251
|
Molecular phylogenetic analyses reveal three new Ceratocystis species and provide evidence for geographic differentiation of the genus in Africa. Mycol Prog 2013. [DOI: 10.1007/s11557-013-0907-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
252
|
Leroy T, Lemaire C, Dunemann F, Le Cam B. The genetic structure of a Venturia inaequalis population in a heterogeneous host population composed of different Malus species. BMC Evol Biol 2013; 13:64. [PMID: 23497223 PMCID: PMC3626921 DOI: 10.1186/1471-2148-13-64] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 02/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Adaptation, which induces differentiation between populations in relation to environmental conditions, can initiate divergence. The balance between gene flow and selection determines the maintenance of such a structure in sympatry. Studying these two antagonistic forces in plant pathogens is made possible because of the high ability of pathogens to disperse and of the strong selective pressures exerted by their hosts. In this article, we analysed the genetic structure of the population of the apple scab fungus, Venturia inaequalis, in a heterogeneous environment composed of various Malus species. Inferences were drawn from microsatellite and AFLP data obtained from 114 strains sampled in a single orchard on nine different Malus species to determine the forces that shape the genetic structure of the pathogen. RESULTS Using clustering methods, we first identified two specialist subpopulations: (i) a virulent subpopulation sampled on Malus trees carrying the Rvi6 resistance gene; and (ii) a subpopulation infecting only Malus trees that did not carry this resistance gene. A genome scan of loci on these two subpopulations did not detect any locus under selection. Additionally, we did not detect any other particular substructure linked to different hosts. However, an isolation-by-distance (IBD) pattern at the orchard scale revealed free gene flow within each subpopulation. CONCLUSIONS Our work shows a rare example of a very strong effect of a resistance gene on pathogen populations. Despite the high diversity of Malus hosts, the presence of Rvi6 seems sufficient to explain the observed genetic structure. Moreover, detection of an IBD pattern at the orchard scale revealed a very low average dispersal distance that is particularly significant for epidemiologists and landscape managers for the design of scab control strategies.
Collapse
Affiliation(s)
- Thibault Leroy
- Université d’Angers, IRHS, PRES UNAM, SFR QUASAV, Boulevard Lavoisier, Angers, 49045 France
- INRA, IRHS, PRES UNAM, SFR QUASAV, Rue Georges Morel, Beaucouzé, 49071 France
- Agrocampus Ouest, IRHS, PRES UNAM, SFR QUASAV, Rue Le Nôtre, F-49045 Angers, France
| | - Christophe Lemaire
- Université d’Angers, IRHS, PRES UNAM, SFR QUASAV, Boulevard Lavoisier, Angers, 49045 France
- INRA, IRHS, PRES UNAM, SFR QUASAV, Rue Georges Morel, Beaucouzé, 49071 France
- Agrocampus Ouest, IRHS, PRES UNAM, SFR QUASAV, Rue Le Nôtre, F-49045 Angers, France
| | - Frank Dunemann
- Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Breeding Research on Horticultural and Fruit Crops, Erwin-Baur-Strasse 27, 06484, Quedlinburg, Germany
| | - Bruno Le Cam
- Université d’Angers, IRHS, PRES UNAM, SFR QUASAV, Boulevard Lavoisier, Angers, 49045 France
- INRA, IRHS, PRES UNAM, SFR QUASAV, Rue Georges Morel, Beaucouzé, 49071 France
- Agrocampus Ouest, IRHS, PRES UNAM, SFR QUASAV, Rue Le Nôtre, F-49045 Angers, France
| |
Collapse
|
253
|
Mhedbi-Hajri N, Hajri A, Boureau T, Darrasse A, Durand K, Brin C, Saux MFL, Manceau C, Poussier S, Pruvost O, Lemaire C, Jacques MA. Evolutionary history of the plant pathogenic bacterium Xanthomonas axonopodis. PLoS One 2013; 8:e58474. [PMID: 23505513 PMCID: PMC3591321 DOI: 10.1371/journal.pone.0058474] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 02/05/2013] [Indexed: 01/02/2023] Open
Abstract
Deciphering mechanisms shaping bacterial diversity should help to build tools to predict the emergence of infectious diseases. Xanthomonads are plant pathogenic bacteria found worldwide. Xanthomonas axonopodis is a genetically heterogeneous species clustering, into six groups, strains that are collectively pathogenic on a large number of plants. However, each strain displays a narrow host range. We address the question of the nature of the evolutionary processes--geographical and ecological speciation--that shaped this diversity. We assembled a large collection of X. axonopodis strains that were isolated over a long period, over continents, and from various hosts. Based on the sequence analysis of seven housekeeping genes, we found that recombination occurred as frequently as point mutation in the evolutionary history of X. axonopodis. However, the impact of recombination was about three times greater than the impact of mutation on the diversity observed in the whole dataset. We then reconstructed the clonal genealogy of the strains using coalescent and genealogy approaches and we studied the diversification of the pathogen using a model of divergence with migration. The suggested scenario involves a first step of generalist diversification that spanned over the last 25,000 years. A second step of ecology-driven specialization occurred during the past two centuries. Eventually, secondary contacts between host-specialized strains probably occurred as a result of agricultural development and intensification, allowing genetic exchanges of virulence-associated genes. These transfers may have favored the emergence of novel pathotypes. Finally, we argue that the largest ecological entity within X. axonopodis is the pathovar.
Collapse
Affiliation(s)
- Nadia Mhedbi-Hajri
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Ahmed Hajri
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Tristan Boureau
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Armelle Darrasse
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Karine Durand
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Chrystelle Brin
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Marion Fischer-Le Saux
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Charles Manceau
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Stéphane Poussier
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | | | - Christophe Lemaire
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| | - Marie-Agnès Jacques
- INRA, UMR1345 Institut de Recherche en Horticulture et Semences, Beaucouzé, France
- Université d’Angers, UMR1345 Institut de Recherche en Horticulture et Semences, SFR4207 QUASAV, PRES L’UNAM, Angers, France
- AgroCampus-Ouest, UMR1345 Institut de Recherche en Horticulture et Semences, Angers, France
| |
Collapse
|
254
|
Troch V, Audenaert K, Vanheule A, Bekaert B, Höfte M, Haesaert G. Evaluation of Resistance to Powdery Mildew in Triticale Seedlings and Adult Plants. PLANT DISEASE 2013; 97:410-417. [PMID: 30722401 DOI: 10.1094/pdis-02-12-0161-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Triticale (×Triticosecale) is the intergeneric hybrid between the female parent wheat and the male parent rye. With the expansion of the triticale growing area, powdery mildew emerged on this new host and has become a significant disease on triticale. Recent research demonstrated that this "new" powdery mildew on triticale has emerged through a host range expansion of powdery mildew of wheat. Moreover, this expansion occurred recently and multiple times at different locations in Europe. An effective and environmentally sensitive approach to controlling powdery mildew involves breeding crop plants for resistance. The main goal of this study was to identify the presence of powdery mildew resistance in commercial triticale cultivars. First, the avirulence (AVR) genes and gene complexity carried by this new powdery mildew population on triticale were characterized. Virulence was identified for all the resistance genes evaluated in the present study, and virulence frequencies higher than 50% were recorded on the genes Pm3f, Pm5b, Pm6, Pm7, Pm8, and Pm17. Using molecular markers, the presence of resistance genes Pm3f and Pm17 was identified in certain triticale cultivars. The triticale cultivars were also evaluated for the presence of quantitative resistance at adult plant growth stages in a 2-year field experiment. Despite the high disease pressure, cultivars highly resistant at the adult-plant growth stages were identified. Because 'Grenado' also showed effective race-specific resistance, this cultivar could be of high value for breeding for durable resistance to powdery mildew. Altogether, this study reveals valuable information on the presence of powdery mildew resistance in commercial triticale cultivars, which can be used in breeding programs in triticale. Additionally, this study underscores the need to broaden the base of powdery mildew resistance in triticale through introgression and deployment of new sources of mildew resistance, including quantitative resistance.
