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Cissé OH, Ma L, Kovacs JA. Retracing the evolution of Pneumocystis species, with a focus on the human pathogen Pneumocystis jirovecii. Microbiol Mol Biol Rev 2024; 88:e0020222. [PMID: 38587383 DOI: 10.1128/mmbr.00202-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024] Open
Abstract
SUMMARYEvery human being is presumed to be infected by the fungus Pneumocystis jirovecii at least once in his or her lifetime. This fungus belongs to a large group of species that appear to exclusively infect mammals, with P. jirovecii being the only one known to cause disease in humans. The mystery of P. jirovecii origin and speciation is just beginning to unravel. Here, we provide a review of the major steps of P. jirovecii evolution. The Pneumocystis genus likely originated from soil or plant-associated organisms during the period of Cretaceous ~165 million years ago and successfully shifted to mammals. The transition coincided with a substantial loss of genes, many of which are related to the synthesis of nutrients that can be scavenged from hosts or cell wall components that could be targeted by the mammalian immune system. Following the transition, the Pneumocystis genus cospeciated with mammals. Each species specialized at infecting its own host. Host specialization is presumably built at least partially upon surface glycoproteins, whose protogene was acquired prior to the genus formation. P. jirovecii appeared at ~65 million years ago, overlapping with the emergence of the first primates. P. jirovecii and its sister species P. macacae, which infects macaques nowadays, may have had overlapping host ranges in the distant past. Clues from molecular clocks suggest that P. jirovecii did not cospeciate with humans. Molecular evidence suggests that Pneumocystis speciation involved chromosomal rearrangements and the mounting of genetic barriers that inhibit gene flow among species.
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Affiliation(s)
- Ousmane H Cissé
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Liang Ma
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
| | - Joseph A Kovacs
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA
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Das S, T C, Selvasembian R, Prabhu AA. Mixed food waste valorization using a thermostable glucoamylase enzyme produced by a newly isolated filamentous fungus: A sustainable biorefinery approach. CHEMOSPHERE 2024; 352:141480. [PMID: 38401866 DOI: 10.1016/j.chemosphere.2024.141480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/26/2024] [Accepted: 02/15/2024] [Indexed: 02/26/2024]
Abstract
Food waste is a lucrative source of complex nutrients, which can be transformed into a multitude of bioproducts by the aid of microbial cell factories. The current study emphasizes isolating Glucoamylase enzyme (GA) producing strains that can effectively break down mixed food waste (MW), which serves as a substrate for biomanufacturing. The screening procedure relied heavily on the growth of isolated fungi on starch agar media, to specifically identify the microbes with the highest starch hydrolysis potential. A strain displayed the highest GA activity of 2.9 ± 0.14 U/ml which was selected and identified as Aspergillus fumigatus via molecular methods of identification. Exposure of the A. fumigatus with 200 mM Ethyl methanesulphonate (EMS) led to a 23.79% increase compared to the wild-type GA. The growth conditions like cultivation temperature or the number of spores in the inoculum were investigated. Further, maximum GA activity was exhibited at pH 5, 55 °C, and at 5 mM Ca2+ concentration. The GA showed thermostability, retaining activity even after long periods of exposure to temperatures as high as 95 °C. The improvement of hydrolysis of MW was achieved by Taguchi design where a maximum yield of 0.57 g g-1 glucose was obtained in the hydrolysate. This study puts forth the possibility that mixed food waste, despite containing spices and other microbial growth-inhibitory substances, can be efficiently hydrolyzed to release glucose units, by robust fungal cell factories. The glucose released can then be utilized as a carbon source for the production of value-added products.
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Affiliation(s)
- Satwika Das
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology, Warangal, Telangana, 506004, India
| | - Chandukishore T
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology, Warangal, Telangana, 506004, India
| | - Rangabhashiyam Selvasembian
- Department of Environmental Science and Engineering, School of Engineering and Sciences, SRM University-AP, Amaravati, Andhra Pradesh, 522240, India
| | - Ashish A Prabhu
- Bioprocess Development Laboratory, Department of Biotechnology, National Institute of Technology, Warangal, Telangana, 506004, India.
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Gautier A, Laval V, Faure S, Rouxel T, Balesdent MH. Polymorphism of Avirulence Genes and Adaptation to Brassica Resistance Genes Is Gene-Dependent in the Phytopathogenic Fungus Leptosphaeria maculans. PHYTOPATHOLOGY 2023; 113:1222-1232. [PMID: 36802873 DOI: 10.1094/phyto-12-22-0466-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The fungal phytopathogen Leptosphaeria maculans, which causes stem canker (blackleg) of rapeseed (Brassica napus), is mainly controlled worldwide by genetic resistance, which includes major resistance genes (Rlm). This model is one of those for which the highest number of avirulence genes (AvrLm) has been cloned. In many systems, including the L. maculans-B. napus interaction, intense use of resistance genes exerts strong selection pressure on the corresponding avirulent isolates, and the fungi may rapidly escape resistance through various molecular events which modify the avirulence genes. In the literature, the study of polymorphism at avirulence loci is often focused on single genes under selection pressure. In this study, we investigate allelic polymorphism at 11 avirulence loci in a French population of 89 L. maculans isolates collected on a trap cultivar in four geographic locations in the 2017-2018 cropping season. The corresponding Rlm genes have been (i) used for a long time, (ii) recently used, or (iii) unused in agricultural practice. The sequence data generated indicate an extreme diversity of situations. For example, genes submitted to an ancient selection may have either been deleted in populations (AvrLm1) or replaced by a single-nucleotide mutated virulent version (AvrLm2, AvrLm5-9). Genes that have never been under selection may either be nearly invariant (AvrLm6, AvrLm10A, AvrLm10B), exhibit rare deletions (AvrLm11, AvrLm14), or display a high diversity of alleles and isoforms (AvrLmS-Lep2). These data suggest that the evolutionary trajectory of avirulence/virulence alleles is gene-dependent and independent of selection pressure in L. maculans. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Angélique Gautier
- Université Paris-Saclay, INRAE, UR BIOGER, Bâtiment F, 22 Place de l'Agronomie, CS 80022, 91120 Palaiseau Cedex, France
| | - Valérie Laval
- Université Paris-Saclay, INRAE, UR BIOGER, Bâtiment F, 22 Place de l'Agronomie, CS 80022, 91120 Palaiseau Cedex, France
| | | | - Thierry Rouxel
- Université Paris-Saclay, INRAE, UR BIOGER, Bâtiment F, 22 Place de l'Agronomie, CS 80022, 91120 Palaiseau Cedex, France
| | - Marie-Hélène Balesdent
- Université Paris-Saclay, INRAE, UR BIOGER, Bâtiment F, 22 Place de l'Agronomie, CS 80022, 91120 Palaiseau Cedex, France
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Becerra S, Baroncelli R, Boufleur TR, Sukno SA, Thon MR. Chromosome-level analysis of the Colletotrichum graminicola genome reveals the unique characteristics of core and minichromosomes. Front Microbiol 2023; 14:1129319. [PMID: 37032845 PMCID: PMC10076810 DOI: 10.3389/fmicb.2023.1129319] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/28/2023] [Indexed: 04/11/2023] Open
Abstract
The fungal pathogen Colletotrichum graminicola causes the anthracnose of maize (Zea mays) and is responsible for significant yield losses worldwide. The genome of C. graminicola was sequenced in 2012 using Sanger sequencing, 454 pyrosequencing, and an optical map to obtain an assembly of 13 pseudochromosomes. We re-sequenced the genome using a combination of short-read (Illumina) and long-read (PacBio) technologies to obtain a chromosome-level assembly. The new version of the genome sequence has 13 chromosomes with a total length of 57.43 Mb. We detected 66 (23.62 Mb) structural rearrangements in the new assembly with respect to the previous version, consisting of 61 (21.98 Mb) translocations, 1 (1.41 Mb) inversion, and 4 (221 Kb) duplications. We annotated the genome and obtained 15,118 predicted genes and 3,614 new gene models compared to the previous version of the assembly. We show that 25.88% of the new assembly is composed of repetitive DNA elements (13.68% more than the previous assembly version), which are mostly found in gene-sparse regions. We describe genomic compartmentalization consisting of repeat-rich and gene-poor regions vs. repeat-poor and gene-rich regions. A total of 1,140 secreted proteins were found mainly in repeat-rich regions. We also found that ~75% of the three smallest chromosomes (minichromosomes, between 730 and 551 Kb) are strongly affected by repeat-induced point mutation (RIP) compared with 28% of the larger chromosomes. The gene content of the minichromosomes (MCs) comprises 121 genes, of which 83.6% are hypothetical proteins with no predicted function, while the mean percentage of Chr1-Chr10 is 36.5%. No predicted secreted proteins are present in the MCs. Interestingly, only 2% of the genes in Chr11 have homologs in other strains of C. graminicola, while Chr12 and 13 have 58 and 57%, respectively, raising the question as to whether Chrs12 and 13 are dispensable. The core chromosomes (Chr1-Chr10) are very different with respect to the MCs (Chr11-Chr13) in terms of the content and sequence features. We hypothesize that the higher density of repetitive elements and RIPs in the MCs may be linked to the adaptation and/or host co-evolution of this pathogenic fungus.
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Affiliation(s)
- Sioly Becerra
- Department of Microbiology and Genetics, Institute for Agrobiotechnology Research (CIALE), University of Salamanca, Villamayor, Spain
| | - Riccardo Baroncelli
- Department of Microbiology and Genetics, Institute for Agrobiotechnology Research (CIALE), University of Salamanca, Villamayor, Spain
- Department of Agricultural and Food Sciences (DISTAL), University of Bologna, Bologna, Italy
| | - Thaís R. Boufleur
- Department of Plant Pathology and Nematology, Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, Brazil
| | - Serenella A. Sukno
- Department of Microbiology and Genetics, Institute for Agrobiotechnology Research (CIALE), University of Salamanca, Villamayor, Spain
- *Correspondence: Serenella A. Sukno
| | - Michael R. Thon
- Department of Microbiology and Genetics, Institute for Agrobiotechnology Research (CIALE), University of Salamanca, Villamayor, Spain
- Michael R. Thon
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Ogaji YO, Lee RC, Sawbridge TI, Cocks BG, Daetwyler HD, Kaur S. De Novo Long-Read Whole-Genome Assemblies and the Comparative Pan-Genome Analysis of Ascochyta Blight Pathogens Affecting Field Pea. J Fungi (Basel) 2022; 8:jof8080884. [PMID: 36012871 PMCID: PMC9410150 DOI: 10.3390/jof8080884] [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: 06/22/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 11/16/2022] Open
Abstract
Ascochyta Blight (AB) is a major disease of many cool-season legumes globally. In field pea, three fungal pathogens have been identified to be responsible for this disease in Australia, namely Peyronellaea pinodes, Peyronellaea pinodella and Phoma koolunga. Limited genomic resources for these pathogens have been generated, which has hampered the implementation of effective management strategies and breeding for resistant cultivars. Using Oxford Nanopore long-read sequencing, we report the first high-quality, fully annotated, near-chromosome-level nuclear and mitochondrial genome assemblies for 18 isolates from the Australian AB complex. Comparative genome analysis was performed to elucidate the differences and similarities between species and isolates using phylogenetic relationships and functional diversity. Our data indicated that P. pinodella and P. koolunga are heterothallic, while P. pinodes is homothallic. More homology and orthologous gene clusters are shared between P. pinodes and P. pinodella compared to P. koolunga. The analysis of the repetitive DNA content showed differences in the transposable repeat composition in the genomes and their expression in the transcriptomes. Significant repeat expansion in P. koolunga’s genome was seen, with strong repeat-induced point mutation (RIP) activity being evident. Phylogenetic analysis revealed that genetic diversity can be exploited for species marker development. This study provided the much-needed genetic resources and characterization of the AB species to further drive research in key areas such as disease epidemiology and host–pathogen interactions.
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Affiliation(s)
- Yvonne O. Ogaji
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, 5 Ring Road, Melbourne, VIC 3083, Australia
- School of Applied Systems Biology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Robert C. Lee
- Centre for Crop and Disease Management, School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia
| | - Tim I. Sawbridge
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, 5 Ring Road, Melbourne, VIC 3083, Australia
- School of Applied Systems Biology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Benjamin G. Cocks
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, 5 Ring Road, Melbourne, VIC 3083, Australia
- School of Applied Systems Biology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Hans D. Daetwyler
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, 5 Ring Road, Melbourne, VIC 3083, Australia
- School of Applied Systems Biology, La Trobe University, Melbourne, VIC 3086, Australia
| | - Sukhjiwan Kaur
- Agriculture Victoria, AgriBio, Centre for AgriBioscience, 5 Ring Road, Melbourne, VIC 3083, Australia
- Correspondence:
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Montezano Fernandes F, Vieira de Queiroz M, Lopes da Silva L, Maria Queiroz Azevedo D, Luis Badel J, Couto Alfenas A. Chromosomal polymorphism of the Ceratocystis fimbriata species complex in Brazil. Fungal Genet Biol 2022; 162:103728. [PMID: 35932991 DOI: 10.1016/j.fgb.2022.103728] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 07/15/2022] [Accepted: 07/23/2022] [Indexed: 11/04/2022]
Abstract
Ceratocystis fimbriata is an important pathogen that causes wilt in several plant species. Despite the importance of this pathogen, knowledge about its karyotypic polymorphism and genomic architecture is limited. The main objective of this study was to investigate the karyotype of isolates of the C. fimbriata species complex from different host plants and geographical origins in Brazil. First, the identity of the isolates was confirmed conducting multilocus sequence analysis (MLSA) phylogeny using β-tubulin (TUBB), translation elongation factor 1α (TEF-1α) and mating-type (MAT1 and MAT2) gene sequences. To investigate the chromosomal polymorphism, two conditions of pulsed-field gel electrophoresis (PFGE) were used and the karyotypes of the isolates obtained. The retrotransposon-microsatellite amplified polymorphism (REMAP) molecular marker was utilized to assess the genetic variability among isolates. In the MLSA utilizing the concatenated gene sequences, Ceratocystis cacaofunesta and C. fimbriata formed separate clades, but considerable variation among C. fimbriata isolates was observed. Polymorphism in chromosome number and size was found, indicating the existence of genomic differences among isolates and occurrence of chromosomal rearrangements in the species complex. The number of chromosomes varied from seven to nine and the estimated minimum chromosome sizes were estimated to be between 2.7 to 6.0 Mbp. Small polymorphic chromosomes ranging from 1.2 to 1.8 Mbp were observed in all isolates, raising the hypothesis that they could be supernumerary chromosomes. REMAP analysis revealed a high genetic variability and that isolates from the same host tend to group together in a same cluster. Our results bring new insights into the chromosomal diversity and genome organization of the C. fimbriata complex.
