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Genetic Diversity and Population Structure of Head Blight Disease Causing Fungus Fusarium graminearum in Northern Wheat Belt of India. J Fungi (Basel) 2022; 8:jof8080820. [PMID: 36012808 PMCID: PMC9409692 DOI: 10.3390/jof8080820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/22/2022] [Accepted: 07/26/2022] [Indexed: 02/04/2023] Open
Abstract
Head blight or scab caused by Fusarium graminearum (FG), once ranked as a minor disease in wheat, is now emerging as one of the economically important diseases in India. The present study represents the first in-depth population genetic analysis of the FG from the northern wheat belt of India. In this study, multiple conserved gene sequences comprised of β-tubulin (TUB), translation elongation factor 1-α (TEF), and histone-3 (HIS) regions were used for multi-locus phylogenetic analysis of 123 geographically distinct F. graminearum isolates collected from four different states (Haryana (HR), Punjab (PB), Rajasthan (RJ) and West Bengal (WB)) of India. The phylogenetic and haplotype analysis showed the presence of thirty haplotypes in all the analyzed populations. The haplotypic diversity in the RJ population (Hd = 0.981) was higher than in the HR (Hd = 0.972), PB (Hd = 0.965) and WB population (Hd = 0.962). Recombination events (Rm = 12) and mutation events (485) were also detected. Analysis of molecular variance (AMOVA) indicated that genetic diversity was exclusively due to the differences within populations. The haplotype network was widely dispersed and not associated with specific populations, as a single common haplotype was not detected. The PB population contained both unique (H9, H10 and H11) and shared haplotypes (27 haplotypes) in a higher number in comparison to other geographical locations. Except for haplotype H22 (contains highly aggressive isolates), there was no specific linkage noticed between the isolate aggressiveness and haplotype. The concatenated sequences of all the three genes demonstrated a low level of genetic differentiation (Fst = −0.014 to 0.02) in the analyzed population. Positive values for the neutrality tests in PB, HR and RJ reveal a balancing selection mechanism behind the FG population structure. The WB population showed both positive and negative values of neutrality indices, indicating the role of both population expansion as well as balancing selection in structuring the FG population.
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Lelwala RV, Scott JB, Ades PK, Taylor PWJ. Population Structure of Colletotrichum tanaceti in Australian Pyrethrum Reveals High Evolutionary Potential. PHYTOPATHOLOGY 2019; 109:1779-1792. [PMID: 31179858 DOI: 10.1094/phyto-03-19-0091-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Colletotrichum tanaceti, the causal agent of anthracnose, is an emerging pathogen of commercially grown pyrethrum (Tanacetum cinerariifolium) in Australia. A microsatellite marker library was developed to understand the spatio-genetic structure over three sampled years and across two regions where pyrethrum is cultivated in Australia. Results indicated that C. tanaceti was highly diverse with a mixed reproductive mode; comprising both sexual and clonal reproduction. Sexual reproduction of C. tanaceti was more prevalent in Tasmania than in Victoria. Little differentiation was observed among field populations likely due to isolation by colonization but most of the genetic variation was occurring within populations. C. tanaceti was likely to have had a long-distance gene and genotype flow among distant populations within a state and between states. Anthropogenic transmission of propagules and wind dispersal of ascospores are the most probable mechanisms of long-distance dispersal of C. tanaceti. Evaluation of putative population histories suggested that C. tanaceti most likely originated in Tasmania and expanded from an unidentified host onto pyrethrum. Victoria was later invaded by the Tasmanian population. With the mixed mode of reproduction and possible long-distance gene flow, C. tanaceti is likely to have a high evolutionary potential and thereby has ability to adapt to management practices in the future.
