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Prunier JG, Saint‐Pé K, Blanchet S, Loot G, Rey O. Molecular approaches reveal weak sibship aggregation and a high dispersal propensity in a non-native fish parasite. Ecol Evol 2021; 11:6080-6090. [PMID: 34141204 PMCID: PMC8207417 DOI: 10.1002/ece3.7415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 02/09/2021] [Accepted: 02/11/2021] [Indexed: 11/19/2022] Open
Abstract
Inferring parameters related to the aggregation pattern of parasites and to their dispersal propensity are important for predicting their ecological consequences and evolutionary potential. Nonetheless, it is notoriously difficult to infer these parameters from wildlife parasites given the difficulty in tracking these organisms. Molecular-based inferences constitute a promising approach that has yet rarely been applied in the wild. Here, we combined several population genetic analyses including sibship reconstruction to document the genetic structure, patterns of sibship aggregation, and the dispersal dynamics of a non-native parasite of fish, the freshwater copepod ectoparasite Tracheliastes polycolpus. We collected parasites according to a hierarchical sampling design, with the sampling of all parasites from all host individuals captured in eight sites spread along an upstream-downstream river gradient. Individual multilocus genotypes were obtained from 14 microsatellite markers, and used to assign parasites to full-sib families and to investigate the genetic structure of T. polycolpus among both hosts and sampling sites. The distribution of full-sibs obtained among the sampling sites was used to estimate individual dispersal distances within families. Our results showed that T. polycolpus sibs tend to be aggregated within sites but not within host individuals. We detected important upstream-to-downstream dispersal events of T. polycolpus between sites (modal distance: 25.4 km; 95% CI [22.9, 27.7]), becoming scarcer as the geographic distance from their family core location increases. Such a dispersal pattern likely contributes to the strong isolation-by-distance observed at the river scale. We also detected some downstream-to-upstream dispersal events (modal distance: 2.6 km; 95% CI [2.2-23.3]) that likely result from movements of infected hosts. Within each site, the dispersal of free-living infective larvae among hosts likely contributes to increasing genetic diversity on hosts, possibly fostering the evolutionary potential of T. polycolpus.
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Affiliation(s)
| | - Keoni Saint‐Pé
- Station d'Écologie Théorique et ExpérimentaleUPR 2021MoulisFrance
| | - Simon Blanchet
- Station d'Écologie Théorique et ExpérimentaleUPR 2021MoulisFrance
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, Université Toulouse 3 Paul Sabatier, CNRS, IRDToulouseFrance
| | - Géraldine Loot
- Laboratoire Evolution et Diversité Biologique (EDB), UMR 5174, Université Toulouse 3 Paul Sabatier, CNRS, IRDToulouseFrance
| | - Olivier Rey
- IHPE, Univ Montpellier, CNRS, IFREMER, Univ Perpignan Via DomitiaPerpignanFrance
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2
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Hartmann FE, Snirc A, Cornille A, Godé C, Touzet P, Van Rossum F, Fournier E, Le Prieur S, Shykoff J, Giraud T. Congruent population genetic structures and divergence histories in anther‐smut fungi and their host plants
Silene italica
and the
Silene nutans
species complex. Mol Ecol 2020; 29:1154-1172. [DOI: 10.1111/mec.15387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 02/07/2020] [Accepted: 02/10/2020] [Indexed: 12/14/2022]
Affiliation(s)
- Fanny E. Hartmann
- Ecologie Systematique Evolution Batiment 360 AgroParisTech CNRS Universite Paris‐Saclay Orsay France
| | - Alodie Snirc
- Ecologie Systematique Evolution Batiment 360 AgroParisTech CNRS Universite Paris‐Saclay Orsay France
| | - Amandine Cornille
- Genetique Quantitative et Evolution–Le Moulon AgroParisTech CNRS INRAE Universite Paris‐Saclay Gif‐sur‐Yvette France
| | - Cécile Godé
- UMR 8198 ‐ Evo‐Eco‐Paleo CNRS Univ. Lille Lille France
| | - Pascal Touzet
- UMR 8198 ‐ Evo‐Eco‐Paleo CNRS Univ. Lille Lille France
| | - Fabienne Van Rossum
- Meise Botanic Garden Meise Belgium
- Fédération Wallonie–Bruxelles Brussels Belgium
| | | | - Stéphanie Le Prieur
- Ecologie Systematique Evolution Batiment 360 AgroParisTech CNRS Universite Paris‐Saclay Orsay France
| | - Jacqui Shykoff
- Ecologie Systematique Evolution Batiment 360 AgroParisTech CNRS Universite Paris‐Saclay Orsay France
| | - Tatiana Giraud
- Ecologie Systematique Evolution Batiment 360 AgroParisTech CNRS Universite Paris‐Saclay Orsay France
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3
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Wyman CR, Hadziabdic D, Boggess SL, Rinehart TA, Windham AS, Wadl PA, Trigiano RN. Low Genetic Diversity Suggests the Recent Introduction of Dogwood Powdery Mildew to North America. PLANT DISEASE 2019; 103:2903-2912. [PMID: 31449437 DOI: 10.1094/pdis-01-19-0051-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Cornus florida (flowering dogwood) is a popular understory tree endemic to the eastern hardwood forests of the United States. In 1996, dogwood powdery mildew caused by Erysiphe pulchra, an obligate biotrophic fungus of large bracted dogwoods, reached epidemic levels throughout the C. florida growing region. In the late 1990s, both sexual and asexual stages of E. pulchra were regularly observed; thereafter, the sexual stage was found less frequently. We examined the genetic diversity and population structure of 167 E. pulchra samples on C. florida leaves using 15 microsatellite loci. Samples were organized into two separate collection zone data sets, separated as eight zones and two zones, for the subsequent analysis of microsatellite allele length data. Clone correction analysis reduced the sample size to 90 multilocus haplotypes. Our study indicated low genetic diversity, a lack of definitive population structure, low genetic distance among multilocus haplotypes, and significant linkage disequilibrium among zones. Evidence of a population bottleneck was also detected. The results of our study indicated a high probability that E. pulchra reproduces predominately via asexual conidia and lend support to the hypothesis that E. pulchra is an exotic pathogen to North America.[Formula: see text] Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Christopher R Wyman
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996
| | - Denita Hadziabdic
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996
| | - Sarah L Boggess
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996
| | - Timothy A Rinehart
- United States Department of Agriculture, Agriculture Research Service, Crop Production and Protection, Beltsville, MD 20705
| | - Alan S Windham
- Department of Entomology and Plant Pathology, University of Tennessee, Soil, Plant, and Pest Center, 5201 Marchant Drive, Nashville, TN 37211
| | - Phillip A Wadl
- United States Department of Agriculture, Agriculture Research Service, U.S. Vegetable Research, Charleston, SC 29414
| | - Robert N Trigiano
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996
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4
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Hartmann FE, Rodríguez de la Vega RC, Carpentier F, Gladieux P, Cornille A, Hood ME, Giraud T. Understanding Adaptation, Coevolution, Host Specialization, and Mating System in Castrating Anther-Smut Fungi by Combining Population and Comparative Genomics. ANNUAL REVIEW OF PHYTOPATHOLOGY 2019; 57:431-457. [PMID: 31337277 DOI: 10.1146/annurev-phyto-082718-095947] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Anther-smut fungi provide a powerful system to study host-pathogen specialization and coevolution, with hundreds of Microbotryum species specialized on diverse Caryophyllaceae plants, castrating their hosts through manipulation of the hosts' reproductive organs to facilitate disease transmission. Microbotryum fungi have exceptional genomic characteristics, including dimorphic mating-type chromosomes, that make this genus anexcellent model for studying the evolution of mating systems and their influence on population genetics structure and adaptive potential. Important insights into adaptation, coevolution, host specialization, and mating system evolution have been gained using anther-smut fungi, with new insights made possible by the recent advent of genomic approaches. We illustrate with Microbotryum case studies how using a combination of comparative genomics, population genomics, and transcriptomics approaches enables the integration of different evolutionary perspectives across different timescales. We also highlight current challenges and suggest future studies that will contribute to advancing our understanding of the mechanisms underlying adaptive processes in populations of fungal pathogens.
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Affiliation(s)
- Fanny E Hartmann
- Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, 91400 Orsay, France;
| | | | - Fantin Carpentier
- Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, 91400 Orsay, France;
| | - Pierre Gladieux
- UMR BGPI, Univ. Montpellier, INRA, CIRAD, Montpellier SupAgro, 34398 Montpellier, France
| | - Amandine Cornille
- Génétique Quantitative et Evolution-Le Moulon, INRA; Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Michael E Hood
- Biology Department, Amherst College, Amherst, Massachusetts 01002-5000, USA
| | - Tatiana Giraud
- Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, 91400 Orsay, France;
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5
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Fortuna TM, Namias A, Snirc A, Branca A, Hood ME, Raquin C, Shykoff JA, Giraud T. Multiple infections, relatedness and virulence in the anther-smut fungus castrating Saponaria plants. Mol Ecol 2018; 27:4947-4959. [PMID: 30372557 DOI: 10.1111/mec.14911] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/28/2018] [Accepted: 10/08/2018] [Indexed: 11/26/2022]
Abstract
Multiple infections (co-occurrence of multiple pathogen genotypes within an individual host) can have important impacts on diseases. Relatedness among pathogens can affect the likelihood of multiple infections and their consequences through kin selection. Previous studies on the castrating anther-smut fungus Microbotryum lychnidis-dioicae have shown that multiple infections occur in its host plant Silene latifolia. Relatedness was high among fungal genotypes within plants, which could result from competitive exclusion between unrelated fungal genotypes, from population structure or from interactions between plant and fungal genotypes for infection ability. Here, we aimed at disentangling these hypotheses using M. saponariae and its host Saponaria officinalis, both experimentally tractable for these questions. By analysing populations using microsatellite markers, we also found frequent occurrence of multiple infections and high relatedness among strains within host plants. Infections resulting from experimental inoculations in the greenhouse also revealed high relatedness among strains co-infecting host plants, even in clonally replicated plant genotypes, indicating that high relatedness within plants did not result merely from plant x fungus interactions or population structure. Furthermore, hyphal growth in vitro was affected by the presence of a competitor growing nearby and by its genetic similarity, although this latter effect was strain-dependent. Altogether, our results support the hypothesis that relatedness-dependent competitive exclusion occurs in Microbotryum fungi within plants. These microorganisms can thus respond to competitors and to their level of relatedness.
