Genetic analysis of red, adenine-requiring mutants of Candida albicans

Abstract

A number of investigators have described the isolation of red, adenine-requiring mutants of Candida albicans. Other fungi have been shown to give rise to two phenotypically similar, but genetically distinct, types of red, adenine-requiring mutants. This paper is the first indication that the red adenine mutants of C. albicans can similarly be resolved into two distinct classes. It is also believed to be the first report of such a resolution in an imperfect fungus. The resolution of these two classes was achieved by applying three distinct parasexual, analytical methods to this imperfect, naturally diploid yeast. The methods employed were complementation analysis of fused protoplasts and two methods of recombination analysis, induced mitotic crossing over in heterozygous revertants and induced mitotic crossing over in the heterozygous tetraploid products of protoplast fusion. The recombination methods depended on linkage analysis between the ade loci and two loci, met1 (methionine) and arg1 (arginine). The three analytical methods supported the same resolution. The results support the generally accepted view that C. albicans is diploid since they indicate disomic inheritance at the ade1, ade2, and met1 loci.