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Khan M, Uhse S, Bindics J, Kogelmann B, Nagarajan N, Tabassum R, Ingole KD, Djamei A. Tip of the iceberg? Three novel TOPLESS-interacting effectors of the gall-inducing fungus Ustilago maydis. THE NEW PHYTOLOGIST 2024; 244:949-961. [PMID: 39021059 DOI: 10.1111/nph.19967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 06/24/2024] [Indexed: 07/20/2024]
Abstract
Ustilago maydis is a biotrophic pathogen causing smut disease in maize. It secretes a cocktail of effector proteins, which target different host proteins during its biotrophic stages in the host plant. One such class of proteins we identified previously is TOPLESS (TPL) and TOPLESS-RELATED (TPR) transcriptional corepressors. Here, we screened 297 U. maydis effector candidates for their ability to interact with maize TPL protein RAMOSA 1 ENHANCER LOCUS 2 LIKE 2 (RELK2) and their ability to induce auxin signaling and thereby identified three novel TPL-interacting protein effectors (Tip6, Tip7, and Tip8). Structural modeling and mutational analysis allowed the identification of TPL-interaction motifs of Tip6 and Tip7. In planta interaction between Tip6 and Tip7 with RELK2 occurs mainly in nuclear compartments, whereas Tip8 colocalizes with RELK2 in a compartment outside the nucleus. Overexpression of Tip8 in nonhost plants leads to cell death, indicating recognition of the effector or its activity. By performing infection assays with single and multideletion mutants of U. maydis, we demonstrate a positive role of Tip6 and Tip7 in U. maydis virulence. Transcriptional profiling of maize leaves infected with Tip effector mutants in comparison with SG200 strain suggests Tip effector activities are not merely redundant.
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Affiliation(s)
- Mamoona Khan
- Department of Plant Pathology, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Nussallee 9, Bonn, 53115, Germany
| | - Simon Uhse
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna Bio Center (VBC), Dr. Bohr-Gasse 3, Vienna, 1030, Austria
| | - Janos Bindics
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna Bio Center (VBC), Dr. Bohr-Gasse 3, Vienna, 1030, Austria
| | - Benjamin Kogelmann
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna Bio Center (VBC), Dr. Bohr-Gasse 3, Vienna, 1030, Austria
| | - Nithya Nagarajan
- Department of Plant Pathology, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Nussallee 9, Bonn, 53115, Germany
| | - Riaz Tabassum
- Department of Plant Pathology, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Nussallee 9, Bonn, 53115, Germany
| | - Kishor D Ingole
- Department of Plant Pathology, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Nussallee 9, Bonn, 53115, Germany
| | - Armin Djamei
- Department of Plant Pathology, Institute of Crop Science and Resource Conservation (INRES), University of Bonn, Nussallee 9, Bonn, 53115, Germany
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna Bio Center (VBC), Dr. Bohr-Gasse 3, Vienna, 1030, Austria
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2
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He Y, Li P, Zhou X, Ali S, Zhu J, Ma Y, Li J, Zhang N, Li H, Li Y, Nie Y. A ribonuclease T2 protein FocRnt2 contributes to the virulence of Fusarium oxysporum f. sp. cubense tropical race 4. MOLECULAR PLANT PATHOLOGY 2024; 25:e13502. [PMID: 39118198 PMCID: PMC11310096 DOI: 10.1111/mpp.13502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2024] [Revised: 07/12/2024] [Accepted: 07/15/2024] [Indexed: 08/10/2024]
Abstract
Banana Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), is a major disease of banana plants worldwide. Effector proteins play critical roles in banana-Foc TR4 interaction. Our previous studies highlighted a ribonuclease protein belonging to the T2 family (named as FocRnt2) in the Foc TR4 secretome, which was predicted to be an effector. However, its biological function in Foc TR4 infection is still unclear. Herein, we observed significant expression of FocRnt2 during the early stage of fungal infection in planta. A yeast signal sequence trap assay showed that FocRnt2 contained a functional signal peptide for secretion. FocRnt2 possessed ribonuclease activity that could degrade the banana total RNA in vitro. Subcellular localization showed that FocRnt2 was localized in the nucleus and cytoplasm of Nicotiana benthamiana leaves. Transient expression of FocRnt2 suppressed the expression of salicylic acid- and jasmonic acid-signalling marker genes, reactive oxygen species accumulation, and BAX-mediated cell death in N. benthamiana. FocRnt2 deletion limited fungal penetration, reduced fusaric acid biosynthesis in Foc TR4, and attenuated fungal virulence against banana plants, but had little effect on Foc TR4 growth and sensitivity to various stresses. Furthermore, FocRnt2 deletion mutants induced higher expression of the defence-related genes in banana plants. These results suggest that FocRnt2 plays an important role in full virulence of Foc TR4, further improving our understanding of effector-mediated Foc TR4 pathogenesis.
