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Boso S.,Mision Biologica de Galicia | Alonso-Villaverde V.,Mision Biologica de Galicia | Martinez M.-C.,Mision Biologica de Galicia | Kassemeyer H.-H.,State Viticulture Institute Freiburg
American Journal of Enology and Viticulture | Year: 2012

Stilbenic phytoalexins have been associated with disease resistance. In Vitis spp., stilbene synthesis can be induced by UV irradiation, treatment with a variety of substance extracts, and inoculation with Botrytis cinerea or Plasmopara viticola. The aim of the present work was to examine the relationship between stilbene production and the level of resistance of different Vitis genotypes to P. viticola. The ability of different grapevine genotypes (Vitis vinifera L. cvs. Tempranillo, Touriga Nacional, Pinot noir, and Cabernet Sauvignon and Vitis riparia cv. Gloire de Montpellier) to resist Plasmopara viticola infection was assessed via their potential to accumulate toxic stilbenic phytoalexins. Leaf discs taken from plants belonging to these genotypes were inoculated with P. viticola sporangia and disease severity was determined five days later. Stilbene production was quantified in similar leaf material at 6, 24, 48, and 72 hr postinoculation. After P. viticola infection, the resistant genotype V. riparia showed high production of the phytotoxic stilbenes ε- and δ-viniferin, which limited the development of the pathogen and prevented it from producing spores. Indeed, this genotype was associated with the lowest sporulation values. No relationship was observed, however, between resistance and these compounds in the V. vinifera genotypes. Further study is required to define the role of stilbenic phytoalexins in resistance to P. viticola. © 2012 by the American Society for Enology and Viticulture. All rights reserved.

Trondle D.,Karlsruhe Institute of Technology | Schroder S.,Karlsruhe Institute of Technology | Kassemeyer H.-H.,State Viticulture Institute Freiburg | Kiefer C.,Heidelberg Institute of Plant science | And 2 more authors.
American Journal of Botany | Year: 2010

Premise of the study: This work represents the first molecular phylogeny of the economically important genus Vitis, an important genetic resource for breeding in grapevine, Vitis vinifera. Methods: A molecular phylogeny of Vitis using a combined data set of three noncoding regions of the plastid DNA genome was constructed from 47 accessions covering 30 species of Vitis. The data for the trnL-F marker were combined with previously published data across the Vitaceae. Key results: The molecular phylogeny demonstrated monophyly of the genus Vitis. Based on the combined analysis of three genes, Vitis is split into three clades that mirror the continental distribution of these accessions. The diversity is highest in the Asian clade, but the general genetic distances across taxa from different continents are relatively small. Conclusions: The findings support a relatively recent and intense gene flow between East Asia and North America and the possible impact of hybridization on the evolution of the genus Vitis. Taxon identity in important stock collections should be screened carefully because roughly 10% of the accessions analyzed in the present study had been misidentified. © 2010 Botanical Society of America.

Fischer M.,Julius Kuhn Institute | Kassemeyer H.-H.,State Viticulture Institute Freiburg
Vitis - Journal of Grapevine Research | Year: 2012

Impact of abiotic factors has been recently discussed in grapevine trunk diseases such as Esca. Emphasis of the present study lies on the relation between different water regime ("normal" and "stress") on one side and growth characters as well as Esca-related wood symptoms on the other side. Trials were conducted in the greenhouse with cuttings of the cultivars 'Müller-Thurgau' and 'Riesling', part of which artificially infected with Phaeomoniella chlamydospora. During a 12 month incubation period the following characters were evaluated: shoot length, weight of stem, expression of wood symptoms, and survival rate of plants. For evaluation of wood symptoms a numerical system was developed that is applied here for the first time. The obtained results indicate that water supply plays a statistically significant role, with plants under "stress" regime shown to be more affected. No strict spatial correlation was found to exist between wood symptoms and physical presence of the pathogen.

Delmotte F.,CNRS Agroecology Lab | Delmotte F.,University of Bordeaux 1 | Mestre P.,CNRS Vine Health and Wine Quality | Schneider C.,CNRS Vine Health and Wine Quality | And 8 more authors.
Infection, Genetics and Evolution | Year: 2014

Crop pathogens evolve rapidly to adapt to their hosts. The use of crops with quantitative disease resistance is expected to alter selection of pathogen life-history traits. This may result in differential adaptation of the pathogen to host cultivars and, sometimes, to the erosion of quantitative resistance. Here, we assessed the level of host adaptation in an oomycete plant pathogenic species. We analysed the phenotypic and genetic variability of 17 Plasmopara viticola isolates collected on Vitis vinifera and 35 isolates from partially resistant varieties (Regent and genotypes carrying the Rpv1 gene). Cross-inoculation experiments assessed two components of aggressiveness and a life-history trait of the pathogen: disease severity, sporangial production and sporangia size. The results contribute evidence to the emergence of P. viticola aggressive isolates presenting a high level of sporulation on the partially resistant Regent. By contrast, no adaptation to the Rpv1 gene was found in this study. The erosion of Regent resistance may have occurred in less than 5. years and at least three times independently in three distant wine-producing areas. Populations from resistant varieties showed a significant increase in sporangia production capacity, indicating an absence of fitness costs for this adaptation. The increase in the number of sporangia was correlated with a reduction in sporangia size, a result which illustrates how partial plant disease resistance can impact selection of the pathogen's life-history traits. This case study on grapevine downy mildew shows how new plant pathogen populations emerge in agro-ecosystems by adapting to partial host resistance. This adaptive pattern highlights the need for wise management of plant partial disease resistance to ensure its sustainability over time. © 2013 Elsevier B.V.

Sack M.,Karlsruhe Institute of Technology | Sigler J.,Karlsruhe Institute of Technology | Eing C.,Karlsruhe Institute of Technology | Stukenbrock L.,State Viticulture Institute Freiburg | And 3 more authors.
IEEE Transactions on Plasma Science | Year: 2010

In the course of the production of red wine, electroporation of mash enables a fast extraction of the red pigments from the skin without remarkable heating of the mash. For white wine, the formation of pores in the cells fosters, among others, the extraction of flavoring substances. During the harvest in 2008, the electroporation device KEA-WEIN has been operated successfully in two wineries. All together, more than 5 m 3 of mash has been treated. During this year's experiments, some experience in the operation of the electroporation device on-site in a winery has been gained. To facilitate the evaluation of the experimental results, the electroporation device has been equipped with different sensors and measurement systems, e.g., for the power drawn from the grid and the temperature of the mash before and after the electroporation. The data logged during one exemplary run are presented in this paper. Based on the measurements, an estimation about the energy consumption and efficiency of the device has been made. Must and wine made from the grape varieties Pinot Noir and Riesling have been chemically analyzed. Selected data are presented in this paper. © 2010 IEEE.

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