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Ji H, Zhou L, Yang R, Xu M, Qian H, Tong J, Sun M. Overexpression of ORP1C gene increases the rice resistance to Xanthomonas oryzae pv. oryzae through negatively regulating transcription activator-like effectors translocation. PLANT SIGNALING & BEHAVIOR 2025; 20:2441864. [PMID: 39719413 DOI: 10.1080/15592324.2024.2441864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2024] [Revised: 12/06/2024] [Accepted: 12/09/2024] [Indexed: 12/26/2024]
Abstract
Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) has shown a high incidence rate in rice fields in recent years. Rice resistance breeding is considered as the most effective method for achieving economical and sustainable management of BLB disease. The essential basis for resistance breeding is rooted in the exploration of rice resistance genes and the clarification of the molecular mechanisms that underlie Xoo resistance. In our previous research, we showed that Xanthomonas outer protein XopZ and rice oxysterol-binding related protein ORP1C collaboratively regulate the compatible interaction between Xoo strain PXO99 and Nipponbare rice, but the deeper regulatory mechanisms remain unknown. In this study, we successfully constructed ORP1C overexpression rice using the plant binary expression vector pCAMBIA1301. Through a series of virulence and effector translocation detections in Xoo-rice interactions, we revealed that overexpression of the ORP1C gene largely increases rice resistance to multiple Xoo strains from different countries and regions. Mechanistically, ORP1C plays a Xoo resistant role through negatively regulating transcription activator-like effectors (TALEs) translocation, ORP1C has become a potential candidate gene resource for disease-resistant breeding in rice. Further studies also indicated that XopZ and ORP1C collaboratively regulate the compatible interaction of PXO99-Nipponbare by modulating TALEs translocation.
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Affiliation(s)
- Hongtao Ji
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Lan Zhou
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Ruibin Yang
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Mingliang Xu
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Hengjie Qian
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Jingyi Tong
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
| | - Mengjie Sun
- Institute of Integrative Plant Biology, School of Life Sciences, Jiangsu Normal University, Xuzhou, China
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2
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Jia L, Zhu L. The Bacterial Type III Secretion System as a Broadly Applied Protein Delivery Tool in Biological Sciences. Microorganisms 2025; 13:75. [PMID: 39858842 PMCID: PMC11767303 DOI: 10.3390/microorganisms13010075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2024] [Revised: 12/22/2024] [Accepted: 01/01/2025] [Indexed: 01/27/2025] Open
Abstract
The type III secretion system (T3SS) is a nano-machine that allows Gram-negative bacteria to alter eukaryotic host biology by directly delivering effector proteins from the bacterial cytoplasm. Protein delivery based on the bacterial T3SS has been widely used in research in biology. This review explores recent advancements in the structure and function of the T3SS. We explore the molecular underpinnings of the T3SS apparatus, which spans bacterial and host cell membranes, and discuss the intricate transport mechanisms of effector proteins. Furthermore, this review emphasizes the innovative applications of the T3SS in crop biology, where it has been leveraged to study plant-pathogen interactions. By summarizing the current knowledge and recent progress, we underscore the potential of the T3SS as a powerful tool in biological sciences and their implications for future research in plant pathology and agricultural biotechnology.
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Affiliation(s)
- Liyu Jia
- College of Forestry and Grassland, Nanjing Forestry University, Nanjing 210037, China;
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
| | - Lihua Zhu
- College of Forestry and Grassland, Nanjing Forestry University, Nanjing 210037, China;
- Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China
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3
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Liu Y, Zhang H, Wang J, Gao W, Sun X, Xiong Q, Shu X, Miao Y, Shen Q, Xun W, Zhang R. Nonpathogenic Pseudomonas syringae derivatives and its metabolites trigger the plant "cry for help" response to assemble disease suppressing and growth promoting rhizomicrobiome. Nat Commun 2024; 15:1907. [PMID: 38429257 PMCID: PMC10907681 DOI: 10.1038/s41467-024-46254-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/21/2024] [Indexed: 03/03/2024] Open
Abstract
Plants are capable of assembling beneficial rhizomicrobiomes through a "cry for help" mechanism upon pathogen infestation; however, it remains unknown whether we can use nonpathogenic strains to induce plants to assemble a rhizomicrobiome against pathogen invasion. Here, we used a series of derivatives of Pseudomonas syringae pv. tomato DC3000 to elicit different levels of the immune response to Arabidopsis and revealed that two nonpathogenic DC3000 derivatives induced the beneficial soil-borne legacy, demonstrating a similar "cry for help" triggering effect as the wild-type DC3000. In addition, an increase in the abundance of Devosia in the rhizosphere induced by the decreased root exudation of myristic acid was confirmed to be responsible for growth promotion and disease suppression of the soil-borne legacy. Furthermore, the "cry for help" response could be induced by heat-killed DC3000 and flg22 and blocked by an effector triggered immunity (ETI) -eliciting derivative of DC3000. In conclusion, we demonstrate the potential of nonpathogenic bacteria and bacterial elicitors to promote the generation of disease-suppressive soils.
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Affiliation(s)
- Yunpeng Liu
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Huihui Zhang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China
- Department of Agronomy and Horticulture, Jiangsu Vocational College of Agriculture and Forestry, Zhenjiang, Jiangsu, 212400, P. R. China
| | - Jing Wang
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Wenting Gao
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Xiting Sun
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Qin Xiong
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Xia Shu
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Youzhi Miao
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Qirong Shen
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Weibing Xun
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China.
| | - Ruifu Zhang
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China.
- Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, 210095, P. R. China.
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4
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Miao P, Zhou JM, Wang W. A self-assembling split Nano luciferase-based assay for investigating Pseudomonas syringae effector secretion. STRESS BIOLOGY 2024; 4:14. [PMID: 38363371 PMCID: PMC10873255 DOI: 10.1007/s44154-024-00152-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 01/28/2024] [Indexed: 02/17/2024]
Abstract
Many Gram-negative pathogens employ the type III secretion system (T3SS) to deliver effector proteins into host cells, thereby modulating host cellular processes and suppressing host immunity to facilitate pathogenesis and colonization. In this study, we developed a straightforward, rapid, and quantitative method for detecting T3SS-mediated translocation of Pseudomonas syringae effectors using a self-assembling split Nano luciferase (Nluc)-based reporter system. It was demonstrated that this system can detect effector secretion in vitro with an exceptionally high signal-to-noise ratio and sensitivity, attributed to the strong affinity between the split domains of Nluc and the intense luminescence generated by functional Nluc. During natural infections, effectors fused to a small C-terminal fragment of Nluc were successfully translocated into plant cells and retained their virulence functions. Furthermore, upon infection of plants expressing the N-terminal fragment of Nluc with these P. syringae strains, functional Nluc proteins were spontaneously assembled and produced bright luminescence, demonstrating that this system enables the straightforward and rapid assessment of P. syringae T3SS-mediated effector translocation during natural infections. In conclusion, the self-assembling split Nluc-based reporting system developed in this study is suitable for efficient in vitro and in planta detection of effectors secreted via T3SS.
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Affiliation(s)
- Pei Miao
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- Yazhouwan National Laboratory, Sanya, 572024, China
| | - Jian-Min Zhou
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Advanced Agricultural Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing, 100049, China
- Yazhouwan National Laboratory, Sanya, 572024, China
| | - Wei Wang
- State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, 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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Lovelace AH, Dorhmi S, Hulin MT, Li Y, Mansfield JW, Ma W. Effector Identification in Plant Pathogens. PHYTOPATHOLOGY 2023; 113:637-650. [PMID: 37126080 DOI: 10.1094/phyto-09-22-0337-kd] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Effectors play a central role in determining the outcome of plant-pathogen interactions. As key virulence proteins, effectors are collectively indispensable for disease development. By understanding the virulence mechanisms of effectors, fundamental knowledge of microbial pathogenesis and disease resistance have been revealed. Effectors are also considered double-edged swords because some of them activate immunity in disease resistant plants after being recognized by specific immune receptors, which evolved to monitor pathogen presence or activity. Characterization of effector recognition by their cognate immune receptors and the downstream immune signaling pathways is instrumental in implementing resistance. Over the past decades, substantial research effort has focused on effector biology, especially concerning their interactions with virulence targets or immune receptors in plant cells. A foundation of this research is robust identification of the effector repertoire from a given pathogen, which depends heavily on bioinformatic prediction. In this review, we summarize methodologies that have been used for effector mining in various microbial pathogens which use different effector delivery mechanisms. We also discuss current limitations and provide perspectives on how recently developed analytic tools and technologies may facilitate effector identification and hence generation of a more complete vision of host-pathogen interactions. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
| | - Sara Dorhmi
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
- Department of Microbiology and Plant Pathology, University of California Riverside, CA 92521, U.S.A
| | | | - Yufei Li
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
| | - John W Mansfield
- Faculty of Natural Sciences, Imperial College London, London, SW7 2BX, U.K
| | - Wenbo Ma
- The Sainsbury Laboratory, Norwich, NR4 7UH, U.K
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6
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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: 17] [Impact Index Per Article: 5.7] [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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7
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Drehkopf S, Otten C, Büttner D. Recognition of a translocation motif in the regulator HpaA from Xanthomonas euvesicatoria is controlled by the type III secretion chaperone HpaB. FRONTIERS IN PLANT SCIENCE 2022; 13:955776. [PMID: 35968103 PMCID: PMC9366055 DOI: 10.3389/fpls.2022.955776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 07/08/2022] [Indexed: 06/15/2023]
Abstract
The Gram-negative plant-pathogenic bacterium Xanthomonas euvesicatoria is the causal agent of bacterial spot disease in pepper and tomato plants. Pathogenicity of X. euvesicatoria depends on a type III secretion (T3S) system which translocates effector proteins into plant cells and is associated with an extracellular pilus and a translocon in the plant plasma membrane. Effector protein translocation is activated by the cytoplasmic T3S chaperone HpaB which presumably targets effectors to the T3S system. We previously reported that HpaB is controlled by the translocated regulator HpaA which binds to and inactivates HpaB during the assembly of the T3S system. In the present study, we show that translocation of HpaA depends on the T3S substrate specificity switch protein HpaC and likely occurs after pilus and translocon assembly. Translocation of HpaA requires the presence of a translocation motif (TrM) in the N-terminal region. The TrM consists of an arginine-and proline-rich amino acid sequence and is also essential for the in vivo function of HpaA. Mutation of the TrM allowed the translocation of HpaA in hpaB mutant strains but not in the wild-type strain, suggesting that the recognition of the TrM depends on HpaB. Strikingly, the contribution of HpaB to the TrM-dependent translocation of HpaA was independent of the presence of the C-terminal HpaB-binding site in HpaA. We propose that HpaB generates a recognition site for the TrM at the T3S system and thus restricts the access to the secretion channel to effector proteins. Possible docking sites for HpaA at the T3S system were identified by in vivo and in vitro interaction studies and include the ATPase HrcN and components of the predicted cytoplasmic sorting platform of the T3S system. Notably, the TrM interfered with the efficient interaction of HpaA with several T3S system components, suggesting that it prevents premature binding of HpaA. Taken together, our data highlight a yet unknown contribution of the TrM and HpaB to substrate recognition and suggest that the TrM increases the binding specificity between HpaA and T3S system components.
