The filamentous fungus A. gossypii and the related dimorphic fungus H. sinecauda have compact genomes of less than 10Mb. They have small intergenic regions frequently less than 100 bases in length, no transposable elements, and short telomeric and centromeric regions. We have recently completed the genomic sequence of H. sinecauda and deposited it in Genbank. A comparison of the genomes identifies approximately 30 genes whose presence or absence differs between these two species. While A. gossypii has over 5000 protein coding genes and genes producing an RNA product, comparison with H. sinecauda and other hemiascomycete species suggests the minimal gene set for a hemiascomycete to grow robustly on salts, ammonia, carbon source, water is around 4800 genes.
Combining this analysis with the recent analysis of 100 S. cerevisiae genes (Strope et al, 2015) suggests a set of core genes in S. cerevisiae, a set of additional genes beyond the core set, and a set of genes found in only a subset of S. cerevisiae genomes. In addition to variation in the gene set adding functionality to the genome, gene duplication, horizontal gene transfer, and introgression are all contributing to the genomic plasticity of S. cerevisiae..