In the grapevine cultivar 'Börner' QTLs for black rot resistance were detected consistently in several independent experiments. For one QTL on chromosome 14 closely linked markers were developed and a detailed map provided. Black rot is a serious grapevine disease that causes substantial yield loss under unfavourable conditions. All traditional European grapevine cultivars are susceptible to the causative fungus Guignardia bidwellii which is native to North America. The cultivar 'Börner', an interspecific hybrid of V. riparia and V. cinerea, shows a high resistance to black rot. Therefore, a mapping population derived from the cross of the susceptible breeding line V3125 ('Schiava grossa' × 'Riesling') with 'Börner' was used to carry out QTL analysis. A resistance test was established based on potted plants which were artificially inoculated in a climate chamber with in vitro produced G. bidwellii spores. Several rating systems were developed and tested. Finally, a five class scheme was applied for scoring the level of resistance. A major QTL was detected based on a previously constructed genetic map and data from six independent resistance tests in the climate chamber and one rating of natural infections in the field. The QTL is located on linkage group 14 (Rgb1) and explained up to 21.8 % of the phenotypic variation (LOD 10.5). A second stable QTL mapped on linkage group 16 (Rgb2; LOD 4.2) and explained 8.5 % of the phenotypic variation. These two QTLs together with several minor QTLs observed on the integrated map indicate a polygenic nature of the black rot resistance in 'Börner'. A detailed genetic map is presented for the locus Rgb1 with tightly linked markers valuable for the development for marker-assisted selection for black rot resistance in grapevine breeding.
Considering that many Saccharomyces cerevisiae strains exist and that they have different fermentation capacities, the challenge is to select the yeast strain that generates the most interesting wine character and wine flavor for the winemaker. A method based on simple sequence repeats (SSRs) markers, occurring in the yeast genome, was developed to differentiate the collected S.cerevisiae strains. For the amplification of the polymorphic SSR markers performed by polymerase chain reaction (PCR), two primer sets showing different size products for different S. cerevisiae strains were designed. The PCR-method with gel electrophoresis was validated using capillary sequencing and then used as a service for winegrowers combined with a sensory analysis via napping. This approach can be used for the preservation of the yeast diversity associated with given terroirs and as an option for an increased safety of fermentations. The application of S. cerevisiae strains collected in spontaneous fermentations and used for fermentation sustains the initial character of the wine and ensures a secure fermentation at the same time.
In this study, an amplicon metagenomic approach was used to determine the effect of repeated treatments with ozonized oleic acid on the microbial community of grapevine carpoplane. Differences in community composition of treated vineyards were compared to non-treated and conventionally treated samples regarding the prokaryotic and eukaryotic microbiome at two developmental stages (BBCH 83, BBCH 87). The results showed effects both on occurrence and on abundance of microorganisms and the community assembly. Wine-relevant genera such as Acetobacter and members of the former genus Lactobacillus could be identified as part of the natural microbiota. The impact of the new viticultural treatment on these organisms was assessed in liquid culture-based microtiter assays. Therefore, we investigated an array of two acetic acid bacteria (AAB), four lactic acid bacteria (LAB) and nine saccharomyces and non-saccharomyces yeasts. Brettanomyces bruxellensis, Saccharomyces cerevisiae, Pediococcus sp. and Acetobacter aceti revealed the highest sensitivities against ozonized oleic acid (LIQUENSO® Oxygenat). Culture growth of these organisms was significantly reduced at an ozonide concentration of 0.25% (v/v), which corresponded to a quarter of the concentration used in the vineyard. The metabarcoding approach in combination with complementary in vitro assays allow new insights into treatment effects on the community and species scale.
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