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Langlands-Perry C, Pitarch A, Lapalu N, Cuenin M, Bergez C, Noly A, Amezrou R, Gélisse S, Barrachina C, Parrinello H, Suffert F, Valade R, Marcel TC. Quantitative and qualitative plant-pathogen interactions call upon similar pathogenicity genes with a spectrum of effects. FRONTIERS IN PLANT SCIENCE 2023; 14:1128546. [PMID: 37235026 PMCID: PMC10206311 DOI: 10.3389/fpls.2023.1128546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/19/2023] [Indexed: 05/28/2023]
Abstract
Septoria leaf blotch is a foliar wheat disease controlled by a combination of plant genetic resistances and fungicides use. R-gene-based qualitative resistance durability is limited due to gene-for-gene interactions with fungal avirulence (Avr) genes. Quantitative resistance is considered more durable but the mechanisms involved are not well documented. We hypothesize that genes involved in quantitative and qualitative plant-pathogen interactions are similar. A bi-parental population of Zymoseptoria tritici was inoculated on wheat cultivar 'Renan' and a linkage analysis performed to map QTL. Three pathogenicity QTL, Qzt-I05-1, Qzt-I05-6 and Qzt-I07-13, were mapped on chromosomes 1, 6 and 13 in Z. tritici, and a candidate pathogenicity gene on chromosome 6 was selected based on its effector-like characteristics. The candidate gene was cloned by Agrobacterium tumefaciens-mediated transformation, and a pathology test assessed the effect of the mutant strains on 'Renan'. This gene was demonstrated to be involved in quantitative pathogenicity. By cloning a newly annotated quantitative-effect gene in Z. tritici that is effector-like, we demonstrated that genes underlying pathogenicity QTL can be similar to Avr genes. This opens up the previously probed possibility that 'gene-for-gene' underlies not only qualitative but also quantitative plant-pathogen interactions in this pathosystem.
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Affiliation(s)
- Camilla Langlands-Perry
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
- ARVALIS Institut du Végétal, Boigneville, France
| | - Anaïs Pitarch
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Nicolas Lapalu
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Murielle Cuenin
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Alicia Noly
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | - Reda Amezrou
- Université Paris-Saclay, INRAE, UR BIOGER, Palaiseau, France
| | | | - Célia Barrachina
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Hugues Parrinello
- MGX-Montpellier GenomiX, Univ. Montpellier, CNRS, INSERM, Montpellier, France
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2
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Habig M, Schotanus K, Hufnagel K, Happel P, Stukenbrock EH. Ago1 Affects the Virulence of the Fungal Plant Pathogen Zymoseptoria tritici. Genes (Basel) 2021; 12:1011. [PMID: 34208898 PMCID: PMC8303167 DOI: 10.3390/genes12071011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/04/2022] Open
Abstract
In host-pathogen interactions RNA interference (RNAi) has emerged as a pivotal mechanism to modify both, the immune responses of the host as well as the pathogenicity and virulence of the pathogen. In addition, in some fungi RNAi is also known to affect chromosome biology via its effect on chromatin conformation. Previous studies reported no effect of the RNAi machinery on the virulence of the fungal plant pathogen Zymoseptoria tritici however the role of RNAi is still poorly understood in this species. Herein, we elucidate whether the RNAi machinery is conserved within the genus Zymoseptoria. Moreover, we conduct functional analyses of Argonaute and Dicer-like proteins and test if the RNAi machinery affects chromosome stability. We show that the RNAi machinery is conserved among closely related Zymoseptoria species while an exceptional pattern of allelic diversity was possibly caused by introgression. The deletion of Ago1 reduced the ability of the fungus to produce asexual propagules in planta in a quantitative matter. Chromosome stability of the accessory chromosome of Z. tritici was not prominently affected by the RNAi machinery. These results indicate, in contrast to previous finding, a role of the RNAi pathway during host infection, but not in the stability of accessory chromosomes in Z. tritici.
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Affiliation(s)
- Michael Habig
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Klaas Schotanus
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Kim Hufnagel
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Petra Happel
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany;
| | - Eva H. Stukenbrock
- Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 1-11, 24118 Kiel, Germany; (M.H.); (K.S.); (K.H.)
- Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
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3
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Tian H, MacKenzie CI, Rodriguez‐Moreno L, van den Berg GCM, Chen H, Rudd JJ, Mesters JR, Thomma BPHJ. Three LysM effectors of Zymoseptoria tritici collectively disarm chitin-triggered plant immunity. MOLECULAR PLANT PATHOLOGY 2021; 22:683-693. [PMID: 33797163 PMCID: PMC8126183 DOI: 10.1111/mpp.13055] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 02/24/2021] [Accepted: 03/03/2021] [Indexed: 05/09/2023]
Abstract
Chitin is a major structural component of fungal cell walls and acts as a microbe-associated molecular pattern (MAMP) that, on recognition by a plant host, triggers the activation of immune responses. To avoid the activation of these responses, the Septoria tritici blotch (STB) pathogen of wheat, Zymoseptoria tritici, secretes LysM effector proteins. Previously, the LysM effectors Mg1LysM and Mg3LysM were shown to protect fungal hyphae against host chitinases. Furthermore, Mg3LysM, but not Mg1LysM, was shown to suppress chitin-induced reactive oxygen species (ROS) production. Whereas initially a third LysM effector gene was disregarded as a presumed pseudogene, we now provide functional data to show that this gene also encodes a LysM effector, named Mgx1LysM, that is functional during wheat colonization. While Mg3LysM confers a major contribution to Z. tritici virulence, Mgx1LysM and Mg1LysM contribute to Z. tritici virulence with smaller effects. All three LysM effectors display partial functional redundancy. We furthermore demonstrate that Mgx1LysM binds chitin, suppresses the chitin-induced ROS burst, and is able to protect fungal hyphae against chitinase hydrolysis. Finally, we demonstrate that Mgx1LysM is able to undergo chitin-induced polymerization. Collectively, our data show that Z. tritici utilizes three LysM effectors to disarm chitin-triggered wheat immunity.
