Oral Presentation Society for Molecular Biology and Evolution Conference 2016

Genetics and evolution of early branching Saccharomyces. (#134)

EmilyClare P Baker 1 , William G Alexander 1 , David Peris 1 , Quinn K Langdon 1 , Chris Todd Hittinger 1
  1. Laboratory of Genetics, University of Wisconsin - Madison, Madison, WI, United States

Yeast of the Saccharomyces genus, including the classical model Saccharomyces cerevisiae and less well known members of the genus, are important for many fermentative processes. Among these species are two early branching members of the genus, the sister species Saccharomyces uvarum (Saccharomyces bayanus var. uvarum) and Saccharomyces eubayanus. Important contributors to the brewing industry, they are strongly allied with different beverages, almost always with a S. cerevisiae genetic component. S. uvarum is associated with wines and ciders, while S. eubayanus is the non-cerevisiae parent of lager yeasts. Despite their differences in brewing associations and ~6.5% nucleotide divergence these sister species are physiologically very similar and it is not immediately clear why they show different brewing associations. Using genome sequencing and traditional genetic approaches we aim to understand what separates these species from each other and what contributes to their importance in the brewing industry. Comparing the S. eubayanus genome in lager yeasts to its parent genome we found that lager yeasts’ S. eubayanus genome has experienced relaxation of selective pressure. Analyzing the S. eubayanus parent genome we identified fourteen genes that likely contribute to maltose utilization (essential for effective brewing). We are further exploring the function of these genes using gene-knockout and replacement studies. Moving from how and why a single species adapted to brewing to determining how both species have diverged genetically and phenotypically we are directly comparing their genome sequences and analyzing hybrids. Initial analyses indicate possible differences in RNA metabolism potentially leading to new insights into the role of RNA metabolism throughout Saccharomyces. As early branching members of Saccharomyces studying S. eubayanus and S. uvarum can not only provide insight into the genetic and physical characteristics of these economically important yeast, but further our understanding of the evolution of this scientifically and industrially important genus.