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Affiliation(s)
- Fernando Montezano Fernandes
- Laboratory of Forest Pathology, Department of Plant Pathology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil
| | - Marisa Vieira de Queiroz
- Laboratory of Molecular Genetics of Microorganisms, Department of Microbiology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil
| | - Leandro Lopes da Silva
- Laboratory of Molecular Genetics of Microorganisms, Department of Microbiology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil
| | - Daiana Maria Queiroz Azevedo
- Laboratory of Forest Pathology, Department of Plant Pathology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil
| | - Jorge Luis Badel
- Laboratory of Molecular Phytobacteriology, Department of Plant Pathology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil
| | - Acelino Couto Alfenas
- Laboratory of Forest Pathology, Department of Plant Pathology, Universidade Federal de Viçosa, Minas Gerais State, 36570-900, Brazil.
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7
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Späth GF, Bussotti G. GIP: an open-source computational pipeline for mapping genomic instability from protists to cancer cells. Nucleic Acids Res 2021; 50:e36. [PMID: 34928370 PMCID: PMC8989552 DOI: 10.1093/nar/gkab1237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 11/01/2021] [Accepted: 12/03/2021] [Indexed: 11/25/2022] Open
Abstract
Genome instability has been recognized as a key driver for microbial and cancer adaptation and thus plays a central role in many diseases. Genome instability encompasses different types of genomic alterations, yet most available genome analysis software are limited to just one type of mutation. To overcome this limitation and better understand the role of genetic changes in enhancing pathogenicity we established GIP, a novel, powerful bioinformatic pipeline for comparative genome analysis. Here, we show its application to whole genome sequencing datasets of Leishmania, Plasmodium, Candida and cancer. Applying GIP on available data sets validated our pipeline and demonstrated the power of our tool to drive biological discovery. Applied to Plasmodium vivax genomes, our pipeline uncovered the convergent amplification of erythrocyte binding proteins and identified a nullisomic strain. Re-analyzing genomes of drug adapted Candida albicans strains revealed correlated copy number variations of functionally related genes, strongly supporting a mechanism of epistatic adaptation through interacting gene-dosage changes. Our results illustrate how GIP can be used for the identification of aneuploidy, gene copy number variations, changes in nucleic acid sequences, and chromosomal rearrangements. Altogether, GIP can shed light on the genetic bases of cell adaptation and drive disease biomarker discovery.
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Affiliation(s)
- Gerald F Späth
- Institut Pasteur, Université de Paris, INSERM U1201, Unité de Parasitologie moléculaire et Signalisation, Paris, France
| | - Giovanni Bussotti
- Institut Pasteur, Université de Paris, INSERM U1201, Unité de Parasitologie moléculaire et Signalisation, Paris, France.,Institut Pasteur, Université de Paris, Bioinformatics and Biostatistics Hub, F-75015 Paris, France
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8
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Chen JY, Klosterman SJ, Hu XP, Dai XF, Subbarao KV. Key Insights and Research Prospects at the Dawn of the Population Genomics Era for Verticillium dahliae. ANNUAL REVIEW OF PHYTOPATHOLOGY 2021; 59:31-51. [PMID: 33891830 DOI: 10.1146/annurev-phyto-020620-121925] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The genomics era has ushered in exciting possibilities to examine the genetic bases that undergird the characteristic features of Verticillium dahliae and other plant pathogens. In this review, we provide historical perspectives on some of the salient biological characteristics of V. dahliae, including its morphology, microsclerotia formation, host range, disease symptoms, vascular niche, reproduction, and population structure. The kaleidoscopic population structure of this pathogen is summarized, including different races of the pathogen, defoliating and nondefoliating phenotypes, vegetative compatibility groupings, and clonal populations. Where possible, we place the characteristic differences in the context of comparative and functional genomics analyses that have offered insights into population divergence within V. dahliae and the related species.Current challenges are highlighted along with some suggested future population genomics studies that will contribute to advancing our understanding of the population divergence in V. dahliae.
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Affiliation(s)
- Jie-Yin Chen
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; ,
| | - Steven J Klosterman
- Agricultural Research Service, United States Department of Agriculture, Salinas, California 93905, USA;
| | - Xiao-Ping Hu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Yangling 712100, China;
| | - Xiao-Feng Dai
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China; ,
| | - Krishna V Subbarao
- Department of Plant Pathology, University of California, Davis, California 93905, USA;
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Bertazzoni S, Jones DAB, Phan HT, Tan KC, Hane JK. Chromosome-level genome assembly and manually-curated proteome of model necrotroph Parastagonospora nodorum Sn15 reveals a genome-wide trove of candidate effector homologs, and redundancy of virulence-related functions within an accessory chromosome. BMC Genomics 2021; 22:382. [PMID: 34034667 PMCID: PMC8146201 DOI: 10.1186/s12864-021-07699-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 05/11/2021] [Indexed: 11/19/2022] Open
Abstract
Background The fungus Parastagonospora nodorum causes septoria nodorum blotch (SNB) of wheat (Triticum aestivum) and is a model species for necrotrophic plant pathogens. The genome assembly of reference isolate Sn15 was first reported in 2007. P. nodorum infection is promoted by its production of proteinaceous necrotrophic effectors, three of which are characterised – ToxA, Tox1 and Tox3. Results A chromosome-scale genome assembly of P. nodorum Australian reference isolate Sn15, which combined long read sequencing, optical mapping and manual curation, produced 23 chromosomes with 21 chromosomes possessing both telomeres. New transcriptome data were combined with fungal-specific gene prediction techniques and manual curation to produce a high-quality predicted gene annotation dataset, which comprises 13,869 high confidence genes, and an additional 2534 lower confidence genes retained to assist pathogenicity effector discovery. Comparison to a panel of 31 internationally-sourced isolates identified multiple hotspots within the Sn15 genome for mutation or presence-absence variation, which was used to enhance subsequent effector prediction. Effector prediction resulted in 257 candidates, of which 98 higher-ranked candidates were selected for in-depth analysis and revealed a wealth of functions related to pathogenicity. Additionally, 11 out of the 98 candidates also exhibited orthology conservation patterns that suggested lateral gene transfer with other cereal-pathogenic fungal species. Analysis of the pan-genome indicated the smallest chromosome of 0.4 Mbp length to be an accessory chromosome (AC23). AC23 was notably absent from an avirulent isolate and is predominated by mutation hotspots with an increase in non-synonymous mutations relative to other chromosomes. Surprisingly, AC23 was deficient in effector candidates, but contained several predicted genes with redundant pathogenicity-related functions. Conclusions We present an updated series of genomic resources for P. nodorum Sn15 – an important reference isolate and model necrotroph – with a comprehensive survey of its predicted pathogenicity content. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07699-8.
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Affiliation(s)
| | - Darcy A B Jones
- Centre for Crop & Disease Management, Curtin University, Perth, Australia
| | - Huyen T Phan
- Centre for Crop & Disease Management, Curtin University, Perth, Australia.
| | - Kar-Chun Tan
- Centre for Crop & Disease Management, Curtin University, Perth, Australia.
| | - James K Hane
- Centre for Crop & Disease Management, Curtin University, Perth, Australia. .,Curtin Institute for Computation, Curtin University, Perth, Australia.
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10
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Smith CA. Macrosynteny analysis between Lentinula edodes and Lentinula novae-zelandiae reveals signals of domestication in Lentinula edodes. Sci Rep 2021; 11:9845. [PMID: 33972587 PMCID: PMC8110776 DOI: 10.1038/s41598-021-89146-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/08/2021] [Indexed: 12/03/2022] Open
Abstract
The basidiomycete fungus Lentinula novae-zelandiae is endemic to New Zealand and is a sister taxon to Lentinula edodes, the second most cultivated mushroom in the world. To explore the biology of this organism, a high-quality chromosome level reference genome of L. novae-zelandiae was produced. Macrosyntenic comparisons between the genome assembly of L. novae-zelandiae, L. edodes and a set of three genome assemblies of diverse species from the Agaricomycota reveal a high degree of macrosyntenic restructuring within L. edodes consistent with signal of domestication. These results show L. edodes has undergone significant genomic change during the course of its evolutionary history, likely a result of its cultivation and domestication over the last 1000 years.
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11
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Genomic rearrangements generate hypervariable mini-chromosomes in host-specific isolates of the blast fungus. PLoS Genet 2021; 17:e1009386. [PMID: 33591993 PMCID: PMC7909708 DOI: 10.1371/journal.pgen.1009386] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 02/26/2021] [Accepted: 01/26/2021] [Indexed: 12/11/2022] Open
Abstract
Supernumerary mini-chromosomes–a unique type of genomic structural variation–have been implicated in the emergence of virulence traits in plant pathogenic fungi. However, the mechanisms that facilitate the emergence and maintenance of mini-chromosomes across fungi remain poorly understood. In the blast fungus Magnaporthe oryzae (Syn. Pyricularia oryzae), mini-chromosomes have been first described in the early 1990s but, until very recently, have been overlooked in genomic studies. Here we investigated structural variation in four isolates of the blast fungus M. oryzae from different grass hosts and analyzed the sequences of mini-chromosomes in the rice, foxtail millet and goosegrass isolates. The mini-chromosomes of these isolates turned out to be highly diverse with distinct sequence composition. They are enriched in repetitive elements and have lower gene density than core-chromosomes. We identified several virulence-related genes in the mini-chromosome of the rice isolate, including the virulence-related polyketide synthase Ace1 and two variants of the effector gene AVR-Pik. Macrosynteny analyses around these loci revealed structural rearrangements, including inter-chromosomal translocations between core- and mini-chromosomes. Our findings provide evidence that mini-chromosomes emerge from structural rearrangements and segmental duplication of core-chromosomes and might contribute to adaptive evolution of the blast fungus. The genomes of plant pathogens often exhibit an architecture that facilitates high rates of dynamic rearrangements and genetic diversification in virulence associated regions. These regions, which tend to be gene sparse and repeat rich, are thought to serve as a cradle for adaptive evolution. Supernumerary chromosomes, i.e. chromosomes that are only present in some but not all individuals of a species, are a special type of structural variation that have been observed in plants, animals, and fungi. Here we identified and studied supernumerary mini-chromosomes in the blast fungus Magnaporthe oryzae, a pathogen that causes some of the most destructive plant diseases. We found that rice, foxtail millet and goosegrass isolates of this pathogen contain mini-chromosomes with distinct sequence composition. All mini-chromosomes are rich in repetitive genetic elements and have lower gene densities than core-chromosomes. Further, we identified virulence-related genes on the mini-chromosome of the rice isolate. We observed large-scale genomic rearrangements around these loci, indicative of a role of mini-chromosomes in facilitating genome dynamics. Taken together, our results indicate that mini-chromosomes contribute to genome rearrangements and possibly adaptive evolution of the blast fungus.
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Jiang L, Stärkel P, Fan JG, Fouts DE, Bacher P, Schnabl B. The gut mycobiome: a novel player in chronic liver diseases. J Gastroenterol 2021; 56:1-11. [PMID: 33151407 PMCID: PMC7819863 DOI: 10.1007/s00535-020-01740-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 10/15/2020] [Indexed: 02/07/2023]
Abstract
The human gut microbiome (bacteria, fungi, viruses, and archaea) is a complex and diverse ecosystem. It plays an important role in human health, but is involved in several intestinal and extraintestinal diseases. Most research to date has focused on the role of bacteria, while studies focusing on fungi (also referred to as "mycobiome" or "fungome") are still in its infancy. In this review, we focus on the existing literature available about the gut mycobiome with an emphasis on compositional mycobiome changes associated with liver diseases, the impact on pathogenesis of disease, and its potential use as therapeutic targets. We also provide insights into current methodologies of studying mycobiome, and we highlight the interkingdom interactions in the context of disease and how they affect health of the host. Herein, by focusing on the gut mycobiome, this review provides novel insights and directions for liver research.
