Genetic Dissection of Ethanol Tolerance in the Budding Yeast Saccharomyces cerevisiae

摘要

Uncovering genetic control of variation in ethanol tolerance in natural populations of yeast Saccharomycesncerevisiae is essential for understanding the evolution of fermentation, the dominant lifestyle of the species,nand for improving efficiency of selection for strains with high ethanol tolerance, a character of greatneconomic value for the brewing and biofuel industries. To date, as many as 251 genes have been predicted tonbe involved in influencing this character. Candidacy of these genes was determined from a tested phenotypicneffect following gene knockout, from an induced change in gene function under an ethanol stress condition,nor by mutagenesis. This article represents the first genomics approach for dissecting genetic variation innethanol tolerance between two yeast strains with a highly divergent trait phenotype. We developed a simplenbut reliable experimental protocol for scoring the phenotype and a set of STR/SNP markers evenly coveringnthe whole genome.We created a mapping population comprising 319 segregants from crossing the parentalnstrains. On the basis of the data sets, we find that the tolerance trait has a high heritability and that additivengenetic variance dominates genetic variation of the trait. Segregation at five QTL detected has explainednu000250% of phenotypic variation; in particular, the major QTL mapped on yeast chromosome 9 has accountednfor a quarter of the phenotypic variation. We integrated the QTL analysis with the predicted candidacy ofnethanol resistance genes and found that only a few of these candidates fall in the QTL regions.