Investigating Natural Genetic Variation in Environmental Stress Survival and Induced Stress Resistance in Budding Yeast

Abstract

Heat shock and salt shock resistance are two well-studied phenotypes but we don't have a complete molecular level understanding of how these shocks effect the cell. In addition yeast, along with many other species, will increase in resistance to similar or dissimilar stresses following a mild stress. To learn more about natural variation present in these traits I mapped QTL in the yeast Saccharomyces cerevisiae for uninduced and induced stress resistance. To do this I utilized the X-QTL method, a selection based pooled genotyping approach to mapping quantitative traits. I identified two phenotypically divergent strains to use as the parents for X-QTL, a wine strain and an oak strain. X-QTL was performed on this cross using heat shock, salt shock, and each shock preceded by a mild heat or mild salt shock. QTL were successfully mapped for five of the six conditions and 65 different QTL were identified between those conditions. I found that survival of severe heat was highly complex, with 46 different QTL identified. A smaller number of QTL were identified for induced resistance but with a single exception they were QTL that were also present in the uninduced resistance. The lack of induction specific QTL suggests that the stress resistance regulation is highly conserved.