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Affiliation(s)
- Lu Jiang
- Department of Medicine, University of California San Diego, MC0063, 9500 Gilman Drive, La Jolla, CA 92093 USA ,Department of Medicine, VA San Diego Healthcare System, San Diego, CA USA
| | - Peter Stärkel
- Cliniques Universitaires Saint Luc, Université Catholique de Louvain, Brussels, Belgium
| | - Jian-Gao Fan
- Department of Gastroenterology, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | | | - Petra Bacher
- Institute of Immunology, Christian-Albrechts-University of Kiel and UKSH Schleswig-Holstein, Kiel, Germany ,Institute of Clinical Molecular Biology, Christian-Albrechts-University of Kiel, Kiel, Germany
| | - Bernd Schnabl
- Department of Medicine, University of California San Diego, MC0063, 9500 Gilman Drive, La Jolla, CA 92093 USA ,Department of Medicine, VA San Diego Healthcare System, San Diego, CA USA
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Korfanty G, Stanley K, Lammers K, Fan Y, Xu J. Variations in sexual fitness among natural strains of the opportunistic human fungal pathogen Aspergillus fumigatus. INFECTION GENETICS AND EVOLUTION 2020; 87:104640. [PMID: 33246083 DOI: 10.1016/j.meegid.2020.104640] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Revised: 10/05/2020] [Accepted: 11/21/2020] [Indexed: 10/22/2022]
Abstract
Aspergillus fumigatus is a ubiquitous ascomycete fungus, naturally inhabiting the soil and compost piles. Its conidia readily disperse into the atmosphere and cause opportunistic infections known as aspergillosis. With the emerging resistance to many antifungal drugs, our understanding of A. fumigatus epidemiology has become increasingly important for developing effective control and treatment strategies. As a pathogen capable of both sexual and asexual reproduction, mutations causing drug resistance and increased virulence could be spread rapidly in A. fumigatus populations. However, relatively little is known about the distributions of sexual reproductive fitness among natural strains of A. fumigatus. Here we investigated the formation of sexual reproductive structure (i.e. cleistothecia) and sexual spore viability among 60 natural strains of A. fumigatus. These strains were from six geographically distant countries (India, China, Canada, Cameroon, Saudi Arabia, and New Zealand), with 10 strains (including five MAT1-1 strains and five MAT1-2 strains) from each country. These strains were crossed in all combinations with strains of the opposite mating type. In addition, all 60 strains were crossed with either AFB62-1 (MAT1-1) or AFIR928 (MAT1-2), two reference supermater strains. Of the 900 crosses among the 60 natural strains, 136 crosses (15.1%) produced cleistothecia. Our analyses revealed that strains from China had the highest average ability to form cleistothecia, followed by those from New Zealand, Saudi Arabia, India, Canada, and Cameroon. Among the crosses that produced cleistothecia, about 40% produced viable ascospores, with the rate of ascospore germination varied significantly among crosses. Interestingly, neither the ability to form cleistothecia nor ascospore germination rate showed any distinct relationships with either geographic or genetic distance between parental strains. Our results suggest that genetic exchange among geographically and genetically divergent strains of A. fumigatus are possible. However, the rates of genetic exchange likely vary among strains and populations in nature.
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Affiliation(s)
- Greg Korfanty
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Kaitlin Stanley
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Kaitlyn Lammers
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - YuYing Fan
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
| | - Jianping Xu
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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Genomic Organization and Generation of Genetic Variability in the RHS (Retrotransposon Hot Spot) Protein Multigene Family in Trypanosoma cruzi. Genes (Basel) 2020; 11:genes11091085. [PMID: 32957642 PMCID: PMC7563717 DOI: 10.3390/genes11091085] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/15/2022] Open
Abstract
Retrotransposon Hot Spot (RHS) is the most abundant gene family in Trypanosoma cruzi, with unknown function in this parasite. The aim of this work was to shed light on the organization and expression of RHS in T. cruzi. The diversity of the RHS protein family in T. cruzi was demonstrated by phylogenetic and recombination analyses. Transcribed sequences carrying the RHS domain were classified into ten distinct groups of monophyletic origin. We identified numerous recombination events among the RHS and traced the origins of the donors and target sequences. The transcribed RHS genes have a mosaic structure that may contain fragments of different RHS inserted in the target sequence. About 30% of RHS sequences are located in the subtelomere, a region very susceptible to recombination. The evolution of the RHS family has been marked by many events, including gene duplication by unequal mitotic crossing-over, homologous, as well as ectopic recombination, and gene conversion. The expression of RHS was analyzed by immunofluorescence and immunoblotting using anti-RHS antibodies. RHS proteins are evenly distributed in the nuclear region of T. cruzi replicative forms (amastigote and epimastigote), suggesting that they could be involved in the control of the chromatin structure and gene expression, as has been proposed for T. brucei.
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Mahmoudjanlou Y, Dahlmann TA, Kück U. Molecular analysis of mating type loci from the mycophenolic acid producer Penicillium brevicompactum: Phylogeny and MAT protein characterization suggest a cryptic sexual life cycle. Fungal Biol 2020; 124:821-833. [PMID: 32883432 DOI: 10.1016/j.funbio.2020.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 06/25/2020] [Accepted: 07/07/2020] [Indexed: 12/31/2022]
Abstract
The mycophenolic acid producing ascomycete Penicillium brevicompactum is considered to be an anamorphic (asexual) species, for which a sexual cycle was never observed. However, since recent reports of otherwise asexually propagating filamentous fungi have demonstrated a sexual cycle controlled by mating type loci, we carried out a molecular analysis of mating type loci from P. brevicompactum. Using data from extensive DNA sequencing analysis, we determined the mating type loci from 22 strains derived from various type culture collections. We found 8 strains carrying a MAT1-1 locus encoding a 362 amino acid alpha domain transcription factor. The other 14 possessed a MAT1-2 locus encoding a 298 amino acid HMG domain transcription factor. cDNA analysis confirmed that both mating type loci are transcriptionally expressed. The karyotype of six selected strains, determined using contour-clamped homogeneous electric field (CHEF) electrophoresis, demonstrated distinct differences in size and numbers of chromosomes between the strains investigated. Interestingly, our phylogenetic survey of 72 strains from 11 different Penicillium species revealed that MAT genes serve as excellent molecular markers to determine phylogenetic relationships among species closely related to P. brevicompactum. Based on our sequencing results, we constructed transformation vectors for site-specific deletion of mating type loci from two selected strains of opposite mating type. Complementation strains were constructed containing both the mating type locus deletion cassette and a MAT-egfp fusion gene. These strains were used for comparative phenotypic analyses between strains containing or lacking the mating type gene. Whereas all MAT1-2 strains were indistinguishable, the MAT1-1 and MAT1-1-1 deletion strains differed distinctly. The MAT1-1-1 deletion strain produced more conidiospores on solid media, but smaller pellets in liquid media. This is probably the consequence of fewer conidial germ tubes than with the wild type mating type strain. Finally, we showed that the MAT-EGPF fusion protein is localized to the nuclei and detectable in protein samples by Western analysis. Together, our results suggest that the asexually propagating fungus P. brevicompactum might be a heterothallic species with a cryptic sexual life cycle.
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Affiliation(s)
| | - Tim A Dahlmann
- Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780 Bochum, Germany.
| | - Ulrich Kück
- Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780 Bochum, Germany.
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Abstract
Most genomes within the species complex of Fusarium oxysporum are organized into two compartments: the core chromosomes (CCs) and accessory chromosomes (ACs). As opposed to CCs, which are conserved and vertically transmitted to carry out essential housekeeping functions, lineage- or strain-specific ACs are believed to be initially horizontally acquired through unclear mechanisms. These two genomic compartments are different in terms of gene density, the distribution of transposable elements, and epigenetic markers. Although common in eukaryotes, the functional importance of ACs is uniquely emphasized among fungal species, specifically in relationship to fungal pathogenicity and their adaptation to diverse hosts. With a focus on the cross-kingdom fungal pathogen F. oxysporum, this review provides a summary of the differences between CCs and ACs based on current knowledge of gene functions, genome structures, and epigenetic signatures, and explores the transcriptional crosstalk between the core and accessory genomes.
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Todd RT, Selmecki A. Expandable and reversible copy number amplification drives rapid adaptation to antifungal drugs. eLife 2020; 9:e58349. [PMID: 32687060 PMCID: PMC7371428 DOI: 10.7554/elife.58349] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/09/2020] [Indexed: 12/13/2022] Open
Abstract
Previously, we identified long repeat sequences that are frequently associated with genome rearrangements, including copy number variation (CNV), in many diverse isolates of the human fungal pathogen Candida albicans (Todd et al., 2019). Here, we describe the rapid acquisition of novel, high copy number CNVs during adaptation to azole antifungal drugs. Single-cell karyotype analysis indicates that these CNVs appear to arise via a dicentric chromosome intermediate and breakage-fusion-bridge cycles that are repaired using multiple distinct long inverted repeat sequences. Subsequent removal of the antifungal drug can lead to a dramatic loss of the CNV and reversion to the progenitor genotype and drug susceptibility phenotype. These findings support a novel mechanism for the rapid acquisition of antifungal drug resistance and provide genomic evidence for the heterogeneity frequently observed in clinical settings.
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Affiliation(s)
- Robert T Todd
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
| | - Anna Selmecki
- Department of Microbiology and Immunology, University of Minnesota Medical SchoolMinneapolis, MinnesotaUnited States
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18
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Armitage AD, Cockerton HM, Sreenivasaprasad S, Woodhall J, Lane CR, Harrison RJ, Clarkson JP. Genomics Evolutionary History and Diagnostics of the Alternaria alternata Species Group Including Apple and Asian Pear Pathotypes. Front Microbiol 2020; 10:3124. [PMID: 32038562 PMCID: PMC6989435 DOI: 10.3389/fmicb.2019.03124] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 12/24/2019] [Indexed: 02/04/2023] Open
Abstract
The Alternaria section alternaria (Alternaria alternata species group) represents a diverse group of saprotroph, human allergens, and plant pathogens. Alternaria taxonomy has benefited from recent phylogenetic revision but the basis of differentiation between major phylogenetic clades within the group is not yet understood. Furthermore, genomic resources have been limited for the study of host-specific pathotypes. We report near complete genomes of the apple and Asian pear pathotypes as well as draft assemblies for a further 10 isolates representing Alternaria tenuissima and Alternaria arborescens lineages. These assemblies provide the first insights into differentiation of these taxa as well as allowing the description of effector and non-effector profiles of apple and pear conditionally dispensable chromosomes (CDCs). We define the phylogenetic relationship between the isolates sequenced in this study and a further 23 Alternaria spp. based on available genomes. We determine which of these genomes represent MAT1-1-1 or MAT1-2-1 idiomorphs and designate host-specific pathotypes. We show for the first time that the apple pathotype is polyphyletic, present in both the A. arborescens and A. tenuissima lineages. Furthermore, we profile a wider set of 89 isolates for both mating type idiomorphs and toxin gene markers. Mating-type distribution indicated that gene flow has occurred since the formation of A. tenuissima and A. arborescens lineages. We also developed primers designed to AMT14, a gene from the apple pathotype toxin gene cluster with homologs in all tested pathotypes. These primers allow identification and differentiation of apple, pear, and strawberry pathotypes, providing new tools for pathogen diagnostics.
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Affiliation(s)
- Andrew D. Armitage
- NIAB EMR, East Malling, United Kingdom
- Natural Resources Institute, University of Greenwich, Chatham Maritime, London, United Kingdom
| | | | | | - James Woodhall
- Parma Research and Extension Center, University of Idaho, Parma, ID, United States
| | | | | | - John P. Clarkson
- Warwick Crop Centre, University of Warwick, Warwick, United Kingdom
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19
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Bravo Ruiz G, Ross ZK, Holmes E, Schelenz S, Gow NAR, Lorenz A. Rapid and extensive karyotype diversification in haploid clinical Candida auris isolates. Curr Genet 2019; 65:1217-1228. [PMID: 31020384 PMCID: PMC6744574 DOI: 10.1007/s00294-019-00976-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/09/2019] [Accepted: 04/15/2019] [Indexed: 11/30/2022]
Abstract
Candida auris is a newly emerged pathogenic microbe, having been identified as a medically relevant fungus as recently as 2009. It is one of the most drug-resistant yeast species known to date and its emergence and population structure are unusual. Because of its recent emergence, we are largely ignorant about fundamental aspects of its general biology, life cycle, and population dynamics. Here, we report the karyotype variability of 26 C. auris strains representing the four main clades. We demonstrate that all strains are haploid and have a highly plastic karyotype containing five to seven chromosomes, which can undergo marked alterations within a short time frame when the fungus is put under genotoxic, heat, or osmotic stress. No simple correlation was found between karyotype pattern, drug resistance, and clade affiliation indicating that karyotype heterogeneity is rapidly evolving. As with other Candida species, these marked karyotype differences between isolates are likely to have an important impact on pathogenic traits of C. auris.