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Affiliation(s)
- Hui Tian
- Laboratory of PhytopathologyWageningen University and ResearchWageningenNetherlands
- Institute for Plant SciencesCluster of Excellence on Plant Sciences (CEPLAS)University of CologneCologneGermany
| | - Craig I. MacKenzie
- Laboratory of PhytopathologyWageningen University and ResearchWageningenNetherlands
| | - Luis Rodriguez‐Moreno
- Laboratory of PhytopathologyWageningen University and ResearchWageningenNetherlands
- Departamento de Biología Celular, Genética y FisiologíaUniversidad de MálagaMálagaSpain
| | | | - Hongxin Chen
- Department of Bio‐Interactions and Crop ProtectionRothamsted ResearchHarpendenUK
| | - Jason J. Rudd
- Department of Bio‐Interactions and Crop ProtectionRothamsted ResearchHarpendenUK
| | | | - Bart P. H. J. Thomma
- Laboratory of PhytopathologyWageningen University and ResearchWageningenNetherlands
- Institute for Plant SciencesCluster of Excellence on Plant Sciences (CEPLAS)University of CologneCologneGermany
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4
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Steinhauer D, Salat M, Frey R, Mosbach A, Luksch T, Balmer D, Hansen R, Widdison S, Logan G, Dietrich RA, Kema GHJ, Bieri S, Sierotzki H, Torriani SFF, Scalliet G. A dispensable paralog of succinate dehydrogenase subunit C mediates standing resistance towards a subclass of SDHI fungicides in Zymoseptoria tritici. PLoS Pathog 2019; 15:e1007780. [PMID: 31860693 PMCID: PMC6941823 DOI: 10.1371/journal.ppat.1007780] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 01/03/2020] [Accepted: 11/20/2019] [Indexed: 11/24/2022] Open
Abstract
Succinate dehydrogenase inhibitor (SDHI) fungicides are widely used for the control of a broad range of fungal diseases. This has been the most rapidly expanding fungicide group in terms of new molecules discovered and introduced for agricultural use over the past fifteen years. A particular pattern of differential sensitivity (resistance) to the stretched heterocycle amide SDHIs (SHA-SDHIs), a subclass of chemically-related SDHIs, was observed in naïve Zymoseptoria tritici populations not previously exposed to these chemicals. Subclass-specific resistance was confirmed at the enzyme level but did not correlate with the genotypes of the succinate dehydrogenase (SDH) encoding genes. Mapping and characterization of the molecular mechanisms responsible for standing SHA-SDHI resistance in natural field isolates identified a gene paralog of SDHC, termed ZtSDHC3, which encodes for an alternative C subunit of succinate dehydrogenase, named alt-SDHC. Using reverse genetics, we showed that alt-SDHC associates with the three other SDH subunits, leading to a fully functional enzyme and that a unique Qp-site residue within the alt-SDHC protein confers SHA-SDHI resistance. Enzymatic assays, computational modelling and docking simulations for the two SQR enzymes (altC-SQR, WT_SQR) enabled us to describe enzyme-inhibitor interactions at an atomistic level and to propose rational explanations for differential potency and resistance across SHA-SDHIs. European Z. tritici populations displayed a presence (20–30%) / absence polymorphism of ZtSDHC3, as well as differences in ZtSDHC3 expression levels and splicing efficiency. These polymorphisms have a strong impact on SHA-SDHI resistance phenotypes. Characterization of the ZtSDHC3 promoter in European Z. tritici populations suggests that transposon insertions are associated with the strongest resistance phenotypes. These results establish that a dispensable paralogous gene determines SHA-SDHIs fungicide resistance in natural populations of Z. tritici. This study paves the way to an increased awareness of the role of fungicidal target paralogs in resistance to fungicides and demonstrates the paramount importance of population genomics in fungicide discovery. Zymoseptoria tritici is the causal agent of Septoria tritici leaf blotch (STB) of wheat, the most devastating disease for cereal production in Europe. Multiple succinate dehydrogenase inhibitor (SDHI) fungicides have been developed and introduced for the control of STB. We report the discovery and detailed characterization of a paralog of the C subunit of the SDH enzyme conferring standing resistance towards the SHA-SDHIs, a particular chemical subclass of the SDHIs. The SDHC paralog is characterized by its presence/absence, expression and alternative splicing polymorphisms, which in turn influence resistance levels. The identified mechanisms exemplify the importance of population genomics for the discovery and rational design of the most adapted solutions.
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Affiliation(s)
| | - Marie Salat
- Syngenta Crop Protection AG, Stein, Switzerland
| | - Regula Frey
- Syngenta Crop Protection AG, Stein, Switzerland
| | | | | | - Dirk Balmer
- Syngenta Crop Protection AG, Stein, Switzerland
| | - Rasmus Hansen
- Syngenta Jealott’s Hill Int. Research Centre, Bracknell Berkshire, United Kingdom
| | - Stephanie Widdison
- Syngenta Jealott’s Hill Int. Research Centre, Bracknell Berkshire, United Kingdom
| | - Grace Logan
- Syngenta Jealott’s Hill Int. Research Centre, Bracknell Berkshire, United Kingdom
| | - Robert A. Dietrich
- Syngenta Biotechnology Inc., Research Triangle Park, North Carolina, United States of America
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5
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Kettles GJ, Hofinger BJ, Hu P, Bayon C, Rudd JJ, Balmer D, Courbot M, Hammond-Kosack KE, Scalliet G, Kanyuka K. sRNA Profiling Combined With Gene Function Analysis Reveals a Lack of Evidence for Cross-Kingdom RNAi in the Wheat - Zymoseptoria tritici Pathosystem. FRONTIERS IN PLANT SCIENCE 2019; 10:892. [PMID: 31333714 PMCID: PMC6620828 DOI: 10.3389/fpls.2019.00892] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 06/21/2019] [Indexed: 05/19/2023]
Abstract
Cross-kingdom small RNA (sRNA) silencing has recently emerged as a mechanism facilitating fungal colonization and disease development. Here we characterized RNAi pathways in Zymoseptoria tritici, a major fungal pathogen of wheat, and assessed their contribution to pathogenesis. Computational analysis of fungal sRNA and host mRNA sequencing datasets was used to define the global sRNA populations in Z. tritici and predict their mRNA targets in wheat. 389 in planta-induced sRNA loci were identified. sRNAs generated from some of these loci were predicted to target wheat mRNAs including those potentially involved in pathogen defense. However, molecular approaches failed to validate targeting of selected wheat mRNAs by fungal sRNAs. Mutant strains of Z. tritici carrying deletions of genes encoding key components of RNAi such as Dicer-like (DCL) and Argonaute (AGO) proteins were generated, and virulence bioassays suggested that these are dispensable for full infection of wheat. Nonetheless, our results did suggest the existence of non-canonical DCL-independent pathway(s) for sRNA biogenesis in Z. tritici. dsRNA targeting essential fungal genes applied in vitro or generated from an RNA virus vector in planta in a procedure known as HIGS (Host-Induced Gene Silencing) was ineffective in preventing Z. tritici growth or disease. We also demonstrated that Z. tritici is incapable of dsRNA uptake. Collectively, our data suggest that RNAi approaches for gene function analyses in this fungal species and potentially also as a control measure may not be as effective as has been demonstrated for some other plant pathogenic fungi.
