Project description:Analysis of genomic variation in several Saccharomyces cerevisiae x S. kudriavzevii natural hybrids S. cerevisiae and S. kudriavzevii yeasts have been described among wine strains. These strains exhibit enological properties of interest for the wine industry. A preliminary characterization of these hybrids showed a trend to reduce the S. kudriavzevii fraction of the hybrid genome. As a first approach to understand the mechanisms involved in the genome changes occurred after hybridization that may account for differences in their enological properties, we characterized the genomic constitution of several wine S. cerevisiae x S. kudriavzevii strains by using a combined approach based on the RFLP analysis of gene regions, comparative genome hybridizations with S. cerevisiae DNA arrays, ploidy analysis and gene dose determination by quantitative real-time PCR. Genomic DNA hybridizations of w27, w46, SPG1691 and 441 hybrids were compared against the laboratory strain FY1679. Hybridizations were performed by triplicate in order to obtain the final CGH ratio.
Project description:This research work investigates the expression of the genes involved in flavor compound production in two hybrids between Saccharomyces cerevisiae and S. kudriavzevii under low (12°C) and moderate fermentation temperatures (28°C).
Project description:In this work, we evaluated the genetic stabilization process, of the intra- (Saccharomyces cerevisiae) and interspecific (S. cerevisiae x Saccharomyces kudriavzevii) hybrids obtained by different non-GMO techniques, under fermentative conditions. Large-scale transitions in genome size, detected by measuring total DNA content, and genome reorganizations in both nuclear and mitochondrial DNA, evidenced by changes in molecular markers, were observed during the experiments. Interspecific hybrids seem to need fewer generations to reach genetic stability than intraspecific hybrids. The largest number of molecular patterns among the derived stable colonies was observed for intraspecific hybrids, particularly for those obtained by rare-mating in which the total amount of initial DNA was larger. Finally, a representative intraspecific stable hybrid underwent a normal industrial process to obtain active dry yeast production as an important point at which inducing changes in genome composition was possible. No changes in hybrid genetic composition after this procedure were confirmed by comparative genome hybridization. According to our results, fermentation steps 2 and 5 –comprising between 30 and 50 generations- suffice to obtain genetically stable interspecific and intraspecific hybrids, respectively. This work aimed to develop and validate a fast genetic stabilization method for newly generated Saccharomyces hybrids under selective enological conditions. A comparison of the whole stabilization process in intra- and interspecific hybrids showing different ploidy levels, as a result of using different hybridization methodologies, was also made.
Project description:The aim of this experiment is to characterize the genome composition of the two hybrids IF6 and MR25. IF6 and MR25 are hybrids among S.cerevisiae and S. kudriavzevii. The hybridization of the genome extraction with the microarray was at 65C, under this condition only S. cerevisiae genes can hybridize. In this case we are only studying the genome composition of S. cerevisiae parental in the hybrids. The study of S. kudriavzevii parental genome was done by other methods.
Project description:In this work, we evaluated the genetic stabilization process, of the intra- (Saccharomyces cerevisiae) and interspecific (S. cerevisiae x Saccharomyces kudriavzevii) hybrids obtained by different non-GMO techniques, under fermentative conditions. Large-scale transitions in genome size, detected by measuring total DNA content, and genome reorganizations in both nuclear and mitochondrial DNA, evidenced by changes in molecular markers, were observed during the experiments. Interspecific hybrids seem to need fewer generations to reach genetic stability than intraspecific hybrids. The largest number of molecular patterns among the derived stable colonies was observed for intraspecific hybrids, particularly for those obtained by rare-mating in which the total amount of initial DNA was larger. Finally, a representative intraspecific stable hybrid underwent a normal industrial process to obtain active dry yeast production as an important point at which inducing changes in genome composition was possible. No changes in hybrid genetic composition after this procedure were confirmed by comparative genome hybridization. According to our results, fermentation steps 2 and 5 –comprising between 30 and 50 generations- suffice to obtain genetically stable interspecific and intraspecific hybrids, respectively. This work aimed to develop and validate a fast genetic stabilization method for newly generated Saccharomyces hybrids under selective enological conditions. A comparison of the whole stabilization process in intra- and interspecific hybrids showing different ploidy levels, as a result of using different hybridization methodologies, was also made. A stable hybrid strain was compared with itself before and after ADY (active dry yeast) production in order to evaluate the genetic stability of this strain.
Project description:Comparative genome-wide gene expression analysis between two industrial wine yeast hybrid strains belonging to the species S. cerevisiae x S. Kudriavzevii, in natural must fermentations.
Project description:Determining the different sources of heritable variation underlying quantitative traits in nature is currently at the forefront of genetic studies. To this end, molecular profiling studies in S. cerevisiae have shown that individual gene expression levels are subject to genetic control and this variation can mediate genetic differences on phenotype. Thus, determining how natural variation influences allele specific expression (ASE) and ultimately complex traits represents a useful tool to determine the mechanisms leading to yeast niche adaptation. Here, in order to test the hypothesis that allele-specific expression differences between isolates contributes to the phenotypic diversity in natural populations, we evaluated ASE levels in a grid of six F1 hybrids from the cross of four representative founder strains from major lineages. Genome-wide and across hybrids we quantified ASE for 3,320 genes. We found evidence for abundant genome-wide expression differences between alleles, with levels ranging between 27% up to 61% of the evaluated genes, depending on the cross. We observed that ASE can be explained by allele-specific differences in transcription factor binding to cis-regulatory regions and differences in strain-specific trans-activation can be detected by taking advantage of the shared trans environment of F1 hybrids. Furthermore, modules of genes under cis-regulatory variation with related function are enriched within the different genetic backgrounds, supporting the premise of intraspecies directional regulatory selection in yeast. Finally, we were able to identify two genes, GDB1 and ASN1 exhibiting high expression levels in the Wine/European strain and underlying phenotypic differences for oenological phenotypes due to polymorphisms within non-coding regions, providing direct evidence of the importance of regulatory variation in natural trait diversity.
Project description:We created a multi-species microarray platform, containing probes to the whole genomes of seven different Saccharomyces species, with very dense coverage (one probe every ~500 bp) of the S. cerevisiae genome, including non-S288c regions, mitochondrial and 2 micron circle genomes, plus probes at fairly dense coverage (one probe every ~2,100 bp) for each of the genomes of six other Saccharomyces species: S. paradoxus, S. mikatae, S. kudriavzevii, S. bayanus, S. kluyveri and S. castellii. We performed array-Comparative Genomic Hybridization (aCGH) using this platform, examining 83 different Saccharomyces strains collected across a wide range of habitats; of these, 69 were widely used commercial S. cerevisiae wine strains, while the remaining 14 were from a wide range of other industrial and natural habitats. Thus, we were able to sample much of the pan-genome space of the Saccharomyces genus. We observed interspecific hybridization events, introgression events, and pervasive copy number variation (CNV) in all but a few of the strains. These CNVs were distributed throughout the strains such that they did not produce any clear phylogeny, suggesting extensive mating in both industrial and wild strains. To validate our results and to determine whether apparently similar introgressions and CNVs were identical by descent or recurrent, we also performed whole genome sequencing on nine of these strains. These data may help pinpoint genomic regions involved in adaptation to different industrial milieus, as well as shed light on the course of domestication of S. cerevisiae.