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Nabi Z, Manzoor S, Nabi SU, Wani TA, Gulzar H, Farooq M, Arya VM, Baloch FS, Vlădulescu C, Popescu SM, Mansoor S. Pattern-Triggered Immunity and Effector-Triggered Immunity: crosstalk and cooperation of PRR and NLR-mediated plant defense pathways during host-pathogen interactions. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2024; 30:587-604. [PMID: 38737322 PMCID: PMC11087456 DOI: 10.1007/s12298-024-01452-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 05/14/2024]
Abstract
The elucidation of the molecular basis underlying plant-pathogen interactions is imperative for the development of sustainable resistance strategies against pathogens. Plants employ a dual-layered immunological detection and response system wherein cell surface-localized Pattern Recognition Receptors (PRRs) and intracellular Nucleotide-Binding Leucine-Rich Repeat Receptors (NLRs) play pivotal roles in initiating downstream signalling cascades in response to pathogen-derived chemicals. Pattern-Triggered Immunity (PTI) is associated with PRRs and is activated by the recognition of conserved molecular structures, known as Pathogen-Associated Molecular Patterns. When PTI proves ineffective due to pathogenic effectors, Effector-Triggered Immunity (ETI) frequently confers resistance. In ETI, host plants utilize NLRs to detect pathogen effectors directly or indirectly, prompting a rapid and more robust defense response. Additionally epigenetic mechanisms are participating in plant immune memory. Recently developed technologies like CRISPR/Cas9 helps in exposing novel prospects in plant pathogen interactions. In this review we explore the fascinating crosstalk and cooperation between PRRs and NLRs. We discuss epigenomic processes and CRISPR/Cas9 regulating immune response in plants and recent findings that shed light on the coordination of these defense layers. Furthermore, we also have discussed the intricate interactions between the salicylic acid and jasmonic acid signalling pathways in plants, offering insights into potential synergistic interactions that would be harnessed for the development of novel and sustainable resistance strategies against diverse group of pathogens.
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Affiliation(s)
- Zarka Nabi
- Division of Plant Pathology, FOA-SKUAST-K, Wadura, 193201 India
| | - Subaya Manzoor
- Division of Plant Pathology, FOA-SKUAST-K, Wadura, 193201 India
| | - Sajad Un Nabi
- ICAR-Central Institute of Temperate Horticulture, Srinagar, 191132 India
| | | | - Humira Gulzar
- Division of Plant Pathology, FOA-SKUAST-K, Wadura, 193201 India
| | - Mehreena Farooq
- Division of Plant Pathology, FOH-SKUAST-K, Shalimar, Srinagar, 190025 India
| | - Vivak M. Arya
- Division of Soil Science and Agriculture Chemistry, Sher-e-Kashmir University of Agricultural Sciences and Technology, Jammu, India
| | - Faheem Shehzad Baloch
- Department of Biotechnology, Faculty of Science, Mersin University, 33100 Yenişehir, Mersin Turkey
| | - Carmen Vlădulescu
- Department of Biology and Environmental Engineering, University of Craiova, A. I. Cuza 13, 200585 Craiova, Romania
| | - Simona Mariana Popescu
- Department of Biology and Environmental Engineering, University of Craiova, A. I. Cuza 13, 200585 Craiova, Romania
| | - Sheikh Mansoor
- Department of Plant Resources and Environment, Jeju National University, Jeju, 63243 Republic of Korea
- Subtropical/Tropical Organism Gene Bank, Jeju National University, Jeju, 63243 Republic of Korea
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2
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Havenga M, Wingfield BD, Wingfield MJ, Dreyer LL, Roets F, Aylward J. Genetic response to nitrogen starvation in the aggressive Eucalyptus foliar pathogen Teratosphaeria destructans. Curr Genet 2021; 67:981-990. [PMID: 34432124 DOI: 10.1007/s00294-021-01208-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 07/20/2021] [Accepted: 08/21/2021] [Indexed: 12/13/2022]
Abstract
Teratosphaeria destructans is one of the most aggressive foliar pathogens of Eucalyptus. The biological factors underpinning T. destructans infections, which include shoot and leaf blight on young trees, have never been interrogated. Thus, the means by which the pathogen modifies its host environment to overcome host defences remain unknown. By applying transcriptome sequencing, the aim of this study was to compare gene expression in a South African isolate of T. destructans grown on nitrogen-deficient and complete media. This made it possible to identify upregulated genes in a nitrogen-starved environment, often linked to the pathogenicity of the fungus. The results support the hypothesis that nitrogen starvation in T. destructans likely mirrors an in planta genetic response. This is because 45% of genes that were highly upregulated under nitrogen starvation have previously been reported to be associated with infection in other pathogen systems. These included several CAZymes, fungal effector proteins, peptidases, kinases, toxins, lipases and proteins associated with detoxification of toxic compounds. Twenty-five secondary metabolites were identified and expressed in both nitrogen-deficient and complete conditions. Additionally, the most highly expressed genes in both growth conditions had pathogenicity-related functions. This study highlights the large number of expressed genes associated with pathogenicity and overcoming plant defences. As such, the generated baseline knowledge regarding pathogenicity and aggressiveness in T. destructans is a valuable reference for future in planta work.
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Affiliation(s)
- Minette Havenga
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa. .,Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa.
| | - Brenda D Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Michael J Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa
| | - Léanne L Dreyer
- Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa
| | - Francois Roets
- Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa
| | - Janneke Aylward
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa.,Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa
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Kumar J, Ramlal A, Kumar K, Rani A, Mishra V. Signaling Pathways and Downstream Effectors of Host Innate Immunity in Plants. Int J Mol Sci 2021; 22:ijms22169022. [PMID: 34445728 PMCID: PMC8396522 DOI: 10.3390/ijms22169022] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/15/2022] Open
Abstract
Phytopathogens, such as biotrophs, hemibiotrophs and necrotrophs, pose serious stress on the development of their host plants, compromising their yields. Plants are in constant interaction with such phytopathogens and hence are vulnerable to their attack. In order to counter these attacks, plants need to develop immunity against them. Consequently, plants have developed strategies of recognizing and countering pathogenesis through pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Pathogen perception and surveillance is mediated through receptor proteins that trigger signal transduction, initiated in the cytoplasm or at the plasma membrane (PM) surfaces. Plant hosts possess microbe-associated molecular patterns (P/MAMPs), which trigger a complex set of mechanisms through the pattern recognition receptors (PRRs) and resistance (R) genes. These interactions lead to the stimulation of cytoplasmic kinases by many phosphorylating proteins that may also be transcription factors. Furthermore, phytohormones, such as salicylic acid, jasmonic acid and ethylene, are also effective in triggering defense responses. Closure of stomata, limiting the transfer of nutrients through apoplast and symplastic movements, production of antimicrobial compounds, programmed cell death (PCD) are some of the primary defense-related mechanisms. The current article highlights the molecular processes involved in plant innate immunity (PII) and discusses the most recent and plausible scientific interventions that could be useful in augmenting PII.
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Affiliation(s)
- Jitendra Kumar
- Bangalore Bioinnovation Centre, Life Sciences Park, Electronics City Phase 1, Bengaluru 560100, India;
| | - Ayyagari Ramlal
- Division of Genetics, Indian Agricultural Research Institute (IARI), Pusa Campus, New Delhi 110012, India;
| | - Kamal Kumar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110066, India;
| | - Anita Rani
- Department of Botany, Dyal Singh College, University of Delhi, Delhi 110003, India;
| | - Vachaspati Mishra
- Department of Botany, Dyal Singh College, University of Delhi, Delhi 110003, India;
- Correspondence:
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John E, Singh KB, Oliver RP, Tan K. Transcription factor control of virulence in phytopathogenic fungi. MOLECULAR PLANT PATHOLOGY 2021; 22:858-881. [PMID: 33973705 PMCID: PMC8232033 DOI: 10.1111/mpp.13056] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 05/12/2023]
Abstract
Plant-pathogenic fungi are a significant threat to economic and food security worldwide. Novel protection strategies are required and therefore it is critical we understand the mechanisms by which these pathogens cause disease. Virulence factors and pathogenicity genes have been identified, but in many cases their roles remain elusive. It is becoming increasingly clear that gene regulation is vital to enable plant infection and transcription factors play an essential role. Efforts to determine their regulatory functions in plant-pathogenic fungi have expanded since the annotation of fungal genomes revealed the ubiquity of transcription factors from a broad range of families. This review establishes the significance of transcription factors as regulatory elements in plant-pathogenic fungi and provides a systematic overview of those that have been functionally characterized. Detailed analysis is provided on regulators from well-characterized families controlling various aspects of fungal metabolism, development, stress tolerance, and the production of virulence factors such as effectors and secondary metabolites. This covers conserved transcription factors with either specialized or nonspecialized roles, as well as recently identified regulators targeting key virulence pathways. Fundamental knowledge of transcription factor regulation in plant-pathogenic fungi provides avenues to identify novel virulence factors and improve our understanding of the regulatory networks linked to pathogen evolution, while transcription factors can themselves be specifically targeted for disease control. Areas requiring further insight regarding the molecular mechanisms and/or specific classes of transcription factors are identified, and direction for future investigation is presented.
