Mapping natural bypass suppressors of essential genes in Saccharomyces cerevisiae

Mutants of the budding yeast strain S288C, each deleted for an essential gene in the genome and instead carrying it on a plasmid, were crossed to 19 wild yeast isolates. Haploid segregant progeny carrying the deletion allele were selected in both the presence and absence of the plasmid. If viable progeny lacking the plasmid (and thus lacking the essential gene) were obtained, segregant pools were sequenced to identify regions in the wild genome that carried a variant that could suppress the lethality of the essential gene deletion mutant.