, while still possessing the capacity for specificity in kinase interactions. Finally, using AtZAR1-ZRK interaction data, we rationally increased ZRK10 interaction strength with AtZAR1, demonstrating the feasibility of the rational design of a ZAR1-interacting kinase. Overall, our findings advance our understanding of the rules governing ZAR1 interaction specificity, with promising future directions for expanding ZAR1 immunodiversity.
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Affiliation(s)
- Nathan Diplock
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Maël Baudin
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Leslie Harden
- United States Department of Agriculture, Agriculture Research Service, Western Regional Research Center, Albany, California, USA
| | - Christopher J Silva
- United States Department of Agriculture, Agriculture Research Service, Western Regional Research Center, Albany, California, USA
| | - Melissa L Erickson-Beltran
- United States Department of Agriculture, Agriculture Research Service, Western Regional Research Center, Albany, California, USA
| | - Jana A Hassan
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Jennifer D Lewis
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
- United States Department of Agriculture, Agriculture Research Service, Plant Gene Expression Center, Albany, California, USA
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5
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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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6
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Zönnchen J, Gantner J, Lapin D, Barthel K, Eschen-Lippold L, Erickson JL, Villanueva SL, Zantop S, Kretschmer C, Joosten MHAJ, Parker JE, Guerois R, Stuttmann J. EDS1 complexes are not required for PRR responses and execute TNL-ETI from the nucleus in Nicotiana benthamiana. THE NEW PHYTOLOGIST 2022; 236:2249-2264. [PMID: 36151929 DOI: 10.1111/nph.18511] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
Heterodimeric complexes incorporating the lipase-like proteins EDS1 with PAD4 or SAG101 are central hubs in plant innate immunity. EDS1 functions encompass signal relay from TIR domain-containing intracellular NLR-type immune receptors (TNLs) towards RPW8-type helper NLRs (RNLs) and, in Arabidopsis thaliana, bolstering of signaling and resistance mediated by cell-surface pattern recognition receptors (PRRs). Increasing evidence points to the activation of EDS1 complexes by small molecule binding. We used CRISPR/Cas-generated mutant lines and agroinfiltration-based complementation assays to interrogate functions of EDS1 complexes in Nicotiana benthamiana. We did not detect impaired PRR signaling in N. benthamiana lines deficient in EDS1 complexes or RNLs. Intriguingly, in assays monitoring functions of SlEDS1-NbEDS1 complexes in N. benthamiana, mutations within the SlEDS1 catalytic triad could abolish or enhance TNL immunity. Furthermore, nuclear EDS1 accumulation was sufficient for N. benthamiana TNL (Roq1) immunity. Reinforcing PRR signaling in Arabidopsis might be a derived function of the TNL/EDS1 immune sector. Although Solanaceae EDS1 functionally depends on catalytic triad residues in some contexts, our data do not support binding of a TNL-derived small molecule in the triad environment. Whether and how nuclear EDS1 activity connects to membrane pore-forming RNLs remains unknown.
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Affiliation(s)
- Josua Zönnchen
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
| | - Johannes Gantner
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
| | - Dmitry Lapin
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, D-50829, Cologne, Germany
- Department of Biology, Plant-Microbe Interactions, Utrecht University, 3584 CH, Utrecht, the Netherlands
| | - Karen Barthel
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
| | - Lennart Eschen-Lippold
- Department of Crop Physiology, Institute of Agricultural and Nutritional Sciences, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
- Department of Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, D-06120, Halle, Germany
| | - Jessica L Erickson
- Department of Biochemistry of Plant Interactions, Leibniz Institute of Plant Biochemistry, D-06120, Halle, Germany
| | - Sergio Landeo Villanueva
- Laboratory of Phytopathology, Wageningen University and Research, 6708 PB, Wageningen, the Netherlands
| | - Stefan Zantop
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
| | - Carola Kretschmer
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
| | - Matthieu H A J Joosten
- Laboratory of Phytopathology, Wageningen University and Research, 6708 PB, Wageningen, the Netherlands
| | - Jane E Parker
- Department of Plant-Microbe Interactions, Max-Planck Institute for Plant Breeding Research, D-50829, Cologne, Germany
- Cologne-Düsseldorf Cluster of Excellence in Plant Sciences (CEPLAS), D-40225, Düsseldorf, Germany
| | - Raphael Guerois
- Institute for Integrative Biology of the Cell (I2BC), IBITECS, CEA, CNRS, Université Paris-Saclay, F-91198, Gif-sur-Yvette, France
| | - Johannes Stuttmann
- Department of Plant Genetics, Institute for Biology, Martin Luther University Halle-Wittenberg, D-06120, Halle, Germany
- Institute for Biosafety in Plant Biotechnology, Federal Research Centre for Cultivated Plants, Julius Kühn-Institute (JKI), 06484, Quedlinburg, Germany
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7
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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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8
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Zheng X, Zhou Z, Gong Z, Hu M, Ahn YJ, Zhang X, Zhao Y, Gong G, Zhang J, Zuo J, Han GZ, Hoon SK, Zhou JM. Two plant NLR proteins confer strain-specific resistance conditioned by an effector from Pseudomonas syringae pv. actinidiae. J Genet Genomics 2022; 49:823-832. [PMID: 35760352 DOI: 10.1016/j.jgg.2022.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/06/2022] [Accepted: 06/15/2022] [Indexed: 11/27/2022]
Abstract
Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker, a devastating disease threatening the Actinidia fruit industry. In a search for non-host resistance genes against Psa, we found that the nucleotide-binding leucine-rich repeat receptor (NLR) protein ZAR1 from both Arabidopsis and Nicotiana benthamiana (Nb) recognizes HopZ5 and triggers cell death. The recognition requires ZED1 in Arabidopsis and JIM2 in Nb plants, which are members of the ZRK pseudokinases and known components of the ZAR1 resistosome. Surprisingly, Arabidopsis ZAR1 and RPM1, another NLR known to recognize HopZ5, confer disease resistance to HopZ5 in a strain-specific manner. Thus, ZAR1, but not RPM1, is solely required for resistance to P. s. maculicola ES4326 (Psm) carrying hopZ5, whereas RPM1 is primarily required for resistance to P. s. tomato DC3000 (Pst) carrying hopZ5. Furthermore, the ZAR1-mediated resistance to Psm hopZ5 in Arabidopsis is insensitive to SOBER1, which encodes a deacetylase known to suppress the RPM1-mediated resistance to Pst hopZ5. In addition, hopZ5 enhances P. syringae virulence in the absence of ZAR1 or RPM1, and that SOBER1 abolishes such virulence function. Together the study suggests that ZAR1 may be used for improving Psa resistance in Actinidia and uncovers previously unknown complexity of effector-triggered immunity and effector-triggered virulence.
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Affiliation(s)
- Xiaojuan Zheng
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zhaoyang Zhou
- College of Horticulture, China Agricultural University, Beijing 100193, P. R. China
| | - Zhen Gong
- College of Life Sciences, Jiangsu Key Laboratory for Microbes and Functional Genomics, Nanjing Normal University, Nanjing, Jiangsu 210023, P. R. China
| | - Meijuan Hu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Ye Jin Ahn
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Xiaojuan Zhang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Yan Zhao
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guoshu Gong
- Plant Protection Department and Major Crop Disease Laboratory, College of Agronomy, Sichuan Agricultural University, Chengdu, Sichuan 611130, P. R. China
| | - Jian Zhang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Jianru Zuo
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China; Hainan Yazhou Bay Seed Laboratory, Sanya 572025, P. R. China
| | - Guan-Zhu Han
- College of Life Sciences, Jiangsu Key Laboratory for Microbes and Functional Genomics, Nanjing Normal University, Nanjing, Jiangsu 210023, P. R. China
| | - Sohn Kee Hoon
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea; School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China; Hainan Yazhou Bay Seed Laboratory, Sanya 572025, P. R. China.
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9
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Denne NL, Hiles RR, Kyrysyuk O, Iyer-Pascuzzi AS, Mitra RM. Ralstonia solanacearum Effectors Localize to Diverse Organelles in Solanum Hosts. PHYTOPATHOLOGY 2021; 111:2213-2226. [PMID: 33720750 DOI: 10.1094/phyto-10-20-0483-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phytopathogenic bacteria secrete type III effector (T3E) proteins directly into host plant cells. T3Es can interact with plant proteins and frequently manipulate plant host physiological or developmental processes. The proper subcellular localization of T3Es is critical for their ability to interact with plant targets, and knowledge of T3E localization can be informative for studies of effector function. Here we investigated the subcellular localization of 19 T3Es from the phytopathogenic bacteria Ralstonia pseudosolanacearum and Ralstonia solanacearum. Approximately 45% of effectors in our library localize to both the plant cell periphery and the nucleus, 15% exclusively to the cell periphery, 15% exclusively to the nucleus, and 25% to other organelles, including tonoplasts and peroxisomes. Using tomato hairy roots, we show that T3E localization is similar in both leaves and roots and is not impacted by Solanum species. We find that in silico prediction programs are frequently inaccurate, highlighting the value of in planta localization experiments. Our data suggest that Ralstonia targets a wide diversity of cellular organelles and provides a foundation for developing testable hypotheses about Ralstonia effector function.
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Affiliation(s)
- Nina L Denne
- Department of Biology, Carleton College, Northfield, MN 55057
| | - Rachel R Hiles
- Department of Botany and Plant Pathology and Center for Plant Biology, Purdue University, West Lafayette, IN 47907
| | | | - Anjali S Iyer-Pascuzzi
- Department of Botany and Plant Pathology and Center for Plant Biology, Purdue University, West Lafayette, IN 47907
| | - Raka M Mitra
- Department of Biology, Carleton College, Northfield, MN 55057
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10
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Bi G, Zhou JM. Regulation of Cell Death and Signaling by Pore-Forming Resistosomes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:239-263. [PMID: 33957051 DOI: 10.1146/annurev-phyto-020620-095952] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nucleotide-binding leucine-rich repeat receptors (NLRs) are the largest class of immune receptors in plants. They play a key role in the plant surveillance system by monitoring pathogen effectors that are delivered into the plant cell. Recent structural biology and biochemical analyses have uncovered how NLRs are activated to form oligomeric resistosomes upon the recognition of pathogen effectors. In the resistosome, the signaling domain of the NLR is brought to the center of a ringed structure to initiate immune signaling and regulated cell death (RCD). The N terminus of the coiled-coil (CC) domain of the NLR protein HOPZ-ACTIVATED RESISTANCE 1 likely forms a pore in the plasma membrane to trigger RCD in a way analogous to animal pore-forming proteins that trigger necroptosis or pyroptosis. NLRs that carry TOLL-INTERLEUKIN1-RECEPTOR as a signaling domain may also employ pore-forming resistosomes for RCD execution. In addition, increasing evidence supports intimate connections between NLRs and surface receptors in immune signaling. These new findings are rapidly advancing our understanding of the plant immune system.