Collapse
Affiliation(s)
- V Troch
- Faculty of Applied Bioscience Engineering, University College Ghent (Ghent University Association), and Department of Crop Protection, Laboratory of Phytopathology, Ghent University
| | - K Audenaert
- Faculty of Applied Bioscience Engineering, University College Ghent (Ghent University Association), and Department of Crop Protection, Laboratory of Phytopathology, Ghent University
| | - A Vanheule
- Faculty of Applied Bioscience Engineering, University College Ghent (Ghent University Association), and Department of Crop Protection, Laboratory of Phytopathology, Ghent University
| | - B Bekaert
- Faculty of Applied Bioscience Engineering, University College Ghent (Ghent University Association)
| | - M Höfte
- Department of Crop Protection, Laboratory of Phytopathology
| | - G Haesaert
- Faculty of Applied Bioscience Engineering, University College Ghent (Ghent University Association), and Department of Crop Protection, Laboratory of Phytopathology, Ghent University, BE-9000 Ghent, Belgium
| |
Collapse
|
255
|
Rodelo-Urrego M, Pagán I, González-Jara P, Betancourt M, Moreno-Letelier A, Ayllón MA, Fraile A, Piñero D, García-Arenal F. Landscape heterogeneity shapes host-parasite interactions and results in apparent plant-virus codivergence. Mol Ecol 2013; 22:2325-40. [DOI: 10.1111/mec.12232] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 12/12/2012] [Accepted: 12/20/2012] [Indexed: 12/22/2022]
Affiliation(s)
- M. Rodelo-Urrego
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - I. Pagán
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - P. González-Jara
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - M. Betancourt
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - A. Moreno-Letelier
- Departamento de Ecología Evolutiva; Instituto de Ecología; Universidad Nacional Autónoma de México; Apartado Postal 70-275 México DF 04510 México
| | - M. A. Ayllón
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - A. Fraile
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| | - D. Piñero
- Departamento de Ecología Evolutiva; Instituto de Ecología; Universidad Nacional Autónoma de México; Apartado Postal 70-275 México DF 04510 México
| | - F. García-Arenal
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos; Campus de Montegancedo; Universidad Politécnica de Madrid; Pozuelo de Alarcón Madrid 28223 Spain
| |
Collapse
|
256
|
Boussalah N, Touzani R, Souna F, Himri I, Bouakka M, Hakkou A, Ghalem S, Kadiri SE. Antifungal activities of amino acid ester functional pyrazolyl compounds against Fusarium oxysporum f.sp. albedinis and Saccharomyces cerevisiae yeast. JOURNAL OF SAUDI CHEMICAL SOCIETY 2013. [DOI: 10.1016/j.jscs.2011.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
257
|
Morris CE, Monteil CL, Berge O. The life history of Pseudomonas syringae: linking agriculture to earth system processes. ANNUAL REVIEW OF PHYTOPATHOLOGY 2013; 51:85-104. [PMID: 23663005 DOI: 10.1146/annurev-phyto-082712-102402] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The description of the ecology of Pseudomonas syringae is moving away from that of a ubiquitous epiphytic plant pathogen to one of a multifaceted bacterium sans frontières in fresh water and other ecosystems linked to the water cycle. Discovery of the aquatic facet of its ecology has led to a vision of its life history that integrates spatial and temporal scales spanning billions of years and traversing catchment basins, continents, and the planet and that confronts the implication of roles that are potentially conflicting for agriculture (as a plant pathogen and as an actor in processes leading to rain and snowfall). This new ecological perspective has also yielded insight into epidemiological phenomena linked to disease emergence. Overall, it sets the stage for the integration of more comprehensive contexts of ecology and evolutionary history into comparative genomic analyses to elucidate how P. syringae subverts the attack and defense responses of the cohabitants of the diverse environments it occupies.
Collapse
Affiliation(s)
- Cindy E Morris
- INRA, UR0407 Pathologie Végétale, 84143 Montfavet Cedex, France.
| | | | | |
Collapse
|
258
|
Rouxel M, Mestre P, Comont G, Lehman BL, Schilder A, Delmotte F. Phylogenetic and experimental evidence for host-specialized cryptic species in a biotrophic oomycete. THE NEW PHYTOLOGIST 2013; 197:251-263. [PMID: 23153246 DOI: 10.1111/nph.12016] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Accepted: 09/22/2012] [Indexed: 05/09/2023]
Abstract
Assortative mating resulting from host plant specialization has been proposed to facilitate rapid ecological divergence in biotrophic plant pathogens. Downy mildews, a major group of biotrophic oomycetes, are prime candidates for testing speciation by host plant specialization. Here, we combined a phylogenetic and morphological approach with cross-pathogenicity tests to investigate host plant specialization and host range expansion in grapevine downy mildew. This destructive disease is caused by Plasmopara viticola, an oomycete endemic to North America on wild species and cultivated grapevines. Multiple genealogies and sporangia morphology provide evidence that P. viticola is a complex of four cryptic species, each associated with different host plants. Cross-inoculation experiments showed complete host plant specialization on Parthenocissus quinquefolia and on Vitis riparia, whereas cryptic species found on V. aestivalis, V. labrusca and V. vinifera were revealed to be less specific. We reconstructed the recent host range expansion of P. viticola from wild to cultivated grapevines, and showed that it was accompanied by an increase in aggressiveness of the pathogen. This case study on grapevine downy mildew illustrates how biotrophic plant pathogens can diversify by host plant specialization and emerge in agrosystems by shifting to cultivated hosts. These results might have important implications for viticulture, including breeding for resistance and disease management.
Collapse
Affiliation(s)
- Mélanie Rouxel
- INRA, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
- Université de Bordeaux, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
| | - Pere Mestre
- INRA, UMR1131 Santé de la Vigne et Qualité du vin, F-68000, Colmar, France
- Université de Strasbourg, UMR1131 Santé de la Vigne et Qualité du vin, F-68000, Colmar, France
| | - Gwenaelle Comont
- INRA, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
- Université de Bordeaux, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
| | - Brian L Lehman
- Department of Plant Pathology, Michigan State University, East Lansing, MI, 48824, USA
| | - Annemiek Schilder
- Department of Plant Pathology, Michigan State University, East Lansing, MI, 48824, USA
| | - François Delmotte
- INRA, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
- Université de Bordeaux, ISVV, UMR1065 Santé et Agroécologie du Vignoble, F-33883, Villenave d'Ornon, France
| |
Collapse
|
259
|
Manning VA, Pandelova I, Dhillon B, Wilhelm LJ, Goodwin SB, Berlin AM, Figueroa M, Freitag M, Hane JK, Henrissat B, Holman WH, Kodira CD, Martin J, Oliver RP, Robbertse B, Schackwitz W, Schwartz DC, Spatafora JW, Turgeon BG, Yandava C, Young S, Zhou S, Zeng Q, Grigoriev IV, Ma LJ, Ciuffetti LM. Comparative genomics of a plant-pathogenic fungus, Pyrenophora tritici-repentis, reveals transduplication and the impact of repeat elements on pathogenicity and population divergence. G3 (BETHESDA, MD.) 2013; 3:41-63. [PMID: 23316438 PMCID: PMC3538342 DOI: 10.1534/g3.112.004044] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 11/02/2012] [Indexed: 12/31/2022]
Abstract
Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi. Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes.
Collapse
Affiliation(s)
- Viola A. Manning
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Iovanna Pandelova
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Braham Dhillon
- Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4
| | - Larry J. Wilhelm
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- Carbone/Ferguson Laboratories, Division of Neuroscience, Oregon National Primate Research Center (ONPRC), Beaverton, Oregon 97006
| | - Stephen B. Goodwin
- USDA–Agricultural Research Service, Purdue University, West Lafayette, Indiana 47907
| | | | - Melania Figueroa
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- USDA-Agricultural Research Service, Forage Seed and Cereal Research Unit, Oregon State University, Corvallis, Oregon 97331
| | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331
| | - James K. Hane
- Commonwealth Scientific and Industrial Research Organization−Plant Industry, Centre for Environment and Life Sciences, Floreat, Western Australia 6014, Australia
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Centre National de la Recherche Scientifique, 13288 Marseille cedex 9, France
| | - Wade H. Holman
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - Chinnappa D. Kodira
- The Broad Institute, Cambridge, Massachusetts 02142
- Roche 454, Branford, Connecticut 06405
| | - Joel Martin
- US DOE Joint Genome Institute, Walnut Creek, California 94598
| | - Richard P. Oliver
- Australian Centre for Necrotrophic Fungal Pathogens, Department of Environment and Agriculture, Curtin University, Bentley, Western Australia 6845, Australia
| | - Barbara Robbertse
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Centre National de la Recherche Scientifique, 13288 Marseille cedex 9, France
| | | | - David C. Schwartz
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, UW Biotechnology Center, University of Wisconsin–Madison, Madison, Wisconsin 53706
| | - Joseph W. Spatafora
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
| | - B. Gillian Turgeon
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York 14850
| | | | - Sarah Young
- The Broad Institute, Cambridge, Massachusetts 02142
| | - Shiguo Zhou
- Laboratory for Molecular and Computational Genomics, Department of Chemistry, Laboratory of Genetics, UW Biotechnology Center, University of Wisconsin–Madison, Madison, Wisconsin 53706
| | | | | | - Li-Jun Ma
- The Broad Institute, Cambridge, Massachusetts 02142
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Massachusetts 01003
| | - Lynda M. Ciuffetti
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon 97331
- Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon 97331
| |
Collapse
|
260
|
Martin MD, Cappellini E, Samaniego JA, Zepeda ML, Campos PF, Seguin-Orlando A, Wales N, Orlando L, Ho SYW, Dietrich FS, Mieczkowski PA, Heitman J, Willerslev E, Krogh A, Ristaino JB, Gilbert MTP. Reconstructing genome evolution in historic samples of the Irish potato famine pathogen. Nat Commun 2013; 4:2172. [PMID: 23863894 PMCID: PMC3759036 DOI: 10.1038/ncomms3172] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 06/20/2013] [Indexed: 11/15/2022] Open
Abstract
Responsible for the Irish potato famine of 1845-49, the oomycete pathogen Phytophthora infestans caused persistent, devastating outbreaks of potato late blight across Europe in the 19th century. Despite continued interest in the history and spread of the pathogen, the genome of the famine-era strain remains entirely unknown. Here we characterize temporal genomic changes in introduced P. infestans. We shotgun sequence five 19th-century European strains from archival herbarium samples--including the oldest known European specimen, collected in 1845 from the first reported source of introduction. We then compare their genomes to those of extant isolates. We report multiple distinct genotypes in historical Europe and a suite of infection-related genes different from modern strains. At virulence-related loci, several now-ubiquitous genotypes were absent from the historical gene pool. At least one of these genotypes encodes a virulent phenotype in modern strains, which helps explain the 20th century's episodic replacements of European P. infestans lineages.