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Affiliation(s)
- Yanqiu He
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
- Institute of Plant Protection and Agro‐Products SafetyAnhui Academy of Agricultural SciencesHefeiChina
| | - Pengfei Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Xiaoshu Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Shaukat Ali
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Jie Zhu
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Yini Ma
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Jieling Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Nan Zhang
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Huaping Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Yunfeng Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
| | - Yanfang Nie
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, College of Plant ProtectionSouth China Agricultural UniversityGuangzhouChina
- College of Materials and EnergySouth China Agricultural UniversityGuangzhouChina
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Navarrete F, Gallei M, Kornienko AE, Saado I, Khan M, Chia KS, Darino MA, Bindics J, Djamei A. TOPLESS promotes plant immunity by repressing auxin signaling and is targeted by the fungal effector Naked1. PLANT COMMUNICATIONS 2022; 3:100269. [PMID: 35529945 PMCID: PMC9073326 DOI: 10.1016/j.xplc.2021.100269] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 10/21/2021] [Accepted: 11/21/2021] [Indexed: 05/05/2023]
Abstract
In plants, the antagonism between growth and defense is hardwired by hormonal signaling. The perception of pathogen-associated molecular patterns (PAMPs) from invading microorganisms inhibits auxin signaling and plant growth. Conversely, pathogens manipulate auxin signaling to promote disease, but how this hormone inhibits immunity is not fully understood. Ustilago maydis is a maize pathogen that induces auxin signaling in its host. We characterized a U. maydis effector protein, Naked1 (Nkd1), that is translocated into the host nucleus. Through its native ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif, Nkd1 binds to the transcriptional co-repressors TOPLESS/TOPLESS-related (TPL/TPRs) and prevents the recruitment of a transcriptional repressor involved in hormonal signaling, leading to the de-repression of auxin and jasmonate signaling and thereby promoting susceptibility to (hemi)biotrophic pathogens. A moderate upregulation of auxin signaling inhibits the PAMP-triggered reactive oxygen species (ROS) burst, an early defense response. Thus, our findings establish a clear mechanism for auxin-induced pathogen susceptibility. Engineered Nkd1 variants with increased expression or increased EAR-mediated TPL/TPR binding trigger typical salicylic-acid-mediated defense reactions, leading to pathogen resistance. This implies that moderate binding of Nkd1 to TPL is a result of a balancing evolutionary selection process to enable TPL manipulation while avoiding host recognition.
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Affiliation(s)
- Fernando Navarrete
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Michelle Gallei
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Aleksandra E. Kornienko
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Indira Saado
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstraße 3, 06466 Stadt Seeland, Germany
| | - Mamoona Khan
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstraße 3, 06466 Stadt Seeland, Germany
| | - Khong-Sam Chia
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstraße 3, 06466 Stadt Seeland, Germany
| | - Martin A. Darino
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Janos Bindics
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Armin Djamei
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences (OEAW), Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, 1030 Vienna, Austria
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstraße 3, 06466 Stadt Seeland, Germany
- Corresponding author
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He Y, Zhou X, Li J, Li H, Li Y, Nie Y. In Vitro Secretome Analysis Suggests Differential Pathogenic Mechanisms between Fusarium oxysporum f. sp. cubense Race 1 and Race 4. Biomolecules 2021; 11:1353. [PMID: 34572566 PMCID: PMC8466104 DOI: 10.3390/biom11091353] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 09/07/2021] [Accepted: 09/10/2021] [Indexed: 11/16/2022] Open
Abstract
Banana Fusarium wilt, caused by the fungus pathogen Fusarium oxysporum f. sp. cubense (Foc), is a devastating disease that causes tremendous reductions in banana yield worldwide. Secreted proteins can act as pathogenicity factors and play important roles in the Foc-banana interactions. In this study, a shotgun-based proteomic approach was employed to characterize and compare the secretomes of Foc1 and Foc4 upon banana extract treatment, which detected 1183 Foc1 and 2450 Foc4 proteins. Comprehensive in silico analyses further identified 447 Foc1 and 433 Foc4 proteins in the classical and non-classical secretion pathways, while the remaining proteins might be secreted through currently unknown mechanisms. Further analyses showed that the secretomes of Foc1 and Foc4 are similar in their overall functional characteristics and share largely conserved repertoires of CAZymes and effectors. However, we also identified a number of potentially important pathogenicity factors that are differentially present in Foc1 and Foc4, which may contribute to their different pathogenicity against banana hosts. Furthermore, our quantitative PCR analysis revealed that genes encoding secreted pathogenicity factors differ significantly between Foc1 and Foc4 in their expression regulation in response to banana extract treatment. To our knowledge, this is the first experimental secretome analysis that focused on the pathogenicity mechanism in different Foc races. The results of this study provide useful resources for further exploration of the complicated pathogenicity mechanisms in Foc.
