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Hietala AM, Agan A, Nagy NE, Børja I, Timmermann V, Drenkhan R, Solheim H. The Native Hymenoscyphus albidus and the Invasive Hymenoscyphus fraxineus Are Similar in Their Necrotrophic Growth Phase in Ash Leaves. Front Microbiol 2022; 13:892051. [PMID: 35711744 PMCID: PMC9196304 DOI: 10.3389/fmicb.2022.892051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/02/2022] [Indexed: 11/13/2022] Open
Abstract
The populations of European ash and its harmless fungal associate Hymenoscyphus albidus are in decline owing to ash dieback caused by the invasive Hymenoscyphus fraxineus, a fungus that in its native range in Asia is a harmless leaf endophyte of local ash species. To clarify the behavior of H. albidus and its spatial and temporal niche overlap with the invasive relative, we used light microscopy, fungal species-specific qPCR assays, and PacBio long-read amplicon sequencing of the ITS1-5.8S-ITS2 region to examine fungal growth and species composition in attached leaves of European ash. The plant material was collected from a healthy stand in central Norway, where ash saplings in late autumn showed leaflet vein necrosis like that commonly related to H. fraxineus. For reference, leaflet samples were analyzed from stands with epidemic level of ash dieback in southeastern Norway and Estonia. While H. albidus was predominant in the necrotic veins in the healthy stand, H. fraxineus was predominant in the diseased stands. Otherwise, endophytes with pathogenic potential in the genera Venturia (anamorph Fusicladium), Mycosphaerella (anamorph Ramularia), and Phoma, and basidiomycetous yeasts formed the core leaflet mycobiome both in the healthy and diseased stands. In necrotic leaf areas with high levels of either H. albidus or H. fraxineus DNA, one common feature was the high colonization of sclerenchyma and phloem, a region from which the ascomata of both species arise. Our data suggest that H. albidus can induce necrosis in ash leaves, but that owing to low infection pressure, this first takes place in tissues weakened by autumn senescence, 1-2 months later in the season than what is characteristic of H. fraxineus at an epidemic phase of ash dieback. The most striking difference between these fungi would appear to be the high fecundity of H. fraxineus. The adaptation to a host that is phylogenetically closely related to European ash, a tree species with high occurrence frequency in Europe, and the presence of environmental conditions favorable to H. fraxineus life cycle completion in most years may enable the build-up of high infection pressure and challenge of leaf defense prior to autumn senescence.
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Affiliation(s)
- Ari M Hietala
- Norwegian Institute of Bioeconomy Research, Steinkjer, Norway
| | - Ahto Agan
- Institute of Forestry and Engineering, Estonian University of Life Sciences, Tartu, Estonia
| | - Nina E Nagy
- Norwegian Institute of Bioeconomy Research, Ås, Norway
| | | | | | - Rein Drenkhan
- Institute of Forestry and Engineering, Estonian University of Life Sciences, Tartu, Estonia
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2
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Cheng Q, Yang H, Chen J, Zhao L. Population Genomics Reveals Population Structure and Mating-Type Loci in Marssonina brunnea. J Fungi (Basel) 2022; 8:jof8060579. [PMID: 35736062 PMCID: PMC9225152 DOI: 10.3390/jof8060579] [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: 04/25/2022] [Revised: 05/21/2022] [Accepted: 05/24/2022] [Indexed: 12/12/2022] Open
Abstract
Marssonina brunnea is an important fungal pathogen of poplar trees. We collected 32 M. brunnea f.sp. multigermtubi (MbMu) and three M. brunnea f.sp. monogermtubi (MbMo) isolates from four poplar species in three Chinese regions and performed genome resequencing. An annotation of SNPs of MbMu indicated that the SNPs potentially have a functional effect on 69.2% of the predicted genes. Using the SNP dataset of nonredundant isolates, a structure and principal component analysis revealed that MbMu and MbMo belong to two genetically distinct populations. By contrast, subpopulation structures could not be found among MbMu isolates. A neighbor-net analysis and a homoplasy index test provided evidence of recombination among MbMu isolates. The short distance (109–174 bp) of linkage disequilibrium half-decay supported the presence of a high level of recombination in the MbMu population. The genetic architectures of the MAT loci of MbMu and MbMo were revealed by searching genome assemblies or by homology-based cloning, and a BLAST search verified each isolate carrying one of the two opposite MAT loci. This study revealed that the MbMu population contains a wide range of functional variants, shows high-frequency recombination, and exhibits heterothallic mating systems, indicating high evolutionary potential and a resultant threat to poplar plantations.