Collapse
Affiliation(s)
- Michael D Martin
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
261
|
Characterization and inheritance of resistance to stripe rust in the wheat line Guinong775. YI CHUAN = HEREDITAS 2012; 34:1607-13. [DOI: 10.3724/sp.j.1005.2012.01607] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
262
|
Le May C, Guibert M, Leclerc A, Andrivon D, Tivoli B. A single, plastic population of Mycosphaerella pinodes causes ascochyta blight on winter and spring peas (Pisum sativum) in France. Appl Environ Microbiol 2012; 78:8431-40. [PMID: 23023742 PMCID: PMC3497390 DOI: 10.1128/aem.01543-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 09/19/2012] [Indexed: 11/20/2022] Open
Abstract
Plant diseases are caused by pathogen populations continuously subjected to evolutionary forces (genetic flow, selection, and recombination). Ascochyta blight, caused by Mycosphaerella pinodes, is one of the most damaging necrotrophic pathogens of field peas worldwide. In France, both winter and spring peas are cultivated. Although these crops overlap by about 4 months (March to June), primary Ascochyta blight infections are not synchronous on the two crops. This suggests that the disease could be due to two different M. pinodes populations, specialized on either winter or spring pea. To test this hypothesis, 144 pathogen isolates were collected in the field during the winter and spring growing seasons in Rennes (western France), and all the isolates were genotyped using amplified fragment length polymorphism (AFLP) markers. Furthermore, the pathogenicities of 33 isolates randomly chosen within the collection were tested on four pea genotypes (2 winter and 2 spring types) grown under three climatic regimes, simulating winter, late winter, and spring conditions. M. pinodes isolates from winter and spring peas were genetically polymorphic but not differentiated according to the type of cultivars. Isolates from winter pea were more pathogenic than isolates from spring pea on hosts raised under winter conditions, while isolates from spring pea were more pathogenic than those from winter pea on plants raised under spring conditions. These results show that disease developed on winter and spring peas was initiated by a single population of M. pinodes whose pathogenicity is a plastic trait modulated by the physiological status of the host plant.
Collapse
|
263
|
McKinney L, Thomsen I, Kjær E, Bengtsson S, Nielsen L. Rapid invasion by an aggressive pathogenic fungus (Hymenoscyphus pseudoalbidus) replaces a native decomposer (Hymenoscyphus albidus): a case of local cryptic extinction? FUNGAL ECOL 2012. [DOI: 10.1016/j.funeco.2012.05.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
264
|
Lê Van A, Gladieux P, Lemaire C, Cornille A, Giraud T, Durel CE, Caffier V, Le Cam B. Evolution of pathogenicity traits in the apple scab fungal pathogen in response to the domestication of its host. Evol Appl 2012; 5:694-704. [PMID: 23144656 PMCID: PMC3492895 DOI: 10.1111/j.1752-4571.2012.00246.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Accepted: 01/09/2012] [Indexed: 02/04/2023] Open
Abstract
Understanding how pathogens emerge is essential to bring disease-causing agents under durable human control. Here, we used cross-pathogenicity tests to investigate the changes in life-history traits of the fungal pathogen Venturia inaequalis associated with host-tracking during the domestication of apple and subsequent host-range expansion on the wild European crabapple (Malus sylvestris). Pathogenicity of 40 isolates collected in wild and domesticated ecosystems was assessed on the domesticated apple, its Central Asian main progenitor (M. sieversii) and M. sylvestris. Isolates from wild habitats in the centre of origin of the crop were not pathogenic on the domesticated apple and less aggressive than other isolates on their host of origin. Isolates from the agro-ecosystem in Central Asia infected a higher proportion of plants with higher aggressiveness, on both the domesticated host and its progenitor. Isolates from the European crabapple were still able to cause disease on other species but were less aggressive and less frequently virulent on these hosts than their endemic populations. Our results suggest that the domestication of apple was associated with the acquisition of virulence in the pathogen following host-tracking. The spread of the disease in the agro-ecosystem would also have been accompanied by an increase in overall pathogenicity.
Collapse
Affiliation(s)
- Amandine Lê Van
- INRA, UMR1345, IRHS (INRA, Agrocampus-Ouest, Université d'Angers) SFR QUASAV, Beaucouzé, France
| | | | | | | | | | | | | | | |
Collapse
|
265
|
Plant-pathogen interactions: disease resistance in modern agriculture. Trends Genet 2012; 29:233-40. [PMID: 23153595 DOI: 10.1016/j.tig.2012.10.011] [Citation(s) in RCA: 196] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/19/2012] [Accepted: 10/08/2012] [Indexed: 11/21/2022]
Abstract
The growing human population will require a significant increase in agricultural production. This challenge is made more difficult by the fact that changes in the climatic and environmental conditions under which crops are grown have resulted in the appearance of new diseases, whereas genetic changes within the pathogen have resulted in the loss of previously effective sources of resistance. To help meet this challenge, advanced genetic and statistical methods of analysis have been used to identify new resistance genes through global screens, and studies of plant-pathogen interactions have been undertaken to uncover the mechanisms by which disease resistance is achieved. The informed deployment of major, race-specific and partial, race-nonspecific resistance, either by conventional breeding or transgenic approaches, will enable the production of crop varieties with effective resistance without impacting on other agronomically important crop traits. Here, we review these recent advances and progress towards the ultimate goal of developing disease-resistant crops.
Collapse
|
266
|
Daverdin G, Rouxel T, Gout L, Aubertot JN, Fudal I, Meyer M, Parlange F, Carpezat J, Balesdent MH. Genome structure and reproductive behaviour influence the evolutionary potential of a fungal phytopathogen. PLoS Pathog 2012; 8:e1003020. [PMID: 23144620 PMCID: PMC3493481 DOI: 10.1371/journal.ppat.1003020] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2012] [Accepted: 09/24/2012] [Indexed: 11/21/2022] Open
Abstract
Modern agriculture favours the selection and spread of novel plant diseases. Furthermore, crop genetic resistance against pathogens is often rendered ineffective within a few years of its commercial deployment. Leptosphaeria maculans, the cause of phoma stem canker of oilseed rape, develops gene-for-gene interactions with its host plant, and has a high evolutionary potential to render ineffective novel sources of resistance in crops. Here, we established a four-year field experiment to monitor the evolution of populations confronted with the newly released Rlm7 resistance and to investigate the nature of the mutations responsible for virulence against Rlm7. A total of 2551 fungal isolates were collected from experimental crops of a Rlm7 cultivar or a cultivar without Rlm7. All isolates were phenotyped for virulence and a subset was genotyped with neutral genetic markers. Virulent isolates were investigated for molecular events at the AvrLm4-7 locus. Whilst virulent isolates were not found in neighbouring crops, their frequency had reached 36% in the experimental field after four years. An extreme diversity of independent molecular events leading to virulence was identified in populations, with large-scale Repeat Induced Point mutations or complete deletion of AvrLm4-7 being the most frequent. Our data suggest that increased mutability of fungal genes involved in the interactions with plants is directly related to their genomic environment and reproductive system. Thus, rapid allelic diversification of avirulence genes can be generated in L. maculans populations in a single field provided that large population sizes and sexual reproduction are favoured by agricultural practices.
Collapse
Affiliation(s)
| | - Thierry Rouxel
- INRA, UR 1290 Bioger, Campus AgroParisTech, Thiverval-Grignon, France
| | - Lilian Gout
- INRA, UR 1290 Bioger, Campus AgroParisTech, Thiverval-Grignon, France
- AgroParisTech, Campus AgroParisTech, Thiverval-Grignon, France
| | | | - Isabelle Fudal
- INRA, UR 1290 Bioger, Campus AgroParisTech, Thiverval-Grignon, France
| | - Michel Meyer
- INRA, UR 1290 Bioger, Campus AgroParisTech, Thiverval-Grignon, France
| | - Francis Parlange
- INRA, UR 1290 Bioger, Campus AgroParisTech, Thiverval-Grignon, France
| | | | | |
Collapse
|
267
|
Ahmed S, de Labrouhe DT, Delmotte F. Emerging virulence arising from hybridisation facilitated by multiple introductions of the sunflower downy mildew pathogen Plasmopara halstedii. Fungal Genet Biol 2012; 49:847-55. [DOI: 10.1016/j.fgb.2012.06.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 06/20/2012] [Accepted: 06/22/2012] [Indexed: 11/24/2022]
|
268
|
Stukenbrock EH, Bataillon T. A population genomics perspective on the emergence and adaptation of new plant pathogens in agro-ecosystems. PLoS Pathog 2012; 8:e1002893. [PMID: 23028308 PMCID: PMC3460620 DOI: 10.1371/journal.ppat.1002893] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Eva H Stukenbrock
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
| | | |
Collapse
|
269
|
Rieux A, De Lapeyre De Bellaire L, Zapater MF, Ravigne V, Carlier J. Recent range expansion and agricultural landscape heterogeneity have only minimal effect on the spatial genetic structure of the plant pathogenic fungus Mycosphaerella fijiensis. Heredity (Edinb) 2012; 110:29-38. [PMID: 22990310 DOI: 10.1038/hdy.2012.55] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Understanding how geographical and environmental features affect genetic variation at both the population and individual levels is crucial in biology, especially in the case of pathogens. However, distinguishing between these factors and the effects of historical range expansion on spatial genetic structure remains challenging. In the present study, we investigated the case of Mycosphaerella fijiensis-a plant pathogenic fungus that has recently colonized an agricultural landscape characterized by the presence of potential barriers to gene flow, including several commercial plantations in which disease control practises such as the use of fungicides are applied frequently, and low host density areas. We first genotyped 300 isolates sampled at a global scale on untreated plants in two dimensions over a 50 × 80-km area. Using two different clustering algorithms, no genetic structure was detected in the studied area, suggesting expansion of large populations and/or no influence of potential barriers. Second, we investigated the potential effect of disease control practises on M. fijiensis diversity by comparing populations sampled in commercial vs food-crop plantations. At this local scale, we detected significantly higher allelic richness inside commercial plantations compared with the surrounding food-crop plantation populations. Analysis of molecular variance indicated that 99% of the total genetic variance occurred within populations. We discuss the suggestion that high population size and/or high migration rate between populations might be responsible for the absence of any effect of disease control practises on genetic diversity and differentiation.