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Affiliation(s)
- Gustavo Bravo Ruiz
- Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Zoe K Ross
- Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
- MRC Centre for Medical Mycology, University of Aberdeen, Aberdeen, UK
| | - Eilidh Holmes
- Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Silke Schelenz
- Department of Microbiology, Royal Brompton Hospital, London, UK
| | - Neil A R Gow
- Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
- MRC Centre for Medical Mycology, University of Aberdeen, Aberdeen, UK
- School of Biosciences, University of Exeter, Exeter, UK
| | - Alexander Lorenz
- Institute of Medical Sciences (IMS), University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
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20
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The Aspergillus fumigatus Mismatch Repair MSH2 Homolog Is Important for Virulence and Azole Resistance. mSphere 2019; 4:4/4/e00416-19. [PMID: 31391280 PMCID: PMC6686229 DOI: 10.1128/msphere.00416-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Invasive aspergillosis (IA) has emerged as one of the most common life-threatening fungal diseases in immunocompromised patients, with mortality rates as high as 90%. Systemic fungal infections such as IA are usually treated with triazoles; however, epidemiological research has shown that the prevalence of azole-resistant Aspergillus fumigatus isolates has increased significantly over the last decade. There is very little information about the importance of genomic stability for A. fumigatus population structure, azole resistance, and virulence. Here, we decided to investigate whether the mismatch repair system could influence A. fumigatus azole resistance and virulence, focusing on one of the components of this system, MSH2. Although the mutation frequency of mshA (the A. fumigatusMSH2 homologue) is low in environmental and clinical isolates, our results indicate that loss of mshA function can provide increased azole resistance and virulence when selected for. These results demonstrate the importance of genetic instability in A. fumigatus as a possible mechanism of evolving azole resistance and establishing fitness in the host. The genetic stability of every living organism depends on accurate DNA replication and repair systems. Here, we investigated the Aspergillus fumigatusMSH2 mismatch repair (MMR) gene MshA and how it impacts virulence and the evolution of azole resistance. We examined mshA gene variation in 62 environmental and clinical A. fumigatus strains. We have observed 12 strains with variants (18.2%), and 8 strains among them showed missense variants. We demonstrated that A. fumigatusmshA null mutants are haploid and have conserved karyotypes with discrete gross chromosomal rearrangements. The ΔmshA strains are not sensitive to several DNA-damaging agents. The lack of mshA caused a significant reduction of virulence of A. fumigatus in a neutropenic murine model of invasive pulmonary aspergillosis and in the invertebrate alternative model Galleria mellonella. Wild-type and ΔmshA populations did not show any significant changes in drug resistance acquisition after they were transferred 10 times in minimal medium in the absence of any stress. However, these populations rapidly acquired virulence in the ΔmshA background and high levels of resistance to posaconazole in the presence of this drug (at least 200-fold-higher levels of resistance than those derived from the wild-type strain). Taken together, these results suggest that genetic instability caused by ΔmshA mutations can confer an adaptive advantage, mainly increasing posaconazole resistance and virulence acquisition. IMPORTANCE Invasive aspergillosis (IA) has emerged as one of the most common life-threatening fungal diseases in immunocompromised patients, with mortality rates as high as 90%. Systemic fungal infections such as IA are usually treated with triazoles; however, epidemiological research has shown that the prevalence of azole-resistant Aspergillus fumigatus isolates has increased significantly over the last decade. There is very little information about the importance of genomic stability for A. fumigatus population structure, azole resistance, and virulence. Here, we decided to investigate whether the mismatch repair system could influence A. fumigatus azole resistance and virulence, focusing on one of the components of this system, MSH2. Although the mutation frequency of mshA (the A. fumigatusMSH2 homologue) is low in environmental and clinical isolates, our results indicate that loss of mshA function can provide increased azole resistance and virulence when selected for. These results demonstrate the importance of genetic instability in A. fumigatus as a possible mechanism of evolving azole resistance and establishing fitness in the host.
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21
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Lofgren LA, Uehling JK, Branco S, Bruns TD, Martin F, Kennedy PG. Genome‐based estimates of fungal rDNA copy number variation across phylogenetic scales and ecological lifestyles. Mol Ecol 2019; 28:721-730. [DOI: 10.1111/mec.14995] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 11/22/2018] [Accepted: 11/27/2018] [Indexed: 12/28/2022]
Affiliation(s)
- Lotus A. Lofgren
- Department of Plant and Microbial Biology University of Minnesota St. Paul Minnesota
| | - Jessie K. Uehling
- Department of Plant and Microbial Biology University of California Berkeley Berkeley California
| | - Sara Branco
- Department of Microbiology and Immunology Montana State University Bozeman Montana
| | - Thomas D. Bruns
- Department of Plant and Microbial Biology University of California Berkeley Berkeley California
| | - Francis Martin
- Laboratoire d'Excellence ARBRE, Interactions Arbres/Micro‐organismes, INRA UMR1136 INRA‐Université de Lorraine Champenoux France
| | - Peter G. Kennedy
- Department of Plant and Microbial Biology University of Minnesota St. Paul Minnesota
- Department of Ecology, Evolution and Behavior University of Minnesota St. Paul Minnesota
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22
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Abstract
Fungi are prone to phenotypic instability, that is, the vegetative phase of these organisms, be they yeasts or molds, undergoes frequent switching between two or more behaviors, often with different morphologies, but also sometime having different physiologies without any obvious morphological outcome. In the context of industrial utilization of fungi, this can have a negative impact on the maintenance of strains and/or on their productivity. Instabilities have been shown to result from various mechanisms, either genetic or epigenetic. This chapter will review different types of instabilities and discuss some lesser-known ones, mostly in filamentous fungi, while it will direct readers to additional literature in the case of well-known phenomena such as the amyloid prions or fungal senescence. It will present in depth the "white/opaque" switch of Candida albicans and the "crippled growth" degeneration of the model fungus Podospora anserina. These are two of the most thoroughly studied epigenetic phenotypic switches. I will also discuss the "sectors" presented by many filamentous ascomycetes, for which a prion-based model exists but is not demonstrated. Finally, I will also describe intriguing examples of phenotypic instability for which an explanation has yet to be provided.
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Syme RA, Tan KC, Rybak K, Friesen TL, McDonald BA, Oliver RP, Hane JK. Pan-Parastagonospora Comparative Genome Analysis-Effector Prediction and Genome Evolution. Genome Biol Evol 2018; 10:2443-2457. [PMID: 30184068 PMCID: PMC6152946 DOI: 10.1093/gbe/evy192] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2018] [Indexed: 01/01/2023] Open
Abstract
We report a fungal pan-genome study involving Parastagonospora spp., including 21 isolates of the wheat (Triticum aestivum) pathogen Parastagonospora nodorum, 10 of the grass-infecting Parastagonospora avenae, and 2 of a closely related undefined sister species. We observed substantial variation in the distribution of polymorphisms across the pan-genome, including repeat-induced point mutations, diversifying selection and gene gains and losses. We also discovered chromosome-scale inter and intraspecific presence/absence variation of some sequences, suggesting the occurrence of one or more accessory chromosomes or regions that may play a role in host-pathogen interactions. The presence of known pathogenicity effector loci SnToxA, SnTox1, and SnTox3 varied substantially among isolates. Three P. nodorum isolates lacked functional versions for all three loci, whereas three P. avenae isolates carried one or both of the SnTox1 and SnTox3 genes, indicating previously unrecognized potential for discovering additional effectors in the P. nodorum-wheat pathosystem. We utilized the pan-genomic comparative analysis to improve the prediction of pathogenicity effector candidates, recovering the three confirmed effectors among our top-ranked candidates. We propose applying this pan-genomic approach to identify the effector repertoire involved in other host-microbe interactions involving necrotrophic pathogens in the Pezizomycotina.
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Affiliation(s)
- Robert A Syme
- Centre for Crop & Disease Management, School of Molecular & Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Kar-Chun Tan
- Centre for Crop & Disease Management, School of Molecular & Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Kasia Rybak
- Centre for Crop & Disease Management, School of Molecular & Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - Timothy L Friesen
- Cereal Crops Research Unit, USDA-ARS Red River Valley Agricultural Research Center, Fargo, North Dakota
| | - Bruce A McDonald
- Plant Pathology Group, Institute of Integrative Biology, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | - Richard P Oliver
- Centre for Crop & Disease Management, School of Molecular & Life Sciences, Curtin University, Bentley, Western Australia, Australia
| | - James K Hane
- Centre for Crop & Disease Management, School of Molecular & Life Sciences, Curtin University, Bentley, Western Australia, Australia
- Curtin Institute for Computation, Curtin University, Bentley, Western Australia, Australia
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Genomic Analysis of the Insect-Killing Fungus Beauveria bassiana JEF-007 as a Biopesticide. Sci Rep 2018; 8:12388. [PMID: 30120392 PMCID: PMC6098154 DOI: 10.1038/s41598-018-30856-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/07/2018] [Indexed: 02/07/2023] Open
Abstract
Insect-killing fungi have high potential in pest management. A deeper insight into the fungal genes at the whole genome level is necessary to understand the inter-species or intra-species genetic diversity of fungal genes, and to select excellent isolates. In this work, we conducted a whole genome sequencing of Beauveria bassiana (Bb) JEF-007 and characterized pathogenesis-related features and compared with other isolates including Bb ARSEF2860. A large number of Bb JEF-007 genes showed high identity with Bb ARSEF2860, but some genes showed moderate or low identity. The two Bb isolates showed a significant difference in vegetative growth, antibiotic-susceptibility, and virulence against Tenebrio molitor larvae. When highly identical genes between the two Bb isolates were subjected to real-time PCR, their transcription levels were different, particularly in heat shock protein 30 (hsp30) gene which is related to conidial thermotolerance. In several B. bassiana isolates, chitinases and trypsin-like protease genes involved in pathogenesis were highly conserved, but other genes showed noticeable sequence variation within the same species. Given the transcriptional and genetic diversity in B. bassiana, a selection of virulent isolates with industrial advantages is a pre-requisite, and this genetic approach could support the development of excellent biopesticides with intellectual property protection.
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25
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Plissonneau C, Hartmann FE, Croll D. Pangenome analyses of the wheat pathogen Zymoseptoria tritici reveal the structural basis of a highly plastic eukaryotic genome. BMC Biol 2018; 16:5. [PMID: 29325559 PMCID: PMC5765654 DOI: 10.1186/s12915-017-0457-4] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 11/16/2017] [Indexed: 01/01/2023] Open
Abstract
Background Structural variation contributes substantially to polymorphism within species. Chromosomal rearrangements that impact genes can lead to functional variation among individuals and influence the expression of phenotypic traits. Genomes of fungal pathogens show substantial chromosomal polymorphism that can drive virulence evolution on host plants. Assessing the adaptive significance of structural variation is challenging, because most studies rely on inferences based on a single reference genome sequence. Results We constructed and analyzed the pangenome of Zymoseptoria tritici, a major pathogen of wheat that evolved host specialization by chromosomal rearrangements and gene deletions. We used single-molecule real-time sequencing and high-density genetic maps to assemble multiple genomes. We annotated the gene space based on transcriptomics data that covered the infection life cycle of each strain. Based on a total of five telomere-to-telomere genomes, we constructed a pangenome for the species and identified a core set of 9149 genes. However, an additional 6600 genes were exclusive to a subset of the isolates. The substantial accessory genome encoded on average fewer expressed genes but a larger fraction of the candidate effector genes that may interact with the host during infection. We expanded our analyses of the pangenome to a worldwide collection of 123 isolates of the same species. We confirmed that accessory genes were indeed more likely to show deletion polymorphisms and loss-of-function mutations compared to core genes. Conclusions The pangenome construction of a highly polymorphic eukaryotic pathogen showed that a single reference genome significantly underestimates the gene space of a species. The substantial accessory genome provides a cradle for adaptive evolution. Electronic supplementary material The online version of this article (doi:10.1186/s12915-017-0457-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Clémence Plissonneau
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, 8092, Zurich, Switzerland.,UMR BIOGER, INRA, AgroParisTech, Université Paris-Saclay, Avenue Lucien Bretignières, BP 01, Thiverval-Grignon, F-78850, France
| | - Fanny E Hartmann
- Plant Pathology, Institute of Integrative Biology, ETH Zurich, 8092, Zurich, Switzerland.,Ecologie Systématique Evolution, Univ. Paris-Sud, AgroParisTech, CNRS, Université Paris-Saclay, 91400, Orsay, France
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, CH-2000, Neuchâtel, Switzerland.
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The Influence of Genetic Stability on Aspergillus fumigatus Virulence and Azole Resistance. G3-GENES GENOMES GENETICS 2018; 8:265-278. [PMID: 29150592 PMCID: PMC5765354 DOI: 10.1534/g3.117.300265] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Genetic stability is extremely important for the survival of every living organism, and a very complex set of genes has evolved to cope with DNA repair upon DNA damage. Here, we investigated the Aspergillus fumigatus AtmA (Ataxia-telangiectasia mutated, ATM) and AtrA kinases, and how they impact virulence and the evolution of azole resistance. We demonstrated that A. fumigatus atmA and atrA null mutants are haploid and have a discrete chromosomal polymorphism. The ΔatmA and ΔatrA strains are sensitive to several DNA-damaging agents, but surprisingly both strains were more resistant than the wild-type strain to paraquat, menadione, and hydrogen peroxide. The atmA and atrA genes showed synthetic lethality emphasizing the cooperation between both enzymes and their consequent redundancy. The lack of atmA and atrA does not cause any significant virulence reduction in A. fumigatus in a neutropenic murine model of invasive pulmonary aspergillosis and in the invertebrate alternative model Galleria mellonela. Wild-type, ΔatmA, and ΔatrA populations that were previously transferred 10 times in minimal medium (MM) in the absence of voriconazole have not shown any significant changes in drug resistance acquisition. In contrast, ΔatmA and ΔatrA populations that similarly evolved in the presence of a subinhibitory concentration of voriconazole showed an ∼5–10-fold increase when compared to the original minimal inhibitory concentration (MIC) values. There are discrete alterations in the voriconazole target Cyp51A/Erg11A or cyp51/erg11 and/or Cdr1B efflux transporter overexpression that do not seem to be the main mechanisms to explain voriconazole resistance in these evolved populations. Taken together, these results suggest that genetic instability caused by ΔatmA and ΔatrA mutations can confer an adaptive advantage, mainly in the intensity of voriconazole resistance acquisition.
