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The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited

BACKGROUND: We investigate the scope for selection at the level of nuclei within fungal individuals (mycelia) of the mutualistic Termitomyces cultivated by fungus-growing termites. Whereas in most basidiomycete fungi the number and kind of nuclei is strictly regulated to be two per cell, in Termitom...

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Autores principales: Nobre, Tania, Koopmanschap, Bertha, Baars, Johan JP, Sonnenberg, Anton SM, Aanen, Duur K
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085734/
https://www.ncbi.nlm.nih.gov/pubmed/24902958
http://dx.doi.org/10.1186/1471-2148-14-121
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author Nobre, Tania
Koopmanschap, Bertha
Baars, Johan JP
Sonnenberg, Anton SM
Aanen, Duur K
author_facet Nobre, Tania
Koopmanschap, Bertha
Baars, Johan JP
Sonnenberg, Anton SM
Aanen, Duur K
author_sort Nobre, Tania
collection PubMed
description BACKGROUND: We investigate the scope for selection at the level of nuclei within fungal individuals (mycelia) of the mutualistic Termitomyces cultivated by fungus-growing termites. Whereas in most basidiomycete fungi the number and kind of nuclei is strictly regulated to be two per cell, in Termitomyces mycelia the number of nuclei per cell is highly variable. We hypothesised that natural selection on these fungi not only occurs between mycelia, but also at the level of nuclei within the mycelium. We test this hypothesis using in vitro tests with five nuclear haplotypes of a Termitomyces species. RESULTS: First, we studied the transition from a mixture of five homokaryons (mycelia with identical nuclei) each with a different nuclear haplotype to heterokaryons (mycelia with genetically different nuclei). In vitro cultivation of this mixture for multiple asexual transfers led to the formation of multiple heterokaryotic mycelia, and a reduction of mycelial diversity over time. All heterokaryotic mycelia contained exactly two types of nucleus. The success of a heterokaryon during in vitro cultivation was mainly determined by spore production and to a lesser extent by mycelial growth rate. Second, heterokaryons invariably produced more spores than homokaryons implying that homokaryons will be outcompeted. Third, no homokaryotic ‘escapes’ from a heterokaryon via the formation of homokaryotic spores were found, despite extensive spore genotyping. Fourth, in contrast to most studied basidiomycete fungi, in Termitomyces sp. no nuclear migration occurs during mating, limiting the scope for nuclear competition within the mycelium. CONCLUSIONS: Our experiments demonstrate that in this species of Termitomyces the scope for selection at the level of the nucleus within an established mycelium is limited. Although ‘mate choice’ of a particular nuclear haplotype is possible during mating, we infer that selection primarily occurs between mycelia with two types of nucleus (heterokaryons).
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spelling pubmed-40857342014-07-24 The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited Nobre, Tania Koopmanschap, Bertha Baars, Johan JP Sonnenberg, Anton SM Aanen, Duur K BMC Evol Biol Research Article BACKGROUND: We investigate the scope for selection at the level of nuclei within fungal individuals (mycelia) of the mutualistic Termitomyces cultivated by fungus-growing termites. Whereas in most basidiomycete fungi the number and kind of nuclei is strictly regulated to be two per cell, in Termitomyces mycelia the number of nuclei per cell is highly variable. We hypothesised that natural selection on these fungi not only occurs between mycelia, but also at the level of nuclei within the mycelium. We test this hypothesis using in vitro tests with five nuclear haplotypes of a Termitomyces species. RESULTS: First, we studied the transition from a mixture of five homokaryons (mycelia with identical nuclei) each with a different nuclear haplotype to heterokaryons (mycelia with genetically different nuclei). In vitro cultivation of this mixture for multiple asexual transfers led to the formation of multiple heterokaryotic mycelia, and a reduction of mycelial diversity over time. All heterokaryotic mycelia contained exactly two types of nucleus. The success of a heterokaryon during in vitro cultivation was mainly determined by spore production and to a lesser extent by mycelial growth rate. Second, heterokaryons invariably produced more spores than homokaryons implying that homokaryons will be outcompeted. Third, no homokaryotic ‘escapes’ from a heterokaryon via the formation of homokaryotic spores were found, despite extensive spore genotyping. Fourth, in contrast to most studied basidiomycete fungi, in Termitomyces sp. no nuclear migration occurs during mating, limiting the scope for nuclear competition within the mycelium. CONCLUSIONS: Our experiments demonstrate that in this species of Termitomyces the scope for selection at the level of the nucleus within an established mycelium is limited. Although ‘mate choice’ of a particular nuclear haplotype is possible during mating, we infer that selection primarily occurs between mycelia with two types of nucleus (heterokaryons). BioMed Central 2014-06-05 /pmc/articles/PMC4085734/ /pubmed/24902958 http://dx.doi.org/10.1186/1471-2148-14-121 Text en Copyright © 2014 Nobre et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/4.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Nobre, Tania
Koopmanschap, Bertha
Baars, Johan JP
Sonnenberg, Anton SM
Aanen, Duur K
The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title_full The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title_fullStr The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title_full_unstemmed The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title_short The scope for nuclear selection within Termitomyces fungi associated with fungus-growing termites is limited
title_sort scope for nuclear selection within termitomyces fungi associated with fungus-growing termites is limited
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4085734/
https://www.ncbi.nlm.nih.gov/pubmed/24902958
http://dx.doi.org/10.1186/1471-2148-14-121
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