Collapse
Affiliation(s)
- A Rieux
- CIRAD, UMR BGPI, TA A-54K, Campus International de Baillarguet, Montpellier Cedex 5, France
| | | | | | | | | |
Collapse
|
270
|
Barrès B, Dutech C, Andrieux A, Halkett F, Frey P. Exploring the role of asexual multiplication in poplar rust epidemics: impact on diversity and genetic structure. Mol Ecol 2012; 21:4996-5008. [DOI: 10.1111/mec.12008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 07/06/2012] [Accepted: 07/15/2012] [Indexed: 11/28/2022]
|
271
|
Broders KD, Boraks A, Sanchez AM, Boland GJ. Population structure of the butternut canker fungus, Ophiognomonia clavigignenti-juglandacearum, in North American forests. Ecol Evol 2012; 2:2114-27. [PMID: 23139872 PMCID: PMC3488664 DOI: 10.1002/ece3.332] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2012] [Revised: 06/18/2012] [Accepted: 06/22/2012] [Indexed: 12/03/2022] Open
Abstract
The occurrence of multiple introduction events, or sudden emergence from a host jump, of forest pathogens may be an important factor in successful establishment in a novel environment or on a new host; however, few studies have focused on the introduction and emergence of fungal pathogens in forest ecosystems. While Ophiognomonia clavigignenti-juglandacearum (Oc-j), the butternut canker fungus, has caused range-wide mortality of butternut trees in North America since its first observation in 1967, the history of its emergence and spread across the United States and Canada remains unresolved. Using 17 single nucleotide polymorphic loci, we investigated the genetic population structure of 101 isolates of Oc-j from across North America. Clustering analysis revealed that the Oc-j population in North America is made up of three differentiated genetic clusters of isolates, and these genetic clusters were found to have a strong clonal structure. These results, in combination with the geographic distribution of the populations, suggest that Oc-j was introduced or has emerged in North America on more than one occasion, and these clonal lineages have since proliferated across much of the range of butternut. No evidence of genetic recombination was observed in the linkage analysis, and conservation of the distinct genetic clusters in regions where isolates from two or more genetic clusters are present, would indicate a very minimal or non-existent role of sexual recombination in populations of Oc-j in North America.
Collapse
Affiliation(s)
- K D Broders
- Department of Biological Sciences, University of New Hampshire 46 College Rd, Durham, New Hampshire, 03824 ; School of Environmental Sciences, University of Guelph Guelph, Ontario, Canada, N1G 2W1
| | | | | | | |
Collapse
|
272
|
Phylogenetic and population genetic analyses of Phaeosphaeria nodorum and its close relatives indicate cryptic species and an origin in the Fertile Crescent. Fungal Genet Biol 2012; 49:882-95. [PMID: 22922546 DOI: 10.1016/j.fgb.2012.08.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/25/2012] [Accepted: 08/01/2012] [Indexed: 11/22/2022]
Abstract
The origin of the fungal wheat pathogen Phaeosphaeria nodorum remains unclear despite earlier intensive global population genetic and phylogeographical studies. We sequenced 1683 bp distributed across three loci in 355 globally distributed Phaeosphaeria isolates, including 74 collected in Iran near the center of origin of wheat. We identified nine phylogenetically distinct clades, including two previously unknown species tentatively named P1 and P2 collected in Iran. Coalescent analysis indicates that P1 and P2 are sister species of P. nodorum and the other Phaeosphaeria species identified in our analysis. Two species, P. nodorum and P. avenaria f. sp. tritici 1 (Pat1), comprised ~85% of the sampled isolates, making them the dominant wheat-infecting pathogens within the species complex. We designed a PCR-RFLP assay to distinguish P. nodorum from Pat1. Approximately 4% of P. nodorum and Pat1 isolates showed evidence of hybridization. Measures of private allelic richness at SSR and sequence loci suggest that the center of origin of P. nodorum coincides with its host in the Fertile Crescent. We hypothesize that the origin of this species complex is also in the Fertile Crescent, with four species out of nine found exclusively in the Iranian collections.
Collapse
|
273
|
Tack AJM, Thrall PH, Barrett LG, Burdon JJ, Laine AL. Variation in infectivity and aggressiveness in space and time in wild host-pathogen systems: causes and consequences. J Evol Biol 2012; 25:1918-1936. [PMID: 22905782 DOI: 10.1111/j.1420-9101.2012.02588.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 12/18/2022]
Abstract
Variation in host resistance and in the ability of pathogens to infect and grow (i.e. pathogenicity) is important as it provides the raw material for antagonistic (co)evolution and therefore underlies risks of disease spread, disease evolution and host shifts. Moreover, the distribution of this variation in space and time may inform us about the mode of coevolutionary selection (arms race vs. fluctuating selection dynamics) and the relative roles of G × G interactions, gene flow, selection and genetic drift in shaping coevolutionary processes. Although variation in host resistance has recently been reviewed, little is known about overall patterns in the frequency and scale of variation in pathogenicity, particularly in natural systems. Using 48 studies from 30 distinct host-pathogen systems, this review demonstrates that variation in pathogenicity is ubiquitous across multiple spatial and temporal scales. Quantitative analysis of a subset of extensively studied plant-pathogen systems shows that the magnitude of within-population variation in pathogenicity is large relative to among-population variation and that the distribution of pathogenicity partly mirrors the distribution of host resistance. At least part of the variation in pathogenicity found at a given spatial scale is adaptive, as evidenced by studies that have examined local adaptation at scales ranging from single hosts through metapopulations to entire continents and - to a lesser extent - by comparisons of pathogenicity with neutral genetic variation. Together, these results support coevolutionary selection through fluctuating selection dynamics. We end by outlining several promising directions for future research.
Collapse
Affiliation(s)
- A J M Tack
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - P H Thrall
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - L G Barrett
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - J J Burdon
- CSIRO-Plant Industry, Canberra, ACT, Australia
| | - A-L Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, Helsinki, Finland
| |
Collapse
|
274
|
Pérez G, Slippers B, Wingfield MJ, Wingfield BD, Carnegie AJ, Burgess TI. Cryptic species, native populations and biological invasions by a eucalypt forest pathogen. Mol Ecol 2012; 21:4452-71. [PMID: 22882273 DOI: 10.1111/j.1365-294x.2012.05714.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Human-associated introduction of pathogens and consequent invasions is very evident in areas where no related organisms existed before. In areas where related but distinct populations or closely related cryptic species already exist, the invasion process is much harder to unravel. In this study, the population structure of the Eucalyptus leaf pathogen Teratosphaeria nubilosa was studied within its native range in Australia, including both commercial plantations and native forests. A collection of 521 isolates from across its distribution was characterized using eight microsatellite loci, resulting in 112 multilocus haplotypes (MLHs). Multivariate and Bayesian analyses of the population conducted in structure revealed three genetically isolated groups (A, B and C), with no evidence for recombination or hybridization among groups, even when they co-occur in the same plantation. DNA sequence data of the ITS (n = 32), β-tubulin (n = 32) and 27 anonymous loci (n = 16) were consistent with microsatellite data in suggesting that T. nubilosa should be considered as a species complex. Patterns of genetic diversity provided evidence of biological invasions by the pathogen within Australia in the states of Western Australia and New South Wales and helped unravel the pattern of invasion beyond Australia into New Zealand, Brazil and Uruguay. No significant genetic differences in pathogen populations collected in native forests and commercial plantations were observed. This emphasizes the importance of sanitation in the acquisition of nursery stock for the establishment of commercial plantations.
Collapse
Affiliation(s)
- Guillermo Pérez
- Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0002, South Africa.
| | | | | | | | | | | |
Collapse
|
275
|
Chen M, Li X, Yang Q, Chi X, Pan L, Chen N, Yang Z, Wang T, Wang M, Yu S. Soil eukaryotic microorganism succession as affected by continuous cropping of peanut--pathogenic and beneficial fungi were selected. PLoS One 2012; 7:e40659. [PMID: 22808226 PMCID: PMC3393692 DOI: 10.1371/journal.pone.0040659] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 06/11/2012] [Indexed: 11/18/2022] Open
Abstract
Peanut is an important oil crop worldwide and shows considerable adaptability but growth and yield are negatively affected by continuous cropping. Soil micro-organisms are efficient bio-indicators of soil quality and plant health and are critical to the sustainability of soil-based ecosystem function and to successful plant growth. In this study, 18S rRNA gene clone library analyses were employed to study the succession progress of soil eukaryotic micro-organisms under continuous peanut cultivation. Eight libraries were constructed for peanut over three continuous cropping cycles and its representative growth stages. Cluster analyses indicated that soil micro-eukaryotic assemblages obtained from the same peanut cropping cycle were similar, regardless of growth period. Six eukaryotic groups were found and fungi predominated in all libraries. The fungal populations showed significant dynamic change and overall diversity increased over time under continuous peanut cropping. The abundance and/or diversity of clones affiliated with Eurotiales, Hypocreales, Glomerales, Orbiliales, Mucorales and Tremellales showed an increasing trend with continuous cropping but clones affiliated with Agaricales, Cantharellales, Pezizales and Pyxidiophorales decreased in abundance and/or diversity over time. The current data, along with data from previous studies, demonstrated that the soil microbial community was affected by continuous cropping, in particular, the pathogenic and beneficial fungi that were positively selected over time, which is commonplace in agro-ecosystems. The trend towards an increase in fungal pathogens and simplification of the beneficial fungal community could be important factors contributing to the decline in peanut growth and yield over many years of continuous cropping.