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Affiliation(s)
- Evan John
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Karam B. Singh
- Agriculture and FoodCommonwealth Scientific and Industrial Research OrganisationFloreatWestern AustraliaAustralia
| | - Richard P. Oliver
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
| | - Kar‐Chun Tan
- Centre for Crop and Disease ManagementCurtin UniversityBentleyWestern AustraliaAustralia
- School of Molecular and Life SciencesCurtin UniversityBentleyWestern AustraliaAustralia
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Li C, Zhang Q, Xia Y, Jin K. MaAreB, a GATA Transcription Factor, Is Involved in Nitrogen Source Utilization, Stress Tolerances and Virulence in Metarhizium acridum. J Fungi (Basel) 2021; 7:jof7070512. [PMID: 34198996 PMCID: PMC8305397 DOI: 10.3390/jof7070512] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/24/2021] [Accepted: 06/24/2021] [Indexed: 01/14/2023] Open
Abstract
The nitrogen catabolite repression (NCR) pathway is involved in nitrogen utilization, in which the global GATA transcription factor AreA plays an indispensable role and has been reported in many fungi. However, relatively few studies are focused on AreB, another GATA transcription factor in the NCR pathway and the functions of AreB are largely unknown in entomopathogenic fungi. Here, we characterized MaAreB in the model entomopathogenic fungus Metarhizium acridum. Sequence arrangement found that MaAreB had a conserved GATA zinc finger DNA binding domain and a leucine zipper domain. Disruption of MaAreB affected the nitrogen utilization and led to decelerated conidial germination and hyphal growth, decreased conidial yield, and lower tolerances to UV-B irradiation and heat-shock. Furthermore, the MaAreB mutant (ΔMaAreB) exhibited increased sensitivity to CFW (Calcofluor white), decreased cell wall contents (chitin and β-1,3-glucan) and reduced expression levels of some genes related to cell wall integrity, indicating that disruption of MaAreB affected the cell wall integrity. Bioassays showed that the virulence of the ΔMaAreB strain was decreased in topical inoculation but not in intra-hemocoel injection. Consistently, deletion of MaAreB severely impaired the appressorium formation and reduced the turgor pressure of appressorium. These results revealed that MaAreB regulated fungal nitrogen utilization, cell wall integrity and biological control potential, which would contribute to the functional characterization of AreB homologous proteins in other insect fungal pathogens, and even filamentous fungi.
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Affiliation(s)
- Chaochuang Li
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing 401331, China; (C.L.); (Q.Z.)
- Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 401331, China
- Key Laboratory of Gene Function and Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing 401331, China
| | - Qipei Zhang
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing 401331, China; (C.L.); (Q.Z.)
- Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 401331, China
- Key Laboratory of Gene Function and Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing 401331, China
| | - Yuxian Xia
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing 401331, China; (C.L.); (Q.Z.)
- Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 401331, China
- Key Laboratory of Gene Function and Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing 401331, China
- Correspondence: (Y.X.); (K.J.); Tel.: +86-23-65120990 (Y.X.)
| | - Kai Jin
- Genetic Engineering Research Center, School of Life Sciences, Chongqing University, Chongqing 401331, China; (C.L.); (Q.Z.)
- Chongqing Engineering Research Center for Fungal Insecticide, Chongqing 401331, China
- Key Laboratory of Gene Function and Regulation Technologies Under Chongqing Municipal Education Commission, Chongqing 401331, China
- Correspondence: (Y.X.); (K.J.); Tel.: +86-23-65120990 (Y.X.)
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Zhu J, Jeong JS, Khang CH. Tandem DNA repeats contain cis-regulatory sequences that activate biotrophy-specific expression of Magnaporthe effector gene PWL2. MOLECULAR PLANT PATHOLOGY 2021; 22:508-521. [PMID: 33694285 PMCID: PMC8035637 DOI: 10.1111/mpp.13038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 06/12/2023]
Abstract
During plant infection, fungi secrete effector proteins in coordination with distinct infection stages. Thus, the success of plant infection is determined by precise control of effector gene expression. We analysed the PWL2 effector gene of the rice blast fungus Magnaporthe oryzae to understand how effector genes are activated specifically during the early biotrophic stages of rice infection. Here, we used confocal live-cell imaging of M. oryzae transformants with various PWL2 promoter fragments fused to sensitive green fluorescent protein reporter genes to determine the expression patterns of PWL2 at the cellular level, together with quantitative reverse transcription PCR analyses at the tissue level. We found PWL2 expression was coupled with sequential biotrophic invasion of rice cells. PWL2 expression was induced in the appressorium upon penetration into a living rice cell but greatly declined in the highly branched hyphae when the first-invaded rice cell was dead. PWL2 expression then increased again as the hyphae penetrate into living adjacent cells. The expression of PWL2 required fungal penetration into living plant cells of either host rice or nonhost onion. Deletion and mutagenesis experiments further revealed that the tandem repeats in the PWL2 promoter contain 12-base pair sequences required for expression. We conclude that PWL2 expression is (a) activated by an unknown signal commonly present in living plant cells, (b) specific to biotrophic stages of fungal infection, and (c) requires 12-base pair cis-regulatory sequences in the promoter.
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Affiliation(s)
- Jie Zhu
- Department of Plant BiologyUniversity of GeorgiaAthensGeorgiaUSA
- Present address:
Department of Plant PathologyUniversity of CaliforniaDavisCaliforniaUSA
| | - Jun Seop Jeong
- Department of BiologyNorth Carolina A&T State UniversityGreensboroNorth CarolinaUSA
| | - Chang Hyun Khang
- Department of Plant BiologyUniversity of GeorgiaAthensGeorgiaUSA
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Zarattini M, Farjad M, Launay A, Cannella D, Soulié MC, Bernacchia G, Fagard M. Every cloud has a silver lining: how abiotic stresses affect gene expression in plant-pathogen interactions. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:1020-1033. [PMID: 33188434 PMCID: PMC7904152 DOI: 10.1093/jxb/eraa531] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 11/10/2020] [Indexed: 05/03/2023]
Abstract
Current environmental and climate changes are having a pronounced influence on the outcome of plant-pathogen interactions, further highlighting the fact that abiotic stresses strongly affect biotic interactions at various levels. For instance, physiological parameters such as plant architecture and tissue organization together with primary and specialized metabolism are affected by environmental constraints, and these combine to make an individual plant either a more or less suitable host for a given pathogen. In addition, abiotic stresses can affect the timely expression of plant defense and pathogen virulence. Indeed, several studies have shown that variations in temperature, and in water and mineral nutrient availability affect the expression of plant defense genes. The expression of virulence genes, known to be crucial for disease outbreak, is also affected by environmental conditions, potentially modifying existing pathosystems and paving the way for emerging pathogens. In this review, we summarize our current knowledge on the impact of abiotic stress on biotic interactions at the transcriptional level in both the plant and the pathogen side of the interaction. We also perform a metadata analysis of four different combinations of abiotic and biotic stresses, which identifies 197 common modulated genes with strong enrichment in Gene Ontology terms related to defense . We also describe the multistress-specific responses of selected defense-related genes.
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Affiliation(s)
- Marco Zarattini
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- PhotoBioCatalysis Unit – Crop Production and Biostimulation Lab (CPBL), Interfaculty School of Bioengineers, Université Libre de Bruxelles (ULB), CP150, Avenue F.D. Roosevelt 50, Brussels, Belgium
| | - Mahsa Farjad
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - Alban Launay
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | - David Cannella
- PhotoBioCatalysis Unit – Crop Production and Biostimulation Lab (CPBL), Interfaculty School of Bioengineers, Université Libre de Bruxelles (ULB), CP150, Avenue F.D. Roosevelt 50, Brussels, Belgium
| | - Marie-Christine Soulié
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- Sorbonne Universités, UPMC Univ. Paris 06, UFR 927, 4 place Jussieu, Paris, France
| | - Giovanni Bernacchia
- Department of Life Sciences and Biotechnology, University of Ferrara, Via Borsari 46, Ferrara, Italy
| | - Mathilde Fagard
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
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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: 16] [Impact Index Per Article: 4.0] [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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Zhang C, Cui T, Zhang F, Xue Z, Miao J, Wang W, Liu X. Identification of differentially activated pathways in Phytophthora sojae at the mycelial, cyst, and oospore stages by TMT-based quantitative proteomics analysis. J Proteomics 2020; 221:103776. [PMID: 32268220 DOI: 10.1016/j.jprot.2020.103776] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 03/25/2020] [Accepted: 04/02/2020] [Indexed: 01/24/2023]
Abstract
Phytophthora sojae is a widely distributed, destructive oomycete plant pathogen that has been developed as a model for oomycete biology. Given the important but limited reports on the comparison of the sexual and asexual stages in Phytophthora, we performed a large-scale quantitative proteomics study on two key asexual life stages of P. sojae-the mycelium and cyst-as well as on the oospore, which is a key sexual stage. Over 29,631 peptides from 4688 proteins were analyzed. Briefly, 445 proteins, 624 proteins, and 579 proteins were defined as differentially quantified proteins in cyst vs mycelium, oospore vs cyst, and oospore vs mycelium comparisons, respectively (|log2 fold change| > 1 and P < 0.05). Compared to the mycelium and oospore, fatty acid and nitrogen metabolism were specifically induced in cysts. In oospores, the up-regulated proteins focused on RNA transport and protein processing in endoplasmic reticulum, indicating translation, folding, and the secretion of core cellular or stage-specific proteins active in oospores, which might be used for oospore germination. The data presented expand our knowledge of pathways specifically linked to asexual and sexual stages of this pathogen. BIOLOGICAL SIGNIFICANCE: The sexual spores (oospores) in oomycetes have thick cell walls and can survive in the soil for years, thus providing a primary source and allowing the reinfection of their host plant in subsequent growing seasons. However, the proteomic study on oospores remains very limited as they are generally considered to be dormant. In the present study, we successfully isolated oospores, and performed a large-scale comparative quantitative proteomics study on this key sexual stage and two representative asexual stages of P. sojae. The results provide an improved understanding of P. sojae biology and suggest potential metabolic targets for disease control at the three different developmental stages in oomycetes.
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Affiliation(s)
- Can Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Tongshan Cui
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Fan Zhang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Zhaolin Xue
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Jianqiang Miao
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, China
| | - Weizhen Wang
- Department of Plant Pathology, China Agricultural University, Beijing 100193, China
| | - Xili Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, China.