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Affiliation(s)
- Yanqiu He
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (X.Z.); (J.L.); (H.L.)
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Xiaofan Zhou
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (X.Z.); (J.L.); (H.L.)
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Jieling Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (X.Z.); (J.L.); (H.L.)
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Huaping Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (X.Z.); (J.L.); (H.L.)
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yunfeng Li
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, South China Agricultural University, Guangzhou 510642, China; (Y.H.); (X.Z.); (J.L.); (H.L.)
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China
| | - Yanfang Nie
- College of Materials and Energy, South China Agricultural University, Guangzhou 510642, China
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5
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The Pleiades are a cluster of fungal effectors that inhibit host defenses. PLoS Pathog 2021; 17:e1009641. [PMID: 34166468 PMCID: PMC8224859 DOI: 10.1371/journal.ppat.1009641] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 05/13/2021] [Indexed: 01/07/2023] Open
Abstract
Biotrophic plant pathogens secrete effector proteins to manipulate the host physiology. Effectors suppress defenses and induce an environment favorable to disease development. Sequence-based prediction of effector function is impeded by their rapid evolution rate. In the maize pathogen Ustilago maydis, effector-coding genes frequently organize in clusters. Here we describe the functional characterization of the pleiades, a cluster of ten effector genes, by analyzing the micro- and macroscopic phenotype of the cluster deletion and expressing these proteins in planta. Deletion of the pleiades leads to strongly impaired virulence and accumulation of reactive oxygen species (ROS) in infected tissue. Eight of the Pleiades suppress the production of ROS upon perception of pathogen associated molecular patterns (PAMPs). Although functionally redundant, the Pleiades target different host components. The paralogs Taygeta1 and Merope1 suppress ROS production in either the cytoplasm or nucleus, respectively. Merope1 targets and promotes the auto-ubiquitination activity of RFI2, a conserved family of E3 ligases that regulates the production of PAMP-triggered ROS burst in plants.
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6
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Kanja C, Hammond‐Kosack KE. Proteinaceous effector discovery and characterization in filamentous plant pathogens. MOLECULAR PLANT PATHOLOGY 2020; 21:1353-1376. [PMID: 32767620 PMCID: PMC7488470 DOI: 10.1111/mpp.12980] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/03/2020] [Accepted: 07/05/2020] [Indexed: 05/26/2023]
Abstract
The complicated interplay of plant-pathogen interactions occurs on multiple levels as pathogens evolve to constantly evade the immune responses of their hosts. Many economically important crops fall victim to filamentous pathogens that produce small proteins called effectors to manipulate the host and aid infection/colonization. Understanding the effector repertoires of pathogens is facilitating an increased understanding of the molecular mechanisms underlying virulence as well as guiding the development of disease control strategies. The purpose of this review is to give a chronological perspective on the evolution of the methodologies used in effector discovery from physical isolation and in silico predictions, to functional characterization of the effectors of filamentous plant pathogens and identification of their host targets.