Collapse
Affiliation(s)
- Mingna Chen
- Shandong Peanut Research Institute, Qingdao, China
| | - Xiao Li
- Shandong Peanut Research Institute, Qingdao, China
| | - Qingli Yang
- Shandong Peanut Research Institute, Qingdao, China
| | - Xiaoyuan Chi
- Shandong Peanut Research Institute, Qingdao, China
| | - Lijuan Pan
- Shandong Peanut Research Institute, Qingdao, China
| | - Na Chen
- Shandong Peanut Research Institute, Qingdao, China
| | - Zhen Yang
- Shandong Peanut Research Institute, Qingdao, China
| | - Tong Wang
- Shandong Peanut Research Institute, Qingdao, China
| | - Mian Wang
- Shandong Peanut Research Institute, Qingdao, China
| | - Shanlin Yu
- Shandong Peanut Research Institute, Qingdao, China
- * E-mail:
| |
Collapse
|
276
|
Pagán I, González-Jara P, Moreno-Letelier A, Rodelo-Urrego M, Fraile A, Piñero D, García-Arenal F. Effect of biodiversity changes in disease risk: exploring disease emergence in a plant-virus system. PLoS Pathog 2012; 8:e1002796. [PMID: 22792068 PMCID: PMC3390404 DOI: 10.1371/journal.ppat.1002796] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Accepted: 05/25/2012] [Indexed: 11/19/2022] Open
Abstract
The effect of biodiversity on the ability of parasites to infect their host and cause disease (i.e. disease risk) is a major question in pathology, which is central to understand the emergence of infectious diseases, and to develop strategies for their management. Two hypotheses, which can be considered as extremes of a continuum, relate biodiversity to disease risk: One states that biodiversity is positively correlated with disease risk (Amplification Effect), and the second predicts a negative correlation between biodiversity and disease risk (Dilution Effect). Which of them applies better to different host-parasite systems is still a source of debate, due to limited experimental or empirical data. This is especially the case for viral diseases of plants. To address this subject, we have monitored for three years the prevalence of several viruses, and virus-associated symptoms, in populations of wild pepper (chiltepin) under different levels of human management. For each population, we also measured the habitat species diversity, host plant genetic diversity and host plant density. Results indicate that disease and infection risk increased with the level of human management, which was associated with decreased species diversity and host genetic diversity, and with increased host plant density. Importantly, species diversity of the habitat was the primary predictor of disease risk for wild chiltepin populations. This changed in managed populations where host genetic diversity was the primary predictor. Host density was generally a poorer predictor of disease and infection risk. These results support the dilution effect hypothesis, and underline the relevance of different ecological factors in determining disease/infection risk in host plant populations under different levels of anthropic influence. These results are relevant for managing plant diseases and for establishing conservation policies for endangered plant species.
Collapse
Affiliation(s)
- Israel Pagán
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Pablo González-Jara
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Alejandra Moreno-Letelier
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Manuel Rodelo-Urrego
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Aurora Fraile
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| | - Daniel Piñero
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Fernando García-Arenal
- Centro de Biotecnología y Genómica de Plantas (UPM-INIA), and E.T.S.I. Agrónomos, Campus de Montegancedo, Universidad Politécnica de Madrid, Pozuelo de Alarcón, Madrid, Spain
| |
Collapse
|
277
|
Troch V, Audenaert K, Bekaert B, Höfte M, Haesaert G. Phylogeography and virulence structure of the powdery mildew population on its 'new' host triticale. BMC Evol Biol 2012; 12:76. [PMID: 22658131 PMCID: PMC3457899 DOI: 10.1186/1471-2148-12-76] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 05/10/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Powdery mildew, caused by the obligate biotrophic fungus Blumeria graminis, is a major problem in cereal production as it can reduce quality and yield. B. graminis has evolved eight distinct formae speciales (f.sp.) which display strict host specialization. In the last decade, powdery mildew has emerged on triticale, the artificial intergeneric hybrid between wheat and rye. This emergence is probably triggered by a host range expansion of the wheat powdery mildew B. graminis f.sp. tritici. To gain more precise information about the evolutionary processes that led to this host range expansion, we pursued a combined pathological and genetic approach. RESULTS B. graminis isolates were sampled from triticale, wheat and rye from different breeding regions in Europe. Pathogenicity tests showed that isolates collected from triticale are highly pathogenic on most of the tested triticale cultivars. Moreover, these isolates were also able to infect several wheat cultivars (their previous hosts), although a lower aggressiveness was observed compared to isolates collected from wheat. Phylogenetic analysis of nuclear gene regions identified two statistically significant clades, which to a certain extent correlated with pathogenicity. No differences in virulence profiles were found among the sampled regions, but the distribution of genetic variation demonstrated to be geography dependent. A multilocus haplotype network showed that haplotypes pathogenic on triticale are distributed at different sites in the network, but always clustered at or near the tips of the network. CONCLUSIONS This study reveals a genetic structure in B. graminis with population differentiation according to geography and host specificity. In addition, evidence is brought forward demonstrating that the host range expansion of wheat isolates to the new host triticale occurred recently and multiple times at different locations in Europe.
Collapse
Affiliation(s)
- Veronique Troch
- Associated Faculty of Applied Bioscience Engineering, University College Ghent, Valentin Vaerwyckweg 1, B-9000, Ghent, Belgium
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - Kris Audenaert
- Associated Faculty of Applied Bioscience Engineering, University College Ghent, Valentin Vaerwyckweg 1, B-9000, Ghent, Belgium
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - Boris Bekaert
- Associated Faculty of Applied Bioscience Engineering, University College Ghent, Valentin Vaerwyckweg 1, B-9000, Ghent, Belgium
| | - Monica Höfte
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| | - Geert Haesaert
- Associated Faculty of Applied Bioscience Engineering, University College Ghent, Valentin Vaerwyckweg 1, B-9000, Ghent, Belgium
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Coupure links 653, B-9000, Ghent, Belgium
| |
Collapse
|
278
|
Silva DN, Talhinhas P, Cai L, Manuel L, Gichuru EK, Loureiro A, Várzea V, Paulo OS, Batista D. Host-jump drives rapid and recent ecological speciation of the emergent fungal pathogen Colletotrichum kahawae. Mol Ecol 2012; 21:2655-70. [PMID: 22519519 DOI: 10.1111/j.1365-294x.2012.05557.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Ecological speciation through host-shift has been proposed as a major route for the appearance of novel fungal pathogens. The growing awareness of their negative impact on global economies and public health created an enormous interest in identifying the factors that are most likely to promote their emergence in nature. In this work, a combination of pathological, molecular and geographical data was used to investigate the recent emergence of the fungus Colletotrichum kahawae. C. kahawae emerged as a specialist pathogen causing coffee berry disease in Coffea arabica, owing to its unparalleled adaptation of infecting green coffee berries. Contrary to current hypotheses, our results suggest that a recent host-jump underlay the speciation of C. kahawae from a generalist group of fungi seemingly harmless to coffee berries. We posit that immigrant inviability and a predominantly asexual behaviour could have been instrumental in driving speciation by creating pleiotropic interactions between local adaptation and reproductive patterns. Moreover, we estimate that C. kahawae began its diversification at <2200 bp leaving a very short time frame since the divergence from its sibling lineage (c. 5600 bp), during which a severe drop in C. kahawae's effective population size occurred. This further supports a scenario of recent introduction and subsequent adaptation to C. arabica. Phylogeographical data revealed low levels of genetic polymorphism but provided the first geographically consistent population structure of C. kahawae, inferring the Angolan population as the most ancestral and the East African populations as the most recently derived. Altogether, these results highlight the significant role of host specialization and asexuality in the emergence of fungal pathogens through ecological speciation.
Collapse
Affiliation(s)
- Diogo N Silva
- CIFC/IICT-Centro de Investigação das Ferrugens do Cafeeiro/Instituto de Investigação Científica Tropical, Quinta do Marquês, 2784-505 Oeiras, Portugal.
| | | | | | | | | | | | | | | | | |
Collapse
|
279
|
Fisher MC, Henk DA, Briggs CJ, Brownstein JS, Madoff LC, McCraw SL, Gurr SJ. Emerging fungal threats to animal, plant and ecosystem health. Nature 2012; 484:186-94. [PMID: 22498624 PMCID: PMC3821985 DOI: 10.1038/nature10947] [Citation(s) in RCA: 1775] [Impact Index Per Article: 147.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 01/25/2012] [Indexed: 01/15/2023]
Abstract
The past two decades have seen an increasing number of virulent infectious diseases in natural populations and managed landscapes. In both animals and plants, an unprecedented number of fungal and fungal-like diseases have recently caused some of the most severe die-offs and extinctions ever witnessed in wild species, and are jeopardizing food security. Human activity is intensifying fungal disease dispersal by modifying natural environments and thus creating new opportunities for evolution. We argue that nascent fungal infections will cause increasing attrition of biodiversity, with wider implications for human and ecosystem health, unless steps are taken to tighten biosecurity worldwide.