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Affiliation(s)
- Ruvini V Lelwala
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia 3010
| | - Jason B Scott
- Tasmanian Institute of Agriculture, University of Tasmania, Burnie, Tasmania, Australia 7320
| | - Peter K Ades
- School of Ecosystem and Forest Sciences, University of Melbourne, Victoria, Australia 3010
| | - Paul W J Taylor
- School of Agriculture and Food, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Victoria, Australia 3010
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Koenick LB, Vaghefi N, Knight NL, du Toit LJ, Pethybridge SJ. Genetic Diversity and Differentiation in Phoma betae Populations on Table Beet in New York and Washington States. PLANT DISEASE 2019; 103:1487-1497. [PMID: 31059387 DOI: 10.1094/pdis-09-18-1675-re] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Phoma betae is an important seedborne pathogen of table beet worldwide that is capable of causing foliar, root, and damping-off diseases. Ten microsatellite and mating type markers were developed to investigate the genetics of P. betae populations in table beet root crops in New York and in table beet seed crops in Washington, from where table beet seed is predominantly sourced. The markers were used to characterize 175 isolates comprising five P. betae populations (two from New York and three from Washington), and they were highly polymorphic with an allelic range of 4 to 33 and an average of 11.7 alleles per locus. All populations had high genotypic diversity (Simpson's complement index = 0.857 to 0.924) and moderate allelic diversity (Nei's unbiased gene diversity = 0.582 to 0.653). Greater differentiation observed between populations from the two states compared with populations within the same state suggested that an external inoculum source, such as windblown ascospores, may be homogenizing the populations. However, most genetic diversity (87%) was among individual isolates within populations (pairwise index of population differentiation = 0.127; P = 0.001), suggesting that local within-field inoculum source(s), such as infested field debris or infected weeds, may also be important in initiating disease outbreaks. Standardized index of association, proportion of compatible pairs of loci, and mating type ratio calculations showed evidence for a mixed reproduction mode in all populations. These findings could be useful in designing more effective management strategies for diseases caused by P. betae in table beet production.
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Affiliation(s)
- Lori B Koenick
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
| | - Niloofar Vaghefi
- 2 Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland 4350, Australia
| | - Noel L Knight
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
| | - Lindsey J du Toit
- 3 Washington State University, Mount Vernon Northwestern Washington Research and Extension Center, Mount Vernon, WA 98273, U.S.A
| | - Sarah J Pethybridge
- 1 Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456, U.S.A
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The Genome of the Human Pathogen Candida albicans Is Shaped by Mutation and Cryptic Sexual Recombination. mBio 2018; 9:mBio.01205-18. [PMID: 30228236 PMCID: PMC6143739 DOI: 10.1128/mbio.01205-18] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The opportunistic fungal pathogen Candida albicans lacks a conventional sexual program and is thought to evolve, at least primarily, through the clonal acquisition of genetic changes. Here, we performed an analysis of heterozygous diploid genomes from 21 clinical isolates to determine the natural evolutionary processes acting on the C. albicans genome. Mutation and recombination shaped the genomic landscape among the C. albicans isolates. Strain-specific single nucleotide polymorphisms (SNPs) and insertions/deletions (indels) clustered across the genome. Additionally, loss-of-heterozygosity (LOH) events contributed substantially to genotypic variation, with most long-tract LOH events extending to the ends of the chromosomes suggestive of repair via break-induced replication. Consistent with a model of inheritance by descent, most polymorphisms were shared between closely related strains. However, some isolates contained highly mosaic genomes consistent with strains having experienced interclade recombination during their evolutionary history. A detailed examination of mitochondrial genomes also revealed clear examples of interclade recombination among sequenced strains. These analyses therefore establish that both (para)sexual recombination and mitotic mutational processes drive evolution of this important pathogen. To further facilitate the study of C. albicans genomes, we also introduce an online platform, SNPMap, to examine SNP patterns in sequenced isolates.IMPORTANCE Mutations introduce variation into the genome upon which selection can act. Defining the nature of these changes is critical for determining species evolution, as well as for understanding the genetic changes driving important cellular processes. The heterozygous diploid fungus Candida albicans is both a frequent commensal organism and a prevalent opportunistic pathogen. A prevailing theory is that C. albicans evolves primarily through the gradual buildup of mitotic mutations, and a pressing issue is whether sexual or parasexual processes also operate within natural populations. Here, we establish that the C. albicans genome evolves by a combination of localized mutation and both short-tract and long-tract loss-of-heterozygosity (LOH) events within the sequenced isolates. Mutations are more prevalent within noncoding and heterozygous regions and LOH increases towards chromosome ends. Furthermore, we provide evidence for genetic exchange between isolates, establishing that sexual or parasexual processes have contributed to the diversity of both nuclear and mitochondrial genomes.