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Affiliation(s)
- Taiadjana M Fortuna
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Alice Namias
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France.,Département de Biologie, Ecole Normale Supérieure, PSL Research University, Paris, France
| | - Alodie Snirc
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Antoine Branca
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, Massachusetts
| | - Christian Raquin
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Jacqui A Shykoff
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
| | - Tatiana Giraud
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, France
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6
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Abbate JL, Gladieux P, Hood ME, de Vienne DM, Antonovics J, Snirc A, Giraud T. Co-occurrence among three divergent plant-castrating fungi in the same Silene host species. Mol Ecol 2018; 27:10.1111/mec.14805. [PMID: 30030861 PMCID: PMC6340787 DOI: 10.1111/mec.14805] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 06/21/2018] [Accepted: 07/05/2018] [Indexed: 01/04/2023]
Abstract
The competitive exclusion principle postulates that different species can only coexist in sympatry if they occupy distinct ecological niches. The goal of this study was to understand the geographical distribution of three species of Microbotryum anther-smut fungi that are distantly related but infect the same host plants, the sister species Silene vulgaris and S. uniflora, in Western Europe. We used microsatellite markers to investigate pathogen distribution in relation to host specialization and ecological factors. Microbotryum violaceo-irregulare was only found on S. vulgaris at high elevations in the Alps. Microbotryum lagerheimii could be subdivided into two genetically differentiated clusters, one on S. uniflora in the UK and the second on S. vulgaris in the Alps and Pyrenees. The most abundant pathogen species, M. silenes-inflatae, could be subdivided into four genetic clusters, co-occurring in the Alps, the UK and the Pyrenees, and was found on both S. vulgaris and S. uniflora. All three fungal species had high levels of homozygosity, in agreement with the selfing mating system generally observed in anther-smut fungi. The three pathogen species and genetic clusters had large range overlaps, but occurred at sites with different elevations, temperatures and precipitation levels. The three Microbotryum species thus do not appear to be maintained by host specialization or geographic allopatry, but instead may occupy different ecological niches in terms of environmental conditions.
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Affiliation(s)
- Jessica L. Abbate
- UMR MIVEGEC, IRD 224, CNRS, Université de Montpellier, F-34394 Montpellier, France
- UMR UMMISCO, IRD 209, UPMC, F-93143 Bondy, France
| | - Pierre Gladieux
- Laboratoire Ecologie Systématique et Evolution, Univ. Paris Sud, CNRS, AgroParisTech, Université Paris Saclay, Orsay, F-91400 France
- INRA, UMR BGPI, Bâtiment K; Campus International de Baillarguet, F-34398, Montpellier, France
| | - Michael E. Hood
- Biology Department, McGuire Life Sciences Building, Amherst College, Rts 9 & 116, Amherst, MA USA 01002-5000
| | - Damien M. de Vienne
- Laboratoire Ecologie Systématique et Evolution, Univ. Paris Sud, CNRS, AgroParisTech, Université Paris Saclay, Orsay, F-91400 France
- Laboratoire de Biométrie et Biologie Evolutive, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 5558, Université Lyon 1, F-69622 Villeurbanne, France
- Université de Lyon, F-69000 Lyon, France
| | - Janis Antonovics
- University of Virginia, Dept. of Biology, Gilmer Hall, Charlottesville, VA 22904, USA
| | - Alodie Snirc
- Laboratoire Ecologie Systématique et Evolution, Univ. Paris Sud, CNRS, AgroParisTech, Université Paris Saclay, Orsay, F-91400 France
| | - Tatiana Giraud
- Laboratoire Ecologie Systématique et Evolution, Univ. Paris Sud, CNRS, AgroParisTech, Université Paris Saclay, Orsay, F-91400 France
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7
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Coelho MA, Bakkeren G, Sun S, Hood ME, Giraud T. Fungal Sex: The Basidiomycota. Microbiol Spectr 2017; 5:10.1128/microbiolspec.FUNK-0046-2016. [PMID: 28597825 PMCID: PMC5467461 DOI: 10.1128/microbiolspec.funk-0046-2016] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Indexed: 12/29/2022] Open
Abstract
Fungi of the Basidiomycota, representing major pathogen lineages and mushroom-forming species, exhibit diverse means to achieve sexual reproduction, with particularly varied mechanisms to determine compatibilities of haploid mating partners. For species that require mating between distinct genotypes, discrimination is usually based on both the reciprocal exchange of diffusible mating pheromones, rather than sexes, and the interactions of homeodomain protein signals after cell fusion. Both compatibility factors must be heterozygous in the product of mating, and genetic linkage relationships of the mating pheromone/receptor and homeodomain genes largely determine the complex patterns of mating-type variation. Independent segregation of the two compatibility factors can create four haploid mating genotypes from meiosis, referred to as tetrapolarity. This condition is thought to be ancestral to the basidiomycetes. Alternatively, cosegregation by linkage of the two mating factors, or in some cases the absence of the pheromone-based discrimination, yields only two mating types from meiosis, referred to as bipolarity. Several species are now known to have large and highly rearranged chromosomal regions linked to mating-type genes. At the population level, polymorphism of the mating-type genes is an exceptional aspect of some basidiomycete fungi, where selection under outcrossing for rare, intercompatible allelic variants is thought to be responsible for numbers of mating types that may reach several thousand. Advances in genome sequencing and assembly are yielding new insights by comparative approaches among and within basidiomycete species, with the promise to resolve the evolutionary origins and dynamics of mating compatibility genetics in this major eukaryotic lineage.
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Affiliation(s)
- Marco A. Coelho
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
| | - Guus Bakkeren
- Agriculture and Agri-Food Canada, Summerland Research and Development Centre Summerland, BC, V0H 1Z0, Canada
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Michael E. Hood
- Department of Biology, Amherst College, 01002-5000 Amherst, Massachusetts, USA
| | - Tatiana Giraud
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
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8
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Petit E, Silver C, Cornille A, Gladieux P, Rosenthal L, Bruns E, Yee S, Antonovics J, Giraud T, Hood ME. Co-occurrence and hybridization of anther-smut pathogens specialized on Dianthus hosts. Mol Ecol 2017; 26:1877-1890. [PMID: 28231407 DOI: 10.1111/mec.14073] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/13/2017] [Accepted: 02/09/2017] [Indexed: 01/05/2023]
Abstract
Host specialization has important consequences for the diversification and ecological interactions of obligate pathogens. The anther-smut disease of natural plant populations, caused by Microbotryum fungi, has been characterized by specialized host-pathogen interactions, which contribute in part to the isolation among these numerous fungal species. This study investigated the molecular variation of Microbotryum pathogens within the geographic and host-specific distributions on wild Dianthus species in southern European Alps. In contrast to prior studies on this pathogen genus, a range of overlapping host specificities was observed for four delineated Microbotryum lineages on Dianthus hosts, and their frequent co-occurrence within single-host populations was quantified at local and regional scales. In addition to potential consequences for direct pathogen competition, the sympatry of Microbotryum lineages led to hybridization between them in many populations, and these admixed genotypes suffered significant meiotic sterility. Therefore, this investigation of the anther-smut fungi reveals how variation in the degrees of host specificity can have major implications for ecological interactions and genetic integrity of differentiated pathogen lineages.
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Affiliation(s)
- Elsa Petit
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, USA
| | - Casey Silver
- Biology Department, Amherst College, Amherst, MA, 01002, USA
| | - Amandine Cornille
- Center for Adaptation to a Changing Environment, ETH Zürich, 8092, Zürich, Switzerland
| | - Pierre Gladieux
- UMR BGPI, INRA, Campus International de Baillarguet, 34398, Montpellier, France
| | - Lisa Rosenthal
- Biology Department, Amherst College, Amherst, MA, 01002, USA
| | - Emily Bruns
- Department of Biology, University of Virginia, Charlottesville, VA, 22903, USA
| | - Sarah Yee
- Biology Department, Amherst College, Amherst, MA, 01002, USA
| | - Janis Antonovics
- Department of Biology, University of Virginia, Charlottesville, VA, 22903, USA
| | - Tatiana Giraud
- Ecologie Systematique Evolution, CNRS, University of Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Michael E Hood
- Biology Department, Amherst College, Amherst, MA, 01002, USA
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9
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Devier B, Aguileta G, Hood ME, Giraud T. Using phylogenies of pheromone receptor genes in theMicrobotryum violaceumspecies complex to investigate possible speciation by hybridization. Mycologia 2017; 102:689-96. [DOI: 10.3852/09-192] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
| | - Gabriela Aguileta
- Ecologie, Systématique et Evolution, Université Paris-Sud, F-91405 Orsay cedex, France; CNRS F-91405 Orsay cedex, France
| | - Michael E. Hood
- Department of Biology, McGuire Life Sciences Building, Amherst College, Amherst, Massachusetts 01002-5000
| | - Tatiana Giraud
- Ecologie, Systématique et Evolution, Université Paris-Sud, F-91405 Orsay cedex, France; CNRS F-91405 Orsay cedex, France
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10
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Affiliation(s)
- Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Timothy Y. James
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109
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11
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Fortuna TM, Snirc A, Badouin H, Gouzy J, Siguenza S, Esquerre D, Le Prieur S, Shykoff JA, Giraud T. Polymorphic Microsatellite Markers for the Tetrapolar Anther-Smut Fungus Microbotryum saponariae Based on Genome Sequencing. PLoS One 2016; 11:e0165656. [PMID: 27832131 PMCID: PMC5104459 DOI: 10.1371/journal.pone.0165656] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/14/2016] [Indexed: 01/06/2023] Open
Abstract
Background Anther-smut fungi belonging to the genus Microbotryum sterilize their host plants by aborting ovaries and replacing pollen by fungal spores. Sibling Microbotryum species are highly specialized on their host plants and they have been widely used as models for studies of ecology and evolution of plant pathogenic fungi. However, most studies have focused, so far, on M. lychnidis-dioicae that parasitizes the white campion Silene latifolia. Microbotryum saponariae, parasitizing mainly Saponaria officinalis, is an interesting anther-smut fungus, since it belongs to a tetrapolar lineage (i.e., with two independently segregating mating-type loci), while most of the anther-smut Microbotryum fungi are bipolar (i.e., with a single mating-type locus). Saponaria officinalis is a widespread long-lived perennial plant species with multiple flowering stems, which makes its anther-smut pathogen a good model for studying phylogeography and within-host multiple infections. Principal Findings Here, based on a generated genome sequence of M. saponariae we developed 6 multiplexes with a total of 22 polymorphic microsatellite markers using an inexpensive and efficient method. We scored these markers in fungal individuals collected from 97 populations across Europe, and found that the number of their alleles ranged from 2 to 11, and their expected heterozygosity from 0.01 to 0.58. Cross-species amplification was examined using nine other Microbotryum species parasitizing hosts belonging to Silene, Dianthus and Knautia genera. All loci were successfully amplified in at least two other Microbotryum species. Significance These newly developed markers will provide insights into the population genetic structure and the occurrence of within-host multiple infections of M. saponariae. In addition, the draft genome of M. saponariae, as well as one of the described markers will be useful resources for studying the evolution of the breeding systems in the genus Microbotryum and the evolution of specialization onto different plant species.
