Epistasis and cryptic QTL identified using modified bulk segregant analysis of copper resistance in budding yeast.

The contributions of genetic interactions to natural trait variation are challenging to estimate experimentally, as current approaches for detecting epistasis are often underpowered. Powerful mapping approaches such as bulk segregant analysis, wherein individuals with extreme phenotypes are pooled for genotyping, obscure epistasis by averaging over genotype combinations. To accurately characterize and quantify epistasis underlying natural trait variation, we have engineered strains of the budding yeast to enable crosses where one parent's chromosome is fixed while the rest of the chromosomes segregate.