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Beernink BM, Whitham SA. Foxtail mosaic virus: A tool for gene function analysis in maize and other monocots. MOLECULAR PLANT PATHOLOGY 2023; 24:811-822. [PMID: 37036421 PMCID: PMC10257046 DOI: 10.1111/mpp.13330] [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: 10/31/2022] [Revised: 02/20/2023] [Accepted: 03/08/2023] [Indexed: 06/11/2023]
Abstract
Many plant viruses have been engineered into vectors for use in functional genomics studies, expression of heterologous proteins, and, most recently, gene editing applications. The use of viral vectors overcomes bottlenecks associated with mutagenesis and transgenesis approaches often implemented for analysis of gene function. There are several engineered viruses that are demonstrated or suggested to be useful in maize through proof-of-concept studies. However, foxtail mosaic virus (FoMV), which has a relatively broad host range, is emerging as a particularly useful virus for gene function studies in maize and other monocot crop or weed species. A few clones of FoMV have been independently engineered, and they have different features and capabilities for virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) of proteins. In addition, FoMV can be used to deliver functional guide RNAs in maize and other plants expressing the Cas9 protein, demonstrating its potential utility in virus-induced gene editing applications. There is a growing number of studies in which FoMV vectors are being applied for VIGS or VOX in maize and the vast majority of these are related to maize-microbe interactions. In this review, we highlight the biology and engineering of FoMV as well as its applications in maize-microbe interactions and more broadly in the context of the monocot functional genomics toolbox.
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Affiliation(s)
- Bliss M. Beernink
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
- Department of BiologyUniversity of ManitobaWinnipegManitobaCanada
| | - Steven A. Whitham
- Department of Plant Pathology, Entomology, and MicrobiologyIowa State UniversityAmesIowaUSA
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Montenegro Alonso AP, Bakkeren G. Transfection of Barley Leaf Protoplasts with a Fluorescently Tagged Fungal Effector for In Planta Localization Studies in Barley. Methods Mol Biol 2023; 2659:83-93. [PMID: 37249887 DOI: 10.1007/978-1-0716-3159-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The isolation and transfection of protoplasts from plant leaves have been routinely used for transient expression and functional studies in model plants. However, current approaches to characterize pathogen effector molecules in a cereal host are inefficient and technically challenging. In this chapter, we describe a protocol to isolate and transfect barley mesophyll protoplasts with a fluorescently tagged fungal effector of the barley smut pathogen Ustilago hordei. Tagging of a fungal effector with a fluorescent protein and tracking its localization in cells of its natural host provides insight into its putative in planta localization and helps to narrow down the location of putative host interactors.
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Affiliation(s)
- Ana Priscilla Montenegro Alonso
- Department of Botany, University of British Columbia, Vancouver, BC, Canada
- Saskatoon Research and Development Centre, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada
| | - Guus Bakkeren
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC, Canada.
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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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Miltenburg MG, Bonner C, Hepworth S, Huang M, Rampitsch C, Subramaniam R. Proximity-dependent biotinylation identifies a suite of candidate effector proteins from Fusarium graminearum. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 112:369-382. [PMID: 35986640 DOI: 10.1111/tpj.15949] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 06/15/2023]
Abstract
Fusarium graminearum is a fungal pathogen that causes Fusarium head blight in cereal crops. The identification of proteins secreted from pathogens to overcome plant defenses and cause disease, collectively known as effectors, can reveal the etiology of a disease process. Proximity-dependent biotin identification (BioID) was used to identify potential effector proteins secreted in planta by F. graminearum during the infection of Arabidopsis. Mass spectrometry analysis of streptavidin affinity-purified proteins revealed over 300 proteins from F. graminearum, of which 62 were candidate effector proteins (CEPs). An independent analysis of secreted proteins from axenic cultures of F. graminearum showed a 42% overlap with CEPs, thereby assuring confidence in the BioID methodology. The analysis also revealed that 19 out of 62 CEPs (approx. 30%) had been previously characterized with virulence function in fungi. The functional characterization of additional CEPs was undertaken through deletion analysis by the CRISPR/Cas9 method, and by overexpression into Triticum aestivum (wheat) leaves by the Ustilago hordei delivery system. Deletion studies of 12 CEPs confirmed the effector function of three previously characterized CEPs and validated the function of another four CEPs on wheat inflorescence or vegetative tissues. Lastly, overexpression in wheat showed that all seven CEPs enhanced resistance against the bacterial pathogen Pseudomonas syringae DC3000.
