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Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of intense research, as they are able to combine the favourable characteristics of both parental strains. In this study, two Saccharomyces “Kéknyelű” grape juice isolates were identified by species-specific PCR and PCR-RFLP methods and investigated with respect to their wine fermentation potential. Physiological characterization of the isolated strains was performed and included assessment of ethanol, sulphur dioxide, temperature and glucose (osmotic stress) tolerance, killer-toxin production, glucose fermentation ability at 16 °C and 24 °C, and laboratory-scale fermentation using sterile “Kéknyelű” must. Volatile components of the final product were studied by gas chromatography (GC) and mass spectrometry (MS). One isolate was identified as a S. cerevisiae × S. kudriavzevii hybrid and the other was S. cerevisiae. Both strains were characterized by high ethanol, sulphur dioxide and glucose tolerance, and the S. cerevisiae strain exhibited the killer phenotype. The hybrid isolate showed good glucose fermentation ability and achieved the lowest residual sugar content in wine. The ester production of the hybrid strain was high compared to the control S. cerevisiae starter strain, and this contributed to the fruity aroma of the wine. Both strains have good oenological characteristics, but only the hybrid yeast has the potential for use in wine fermentation.

<p style="text-align: justify;"><strong>Aims</strong>: The aim of this work was to determine the SSR profile of 96 <em>Vitis</em> accessions (mainly rootstocks) at 19 loci to find genetic relatedness between them.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The molecular markers used in the last 30 years are not or less affected by the environment, making them a valuable tool for the determination of genetic distances. Based on our former experiences, an SSR analysis was carried out on 96 grape accretions, mainly rootstocks. DNA was extracted from young leaves and analyses were carried out at 19 microsatellite loci. The loci were selected to cover all of the linkage groups to get a more accurate genotyping of each grape rootstock. Results of the SSR analysis and the resulting dendrogram showing genetic relatedness are presented.</p><p style="text-align: justify;"><strong>Conclusions</strong>: Based on the results, it can be established, that most of the selected loci showed appropriate polymorphism for the assessment of genetic relatedness. The rootstocks derived from Teleki’s seedlings showed high similarity. A low genetic distance was also detected between the accessions originated from the cross between Börner and Georgikon 28. Finally, the <em>Vitis sylvestris</em> accessions showed close relatedness with the <em>Vitis vinifera</em> L. varieties.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: Our results indicate a high level of polymorphism between grape rootstock accessions. Strong differences were detected between the so-called Teleki 5C (T5C) and Teleki-Kober 5BB (T5KBB) “clones”, suggesting that they are not real clones but different genotypes with highly similar morphological features.</p>

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