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Affiliation(s)
- Taiadjana M. Fortuna
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
- * E-mail:
| | - Alodie Snirc
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Hélène Badouin
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Jérome Gouzy
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan, F-31326, France
- CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan, F-31326, France
| | - Sophie Siguenza
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan, F-31326, France
- CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan, F-31326, France
| | - Diane Esquerre
- GenPhySE, Université de Toulouse, INRA, INPT, ENVT, Castanet-Tolosan, F-31326, France
| | - Stéphanie Le Prieur
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Jacqui A. Shykoff
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Tatiana Giraud
- Laboratoire d’Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
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12
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Feurtey A, Gladieux P, Hood ME, Snirc A, Cornille A, Rosenthal L, Giraud T. Strong phylogeographic co-structure between the anther-smut fungus and its white campion host. THE NEW PHYTOLOGIST 2016; 212:668-679. [PMID: 27500396 DOI: 10.1111/nph.14125] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/18/2016] [Indexed: 06/06/2023]
Abstract
Although congruence between host and pathogen phylogenies has been extensively investigated, the congruence between host and pathogen genetic structures at the within-species level has received little attention. Using an unprecedented and comprehensive collection of associated plant-pathogen samples, we investigated the degree of congruence between the genetic structures across Europe of two evolutionary and ecological model organisms, the anther-smut pathogen Microbotryum lychnidis-dioicae and its host plant Silene latifolia. We demonstrated a significant and particularly strong level of host-pathogen co-structure, with three main genetic clusters displaying highly similar spatial ranges in Western Europe, Eastern Europe and Italy, respectively. Correcting for the geographical component of genetic variation, significant correlations were still found between the genetic distances of anther-smut and host populations. Inoculation experiments suggested plant local adaptation, at the cluster level, for resistance to pathogens. These findings indicate that the pathogen remained isolated in the same fragmented southern refugia as its host plant during the last glaciation, and that little long-distance dispersal has occurred since the recolonization of Europe for either the plant or the pathogen, despite their known ability to travel across continents. This, together with the inoculation results, suggests that coevolutionary and competitive processes may be drivers of host-pathogen co-structure.
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Affiliation(s)
- Alice Feurtey
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, 91400, France
| | - Pierre Gladieux
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, 91400, France
- UMR BGPI, INRA, Montpellier, 34398, France
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, MA, 01002, USA
| | - Alodie Snirc
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, 91400, France
| | - Amandine Cornille
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, 91400, France
| | - Lisa Rosenthal
- Department of Biology, Amherst College, Amherst, MA, 01002, USA
| | - Tatiana Giraud
- Ecologie Systématique Evolution, Univ. Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, Orsay, 91400, France.
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13
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Taschen E, Rousset F, Sauve M, Benoit L, Dubois MP, Richard F, Selosse MA. How the truffle got its mate: insights from genetic structure in spontaneous and planted Mediterranean populations ofTuber melanosporum. Mol Ecol 2016; 25:5611-5627. [DOI: 10.1111/mec.13864] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 09/17/2016] [Accepted: 09/19/2016] [Indexed: 02/01/2023]
Affiliation(s)
- E. Taschen
- CEFE UMR 5175; CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; 1919 route de Mende Montpellier 34293 France
- Institut de Systématique, Évolution; Biodiversité (ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE); Muséum National d'Histoire Naturelle; Sorbonne Universités; 57 rue Cuvier (CP50) Paris 75005 France
| | - F. Rousset
- Institut des Sciences de l'Evolution; Université de Montpellier; CNRS, IRD, EPHE CC 065; Place Eugène Bataillon Montpellier 34095 France
| | - M. Sauve
- CEFE UMR 5175; CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; 1919 route de Mende Montpellier 34293 France
| | - L. Benoit
- CEFE UMR 5175; CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; 1919 route de Mende Montpellier 34293 France
| | - M.-P. Dubois
- CEFE UMR 5175; CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; 1919 route de Mende Montpellier 34293 France
| | - F. Richard
- CEFE UMR 5175; CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE; 1919 route de Mende Montpellier 34293 France
| | - M.-A. Selosse
- Institut de Systématique, Évolution; Biodiversité (ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE); Muséum National d'Histoire Naturelle; Sorbonne Universités; 57 rue Cuvier (CP50) Paris 75005 France
- Department of Plant Taxonomy and Nature Conservation; University of Gdansk; Wita Stwosza 59 Gdansk 80-308 Poland
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14
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Bueker B, Eberlein C, Gladieux P, Schaefer A, Snirc A, Bennett DJ, Begerow D, Hood ME, Giraud T. Distribution and population structure of the anther smut Microbotryum silenes-acaulis parasitizing an arctic-alpine plant. Mol Ecol 2016; 25:811-24. [PMID: 26671732 DOI: 10.1111/mec.13512] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 11/02/2015] [Accepted: 11/26/2015] [Indexed: 12/18/2022]
Abstract
Cold-adapted organisms with current arctic-alpine distributions have persisted during the last glaciation in multiple ice-free refugia, leaving footprints in their population structure that contrast with temperate plants and animals. However, pathogens that live within hosts having arctic-alpine distributions have been little studied. Here, we therefore investigated the geographical range and population structure of a fungus parasitizing an arctic-alpine plant. A total of 1437 herbarium specimens of the plant Silene acaulis were examined, and the anther smut pathogen Microbotryum silenes-acaulis was present throughout the host's geographical range. There was significantly greater incidence of anther smut disease in more northern latitudes and where the host locations were less dense, indicating a major influence of environmental factors and/or host demographic structure on the pathogen distribution. Genetic analyses with seven microsatellite markers on recent collections of 195 M. silenes-acaulis individuals revealed three main genetic clusters, in North America, northern Europe and southern Europe, likely corresponding to differentiation in distinct refugia during the last glaciation. The lower genetic diversity in northern Europe indicates postglacial recolonization northwards from southern refugia. This study combining herbarium surveys and population genetics thus uniquely reveals the effects of climate and environmental factors on a plant pathogen species with an arctic-alpine distribution.
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Affiliation(s)
- Britta Bueker
- Lehrstuhl für Evolution und Biodiversität der Pflanzen, AG Geobotanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany.,Department of Biology, Amherst College, 220 South Pleasant Street, Amherst, MA, 01002, USA
| | - Chris Eberlein
- Lehrstuhl für Evolution und Biodiversität der Pflanzen, AG Geobotanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany.,Institut de Biologie Intégrative et des Systèmes, Département de Biologie, PROTEO, Université Laval, Pavillon Charles-Eugène-Marchand, 1030 Avenue de la Médicine, Quebec City, Quebec, Canada, G1V 0A6
| | - Pierre Gladieux
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France.,INRA, UMR BGPI, Bâtiment K, Campus International de Baillarguet, F-34398, Montpellier, France.,CIRAD, F-34398, Montpellier, France
| | - Angela Schaefer
- Lehrstuhl für Evolution und Biodiversität der Pflanzen, AG Geobotanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Alodie Snirc
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Dominic J Bennett
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France.,Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Dominik Begerow
- Lehrstuhl für Evolution und Biodiversität der Pflanzen, AG Geobotanik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780, Bochum, Germany
| | - Michael E Hood
- Department of Biology, Amherst College, 220 South Pleasant Street, Amherst, MA, 01002, USA
| | - Tatiana Giraud
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
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15
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Aguileta G, Badouin H, Hood ME, Møller AP, Le Prieur S, Snirc A, Siguenza S, Mousseau TA, Shykoff JA, Cuomo CA, Giraud T. Lower prevalence but similar fitness in a parasitic fungus at higher radiation levels near Chernobyl. Mol Ecol 2016; 25:3370-83. [PMID: 27136128 DOI: 10.1111/mec.13675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/04/2016] [Accepted: 04/15/2016] [Indexed: 12/24/2022]
Abstract
Nuclear disasters at Chernobyl and Fukushima provide examples of effects of acute ionizing radiation on mutations that can affect the fitness and distribution of species. Here, we investigated the prevalence of Microbotryum lychnidis-dioicae, a pollinator-transmitted fungal pathogen of plants causing anther-smut disease in Chernobyl, its viability, fertility and karyotype variation, and the accumulation of nonsynonymous mutations in its genome. We collected diseased flowers of Silene latifolia from locations ranging by more than two orders of magnitude in background radiation, from 0.05 to 21.03 μGy/h. Disease prevalence decreased significantly with increasing radiation level, possibly due to lower pollinator abundance and altered pollinator behaviour. Viability and fertility, measured as the budding rate of haploid sporidia following meiosis from the diploid teliospores, did not vary with increasing radiation levels and neither did karyotype overall structure and level of chromosomal size heterozygosity. We sequenced the genomes of twelve samples from Chernobyl and of four samples collected from uncontaminated areas and analysed alignments of 6068 predicted genes, corresponding to 1.04 × 10(7) base pairs. We found no dose-dependent differences in substitution rates (neither dN, dS, nor dN/dS). Thus, we found no significant evidence of increased deleterious mutation rates at higher levels of background radiation in this plant pathogen. We even found lower levels of nonsynonymous substitution rates in contaminated areas compared to control regions, suggesting that purifying selection was stronger in contaminated than uncontaminated areas. We briefly discuss the possibilities for a mechanistic basis of radio resistance in this nonmelanized fungus.