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Nuaima RH, Roeb J, Hallmann J, Daub M, Otte S, Heuer H. Effector gene vap1 based DGGE fingerprinting to assess variation within and among Heterodera schachtii populations. J Nematol 2018; 50:517-528. [PMID: 31094153 DOI: 10.21307/jofnem-2018-055] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Populations of beet cyst nematodes Heterodera schachtii vary in aggressiveness and virulence toward sugar beet varieties, but also in traits like host range, or decline rate in the field. Diversity of their essential pathogenicity gene vap1 is shaped by diversifying selection and gene flow. The authors developed a technique to study inter-population variation and intra-population diversity and dynamics of H. schachtii based on the gene vap1. Degenerate primers were designed to amplify, clone, and sequence this gene from diverse species and populations of cyst nematodes. This resulted in a high diversity of sequences for H. schachtii, and allowed to design non-degenerated primers to amplify a fragment suitable for sequence dependent separation of gene variants in denaturing gradient gel electrophoresis (DGGE). The developed primers span a highly variable intron and part of a slightly variable exon. A marker comprised of the 14 mostly detected gene variants was established for gel-to-gel comparisons. For individual juveniles up to six gene variants were resolved and substantial variation within and among cysts was observed. A fast and easy DNA extraction procedure for 20 pooled cysts was established, which provided DGGE patterns with high similarity among replicate samples from field populations. Permutation tests on pairwise similarities within and among populations showed significant differences among vap1 patterns of field populations of H. schachtii. Similarly, gene diversity as expressed by the Shannon index was statistically different among field populations. In conclusion, the DGGE technique is a fast and - compared to sequencing approaches - inexpensive tool to compare populations of H. schachtii and link observed biological characteristics to genetic pattern. Populations of beet cyst nematodes Heterodera schachtii vary in aggressiveness and virulence toward sugar beet varieties, but also in traits like host range, or decline rate in the field. Diversity of their essential pathogenicity gene vap1 is shaped by diversifying selection and gene flow. The authors developed a technique to study inter-population variation and intra-population diversity and dynamics of H. schachtii based on the gene vap1. Degenerate primers were designed to amplify, clone, and sequence this gene from diverse species and populations of cyst nematodes. This resulted in a high diversity of sequences for H. schachtii, and allowed to design non-degenerated primers to amplify a fragment suitable for sequence dependent separation of gene variants in denaturing gradient gel electrophoresis (DGGE). The developed primers span a highly variable intron and part of a slightly variable exon. A marker comprised of the 14 mostly detected gene variants was established for gel-to-gel comparisons. For individual juveniles up to six gene variants were resolved and substantial variation within and among cysts was observed. A fast and easy DNA extraction procedure for 20 pooled cysts was established, which provided DGGE patterns with high similarity among replicate samples from field populations. Permutation tests on pairwise similarities within and among populations showed significant differences among vap1 patterns of field populations of H. schachtii. Similarly, gene diversity as expressed by the Shannon index was statistically different among field populations. In conclusion, the DGGE technique is a fast and – compared to sequencing approaches – inexpensive tool to compare populations of H. schachtii and link observed biological characteristics to genetic pattern.
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Affiliation(s)
- Rasha Haj Nuaima
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics , Messeweg 11-12, 38104 Braunschweig , Germany ; Department of Plant Protection, Faculty of Agriculture, Euphrates University , Syria
| | - Johannes Roeb
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics , Toppheideweg 88, 48161 Münster , Germany
| | - Johannes Hallmann
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics , Toppheideweg 88, 48161 Münster , Germany
| | - Matthias Daub
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Plant Protection in Field Crops and Grassland , Dürener Str. 71, 50189 Elsdorf , Germany
| | - Sandra Otte
- Strube Research GmbH & Co. KG , Hauptstraße 1, 38387 Söllingen , Germany
| | - Holger Heuer
- Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics , Messeweg 11-12, 38104 Braunschweig , Germany
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Reich M, Labes A. How to boost marine fungal research: A first step towards a multidisciplinary approach by combining molecular fungal ecology and natural products chemistry. Mar Genomics 2017; 36:57-75. [PMID: 29031541 DOI: 10.1016/j.margen.2017.09.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 09/22/2017] [Accepted: 09/23/2017] [Indexed: 12/30/2022]
Abstract
Marine fungi have attracted attention in recent years due to increased appreciation of their functional role in ecosystems and as important sources of new natural products. The concomitant development of various "omic" technologies has boosted fungal research in the fields of biodiversity, physiological ecology and natural product biosynthesis. Each of these research areas has its own research agenda, scientific language and quality standards, which have so far hindered an interdisciplinary exchange. Inter- and transdisciplinary interactions are, however, vital for: (i) a detailed understanding of the ecological role of marine fungi, (ii) unlocking their hidden potential for natural product discovery, and (iii) designing access routes for biotechnological production. In this review and opinion paper, we describe the two different "worlds" of marine fungal natural product chemists and marine fungal molecular ecologists. The individual scientific approaches and tools employed are summarised and explained, and enriched with a first common glossary. We propose a strategy to find a multidisciplinary approach towards a comprehensive view on marine fungi and their chemical potential.