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Affiliation(s)
- Guozhi Bi
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China;
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China;
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China
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11
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Rufián JS, Rueda-Blanco J, López-Márquez D, Macho AP, Beuzón CR, Ruiz-Albert J. The bacterial effector HopZ1a acetylates MKK7 to suppress plant immunity. THE NEW PHYTOLOGIST 2021; 231:1138-1156. [PMID: 33960430 DOI: 10.1111/nph.17442] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
The Pseudomonas syringae type III secretion system translocates effector proteins into the host cell cytosol to suppress plant basal immunity. Effector HopZ1a suppresses local and systemic immunity triggered by pathogen-associated molecular patterns (PAMPs) and effectors, through target acetylation. HopZ1a has been shown to target several plant proteins, but none fully substantiates HopZ1a-associated immune suppression. Here, we investigate Arabidopsis thaliana mitogen-activated protein kinase kinases (MKKs) as potential targets, focusing on AtMKK7, a positive regulator of local and systemic immunity. We analyse HopZ1a interference with AtMKK7 by translocation of HopZ1a from bacteria inoculated into Arabidopsis expressing MKK7 from an inducible promoter. Reciprocal phenotypes are analysed on plants expressing a construct quenching MKK7 native expression. We analyse HopZ1a-MKK7 interaction by three independent methods, and the relevance of acetylation by in vitro kinase and in planta functional assays. We demonstrate the AtMKK7 contribution to immune signalling showing MKK7-dependent flg22-induced reactive oxygen species (ROS) burst, MAP kinas (MAPK) activation and callose deposition, plus AvrRpt2-triggered MKK7-dependent signalling. Furthermore, we demonstrate HopZ1a suppression of all MKK7-dependent responses, HopZ1a-MKK7 interaction in planta and HopZ1a acetylation of MKK7 with a lysine required for full kinase activity. We demonstrate that HopZ1a targets AtMKK7 to suppress local and systemic plant immunity.
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Affiliation(s)
- José S Rufián
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Campus de Teatinos, Málaga, E-29071, Spain
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Javier Rueda-Blanco
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Campus de Teatinos, Málaga, E-29071, Spain
| | - Diego López-Márquez
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Campus de Teatinos, Málaga, E-29071, Spain
| | - Alberto P Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Carmen R Beuzón
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Campus de Teatinos, Málaga, E-29071, Spain
| | - Javier Ruiz-Albert
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Campus de Teatinos, Málaga, E-29071, Spain
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12
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Makita Y, Suzuki S, Fushimi K, Shimada S, Suehisa A, Hirata M, Kuriyama T, Kurihara Y, Hamasaki H, Okubo-Kurihara E, Yoshitake K, Watanabe T, Sakuta M, Gojobori T, Sakami T, Narikawa R, Yamaguchi H, Kawachi M, Matsui M. Identification of a dual orange/far-red and blue light photoreceptor from an oceanic green picoplankton. Nat Commun 2021; 12:3593. [PMID: 34135337 PMCID: PMC8209157 DOI: 10.1038/s41467-021-23741-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 05/11/2021] [Indexed: 11/09/2022] Open
Abstract
Photoreceptors are conserved in green algae to land plants and regulate various developmental stages. In the ocean, blue light penetrates deeper than red light, and blue-light sensing is key to adapting to marine environments. Here, a search for blue-light photoreceptors in the marine metagenome uncover a chimeric gene composed of a phytochrome and a cryptochrome (Dualchrome1, DUC1) in a prasinophyte, Pycnococcus provasolii. DUC1 detects light within the orange/far-red and blue spectra, and acts as a dual photoreceptor. Analyses of its genome reveal the possible mechanisms of light adaptation. Genes for the light-harvesting complex (LHC) are duplicated and transcriptionally regulated under monochromatic orange/blue light, suggesting P. provasolii has acquired environmental adaptability to a wide range of light spectra and intensities.
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Affiliation(s)
- Yuko Makita
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Shigekatsu Suzuki
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Keiji Fushimi
- Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
- Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan
| | - Setsuko Shimada
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Aya Suehisa
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Manami Hirata
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Tomoko Kuriyama
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Yukio Kurihara
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Hidefumi Hamasaki
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Yokohama City University, Kihara Institute for Biological Research, Yokohama, Japan
| | - Emiko Okubo-Kurihara
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Kazutoshi Yoshitake
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Tsuyoshi Watanabe
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Kushiro, Hokkaido, Japan
| | - Masaaki Sakuta
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Takashi Gojobori
- Computational Bioscience Research Center, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Tomoko Sakami
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Minami-ise, Mie, Japan
| | - Rei Narikawa
- Graduate School of Integrated Science and Technology, Shizuoka University, Shizuoka, Japan
- Research Institute of Green Science and Technology, Shizuoka University, Shizuoka, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama, Japan
- Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan
| | - Haruyo Yamaguchi
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Masanobu Kawachi
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Japan
| | - Minami Matsui
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan.
- Yokohama City University, Kihara Institute for Biological Research, Yokohama, Japan.
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13
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Bi G, Su M, Li N, Liang Y, Dang S, Xu J, Hu M, Wang J, Zou M, Deng Y, Li Q, Huang S, Li J, Chai J, He K, Chen YH, Zhou JM. The ZAR1 resistosome is a calcium-permeable channel triggering plant immune signaling. Cell 2021; 184:3528-3541.e12. [PMID: 33984278 DOI: 10.1016/j.cell.2021.05.003] [Citation(s) in RCA: 274] [Impact Index Per Article: 91.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/18/2021] [Accepted: 05/04/2021] [Indexed: 12/21/2022]
Abstract
Nucleotide-binding, leucine-rich repeat receptors (NLRs) are major immune receptors in plants and animals. Upon activation, the Arabidopsis NLR protein ZAR1 forms a pentameric resistosome in vitro and triggers immune responses and cell death in plants. In this study, we employed single-molecule imaging to show that the activated ZAR1 protein can form pentameric complexes in the plasma membrane. The ZAR1 resistosome displayed ion channel activity in Xenopus oocytes in a manner dependent on a conserved acidic residue Glu11 situated in the channel pore. Pre-assembled ZAR1 resistosome was readily incorporated into planar lipid-bilayers and displayed calcium-permeable cation-selective channel activity. Furthermore, we show that activation of ZAR1 in the plant cell led to Glu11-dependent Ca2+ influx, perturbation of subcellular structures, production of reactive oxygen species, and cell death. The results thus support that the ZAR1 resistosome acts as a calcium-permeable cation channel to trigger immunity and cell death.
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Affiliation(s)
- Guozhi Bi
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Min Su
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Nan Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu Liang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Song Dang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jiachao Xu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Meijuan Hu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Jizong Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Minxia Zou
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China; Key Laboratory of Cell Proliferation and Regulation of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Yanan Deng
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiyu Li
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Shijia Huang
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jiejie Li
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China; Key Laboratory of Cell Proliferation and Regulation of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | - Jijie Chai
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Max-Planck Institute for Plant Breeding Research, Cologne, Germany; Institute of Biochemistry, University of Cologne, Zuelpicher Str. 47, 50674 Cologne, Germany.
| | - Kangmin He
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China.
| | - Yu-Hang Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China; Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China.
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China.
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14
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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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15
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Baudin M, Martin EC, Sass C, Hassan JA, Bendix C, Sauceda R, Diplock N, Specht CD, Petrescu AJ, Lewis JD. A natural diversity screen in Arabidopsis thaliana reveals determinants for HopZ1a recognition in the ZAR1-ZED1 immune complex. PLANT, CELL & ENVIRONMENT 2021; 44:629-644. [PMID: 33103794 DOI: 10.1111/pce.13927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/15/2020] [Accepted: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Pathogen pressure on hosts can lead to the evolution of genes regulating the innate immune response. By characterizing naturally occurring polymorphisms in immune receptors, we can better understand the molecular determinants of pathogen recognition. ZAR1 is an ancient Arabidopsis thaliana NLR (Nucleotide-binding [NB] Leucine-rich-repeat [LRR] Receptor) that recognizes multiple secreted effector proteins from the pathogenic bacteria Pseudomonas syringae and Xanthomonas campestris through its interaction with receptor-like cytoplasmic kinases (RLCKs). ZAR1 was first identified for its role in recognizing P. syringae effector HopZ1a, through its interaction with the RLCK ZED1. To identify additional determinants of HopZ1a recognition, we performed a computational screen for ecotypes from the 1001 Genomes project that were likely to lack HopZ1a recognition, and tested ~300 ecotypes. We identified ecotypes containing polymorphisms in ZAR1 and ZED1. Using our previously established Nicotiana benthamiana transient assay and Arabidopsis ecotypes, we tested for the effect of naturally occurring polymorphisms on ZAR1 interactions and the immune response. We identified key residues in the NB or LRR domain of ZAR1 that impact the interaction with ZED1. We demonstrate that natural diversity combined with functional assays can help define the molecular determinants and interactions necessary to regulate immune induction in response to pathogens.
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Affiliation(s)
- Maël Baudin
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Eliza C Martin
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Chodon Sass
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Jana A Hassan
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Claire Bendix
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Rolin Sauceda
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Nathan Diplock
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
| | - Chelsea D Specht
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
- School of Integrative Plant Science, Section of Plant Biology and the L.H. Bailey Hortorium, Cornell University, Ithaca, New York, USA
| | - Andrei J Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Jennifer D Lewis
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, USA
- Plant Gene Expression Center, United States Department of Agriculture, Albany, California, USA
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16
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Jiang T, Mu B, Zhao R. Plastid chaperone HSP90C guides precursor proteins to the SEC translocase for thylakoid transport. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7073-7087. [PMID: 32853383 PMCID: PMC7906790 DOI: 10.1093/jxb/eraa399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 08/24/2020] [Indexed: 05/04/2023]
Abstract
Chloroplast stromal factors involved in regulating thylakoid protein targeting are poorly understood. We previously reported that in Arabidopsis thaliana, the stromal-localized chaperone HSP90C (plastid heat shock protein 90) interacted with the nuclear-encoded thylakoid lumen protein PsbO1 (PSII subunit O isoform 1) and suggested a role for HSP90C in aiding PsbO1 thylakoid targeting. Using in organello transport assays, particularly with model substrates naturally expressed in stroma, we showed that light, exogenous ATP, and HSP90C activity were required for Sec-dependent transport of green fluorescent protein (GFP) led by the PsbO1 thylakoid targeting sequence. Using a previously identified PsbO1T200A mutant, we provided evidence that a stronger interaction between HSP90C and PsbO1 better facilitated its stroma-thylakoid trafficking. We also demonstrated that SecY1, the channel protein of the thylakoid SEC translocase, specifically interacted with HSP90C in vivo. Inhibition of the chaperone ATPase activity suppressed the association of the PsbO1GFP-HSP90C complex with SecY1. Together with analyzing the expression and accumulation of a few other thylakoid proteins that utilize the SRP, TAT, or SEC translocation pathways, we propose a model in which HSP90C forms a guiding complex that interacts with thylakoid protein precursors and assists in their specific targeting to the thylakoid SEC translocon.