Collapse
Affiliation(s)
- Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College, London W2 1PG, UK.
| | | | | | | | | | | | | |
Collapse
|
280
|
Wolfe BE, Pringle A. Geographically structured host specificity is caused by the range expansions and host shifts of a symbiotic fungus. THE ISME JOURNAL 2012; 6:745-55. [PMID: 22134645 PMCID: PMC3309363 DOI: 10.1038/ismej.2011.155] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 09/12/2011] [Accepted: 09/15/2011] [Indexed: 11/09/2022]
Abstract
The inability to associate with local species may constrain the spread of mutualists arriving to new habitats, but the fates of introduced, microbial mutualists are largely unknown. The deadly poisonous ectomycorrhizal fungus Amanita phalloides (the death cap) is native to Europe and introduced to the East and West Coasts of North America. By cataloging host associations across the two continents, we record dramatic changes in specificity among the three ranges. On the East Coast, where the fungus is restricted in its distribution, it associates almost exclusively with pines, which are rarely hosts of A. phalloides in its native range. In California, where the fungus is widespread and locally abundant, it associates almost exclusively with oaks, mirroring the host associations observed in Europe. The most common host of the death cap in California is the endemic coast live oak (Quercus agrifolia), and the current distribution of A. phalloides appears constrained within the distribution of Q. agrifolia. In California, host shifts to native plants are also associated with a near doubling in the resources allocated to sexual reproduction and a prolonged fruiting period; mushrooms are twice as large as they are elsewhere and mushrooms are found throughout the year. Host and niche shifts are likely to shape the continuing range expansion of A. phalloides and other ectomycorrhizal fungi introduced across the world.
Collapse
Affiliation(s)
- Benjamin E Wolfe
- Department of Organismic and Evolutionary Biology, FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
| | | |
Collapse
|
281
|
Asexual reproduction induces a rapid and permanent loss of sexual reproduction capacity in the rice fungal pathogen Magnaporthe oryzae: results of in vitro experimental evolution assays. BMC Evol Biol 2012; 12:42. [PMID: 22458778 PMCID: PMC3379926 DOI: 10.1186/1471-2148-12-42] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 03/29/2012] [Indexed: 12/15/2022] Open
Abstract
Background Sexual reproduction is common in eukaryotic microorganisms, with few species reproducing exclusively asexually. However, in some organisms, such as fungi, asexual reproduction alternates with episodic sexual reproduction events. Fungi are thus appropriate organisms for studies of the reasons for the selection of sexuality or clonality and of the mechanisms underlying this selection. Magnaporthe oryzae, an Ascomycete causing blast disease on rice, reproduces mostly asexually in natura. Sexual reproduction is possible in vitro and requires (i) two strains of opposite mating types including (ii) at least one female-fertile strain (i.e. a strain able to produce perithecia, the female organs in which meiosis occurs). Female-fertile strains are found only in limited areas of Asia, in which evidence for contemporary recombination has recently been obtained. We induced the forced evolution of four Chinese female-fertile strains in vitro by the weekly transfer of asexual spores (conidia) between Petri dishes. We aimed to determine whether female fertility was rapidly lost in the absence of sexual reproduction and whether this loss was controlled genetically or epigenetically. Results All the strains became female-sterile after 10 to 19 rounds of selection under asexual conditions. As no single-spore isolation was carried out, the observed decrease in the production of perithecia reflected the emergence and the invasion of female-sterile mutants. The female-sterile phenotype segregated in the offspring of crosses between female-sterile evolved strains and female-fertile wild-type strains. This segregation was maintained in the second generation in backcrosses. Female-sterile evolved strains were subjected to several stresses, but none induced the restoration of female fertility. This loss of fertility was therefore probably due to genetic rather than epigenetic mechanisms. In competition experiments, female-sterile mutants produced similar numbers of viable conidia to wild-type strains, but released them more efficiently. This advantage may account for the invasion of our populations by female-sterile mutants. Conclusions We show for the first time that, in the absence of sexual reproduction, female-sterile mutants of M. oryzae rice strains can arise and increase in abundance in asexual generations. This change in phenotype was frequent and probably caused by mutation. These results suggest that female fertility may have been lost rapidly during the dispersion of the fungus from Asia to the rest of the world.
Collapse
|
282
|
DILMAGHANI A, GLADIEUX P, GOUT L, GIRAUD T, BRUNNER PC, STACHOWIAK A, BALESDENT MH, ROUXEL T. Migration patterns and changes in population biology associated with the worldwide spread of the oilseed rape pathogenLeptosphaeria maculans. Mol Ecol 2012; 21:2519-33. [DOI: 10.1111/j.1365-294x.2012.05535.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
283
|
Loker ES. Macroevolutionary Immunology: A Role for Immunity in the Diversification of Animal life. Front Immunol 2012; 3:25. [PMID: 22566909 PMCID: PMC3342036 DOI: 10.3389/fimmu.2012.00025] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 02/08/2012] [Indexed: 11/13/2022] Open
Abstract
An emerging picture of the nature of immune systems across animal phyla reveals both conservatism of some features and the appearance among and within phyla of novel, lineage-specific defense solutions. The latter collectively represent a major and underappreciated form of animal diversity. Factors influencing this macroevolutionary (above the species level) pattern of novelty are considered and include adoption of different life styles, life histories, and body plans; a general advantage of being distinctive with respect to immune defenses; and the responses required to cope with parasites, many of which afflict hosts in a lineage-specific manner. This large-scale pattern of novelty implies that immunological phenomena can affect microevolutionary processes (at the population level within species) that can eventually lead to macroevolutionary events such as speciation, radiations, or extinctions. Immunologically based phenomena play a role in favoring intraspecific diversification, specialization and host specificity of parasites, and mechanisms are discussed whereby this could lead to parasite speciation. Host switching - the acquisition of new host species by parasites - is a major mechanism that drives parasite diversity and is frequently involved in disease emergence. It is also one that can be favored by reductions in immune competence of new hosts. Mechanisms involving immune phenomena favoring intraspecific diversification and speciation of host species are also discussed. A macroevolutionary perspective on immunology is invaluable in today's world, including the need to study a broader range of species with distinctive immune systems. Many of these species are faced with extinction, another macroevolutionary process influenced by immune phenomena.
Collapse
Affiliation(s)
- Eric S. Loker
- Center for Evolutionary and Theoretical Immunology, Department of Biology, Division of Parasitology, Museum of Southwestern Biology, University of New MexicoAlbuquerque, NM, USA
| |
Collapse
|
284
|
Saleh D, Xu P, Shen Y, Li C, Adreit H, Milazzo J, Ravigné V, Bazin E, Nottéghem JL, Fournier E, Tharreau D. Sex at the origin: an Asian population of the rice blast fungus Magnaporthe oryzae reproduces sexually. Mol Ecol 2012; 21:1330-44. [PMID: 22313491 DOI: 10.1111/j.1365-294x.2012.05469.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Sexual reproduction may be cryptic or facultative in fungi and therefore difficult to detect. Magnaporthe oryzae, which causes blast, the most damaging fungal disease of rice, is thought to originate from southeast Asia. It reproduces asexually in all rice-growing regions. Sexual reproduction has been suspected in limited areas of southeast Asia, but has never been demonstrated in contemporary populations. We characterized several M. oryzae populations worldwide both biologically and genetically, to identify candidate populations for sexual reproduction. The sexual cycle of M. oryzae requires two strains of opposite mating types, at least one of which is female-fertile, to come into contact. In one Chinese population, the two mating types were found to be present at similar frequencies and almost all strains were female-fertile. Compatible strains from this population completed the sexual cycle in vitro and produced viable progenies. Genotypic richness and linkage disequilibrium data also supported the existence of sexual reproduction in this population. We resampled this population the following year, and the data obtained confirmed the presence of all the biological and genetic characteristics of sexual reproduction. In particular, a considerable genetic reshuffling of alleles was observed between the 2 years. Computer simulations confirmed that the observed genetic characteristics were unlikely to have arisen in the absence of recombination. We therefore concluded that a contemporary population of M. oryzae, pathogenic on rice, reproduces sexually in natura in southeast Asia. Our findings provide evidence for the loss of sexual reproduction by a fungal plant pathogen outside its centre of origin.
Collapse
Affiliation(s)
- Dounia Saleh
- Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR BGPI, Montpellier, France
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
285
|
Robert S, Ravigne V, Zapater MF, Abadie C, Carlier J. Contrasting introduction scenarios among continents in the worldwide invasion of the banana fungal pathogen Mycosphaerella fijiensis. Mol Ecol 2012; 21:1098-114. [PMID: 22256778 DOI: 10.1111/j.1365-294x.2011.05432.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Reconstructing and characterizing introduction routes is a key step towards understanding the ecological and evolutionary factors underlying successful invasions and disease emergence. Here, we aimed to decipher scenarios of introduction and stochastic demographic events associated with the global spread of an emerging disease of bananas caused by the destructive fungal pathogen Mycosphaerella fijiensis. We analysed the worldwide population structure of this fungus using 21 microsatellites and 8 sequence-based markers on 735 individuals from 37 countries. Our analyses designated South-East Asia as the source of the global invasion and supported the location of the centre of origin of M. fijiensis within this area. We confirmed the occurrence of bottlenecks upon introduction into other continents followed by widespread founder events within continents. Furthermore, this study suggested contrasting introduction scenarios of the pathogen between the African and American continents. While potential signatures of admixture resulting from multiple introductions were detected in America, all the African samples examined seem to descend from a single successful founder event. In combination with historical information, our study reveals an original and unprecedented global scenario of invasion for this recently emerging disease caused by a wind-dispersed pathogen.