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Verly C, Djoman ACR, Rigault M, Giraud F, Rajjou L, Saint-Macary ME, Dellagi A. Plant Defense Stimulator Mediated Defense Activation Is Affected by Nitrate Fertilization and Developmental Stage in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2020; 11:583. [PMID: 32528493 PMCID: PMC7264385 DOI: 10.3389/fpls.2020.00583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/17/2020] [Indexed: 05/20/2023]
Abstract
Plant defense stimulators, used in crop protection, are an attractive option to reduce the use of conventional crop protection products and optimize biocontrol strategies. These products are able to activate plant defenses and thus limit infection by pathogens. However, the effectiveness of these plant defense stimulators remains erratic and is potentially dependent on many agronomic and environmental parameters still unknown or poorly controlled. The developmental stage of the plant as well as its fertilization, and essentially nitrogen nutrition, play major roles in defense establishment in the presence of pathogens or plant defense stimulators. The major nitrogen source used by plants is nitrate. In this study, we investigated the impact of Arabidopsis thaliana plant developmental stage and nitrate nutrition on its capacity to mount immune reactions in response to two plant defense stimulators triggering two major defense pathways, the salicylic acid and the jasmonic acid pathways. We show that optimal nitrate nutrition is needed for effective defense activation and protection against the pathogenic bacteria Dickeya dadantii and Pseudomonas syringae pv. tomato. Using an npr1 defense signaling mutant, we showed that nitrate dependent protection against D. dadantii requires a functional NPR1 gene. Our results indicate that the efficacy of plant defense stimulators is strongly affected by nitrate nutrition and the developmental stage. The nitrate dependent efficacy of plant defense stimulators is not only due to a metabolic effect but also invloves NPR1 mediated defense signaling. Plant defense stimulators may have opposite effects on plant resistance to a pathogen. Together, our results indicate that agronomic use of plant defense stimulators must be optimized according to nitrate fertilization and developmental stage.
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Affiliation(s)
- Camille Verly
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- Staphyt-Service L&G/BIOTEAM, Martillac, France
| | - Atsin Claude Roméo Djoman
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- Staphyt-Service L&G/BIOTEAM, Martillac, France
| | - Martine Rigault
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | | | - Loïc Rajjou
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
| | | | - Alia Dellagi
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, Versailles, France
- *Correspondence: Alia Dellagi,
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Griffiths SA, Cox RJ, Overdijk EJR, Mesarich CH, Saccomanno B, Lazarus CM, de Wit PJGM, Collemare J. Assignment of a dubious gene cluster to melanin biosynthesis in the tomato fungal pathogen Cladosporium fulvum. PLoS One 2018; 13:e0209600. [PMID: 30596695 PMCID: PMC6312243 DOI: 10.1371/journal.pone.0209600] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 12/07/2018] [Indexed: 12/17/2022] Open
Abstract
Pigments and phytotoxins are crucial for the survival and spread of plant pathogenic fungi. The genome of the tomato biotrophic fungal pathogen Cladosporium fulvum contains a predicted gene cluster (CfPKS1, CfPRF1, CfRDT1 and CfTSF1) that is syntenic with the characterized elsinochrome toxin gene cluster in the citrus pathogen Elsinoë fawcettii. However, a previous phylogenetic analysis suggested that CfPks1 might instead be involved in pigment production. Here, we report the characterization of the CfPKS1 gene cluster to resolve this ambiguity. Activation of the regulator CfTSF1 specifically induced the expression of CfPKS1 and CfRDT1, but not of CfPRF1. These co-regulated genes that define the CfPKS1 gene cluster are orthologous to genes involved in 1,3-dihydroxynaphthalene (DHN) melanin biosynthesis in other fungi. Heterologous expression of CfPKS1 in Aspergillus oryzae yielded 1,3,6,8-tetrahydroxynaphthalene, a typical precursor of DHN melanin. Δcfpks1 deletion mutants showed similar altered pigmentation to wild type treated with DHN melanin inhibitors. These mutants remained virulent on tomato, showing this gene cluster is not involved in pathogenicity. Altogether, our results showed that the CfPKS1 gene cluster is involved in the production of DHN melanin and suggests that elsinochrome production in E. fawcettii likely involves another gene cluster.
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Affiliation(s)
- Scott A. Griffiths
- Fungal Natural Products, Westerdijk Fungal Biodiversity Institute, CT, Utrecht, The Netherlands
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Russell J. Cox
- Institut für Organische Chemie, Leibniz Universität Hannover, Hannover
| | - Elysa J. R. Overdijk
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Laboratory of Cell Biology, Wageningen University, Wageningen, The Netherlands
| | - Carl H. Mesarich
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Benedetta Saccomanno
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Colin M. Lazarus
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | | | - Jérôme Collemare
- Fungal Natural Products, Westerdijk Fungal Biodiversity Institute, CT, Utrecht, The Netherlands
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- * E-mail:
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Griffiths S, Mesarich CH, Overdijk EJR, Saccomanno B, de Wit PJGM, Collemare J. Down-regulation of cladofulvin biosynthesis is required for biotrophic growth of Cladosporium fulvum on tomato. MOLECULAR PLANT PATHOLOGY 2018; 19:369-380. [PMID: 27997759 PMCID: PMC6638085 DOI: 10.1111/mpp.12527] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/01/2016] [Accepted: 12/09/2016] [Indexed: 05/19/2023]
Abstract
Fungal biotrophy is associated with a reduced capacity to produce potentially toxic secondary metabolites (SMs). Yet, the genome of the biotrophic plant pathogen Cladosporium fulvum contains many SM biosynthetic gene clusters, with several related to toxin production. These gene clusters are, however, poorly expressed during the colonization of tomato. The sole detectable SM produced by C. fulvum during in vitro growth is the anthraquinone cladofulvin. Although this pigment is not detected in infected leaves, cladofulvin biosynthetic genes are expressed throughout the pre-penetration phase and during conidiation at the end of the infection cycle, but are repressed during the biotrophic phase of tomato colonization. It has been suggested that the tight regulation of SM gene clusters is required for C. fulvum to behave as a biotrophic pathogen, whilst retaining potential fitness determinants for growth and survival outside its host. To address this hypothesis, we analysed the disease symptoms caused by mutant C. fulvum strains that do not produce or over-produce cladofulvin during the biotrophic growth phase. Non-producers infected tomato in a similar manner to the wild-type, suggesting that cladofulvin is not a virulence factor. In contrast, the cladofulvin over-producers caused strong necrosis and desiccation of tomato leaves, which, in turn, arrested conidiation. Consistent with the role of pigments in survival against abiotic stresses, cladofulvin protects conidia against UV light and low-temperature stress. Overall, this study demonstrates that the repression of cladofulvin production is required for C. fulvum to sustain its biotrophic lifestyle in tomato, whereas its production is important for survival outside its host.
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Affiliation(s)
- Scott Griffiths
- Laboratory of PhytopathologyWageningen UniversityWageningen6708 PBthe Netherlands
| | - Carl H. Mesarich
- Laboratory of PhytopathologyWageningen UniversityWageningen6708 PBthe Netherlands
- Present address:
Laboratory of Molecular Plant PathologyInstitute of Agriculture and Environment, Massey University, Private Bag 11222Palmerston North4442New Zealand
| | - Elysa J. R. Overdijk
- Laboratory of PhytopathologyWageningen UniversityWageningen6708 PBthe Netherlands
- Laboratory of Cell BiologyWageningen UniversityWageningen6708 PBthe Netherlands
| | - Benedetta Saccomanno
- Laboratory of PhytopathologyWageningen UniversityWageningen6708 PBthe Netherlands
| | | | - Jérôme Collemare
- Laboratory of PhytopathologyWageningen UniversityWageningen6708 PBthe Netherlands
- UMR1345 Institut de Recherche en Horticulture et Semences (IRHS)‐INRA, ACO, Université d'AngersBeaucouzé Cedex49071France
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Oh Y, Robertson SL, Parker J, Muddiman DC, Dean RA. Comparative proteomic analysis between nitrogen supplemented and starved conditions in Magnaporthe oryzae. Proteome Sci 2017; 15:20. [PMID: 29158724 PMCID: PMC5684745 DOI: 10.1186/s12953-017-0128-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/02/2017] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Fungi are constantly exposed to nitrogen limiting environments, and thus the efficient regulation of nitrogen metabolism is essential for their survival, growth, development and pathogenicity. To understand how the rice blast pathogen Magnaporthe oryzae copes with limited nitrogen availability, a global proteome analysis under nitrogen supplemented and nitrogen starved conditions was completed. METHODS M. oryzae strain 70-15 was cultivated in liquid minimal media and transferred to media with nitrate or without a nitrogen source. Proteins were isolated and subjected to unfractionated gel-free based liquid chromatography-tandem mass spectrometry (LC-MS/MS). The subcellular localization and function of the identified proteins were predicted using bioinformatics tools. RESULTS A total of 5498 M. oryzae proteins were identified. Comparative analysis of protein expression showed 363 proteins and 266 proteins significantly induced or uniquely expressed under nitrogen starved or nitrogen supplemented conditions, respectively. A functional analysis of differentially expressed proteins revealed that during nitrogen starvation nitrogen catabolite repression, melanin biosynthesis, protein degradation and protein translation pathways underwent extensive alterations. In addition, nitrogen starvation induced accumulation of various extracellular proteins including small extracellular proteins consistent with observations of a link between nitrogen starvation and the development of pathogenicity in M. oryzae. CONCLUSION The results from this study provide a comprehensive understanding of fungal responses to nitrogen availability.
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Affiliation(s)
- Yeonyee Oh
- Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695 USA
| | - Suzanne L. Robertson
- W. M. Keck FT-ICR Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC 27695 USA
| | - Jennifer Parker
- W. M. Keck FT-ICR Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC 27695 USA
| | - David C. Muddiman
- W. M. Keck FT-ICR Mass Spectrometry Laboratory, Department of Chemistry, North Carolina State University, Raleigh, NC 27695 USA
| | - Ralph A. Dean
- Center for Integrated Fungal Research, Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC 27695 USA
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Abstract
The interactions between fungi and plants encompass a spectrum of ecologies ranging from saprotrophy (growth on dead plant material) through pathogenesis (growth of the fungus accompanied by disease on the plant) to symbiosis (growth of the fungus with growth enhancement of the plant). We consider pathogenesis in this article and the key roles played by a range of pathogen-encoded molecules that have collectively become known as effectors.
