Evidence for recombination in Candida glabrata

Despite its clinical importance, little is known of the epidemiology and population structure of Candida glabrata. C. glabrata possesses a mating type system similar to that in Saccharomyces cerevisiae, however mating, meiosis and recombination have not been demonstrated. We performed multilocus sequence typing on a collection of 165 isolates to test for evidence of genetic recombination. A total of 3345 bp from six loci (FKS, LEU2, NMT1, TRP1, UGP1, and URA3) were sequenced for each isolate. The polymorphisms at these loci defined 34 sequence types. Significant evidence for a clonal population was revealed by the index of association and the number of phylogenetically compatible pairs of loci. However, 14 examples of phylogenetic incompatibility were also found. Thus we conclude that although C. glabrata has a predominantly clonal population structure, the multiple phylogenetic incompatibilities found strongly suggest that recombination occurred during the evolution of C. glabrata, and may infrequently still occur.