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Akiba M, Ota Y, Tsai IJ, Hattori T, Sahashi N, Kikuchi T. Genetic Differentiation and Spatial Structure of Phellinus noxius, the Causal Agent of Brown Root Rot of Woody Plants in Japan. PLoS One 2015; 10:e0141792. [PMID: 26513585 PMCID: PMC4626371 DOI: 10.1371/journal.pone.0141792] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/13/2015] [Indexed: 01/12/2023] Open
Abstract
Phellinus noxius is a pathogenic fungus that causes brown root rot disease in a variety of tree species. This fungus is distributed in tropical and sub-tropical regions of Southeast and East Asia, Oceania, Australia, Central America and Africa. In Japan, it was first discovered on Ishigaki Island in Okinawa Prefecture in 1988; since then, it has been found on several of the Ryukyu Islands. Recently, this fungus was identified from the Ogasawara (Bonin) Islands, where it has killed trees, including rare endemic tree species. For effective control or quarantine methods, it is important to clarify whether the Japanese populations of P. noxius are indigenous to the area or if they have been introduced from other areas. We developed 20 microsatellite markers from genome assembly of P. noxius and genotyped 128 isolates from 12 of the Ryukyu Islands and 3 of the Ogasawara Islands. All isolates had unique genotypes, indicating that basidiospore infection is a primary dissemination method for the formation of new disease foci. Genetic structure analyses strongly supported genetic differentiation between the Ryukyu populations and the Ogasawara populations of P. noxius. High polymorphism of microsatellite loci suggests that Japanese populations are indigenous or were introduced a very long time ago. We discuss differences in invasion patterns between the Ryukyu Islands and the Ogasawara Islands.
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Affiliation(s)
- Mitsuteru Akiba
- Department of Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Yuko Ota
- Department of Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Isheng J. Tsai
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Tsutomu Hattori
- Department of Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Norio Sahashi
- Department of Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Taisei Kikuchi
- Division of Parasitology, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan
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Mercière M, Laybats A, Carasco-Lacombe C, Tan JS, Klopp C, Durand-Gasselin T, Alwee SSRS, Camus-Kulandaivelu L, Breton F. Identification and development of new polymorphic microsatellite markers using genome assembly for Ganoderma boninense, causal agent of oil palm basal stem rot disease. Mycol Prog 2015. [DOI: 10.1007/s11557-015-1123-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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53
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Multilocus PCR Assays Elucidate Vegetative Incompatibility Gene Profiles of Cryphonectria parasitica in the United States. Appl Environ Microbiol 2015; 81:5736-42. [PMID: 26070681 DOI: 10.1128/aem.00926-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/08/2015] [Indexed: 11/20/2022] Open
Abstract
Chestnut blight is a devastating disease of Castanea spp. Mycoviruses that reduce virulence (hypovirulence) of the causative agent, Cryphonectria parasitica, can be used to manage chestnut blight. However, vegetative incompatibility (vic) barriers that restrict anastomosis-mediated virus transmission hamper hypovirulence efficacy. In order to effectively determine the vegetative incompatibility genetic structure of C. parasitica field populations, we have designed PCR primer sets that selectively amplify and distinguish alleles for each of the six known diallelic C. parasitica vic genetic loci. PCR assay results were validated using a panel of 64 European tester strains with genetically determined vic genotypes. Analysis of 116 C. parasitica isolates collected from five locations in the eastern United States revealed 39 unique vic genotypes and generally good agreement between PCR and tester strain coculturing assays in terms of vic diversity and genotyping. However, incongruences were observed for isolates from multiple locations and suggested that the coculturing assay can overestimate diversity at the six known vic loci. The availability of molecular tools for rapid and precise vic genotyping significantly improves the ability to predict and evaluate the efficacy of hypovirulence and related management strategies.
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Leduc A, Traoré YN, Boyer K, Magne M, Grygiel P, Juhasz CC, Boyer C, Guerin F, Wonni I, Ouedraogo L, Vernière C, Ravigné V, Pruvost O. Bridgehead invasion of a monomorphic plant pathogenic bacterium:Xanthomonas citripv. citri, an emerging citrus pathogen in Mali and Burkina Faso. Environ Microbiol 2015; 17:4429-42. [DOI: 10.1111/1462-2920.12876] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 03/06/2015] [Indexed: 11/29/2022]
Affiliation(s)
- A. Leduc
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | | | - K. Boyer
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - M. Magne
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - P. Grygiel
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - C. C. Juhasz
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - C. Boyer
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - F. Guerin
- UMR PVBMT; Université de la Réunion; 97410 Saint Pierre La Réunion France
| | - I. Wonni
- Institut de l'Environnement et de Recherches agricoles; 01 BP910 Bobo Dioulasso Burkina Faso
| | - L. Ouedraogo
- Institut de l'Environnement et de Recherches agricoles; 01 BP910 Bobo Dioulasso Burkina Faso
| | - C. Vernière
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
| | - V. Ravigné
- UMR BGPI; CIRAD; 34398 Montpellier France
| | - O. Pruvost
- UMR PVBMT; CIRAD; 97410 Saint Pierre La Réunion France
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55
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Burokiene D, Prospero S, Jung E, Marciulyniene D, Moosbrugger K, Norkute G, Rigling D, Lygis V, Schoebel CN. Genetic population structure of the invasive ash dieback pathogen Hymenoscyphus fraxineus in its expanding range. Biol Invasions 2015. [DOI: 10.1007/s10530-015-0911-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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56
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Abstract
Trade in plant and plant products has profoundly affected the global distribution and diversity of plant pathogens. Identification of migration pathways can be used to monitor or manage pathogen movement for proactive disease management or quarantine measures. Genomics-based genetic marker discovery is allowing unprecedented collection of population genetic data for plant pathogens. These data can be used for detailed analysis of the ancestry of population samples and therefore for analysis of migration. Reconstruction of migration histories has confirmed previous hypotheses based on observational data and led to unexpected new findings on the origins of pathogens and source populations for past and recent migration. The choice of software for analysis depends on the type of migration being studied and the reproductive mode of the pathogen. Biased sampling and complex population structures are potential challenges to accurate inference of migration pathways.