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Mehrabi R, Mirzadi Gohari A, Kema GHJ. Karyotype Variability in Plant-Pathogenic Fungi. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017; 55:483-503. [PMID: 28777924 DOI: 10.1146/annurev-phyto-080615-095928] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Recent advances in genetic and molecular technologies gradually paved the way for the transition from traditional fungal karyotyping to more comprehensive chromosome biology studies. Extensive chromosomal polymorphisms largely resulting from chromosomal rearrangements (CRs) are widely documented in fungal genomes. These extraordinary CRs in fungi generate substantial genome plasticity compared to other eukaryotic organisms. Here, we review the most recent findings on fungal CRs and their underlying mechanisms and discuss the functional consequences of CRs for adaptation, fungal evolution, host range, and pathogenicity of fungal plant pathogens in the context of chromosome biology. In addition to a complement of permanent chromosomes called core chromosomes, the genomes of many fungal pathogens comprise distinct unstable chromosomes called dispensable chromosomes (DCs) that also contribute to chromosome polymorphisms. Compared to the core chromosomes, the structural features of DCs usually differ for gene density, GC content, housekeeping genes, and recombination frequency. Despite their dispensability for normal growth and development, DCs have important biological roles with respect to pathogenicity in some fungi but not in others. Therefore, their evolutionary origin is also reviewed in relation to overall fungal physiology and pathogenicity.
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Affiliation(s)
- Rahim Mehrabi
- Seed and Plant Improvement Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
- Department of Biotechnology, College of Agriculture, Isfahan University of Technology, Isfahan, Iran
| | - Amir Mirzadi Gohari
- Department of Plant Pathology, Faculty of Agricultural Sciences and Engineering, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
- Wageningen Plant Research, Wageningen University and Research, 6700AA Wageningen, The Netherlands;
| | - Gert H J Kema
- Wageningen Plant Research, Wageningen University and Research, 6700AA Wageningen, The Netherlands;
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Plissonneau C, Benevenuto J, Mohd-Assaad N, Fouché S, Hartmann FE, Croll D. Using Population and Comparative Genomics to Understand the Genetic Basis of Effector-Driven Fungal Pathogen Evolution. FRONTIERS IN PLANT SCIENCE 2017; 8:119. [PMID: 28217138 PMCID: PMC5289978 DOI: 10.3389/fpls.2017.00119] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 01/20/2017] [Indexed: 05/20/2023]
Abstract
Epidemics caused by fungal plant pathogens pose a major threat to agro-ecosystems and impact global food security. High-throughput sequencing enabled major advances in understanding how pathogens cause disease on crops. Hundreds of fungal genomes are now available and analyzing these genomes highlighted the key role of effector genes in disease. Effectors are small secreted proteins that enhance infection by manipulating host metabolism. Fungal genomes carry 100s of putative effector genes, but the lack of homology among effector genes, even for closely related species, challenges evolutionary and functional analyses. Furthermore, effector genes are often found in rapidly evolving chromosome compartments which are difficult to assemble. We review how population and comparative genomics toolsets can be combined to address these challenges. We highlight studies that associated genome-scale polymorphisms with pathogen lifestyles and adaptation to different environments. We show how genome-wide association studies can be used to identify effectors and other pathogenicity-related genes underlying rapid adaptation. We also discuss how the compartmentalization of fungal genomes into core and accessory regions shapes the evolution of effector genes. We argue that an understanding of genome evolution provides important insight into the trajectory of host-pathogen co-evolution.
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Affiliation(s)
- Clémence Plissonneau
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- UMR, BIOGER, INRA, AgroParisTech, Université Paris-SaclayThiverval-Grignon, France
| | - Juliana Benevenuto
- College of Agriculture “Luiz de Queiroz”, University of São PauloSão Paulo, Brazil
| | - Norfarhan Mohd-Assaad
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- School of Biosciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan MalaysiaSelangor, Malaysia
| | - Simone Fouché
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
| | - Fanny E. Hartmann
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
| | - Daniel Croll
- Plant Pathology, Institute of Integrative Biology, ETH ZurichZurich, Switzerland
- Laboratory of Evolutionary Genetics, Institute of Biology, University of NeuchatelNeuchatel, Switzerland
- *Correspondence: Daniel Croll,
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Lopes ML, Paulillo SCDL, Godoy A, Cherubin RA, Lorenzi MS, Giometti FHC, Bernardino CD, Amorim Neto HBD, Amorim HVD. Ethanol production in Brazil: a bridge between science and industry. Braz J Microbiol 2016; 47 Suppl 1:64-76. [PMID: 27818090 PMCID: PMC5156502 DOI: 10.1016/j.bjm.2016.10.003] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 10/05/2016] [Indexed: 12/13/2022] Open
Abstract
In the last 40 years, several scientific and technological advances in microbiology of the fermentation have greatly contributed to evolution of the ethanol industry in Brazil. These contributions have increased our view and comprehension about fermentations in the first and, more recently, second-generation ethanol. Nowadays, new technologies are available to produce ethanol from sugarcane, corn and other feedstocks, reducing the off-season period. Better control of fermentation conditions can reduce the stress conditions for yeast cells and contamination by bacteria and wild yeasts. There are great research opportunities in production processes of the first-generation ethanol regarding high-value added products, cost reduction and selection of new industrial yeast strains that are more robust and customized for each distillery. New technologies have also focused on the reduction of vinasse volumes by increasing the ethanol concentrations in wine during fermentation. Moreover, conversion of sugarcane biomass into fermentable sugars for second-generation ethanol production is a promising alternative to meet future demands of biofuel production in the country. However, building a bridge between science and industry requires investments in research, development and transfer of new technologies to the industry as well as specialized personnel to deal with new technological challenges.
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Abstract
Fungal plant pathogens rapidly evolve virulence on resistant hosts through mutations in genes encoding proteins that modulate the host immune responses. The mutational spectrum likely includes chromosomal rearrangements responsible for gains or losses of entire genes. However, the mechanisms creating adaptive structural variation in fungal pathogen populations are poorly understood. We used complete genome assemblies to quantify structural variants segregating in the highly polymorphic fungal wheat pathogen Zymoseptoria tritici The genetic basis of virulence in Z. tritici is complex, and populations harbor significant genetic variation for virulence; hence, we aimed to identify whether structural variation led to functional differences. We combined single-molecule real-time sequencing, genetic maps, and transcriptomics data to generate a fully assembled and annotated genome of the highly virulent field isolate 3D7. Comparative genomics analyses against the complete reference genome IPO323 identified large chromosomal inversions and the complete gain or loss of transposable-element clusters, explaining the extensive chromosomal-length polymorphisms found in this species. Both the 3D7 and IPO323 genomes harbored long tracts of sequences exclusive to one of the two genomes. These orphan regions contained 296 genes unique to the 3D7 genome and not previously known for this species. These orphan genes tended to be organized in clusters and showed evidence of mutational decay. Moreover, the orphan genes were enriched in genes encoding putative effectors and included a gene that is one of the most upregulated putative effector genes during wheat infection. Our study showed that this pathogen species harbored extensive chromosomal structure polymorphism that may drive the evolution of virulence. IMPORTANCE Pathogen outbreak populations often harbor previously unknown genes conferring virulence. Hence, a key puzzle of rapid pathogen evolution is the origin of such evolutionary novelty in genomes. Chromosomal rearrangements and structural variation in pathogen populations likely play a key role. However, identifying such polymorphism is challenging, as most genome-sequencing approaches only yield information about point mutations. We combined long-read technology and genetic maps to assemble the complete genome of a strain of a highly polymorphic fungal pathogen of wheat. Comparisons against the reference genome of the species showed substantial variation in the chromosome structure and revealed large regions unique to each assembled genome. These regions were enriched in genes encoding likely effector proteins, which are important components of pathogenicity. Our study showed that pathogen populations harbor extensive polymorphism at the chromosome level and that this polymorphism can be a source of adaptive genetic variation in pathogen evolution.
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Depotter JRL, Deketelaere S, Inderbitzin P, Tiedemann AV, Höfte M, Subbarao KV, Wood TA, Thomma BPHJ. Verticillium longisporum, the invisible threat to oilseed rape and other brassicaceous plant hosts. MOLECULAR PLANT PATHOLOGY 2016; 17:1004-16. [PMID: 26663851 PMCID: PMC6638321 DOI: 10.1111/mpp.12350] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/03/2015] [Accepted: 12/04/2015] [Indexed: 05/21/2023]
Abstract
INTRODUCTION The causal agents of Verticillium wilts are globally distributed pathogens that cause significant crop losses every year. Most Verticillium wilts are caused by V. dahliae, which is pathogenic on a broad range of plant hosts, whereas other pathogenic Verticillium species have more restricted host ranges. In contrast, V. longisporum appears to prefer brassicaceous plants and poses an increasing problem to oilseed rape production. TAXONOMY Kingdom Fungi; Phylum Ascomycota; Class Sordariomycetes; Subclass Hypocreomycetida; Family Plectosphaerellaceae; genus Verticillium. DISEASE SYMPTOMS Dark unilateral stripes appear on the stems of apparently healthy looking oilseed rape plants at the end of the growing season. Microsclerotia are subsequently formed in the stem cortex beneath the epidermis. GENOME Verticillium longisporum is the only non-haploid species in the Verticillium genus, as it is an amphidiploid hybrid that carries almost twice as much genetic material as the other Verticillium species as a result of interspecific hybridization. DISEASE MANAGEMENT There is no effective fungicide treatment to control Verticillium diseases, and resistance breeding is the preferred strategy for disease management. However, only a few Verticillium wilt resistance genes have been identified, and monogenic resistance against V. longisporum has not yet been found. Quantitative resistance exists mainly in the Brassica C-genome of parental cabbage lines and may be introgressed in oilseed rape breeding lines. COMMON NAME Oilseed rape colonized by V. longisporum does not develop wilting symptoms, and therefore the common name of Verticillium wilt is unsuitable for this crop. Therefore, we propose 'Verticillium stem striping' as the common name for Verticillium infections of oilseed rape.
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Affiliation(s)
- Jasper R L Depotter
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, the Netherlands
- Department of Crops and Agronomy, National Institute of Agricultural Botany, Huntingdon Road, Cambridge, CB3 0LE, UK
| | - Silke Deketelaere
- Laboratory of Phytopathology, Faculty of Bioscience Engineering, Coupure links 653, Ghent University, B-9000, Ghent, Belgium
| | - Patrik Inderbitzin
- Department of Plant Pathology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Andreas Von Tiedemann
- Department of Crop Sciences, Plant Pathology and Crop Protection Division, Georg-August University Göttingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Monica Höfte
- Laboratory of Phytopathology, Faculty of Bioscience Engineering, Coupure links 653, Ghent University, B-9000, Ghent, Belgium
| | - Krishna V Subbarao
- Department of Plant Pathology, University of California Davis, One Shields Avenue, Davis, CA, 95616, USA
| | - Thomas A Wood
- Department of Crops and Agronomy, National Institute of Agricultural Botany, Huntingdon Road, Cambridge, CB3 0LE, UK
| | - Bart P H J Thomma
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708, PB, Wageningen, the Netherlands
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Anderson C, Khan MA, Catanzariti AM, Jack CA, Nemri A, Lawrence GJ, Upadhyaya NM, Hardham AR, Ellis JG, Dodds PN, Jones DA. Genome analysis and avirulence gene cloning using a high-density RADseq linkage map of the flax rust fungus, Melampsora lini. BMC Genomics 2016; 17:667. [PMID: 27550217 PMCID: PMC4994203 DOI: 10.1186/s12864-016-3011-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 08/11/2016] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Rust fungi are an important group of plant pathogens that cause devastating losses in agricultural, silvicultural and natural ecosystems. Plants can be protected from rust disease by resistance genes encoding receptors that trigger a highly effective defence response upon recognition of specific pathogen avirulence proteins. Identifying avirulence genes is crucial for understanding how virulence evolves in the field. RESULTS To facilitate avirulence gene cloning in the flax rust fungus, Melampsora lini, we constructed a high-density genetic linkage map using single nucleotide polymorphisms detected in restriction site-associated DNA sequencing (RADseq) data. The map comprises 13,412 RADseq markers in 27 linkage groups that together span 5860 cM and contain 2756 recombination bins. The marker sequences were used to anchor 68.9 % of the M. lini genome assembly onto the genetic map. The map and anchored assembly were then used to: 1) show that M. lini has a high overall meiotic recombination rate, but recombination distribution is uneven and large coldspots exist; 2) show that substantial genome rearrangements have occurred in spontaneous loss-of-avirulence mutants; and 3) identify the AvrL2 and AvrM14 avirulence genes by map-based cloning. AvrM14 is a dual-specificity avirulence gene that encodes a predicted nudix hydrolase. AvrL2 is located in the region of the M. lini genome with the lowest recombination rate and encodes a small, highly-charged proline-rich protein. CONCLUSIONS The M. lini high-density linkage map has greatly advanced our understanding of virulence mechanisms in this pathogen by providing novel insights into genome variability and enabling identification of two new avirulence genes.