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Abstract
Effectors are molecules used by microbial pathogens to facilitate infection via effector-triggered susceptibility or tissue necrosis in their host. Much research has been focussed on the identification and elucidating the function of fungal effectors during plant pathogenesis. By comparison, knowledge of how phytopathogenic fungi regulate the expression of effector genes has been lagging. Several recent studies have illustrated the role of various transcription factors, chromosome-based control, effector epistasis, and mobilisation of endosomes within the fungal hyphae in regulating effector expression and virulence on the host plant. Improved knowledge of effector regulation is likely to assist in improving novel crop protection strategies.
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Affiliation(s)
- Kar-Chun Tan
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
| | - Richard P. Oliver
- Centre for Crop and Disease Management, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia, Australia
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Meyer M, Bourras S, Gervais J, Labadie K, Cruaud C, Balesdent MH, Rouxel T. Impact of biotic and abiotic factors on the expression of fungal effector-encoding genes in axenic growth conditions. Fungal Genet Biol 2016; 99:1-12. [PMID: 28034799 DOI: 10.1016/j.fgb.2016.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 12/15/2016] [Accepted: 12/22/2016] [Indexed: 12/31/2022]
Abstract
In phytopathogenic fungi, the expression of hundreds of small secreted protein (SSP)-encoding genes is induced upon primary infection of plants while no or a low level of expression is observed during vegetative growth. In some species such as Leptosphaeria maculans, this coordinated in-planta upregulation of SSP-encoding genes expression relies on an epigenetic control but the signals triggering gene expression in-planta are unknown. In the present study, biotic and abiotic factors that may relieve suppression of SSP-encoding gene expression during axenic growth of L. maculans were investigated. Some abiotic factors (temperature, pH) could have a limited effect on SSP gene expression. In contrast, two types of cellular stresses induced by antibiotics (cycloheximide, phleomycin) activated strongly the transcription of SSP genes. A transcriptomic analysis to cycloheximide exposure revealed that biological processes such as ribosome biosynthesis and rRNA processing were induced whereas important metabolic pathways such as glycogen and nitrogen metabolism, glycolysis and tricarboxylic acid cycle activity were down-regulated. A quantitatively different expression of SSP-encoding genes compared to plant infection was also detected. Interestingly, the same physico-chemical parameters as those identified here for L. maculans effectors were identified to regulate positively or negatively the expression of bacterial effectors. This suggests that apoplastic phytopathogens may react to similar physiological parameters for regulation of their effector genes.
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Affiliation(s)
- Michel Meyer
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France.
| | - Salim Bourras
- Université Paris-Sud, 91400 Orsay, France; Institute of Plant Biology, University of Zürich, Zollikerstrasse 107, CH-8008 Zürich, Switzerland
| | - Julie Gervais
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Karine Labadie
- Centre National de Séquençage, CEA-Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry Cedex, France
| | - Corinne Cruaud
- Centre National de Séquençage, CEA-Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry Cedex, France
| | - Marie-Hélène Balesdent
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Thierry Rouxel
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
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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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18
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Bi F, Barad S, Ment D, Luria N, Dubey A, Casado V, Glam N, Mínguez JD, Espeso EA, Fluhr R, Prusky D. Carbon regulation of environmental pH by secreted small molecules that modulate pathogenicity in phytopathogenic fungi. MOLECULAR PLANT PATHOLOGY 2016; 17:1178-95. [PMID: 26666972 PMCID: PMC6638356 DOI: 10.1111/mpp.12355] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 05/22/2023]
Abstract
Fruit pathogens can contribute to the acidification or alkalinization of the host environment. This capability has been used to divide fungal pathogens into acidifying and/or alkalinizing classes. Here, we show that diverse classes of fungal pathogens-Colletotrichum gloeosporioides, Penicillium expansum, Aspergillus nidulans and Fusarium oxysporum-secrete small pH-affecting molecules. These molecules modify the environmental pH, which dictates acidic or alkaline colonizing strategies, and induce the expression of PACC-dependent genes. We show that, in many organisms, acidification is induced under carbon excess, i.e. 175 mm sucrose (the most abundant sugar in fruits). In contrast, alkalinization occurs under conditions of carbon deprivation, i.e. less than 15 mm sucrose. The carbon source is metabolized by glucose oxidase (gox2) to gluconic acid, contributing to medium acidification, whereas catalysed deamination of non-preferred carbon sources, such as the amino acid glutamate, by glutamate dehydrogenase 2 (gdh2), results in the secretion of ammonia. Functional analyses of Δgdh2 mutants showed reduced alkalinization and pathogenicity during growth under carbon deprivation, but not in high-carbon medium or on fruit rich in sugar, whereas analysis of Δgox2 mutants showed reduced acidification and pathogencity under conditions of excess carbon. The induction pattern of gdh2 was negatively correlated with the expression of the zinc finger global carbon catabolite repressor creA. The present results indicate that differential pH modulation by fruit fungal pathogens is a host-dependent mechanism, affected by host sugar content, that modulates environmental pH to enhance fruit colonization.
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Affiliation(s)
- Fangcheng Bi
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
- Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, and Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization, Ministry of Agriculture, Guangzhou, 510640, China
| | - Shiri Barad
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Dana Ment
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Neta Luria
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Amit Dubey
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
| | - Virginia Casado
- Department of Microbiology and Genetics, CIALE, Universidad de Salamanca, Salamanca, 37007, Spain
| | - Nofar Glam
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Jose Diaz Mínguez
- Department of Microbiology and Genetics, CIALE, Universidad de Salamanca, Salamanca, 37007, Spain
| | - Eduardo A Espeso
- Department of Molecular and Cellular Biology, Centro de Investigaciones Biológicas (C.I.B.), Madrid, 28040, Spain
| | - Robert Fluhr
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Dov Prusky
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
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de Wit PJGM. Cladosporium fulvum Effectors: Weapons in the Arms Race with Tomato. ANNUAL REVIEW OF PHYTOPATHOLOGY 2016; 54:1-23. [PMID: 27215970 DOI: 10.1146/annurev-phyto-011516-040249] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In this review, I recount my personal history. My drive to study host-pathogen interactions was to find alternatives for agrochemicals, which was triggered after reading the book "Silent Spring" by Rachel Carson. I reflect on my research at the Laboratory of Phytopathology at Wageningen University, where I have worked for my entire career on the interaction between Cladosporium fulvum and tomato, and related gene-for-gene pathosystems. I describe different methods used to identify and sequence avirulence (Avr) genes from the pathogen and resistance (R) genes from the host. The major genes involved in classical gene-for-gene interactions have now been identified, and breeders can produce plants with multiple R genes providing durable and environmentally safe protection against pathogens. In some cases, this might require the use of genetically modified plants when R genes cannot be introduced by classical breeding.
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Affiliation(s)
- Pierre J G M de Wit
- Laboratory of Phytopathology, Wageningen University, 6700 AA, Wageningen, The Netherlands; ,
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20
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Griffiths S, Saccomanno B, de Wit PJ, Collemare J. Regulation of secondary metabolite production in the fungal tomato pathogen Cladosporium fulvum. Fungal Genet Biol 2015; 84:52-61. [DOI: 10.1016/j.fgb.2015.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 09/23/2015] [Accepted: 09/24/2015] [Indexed: 12/15/2022]
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21
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Eaton CJ, Dupont PY, Solomon P, Clayton W, Scott B, Cox MP. A Core Gene Set Describes the Molecular Basis of Mutualism and Antagonism in Epichloë spp. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:218-31. [PMID: 25496592 DOI: 10.1094/mpmi-09-14-0293-fi] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Beneficial plant-fungal interactions play an important role in the ability of plants to survive changing environmental conditions. In contrast, phytopathogenic fungi fall at the opposite end of the symbiotic spectrum, causing reduced host growth or even death. In order to exploit beneficial interactions and prevent pathogenic ones, it is essential to understand the molecular differences underlying these alternative states. The association between the endophyte Epichloë festucae and Lolium perenne (perennial ryegrass) is an excellent system for studying these molecular patterns due to the existence of several fungal mutants that have an antagonistic rather than a mutualistic interaction with the host plant. By comparing gene expression in a wild-type beneficial association with three mutant antagonistic associations disrupted in key signaling genes, we identified a core set of 182 genes that show common differential expression patterns between these two states. These gene expression changes are indicative of a nutrient-starvation response, as supported by the upregulation of genes encoding degradative enzymes, transporters, and primary metabolism, and downregulation of genes encoding putative small-secreted proteins and secondary metabolism. These results suggest that disruption of a mutualistic symbiotic interaction may lead to an elevated uptake and degradation of host-derived nutrients and cell-wall components, reminiscent of phytopathogenic interactions.
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22
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Mesarich CH, Griffiths SA, van der Burgt A, Okmen B, Beenen HG, Etalo DW, Joosten MHAJ, de Wit PJGM. Transcriptome sequencing uncovers the Avr5 avirulence gene of the tomato leaf mold pathogen Cladosporium fulvum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:846-57. [PMID: 24678832 DOI: 10.1094/mpmi-02-14-0050-r] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The Cf-5 gene of tomato confers resistance to strains of the fungal pathogen Cladosporium fulvum carrying the avirulence gene Avr5. Although Cf-5 has been cloned, Avr5 has remained elusive. We report the cloning of Avr5 using a combined bioinformatic and transcriptome sequencing approach. RNA-Seq was performed on the sequenced race 0 strain (0WU; carrying Avr5), as well as a race 5 strain (IPO 1979; lacking a functional Avr5 gene) during infection of susceptible tomato. Forty-four in planta-induced C. fulvum candidate effector (CfCE) genes of 0WU were identified that putatively encode a secreted, small cysteine-rich protein. An expressed transcript sequence comparison between strains revealed two polymorphic CfCE genes in IPO 1979. One of these conferred avirulence to IPO 1979 on Cf-5 tomato following complementation with the corresponding 0WU allele, confirming identification of Avr5. Complementation also led to increased fungal biomass during infection of susceptible tomato, signifying a role for Avr5 in virulence. Seven of eight race 5 strains investigated escape Cf-5-mediated resistance through deletion of the Avr5 gene. Avr5 is heavily flanked by repetitive elements, suggesting that repeat instability, in combination with Cf-5-mediated selection pressure, has led to the emergence of race 5 strains deleted for the Avr5 gene.