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3
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Yuan Z, Wu Q, Xu L, Druzhinina IS, Stukenbrock EH, Nieuwenhuis BPS, Zhong Z, Liu ZJ, Wang X, Cai F, Kubicek CP, Shan X, Wang J, Shi G, Peng L, Martin FM. Genomic landscape of a relict fir-associated fungus reveals rapid convergent adaptation towards endophytism. THE ISME JOURNAL 2022; 16:1294-1305. [PMID: 34916613 PMCID: PMC9038928 DOI: 10.1038/s41396-021-01176-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/02/2021] [Accepted: 12/08/2021] [Indexed: 12/24/2022]
Abstract
Comparative and pan-genomic analyses of the endophytic fungus Pezicula neosporulosa (Helotiales, Ascomycota) from needles of the relict fir, Abies beshanzuensis, showed expansions of carbohydrate metabolism and secondary metabolite biosynthetic genes characteristic for unrelated plant-beneficial helotialean, such as dark septate endophytes and ericoid mycorrhizal fungi. The current species within the relatively young Pliocene genus Pezicula are predominantly saprotrophic, while P. neosporulosa lacks such features. To understand the genomic background of this putatively convergent evolution, we performed population analyses of 77 P. neosporulosa isolates. This revealed a mosaic structure of a dozen non-recombining and highly genetically polymorphic subpopulations with a unique mating system structure. We found that one idiomorph of a probably duplicated mat1-2 gene was found in putatively heterothallic isolates, while the other co-occurred with mat1-1 locus suggesting homothallic reproduction for these strains. Moreover, 24 and 81 genes implicated in plant cell-wall degradation and secondary metabolite biosynthesis, respectively, showed signatures of the balancing selection. These findings highlight the evolutionary pattern of the two gene families for allowing the fungus a rapid adaptation towards endophytism and facilitating diverse symbiotic interactions.
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Affiliation(s)
- Zhilin Yuan
- State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, 100091, Beijing, China. .,Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, 311400, China.
| | - Qi Wu
- grid.458488.d0000 0004 0627 1442State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
| | - Liangxiong Xu
- grid.411411.00000 0004 0644 5457School of Life Sciences, Huizhou University, Huizhou, 516007 China
| | - Irina S. Druzhinina
- grid.27871.3b0000 0000 9750 7019Key Laboratory of Plant Immunity, Fungal Genomics Laboratory (FungiG), College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China ,grid.5329.d0000 0001 2348 4034Institute of Chemical, Environmental & Bioscience Engineering (ICEBE), TU Wien, Vienna, A1060 Austria
| | - Eva H. Stukenbrock
- grid.9764.c0000 0001 2153 9986Botanical Institute, Christian-Albrechts Universität zu Kiel, 24118 Kiel, Germany ,grid.419520.b0000 0001 2222 4708Environmental Genomics Research Group, Max-Planck Institute for Evolutionary Biology, 24306 Plön, Germany
| | - Bart P. S. Nieuwenhuis
- grid.5252.00000 0004 1936 973XDivision of Evolutionary Biology, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Zhenhui Zhong
- grid.256111.00000 0004 1760 2876State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002 China ,grid.19006.3e0000 0000 9632 6718Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095 USA
| | - Zhong-Jian Liu
- grid.256111.00000 0004 1760 2876Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization at College of Landscape Architecture, Fujian Agriculture and Forestry University, Fuzhou, 350002 China
| | - Xinyu Wang
- grid.509676.bResearch Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, 311400 China
| | - Feng Cai
- grid.27871.3b0000 0000 9750 7019Key Laboratory of Plant Immunity, Fungal Genomics Laboratory (FungiG), College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China
| | - Christian P. Kubicek