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Affiliation(s)
- Tim Jiang
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Bona Mu
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rongmin Zhao
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
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17
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Forrest S, Welch M. Arming the troops: Post-translational modification of extracellular bacterial proteins. Sci Prog 2020; 103:36850420964317. [PMID: 33148128 PMCID: PMC10450907 DOI: 10.1177/0036850420964317] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Protein secretion is almost universally employed by bacteria. Some proteins are retained on the cell surface, whereas others are released into the extracellular milieu, often playing a key role in virulence. In this review, we discuss the diverse types and potential functions of post-translational modifications (PTMs) occurring to extracellular bacterial proteins.
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Affiliation(s)
- Suzanne Forrest
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Martin Welch
- Department of Biochemistry, University of Cambridge, Cambridge, UK
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18
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Carianopol CS, Gazzarrini S. SnRK1α1 Antagonizes Cell Death Induced by Transient Overexpression of Arabidopsis thaliana ABI5 Binding Protein 2 (AFP2). FRONTIERS IN PLANT SCIENCE 2020; 11:582208. [PMID: 33133119 PMCID: PMC7550686 DOI: 10.3389/fpls.2020.582208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/10/2020] [Indexed: 06/01/2023]
Abstract
Plants are continuously exposed to environmental stressors. They have thus evolved complex signaling pathways to govern responses to a variety of stimuli. The hormone abscisic acid (ABA) has been implicated in modulating both abiotic and biotic stress responses in plants. ABI5 Binding Proteins (AFPs) are a family of negative regulators of bZIP transcription factors of the AREB/ABF family, which promote ABA responses. AFP2 interacts with Snf1-Related protein Kinase 1 (SnRK1), which belongs to a highly conserved heterotrimeric kinase complex that is activated to re-establish energy homeostasis following stress. However, the role of this interaction is currently unknown. Here, we show that transient overexpression of Arabidopsis thaliana AFP2 in Nicotiana benthamiana leaves induces cell death (CD). Using truncated AFP2 constructs, we demonstrate that CD induction by AFP2 is dependent on the EAR domain. Co-expression of the catalytic subunit SnRK1α1, but not SnRK1α2, rescues AFP2-induced CD. Overexpression of SnRK1α1 has little effect on AFP2 protein level and does not affect AFP2 subcellular localization. Our results show that a high level of AFP2 is detrimental for cell function and that SnRK1α1 antagonizes AFP2-induced CD most likely through a mechanism that does not involve AFP2 protein degradation or a change in subcellular localization.
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Affiliation(s)
- Carina Steliana Carianopol
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Sonia Gazzarrini
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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19
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Hu M, Qi J, Bi G, Zhou JM. Bacterial Effectors Induce Oligomerization of Immune Receptor ZAR1 In Vivo. MOLECULAR PLANT 2020; 13:793-801. [PMID: 32194243 DOI: 10.1016/j.molp.2020.03.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 03/02/2020] [Accepted: 03/11/2020] [Indexed: 05/22/2023]
Abstract
Plants utilize nucleotide-binding, leucine-rich repeat receptors (NLRs) to detect pathogen effectors, leading to effector-triggered immunity. The NLR ZAR1 indirectly recognizes the Xanthomonas campestris pv. campestris effector AvrAC and Pseudomonas syringae effector HopZ1a by associating with closely related receptor-like cytoplasmic kinase subfamily XII-2 (RLCK XII-2) members RKS1 and ZED1, respectively. ZAR1, RKS1, and the AvrAC-modified decoy PBL2UMP form a pentameric resistosome in vitro, and the ability of resistosome formation is required for AvrAC-triggered cell death and disease resistance. However, it remains unknown whether the effectors induce ZAR1 oligomerization in the plant cell. In this study, we show that both AvrAC and HopZ1a can induce oligomerization of ZAR1 in Arabidopsis protoplasts. Residues mediating ZAR1-ZED1 interaction are indispensable for HopZ1a-induced ZAR1 oligomerization in vivo and disease resistance. In addition, ZAR1 residues required for the assembly of ZAR1 resistosome in vitro are also essential for HopZ1a-induced ZAR1 oligomerization in vivo and disease resistance. Our study provides evidence that pathogen effectors induce ZAR1 resistosome formation in the plant cell and that the resistosome formation triggers disease resistance.
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Affiliation(s)
- Meijuan Hu
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jinfeng Qi
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guozhi Bi
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China.
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100101, P. R. China; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
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20
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Laflamme B, Dillon MM, Martel A, Almeida RND, Desveaux D, Guttman DS. The pan-genome effector-triggered immunity landscape of a host-pathogen interaction. Science 2020; 367:763-768. [PMID: 32054757 DOI: 10.1126/science.aax4079] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 10/18/2019] [Accepted: 01/17/2020] [Indexed: 12/24/2022]
Abstract
Effector-triggered immunity (ETI), induced by host immune receptors in response to microbial effectors, protects plants against virulent pathogens. However, a systematic study of ETI prevalence against species-wide pathogen diversity is lacking. We constructed the Pseudomonas syringae Type III Effector Compendium (PsyTEC) to reduce the pan-genome complexity of 5127 unique effector proteins, distributed among 70 families from 494 strains, to 529 representative alleles. We screened PsyTEC on the model plant Arabidopsis thaliana and identified 59 ETI-eliciting alleles (11.2%) from 19 families (27.1%), with orthologs distributed among 96.8% of P. syringae strains. We also identified two previously undescribed host immune receptors, including CAR1, which recognizes the conserved effectors AvrE and HopAA1, and found that 94.7% of strains harbor alleles predicted to be recognized by either CAR1 or ZAR1.
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Affiliation(s)
- Bradley Laflamme
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Marcus M Dillon
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Alexandre Martel
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Renan N D Almeida
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada.
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada. .,Center for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON M5S 3B2, Canada
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21
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Carianopol CS, Chan AL, Dong S, Provart NJ, Lumba S, Gazzarrini S. An abscisic acid-responsive protein interaction network for sucrose non-fermenting related kinase1 in abiotic stress response. Commun Biol 2020; 3:145. [PMID: 32218501 PMCID: PMC7099082 DOI: 10.1038/s42003-020-0866-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 02/24/2020] [Indexed: 12/13/2022] Open
Abstract
Yeast Snf1 (Sucrose non-fermenting1), mammalian AMPK (5′ AMP-activated protein kinase) and plant SnRK1 (Snf1-Related Kinase1) are conserved heterotrimeric kinase complexes that re-establish energy homeostasis following stress. The hormone abscisic acid (ABA) plays a crucial role in plant stress response. Activation of SnRK1 or ABA signaling results in overlapping transcriptional changes, suggesting these stress pathways share common targets. To investigate how SnRK1 and ABA interact during stress response in Arabidopsis thaliana, we screened the SnRK1 complex by yeast two-hybrid against a library of proteins encoded by 258 ABA-regulated genes. Here, we identify 125 SnRK1- interacting proteins (SnIPs). Network analysis indicates that a subset of SnIPs form signaling modules in response to abiotic stress. Functional studies show the involvement of SnRK1 and select SnIPs in abiotic stress responses. This targeted study uncovers the largest set of SnRK1 interactors, which can be used to further characterize SnRK1 role in plant survival under stress. Carianopol et al. construct a detailed protein interaction network for the SnRK1 kinase complex to investigate the interaction of SnRK1 and ABA during stress response. They identify 125 proteins that interact with SnRK1, which can be used further to characterise the role of SnRK1 in plant survival under stress.
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Affiliation(s)
- Carina Steliana Carianopol
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.,Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Aaron Lorheed Chan
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.,Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Shaowei Dong
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Nicholas J Provart
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.,Centre for the Analysis of Genome Evolution and Function, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Shelley Lumba
- Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada
| | - Sonia Gazzarrini
- Department of Biological Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada. .,Department of Cell and Systems Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 3B2, Canada.
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22
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Chen Y, Bendix C, Lewis JD. Comparative Genomics Screen Identifies Microbe-Associated Molecular Patterns from ' Candidatus Liberibacter' spp. That Elicit Immune Responses in Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:539-552. [PMID: 31790346 DOI: 10.1094/mpmi-11-19-0309-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Citrus huanglongbing (HLB), caused by phloem-limited 'Candidatus Liberibacter' bacteria, is a destructive disease threatening the worldwide citrus industry. The mechanisms of pathogenesis are poorly understood and no efficient strategy is available to control HLB. Here, we used a comparative genomics screen to identify candidate microbe-associated molecular patterns (MAMPs) from 'Ca. Liberibacter' spp. We identified the core genome from multiple 'Ca. Liberibacter' pathogens, and searched for core genes with signatures of positive selection. We hypothesized that genes encoding putative MAMPs would evolve to reduce recognition by the plant immune system, while retaining their essential functions. To efficiently screen candidate MAMP peptides, we established a high-throughput microtiter plate-based screening assay, particularly for citrus, that measured reactive oxygen species (ROS) production, which is a common immune response in plants. We found that two peptides could elicit ROS production in Arabidopsis and Nicotiana benthamiana. One of these peptides elicited ROS production and defense gene expression in HLB-tolerant citrus genotypes, and induced MAMP-triggered immunity against the bacterial pathogen Pseudomonas syringae. Our findings identify MAMPs that boost immunity in citrus and could help prevent or reduce HLB infection.
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Affiliation(s)
- Yuan Chen
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
| | - Claire Bendix
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
| | - Jennifer D Lewis
- Plant Gene Expression Center, United States Department of Agriculture-Agricultural Research Service and Department of Plant and Microbial Biology, University of California-Berkeley, 800 Buchanan Street, Albany, CA 94710, U.S.A
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23
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Martel A, Lo T, Desveaux D, Guttman DS. A High-Throughput, Seedling Screen for Plant Immunity. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:394-401. [PMID: 31851574 DOI: 10.1094/mpmi-10-19-0295-ta] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
An understanding of how biological diversity affects plant-microbe interactions is becoming increasingly important, particularly with respect to components of the pathogen effector arsenal and the plant immune system. Although technological improvements have greatly advanced our ability to examine molecular sequences and interactions, relatively few advances have been made that facilitate high-throughput, in vivo pathology screens. Here, we present a high-throughput, microplate-based, nondestructive seedling pathology assay, and apply it to identify Arabidopsis thaliana effector-triggered immunity (ETI) responses against Pseudomonas syringae type III secreted effectors. The assay was carried out in a 48-well microplate format with spray inoculation, and disease symptoms were quantitatively recorded in a semiautomated manner, thereby greatly reducing both time and costs. The assay requires only slight modifications of common labware and uses no proprietary software. We validated the assay by recapitulating known ETI responses induced by P. syringae in Arabidopsis. We also demonstrated that we can quantitatively differentiate responses from a diversity of plant genotypes grown in the same microplate. Finally, we showed that the results obtained from our assay can be used to perform genome-wide association studies to identify host immunity genes, recapitulating results that have been independently obtained with mature plants.