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Affiliation(s)
- Gabriela Aguileta
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Helene Badouin
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Michael E Hood
- Biology Department, Amherst College, Amherst, MA 01002, USA
| | - Anders P Møller
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Stephanie Le Prieur
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Alodie Snirc
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | - Sophie Siguenza
- INRA, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR441, Castanet-Tolosan, F-31326, France.,CNRS, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR2594, Castanet-Tolosan, F-31326, France
| | - Timothy A Mousseau
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Jacqui A Shykoff
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
| | | | - Tatiana Giraud
- Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France
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16
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Xu L, Petit E, Hood ME. Variation in mate-recognition pheromones of the fungal genus Microbotryum. Heredity (Edinb) 2015; 116:44-51. [PMID: 26306729 PMCID: PMC4675872 DOI: 10.1038/hdy.2015.68] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 05/05/2015] [Accepted: 06/09/2015] [Indexed: 11/24/2022] Open
Abstract
Mate recognition is an essential life-cycle stage that exhibits strong conservation in function, whereas diversification of mating signals can contribute directly to the integrity of species boundaries through assortative mating. Fungi are simple models, where compatibility is based on the recognition of pheromone peptides by corresponding receptor proteins, but clear patterns of diversification have not emerged from the species examined, which are few compared with mate signaling studies in plant and animal systems. In this study, candidate loci from Microbotryum species were used to characterize putative pheromones that were synthesized and found to be functional across multiple species in triggering a mating response in vitro. There is no significant correlation between the strength of a species' response and its genetic distance from the pheromone sequence source genome. Instead, evidence suggests that species may be strong or weak responders, influenced by environmental conditions or developmental differences. Gene sequence comparisons reveals very strong purifying selection on the a1 pheromone peptide and corresponding receptor, but significantly less purifying selection on the a2 pheromone peptide that corresponds with more variation across species in the receptor. This represents an exceptional case of a reciprocally interacting mate-recognition system in which the two mating types are under different levels of purifying selection.
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Affiliation(s)
- L Xu
- Department of Biology, Amherst College, Amherst, MA, USA
| | - E Petit
- Department of Biology, Amherst College, Amherst, MA, USA
| | - M E Hood
- Department of Biology, Amherst College, Amherst, MA, USA
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17
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Pintye A, Ropars J, Harvey N, Shin HD, Leyronas C, Nicot PC, Giraud T, Kiss L. Host phenology and geography as drivers of differentiation in generalist fungal mycoparasites. PLoS One 2015; 10:e0120703. [PMID: 25803832 PMCID: PMC4372539 DOI: 10.1371/journal.pone.0120703] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 01/25/2015] [Indexed: 11/19/2022] Open
Abstract
The question as to why parasites remain generalist or become specialist is a key unresolved question in evolutionary biology. Ampelomyces spp., intracellular mycoparasites of powdery mildew fungi, which are themselves plant pathogens, are a useful model for studies of this issue. Ampelomyces is used for the biological control of mildew. Differences in mycohost phenology promote temporal isolation between sympatric Ampelomyces mycoparasites. Apple powdery mildew (APM) causes spring epidemics, whereas other powdery mildew species on plants other than apple cause epidemics later in the season. This has resulted in genetic differentiation between APM and non-APM strains. It is unclear whether there is genetic differentiation between non-APM Ampelomyces lineages due to their specialization on different mycohosts. We used microsatellites to address this question and found no significant differentiation between non-APM Ampelomyces strains from different mycohosts or host plants, but strong differentiation between APM and non-APM strains. A geographical structure was revealed in both groups, with differences between European countries, demonstrating restricted dispersal at the continent scale and a high resolution for our markers. We found footprints of recombination in both groups, possibly more frequent in the APM cluster. Overall, Ampelomyces thus appears to be one of the rare genuine generalist pathogenic fungi able to parasitize multiple hosts in natural populations. It is therefore an excellent model for studying the evolution of pathogens towards a generalist rather than host-specific strategy, particularly in light of the tritrophic interaction between Ampelomyces mycoparasites, their powdery mildew fungal hosts and the mildew host plants.
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Affiliation(s)
- Alexandra Pintye
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), Budapest, Hungary
| | - Jeanne Ropars
- CNRS (Centre National de la Recherche Scientifique), Ecologie, Systematique et Evolution (ESE), Orsay, France
- Univ Paris Sud, Ecology, Systematique et Evolution (ESE), Orsay, France
| | - Nick Harvey
- Genetic Marker Services, 7 Brighton, United Kingdom
| | - Hyeon-Dong Shin
- Division of Environmental Science and Ecological Engineering, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Christel Leyronas
- Institut National de la Recherche Agronomique (INRA), Unite de Recherche UR407, Unité de Pathologie Végétale, Domaine St. Maurice, Montfavet, France
| | - Philippe C. Nicot
- Institut National de la Recherche Agronomique (INRA), Unite de Recherche UR407, Unité de Pathologie Végétale, Domaine St. Maurice, Montfavet, France
| | - Tatiana Giraud
- CNRS (Centre National de la Recherche Scientifique), Ecologie, Systematique et Evolution (ESE), Orsay, France
- Univ Paris Sud, Ecology, Systematique et Evolution (ESE), Orsay, France
- * E-mail: (TG); (LK)
| | - Levente Kiss
- Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences (MTA), Budapest, Hungary
- * E-mail: (TG); (LK)
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18
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Buono L, López-Villavicencio M, Shykoff JA, Snirc A, Giraud T. Influence of multiple infection and relatedness on virulence: disease dynamics in an experimental plant population and its castrating parasite. PLoS One 2014; 9:e98526. [PMID: 24892951 PMCID: PMC4043691 DOI: 10.1371/journal.pone.0098526] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/02/2014] [Indexed: 11/18/2022] Open
Abstract
The level of parasite virulence, i.e., the decrease in host's fitness due to a pathogen, is expected to depend on several parameters, such as the type of the disease (e.g., castrating or host-killing) and the prevalence of multiple infections. Although these parameters have been extensively studied theoretically, few empirical data are available to validate theoretical predictions. Using the anther smut castrating disease on Silene latifolia caused by Microbotryum lychnidis-dioicae, we studied the dynamics of multiple infections and of different components of virulence (host death, non-recovery and percentage of castrated stems) during the entire lifespan of the host in an experimental population. We monitored the number of fungal genotypes within plants and their relatedness across five years, using microsatellite markers, as well as the rates of recovery and host death in the population. The mean relatedness among genotypes within plants remained at a high level throughout the entire host lifespan despite the dynamics of the disease, with recurrent new infections. Recovery was lower for plants with multiple infections compared to plants infected by a single genotype. As expected for castrating parasites, M. lychnidis-dioicae did not increase host mortality. Mortality varied across years but was generally lower for plants that had been diseased the preceding year. This is one of the few studies to have empirically verified theoretical expectations for castrating parasites, and to show particularly i) that castrated hosts live longer, suggesting that parasites can redirect resources normally used in reproduction to increase host lifespan, lengthening their transmission phase, and ii) that multiple infections increase virulence, here in terms of non-recovery and host castration.
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Affiliation(s)
- Lorenza Buono
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Manuela López-Villavicencio
- Department Systématique et Evolution, Origine, Structure, Evolution de la Biodiversité, UMR 7205 CNRS-MNHN, Muséum National d'Histoire Naturelle, Paris, France
| | - Jacqui A. Shykoff
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Alodie Snirc
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
| | - Tatiana Giraud
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay, France
- Ecologie, Systématique et Evolution, CNRS, Orsay, France
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19
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Fournier E, Gladieux P, Giraud T. The 'Dr Jekyll and Mr Hyde fungus': noble rot versus gray mold symptoms of Botrytis cinerea on grapes. Evol Appl 2013; 6:960-9. [PMID: 24062804 PMCID: PMC3779096 DOI: 10.1111/eva.12079] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 04/08/2013] [Indexed: 11/29/2022] Open
Abstract
Many cryptic species have recently been discovered in fungi, especially in fungal plant pathogens. Cryptic fungal species co-occurring in sympatry may occupy slightly different ecological niches, for example infecting the same crop plant but specialized on different organs or having different phenologies. Identifying cryptic species in fungal pathogens of crops and determining their ecological specialization are therefore crucial for disease management. Here, we addressed this question in the ascomycete Botrytis cinerea, the agent of gray mold on a wide range of plants. On grape, B. cinerea causes severe damage but is also responsible for noble rot used for processing sweet wines. We used microsatellite genotyping and clustering methods to elucidate whether isolates sampled on gray mold versus noble rot symptoms in three French regions belong to genetically differentiated populations. The inferred population structure matched geography rather than the type of symptom. Noble rot symptoms therefore do not seem to be caused by a specific B. cinerea population but instead seem to depend essentially on microclimatic conditions, which has applied consequences for the production of sweet wines.
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Affiliation(s)
- Elisabeth Fournier
- Biologie et Génétique des Interactions Plante-Parasite, INRA-CIRAD-SupAgro Montpellier Cedex 5, France
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20
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Purifying selection after episodes of recurrent adaptive diversification in fungal pathogens. INFECTION GENETICS AND EVOLUTION 2013; 17:123-31. [DOI: 10.1016/j.meegid.2013.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 02/26/2013] [Accepted: 03/07/2013] [Indexed: 11/20/2022]
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21
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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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22
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Baumgartner K, Baker BR, Korhonen K, Zhao J, Hughes KW, Bruhn J, Bowman TS, Bergemann SE. Evidence of natural hybridization among homothallic members of the basidiomycete Armillaria mellea sensu stricto. Fungal Biol 2012; 116:677-91. [DOI: 10.1016/j.funbio.2012.03.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 02/24/2012] [Accepted: 03/30/2012] [Indexed: 01/09/2023]
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23
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Billiard S, López-Villavicencio M, Hood ME, Giraud T. Sex, outcrossing and mating types: unsolved questions in fungi and beyond. J Evol Biol 2012; 25:1020-38. [PMID: 22515640 DOI: 10.1111/j.1420-9101.2012.02495.x] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Variability in the way organisms reproduce raises numerous, and still unsolved, questions in evolutionary biology. In this study, we emphasize that fungi deserve a much greater emphasis in efforts to address these questions because of their multiple advantages as model eukaryotes. A tremendous diversity of reproductive modes and mating systems can be found in fungi, with many evolutionary transitions among closely related species. In addition, fungi show some peculiarities in their mating systems that have received little attention so far, despite the potential for providing insights into important evolutionary questions. In particular, selfing can occur at the haploid stage in addition to the diploid stage in many fungi, which is generally not possible in animals and plants but has a dramatic influence upon the structure of genetic systems. Fungi also present several advantages that make them tractable models for studies in experimental evolution. Here, we briefly review the unsolved questions and extant hypotheses about the evolution and maintenance of asexual vs. sexual reproduction and of selfing vs. outcrossing, focusing on fungal life cycles. We then propose how fungi can be used to address these long-standing questions and advance our understanding of sexual reproduction and mating systems across all eukaryotes.
