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Schuster M, Schweizer G, Reißmann S, Happel P, Aßmann D, Rössel N, Güldener U, Mannhaupt G, Ludwig N, Winterberg S, Pellegrin C, Tanaka S, Vincon V, Presti LL, Wang L, Bender L, Gonzalez C, Vranes M, Kämper J, Seong K, Krasileva K, Kahmann R. Novel Secreted Effectors Conserved Among Smut Fungi Contribute to the Virulence of Ustilago maydis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2024; 37:250-263. [PMID: 38416124 DOI: 10.1094/mpmi-09-23-0139-fi] [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] [Indexed: 02/29/2024]
Abstract
Fungal pathogens deploy a set of molecules (proteins, specialized metabolites, and sRNAs), so-called effectors, to aid the infection process. In comparison to other plant pathogens, smut fungi have small genomes and secretomes of 20 Mb and around 500 proteins, respectively. Previous comparative genomic studies have shown that many secreted effector proteins without known domains, i.e., novel, are conserved only in the Ustilaginaceae family. By analyzing the secretomes of 11 species within Ustilaginaceae, we identified 53 core homologous groups commonly present in this lineage. By collecting existing mutants and generating additional ones, we gathered 44 Ustilago maydis strains lacking single core effectors as well as 9 strains containing multiple deletions of core effector gene families. Pathogenicity assays revealed that 20 of these 53 mutant strains were affected in virulence. Among the 33 mutants that had no obvious phenotypic changes, 13 carried additional, sequence-divergent, structurally similar paralogs. We report a virulence contribution of seven previously uncharacterized single core effectors and of one effector family. Our results help to prioritize effectors for understanding U. maydis virulence and provide genetic resources for further characterization. [Formula: see text] Copyright © 2024 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)
- Mariana Schuster
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120 Halle, Germany
| | - Gabriel Schweizer
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Independent Data Lab UG, 80937 Munich, Germany
| | - Stefanie Reißmann
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Petra Happel
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Daniela Aßmann
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Nicole Rössel
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Ulrich Güldener
- Deutsches Herzzentrum München, Technische Universität München, 80636 München, Germany
| | - Gertrud Mannhaupt
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Nicole Ludwig
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Research & Development, Weed Control Bayer AG, Crop Science Division, 65926 Frankfurt am Main, Germany
| | - Sarah Winterberg
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Clément Pellegrin
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Shigeyuki Tanaka
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Volker Vincon
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Libera Lo Presti
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Lei Wang
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Lena Bender
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
- Department of Pharmaceutics and Biopharmaceutics, Phillips-University Marburg, 35037 Marburg, Germany
| | - Carla Gonzalez
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Miroslav Vranes
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, 76131 Karlsruhe, Germany
| | - Jörg Kämper
- Karlsruhe Institute of Technology, Institute for Applied Biosciences, Department of Genetics, 76131 Karlsruhe, Germany
| | - Kyungyong Seong
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, U.S.A
| | - Ksenia Krasileva
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, U.S.A
| | - Regine Kahmann
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
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Ökmen B, Katzy P, Huang L, Wemhöner R, Doehlemann G. A conserved extracellular Ribo1 with broad-spectrum cytotoxic activity enables smut fungi to compete with host-associated bacteria. THE NEW PHYTOLOGIST 2023; 240:1976-1989. [PMID: 37680042 DOI: 10.1111/nph.19244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 08/14/2023] [Indexed: 09/09/2023]
Abstract
Ribotoxins are secreted ribonucleases that specifically target and cleave the universally conserved sarcin-ricin loop sequence of rRNA, which leads to inhibition of protein biosynthesis and subsequently to cell death. We have identified and characterized a secreted Ribo1 protein of plant pathogenic smut fungi. Heterologous expression in different model systems showed that smut Ribo1 has cytotoxic activity against bacteria, yeast, host and nonhost plants. Recombinant expression of Ribo1 in Nicotiana benthamiana induced plant cell death; however, an active site mutant induced cell death only when expressed as a secreted protein. In the maize smut Ustilago maydis, transcription of Ribo1 is specifically induced in early infection stages. While a knockout mutant revealed that Ribo1 is dispensable for U. maydis virulence, the overexpression of Ribo1 in planta had a strong dominant negative effect on virulence and induced host defense responses including cell death. Our findings suggest a function of Ribo1 during the epiphytic development rather than for invasive colonization of the host. Accordingly, in the presence of the biocontrol bacteria Pantoea sp., which were isolated from maize leaves, the ribo1 knockout mutant was significantly impaired in virulence. Together, we conclude that Ribo1 enables smut fungi to compete with host-associated bacteria during epiphytic development.
