The Ashbya gossypii Genome as a Tool for Mapping the Ancient Saccharomyces cerevisiae Genome

Abstract

We have sequenced and annotated the genome of the filamentous ascomycete Ashbya gossypii . With a size of only 9.2 megabases, encoding 4718 protein-coding genes, it is the smallest genome of a free-living eukaryote yet characterized. More than 90% of A. gossypii genes show both homology and a particular pattern of synteny with Saccharomyces cerevisiae . Analysis of this pattern revealed 300 inversions and translocations that have occurred since divergence of these two species. It also provided compelling evidence that the evolution of S. cerevisiae included a whole genome duplication orfusion of two related species and showed, through inferred ancient gene orders, which of the duplicated genes lost one copy and which retained both copies.