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Sanz-Martín JM, Pacheco-Arjona JR, Bello-Rico V, Vargas WA, Monod M, Díaz-Mínguez JM, Thon MR, Sukno SA. A highly conserved metalloprotease effector enhances virulence in the maize anthracnose fungus Colletotrichum graminicola. Mol Plant Pathol 2016; 17:1048-62. [PMID: 26619206 PMCID: PMC6638349 DOI: 10.1111/mpp.12347] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 05/22/2023]
Abstract
Colletotrichum graminicola causes maize anthracnose, an agronomically important disease with a worldwide distribution. We have identified a fungalysin metalloprotease (Cgfl) with a role in virulence. Transcriptional profiling experiments and live cell imaging show that Cgfl is specifically expressed during the biotrophic stage of infection. To determine whether Cgfl has a role in virulence, we obtained null mutants lacking Cgfl and performed pathogenicity and live microscopy assays. The appressorium morphology of the null mutants is normal, but they exhibit delayed development during the infection process on maize leaves and roots, showing that Cgfl has a role in virulence. In vitro chitinase activity assays of leaves infected with wild-type and null mutant strains show that, in the absence of Cgfl, maize leaves exhibit increased chitinase activity. Phylogenetic analyses show that Cgfl is highly conserved in fungi. Similarity searches, phylogenetic analysis and transcriptional profiling show that C. graminicola encodes two LysM domain-containing homologues of Ecp6, suggesting that this fungus employs both Cgfl-mediated and LysM protein-mediated strategies to control chitin signalling.
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Affiliation(s)
- José M Sanz-Martín
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - José Ramón Pacheco-Arjona
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - Víctor Bello-Rico
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - Walter A Vargas
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - Michel Monod
- Laboratoire de Mycologie, Service de Dermatologie, Centre Hospitalier Universitaire Vaudois, 1011, Lausanne, Switzerland
| | - José M Díaz-Mínguez
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - Michael R Thon
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
| | - Serenella A Sukno
- Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Department of Microbiology and Genetics, University of Salamanca, 37185, Villamayor, Spain
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Vargas WA, Sanz-Martín JM, Rech GE, Armijos-Jaramillo VD, Rivera LP, Echeverria MM, Díaz-Mínguez JM, Thon MR, Sukno SA. A Fungal Effector With Host Nuclear Localization and DNA-Binding Properties Is Required for Maize Anthracnose Development. Mol Plant Microbe Interact 2016; 29:83-95. [PMID: 26554735 DOI: 10.1094/mpmi-09-15-0209-r] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Plant pathogens have the capacity to manipulate the host immune system through the secretion of effectors. We identified 27 putative effector proteins encoded in the genome of the maize anthracnose pathogen Colletotrichum graminicola that are likely to target the host's nucleus, as they simultaneously contain sequence signatures for secretion and nuclear localization. We functionally characterized one protein, identified as CgEP1. This protein is synthesized during the early stages of disease development and is necessary for anthracnose development in maize leaves, stems, and roots. Genetic, molecular, and biochemical studies confirmed that this effector targets the host's nucleus and defines a novel class of double-stranded DNA-binding protein. We show that CgEP1 arose from a gene duplication in an ancestor of a lineage of monocot-infecting Colletotrichum spp. and has undergone an intense evolution process, with evidence for episodes of positive selection. We detected CgEP1 homologs in several species of a grass-infecting lineage of Colletotrichum spp., suggesting that its function may be conserved across a large number of anthracnose pathogens. Our results demonstrate that effectors targeted to the host nucleus may be key elements for disease development and aid in the understanding of the genetic basis of anthracnose development in maize plants.
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Affiliation(s)
- Walter A Vargas
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - José M Sanz-Martín
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - Gabriel E Rech
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - Vinicio D Armijos-Jaramillo
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - Lina P Rivera
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - María Mercedes Echeverria
- 2 Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata - C.C. 276 (7620) Balcarce, Buenos Aires, Argentina
| | - José M Díaz-Mínguez
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - Michael R Thon
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
| | - Serenella A Sukno
- 1 Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, 37185 Villamayor, Spain
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Rech GE, Sanz-Martín JM, Anisimova M, Sukno SA, Thon MR. Natural selection on coding and noncoding DNA sequences is associated with virulence genes in a plant pathogenic fungus. Genome Biol Evol 2014; 6:2368-79. [PMID: 25193312 PMCID: PMC4202328 DOI: 10.1093/gbe/evu192] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/26/2014] [Indexed: 12/20/2022] Open
Abstract
Natural selection leaves imprints on DNA, offering the opportunity to identify functionally important regions of the genome. Identifying the genomic regions affected by natural selection within pathogens can aid in the pursuit of effective strategies to control diseases. In this study, we analyzed genome-wide patterns of selection acting on different classes of sequences in a worldwide sample of eight strains of the model plant-pathogenic fungus Colletotrichum graminicola. We found evidence of selective sweeps, balancing selection, and positive selection affecting both protein-coding and noncoding DNA of pathogenicity-related sequences. Genes encoding putative effector proteins and secondary metabolite biosynthetic enzymes show evidence of positive selection acting on the coding sequence, consistent with an Arms Race model of evolution. The 5' untranslated regions (UTRs) of genes coding for effector proteins and genes upregulated during infection show an excess of high-frequency polymorphisms likely the consequence of balancing selection and consistent with the Red Queen hypothesis of evolution acting on these putative regulatory sequences. Based on the findings of this work, we propose that even though adaptive substitutions on coding sequences are important for proteins that interact directly with the host, polymorphisms in the regulatory sequences may confer flexibility of gene expression in the virulence processes of this important plant pathogen.