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Affiliation(s)
- Claire Kanja
- Department of Biointeractions and Crop ProtectionRothamsted ResearchHarpendenUK
- School of BiosciencesUniversity of NottinghamNottinghamUK
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7
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Montenegro Alonso AP, Ali S, Song X, Linning R, Bakkeren G. UhAVR1, an HR-Triggering Avirulence Effector of Ustilago hordei, Is Secreted via the ER-Golgi Pathway, Localizes to the Cytosol of Barley Cells during in Planta-Expression, and Contributes to Virulence Early in Infection. J Fungi (Basel) 2020; 6:E178. [PMID: 32961976 PMCID: PMC7559581 DOI: 10.3390/jof6030178] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 09/15/2020] [Accepted: 09/15/2020] [Indexed: 12/19/2022] Open
Abstract
The basidiomycete Ustilago hordei causes covered smut disease of barley and oats. Virulence effectors promoting infection and supporting pathogen lifestyle have been described for this fungus. Genetically, six avirulence genes are known and one codes for UhAVR1, the only proven avirulence effector identified in smuts to date that triggers complete immunity in barley cultivars carrying resistance gene Ruh1. A prerequisite for resistance breeding is understanding the host targets and molecular function of UhAVR1. Analysis of this effector upon natural infection of barley coleoptiles using teliospores showed that UhAVR1 is expressed during the early stages of fungal infection where it leads to HR triggering in resistant cultivars or performs its virulence function in susceptible cultivars. Fungal secretion of UhAVR1 is directed by its signal peptide and occurs via the BrefeldinA-sensitive ER-Golgi pathway in cell culture away from its host. Transient in planta expression of UhAVR1 in barley and a nonhost, Nicotiana benthamiana, supports a cytosolic localization. Delivery of UhAVR1 via foxtail mosaic virus or Pseudomonas species in both barley and N. benthamiana reveals a role in suppressing components common to both plant systems of Effector- and Pattern-Triggered Immunity, including necrosis triggered by Agrobacterium-delivered cell death inducers.
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Affiliation(s)
- Ana Priscilla Montenegro Alonso
- Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada;
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre, Summerland, BC V0H 1Z0, Canada;
| | - Shawkat Ali
- Agriculture and Agri-Food Canada, Kentville Research and Development Centre, Kentville, NS B4N 1J5, Canada;
| | - Xiao Song
- Sandstone Pharmacies Glenmore Landing Calgary-Compounding, 167D, 1600–90 Ave SW Calgary, AB T2V 5A8, Canada;
| | - Rob Linning
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre, Summerland, BC V0H 1Z0, Canada;
| | - Guus Bakkeren
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre, Summerland, BC V0H 1Z0, Canada;
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Tanaka S, Gollin I, Rössel N, Kahmann R. The functionally conserved effector Sta1 is a fungal cell wall protein required for virulence in Ustilago maydis. THE NEW PHYTOLOGIST 2020; 227:185-199. [PMID: 32112567 DOI: 10.1111/nph.16508] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 02/18/2020] [Indexed: 06/10/2023]
Abstract
The biotrophic fungus Ustilago maydis causes the smut disease of maize. The interaction with its host and induction of characteristic tumors are governed largely by secreted effectors whose function is mostly unknown. To identify effectors with a prominent role in virulence, we used RNA sequencing and found that the gene sta1 is upregulated during early stages of infection. We characterized Sta1 by comparative genomics, reverse genetics, protein localization, stress assays, and microscopy. sta1 mutants show a dramatic reduction of virulence and show altered colonization of tissue neighboring the vascular bundles. Functional orthologues of Sta1 are found in related smut pathogens infecting monocot and dicot plants. Sta1 is secreted by budding cells but is attached to the cell wall of filamentous hyphae. Upon constitutive expression of Sta1, fungal filaments become susceptible to Congo red, β-glucanase, and chitinase, suggesting that Sta1 alters the structure of the fungal cell wall. Constitutive or delayed expression of sta1 during plant colonization negatively impacts on virulence. Our results suggest that Sta1 is a novel kind of effector, which needs to modify the hyphal cell wall to allow hyphae to be accommodated in tissue next to the vascular bundles.