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Affiliation(s)
- Alexandre Martel
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Timothy Lo
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
| | - David S Guttman
- Department of Cell and Systems Biology, University of Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Ontario, Canada
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24
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Baudin M, Schreiber KJ, Martin EC, Petrescu AJ, Lewis JD. Structure-function analysis of ZAR1 immune receptor reveals key molecular interactions for activity. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:352-370. [PMID: 31557357 DOI: 10.1111/tpj.14547] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/11/2019] [Accepted: 09/16/2019] [Indexed: 05/26/2023]
Abstract
NLR (nucleotide-binding [NB] leucine-rich repeat [LRR] receptor) proteins are critical for inducing immune responses in response to pathogen proteins, and must be tightly modulated to prevent spurious activation in the absence of a pathogen. The ZAR1 NLR recognizes diverse effector proteins from Pseudomonas syringae, including HopZ1a, and Xanthomonas species. Receptor-like cytoplasmic kinases (RLCKs) such as ZED1, interact with ZAR1 and provide specificity for different effector proteins, such as HopZ1a. We previously developed a transient expression system in Nicotiana benthamiana that allowed us to demonstrate that ZAR1 function is conserved from the Brassicaceae to the Solanaceae. Here, we combined structural modelling of ZAR1, with molecular and functional assays in our transient system, to show that multiple intramolecular and intermolecular interactions modulate ZAR1 activity. We identified determinants required for the formation of the ZARCC oligomer and its activity. Lastly, we characterized intramolecular interactions between ZAR1 subdomains that participate in keeping ZAR1 immune complexes inactive. This work identifies molecular constraints on immune receptor function and activation.
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Affiliation(s)
- Maël Baudin
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, USA
| | - Karl J Schreiber
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, USA
| | - Eliza C Martin
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Andrei J Petrescu
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Jennifer D Lewis
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, USA
- United States Department of Agriculture, Plant Gene Expression Center, Albany, USA
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25
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Albers P, Üstün S, Witzel K, Kraner M, Börnke F. A Remorin from Nicotiana benthamiana Interacts with the Pseudomonas Type-III Effector Protein HopZ1a and is Phosphorylated by the Immune-Related Kinase PBS1. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1229-1242. [PMID: 31012804 DOI: 10.1094/mpmi-04-19-0105-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The plasma membrane (PM) is at the interface of plant-pathogen interactions and, thus, many bacterial type-III effector (T3E) proteins target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E HopZ1a is a host cell PM-localized effector protein that has several immunity-associated host targets but also activates effector-triggered immunity in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated PM-associated HopZ1a target protein has been identified until now. Here, we show that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 relocalizes to membrane nanodomains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense-related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase avrPphB-susceptible 1 (PBS1) and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a-NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed.Copyright © 2019 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)
- Philip Albers
- Plant Metabolism, Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), 14979 Großbeeren, Germany
| | - Suayib Üstün
- Plant Metabolism, Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), 14979 Großbeeren, Germany
| | - Katja Witzel
- Principles of Integrated Pest Management, Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), 14979 Großbeeren, Germany
| | - Max Kraner
- Friedrich-Alexander-Universität, Department of Biology, Division of Biochemistry, 91058 Erlangen, Germany
| | - Frederik Börnke
- Plant Metabolism, Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), 14979 Großbeeren, Germany
- Institute of Biochemistry and Biology, University of Potsdam, 14476 Potsdam, Germany
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26
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Bastedo DP, Khan M, Martel A, Seto D, Kireeva I, Zhang J, Masud W, Millar D, Lee JY, Lee AHY, Gong Y, Santos-Severino A, Guttman DS, Desveaux D. Perturbations of the ZED1 pseudokinase activate plant immunity. PLoS Pathog 2019; 15:e1007900. [PMID: 31269090 PMCID: PMC6634424 DOI: 10.1371/journal.ppat.1007900] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 07/16/2019] [Accepted: 06/08/2019] [Indexed: 11/19/2022] Open
Abstract
The Pseudomonas syringae acetyltransferase HopZ1a is delivered into host cells by the type III secretion system to promote bacterial growth. However, in the model plant host Arabidopsis thaliana, HopZ1a activity results in an effector-triggered immune response (ETI) that limits bacterial proliferation. HopZ1a-triggered immunity requires the nucleotide-binding, leucine-rich repeat domain (NLR) protein, ZAR1, and the pseudokinase, ZED1. Here we demonstrate that HopZ1a can acetylate members of a family of ‘receptor-like cytoplasmic kinases’ (RLCK family VII; also known as PBS1-like kinases, or PBLs) and promote their interaction with ZED1 and ZAR1 to form a ZAR1-ZED1-PBL ternary complex. Interactions between ZED1 and PBL kinases are determined by the pseudokinase features of ZED1, and mutants designed to restore ZED1 kinase motifs can (1) bind to PBLs, (2) recruit ZAR1, and (3) trigger ZAR1-dependent immunity in planta, all independently of HopZ1a. A ZED1 mutant that mimics acetylation by HopZ1a also triggers immunity in planta, providing evidence that effector-induced perturbations of ZED1 also activate ZAR1. Overall, our results suggest that interactions between these two RLCK families are promoted by perturbations of structural features that distinguish active from inactive kinase domain conformations. We propose that effector-induced interactions between ZED1/ZRK pseudokinases (RLCK family XII) and PBL kinases (RLCK family VII) provide a sensitive mechanism for detecting perturbations of either kinase family to activate ZAR1-mediated ETI. All plants must ward off potentially infectious microbes, and those grown in large-scale crop operations are especially vulnerable to the rapid spread of disease by successful pathogens. Although many bacteria and fungi can supress plant immune responses by producing specialized virulence proteins called ‘effectors’, these effectors can also trigger immune responses that render plants resistant to infection. We studied the molecular mechanisms underlying one such effector-triggered immune response elicited by the bacterial effector HopZ1a in the model plant host Arabidopsis thaliana. We have shown that HopZ1a promotes binding between a ZED1, a ‘pseudokinase’ required for HopZ1a-triggered immunity, and several ‘true kinases’ (known as PBLs) that are likely targets of HopZ1a activity in planta. HopZ1a-induced ZED1-PBL interactions also recruit ZAR1, an Arabidopsis ‘resistance protein’ previously implicated in HopZ1a-triggered immunity. Importantly, ZED1 mutants that restore degenerate kinase motifs can bridge interactions between PBLs and ZAR1 (independently of HopZ1a) and trigger immunity in planta. Our results suggest that equilibria between active and inactive kinase domain conformations regulate ZED1-PBL interactions and formation of ternary complexes with ZAR1. Improved models describing molecular interactions between immunity determinants, effectors and effector targets will inform efforts to exploit natural diversity for development of crops with enhanced disease resistance.
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Affiliation(s)
- D. Patrick Bastedo
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Madiha Khan
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Alexandre Martel
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Derek Seto
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Inga Kireeva
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - Jianfeng Zhang
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Wardah Masud
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - David Millar
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Jee Yeon Lee
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - Amy Huei-Yi Lee
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Pharmaceutical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yunchen Gong
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - André Santos-Severino
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - David S. Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
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27
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Liu C, Cui D, Zhao J, Liu N, Wang B, Liu J, Xu E, Hu Z, Ren D, Tang D, Hu Y. Two Arabidopsis Receptor-like Cytoplasmic Kinases SZE1 and SZE2 Associate with the ZAR1-ZED1 Complex and Are Required for Effector-Triggered Immunity. MOLECULAR PLANT 2019; 12:967-983. [PMID: 30947022 DOI: 10.1016/j.molp.2019.03.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 03/10/2019] [Accepted: 03/22/2019] [Indexed: 05/21/2023]
Abstract
Plants utilize intracellular nucleotide-binding leucine-rich repeat domain-containing receptors (NLRs) to recognize pathogen effectors and induce a robust defense response named effector-triggered immunity (ETI). The Arabidopsis NLR protein HOPZ-ACTIVATED RESISTANCE 1 (ZAR1) forms a precomplex with HOPZ-ETI-DEFICIENT 1 (ZED1), a receptor-like cytoplasmic kinase (RLCK) XII-2 subfamily member, to recognize the Pseudomonas syringae effector HopZ1a. We previously described a dominant mutant of Arabidopsis ZED1, zed1-D, which displays temperature-sensitive autoimmunity in a ZAR1-dependent manner. Here, we report that the RLCKs SUPPRESSOR OF ZED1-D1 (SZE1) and SZE2 associate with the ZAR1-ZED1 complex and are required for the ZED1-D-activated autoimmune response and HopZ1a-triggered immunity. We show that SZE1 but not SZE2 has autophosphorylation activity, and that the N-terminal myristoylation of both SZE1 and SZE2 is critical for their plasma membrane localization and ZED1-D-activated autoimmunity. Furthermore, we demonstrate that SZE1 and SZE2 both interact with ZAR1 to form a functional complex and are required for resistance against P. syringae pv. tomato DC3000 expressing HopZ1a. We also provide evidence that SZE1 and SZE2 interact with HopZ1a and function together with ZED1 to change the intramolecular interactions of ZAR1, leading to its activation. Taken together, our results reveal SZE1 and SZE2 as critical signaling components of HopZ1a-triggered immunity.
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Affiliation(s)
- Cheng Liu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dayong Cui
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; School of Life Sciences, Qilu Normal University, Jinan 250200, China
| | - Jingbo Zhao
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Na Liu
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Bo Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jing Liu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Enjun Xu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Zhubing Hu
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology, Henan University, Kaifeng 475001, China
| | - Dongtao Ren
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Dingzhong Tang
- Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, Plant Immunity Center, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yuxin Hu
- Key Laboratory of Plant Molecular Physiology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; National Center for Plant Gene Research, Beijing 100093, China.