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Affiliation(s)
- Claire Anderson
- Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 2601 Australia
| | - Muhammad Adil Khan
- Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 2601 Australia
- Current address: ARC Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Ann-Maree Catanzariti
- Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 2601 Australia
| | - Cameron A. Jack
- ANU Bioinformatics Consulting Unit, The John Curtin School of Medical Research, The Australian National University, 131 Garran Road, Acton, ACT 2601 Australia
| | - Adnane Nemri
- CSIRO Agriculture, GPO Box 1600, Canberra, ACT 2601 Australia
- Current address: KWS SAAT SE, Grimsehlstraße 31, Einbeck, 37574 Germany
| | | | | | - Adrienne R. Hardham
- Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 2601 Australia
| | | | - Peter N. Dodds
- CSIRO Agriculture, GPO Box 1600, Canberra, ACT 2601 Australia
| | - David A. Jones
- Research School of Biology, The Australian National University, 134 Linnaeus Way, Acton, ACT 2601 Australia
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Arango Isaza RE, Diaz-Trujillo C, Dhillon B, Aerts A, Carlier J, Crane CF, V. de Jong T, de Vries I, Dietrich R, Farmer AD, Fortes Fereira C, Garcia S, Guzman M, Hamelin RC, Lindquist EA, Mehrabi R, Quiros O, Schmutz J, Shapiro H, Reynolds E, Scalliet G, Souza M, Stergiopoulos I, Van der Lee TAJ, De Wit PJGM, Zapater MF, Zwiers LH, Grigoriev IV, Goodwin SB, Kema GHJ. Combating a Global Threat to a Clonal Crop: Banana Black Sigatoka Pathogen Pseudocercospora fijiensis (Synonym Mycosphaerella fijiensis) Genomes Reveal Clues for Disease Control. PLoS Genet 2016; 12:e1005876. [PMID: 27512984 PMCID: PMC4981457 DOI: 10.1371/journal.pgen.1005876] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 01/27/2016] [Indexed: 12/03/2022] Open
Abstract
Black Sigatoka or black leaf streak disease, caused by the Dothideomycete fungus Pseudocercospora fijiensis (previously: Mycosphaerella fijiensis), is the most significant foliar disease of banana worldwide. Due to the lack of effective host resistance, management of this disease requires frequent fungicide applications, which greatly increase the economic and environmental costs to produce banana. Weekly applications in most banana plantations lead to rapid evolution of fungicide-resistant strains within populations causing disease-control failures throughout the world. Given its extremely high economic importance, two strains of P. fijiensis were sequenced and assembled with the aid of a new genetic linkage map. The 74-Mb genome of P. fijiensis is massively expanded by LTR retrotransposons, making it the largest genome within the Dothideomycetes. Melting-curve assays suggest that the genomes of two closely related members of the Sigatoka disease complex, P. eumusae and P. musae, also are expanded. Electrophoretic karyotyping and analyses of molecular markers in P. fijiensis field populations showed chromosome-length polymorphisms and high genetic diversity. Genetic differentiation was also detected using neutral markers, suggesting strong selection with limited gene flow at the studied geographic scale. Frequencies of fungicide resistance in fungicide-treated plantations were much higher than those in untreated wild-type P. fijiensis populations. A homologue of the Cladosporium fulvum Avr4 effector, PfAvr4, was identified in the P. fijiensis genome. Infiltration of the purified PfAVR4 protein into leaves of the resistant banana variety Calcutta 4 resulted in a hypersensitive-like response. This result suggests that Calcutta 4 could carry an unknown resistance gene recognizing PfAVR4. Besides adding to our understanding of the overall Dothideomycete genome structures, the P. fijiensis genome will aid in developing fungicide treatment schedules to combat this pathogen and in improving the efficiency of banana breeding programs.
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Affiliation(s)
- Rafael E. Arango Isaza
- Escuela de Biociencias, Universidad Nacional de Colombia, Medellín, Colombia
- Plant Biotechnology Unit, Corporación Para Investigaciones Biológicas, Medellín, Colombia
| | | | - Braham Dhillon
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana, United States of America
| | - Andrea Aerts
- US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | | | - Charles F. Crane
- USDA-Agricultural Research Service, West Lafayette, Indiana, United States of America
| | - Tristan V. de Jong
- Plant Research International, Wageningen University and Research, Wageningen, The Netherlands
| | - Ineke de Vries
- Plant Research International, Wageningen University and Research, Wageningen, The Netherlands
| | - Robert Dietrich
- Syngenta Biotechnology Inc., Research Triangle Park, United States of America
| | - Andrew D. Farmer
- National Center for Genome Resources, Santa Fe, United States of America
| | | | | | - Mauricio Guzman
- National Banana Corporation of Costa Rica (CORBANA), La Rita de Pococí, Limón, Costa Rica
| | - Richard C. Hamelin
- Department of Forest and Conservation Sciences, The University of British Columbia, Vancouver, BC, Canada
- Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, Québec, QC, Canada
| | - Erika A. Lindquist
- US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Rahim Mehrabi
- Department of Genetics, Seed and Plant Improvement Institute, Karaj, Iran
| | - Olman Quiros
- National Banana Corporation of Costa Rica (CORBANA), La Rita de Pococí, Limón, Costa Rica
| | - Jeremy Schmutz
- US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Harris Shapiro
- US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Elizabeth Reynolds
- General Bioinformatics at Syngenta Crop protection Jeallots Hill International Research Centre, Bracknell Berkshire, United Kingdom
| | | | - Manoel Souza
- Embrapa-LABEX Europe, Wageningen, The Netherlands
| | | | - Theo A. J. Van der Lee
- Plant Research International, Wageningen University and Research, Wageningen, The Netherlands
| | | | | | | | - Igor V. Grigoriev
- US Department of Energy Joint Genome Institute, Walnut Creek, California, United States of America
| | - Stephen B. Goodwin
- USDA-Agricultural Research Service, West Lafayette, Indiana, United States of America
| | - Gert H. J. Kema
- Plant Research International, Wageningen University and Research, Wageningen, The Netherlands
- Wageningen University, Laboratory of Phytopathology, Wageningen, The Netherlands
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Testa AC, Oliver RP, Hane JK. OcculterCut: A Comprehensive Survey of AT-Rich Regions in Fungal Genomes. Genome Biol Evol 2016; 8:2044-64. [PMID: 27289099 PMCID: PMC4943192 DOI: 10.1093/gbe/evw121] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2016] [Indexed: 12/03/2022] Open
Abstract
We present a novel method to measure the local GC-content bias in genomes and a survey of published fungal species. The method, enacted as "OcculterCut" (https://sourceforge.net/projects/occultercut, last accessed April 30, 2016), identified species containing distinct AT-rich regions. In most fungal taxa, AT-rich regions are a signature of repeat-induced point mutation (RIP), which targets repetitive DNA and decreases GC-content though the conversion of cytosine to thymine bases. RIP has in turn been identified as a driver of fungal genome evolution, as RIP mutations can also occur in single-copy genes neighboring repeat-rich regions. Over time RIP perpetuates "two speeds" of gene evolution in the GC-equilibrated and AT-rich regions of fungal genomes. In this study, genomes showing evidence of this process are found to be common, particularly among the Pezizomycotina. Further analysis highlighted differences in amino acid composition and putative functions of genes from these regions, supporting the hypothesis that these regions play an important role in fungal evolution. OcculterCut can also be used to identify genes undergoing RIP-assisted diversifying selection, such as small, secreted effector proteins that mediate host-microbe disease interactions.
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Affiliation(s)
- Alison C Testa
- Department of Environment & Agriculture, Centre for Crop and Disease Management, Curtin University, Perth, Australia
| | - Richard P Oliver
- Department of Environment & Agriculture, Centre for Crop and Disease Management, Curtin University, Perth, Australia
| | - James K Hane
- Department of Environment & Agriculture, Centre for Crop and Disease Management, Curtin University, Perth, Australia Curtin Institute for Computation, Curtin University, Perth, Australia
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35
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Williams AH, Sharma M, Thatcher LF, Azam S, Hane JK, Sperschneider J, Kidd BN, Anderson JP, Ghosh R, Garg G, Lichtenzveig J, Kistler HC, Shea T, Young S, Buck SAG, Kamphuis LG, Saxena R, Pande S, Ma LJ, Varshney RK, Singh KB. Comparative genomics and prediction of conditionally dispensable sequences in legume-infecting Fusarium oxysporum formae speciales facilitates identification of candidate effectors. BMC Genomics 2016; 17:191. [PMID: 26945779 PMCID: PMC4779268 DOI: 10.1186/s12864-016-2486-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 02/17/2016] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Soil-borne fungi of the Fusarium oxysporum species complex cause devastating wilt disease on many crops including legumes that supply human dietary protein needs across many parts of the globe. We present and compare draft genome assemblies for three legume-infecting formae speciales (ff. spp.): F. oxysporum f. sp. ciceris (Foc-38-1) and f. sp. pisi (Fop-37622), significant pathogens of chickpea and pea respectively, the world's second and third most important grain legumes, and lastly f. sp. medicaginis (Fom-5190a) for which we developed a model legume pathosystem utilising Medicago truncatula. RESULTS Focusing on the identification of pathogenicity gene content, we leveraged the reference genomes of Fusarium pathogens F. oxysporum f. sp. lycopersici (tomato-infecting) and F. solani (pea-infecting) and their well-characterised core and dispensable chromosomes to predict genomic organisation in the newly sequenced legume-infecting isolates. Dispensable chromosomes are not essential for growth and in Fusarium species are known to be enriched in host-specificity and pathogenicity-associated genes. Comparative genomics of the publicly available Fusarium species revealed differential patterns of sequence conservation across F. oxysporum formae speciales, with legume-pathogenic formae speciales not exhibiting greater sequence conservation between them relative to non-legume-infecting formae speciales, possibly indicating the lack of a common ancestral source for legume pathogenicity. Combining predicted dispensable gene content with in planta expression in the model legume-infecting isolate, we identified small conserved regions and candidate effectors, four of which shared greatest similarity to proteins from another legume-infecting ff. spp. CONCLUSIONS We demonstrate that distinction of core and potential dispensable genomic regions of novel F. oxysporum genomes is an effective tool to facilitate effector discovery and the identification of gene content possibly linked to host specificity. While the legume-infecting isolates didn't share large genomic regions of pathogenicity-related content, smaller regions and candidate effector proteins were highly conserved, suggesting that they may play specific roles in inducing disease on legume hosts.
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Affiliation(s)
- Angela H Williams
- The Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Mamta Sharma
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - Louise F Thatcher
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Sarwar Azam
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - James K Hane
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
- Department of Environment and Agriculture, Curtin Institute for Computation, and CCDM Bioinformatics, Centre for Crop and Disease Management, Curtin University, Perth, WA, 6102, Australia.
| | - Jana Sperschneider
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Brendan N Kidd
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Jonathan P Anderson
- The Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Raju Ghosh
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - Gagan Garg
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Judith Lichtenzveig
- Department of Environment and Agriculture, Pulse Pathology and Genetics, Centre for Crop and Disease Management and Curtin Institute for Computation, Curtin University, Perth, WA, 6102, Australia.
| | - H Corby Kistler
- USDA-ARS, Cereal Disease Laboratory, University of Minnesota, St Paul, MN, 55108, USA.
| | | | - Sarah Young
- The Broad Institute, Cambridge, MA, 02141, USA.
| | - Sally-Anne G Buck
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Lars G Kamphuis
- The Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
| | - Rachit Saxena
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - Suresh Pande
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - Li-Jun Ma
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, 01003, USA.
| | - Rajeev K Varshney
- The Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
- International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, Greater Hyderabad, 502324, Telangana, India.
| | - Karam B Singh
- The Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia.
- CSIRO Agriculture, Centre for Environment and Life Sciences, Wembley, WA, 6913, Australia.
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Milgroom MG, Jiménez-Gasco MDM, Olivares García C, Drott MT, Jiménez-Díaz RM. Recombination between clonal lineages of the asexual fungus Verticillium dahliae detected by genotyping by sequencing. PLoS One 2014; 9:e106740. [PMID: 25181515 PMCID: PMC4152335 DOI: 10.1371/journal.pone.0106740] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 08/09/2014] [Indexed: 11/18/2022] Open
Abstract
Most asexual species of fungi have either lost sexuality recently, or they experience recombination by cryptic sexual reproduction. Verticillium dahliae is a plant-pathogenic, ascomycete fungus with no known sexual stage, even though related genera have well-described sexual reproduction. V. dahliae reproduces mitotically and its population structure is highly clonal. However, previously described discrepancies in phylogenetic relationships among clonal lineages may be explained more parsimoniously by recombination than mutation; therefore, we looked for evidence of recombination within and between clonal lineages. Genotyping by sequencing was performed on 141 V. dahliae isolates from diverse geographic and host origins, resulting in 26,748 single-nucleotide polymorphisms (SNPs). We found a strongly clonal population structure with the same lineages as described previously by vegetative compatibility groups (VCGs) and molecular markers. We detected 443 recombination events, evenly distributed throughout the genome. Most recombination events detected were between clonal lineages, with relatively few recombinant haplotypes detected within lineages. The only three isolates with mating type MAT1-1 had recombinant SNP haplotypes; all other isolates had mating type MAT1-2. We found homologs of eight meiosis-specific genes in the V. dahliae genome, all with conserved or partially conserved protein domains. The extent of recombination and molecular signs of sex in (mating-type and meiosis-specific genes) suggest that V. dahliae clonal lineages arose by recombination, even though the current population structure is markedly clonal. Moreover, the detection of new lineages may be evidence that sexual reproduction has occurred recently and may potentially occur under some circumstances. We speculate that the current clonal population structure, despite the sexual origin of lineages, has arisen, in part, as a consequence of agriculture and selection for adaptation to agricultural cropping systems.
