Evaluation Of The Genetic Diversity For Saccharomyces Cerevisiae By Sequence Analysis And Microsatellite Markers

Saccharomyces cerevisiae, widely used in brewing, food, energy, pharmaceuticals,environmental protection, feeding and so on, had great economic value and the closestrelationship with human activity. And it had also been used as a eukaryotic model organism inmodern molecular biology and cell biology. And fifty S. cerevisiae strains from differentindustrial applications in traditional brewing industry and other laboratories or publiccollections were selected and the genetic diversity and phylogenetic relationship among thesestrains were studied using sequences analysis and microsatellite markers.Firstly the genetic diversity of the selected yeast strains was evaluated on the basis ofsequences analysis of5.8S and ITS-2rDNA, the large-subunit (26S) rDNA D1/D2domainand RPB2gene. The results showed that there were differences between many strains, exceptthat some of them have the same sequence of5.8S and ITS-2rDNA, and the maximumdifference among the strains was three bases. The sequences of26S rDNA D1/D2domainwere highly conserved in the seleted strains and the maximum difference among the strainswas only two bases. Compared with the above two, the variability of RPB2gene of the stainswas slightly higher and the maximum difference among the strains was ten bases. The resultsconfirmed that sequence polymorphism existed among the yeast strains and the variation ofthe strains was different in different regions. And the sequence similarities of fifty strains withS. cerevisiae S288c are from99%to100%. The variation of the strains was not enough sothat the stains could not be discriminated.Subsequently genetic diversity of the selected yeast strains was evaluated on the basis ofmicrosatellite markers. Allele number, allele frequency, gene heterozygosity, polymorphisminformation content for eleven microsatellite loci among the yeast strains were calculated andcluster analysis based on Dice similarity coefficient of the strains was performed. The resultsshowed that a total of50multilocus genotypes and210alleles were observed bymicrosatellite markers among the yeast strains. The allele number for each locus ranged from9to38and the average allele number per locus was19.09, which exhibited a higherpolymorphism. The mean observed heterozygosity and the mean expected heterozygositywere0.564(0.229~0.880) and0.851(0.697~0.956), respectively. And the averagepolymorphic information content (PIC) was0.851(0.697~0.956). These results showed thatthe abundant polymorphism existed among the yeast strains. The cluster analysis showed thatall strains can be differentiated but the correlation between clustering relationships, industrialsources or applications of the strains was not observed.The study showed that the microevolutionary changes occurred in the industrialapplications of S. cerevisiae because of the long-term presence in the fermentation processand the abundant polymorphism exists among the strain within species. The genetic variationwas closely connected with its existing environment, but no significant correlation existedbetween the cluster groups and their industrial applications. And the study would providesome reference for obtaining adequate strains to meet the need of different fermentationprocess and getting better development and utilization of S. cerevisiae.