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Affiliation(s)
- Graeme J. Kettles
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, United Kingdom
| | - Bernhard J. Hofinger
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, United Kingdom
| | - Pingsha Hu
- Syngenta Biotechnology, Inc., Research Triangle Park, NC, United States
| | - Carlos Bayon
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, United Kingdom
| | - Jason J. Rudd
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, United Kingdom
| | - Dirk Balmer
- Syngenta Crop Protection AG, Stein, Switzerland
| | | | | | | | - Kostya Kanyuka
- Biointeractions and Crop Protection, Rothamsted Research, Harpenden, United Kingdom
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6
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Möller M, Schotanus K, Soyer JL, Haueisen J, Happ K, Stralucke M, Happel P, Smith KM, Connolly LR, Freitag M, Stukenbrock EH. Destabilization of chromosome structure by histone H3 lysine 27 methylation. PLoS Genet 2019; 15:e1008093. [PMID: 31009462 PMCID: PMC6510446 DOI: 10.1371/journal.pgen.1008093] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Revised: 05/10/2019] [Accepted: 03/15/2019] [Indexed: 01/23/2023] Open
Abstract
Chromosome and genome stability are important for normal cell function as instability often correlates with disease and dysfunction of DNA repair mechanisms. Many organisms maintain supernumerary or accessory chromosomes that deviate from standard chromosomes. The pathogenic fungus Zymoseptoria tritici has as many as eight accessory chromosomes, which are highly unstable during meiosis and mitosis, transcriptionally repressed, show enrichment of repetitive elements, and enrichment with heterochromatic histone methylation marks, e.g., trimethylation of H3 lysine 9 or lysine 27 (H3K9me3, H3K27me3). To elucidate the role of heterochromatin on genome stability in Z. tritici, we deleted the genes encoding the methyltransferases responsible for H3K9me3 and H3K27me3, kmt1 and kmt6, respectively, and generated a double mutant. We combined experimental evolution and genomic analyses to determine the impact of these deletions on chromosome and genome stability, both in vitro and in planta. We used whole genome sequencing, ChIP-seq, and RNA-seq to compare changes in genome and chromatin structure, and differences in gene expression between mutant and wildtype strains. Analyses of genome and ChIP-seq data in H3K9me3-deficient strains revealed dramatic chromatin reorganization, where H3K27me3 is mostly relocalized into regions that are enriched with H3K9me3 in wild type. Many genome rearrangements and formation of new chromosomes were found in the absence of H3K9me3, accompanied by activation of transposable elements. In stark contrast, loss of H3K27me3 actually increased the stability of accessory chromosomes under normal growth conditions in vitro, even without large scale changes in gene activity. We conclude that H3K9me3 is important for the maintenance of genome stability because it disallows H3K27me3 in regions considered constitutive heterochromatin. In this system, H3K27me3 reduces the overall stability of accessory chromosomes, generating a "metastable" state for these quasi-essential regions of the genome.
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Affiliation(s)
- Mareike Möller
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Klaas Schotanus
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, United States of America
| | - Jessica L. Soyer
- UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, Thiverval-Grignon, France
| | - Janine Haueisen
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Kathrin Happ
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
| | - Maja Stralucke
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
| | - Petra Happel
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Kristina M. Smith
- Department of Biology, Oregon State University—Cascades, Bend, OR, United States of America
| | - Lanelle R. Connolly
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States of America
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States of America
| | - Eva H. Stukenbrock
- Environmental Genomics, Christian-Albrechts University, Kiel, Germany
- Max Planck Fellow Group Environmental Genomics, Max Planck Institute for Evolutionary Biology, Plön, Germany
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7
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Derbyshire MC, Gohari AM, Mehrabi R, Kilaru S, Steinberg G, Ali S, Bailey A, Hammond-Kosack K, Kema GHJ, Rudd JJ. Phosphopantetheinyl transferase (Ppt)-mediated biosynthesis of lysine, but not siderophores or DHN melanin, is required for virulence of Zymoseptoria tritici on wheat. Sci Rep 2018; 8:17069. [PMID: 30459352 PMCID: PMC6244202 DOI: 10.1038/s41598-018-35223-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 10/30/2018] [Indexed: 12/19/2022] Open
Abstract
Zymoseptoria tritici is the causal agent of Septoria tritici blotch (STB) disease of wheat. Z. tritici is an apoplastic fungal pathogen, which does not penetrate plant cells at any stage of infection, and has a long initial period of symptomless leaf colonisation. During this phase it is unclear to what extent the fungus can access host plant nutrients or communicate with plant cells. Several important primary and secondary metabolite pathways in fungi are regulated by the post-translational activator phosphopantetheinyl transferase (Ppt) which provides an essential co-factor for lysine biosynthesis and the activities of non-ribosomal peptide synthases (NRPS) and polyketide synthases (PKS). To investigate the relative importance of lysine biosynthesis, NRPS-based siderophore production and PKS-based DHN melanin biosynthesis, we generated deletion mutants of ZtPpt. The ∆ZtPpt strains were auxotrophic for lysine and iron, non-melanised and non-pathogenic on wheat. Deletion of the three target genes likely affected by ZtPpt loss of function (Aar- lysine; Nrps1-siderophore and Pks1- melanin), highlighted that lysine auxotrophy was the main contributing factor for loss of virulence, with no reduction caused by loss of siderophore production or melanisation. This reveals Ppt, and the lysine biosynthesis pathway, as potential targets for fungicides effective against Z. tritici.
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Affiliation(s)
- Mark C Derbyshire
- BioIntercations and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, UK.,Centre for Crop and Disease Management, Curtin University, Perth, Australia
| | - Amir Mirzadi Gohari
- Department of Plant Pathology, Faculty of Agricultural Sciences and Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.,Wageningen University and Research, Wageningen Plant Research, PO Box 16, 6700AA, Wageningen, The Netherlands
| | - Rahim Mehrabi
- Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | | | | | - Solaf Ali
- Technical College of Health, Sulaimani Polytechnic University, Qrga, Wrme Street, Mardin 327, Alley 76, Sulaimaniyah, Kurdistan Region of Iraq, Sulaimani Governorate, Iraq
| | - Andy Bailey
- School of Biological Sciences, Bristol University, 24 Tyndall Avenue, Bristol, UK
| | - Kim Hammond-Kosack
- BioIntercations and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, UK
| | - Gert H J Kema
- Wageningen University and Research, Wageningen Plant Research, PO Box 16, 6700AA, Wageningen, The Netherlands. .,Wageningen University and Research, Laboratory of Phytopathology, PO box 16, 6700AA, Wageningen, The Netherlands.
| | - Jason J Rudd
- BioIntercations and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, UK.
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8
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Tiley AMM, Foster GD, Bailey AM. Exploring the Genetic Regulation of Asexual Sporulation in Zymoseptoria tritici. Front Microbiol 2018; 9:1859. [PMID: 30154771 PMCID: PMC6102487 DOI: 10.3389/fmicb.2018.01859] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/24/2018] [Indexed: 01/03/2023] Open
Abstract
Zymoseptoria tritici is the causal agent of septoria tritici blotch, a devastating fungal disease of wheat which can cause up to 40% yield loss. One of the ways in which Z. tritici spreads in the field is via rain splash-dispersed asexual pycnidiospores, however there is currently limited understanding of the genetic mechanisms governing the development of these propagules. In order to explore whether the existing models for conidiation in ascomycete fungi apply to Z. tritici, homologs to the well-characterized Aspergillus nidulans genes abacus (abaA), bristle (brlA), fluffy B (flbB), fluffy C (flbC), and stunted (stuA) were identified and knocked-out by Agrobacterium-mediated transformation. Although deletion of the ZtAbaA, ZtBrlA1, and ZtFlbB genes had no apparent effect on Z. tritici asexual sporulation or on pathogenicity, deletion of ZtFlbC or ZtBrlA2 resulted in mutants with reduced pycnidiospore production compared to the parental IPO323 strain. Deletion of ZtStuA gave non-pigmented mutants with altered vegetative growth and eliminated asexual sporulation and pathogenicity. These findings suggest that the well-established A. nidulans model of asexual sporulation is only partially applicable to Z. tritici, and that this pathogen likely uses additional, as yet uncharacterized genes to control asexual sporulation.