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Affiliation(s)
- Erica M Goss
- Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, Florida 32611;
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57
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Pautasso M, Schlegel M, Holdenrieder O. Forest health in a changing world. MICROBIAL ECOLOGY 2015; 69:826-842. [PMID: 25502075 DOI: 10.1007/s00248-014-0545-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 11/27/2014] [Indexed: 06/04/2023]
Abstract
Forest pathology, the science of forest health and tree diseases, is operating in a rapidly developing environment. Most importantly, global trade and climate change are increasing the threat to forest ecosystems posed by new diseases. Various studies relevant to forest pathology in a changing world are accumulating, thus making it necessary to provide an update of recent literature. In this contribution, we summarize research at the interface between forest pathology and landscape ecology, biogeography, global change science and research on tree endophytes. Regional outbreaks of tree diseases are requiring interdisciplinary collaboration, e.g. between forest pathologists and landscape ecologists. When tree pathogens are widely distributed, the factors determining their broad-scale distribution can be studied using a biogeographic approach. Global change, the combination of climate and land use change, increased pollution, trade and urbanization, as well as invasive species, will influence the effects of forest disturbances such as wildfires, droughts, storms, diseases and insect outbreaks, thus affecting the health and resilience of forest ecosystems worldwide. Tree endophytes can contribute to biological control of infectious diseases, enhance tolerance to environmental stress or behave as opportunistic weak pathogens potentially competing with more harmful ones. New molecular techniques are available for studying the complete tree endobiome under the influence of global change stressors from the landscape to the intercontinental level. Given that exotic tree diseases have both ecologic and economic consequences, we call for increased interdisciplinary collaboration in the coming decades between forest pathologists and researchers studying endophytes with tree geneticists, evolutionary and landscape ecologists, biogeographers, conservation biologists and global change scientists and outline interdisciplinary research gaps.
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Affiliation(s)
- Marco Pautasso
- Forest Pathology & Dendrology, Institute of Integrative Biology (IBZ), ETH Zurich, 8092, Zurich, Switzerland,
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58
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Short DPG, Gurung S, Gladieux P, Inderbitzin P, Atallah ZK, Nigro F, Li G, Benlioglu S, Subbarao KV. Globally invading populations of the fungal plant pathogen Verticillium dahliae are dominated by multiple divergent lineages. Environ Microbiol 2015; 17:2824-40. [PMID: 25630463 DOI: 10.1111/1462-2920.12789] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/17/2014] [Indexed: 11/28/2022]
Abstract
The spread of aggressive fungal pathogens into previously non-endemic regions is a major threat to plant health and food security. Analyses of the spatial and genetic structure of plant pathogens offer valuable insights into their origin, dispersal mechanisms and evolution, and have been useful to develop successful disease management strategies. Here, we elucidated the genetic diversity, population structure and demographic history of worldwide invasion of the ascomycete Verticillium dahliae, a soil-borne pathogen, using a global collection of 1100 isolates from multiple plant hosts and countries. Seven well-differentiated genetic clusters were revealed through discriminant analysis of principal components (DAPC), but no strong associations between these clusters and host/geographic origin of isolates were found. Analyses of clonal evolutionary relationships among multilocus genotypes with the eBURST algorithm and analyses of genetic distances revealed that genetic clusters represented several ancient evolutionary lineages with broad geographic distribution and wide host range. Comparison of different scenarios of demographic history using approximate Bayesian computations revealed the branching order among the different genetic clusters and lineages. The different lineages may represent incipient species, and this raises questions with respect to their evolutionary origin and the factors allowing their maintenance in the same areas and same hosts without evidence of admixture between them. Based on the above findings and the biology of V. dahliae, we conclude that anthropogenic movement has played an important role in spreading V. dahliae lineages. Our findings have implications for the development of management strategies such as quarantine measures and crop resistance breeding.