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Affiliation(s)
- S Billiard
- Laboratoire de Génétique et Evolution des Populations Végétales, UMR CNRS 8016, Université des Sciences et Technologies de Lille - Lille1, Villeneuve d'Ascq Cedex, France.
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Gibson AK, Hood ME, Giraud T. Sibling competition arena: selfing and a competition arena can combine to constitute a barrier to gene flow in sympatry. Evolution 2012; 66:1917-30. [PMID: 22671556 DOI: 10.1111/j.1558-5646.2011.01563.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Closely related species coexisting in sympatry provide critical insight into the mechanisms underlying speciation and the maintenance of genetic divergence. Selfing may promote reproductive isolation by facilitating local adaptation, causing reduced hybrid fitness in parental environments. Here, we propose a novel mechanism by which selfing can further impair interspecific gene flow: selfing may act to ensure that nonhybrid progeny systematically co-occur whenever hybrid genotypes are produced. Under a competition arena, the fitness differentials between nonhybrid and hybrid progeny are then magnified, preventing development of interspecific hybrids. We investigate whether this "sibling competition arena" can explain the coexistence in sympatry of closely related species of the plant fungal pathogens (Microbotryum) causing anther-smut disease. The probabilities of intrapromycelial mating (automixis), outcrossing, and sibling competition were manipulated in artificial inoculations to evaluate their contribution to reproductive isolation. We report that both intrapromycelial selfing and sibling competition significantly reduced rates of hybrid infection beyond that expected based solely upon selfing rates and noncompetitive fitness differentials between hybrid and nonhybrid progeny. Our results thus suggest that selfing and a sibling competition arena can combine to constitute a barrier to gene flow and diminish selection for additional barriers to gene flow in sympatry.
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Affiliation(s)
- A K Gibson
- Laboratoire Ecologie, Systématique et Evolution, Université Paris Sud, 91405 Orsay, France.
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Votintseva AA, Filatov DA. DNA polymorphism in recombining and non-recombining mating-type-specific loci of the smut fungus Microbotryum. Heredity (Edinb) 2011; 106:936-44. [PMID: 21081967 PMCID: PMC3186254 DOI: 10.1038/hdy.2010.140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2009] [Revised: 07/21/2010] [Accepted: 09/06/2010] [Indexed: 11/09/2022] Open
Abstract
The population-genetic processes leading to the genetic degeneration of non-recombining regions have mainly been studied in animal and plant sex chromosomes. Here, we report population genetic analysis of the processes in the non-recombining mating-type-specific regions of the smut fungus Microbotryum violaceum. M. violaceum has A1 and A2 mating types, determined by mating-type-specific 'sex chromosomes' that contain 1-2 Mb long non-recombining regions. If genetic degeneration were occurring, then one would expect reduced DNA polymorphism in the non-recombining regions of this fungus. The analysis of DNA diversity among 19 M. violaceum strains, collected across Europe from Silene latifolia flowers, revealed that (i) DNA polymorphism is relatively low in all 20 studied loci (π∼0.15%), (ii) it is not significantly different between the two mating-type-specific chromosomes nor between the non-recombining and recombining regions, (iii) there is substantial population structure in M. violaceum populations, which resembles that of its host species, S. latifolia, and (iv) there is significant linkage disequilibrium, suggesting that widespread selfing in this species results in a reduction of the effective recombination rate across the genome. We hypothesise that selfing-related reduction of recombination across the M. violaceum genome negates the difference in the level of DNA polymorphism between the recombining and non-recombining regions, and may possibly lead to similar levels of genetic degeneration in the mating-type-specific regions of the non-recombining 'sex chromosomes' and elsewhere in the genome.
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Affiliation(s)
- A A Votintseva
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - D A Filatov
- Department of Plant Sciences, University of Oxford, Oxford, UK
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Kiss L, Pintye A, Kovács GM, Jankovics T, Fontaine MC, Harvey N, Xu X, Nicot PC, Bardin M, Shykoff JA, Giraud T. Temporal isolation explains host-related genetic differentiation in a group of widespread mycoparasitic fungi. Mol Ecol 2011; 20:1492-507. [PMID: 21261766 DOI: 10.1111/j.1365-294x.2011.05007.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Understanding the mechanisms responsible for divergence and specialization of pathogens on different hosts is of fundamental importance, especially in the context of the emergence of new diseases via host shifts. Temporal isolation has been reported in a few plants and parasites, but is probably one of the least studied speciation processes. We studied whether temporal isolation could be responsible for the maintenance of genetic differentiation among sympatric populations of Ampelomyces, widespread intracellular mycoparasites of powdery mildew fungi, themselves plant pathogens. The timing of transmission of Ampelomyces depends on the life cycles of the powdery mildew species they parasitize. Internal transcribed spacer sequences and microsatellite markers showed that Ampelomyces populations found in apple powdery mildew (Podosphaera leucotricha) were genetically highly differentiated from other Ampelomyces populations sampled from several other powdery mildew species across Europe, infecting plant hosts other than apple. While P. leucotricha starts its life cycle early in spring, and the main apple powdery mildew epidemics occur before summer, the fungal hosts of the other Ampelomyces cause epidemics mainly in summer and autumn. When two powdery mildew species were experimentally exposed to Ampelomyces strains naturally occurring in P. leucotricha in spring, and to strains naturally present in other mycohost species in autumn, cross-infections always occurred. Thus, the host-related genetic differentiation in Ampelomyces cannot be explained by narrow physiological specialization, because Ampelomyces were able to infect powdery mildew species they were unlikely to have encountered in nature, but instead appears to result from temporal isolation.
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Affiliation(s)
- Levente Kiss
- Plant Protection Institute of the Hungarian Academy of Sciences, Budapest, Hungary.
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López‐Villavicencio M, Courjol F, Gibson AK, Hood ME, Jonot O, Shykoff JA, Giraud T. COMPETITION, COOPERATION AMONG KIN, AND VIRULENCE IN MULTIPLE INFECTIONS. Evolution 2010; 65:1357-66. [DOI: 10.1111/j.1558-5646.2010.01207.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Manuela López‐Villavicencio
- Origine, Structure, Evolution de la Diversité, UMR 7205 CNRS‐MNHN, Muséum national d’histoire naturelle, CP39, 57 rue Cuvier, 75231 Paris Cedex 05, France
- E‐mail:
| | - Flavie Courjol
- Ecologie, Systématique et Evolution, UMR 8079, Bâtiment 360, Université Paris‐Sud, F‐91405 Orsay cedex, France; UMR 8079, Bâtiment 360, CNRS, F‐91405 Orsay cedex; France
- E‐mail:
| | - Amanda K. Gibson
- Ecologie, Systématique et Evolution, UMR 8079, Bâtiment 360, Université Paris‐Sud, F‐91405 Orsay cedex, France; UMR 8079, Bâtiment 360, CNRS, F‐91405 Orsay cedex; France
- E‐mail:
| | - Michael E. Hood
- Department of Biology, McGuire Life Sciences Building, Amherst College, Rts 9 and 116, Amherst, Massachusetts 01002‐5000
- E‐mail:
| | - Odile Jonot
- Ecologie, Systématique et Evolution, UMR 8079, Bâtiment 360, Université Paris‐Sud, F‐91405 Orsay cedex, France; UMR 8079, Bâtiment 360, CNRS, F‐91405 Orsay cedex; France
- E‐mail:
| | - Jacqui A. Shykoff
- Ecologie, Systématique et Evolution, UMR 8079, Bâtiment 360, Université Paris‐Sud, F‐91405 Orsay cedex, France; UMR 8079, Bâtiment 360, CNRS, F‐91405 Orsay cedex; France
- E‐mail:
| | - Tatiana Giraud
- Ecologie, Systématique et Evolution, UMR 8079, Bâtiment 360, Université Paris‐Sud, F‐91405 Orsay cedex, France; UMR 8079, Bâtiment 360, CNRS, F‐91405 Orsay cedex; France
- E‐mail:
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Vercken E, Fontaine MC, Gladieux P, Hood ME, Jonot O, Giraud T. Glacial refugia in pathogens: European genetic structure of anther smut pathogens on Silene latifolia and Silene dioica. PLoS Pathog 2010; 6:e1001229. [PMID: 21187901 PMCID: PMC3002987 DOI: 10.1371/journal.ppat.1001229] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 11/15/2010] [Indexed: 11/18/2022] Open
Abstract
Climate warming is predicted to increase the frequency of invasions by pathogens and to cause the large-scale redistribution of native host species, with dramatic consequences on the health of domesticated and wild populations of plants and animals. The study of historic range shifts in response to climate change, such as during interglacial cycles, can help in the prediction of the routes and dynamics of infectious diseases during the impending ecosystem changes. Here we studied the population structure in Europe of two Microbotryum species causing anther smut disease on the plants Silene latifolia and Silene dioica. Clustering analyses revealed the existence of genetically distinct groups for the pathogen on S. latifolia, providing a clear-cut example of European phylogeography reflecting recolonization from southern refugia after glaciation. The pathogen genetic structure was congruent with the genetic structure of its host species S. latifolia, suggesting dependence of the migration pathway of the anther smut fungus on its host. The fungus, however, appeared to have persisted in more numerous and smaller refugia than its host and to have experienced fewer events of large-scale dispersal. The anther smut pathogen on S. dioica also showed a strong phylogeographic structure that might be related to more northern glacial refugia. Differences in host ecology probably played a role in these differences in the pathogen population structure. Very high selfing rates were inferred in both fungal species, explaining the low levels of admixture between the genetic clusters. The systems studied here indicate that migration patterns caused by climate change can be expected to include pathogen invasions that follow the redistribution of their host species at continental scales, but also that the recolonization by pathogens is not simply a mirror of their hosts, even for obligate biotrophs, and that the ecology of hosts and pathogen mating systems likely affects recolonization patterns.