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28
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Identifying Pseudomonas syringae Type III Secreted Effector Function via a Yeast Genomic Screen. G3-GENES GENOMES GENETICS 2019; 9:535-547. [PMID: 30573466 PMCID: PMC6385969 DOI: 10.1534/g3.118.200877] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Gram-negative bacterial pathogens inject type III secreted effectors (T3SEs) directly into host cells to promote pathogen fitness by manipulating host cellular processes. Despite their crucial role in promoting virulence, relatively few T3SEs have well-characterized enzymatic activities or host targets. This is in part due to functional redundancy within pathogen T3SE repertoires as well as the promiscuity of individual T3SEs that can have multiple host targets. To overcome these challenges, we generated and characterized a collection of yeast strains stably expressing 75 T3SE constructs from the plant pathogen Pseudomonas syringae. This collection is devised to facilitate heterologous genetic screens in yeast, a non-host organism, to identify T3SEs that target conserved eukaryotic processes. Among 75 T3SEs tested, we identified 16 that inhibited yeast growth on rich media and eight that inhibited growth on stress-inducing media. We utilized Pathogenic Genetic Array (PGA) screens to identify potential host targets of P. syringae T3SEs. We focused on the acetyltransferase, HopZ1a, which interacts with plant tubulin and alters microtubule networks. To uncover putative HopZ1a host targets, we identified yeast genes with genetic interaction profiles most similar (i.e., congruent) to the PGA profile of HopZ1a and performed a functional enrichment analysis of these HopZ1a-congruent genes. We compared the congruence analyses above to previously described HopZ physical interaction datasets and identified kinesins as potential HopZ1a targets. Finally, we demonstrated that HopZ1a can target kinesins by acetylating the plant kinesins HINKEL and MKRP1, illustrating the utility of our T3SE-expressing yeast library to characterize T3SE functions.
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29
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Hamasaki H, Kurihara Y, Kuromori T, Kusano H, Nagata N, Yamamoto YY, Shimada H, Matsui M. SnRK1 Kinase and the NAC Transcription Factor SOG1 Are Components of a Novel Signaling Pathway Mediating the Low Energy Response Triggered by ATP Depletion. FRONTIERS IN PLANT SCIENCE 2019; 10:503. [PMID: 31134102 PMCID: PMC6523062 DOI: 10.3389/fpls.2019.00503] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 04/01/2019] [Indexed: 05/19/2023]
Abstract
Plant growth is strictly controlled by cell division, elongation, and differentiation for which adequate supplies of intracellular ATP are required. However, it is unclear how changes in the amount of intracellular ATP affect cell division and growth. To reveal the specific pathway dependent on ATP concentration, we performed analyses on the Arabidopsis mitochondria mutation sd3. The mutant is tiny, a result of a low amount of ATP caused by the disruption of Tim21, a subunit of the TIM23 protein complex localized in the inner membrane of the mitochondria. Loss of function of suppressor of gamma response 1 (SOG1) also restored the dwarf phenotype of wild type treated with antimycin A, a blocker of ATP synthesis in mitochondria. The sd3 phenotype is partially restored by the introduction of sog1, suppressor of gamma response 1, and kin10/kin11, subunits of Snf1-related kinase 1 (SnRK1). Additionally, SOG1 interacted with SnRK1, and was modified by phosphorylation in planta only after treatment with antimycin A. Transcripts of several negative regulators of the endocycle were up-regulated in the sd3 mutant, and this high expression was not observed in sd3sog1 and sd3kin11. We suggest that there is a novel regulatory mechanism for the control of plant cell cycle involving SnRK1 and SOG1, which is induced by low amounts of intracellular ATP, and controls plant development.
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Affiliation(s)
- Hidefumi Hamasaki
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Department of Biological Science and Technology, Tokyo University of Science, Tokyo, Japan
- Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Yukio Kurihara
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Takashi Kuromori
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
| | - Hiroaki Kusano
- Department of Biological Science and Technology, Tokyo University of Science, Tokyo, Japan
| | - Noriko Nagata
- Department of Chemical and Biological Sciences, Faculty of Science, Japan Woman’s University, Tokyo, Japan
| | - Yoshiharu Y. Yamamoto
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- Applied Biological Sciences, Gifu University, Gifu, Japan
| | - Hiroaki Shimada
- Department of Biological Science and Technology, Tokyo University of Science, Tokyo, Japan
| | - Minami Matsui
- Synthetic Genomics Research Group, RIKEN Center for Sustainable Resource Science, Yokohama, Japan
- *Correspondence: Minami Matsui,
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Hassan JA, de la Torre‐Roche R, White JC, Lewis JD. Soil mixture composition alters Arabidopsis susceptibility to Pseudomonas syringae infection. PLANT DIRECT 2018; 2:e00044. [PMID: 31245710 PMCID: PMC6508533 DOI: 10.1002/pld3.44] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/08/2018] [Accepted: 01/23/2018] [Indexed: 05/25/2023]
Abstract
Pseudomonas syringae is a gram-negative bacterial pathogen that causes disease on more than 100 different plant species, including the model plant Arabidopsis thaliana. Dissection of the Arabidopsis thaliana-Pseudomonas syringae pathosystem has identified many factors that contribute to successful infection or immunity, including the genetics of the host, the genetics of the pathogen, and the environment. Environmental factors that contribute to a successful interaction can include temperature, light, and the circadian clock, as well as the soil environment. As silicon-amended Resilience soil is advertised to enhance plant health, we sought to examine the extent to which this soil might affect the behavior of the A. thaliana-P. syringae model pathosystem and to characterize the mechanisms through which these effects may occur. We found that plants grown in Si-amended Resilience soil displayed enhanced resistance to bacteria compared to plants grown in non-Si-amended Sunshine soil, and salicylic acid biosynthesis and signaling were not required for resistance. Although silicon has been shown to contribute to broad-spectrum resistance, our data indicate that silicon is not the direct cause of enhanced resistance and that the Si-amended Resilience soil has additional properties that modulate plant resistance. Our work demonstrates the importance of environmental factors, such as soil in modulating interactions between the plant and foliar pathogens, and highlights the significance of careful annotation of the environmental conditions under which plant-pathogen interactions are studied.
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Affiliation(s)
- Jana A. Hassan
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
| | | | - Jason C. White
- Department of Analytical ChemistryThe Connecticut Agricultural Experiment StationNew HavenCTUSA
| | - Jennifer D. Lewis
- Department of Plant and Microbial BiologyUniversity of California BerkeleyBerkeleyCAUSA
- Plant Gene Expression CenterUnited States Department of AgricultureAlbanyCAUSA
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Rufián JS, Lucía A, Rueda-Blanco J, Zumaquero A, Guevara CM, Ortiz-Martín I, Ruiz-Aldea G, Macho AP, Beuzón CR, Ruiz-Albert J. Suppression of HopZ Effector-Triggered Plant Immunity in a Natural Pathosystem. FRONTIERS IN PLANT SCIENCE 2018; 9:977. [PMID: 30154802 PMCID: PMC6103241 DOI: 10.3389/fpls.2018.00977] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 06/15/2018] [Indexed: 05/13/2023]
Abstract
Many type III-secreted effectors suppress plant defenses, but can also activate effector-triggered immunity (ETI) in resistant backgrounds. ETI suppression has been shown for a number of type III effectors (T3Es) and ETI-suppressing effectors are considered part of the arms race model for the co-evolution of bacterial virulence and plant defense. However, ETI suppression activities have been shown mostly between effectors not being naturally expressed within the same strain. Furthermore, evolution of effector families is rarely explained taking into account that selective pressure against ETI-triggering effectors may be compensated by ETI-suppressing effector(s) translocated by the same strain. The HopZ effector family is one of the most diverse, displaying a high rate of loss and gain of alleles, which reflects opposing selective pressures. HopZ effectors trigger defense responses in a variety of crops and some have been shown to suppress different plant defenses. Mutational changes in the sequence of ETI-triggering effectors have been proposed to result in the avoidance of detection by their respective hosts, in a process called pathoadaptation. We analyze how deleting or overexpressing HopZ1a and HopZ3 affects virulence of HopZ-encoding and non-encoding strains. We find that both effectors trigger immunity in their plant hosts only when delivered from heterologous strains, while immunity is suppressed when delivered from their native strains. We carried out screens aimed at identifying the determinant(s) suppressing HopZ1a-triggered and HopZ3-triggered immunity within their native strains, and identified several effectors displaying suppression of HopZ3-triggered immunity. We propose effector-mediated cross-suppression of ETI as an additional force driving evolution of the HopZ family.
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Affiliation(s)
- José S. Rufián
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ainhoa Lucía
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Javier Rueda-Blanco
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Adela Zumaquero
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Carlos M. Guevara
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Inmaculada Ortiz-Martín
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Gonzalo Ruiz-Aldea
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Alberto P. Macho
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Carmen R. Beuzón
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
| | - Javier Ruiz-Albert
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea, Universidad de Málaga-Consejo Superior de Investigaciones Científicas, Málaga, Spain
- *Correspondence: Javier Ruiz-Albert,
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Bürger M, Willige BC, Chory J. A hydrophobic anchor mechanism defines a deacetylase family that suppresses host response against YopJ effectors. Nat Commun 2017; 8:2201. [PMID: 29259199 PMCID: PMC5736716 DOI: 10.1038/s41467-017-02347-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 11/20/2017] [Indexed: 01/09/2023] Open
Abstract
Several Pseudomonas and Xanthomonas species are plant pathogens that infect the model organism Arabidopsis thaliana and important crops such as Brassica. Resistant plants contain the infection by rapid cell death of the infected area through the hypersensitive response (HR). A family of highly related α/β hydrolases is involved in diverse processes in all domains of life. Functional details of their catalytic machinery, however, remained unclear. We report the crystal structures of α/β hydrolases representing two different clades of the family, including the protein SOBER1, which suppresses AvrBsT-incited HR in Arabidopsis. Our results reveal a unique hydrophobic anchor mechanism that defines a previously unknown family of protein deacetylases. Furthermore, this study identifies a lid-loop as general feature for substrate turnover in acyl-protein thioesterases and the described family of deacetylases. Furthermore, we found that SOBER1's biological function is not restricted to Arabidopsis thaliana and not limited to suppress HR induced by AvrBsT.
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Affiliation(s)
- Marco Bürger
- Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Björn C Willige
- Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Joanne Chory
- Plant Biology Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA.
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA.