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Mirzadi Gohari A, Mehrabi R, Robert O, Ince IA, Boeren S, Schuster M, Steinberg G, de Wit PJGM, Kema GHJ. Molecular characterization and functional analyses of ZtWor1, a transcriptional regulator of the fungal wheat pathogen Zymoseptoria tritici. MOLECULAR PLANT PATHOLOGY 2014; 15:394-405. [PMID: 24341593 PMCID: PMC6638687 DOI: 10.1111/mpp.12102] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Zymoseptoria tritici causes the major fungal wheat disease septoria tritici blotch, and is increasingly being used as a model for transmission and population genetics, as well as host-pathogen interactions. Here, we study the biological function of ZtWor1, the orthologue of Wor1 in the fungal human pathogen Candida albicans, as a representative of a superfamily of regulatory proteins involved in dimorphic switching. In Z. tritici, this gene is pivotal for pathogenesis, as ZtWor1 mutants were nonpathogenic and complementation restored the wild-type phenotypes. In planta expression analyses showed that ZtWor1 is up-regulated during the initiation of colonization and fructification, and regulates candidate effector genes, including one that was discovered after comparative proteome analysis of the Z. tritici wild-type strain and the ZtWor1 mutant, which was particularly expressed in planta. Cell fusion and anastomosis occur frequently in ZtWor1 mutants, reminiscent of mutants of MgGpb1, the β-subunit of the heterotrimeric G protein. Comparative expression of ZtWor1 in knock-out strains of MgGpb1 and MgTpk2, the catalytic subunit of protein kinase A, suggests that ZtWor1 is downstream of the cyclic adenosine monophosphate (cAMP) pathway that is crucial for pathogenesis in many fungal plant pathogens.
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Affiliation(s)
- Amir Mirzadi Gohari
- Plant Science Group, Plant Research International BV, Wageningen University, Droevendaalsesteeg 1, 06708 PB, Wageningen, The Netherlands; Department of Plant Protection, College of Agriculture, University of Tehran, Plant Pathology Building, Karaj, Iran
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Ökmen B, Collemare J, Griffiths S, van der Burgt A, Cox R, de Wit PJGM. Functional analysis of the conserved transcriptional regulator CfWor1 inCladosporium fulvumreveals diverse roles in the virulence of plant pathogenic fungi. Mol Microbiol 2014; 92:10-27. [DOI: 10.1111/mmi.12535] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Bilal Ökmen
- Laboratory of Phytopathology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
| | - Jérôme Collemare
- Laboratory of Phytopathology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
- Centre for BioSystems Genomics; P.O. Box 98 6700 AB Wageningen The Netherlands
| | - Scott Griffiths
- Laboratory of Phytopathology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
| | - Ate van der Burgt
- Laboratory of Phytopathology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
| | - Russell Cox
- School of Chemistry; University of Bristol; Cantock's Close Bristol UK
- Institut für Organische Chemie; Leibniz Universität Hannover; Schneiderberg 1B 30167 Hannover Germany
| | - Pierre J. G. M. de Wit
- Laboratory of Phytopathology; Wageningen University; Droevendaalsesteeg 1 6708 PB Wageningen The Netherlands
- Centre for BioSystems Genomics; P.O. Box 98 6700 AB Wageningen The Netherlands
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Kim PD, Šašek V, Burketová L, Čopíková J, Synytsya A, Jindřichová B, Valentová O. Cell wall components of Leptosphaeria maculans enhance resistance of Brassica napus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:5207-5214. [PMID: 23638999 DOI: 10.1021/jf401221v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Preparations with elicitation activity were obtained from the mycelium of Leptosphaeria maculans , a fungal pathogen of oilseed rape (Brassica napus). Crude delipidated and deproteinized extract from fungal cell walls induced expression of pathogenesis related gene 1 (PR1), hydrogen peroxide accumulation, and enhanced resistance of B. napus plants toward infection by L. maculans. Elicitation activity significantly decreased after treatment of a crude extract with α- or β-glucanase. Monosaccharide composition analysis of a crude extract purified by ion-exchange chromatography revealed glucose (∼58 mol %), mannose (∼22 mol %), and galactose (∼18 mol %) as the major sugars. FT-IR and NMR spectra confirmed the presence of both carbohydrate and polypeptide components in the purified product. Correlation NMR experiments defined trisaccharide bound to O-3 of serine residue α-D-Glcp-(1→2)-β-D-Galf-(1→6)-α-D-Manp-(1→3)-L-Ser. Terminal α-D-Glcp and (1→6)-β-D-glucan were also detected. The obtained results strongly support the conclusion that these carbohydrates induce defense response in B. napus plants.
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Affiliation(s)
- Phuong Dinh Kim
- Department of Biochemistry and Microbiology and ‡Department of Carbohydrates and Cereals, Institute of Chemical Technology Prague , Technická 3, 166 28 Prague 6, Czech Republic
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Seifi HS, Van Bockhaven J, Angenon G, Höfte M. Glutamate Metabolism in Plant Disease and Defense: Friend or Foe? MOLECULAR PLANT-MICROBE INTERACTIONS® 2013; 26:475-85. [PMID: 23342972 DOI: 10.1094/mpmi-07-12-0176-cr] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Plant glutamate metabolism (GM) plays a pivotal role in amino acid metabolism and orchestrates crucial metabolic functions, with key roles in plant defense against pathogens. These functions concern three major areas: nitrogen transportation via the glutamine synthetase and glutamine-oxoglutarate aminotransferase cycle, cellular redox regulation, and tricarboxylic acid cycle-dependent energy reprogramming. During interactions with pathogens, the host GM is markedly altered, leading to either a metabolic state, termed “endurance”, in which cell viability is maintained, or to an opposite metabolic state, termed “evasion”, in which the process of cell death is facilitated. It seems that endurance-natured modulations result in resistance to necrotrophic pathogens and susceptibility to biotrophs, whereas evasion-related reconfigurations lead to resistance to biotrophic pathogens but stimulate the infection by necrotrophs. Pathogens, however, have evolved strategies such as toxin secretion, hemibiotrophy, and selective amino acid utilization to exploit the plant GM to their own benefit. Collectively, alterations in the host GM in response to different pathogenic scenarios appear to function in two opposing ways, either backing the ongoing defense strategy to ultimately shape an efficient resistance response or being exploited by the pathogen to promote and facilitate infection.
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Progress on nitrogen regulation gene expression of plant pathogenic fungi under nitrogen starvation. YI CHUAN = HEREDITAS 2012; 34:848-56. [DOI: 10.3724/sp.j.1005.2012.00848] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Dallal Bashi Z, Rimmer SR, Khachatourians GG, Hegedus DD. Factors governing the regulation of Sclerotinia sclerotiorum cutinase A and polygalacturonase 1 during different stages of infection. Can J Microbiol 2012; 58:605-16. [PMID: 22524557 DOI: 10.1139/w2012-031] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sclerotinia sclerotiorum releases hydrolytic enzymes that sequentially degrade the plant cuticle, middle lamellae, and primary and secondary cell walls. The cuticle was found to be a barrier to S. sclerotiorum infection, as leaves stripped of epicuticular wax were more rapidly colonized. Consequently, the factors affecting the regulation of genes encoding polygalacturonase 1 (SsPG1) and a newly identified cutinase (SsCUTA) were examined. In vitro, SsCutA transcripts were detected within 1 h postinoculation of leaves, and expression was primarily governed by contact of mycelia with solid surfaces. Expression of SsPg1 was moderately induced by contact with solid surfaces including the leaf, and expression was restricted to the expanding margin of the lesion as the infection progressed. SsPg1 expression was induced by carbohydrate starvation but repressed by galacturonic acid. Glucose supported a basal level of SsPg1 expression but accentuated expression when provided to mycelia used to inoculate leaves. These observations were contrary to earlier reports indicating that glucose repressed SsPg1 expression while galacturonic acid induced expression. Pharmacological studies showed that disruption of calcium signalling affected SsCutA and SsPg1 expression and decreased S. sclerotiorum virulence, whereas elevated cAMP levels reduced virulence without affecting gene expression. The mechanisms involved in coordinating the expression of S. sclerotiorum hydrolytic enzymes throughout the various stages of the infection are discussed.
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Affiliation(s)
- Zafer Dallal Bashi
- Agriculture and Agri-Food Canada, 107 Science Place Saskatoon, SK S7N 0X2, Canada
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Horst RJ, Zeh C, Saur A, Sonnewald S, Sonnewald U, Voll LM. The Ustilago maydis Nit2 homolog regulates nitrogen utilization and is required for efficient induction of filamentous growth. EUKARYOTIC CELL 2012; 11:368-80. [PMID: 22247264 PMCID: PMC3294441 DOI: 10.1128/ec.05191-11] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 12/22/2011] [Indexed: 11/20/2022]
Abstract
Nitrogen catabolite repression (NCR) is a regulatory strategy found in microorganisms that restricts the utilization of complex and unfavored nitrogen sources in the presence of favored nitrogen sources. In fungi, this concept has been best studied in yeasts and filamentous ascomycetes, where the GATA transcription factors Gln3p and Gat1p (in yeasts) and Nit2/AreA (in ascomycetes) constitute the main positive regulators of NCR. The reason why functional Nit2 homologs of some phytopathogenic fungi are required for full virulence in their hosts has remained elusive. We have identified the Nit2 homolog in the basidiomycetous phytopathogen Ustilago maydis and show that it is a major, but not the exclusive, positive regulator of nitrogen utilization. By transcriptome analysis of sporidia grown on artificial media devoid of favored nitrogen sources, we show that only a subset of nitrogen-responsive genes are regulated by Nit2, including the Gal4-like transcription factor Ton1 (a target of Nit2). Ustilagic acid biosynthesis is not under the control of Nit2, while nitrogen starvation-induced filamentous growth is largely dependent on functional Nit2. nit2 deletion mutants show the delayed initiation of filamentous growth on maize leaves and exhibit strongly compromised virulence, demonstrating that Nit2 is required to efficiently initiate the pathogenicity program of U. maydis.