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Affiliation(s)
- Elodie Vercken
- Université Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, UMR 8079, Orsay, France.
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Wolinska J, Spaak P, Koerner H, Petrusek A, Seda J, Giessler S. Transmission mode affects the population genetic structure of Daphnia parasites. J Evol Biol 2010; 24:265-73. [PMID: 21044206 DOI: 10.1111/j.1420-9101.2010.02163.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Parasite life cycle variation can shape parasite evolution, by predisposing them towards different population genetic structures. We compared the population genetic structure of two co-occurring parasite species of Daphnia, to collect evidence for their expected transmission modes. The ichthyosporean Caullerya mesnili has a direct life cycle, whereas the microsporidian Berwaldia schaefernai is hypothesized to require passage through a secondary host. The parasites were collected from three geographically isolated Daphnia populations. The nucleotide variation in the internal transcribed spacer (ITS) region was assessed at the within-individual, within-population and among-population levels, using amova. We detected significant partitioning at all levels, except for a lack of among-population variation in Berwaldia. This was confirmed by neighbour-joining and principal component analyses; Caullerya populations were distinct from each other, while there was much overlap among parasite isolates representing different populations of Berwaldia. This all implies a higher amount of gene flow for Berwaldia, consistent with the hypothesized transmission mode.
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Affiliation(s)
- J Wolinska
- Department Biologie II, Evolutionsökologie, Ludwig-Maximilians-Universität, München, Germany.
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Gladieux P, Vercken E, Fontaine MC, Hood ME, Jonot O, Couloux A, Giraud T. Maintenance of fungal pathogen species that are specialized to different hosts: allopatric divergence and introgression through secondary contact. Mol Biol Evol 2010; 28:459-71. [PMID: 20837605 DOI: 10.1093/molbev/msq235] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Sympatry of species that lack complete prezygotic isolation is ideal for the study of how species can be maintained in the face of potential gene flow. This is particularly important in the context of emerging diseases on new hosts because pathogen adaptation is facilitated by reduced gene flow from ancestral populations. Here, we investigated divergence and gene flow between two closely related fungal species, Microbotryum lychnidis-dioicae and M. silenes-dioicae, causing anther-smut disease on the wide-spread plant species Silene latifolia and S. dioica, respectively. Using model-based clustering algorithms on microsatellite data from samples across Europe, we identified rare disease transmission between the host species and rare pathogen hybrids. Using a coalescent-based approach and an isolation-with-migration model, the age of divergence between the two fungal species was estimated at approximately 4.2 × 10(5) years. Levels of gene flow were low and concentrated in very recent times. In addition, gene flow appeared unidirectional from M. silenes-dioicae to M. lychnidis-dioicae. Altogether, our findings are consistent with a scenario of recurrent introgressive hybridization but at a very low level and through secondary contact following initial divergence in allopatry. Asymmetry in the direction of gene flow mirrors previous findings on introgression between the two host plants. Our study highlights the consequences of bringing closely related pathogens into contact, which is increasing through modern global changes and favors cross-species disease transmission, hybridization, and introgression by pathogens.
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Affiliation(s)
- Pierre Gladieux
- Laboratoire Ecologie, Systématique et Evolution, Univ Paris Sud, UMR8079, Orsay, France.
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Halkett F, Coste D, Platero GGR, Zapater MF, Abadie C, Carlier J. Genetic discontinuities and disequilibria in recently established populations of the plant pathogenic fungus Mycosphaerella fijiensis. Mol Ecol 2010; 19:3909-23. [PMID: 20723067 DOI: 10.1111/j.1365-294x.2010.04774.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Dispersal processes of fungal plant pathogens can be inferred from analysis of spatial genetic structures resulting from recent range expansion. The relative importance of long-distance dispersal (LDD) events vs. gradual dispersal in shaping population structures depends on the geographical scale considered. The fungus Mycosphaerella fijiensis, pathogenic on banana, is an example of a recent worldwide epidemic. Founder effects in this species were detected at both global and continental scale, suggesting stochastic spread of the disease through LDD events. In this study, we analysed the structure of M. fijiensis populations in two recently (∼1979-1980) colonized areas in Costa Rica and Cameroon. Isolates collected in 10-15 sites distributed along a ∼250- to 300- km-long transect in each country were analysed using 19 microsatellite markers. We detected low-to-moderate genetic differentiation among populations in both countries and isolation by distance in Cameroon. Combined with historical data, these observations suggest continuous range expansion at the scale of banana-production area through gradual dispersal of spores. However, both countries displayed specific additional signatures of colonization: a sharp discontinuity in gene frequencies was observed along the Cameroon transect, while the Costa Rican populations seemed not yet to have reached genetic equilibrium. These differences in the genetic characteristics of M. fijiensis populations in two recently colonized areas are discussed in the light of historical data on disease spread and ecological data on landscape features.
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Affiliation(s)
- F Halkett
- CIRAD, UMR BGPI, Campus international de Baillarguet, Montpellier Cedex, France
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Abstract
The spread of parasites is inherently a spatial process often embedded in physically complex landscapes. It is therefore not surprising that infectious disease researchers are increasingly taking a landscape genetics perspective to elucidate mechanisms underlying basic ecological processes driving infectious disease dynamics and to understand the linkage between spatially dependent population processes and the geographic distribution of genetic variation within both hosts and parasites. The increasing availability of genetic information on hosts and parasites when coupled to their ecological interactions can lead to insights for predicting patterns of disease emergence, spread and control. Here, we review research progress in this area based on four different motivations for the application of landscape genetics approaches: (i) assessing the spatial organization of genetic variation in parasites as a function of environmental variability, (ii) using host population genetic structure as a means to parameterize ecological dynamics that indirectly influence parasite populations, for example, gene flow and movement pathways across heterogeneous landscapes and the concurrent transport of infectious agents, (iii) elucidating the temporal and spatial scales of disease processes and (iv) reconstructing and understanding infectious disease invasion. Throughout this review, we emphasize that landscape genetic principles are relevant to infection dynamics across a range of scales from within host dynamics to global geographic patterns and that they can also be applied to unconventional 'landscapes' such as heterogeneous contact networks underlying the spread of human and livestock diseases. We conclude by discussing some general considerations and problems for inferring epidemiological processes from genetic data and try to identify possible future directions and applications for this rapidly expanding field.
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Affiliation(s)
- Roman Biek
- Division of Ecology and Evolutionary Biology, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Glasgow G12 8QQ, UK.
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Giraud F, Giraud T, Aguileta G, Fournier E, Samson R, Cruaud C, Lacoste S, Ropars J, Tellier A, Dupont J. Microsatellite loci to recognize species for the cheese starter and contaminating strains associated with cheese manufacturing. Int J Food Microbiol 2009; 137:204-13. [PMID: 20031244 DOI: 10.1016/j.ijfoodmicro.2009.11.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 11/05/2009] [Accepted: 11/20/2009] [Indexed: 10/20/2022]
Abstract
We report the development of 17 microsatellite markers in the cheese fungi Penicillium camemberti and P. roqueforti, using an enrichment protocol. Polymorphism and cross-amplification were explored using 23 isolates of P. camemberti, 26 isolates of P. roqueforti, and 2 isolates of each of the P. chrysogenum and P. nalgiovense species, used to produce meat fermented products. The markers appeared useful for differentiating species, both using their amplification sizes and the sequences of their flanking regions. The microsatellite locus PC4 was particularly suitable for distinguishing contaminant species closely related to P. camemberti and for clarifying the phylogenetic relationship of this species with its supposed ancestral form, P. commune. We analyzed 22 isolates from different culture collections assigned to the morphospecies P. commune, most of them occurring as food spoilers, mainly from the cheese environment. None of them exhibited identical sequences with the ex-type isolate of the species P. commune. They were instead distributed into two other distinct lineages, corresponding to the old species P. fuscoglaucum and P. biforme, previously synonymized respectively with P. commune and P. camemberti. The ex-type isolate of P. commune was strictly identical to P. camemberti at all the loci examined. P. caseifulvum, a non toxinogenic species described as a new candidate for cheese fermentation, also exhibited sequences identical to P. camemberti. The microsatellite locus PC4 may therefore be considered as a useful candidate for the barcode of these economically important species.
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Affiliation(s)
- Frédéric Giraud
- Muséum National d'Histoire Naturelle, Département Systématique et Evolution, UMR OSEB 7205, CP 39, 57 rue Cuvier, 75231 Paris Cedex 05, France
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Within-host competitive exclusion among species of the anther smut pathogen. BMC Ecol 2009; 9:11. [PMID: 19422703 PMCID: PMC2688501 DOI: 10.1186/1472-6785-9-11] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 05/07/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Host individuals represent an arena in which pathogens compete for resources and transmission opportunities, with major implications for the evolution of virulence and the structure of populations. Studies to date have focused on competitive interactions within pathogen species, and the level of antagonism tends to increase with the genetic distance between competitors. Anther-smut fungi, in the genus Microbotryum, have emerged as a tractable model for within-host competition. Here, using two pathogen species that are frequently found in sympatry, we investigated whether the antagonism seen among genotypes of the same species cascades up to influence competition among pathogen species. RESULTS Sequential inoculation of hosts showed that a resident infection most often excludes a challenging pathogen genotype, which is consistent with prior studies. However, the challenging pathogen was significantly more likely to invade the already-infected host if the resident infection was a conspecific genotype compared to challenges involving a closely related species. Moreover, when inter-specific co-infection occurred, the pathogens were highly segregated within the host, in contrast to intra-specific co-infection. CONCLUSION We show evidence that competitive exclusion during infection can be greater among closely related pathogen species than among genotypes within species. This pattern follows from prior studies demonstrating that genetic distance and antagonistic interactions are positively correlated in Microbotryum. Fungal vegetative incompatibility is a likely mechanism of direct competitive interference, and has been shown in some fungi to be effective both within and across species boundaries. For systems where related pathogen species frequently co-occur in the same host populations, these competitive dynamics may substantially impact the spatial segregation of pathogen species.
