Genetic evidence for recombination in Candida albicans based on haplotype analysis.

The possibility of sexual reproduction in the human pathogenic fungus Candida albicans is a question of great interest in medical mycology. Not only is it a fundamental biological issue, but it is also a potential mechanism for contributing to the phenotypic plasticity (and hence the virulence) of the organism. Molecular genotyping methods such as multi-locus sequence typing (MLST) are generating data that can shed light on this question. In the present study we have used MLST information to generate haplotypes that identify many different homologues of a chromosome within a collection of strains. Particular combinations of these haplotypes provide evidence for chromosomal segregation and intra-chromosome recombination. All of our observations of haplotype diversity could also be explained by other mechanisms, such as gene conversion or mitotic recombination, and the resolution of these issues will require a denser map of accurately localised markers. A common event observed in strain evolution is loss of heterozygosity at a particular marker. Our results contribute to the emerging picture of C. albicans as an organism whose primary means of reproduction is clonal, but with a small but important contribution from sexual reproduction, occurring in nature but not under commonly used laboratory conditions.