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Affiliation(s)
- Marlis Reich
- University of Bremen, BreMarE, NW2 B3320, Leobener Str. 5, D-28359 Bremen, Germany.
| | - Antje Labes
- Flensburg University of Applied Sciences, Kanzleistr. 91-93, D-24943 Flensburg, Germany.
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Grünwald NJ, Everhart SE, Knaus BJ, Kamvar ZN. Best Practices for Population Genetic Analyses. PHYTOPATHOLOGY 2017; 107:1000-1010. [PMID: 28513284 DOI: 10.1094/phyto-12-16-0425-rvw] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Population genetic analysis is a powerful tool to understand how pathogens emerge and adapt. However, determining the genetic structure of populations requires complex knowledge on a range of subtle skills that are often not explicitly stated in book chapters or review articles on population genetics. What is a good sampling strategy? How many isolates should I sample? How do I include positive and negative controls in my molecular assays? What marker system should I use? This review will attempt to address many of these practical questions that are often not readily answered from reading books or reviews on the topic, but emerge from discussions with colleagues and from practical experience. A further complication for microbial or pathogen populations is the frequent observation of clonality or partial clonality. Clonality invariably makes analyses of population data difficult because many assumptions underlying the theory from which analysis methods were derived are often violated. This review provides practical guidance on how to navigate through the complex web of data analyses of pathogens that may violate typical population genetics assumptions. We also provide resources and examples for analysis in the R programming environment.
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Affiliation(s)
- N J Grünwald
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - S E Everhart
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - B J Knaus
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
| | - Z N Kamvar
- First and third authors: Horticultural Crop Research Unit, USDA-ARS, Corvallis, OR; and second and fourth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis
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Ramdial H, Latchoo RK, Hosein FN, Rampersad SN. Phylogeny and Haplotype Analysis of Fungi Within the Fusarium incarnatum-equiseti Species Complex. PHYTOPATHOLOGY 2017; 107:109-120. [PMID: 27901448 DOI: 10.1094/phyto-05-16-0209-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Fusarium spp. are ranked among the top 10 most economically and scientifically important plant-pathogenic fungi in the world and are associated with plant diseases that include fruit decay of a number of crops. Fusarium isolates infecting bell pepper in Trinidad were identified based on sequence comparisons of the translation elongation factor gene (EF-1a) with sequences of Fusarium incarnatum-equiseti species complex (FIESC) verified in the FUSARIUM-ID database. Eighty-two isolates were identified as belonging to one of four phylogenetic species within the subclades FIESC-1, FIESC-15, FIESC-16, and FIESC-26, with the majority of isolates belonging to FIESC-15. A comparison of the level of DNA polymorphism and phylogenetic inference for sequences of the internal transcribed spacer region (ITS1-5.8S-ITS2) and EF-1a sequences for Trinidad and FUSARIUM-ID type species was carried out. The ITS sequences were less informative, had lower haplotype diversity and restricted haplotype distribution, and resulted in poor resolution and taxa placement in the consensus maximum-likelihood tree. EF-1a sequences enabled strongly supported phylogenetic inference with highly resolved branching patterns of the 30 phylogenetic species within the FIESC and placement of representative Trinidad isolates. Therefore, global phylogeny was inferred from EF-1a sequences representing 11 countries, and separation into distinct Incarnatum and Equiseti clades was again evident. In total, 42 haplotypes were identified: 12 were shared and the remaining were unique haplotypes. The most diverse haplotype was represented by sequences from China, Indonesia, Malaysia, and Trinidad and consisted exclusively of F. incarnatum isolates. Spain had the highest haplotype diversity, perhaps because both F. equiseti and F. incarnatum sequences were represented; followed by the United States, which contributed both F. equiseti and F. incarnatum sequences to the data set; then by countries representing Southeast Asia (China, Indonesia, Malaysia, Thailand, and Philippines) and Trinidad; both of these regions were represented by only F. incarnatum sequences. Trinidad shared two haplotypes with China and one haplotype with the United States for only F. incarnatum isolates. The findings of this study are important for devising disease management strategies and for understanding the phylogenetic relationships among members of the FIESC.