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8
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Recent Advancements in Tracking Bacterial Effector Protein Translocation. Microorganisms 2022; 10:microorganisms10020260. [PMID: 35208715 PMCID: PMC8876096 DOI: 10.3390/microorganisms10020260] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 11/17/2022] Open
Abstract
Bacteria-host interactions are characterized by the delivery of bacterial virulence factors, i.e., effectors, into host cells where they counteract host immunity and exploit host responses allowing bacterial survival and spreading. These effectors are translocated into host cells by means of dedicated secretion systems such as the type 3 secretion system (T3SS). A comprehensive understanding of effector translocation in a spatio-temporal manner is of critical importance to gain insights into an effector’s mode of action. Various approaches have been developed to understand timing and order of effector translocation, quantities of translocated effectors and their subcellular localization upon translocation into host cells. Recently, the existing toolset has been expanded by newly developed state-of-the art methods to monitor bacterial effector translocation and dynamics. In this review, we elaborate on reported methods and discuss recent advances and shortcomings in this area of tracking bacterial effector translocation.
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Nakamura M, Kondo M, Suzuki A, Hirai H, Che FS. Novel Effector RHIFs Identified From Acidovorax avenae Strains N1141 and K1 Play Different Roles in Host and Non-host Plants. FRONTIERS IN PLANT SCIENCE 2021; 12:716738. [PMID: 34421970 PMCID: PMC8377416 DOI: 10.3389/fpls.2021.716738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 07/05/2021] [Indexed: 06/13/2023]
Abstract
Plant pathogenic bacteria inject effectors into plant cells using type III secretion systems (T3SS) to evade plant immune systems and facilitate infection. In contrast, plants have evolved defense systems called effector-triggered immunity (ETI) that can detect such effectors during co-evolution with pathogens. The rice-avirulent strain N1141 of the bacterial pathogen Acidovorax avenae causes rice ETI, including hypersensitive response (HR) cell death in a T3SS-dependent manner, suggesting that strain N1141 expresses an ETI-inducing effector. By screening 6,200 transposon-tagged N1141 mutants based on their ability to induce HR cell death, we identified 17 mutants lacking this ability. Sequence analysis and T3SS-mediated intracellular transport showed that a protein called rice HR cell death inducing factor (RHIF) is a candidate effector protein that causes HR cell death in rice. RHIF-disrupted N1141 lacks the ability to induce HR cell death, whereas RHIF expression in this mutant complemented this ability. In contrast, RHIF from rice-virulent strain K1 functions as an ETI inducer in the non-host plant finger millet. Furthermore, inoculation of rice and finger millet with either RHIF-deficient N1141 or K1 strains showed that a deficiency of RHIF genes in both strains results in decreased infectivity toward each the host plants. Collectively, novel effector RHIFs identified from A. avenae strains N1141 and K1 function in establishing infection in host plants and in ETI induction in non-host plants.
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Affiliation(s)
- Minami Nakamura
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Machiko Kondo
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Aika Suzuki
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Hiroyuki Hirai
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Fang-Sik Che
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
- Genome Editing Research Institute, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
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Yuan X, Hulin MT, Sundin GW. Effectors, chaperones, and harpins of the Type III secretion system in the fire blight pathogen Erwinia amylovora: a review. JOURNAL OF PLANT PATHOLOGY 2021; 103:25-39. [PMID: 0 DOI: 10.1007/s42161-020-00623-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/23/2020] [Indexed: 05/20/2023]
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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: 320] [Impact Index Per Article: 80.0] [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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12
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Liu J, Yu M, Ge Y, Tian Y, Hu B, Zhao Y. The RsmA RNA-Binding Proteins in Pseudomonas syringae Exhibit Distinct and Overlapping Roles in Modulating Virulence and Survival Under Different Nutritional Conditions. FRONTIERS IN PLANT SCIENCE 2021; 12:637595. [PMID: 33719314 PMCID: PMC7952654 DOI: 10.3389/fpls.2021.637595] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
The post-transcriptional regulator RsmA globally controls gene expression in bacteria. Previous studies showed that RsmA2 and RsmA3 played critical roles in regulating type III secretion system (T3SS), motility, syringafactin, and alginate productions in Pseudomonas syringae pv. tomato strain DC3000 (PstDC3000). In this study, we investigated global gene expression profiles of the wild-type PstDC3000, the rsmA3 mutant, and the rsmA2/A3 double mutant in the hrp-inducing minimum medium (HMM) and King's B (KB) medium. By comparing the rsmA2/A3 and rsmA3 mutants to PstDC3000, a total of 1358 and 1074 differentially expressed genes (DEGs) in HMM, and 870 and 1463 DEGs in KB were uncovered, respectively. When comparing the rsmA2/A3 mutant with the rsmA3 mutant, 277 and 741 DEGs in HMM and KB, respectively, were revealed. Transcriptomic analysis revealed that the rsmY, rsmZ, and rsmX1-5 non-coding small RNAs (ncsRNAs) were positively affected by RsmA2 and RsmA3, while RsmA3 positively regulates the expression of the rsmA2 gene and negatively regulates both rsmA1 and rsmA5 gene expression. Comparative transcriptomic analysis showed that RsmA2 and RsmA3 synergistically influenced the expression of genes involved in T3SS and alginate biosynthesis in HMM and chemotaxis in KB. RsmA2 and RsmA3 inversely affected genes involved in syringafactin production in HMM and ribosomal protein biosynthesis in KB. In addition, RsmA2 played a major role in influencing genes involved in sarcosine and thiamine biosynthesis in HMM and in mannitol and phosphate metabolism in KB. On the other hand, genes involved in fatty acid metabolism, cellulose biosynthesis, signal transduction, and stress responses were mainly impacted by RsmA3 in both HMM and KB; whereas RsmA3 played a major role in controlling genes involved in c-di-GMP, phosphate metabolism, chemotaxis, and capsular polysaccharide in HMM. Furthermore, regulation of syringafactin production and oxidative stress by RsmA2 and RsmA3 was experimentally verified. Our results suggested the potential interplay among the RsmA proteins, which exhibit distinct and overlapping roles in modulating virulence and survival in P. syringae under different nutritional conditions.
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Affiliation(s)
- Jun Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yixin Ge
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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Kawaguchi T, Nakamura M, Hirai H, Furukawa T, Kondo M, Che FS. AKSF1 Isolated From the Rice-Virulent Strain Acidovorax avenae K1 Is a Novel Effector That Suppresses PAMP-Triggered Immunity in Rice. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2021; 34:186-197. [PMID: 33135963 DOI: 10.1094/mpmi-10-20-0271-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Microbial pathogens deliver effectors into plant cells to suppress plant immune responses and modulate host metabolism in order to support infection processes. We sought to determine if the Acidovorax avenae rice-virulent K1 strain can suppress pathogen-associated molecular pattern-triggered immunity (PTI) induced by flagellin isolated from the rice-avirulent N1141 strain. The flagellin-triggered PTI, including H2O2 generation, callose deposition, and expression of several immune-related genes were strongly suppressed in K1 preinoculated cultured rice cells in a type III secretion system (T3SS)-dependent manner. By screening 4,562 transposon-tagged mutants based on their suppression ability, we found that 156 transposon-tagged K1 mutants lost the ability to suppress PTI induction. Mutant sequence analysis, comprehensive expression analysis using RNA sequencing, and the prediction of secretion through T3SS showed that a protein named A. avenae K1 suppression factor 1 (AKSF1) suppresses flagellin-triggered PTI in rice. Translocation of AKSF1 protein into rice cells is dependent on the T3SS during infection, an AKSF1-disruption mutant lost the ability to suppress PTI responses, and expression of AKSF1 in the AKSF1-disruption mutant complemented the suppression activity. When AKSF1-disruption mutants were inoculated into the host rice plant, reduction of the disease symptoms and suppression of bacterial growth were observed. Taken together, our results demonstrate that AKSF1 is a novel effector that can suppress the PTI in a host rice plant.[Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. 2021.
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Affiliation(s)
- Takemasa Kawaguchi
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Minami Nakamura
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Hiroyuki Hirai
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Takehito Furukawa
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Machiko Kondo
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
| | - Fang-Sik Che
- Department of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
- Graduate School of Biosciences, Nagahama Institute of Bio-Science and Technology, 1266, Tamura, Nagahama, Shiga 526-0829, Japan
- Genome Editing Research Institute, Nagahama Institute of Bio-Science and Technology, 1281-8, Tamura, Nagahama, Shiga 526-0829, Japan
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14
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Gan YL, Yang LY, Yang LC, Li WL, Liang XL, Jiang W, Jiang GF, Hang XH, Yang M, Tang JL, Jiang BL. The C-terminal domain of the type III secretion chaperone HpaB contributes to dissociation of chaperone-effector complex in Xanthomonas campestris pv. campestris. PLoS One 2021; 16:e0246033. [PMID: 33507993 PMCID: PMC7842900 DOI: 10.1371/journal.pone.0246033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/12/2021] [Indexed: 12/01/2022] Open
Abstract
Many animal and plant pathogenic bacteria employ a type three secretion system (T3SS) to deliver type three effector proteins (T3Es) into host cells. Efficient secretion of many T3Es in the plant pathogen Xanthomonas campestris pv. campestris (Xcc) relies on the global chaperone HpaB. However, how the domain of HpaB itself affects effector translocation/secretion is poorly understood. Here, we used genetic and biochemical approaches to identify a novel domain at the C-terminal end of HpaB (amino acid residues 137-160) that contributes to virulence and hypersensitive response (HR). Both in vitro secretion assay and in planta translocation assay showed that the secretion and translocation of T3E proteins depend on the C-terminal region of HpaB. Deletion of the C-terminal region of HpaB did not affect binding to T3Es, self-association or interaction with T3SS components. However, the deletion of C-terminal region sharply reduced the mounts of free T3Es liberated from the complex of HpaB with the T3Es, a reaction catalyzed in an ATP-dependent manner by the T3SS-associated ATPase HrcN. Our findings demonstrate the C-terminal domain of HpaB contributes to disassembly of chaperone-effector complex and reveal a potential molecular mechanism underpinning the involvement of HpaB in secretion of T3Es in Xcc.