- grid.5329.d0000 0001 2348 4034Institute of Chemical, Environmental & Bioscience Engineering (ICEBE), TU Wien, Vienna, A1060 Austria
| | - Xiaoliang Shan
- grid.216566.00000 0001 2104 9346State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, 100091 Beijing, China ,grid.509676.bResearch Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, 311400 China
| | - Jieyu Wang
- grid.458495.10000 0001 1014 7864Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650 China
| | - Guohui Shi
- grid.458488.d0000 0004 0627 1442State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101 Beijing, China
| | - Long Peng
- grid.216566.00000 0001 2104 9346State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, 100091 Beijing, China ,grid.509676.bResearch Institute of Subtropical Forestry, Chinese Academy of Forestry, Hangzhou, 311400 China
| | - Francis M. Martin
- grid.29172.3f0000 0001 2194 6418Université de Lorraine, INRAe, UMR 1136 Interactions Arbres/Microorganismes, INRAe-Grand Est-Nancy, 54280 Champenoux, France
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4
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Genomic patterns and the evolutionary origin of an invasive fungal pathogen (Hymenoscyphus fraxineus) in Europe. Basic Appl Ecol 2022. [DOI: 10.1016/j.baae.2021.12.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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5
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Hymenoscyphus fraxineus on Fraxinus excelsior in Slovakia: distribution and mating types. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01023-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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6
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Elfstrand M, Chen J, Cleary M, Halecker S, Ihrmark K, Karlsson M, Davydenko K, Stenlid J, Stadler M, Durling MB. Comparative analyses of the Hymenoscyphus fraxineus and Hymenoscyphus albidus genomes reveals potentially adaptive differences in secondary metabolite and transposable element repertoires. BMC Genomics 2021; 22:503. [PMID: 34217229 PMCID: PMC8254937 DOI: 10.1186/s12864-021-07837-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 06/24/2021] [Indexed: 11/29/2022] Open
Abstract
Background The dieback epidemic decimating common ash (Fraxinus excelsior) in Europe is caused by the invasive fungus Hymenoscyphus fraxineus. In this study we analyzed the genomes of H. fraxineus and H. albidus, its native but, now essentially displaced, non-pathogenic sister species, and compared them with several other members of Helotiales. The focus of the analyses was to identify signals in the genome that may explain the rapid establishment of H. fraxineus and displacement of H. albidus. Results The genomes of H. fraxineus and H. albidus showed a high level of synteny and identity. The assembly of H. fraxineus is 13 Mb longer than that of H. albidus’, most of this difference can be attributed to higher dispersed repeat content (i.e. transposable elements [TEs]) in H. fraxineus. In general, TE families in H. fraxineus showed more signals of repeat-induced point mutations (RIP) than in H. albidus, especially in Long-terminal repeat (LTR)/Copia and LTR/Gypsy elements. Comparing gene family expansions and 1:1 orthologs, relatively few genes show signs of positive selection between species. However, several of those did appeared to be associated with secondary metabolite genes families, including gene families containing two of the genes in the H. fraxineus-specific, hymenosetin biosynthetic gene cluster (BGC). Conclusion The genomes of H. fraxineus and H. albidus show a high degree of synteny, and are rich in both TEs and BGCs, but the genomic signatures also indicated that H. albidus may be less well equipped to adapt and maintain its ecological niche in a rapidly changing environment. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07837-2.
