451
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Manning VA, Pandelova I, Dhillon B, Wilhelm LJ, Goodwin SB, Berlin AM, Figueroa M, Freitag M, Hane JK, Henrissat B, Holman WH, Kodira CD, Martin J, Oliver RP, Robbertse B, Schackwitz W, Schwartz DC, Spatafora JW, Turgeon BG, Yandava C, Young S, Zhou S, Zeng Q, Grigoriev IV, Ma LJ, Ciuffetti LM. Comparative genomics of a plant-pathogenic fungus, Pyrenophora tritici-repentis, reveals transduplication and the impact of repeat elements on pathogenicity and population divergence. G3 (BETHESDA, MD.) 2013; 3:41-63. [PMID: 23316438 PMCID: PMC3538342 DOI: 10.1534/g3.112.004044] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 11/02/2012] [Indexed: 12/31/2022]
Abstract
Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes.
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Affiliation(s)
- Viola A. Manning
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Iovanna Pandelova
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Braham Dhillon
- Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4
| | - Larry J. Wilhelm
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- Carbone/Ferguson Laboratories, Division of Neuroscience, Oregon National Primate Research Center (ONPRC), Beaverton, Oregon 97006
| | - Stephen B. Goodwin
- USDA–Agricultural Research Service, Purdue University, West Lafayette, Indiana 47907
| | | | - Melania Figueroa
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- USDA-Agricultural Research Service, Forage Seed and Cereal Research Unit, Oregon State University, Corvallis, Oregon 97331
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331
| | - James K. Hane
- Commonwealth Scientific and Industrial Research Organization−Plant Industry, Centre for Environment and Life Sciences, Floreat, Western Australia 6014, Australia
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Centre National de la Recherche Scientifique, 13288 Marseille cedex 9, France
| | - Wade H. Holman
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Chinnappa D. Kodira
- The Broad Institute, Cambridge, Massachusetts 02142
- Roche 454, Branford, Connecticut 06405
| | - Joel Martin
- US DOE Joint Genome Institute, Walnut Creek, California 94598
| | - Richard P. Oliver
- Australian Centre for Necrotrophic Fungal Pathogens, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia 6845, Australia
| | - Barbara Robbertse
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Centre National de la Recherche Scientifique, 13288 Marseille cedex 9, France
| | | | - David C. Schwartz
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, UW Biotechnology Center, University of Wisconsin–Madison, Madison, Wisconsin 53706
| | - Joseph W. Spatafora
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - B. Gillian Turgeon
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York 14850
| | | | - Sarah Young
- The Broad Institute, Cambridge, Massachusetts 02142
| | - Shiguo Zhou
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, UW Biotechnology Center, University of Wisconsin–Madison, Madison, Wisconsin 53706
| | | | | | - Li-Jun Ma
- The Broad Institute, Cambridge, Massachusetts 02142
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Lynda M. Ciuffetti
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331
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452
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Martin MD, Cappellini E, Samaniego JA, Zepeda ML, Campos PF, Seguin-Orlando A, Wales N, Orlando L, Ho SYW, Dietrich FS, Mieczkowski PA, Heitman J, Willerslev E, Krogh A, Ristaino JB, Gilbert MTP. Reconstructing genome evolution in historic samples of the Irish potato famine pathogen. Nat Commun 2013; 4:2172. [PMID: 23863894 PMCID: PMC3759036 DOI: 10.1038/ncomms3172] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/20/2013] [Indexed: 11/15/2022] Open
Abstract
Responsible for the Irish potato famine of 1845-49, the oomycete pathogen Phytophthora infestans caused persistent, devastating outbreaks of potato late blight across Europe in the 19th century. Despite continued interest in the history and spread of the pathogen, the genome of the famine-era strain remains entirely unknown. Here we characterize temporal genomic changes in introduced P. infestans. We shotgun sequence five 19th-century European strains from archival herbarium samples--including the oldest known European specimen, collected in 1845 from the first reported source of introduction. We then compare their genomes to those of extant isolates. We report multiple distinct genotypes in historical Europe and a suite of infection-related genes different from modern strains. At virulence-related loci, several now-ubiquitous genotypes were absent from the historical gene pool. At least one of these genotypes encodes a virulent phenotype in modern strains, which helps explain the 20th century's episodic replacements of European P. infestans lineages.
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Affiliation(s)
- Michael D Martin
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark.