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Affiliation(s)
- Yong-Liang Gan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Li-Yan Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Li-Chao Yang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Wan-Lian Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Xue-Lian Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Wei Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | | | - Xiao-Hong Hang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Mei Yang
- School of Chemistry and Chemical Engineering, Guangxi University, Nanning, China
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
| | - Bo-Le Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, China
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Wang Y, Wang C, Rajaofera MJN, Zhu L, Xu X, Liu W, Zheng F, Miao W. WY195, a New Inducible Promoter From the Rubber Powdery Mildew Pathogen, Can Be Used as an Excellent Tool for Genetic Engineering. Front Microbiol 2020; 11:610252. [PMID: 33424812 PMCID: PMC7793764 DOI: 10.3389/fmicb.2020.610252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 11/24/2020] [Indexed: 11/13/2022] Open
Abstract
Until now, there are few studies and reports on the use of endogenous promoters of obligate biotrophic fungi. The WY195 promoter in the genome of Oidium heveae, the rubber powdery mildew pathogen, was predicted using PromoterScan and its promoter function was verified by the transient expression of the β-glucuronidase (GUS) gene. WY195 drove high levels of GUS expression in dicotyledons and monocotyledons. qRT-PCR indicated that GUS expression regulated by the WY195 promoter was 17.54-fold greater than that obtained using the CaMV 35S promoter in dicotyledons (Nicotiana tabacum), and 5.09-fold greater than that obtained using the ACT1 promoter in monocotyledons (Oryza sativa). Furthermore, WY195-regulated GUS gene expression was induced under high-temperature and drought conditions. Soluble proteins extracted from WY195-hpaXm transgenic tobacco was bioactive. Defensive micro-HR induced by the transgene expression of hpaXm was observed on transgenic tobacco leaves. Disease resistance bioassays showed that WY195-hpaXm transgenic tobacco enhanced the resistance to tobacco mosaic virus (TMV). WY195 has great potential for development as a new tool for genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms and the pathogenic mechanisms of O. heveae.
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Affiliation(s)
- Yi Wang
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
- Hainan Academy of Ocean and Fisheries Sciences, Haikou, China
| | - Chen Wang
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Mamy Jayne Nelly Rajaofera
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Li Zhu
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Xinze Xu
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Wenbo Liu
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Fucong Zheng
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
| | - Weiguo Miao
- Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, Haikou, China
- College of Plant Protection, Hainan University, Haikou, China
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16
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A TAL effector-like protein of an endofungal bacterium increases the stress tolerance and alters the transcriptome of the host. Proc Natl Acad Sci U S A 2020; 117:17122-17129. [PMID: 32632014 PMCID: PMC7382252 DOI: 10.1073/pnas.2003857117] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Endosymbiotic bacteria are found in diverse fungi, but little is known about how they communicate with their hosts. Some plant pathogenic bacteria use type III-translocated TAL effectors to control host transcription, and TAL-like proteins are encoded in genomes of the fungal endosymbiotic bacterium Mycetohabitans rhizoxinica. In this paper, we present evidence that these proteins are, like TAL effectors, type III-secreted, nuclear-localizing effectors that perturb host transcription and show that one enhances tolerance of the fungal host to cell membrane stress. Our characterization of an effector in a bacterial–fungal symbiosis opens a new door to molecular understanding of these interkingdom partnerships. Our findings also provide insight into the functional diversity and evolution of the TAL effector protein family. Symbioses of bacteria with fungi have only recently been described and are poorly understood. In the symbiosis of Mycetohabitans (formerly Burkholderia) rhizoxinica with the fungus Rhizopus microsporus, bacterial type III (T3) secretion is known to be essential. Proteins resembling T3-secreted transcription activator-like (TAL) effectors of plant pathogenic bacteria are encoded in the three sequenced Mycetohabitans spp. genomes. TAL effectors nuclear-localize in plants, where they bind and activate genes important in disease. The Burkholderia TAL-like (Btl) proteins bind DNA but lack the N- and C-terminal regions, in which TAL effectors harbor their T3 and nuclear localization signals, and activation domain. We characterized a Btl protein, Btl19-13, and found that, despite the structural differences, it can be T3-secreted and can nuclear-localize. A btl19-13 gene knockout did not prevent the bacterium from infecting the fungus, but the fungus became less tolerant to cell membrane stress. Btl19-13 did not alter transcription in a plant-based reporter assay, but 15 R. microsporus genes were differentially expressed in comparisons both of the fungus infected with the wild-type bacterium vs. the mutant and with the mutant vs. a complemented strain. Southern blotting revealed btl genes in 14 diverse Mycetohabitans isolates. However, banding patterns and available sequences suggest variation, and the btl19-13 phenotype could not be rescued by a btl gene from a different strain. Our findings support the conclusion that Btl proteins are effectors that act on host DNA and play important but varied or possibly host genotype-specific roles in the M. rhizoxinica–R. microsporus symbiosis.
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17
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Liu J, Yu M, Chatnaparat T, Lee JH, Tian Y, Hu B, Zhao Y. Comparative transcriptomic analysis of global gene expression mediated by (p) ppGpp reveals common regulatory networks in Pseudomonas syringae. BMC Genomics 2020; 21:296. [PMID: 32272893 PMCID: PMC7146990 DOI: 10.1186/s12864-020-6701-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/25/2020] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Pseudomonas syringae is an important plant pathogen, which could adapt many different environmental conditions. Under the nutrient-limited and other stress conditions, P. syringae produces nucleotide signal molecules, i.e., guanosine tetra/pentaphosphate ((p)ppGpp), to globally regulate gene expression. Previous studies showed that (p) ppGpp played an important role in regulating virulence factors in P. syringae pv. tomato DC3000 (PstDC3000) and P. syringae pv. syringae B728a (PssB728a). Here we present a comparative transcriptomic analysis to uncover the overall effects of (p)ppGpp-mediated stringent response in P. syringae. RESULTS In this study, we investigated global gene expression profiles of PstDC3000 and PssB728a and their corresponding (p)ppGpp0 mutants in hrp-inducing minimal medium (HMM) using RNA-seq. A total of 1886 and 1562 differentially expressed genes (DEGs) were uncovered between the (p)ppGpp0 mutants and the wild-type in PstDC3000 and PssB728a, respectively. Comparative transcriptomics identified 1613 common DEGs, as well as 444 and 293 unique DEGs in PstDC3000 and PssB728a, respectively. Functional cluster analysis revealed that (p) ppGpp positively regulated a variety of virulence-associated genes, including type III secretion system (T3SS), type VI secretion system (T6SS), cell motility, cell division, and alginate biosynthesis, while negatively regulated multiple basic physiological processes, including DNA replication, RNA processes, nucleotide biosynthesis, fatty acid metabolism, ribosome protein biosynthesis, and amino acid metabolism in both PstDC3000 and PssB728a. Furthermore, (p) ppGpp had divergent effects on other processes in PstDC3000 and PssB728a, including phytotoxin, nitrogen regulation and general secretion pathway (GSP). CONCLUSION In this study, comparative transcriptomic analysis reveals common regulatory networks in both PstDC3000 and PssB728a mediated by (p) ppGpp in HMM. In both P. syringae systems, (p) ppGpp re-allocate cellular resources by suppressing multiple basic physiological activities and enhancing virulence gene expression, suggesting a balance between growth, survival and virulence. Our research is important in that due to similar global gene expression mediated by (p) ppGpp in both PstDC3000 and PssB728a, it is reasonable to propose that (p) ppGpp could be used as a target to develop novel control measures to fight against important plant bacterial diseases.
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Affiliation(s)
- Jun Liu
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China.,Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Tiyakhon Chatnaparat
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Yanli Tian
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Baishi Hu
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China.
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA.
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18
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Collmer A. James Robert Alfano, A Giant in Phytopathogenic Bacteria Effector Biology. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2020; 33:377-381. [PMID: 31990622 DOI: 10.1094/mpmi-12-19-0354-cr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The worldwide molecular plant-microbe interactions research community was significantly diminished in November 2019 by the death of James "Jim" Robert Alfano at age 56. Jim was a giant in our field, who gained key insights into plant pathogenesis using the model bacterial pathogen Pseudomonas syringae. As a mentor, collaborator, and, above all, a friend, I know Jim's many dimensions and accomplishments and, sadly, the depth of loss being felt by the many people around the world who were touched by him. In tracing the path of Jim's career, I will emphasize the historical context and impact of his advances and, finally, the essence of the person we will so miss.
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Affiliation(s)
- Alan Collmer
- School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A
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19
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Lomovatskaya LA, Romanenko AS. Secretion Systems of Bacterial Phytopathogens and Mutualists (Review). APPL BIOCHEM MICRO+ 2020. [DOI: 10.1134/s0003683820020106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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O’Malley MR, Chien C, Peck SC, Lin N, Anderson JC. A revised model for the role of GacS/GacA in regulating type III secretion by Pseudomonas syringae pv. tomato DC3000. MOLECULAR PLANT PATHOLOGY 2020; 21:139-144. [PMID: 31588661 PMCID: PMC6913209 DOI: 10.1111/mpp.12876] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
GacS/GacA is a conserved two-component system that functions as a master regulator of virulence-associated traits in many bacterial pathogens, including Pseudomonas spp., that collectively infect both plant and animal hosts. Among many GacS/GacA-regulated traits, type III secretion of effector proteins into host cells plays a critical role in bacterial virulence. In the opportunistic plant and animal pathogen Pseudomonas aeruginosa, GacS/GacA negatively regulates the expression of type III secretion system (T3SS)-encoding genes. However, in the plant pathogenic bacterium Pseudomonas syringae, strain-to-strain variation exists in the requirement of GacS/GacA for T3SS deployment, and this variability has limited the development of predictive models of how GacS/GacA functions in this species. In this work we re-evaluated the function of GacA in P. syringae pv. tomato DC3000. Contrary to previous reports, we discovered that GacA negatively regulates the expression of T3SS genes in DC3000, and that GacA is not required for DC3000 virulence inside Arabidopsis leaf tissue. However, our results show that GacA is required for full virulence of leaf surface-inoculated bacteria. These data significantly revise current understanding of GacS/GacA in regulating P. syringae virulence.
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Affiliation(s)
- Megan R. O’Malley
- Department of Botany and Plant PathologyOregon State UniversityCorvallisORUSA
| | - Ching‐Fang Chien
- Department of Agricultural ChemistryNational Taiwan UniversityTaipeiTaiwanR.O.C.