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Affiliation(s)
- H Ramdial
- The University of the West Indies, Department of Life Sciences, Faculty of Science and Technology, St. Augustine, Trinidad and Tobago, West Indies
| | - R K Latchoo
- The University of the West Indies, Department of Life Sciences, Faculty of Science and Technology, St. Augustine, Trinidad and Tobago, West Indies
| | - F N Hosein
- The University of the West Indies, Department of Life Sciences, Faculty of Science and Technology, St. Augustine, Trinidad and Tobago, West Indies
| | - S N Rampersad
- The University of the West Indies, Department of Life Sciences, Faculty of Science and Technology, St. Augustine, Trinidad and Tobago, West Indies
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Knaus BJ, Tabima JF, Davis CE, Judelson HS, Grünwald NJ. Genomic Analyses of Dominant U.S. Clonal Lineages of Phytophthora infestans Reveals a Shared Common Ancestry for Clonal Lineages US11 and US18 and a Lack of Recently Shared Ancestry Among All Other U.S. Lineages. PHYTOPATHOLOGY 2016; 106:1393-1403. [PMID: 27348344 DOI: 10.1094/phyto-10-15-0279-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Populations of the potato and tomato late-blight pathogen Phytophthora infestans are well known for emerging as novel clonal lineages. These successions of dominant clones have historically been named US1 through US24, in order of appearance, since their first characterization using molecular markers. Hypothetically, these lineages can emerge through divergence from other U.S. lineages, recombination among lineages, or as novel, independent lineages originating outside the United States. We tested for the presence of phylogenetic relationships among U.S. lineages using a population of 31 whole-genome sequences, including dominant U.S. clonal lineages as well as available samples from global populations. We analyzed ancestry of the whole mitochondrial genome and samples of nuclear loci, including supercontigs 1.1 and 1.5 as well as several previously characterized coding regions. We found support for a shared ancestry among lineages US11 and US18 from the mitochondrial genome as well as from one nuclear haplotype on each supercontig analyzed. The other nuclear haplotype from each sample assorted independently, indicating an independent ancestry. We found no support for emergence of any other of the U.S. lineages from a common ancestor shared with the other U.S. lineages. Each of the U.S. clonal lineages fit a model where populations of new clonal lineages emerge via migration from a source population that is sexual in nature and potentially located in central Mexico or elsewhere. This work provides novel insights into patterns of emergence of clonal lineages in plant pathogen genomes.
