Loss and fragmentation of chromosome 5 are major events linked to the adaptation of rad52-DeltaDelta strains of Candida albicans to sorbose

Candida albicans can adapt and grow on sorbose plates by losing one copy of Chr5. Since rad52 mutants of Saccharomyces cerevisiae lose chromosomes at a high rate, we have investigated the ability of C. albicans rad52 to adapt to sorbose. Carad52-DeltaDelta mutants generate Sou(+) strains earlier than wild-type but the final yield is lower, probably because they die at a higher rate in sorbose. As other strains of C. albicans, CAF2 and rad52-DeltaDelta derivatives generate Sou(+) strains by a loss of one copy of Chr5 about 75% of the time. In addition, rad52 strains were able to produce Sou(+) strains by a fragmentation/deletion event in one copy of Chr5, consisting of loss of a region adjacent to the right telomere. Finally, both CAF2 and rad52-DeltaDelta produced Sou(+) strains with two apparent full copies of Chr5, suggesting that additional genomic changes may also regulate adaptation to sorbose.