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Affiliation(s)
- Malin Elfstrand
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.
| | - Jun Chen
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.,Systematic & Evolutionary Botany and Biodiversity group, MOE Laboratory of Biosystem Homeostasis and Protection, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Michelle Cleary
- Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Sundsvägen 3, Box 49, SE-230 53, Alnarp, Sweden
| | - Sandra Halecker
- Dept. Microbial Drugs, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124, Braunschweig, Germany
| | - Katarina Ihrmark
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Magnus Karlsson
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Kateryna Davydenko
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden.,Ukrainian research Institute of Forestry and Forest Melioration, 62458, Kharkov, Ukraine
| | - Jan Stenlid
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
| | - Marc Stadler
- Dept. Microbial Drugs, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124, Braunschweig, Germany
| | - Mikael Brandström Durling
- Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7026, SE-750 07, Uppsala, Sweden
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7
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Detection of a Conspecific Mycovirus in Two Closely Related Native and Introduced Fungal Hosts and Evidence for Interspecific Virus Transmission. Viruses 2018; 10:v10110628. [PMID: 30428556 PMCID: PMC6266060 DOI: 10.3390/v10110628] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 11/09/2018] [Accepted: 11/10/2018] [Indexed: 11/17/2022] Open
Abstract
Hymenoscyphus albidus is a native fungus in Europe where it behaves as a harmless decomposer of leaves of common ash. Its close relative Hymenoscyphus fraxineus was introduced into Europe from Asia and currently threatens ash (Fraxinus sp.) stands all across the continent causing ash dieback. H. fraxineus isolates from Europe were previously shown to harbor a mycovirus named Hymenoscyphus fraxineus Mitovirus 1 (HfMV1). In the present study, we describe a conspecific mycovirus that we detected in H. albidus. HfMV1 was consistently identified in H. albidus isolates (mean prevalence: 49.3%) which were collected in the sampling areas before the arrival of ash dieback. HfMV1 strains in both fungal hosts contain a single ORF of identical length (717 AA) for which a mean pairwise identity of 94.5% was revealed. The occurrence of a conspecific mitovirus in H. albidus and H. fraxineus is most likely the result of parallel virus evolution in the two fungal hosts. HfMV1 sequences from H. albidus showed a higher nucleotide diversity and a higher number of mutations compared to those from H. fraxineus, probably due to a bottleneck caused by the introduction of H. fraxineus in Europe. Our data also points to multiple interspecific virus transfers from H. albidus to H. fraxineus, which could have contributed to the intraspecific virus diversity found in H. fraxineus.
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8
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Hietala AM, Børja I, Solheim H, Nagy NE, Timmermann V. Propagule Pressure Build-Up by the Invasive Hymenoscyphus fraxineus Following Its Introduction to an Ash Forest Inhabited by the Native Hymenoscyphus albidus. FRONTIERS IN PLANT SCIENCE 2018; 9:1087. [PMID: 30105041 PMCID: PMC6077690 DOI: 10.3389/fpls.2018.01087] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/05/2018] [Indexed: 06/02/2023]
Abstract
Dieback of European ash, caused by the ascomycete Hymenoscyphus fraxineus originating from Asia, has rapidly spread across Europe, and is threatening this keystone tree at a continental scale. High propagule pressure is characteristic to invasive species. Consistently, the enormous production of windborne ascospores by H. fraxineus in an ash forest with epidemic level of disease obviously facilitates its invasiveness and long distance spread. To understand the rate of build-up of propagule pressure by this pathogen following its local introduction, during 2011-2017 we monitored its sporulation at a newly infested ash stand in south-western Norway characterized with mild winters and cool summers. We also monitored the propagule pressure by Hymenoscyphus albidus, a non-pathogenic native species that competes for the same sporulation niche with H. fraxineus. During the monitoring period, crown condition of ash trees had impaired, and 20% of the dominant trees were severely damaged in 2017. H. fraxineus showed an exponential increase in spore production between 2012 and 2015, followed by drastic decline in 2016 and 2017. During 2011-2013, the two Hymenoscyphus species showed similar sporulation level, but thereafter spores of H. albidus were no longer detected. The data suggest that following local introduction, the population of H. fraxineus reaches rapidly an exponential growth stage if the local weather conditions are favorable for ascomata maturation across years. In the North Atlantic climate, summer temperatures critically influence the pathogen infection pressure, warm summers allowing the population to grow according to its biotic potential, whereas cold summers can cause a drastic decline in propagule pressure.