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Affiliation(s)
- Dylan P G Short
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Suraj Gurung
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Pierre Gladieux
- Ecologie Systematique Evolution, CNRS, Université Paris Sud, Orsay, F-91405, France
| | - Patrik Inderbitzin
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
| | - Zahi K Atallah
- Department of Advanced Technology, Hartnell College, Salinas, CA, 93905, USA
| | - Franco Nigro
- Department of Soil, Plant, and Food Sciences, University of Bari 'Aldo Moro', Bari, 70126, Italy
| | - Guoqing Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, 430070, China
| | | | - Krishna V Subbarao
- Department of Plant Pathology, University of California, Davis, CA, 95616, USA
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59
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Gladieux P, Feurtey A, Hood ME, Snirc A, Clavel J, Dutech C, Roy M, Giraud T. The population biology of fungal invasions. Mol Ecol 2015; 24:1969-86. [DOI: 10.1111/mec.13028] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 11/24/2014] [Accepted: 11/28/2014] [Indexed: 12/16/2022]
Affiliation(s)
- P. Gladieux
- Ecologie; Systématique et Evolution; Université Paris-Sud; Bâtiment 360 F-91405 Orsay France
- CNRS; 91405 Orsay France
| | - A. Feurtey
- Ecologie; Systématique et Evolution; Université Paris-Sud; Bâtiment 360 F-91405 Orsay France
- CNRS; 91405 Orsay France
| | - M. E. Hood
- Department of Biology; Amherst College; Amherst Massachusetts 01002 USA
| | - A. Snirc
- Ecologie; Systématique et Evolution; Université Paris-Sud; Bâtiment 360 F-91405 Orsay France
- CNRS; 91405 Orsay France
| | - J. Clavel
- Conservation des Espèces; Restauration et Suivi des Populations - CRBPO; Muséum National d'Histoire Naturelle-CNRS-Université Pierre et Marie Curie; 55 rue Buffon 75005 Paris France
| | - C. Dutech
- Biodiversité Gènes et Communautés; INRA-Université Bordeaux 1; Site de Pierroton 33610 Cestas France
| | - M. Roy
- Evolution et Diversité Biologique; Université Toulouse Paul Sabatier-Ecole Nationale de Formation Agronomique-CNRS; 118 route de Narbonne 31062 Toulouse France
| | - T. Giraud
- Ecologie; Systématique et Evolution; Université Paris-Sud; Bâtiment 360 F-91405 Orsay France
- CNRS; 91405 Orsay France
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60
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Bryner SF, Prospero S, Rigling D. Dynamics of Cryphonectria hypovirus infection in chestnut blight cankers. PHYTOPATHOLOGY 2014; 104:918-925. [PMID: 24601984 DOI: 10.1094/phyto-03-13-0069-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Virulent strains of the chestnut blight fungus Cryphonectria parasitica cause lethal bark cankers on chestnut trees. Infection of C. parasitica with Cryphonectria hypovirus 1 in Europe biologically controls this disease, leading to nonlethal and inactive cankers. Unexpectedly, virus-free C. parasitica strains have been isolated from inactive cankers. In this study, we compared the virulence of virus-infected and virus-free C. parasitica strains isolated from either inactive or active cankers on chestnut seedlings and sprouts. In the seedling experiment, we assessed canker growth and seedling mortality. In the sprout experiment, we also assessed canker growth and made fungal reisolations to determine virus infection and immigration of foreign vegetative compatibility (vc) types over a period of 13 years in a coppice forest. Overall, the virulence of virus-free C. parasitica strains isolated from inactive versus active cankers did not differ. Significant differences were only attributed to virus infection. Virus infection and fungal strain composition in cankers changed over time. Foreign vc types immigrated into cankers and virus-free cankers became virus-infected within a few years. Most of the cankers were callused over time and became inactive. However, we observed that the virus did not always persist in these cankers. This study demonstrates that virus spread occurs effectively in European chestnut forests and that this biocontrol system is highly dynamic.
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61
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Walker AS, Gladieux P, Decognet V, Fermaud M, Confais J, Roudet J, Bardin M, Bout A, C. Nicot P, Poncet C, Fournier E. Population structure and temporal maintenance of the multihost fungal pathogenBotrytis cinerea: causes and implications for disease management. Environ Microbiol 2014; 17:1261-74. [DOI: 10.1111/1462-2920.12563] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 07/04/2014] [Indexed: 01/02/2023]
Affiliation(s)
- Anne-Sophie Walker
- INRA, UR 1290 BIOGER-CPP; Avenue Lucien Brétignières Thiverval-Grignon F-78850 France
| | - Pierre Gladieux
- CNRS, UMR 8079 Ecologie Systématique Evolution; Bâtiment 360 Orsay F-91405 France
- University of Paris-Sud; Orsay F-91405 France
- Department of Plant and Microbial Biology; University of California; Berkeley CA 94720 USA
| | - Véronique Decognet
- INRA, UR 407 Plant Pathology Unit; Domaine Saint Maurice; Montfavet F-84143 France
| | - Marc Fermaud
- INRA UMR 1065 SAVE; ISVV; 71 Avenue Edouard Bourlaux Villenave d'Ornon F-33882 France
| | - Johann Confais
- INRA, UR 1290 BIOGER-CPP; Avenue Lucien Brétignières Thiverval-Grignon F-78850 France
| | - Jean Roudet
- INRA UMR 1065 SAVE; ISVV; 71 Avenue Edouard Bourlaux Villenave d'Ornon F-33882 France
| | - Marc Bardin
- INRA, UR 407 Plant Pathology Unit; Domaine Saint Maurice; Montfavet F-84143 France
| | - Alexandre Bout
- INRA, UMR 1355 ISA, TEAPEA; Sophia-Antipolis F-06903 France
| | - Philippe C. Nicot
- INRA, UR 407 Plant Pathology Unit; Domaine Saint Maurice; Montfavet F-84143 France
| | | | - Elisabeth Fournier
- INRA, UMR BGPI; TA A 54/K; Campus International de Baillarguet Montpellier F-34398 France
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62
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Gross A, Hosoya T, Queloz V. Population structure of the invasive forest pathogen Hymenoscyphus pseudoalbidus. Mol Ecol 2014; 23:2943-60. [PMID: 24819666 DOI: 10.1111/mec.12792] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 04/29/2014] [Accepted: 04/30/2014] [Indexed: 12/21/2022]
Abstract
Understanding the genetic diversity and structure of invasive pathogens in source and in introduced areas is crucial to the revelation of hidden biological features of an organism, to the reconstruction of the course of invasions and to the establishment of effective control measures. Hymenoscyphus pseudoalbidus (anamorph: Chalara fraxinea) is an invasive and highly destructive fungal pathogen found on common ash Fraxinus excelsior in Europe and is native to East Asia. To gain insights into its dispersal mechanisms and history of invasion, we used microsatellite markers and characterized the genetic structure and diversity of H. pseudoalbidus populations at three spatial levels: (i) between Europe and Japan, (ii) in Europe and (iii) at the epidemic's front in Switzerland. Phylogenetic and network analysis demonstrated that individuals from both regions are conspecific. However, populations from Japan harboured a higher genetic diversity and were genetically differentiated from European ones. No evident population structure was found among the 1208 European strains using Bayesian and multivariate clustering analysis. Only the distribution of genetic diversity in space, pairwise population differentiation (GST) and the spatial analysis of principal components revealed a faint geographical pattern around Europe. A significant allele deficiency in most European populations pointed to a recent genetic bottleneck, whereas no pattern of isolation by distance was found. Our data suggest that H. pseudoalbidus was introduced just once by at least two individuals. The potential source region of H. pseudoalbidus is vast, and further investigations are required for a more accurate localization of the source population.