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Affiliation(s)
- Robin J Horst
- Division of Biochemistry, Friedrich-Alexander-University Erlangen-Nuremberg, Staudtstr. 5, Erlangen, Germany
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A new method to induce sclerotial differentiation in Polyporus umbellatus by split-plate culture. Mycol Prog 2012. [DOI: 10.1007/s11557-011-0802-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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AreA controls nitrogen source utilisation during both growth programs of the dimorphic fungus Penicillium marneffei. Fungal Biol 2011; 116:145-54. [PMID: 22208609 DOI: 10.1016/j.funbio.2011.10.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Revised: 10/28/2011] [Accepted: 10/28/2011] [Indexed: 12/17/2022]
Abstract
The opportunistic pathogen Penicillium marneffei displays a temperature-dependent dimorphic switching program with saprophytic hyphal growth at 25 °C and yeast growth at 37 °C. The areA gene of P. marneffei has been isolated and found to be required for the utilisation of nonpreferred nitrogen sources during both growth programs of P. marneffei, albeit to differing degrees. Based on this functional characterisation and high degree of sequence conservation with other fungal GATA factors, P. marneffei areA represents an orthologue of Aspergillus nidulans areA and Neurospora crassa NIT2. Based on this study it is proposed that AreA is likely to contribute to the pathogenicity of P. marneffei by facilitating growth in the host environment and regulating the expression of potential virulence factors such as extracellular proteases.
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Transcriptome profiling of the rice blast fungus during invasive plant infection and in vitro stresses. BMC Genomics 2011; 12:49. [PMID: 21247492 PMCID: PMC3037901 DOI: 10.1186/1471-2164-12-49] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 01/19/2011] [Indexed: 01/13/2023] Open
Abstract
Background Rice blast is the most threatening disease to cultivated rice. Magnaporthe oryzae, its causal agent, is likely to encounter environmental challenges during invasive growth in its host plants that require shifts in gene expression to establish a compatible interaction. Here, we tested the hypothesis that gene expression patterns during in planta invasive growth are similar to in vitro stress conditions, such as nutrient limitation, temperature up shift and oxidative stress, and determined which condition most closely mimicked that of in planta invasive growth. Gene expression data were collected from these in vitro experiments and compared to fungal gene expression during the invasive growth phase at 72 hours post-inoculation in compatible interactions on two grass hosts, rice and barley. Results We identified 4,973 genes that were differentially expressed in at least one of the in planta and in vitro stress conditions when compared to fungal mycelia grown in complete medium, which was used as reference. From those genes, 1,909 showed similar expression patterns between at least one of the in vitro stresses and rice and/or barley. Hierarchical clustering of these 1,909 genes showed three major clusters in which in planta conditions closely grouped with the nutrient starvation conditions. Out of these 1,909 genes, 55 genes and 129 genes were induced and repressed in all treatments, respectively. Functional categorization of the 55 induced genes revealed that most were either related to carbon metabolism, membrane proteins, or were involved in oxidoreduction reactions. The 129 repressed genes showed putative roles in vesicle trafficking, signal transduction, nitrogen metabolism, or molecular transport. Conclusions These findings suggest that M. oryzae is likely primarily coping with nutrient-limited environments at the invasive growth stage 72 hours post-inoculation, and not with oxidative or temperature stresses.
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Leal GA, Gomes LH, Albuquerque PSB, Tavares FCA, Figueira A. Searching for Moniliophthora perniciosa pathogenicity genes. Fungal Biol 2010; 114:842-54. [PMID: 20943194 DOI: 10.1016/j.funbio.2010.07.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 07/21/2010] [Accepted: 07/30/2010] [Indexed: 10/19/2022]
Abstract
The basidiomycete Moniliophthora perniciosa is the causal agent of witches' broom disease of Theobroma cacao (cacao). Pathogenesis mechanisms of this hemibiotrophic fungus are largely unknown. An approach to identify putative pathogenicity genes is searching for sequences induced in mycelia grown under in vitro conditions. Using this approach, genes from M. perniciosa induced under limiting nitrogen and light were identified from a cDNA library enriched by suppression subtractive hybridization as potential putative pathogenicity genes. From the 159 identified unique sequences, 59 were annotated and classified by gene ontology. Two sequences were categorized as "Defence genes, Virulence, and Cell response" presumably coding for allergenic proteins, whose homologues from other fungi are inducers of animal or plant defences. Differential gene expression was evaluated by quantitative amplification of reversed transcripts (RT-qPCR) of the putative identified genes coding for the two allergenic proteins (Aspf13 and 88KD), and for the enzymes Arylsulfatase (AS); Aryl-Alcohol Oxidase; Aldo-Keto Reductase (AK); Cytochrome P450 (P450); Phenylalanine Ammonia-Lyase; and Peroxidase from mycelia grown under contrasting N concentrations. All genes were validated for differential expression, except for the putative Peroxidase. The same eight genes were analysed for expression in susceptible plants inoculated with M. perniciosa, and six were induced during the early asymptomatic stage of the disease. In infected host tissues, transcripts of 88KD and AS were found more abundant at the biotrophic phase, while those from Aspf13, AK, PAL, and P450 accumulated at the necrotrophic phase, enabling to suggest that mycelia transition from biotrophic to necrotrophic might occur earlier than currently considered. These sequences appeared to be virulence life-style genes, which encode factors or enzymes that enable invasion, colonization or intracellular survival, or manipulate host factors to benefit the pathogen's own survival in the hostile environment.
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Affiliation(s)
- Gildemberg A Leal
- Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Piracicaba, SP, Brazil
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López-Berges MS, Rispail N, Prados-Rosales RC, Di Pietro A. A nitrogen response pathway regulates virulence functions in Fusarium oxysporum via the protein kinase TOR and the bZIP protein MeaB. THE PLANT CELL 2010; 22:2459-75. [PMID: 20639450 PMCID: PMC2929112 DOI: 10.1105/tpc.110.075937] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 06/03/2010] [Accepted: 06/22/2010] [Indexed: 05/19/2023]
Abstract
During infection, fungal pathogens activate virulence mechanisms, such as host adhesion, penetration and invasive growth. In the vascular wilt fungus Fusarium oxysporum, the mitogen-activated protein kinase Fmk1 is required for plant infection and controls processes such as cellophane penetration, vegetative hyphal fusion, or root adhesion. Here, we show that these virulence-related functions are repressed by the preferred nitrogen source ammonium and restored by treatment with l-methionine sulfoximine or rapamycin, two specific inhibitors of Gln synthetase and the protein kinase TOR, respectively. Deletion of the bZIP protein MeaB also resulted in nitrogen source-independent activation of virulence mechanisms. Activation of these functions did not require the global nitrogen regulator AreA, suggesting that MeaB-mediated repression of virulence functions does not act through inhibition of AreA. Tomato plants (Solanum lycopersicum) supplied with ammonium rather than nitrate showed a significant reduction in vascular wilt symptoms when infected with the wild type but not with the DeltameaB strain. Nitrogen source also affected invasive growth in the rice blast fungus Magnaporthe oryzae and the wheat head blight pathogen Fusarium graminearum. We propose that a conserved nitrogen-responsive pathway might operate via TOR and MeaB to control virulence in plant pathogenic fungi.
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Affiliation(s)
| | | | | | - Antonio Di Pietro
- Departamento de Genética, Universidad de Córdoba, Campus de Rabanales, Edificio Gregor Mendel, 14071 Córdoba, Spain
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Asunción García-Sánchez M, Martín-Rodrigues N, Ramos B, de Vega-Bartol JJ, Perlin MH, Díaz-Mínguez JM. fost12, the Fusarium oxysporum homolog of the transcription factor Ste12, is upregulated during plant infection and required for virulence. Fungal Genet Biol 2010; 47:216-25. [DOI: 10.1016/j.fgb.2009.11.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 11/03/2009] [Accepted: 11/19/2009] [Indexed: 11/27/2022]
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De Wit PJGM, Mehrabi R, Van den Burg HA, Stergiopoulos I. Fungal effector proteins: past, present and future. MOLECULAR PLANT PATHOLOGY 2009; 10:735-47. [PMID: 19849781 PMCID: PMC6640362 DOI: 10.1111/j.1364-3703.2009.00591.x] [Citation(s) in RCA: 179] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The pioneering research of Harold Flor on flax and the flax rust fungus culminated in his gene-for-gene hypothesis. It took nearly 50 years before the first fungal avirulence (Avr) gene in support of his hypothesis was cloned. Initially, fungal Avr genes were identified by reverse genetics and map-based cloning from model organisms, but, currently, the availability of many sequenced fungal genomes allows their cloning from additional fungi by a combination of comparative and functional genomics. It is believed that most Avr genes encode effectors that facilitate virulence by suppressing pathogen-associated molecular pattern-triggered immunity and induce effector-triggered immunity in plants containing cognate resistance proteins. In resistant plants, effectors are directly or indirectly recognized by cognate resistance proteins that reside either on the plasma membrane or inside the plant cell. Indirect recognition of an effector (also known as the guard model) implies that the virulence target of an effector in the host (the guardee) is guarded by the resistance protein (the guard) that senses manipulation of the guardee, leading to activation of effector-triggered immunity. In this article, we review the literature on fungal effectors and some pathogen-associated molecular patterns, including those of some fungi for which no gene-for-gene relationship has been established.
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Affiliation(s)
- Pierre J G M De Wit
- Wageningen University and Research Centre, Laboratory of Phytopathology, Droevendaalsesteeg 1, 6708 PB Wageningen, the Netherlands.
