We demonstrate that both species have the potential for sexual reproduction, and although our mating studies suggest that sexual reproduction is infrequent, strains of both mating types are equally abundant in both species.
Among the Binding SPLN deletion strains, 8% (7/88) are significantly long-lived in both mating types and 15.9% (14/88) are significantly long-lived when data from both mating types are pooled, compared to only 2.7% (15/564) and 4.3% (24) in each category for the randomly selected set of 564 deletion strains (Table 1).
This information could explain the apparent asexuality of the populations we sampled (for example, only one mating type may be present), or suggest that asexual reproduction is dominant at broader geographic scales if both mating types are co-occurring but no evidence of recombination is observed.
Conversely, in homothallic fungi, both mating types are encoded by the same genome, and an individual can mate with any other individual, including itself [ 15].
In particular, although mating has never been reported in C. glabrata, the two additional MAT cassettes, HMRa and HMLalpha, and the HO gene are present in its genome, and haploid isolates of both mating types are found.
Interestingly, MAT1-1-3, the HMG-box domain protein of the MAT1-1 isionlyph, is only expressed at low levels when both mating types are grown in co-culture, suggesting that it could be involved in downstream transcriptional activation of sexual reproduction.
Isolates of both mating types were found on all continents for both species despite the rarely observed occurrence of sexual reproduction of T. acuformis.
Considering the ploidy of these strains, EC1118 has been reported to be a diploid (Novo et al. 2009) and according to a PCR test performed in our lab, Mab2C would be at least a diploid since both mating types were present.
Both mating types were retained (FY5216: h + or FY5217: h −).
Both mating types were present in strains isolated in Russia (six strains), Argentina (five strains) and Japan (two strains).