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De Vienne DM, Refrégier G, Hood ME, Guigue A, Devier B, Vercken E, Smadja C, Deseille A, Giraud T. Hybrid sterility and inviability in the parasitic fungal species complex Microbotryum. J Evol Biol 2009; 22:683-98. [PMID: 19228274 DOI: 10.1111/j.1420-9101.2009.01702.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbotryum violaceum, the anther-smut fungus, forms a complex of sibling species which specialize on different plants. Previous studies have shown the presence of partial ecological isolation and F1 inviability, but did not detect assortative mating apart from a high selfing rate. We investigated other post-mating barriers and show that F1 hybrid sterility, the inability of gametes to mate, increased gradually with the increasing genetic distance between the parents. F2 hybrids showed a reduced ability to infect the plants that was also correlated with the genetic distance. The host on which the F2 hybrids were passaged caused a selection for alleles derived from the pathogen species originally isolated from that host, but this effect was not detectable for the most closely related species. The post-mating barriers thus remain weak among the closest species pairs, suggesting that premating barriers are sufficient to initiate divergence in this system.
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Affiliation(s)
- D M De Vienne
- Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay Cedex, France
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Abstract
In the majority of sexual organisms, reproduction occurs almost exclusively through the combination of distinct and alternate forms, called sexes or mating types. In some fungi, there can be dozens to hundreds of alternate alleles that determine compatible mating types. Such extensive polymorphism is expected to be maintained by balancing selection, and in extreme cases may give rise to trans-specific polymorphism. Here, we analyzed sequences of two pheromone receptors in the Microbotryum fungal species complex (Basidiomycota), which has only two alternate mating types. Several lines of evidence strongly suggest that the pheromone receptors are two allelic sequences acting to determine the alternate A1 and A2 mating types required for mating in Microbotryum. Phylogenetic trees of pheromone receptors in the Microbotryum species complex indicated a trans-specific polymorphism: the Microbotryum sequences from a given mating type were all more similar to the pheromone receptors of distantly related classes of fungi than to the alternate pheromone receptor in the Microbotryum species. A phylogenetic tree built using other known pheromone receptors from basidiomycetes showed that trans-specific polymorphism is widespread. The pheromone receptor alleles from Microbotryum appeared as the oldest, being at least 370 million years old. This represents the oldest known trans-specific polymorphism known in any organism so far, which may be due to the existence of sex chromosomes, obligate sexuality, mitochondrial inheritance linked to the mating type, and a highly selfing mating system in Microbotryum.
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Barrett LG, Thrall PH, Burdon JJ, Linde CC. Life history determines genetic structure and evolutionary potential of host-parasite interactions. Trends Ecol Evol 2008; 23:678-85. [PMID: 18947899 DOI: 10.1016/j.tree.2008.06.017] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 06/25/2008] [Accepted: 06/26/2008] [Indexed: 02/04/2023]
Abstract
Measures of population genetic structure and diversity of disease-causing organisms are commonly used to draw inferences regarding their evolutionary history and potential to generate new variation in traits that determine interactions with their hosts. Parasite species exhibit a range of population structures and life-history strategies, including different transmission modes, life-cycle complexity, off-host survival mechanisms and dispersal ability. These are important determinants of the frequency and predictability of interactions with host species. Yet the complex causal relationships between spatial structure, life history and the evolutionary dynamics of parasite populations are not well understood. We demonstrate that a clear picture of the evolutionary potential of parasitic organisms and their demographic and evolutionary histories can only come from understanding the role of life history and spatial structure in influencing population dynamics and epidemiological patterns.
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Affiliation(s)
- Luke G Barrett
- CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601, Australia.
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Brooks C, Antonovics J, Keitt T. Spatial and Temporal Heterogeneity Explain Disease Dynamics in a Spatially Explicit Network Model. Am Nat 2008; 172:149-59. [DOI: 10.1086/589451] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Bauer R, Lutz M, Begerow D, Piatek M, Vánky K, Bacigálová K, Oberwinkler F. Anther smut fungi on monocots. ACTA ACUST UNITED AC 2008; 112:1297-306. [PMID: 18640272 DOI: 10.1016/j.mycres.2008.06.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Revised: 05/13/2008] [Accepted: 06/11/2008] [Indexed: 10/21/2022]
Abstract
Teliospores, hyphal septa, cellular interactions, and nucleotide sequences from the ITS and LSU region of the rRNA gene of specimens of Ustilago vaillantii s. lat. on Muscari and Scilla species were examined and compared with findings in other Ustilaginomycotina. The data show that U. vaillantii s. lat. specimens belong to the Urocystales and represent the sister group of the Urocystaceae, standing well apart from Vankya heufleri and V. ornithogali. Within the Urocystales, U. vaillantii s. lat. is unique in sporulating in the anthers of the host plants. Accordingly, the new genus Antherospora is proposed for the anther smuts on Hyacinthaceae. In addition, our data show that there is a stringent phylogenetic correlation between the specimens of Antherospora and their respective hosts. Thus, the specimens on Scilla spp. as well as those on Muscari spp. form highly supported monophyla. Furthermore, on Scilla a phylogenetic dichotomy exists between the specimens infecting Scilla bifolia and those infecting S. vindobonensis, with the specimens of the two host species showing a difference of 17bp in the ITS nucleotide sequences. Therefore, A. vindobonensis is described as a new species, and A. scillae and A. vaillantii are proposed as new combinations. Consequently, because of their sporulation in anthers and their parasitism on species of other genera of the Hyacinthaceae, Ustilago albucae, U. peglerae, U. tourneuxii, and U. urgineae are also ascribed to Antherospora as new combinations. Descriptions are given for all species.
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Affiliation(s)
- Robert Bauer
- Universität Tübingen, Botanisches Institut, Lehrstuhl Spezielle Botanik und Mykologie, Tübingen, Germany.
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GIRAUD T, YOCKTENG R, MARTHEY S, CHIAPELLO H, JONOT O, LOPEZ-VILLAVICENCIO M, DE VIENNE DM, HOOD ME, REFREGIER G, GENDRAULT-JACQUEMARD A, WINCKER P, DOSSAT C. PERMANENT GENETIC RESOURCES: Isolation of 60 polymorphic microsatellite loci in EST libraries of four sibling species of the phytopathogenic fungal complex Microbotryum. Mol Ecol Resour 2008; 8:387-92. [DOI: 10.1111/j.1471-8286.2007.01967.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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41
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Lutz M, Piatek M, Kemler M, Chlebicki A, Oberwinkler F. Anther smuts of Caryophyllaceae: molecular analyses reveal further new species. ACTA ACUST UNITED AC 2008; 112:1280-96. [PMID: 18951773 DOI: 10.1016/j.mycres.2008.04.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 04/02/2008] [Accepted: 04/04/2008] [Indexed: 10/22/2022]
Abstract
Recent collections of Microbotryum (Pucciniomycotina, Basidiomycota) specimens inhabiting anthers of different caryophyllaceous host plants were analysed using LM and electron microscopy, as well as molecular phylogenetic analyses using rDNA (ITS and LSU) sequences. The phylogenetic relationships of caryophyllaceous anther parasites are discussed. Three new species, Microbotryum adenopetalae, M. minuartiae, and M. silenes-acaulis, are described based on morphological, ecological, and molecular characteristics. New host plants are reported for Microbotryum dianthorum (Dianthus jacquemontii and Petrorhagia saxifraga) and M. lychnidis-dioicae (Cucubalus baccifer and Silene zawadskii). For Microbotryum violaceum, a neotype is selected.
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Affiliation(s)
- Matthias Lutz
- Lehrstuhl für Spezielle Botanik und Mykologie, Botanisches Institut, Universität Tübingen, Tübingen, Germany.
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Genetic structure of the poplar rust fungus Melampsora larici-populina: evidence for isolation by distance in Europe and recent founder effects overseas. INFECTION GENETICS AND EVOLUTION 2008; 8:577-87. [PMID: 18499532 DOI: 10.1016/j.meegid.2008.04.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2007] [Revised: 04/09/2008] [Accepted: 04/11/2008] [Indexed: 11/21/2022]
Abstract
Dispersal has a great impact on the genetic structure of populations, but remains difficult to estimate by direct measures. In particular, gradual and stochastic dispersal are often difficult to assess and to distinguish, although they have different evolutionary consequences. Plant pathogens, especially rust fungi, are suspected to display both dispersal modes, though on different spatial scales. In this study, we inferred dispersal capacities of the poplar rust fungus Melampsora larici-populina by examining the genetic diversity and structure of 13 populations from eight European and two overseas countries in the Northern hemisphere. M. larici-populina was sampled from both cultivated hybrid poplars and on the wild host, Populus nigra. The populations were analyzed with 11 microsatellite and 8 virulence markers. Although isolates displayed different virulence profiles according to the host plant, neutral markers revealed little population differentiation with respect to the type of host. This suggests an absence of reproductive isolation between populations sampled from cultivated and wild poplars. Conversely, studying the relationship between geographic and genetic structure allowed us to distinguish between isolation by distance (IBD) patterns and long distance dispersal (LDD) events. The European populations exhibited a significant IBD pattern, suggesting a regular and gradual dispersal of the pathogen over this spatial scale. Nonetheless, the genetic differentiation between these populations was low, suggesting an important gene flow on a continental scale. The two overseas populations from Iceland and Canada were shown to result from rare LDD events, and exhibited signatures of strong founder effects. Furthermore, the high genetic differentiation between both populations suggested that these two recent introductions were independent. This study illustrated how the proper use of population genetics methods can enable contrasted dispersal modes to be revealed.
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Mating system of the anther smut fungus Microbotryum violaceum: selfing under heterothallism. EUKARYOTIC CELL 2008; 7:765-75. [PMID: 18281603 DOI: 10.1128/ec.00440-07] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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44
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Evidence of recombination in mixed-mating-type and alpha-only populations of Cryptococcus gattii sourced from single eucalyptus tree hollows. EUKARYOTIC CELL 2008; 7:727-34. [PMID: 18281600 DOI: 10.1128/ec.00020-08] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Disease caused by the pathogenic yeast Cryptococcus gattii begins with the inhalation of an infectious propagule. As C. gattii is heavily encapsulated, this propagule is most likely to be a basidiospore. However, most C. gattii strains are infertile in laboratory crosses, and population studies indicate that recombination and dispersal are very restricted. In addition, strains of the alpha mating type predominate, which would not be expected in a mating population. C. gattii comprises four genetically distinct molecular genotypes, designated VGI to VGIV. C. gattii molecular type VGI has a strong association with Eucalyptus camaldulensis and can be found in high numbers in E. camaldulensis hollows. Previous work on isolates obtained from E. camaldulensis suggested that environmental populations of C. gattii are highly fragmented, have limited ability to disperse, and are confined to individual tree hollows. In the current study, we examined large numbers of isolates from three separate hollows for evidence of recombination. In two hollows, the alpha and a mating types were present in approximately equal numbers. The third hollow had alpha cells only and was from a region where a isolates have never been found. Statistical analysis of multilocus genotypes revealed recombining subpopulations in the three Eucalyptus hollows. Recombination was equally present in the alpha-a and alpha-only populations. This is consistent with recent studies that have found evidence suggestive of alpha-alpha mating in C. gattii and Cryptococcus neoformans and raises the possibility this may be a widespread phenomenon, allowing these fungi to recombine despite a paucity of a mating partners.