Collapse
Affiliation(s)
- S Robert
- CIRAD, UMR BGPI, Campus International de Baillarguet, Montpellier Cedex 5, France
| | | | | | | | | |
Collapse
|
286
|
Kjær ED, McKinney LV, Nielsen LR, Hansen LN, Hansen JK. Adaptive potential of ash (Fraxinus excelsior) populations against the novel emerging pathogen Hymenoscyphus pseudoalbidus. Evol Appl 2011; 5:219-28. [PMID: 25568043 PMCID: PMC3353348 DOI: 10.1111/j.1752-4571.2011.00222.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2010] [Accepted: 10/05/2011] [Indexed: 11/30/2022] Open
Abstract
An emerging infectious pathogen Hymenoscyphus pseudoalbidus has spread across much of Europe within recent years causing devastating damage on European common ash trees (Fraxinus excelsior) and associated plant communities. The present study demonstrates the presence of additive genetic variation in susceptibility of natural F. excelsior populations to the new invasive disease. We observe high levels of additive variation in the degree of susceptibility with relatively low influence of environmental factors (narrow-sense heritability = 0.37–0.52). Most native trees are found to be highly susceptible, and we estimate that only around 1% has the potential of producing offspring with expected crown damage of <10% under the present disease pressure. The results suggest that the presence of additive genetic diversity in natural F. excelsior populations can confer the species with important ability to recover, but that low resistance within natural European populations is to be expected because of a low frequency of the hypo-sensitive trees. Large effective population sizes will be required to avoid genetic bottlenecks. The role of artificial selection and breeding for protection of the species is discussed based on the findings.
Collapse
Affiliation(s)
- Erik Dahl Kjær
- Forest & Landscape, Faculty of Life Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Lea Vig McKinney
- Forest & Landscape, Faculty of Life Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Lene Rostgaard Nielsen
- Forest & Landscape, Faculty of Life Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Lars Nørgaard Hansen
- Forest & Landscape, Faculty of Life Sciences, University of Copenhagen Frederiksberg, Denmark
| | - Jon Kehlet Hansen
- Forest & Landscape, Faculty of Life Sciences, University of Copenhagen Frederiksberg, Denmark
| |
Collapse
|
287
|
Farrer RA, Weinert LA, Bielby J, Garner TWJ, Balloux F, Clare F, Bosch J, Cunningham AA, Weldon C, du Preez LH, Anderson L, Pond SLK, Shahar-Golan R, Henk DA, Fisher MC. Multiple emergences of genetically diverse amphibian-infecting chytrids include a globalized hypervirulent recombinant lineage. Proc Natl Acad Sci U S A 2011; 108:18732-6. [PMID: 22065772 PMCID: PMC3219125 DOI: 10.1073/pnas.1111915108] [Citation(s) in RCA: 300] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Batrachochytrium dendrobatidis (Bd) is a globally ubiquitous fungal infection that has emerged to become a primary driver of amphibian biodiversity loss. Despite widespread effort to understand the emergence of this panzootic, the origins of the infection, its patterns of global spread, and principle mode of evolution remain largely unknown. Using comparative population genomics, we discovered three deeply diverged lineages of Bd associated with amphibians. Two of these lineages were found in multiple continents and are associated with known introductions by the amphibian trade. We found that isolates belonging to one clade, the global panzootic lineage (BdGPL) have emerged across at least five continents during the 20th century and are associated with the onset of epizootics in North America, Central America, the Caribbean, Australia, and Europe. The two newly identified divergent lineages, Cape lineage (BdCAPE) and Swiss lineage (BdCH), were found to differ in morphological traits when compared against one another and BdGPL, and we show that BdGPL is hypervirulent. BdGPL uniquely bears the hallmarks of genomic recombination, manifested as extensive intergenomic phylogenetic conflict and patchily distributed heterozygosity. We postulate that contact between previously genetically isolated allopatric populations of Bd may have allowed recombination to occur, resulting in the generation, spread, and invasion of the hypervirulent BdGPL leading to contemporary disease-driven losses in amphibian biodiversity.
Collapse
Affiliation(s)
- Rhys A Farrer
- Department Infectious Disease Epidemiology, Imperial College, London W2 1PG, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
288
|
Llop P, Barbé S, López MM. Functions and origin of plasmids in Erwinia species that are pathogenic to or epiphytically associated with pome fruit trees. TREES (BERLIN, GERMANY : WEST) 2011; 26:31-46. [PMID: 25983394 PMCID: PMC4425259 DOI: 10.1007/s00468-011-0630-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 09/17/2011] [Accepted: 09/21/2011] [Indexed: 05/29/2023]
Abstract
The genus Erwinia includes plant-associated pathogenic and non-pathogenic species. Among them, all species pathogenic to pome fruit trees (E. amylovora, E. pyrifoliae, E. piriflorinigrans, Erwinia sp. from Japan) cause similar symptoms, but differ in their degrees of aggressiveness, i.e. in symptoms, host range or both. The presence of plasmids of similar size, in the range of 30 kb, is a common characteristic that they possess. Besides, they share some genetic content with high homology in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes. Knowledge of the content of these plasmids and comparative genetic analyses may provide interesting new clues to understanding the origin and evolution of these pathogens and the level of symptoms they produce. Furthermore, genetic similarities observed among some of the plasmids (and genomes) from the above indicated pathogenic species and E. tasmaniensis or E. billingiae, which are epiphytic on the same hosts, may reveal associations that could expose the mechanisms of origin of pathogens. A summary of the current information on their plasmids and the relationships among them is presented here.
Collapse
Affiliation(s)
- Pablo Llop
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - Silvia Barbé
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| | - María M. López
- Instituto Valenciano de Investigaciones Agrarias (IVIA), Ctra. Moncada-Náquera Km 4.5, 46113 Moncada, Valencia Spain
| |
Collapse
|
289
|
GLADIEUX PIERRE, GUÉRIN FABIEN, GIRAUD TATIANA, CAFFIER VALÉRIE, LEMAIRE CHRISTOPHE, PARISI LUCIANA, DIDELOT FRÉDÉRIQUE, LE CAM BRUNO. Emergence of novel fungal pathogens by ecological speciation: importance of the reduced viability of immigrants. Mol Ecol 2011; 20:4521-32. [DOI: 10.1111/j.1365-294x.2011.05288.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
290
|
Cai R, Yan S, Liu H, Leman S, Vinatzer BA. Reconstructing host range evolution of bacterial plant pathogens using Pseudomonas syringae pv. tomato and its close relatives as a model. INFECTION GENETICS AND EVOLUTION 2011; 11:1738-51. [DOI: 10.1016/j.meegid.2011.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 07/07/2011] [Accepted: 07/12/2011] [Indexed: 10/17/2022]
|
291
|
Gutiérrez-Gutiérrez C, Castillo P, Cantalapiedra-Navarrete C, Landa BB, Derycke S, Palomares-Rius JE. Genetic structure of Xiphinema pachtaicum and X. index populations based on mitochondrial DNA variation. PHYTOPATHOLOGY 2011; 101:1168-1175. [PMID: 21554182 DOI: 10.1094/phyto-07-10-0194] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The dagger nematodes Xiphinema pachtaicum and X. index are two of the most widespread and frequently occurring Xiphinema spp. co-infesting vineyards and other crops and natural habitats worldwide. Sexual reproduction is rare in these species. The primary objective of this study was to determine the genetic structure of X. pachtaicum and X. index populations using eight and seven populations, respectively, from different "wine of denomination of origin (D.O.) zones" in Spain and Sardinia (Italy), by studying mitochondrial (cytochrome oxidase c subunit 1 or COI) and nuclear (D2-D3 expansion segments of 28S rDNA) markers. Both Xiphinema spp. showed low intraspecific divergence among COI sequences, ranging from 0.2% (1 base substitution) to 2.3% (10 substitutions) in X. pachtaicum and from 0.2% (1 base substitution) to 0.4% (2 substitutions) in X. index. Population genetic structure was strong for both species. Nevertheless, molecular differences among grapevine-growing areas were not significant, and intrapopulation diversity was very low. It is hypothesized that this genetic homogeneity in the nematode populations reflects their predominant parthenogenetic reproduction mode and low dispersal abilities. Our results also show that X. pachtaicum populations in Spain have possibly been established from two different populations of origin. Results also demonstrated that the two DNA regions studied are suitable diagnostic markers for X. index and X. pachtaicum.
Collapse
|
292
|
Goss EM, Cardenas ME, Myers K, Forbes GA, Fry WE, Restrepo S, Grünwald NJ. The plant pathogen Phytophthora andina emerged via hybridization of an unknown Phytophthora species and the Irish potato famine pathogen, P. infestans. PLoS One 2011; 6:e24543. [PMID: 21949727 PMCID: PMC3174952 DOI: 10.1371/journal.pone.0024543] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 08/12/2011] [Indexed: 11/19/2022] Open
Abstract
Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c.
Collapse
Affiliation(s)
- Erica M. Goss
- Horticultural Crops Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Corvallis, Oregon, United States of America
| | - Martha E. Cardenas
- Laboratorio de Micología y Fitopatología, Universidad de los Andes, Bogotá, Colombia
| | - Kevin Myers
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | | | - William E. Fry
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Silvia Restrepo
- Laboratorio de Micología y Fitopatología, Universidad de los Andes, Bogotá, Colombia
| | - Niklaus J. Grünwald
- Horticultural Crops Research Laboratory, Agricultural Research Service, United States Department of Agriculture, Corvallis, Oregon, United States of America
| |
Collapse
|
293
|
Bus VG, Rikkerink EH, Caffier V, Durel CE, Plummer KM. Revision of the Nomenclature of the Differential Host-Pathogen Interactions of Venturia inaequalis and Malus. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:391-413. [PMID: 0 DOI: 10.1146/annurev-phyto-072910-095339] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The apple scab (Venturia inaequalis–Malus) pathosystem was one of the first systems for which Flor's concept of gene-for-gene (GfG) relationships between the host plant and the pathogen was demonstrated. There is a rich resource of host resistance genes present in Malus germplasm that could potentially be marshalled to confer durable resistance against this most important apple disease. A comprehensive understanding of the host-pathogen interactions occurring in this pathosystem is a prerequisite for effectively manipulating these host resistance factors. An accurate means of identification of specific resistance and consistent use of gene nomenclature is critical for this process. A set of universally available, differentially resistant hosts is described, which will be followed by a set of defined pathogen races at a later stage. We review pertinent aspects of the history of apple scab research, describe the current status and future directions of this research, and resolve some outstanding issues.