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Affiliation(s)
- Anna M M Tiley
- Molecular Plant Pathology and Fungal Biology Group, School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Gary D Foster
- Molecular Plant Pathology and Fungal Biology Group, School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Andy M Bailey
- Molecular Plant Pathology and Fungal Biology Group, School of Biological Sciences, University of Bristol, Bristol, United Kingdom
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9
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Kettles GJ, Bayon C, Sparks CA, Canning G, Kanyuka K, Rudd JJ. Characterization of an antimicrobial and phytotoxic ribonuclease secreted by the fungal wheat pathogen Zymoseptoria tritici. THE NEW PHYTOLOGIST 2018; 217:320-331. [PMID: 28895153 PMCID: PMC5724701 DOI: 10.1111/nph.14786] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/11/2017] [Indexed: 05/19/2023]
Abstract
The fungus Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB) disease of wheat leaves. Zymoseptoria tritici secretes many functionally uncharacterized effector proteins during infection. Here, we characterized a secreted ribonuclease (Zt6) with an unusual biphasic expression pattern. Transient expression systems were used to characterize Zt6, and mutants thereof, in both host and non-host plants. Cell-free protein expression systems monitored the impact of Zt6 protein on functional ribosomes, and in vitro assays of cells treated with recombinant Zt6 determined toxicity against bacteria, yeasts and filamentous fungi. We demonstrated that Zt6 is a functional ribonuclease and that phytotoxicity is dependent on both the presence of a 22-amino-acid N-terminal 'loop' region and its catalytic activity. Zt6 selectively cleaves both plant and animal rRNA species, and is toxic to wheat, tobacco, bacterial and yeast cells, but not to Z. tritici itself. Zt6 is the first Z. tritici effector demonstrated to have a likely dual functionality. The expression pattern of Zt6 and potent toxicity towards microorganisms suggest that, although it may contribute to the execution of wheat cell death, it is also likely to have an important secondary function in antimicrobial competition and niche protection.
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Affiliation(s)
- Graeme J. Kettles
- Biointeractions & Crop ProtectionRothamsted ResearchHarpendenAL5 2JQUK
| | - Carlos Bayon
- Biointeractions & Crop ProtectionRothamsted ResearchHarpendenAL5 2JQUK
| | | | - Gail Canning
- Biointeractions & Crop ProtectionRothamsted ResearchHarpendenAL5 2JQUK
| | - Kostya Kanyuka
- Biointeractions & Crop ProtectionRothamsted ResearchHarpendenAL5 2JQUK
| | - Jason J. Rudd
- Biointeractions & Crop ProtectionRothamsted ResearchHarpendenAL5 2JQUK
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10
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King R, Urban M, Lauder RP, Hawkins N, Evans M, Plummer A, Halsey K, Lovegrove A, Hammond-Kosack K, Rudd JJ. A conserved fungal glycosyltransferase facilitates pathogenesis of plants by enabling hyphal growth on solid surfaces. PLoS Pathog 2017; 13:e1006672. [PMID: 29020037 PMCID: PMC5653360 DOI: 10.1371/journal.ppat.1006672] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/23/2017] [Accepted: 09/27/2017] [Indexed: 11/18/2022] Open
Abstract
Pathogenic fungi must extend filamentous hyphae across solid surfaces to cause diseases of plants. However, the full inventory of genes which support this is incomplete and many may be currently concealed due to their essentiality for the hyphal growth form. During a random T-DNA mutagenesis screen performed on the pleomorphic wheat (Triticum aestivum) pathogen Zymoseptoria tritici, we acquired a mutant unable to extend hyphae specifically when on solid surfaces. In contrast "yeast-like" growth, and all other growth forms, were unaffected. The inability to extend surface hyphae resulted in a complete loss of virulence on plants. The affected gene encoded a predicted type 2 glycosyltransferase (ZtGT2). Analysis of >800 genomes from taxonomically diverse fungi highlighted a generally widespread, but discontinuous, distribution of ZtGT2 orthologues, and a complete absence of any similar proteins in non-filamentous ascomycete yeasts. Deletion mutants of the ZtGT2 orthologue in the taxonomically un-related fungus Fusarium graminearum were also severely impaired in hyphal growth and non-pathogenic on wheat ears. ZtGT2 expression increased during filamentous growth and electron microscopy on deletion mutants (ΔZtGT2) suggested the protein functions to maintain the outermost surface of the fungal cell wall. Despite this, adhesion to leaf surfaces was unaffected in ΔZtGT2 mutants and global RNAseq-based gene expression profiling highlighted that surface-sensing and protein secretion was also largely unaffected. However, ΔZtGT2 mutants constitutively overexpressed several transmembrane and secreted proteins, including an important LysM-domain chitin-binding virulence effector, Zt3LysM. ZtGT2 likely functions in the synthesis of a currently unknown, potentially minor but widespread, extracellular or outer cell wall polysaccharide which plays a key role in facilitating many interactions between plants and fungi by enabling hyphal growth on solid matrices.
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Affiliation(s)
- Robert King
- Department of Computational and Analytical Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Martin Urban
- Wheat Pathogenomics Team, Department of BioInteractions and Crop Protection, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Rebecca P. Lauder
- Rothamsted Centre for Bioimaging, Department of Plant Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Nichola Hawkins
- Fungicide resistance group, Department of BioInteractions and Crop Protection, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Matthew Evans
- Cereal cell walls group, Department of Plant Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Amy Plummer
- Cereal cell walls group, Department of Plant Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Kirstie Halsey
- Rothamsted Centre for Bioimaging, Department of Plant Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Alison Lovegrove
- Cereal cell walls group, Department of Plant Sciences, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Kim Hammond-Kosack
- Wheat Pathogenomics Team, Department of BioInteractions and Crop Protection, Rothamsted Research, Harpenden, Herts, United Kingdom
| | - Jason J. Rudd
- Wheat Pathogenomics Team, Department of BioInteractions and Crop Protection, Rothamsted Research, Harpenden, Herts, United Kingdom
- * E-mail:
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11
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Sidhu YS, Cairns TC, Chaudhari YK, Usher J, Talbot NJ, Studholme DJ, Csukai M, Haynes K. Exploitation of sulfonylurea resistance marker and non-homologous end joining mutants for functional analysis in Zymoseptoria tritici. Fungal Genet Biol 2016; 79:102-9. [PMID: 26092796 PMCID: PMC4502460 DOI: 10.1016/j.fgb.2015.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/10/2015] [Accepted: 04/13/2015] [Indexed: 11/25/2022]
Abstract
We have constructed Z. tritici ku70 and ku80 null mutants. Gene targeting frequency in the ku null strains is greater than 85%. Deletion of KU70 and KU80 does not affect in vitro growth or pathogenicity. Sulfonylurea resistance was established as a new positive selection marker in Z. tritici. Ternary vectors were constructed to enable yeast recombinational cloning in Z. tritici.