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Fournier E, Giraud T. Sympatric genetic differentiation of a generalist pathogenic fungus, Botrytis cinerea, on two different host plants, grapevine and bramble. J Evol Biol 2007; 21:122-132. [PMID: 18028352 DOI: 10.1111/j.1420-9101.2007.01462.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prime candidates for sympatric ecological divergence include parasites that differentiate via host shifts, because different host species exert strong disruptive selection and because both hosts and parasites are continually co-evolving. Sympatric divergence may be fostered even more strongly in phytopathogenic fungi, in particular those where sex must occur on the host, which allows adaptation alone to restrict gene flow between populations developing on different hosts. We sampled populations of Botrytis cinerea, a generalist ascomycete fungus, on sympatric grapes and brambles in six regions in France. Microsatellite data were analyzed using standard population genetics, a population graph analysis and a Bayesian approach. In addition to confirming that B. cinerea reproduces sexually, our results showed that the fungal populations on the two hosts were significantly differentiated, indicating restricted gene flow, even in sympatry. In contrast, only weak geographical differentiation could be detected. These results support the possibility of sympatric divergence associated with host use in generalist parasites.
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Affiliation(s)
- E Fournier
- INRA Centre de Versailles, UMR 1290 Bioger-CPP, Versailles cedex, FranceEcologie, Systématique et Evolution, UMR 8079 CNRS-UPS-ENGREF, Université Paris-Sud, Orsay, France
| | - T Giraud
- INRA Centre de Versailles, UMR 1290 Bioger-CPP, Versailles cedex, FranceEcologie, Systématique et Evolution, UMR 8079 CNRS-UPS-ENGREF, Université Paris-Sud, Orsay, France
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Abstract
Many agricultural landscapes are characterized by a high degree of heterogeneity and fragmentation. Landscape ecology focuses on the influence of habitat heterogeneity in space and time on ecological processes. Landscape epidemiology aims at applying concepts and approaches originating from landscape ecology to the study of pathogen dynamics at the landscape scale. However, despite the strong influence that the landscape properties may have on the spread of plant diseases, landscape epidemiology has still received little attention from plant pathologists. Some recent methodological and technological progress provides new and powerful tools to describe and analyse the spatial patterns of host-pathogen interactions. Here, we review some important topics in plant pathology that may benefit from a landscape perspective. These include the influence of: landscape composition on the global inoculum pressure; landscape heterogeneity on pathogen dynamics; landscape structure on pathogen dispersal; and landscape properties on the emergence of pathogens and on their evolution.
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Affiliation(s)
- Manuel Plantegenest
- UMR INRA/Agrocampus Rennes 1099 [BIO3P], 65, rue de Saint-Brieuc, CS 84215, 35042 Rennes, France.
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López-Villavicencio M, Jonot O, Coantic A, Hood ME, Enjalbert J, Giraud T. Multiple infections by the anther smut pathogen are frequent and involve related strains. PLoS Pathog 2007; 3:e176. [PMID: 18020704 PMCID: PMC2077905 DOI: 10.1371/journal.ppat.0030176] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Accepted: 10/03/2007] [Indexed: 11/18/2022] Open
Abstract
Population models of host-parasite interactions predict that when different parasite genotypes compete within a host for limited resources, those that exploit the host faster will be selected, leading to an increase in parasite virulence. When parasites sharing a host are related, however, kin selection should lead to more cooperative host exploitation that may involve slower rates of parasite reproduction. Despite their potential importance, studies that assess the prevalence of multiple genotype infections in natural populations remain rare, and studies quantifying the relatedness of parasites occurring together as natural multiple infections are particularly scarce. We investigated multiple infections in natural populations of the systemic fungal plant parasite Microbotryum violaceum, the anther smut of Caryophyllaceae, on its host, Silene latifolia. We found that multiple infections can be extremely frequent, with different fungal genotypes found in different stems of single plants. Multiple infections involved parasite genotypes more closely related than would be expected based upon their genetic diversity or due to spatial substructuring within the parasite populations. Together with previous sequential inoculation experiments, our results suggest that M. violaceum actively excludes divergent competitors while tolerating closely related genotypes. Such an exclusion mechanism might explain why multiple infections were less frequent in populations with the highest genetic diversity, which is at odds with intuitive expectations. Thus, these results demonstrate that genetic diversity can influence the prevalence of multiple infections in nature, which will have important consequences for their optimal levels of virulence. Measuring the occurrence of multiple infections and the relatedness among parasites within hosts in natural populations may be important for understanding the evolutionary dynamics of disease, the consequences of vaccine use, and forces driving the population genetic structure of parasites.
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Affiliation(s)
| | - Odile Jonot
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
| | - Amélie Coantic
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
| | - Michael E Hood
- Department of Biology, Amherst College, Amherst, Massachusetts, United States of America
| | - Jérôme Enjalbert
- Laboratoire de Pathologie Végétale, INRA BIOGER, Thiverval Grignon, France
| | - Tatiana Giraud
- Univ Paris-Sud, Laboratoire Ecologie, Systématique et Evolution, Orsay, France
- CNRS, UMR 8079, Orsay, France
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48
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Tellier A, Villaréal LMMA, Giraud T. Antagonistic pleiotropy may help population-level selection in maintaining genetic polymorphism for transmission rate in a model phytopathogenic fungus. Heredity (Edinb) 2006; 98:45-52. [PMID: 17021614 DOI: 10.1038/sj.hdy.6800902] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
It has been shown theoretically that the conditions for the maintenance of polymorphism at pleiotropic loci with antagonistic effects on fitness components are rather restrictive. Here, we use a metapopulation model to investigate whether antagonistic pleiotropy could help maintain polymorphism involving common deleterious alleles in the phytopathogenic fungus Microbotryum violaceum. This fungus causes anther smut disease of the Caryophyllaceae. A previous model has shown that the sex-linked deleterious alleles can be maintained under a metapopulation structure, when intra-tetrad selfing (mating between products of the same meiosis) is high, due to founder effects and selection at the population level. Here, we add two types of pleiotropic advantages to the metapopulation model. A competitive advantage for strains carrying the sex-linked deleterious alleles did not facilitate their maintenance because competitive situations were too rare. In contrast, higher spore production did facilitate the maintenance of the deleterious alleles at low intra-tetrad mating rates and with a large advantage for spore production. These results show that antagonistic pleiotropy may promote the persistence of genetic variation, in combination with other selective forces.
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Affiliation(s)
- A Tellier
- Ecologie, Systématique et Evolution, UMR 8079 CNRS-UPS, Université Paris-Sud, Orsay, France
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49
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Raboin LM, Selvi A, Oliveira KM, Paulet F, Calatayud C, Zapater MF, Brottier P, Luzaran R, Garsmeur O, Carlier J, D'Hont A. Evidence for the dispersal of a unique lineage from Asia to America and Africa in the sugarcane fungal pathogen Ustilago scitaminea. Fungal Genet Biol 2006; 44:64-76. [PMID: 16979360 DOI: 10.1016/j.fgb.2006.07.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Revised: 07/07/2006] [Accepted: 07/17/2006] [Indexed: 10/24/2022]
Abstract
The basidiomycete Ustilago scitaminea Sydow, which causes sugarcane smut disease, has been spreading throughout Africa and America since the 1940s. The genetic diversity and structure of different populations of this fungus worldwide was investigated using microsatellites. A total of 142 single-teliospore were isolated from 77 distinct whips (sori) collected in 15 countries worldwide. Mycelium culture derived from on generation of selfing of these single teliospores were analysed for their polymorphisms at 17 microsatellite loci. All these strains but one were homozygous at all loci, indicating that selfing is likely the predominant reproductive mode of U. scitaminea. The genetic diversity of either American or African U. scitaminea populations was found to be extremely low and all strains belong to a single lineage. This lineage was also found in some populations of Asia, where most U. scitaminea genetic diversity was detected, suggesting that this fungal species originated from this region. The strong founder effect observed in U. scitaminea African and American populations suggests that the fungus migrated from Asia to other continents on rare occasions through movement of infected plant material.
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Affiliation(s)
- Louis-Marie Raboin
- CIRAD (Centre de coopération internationale en recherche agronomique pour le développement), UMR PVBMT, Pôle de Protection des Plantes, Ligne Paradis, 97410 Saint-Pierre, Réunion, France
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50
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Giraud T, Jonot O, Shykoff JA. Common sex-linked deleterious alleles in a plant parasitic fungus alter infection success but show no pleiotropic advantage. J Evol Biol 2006; 19:970-80. [PMID: 16674592 DOI: 10.1111/j.1420-9101.2005.01032.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Microbotryum violaceum is a fungus that causes the sterilizing anther smut disease in Caryophyllaceae. Its diploid teliospores normally produce equal proportions of haploid sporidia of its two mating types. However natural populations contain high frequencies of individuals producing sporidia of only one mating type ('biased strains'). This mating type-ratio bias is caused by deleterious alleles at haploid phase ('haplo-lethals') linked to the mating type locus that can be transmitted only by intra-tetrad selfing. We used experimental inoculations to test some of the hypotheses proposed to explain the maintenance of haplo-lethals. We found a disadvantage of biased strains in infection ability and high intra-tetrad mating rates. Biased strains had no higher competitive ability nor shorter latency and their higher spore production per flower appeared insufficient to compensate their disadvantages. These findings were only consistent with the hypothesis that haplo-lethals are maintained under a metapopulation structure because of high intra-tetrad selfing rates, founder effects and selection at the population level.
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Affiliation(s)
- T Giraud
- Ecologie, Systématique et Evolution, UMR 8079 Université Paris Sud, Université Paris-Sud, Orsay cedex, France.
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