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37
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Stergiopoulos I, de Wit PJGM. Fungal effector proteins. ANNUAL REVIEW OF PHYTOPATHOLOGY 2009; 47:233-63. [PMID: 19400631 DOI: 10.1146/annurev.phyto.112408.132637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
It is accepted that most fungal avirulence genes encode virulence factors that are called effectors. Most fungal effectors are secreted, cysteine-rich proteins, and a role in virulence has been shown for a few of them, including Avr2 and Avr4 of Cladosporium fulvum, which inhibit plant cysteine proteases and protect chitin in fungal cell walls against plant chitinases, respectively. In resistant plants, effectors are directly or indirectly recognized by cognate resistance proteins that reside either inside the plant cell or on plasma membranes. Several secreted effectors function inside the host cell, but the uptake mechanism is not yet known. Variation observed among fungal effectors shows two types of selection that appear to relate to whether they interact directly or indirectly with their cognate resistance proteins. Direct interactions seem to favor point mutations in effector genes, leading to amino acid substitutions, whereas indirect interactions seem to favor jettison of effector genes.
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Affiliation(s)
- Ioannis Stergiopoulos
- Wageningen University and Research Center ( http://www.php.wur.nl/uk ), Laboratory of Phytopathology, 6709 PD Wageningen, The Netherlands.
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38
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Kucheryava N, Bowen JK, Sutherland PW, Conolly JJ, Mesarich CH, Rikkerink EH, Kemen E, Plummer KM, Hahn M, Templeton MD. Two novel Venturia inaequalis genes induced upon morphogenetic differentiation during infection and in vitro growth on cellophane. Fungal Genet Biol 2008; 45:1329-39. [DOI: 10.1016/j.fgb.2008.07.010] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 07/09/2008] [Accepted: 07/15/2008] [Indexed: 11/29/2022]
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39
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van der Does HC, Duyvesteijn RG, Goltstein PM, van Schie CC, Manders EM, Cornelissen BJ, Rep M. Expression of effector gene SIX1 of Fusarium oxysporum requires living plant cells. Fungal Genet Biol 2008; 45:1257-64. [DOI: 10.1016/j.fgb.2008.06.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 06/06/2008] [Accepted: 06/10/2008] [Indexed: 10/21/2022]
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40
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Alkan N, Fluhr R, Sherman A, Prusky D. Role of ammonia secretion and pH modulation on pathogenicity of Colletotrichum coccodes on tomato fruit. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1058-66. [PMID: 18616402 DOI: 10.1094/mpmi-21-8-1058] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Colletotrichum coccodes was found to alkalinize the decaying tissue of tomato fruit via accumulation and secretion of ammonia. Alkalinization dynamics caused by ammonia secretion from growing hyphae was examined microscopically using the pH-sensitive fluorescent dye 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. Values of pH of 7.9 observed in the host tissue close to the hyphal tips declined to pH 6.0 at 10 mm away from the hyphal tip, which was a value that was still higher than that detected in the healthy tissue, pH 4.2. Ammonia accumulation at the infection site depended on the initial environmental pH. Treatments with low (4.0) pH buffer at the infection site resulted in high levels of ammonia secretion and increased virulence of C. coccodes compared with similar treatments with buffer at pH 7.0. Significantly, mutants of C. coccodes defective in nitrogen utilization, nit-, and areA- were impaired in ammonia secretion and showed reduced decay development. The reduced infection rate of nit- mutants could be complemented by adding glutamine at the infection site. Thus, ammonia accumulation is a critical factor contributing to C. coccodes pathogenicity on tomato fruit. The results show that the initial acidic pH of the fruit is conducive to ammonia secretion and the subsequent alkalinization of the infection site, and facilitates fungal virulence and the transformation from the quiescent-biotrophic to active-necrotrophic state.
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Affiliation(s)
- N Alkan
- Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, the Volcani Center, Bet Dagan, Israel
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41
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van Esse HP, Bolton MD, Stergiopoulos I, de Wit PJGM, Thomma BPHJ. The chitin-binding Cladosporium fulvum effector protein Avr4 is a virulence factor. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:1092-101. [PMID: 17849712 DOI: 10.1094/mpmi-20-9-1092] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The biotrophic fungal pathogen Cladosporium fulvum (syn. Passalora fulva) is the causal agent of tomato leaf mold. The Avr4 protein belongs to a set of effectors that is secreted by C. fulvum during infection and is thought to play a role in pathogen virulence. Previous studies have shown that Avr4 binds to chitin present in fungal cell walls and that, through this binding, Avr4 can protect these cell walls against hydrolysis by plant chitinases. In this study, we demonstrate that Avr4 expression in Arabidopsis results in increased virulence of several fungal pathogens with exposed chitin in their cell walls, whereas the virulence of a bacterium and an oomycete remained unaltered. Heterologous expression of Avr4 in tomato increased the virulence of Fusarium oxysporum f. sp. lycopersici. Through tomato GeneChip analyses, we demonstrate that Avr4 expression in tomato results in the induced expression of only a few genes. Finally, we demonstrate that silencing of the Avr4 gene in C. fulvum decreases its virulence on tomato. This is the first report on the intrinsic function of a fungal avirulence protein that has a counter-defensive activity required for full virulence of the pathogen.
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Affiliation(s)
- H Peter van Esse
- Laboratory of Phytopathology, Centre for Biosystems Genomics (CBSG), Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands
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Jeong JS, Mitchell TK, Dean RA. TheMagnaporthe griseasnodprot1 homolog, MSP1, is required for virulence. FEMS Microbiol Lett 2007; 273:157-65. [PMID: 17590228 DOI: 10.1111/j.1574-6968.2007.00796.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Secreted proteins play central roles in plant-microbe interactions acting as signals, toxins, and effectors. One important group of small secreted proteins is the snodprot1 family, members of which have demonstrated phytotoxic properties. A split-marker transformation system was applied for gene deletion of the snodprot1 homolog, MSP1, in the rice blast fungus Magnaporthe grisea. msp1 mutants were phenotypically indistinguishable from wild type and elaborated apparently normal appressoria. However, the deletion mutants were greatly reduced in virulence primarily due to impaired growth in planta. Western blot analysis showed that the protein was secreted and not associated with the fungal cell wall. When purified MSP1 protein was applied to wounded leaf tissue, no apparent phytotoxic effects were noted. This is the first report to the authors' knowledge that directly implicates a snodprot1 protein as a virulence factor.
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Affiliation(s)
- Jun Seop Jeong
- Department of Plant Pathology, Center for Integrated Fungal Research (CIFR), North Carolina State University, Raleigh, NC 27695, USA
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43
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Keon J, Antoniw J, Carzaniga R, Deller S, Ward JL, Baker JM, Beale MH, Hammond-Kosack K, Rudd JJ. Transcriptional adaptation of Mycosphaerella graminicola to programmed cell death (PCD) of its susceptible wheat host. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:178-93. [PMID: 17313169 DOI: 10.1094/mpmi-20-2-0178] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Many important fungal pathogens of plants spend long periods (days to weeks) of their infection cycle in symptomless association with living host tissue, followed by a sudden transition to necrotrophic feeding as host tissue death occurs. Little is known about either the host responses associated with this sudden transition or the specific adaptations made by the pathogen to invoke or tolerate it. We are studying a major host-specific fungal pathogen of cultivated wheat, Septoria tritici (teleomorph Mycosphaerella graminicola). Here, we describe the host responses of wheat leaves infected with M. graminicola during the development of disease symptoms and use microarray transcription profiling to identify adaptive responses of the fungus to its changing environment. We show that symptom development on a susceptible host genotype has features reminiscent of the hypersensitive response, a rapid and strictly localized form of host programmed cell death (PCD) more commonly associated with disease-resistance mechanisms. The initiation and advancement of this host response is associated with a loss of cell-membrane integrity and dramatic increases in apoplastic metabolites and the rate of fungal growth. Microarray analysis of the fungal genes differentially expressed before and after the onset of host PCD supports a transition to more rapid growth. Specific physiological adaptation of the fungus is also revealed with respect to membrane transport, chemical and oxidative stress mechanisms, and metabolism. Our data support the hypothesis that host plant PCD plays an important role in susceptibility towards fungal pathogens with necrotrophic lifestyles.
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Affiliation(s)
- John Keon
- Wheat Pathogenesis Programme, Plant-Pathogen Interactions Division, Rothamsted Research, Harpenden, Herts AL5 2JQ, U.K
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Divon HH, Ziv C, Davydov O, Yarden O, Fluhr R. The global nitrogen regulator, FNR1, regulates fungal nutrition-genes and fitness during Fusarium oxysporum pathogenesis. MOLECULAR PLANT PATHOLOGY 2006; 7:485-97. [PMID: 20507463 DOI: 10.1111/j.1364-3703.2006.00354.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
SUMMARY Fusarium oxysporum is a soil-borne pathogen that infects plants through the roots and uses the vascular system for host ingress. Specialized for this route of infection, F. oxysporum is able to adapt to the scarce nutrient environment in the xylem vessels. Here we report the cloning of the F. oxysporum global nitrogen regulator, Fnr1, and show that it is one of the determinants for fungal fitness during in planta growth. The Fnr1 gene has a single conserved GATA-type zinc finger domain and is 96% and 48% identical to AREA-GF from Gibberella fujikuroi, and NIT2 from Neurospora crassa, respectively. Fnr1 cDNA, expressed under a constitutive promoter, was able to complement functionally an N. crassa nit-2(RIP) mutant, restoring the ability of the mutant to utilize nitrate. Fnr1 disruption mutants showed high tolerance to chlorate and reduced ability to utilize several secondary nitrogen sources such as amino acids, hypoxanthine and uric acid, whereas growth on favourable nitrogen sources was not affected. Fnr1 disruption also abolished in vitro expression of nutrition genes, normally induced during the early phase of infection. In an infection assay on tomato seedlings, infection rate of disruption mutants was significantly delayed in comparison with the parental strain. Our results indicate that FNR1 mediates adaptation to nitrogen-poor conditions in planta through the regulation of secondary nitrogen acquisition, and as such acts as a determinant for fungal fitness during infection.