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Affiliation(s)
- Michael G. Milgroom
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - María del Mar Jiménez-Gasco
- Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Concepción Olivares García
- College of Agriculture and Forestry, University of Córdoba, and Institute for Sustainable Agriculture, CSIC, Campus de Excelencia Internacional Agroalimentario, ceiA3, Córdoba, Spain
| | - Milton T. Drott
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Rafael M. Jiménez-Díaz
- College of Agriculture and Forestry, University of Córdoba, and Institute for Sustainable Agriculture, CSIC, Campus de Excelencia Internacional Agroalimentario, ceiA3, Córdoba, Spain
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Sasaki AA, Fernandes GF, Rodrigues AM, Lima FM, Marini MM, dos S. Feitosa L, de Melo Teixeira M, Felipe MSS, da Silveira JF, de Camargo ZP. Chromosomal polymorphism in the Sporothrix schenckii complex. PLoS One 2014; 9:e86819. [PMID: 24466257 PMCID: PMC3900657 DOI: 10.1371/journal.pone.0086819] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 12/14/2013] [Indexed: 01/18/2023] Open
Abstract
Sporotrichosis is a polymorphic disease caused by a complex of thermodimorphic fungi including S. brasiliensis, S. schenckii sensu stricto (s. str.), S. globosa and S. luriei. Humans and animals can acquire the disease through traumatic inoculation of propagules into the subcutaneous tissue. Despite the importance of sporotrichosis as a disease that can take epidemic proportions there are just a few studies dealing with genetic polymorphisms and genomic architecture of these pathogens. The main objective of this study was to investigate chromosomal polymorphisms and genomic organization among different isolates in the S. schenckii complex. We used pulsed field gel electrophoresis (PFGE) to separate chromosomal fragments of isolated DNA, followed by probe hybridization. Nine loci (β-tubulin, calmodulin, catalase, chitin synthase 1, Internal Transcribed Spacer, Pho85 cyclin-dependent kinase, protein kinase C Ss-2, G protein α subunit and topoisomerase II) were mapped onto chromosomal bands of Brazilian isolates of S. schenckii s. str. and S. brasiliensis. Our results revealed the presence of intra and interspecies polymorphisms in chromosome number and size. The gene hybridization analysis showed that closely related species in phylogenetic analysis had similar genetic organizations, mostly due to identification of synteny groups in chromosomal bands of similar sizes. Our results bring new insights into the genetic diversity and genome organization among pathogenic species in the Sporothrix schenckii complex.
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Affiliation(s)
- Alexandre A. Sasaki
- Discipline of Cellular Biology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Geisa F. Fernandes
- Discipline of Cellular Biology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Anderson M. Rodrigues
- Discipline of Cellular Biology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Fábio M. Lima
- Discipline of Parasitology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Marjorie M. Marini
- Discipline of Parasitology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Luciano dos S. Feitosa
- Biomedical Engineering Center, Camilo Castelo Branco University, São Paulo, São Paulo, Brazil
| | - Marcus de Melo Teixeira
- Department of Cell Biology, Biological Sciences Institute, University of Brasília, Brasília, Distrito Federal, Brazil
| | - Maria Sueli Soares Felipe
- Department of Cell Biology, Biological Sciences Institute, University of Brasília, Brasília, Distrito Federal, Brazil
- Genomic Sciences and Biotechnology, Catholic University of Brasília, Brasília, Distrito Federal, Brazil
| | - José Franco da Silveira
- Discipline of Parasitology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Zoilo P. de Camargo
- Discipline of Cellular Biology, Department of Microbiology, Immunology and Parasitology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
- * E-mail:
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Breakage-fusion-bridge cycles and large insertions contribute to the rapid evolution of accessory chromosomes in a fungal pathogen. PLoS Genet 2013; 9:e1003567. [PMID: 23785303 PMCID: PMC3681731 DOI: 10.1371/journal.pgen.1003567] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 05/01/2013] [Indexed: 12/12/2022] Open
Abstract
Chromosomal rearrangements are a major driver of eukaryotic genome evolution, affecting speciation, pathogenicity and cancer progression. Changes in chromosome structure are often initiated by mis-repair of double-strand breaks in the DNA. Mis-repair is particularly likely when telomeres are lost or when dispersed repeats misalign during crossing-over. Fungi carry highly polymorphic chromosomal complements showing substantial variation in chromosome length and number. The mechanisms driving chromosome polymorphism in fungi are poorly understood. We aimed to identify mechanisms of chromosomal rearrangements in the fungal wheat pathogen Zymoseptoria tritici. We combined population genomic resequencing and chromosomal segment PCR assays with electrophoretic karyotyping and resequencing of parents and offspring from experimental crosses to show that this pathogen harbors a highly diverse complement of accessory chromosomes that exhibits strong global geographic differentiation in numbers and lengths of chromosomes. Homologous chromosomes carried highly differentiated gene contents due to numerous insertions and deletions. The largest accessory chromosome recently doubled in length through insertions totaling 380 kb. Based on comparative genomics, we identified the precise breakpoint locations of these insertions. Nondisjunction during meiosis led to chromosome losses in progeny of three different crosses. We showed that a new accessory chromosome emerged in two viable offspring through a fusion between sister chromatids. Such chromosome fusion is likely to initiate a breakage-fusion-bridge (BFB) cycle that can rapidly degenerate chromosomal structure. We suggest that the accessory chromosomes of Z. tritici originated mainly from ancient core chromosomes through a degeneration process that included BFB cycles, nondisjunction and mutational decay of duplicated sequences. The rapidly evolving accessory chromosome complement may serve as a cradle for adaptive evolution in this and other fungal pathogens.
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de Jonge R, Bolton MD, Kombrink A, van den Berg GCM, Yadeta KA, Thomma BPHJ. Extensive chromosomal reshuffling drives evolution of virulence in an asexual pathogen. Genome Res 2013; 23:1271-82. [PMID: 23685541 PMCID: PMC3730101 DOI: 10.1101/gr.152660.112] [Citation(s) in RCA: 206] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Sexual recombination drives genetic diversity in eukaryotic genomes and fosters adaptation to novel environmental challenges. Although strictly asexual microorganisms are often considered as evolutionary dead ends, they comprise many devastating plant pathogens. Presently, it remains unknown how such asexual pathogens generate the genetic variation that is required for quick adaptation and evolution in the arms race with their hosts. Here, we show that extensive chromosomal rearrangements in the strictly asexual plant pathogenic fungus Verticillium dahliae establish highly dynamic lineage-specific (LS) genomic regions that act as a source for genetic variation to mediate aggressiveness. We show that such LS regions are greatly enriched for in planta-expressed effector genes encoding secreted proteins that enable host colonization. The LS regions occur at the flanks of chromosomal breakpoints and are enriched for retrotransposons and other repetitive sequence elements. Our results suggest that asexual pathogens may evolve by prompting chromosomal rearrangements, enabling rapid development of novel effector genes. Likely, chromosomal reshuffling can act as a general mechanism for adaptation in asexually propagating organisms.
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Affiliation(s)
- Ronnie de Jonge
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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Abstract
Reproductive isolation is an essential ingredient of speciation, and much has been learned in recent years about the evolution of reproductive isolation and the genetics of reproductive barriers in animals and plants. Fungi have been neglected on these aspects, despite being tractable model eukaryotes. Here, we used a model fitting approach to look at the importance of different barriers to gene flow to explain the decrease of reproductive compatibility with genetic distance in fungi. We found support for the occurrence of reinforcement in the presyngamy compatibility among basidiomycetes. In contrast, no evidence for reinforcement was detected in ascomycetes, concurring with the idea that host/habitat adaptation in this group can pleiotropically cause reproductive isolation. We found no evidence of a snowballing accumulation of postsyngamic reproductive incompatibilities in either ascomycetes or the complex of anther smut fungi. Together with previous studies, our results suggest that ecologically based barriers to gene flow and karyotypic differences may have an important role in hybrid inviability and sterility in fungi. Interestingly, hybrid sterility appeared to evolve faster than hybrid inviability in fungi.
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D'Hondt L, Höfte M, Van Bockstaele E, Leus L. Applications of flow cytometry in plant pathology for genome size determination, detection and physiological status. MOLECULAR PLANT PATHOLOGY 2011; 12:815-28. [PMID: 21726378 PMCID: PMC6640489 DOI: 10.1111/j.1364-3703.2011.00711.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Flow cytometers are probably the most multipurpose laboratory devices available. They can analyse a vast and very diverse range of cell parameters. This technique has left its mark on cancer, human immunodeficiency virus and immunology research, and is indispensable in routine clinical diagnostics. Flow cytometry (FCM) is also a well-known tool for the detection and physiological status assessment of microorganisms in drinking water, marine environments, food and fermentation processes. However, flow cytometers are seldom used in plant pathology, despite FCM's major advantages as both a detection method and a research tool. Potential uses of FCM include the characterization of genome sizes of fungal and oomycete populations, multiplexed pathogen detection and the monitoring of the viability, culturability and gene expression of plant pathogens, and many others. This review provides an overview of the history, advantages and disadvantages of FCM, and focuses on the current applications and future possibilities of FCM in plant pathology.
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Affiliation(s)
- Liesbet D'Hondt
- Plant Sciences Unit, Institute for Agricultural and Fisheries Research, Caritasstraat 21, 9090 Melle, Belgium.
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Inderbitzin P, Davis RM, Bostock RM, Subbarao KV. The ascomycete Verticillium longisporum is a hybrid and a plant pathogen with an expanded host range. PLoS One 2011; 6:e18260. [PMID: 21455321 PMCID: PMC3063834 DOI: 10.1371/journal.pone.0018260] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 02/23/2011] [Indexed: 01/24/2023] Open
Abstract
Hybridization plays a central role in plant evolution, but its overall importance in fungi is unknown. New plant pathogens are thought to arise by hybridization between formerly separated fungal species. Evolution of hybrid plant pathogens from non-pathogenic ancestors in the fungal-like protist Phytophthora has been demonstrated, but in fungi, the most important group of plant pathogens, there are few well-characterized examples of hybrids. We focused our attention on the hybrid and plant pathogen Verticillium longisporum, the causal agent of the Verticillium wilt disease in crucifer crops. In order to address questions related to the evolutionary origin of V. longisporum, we used phylogenetic analyses of seven nuclear loci and a dataset of 203 isolates of V. longisporum, V. dahliae and related species. We confirmed that V. longisporum was diploid, and originated three different times, involving four different lineages and three different parental species. All hybrids shared a common parent, species A1, that hybridized respectively with species D1, V. dahliae lineage D2 and V. dahliae lineage D3, to give rise to three different lineages of V. longisporum. Species A1 and species D1 constituted as yet unknown taxa. Verticillium longisporum likely originated recently, as each V. longisporum lineage was genetically homogenous, and comprised species A1 alleles that were identical across lineages.
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Affiliation(s)
- Patrik Inderbitzin
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - R. Michael Davis
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Richard M. Bostock
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
| | - Krishna V. Subbarao
- Department of Plant Pathology, University of California Davis, Davis, California, United States of America
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Abstract
Cryptococcus gattii recently emerged as the causative agent of cryptococcosis in healthy individuals in western North America, despite previous characterization of the fungus as a pathogen in tropical or subtropical regions. As a foundation to study the genetics of virulence in this pathogen, we sequenced the genomes of a strain (WM276) representing the predominant global molecular type (VGI) and a clinical strain (R265) of the major genotype (VGIIa) causing disease in North America. We compared these C. gattii genomes with each other and with the genomes of representative strains of the two varieties of Cryptococcus neoformans that generally cause disease in immunocompromised people. Our comparisons included chromosome alignments, analysis of gene content and gene family evolution, and comparative genome hybridization (CGH). These studies revealed that the genomes of the two representative C. gattii strains (genotypes VGI and VGIIa) are colinear for the majority of chromosomes, with some minor rearrangements. However, multiortholog phylogenetic analysis and an evaluation of gene/sequence conservation support the existence of speciation within the C. gattii complex. More extensive chromosome rearrangements were observed upon comparison of the C. gattii and the C. neoformans genomes. Finally, CGH revealed considerable variation in clinical and environmental isolates as well as changes in chromosome copy numbers in C. gattii isolates displaying fluconazole heteroresistance. Isolates of Cryptococcus gattii are currently causing an outbreak of cryptococcosis in western North America, and most of the cases occurred in the absence of coinfection with HIV. This pattern is therefore in stark contrast to the current global burden of one million annual cases of cryptococcosis, caused by the related species Cryptococcus neoformans, in the HIV/AIDS population. The genome sequences of two outbreak-associated major genotypes of C. gattii reported here provide insights into genome variation within and between cryptococcal species. These sequences also provide a resource to further evaluate the epidemiology of cryptococcal disease and to evaluate the role of pathogen genes in the differential interactions of C. gattii and C. neoformans with immunocompromised and immunocompetent hosts.
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Sionov E, Lee H, Chang YC, Kwon-Chung KJ. Cryptococcus neoformans overcomes stress of azole drugs by formation of disomy in specific multiple chromosomes. PLoS Pathog 2010; 6:e1000848. [PMID: 20368972 PMCID: PMC2848560 DOI: 10.1371/journal.ppat.1000848] [Citation(s) in RCA: 246] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Accepted: 03/05/2010] [Indexed: 12/20/2022] Open
Abstract
Cryptococcus neoformans is a haploid environmental organism and the major cause of fungal meningoencephalitis in AIDS patients. Fluconazole (FLC), a triazole, is widely used for the maintenance therapy of cryptococcosis. Heteroresistance to FLC, an adaptive mode of azole resistance, was associated with FLC therapy failure cases but the mechanism underlying the resistance was unknown. We used comparative genome hybridization and quantitative real-time PCR in order to show that C. neoformans adapts to high concentrations of FLC by duplication of multiple chromosomes. Formation of disomic chromosomes in response to FLC stress was observed in both serotype A and D strains. Strains that adapted to FLC concentrations higher than their minimal inhibitory concentration (MIC) contained disomies of chromosome 1 and stepwise exposure to even higher drug concentrations induced additional duplications of several other specific chromosomes. The number of disomic chromosomes in each resistant strain directly correlated with the concentration of FLC tolerated by each strain. Upon removal of the drug pressure, strains that had adapted to high concentrations of FLC returned to their original level of susceptibility by initially losing the extra copy of chromosome 1 followed by loss of the extra copies of the remaining disomic chromosomes. The duplication of chromosome 1 was closely associated with two of its resident genes: ERG11, the target of FLC and AFR1, the major transporter of azoles in C. neoformans. This adaptive mechanism in C. neoformans may play an important role in FLC therapy failure of cryptococcosis leading to relapse during azole maintenance therapy. Cryptococcus neoformans is an environmental fungus that causes life threatening brain disease, primarily in AIDS patients. The disease is estimated to claim 700,000 lives annually world-wide but most heavily in Africa. Fluconazole (FLC), a fungistatic antifungal drug, is commonly used to treat patients for long term maintenance therapy. Recurrence of cryptococcosis in AIDS patients undergoing FLC maintenance therapy has been increasingly reported. Heteroresistance, an adaptive azole resistance, was associated with FLC therapy failure cases but the mechanism underlying the resistance was unknown. We previously described that C. neoformans strains are innately heteroresistant to FLC; each strain producing a fraction of subpopulation that can tolerate a high concentration of the drug. These resistant subpopulations revert to original phenotype during maintenance in drug free media. Various methods including cDNA microarrays, comparative genome hybridization and quantitative PCR have been applied to uncover the mechanism involved in the adaptation of C. neoformans to high concentrations of FLC and subsequent loss of resistance upon the removal of drug pressure. We discovered that C. neoformans adapts to high concentration of FLC by formation of disomy in multiple chromosomes. The removal of drug pressure results in a sequential loss of the extra chromosomal copies. It is likely that this novel mechanism of adaptation contributes to the failure of FLC therapy for cryptococcosis.