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Affiliation(s)
- B J Knaus
- First and fifth authors: Horticultural Crop Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330; second and fifth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and third and fourth authors: Department of Plant Pathology, University of California, Riverside 92521
| | - J F Tabima
- First and fifth authors: Horticultural Crop Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330; second and fifth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and third and fourth authors: Department of Plant Pathology, University of California, Riverside 92521
| | - C E Davis
- First and fifth authors: Horticultural Crop Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330; second and fifth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and third and fourth authors: Department of Plant Pathology, University of California, Riverside 92521
| | - H S Judelson
- First and fifth authors: Horticultural Crop Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330; second and fifth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and third and fourth authors: Department of Plant Pathology, University of California, Riverside 92521
| | - N J Grünwald
- First and fifth authors: Horticultural Crop Research Unit, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR 97330; second and fifth authors: Department of Botany and Plant Pathology, Oregon State University, Corvallis 97331; and third and fourth authors: Department of Plant Pathology, University of California, Riverside 92521
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Sánchez-Ramírez S, Tulloss RE, Guzmán-Dávalos L, Cifuentes-Blanco J, Valenzuela R, Estrada-Torres A, Ruán-Soto F, Díaz-Moreno R, Hernández-Rico N, Torres-Gómez M, León H, Moncalvo JM. In and out of refugia: historical patterns of diversity and demography in the North American Caesar's mushroom species complex. Mol Ecol 2015; 24:5938-56. [PMID: 26465233 DOI: 10.1111/mec.13413] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 11/30/2022]
Abstract
Some of the effects of past climate dynamics on plant and animal diversity make-up have been relatively well studied, but to less extent in fungi. Pleistocene refugia are thought to harbour high biological diversity (i.e. phylogenetic lineages and genetic diversity), mainly as a product of increased reproductive isolation and allele conservation. In addition, high extinction rates and genetic erosion are expected in previously glaciated regions. Some of the consequences of past climate dynamics might involve changes in range and population size that can result in divergence and incipient or cryptic speciation. Many of these dynamic processes and patterns can be inferred through phylogenetic and coalescent methods. In this study, we first delimit species within a group of closely related edible ectomycorrhizal Amanita from North America (the American Caesar's mushrooms species complex) using multilocus coalescent-based approaches; and then address questions related to effects of Pleistocene climate change on the diversity and genetics of the group. Our study includes extensive geographical sampling throughout the distribution range, and DNA sequences from three nuclear protein-coding genes. Results reveal cryptic diversity and high speciation rates in refugia. Population sizes and expansions seem to be larger at midrange latitudes (Mexican highlands and SE USA). Range shifts are proportional to population size expansions, which were overall more common during the Pleistocene. This study documents responses to past climate change in fungi and also highlights the applicability of the multispecies coalescent in comparative phylogeographical analyses and diversity assessments that include ancestral species.
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Affiliation(s)
- Santiago Sánchez-Ramírez
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, ON, M5S 3B2, Canada
| | | | - Laura Guzmán-Dávalos
- Departamento de Botánica y Zoología, Universidad de Guadalajara, Zapopan, 45101, México
| | - Joaquín Cifuentes-Blanco
- Facultad de Ciencias, Departamento de Biología Comparada, UNAM, Ciudad Universitaria, México City, 04510, México
| | - Ricardo Valenzuela
- Escuela Nacional de Ciencias Biólogicas, Instituto Politécnico Nacional, México City, 11340, México
| | - Arturo Estrada-Torres
- Centro de Investigación en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, 90122, México
| | - Felipe Ruán-Soto
- Facultad de Ciencias Biológicas, Universidad de Ciencias y Artes de Chiapas, Tuxtla Gutiérrez, 29039, Mexico
| | - Raúl Díaz-Moreno
- Instituto de Silvicultura e Industria de la Madera, Universidad Juárez del Estado de Durango, Durango, 34120, México
| | - Nallely Hernández-Rico
- Laboratorio de Etnobiología, Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, Pachuca, México
| | - Mariano Torres-Gómez
- Centro de Investigaciones en Ecosistemas CIEco, Antigua carretera a Pátzcuaro # 8701, Col. Ex-Hacienda de San José de La Huerta, Morelia, 58190, México
| | - Hugo León
- Coleccion Etnomicológica "Dr. Teófilo Herrera Suárez", Instituto Tecnológico del Valle de Oaxaca, Xoxocotlán, 71230, México
| | - Jean-Marc Moncalvo
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks, Toronto, ON, M5S 3B2, Canada
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Begoude Boyogueno AD, Slippers B, Perez G, Wingfield MJ, Roux J. High gene flow and outcrossing within populations of two cryptic fungal pathogens on a native and non-native host in Cameroon. Fungal Biol 2012; 116:343-53. [DOI: 10.1016/j.funbio.2011.12.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 12/05/2011] [Accepted: 12/05/2011] [Indexed: 11/16/2022]
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Grünwald NJ, Goss EM. Evolution and population genetics of exotic and re-emerging pathogens: novel tools and approaches. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:249-267. [PMID: 21370974 DOI: 10.1146/annurev-phyto-072910-095246] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Given human population growth and accelerated global trade, the rate of emergence of exotic plant pathogens is bound to increase. Understanding the processes that lead to the emergence of new pathogens can help manage emerging epidemics. Novel tools for analyzing population genetic variation can be used to infer the evolutionary history of populations or species, allowing for the unprecedented reconstruction of the demographic history of pathogens. Specifically, recent advances in the application of coalescent, maximum likelihood (ML), and Bayesian methods to population genetic data combined with increasing availability of affordable sequencing and parallel computing have created the opportunity to apply these methods to a broad range of questions regarding the evolution of emerging pathogens. These approaches are particularly powerful when used to test multiple competing hypotheses. We provide several examples illustrating how coalescent analysis provides critical insights into understanding migration pathways as well as processes of divergence, speciation, and recombination.