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Affiliation(s)
- Andrin Gross
- Forest Pathology and Dendrology, Institute of Integrative Biology (IBZ), ETH Zurich, Universitätsstrasse 16, Zurich, 8092, Switzerland
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63
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The Irish potato famine pathogen Phytophthora infestans originated in central Mexico rather than the Andes. Proc Natl Acad Sci U S A 2014; 111:8791-6. [PMID: 24889615 DOI: 10.1073/pnas.1401884111] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Phytophthora infestans is a destructive plant pathogen best known for causing the disease that triggered the Irish potato famine and remains the most costly potato pathogen to manage worldwide. Identification of P. infestan's elusive center of origin is critical to understanding the mechanisms of repeated global emergence of this pathogen. There are two competing theories, placing the origin in either South America or in central Mexico, both of which are centers of diversity of Solanum host plants. To test these competing hypotheses, we conducted detailed phylogeographic and approximate Bayesian computation analyses, which are suitable approaches to unraveling complex demographic histories. Our analyses used microsatellite markers and sequences of four nuclear genes sampled from populations in the Andes, Mexico, and elsewhere. To infer the ancestral state, we included the closest known relatives Phytophthora phaseoli, Phytophthora mirabilis, and Phytophthora ipomoeae, as well as the interspecific hybrid Phytophthora andina. We did not find support for an Andean origin of P. infestans; rather, the sequence data suggest a Mexican origin. Our findings support the hypothesis that populations found in the Andes are descendants of the Mexican populations and reconcile previous findings of ancestral variation in the Andes. Although centers of origin are well documented as centers of evolution and diversity for numerous crop plants, the number of plant pathogens with a known geographic origin are limited. This work has important implications for our understanding of the coevolution of hosts and pathogens, as well as the harnessing of plant disease resistance to manage late blight.
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64
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Feau N, Dutech C, Brusini J, Rigling D, Robin C. Multiple introductions and recombination in Cryphonectria hypovirus 1: perspective for a sustainable biological control of chestnut blight. Evol Appl 2014; 7:580-96. [PMID: 24944571 PMCID: PMC4055179 DOI: 10.1111/eva.12157] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 03/03/2014] [Accepted: 03/06/2014] [Indexed: 11/26/2022] Open
Abstract
Cryphonectria hypovirus 1 (CHV1) is a mycovirus which decreases the virulence of its fungal host Cryphonectria parasitica, the causal agent of chestnut blight recently introduced in Europe. The understanding of the evolutionary processes which have shaped CHV1 populations in Europe is required to develop a sustainable biocontrol strategy targeting chestnut blight and effective in European chestnut forests. To retrace the evolutionary history of CHV1, we analyzed sequences from two genomic regions on a collection of 55 CHV1 strains from France and northern Spain, two countries where multiple introductions of C. parasitica occurred. Several recombination events and variable selection pressures contributed to CHV1 evolution, agreeing with a non-clock-like diversification rate. These two mechanisms may be at the origin of CHV1 population diversity observed in western Europe. Considering the actual prevalence of CHV1 and its association with host genotypes, multiple introductions of CHV1 may have occurred in Europe, some of them directly from Asia and some of them through North America. Although some viral strains remained with low frequency in their introduction area, multiple infections might have allowed homologous recombination within parental sequences. Some of these recombinant lineages are associated with the spread of CHV1 in European regions.
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Affiliation(s)
- Nicolas Feau
- INRA, UMR1202 BIOGECO F-33610, Cestas, France ; University Bordeaux, BIOGECO, UMR 1202 F-33400, Talence, France ; TAIGA-Lab, Forest Sciences Centre, University of British Columbia #3618-2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Cyril Dutech
- INRA, UMR1202 BIOGECO F-33610, Cestas, France ; University Bordeaux, BIOGECO, UMR 1202 F-33400, Talence, France
| | - Jérémie Brusini
- INRA, UMR1202 BIOGECO F-33610, Cestas, France ; University Bordeaux, BIOGECO, UMR 1202 F-33400, Talence, France ; Department of Ecology and Evolutionary Biology, Earth and Marine Sciences Building, University of California Santa Cruz, CA, 95064, USA
| | - Daniel Rigling
- WSL Swiss Federal Research Institute CH-8903, Birmensdorf, Switzerland
| | - Cécile Robin
- INRA, UMR1202 BIOGECO F-33610, Cestas, France ; University Bordeaux, BIOGECO, UMR 1202 F-33400, Talence, France
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65
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Rius M, Darling JA. How important is intraspecific genetic admixture to the success of colonising populations? Trends Ecol Evol 2014; 29:233-42. [DOI: 10.1016/j.tree.2014.02.003] [Citation(s) in RCA: 329] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 02/06/2014] [Accepted: 02/07/2014] [Indexed: 11/16/2022]
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66
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Fountain T, Duvaux L, Horsburgh G, Reinhardt K, Butlin RK. Human-facilitated metapopulation dynamics in an emerging pest species, Cimex lectularius. Mol Ecol 2014; 23:1071-84. [PMID: 24446663 PMCID: PMC4016754 DOI: 10.1111/mec.12673] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 01/06/2014] [Accepted: 01/13/2014] [Indexed: 12/01/2022]
Abstract
The number and demographic history of colonists can have dramatic consequences for the way in which genetic diversity is distributed and maintained in a metapopulation. The bed bug (Cimex lectularius) is a re-emerging pest species whose close association with humans has led to frequent local extinction and colonization, that is, to metapopulation dynamics. Pest control limits the lifespan of subpopulations, causing frequent local extinctions, and human-facilitated dispersal allows the colonization of empty patches. Founder events often result in drastic reductions in diversity and an increased influence of genetic drift. Coupled with restricted migration, this can lead to rapid population differentiation. We therefore predicted strong population structuring. Here, using 21 newly characterized microsatellite markers and approximate Bayesian computation (ABC), we investigate simplified versions of two classical models of metapopulation dynamics, in a coalescent framework, to estimate the number and genetic composition of founders in the common bed bug. We found very limited diversity within infestations but high degrees of structuring across the city of London, with extreme levels of genetic differentiation between infestations (FST = 0.59). ABC results suggest a common origin of all founders of a given subpopulation and that the numbers of colonists were low, implying that even a single mated female is enough to found a new infestation successfully. These patterns of colonization are close to the predictions of the propagule pool model, where all founders originate from the same parental infestation. These results show that aspects of metapopulation dynamics can be captured in simple models and provide insights that are valuable for the future targeted control of bed bug infestations.
