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Sexual Crosses with the Mucoromycete Phycomyces blakesleeanus
Published on: June 6, 2025
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Genomic Evidence for a-α Heterothallic and α-α Unisexual Mating and Recombination in an Environmental Cryptococcus
Megan Hitchcock1, Veronica Thorn1, Himeshi Samarasinghe1
1Department of Biology, McMaster University, Hamilton, ON L8S 4K1, Canada.
Biorxiv : the Preprint Server for Biology
|September 2, 2025
Summary
This study provides robust evidence for both a-α and α-α sexual reproduction in environmental Cryptococcus deneoformans populations. Analysis of whole-genome sequences revealed recombination signatures, confirming natural sexual reproduction in this fungal pathogen.
Area of Science:
- Mycology
- Genetics
- Evolutionary Biology
Background:
- Cryptococcus deneoformans is a human fungal pathogen.
- Sexual reproduction in C. deneoformans is known in laboratory settings.
- The extent of sexual reproduction in natural populations is largely unexplored.
Purpose of the Study:
- To investigate the occurrence and extent of a-α and α-α sexual reproduction in environmental C. deneoformans populations.
- To analyze whole-genome sequences of environmental isolates to identify signatures of sexual reproduction.
- To compare findings from whole-genome SNP data with multilocus sequence typing.
Main Methods:
- Whole-genome sequencing of 24 environmental C. deneoformans strains from Saudi Arabia.
- Identification and analysis of single nucleotide polymorphisms (SNPs) in nuclear and mitochondrial genomes.
- Application of the four-gamete test to detect recombination signatures.
Main Results:
- Evidence of recombination was found in both nuclear and mitochondrial genomes across different subpopulations.
- The ST160 subpopulation showed nuclear genome recombination despite no mitogenome SNPs.
- Recombination frequency was correlated with SNP distance on chromosomes, indicating widespread genetic exchange.
Conclusions:
- Robust evidence supports both a-α and α-α sexual reproduction in environmental C. deneoformans populations.
- Sexual reproduction occurs in nature, contributing to genetic diversity in this fungal pathogen.
- Whole-genome SNP data offers a more comprehensive view of genetic diversity than multilocus sequence typing.
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