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Affiliation(s)
- Gabriel E Rech
- Departamento de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Villamayor, Spain
| | - José M Sanz-Martín
- Departamento de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Villamayor, Spain
| | - Maria Anisimova
- Computer Science Department, ETH Zürich, Universitätsstrasse 6, Zürich, Switzerland Institute of Applied Simulation, Zürich University of Applied Sciences (ZHAW), Wädenswil, Switzerland
| | - Serenella A Sukno
- Departamento de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Villamayor, Spain
| | - Michael R Thon
- Departamento de Microbiología y Genética, Instituto Hispano-Luso de Investigaciones Agrarias (CIALE), Universidad de Salamanca, Villamayor, Spain
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Sukno SA, Sanz-Martín JM, González-Fuente M, Hiltbrunner J, Thon MR. First Report of Anthracnose Stalk Rot of Maize Caused by Colletotrichum graminicola in Switzerland. Plant Dis 2014; 98:694. [PMID: 30708515 DOI: 10.1094/pdis-09-13-0912-pdn] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Maize stem samples exhibiting symptoms of anthracnose were collected from a field near Zurich, Switzerland, in September of 2012 and were sent to the fungal genetics laboratory, Centro Hispano-Luso de Investigaciones Agrarias (CIALE) at the University of Salamanca, Spain, for further analysis. The stem samples exhibited glossy, black, and irregularly shaped lesions. Tissue samples, approximately 5 mm2, were dissected from below the epidermis. The tissue samples were surface disinfested for 1 min in 20% sodium hypochlorite and cultured on one half strength acidified PDA supplemented with ampicillin (2). Monoconidial isolates from three different stems were grown on potato dextrose agar (PDA) and had dark gray aerial mycelium with orange spore masses. Conidia were falcate, slightly curved, tapered toward the tips with an average length of 31.77 μm and an average width of 4.76 μm and produced in acervuli with setae, consistent with descriptions of C. graminicola Ces. Wils. Conidial suspensions were prepared for each isolate, and were inoculated onto the leaves of 2-week-old maize plants by laying the plants horizontally in a tray (in pots with their root systems intact) and placing 7.5-μl droplets of a 106 conidial suspension on the leaf surface. The trays were covered and plants were incubated overnight at 23°C. The plants were then returned to their upright position and grown in a growth chamber at 25°C with a 12-h light cycle (3). After 6 days, the inoculated plant leaves exhibited lesions that were elongated and irregularly shaped with necrotic centers and chlorotic margins. The water-inoculated controls did not show symptoms. Microscopic examination revealed the production of conidia on the surface of the leaves, identical to the original isolates. Genomic DNA was extracted using the protocol of Baek and Kenerley (1). A region of the ribosomal DNA repeat was amplified and sequenced using the universal primers ITS4 and ITS5. The resulting sequences were 100% identical to each other and 100% identical to C. graminicola sequences in GenBank. One representative sequence was deposited in GenBank under accession no. KF597538. The 100 most similar sequences in GenBank were used to construct a phylogenetic tree using the neighbor-joining method. The phylogenetic analysis revealed that the isolates clustered within the C. graminicola clade, consistent with their identification as C. graminicola. To our knowledge, this is the first report of anthracnose on maize caused by C. graminicola in Switzerland. Previous reports have demonstrated that the pathogen exists in neighboring countries Germany and France. References: (1) J.-M. Baek and C. M. Kenerley. Fungal Genet. Biol. 23:34, 1998. (2) S. A. Sukno et al. Appl. Environ. Microbiol. 74:823, 2008. (3) W. A. Vargas et al. Plant Physiol. 158:1342, 2012.
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Affiliation(s)
- S A Sukno
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Río Duero 12, Villamayor, 37185 Salamanca, Spain
| | - J M Sanz-Martín
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Río Duero 12, Villamayor, 37185 Salamanca, Spain
| | - M González-Fuente
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Río Duero 12, Villamayor, 37185 Salamanca, Spain
| | - J Hiltbrunner
- Federal Department of Economic Affairs, Agroscope Reckenholz-Tänikon Research Station (ART) Reckenholzstrasse 191, 8046 Zurich, Switzerland
| | - M R Thon
- Centro Hispano-Luso de Investigaciones Agrarias (CIALE), Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Río Duero 12, Villamayor, 37185 Salamanca, Spain
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