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Pichia sorbitophila, an Interspecies Yeast Hybrid, Reveals Early Steps of Genome Resolution After Polyploidization

By Véronique Leh Louis, Laurence Despons, Anne Friedrich, Tiphaine Martin, Pascal Durrens, Serge Casarégola, Cécile Neuvéglise, Cécile Fairhead, Christian Marck, José A. Cruz, Marie-Laure Straub, Valérie Kugler, Christine Sacerdot, Zlatyo Uzunov, Agnes Thierry, Stéphanie Weiss, Claudine Bleykasten, Jacky De Montigny, Noemie Jacques, Paul Jung, Marc Lemaire, Sandrine Mallet, Guillaume Morel, Guy-Franck Richard, Anasua Sarkar, Guilhem Savel, Joseph Schacherer, Marie-Line Seret, Emmanuel Talla, Gaelle Samson, Claire Jubin, Julie Poulain, Benoît Vacherie, Valérie Barbe, Eric Pelletier, David J. Sherman, Eric Westhof, Jean Weissenbach, Philippe V. Baret, Patrick Wincker, Claude Gaillardin, Bernard Dujon and Jean-Luc Souciet


Polyploidization is an important process in the evolution of eukaryotic genomes, but ensuing molecular mechanisms remain to be clarified. Autopolyploidization or whole-genome duplication events frequently are resolved in resulting lineages by the loss of single genes from most duplicated pairs, causing transient gene dosage imbalance and accelerating speciation through meiotic infertility. Allopolyploidization or formation of interspecies hybrids raises the problem of genetic incompatibility (Bateson-Dobzhansky-Muller effect) and may be resolved by the accumulation of mutational changes in resulting lineages. In this article, we show that an osmotolerant yeast species, Pichia sorbitophila, recently isolated in a concentrated sorbitol solution in industry, illustrates this last situation. Its genome is a mosaic of homologous and homeologous chromosomes, or parts thereof, that corresponds to a recently formed hybrid in the process of evolution. The respective parental contributions to this genome were characterized using existing variations in GC content. The genomic changes that occurred during the short period since hybrid formation were identified (e.g., loss of heterozygosity, unilateral loss of rDNA, reciprocal exchange) and distinguished from those undergone by the two parental genomes after separation from their common ancestor (i.e., NUMT (NUclear sequences of MiTochondrial origin) insertions, gene acquisitions, gene location movements, reciprocal translocation). We found that the physiological characteristics of this new yeast species are determined by specific but unequal contributions of its two parents, one of which could be identified as very closely related to an extant Pichia farinosa strain

Topics: Investigations
Publisher: Genetics Society of America
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Provided by: PubMed Central
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