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Mayer A, McLaughlin G, Gladfelter A, Glass NL, Mela A, Roper M. Syncytial Assembly Lines: Consequences of Multinucleate Cellular Compartments for Fungal Protein Synthesis. Results Probl Cell Differ 2024; 71:159-183. [PMID: 37996678 DOI: 10.1007/978-3-031-37936-9_9] [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: 11/25/2023]
Abstract
Fast growth and prodigious cellular outputs make fungi powerful tools in biotechnology. Recent modeling work has exposed efficiency gains associated with dividing the labor of transcription over multiple nuclei, and experimental innovations are opening new windows on the capacities and adaptations that allow nuclei to behave autonomously or in coordination while sharing a single, common cytoplasm. Although the motivation of our review is to motivate and connect recent work toward a greater understanding of fungal factories, we use the analogy of the assembly line as an organizing idea for studying coordinated gene expression, generally.
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Affiliation(s)
- Alex Mayer
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA
| | - Grace McLaughlin
- Department of Cell Biology, Duke University, Durham, NC, USA
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Amy Gladfelter
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Alexander Mela
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Marcus Roper
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Computational Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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2
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Aanen DK, van ’t Padje A, Auxier B. Longevity of Fungal Mycelia and Nuclear Quality Checks: a New Hypothesis for the Role of Clamp Connections in Dikaryons. Microbiol Mol Biol Rev 2023; 87:e0002221. [PMID: 37409939 PMCID: PMC10521366 DOI: 10.1128/mmbr.00022-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023] Open
Abstract
This paper addresses the stability of mycelial growth in fungi and differences between ascomycetes and basidiomycetes. Starting with general evolutionary theories of multicellularity and the role of sex, we then discuss individuality in fungi. Recent research has demonstrated the deleterious consequences of nucleus-level selection in fungal mycelia, favoring cheaters with a nucleus-level benefit during spore formation but a negative effect on mycelium-level fitness. Cheaters appear to generally be loss-of-fusion (LOF) mutants, with a higher propensity to form aerial hyphae developing into asexual spores. Since LOF mutants rely on heterokaryosis with wild-type nuclei, we argue that regular single-spore bottlenecks can efficiently select against such cheater mutants. We then zoom in on ecological differences between ascomycetes being typically fast-growing but short-lived with frequent asexual-spore bottlenecks and basidiomycetes being generally slow-growing but long-lived and usually without asexual-spore bottlenecks. We argue that these life history differences have coevolved with stricter nuclear quality checks in basidiomycetes. Specifically, we propose a new function for clamp connections, structures formed during the sexual stage in ascomycetes and basidiomycetes but during somatic growth only in basidiomycete dikaryons. During dikaryon cell division, the two haploid nuclei temporarily enter a monokaryotic phase, by alternatingly entering a retrograde-growing clamp cell, which subsequently fuses with the subapical cell to recover the dikaryotic cell. We hypothesize that clamp connections act as screening devices for nuclear quality, with both nuclei continuously testing each other for fusion ability, a test that LOF mutants will fail. By linking differences in longevity of the mycelial phase to ecology and stringency of nuclear quality checks, we propose that mycelia have a constant and low lifetime cheating risk, irrespective of their size and longevity.