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Affiliation(s)
- Ari M. Hietala
- Department of Forest Health, Norwegian Institute of Bioeconomy Research, Ås, Norway
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9
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McMullan M, Rafiqi M, Kaithakottil G, Clavijo BJ, Bilham L, Orton E, Percival-Alwyn L, Ward BJ, Edwards A, Saunders DGO, Garcia Accinelli G, Wright J, Verweij W, Koutsovoulos G, Yoshida K, Hosoya T, Williamson L, Jennings P, Ioos R, Husson C, Hietala AM, Vivian-Smith A, Solheim H, MaClean D, Fosker C, Hall N, Brown JKM, Swarbreck D, Blaxter M, Downie JA, Clark MD. The ash dieback invasion of Europe was founded by two genetically divergent individuals. Nat Ecol Evol 2018; 2:1000-1008. [PMID: 29686237 PMCID: PMC5969572 DOI: 10.1038/s41559-018-0548-9] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 03/27/2018] [Indexed: 11/22/2022]
Abstract
Accelerating international trade and climate change make pathogen spread an increasing concern. Hymenoscyphus fraxineus, the causal agent of ash dieback, is a fungal pathogen that has been moving across continents and hosts from Asian to European ash. Most European common ash trees (Fraxinus excelsior) are highly susceptible to H. fraxineus, although a minority (~5%) have partial resistance to dieback. Here, we assemble and annotate a H. fraxineus draft genome which approaches chromosome scale. Pathogen genetic diversity across Europe and in Japan, reveals a strong bottleneck in Europe, though a signal of adaptive diversity remains in key host interaction genes. We find that the European population was founded by two divergent haploid individuals. Divergence between these haplotypes represents the ancestral polymorphism within a large source population. Subsequent introduction from this source would greatly increase adaptive potential of the pathogen. Thus, further introgression of H. fraxineus into Europe represents a potential threat and Europe-wide biological security measures are needed to manage this disease.
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Affiliation(s)
- Mark McMullan
- The Earlham Institute, Norwich Research Park, Norwich, UK.
| | | | | | | | | | | | | | - Ben J Ward
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | - Anne Edwards
- John Innes Centre, Norwich Research Park, Norwich, UK
| | | | | | | | - Walter Verweij
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | | | - Kentaro Yoshida
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK.,Graduate school of Agricultural Science, Kobe University, Kobe, Hyogo, Japan
| | - Tsuyoshi Hosoya
- Department of Botany, National Museum of Nature and Science, Tsukuba, Ibaraki, Japan
| | | | | | - Renaud Ioos
- ANSES Laboratoire de la Santé des Végétaux, Malzéville, France
| | | | - Ari M Hietala
- Norwegian Institute of Bioeconomy Research, Ås, Norway
| | | | | | - Dan MaClean
- The Sainsbury Laboratory, Norwich Research Park, Norwich, UK
| | | | - Neil Hall
- The Earlham Institute, Norwich Research Park, Norwich, UK
| | | | | | - Mark Blaxter
- Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh, UK.,Edinburgh Genomics, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | | | - Matthew D Clark
- The Earlham Institute, Norwich Research Park, Norwich, UK. .,Department of Life Sciences, Natural History Museum, London, UK.