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Affiliation(s)
- Toby Fountain
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK; Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
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67
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Schoebel CN, Stewart J, Gruenwald NJ, Rigling D, Prospero S. Population history and pathways of spread of the plant pathogen Phytophthora plurivora. PLoS One 2014; 9:e85368. [PMID: 24427303 PMCID: PMC3888410 DOI: 10.1371/journal.pone.0085368] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 11/25/2013] [Indexed: 12/05/2022] Open
Abstract
Human activity has been shown to considerably affect the spread of dangerous pests and pathogens worldwide. Therefore, strict regulations of international trade exist for particularly harmful pathogenic organisms. Phytophthora plurivora, which is not subject to regulations, is a plant pathogen frequently found on a broad range of host species, both in natural and artificial environments. It is supposed to be native to Europe while resident populations are also present in the US. We characterized a hierarchical sample of isolates from Europe and the US and conducted coalescent-, migration, and population genetic analysis of sequence and microsatellite data, to determine the pathways of spread and the demographic history of this pathogen. We found P. plurivora populations to be moderately diverse but not geographically structured. High levels of gene flow were observed within Europe and unidirectional from Europe to the US. Coalescent analyses revealed a signal of a recent expansion of the global P. plurivora population. Our study shows that P. plurivora has most likely been spread around the world by nursery trade of diseased plant material. In particular, P. plurivora was introduced into the US from Europe. International trade has allowed the pathogen to colonize new environments and/or hosts, resulting in population growth.
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Affiliation(s)
- Corine N. Schoebel
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Department of Biodiversity and Conservation Biology, Birmensdorf, Switzerland
| | - Jane Stewart
- USDA-ARS-Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America
- Department of Botany & Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Niklaus J. Gruenwald
- USDA-ARS-Horticultural Crops Research Laboratory, Corvallis, Oregon, United States of America
- Department of Botany & Plant Pathology, Oregon State University, Corvallis, Oregon, United States of America
| | - Daniel Rigling
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Department of Biodiversity and Conservation Biology, Birmensdorf, Switzerland
| | - Simone Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Department of Biodiversity and Conservation Biology, Birmensdorf, Switzerland
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Leroy T, Le Cam B, Lemaire C. When virulence originates from non-agricultural hosts: new insights into plant breeding. INFECTION GENETICS AND EVOLUTION 2014; 27:521-9. [PMID: 24412509 DOI: 10.1016/j.meegid.2013.12.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 12/11/2013] [Accepted: 12/30/2013] [Indexed: 12/27/2022]
Abstract
Monogenic plant resistance breakdown is a model for testing evolution in action in pathogens. As a rule, plant pathologists argue that virulence - the allele that allows pathogens to overcome resistance - is due to a new mutation at the avirulence locus within the native/endemic population that infects susceptible crops. In this article, we develop an alternative and neglected scenario where a given virulence pre-exists in a non-agricultural host and might be accidentally released or introduced on the matching resistant cultivar in the field. The main difference between the two scenarios is the divergence time expected between the avirulent and the virulent populations. As a consequence, population genetic approaches such as genome scans and Approximate Bayesian Computation methods allow explicit testing of the two scenarios by timing the divergence. This review then explores the fundamental implications of this alternative scenario for plant breeding, including the invasion of virulence or the evolution of more aggressive hybrids, and proposes concrete solutions to achieve a sustainable resistance.
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Affiliation(s)
- Thibault Leroy
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France
| | - Bruno Le Cam
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France
| | - Christophe Lemaire
- Université d'Angers, IRHS, PRES LUNAM, SFR QUASAV, Boulevard Lavoisier, 49045 Angers, France; INRA, IRHS, PRES LUNAM, SFR QUASAV, Rue Georges Morel, 49071 Beaucouzé, France; Agrocampus Ouest, IRHS, PRES LUNAM, SFR QUASAV, Rue Le Nôtre, 49045 Angers, France.
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69
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Peters FS, Busskamp J, Prospero S, Rigling D, Metzler B. Genetic diversification of the chestnut blight fungus Cryphonectria parasitica and its associated hypovirus in Germany. Fungal Biol 2013; 118:193-210. [PMID: 24528641 DOI: 10.1016/j.funbio.2013.11.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Revised: 11/06/2013] [Accepted: 11/20/2013] [Indexed: 10/25/2022]
Abstract
Chestnut blight in south-western Germany was first reported in 1992 and is since expanding in distribution. Here we investigated the invasion history of Cryphonectria parasitica and its associated hypovirus. For this, we characterized 284 isolates collected between 1992 and 2012 for hypovirulence, vegetative compatibility (vc), mating type, and microsatellite haplotype. A total of 27 haplotypes and 15 vc types were observed, although the C. parasitica population analyzed is currently dominated to 50 % by one haplotype and to 64 % by the vc type EU-2. Structure analysis indicated two divergent genetic pools. Over 66 % of the haplotypes belonged to a pool probably originating from northern Italy. Further diversification is expected due to ongoing sexual recombination, but also to new migration and additional introductions. Cryphonectria hypovirus 1 (CHV-1) was found in four of five C. parasitica populations from Baden-Württemberg. Genetic analysis of the 35 CHV-1 isolates obtained revealed that they all belong to the German subtype, although they have clearly diverged from the first German hypovirus isolated in 1992. Our study suggests that C. parasitica has been introduced into Germany several times from two different gene pools, whereas the hypovirus most probably has a single origin.