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Affiliation(s)
- Bilal Ökmen
- Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Center for Molecular Biosciences, 50674, Cologne, Germany
- Department of Microbial Interactions, IMIT/ZMBP, University of Tübingen, 72076, Tübingen, Germany
| | - Philipp Katzy
- Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Center for Molecular Biosciences, 50674, Cologne, Germany
| | - Luyao Huang
- Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Center for Molecular Biosciences, 50674, Cologne, Germany
| | - Raphael Wemhöner
- Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Center for Molecular Biosciences, 50674, Cologne, Germany
| | - Gunther Doehlemann
- Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Center for Molecular Biosciences, 50674, Cologne, Germany
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Magnaporthe oryzae pathotype Triticum (MoT) can act as a heterologous expression system for fungal effectors with high transcript abundance in wheat. Sci Rep 2023; 13:108. [PMID: 36596834 PMCID: PMC9810704 DOI: 10.1038/s41598-022-27030-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 12/23/2022] [Indexed: 01/04/2023] Open
Abstract
Plant pathogens deliver effector proteins to reprogramme a host plants circuitry, supporting their own growth and development, whilst thwarting defence responses. A subset of these effectors are termed avirulence factors (Avr) and can be recognised by corresponding host resistance (R) proteins, creating a strong evolutionary pressure on pathogen Avr effectors that favours their modification/deletion to evade the immune response. Hence, identifying Avr effectors and tracking their allele frequencies in a population is critical for understanding the loss of host recognition. However, the current systems available to confirm Avr effector function, particularly for obligate biotrophic fungi, remain limited and challenging. Here, we explored the utility of the genetically tractable wheat blast pathogen Magnaporthe oryzae pathotype Triticum (MoT) as a suitable heterologous expression system in wheat. Using the recently confirmed wheat stem rust pathogen (Puccina graminis f. sp. tritici) avirulence effector AvrSr50 as a proof-of-concept, we found that delivery of AvrSr50 via MoT could elicit a visible Sr50-dependant cell death phenotype. However, activation of Sr50-mediated cell death correlated with a high transgene copy number and transcript abundance in MoT transformants. This illustrates that MoT can act as an effective heterologous delivery system for fungal effectors from distantly related fungal species, but only when enough transgene copies and/or transcript abundance is achieved.
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Elhamouly NA, Hewedy OA, Zaitoon A, Miraples A, Elshorbagy OT, Hussien S, El-Tahan A, Peng D. The hidden power of secondary metabolites in plant-fungi interactions and sustainable phytoremediation. FRONTIERS IN PLANT SCIENCE 2022; 13:1044896. [PMID: 36578344 PMCID: PMC9790997 DOI: 10.3389/fpls.2022.1044896] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 11/16/2022] [Indexed: 06/17/2023]
Abstract
The global environment is dominated by various small exotic substances, known as secondary metabolites, produced by plants and microorganisms. Plants and fungi are particularly plentiful sources of these molecules, whose physiological functions, in many cases, remain a mystery. Fungal secondary metabolites (SM) are a diverse group of substances that exhibit a wide range of chemical properties and generally fall into one of four main family groups: Terpenoids, polyketides, non-ribosomal peptides, or a combination of the latter two. They are incredibly varied in their functions and are often related to the increased fitness of the respective fungus in its environment, often competing with other microbes or interacting with plant species. Several of these metabolites have essential roles in the biological control of plant diseases by various beneficial microorganisms used for crop protection and biofertilization worldwide. Besides direct toxic effects against phytopathogens, natural metabolites can promote root and shoot development and/or disease resistance by activating host systemic defenses. The ability of these microorganisms to synthesize and store biologically active metabolites that are a potent source of novel natural compounds beneficial for agriculture is becoming a top priority for SM fungi research. In this review, we will discuss fungal-plant secondary metabolites with antifungal properties and the role of signaling molecules in induced and acquired systemic resistance activities. Additionally, fungal secondary metabolites mimic plant promotion molecules such as auxins, gibberellins, and abscisic acid, which modulate plant growth under biotic stress. Moreover, we will present a new trend regarding phytoremediation applications using fungal secondary metabolites to achieve sustainable food production and microbial diversity in an eco-friendly environment.
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Affiliation(s)
- Neveen Atta Elhamouly
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- Department of Botany, Faculty of Agriculture, Menoufia University, Shibin El-Kom, Egypt
| | - Omar A. Hewedy
- Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada
| | - Amr Zaitoon
- Department of Food Science, University of Guelph, Guelph, ON, Canada
| | - Angelica Miraples
- Department of Plant Agriculture, University of Guelph, Guelph, ON, Canada
| | - Omnia T. Elshorbagy
- School of Natural and Environmental Sciences, Faculty of Science, Agriculture & Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Suzan Hussien
- Botany Department Faculty of Science, Mansoura University, Mansoura, Egypt
| | - Amira El-Tahan
- Plant Production Department, Arid Lands Cultivation Research Institute, the City of Scientific Research and Technological Applications, City of Scientific Research and Technological Applications (SRTA-City), Borg El Arab, Alexandria, Egypt
| | - Deliang Peng
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
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A conserved enzyme of smut fungi facilitates cell-to-cell extension in the plant bundle sheath. Nat Commun 2022; 13:6003. [PMID: 36224193 PMCID: PMC9556619 DOI: 10.1038/s41467-022-33815-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 10/04/2022] [Indexed: 12/01/2022] Open
Abstract
Smut fungi comprise one of the largest groups of fungal plant pathogens causing disease in all cereal crops. They directly penetrate host tissues and establish a biotrophic interaction. To do so, smut fungi secrete a wide range of effector proteins, which suppress plant immunity and modulate cellular functions as well as development of the host, thereby determining the pathogen’s lifestyle and virulence potential. The conserved effector Erc1 (enzyme required for cell-to-cell extension) contributes to virulence of the corn smut Ustilago maydis in maize leaves but not on the tassel. Erc1 binds to host cell wall components and displays 1,3-β-glucanase activity, which is required to attenuate β-glucan-induced defense responses. Here we show that Erc1 has a cell type-specific virulence function, being necessary for fungal cell-to-cell extension in the plant bundle sheath and this function is fully conserved in the Erc1 orthologue of the barley pathogen Ustilago hordei. Smut fungi secrete effector proteins that suppress host plant immunity. Here the authors show that the corn smut effector Erc1 has 1,3-β-glucanase activity and promotes virulence in maize leaves by attenuating β-glucan-induced defense responses.
