title: Ploidy influences the functional attributes of de novo lager yeast hybrids.
abstract: The genomes of hybrid organisms, such as lager yeast (Saccharomyces cerevisiae × Saccharomyces eubayanus), contain orthologous genes, the functionality and effect of which may differ depending on their origin and copy number. How the parental subgenomes in lager yeast contribute to important phenotypic traits such as fermentation performance, aroma production, and stress tolerance remains poorly understood. Here, three de novo lager yeast hybrids with different ploidy levels (allodiploid, allotriploid, and allotetraploid) were generated through hybridization techniques without genetic modification. The hybrids were characterized in fermentations of both high gravity wort (15 °P) and very high gravity wort (25 °P), which were monitored for aroma compound and sugar concentrations. The hybrid strains with higher DNA content performed better during fermentation and produced higher concentrations of flavor-active esters in both worts. The hybrid strains also outperformed both the parent strains. Genome sequencing revealed that several genes related to the formation of flavor-active esters (ATF1, ATF2¸ EHT1, EEB1, and BAT1) were present in higher copy numbers in the higher ploidy hybrid strains. A direct relationship between gene copy number and transcript level was also observed. The measured ester concentrations and transcript levels also suggest that the functionality of the S. cerevisiae- and S. eubayanus-derived gene products differs. The results contribute to our understanding of the complex molecular mechanisms that determine phenotypes in lager yeast hybrids and are expected to facilitate targeted strain development through interspecific hybridization.
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland. kristoffer.krogerus@aalto.fi.|Department of Biotechnology and Chemical Technology, Aalto University, School of Chemical Technology, Kemistintie 1, Aalto, P.O. Box 16100, FI-00076, Espoo, Finland. kristoffer.krogerus@aalto.fi.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Krogerus
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland.
authors.forename: Mikko
authors.initials: M
authors.lastname: Arvas
authors.affiliation: Institute for Research on Cancer and Ageing of Nice (IRCAN), CNRS UMR 7284, INSERM U1081, University of Nice Sophia Antipolis, 06107, Nice, France.
authors.forename: Matteo
authors.initials: M
authors.lastname: De Chiara
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland.|Department of Biotechnology and Chemical Technology, Aalto University, School of Chemical Technology, Kemistintie 1, Aalto, P.O. Box 16100, FI-00076, Espoo, Finland.
authors.forename: Frederico
authors.initials: F
authors.lastname: Magalhães
authors.affiliation: ValiRx Finland Oy, Kiviharjuntie 8, FI-90220, Oulu, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Mattinen
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Oja
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland.
authors.forename: Virve
authors.initials: V
authors.lastname: Vidgren
authors.affiliation: Institute for Research on Cancer and Ageing of Nice (IRCAN), CNRS UMR 7284, INSERM U1081, University of Nice Sophia Antipolis, 06107, Nice, France.
authors.forename: Jia-Xing
authors.initials: JX
authors.lastname: Yue
authors.affiliation: Institute for Research on Cancer and Ageing of Nice (IRCAN), CNRS UMR 7284, INSERM U1081, University of Nice Sophia Antipolis, 06107, Nice, France.
authors.forename: Gianni
authors.initials: G
authors.lastname: Liti
authors.affiliation: VTT Technical Research Centre of Finland, Tietotie 2, P.O. Box 1000, FI-02044, Espoo, Finland.
authors.forename: Brian
authors.initials: B
authors.lastname: Gibson
mesh_terms: D001515:Beer / Q000382:microbiology*; D002678:Chimera / Q000235:genetics* / Q000254:growth & development; D004271:DNA, Fungal / Q000235:genetics; D004952:Esters / Q000032:analysis; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000235:genetics*; D006824:Hybridization, Genetic; D009930:Organic Chemicals / Q000032:analysis; D011003:Ploidies; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012441:Saccharomyces cerevisiae / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D004271:DNA, Fungal; D004952:Esters; D009930:Organic Chemicals; D000431:Ethanol
keywords: Brewing; Heterosis; Hybrid; Lager yeast; Rare mating; S. eubayanus