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Affiliation(s)
- Duur K. Aanen
- Department of Plant Sciences, Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands
| | - Anouk van ’t Padje
- Department of Plant Sciences, Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands
| | - Benjamin Auxier
- Department of Plant Sciences, Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands
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3
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Vittorelli N, Rodríguez de la Vega RC, Snirc A, Levert E, Gautier V, Lalanne C, De Filippo E, Gladieux P, Guillou S, Zhang Y, Tejomurthula S, Grigoriev IV, Debuchy R, Silar P, Giraud T, Hartmann FE. Stepwise recombination suppression around the mating-type locus in an ascomycete fungus with self-fertile spores. PLoS Genet 2023; 19:e1010347. [PMID: 36763677 PMCID: PMC9949647 DOI: 10.1371/journal.pgen.1010347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 02/23/2023] [Accepted: 01/17/2023] [Indexed: 02/12/2023] Open
Abstract
Recombination is often suppressed at sex-determining loci in plants and animals, and at self-incompatibility or mating-type loci in plants and fungi. In fungal ascomycetes, recombination suppression around the mating-type locus is associated with pseudo-homothallism, i.e. the production of self-fertile dikaryotic sexual spores carrying the two opposite mating types. This has been well studied in two species complexes from different families of Sordariales: Podospora anserina and Neurospora tetrasperma. However, it is unclear whether this intriguing association holds in other species. We show here that Schizothecium tetrasporum, a fungus from a third family in the order Sordariales, also produces mostly self-fertile dikaryotic spores carrying the two opposite mating types. This was due to a high frequency of second meiotic division segregation at the mating-type locus, indicating the occurrence of a single and systematic crossing-over event between the mating-type locus and the centromere, as in P. anserina. The mating-type locus has the typical Sordariales organization, plus a MAT1-1-1 pseudogene in the MAT1-2 haplotype. High-quality genome assemblies of opposite mating types and segregation analyses revealed a suppression of recombination in a region of 1.47 Mb around the mating-type locus. We detected three evolutionary strata, indicating a stepwise extension of recombination suppression. The three strata displayed no rearrangement or transposable element accumulation but gene losses and gene disruptions were present, and precisely at the strata margins. Our findings indicate a convergent evolution of self-fertile dikaryotic sexual spores across multiple ascomycete fungi. The particular pattern of meiotic segregation at the mating-type locus was associated with recombination suppression around this locus, that had extended stepwise. This association between pseudo-homothallism and recombination suppression across lineages and the presence of gene disruption at the strata limits are consistent with a recently proposed mechanism of sheltering deleterious alleles to explain stepwise recombination suppression.
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Affiliation(s)
- Nina Vittorelli
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
- Département de Biologie, École Normale Supérieure, PSL Université Paris, Paris, France
| | | | - Alodie Snirc
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
| | - Emilie Levert
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
| | - Valérie Gautier
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
| | - Christophe Lalanne
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
| | - Elsa De Filippo
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
| | - Pierre Gladieux
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Sonia Guillou
- PHIM Plant Health Institute, Univ Montpellier, INRAE, CIRAD, Institut Agro, IRD, Montpellier, France
| | - Yu Zhang
- U.S. Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Sravanthi Tejomurthula
- U.S. Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Igor V. Grigoriev
- U.S. Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Robert Debuchy
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Philippe Silar
- Laboratoire Interdisciplinaire des Energies de Demain, Université Paris Cité, Paris, France
| | - Tatiana Giraud
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
| | - Fanny E. Hartmann
- Ecologie Systematique et Evolution, CNRS, Université Paris-Saclay, AgroParisTech, Gif-sur-Yvette, France
- * E-mail:
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4
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Meunier C, Darolti I, Reimegård J, Mank JE, Johannesson H. Nuclear-specific gene expression in heterokaryons of the filamentous ascomycete Neurospora tetrasperma. Proc Biol Sci 2022; 289:20220971. [PMID: 35946150 PMCID: PMC9363985 DOI: 10.1098/rspb.2022.0971] [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] [Indexed: 12/14/2022] Open
Abstract
Heterokaryosis is a system in which genetically distinct nuclei coexist within the same cytoplasm. While heterokaryosis dominates the life cycle of many fungal species, the transcriptomic changes associated with the transition from homokaryosis to heterokaryosis is not well understood. Here, we analyse gene expression profiles of homokaryons and heterokaryons from three phylogenetically and reproductively isolated lineages of the filamentous ascomycete Neurospora tetrasperma. We show that heterokaryons are transcriptionally distinct from homokaryons in the sexual stage of development, but not in the vegetative stage, suggesting that the phenotypic switch to fertility in heterokaryons is associated with major changes in gene expression. Heterokaryon expression is predominantly defined by additive effects of its two nuclear components. Furthermore, allele-specific expression analysis of heterokaryons with varying nuclear ratios show patterns of expression ratios strongly dependent on nuclear ratios in the vegetative stage. By contrast, in the sexual stage, strong deviations of expression ratios indicate a co-regulation of nuclear gene expression in all three lineages. Taken together, our results show two levels of expression control: additive effects suggest a nuclear level of expression, whereas co-regulation of gene expression indicate a heterokaryon level of control.