The lack of techniques for rapid assembly of gene deletion vectors, paucity of selectable marker genes available for genetic manipulation and low frequency of homologous recombination are major constraints in construction of gene deletion mutants in Zymoseptoria tritici. To address these issues, we have constructed ternary vectors for Agrobacterium tumefaciens mediated transformation of Z. tritici, which enable the single step assembly of multiple fragments via yeast recombinational cloning. The sulfonylurea resistance gene, which is a mutated allele of the Magnaporthe oryzae ILV2 gene, was established as a new dominant selectable marker for Z. tritici. To increase the frequency of homologous recombination, we have constructed Z. tritici strains deficient in the non-homologous end joining pathway of DNA double stranded break repair by inactivating the KU70 and KU80 genes. Targeted gene deletion frequency increased to more than 85% in both Z. tritici ku70 and ku80 null strains, compared to ⩽10% seen in the wild type parental strain IPO323. The in vitro growth and in planta pathogenicity of the Z. tritici ku70 and ku80 null strains were comparable to strain IPO323. Together these molecular tools add significantly to the platform available for genomic analysis through targeted gene deletion or promoter replacements and will facilitate large-scale functional characterization projects in Z. tritici.
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Affiliation(s)
- Y S Sidhu
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - T C Cairns
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Y K Chaudhari
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - J Usher
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - N J Talbot
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - D J Studholme
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - M Csukai
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG426EY, UK
| | - K Haynes
- Biosciences, University of Exeter, Stocker Road, Exeter EX4 4QD, UK.
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12
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Kilaru S, Steinberg G. Yeast recombination-based cloning as an efficient way of constructing vectors for Zymoseptoria tritici. Fungal Genet Biol 2016; 79:76-83. [PMID: 26092792 PMCID: PMC4502459 DOI: 10.1016/j.fgb.2015.03.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/13/2015] [Accepted: 03/21/2015] [Indexed: 11/28/2022]
Abstract
Yeast recombination-based cloning (YRBC) is a reliable and inexpensive way of generating plasmids. We provide 4 vectors for YRBC that a cover different resistance genes. Using this technique promises rapid generation of molecular tools to study Z. tritici.
Many pathogenic fungi are genetically tractable. Analysis of their cellular organization and invasion mechanisms underpinning virulence determinants profits from exploiting such molecular tools as fluorescent fusion proteins or conditional mutant protein alleles. Generation of these tools requires efficient cloning methods, as vector construction is often a rate-limiting step. Here, we introduce an efficient yeast recombination-based cloning (YRBC) method to construct vectors for the fungus Zymoseptoria tritici. This method is of low cost and avoids dependency on the availability of restriction enzyme sites in the DNA sequence, as needed in more conventional restriction/ligation-based cloning procedures. Furthermore, YRBC avoids modification of the DNA of interest, indeed this potential risk limits the use of site-specific recombination systems, such as Gateway cloning. Instead, in YRBC, multiple DNA fragments, with 30 bp overlap sequences, are transformed into Saccharomyces cerevisiae, whereupon homologous recombination generates the vector in a single step. Here, we provide a detailed experimental protocol and four vectors, each encoding a different dominant selectable marker cassette, that enable YRBC of constructs to be used in the wheat pathogen Z. tritici.
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Affiliation(s)
- S Kilaru
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK.
| | - G Steinberg
- School of Biosciences, University of Exeter, Exeter EX4 4QD, UK
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13
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Schotanus K, Soyer JL, Connolly LR, Grandaubert J, Happel P, Smith KM, Freitag M, Stukenbrock EH. Histone modifications rather than the novel regional centromeres of Zymoseptoria tritici distinguish core and accessory chromosomes. Epigenetics Chromatin 2015; 8:41. [PMID: 26430472 PMCID: PMC4589918 DOI: 10.1186/s13072-015-0033-5] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 09/21/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Supernumerary chromosomes have been found in many organisms. In fungi, these "accessory" or "dispensable" chromosomes are present at different frequencies in populations and are usually characterized by higher repetitive DNA content and lower gene density when compared to the core chromosomes. In the reference strain of the wheat pathogen, Zymoseptoria tritici, eight discrete accessory chromosomes have been found. So far, no functional role has been assigned to these chromosomes; however, they have existed as separate entities in the karyotypes of Zymoseptoria species over evolutionary time. In this study, we addressed what-if anything-distinguishes the chromatin of accessory chromosomes from core chromosomes. We used chromatin immunoprecipitation combined with high-throughput sequencing ("ChIP-seq") of DNA associated with the centromere-specific histone H3, CENP-A (CenH3), to identify centromeric DNA, and ChIP-seq with antibodies against dimethylated H3K4, trimethylated H3K9 and trimethylated H3K27 to determine the relative distribution and proportion of euchromatin, obligate and facultative heterochromatin, respectively. RESULTS Centromeres of the eight accessory chromosomes have the same sequence composition and structure as centromeres of the 13 core chromosomes and they are of similar length. Unlike those of most other fungi, Z. tritici centromeres are not composed entirely of repetitive DNA; some centromeres contain only unique DNA sequences, and bona fide expressed genes are located in regions enriched with CenH3. By fluorescence microscopy, we showed that centromeres of Z. tritici do not cluster into a single chromocenter during interphase. We found dramatically higher enrichment of H3K9me3 and H3K27me3 on the accessory chromosomes, consistent with the twofold higher proportion of repetitive DNA and poorly transcribed genes. In contrast, no single histone modification tested here correlated with the distribution of centromeric nucleosomes. CONCLUSIONS All centromeres are similar in length and composed of a mixture of unique and repeat DNA, and most contain actively transcribed genes. Centromeres, subtelomeric regions or telomere repeat length cannot account for the differences in transfer fidelity between core and accessory chromosomes, but accessory chromosomes are greatly enriched in nucleosomes with H3K27 trimethylation. Genes on accessory chromosomes appear to be silenced by trimethylation of H3K9 and H3K27.