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Baudin M, Hassan JA, Schreiber KJ, Lewis JD. Analysis of the ZAR1 Immune Complex Reveals Determinants for Immunity and Molecular Interactions. PLANT PHYSIOLOGY 2017; 174:2038-2053. [PMID: 28652264 PMCID: PMC5543953 DOI: 10.1104/pp.17.00441] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 06/22/2017] [Indexed: 05/06/2023]
Abstract
Plants depend on innate immunity to prevent disease. Plant pathogenic bacteria, like Pseudomonas syringae and Xanthomonas campestris, use the type III secretion system as a molecular syringe to inject type III secreted effector (T3SE) proteins in plants. The primary function of most T3SEs is to suppress immunity; however, the plant can evolve nucleotide-binding domain-leucine-rich repeat domain-containing proteins to recognize specific T3SEs. The AtZAR1 NLR induces strong defense responses against P. syringae and X. campestris The P. syringae T3SE HopZ1a is an acetyltransferase that acetylates the pseudokinase AtZED1 and triggers recognition by AtZAR1. However, little is known about the molecular mechanisms that lead to AtZAR1-induced immunity in response to HopZ1a. We established a transient expression system in Nicotiana benthamiana to study detailed interactions among HopZ1a, AtZED1, and AtZAR1. We show that the AtZAR1 immune pathway is conserved in N. benthamiana and identify AtZAR1 domains, and residues in AtZAR1 and AtZED1, that are important for immunity and protein-protein interactions in planta and in yeast (Saccharomyces cerevisiae). We show that the coiled-coil domain of AtZAR1 oligomerizes, and this domain acts as a signal to induce immunity. This detailed analysis of the AtZAR1-AtZED1 protein complex provides a better understanding of the immune signaling hub controlled by AtZAR1.
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Affiliation(s)
- Maël Baudin
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California 94720
| | - Jana A Hassan
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California 94720
| | - Karl J Schreiber
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California 94720
| | - Jennifer D Lewis
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California 94720
- Plant Gene Expression Center, U.S. Department of Agriculture, Albany, California 94710
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A bacterial acetyltransferase triggers immunity in Arabidopsis thaliana independent of hypersensitive response. Sci Rep 2017; 7:3557. [PMID: 28620210 PMCID: PMC5472582 DOI: 10.1038/s41598-017-03704-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 05/08/2017] [Indexed: 12/14/2022] Open
Abstract
Type-III secreted effectors (T3Es) play critical roles during bacterial pathogenesis in plants. Plant recognition of certain T3Es can trigger defence, often accompanied by macroscopic cell death, termed the hypersensitive response (HR). Economically important species of kiwifruit are susceptible to Pseudomonas syringae pv. actinidiae (Psa), the causal agent of kiwifruit bacterial canker. Although Psa is non-pathogenic in Arabidopsis thaliana, we observed that a T3E, HopZ5 that is unique to a global outbreak clade of Psa, triggers HR and defence in Arabidopsis accession Ct-1. Ws-2 and Col-0 accessions are unable to produce an HR in response to Pseudomonas-delivered HopZ5. While Ws-2 is susceptible to virulent bacterial strain Pseudomonas syringae pv. tomato DC3000 carrying HopZ5, Col-0 is resistant despite the lack of an HR. We show that HopZ5, like other members of the YopJ superfamily of acetyltransferases that it belongs to, autoacetylates lysine residues. Through comparisons to other family members, we identified an acetyltransferase catalytic activity and demonstrate its requirement for triggering defence in Arabidopsis and Nicotiana species. Collectively, data herein indicate that HopZ5 is a plasma membrane-localized acetyltransferase with autoacetylation activity required for avirulence.
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Castañeda‐Ojeda MP, López‐Solanilla E, Ramos C. Differential modulation of plant immune responses by diverse members of the Pseudomonas savastanoi pv. savastanoi HopAF type III effector family. MOLECULAR PLANT PATHOLOGY 2017; 18:625-634. [PMID: 27116193 PMCID: PMC6638205 DOI: 10.1111/mpp.12420] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/21/2016] [Accepted: 04/22/2016] [Indexed: 05/25/2023]
Abstract
The Pseudomonas savastanoi pv. savastanoi NCPPB 3335 type III secretion system (T3SS) effector repertoire includes 33 candidates, seven of which translocate into host cells and interfere with plant defences. The present study was performed to investigate the co-existence of both plasmid- and chromosomal-encoded members of the HopAF effector family, HopAF1-1 and HopAF1-2, respectively, in the genome of NCPPB 3335. Here, we show that the HopAF1 paralogues are widely distributed in the Pseudomonas syringae complex, where HopAF1-1 is most similar to the homologues encoded by other P. syringae pathovars infecting woody hosts that belong to phylogroups 1 and 3. We show that the expression of both HopAF1-1 and HopAF-2 is transcriptionally dependent on HrpL and demonstrate their delivery into Nicotiana tabacum leaves. Although the heterologous delivery of either HopAF1-1 or HopAF1-2 significantly suppressed the production of defence-associated reactive oxygen species levels, only HopAF1-2 reduced the levels of callose deposition. Moreover, the expression of HopAF1-2 by functionally effectorless P. syringae pv. tomato DC3000D28E completely inhibited the hypersensitive response in tobacco and significantly increased the competitiveness of the strain in Nicotiana benthamiana. Despite their functional differences, subcellular localization studies reveal that green fluorescent protein (GFP) fusions to either HopAF1-1 or HopAF1-2 are targeted to the plasma membrane when they are expressed in plant cells, a process that is completely dependent on the integrity of their N-myristoylation motif. Our results further support the notion that highly similar T3SS effectors might differentially interact with diverse plant targets, even when they co-localize in the same cell compartment.
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Affiliation(s)
- M. Pilar Castañeda‐Ojeda
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Campus Teatinos s/nMálagaE‐29010Spain
| | - Emilia López‐Solanilla
- Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid‐Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Parque Científico y Tecnológico de la UPM, Campus de MontegancedoPozuelo de AlarcónMadrid28223Spain
- Departamento de BiotecnologíaEscuela Técnica Superior de Ingenieros Agrónomos, UPMAvda. Complutense S/NMadrid28040Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea ‘La Mayora’, Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Campus Teatinos s/nMálagaE‐29010Spain
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Price C, Merchant M, Jones S, Best A, Von Dwingelo J, Lawrenz MB, Alam N, Schueler-Furman O, Kwaik YA. Host FIH-Mediated Asparaginyl Hydroxylation of Translocated Legionella pneumophila Effectors. Front Cell Infect Microbiol 2017; 7:54. [PMID: 28321389 PMCID: PMC5337513 DOI: 10.3389/fcimb.2017.00054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/13/2017] [Indexed: 01/15/2023] Open
Abstract
FIH-mediated post-translational modification through asparaginyl hydroxylation of eukaryotic proteins impacts regulation of protein-protein interaction. We have identified the FIH recognition motif in 11 Legionella pneumophila translocated effectors, YopM of Yersinia, IpaH4.5 of Shigella and an ankyrin protein of Rickettsia. Mass spectrometry analyses of the AnkB and AnkH effectors of L. pneumophila confirm their asparaginyl hydroxylation. Consistent with localization of the AnkB effector to the Legionella-containing vacuole (LCV) membrane and its modification by FIH, our data show that FIH and its two interacting proteins, Mint3 and MT1-MMP are acquired by the LCV in a Dot/Icm type IV secretion-dependent manner. Chemical inhibition or RNAi-mediated knockdown of FIH promotes LCV-lysosomes fusion, diminishes decoration of the LCV with polyubiquitinated proteins, and abolishes intra-vacuolar replication of L. pneumophila. These data show acquisition of the host FIH by a pathogen-containing vacuole and that asparaginyl-hydroxylation of translocated effectors is indispensable for their function.
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Affiliation(s)
- Christopher Price
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Michael Merchant
- Department of Medicine-Renal, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Snake Jones
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Ashley Best
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Juanita Von Dwingelo
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Matthew B. Lawrenz
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
- Center for Predictive Medicine, College of Medicine, University of LouisvilleLouisville, KY, USA
| | - Nawsad Alam
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hadassah Medical School, The Hebrew University of JerusalemJerusalem, Israel
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada (IMRIC), Faculty of Medicine, Hadassah Medical School, The Hebrew University of JerusalemJerusalem, Israel
| | - Yousef A. Kwaik
- Department of Microbiology and Immunology, College of Medicine, University of LouisvilleLouisville, KY, USA
- Center for Predictive Medicine, College of Medicine, University of LouisvilleLouisville, KY, USA
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Duong S, Vonapartis E, Li CY, Patel S, Gazzarrini S. The E3 ligase ABI3-INTERACTING PROTEIN2 negatively regulates FUSCA3 and plays a role in cotyledon development in Arabidopsis thaliana. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:1555-1567. [PMID: 28369580 PMCID: PMC5441903 DOI: 10.1093/jxb/erx046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
FUSCA3 (FUS3) is a short-lived B3-domain transcription factor that regulates seed development and phase transitions in Arabidopsis thaliana. The mechanisms controlling FUS3 levels are currently poorly understood. Here we show that FUS3 interacts with the RING E3 ligase ABI3-INTERACTING PROTEIN2 (AIP2). AIP2-green fluorescent protein (GFP) is preferentially expressed in the protoderm during early embryogenesis, similarly to FUS3, suggesting that their interaction is biologically relevant. FUS3 degradation is delayed in the aip2-1 mutant and FUS3-GFP fluorescence is increased in aip2-1, but only during mid-embryogenesis, suggesting that FUS3 is negatively regulated by AIP2 at a specific time during embryogenesis. aip2-1 shows delayed flowering and therefore also functions post-embryonically to regulate developmental phase transitions. Plants overexpressing FUS3 post-embryonically in the L1 layer (ML1p:FUS3) show late flowering and other developmental phenotypes that can be rescued by ML1p:AIP2, further supporting a negative role for AIP2 in FUS3 accumulation. However, additional factors regulate FUS3 levels during embryogenesis, as ML1:AIP2 seeds do not resemble fus3-3. Lastly, targeted expression of a RING-inactive AIP2 variant to the protoderm/L1 layer causes FUS3 and ABI3 overexpression phenotypes and defects in cotyledon development. Taken together, these results indicate that AIP2 targets FUS3 for degradation and plays a role in cotyledon development and flowering time in Arabidopsis.