- Institute of Plant and Microbial BiologyAcademia SinicaTaipeiTaiwanR.O.C.
| | - Scott C. Peck
- Department of BiochemistryUniversity of MissouriColumbiaMOUSA
- Christopher S Bond Life Sciences CenterUniversity of MissouriColumbiaMOUSA
- Interdisciplinary Plant GroupUniversity of MissouriColumbiaMOUSA
| | - Nai‐Chun Lin
- Department of Agricultural ChemistryNational Taiwan UniversityTaipeiTaiwanR.O.C.
| | - Jeffrey C. Anderson
- Department of Botany and Plant PathologyOregon State UniversityCorvallisORUSA
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Li Z, Liu H, Ding Z, Yan J, Yu H, Pan R, Hu J, Guan Y, Hua J. Low Temperature Enhances Plant Immunity via Salicylic Acid Pathway Genes That Are Repressed by Ethylene. PLANT PHYSIOLOGY 2020; 182:626-639. [PMID: 31694900 PMCID: PMC6945861 DOI: 10.1104/pp.19.01130] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/28/2019] [Indexed: 05/14/2023]
Abstract
Temperature has a large impact on plant immune responses. Earlier studies identified intracellular immune receptor nucleotide-binding leucine-rich repeat (NLR) genes and salicylic acid (SA) as targets of high-temperature inhibition of plant immunity. Here, we report that moderately low temperature enhances immunity to the bacterial pathogen Pseudomonas syringae in Arabidopsis (Arabidopsis thaliana). This enhancement is dependent on SA signaling and is accompanied by up-regulation of multiple SA biosynthesis and signaling genes at lower temperature. SA signaling is repressed by jasmonic acid and ethylene at both normal and low temperatures. The inhibition of SA biosynthesis by ethylene, while mainly through ISOCHORISMATE SYNTHASE1/SALICYLIC ACID-INDUCTION DEFICIENT2 (ICS1/SID2) at normal temperature, is through ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5)/SID1, ICS2, and ICS1/SID2 at lower temperature. The repression by ethylene is mediated by a direct regulation of the ethylene response transcription factor ETHYLENE INSENSITIVE3 (EIN3) on multiple SA biosynthesis and signaling genes. Thus, low temperature enhances the SA pathway to promote immunity and at the same time uses ethylene to repress multiple SA regulators to achieve fine-tuned immune responses.
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Affiliation(s)
- Zhan Li
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
- School of Integrative Plant Science, Plant Biology Section, Cornell University, Ithaca, New York 14853
| | - Huimin Liu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Zehong Ding
- Key Laboratory of Biology and Genetic Resources of Tropical Crops, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, China
| | - Jiapei Yan
- School of Integrative Plant Science, Plant Biology Section, Cornell University, Ithaca, New York 14853
| | - Huiyun Yu
- School of Integrative Plant Science, Plant Biology Section, Cornell University, Ithaca, New York 14853
| | - Ronghui Pan
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Jin Hu
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Yajing Guan
- Seed Science Center, Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China
| | - Jian Hua
- School of Integrative Plant Science, Plant Biology Section, Cornell University, Ithaca, New York 14853
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
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Zeng C, Zou L. An account of in silico identification tools of secreted effector proteins in bacteria and future challenges. Brief Bioinform 2019; 20:110-129. [PMID: 28981574 DOI: 10.1093/bib/bbx078] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Indexed: 01/08/2023] Open
Abstract
Bacterial pathogens secrete numerous effector proteins via six secretion systems, type I to type VI secretion systems, to adapt to new environments or to promote virulence by bacterium-host interactions. Many computational approaches have been used in the identification of effector proteins before the subsequent experimental verification because they tolerate laborious biological procedures and are genome scale, automated and highly efficient. Prevalent examples include machine learning methods and statistical techniques. In this article, we summarize the computational progress toward predicting secreted effector proteins in bacteria, with an opening of an introduction of features that are used to discriminate effectors from non-effectors. The mechanism, contribution and deficiency of previous developed detection tools are presented, which are further benchmarked based on a curated testing data set. According to the results of benchmarking, potential improvements of the prediction performance are discussed, which include (1) more informative features for discriminating the effectors from non-effectors; (2) the construction of comprehensive training data set of the machine learning algorithms; (3) the advancement of reliable prediction methods and (4) a better interpretation of the mechanisms behind the molecular processes. The future of in silico identification of bacterial secreted effectors includes both opportunities and challenges.
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Affiliation(s)
- Cong Zeng
- Bioinformatics Center, Third Military Medical University (TMMU), China
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23
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Zhang L, Paasch BC, Chen J, Day B, He SY. An important role of l-fucose biosynthesis and protein fucosylation genes in Arabidopsis immunity. THE NEW PHYTOLOGIST 2019; 222:981-994. [PMID: 30552820 DOI: 10.1111/nph.15639] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 12/01/2018] [Indexed: 05/28/2023]
Abstract
Plants mount coordinated immune responses to defend themselves against pathogens. However, the cellular components required for plant immunity are not fully understood. The jasmonate-mimicking coronatine (COR) toxin produced by Pseudomonas syringae pv. tomato (Pst) DC3000 functions to overcome plant immunity. We previously isolated eight Arabidopsis (scord) mutants that exhibit increased susceptibility to a COR-deficient mutant of PstDC3000. Among them, the scord6 mutant exhibits defects both in stomatal closure response and in restricting bacterial multiplication inside the apoplast. However, the identity of SCORD6 remained elusive. In this study, we aim to identify the SCORD6 gene. We identified SCORD6 via next-generation sequencing and found it to be MURUS1 (MUR1), which is involved in the biosynthesis of GDP-l-fucose. Discovery of SCORD6 as MUR1 led to a series of experiments that revealed a multi-faceted role of l-fucose biosynthesis in stomatal and apoplastic defenses as well as in pattern-triggered immunity and effector-triggered immunity, including glycosylation of pattern-recognition receptors. Furthermore, compromised stomatal and/or apoplastic defenses were observed in mutants of several fucosyltransferases with specific substrates (e.g. O-glycan, N-glycan or the DELLA transcriptional repressors). Collectively, these results uncover a novel and broad role of l-fucose and protein fucosylation in plant immunity.
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Affiliation(s)
- Li Zhang
- Department of Energy Plant Research Laboratory, East Lansing, MI, 48824, USA
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Bradley C Paasch
- Department of Energy Plant Research Laboratory, East Lansing, MI, 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Jin Chen
- Department of Energy Plant Research Laboratory, East Lansing, MI, 48824, USA
- Department of Computer Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - Brad Day
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory, East Lansing, MI, 48824, USA
- Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
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24
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Borah SM, Jha AN. Identification and analysis of structurally critical fragments in HopS2. BMC Bioinformatics 2019; 19:552. [PMID: 30717655 PMCID: PMC7394326 DOI: 10.1186/s12859-018-2551-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 11/30/2018] [Indexed: 12/02/2022] Open
Abstract
Background Among the diverse roles of the Type III secretion-system (T3SS), one of the notable functions is that it serves as unique nano machineries in gram-negative bacteria that facilitate the translocation of effector proteins from bacteria into their host. These effector proteins serve as potential targets to control the pathogenicity conferred to the bacteria. Despite being ideal choices to disrupt bacterial systems, it has been quite an ordeal in the recent times to experimentally reveal and establish a concrete sequence-structure-function relationship for these effector proteins. This work focuses on the disease-causing spectrum of an effector protein, HopS2 secreted by the phytopathogen Pseudomonas syringae pv. tomato DC3000. Results The study addresses the structural attributes of HopS2 via a bioinformatics approach to by-pass some of the experimental shortcomings resulting in mining some critical regions in the effector protein. We have elucidated the functionally important regions of HopS2 with the assistance of sequence and structural analyses. The sequence based data supports the presence of important regions in HopS2 that are present in the other functional parts of Hop family proteins. Furthermore, these regions have been validated by an ab-initio structure prediction of the protein followed by 100 ns long molecular dynamics (MD) simulation. The assessment of these secondary structural regions has revealed the stability and importance of these regions in the protein structure. Conclusions The analysis has provided insights on important functional regions that may be vital to the effector functioning. In dearth of ample experimental evidence, such a bioinformatics approach has helped in the revelation of a few structural regions which will aid in future experiments to attain and evaluate the structural and functional aspects of this protein family. Electronic supplementary material The online version of this article (10.1186/s12859-018-2551-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sapna M Borah
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India
| | - Anupam Nath Jha
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India.
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In Vitro and In Vivo Secretion/Translocation Assays to Identify Novel Ralstonia solanacearum Type 3 Effectors. Methods Mol Biol 2019; 1734:209-222. [PMID: 29288457 DOI: 10.1007/978-1-4939-7604-1_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Phytopathogenic bacteria have evolved multiple strategies to infect plants. Like many gram-negative bacteria, Ralstonia solanacearum, the causal agent of bacterial wilt, possesses a specialized protein secretion machinery to deliver effector proteins directly into the host cells. This type 3 secretion system (T3SS) and the bacterial proteins translocated, called type 3 effectors (T3Es), constitute the main pathogenicity determinants of the R. solanacearum species complex (RSSC). Up to 113 orthologous groups defining T3E genes have been identified among the RSSC strains sequenced to date. The increasing number of R. solanacearum genomic sequences available still expands the number of T3E candidates which require experimental validation. Here, we describe in vitro (type 3 secretion) and in vivo (type 3 translocation based on CyaA' reporter gene) methods to identify and validate type 3-dependent delivery of proteins of interest highlighted as candidate T3Es. We also present protocols to generate dedicated vectors and R. solanacearum transformation to perform these experiments.
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26
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Abstract
An accurate and complete roster of the Type III effector (T3E) proteins translocated by the P. syringae Type III secretion system (T3SS) into host cells is critical to understanding the pathogen's interactions with plants. The adenylate cyclase (Cya) reporter offers a highly sensitive and robust assay for monitoring the translocation of T3Es. T3Es are fused to the calmodulin-dependent adenylate-cyclase domain of CyaA. The T3E targets Cya for translocation through the T3SS into the host cell at which point it is activated by calmodulin and converts adenosine triphosphate into cyclic adenosine monophosphate (cAMP). The T3SS translocation-dependent increase in cAMP concentration in plant cells is then measured with an enzyme-linked immunosorbent assay kit. The Cya reporter can be used to determine whether a candidate protein is translocated by T3SS or to measure relative levels of T3SS translocation in a semiquantitative manner.