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Affiliation(s)
- Shigeyuki Tanaka
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, D-35043, Marburg, Germany
| | - Isabelle Gollin
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, D-35043, Marburg, Germany
| | - Nicole Rössel
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, D-35043, Marburg, Germany
| | - Regine Kahmann
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, D-35043, Marburg, Germany
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Lee HY, Lee SE, Woo J, Choi D, Park E. Split Green Fluorescent Protein System to Visualize Effectors Delivered from Bacteria During Infection. J Vis Exp 2018. [PMID: 29889187 DOI: 10.3791/57719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Bacteria, one of the most important causative agents of various plant diseases, secrete a set of effector proteins into the host plant cell to subvert the plant immune system. During infection cytoplasmic effectors are delivered to the host cytosol via a type III secretion system (T3SS). After delivery into the plant cell, the effector(s) targets the specific compartment(s) to modulate host cell processes for survival and replication of the pathogen. Although there has been some research on the subcellular localization of effector proteins in the host cells to understand their function in pathogenicity by using fluorescent proteins, investigation of the dynamics of effectors directly injected from bacteria has been challenging due to the incompatibility between the T3SS and fluorescent proteins. Here, we describe our recent method of an optimized split superfolder green fluorescent protein system (sfGFPOPT) to visualize the localization of effectors delivered via the bacterial T3SS in the host cell. The sfGFP11 (11th β-strand of sfGFP)-tagged effector secreted through the T3SS can be assembled with a specific organelle targeted sfGFP1-10OPT (1-10th β-strand of sfGFP) leading to fluorescence emission at the site. This protocol provides a procedure to visualize the reconstituted sfGFP fluorescence signal with an effector protein from Pseudomonas syringae in a particular organelle in the Arabidopsis and Nicotiana benthamiana plants.
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Affiliation(s)
- Hye-Young Lee
- Department of Plant Science, Plant Genomics and Breeding Institute, College of Agriculture and Life Science, Seoul National University
| | - So Eui Lee
- Department of Plant Science, Plant Genomics and Breeding Institute, College of Agriculture and Life Science, Seoul National University
| | - Jongchan Woo
- Department of Bioindustry and Bioresource Engineering, Sejong University
| | - Doil Choi
- Department of Plant Science, Plant Genomics and Breeding Institute, College of Agriculture and Life Science, Seoul National University;
| | - Eunsook Park
- Department of Plant Science, Plant Genomics and Breeding Institute, College of Agriculture and Life Science, Seoul National University;
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10
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Oeser B, Kind S, Schurack S, Schmutzer T, Tudzynski P, Hinsch J. Cross-talk of the biotrophic pathogen Claviceps purpurea and its host Secale cereale. BMC Genomics 2017; 18:273. [PMID: 28372538 PMCID: PMC5379732 DOI: 10.1186/s12864-017-3619-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/10/2017] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The economically important Ergot fungus Claviceps purpurea is an interesting biotrophic model system because of its strict organ specificity (grass ovaries) and the lack of any detectable plant defense reactions. Though several virulence factors were identified, the exact infection mechanisms are unknown, e.g. how the fungus masks its attack and if the host detects the infection at all. RESULTS We present a first dual transcriptome analysis using an RNA-Seq approach. We studied both, fungal and plant gene expression in young ovaries infected by the wild-type and two virulence-attenuated mutants. We can show that the plant recognizes the fungus, since defense related genes are upregulated, especially several phytohormone genes. We present a survey of in planta expressed fungal genes, among them several confirmed virulence genes. Interestingly, the set of most highly expressed genes includes a high proportion of genes encoding putative effectors, small secreted proteins which might be involved in masking the fungal attack or interfering with host defense reactions. As known from several other phytopathogens, the C. purpurea genome contains more than 400 of such genes, many of them clustered and probably highly redundant. Since the lack of effective defense reactions in spite of recognition of the fungus could very well be achieved by effectors, we started a functional analysis of some of the most highly expressed candidates. However, the redundancy of the system made the identification of a drastic effect of a single gene most unlikely. We can show that at least one candidate accumulates in the plant apoplast. Deletion of some candidates led to a reduced virulence of C. purpurea on rye, indicating a role of the respective proteins during the infection process. CONCLUSIONS We show for the first time that- despite the absence of effective plant defense reactions- the biotrophic pathogen C. purpurea is detected by its host. This points to a role of effectors in modulation of the effective plant response. Indeed, several putative effector genes are among the highest expressed genes in planta.