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Affiliation(s)
- Franziska S Peters
- FVA Forest Research Institute of Baden-Württemberg (FVA-BW), Dept. Forest Protection, Wonnhaldestr. 4, D-79100 Freiburg, Germany.
| | - Johanna Busskamp
- FVA Forest Research Institute of Baden-Württemberg (FVA-BW), Dept. Forest Protection, Wonnhaldestr. 4, D-79100 Freiburg, Germany.
| | - Simone Prospero
- WSL Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland.
| | - Daniel Rigling
- WSL Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903 Birmensdorf, Switzerland.
| | - Berthold Metzler
- FVA Forest Research Institute of Baden-Württemberg (FVA-BW), Dept. Forest Protection, Wonnhaldestr. 4, D-79100 Freiburg, Germany.
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70
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Schoebel CN, Jung E, Prospero S. Development of new polymorphic microsatellite markers for three closely related plant-pathogenic Phytophthora species using 454-pyrosequencing and their potential applications. PHYTOPATHOLOGY 2013; 103:1020-1027. [PMID: 23617336 DOI: 10.1094/phyto-01-13-0026-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Phytophthora spp. (oomycetes) are causal agents of devastating diseases on a high number of crops, ornamentals, and native plants worldwide. Neutral molecular markers are increasingly being used to investigate the genetic population structure and possible pathways of spread of different plant pathogens, including Phytophthora spp. In this study, polymorphic microsatellite markers were developed for three species of the former Phytophthora citricola species complex-namely, P. multivora, P. plurivora, and P. pini (P. citricola I)-using the 454-pyrosequencing technique. In total, 35 polymorphic microsatellite loci were found and further characterized: 11 for P. plurivora, 16 for P. multivora, and 8 for P. pini. Microsatellites with dinucleotide motifs repeated 6 to 10 times were the most common for all three species. On average, 65 alleles per species and 5.3 alleles per locus were detected. Most loci were characterized by a low observed heterozygosity, which might be due to the homothallic mating system of the three Phytophthora spp. targeted. Cross amplification of the newly developed markers was tested on 17 Phytophthora spp. belonging to five different internal transcribed spacer clades. Transferability success was generally low and decreased with increasing genetic distance from the species to the three target species. A set of four loci was selected to easily discriminate P. plurivora, P. multivora, and P. pini on the basis of presence or absence of a polymerase chain reaction amplicon on an agarose gel.
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71
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Garbelotto M, Guglielmo F, Mascheretti S, Croucher PJP, Gonthier P. Population genetic analyses provide insights on the introduction pathway and spread patterns of the North American forest pathogen Heterobasidion irregulare in Italy. Mol Ecol 2013; 22:4855-69. [PMID: 24033583 DOI: 10.1111/mec.12452] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Revised: 07/12/2013] [Accepted: 07/15/2013] [Indexed: 11/26/2022]
Abstract
A population genetics approach is used to identify the most likely introduction site and introduction pathway for the North American forest pathogen Heterobasidion irregulare using 101 isolates from six sites in Italy and 34 isolates from five sites in North America. Diversity indices based on sequences from ten loci indicate the highest diversity in Italy is found in Castelfusano/Castelporziano and that diversity progressively decreases with increasing distance from that site. AMOVA, Bayesian clustering and principal coordinates analyses based on 12 SSR loci indicate high levels of gene flow among sites, high frequency of admixing, and fail to identify groups of genotypes exclusive to single locations. Cumulatively, these analyses suggest the current infestation is the result of multiple genotypes expanding their range from a single site. Based on two sequenced loci, a single source site in North America could provide enough variability to explain the variability observed in Italy. These results support the notion that H. irregulare was introduced originally in Castelporziano: because Castelporziano has been sealed off from the rest of the world for centuries except for a camp set up by the US military in 1944, we conclude the fungus may have been transported in infected wood used by the military. Finally, spatial autocorrelation analyses using SSR data indicate a significant under-dispersion of alleles up to 0.5-10 km, while a significant overdispersion of alleles was detected at distances over 80 km: these ranges can be used to make predictions on the likely dispersal potential of the invasive pathogen.
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Affiliation(s)
- M Garbelotto
- Department of Environmental Science, Policy and Management, University of California at Berkeley, 37 Mulford Hall, Berkeley, CA, 94720, USA
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72
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Prospero S, Lutz A, Tavadze B, Supatashvili A, Rigling D. Discovery of a new gene pool and a high genetic diversity of the chestnut blight fungus Cryphonectria parasitica in Caucasian Georgia. INFECTION GENETICS AND EVOLUTION 2013; 20:131-9. [PMID: 23994123 DOI: 10.1016/j.meegid.2013.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 08/08/2013] [Accepted: 08/12/2013] [Indexed: 11/24/2022]
Abstract
In this study, we investigated the population genetic structure and possible origins of the plant pathogen Cryphonectria parasitica in Caucasian Georgia, a region within the centre of origin of the host species Castanea sativa. A total of 427 C. parasitica isolates from nine populations were genotyped at 10 microsatellite loci. A high genetic diversity was detected, but the overall Georgian population was dominated by three haplotypes which were present in most individual populations. Two of them have not been previously found in Europe. Bayesian clustering analysis and principal component analysis could not identify their source population, neither in Asia nor in North America. On the other hand, one haplotype is frequent in Central Europe and probably naturally invaded Caucasian Georgia from neighbouring Turkey. Seventy-three haplotypes were unique to specific populations, and 66 of them were represented by a single isolate. Allele patterns suggest that most of these haplotypes emerged locally through sexual recombination between haplotypes of the Georgian and the central European gene pool. Due to the high incidence of haplotypes not otherwise present in Europe, Caucasian Georgia represents an additional source of diversity for the European C. parasitica population.
