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Yeast Sex: Surprisingly High Rates of Outcrossing between Asci

BACKGROUND: Saccharomyces yeasts are an important model system in many areas of biological research. Very little is known about their ecology and evolution in the wild, but interest in this natural history is growing. Extensive work with lab strains in the last century uncovered the Saccharomyces li...

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Autores principales: Murphy, Helen A., Zeyl, Clifford W.
Formato: Texto
Lenguaje:English
Publicado: Public Library of Science 2010
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864747/
https://www.ncbi.nlm.nih.gov/pubmed/20463964
http://dx.doi.org/10.1371/journal.pone.0010461
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author Murphy, Helen A.
Zeyl, Clifford W.
author_facet Murphy, Helen A.
Zeyl, Clifford W.
author_sort Murphy, Helen A.
collection PubMed
description BACKGROUND: Saccharomyces yeasts are an important model system in many areas of biological research. Very little is known about their ecology and evolution in the wild, but interest in this natural history is growing. Extensive work with lab strains in the last century uncovered the Saccharomyces life cycle. When nutrient limited, a diploid yeast cell will form four haploid spores encased in a protective outer layer called the ascus. Confinement within the ascus is thought to enforce mating between products of the same meiotic division, minimizing outcrossing in this stage of the life cycle. METHODOLOGY/PRINCIPAL FINDINGS: Using a set of S. cerevisiae and S. paradoxus strains isolated from woodlands in North America, we set up trials in which pairs of asci were placed in contact with one another and allowed to germinate. We observed outcrossing in ∼40% of the trials, and multiple outcrossing events in trials with three asci in contact with each other. When entire populations of densely crowded asci germinated, ∼10–25% of the resulting colonies were outcrossed. There were differences between the species with S. cerevisiae having an increased tendency to outcross in mass mating conditions. CONCLUSIONS/SIGNIFICANCE: Our results highlight the potential for random mating between spores in natural strains, even in the presence of asci. If this type of mating does occur in nature and it is between close relatives, then a great deal of mating behavior may be undetectable from genome sequences.
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spelling pubmed-28647472010-05-12 Yeast Sex: Surprisingly High Rates of Outcrossing between Asci Murphy, Helen A. Zeyl, Clifford W. PLoS One Research Article BACKGROUND: Saccharomyces yeasts are an important model system in many areas of biological research. Very little is known about their ecology and evolution in the wild, but interest in this natural history is growing. Extensive work with lab strains in the last century uncovered the Saccharomyces life cycle. When nutrient limited, a diploid yeast cell will form four haploid spores encased in a protective outer layer called the ascus. Confinement within the ascus is thought to enforce mating between products of the same meiotic division, minimizing outcrossing in this stage of the life cycle. METHODOLOGY/PRINCIPAL FINDINGS: Using a set of S. cerevisiae and S. paradoxus strains isolated from woodlands in North America, we set up trials in which pairs of asci were placed in contact with one another and allowed to germinate. We observed outcrossing in ∼40% of the trials, and multiple outcrossing events in trials with three asci in contact with each other. When entire populations of densely crowded asci germinated, ∼10–25% of the resulting colonies were outcrossed. There were differences between the species with S. cerevisiae having an increased tendency to outcross in mass mating conditions. CONCLUSIONS/SIGNIFICANCE: Our results highlight the potential for random mating between spores in natural strains, even in the presence of asci. If this type of mating does occur in nature and it is between close relatives, then a great deal of mating behavior may be undetectable from genome sequences. Public Library of Science 2010-05-05 /pmc/articles/PMC2864747/ /pubmed/20463964 http://dx.doi.org/10.1371/journal.pone.0010461 Text en Murphy, Zeyl. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Murphy, Helen A.
Zeyl, Clifford W.
Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title_full Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title_fullStr Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title_full_unstemmed Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title_short Yeast Sex: Surprisingly High Rates of Outcrossing between Asci
title_sort yeast sex: surprisingly high rates of outcrossing between asci
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864747/
https://www.ncbi.nlm.nih.gov/pubmed/20463964
http://dx.doi.org/10.1371/journal.pone.0010461
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