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10
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Robicheau BM, Bunbury-Blanchette AL, LaButti K, Grigoriev IV, Walker AK. The homothallic mating-type locus of the conifer needle endophyte Phialocephala scopiformis DAOMC 229536 (order Helotiales). Fungal Biol 2017; 121:1011-1024. [PMID: 29122173 DOI: 10.1016/j.funbio.2017.08.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 08/11/2017] [Accepted: 08/22/2017] [Indexed: 12/14/2022]
Abstract
We describe the complete mating-type (MAT) locus for Phialocephala scopiformis Canadian Collection of Fungal Cultures (DAOMC) 229536 - a basal lineage within Vibrisseaceae. This strain is of interest due to its ability to produce the important antiinsectan rugulosin. We also provide some of the first insights into the genome structure and gene inventory of nonclavicipitalean endophytes. Sequence was obtained through shotgun sequencing of the entire P. scopiformis genome, and the MAT locus was then determined by comparing this genomic sequence to known MAT loci within the Phialocephala fortinii s.l.-Acephala applanata species complex. We also tested the relative levels of sequence conservation for MAT genes within Vibrisseaceae (n = 10), as well as within the Helotiales (n = 27). Our results: (1) show a homothallic gene arrangement for P. scopiformis [MAT1-1-1, MAT1-2-1, and MAT1-1-3 genes are present], (2) increase the genomic survey of homothallism within Vibrisseaceae, (3) confirm that P. scopiformis contains a unique S-adenosyl-l-methionine-dependent methyltransferase (SAM-Mtase) gene proximal to its MAT locus, while also lacking a cytoskeleton assembly control protein (sla2) gene, and (4) indicate that MAT1-1-1 is the more useful molecular marker amongst the MAT genes for phylogenetic reconstructions aimed at tracking evolutionary shifts in reproductive strategy and/or MAT loci gene composition within the Helotiales.
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Affiliation(s)
- Brent M Robicheau
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia B4P 2R6, Canada.
| | | | - Kurt LaButti
- U.S. Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA 94598, USA
| | - Igor V Grigoriev
- U.S. Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA 94598, USA; Department of Plant and Microbial Biology, UC Berkeley, 111 Koshland Hall, Berkeley, California 94720, USA
| | - Allison K Walker
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia B4P 2R6, Canada
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11
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Li HX, Gottilla TM, Brewer MT. Organization and evolution of mating-type genes in three Stagonosporopsis species causing gummy stem blight of cucurbits and leaf spot and dry rot of papaya. Fungal Biol 2017; 121:849-857. [PMID: 28889909 DOI: 10.1016/j.funbio.2017.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/12/2017] [Accepted: 06/13/2017] [Indexed: 11/25/2022]
Abstract
Population divergence and speciation of closely related lineages can result from reproductive differences leading to genetic isolation. An increasing number of fungal diseases of plants and animals have been determined to be caused by morphologically indistinguishable species that are genetically distinct, thereby representing cryptic species. We were interested in identifying if mating systems among three Stagonosporopsis species (S. citrulli, S. cucurbitacearum, and S. caricae) causing gummy stem blight (GSB) of cucurbits or leaf spot and dry rot of papaya differed, possibly underlying species divergence. Additionally, we were interested in identifying evolutionary pressures acting on the genes controlling mating in these fungi. The mating-type loci (MAT1) of three isolates from each of the three species were identified in draft genome sequences. For the three species, MAT1 was structurally identical and contained both mating-type genes necessary for sexual reproduction, which suggests that all three species are homothallic. However, both MAT1-1-1 and MAT1-2-1 were divergent among species showing rapid evolution with a much greater number of amino acid-changing substitutions detected for the reproductive genes compared with genes flanking MAT1. Positive selection was detected in MAT1-2-1, especially in the highly conserved high mobility group (MATA_HMG-box) domain. Thus, the mating-type genes are rapidly evolving in GSB fungi, but a difference in mating systems among the three species does not underlie their divergence.