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27
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Kan J, An L, Wu Y, Long J, Song L, Fang R, Jia Y. A dual role for proline iminopeptidase in the regulation of bacterial motility and host immunity. MOLECULAR PLANT PATHOLOGY 2018; 19:2011-2024. [PMID: 29517846 PMCID: PMC6638124 DOI: 10.1111/mpp.12677] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 03/06/2018] [Accepted: 03/06/2018] [Indexed: 05/07/2023]
Abstract
During plant-pathogen interactions, pathogenic bacteria have evolved multiple strategies to cope with the sophisticated defence systems of host plants. Proline iminopeptidase (PIP) is essential to Xanthomonas campestris pv. campestris (Xcc) virulence, and is conserved in many plant-associated bacteria, but its pathogenic mechanism remains unclear. In this study, we found that disruption of pip in Xcc enhanced its flagella-mediated bacterial motility by decreasing intracellular bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) levels, whereas overexpression of pip in Xcc restricted its bacterial motility by elevating c-di-GMP levels. We also found that PIP is a type III secretion system-dependent effector capable of eliciting a hypersensitive response in non-host, but not host plants. When we transformed pip into the host plant Arabidopsis, higher bacterial titres were observed in pip-overexpressing plants relative to wild-type plants after Xcc inoculation. The repressive function of PIP on plant immunity was dependent on PIP's enzymatic activity and acted through interference with the salicylic acid (SA) biosynthetic and regulatory genes. Thus, PIP simultaneously regulates two distinct regulatory networks during plant-microbe interactions, i.e. it affects intracellular c-di-GMP levels to coordinate bacterial behaviour, such as motility, and functions as a type III effector translocated into plant cells to suppress plant immunity. Both processes provide bacteria with the regulatory potential to rapidly adapt to complex environments, to utilize limited resources for growth and survival in a cost-efficient manner and to improve the chances of bacterial survival by helping pathogens to inhabit the internal tissues of host plants.
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Affiliation(s)
- Jinhong Kan
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
- College of Life Sciences, University of the Chinese Academy of SciencesBeijing 100049China
- Present address:
Center for Crop Germplasm Resources, Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing 100081China
| | - Lin An
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
- College of Life Sciences, University of the Chinese Academy of SciencesBeijing 100049China
| | - Yao Wu
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
| | - Jia Long
- College of Life Sciences, Capital Normal UniversityBeijing 100048China
| | - Liyang Song
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
- College of Life Sciences, University of the Chinese Academy of SciencesBeijing 100049China
| | - Rongxiang Fang
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
| | - Yantao Jia
- State Key Laboratory of Plant Genomics, Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China
- National Plant Gene Research CenterBeijing 100101China
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Castiblanco LF, Triplett LR, Sundin GW. Regulation of Effector Delivery by Type III Secretion Chaperone Proteins in Erwinia amylovora. Front Microbiol 2018; 9:146. [PMID: 29472907 PMCID: PMC5809446 DOI: 10.3389/fmicb.2018.00146] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 01/23/2018] [Indexed: 11/16/2022] Open
Abstract
Type III secretion (TTS) chaperones are critical for the delivery of many effector proteins from Gram-negative bacterial pathogens into host cells, functioning in the stabilization and hierarchical delivery of the effectors to the type III secretion system (TTSS). The plant pathogen Erwinia amylovora secretes at least four TTS effector proteins: DspE, Eop1, Eop3, and Eop4. DspE specifically interacts with the TTS chaperone protein DspF, which stabilizes the effector protein in the cytoplasm and promotes its efficient translocation through the TTSS. However, the role of E. amylovora chaperones in regulating the delivery of other secreted effectors is unknown. In this study, we identified functional interactions between the effector proteins DspE, Eop1, and Eop3 with the TTS chaperones DspF, Esc1 and Esc3 in yeast. Using site-directed mutagenesis, secretion, and translocation assays, we demonstrated that the three TTS chaperones have additive roles for the secretion and translocation of DspE into plant cells whereas DspF negatively affects the translocation of Eop1 and Eop3. Collectively, these results indicate that TTS chaperone proteins exhibit a cooperative behavior to orchestrate the effector secretion and translocation dynamics in E. amylovora.
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Affiliation(s)
- Luisa F Castiblanco
- Department of Plant, Soil and Microbial Sciences, Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI, United States
| | - Lindsay R Triplett
- Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station, New Haven, CT, United States
| | - George W Sundin
- Department of Plant, Soil and Microbial Sciences, Center for Microbial Pathogenesis, Michigan State University, East Lansing, MI, United States
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29
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Li Y, Zhang Y, Wang Q, Wang T, Cao X, Zhao Z, Zhao S, Xu Y, Xiao Z, Li J, Fan J, Yang H, Huang F, Xiao S, Wang W. RESISTANCE TO POWDERY MILDEW8.1 boosts pattern-triggered immunity against multiple pathogens in Arabidopsis and rice. PLANT BIOTECHNOLOGY JOURNAL 2018; 16. [PMID: 28640974 PMCID: PMC5787827 DOI: 10.1111/pbi.12782] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The Arabidopsis gene RESISTANCE TO POWDERY MILDEW8.1 (RPW8.1) confers resistance to virulent fungal and oomycete pathogens that cause powdery mildew and downy mildew, respectively. However, the underlying mechanism remains unclear. Here, we show that ectopic expression of RPW8.1 boosts pattern-triggered immunity (PTI) resulting in enhanced resistance against different pathogens in both Arabidopsis and rice. In Arabidopsis, transcriptome analysis revealed that ectopic expression of RPW8.1-YFP constitutively up-regulates expression of many pathogen-associated molecular pattern (PAMP-)-inducible genes. Consistently, upon PAMP application, the transgenic line expressing RPW8.1-YFP exhibited more pronounced PTI responses such as callose deposition, production of reactive oxygen species, expression of defence-related genes and hypersensitive response-like cell death. Accordingly, the growth of a virulent bacterial pathogen was significantly inhibited in the transgenic lines expressing RPW8.1-YFP. Conversely, impairment of the PTI signalling pathway from PAMP cognition to the immediate downstream relay of phosphorylation abolished or significantly compromised RPW8.1-boosted PTI responses. In rice, heterologous expression of RPW8.1-YFP also led to enhanced resistance to the blast fungus Pyricularia oryzae (syn. Magnaporthe oryzae) and the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). Taken together, our data suggest a surprising mechanistic connection between RPW8.1 function and PTI, and demonstrate the potential of RPW8.1 as a transgene for engineering disease resistance across wide taxonomic lineages of plants.
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Affiliation(s)
- Yan Li
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
- Collaborative Innovation Center for Hybrid Rice in Yangtze River BasinSichuan Agricultural UniversityChengduChina
| | - Yong Zhang
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Qing‐Xia Wang
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Ting‐Ting Wang
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Xiao‐Long Cao
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Zhi‐Xue Zhao
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Sheng‐Li Zhao
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Yong‐Ju Xu
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Zhi‐Yuan Xiao
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Jin‐Lu Li
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Jing Fan
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
- Collaborative Innovation Center for Hybrid Rice in Yangtze River BasinSichuan Agricultural UniversityChengduChina
| | - Hui Yang
- College of Agronomy and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Fu Huang
- College of Agronomy and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
| | - Shunyuan Xiao
- Institute of Bioscience and Biotechnology ResearchDepartment of Plant Science and Landscape ArchitectureUniversity of MarylandCollege ParkMDUSA
| | - Wen‐Ming Wang
- Rice Research Institute and Key Lab for Major Crop DiseasesSichuan Agricultural UniversityChengduChina
- Collaborative Innovation Center for Hybrid Rice in Yangtze River BasinSichuan Agricultural UniversityChengduChina
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Scheibner F, Hartmann N, Hausner J, Lorenz C, Hoffmeister AK, Büttner D. The Type III Secretion Chaperone HpaB Controls the Translocation of Effector and Noneffector Proteins From Xanthomonas campestris pv. vesicatoria. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:61-74. [PMID: 28771395 DOI: 10.1094/mpmi-06-17-0138-r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pathogenicity of the gram-negative bacterium Xanthomonas campestris pv. vesicatoria depends on a type III secretion (T3S) system, which translocates effector proteins into plant cells. Effector proteins contain N-terminal T3S and translocation signals and interact with the T3S chaperone HpaB, which presumably escorts effectors to the secretion apparatus. The molecular mechanisms underlying the recognition of effectors by the T3S system are not yet understood. In the present study, we analyzed T3S and translocation signals in the type III effectors XopE2 and XopJ from X. campestris pv. vesicatoria. Both effectors contain minimal translocation signals, which are only recognized in the absence of HpaB. Additional N-terminal signals promote translocation of XopE2 and XopJ in the wild-type strain. The results of translocation and interaction studies revealed that the interaction of XopE2 and XopJ with HpaB and a predicted cytoplasmic substrate docking site of the T3S system is not sufficient for translocation. In agreement with this finding, we show that the presence of an artificial HpaB-binding site does not promote translocation of the noneffector XopA in the wild-type strain. Our data, therefore, suggest that the T3S chaperone HpaB not only acts as an escort protein but also controls the recognition of translocation signals.
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Affiliation(s)
- Felix Scheibner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Nadine Hartmann
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Jens Hausner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Christian Lorenz
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Anne-Katrin Hoffmeister
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
| | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany
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Huot B, Castroverde CDM, Velásquez AC, Hubbard E, Pulman JA, Yao J, Childs KL, Tsuda K, Montgomery BL, He SY. Dual impact of elevated temperature on plant defence and bacterial virulence in Arabidopsis. Nat Commun 2017; 8:1808. [PMID: 29180698 PMCID: PMC5704021 DOI: 10.1038/s41467-017-01674-2] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 10/06/2017] [Indexed: 11/16/2022] Open
Abstract
Environmental conditions profoundly affect plant disease development; however, the underlying molecular bases are not well understood. Here we show that elevated temperature significantly increases the susceptibility of Arabidopsis to Pseudomonas syringae pv. tomato (Pst) DC3000 independently of the phyB/PIF thermosensing pathway. Instead, elevated temperature promotes translocation of bacterial effector proteins into plant cells and causes a loss of ICS1-mediated salicylic acid (SA) biosynthesis. Global transcriptome analysis reveals a major temperature-sensitive node of SA signalling, impacting ~60% of benzothiadiazole (BTH)-regulated genes, including ICS1 and the canonical SA marker gene, PR1. Remarkably, BTH can effectively protect Arabidopsis against Pst DC3000 infection at elevated temperature despite the lack of ICS1 and PR1 expression. Our results highlight the broad impact of a major climate condition on the enigmatic molecular interplay between temperature, SA defence and function of a central bacterial virulence system in the context of a widely studied susceptible plant–pathogen interaction. Temperature is known to influence plant disease development. Here Huot et al. show that elevated temperature can enhance Pseudomonas syringae effector delivery into plant cells and suppress SA biosynthesis while also finding a temperature-sensitive branch of the SA signaling pathway in Arabidopsis.