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453
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Vetukuri RR, Åsman AKM, Tellgren-Roth C, Jahan SN, Reimegård J, Fogelqvist J, Savenkov E, Söderbom F, Avrova AO, Whisson SC, Dixelius C. Evidence for small RNAs homologous to effector-encoding genes and transposable elements in the oomycete Phytophthora infestans. PLoS One 2012; 7:e51399. [PMID: 23272103 PMCID: PMC3522703 DOI: 10.1371/journal.pone.0051399] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/31/2012] [Indexed: 12/03/2022] Open
Abstract
Phytophthora infestans is the oomycete pathogen responsible for the devastating late blight disease on potato and tomato. There is presently an intense research focus on the role(s) of effectors in promoting late blight disease development. However, little is known about how they are regulated, or how diversity in their expression may be generated among different isolates. Here we present data from investigation of RNA silencing processes, characterized by non-coding small RNA molecules (sRNA) of 19-40 nt. From deep sequencing of sRNAs we have identified sRNAs matching numerous RxLR and Crinkler (CRN) effector protein genes in two isolates differing in pathogenicity. Effector gene-derived sRNAs were present in both isolates, but exhibited marked differences in abundance, especially for CRN effectors. Small RNAs in P. infestans grouped into three clear size classes of 21, 25/26 and 32 nt. Small RNAs from all size classes mapped to RxLR effector genes, but notably 21 nt sRNAs were the predominant size class mapping to CRN effector genes. Some effector genes, such as PiAvr3a, to which sRNAs were found, also exhibited differences in transcript accumulation between the two isolates. The P. infestans genome is rich in transposable elements, and the majority of sRNAs of all size classes mapped to these sequences, predominantly to long terminal repeat (LTR) retrotransposons. RNA silencing of Dicer and Argonaute genes provided evidence that generation of 21 nt sRNAs is Dicer-dependent, while accumulation of longer sRNAs was impacted by silencing of Argonaute genes. Additionally, we identified six microRNA (miRNA) candidates from our sequencing data, their precursor sequences from the genome sequence, and target mRNAs. These miRNA candidates have features characteristic of both plant and metazoan miRNAs.
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Affiliation(s)
- Ramesh R Vetukuri
- Department of Plant Biology and Forest Genetics, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, Uppsala, Sweden.
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454
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Oliver R. Genomic tillage and the harvest of fungal phytopathogens. THE NEW PHYTOLOGIST 2012; 196:1015-1023. [PMID: 22998436 DOI: 10.1111/j.1469-8137.2012.04330.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/06/2012] [Indexed: 06/01/2023]
Abstract
Genome sequencing has been carried out on a small selection of major fungal ascomycete pathogens. These studies show that simple models whereby pathogens evolved from phylogenetically related saprobes by the acquisition or modification of a small number of key genes cannot be sustained.The genomes show that pathogens cannot be divided into three clearly delineated classes (biotrophs, hemibiotrophs and necrotrophs) but rather into a complex matrix of categories each with subtly different properties. It is clear that the evolution of pathogenicity is ancient, rapid and ongoing. Fungal pathogens have undergone substantial genomic rearrangements that can be appropriately described as 'genomic tillage'. Genomic tillage underpins the evolution and expression of large families of genes - known as effectors - that manipulate and exploit metabolic and defence processes of plants so as to allow the proliferation of pathogens.
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Affiliation(s)
- Richard Oliver
- Australian Centre for Necrotrophic Fungal Pathogens, Department of Environment and Agriculture, Curtin University, Bentley, WA, 6845, Australia
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455
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Milani NA, Lawrence DP, Arnold AE, VanEtten HD. Origin of pisatin demethylase (PDA) in the genus Fusarium. Fungal Genet Biol 2012; 49:933-42. [PMID: 22985693 DOI: 10.1016/j.fgb.2012.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 11/25/2022]
Abstract
Host specificity of plant pathogens can be dictated by genes that enable pathogens to circumvent host defenses. Upon recognition of a pathogen, plants initiate defense responses that can include the production of antimicrobial compounds such as phytoalexins. The pea pathogen Nectria haematococca mating population VI (MPVI) is a filamentous ascomycete that contains a cluster of genes known as the pea pathogenicity (PEP) cluster in which the pisatin demethylase (PDA) gene resides. The PDA gene product is responsible for the detoxification of the phytoalexin pisatin, which is produced by the pea plant (Pisum sativum L.). This detoxification activity allows the pathogen to evade the phytoalexin defense mechanism. It has been proposed that the evolution of PDA and the PEP cluster reflects horizontal gene transfer (HGT). Previous observations consistent with this hypothesis include the location of the PEP cluster and PDA gene on a dispensable portion of the genome (a supernumerary chromosome), a phylogenetically discontinuous distribution of the cluster among closely related species, and a bias in G+C content and codon usage compared to other regions of the genome. In this study we compared the phylogenetic history of PDA, beta-tubulin, and translation elongation factor 1-alpha in three closely related fungi (Nectria haematococca, Fusarium oxysporum, and Neocosmospora species) to formally evaluate hypotheses regarding the origin and evolution of PDA. Our results, coupled with previous work, robustly demonstrate discordance between the gene genealogy of PDA and the organismal phylogeny of these species, and illustrate how HGT of pathogenicity genes can contribute to the expansion of host specificity in plant-pathogenic fungi.
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Affiliation(s)
- Nicholas A Milani
- School of Plant Sciences, College of Agriculture, University of Arizona, Tucson, AZ 85721, USA
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456
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Peyretaillade E, Parisot N, Polonais V, Terrat S, Denonfoux J, Dugat-Bony E, Wawrzyniak I, Biderre-Petit C, Mahul A, Rimour S, Gonçalves O, Bornes S, Delbac F, Chebance B, Duprat S, Samson G, Katinka M, Weissenbach J, Wincker P, Peyret P. Annotation of microsporidian genomes using transcriptional signals. Nat Commun 2012; 3:1137. [DOI: 10.1038/ncomms2156] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 09/20/2012] [Indexed: 12/24/2022] Open
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