Fungal model organisms: phylogenetics of Saccharomyces, Aspergillus

Abstract.—Fungal model organisms are widely used because, in general, they are less expensive to maintain under laboratory conditions than are members of the two other higher eukaryotic kingdoms, the animals and plants. Ascomycetes have been the most popular fungi with genet-icists and molecular developmental biologists, beginning with Neurospora and recently with Saccharomyces and Aspergillus. Fungal molecular evolution studies of 18S ribosomal RNA and DNA have recently produced a robust phylogeny of ascomycetes, and molecular genetic studies of fungal development are unraveling the pathway of spore production. We wondered if sys-tematists and developmental biologists were taking advantage of each other's knowledge. The majority of molecular biology studies of fungi still use model species, and only a few studies of nonmodel organisms have used phylogenetic information in their design. Likewise, studies of asexual spore development and mating type genes have emphasized model fungi, but studies of mating type in nonmodel fungi are beginning to yield results. We predict that truly com-parative molecular biological studies of fungal development will be available shortly because the prerequisites have been completed, e.g., a well-supported phylogeny, sophisticated molecular techniques, including complementation by transformation and gene disruption, and morpho-logical developmental pathways that are simpler than those of plants or animals. [Fungus; phylogeny; development; genetics; molecular evolution; Neurospora; Saccharomyces; Aspergillus; Schizosaccharomyces; yeast; fission yeast.] Now that nucleic acid molecular biology has thoroughly infiltrated both phyloge-netic studies of fungal evolution (reviewed by Bruns et al., 1991) and experimental studies of fungal genetics and develop