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Affiliation(s)
- Birgitt Oeser
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, D-48143 Münster, Germany
| | - Sabine Kind
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, D-48143 Münster, Germany
| | - Selma Schurack
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, D-48143 Münster, Germany
| | - Thomas Schmutzer
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Paul Tudzynski
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, D-48143 Münster, Germany
| | - Janine Hinsch
- Institut für Biologie und Biotechnologie der Pflanzen, Westfälische Wilhelms-Universität, D-48143 Münster, Germany
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Lo Presti L, Zechmann B, Kumlehn J, Liang L, Lanver D, Tanaka S, Bock R, Kahmann R. An assay for entry of secreted fungal effectors into plant cells. THE NEW PHYTOLOGIST 2017; 213:956-964. [PMID: 27716942 DOI: 10.1111/nph.14188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/05/2016] [Indexed: 05/23/2023]
Abstract
Successful colonization of plants by prokaryotic and eukaryotic pathogens requires active effector-mediated suppression of defense responses and host tissue reprogramming. Secreted effector proteins can either display their activity in the apoplast or translocate into host cells and function therein. Although characterized in bacteria, the molecular mechanisms of effector delivery by fungal phytopathogens remain elusive. Here we report the establishment of an assay that is based on biotinylation of effectors in the host cytoplasm as hallmark of uptake. The assay exploits the ability of the bacterial biotin ligase BirA to biotinylate any protein that carries a short peptide (Avitag). It is based on the stable expression of BirA in the cytoplasm of maize plants and on engineering of Ustilago maydis strains to secrete Avitagged effectors. We demonstrate translocation of a number of effectors in the U. maydis-maize system and show data that suggest that the uptake mechanism could be rather nonspecific The assay promises to be a powerful tool for the classification of effectors as well as for the functional study of effector uptake mechanism not only in the chosen system but more generally for systems where biotrophic interactions are established.
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Affiliation(s)
- Libera Lo Presti
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Bernd Zechmann
- Center for Microscopy and Imaging, Baylor University, One Bear Place #97046, Waco, TX, 76798-7046, USA
| | - Jochen Kumlehn
- Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstrasse 3, 06466, Stadt Seeland, Germany
| | - Liang Liang
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Daniel Lanver
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Shigeyuki Tanaka
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
| | - Ralph Bock
- Department of Organelle Biology, Biotechnology and Molecular Ecophysiology, Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Regine Kahmann
- Department of Organismic Interactions, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, 35043, Marburg, Germany
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12
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De Wit PJGM. Apoplastic fungal effectors in historic perspective; a personal view. THE NEW PHYTOLOGIST 2016; 212:805-813. [PMID: 27523582 DOI: 10.1111/nph.14144] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- Pierre J G M De Wit
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, the Netherlands
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13
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Sonah H, Deshmukh RK, Bélanger RR. Computational Prediction of Effector Proteins in Fungi: Opportunities and Challenges. FRONTIERS IN PLANT SCIENCE 2016; 7:126. [PMID: 26904083 PMCID: PMC4751359 DOI: 10.3389/fpls.2016.00126] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/23/2016] [Indexed: 05/20/2023]
Abstract
Effector proteins are mostly secretory proteins that stimulate plant infection by manipulating the host response. Identifying fungal effector proteins and understanding their function is of great importance in efforts to curb losses to plant diseases. Recent advances in high-throughput sequencing technologies have facilitated the availability of several fungal genomes and 1000s of transcriptomes. As a result, the growing amount of genomic information has provided great opportunities to identify putative effector proteins in different fungal species. There is little consensus over the annotation and functionality of effector proteins, and mostly small secretory proteins are considered as effector proteins, a concept that tends to overestimate the number of proteins involved in a plant-pathogen interaction. With the characterization of Avr genes, criteria for computational prediction of effector proteins are becoming more efficient. There are 100s of tools available for the identification of conserved motifs, signature sequences and structural features in the proteins. Many pipelines and online servers, which combine several tools, are made available to perform genome-wide identification of effector proteins. In this review, available tools and pipelines, their strength and limitations for effective identification of fungal effector proteins are discussed. We also present an exhaustive list of classically secreted proteins along with their key conserved motifs found in 12 common plant pathogens (11 fungi and one oomycete) through an analytical pipeline.
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Affiliation(s)
| | | | - Richard R. Bélanger
- Département de Phytologie, Faculté des Sciences de l’Agriculture et de l’Alimentation, Centre de Recherche en Horticulture, Université Laval, QuébecQC, Canada
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