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Maia T, Rody HVS, Bombardelli RGH, Souto TG, Camargo LEA, Monteiro-Vitorello CB. A Bacterial Type Three Secretion-Based Delivery System for Functional Characterization of Sporisorium scitamineum Plant Immune Suppressing Effector Proteins. PHYTOPATHOLOGY 2022; 112:1513-1523. [PMID: 35050679 DOI: 10.1094/phyto-08-21-0326-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The facultative biotrophic basidiomycete Sporisorium scitamineum causes smut disease in sugarcane. This study applied an assay to identify S. scitamineum candidate effectors (CEs) with plant immunity suppression activities by delivering them into Nicotiana benthamiana cells via the type-three secretion system of Pseudomonas fluorescens EtHAn. Six CEs were individually cloned into the pEDV6 vector and expressed by P. fluorescens EtHAn for translocation into the plant cells. Three CEs (g1052, g3890, and g5159) could suppress pattern-triggered immunity (PTI) responses with high reproducibility in different coinfiltration experiments with P. syringae pv. tomato DC3000. In addition, three CEs (g1052, g4549, and g5159) were also found to be AvrB-induced suppressors of effector-triggered immunity (ETI), demonstrating for the first time that S. scitamineum can defeat both PTI and ETI responses. A transcriptomic analysis at different stages of infection by the smut fungus of three sugarcane cultivars with contrasting responses to the pathogen revealed that suppressors g1052, g3890, g4549, and g5159 were induced at the early stage of infection. By contrast, the two CEs (g2666 and g6610) that did not exhibit suppression activities expressed only at the late stage of infection. Moreover, genomic structures of the CEs and searches for orthologs in other smut species suggested duplication events and further divergence in CEs evolution of S. scitamineum. Thus, the transient assay applied here demonstrated the potential of pEDV6 and P. fluorescens EtHAn as biological tools for identifying plant immune suppressors from S. scitamineum.
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Affiliation(s)
- Thiago Maia
- Departamento de Fitopatologia e Nematologia, Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Piracicaba, SP, Brazil
- Departamento de Genética, USP, ESALQ, Piracicaba, SP, Brazil
| | - Hugo V S Rody
- Departamento de Genética, USP, ESALQ, Piracicaba, SP, Brazil
| | | | - Tiarla Graciane Souto
- Departamento de Fitopatologia e Nematologia, Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Piracicaba, SP, Brazil
- Departamento de Genética, USP, ESALQ, Piracicaba, SP, Brazil
| | - Luis Eduardo Aranha Camargo
- Departamento de Fitopatologia e Nematologia, Universidade de São Paulo (USP), Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Piracicaba, SP, Brazil
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Smuts to the Power of Three: Biotechnology, Biotrophy, and Basic Biology. J Fungi (Basel) 2021; 7:jof7080660. [PMID: 34436199 PMCID: PMC8401932 DOI: 10.3390/jof7080660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 08/10/2021] [Indexed: 11/26/2022] Open
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Perspectives for the application of Ustilaginaceae as biotech cell factories. Essays Biochem 2021; 65:365-379. [PMID: 33860800 DOI: 10.1042/ebc20200141] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/15/2021] [Accepted: 03/17/2021] [Indexed: 01/05/2023]
Abstract
Basidiomycetes fungi of the family Ustilaginaceae are mainly known as plant pathogens causing smut disease on crops and grasses. However, they are also natural producers of value-added substances like glycolipids, organic acids, polyols, and harbor secretory enzymes with promising hydrolytic activities. These attributes recently evoked increasing interest in their biotechnological exploitation. The corn smut fungus Ustilago maydis is the best characterized member of the Ustilaginaceae. After decades of research in the fields of genetics and plant pathology, a broad method portfolio and detailed knowledge on its biology and biochemistry are available. As a consequence, U. maydis has developed into a versatile model organism not only for fundamental research but also for applied biotechnology. Novel genetic, synthetic biology, and process development approaches have been implemented to engineer yields and product specificity as well as for the expansion of the repertoire of produced substances. Furthermore, research on U. maydis also substantially promoted the interest in other members of the Ustilaginaceae, for which the available tools can be adapted. Here, we review the latest developments in applied research on Ustilaginaceae towards their establishment as future biotech cell factories.
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