Unlocking the functional potential of polyploid yeasts

Breeding and domestication have generated widely exploited crops, animals and microbes. However, many Saccharomyces cerevisiae industrial strains have complex polyploid genomes and are sterile, preventing genetic improvement strategies based on breeding. Here, we present a strain improvement approach based on the budding yeasts' property to promote genetic recombination when meiosis is interrupted and cells return-to-mitotic-growth (RTG). We demonstrate that two unrelated sterile industrial strains with complex triploid and tetraploid genomes are RTG-competent and develop a visual screening for easy and high-throughput identification of recombined RTG clones based on colony phenotypes. Sequencing of the evolved clones reveal unprecedented levels of RTG-induced genome-wide recombination. We generate and extensively phenotype a RTG library and identify clones with superior biotechnological traits. Thus, we propose the RTG-framework as a fully non-GMO workflow to rapidly improve industrial yeasts that can be easily brought to the market. Domesticated industrial yeast strains are sterile, which hampers to breed strains with novel properties. Here, the authors employ the genetics paradigm return-to-growth to induce genome wide recombination in two sterile polyploid industrial yeasts and identify clones with superior biotechnological traits.

Automated summary

The authors propose a non-GMO workflow to improve industrial yeast strains by inducing genome-wide recombination using the return-to-growth approach. This approach allows for the identification of clones with superior biotechnological traits, overcoming the sterility of domesticated industrial yeast strains.