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Affiliation(s)
- Klaas Schotanus
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Jessica L Soyer
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; INRA, UMR 1290 INRA-AgroParisTech BIOGER, Avenue Lucien Brétignières, Thiverval-Grignon, 78850 France ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Lanelle R Connolly
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Jonathan Grandaubert
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
| | - Petra Happel
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany
| | - Kristina M Smith
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331-7303 USA
| | - Eva H Stukenbrock
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch Strasse 10, 35043 Marburg, Germany ; Christian-Albrechts University of Kiel, Environmental Genomics, Am Botanischen Garten 9-11, 24118 Kiel, Germany ; Max Planck Institute for Evolutionary Biology, August-Thienemann-Str. 2, 24306 Plön, Germany
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14
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Derbyshire MC, Michaelson L, Parker J, Kelly S, Thacker U, Powers SJ, Bailey A, Hammond-Kosack K, Courbot M, Rudd J. Analysis of cytochrome b(5) reductase-mediated metabolism in the phytopathogenic fungus Zymoseptoria tritici reveals novel functionalities implicated in virulence. Fungal Genet Biol 2015; 82:69-84. [PMID: 26074495 PMCID: PMC4557397 DOI: 10.1016/j.fgb.2015.05.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 12/15/2022]
Abstract
Septoria tritici blotch (STB) caused by the Ascomycete fungus Zymoseptoria tritici is one of the most economically damaging diseases of wheat worldwide. Z. tritici is currently a major target for agricultural fungicides, especially in temperate regions where it is most prevalent. Many fungicides target electron transfer enzymes because these are often important for cell function. Therefore characterisation of genes encoding such enzymes may be important for the development of novel disease intervention strategies. Microsomal cytochrome b5 reductases (CBRs) are an important family of electron transfer proteins which in eukaryotes are involved in the biosynthesis of fatty acids and complex lipids including sphingolipids and sterols. Unlike the model yeast Saccharomyces cerevisiae which possesses only one microsomal CBR, the fully sequenced genome of Z. tritici bears three possible microsomal CBRs. RNA sequencing analysis revealed that ZtCBR1 is the most highly expressed of these genes under all in vitro and in planta conditions tested, therefore ΔZtCBR1 mutant strains were generated through targeted gene disruption. These strains exhibited delayed disease symptoms on wheat leaves and severely limited asexual sporulation. ΔZtCBR1 strains also exhibited aberrant spore morphology and hyphal growth in vitro. These defects coincided with alterations in fatty acid, sphingolipid and sterol biosynthesis observed through GC-MS and HPLC analyses. Data is presented which suggests that Z. tritici may use ZtCBR1 as an additional electron donor for key steps in ergosterol biosynthesis, one of which is targeted by azole fungicides. Our study reports the first functional characterisation of CBR gene family members in a plant pathogenic filamentous fungus. This also represents the first direct observation of CBR functional ablation impacting upon fungal sterol biosynthesis.
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Affiliation(s)
- Mark C Derbyshire
- Department of Plant Biology and Crop Science, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK.
| | - Louise Michaelson
- Department of Biological Chemistry and Crop Protection, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Josie Parker
- Centre for Cytochrome P450 Diversity, Institute of Life Science, College of Medicine, Swansea University Singleton Park, Swansea SA2 8PP, Wales, UK
| | - Steven Kelly
- Centre for Cytochrome P450 Diversity, Institute of Life Science, College of Medicine, Swansea University Singleton Park, Swansea SA2 8PP, Wales, UK
| | | | - Stephen J Powers
- Department of Computational and Systems Biology, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Andy Bailey
- Bristol University, Senate House, Tyndall Avenue, Bristol BS8 1TH, UK
| | - Kim Hammond-Kosack
- Department of Plant Biology and Crop Science, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Mikael Courbot
- Syngenta, Syngenta AG, Schaffhauserstrasse, CH-4332 Stein, Switzerland
| | - Jason Rudd
- Department of Plant Biology and Crop Science, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK.
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15
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Poppe S, Dorsheimer L, Happel P, Stukenbrock EH. Rapidly Evolving Genes Are Key Players in Host Specialization and Virulence of the Fungal Wheat Pathogen Zymoseptoria tritici (Mycosphaerella graminicola). PLoS Pathog 2015. [PMID: 26225424 PMCID: PMC4520584 DOI: 10.1371/journal.ppat.1005055] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The speciation of pathogens can be driven by divergent host specialization. Specialization to a new host is possible via the acquisition of advantageous mutations fixed by positive selection. Comparative genome analyses of closely related species allows for the identification of such key substitutions via inference of genome-wide signatures of positive selection. We previously used a comparative genomics framework to identify genes that have evolved under positive selection during speciation of the prominent wheat pathogen Zymoseptoria tritici (synonym Mycosphaerella graminicola). In this study, we conducted functional analyses of four genes exhibiting strong signatures of positive selection in Z. tritici. We deleted the four genes in Z. tritici and confirm a virulence-related role of three of the four genes ΔZt80707, ΔZt89160 and ΔZt103264. The two mutants ΔZt80707 and ΔZt103264 show a significant reduction in virulence during infection of wheat; the ΔZt89160 mutant causes a hypervirulent phenotype in wheat. Mutant phenotypes of ΔZt80707, ΔZt89160 and ΔZt103264 can be restored by insertion of the wild-type genes. However, the insertion of the Zt80707 and Zt89160 orthologs from Z. pseudotritici and Z. ardabiliae do not restore wild-type levels of virulence, suggesting that positively selected substitutions in Z. tritici may relate to divergent host specialization. Interestingly, the gene Zt80707 encodes also a secretion signal that targets the protein for cell secretion. This secretion signal is however only transcribed in Z. tritici, suggesting that Z. tritici-specific substitutions relate to a new function of the protein in the extracellular space of the wheat-Z. tritici interaction. Together, the results presented here highlight that Zt80707, Zt103264 and Zt89160 represent key genes involved in virulence and host-specific disease development of Z. tritici. Our findings illustrate that evolutionary predictions provide a powerful tool for the identification of novel traits crucial for host adaptation and pathogen evolution. Zymoseptoria spp provides a unique model system to study the underlying genetics of host specialization of plant pathogens. Closely related Zymoseptoria species, including the prominent wheat pathogen Z. tritici, have recently specialized to distinct grass hosts. Positively selected substitutions have played a central role in the acquisition of new host specificities. We have identified a small set of genes showing signatures of positive selection. We demonstrate that three of these four candidate genes play an important role during host infection. Two mutants of Z. tritici were impaired in virulence; a third mutant showed a hypervirulent phenotype. New protein specificities not only include changes at the amino acid sequence level but also at the level of the protein structure. We conducted a gene replacement experiment to test if mutant phenotypes in Z. tritici could be complemented by the insertion of orthologous genes from the two closely related species Z. pseudotritici and Z. ardabiliae. For two genes, we confirm that the species-specific protein changes are essential for proper protein functioning in Z. tritici; key traits involved in the evolution of virulence and host specificity of this prominent pathogen can be characterized via a combination of evolutionary predictions and functional analyses.
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Affiliation(s)
- Stephan Poppe
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lena Dorsheimer
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Petra Happel
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Eva Holtgrewe Stukenbrock
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- * E-mail:
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16
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Rudd JJ. Previous bottlenecks and future solutions to dissecting the Zymoseptoria tritici-wheat host-pathogen interaction. Fungal Genet Biol 2015; 79:24-8. [PMID: 26092786 PMCID: PMC4502452 DOI: 10.1016/j.fgb.2015.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 11/24/2022]
Abstract
Zymoseptoria tritici (previously Mycosphaerella graminicola, teleomorph, Septoria tritici, anamorph) causes Septoria tritici blotch, one of the most economically important diseases of wheat (Triticum aestivum). The host pathogenic interaction, as currently understood, is intriguing, and may distinguish Z. tritici from many of the current models for plant pathogenic fungi. Many important questions remain which require a deeper understanding including; the nature and biological significance of the characteristic long latent periods of symptomless plant infection; how/why the fungus then effectively transitions from this to cause disease and reproduce? Elements of this transition currently resemble a putative "hijack" on plant defence but how is Z. tritici able to do this without any form of plant cell penetration? This commentary provides a summary of the recent history of research into the host-pathogen interaction, whilst highlighting some of the challenges going forwards, which will be faced by improved technologies and a growing research community.
