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Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating.
PLoS Pathog. 2009 Jan; 5(1):e1000283.PP

Abstract

The ubiquitous environmental human pathogen Cryptococcus neoformans is traditionally considered a haploid fungus with a bipolar mating system. In nature, the alpha mating type is overwhelmingly predominant over a. How genetic diversity is generated and maintained by this heterothallic fungus in a largely unisexual alpha population is unclear. Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions generating both diploid intermediates and haploid recombinant progeny. Same-sex mating (alpha-alpha) also occurs in nature as evidenced by the existence of natural diploid alphaADalpha hybrids that arose by fusion between two alpha cells of different serotypes (A and D). How significantly this novel sexual style contributes to genetic diversity of the Cryptococcus population was unknown. In this study, approximately 500 natural C. neoformans isolates were tested for ploidy and close to 8% were found to be diploid by fluorescence flow cytometry analysis. The majority of these diploids were serotype A isolates with two copies of the alpha MAT locus allele. Among those, several are intra-varietal allodiploid hybrids produced by fusion of two genetically distinct alpha cells through same-sex mating. The majority, however, are autodiploids that harbor two seemingly identical copies of the genome and arose via either endoreplication or clonal mating. The diploids identified were isolated from different geographic locations and varied genotypically and phenotypically, indicating independent non-clonal origins. The present study demonstrates that unisexual mating produces diploid isolates of C. neoformans in nature, giving rise to populations of hybrids and mixed ploidy. Our findings underscore the importance of same-sex mating in shaping the current population structure of this important human pathogenic fungus, with implications for mechanisms of selfing and inbreeding in other microbial pathogens.

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Authors+Show Affiliations

Lin X
Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America.
Patel S
No affiliation info available
Litvintseva AP
No affiliation info available
Floyd A
No affiliation info available
Mitchell TG
No affiliation info available
Heitman J
No affiliation info available

MeSH

Base SequenceComparative Genomic HybridizationCryptococcus neoformansDiploidyGenes, FungalGenes, Mating Type, FungalHaploidyMolecular Sequence DataPhenotypePhylogenyPolymorphism, GeneticSerotyping

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

19180236

Citation

Lin, Xiaorong, et al. "Diploids in the Cryptococcus Neoformans Serotype a Population Homozygous for the Alpha Mating Type Originate Via Unisexual Mating." PLoS Pathogens, vol. 5, no. 1, 2009, pp. e1000283.
Lin X, Patel S, Litvintseva AP, et al. Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating. PLoS Pathog. 2009;5(1):e1000283.
Lin, X., Patel, S., Litvintseva, A. P., Floyd, A., Mitchell, T. G., & Heitman, J. (2009). Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating. PLoS Pathogens, 5(1), e1000283. https://doi.org/10.1371/journal.ppat.1000283
Lin X, et al. Diploids in the Cryptococcus Neoformans Serotype a Population Homozygous for the Alpha Mating Type Originate Via Unisexual Mating. PLoS Pathog. 2009;5(1):e1000283. PubMed PMID: 19180236.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Diploids in the Cryptococcus neoformans serotype A population homozygous for the alpha mating type originate via unisexual mating. AU - Lin,Xiaorong, AU - Patel,Sweta, AU - Litvintseva,Anastasia P, AU - Floyd,Anna, AU - Mitchell,Thomas G, AU - Heitman,Joseph, Y1 - 2009/01/30/ PY - 2008/10/02/received PY - 2008/12/30/accepted PY - 2009/1/31/entrez PY - 2009/1/31/pubmed PY - 2009/4/18/medline SP - e1000283 EP - e1000283 JF - PLoS pathogens JO - PLoS Pathog VL - 5 IS - 1 N2 - The ubiquitous environmental human pathogen Cryptococcus neoformans is traditionally considered a haploid fungus with a bipolar mating system. In nature, the alpha mating type is overwhelmingly predominant over a. How genetic diversity is generated and maintained by this heterothallic fungus in a largely unisexual alpha population is unclear. Recently it was discovered that C. neoformans can undergo same-sex mating under laboratory conditions generating both diploid intermediates and haploid recombinant progeny. Same-sex mating (alpha-alpha) also occurs in nature as evidenced by the existence of natural diploid alphaADalpha hybrids that arose by fusion between two alpha cells of different serotypes (A and D). How significantly this novel sexual style contributes to genetic diversity of the Cryptococcus population was unknown. In this study, approximately 500 natural C. neoformans isolates were tested for ploidy and close to 8% were found to be diploid by fluorescence flow cytometry analysis. The majority of these diploids were serotype A isolates with two copies of the alpha MAT locus allele. Among those, several are intra-varietal allodiploid hybrids produced by fusion of two genetically distinct alpha cells through same-sex mating. The majority, however, are autodiploids that harbor two seemingly identical copies of the genome and arose via either endoreplication or clonal mating. The diploids identified were isolated from different geographic locations and varied genotypically and phenotypically, indicating independent non-clonal origins. The present study demonstrates that unisexual mating produces diploid isolates of C. neoformans in nature, giving rise to populations of hybrids and mixed ploidy. Our findings underscore the importance of same-sex mating in shaping the current population structure of this important human pathogenic fungus, with implications for mechanisms of selfing and inbreeding in other microbial pathogens. SN - 1553-7374 UR - https://www.unboundmedicine.com/medline/citation/19180236/Diploids_in_the_Cryptococcus_neoformans_serotype_A_population_homozygous_for_the_alpha_mating_type_originate_via_unisexual_mating_ L2 - https://dx.plos.org/10.1371/journal.ppat.1000283 DB - PRIME DP - Unbound Medicine ER -