Collapse
Affiliation(s)
- Vincent G.M. Bus
- The Plant and Food Research Institute of New Zealand, Private Bag 1401, Havelock North 4157, New Zealand
| | - Erik H.A. Rikkerink
- The Plant and Food Research Institute of New Zealand, Private Bag 92169, Auckland 1142, New Zealand
| | - Valérie Caffier
- INRA, UMR77 Pathologie Végétale – PaVé, INRA/ACO/UA, IFR QUASAV, BP 60057, F-49071 Beaucouzé, France
| | - Charles-Eric Durel
- INRA, UMR 1259 Genetics and Horticulture – GenHort, INRA/ACO/UA, IFR QUASAV, BP 60057, F-49071 Beaucouzé, France
| | - Kim M. Plummer
- La Trobe University, Department of Botany, Bundoora, Vic. 3086, Australia
| |
Collapse
|
294
|
Papaïx J, Goyeau H, Du Cheyron P, Monod H, Lannou C. Influence of cultivated landscape composition on variety resistance: an assessment based on wheat leaf rust epidemics. THE NEW PHYTOLOGIST 2011; 191:1095-1107. [PMID: 21585391 DOI: 10.1111/j.1469-8137.2011.03764.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In plant pathology, the idea of designing variety management strategies at the scale of cultivated landscapes is gaining more and more attention. This requires the identification of effects that take place at large scales on host and pathogen populations. Here, we show how the landscape varietal composition influences the resistance level (as measured in the field) of the most grown wheat varieties by altering the structure of the pathogen populations. For this purpose, we jointly analysed three large datasets describing the wheat leaf rust pathosystem (Puccinia triticina/Triticum aestivum) at the country scale of France with a Bayesian hierarchical model. We showed that among all compatible pathotypes, some were preferentially associated with a variety, that the pathotype frequencies on a variety were affected by the landscape varietal composition, and that the observed resistance level of a variety was linked to the frequency of the most aggressive pathotypes among all compatible pathotypes. This data exploration establishes a link between the observed resistance level of a variety and landscape composition at the national scale. It illustrates that the quantitative aspects of the host-pathogen relationship have to be considered in addition to the major resistance/virulence factors in landscape epidemiology approaches.
Collapse
Affiliation(s)
- Julien Papaïx
- INRA, UMR 1290 BIOGER, F-78850 Thiverval Grignon, France
- INRA, UR 341 Mathématiques et Informatique Appliquées, F-78350 Jouy-en-Josas, France
| | | | | | - Hervé Monod
- INRA, UR 341 Mathématiques et Informatique Appliquées, F-78350 Jouy-en-Josas, France
| | | |
Collapse
|
295
|
Sommerhalder RJ, McDonald BA, Mascher F, Zhan J. Effect of hosts on competition among clones and evidence of differential selection between pathogenic and saprophytic phases in experimental populations of the wheat pathogen Phaeosphaeria nodorum. BMC Evol Biol 2011; 11:188. [PMID: 21718545 PMCID: PMC3145600 DOI: 10.1186/1471-2148-11-188] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Accepted: 07/01/2011] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Monoculture, multi-cropping and wider use of highly resistant cultivars have been proposed as mechanisms to explain the elevated rate of evolution of plant pathogens in agricultural ecosystems. We used a mark-release-recapture experiment with the wheat pathogen Phaeosphaeria nodorum to evaluate the impact of two of these mechanisms on the evolution of a pathogen population. Nine P. nodorum isolates marked with ten microsatellite markers and one minisatellite were released onto five replicated host populations to initiate epidemics of Stagonospora nodorum leaf blotch. The experiment was carried out over two consecutive host growing seasons and two pathogen collections were made during each season. RESULTS A total of 637 pathogen isolates matching the marked inoculants were recovered from inoculated plots over two years. Genetic diversity in the host populations affected the evolution of the corresponding P. nodorum populations. In the cultivar mixture the relative frequencies of inoculants did not change over the course of the experiment and the pathogen exhibited a low variation in selection coefficients. CONCLUSIONS Our results support the hypothesis that increasing genetic heterogeneity in host populations may retard the rate of evolution in associated pathogen populations. Our experiment also provides indirect evidence of fitness costs associated with host specialization in P. nodorum as indicated by differential selection during the pathogenic and saprophytic phases.
Collapse
Affiliation(s)
- Rubik J Sommerhalder
- Institute of Integrative Biology, ETH Zurich, LFW, Universitaetstrasse 2, Zürich, CH-8092, Switzerland
| | - Bruce A McDonald
- Institute of Integrative Biology, ETH Zurich, LFW, Universitaetstrasse 2, Zürich, CH-8092, Switzerland
| | - Fabio Mascher
- Agroscope Changins-Wädenswil Research Station ACW, P.O. Box 1012, Nyon, CH-1260 Switzerland
| | - Jiasui Zhan
- Key Lab for Biopesticide and Chemical Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
- Fujian Key Lab of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, 35002, China
| |
Collapse
|
296
|
Orton ES, Deller S, Brown JKM. Mycosphaerella graminicola: from genomics to disease control. MOLECULAR PLANT PATHOLOGY 2011; 12:413-24. [PMID: 21535348 PMCID: PMC6640266 DOI: 10.1111/j.1364-3703.2010.00688.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
UNLABELLED This Mycosphaerella graminicola pathogen profile covers recent advances in the knowledge of this ascomycete fungus and of the disease it causes, septoria tritici blotch of wheat. Research on this pathogen has accelerated since publication of a previous pathogen profile in this journal in 2002. Septoria tritici blotch continues to have high economic importance and widespread global impact on wheat production. TAXONOMY Mycosphaerella graminicola (Fuckel) J. Schröt. In Cohn (anamorph: Septoria tritici Roberge in Desmaz.). Kingdom Fungi, Phylum Ascomycota, Class Loculoascomycetes (filamentous ascomycetes), Order Dothideales, Genus Mycosphaerella, Species graminicola. HOST RANGE Bread and durum wheat (Triticum aestivum L. and T. turgidum ssp. durum L.). Disease symptoms: Initially leaves develop a chlorotic flecking, which is followed by the development of necrotic lesions which contain brown-black pycnidia. Necrosis causes a reduction in photosynthetic capacity and therefore affects grain yield. Disease control: The disease is primarily controlled by a combination of resistant cultivars and fungicides. Rapid advances in disease control, especially in resistance breeding, are opening up new opportunities for the management of the disease. USEFUL WEBSITES http://genome.jgi-psf.org/Mycgr3/Mycgr3.home.html.
Collapse
Affiliation(s)
- Elizabeth S Orton
- Department of Disease and Stress Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
| | | | | |
Collapse
|
297
|
XHAARD C, FABRE B, ANDRIEUX A, GLADIEUX P, BARRÈS B, FREY P, HALKETT F. The genetic structure of the plant pathogenic fungus Melampsora larici-populina on its wild host is extensively impacted by host domestication. Mol Ecol 2011; 20:2739-55. [DOI: 10.1111/j.1365-294x.2011.05138.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
298
|
Interspecific and intraspecific diversity in oak powdery mildews in Europe: coevolution history and adaptation to their hosts. MYCOSCIENCE 2011. [DOI: 10.1007/s10267-010-0100-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
|
299
|
McKinney LV, Nielsen LR, Hansen JK, Kjær ED. Presence of natural genetic resistance in Fraxinus excelsior (Oleraceae) to Chalara fraxinea (Ascomycota): an emerging infectious disease. Heredity (Edinb) 2011; 106:788-97. [PMID: 20823903 PMCID: PMC3186218 DOI: 10.1038/hdy.2010.119] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/29/2010] [Accepted: 07/15/2010] [Indexed: 11/09/2022] Open
Abstract
Fraxinus excelsior, common ash native to Europe, is threatened by a recently identified pathogenic fungus Chalara fraxinea, which causes extensive damage on ash trees across Europe. In Denmark, most stands are severely affected leaving many trees with dead crowns. However, single trees show notably fewer symptoms. In this study, the impact of the emerging infectious disease on native Danish ash trees is assessed by estimating presence of inherent resistance in natural populations. Disease symptoms were assessed from 2007 to 2009 at two different sites with grafted ramets of 39 selected clones representing native F. excelsior trees. A strong genetic variation in susceptibility to C. fraxinea infections was observed. No genetic or geographic structure can explain the differences, but strong genetic correlations to leaf senescence were observed. The results suggest that a small fraction of trees in the Danish population of ash possess substantial resistance against the damage. Though this fraction is probably too low to avoid population collapse in most natural or managed ash forests, the observed presence of putative resistance against the emerging infectious disease in natural stands is likely to be of evolutionary importance. This provides prospects of future maintenance of the species through natural or artificial selection in favour of remaining healthy individuals.
Collapse
Affiliation(s)
- L V McKinney
- Department of Forest Genetic Resources, Forest and Landscape Denmark, Faculty of Life Sciences, University of Copenhagen, Rolighedsvej 23, Frederiksberg, Denmark.
| | | | | | | |
Collapse
|
300
|
Oberhaensli S, Parlange F, Buchmann JP, Jenny FH, Abbott JC, Burgis TA, Spanu PD, Keller B, Wicker T. Comparative sequence analysis of wheat and barley powdery mildew fungi reveals gene colinearity, dates divergence and indicates host-pathogen co-evolution. Fungal Genet Biol 2011; 48:327-34. [DOI: 10.1016/j.fgb.2010.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/29/2010] [Accepted: 10/06/2010] [Indexed: 12/24/2022]
|