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Affiliation(s)
- Bethany Huot
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.,Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, 48824, USA.,Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Christian Danve M Castroverde
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.,Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - André C Velásquez
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Emily Hubbard
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
| | - Jane A Pulman
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.,Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, MI, 48824, USA
| | - Jian Yao
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, 49008, USA
| | - Kevin L Childs
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.,Center for Genomics Enabled Plant Science, Michigan State University, East Lansing, MI, 48824, USA
| | - Kenichi Tsuda
- Department of Plant-Microbe Interactions, Max Planck Institute for Plant Breeding Research, 50829, Cologne, Germany
| | - Beronda L Montgomery
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA. .,Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA.
| | - Sheng Yang He
- Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA. .,Cell and Molecular Biology Program, Michigan State University, East Lansing, MI, 48824, USA. .,Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA. .,Howard Hughes Medical Institute, Michigan State University, East Lansing, MI, 48933, USA.
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32
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Scheibner F, Marillonnet S, Büttner D. The TAL Effector AvrBs3 from Xanthomonas campestris pv. vesicatoria Contains Multiple Export Signals and Can Enter Plant Cells in the Absence of the Type III Secretion Translocon. Front Microbiol 2017; 8:2180. [PMID: 29170655 PMCID: PMC5684485 DOI: 10.3389/fmicb.2017.02180] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/24/2017] [Indexed: 12/27/2022] Open
Abstract
Pathogenicity of the Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria depends on a type III secretion (T3S) system which translocates effector proteins into plant cells. Effector protein delivery is controlled by the T3S chaperone HpaB, which presumably escorts effector proteins to the secretion apparatus. One intensively studied effector is the transcription activator-like (TAL) effector AvrBs3, which binds to promoter sequences of plant target genes and activates plant gene expression. It was previously reported that type III-dependent delivery of AvrBs3 depends on the N-terminal protein region. The signals that control T3S and translocation of AvrBs3, however, have not yet been characterized. In the present study, we show that T3S and translocation of AvrBs3 depend on the N-terminal 10 and 50 amino acids, respectively. Furthermore, we provide experimental evidence that additional signals in the N-terminal 30 amino acids and the region between amino acids 64 and 152 promote translocation of AvrBs3 in the absence of HpaB. Unexpectedly, in vivo translocation assays revealed that AvrBs3 is delivered into plant cells even in the absence of HrpF, which is the predicted channel-forming component of the T3S translocon in the plant plasma membrane. The presence of HpaB- and HrpF-independent transport routes suggests that the delivery of AvrBs3 is initiated during early stages of the infection process, presumably before the activation of HpaB or the insertion of the translocon into the plant plasma membrane.
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Affiliation(s)
- Felix Scheibner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle, Germany
| | | | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle, Germany
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33
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Hatsugai N, Igarashi D, Mase K, Lu Y, Tsuda Y, Chakravarthy S, Wei HL, Foley JW, Collmer A, Glazebrook J, Katagiri F. A plant effector-triggered immunity signaling sector is inhibited by pattern-triggered immunity. EMBO J 2017; 36:2758-2769. [PMID: 28811287 DOI: 10.15252/embj.201796529] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 12/14/2022] Open
Abstract
Since signaling machineries for two modes of plant-induced immunity, pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), extensively overlap, PTI and ETI signaling likely interact. In an Arabidopsis quadruple mutant, in which four major sectors of the signaling network, jasmonate, ethylene, PAD4, and salicylate, are disabled, the hypersensitive response (HR) typical of ETI is abolished when the Pseudomonas syringae effector AvrRpt2 is bacterially delivered but is intact when AvrRpt2 is directly expressed in planta These observations led us to discovery of a network-buffered signaling mechanism that mediates HR signaling and is strongly inhibited by PTI signaling. We named this mechanism the ETI-Mediating and PTI-Inhibited Sector (EMPIS). The signaling kinetics of EMPIS explain apparently different plant genetic requirements for ETI triggered by different effectors without postulating different signaling machineries. The properties of EMPIS suggest that information about efficacy of the early immune response is fed back to the immune signaling network, modulating its activity and limiting the fitness cost of unnecessary immune responses.
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Affiliation(s)
- Noriyuki Hatsugai
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
| | - Daisuke Igarashi
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA.,Institute for Innovation, Ajinomoto Co., Inc., Kawasaki, Japan
| | - Keisuke Mase
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
| | - You Lu
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
| | - Yayoi Tsuda
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
| | - Suma Chakravarthy
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Hai-Lei Wei
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Joseph W Foley
- Department of Pathology, Stanford University, Stanford, CA, USA.,Ludmer Center for Neuroinformatics and Mental Health, Douglas Hospital Research Centre, McGill University, Montreal, QC, Canada
| | - Alan Collmer
- Section of Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Jane Glazebrook
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
| | - Fumiaki Katagiri
- Department of Plant and Microbial Biology, Microbial and Plant Genomics Institute, University of Minnesota, St. Paul, MN, USA
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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: 1.4] [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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Chakravarthy S, Butcher BG, Liu Y, D'Amico K, Coster M, Filiatrault MJ. Virulence of Pseudomonas syringae pv. tomato DC3000 Is Influenced by the Catabolite Repression Control Protein Crc. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:283-294. [PMID: 28384054 DOI: 10.1094/mpmi-09-16-0196-r] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Pseudomonas syringae infects diverse plant species and is widely used as a model system in the study of effector function and the molecular basis of plant diseases. Although the relationship between bacterial metabolism, nutrient acquisition, and virulence has attracted increasing attention in bacterial pathology, it is largely unexplored in P. syringae. The Crc (catabolite repression control) protein is a putative RNA-binding protein that regulates carbon metabolism as well as a number of other factors in the pseudomonads. Here, we show that deletion of crc increased bacterial swarming motility and biofilm formation. The crc mutant showed reduced growth and symptoms in Arabidopsis and tomato when compared with the wild-type strain. We have evidence that the crc mutant shows delayed hypersensitive response (HR) when infiltrated into Nicotiana benthamiana and tobacco. Interestingly, the crc mutant was more susceptible to hydrogen peroxide, suggesting that, in planta, the mutant may be sensitive to reactive oxygen species generated during pathogen-associated molecular pattern-triggered immunity (PTI). Indeed, HR was further delayed when PTI-induced tissues were challenged with the crc mutant. The crc mutant did not elicit an altered PTI response in plants compared with the wild-type strain. We conclude that Crc plays an important role in growth and survival during infection.
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Affiliation(s)
- Suma Chakravarthy
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Bronwyn G Butcher
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Yingyu Liu
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Katherine D'Amico
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
- 2 Emerging Pests & Pathogens Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, U.S.A
| | - Matthew Coster
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
| | - Melanie J Filiatrault
- 1 School of Integrative Plant Science, Section of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, U.S.A.; and
- 2 Emerging Pests & Pathogens Research Unit, Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, United States Department of Agriculture, Ithaca, NY 14853, U.S.A
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36
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Li L, Miao W, Liu W, Zhang S. The signal peptide-like segment of hpaXm is required for its association to the cell wall in transgenic tobacco plants. PLoS One 2017; 12:e0170931. [PMID: 28141855 PMCID: PMC5283683 DOI: 10.1371/journal.pone.0170931] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 01/12/2017] [Indexed: 11/19/2022] Open
Abstract
Harpins, encoded by hrp (hypersensitive response and pathogenicity) genes of Gram-negative plant pathogens, are elicitors of hypersensitive response (HR). HpaXm is a novel harpin-like protein described from cotton leaf blight bacteria, Xanthomonas citri subsp. malvacearum-a synonym of X. campestris pv. malvacearum (Smith 1901-1978). A putative signal peptide (1-MNSLNTQIGANSSFL-15) of hpaXm was predicted in the nitroxyl-terminal (N-terminal)by SignalP (SignalP 3.0 server). Here, we explored the function of the N-terminal leader peptide like segment of hpaXm using transgenic tobacco (Nicotiana tabacum cv. Xanthi nc.). Transgenic tobacco lines expressing the full-length hpaXm and the signal peptide-like segment-deleted mutant hpaXmΔLP were developed using transformation mediated by Agrobacterium tumefaciens. The target genes were confirmed integrated into the tobacco genomes and expressed normally. Using immune colloidal-gold detection technique, hpaXm protein was found to be transferred to the cytoplasm, the cell membrane, and organelles such as chloroplasts, mitochondria, and nucleus, as well as the cell wall. However, the deletion mutant hpaXmΔLP expressed in transgenic tobacco was found unable to cross the membrane to reach the cell wall. Additionally, soluble proteins extracted from plants transformed with hpaXm and hpaXmΔLP were bio-active. Defensive micro-HR induced by the transgene expression of hpaXm and hpaXmΔLP were observed on transgenic tobacco leaves. Disease resistance bioassays to tobacco mosaic virus (TMV) showed that tobacco plants transformed with hpaXm and with hpaXmΔLP exhibited enhanced resistance to TMV. In summary, the N-terminal signal peptide-like segment (1-45 bp) in hpaXm sequence is not necessary for transgene expression, bioactivity of hpaXm and resistance to TMV in transgenic tobacco, but is required for the protein to be translocated to the cell wall.
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Affiliation(s)
- Le Li
- College of Environment and Plant Protection, Hainan University, Haikou, Hainan Province, China
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Haikou, Hainan Province, China
| | - Weiguo Miao
- College of Environment and Plant Protection, Hainan University, Haikou, Hainan Province, China
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Haikou, Hainan Province, China
| | - Wenbo Liu
- College of Environment and Plant Protection, Hainan University, Haikou, Hainan Province, China
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, Haikou, Hainan Province, China
| | - Shujian Zhang
- U.S. Horticultural Research Laboratory, USDA-ARS, Fort Pierce, Florida, United States of America
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Castañeda-Ojeda MP, Moreno-Pérez A, Ramos C, López-Solanilla E. Suppression of Plant Immune Responses by the Pseudomonas savastanoi pv. savastanoi NCPPB 3335 Type III Effector Tyrosine Phosphatases HopAO1 and HopAO2. FRONTIERS IN PLANT SCIENCE 2017; 8:680. [PMID: 28529516 PMCID: PMC5418354 DOI: 10.3389/fpls.2017.00680] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 04/13/2017] [Indexed: 05/12/2023]
Abstract
The effector repertoire of the olive pathogen P. savastanoi pv. savastanoi NCPPB 3335 includes two members of the HopAO effector family, one of the most diverse T3E families of the P. syringae complex. The study described here explores the phylogeny of these dissimilar members, HopAO1 and HopAO2, among the complex and reveals their activities as immune defense suppressors. Although HopAO1 is predominantly encoded by phylogroup 3 strains isolated from woody organs of woody hosts, both HopAO1 and HopAO2 are phylogenetically clustered according to the woody/herbaceous nature of their host of isolation, suggesting host specialization of the HopAO family across the P. syringae complex. HopAO1 and HopAO2 translocate into plant cells and show hrpL-dependent expression, which allows their classification as actively deployed type III effectors. Our data also show that HopAO1 and HopAO2 possess phosphatase activity, a hallmark of the members of this family. Both of them exert an inhibitory effect on early plant defense responses, such as ROS production and callose deposition, and are able to suppress ETI responses induced by the effectorless polymutant of P. syringae pv. tomato DC3000 (DC3000D28E) in Nicotiana. Moreover, we demonstrate that a ΔhopAO1 mutant of P. savastanoi NCPBB 3335 exhibits a reduced fitness and virulence in olive plants, which supports the relevance of this effector during the interaction of this strain with its host plants. This work contributes to the field with the first report regarding functional analysis of HopAO homologs encoded by P. syringae or P. savastanoi strains isolated from woody hosts.