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Affiliation(s)
- Hao-Xi Li
- Department of Plant Pathology, University of Georgia, Athens 30602, USA
| | - Thomas M Gottilla
- Department of Plant Pathology, University of Georgia, Athens 30602, USA
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12
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Brasier C, King K, Kirisits T, Orton E, Webber J. High frequency of vegetative incompatibility combined with haploid selfing in the native European ash foliage coloniser Hymenoscyphus albidus. FUNGAL ECOL 2017. [DOI: 10.1016/j.funeco.2017.04.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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13
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Affiliation(s)
- J. Allan Downie
- John Innes Centre, Norwich Research Park, Norwich, United Kingdom
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14
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Fones HN, Mardon C, Gurr SJ. A role for the asexual spores in infection of Fraxinus excelsior by the ash-dieback fungus Hymenoscyphus fraxineus. Sci Rep 2016; 6:34638. [PMID: 27694963 PMCID: PMC5046151 DOI: 10.1038/srep34638] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 09/16/2016] [Indexed: 11/09/2022] Open
Abstract
The invasive pathogen, ash dieback fungus Hymenoscyphus fraxineus, is spreading rapidly across Europe. It shows high levels of outcrossing and limited population structure, even at the epidemic front. The anamorphic (asexual) form produces prolific conidia, thought to function solely as spermatia (male gametes), facilitating gene flow between sympatric strains. Here, we show that conidia are capable of germination on ash leaves and in vitro, and can infect seedlings via leaves or soil. In leaves, germlings form structures resembling fruiting bodies. Additionally, H. fraxineus colonises ash debris and grows in soil in the absence of ash tissues. We propose an amended life-cycle in which wind-dispersed, insect-vectored or water-spread conidia infect ash and may sporulate in planta, as well as in forest debris. This amplifies inoculum levels of different strains in ash stands. In combination with their function as spermatia, conidia thus act to maximise gene flow between sympatric strains, including those originally present at low inoculum. Such mixing increases evolutionary potential, as well as enhancing the likelihood of gene introgression from closely-related strains or assimilation of further genetic diversity from parental Asian populations. This scenario increases the adaptability of H. fraxineus to new climates and, indeed, onto new host species.
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Affiliation(s)
- Helen Nicola Fones
- Department of Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Charlotte Mardon
- Department of Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Sarah Jane Gurr
- Department of Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.,Rothamsted Research, North Wyke Farm Platform, Okehampton, Devon, EX20 2SB, UK
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Mating type genes in the genus Neofusicoccum: Mating strategies and usefulness in species delimitation. Fungal Biol 2016; 121:394-404. [PMID: 28317541 DOI: 10.1016/j.funbio.2016.08.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 08/25/2016] [Indexed: 12/16/2022]
Abstract
The genus Neofusicoccum includes species with wide geographical and plant host distribution, some of them of economic importance. The genus currently comprises 27 species that are difficult to identify based on morphological features alone. Thus, species differentiation is based on phylogenetic species recognition using multigene genealogies. In this study, we characterised the mating type genes of Neofusicoccum species. Specific primers were designed to amplify and sequence MAT genes in several species and a PCR-based mating type diagnostic assay was developed. Homothallism was the predominant mating strategy among the species tested. Furthermore, the potential of mating type gene sequences for species delimitation was evaluated. Phylogenetic analyses were performed on both MAT genes and compared with multigene genealogies using sequences of the ribosomal internal transcribed spacer region, translation elongation factor 1-alpha and beta-tubulin. Phylogenies based on mating type genes could discriminate between the species analysed and are in concordance with the results obtained with the more conventional multilocus phylogenetic analysis approach. Thus, MAT genes represent a powerful tool to delimit cryptic species in the genus Neofusicoccum.
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16
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Drenkhan R, Riit T, Adamson K, Hanso M. The earliest samples of Hymenoscyphus albidus vs. H. fraxineus in Estonian mycological herbaria. Mycol Prog 2016. [DOI: 10.1007/s11557-016-1209-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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