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Affiliation(s)
- Hege Hvattum Divon
- Department of Plant Science, Weizmann Institute of Science, 76100 Rehovot, Israel
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45
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Cappellazzo G, Lanfranco L, Bonfante P. A limiting source of organic nitrogen induces specific transcriptional responses in the extraradical structures of the endomycorrhizal fungus Glomus intraradices. Curr Genet 2006; 51:59-70. [PMID: 17061094 DOI: 10.1007/s00294-006-0101-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/06/2006] [Accepted: 09/09/2006] [Indexed: 10/24/2022]
Abstract
The molecular bases of organic nitrogen (N) metabolism in arbuscular mycorrhizal (AM) fungi remain so far largely unexplored. To isolate genes responsive to low versus high organic N concentrations, the techniques of suppressive subtractive hybridization (SSH) and reverse Northern dot blot were performed on extraradical structures of the AM fungus Glomus intraradices grown on carrot hairy roots. This approach allowed the identification of 32 up-regulated and 2 down-regulated genes following a 48-h treatment with 2 microM of an amino acid pool (leucine, alanine, asparagine, lysine, tyrosine). The expression profile of eight genes was further confirmed by semi-quantitative and real-time RT-PCR. The majority of the sequences showed no significant similarity to proteins in databases. The other responsive genes code for putative glyoxal oxidases, transcription factors, a subunit of the 20S proteasome, a protein kinase and a Ras protein. This novel set of data indicates that G. intraradices extraradical structures perceive organic N limitation in the surrounding environment leading to a response at transcriptional level and supports the role of N as signalling molecule in AM fungi.
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Affiliation(s)
- Gilda Cappellazzo
- Dipartimento di Biologia Vegetale, Università di Torino, Viale P.A. Mattioli 25, 10125 Torino, Italy
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Solomon PS, Rybak K, Trengove RD, Oliver RP. Investigating the role of calcium/calmodulin-dependent protein kinases inStagonospora nodorum. Mol Microbiol 2006; 62:367-81. [PMID: 17020577 DOI: 10.1111/j.1365-2958.2006.05380.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three genes encoding different Ca2+/calmodulin-dependent protein kinases have been characterized in the wheat phytopathogenic fungus Stagonospora nodorum. The kinases were identified from the S. nodorum genome sequence on the basis of sequence homology to known Ca2+/calmodulin-dependent protein kinases. Expression analysis determined that each of the kinases was expressed during growth in vitro and also during infection. The onset of sporulation triggered increased transcript levels of each of the kinases, particularly CpkA where an 11-fold increase in expression was observed during sporulation in planta. The role of the kinases was further determined via a reverse genetics approach. The disruption of CpkA affected vegetative growth in vitro and also sporulation. The cpkA strains produced 20-fold less spores on complex media and were unable to sporulate on defined minimal media. Infection assays showed that CpkA was not required for lesion development but was essential for sporulation at the completion of the infection cycle. Microscopic analysis revealed that the disruption of CpkA resulted in Stagonospora nodorum being unable to differentiate the mycelial knot into immature pycnidia during sporulation. A metabolite analysis of infected leaves during sporulation excluded the possible involvement of mannitol, a compound previously shown to be involved in the sporulation of Stagonospora nodorum. The disruption of CpkB did not effect growth in vitro or pathogenicity. Stagonospora nodorum strains lacking CpkC appeared unaffected during growth in planta but showed delayed lesion development and sporulation during infection.
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Affiliation(s)
- Peter S Solomon
- Australian Centre for Necrotrophic Fungal Pathogens, SABC, School of Veterinary and Biomedical Sciences, Murdoch University, Perth, WA 6150, Australia.
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Montanini B, Gabella S, Abbà S, Peter M, Kohler A, Bonfante P, Chalot M, Martin F, Ottonello S. Gene expression profiling of the nitrogen starvation stress response in the mycorrhizal ascomycete Tuber borchii. Fungal Genet Biol 2006; 43:630-41. [PMID: 16698294 DOI: 10.1016/j.fgb.2006.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Revised: 03/31/2006] [Accepted: 04/02/2006] [Indexed: 01/04/2023]
Abstract
The focus of this work is on the nitrogen starvation stress responses operating in a plant symbiotic fungus. A cDNA array profiling analysis was conducted on N-limited mycelia of the mycorrhizal ascomycete Tuber borchii. Fifty-one unique transcripts, out of 2062 redundant arrayed cDNAs, were differentially expressed by at least 1.5-fold in response to N deprivation. Only two N assimilation components-a nitrate transporter and a high-affinity ammonium transporter-were found among differentially expressed genes. All the other N status responsive genes code for as yet unidentified hypothetical proteins or components not directly involved in N assimilation or metabolism, especially carbohydrate binding proteins and oligosaccharide as well as lipid modifying enzymes. A subset of cDNA array data were confirmed and extended by Northern blot analysis, which showed that most of the latter components respond not only to nitrogen, but also to carbon source depletion.
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Affiliation(s)
- Barbara Montanini
- Dipartimento di Biochimica e Biologia Molecolare, Università di Parma, Italy
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Donofrio NM, Oh Y, Lundy R, Pan H, Brown DE, Jeong JS, Coughlan S, Mitchell TK, Dean RA. Global gene expression during nitrogen starvation in the rice blast fungus, Magnaporthe grisea. Fungal Genet Biol 2006; 43:605-17. [PMID: 16731015 DOI: 10.1016/j.fgb.2006.03.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 02/15/2006] [Accepted: 03/24/2006] [Indexed: 01/28/2023]
Abstract
Efficient regulation of nitrogen metabolism likely plays a role in the ability of fungi to exploit ecological niches. To learn about regulation of nitrogen metabolism in the rice blast pathogen Magnaporthe grisea, we undertook a genome-wide analysis of gene expression under nitrogen-limiting conditions. Five hundred and twenty genes showed increased transcript levels at 12 and 48 h after shifting the fungus to media lacking nitrate as a nitrogen source. Thirty-nine of these genes have putative functions in amino acid metabolism and uptake, and include the global nitrogen regulator in M. grisea, NUT1. Evaluation of seven nitrogen starvation-induced genes revealed that all were expressed during rice infection. Targeted gene replacement on one such gene, the vacuolar serine protease, SPM1, resulted in decreased sporulation and appressorial development as well as a greatly attenuated ability to cause disease. Data are discussed in the context of nitrogen metabolism under starvation conditions, as well as conditions potentially encountered during invasive growth in planta.
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Affiliation(s)
- N M Donofrio
- North Carolina State University, Center for Integrated Fungal Research, Raleigh, USA
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Thomma BPHJ, Bolton MD, Clergeot PH, DE Wit PJGM. Nitrogen controls in planta expression of Cladosporium fulvum Avr9 but no other effector genes. MOLECULAR PLANT PATHOLOGY 2006; 7:125-130. [PMID: 20507433 DOI: 10.1111/j.1364-3703.2006.00320.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
SUMMARY During growth on its host tomato, the apoplast-colonizing fungal pathogen Cladosporium fulvum secretes several effector proteins. The expression of the Avr9 gene encoding one of these effector proteins has previously been shown to be strongly induced in vitro during nitrogen deprivation. This led to the hypothesis that expression of additional effector genes in C. fulvum could be triggered by nitrogen starvation conditions that are encountered in the host. We now show that expression of most effectors is not affected by varying levels of nitrogen supplementation in vitro. In addition, we demonstrate that the nitrogen response regulator Nrf1 only regulates Avr9 expression during infection of the host, whereas none of the other known effectors is significantly controlled by this transcription factor in planta. Deletion of Nrf1, but not of Avr9, significantly reduces C. fulvum virulence. Therefore, it is concluded that Nrf1 controls, in addition to Avr9, unidentified effector genes that are required for full virulence of C. fulvum.
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Affiliation(s)
- Bart P H J Thomma
- Laboratory of Phytopathology, Wageningen University, Binnenhaven 5, 6709 PD Wageningen, The Netherlands
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Pageau K, Reisdorf-Cren M, Morot-Gaudry JF, Masclaux-Daubresse C. The two senescence-related markers, GS1 (cytosolic glutamine synthetase) and GDH (glutamate dehydrogenase), involved in nitrogen mobilization, are differentially regulated during pathogen attack and by stress hormones and reactive oxygen species in Nicotiana tabacum L. leaves. JOURNAL OF EXPERIMENTAL BOTANY 2005; 57:547-57. [PMID: 16377736 DOI: 10.1093/jxb/erj035] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
To investigate the role of stress in nitrogen management in plants, the effect of pathogen attack, elicitors, and phytohormone application on the expression of the two senescence-related markers GS1 (cytosolic glutamine synthetase EC 6.3.1.2) and GDH (glutamate dehydrogenase, EC 1.4.1.2) involved in nitrogen mobilization in senescing leaves of tobacco (Nicotiana tabacum L.) plants, was studied. The expression of genes involved in primary nitrogen assimilation such as GS2 (chloroplastic glutamine synthetase) and Nia (nitrate reductase, EC 1.6.1.1) was also analysed. The Glubas gene, coding a beta-1,3-glucanase, was used as a plant-defence gene control. As during natural senescence, the expression of GS2 and Nia was repressed under almost all stress conditions. By contrast, GS1 and GDH mRNA accumulation was increased. However, GS1 and GDH showed differential patterns of expression depending on the stress applied. The expression of GS1 appeared more selective than GDH. Results indicate that the GDH and GS1 genes involved in leaf senescence are also a component of the plant defence response during plant-pathogen interaction. The links between natural plant senescence and stress-induced senescence are discussed, as well as the potential role of GS1 and GDH in a metabolic safeguard process.
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Affiliation(s)
- Karine Pageau
- INRA Unité de Nutrition Azotée des Plantes, Route de Saint Cyr, F-78 026 Versailles Cedex, France
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