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Affiliation(s)
- María Pilar Castañeda-Ojeda
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Alba Moreno-Pérez
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Cayo Ramos
- Área de Genética, Facultad de Ciencias, Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga – Consejo Superior de Investigaciones CientíficasMálaga, Spain
| | - Emilia López-Solanilla
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid – Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Parque Científico y Tecnológico de la UPMMadrid, Spain
- Departamento de Biotecnología y Biología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Alimentaria y de Biosistemas, Universidad Politécnica de MadridMadrid, Spain
- *Correspondence: Emilia López-Solanilla,
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Yamada K, Saijo Y, Nakagami H, Takano Y. Regulation of sugar transporter activity for antibacterial defense in
Arabidopsis. Science 2016; 354:1427-1430. [DOI: 10.1126/science.aah5692] [Citation(s) in RCA: 160] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 11/11/2016] [Indexed: 12/26/2022]
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39
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Huang YC, Lin YC, Wei CF, Deng WL, Huang HC. The pathogenicity factor HrpF interacts with HrpA and HrpG to modulate type III secretion system (T3SS) function and t3ss expression in Pseudomonas syringae pv. averrhoi. MOLECULAR PLANT PATHOLOGY 2016; 17:1080-94. [PMID: 26638129 PMCID: PMC6638529 DOI: 10.1111/mpp.12349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 11/05/2015] [Accepted: 11/29/2015] [Indexed: 05/08/2023]
Abstract
To ensure the optimal infectivity on contact with host cells, pathogenic Pseudomonas syringae has evolved a complex mechanism to control the expression and construction of the functional type III secretion system (T3SS) that serves as a dominant pathogenicity factor. In this study, we showed that the hrpF gene of P. syringae pv. averrhoi, which is located upstream of hrpG, encodes a T3SS-dependent secreted/translocated protein. Mutation of hrpF leads to the loss of bacterial ability on elicitation of disease symptoms in the host and a hypersensitive response in non-host plants, and the secretion or translocation of the tested T3SS substrates into the bacterial milieu or plant cells. Moreover, overexpression of hrpF in the wild-type results in delayed HR and reduced t3ss expression. The results of protein-protein interactions demonstrate that HrpF interacts directly with HrpG and HrpA in vitro and in vivo, and protein stability assays reveal that HrpF assists HrpA stability in the bacterial cytoplasm, which is reduced by a single amino acid substitution at the 67th lysine residue of HrpF with alanine. Taken together, the data presented here suggest that HrpF has two roles in the assembly of a functional T3SS: one by acting as a negative regulator, possibly involved in the HrpSVG regulation circuit via binding to HrpG, and the other by stabilizing HrpA in the bacterial cytoplasm via HrpF-HrpA interaction prior to the secretion and formation of Hrp pilus on the bacterial surface.
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Affiliation(s)
- Yi-Chiao Huang
- Department of Plant Pathology, National Chung Hsing University, Taichung, 40227, Taiwan
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Yuan-Chuen Lin
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Chia-Fong Wei
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Wen-Ling Deng
- Department of Plant Pathology, National Chung Hsing University, Taichung, 40227, Taiwan
- Agricultural Biotechnology Center, National Chung Hsing University, Taichung, 40227, Taiwan
| | - Hsiou-Chen Huang
- Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan
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40
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Salvo E, Alabi S, Liu B, Schlessinger A, Bechhofer DH. Interaction of Bacillus subtilis Polynucleotide Phosphorylase and RNase Y: STRUCTURAL MAPPING AND EFFECT ON mRNA TURNOVER. J Biol Chem 2016; 291:6655-63. [PMID: 26797123 DOI: 10.1074/jbc.m115.711044] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Indexed: 11/06/2022] Open
Abstract
Polynucleotide phosphorylase (PNPase), a 3'-to-5' phosphorolytic exoribonuclease, is thought to be the primary enzyme responsible for turnover ofBacillus subtilismRNA. The role of PNPase inB. subtilismRNA decay has been analyzed previously by comparison of mRNA profiles in a wild-type strainversusa strain that is deleted forpnpA, the gene encoding PNPase. Recent studies have provided evidence for a degradosome-like complex inB. subtilisthat is built around the major decay-initiating endonuclease, RNase Y, and there is ample evidence for a strong interaction between PNPase and RNase Y. The role of the PNPase-RNase Y interaction in the exonucleolytic function of PNPase needs to be clarified. We sought to construct aB. subtilisstrain containing a catalytically active PNPase that could not interact with RNase Y. Mapping studies of the PNPase-RNase Y interaction were guided by a homology model ofB. subtilisPNPase based on the known structure of theEscherichia coliPNPase in complex with an RNase E peptide. Mutations inB. subtilisresidues predicted to be involved in RNase Y binding showed a loss of PNPase-RNase Y interaction. Two mRNAs whose decay is dependent on RNase Y and PNPase were examined in strains containing full-length PNPase that was either catalytically active but unable to interact with RNase Y, or catalytically inactive but able to interact with RNase Y. At least for these two mRNAs, disruption of the PNPase-RNase Y interaction did not appear to affect mRNA turnover.
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Affiliation(s)
- Elizabeth Salvo
- From the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Shanique Alabi
- From the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Bo Liu
- From the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Avner Schlessinger
- From the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - David H Bechhofer
- From the Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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41
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Lu Y, Hatsugai N, Katagiri F, Ishimaru CA, Glazebrook J. Putative Serine Protease Effectors of Clavibacter michiganensis Induce a Hypersensitive Response in the Apoplast of Nicotiana Species. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:1216-26. [PMID: 26075829 DOI: 10.1094/mpmi-02-15-0036-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Clavibacter michiganensis subspp. michiganensis and sepedonicus cause diseases on solanaceous crops. The genomes of both subspecies encode members of the pat-1 family of putative serine proteases known to function in virulence on host plants and induction of hypersensitive responses (HR) on nonhosts. One gene of this family in C. michiganensis subsp. sepedonicus, chp-7, is required for triggering HR in Nicotiana tabacum. Here, further investigation revealed that mutation of the putative catalytic serine residue at position 232 to threonine abolished the HR induction activity of Chp-7, suggesting that enzymatic activity is required. Purified Chp-7 triggered an HR in N. tabacum leaves in the absence of the pathogen, indicating Chp-7 itself is the HR elicitor from C. michiganensis subsp. sepedonicus. Ectopic expression of chp-7 constructs in N. tabacum leaves revealed that Chp-7 targeted to the apoplast triggered an HR while cytoplasmic Chp-7 did not, indicating that Chp-7 induces the HR in the apoplast of N. tabacum leaves. Chp-7 also induced HR in N. sylvestris, a progenitor of N. tabacum, but not in other Nicotiana species tested. ChpG, a related protein from C. michiganensis subsp. michiganensis, also triggered HR in N. tabacum and N. sylvestris. Unlike Chp-7, ChpG triggered HR in N. clevelandii and N. glutinosa.
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Affiliation(s)
- You Lu
- 1 Department of Plant Biology
- 2 Microbial and Plant Genomics Institute, and
- 3 Plant Biological Sciences Graduate Program, University of Minnesota, 1445 Gortner Ave., St. Paul, MN 55108, U.S.A
| | - Noriyuki Hatsugai
- 1 Department of Plant Biology
- 2 Microbial and Plant Genomics Institute, and
| | - Fumiaki Katagiri
- 1 Department of Plant Biology
- 2 Microbial and Plant Genomics Institute, and
| | - Carol A Ishimaru
- 2 Microbial and Plant Genomics Institute, and
- 4 Department of Plant Pathology, University of Minnesota, 1991 Upper Buford Circle, St. Paul, MN 55108, U.S.A
| | - Jane Glazebrook
- 1 Department of Plant Biology
- 2 Microbial and Plant Genomics Institute, and
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42
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Lomovatskaya LA, Romanenko AS, Rykun OV. Transmembrane adenylate cyclase controls the virulence factors of plant pathogenic Pseudomonas siringae and mutualistic Rhizobium leguminosarum. Microbiology (Reading) 2015. [DOI: 10.1134/s0026261715040116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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43
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Russell AR, Ashfield T, Innes RW. Pseudomonas syringae Effector AvrPphB Suppresses AvrB-Induced Activation of RPM1 but Not AvrRpm1-Induced Activation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:727-35. [PMID: 25625821 DOI: 10.1094/mpmi-08-14-0248-r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The Pseudomonas syringae effector AvrB triggers a hypersensitive resistance response in Arabidopsis and soybean plants expressing the disease resistance (R) proteins RPM1 and Rpg1b, respectively. In Arabidopsis, AvrB induces RPM1-interacting protein kinase (RIPK) to phosphorylate a disease regulator known as RIN4, which subsequently activates RPM1-mediated defenses. Here, we show that AvrPphB can suppress activation of RPM1 by AvrB and this suppression is correlated with the cleavage of RIPK by AvrPphB. Significantly, AvrPphB does not suppress activation of RPM1 by AvrRpm1, suggesting that RIPK is not required for AvrRpm1-induced modification of RIN4. This observation indicates that AvrB and AvrRpm1 recognition is mediated by different mechanisms in Arabidopsis, despite their recognition being determined by a single R protein. Moreover, AvrB recognition but not AvrRpm1 recognition is suppressed by AvrPphB in soybean, suggesting that AvrB recognition requires a similar molecular mechanism in soybean and Arabidopsis. In support of this, we found that phosphodeficient mutations in the soybean GmRIN4a and GmRIN4b proteins are sufficient to block Rpg1b-mediated hypersensitive response in transient assays in Nicotiana glutinosa. Taken together, our results indicate that AvrB and AvrPphB target a conserved defense signaling pathway in Arabidopsis and soybean that includes RIPK and RIN4.