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Affiliation(s)
- Edward Sionov
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, United States of America
| | - Hyeseung Lee
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, United States of America
| | - Yun C. Chang
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, United States of America
| | - Kyung J. Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, Maryland, United States of America
- * E-mail:
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Gilbert GS, Parker IM. Rapid evolution in a plant-pathogen interaction and the consequences for introduced host species. Evol Appl 2010; 3:144-56. [PMID: 25567915 PMCID: PMC3352484 DOI: 10.1111/j.1752-4571.2009.00107.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 10/26/2009] [Indexed: 11/30/2022] Open
Abstract
Plant species introduced into new regions can both leave behind co-evolved pathogens and acquire new ones. Traits important to infection and virulence are subject to rapid evolutionary change in both plant and pathogen. Using Stemphylium solani, a native foliar necrotroph on clovers (Trifolium and Medicago) in California, USA, we explore how plant-fungal interactions may change in an invasion context. After four generations of experimental serial passage through multiple hosts, Stemphylium consistently showed increased infection rates but no consistent change in damage to the host. In a historical opportunity study, we compared infection and virulence across four groups of clover hosts: California natives, European clovers not found in California, and both California and European genotypes of species naturalized in California. There was significant variation among hosts, but no pattern across the four groups. However, in direct comparisons of familiar California genotypes to unfamiliar European genotypes of the same naturalized species, Stemphylium consistently infected familiar hosts more frequently, while causing less damage on them. This pattern is consistent with the hypothesis of adaptive evolution in both the pathogen (ability to infect) and the host (tolerance of infection). Together these results suggest the potential for rapid evolution to alter interactions between plant invaders and their natural enemies.
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Affiliation(s)
- Gregory S Gilbert
- Environmental Studies Department, University of California Santa Cruz, CA, USA
| | - Ingrid M Parker
- Ecology and Evolutionary Biology, University of California Santa Cruz, CA, USA
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46
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Meiosis drives extraordinary genome plasticity in the haploid fungal plant pathogen Mycosphaerella graminicola. PLoS One 2009; 4:e5863. [PMID: 19516898 PMCID: PMC2689623 DOI: 10.1371/journal.pone.0005863] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2008] [Accepted: 03/27/2009] [Indexed: 11/24/2022] Open
Abstract
Meiosis in the haploid plant-pathogenic fungus Mycosphaerella graminicola results in eight ascospores due to a mitotic division following the two meiotic divisions. The transient diploid phase allows for recombination among homologous chromosomes. However, some chromosomes of M. graminicola lack homologs and do not pair during meiosis. Because these chromosomes are not present universally in the genome of the organism they can be considered to be dispensable. To analyze the meiotic transmission of unequal chromosome numbers, two segregating populations were generated by crossing genetically unrelated parent isolates originating from Algeria and The Netherlands that had pathogenicity towards durum or bread wheat, respectively. Detailed genetic analyses of these progenies using high-density mapping (1793 DArT, 258 AFLP and 25 SSR markers) and graphical genotyping revealed that M. graminicola has up to eight dispensable chromosomes, the highest number reported in filamentous fungi. These chromosomes vary from 0.39 to 0.77 Mb in size, and represent up to 38% of the chromosomal complement. Chromosome numbers among progeny isolates varied widely, with some progeny missing up to three chromosomes, while other strains were disomic for one or more chromosomes. Between 15–20% of the progeny isolates lacked one or more chromosomes that were present in both parents. The two high-density maps showed no recombination of dispensable chromosomes and hence, their meiotic processing may require distributive disjunction, a phenomenon that is rarely observed in fungi. The maps also enabled the identification of individual twin isolates from a single ascus that shared the same missing or doubled chromosomes indicating that the chromosomal polymorphisms were mitotically stable and originated from nondisjunction during the second division and, less frequently, during the first division of fungal meiosis. High genome plasticity could be among the strategies enabling this versatile pathogen to quickly overcome adverse biotic and abiotic conditions in wheat fields.
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Sun S, Xu J. Chromosomal rearrangements between serotype A and D strains in Cryptococcus neoformans. PLoS One 2009; 4:e5524. [PMID: 19436753 PMCID: PMC2677675 DOI: 10.1371/journal.pone.0005524] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 01/18/2009] [Indexed: 12/30/2022] Open
Abstract
Cryptococcus neoformans is a major human pathogenic fungus that can cause meningoencephalitis in immunocompromised hosts. It contains two divergent varieties, var. grubii (serotype A) and var. neoformans (serotype D), as well as hybrids (serotype AD) between these two varieties. In this study, we investigated the extent of chromosomal rearrangements between the two varieties, estimated the effects of chromosomal rearrangements on recombination frequencies, and surveyed the potential polymorphisms of the rearrangements among natural strains of the three serotypes. Through the analyses of two sequenced genomes from strains H99 (representing var. grubii) and JEC21 (representing var. neoformans), we revealed a total of 32 unambiguous chromosome rearrangements, including five translocations, nine simple inversions, and 18 complex rearrangements. Our analyses identified that overall, rearranged regions had recombination frequencies about half of those around syntenic regions. Using a direct PCR screening strategy, we examined the potential polymorphisms of 11 rearrangements among 64 natural C. neoformans strains from five countries. We found no polymorphism within var. neoformans and very limited polymorphism within var. grubii. However, strains of serotype AD showed significant polymorphism, consistent with their hybrid origins coupled with differential loss of heterozygosity. We discuss the implications of these results on the genome structure, ecology, and evolution of C. neoformans.
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Affiliation(s)
- Sheng Sun
- Department of Biology, McMaster University, Hamilton, Ontario, Canada.
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Pérez G, Pangilinan J, Pisabarro AG, Ramírez L. Telomere organization in the ligninolytic basidiomycete Pleurotus ostreatus. Appl Environ Microbiol 2009; 75:1427-36. [PMID: 19114509 PMCID: PMC2648151 DOI: 10.1128/aem.01889-08] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Accepted: 12/21/2008] [Indexed: 01/19/2023] Open
Abstract
Telomeres are structural and functional chromosome regions that are essential for the cell cycle to proceed normally. They are, however, difficult to map genetically and to identify in genome-wide sequence programs because of their structure and repetitive nature. We studied the telomeric and subtelomeric organization in the basidiomycete Pleurotus ostreatus using a combination of molecular and bioinformatics tools that permitted us to determine 19 out of the 22 telomeres expected in this fungus. The telomeric repeating unit in P. ostreatus is TTAGGG, and the numbers of repetitions of this unit range between 25 and 150. The mapping of the telomere restriction fragments to linkage groups 6 and 7 revealed polymorphisms compatible with those observed by pulsed field gel electrophoresis separation of the corresponding chromosomes. The subtelomeric regions in Pleurotus contain genes similar to those described in other eukaryotic systems. The presence of a cluster of laccase genes in chromosome 6 and a bipartite structure containing a Het-related protein and an alcohol dehydrogenase are especially relevant; this bipartite structure is characteristic of the Pezizomycotina fungi Neurospora crassa and Aspergillus terreus. As far as we know, this is the first report describing the presence of such structures in basidiomycetes and the location of a laccase gene cluster in the subtelomeric region, where, among others, species-specific genes allowing the organism to adapt rapidly to the environment usually map.
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Affiliation(s)
- Gúmer Pérez
- Genetics and Microbiology Research Group, Department of Agrarian Production, Public University of Navarre, 31006 Pamplona, Spain
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Aboukhaddour R, Cloutier S, Ballance GM, Lamari L. Genome characterization of Pyrenophora tritici-repentis isolates reveals high plasticity and independent chromosomal location of ToxA and ToxB. MOLECULAR PLANT PATHOLOGY 2009; 10:201-12. [PMID: 19236569 PMCID: PMC6640439 DOI: 10.1111/j.1364-3703.2008.00520.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The fungus Pyrenophora tritici-repentis (Died.) causes tan spot, an important leaf disease of wheat worldwide. Isolates of this pathogen have been collected and characterized into eight races on the basis of their ability to produce three different host-selective toxins. The karyotype of 47 isolates was determined by pulsed field gel electrophoresis. The collection originated from different parts of the world and included genotypes from all races. A single isolate was characterized for each of races 3, 4 and 6, whereas fourteen, five, nine, five and eleven isolates were karyotyped for races 1, 2, 5, 7 and 8, respectively. The survey showed that the chromosome number of P. tritici-repentis was highly variable, with some isolates having as few as eight chromosomes, but others having 11 or more. Similarly, the genome size ranged from 25.5 to 48.0 Mb, and individual chromosome sizes ranged from 1.3 to more than 5.7 Mb. Considerable variation was observed in karyotype patterns among the P. tritici-repentis isolates tested. A total of 29 different karyotypes was identified among the 47 isolates. These chromosome level variations were as variable for isolates within a race as for isolates across races. Southern blot analysis of the 47 isolates with ToxA and ToxB probes revealed that the toxin genes were always located on different chromosomes. Furthermore, with six chromosome-specific single-copy probes, the ToxA-carrying chromosome was shown to be homologous among the Ptr ToxA-producing isolates, with a related chromosome in the non-ToxA-producing isolates, suggesting that the chromosome on which ToxA generally resides is of an essential nature. Interestingly, a molecular rearrangement involving a translocation of ToxA to a different chromosome was identified in one isolate.
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Affiliation(s)
- R Aboukhaddour
- Department of Plant Science, 66 Dafoe Rd., University of Manitoba, Winnipeg, MB, Canada, R3T 2N2
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Hane JK, Lowe RGT, Solomon PS, Tan KC, Schoch CL, Spatafora JW, Crous PW, Kodira C, Birren BW, Galagan JE, Torriani SFF, McDonald BA, Oliver RP. Dothideomycete plant interactions illuminated by genome sequencing and EST analysis of the wheat pathogen Stagonospora nodorum. THE PLANT CELL 2007; 19:3347-68. [PMID: 18024570 PMCID: PMC2174895 DOI: 10.1105/tpc.107.052829] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Revised: 09/11/2007] [Accepted: 10/15/2007] [Indexed: 05/18/2023]
Abstract
Stagonospora nodorum is a major necrotrophic fungal pathogen of wheat (Triticum aestivum) and a member of the Dothideomycetes, a large fungal taxon that includes many important plant pathogens affecting all major crop plant families. Here, we report the acquisition and initial analysis of a draft genome sequence for this fungus. The assembly comprises 37,164,227 bp of nuclear DNA contained in 107 scaffolds. The circular mitochondrial genome comprises 49,761 bp encoding 46 genes, including four that are intron encoded. The nuclear genome assembly contains 26 classes of repetitive DNA, comprising 4.5% of the genome. Some of the repeats show evidence of repeat-induced point mutations consistent with a frequent sexual cycle. ESTs and gene prediction models support a minimum of 10,762 nuclear genes. Extensive orthology was found between the polyketide synthase family in S. nodorum and Cochliobolus heterostrophus, suggesting an ancient origin and conserved functions for these genes. A striking feature of the gene catalog was the large number of genes predicted to encode secreted proteins; the majority has no meaningful similarity to any other known genes. It is likely that genes for host-specific toxins, in addition to ToxA, will be found among this group. ESTs obtained from axenic mycelium grown on oleate (chosen to mimic early infection) and late-stage lesions sporulating on wheat leaves were obtained. Statistical analysis shows that transcripts encoding proteins involved in protein synthesis and in the production of extracellular proteases, cellulases, and xylanases predominate in the infection library. This suggests that the fungus is dependant on the degradation of wheat macromolecular constituents to provide the carbon skeletons and energy for the synthesis of proteins and other components destined for the developing pycnidiospores.
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MESH Headings
- Ascomycota/genetics
- DNA, Mitochondrial/genetics
- Expressed Sequence Tags
- Fungal Proteins/chemistry
- Fungal Proteins/genetics
- Gene Expression Regulation, Fungal
- Genes, Fungal
- Genome, Fungal/genetics
- Host-Parasite Interactions
- Multigene Family
- Phylogeny
- Protein Structure, Tertiary
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Transfer/genetics
- Repetitive Sequences, Nucleic Acid
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Triticum/microbiology
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Affiliation(s)
- James K Hane
- Australian Centre for Necrotrophic Fungal Pathogens, Murdoch University, WA 6150, Australia
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