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Affiliation(s)
- Niklaus J Grünwald
- Horticultural Crops Research Laboratory, USDA Agricultural Research Service, Corvallis, Oregon 97330, USA.
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Speciation of a tropical fungal species pair following transoceanic dispersal. Mol Phylogenet Evol 2009; 51:413-26. [DOI: 10.1016/j.ympev.2009.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Revised: 12/01/2008] [Accepted: 03/12/2009] [Indexed: 10/21/2022]
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Munkacsi AB, Stoxen S, May G. Ustilago maydis populations tracked maize through domestication and cultivation in the Americas. Proc Biol Sci 2008; 275:1037-46. [PMID: 18252671 PMCID: PMC2366215 DOI: 10.1098/rspb.2007.1636] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 01/11/2008] [Accepted: 01/14/2008] [Indexed: 11/12/2022] Open
Abstract
The domestication of crops and the development of agricultural societies not only brought about major changes in human interactions with the environment but also in plants' interactions with the diseases that challenge them. We evaluated the impact of the domestication of maize from teosinte and the widespread cultivation of maize on the historical demography of Ustilago maydis, a fungal pathogen of maize. To determine the evolutionary response of the pathogen's populations, we obtained multilocus genotypes for 1088 U. maydis diploid individuals from two teosinte subspecies in Mexico and from maize in Mexico and throughout the Americas. Results identified five major U. maydis populations: two in Mexico; two in South America; and one in the United States. The two populations in Mexico diverged from the other populations at times comparable to those for the domestication of maize at 6000-10000 years before present. Maize domestication and agriculture enforced sweeping changes in U. maydis populations such that the standing variation in extant pathogen populations reflects evolution only since the time of the crop's domestication.
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Affiliation(s)
- Andrew B Munkacsi
- Plant Biological Sciences Graduate Program, University of MinnesotaSt Paul, MN 55108, USA
- The Center for Community Genetics, University of MinnesotaSt Paul, MN 55108, USA
| | - Sam Stoxen
- Department of Ecology, Evolution and Behavior, University of MinnesotaSt Paul, MN 55108, USA
| | - Georgiana May
- The Center for Community Genetics, University of MinnesotaSt Paul, MN 55108, USA
- Department of Ecology, Evolution and Behavior, University of MinnesotaSt Paul, MN 55108, USA
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Community structure of Phialocephala fortinii s. lat. in European tree nurseries, and assessment of the potential of the seedlings as dissemination vehicles. ACTA ACUST UNITED AC 2008; 112:650-62. [PMID: 18495453 DOI: 10.1016/j.mycres.2007.12.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 10/26/2007] [Accepted: 12/10/2007] [Indexed: 11/21/2022]
Abstract
Patterns of colonization of conifer roots by dark septate endopyhtes of the Phialocephala fortinii s. lat. species complex in nurseries in Switzerland and Lithuania were studied. The potential for man-mediated genotype flow was estimated for two Swiss nurseries based on customers' addresses and the number of delivered plants. Two hundred and forty-nine strains from three Swiss and five Lithuanian nurseries and an afforestation site were characterized using a combination of inter-simple sequence repeat-anchored PCR (ISSR-PCR), single-copy RFLP analysis, and sequence analysis. P. fortinii s. lat. was abundant in nursery seedlings, but the frequency of seedlings colonized varied considerably among and within nurseries. Ten cryptic species (CSP) of P. fortinii s. lat. were identified, including four hitherto undiscovered CSP. P. helvetica was the dominant species in Swiss nurseries, whereas P. fortinii s. str. was the most abundant species in Lithuanian nurseries and the afforestation site. Swiss nurseries deliver plants over distances of more than 200km indicating the high potential for man-mediated genotype flow in P. fortinii s. lat.