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Affiliation(s)
- Andrew R Russell
- Department of Biology, Indiana University, Bloomington, IN 47405, U.S.A
| | - Tom Ashfield
- Department of Biology, Indiana University, Bloomington, IN 47405, U.S.A
| | - Roger W Innes
- Department of Biology, Indiana University, Bloomington, IN 47405, U.S.A
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44
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Microbial genome-enabled insights into plant–microorganism interactions. Nat Rev Genet 2014; 15:797-813. [DOI: 10.1038/nrg3748] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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45
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Lam HN, Chakravarthy S, Wei HL, BuiNguyen H, Stodghill PV, Collmer A, Swingle BM, Cartinhour SW. Global analysis of the HrpL regulon in the plant pathogen Pseudomonas syringae pv. tomato DC3000 reveals new regulon members with diverse functions. PLoS One 2014; 9:e106115. [PMID: 25170934 PMCID: PMC4149516 DOI: 10.1371/journal.pone.0106115] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022] Open
Abstract
The type III secretion system (T3SS) is required for virulence in the gram-negative plant pathogen Pseudomonas syringae pv. tomato DC3000. The alternative sigma factor HrpL directly regulates expression of T3SS genes via a promoter sequence, often designated as the "hrp promoter." Although the HrpL regulon has been extensively investigated in DC3000, it is not known whether additional regulon members remain to be found. To systematically search for HrpL-regulated genes, we used chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-Seq) and bulk mRNA sequencing (RNA-Seq) to identify HrpL-binding sites and likely hrp promoters. The analysis recovered 73 sites of interest, including 20 sites that represent new hrp promoters. The new promoters lie upstream of a diverse set of genes encoding potential regulators, enzymes and hypothetical proteins. PSPTO_5633 is the only new HrpL regulon member that is potentially an effector and is now designated HopBM1. Deletions in several other new regulon members, including PSPTO_5633, PSPTO_0371, PSPTO_2130, PSPTO_2691, PSPTO_2696, PSPTO_3331, and PSPTO_5240, in either DC3000 or ΔhopQ1-1 backgrounds, do not affect the hypersensitive response or in planta growth of the resulting strains. Many new HrpL regulon members appear to be unrelated to the T3SS, and orthologs for some of these can be identified in numerous non-pathogenic bacteria. With the identification of 20 new hrp promoters, the list of HrpL regulon members is approaching saturation and most likely includes all DC3000 effectors.
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Affiliation(s)
- Hanh N. Lam
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Suma Chakravarthy
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Hai-Lei Wei
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - HoangChuong BuiNguyen
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Paul V. Stodghill
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
- United States Department of Agriculture-Agricultural Research Service, Ithaca, New York, United States of America
| | - Alan Collmer
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Bryan M. Swingle
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
- United States Department of Agriculture-Agricultural Research Service, Ithaca, New York, United States of America
| | - Samuel W. Cartinhour
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
- United States Department of Agriculture-Agricultural Research Service, Ithaca, New York, United States of America
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Lohou D, Turner M, Lonjon F, Cazalé AC, Peeters N, Genin S, Vailleau F. HpaP modulates type III effector secretion in Ralstonia solanacearum and harbours a substrate specificity switch domain essential for virulence. MOLECULAR PLANT PATHOLOGY 2014; 15:601-14. [PMID: 24405562 PMCID: PMC6638691 DOI: 10.1111/mpp.12119] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Many pathogenic bacteria have evolved a type III secretion system (T3SS) to successfully invade their host. This extracellular apparatus allows the translocation of proteins, called type III effectors (T3Es), directly into the host cells. T3Es are virulence factors that have been shown to interfere with the host's immunity or to provide nutrients from the host to the bacteria. The Gram-negative bacterium Ralstonia solanacearum is a worldwide major crop pest whose virulence strongly relies on the T3SS. In R. solanacearum, transcriptional regulation has been extensively studied. However, very few data are available concerning the role played by type III-associated regulators, such as type III chaperones and T3SS control proteins. Here, we characterized HpaP, a putative type III secretion substrate specificity switch (T3S4) protein of R. solanacearum which is not secreted by the bacterium or translocated in the plant cells. HpaP self-interacts and interacts with the PopP1 T3E. HpaP modulates the secretion of early (HrpY pilin) and late (AvrA and PopP1 T3Es) type III substrates. HpaP is dispensable for the translocation of T3Es into the host cells. Finally, we identified two regions of five amino acids in the T3S4 domain that are essential for efficient PopP1 secretion and for HpaP's role in virulence on tomato and Arabidopsis thaliana, but not required for HpaP-HpaP and HpaP-PopP1 interactions. Taken together, our results indicate that HpaP is a putative R. solanacearum T3S4 protein important for full pathogenicity on several hosts, acting as a helper for PopP1 secretion, and repressing AvrA and HrpY secretion.
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Affiliation(s)
- David Lohou
- Laboratoire des Interactions Plantes-Microorganismes (LIPM), INRA, UMR441, F-31326, Castanet-Tolosan, France; Laboratoire des Interactions Plantes-Microorganismes (LIPM), CNRS, UMR2594, F-31326, Castanet-Tolosan, France
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Matas IM, Castañeda-Ojeda MP, Aragón IM, Antúnez-Lamas M, Murillo J, Rodríguez-Palenzuela P, López-Solanilla E, Ramos C. Translocation and functional analysis of Pseudomonas savastanoi pv. savastanoi NCPPB 3335 type III secretion system effectors reveals two novel effector families of the Pseudomonas syringae complex. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:424-36. [PMID: 24329173 DOI: 10.1094/mpmi-07-13-0206-r] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Pseudomonas savastanoi pv. savastanoi NCPPB 3335 causes olive knot disease and is a model pathogen for exploring bacterial infection of woody hosts. The type III secretion system (T3SS) effector repertoire of this strain includes 31 effector candidates plus two novel candidates identified in this study which have not been reported to translocate into plant cells. In this work, we demonstrate the delivery of seven NCPPB 3335 effectors into Nicotiana tabacum leaves, including three proteins from two novel families of the P. syringae complex effector super-repertoire (HopBK and HopBL), one of which comprises two proteins (HopBL1 and HopBL2) that harbor a SUMO protease domain. When delivered by P. fluorescens heterologously expressing a P. syringae T3SS, all seven effectors were found to suppress the production of defense-associated reactive oxygen species. Moreover, six of these effectors, including the truncated versions of HopAA1 and HopAZ1 encoded by NCPPB 3335, suppressed callose deposition. The expression of HopAZ1 and HopBL1 by functionally effectorless P. syringae pv. tomato DC3000D28E inhibited the hypersensitive response in tobacco and, additionally, expression of HopBL2 by this strain significantly increased its competitiveness in N. benthamiana. DNA sequences encoding HopBL1 and HopBL2 were uniquely detected in a collection of 31 P. savastanoi pv. savastanoi strains and other P. syringae strains isolated from woody hosts, suggesting a relevant role of these two effectors in bacterial interactions with olive and other woody plants.
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Decreased abundance of type III secretion system-inducing signals in Arabidopsis mkp1 enhances resistance against Pseudomonas syringae. Proc Natl Acad Sci U S A 2014; 111:6846-51. [PMID: 24753604 DOI: 10.1073/pnas.1403248111] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Genes encoding the virulence-promoting type III secretion system (T3SS) in phytopathogenic bacteria are induced at the start of infection, indicating that recognition of signals from the host plant initiates this response. However, the precise nature of these signals and whether their concentrations can be altered to affect the biological outcome of host-pathogen interactions remain speculative. Here we use a metabolomic comparison of resistant and susceptible genotypes to identify plant-derived metabolites that induce T3SS genes in Pseudomonas syringae pv tomato DC3000 and report that mapk phosphatase 1 (mkp1), an Arabidopsis mutant that is more resistant to bacterial infection, produces decreased levels of these bioactive compounds. Consistent with these observations, T3SS effector expression and delivery by DC3000 was impaired when infecting the mkp1 mutant. The addition of bioactive metabolites fully restored T3SS effector delivery and suppressed the enhanced resistance in the mkp1 mutant. Pretreatment of plants with pathogen-associated molecular patterns (PAMPs) to induce PAMP-triggered immunity (PTI) also restricts T3SS effector delivery and enhances resistance by unknown mechanisms, and the addition of the bioactive metabolites similarly suppressed both aspects of PTI. Together, these results demonstrate that DC3000 perceives multiple signals derived from plants to initiate its T3SS and that the level of these host-derived signals impacts bacterial pathogenesis.
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Marín M, Ott T. Intrinsic disorder in plant proteins and phytopathogenic bacterial effectors. Chem Rev 2014; 114:6912-32. [PMID: 24697726 DOI: 10.1021/cr400488d] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Macarena Marín
- Genetics Institute, Faculty of Biology, Ludwig-Maximilians-University of Munich , Grosshaderner Strasse 2-4, 82152 Martinsried, Germany
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Identification of 17 HrpX-regulated proteins including two novel type III effectors, XOC_3956 and XOC_1550, in Xanthomonas oryzae pv. oryzicola. PLoS One 2014; 9:e93205. [PMID: 24675748 PMCID: PMC3968052 DOI: 10.1371/journal.pone.0093205] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/02/2014] [Indexed: 12/11/2022] Open
Abstract
The function of some hypothetical proteins, possibly regulated by key hrp regulators, in the pathogenicity of phytopathogenic bacteria remains largely unknown. In the present study, in silicon microarray data demonstrated that the expression of 17 HrpX-regulated protein (Xrp) genes of X. oryzae pv. oryzicola (Xoc), which causes bacterial leaf streak in rice, were either positively or negatively regulated by HrpX or/and HrpG. Bioinformatics analysis demonstrated that five Xrps possess a putative type III secretion (T3S) signal in the first 50 N-terminal amino acids, six xrp genes contain a PIP-box-like sequence (TTCGB-NX-TTCGB, 9≤X≤25) in the promoter regions, and two Xrps have both motifs. Twelve Xrps are widely conserved in Xanthomonas spp., whereas four are specific for X. oryzae (Xrp6) or Xoc (Xrp8, Xrp14 and Xrp17). In addition to the regulation by HrpG/HrpX, some of the 17 genes were also modulated by another hrp regulator HrpD6. Mutagenesis of these 17 genes indicated that five Xrps (Xrp1, Xrp2, Xrp5, Xrp8 and Xrp14) were required for full virulence and bacterial growth in planta. Immunoblotting assays and fusion with N-terminally truncated AvrXa10 indicated that Xrp3 and Xrp5 were secreted and translocated into rice cells through the type-III secretion system (T3S), suggesting they are novel T3S effectors. Our results suggest that Xoc exploits an orchestra of proteins that are regulated by HrpG, HrpX and HrpD6, and these proteins facilitate both infection and metabolism.
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