Identification of CDC25-P1306L, a novel mutant allele of CDC25, conferring tolerance to multiple stresses associated with food production on Saccharomyces cerevisiae

Mutations conferring tolerance to diverse stresses (i.e. multistress tolerance) on budding yeast Saccharomyces cerevisiae are useful for industrial yeast strains such as baker’s and wine yeast. However, little is known about the mutations conferring multistress tolerance. Previously, we developed a simple method for isolating multistress-tolerant semidominant mutants of S. cerevisiae by one-step selection under lethal hydrogen peroxide stress, which we named the LCH method. In this study, we applied a combination of genetics and next-generation sequencing (NGS) technology to identify the causal mutation for multistress tolerance of the mutant isolated using the LCH method. The haploid mutant strain was crossed with the wild-type strain and the resulting diploids were sporulated. The 20 haploid progeny strains showing multistress tolerance were mixed and subjected to DNA extraction for NGS. CDC25-P1306L, a novel mutant allele of CDC25 encoding a Ras guanine nucleotide exchange factor, was detected 86 times; however, a wild-type CDC25 allele was not detected in the NGS data from the mixture of the multistress-tolerant progeny strains, suggesting that all of the progeny strains showing multistress tolerance have a CDC25-P1306L allele instead of a wild-type CDC25 allele. Substitution of CDC25 in the wild-type strain with CDC25-P1306L rendered the strain tolerant to ethanol, heat shock, freeze-thaw, chronological aging and high concentrations of glucose. These results indicate that CDC25-P1306L is a multistress-tolerant mutation and is promising for breeding multistress-tolerant S. cerevisiae strains for food production