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Affiliation(s)
- Simon Duong
- Department of Biological Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3G5, Canada
| | - Eliana Vonapartis
- Department of Biological Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3G5, Canada
| | - Cheuk-Yan Li
- Department of Biological Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada
| | - Sajedabanu Patel
- Department of Biological Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada
| | - Sonia Gazzarrini
- Department of Biological Sciences, University of Toronto Scarborough, Toronto M1C 1A4, Canada
- Department of Cell and Systems Biology, University of Toronto, Toronto M5S 3G5, Canada
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38
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Choi S, Jayaraman J, Segonzac C, Park HJ, Park H, Han SW, Sohn KH. Pseudomonas syringae pv. actinidiae Type III Effectors Localized at Multiple Cellular Compartments Activate or Suppress Innate Immune Responses in Nicotiana benthamiana. FRONTIERS IN PLANT SCIENCE 2017; 8:2157. [PMID: 29326748 PMCID: PMC5742410 DOI: 10.3389/fpls.2017.02157] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 12/06/2017] [Indexed: 05/15/2023]
Abstract
Bacterial phytopathogen type III secreted (T3S) effectors have been strongly implicated in altering the interaction of pathogens with host plants. Therefore, it is useful to characterize the whole effector repertoire of a pathogen to understand the interplay of effectors in plants. Pseudomonas syringae pv. actinidiae is a causal agent of kiwifruit canker disease. In this study, we generated an Agrobacterium-mediated transient expression library of YFP-tagged T3S effectors from two strains of Psa, Psa-NZ V13 and Psa-NZ LV5, in order to gain insight into their mode of action in Nicotiana tabacum and N. benthamiana. Determining the subcellular localization of effectors gives an indication of the possible host targets of effectors. A confocal microscopy assay detecting YFP-tagged Psa effectors revealed that the nucleus, cytoplasm and cell periphery are major targets of Psa effectors. Agrobacterium-mediated transient expression of multiple Psa effectors induced HR-like cell death (HCD) in Nicotiana spp., suggesting that multiple Psa effectors may be recognized by Nicotiana spp.. Virus-induced gene silencing (VIGS) of several known plant immune regulators, EDS1, NDR1, or SGT1 specified the requirement of SGT1 in HCD induced by several Psa effectors in N. benthamiana. In addition, the suppression activity of Psa effectors on HCD-inducing proteins and PTI was assessed. Psa effectors showed differential suppression activities on each HCD inducer or PTI. Taken together, our Psa effector repertoire analysis highlights the great diversity of T3S effector functions in planta.
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Affiliation(s)
- Sera Choi
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Jay Jayaraman
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Cécile Segonzac
- Plant Science Department, Plant Genomics and Breeding Institute and Research Institute of Agriculture and Life Sciences, College of Agriculture and Life Sciences, Seoul National University, Seoul, South Korea
| | - Hye-Jee Park
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Hanbi Park
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Sang-Wook Han
- Department of Integrative Plant Science, Chung-Ang University, Anseong, South Korea
| | - Kee Hoon Sohn
- Bioprotection Research Centre, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang, South Korea
- *Correspondence: Kee Hoon Sohn,
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Laflamme B, Middleton M, Lo T, Desveaux D, Guttman DS. Image-Based Quantification of Plant Immunity and Disease. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:919-924. [PMID: 27996374 DOI: 10.1094/mpmi-07-16-0129-ta] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Measuring the extent and severity of disease is a critical component of plant pathology research and crop breeding. Unfortunately, existing visual scoring systems are qualitative, subjective, and the results are difficult to transfer between research groups, while existing quantitative methods can be quite laborious. Here, we present plant immunity and disease image-based quantification (PIDIQ), a quantitative, semi-automated system to rapidly and objectively measure disease symptoms in a biologically relevant context. PIDIQ applies an ImageJ-based macro to plant photos in order to distinguish healthy tissue from tissue that has yellowed due to disease. It can process a directory of images in an automated manner and report the relative ratios of healthy to diseased leaf area, thereby providing a quantitative measure of plant health that can be statistically compared with appropriate controls. We used the Arabidopsis thaliana-Pseudomonas syringae model system to show that PIDIQ is able to identify both enhanced plant health associated with effector-triggered immunity as well as elevated disease symptoms associated with effector-triggered susceptibility. Finally, we show that the quantitative results provided by PIDIQ correspond to those obtained via traditional in planta pathogen growth assays. PIDIQ provides a simple and effective means to nondestructively quantify disease from whole plants and we believe it will be equally effective for monitoring disease on excised leaves and stems.
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Affiliation(s)
- Bradley Laflamme
- 1 Department of Cell & Systems Biology, University of Toronto, Ontario, Canada; and
| | - Maggie Middleton
- 2 Centre for the Analysis of Genome Evolution & Function, University of Toronto
| | - Timothy Lo
- 1 Department of Cell & Systems Biology, University of Toronto, Ontario, Canada; and
| | - Darrell Desveaux
- 1 Department of Cell & Systems Biology, University of Toronto, Ontario, Canada; and
- 2 Centre for the Analysis of Genome Evolution & Function, University of Toronto
| | - David S Guttman
- 1 Department of Cell & Systems Biology, University of Toronto, Ontario, Canada; and
- 2 Centre for the Analysis of Genome Evolution & Function, University of Toronto
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40
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Schreiber KJ, Baudin M, Hassan JA, Lewis JD. Die another day: Molecular mechanisms of effector-triggered immunity elicited by type III secreted effector proteins. Semin Cell Dev Biol 2016; 56:124-133. [DOI: 10.1016/j.semcdb.2016.05.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/02/2016] [Indexed: 11/27/2022]
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Popa CM, Tabuchi M, Valls M. Modification of Bacterial Effector Proteins Inside Eukaryotic Host Cells. Front Cell Infect Microbiol 2016; 6:73. [PMID: 27489796 PMCID: PMC4951486 DOI: 10.3389/fcimb.2016.00073] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 06/27/2016] [Indexed: 12/16/2022] Open
Abstract
Pathogenic bacteria manipulate their hosts by delivering a number of virulence proteins -called effectors- directly into the plant or animal cells. Recent findings have shown that such effectors can suffer covalent modifications inside the eukaryotic cells. Here, we summarize the recent reports where effector modifications by the eukaryotic machinery have been described. We restrict our focus on proteins secreted by the type III or type IV systems, excluding other bacterial toxins. We describe the known examples of effectors whose enzymatic activity is triggered by interaction with plant and animal cell factors, including GTPases, E2-Ubiquitin conjugates, cyclophilin and thioredoxins. We focus on the structural interactions with these factors and their influence on effector function. We also review the described examples of host-mediated post-translational effector modifications which are required for proper subcellular location and function. These host-specific covalent modifications include phosphorylation, ubiquitination, SUMOylation, and lipidations such as prenylation, fatty acylation and phospholipid binding.
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Affiliation(s)
- Crina M Popa
- Department of Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB), Universitat de Barcelona Barcelona, Spain
| | - Mitsuaki Tabuchi
- Department of Applied Biological Science, Faculty of Agriculture, Kagawa University Kagawa, Japan
| | - Marc Valls
- Department of Genetics, Centre for Research in Agricultural Genomics (CSIC-IRTA-UAB), Universitat de Barcelona Barcelona, Spain
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42
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Washington EJ, Mukhtar MS, Finkel OM, Wan L, Banfield MJ, Kieber JJ, Dangl JL. Pseudomonas syringae type III effector HopAF1 suppresses plant immunity by targeting methionine recycling to block ethylene induction. Proc Natl Acad Sci U S A 2016; 113:E3577-86. [PMID: 27274076 PMCID: PMC4922156 DOI: 10.1073/pnas.1606322113] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
HopAF1 is a type III effector protein of unknown function encoded in the genomes of several strains of Pseudomonas syringae and other plant pathogens. Structural modeling predicted that HopAF1 is closely related to deamidase proteins. Deamidation is the irreversible substitution of an amide group with a carboxylate group. Several bacterial virulence factors are deamidases that manipulate the activity of specific host protein substrates. We identified Arabidopsis methylthioadenosine nucleosidase proteins MTN1 and MTN2 as putative targets of HopAF1 deamidation. MTNs are enzymes in the Yang cycle, which is essential for the high levels of ethylene biosynthesis in Arabidopsis We hypothesized that HopAF1 inhibits the host defense response by manipulating MTN activity and consequently ethylene levels. We determined that bacterially delivered HopAF1 inhibits ethylene biosynthesis induced by pathogen-associated molecular patterns and that Arabidopsis mtn1 mtn2 mutant plants phenocopy the effect of HopAF1. Furthermore, we identified two conserved asparagines in MTN1 and MTN2 from Arabidopsis that confer loss of function phenotypes when deamidated via site-specific mutation. These residues are potential targets of HopAF1 deamidation. HopAF1-mediated manipulation of Yang cycle MTN proteins is likely an evolutionarily conserved mechanism whereby HopAF1 orthologs from multiple plant pathogens contribute to disease in a large variety of plant hosts.
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Affiliation(s)
- Erica J Washington
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - M Shahid Mukhtar
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Omri M Finkel
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Li Wan
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Mark J Banfield
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, United Kingdom
| | - Joseph J Kieber
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Jeffery L Dangl
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599; Howard Hughes Medical Institute, University of North Carolina, Chapel Hill, NC 27599; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599; Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC 27599; Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC 27599
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43
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Lee J, Manning AJ, Wolfgeher D, Jelenska J, Cavanaugh KA, Xu H, Fernandez SM, Michelmore RW, Kron SJ, Greenberg JT. Acetylation of an NB-LRR Plant Immune-Effector Complex Suppresses Immunity. Cell Rep 2015; 13:1670-82. [PMID: 26586425 PMCID: PMC4967551 DOI: 10.1016/j.celrep.2015.10.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 09/10/2015] [Accepted: 10/09/2015] [Indexed: 12/21/2022] Open
Abstract
Modifications of plant immune complexes by secreted pathogen effectors can trigger strong immune responses mediated by the action of nucleotide binding-leucine-rich repeat immune receptors. Although some strains of the pathogen Pseudomonas syringae harbor effectors that individually can trigger immunity, the plant's response may be suppressed by other virulence factors. This work reveals a robust strategy for immune suppression mediated by HopZ3, an effector in the YopJ family of acetyltransferases. The suppressing HopZ3 effector binds to and can acetylate multiple members of the RPM1 immune complex, as well as two P. syringae effectors that together activate the RPM1 complex. These acetylations modify serine, threonine, lysine, and/or histidine residues in the targets. Through HopZ3-mediated acetylation, it is possible that the whole effector-immune complex is inactivated, leading to increased growth of the pathogen.
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Affiliation(s)
- Jiyoung Lee
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Andrew J Manning
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Donald Wolfgeher
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Joanna Jelenska
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Keri A Cavanaugh
- The Genome Center & Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Huaqin Xu
- The Genome Center & Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Sandra M Fernandez
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Richard W Michelmore
- The Genome Center & Department of Plant Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Stephen J Kron
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA
| | - Jean T Greenberg
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA.
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Rufián JS, Lucía A, Macho AP, Orozco-Navarrete B, Arroyo-Mateos M, Bejarano ER, Beuzón CR, Ruiz-Albert J. Auto-acetylation on K289 is not essential for HopZ1a-mediated plant defense suppression. Front Microbiol 2015. [PMID: 26217317 PMCID: PMC4495678 DOI: 10.3389/fmicb.2015.00684] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Pseudomonas syringae type III-secreted effector HopZ1a is a member of the HopZ/YopJ superfamily of effectors that triggers immunity in Arabidopsis. We have previously shown that HopZ1a suppresses both local [effector-triggered immunity (ETI)] and systemic immunity [systemic acquired resistance (SAR)] triggered by the heterologous effector AvrRpt2. HopZ1a has been shown to possess acetyltransferase activity, and this activity is essential to trigger immunity in Arabidopsis. HopZ1a acetyltransferase activity has been reported to require the auto-acetylation of the effector on a specific lysine (K289) residue. In this paper we analyze the relevance of autoacetylation of lysine residue 289 in HopZ1a ability to suppress plant defenses, and on the light of the results obtained, we also revise its relevance for HopZ1a avirulence activity. Our results indicate that, while the HopZ1a(K289R) mutant is impaired to some degree in its virulence and avirulence activities, is by no means phenotypically equivalent to the catalytically inactive HopZ1a(C216A), since it is still able to trigger a defense response that induces detectable macroscopic HR and effectively protects Arabidopsis from infection, reducing growth of P. syringae within the plant. We also present evidence that the HopZ1a(K289R) mutant still displays virulence activities, partially suppressing both ETI and SAR.
