<i>Saccharomyces cerevisiae</i> S288C Has a Mutation in <i>FL08</i>, a Gene Required for Filamentous Growth

TLDR

Baker's yeast can switch between yeast and pseudohyphal forms under nitrogen starvation, but many laboratory strains lack this dimorphic ability. The S288C strain carries a nonsense mutation in FL08 that blocks pseudohyphal, invasive, and flocculation growth, suggesting the mutation arose during laboratory domestication.

Abstract

Abstract Diploid strains of baker's yeast Saccharomyces cermisiae can grow in a cellular yeast form or in filaments called pseudohyphae. This dimorphic transition from yeast to pseudohyphae is induced by starvation for nitrogen. Not all laboratory strains are capable of this dimorphic switch; many grow only in the yeast form and fail to form pseudohyphae when starved for nitrogen. Analysis of the standard laboratory strain S288C shows that this defect in dimorphism results from a nonsense mutation in the FL08 gene. This defect in FL08 blocks pseudohyphal growth in diploids, haploid invasive growth, and flocculation. Since feral strains of S. cerevisiae are dimorphic and have a functional FL08 gene, we suggest that the fl08 mutation was selected during laboratory cultivation.