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Affiliation(s)
- S Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, CH-8903 Birmensdorf, Switzerland.
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73
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Gilabert A, Wasmuth JD. Unravelling parasitic nematode natural history using population genetics. Trends Parasitol 2013; 29:438-48. [PMID: 23948430 DOI: 10.1016/j.pt.2013.07.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 01/01/2023]
Abstract
The health and economic importance of parasitic nematodes cannot be overstated. Moreover, they offer a complex and diverse array of life strategies, raising a multitude of evolutionary questions. Researchers are applying population genetics to parasitic nematodes in order to disentangle some aspects of their life strategies, improve our knowledge about disease epidemiology, and design control strategies. However, population genetics studies of nematodes have been constrained due to the difficulty in sampling nematodes and developing molecular markers. In this context, new computational and sequencing technologies represent promising tools to investigate population genomics of parasitic, non-model, nematode species in an epidemiological context.
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Affiliation(s)
- Aude Gilabert
- Department of Ecosystem and Public Health, Faculty of Veterinary Medicine, University of Calgary, 3280 Hospital Drive NW, Calgary, Alberta, T2N 4Z6, Canada
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74
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Combining field epidemiological information and genetic data to comprehensively reconstruct the invasion history and the microevolution of the sudden oak death agent Phytophthora ramorum (Stramenopila: Oomycetes) in California. Biol Invasions 2013; 15:2281-2297. [PMID: 24078788 PMCID: PMC3782357 DOI: 10.1007/s10530-013-0453-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 03/18/2013] [Indexed: 11/27/2022]
Abstract
Understanding the migration patterns of invasive organisms is of paramount importance to predict and prevent their further spread. Previous attempts at reconstructing the entire history of the sudden oak death (SOD) epidemic in California were limited by: (1) incomplete sampling; (2) the inability to include infestations caused by a single genotype of the pathogen; (3) collapsing of non-spatially contiguous yet genetically similar samples into large meta-samples that confounded the coalescent analyses. Here, we employ an intensive sampling coverage of 832 isolates of Phytopthora ramorum (the causative agent of SOD) from 60 California forests, genotyped at nine microsatellite loci, to reconstruct its invasion. By using age of infestation as a constraint on coalescent analyses, by dividing genetically indistinguishable meta-populations into highly-resolved sets of spatially contiguous populations, and by using Bruvo genetic distances for most analyses, we reconstruct the entire history of the epidemic and convincingly show infected nursery plants are the original source for the entire California epidemic. Results indicate that multiple human-mediated introductions occurred in most counties and that further disease sources were represented by large wild infestations. The study also identifies minor introductions, some of them relatively recent, linked to infected ornamental plants. Finally, using archival isolates collected soon after the discovery of the pathogen in California, we corroborate that the epidemic is likely to have resulted form 3 to 4 core founder individuals evolved from a single genotype. This is probably the most complete reconstruction ever completed for an invasion by an exotic forest pathogen, and the approach here described may be useful for the reconstruction of invasions by any clonally reproducing organism with a relatively limited natural dispersal range.
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75
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Fontaine MC, Gladieux P, Hood ME, Giraud T. History of the invasion of the anther smut pathogen on Silene latifolia in North America. THE NEW PHYTOLOGIST 2013; 198:946-956. [PMID: 23406496 DOI: 10.1111/nph.12177] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
Understanding the routes of pathogen introduction contributes greatly to efforts to protect against future disease emergence. Here, we investigated the history of the invasion in North America by the fungal pathogen Microbotryum lychnidis-dioicae, which causes the anther smut disease on the white campion Silene latifolia. This system is a well-studied model in evolutionary biology and ecology of infectious disease in natural systems. Analyses based on microsatellite markers show that the introduced American M. lychnidis-dioicae probably came from Scotland, from a single population, and thus suffered from a drastic bottleneck compared with genetic diversity in the native European range. The pattern in M. lychnidis-dioicae contrasts with that found by previous studies in its host plant species S. latifolia, also introduced in North America. In the plant, several European lineages have been introduced from across Europe. The smaller number of introductions for M. lychnidis-dioicae probably relates to its life history traits, as it is an obligate, specialized pathogen that is neither transmitted by the seeds nor persistent in the environment. The results show that even a nonagricultural, biotrophic, and insect-vectored pathogen suffering from a very strong bottleneck can successfully establish populations on its introduced host.