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Affiliation(s)
- José S Rufián
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Ainhoa Lucía
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Alberto P Macho
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Begoña Orozco-Navarrete
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Manuel Arroyo-Mateos
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Eduardo R Bejarano
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Carmen R Beuzón
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
| | - Javier Ruiz-Albert
- Departamento Biología Celular, Genética y Fisiología, Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" - Universidad de Málaga - Consejo Superior de Investigaciones Científicas Málaga, Spain
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45
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Menna A, Nguyen D, Guttman DS, Desveaux D. Elevated Temperature Differentially Influences Effector-Triggered Immunity Outputs in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2015; 6:995. [PMID: 26617631 PMCID: PMC4637416 DOI: 10.3389/fpls.2015.00995] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/30/2015] [Indexed: 05/20/2023]
Abstract
Pseudomonas syringae is a Gram-negative bacterium that infects multiple plant species by manipulating cellular processes via injection of type three secreted effectors (T3SEs) into host cells. Nucleotide-binding leucine-rich repeat (NLR) resistance (R) proteins recognize specific T3SEs and trigger a robust immune response, called effector-triggered immunity (ETI), which limits pathogen proliferation and is often associated with localized programmed cell death, known as the hypersensitive response (HR). In this study, we examine the influence of elevated temperature on two ETI outputs: HR and pathogen virulence suppression. We found that in the Arabidopsis thaliana accession Col-0, elevated temperatures suppress the HR, but have minimal influence on ETI-associated P. syringae virulence suppression, thereby uncoupling these two ETI responses. We also identify accessions of Arabidopsis that exhibit impaired P. syringae virulence suppression at elevated temperature, highlighting the natural variation that exists in coping with biotic and abiotic stresses. These results not only reinforce the influence of abiotic factors on plant immunity but also emphasize the importance of carefully documented environmental conditions in studies of plant immunity.
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Affiliation(s)
- Alexandra Menna
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Dang Nguyen
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - David S. Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada
- *Correspondence: Darrell Desveaux, ; David S. Guttman,
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, ON, Canada
- *Correspondence: Darrell Desveaux, ; David S. Guttman,
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46
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Lewis JD, Wilton M, Mott G.A, Lu W, Hassan JA, Guttman DS, Desveaux D. Immunomodulation by the Pseudomonas syringae HopZ type III effector family in Arabidopsis. PLoS One 2014; 9:e116152. [PMID: 25546415 PMCID: PMC4278861 DOI: 10.1371/journal.pone.0116152] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 12/04/2014] [Indexed: 11/19/2022] Open
Abstract
Pseudomonas syringae employs a type III secretion system to inject 20-30 different type III effector (T3SE) proteins into plant host cells. A major role of T3SEs is to suppress plant immune responses and promote bacterial infection. The YopJ/HopZ acetyltransferases are a superfamily of T3SEs found in both plant and animal pathogenic bacteria. In P. syringae, this superfamily includes the evolutionarily diverse HopZ1, HopZ2 and HopZ3 alleles. To investigate the roles of the HopZ family in immunomodulation, we generated dexamethasone-inducible T3SE transgenic lines of Arabidopsis for HopZ family members and characterized them for immune suppression phenotypes. We show that all of the HopZ family members can actively suppress various facets of Arabidopsis immunity in a catalytic residue-dependent manner. HopZ family members can differentially suppress the activation of mitogen-activated protein (MAP) kinase cascades or the production of reactive oxygen species, whereas all members can promote the growth of non-virulent P. syringae. Localization studies show that four of the HopZ family members containing predicted myristoylation sites are localized to the vicinity of the plasma membrane while HopZ3 which lacks the myristoylation site is at least partially nuclear localized, suggesting diversification of immunosuppressive mechanisms. Overall, we demonstrate that despite significant evolutionary diversification, all HopZ family members can suppress immunity in Arabidopsis.
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Affiliation(s)
- Jennifer D. Lewis
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Plant Gene Expression Center, United States Department of Agriculture, Albany, California, United States of America
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - Mike Wilton
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - G . Adam Mott
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Wenwan Lu
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Jana A. Hassan
- Department of Plant and Microbial Biology, University of California, Berkeley, California, United States of America
| | - David S. Guttman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
| | - Darrell Desveaux
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario, Canada
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47
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Hurley B, Lee D, Mott A, Wilton M, Liu J, Liu YC, Angers S, Coaker G, Guttman DS, Desveaux D. The Pseudomonas syringae type III effector HopF2 suppresses Arabidopsis stomatal immunity. PLoS One 2014; 9:e114921. [PMID: 25503437 PMCID: PMC4263708 DOI: 10.1371/journal.pone.0114921] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 11/14/2014] [Indexed: 12/22/2022] Open
Abstract
Pseudomonas syringae subverts plant immune signalling through injection of type III secreted effectors (T3SE) into host cells. The T3SE HopF2 can disable Arabidopsis immunity through Its ADP-ribosyltransferase activity. Proteomic analysis of HopF2 interacting proteins identified a protein complex containing ATPases required for regulating stomatal aperture, suggesting HopF2 may manipulate stomatal immunity. Here we report HopF2 can inhibit stomatal immunity independent of its ADP-ribosyltransferase activity. Transgenic expression of HopF2 in Arabidopsis inhibits stomatal closing in response to P. syringae and increases the virulence of surface inoculated P. syringae. Further, transgenic expression of HopF2 inhibits flg22 induced reactive oxygen species production. Intriguingly, ADP-ribosyltransferase activity is dispensable for inhibiting stomatal immunity and flg22 induced reactive oxygen species. Together, this implies HopF2 may be a bifunctional T3SE with ADP-ribosyltransferase activity required for inhibiting apoplastic immunity and an independent function required to inhibit stomatal immunity.
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Affiliation(s)
- Brenden Hurley
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada
| | - Donghyuk Lee
- Department of Plant Pathology, University of California Davis, Davis, CA, United States of America
| | - Adam Mott
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada
| | - Michael Wilton
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada
| | - Jun Liu
- Department of Plant Pathology, University of California Davis, Davis, CA, United States of America
| | - Yulu C. Liu
- Leslie Dan Faculty of Pharmacy, Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Stephane Angers
- Leslie Dan Faculty of Pharmacy, Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Gitta Coaker
- Department of Plant Pathology, University of California Davis, Davis, CA, United States of America
| | - David S. Guttman
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, 25 Willcocks St., Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
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48
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Deslandes L, Genin S. Opening the Ralstonia solanacearum type III effector tool box: insights into host cell subversion mechanisms. CURRENT OPINION IN PLANT BIOLOGY 2014; 20:110-7. [PMID: 24880553 DOI: 10.1016/j.pbi.2014.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/23/2014] [Accepted: 05/01/2014] [Indexed: 05/19/2023]
Abstract
Effectors delivered to host cells by the Type III secretion system are essential to Ralstonia solanacearum pathogenicity, as in several other plant pathogenic bacteria. The establishment of exhaustive effector repertoires in multiple R. solanacearum strains drew a first picture of the evolutionary dynamics of the pathogen effector suites. Effector repertoires are diversified, with a core of 20-30 effectors present in most of the strains and the obtention of mutants lacking one or more effector genes revealed the functional overlap among this effector network. Recent functional studies have provided insights into the ability of single effectors to manipulate the host proteasome, elicit cell death, trigger the expression of plant genes, and/or display biochemical activities on plant protein targets.
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Affiliation(s)
- Laurent Deslandes
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan F-31326, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan F-31326, France
| | - Stephane Genin
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan F-31326, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan F-31326, France.
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49
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Roux F, Noël L, Rivas S, Roby D. ZRK atypical kinases: emerging signaling components of plant immunity. THE NEW PHYTOLOGIST 2014; 203:713-716. [PMID: 24841753 DOI: 10.1111/nph.12841] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Fabrice Roux
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, F-31326, Castanet-Tolosan, France; CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, F-31326, Castanet-Tolosan, France
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50
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An immunity-triggering effector from the Barley smut fungus Ustilago hordei resides in an Ustilaginaceae-specific cluster bearing signs of transposable element-assisted evolution. PLoS Pathog 2014; 10:e1004223. [PMID: 24992661 PMCID: PMC4081816 DOI: 10.1371/journal.ppat.1004223] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 05/15/2014] [Indexed: 11/19/2022] Open
Abstract
The basidiomycete smut fungus Ustilago hordei was previously shown to comprise isolates that are avirulent on various barley host cultivars. Through genetic crosses we had revealed that a dominant avirulence locus UhAvr1 which triggers immunity in barley cultivar Hannchen harboring resistance gene Ruh1, resided within an 80-kb region. DNA sequence analysis of this genetically delimited region uncovered the presence of 7 candidate secreted effector proteins. Sequence comparison of their coding sequences among virulent and avirulent parental and field isolates could not distinguish UhAvr1 candidates. Systematic deletion and complementation analyses revealed that UhAvr1 is UHOR_10022 which codes for a small effector protein of 171 amino acids with a predicted 19 amino acid signal peptide. Virulence in the parental isolate is caused by the insertion of a fragment of 5.5 kb with similarity to a common U. hordei transposable element (TE), interrupting the promoter of UhAvr1 and thereby changing expression and hence recognition of UhAVR1p. This rearrangement is likely caused by activities of TEs and variation is seen among isolates. Using GFP-chimeric constructs we show that UhAvr1 is induced only in mated dikaryotic hyphae upon sensing and infecting barley coleoptile cells. When infecting Hannchen, UhAVR1p causes local callose deposition and the production of reactive oxygen species and necrosis indicative of the immune response. UhAvr1 does not contribute significantly to overall virulence. UhAvr1 is located in a cluster of ten effectors with several paralogs and over 50% of TEs. This cluster is syntenous with clusters in closely-related U. maydis and Sporisorium reilianum. In these corn-infecting species, these clusters harbor however more and further diversified homologous effector families but very few TEs. This increased variability may have resulted from past selection pressure by resistance genes since U. maydis is not known to trigger immunity in its corn host.
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