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Affiliation(s)
- Jason J Rudd
- Department of Plant Biology and Crop Science, Rothamsted Research, Harpenden, Herts AL5 2JQ, UK.
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17
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Schuster M, Kilaru S, Latz M, Steinberg G. Fluorescent markers of the microtubule cytoskeleton in Zymoseptoria tritici. Fungal Genet Biol 2015; 79:141-9. [PMID: 25857261 PMCID: PMC4502552 DOI: 10.1016/j.fgb.2015.03.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 03/12/2015] [Accepted: 03/17/2015] [Indexed: 11/28/2022]
Abstract
The microtubule cytoskeleton supports vital processes in fungal cells, including hyphal growth and mitosis. Consequently, it is a target for fungicides, such as benomyl. The use of fluorescent fusion proteins to illuminate microtubules and microtubule-associated proteins has led to a break-through in our understanding of their dynamics and function in fungal cells. Here, we introduce fluorescent markers to visualize microtubules and accessory proteins in the wheat pathogen Zymoseptoria tritici. We fused enhanced green-fluorescent protein to α-tubulin (ZtTub2), to ZtPeb1, a homologue of the mammalian plus-end binding protein EB1, and to ZtGrc1, a component of the minus-end located γ-tubulin ring complex, involved in the nucleation of microtubules. In vivo observation confirms the localization and dynamic behaviour of all three markers. These marker proteins are useful tools for understanding the organization and importance of the microtubule cytoskeleton in Z. tritici.
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Affiliation(s)
- M Schuster
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - S Kilaru
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - M Latz
- Biosciences, University of Exeter, Exeter EX4 4QD, UK
| | - G Steinberg
- Biosciences, University of Exeter, Exeter EX4 4QD, UK.
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18
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Rudd JJ, Kanyuka K, Hassani-Pak K, Derbyshire M, Andongabo A, Devonshire J, Lysenko A, Saqi M, Desai NM, Powers SJ, Hooper J, Ambroso L, Bharti A, Farmer A, Hammond-Kosack KE, Dietrich RA, Courbot M. Transcriptome and metabolite profiling of the infection cycle of Zymoseptoria tritici on wheat reveals a biphasic interaction with plant immunity involving differential pathogen chromosomal contributions and a variation on the hemibiotrophic lifestyle definition. PLANT PHYSIOLOGY 2015; 167:1158-85. [PMID: 25596183 PMCID: PMC4348787 DOI: 10.1104/pp.114.255927] [Citation(s) in RCA: 180] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 01/16/2015] [Indexed: 05/17/2023]
Abstract
The hemibiotrophic fungus Zymoseptoria tritici causes Septoria tritici blotch disease of wheat (Triticum aestivum). Pathogen reproduction on wheat occurs without cell penetration, suggesting that dynamic and intimate intercellular communication occurs between fungus and plant throughout the disease cycle. We used deep RNA sequencing and metabolomics to investigate the physiology of plant and pathogen throughout an asexual reproductive cycle of Z. tritici on wheat leaves. Over 3,000 pathogen genes, more than 7,000 wheat genes, and more than 300 metabolites were differentially regulated. Intriguingly, individual fungal chromosomes contributed unequally to the overall gene expression changes. Early transcriptional down-regulation of putative host defense genes was detected in inoculated leaves. There was little evidence for fungal nutrient acquisition from the plant throughout symptomless colonization by Z. tritici, which may instead be utilizing lipid and fatty acid stores for growth. However, the fungus then subsequently manipulated specific plant carbohydrates, including fructan metabolites, during the switch to necrotrophic growth and reproduction. This switch coincided with increased expression of jasmonic acid biosynthesis genes and large-scale activation of other plant defense responses. Fungal genes encoding putative secondary metabolite clusters and secreted effector proteins were identified with distinct infection phase-specific expression patterns, although functional analysis suggested that many have overlapping/redundant functions in virulence. The pathogenic lifestyle of Z. tritici on wheat revealed through this study, involving initial defense suppression by a slow-growing extracellular and nutritionally limited pathogen followed by defense (hyper) activation during reproduction, reveals a subtle modification of the conceptual definition of hemibiotrophic plant infection.
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Affiliation(s)
- Jason J Rudd
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Kostya Kanyuka
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Keywan Hassani-Pak
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Mark Derbyshire
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Ambrose Andongabo
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Jean Devonshire
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Artem Lysenko
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Mansoor Saqi
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Nalini M Desai
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Stephen J Powers
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Juliet Hooper
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Linda Ambroso
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Arvind Bharti
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Andrew Farmer
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Kim E Hammond-Kosack
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Robert A Dietrich
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
| | - Mikael Courbot
- Department of Plant Biology and Crop Science (J.J.R., K.K., M.D., J.D., J.H., K.E.H.-K.) and Department of Computational and Systems Biology (K.H.-P., A.A., A.L., M.S., S.J.P.), Rothamsted Research, Harpenden, Hertshire AL5 2JQ, United Kingdom;Metabolon, Inc., Durham, North Carolina 27713 (N.M.D.);Syngenta Biotechnology, Inc., Research Triangle Park, North Carolina 27709 (L.A., A.B., R.A.D.);National Center for Genome Resources, Santa Fe, New Mexico 87505 (A.F.); andSyngenta Crop Protection AG, Crop Protection Research, CH-4332 Stein, Switzerland (M.C.)
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Cools HJ, Hammond-Kosack KE. Exploitation of genomics in fungicide research: current status and future perspectives. MOLECULAR PLANT PATHOLOGY 2013; 14:197-210. [PMID: 23157348 PMCID: PMC6638899 DOI: 10.1111/mpp.12001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Every year, fungicide use to control plant disease caused by pathogenic fungi increases. The global fungicide market is now worth more than £5.3 billion, second only to the herbicide market in importance. In the UK, over 5500 tonnes of fungicide were applied to crops in 2010 (The Food and Environment Research Agency, Pesticide Usage Statistics), with 95.5% of the wheat-growing area receiving three fungicide sprays. Although dependence on fungicides to produce food securely, reliably and cheaply may be moderated in the future by further developments in crop biotechnology, modern crop protection will continue to require a diversity of solutions, including effective and safe chemical control. Therefore, investment in exploiting the increasingly available genome sequences of the most devastating fungal and oomycete phytopathogenic species should bring an array of new opportunities for chemical intervention. To date, the impact of whole genome research on the development, introduction and stewardship of fungicides has been limited, but ongoing improvements in computational analysis, molecular biology, chemical genetics, genome sequencing and transcriptomics will facilitate the development and registration of the future suite of crop protection chemicals.