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Affiliation(s)
- Mary G Miltenburg
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
- Ottawa Research and Development Centre, Agriculture Canada, 960 Carling Avenue, Ottawa, ON, K1S 5B6, Canada
| | - Christopher Bonner
- Ottawa Research and Development Centre, Agriculture Canada, 960 Carling Avenue, Ottawa, ON, K1S 5B6, Canada
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada
| | - Shelley Hepworth
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Mei Huang
- Morden Research and Development Centre, Agriculture Canada, 101 Route 100, Morden, MB, R6M 1Y5, Canada
| | - Christof Rampitsch
- Morden Research and Development Centre, Agriculture Canada, 101 Route 100, Morden, MB, R6M 1Y5, Canada
| | - Rajagopal Subramaniam
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
- Ottawa Research and Development Centre, Agriculture Canada, 960 Carling Avenue, Ottawa, ON, K1S 5B6, Canada
- Department of Cell and Systems Biology, University of Toronto, 25 Harbord Street, Toronto, ON, M5S 3G5, Canada
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The Sporisorium reilianum Effector Vag2 Promotes Head Smut Disease via Suppression of Plant Defense Responses. J Fungi (Basel) 2022; 8:jof8050498. [PMID: 35628753 PMCID: PMC9146561 DOI: 10.3390/jof8050498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/09/2022] [Accepted: 05/10/2022] [Indexed: 01/27/2023] Open
Abstract
Genome comparison between the maize pathogens Ustilago maydis and Sporisorium reilianum revealed a large diversity region (19-1) containing nearly 30 effector gene candidates, whose deletion severely hampers virulence of both fungi. Dissection of the S. reilianum gene cluster resulted in the identification of one major contributor to virulence, virulence-associated gene 2 (vag2; sr10050). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) experiments revealed high expression of vag2 during biotrophic growth of S. reilianum. Using the yeast secretion trap assay, we confirmed the existence of a functional signal peptide allowing protein secretion via the conventional secretory pathway. We identified the cytoplasmic maize chorismate mutase ZmCM2 by yeast two-hybrid screening as a possible interaction partner of Vag2. Interaction of the two proteins in planta was confirmed by bimolecular fluorescence complementation. qRT-PCR experiments revealed vag2-dependent downregulation of salicylic acid (SA)-induced genes, which correlated with higher SA levels in plant tissues colonized by Δvag2 deletion strains relative to S. reilianum wildtype strains. Metabolite analysis suggested rewiring of pathogen-induced SA biosynthesis by preferential conversion of the SA precursor chorismate into the aromatic amino acid precursor prephenate by ZmCM2 in the presence of Vag2. Possibly, the binding of Vag2 to ZmCM2 inhibits the back reaction of the ZmCM2-catalyzed interconversion of chorismate and prephenate, thus contributing to fungal virulence by lowering the plant SA-induced defenses.
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Kanyuka K. Virus-Mediated Protein Overexpression (VOX) in Monocots to Identify and Functionally Characterize Fungal Effectors. Methods Mol Biol 2022; 2523:93-112. [PMID: 35759193 DOI: 10.1007/978-1-0716-2449-4_7] [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] [Indexed: 06/15/2023]
Abstract
One of the important armories that pathogens utilize to successfully colonize the plants is small secreted effector proteins, which could perform a variety of functions from suppression of plant innate immunity to manipulation of plant physiology in favor of the disease. Plants, on the other hand, evolved disease resistance genes that recognize some of the effectors or avirulence (Avr) proteins. Both, identification of the Avr proteins and understanding of the mechanisms of action of other effectors, are important areas of research in the molecular plant-pathogen interactions field as this knowledge is critical for the development of new effective pathogen control measures. To enable functional analysis of the effectors, it is desirable to be able to overexpress them readily in the host plants. Here we describe detailed experimental protocols for transient effector overexpression in wheat and other monocots using binary Barley stripe mosaic virus (BSMV)- and Foxtail mosaic virus (FoMV)-derived vectors. This functional genomics tool, better known as VOX (Virus-mediated protein OvereXpression), is rapid and relatively simple and inexpensive.
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Affiliation(s)
- Kostya Kanyuka
- Plant Pathology and Entomology, NIAB, Cambridge, UK.
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, UK.
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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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Ökmen B, Schwammbach D, Bakkeren G, Neumann U, Doehlemann G. The Ustilago hordei-Barley Interaction Is a Versatile System for Characterization of Fungal Effectors. J Fungi (Basel) 2021; 7:86. [PMID: 33513785 PMCID: PMC7912019 DOI: 10.3390/jof7020086] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/19/2021] [Accepted: 01/22/2021] [Indexed: 12/02/2022] Open
Abstract
Obligate biotrophic fungal pathogens, such as Blumeria graminis and Puccinia graminis, are amongst the most devastating plant pathogens, causing dramatic yield losses in many economically important crops worldwide. However, a lack of reliable tools for the efficient genetic transformation has hampered studies into the molecular basis of their virulence or pathogenicity. In this study, we present the Ustilago hordei-barley pathosystem as a model to characterize effectors from different plant pathogenic fungi. We generate U. hordei solopathogenic strains, which form infectious filaments without the presence of a compatible mating partner. Solopathogenic strains are suitable for heterologous expression system for fungal virulence factors. A highly efficient Crispr/Cas9 gene editing system is made available for U. hordei. In addition, U. hordei infection structures during barley colonization are analyzed using transmission electron microscopy, showing that U. hordei forms intracellular infection structures sharing high similarity to haustoria formed by obligate rust and powdery mildew fungi. Thus, U. hordei has high potential as a fungal expression platform for functional studies of heterologous effector proteins in barley.
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Affiliation(s)
- Bilal Ökmen
- BioCenter, Institute for Plant Sciences, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany
| | - Daniela Schwammbach
- Max Planck Institute for Terrestrial Microbiology, Karl von Frisch Straße, 35043 Marburg, Germany;
| | - Guus Bakkeren
- Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, BC V0H 1Z0, Canada;
| | - Ulla Neumann
- Central Microscopy, Max Planck Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany;
| | - Gunther Doehlemann
- BioCenter, Institute for Plant Sciences, University of Cologne, Zülpicher Straße 47a, 50674 Cologne, Germany
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