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Affiliation(s)
- Cécile Meunier
- Department ECOBIO, UMR CNRS 6553, Université Rennes 1, Rennes, France
| | - Iulia Darolti
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
| | - Johan Reimegård
- Department of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Judith E. Mank
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada,Centre for Ecology and Conservation, University of Exeter, Penryn Campus, UK
| | - Hanna Johannesson
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden,The Royal Swedish Academy of Sciences and Department of Ecology, Environment and Plant Sciences, Stockholm University, SE-106 91 Stockholm, Sweden
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5
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Lakovic M, Rillig MC. A Nuclei-Based Conceptual Model of (Eco)evolutionary Dynamics in Fungal Heterokaryons. Front Microbiol 2022; 13:914040. [PMID: 35711750 PMCID: PMC9194903 DOI: 10.3389/fmicb.2022.914040] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/10/2022] [Indexed: 11/21/2022] Open
Abstract
Filamentous fungi are characterised by specific features, such as multinuclearity, coexistence of genetically different nuclei and nuclear movement across the mycelial network. These attributes make them an interesting, yet rather underappreciated, system for studying (eco)evolutionary dynamics. This is especially noticeable among theoretical studies, where rather few consider nuclei and their role in (eco)evolutionary dynamics. To encourage such theoretical approaches, we here provide an overview of existing research on nuclear genotype heterogeneity (NGH) and its sources, such as mutations and vegetative non-self-fusion. We then discuss the resulting intra-mycelial nuclear dynamics and the potential consequences for fitness and adaptation. Finally, we formulate a nuclei-based conceptual framework, which considers three levels of selection: a single nucleus, a subpopulation of nuclei and the mycelium. We compare this framework to other concepts, for example those that consider only the mycelium as the level of selection, and outline the benefits of our approach for studying (eco)evolutionary dynamics. Our concept should serve as a baseline for modelling approaches, such as individual-based simulations, which will contribute greatly to our understanding of multilevel selection and (eco)evolutionary dynamics in filamentous fungi.
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Affiliation(s)
- Milica Lakovic
- Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research, Berlin, Germany
| | - Matthias C Rillig
- Institut für Biologie, Freie Universität Berlin, Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research, Berlin, Germany
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6
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Auxier B, Czárán TL, Aanen DK. Modelling the consequences of the dikaryotic life cycle of mushroom-forming fungi on genomic conflict. eLife 2022; 11:75917. [PMID: 35441591 PMCID: PMC9084891 DOI: 10.7554/elife.75917] [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: 11/30/2021] [Accepted: 04/14/2022] [Indexed: 11/21/2022] Open
Abstract
Generally, sexual organisms contain two haploid genomes, one from each parent, united in a single diploid nucleus of the zygote which links their fate during growth. A fascinating exception to this is Basidiomycete fungi, where the two haploid genomes remain separate in a dikaryon, retaining the option to fertilize subsequent monokaryons encountered. How the ensuing nuclear competition influences the balance of selection within and between individuals is largely unexplored. We test the consequences of the dikaryotic life cycle for mating success and mycelium-level fitness components. We assume a trade-off between mating fitness at the level of the haploid nucleus and fitness of the fungal mycelium. We show that the maintenance of fertilization potential by dikaryons leads to a higher proportion of fertilized monokaryons, but that the ensuing intradikaryon selection for increased nuclear mating fitness leads to reduced mycelium fitness relative to a diploid life cycle. However, this fitness reduction is lower compared to a hypothetical life cycle where dikaryons can also exchange nuclei. Prohibition of fusion between dikaryons therefore reduces the level of nuclear parasitism. The number of loci influencing fitness is an important determinant of the degree to which average mycelium-level fitness is reduced. The results of this study crucially hinge upon a trade-off between nucleus and mycelium-level fitness. We discuss the evidence for this assumption and the implications of an alternative that there is a positive relationship between nucleus and mycelium-level fitness.