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Crouch JA, Clarke BB, Hillman BI. Unraveling evolutionary relationships among the divergent lineages of colletotrichum causing anthracnose disease in turfgrass and corn. PHYTOPATHOLOGY 2006; 96:46-60. [PMID: 18944204 DOI: 10.1094/phyto-96-0046] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
ABSTRACT Colletotrichum species cause anthracnose diseases on a number of grass hosts and are common inhabitants of many others. They are divided into four species: C. sublineolum is pathogenic to Sorghum spp.; C. caudatum is found on C4 grasses such as indiangrass and big bluestem; C. falcatum causes red rot of sugarcane; and C. graminicola sensu lato is a broadly defined species including isolates that attack maize, wheat, oats, and many forage, turf, and amenity grasses of the subfamily Pooideae. In this paper, a combination of hierarchal- and nonhierarchal-based analyses were employed to examine evolutionary relationships among the grass-infecting Colletotrichum species, with special emphasis on isolates from turf and other grasses in the subfamily Pooideae. Reconstructions performed with data sets from over 100 Colletotrichum isolates at three variable loci using phylogenetic and network-based methodologies unambiguously supported the taxonomic separation of maize-infecting isolates of C. graminicola from the pooid-infecting strains of Colletotrichum. To reflect the evolutionary relationships that exist between these distinct lineages, we propose the resurrection of the species name C. cereale to describe the pooid-infecting isolates. There was also support for further subdivision of C. cereale, but the current data are insufficient to confidently subdivide the species, as there was some evidence of recombination between lineages of this species.
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Banke S, McDonald BA. Migration patterns among global populations of the pathogenic fungus Mycosphaerella graminicola. Mol Ecol 2005; 14:1881-96. [PMID: 15910313 DOI: 10.1111/j.1365-294x.2005.02536.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
DNA sequences from five nuclear loci and data from three microsatellites were collected from 360 isolates representing 14 globally distributed populations of the plant pathogenic fungus Mycosphaerella graminicola. Haplotype networks were constructed for the five sequence loci and population subdivision was assessed using Hudson's permutation test. Migration estimates were calculated using six regional populations for both the sequence and microsatellite loci. While subdivision was detected among the six regional populations, significant gene flow was indicated among some of the populations. The European and Israeli populations contributed the majority of historical immigrants to the New World. Migration estimates for microsatellite loci were used to infer more recent migration events among specific New World populations. We conclude that gene flow was an important factor in determining the demographic history of Mycosphaerella graminicola.
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Affiliation(s)
- S Banke
- Institute for Plant Sciences, Phytopathology Group, Federal Institute of Technology, ETH-Zentrum, LFW, Universitätstrasse 2, 8092, Zürich, Switzerland.
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Abstract
The objective of this review is to provide a synthesis of speciation theory, of what is known about mechanisms of speciation in fungi and from this, what is expected, and of ideas on how speciation can be elucidated in more fungal systems. The emphasis is on process rather than pattern. Phylogeographic studies in some groups, such as the agarics, demonstrate predominantly allopatric speciation, often through vicariance, as seen in many plants and animals. The variety of life history factors in fungi suggests, however, a diversity in speciation mechanisms that is borne out in comparison of some key examples. Life history features in fungi with a bearing on speciation include genetic mechanisms for intra- and interspecies interactions, haploidy as monokaryons, dikaryons, or coenocytes, distinctive types of propagules with distinctive modes of dispersal, as well as characteristic relationships to the substrate or host as specialized or generalist saprotrophs, parasites or mutualists with associated opportunities and selective pressures for hybridization. Approaches are proposed for both retrospective, phylogeographic determination of speciation mechanisms, and experimental studies with the potential for genomic applications, particularly in examining the relationship between adaptation and reproductive isolation.
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Affiliation(s)
- Linda M Kohn
- Department of Botany, University of Toronto, Mississauga, Ontario, Canada L5L 1C6.
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