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Affiliation(s)
- Michael C Fontaine
- Université Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, UMR8079, Orsay Cedex, F-91405, France
- CNRS, UMR 8079, Orsay Cedex, F-91405, France
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Pierre Gladieux
- Université Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, UMR8079, Orsay Cedex, F-91405, France
- CNRS, UMR 8079, Orsay Cedex, F-91405, France
- Plant and Microbial Biology, University of California, Berkeley, CA, USA
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, MA, USA
| | - Tatiana Giraud
- Université Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, UMR8079, Orsay Cedex, F-91405, France
- CNRS, UMR 8079, Orsay Cedex, F-91405, France
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76
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Fontaine MC, Austerlitz F, Giraud T, Labbé F, Papura D, Richard-Cervera S, Delmotte F. Genetic signature of a range expansion and leap-frog event after the recent invasion of Europe by the grapevine downy mildew pathogenPlasmopara viticola. Mol Ecol 2013; 22:2771-86. [DOI: 10.1111/mec.12293] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/11/2013] [Accepted: 02/14/2013] [Indexed: 01/26/2023]
Affiliation(s)
- Michael C. Fontaine
- Ecologie, Systématique et Evolution; UMR 8079 Université Paris Sud Laboratoire Ecologie; Systematique et Evolution; UMR8079 Orsay Cedex F-91405 France
- Eco-Anthropologie et Ethnobiologie; UMR 7206 CNRS; MNHN; Univ Paris Diderot; Sorbonne Paris Cité F-75231 Paris Cedex 5 France
| | - Fréderic Austerlitz
- Ecologie, Systématique et Evolution; UMR 8079 Université Paris Sud Laboratoire Ecologie; Systematique et Evolution; UMR8079 Orsay Cedex F-91405 France
- Eco-Anthropologie et Ethnobiologie; UMR 7206 CNRS; MNHN; Univ Paris Diderot; Sorbonne Paris Cité F-75231 Paris Cedex 5 France
| | - Tatiana Giraud
- Ecologie, Systématique et Evolution; UMR 8079 Université Paris Sud Laboratoire Ecologie; Systematique et Evolution; UMR8079 Orsay Cedex F-91405 France
| | - Frédéric Labbé
- Ecologie, Systématique et Evolution; UMR 8079 Université Paris Sud Laboratoire Ecologie; Systematique et Evolution; UMR8079 Orsay Cedex F-91405 France
| | - Daciana Papura
- INRA; UMR1065 Santé et Agroécologie du Vignoble; ISVV; F-33883 Villenave d'Ornon Cedex France
| | - Sylvie Richard-Cervera
- INRA; UMR1065 Santé et Agroécologie du Vignoble; ISVV; F-33883 Villenave d'Ornon Cedex France
| | - François Delmotte
- INRA; UMR1065 Santé et Agroécologie du Vignoble; ISVV; F-33883 Villenave d'Ornon Cedex France
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Abstract
Exotic, invasive pathogens have emerged repeatedly and continue to emerge to threaten the world's forests. Ecosystem structure and function can be permanently changed when keystone tree species such as the American chestnut (Castanea dentata) are eliminated from a whole range by disease. The fungal ascomycete pathogen Cryphonectria parasitica is responsible for causing chestnut blight. Once the pathogen was introduced into the Eastern US, where chestnuts were predominant, chestnuts were all but eliminated. This pathogen is currently causing extensive damage in Europe. A study in this issue of Molecular Ecology sheds new light on the pattern and process of emergence of this devastating plant pathogen (Dutech et al. 2012). The authors used microsatellite markers to investigate the evolutionary history of C. parasitica populations introduced into North America and Europe. To infer sources of migrants and the migration events, the authors included putative source populations endemic to China and Japan, inferred potentially unsampled populations and conducted a multivariate population genetic and complex ABC analysis. Cryphonectria parasitica emerges as an example of an introduced pathogen with limited genotypic diversity and some admixture in the invaded ranges, yet repeated invasions into different areas of Europe and the United States. This work sheds new light on the emergence of C. parasitica providing compelling evidence that this pathogen emerged by repeated migration and occasional admixture.
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Affiliation(s)
- Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service (ARS), Corvallis, OR 97330, USA.
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78
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Brusini J, Robin C. Mycovirus transmission revisited by in situ pairings of vegetatively incompatible isolates of Cryphonectria parasitica. J Virol Methods 2012. [PMID: 23201291 DOI: 10.1016/j.jviromet.2012.11.025] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In disease ecology, parasite transmission is a key parameter important at both epidemiological and evolutionary scales. Mycoviruses can be transmitted both horizontally and vertically. Their horizontal transmission is strongly restricted by the host vegetative compatibility system, which controls the outcome of somatic fusion in fungi, and by the same way, may limit mycovirus transmission. However, most of current knowledge and predictive capabilities regarding these host/pathogen systems are derived from studies pairing fungal mycelia on artificial medium. An original bioassay method, using infected mycelia as well as asexual spores, had been developed to assess in situ transmission of Cryphonectria Hypovirus-1 (CHV1), a mycovirus of Cryphonectria parasitica that causes chestnut blight. For every pair of different vegetative compatibility types tested, rates of CHV1 transmission were always superior in situ than in vitro. This study supports the hypothesis that the natural ability of CHV1 to migrate within a fungal population composed of different vegetative compatible types may have been underestimated by in vitro essays. This result offers opportunities for a biological control of fungal diseases with mycoviruses.
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79
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Bryner SF, Rigling D, Brunner PC. Invasion history and demographic pattern of Cryphonectria hypovirus 1 across European populations of the chestnut blight fungus. Ecol Evol 2012; 2:3227-41. [PMID: 23301186 PMCID: PMC3539014 DOI: 10.1002/ece3.429] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/09/2012] [Accepted: 10/13/2012] [Indexed: 01/16/2023] Open
Abstract
We reconstructed the invasion history of the fungal virus Cryphonectria hypovirus 1 (CHV-1) in Europe, which infects the chestnut blight fungus Cryphonectria parasitica. The pattern of virus evolution was inferred based on nucleotide sequence variation from isolates sampled across a wide area in Europe at different points in time. Phylogeny and time estimates suggested that CHV-1 was introduced together with its fungal host to Europe and that it rapidly colonized the central range along the south facing slopes of the Alps and the north-east facing slopes of the Dinaric Alps. These central populations were the source for two waves of simultaneous invasions toward the southern Balkans and Turkey, as indicated by migration rates. Our results showed that the evolutionary scenarios for CHV-1 and C. parasitica were spatially congruent. As infection with CHV-1 reduces the pathogenicity of C. parasitica toward the chestnut tree, CHV-1 invasions of the newly established C. parasitica populations probably prevented the development of devastating chestnut blight epidemics in Europe. We propose that in this, and supposedly in other pathosystems, geographic, vegetation-related, demographic, economic, and political factors may help explain the correlated invasion pattern of a parasite and its host.
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Affiliation(s)
- Sarah F Bryner
- WSL Swiss Federal Research Institute CH-8903, Birmensdorf, Switzerland
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