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Affiliation(s)
- Benjamin Auxier
- Laboratory of Genetics, Wageningen University, Wageningen, Netherlands
| | | | - Duur K Aanen
- Laboratory of Genetics, Wageningen University, Wageningen, Netherlands
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7
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Cornell C, Kokkoris V, Turcu B, Dettman J, Stefani F, Corradi N. The arbuscular mycorrhizal fungus Rhizophagus irregularis harmonizes nuclear dynamics in the presence of distinct abiotic factors. Fungal Genet Biol 2021; 158:103639. [PMID: 34800644 DOI: 10.1016/j.fgb.2021.103639] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 11/11/2021] [Accepted: 11/12/2021] [Indexed: 12/14/2022]
Abstract
Arbuscular mycorrhizal fungi (AMF) are widespread obligate root symbionts that assist plants in obtaining nutrients and protection against environmental stresses. In the model species Rhizophagus irregularis, heterokaryotic strains (AMF dikaryons) carry thousands of nuclei originating from two parental strains whose frequency varies depending on strains and host identity. Here, using digital droplet PCR, we demonstrate that surrounding abiotic factors (temperature, phosphorus, and pH) also change the nuclear dynamics of such strains in root organ cultures. Furthermore, when spatially separated portions of the AMF mycelium grow under different abiotic conditions, all the produced spores carry highly similar nuclear ratios. Overall, these findings demonstrate that abiotic stressors impact the nuclear organization of a widespread group of multinucleate plant symbionts, and reveal remarkable mechanisms of nuclear ratio harmonization across the mycelium in these prominent symbionts.
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Affiliation(s)
- Calvin Cornell
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Vasilis Kokkoris
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada; Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, ON K1A 0C6, Canada
| | - Bianca Turcu
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Jeremy Dettman
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, ON K1A 0C6, Canada
| | - Franck Stefani
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre, ON K1A 0C6, Canada
| | - Nicolas Corradi
- Department of Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada.
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8
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Hartmann FE, Duhamel M, Carpentier F, Hood ME, Foulongne‐Oriol M, Silar P, Malagnac F, Grognet P, Giraud T. Recombination suppression and evolutionary strata around mating-type loci in fungi: documenting patterns and understanding evolutionary and mechanistic causes. THE NEW PHYTOLOGIST 2021; 229:2470-2491. [PMID: 33113229 PMCID: PMC7898863 DOI: 10.1111/nph.17039] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/03/2020] [Indexed: 05/08/2023]
Abstract
Genomic regions determining sexual compatibility often display recombination suppression, as occurs in sex chromosomes, plant self-incompatibility loci and fungal mating-type loci. Regions lacking recombination can extend beyond the genes determining sexes or mating types, by several successive steps of recombination suppression. Here we review the evidence for recombination suppression around mating-type loci in fungi, sometimes encompassing vast regions of the mating-type chromosomes. The suppression of recombination at mating-type loci in fungi has long been recognized and maintains the multiallelic combinations required for correct compatibility determination. We review more recent evidence for expansions of recombination suppression beyond mating-type genes in fungi ('evolutionary strata'), which have been little studied and may be more pervasive than commonly thought. We discuss testable hypotheses for the ultimate (evolutionary) and proximate (mechanistic) causes for such expansions of recombination suppression, including (1) antagonistic selection, (2) association of additional functions to mating-type, such as uniparental mitochondria inheritance, (3) accumulation in the margin of nonrecombining regions of various factors, including deleterious mutations or transposable elements resulting from relaxed selection, or neutral rearrangements resulting from genetic drift. The study of recombination suppression in fungi could thus contribute to our understanding of recombination suppression expansion across a broader range of organisms.