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Affiliation(s)
- Hans J Cools
- Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
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20
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Scalliet G, Bowler J, Luksch T, Kirchhofer-Allan L, Steinhauer D, Ward K, Niklaus M, Verras A, Csukai M, Daina A, Fonné-Pfister R. Mutagenesis and functional studies with succinate dehydrogenase inhibitors in the wheat pathogen Mycosphaerella graminicola. PLoS One 2012; 7:e35429. [PMID: 22536383 PMCID: PMC3334918 DOI: 10.1371/journal.pone.0035429] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 03/16/2012] [Indexed: 02/03/2023] Open
Abstract
A range of novel carboxamide fungicides, inhibitors of the succinate dehydrogenase enzyme (SDH, EC 1.3.5.1) is currently being introduced to the crop protection market. The aim of this study was to explore the impact of structurally distinct carboxamides on target site resistance development and to assess possible impact on fitness. We used a UV mutagenesis approach in Mycosphaerella graminicola, a key pathogen of wheat to compare the nature, frequencies and impact of target mutations towards five subclasses of carboxamides. From this screen we identified 27 amino acid substitutions occurring at 18 different positions on the 3 subunits constituting the ubiquinone binding (Qp) site of the enzyme. The nature of substitutions and cross resistance profiles indicated significant differences in the binding interaction to the enzyme across the different inhibitors. Pharmacophore elucidation followed by docking studies in a tridimensional SDH model allowed us to propose rational hypotheses explaining some of the differential behaviors for the first time. Interestingly all the characterized substitutions had a negative impact on enzyme efficiency, however very low levels of enzyme activity appeared to be sufficient for cell survival. In order to explore the impact of mutations on pathogen fitness in vivo and in planta, homologous recombinants were generated for a selection of mutation types. In vivo, in contrast to previous studies performed in yeast and other organisms, SDH mutations did not result in a major increase of reactive oxygen species levels and did not display any significant fitness penalty. However, a number of Qp site mutations affecting enzyme efficiency were shown to have a biological impact in planta. Using the combined approaches described here, we have significantly improved our understanding of possible resistance mechanisms to carboxamides and performed preliminary fitness penalty assessment in an economically important plant pathogen years ahead of possible resistance development in the field.
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Marshall R, Kombrink A, Motteram J, Loza-Reyes E, Lucas J, Hammond-Kosack KE, Thomma BP, Rudd JJ. Analysis of two in planta expressed LysM effector homologs from the fungus Mycosphaerella graminicola reveals novel functional properties and varying contributions to virulence on wheat. PLANT PHYSIOLOGY 2011; 156:756-69. [PMID: 21467214 PMCID: PMC3177273 DOI: 10.1104/pp.111.176347] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 04/05/2011] [Indexed: 05/18/2023]
Abstract
Secreted effector proteins enable plant pathogenic fungi to manipulate host defenses for successful infection. Mycosphaerella graminicola causes Septoria tritici blotch disease of wheat (Triticum aestivum) leaves. Leaf infection involves a long (approximately 7 d) period of symptomless intercellular colonization prior to the appearance of necrotic disease lesions. Therefore, M. graminicola is considered as a hemibiotrophic (or necrotrophic) pathogen. Here, we describe the molecular and functional characterization of M. graminicola homologs of Ecp6 (for extracellular protein 6), the Lysin (LysM) domain-containing effector from the biotrophic tomato (Solanum lycopersicum) leaf mold fungus Cladosporium fulvum, which interferes with chitin-triggered immunity in plants. Three LysM effector homologs are present in the M. graminicola genome, referred to as Mg3LysM, Mg1LysM, and MgxLysM. Mg3LysM and Mg1LysM genes were strongly transcriptionally up-regulated specifically during symptomless leaf infection. Both proteins bind chitin; however, only Mg3LysM blocked the elicitation of chitin-induced plant defenses. In contrast to C. fulvum Ecp6, both Mg1LysM and Mg3LysM also protected fungal hyphae against plant-derived hydrolytic enzymes, and both genes show significantly more nucleotide polymorphism giving rise to nonsynonymous amino acid changes. While Mg1LysM deletion mutant strains of M. graminicola were fully pathogenic toward wheat leaves, Mg3LysM mutant strains were severely impaired in leaf colonization, did not trigger lesion formation, and were unable to undergo asexual sporulation. This virulence defect correlated with more rapid and pronounced expression of wheat defense genes during the symptomless phase of leaf colonization. These data highlight different functions for MgLysM effector homologs during plant infection, including novel activities that distinguish these proteins from C. fulvum Ecp6.
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Churchill ACL. Mycosphaerella fijiensis, the black leaf streak pathogen of banana: progress towards understanding pathogen biology and detection, disease development, and the challenges of control. MOLECULAR PLANT PATHOLOGY 2011; 12:307-28. [PMID: 21453427 PMCID: PMC6640443 DOI: 10.1111/j.1364-3703.2010.00672.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
BACKGROUND Banana (Musa spp.) is grown throughout the tropical and subtropical regions of the world. The fruits are a key staple food in many developing countries and a source of income for subsistence farmers. Bananas are also a major, multibillion-dollar export commodity for consumption primarily in developed countries, where few banana cultivars are grown. The fungal pathogen Mycosphaerella fijiensis causes black leaf streak disease (BLSD; aka black Sigatoka leaf spot) on the majority of edible banana cultivars grown worldwide. The fact that most of these cultivars are sterile and unsuitable for the breeding of resistant lines necessitates the extensive use of fungicides as the primary means of disease control. BLSD is a significant threat to the food security of resource-poor populations who cannot afford fungicides, and increases the environmental and health hazards where large-acreage monocultures of banana (Cavendish subgroup, AAA genome) are grown for export. TAXONOMY Mycosphaerella fijiensis M. Morelet is a sexual, heterothallic fungus having Pseudocercospora fijiensis (M. Morelet) Deighton as the anamorph stage. It is a haploid, hemibiotrophic ascomycete within the class Dothideomycetes, order Capnodiales and family Mycosphaerellaceae. Its taxonomic placement is based on DNA phylogeny, morphological analyses and cultural characteristics. DISEASE SYMPTOMS AND HOST RANGE Mycosphaerella fijiensis is a leaf pathogen that causes reddish-brown streaks running parallel to the leaf veins, which aggregate to form larger, dark-brown to black compound streaks. These streaks eventually form fusiform or elliptical lesions that coalesce, form a water-soaked border with a yellow halo and, eventually, merge to cause extensive leaf necrosis. The disease does not kill the plants immediately, but weakens them by decreasing the photosynthetic capacity of leaves, causing a reduction in the quantity and quality of fruit, and inducing the premature ripening of fruit harvested from infected plants. Although Musa spp. are the primary hosts of M. fijiensis, the ornamental plant Heliconia psittacorum has been reported as an alternative host. NEW OPPORTUNITIES Several valuable tools and resources have been developed to overcome some of the challenges of studying this host-pathogen system. These include a DNA-mediated fungal transformation system and the ability to conduct targeted gene disruptions, reliable quantitative plant bioassays, diagnostic probes to detect and differentiate M. fijiensis from related pathogens and to distinguish strains of different mating types, and a genome sequence that has revealed a wealth of gene sequences and molecular markers to be utilized in functional and population biology studies. USEFUL WEBSITES http://bananas.bioversityinternational.org/, http://genome.jgi-psf.org/Mycfi2/Mycfi2.home.html, http://www.isppweb.org/names_banana_pathogen.asp#fun, http://www.promusa.org/.
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Affiliation(s)
- Alice C L Churchill
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
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