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Affiliation(s)
- Fanny E. Hartmann
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
| | - Marine Duhamel
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
- Ruhr‐Universität Bochum, Evolution of Plants and Fungi ‐ Gebäude ND 03/174Universitätsstraße150, 44801 BochumGermany
| | - Fantin Carpentier
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
| | - Michael E. Hood
- Biology Department, Science CentreAmherst CollegeAmherstMA01002USA
| | | | - Philippe Silar
- Lab Interdisciplinaire Energies DemainUniv Paris DiderotSorbonne Paris CiteParis 13F‐75205France
| | - Fabienne Malagnac
- Institute for Integrative Biology of the Cell (I2BC)Université Paris‐SaclayCEACNRSGif‐sur‐Yvette91198France
| | - Pierre Grognet
- Institute for Integrative Biology of the Cell (I2BC)Université Paris‐SaclayCEACNRSGif‐sur‐Yvette91198France
| | - Tatiana Giraud
- Ecologie Systematique EvolutionBatiment 360Université Paris‐SaclayCNRSAgroParisTechOrsay91400France
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9
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Kronholm I, Ormsby T, McNaught KJ, Selker EU, Ketola T. Marked Neurospora crassa Strains for Competition Experiments and Bayesian Methods for Fitness Estimates. G3 (BETHESDA, MD.) 2020; 10:1261-1270. [PMID: 32001556 PMCID: PMC7144071 DOI: 10.1534/g3.119.400632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 01/27/2020] [Indexed: 01/17/2023]
Abstract
The filamentous fungus Neurospora crassa, a model microbial eukaryote, has a life cycle with many features that make it suitable for studying experimental evolution. However, it has lacked a general tool for estimating relative fitness of different strains in competition experiments. To remedy this need, we constructed N. crassa strains that contain a modified csr-1 locus and developed an assay for detecting the proportion of the marked strain using a post PCR high resolution melting assay. DNA extraction from spore samples can be performed on 96-well plates, followed by a PCR step, which allows many samples to be processed with ease. Furthermore, we suggest a Bayesian approach for estimating relative fitness from competition experiments that takes into account the uncertainty in measured strain proportions. We show that there is a fitness effect of the mating type locus, as mating type mat a has a higher competitive fitness than mat A The csr-1* marker also has a small fitness effect, but is still a suitable marker for competition experiments. As a proof of concept, we estimate the fitness effect of the qde-2 mutation, a gene in the RNA interference pathway, and show that its competitive fitness is lower than what would be expected from its mycelial growth rate alone.
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Affiliation(s)
- Ilkka Kronholm
- Department of Biological and Environmental Sciences, University of Jyväskylä, FI-40014 Jyväskylä, Finland
| | | | | | | | - Tarmo Ketola
- Department of Biological and Environmental Sciences, University of Jyväskylä, FI-40014 Jyväskylä, Finland
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10
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Scott TW, Kiers ET, Cooper GA, dos Santos M, West SA. Evolutionary maintenance of genomic diversity within arbuscular mycorrhizal fungi. Ecol Evol 2019; 9:2425-2435. [PMID: 30891190 PMCID: PMC6405528 DOI: 10.1002/ece3.4834] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/23/2018] [Accepted: 11/26/2018] [Indexed: 01/12/2023] Open
Abstract
Most organisms are built from a single genome. In striking contrast, arbuscular mycorrhizal fungi appear to maintain genomic variation within an individual fungal network. Arbuscular mycorrhizal fungi dwell in the soil, form mutualistic networks with plants, and bear multiple, potentially genetically diverse nuclei within a network. We explore, from a theoretical perspective, why such genetic diversity might be maintained within individuals. We consider selection acting within and between individual fungal networks. We show that genetic diversity could provide a benefit at the level of the individual, by improving growth in variable environments, and that this can stabilize genetic diversity even in the presence of nuclear conflict. Arbuscular mycorrhizal fungi complicate our understanding of organismality, but our findings offer a way of understanding such biological anomalies.
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Affiliation(s)
| | - E. Toby Kiers
- Institute of Ecological Sciences, Faculty of Earth and Life SciencesVrije UniversiteitAmsterdamThe Netherlands
| | | | - Miguel dos Santos
- Department of ZoologyUniversity of OxfordOxfordUK
- Department of Social Psychology and Social Neuroscience, Institute of PsychologyUniversity of BernBernSwitzerland
| | - Stuart A. West
- Department of ZoologyUniversity of OxfordOxfordUK
- Magdalen CollegeOxfordUK
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