Molecular identification of Penicillium species associated with blue mold on grapes in German vineyards

Species of 788 Penicillium strains from grape bunches affected by blue mold in German wine growing regions were identified by PCR based molecular methods. P. expansum was the most common species (n = 733) on the grapes and could be identified by species specific PCR of the polygalacturonase gene certainly (Marek et al., 2003). Eleven further species, P. minoluteum, P. crustosum, P. commune, P. purpurogenum, P. solitum, P. spinulosum, P. brevicompactum, P. chrysogenum (on flower residues only), P. aurantiogriseum, P. thomii/P. purpurescens, and P. janthinellum/P. griseovulvum, could be identified by different molecular methods. However, the identification of these species and the discrimination of closely related species by ITS sequencing was time consuming and not possible in each case. Therefore, a new molecular method based on an amplification of a cytochrome oxidase gene (cox1) sequence by PCR followed by a single restriction with HpyF3I or triple digestion with HpyF3I, BspT1, and BsmI was established. This method allows a fast and reliable distinction of the most common Penicillium species occurring on affected grape bunches in German wine growing regions, and allowed a discrimination of closely related species such as P. crustosum and P. commune, respectively

Nutzung genetischer Ressourcen der Europäischen Wildrebe für die Züchtung von Mehltau- und Schwarzfäule-resistenten Reben

Zur Bekämpfung der Schwarzfäule werden im ökologischen Weinbau nach wie Kupfer- oder Schwefelpräparate eingesetzt. Als Alternative sollte das Potential der Europäischen Wildrebe (Vitis sylvestris) für die Resistenzzüchtung untersucht werden. Dies würde zum einen die natürliche Artbarriere respektieren und neue Resistenzquellen für eine nachhaltige Pyramidisierung erschließen. Grundlage war eine im Rahmen des BLE-Projekts „Überlebenssicherung der Wildrebe in den Rheinauen durch gezieltes in-situ Management“ im Botanischen Garten des KIT etablierte Sammlung von V. sylvestris, die nach derzeitigem Kenntnisstand die in Deutschland für diese Art noch vorhandene genetische Diversität vollständig abbildet. In dieser Sammlung waren Hinweise auf Resistenzen gegen die Rebenkrankheiten Falscher Mehltau, Echter Mehltau und Schwarzfäule entdeckt worden. Diese Population wurde sehr detailliert in Bezug auf Resistenz gegenüber Schwarzfäule, Falschem Mehltau, Echtem Mehltau, anatomischen und chemischen Merkmalen, und genetisch mit 5-10 hochauflösenden Mikrosatellitenmarkern je Chromosom kartiert. Für zwei interessante sylvestris Genotypen konnten umfangreiche Kreuzungspopulationen mit vinifera erzeugt werden. Weiterhin wurden für die Schwarzfäule viele Aspekte der Infektion aufgeklärt. So konnte gezeigt werden, dass während der biotrophen Phase Pektine aus der Zellwand des Wirts als Nahrungsquelle genutzt werden, und dass die bessere Altersresistenz einiger sylvestris Genotypen mit Modifikationen des Pektins zusammenhängt und ein interessantes Ziel für die Resistenzzüchtung darstellen könnten. Weiterhin konnten für zwei Beispiele von nichtamerikanischen Wildreben molekulare Mechanismen aufgezeigt werden, die zu einer wirkungsvolleren basalen Immunität gegen Falschen oder Echten Mehltau führen. Das Projekt legt damit die Grundlage für die Erschließung unserer heimischen Wildrebe V. sylvestris als genetische Ressource für den nachhaltigen Weinbau der Zukunft

Surface wax in the ancestral grapevine Vitis sylvestris correlate with partial resistance to Powdery Mildew

Background Powdery Mildew of Grapevine belongs to the major diseases in viticulture and requires intensive use of fungicides. Genetic introgression of resistance factors from wild grapes from North America and, recently, China, has been successful, but wine made from those varieties is still confronted with low consumer acceptance, due to differences in taste. Results The current work explores the potential of Vitis vinifera sylvestris, the wild ancestor of domesticated Grapevine, with respect to containing Erysiphe necator, the causative agent of Powdery Mildew. Making use of a germplasm collection comprising the entire genetic variability remaining in Germany, we show that there is considerable genetic variation in the formation of leaf surface waxes exceeding wax formation in commercial varieties. Conclusions High wax formation correlates with reduced susceptibility to controlled infection with E. necator linked with perturbations of appressoria formation. We propose V. vinifera sylvestris as novel source for resistance breeding since it is genetically much closer to domesticated grapevine than the hitherto used sources from beyond the species barrier

cDNA-AFLP analysis of plant and pathogen genes expressed in grapevine infected with Plasmopara viticola

<p>Abstract</p> <p>Background</p> <p>The oomycete <it>Plasmopara viticola </it>(Berk. and Curt.) Berl. and de Toni causes downy mildew in grapevine (<it>Vitis vinifera </it>L.). This pathogen is strictly biotrophic, thus completely dependent on living host cells for its survival. The molecular basis of compatibility and disease development in this system is poorly understood. We have carried out a large-scale cDNA-AFLP analysis to identify grapevine and <it>P. viticola </it>genes associated with the infection process.</p> <p>Results</p> <p>We carried out cDNA-AFLP analysis on artificially infected leaves of the susceptible cultivar Riesling at the oil spot stage, on water-treated leaves and on a sample of pure sporangia as controls. Selective amplifications with 128 primer combinations allowed the visualization of about 7000 transcript-derived fragments (TDFs) in infected leaves, 1196 of which (17%) were differentially expressed. We sequenced 984 fragments, 804 of which were identified as grapevine transcripts after homology searching, while 96 were homologous to sequences in <it>Phytophthora </it>spp. databases and were attributed to <it>P. viticola</it>. There were 82 orphan TDFs. Many grapevine genes spanning almost all functional categories were downregulated during infection, especially genes involved in photosynthesis. Grapevine genes homologous to known resistance genes also tended to be repressed, as were several resistance gene analogs and carbonic anhydrase (recently implicated in pathogen resistance). In contrast, genes encoding cytoskeletal components, enzymes of the phenylpropanoid and beta-oxidation pathways, and pathogenesis related proteins were primarily upregulated during infection. The majority of <it>P. viticola </it>transcripts expressed <it>in planta </it>showed homology to genes of unknown function or to genomic <it>Phytophthora </it>sequences, but genes related to metabolism, energy production, transport and signal transduction were also identified.</p> <p>Conclusion</p> <p>This study provides the first global catalogue of grapevine and <it>P. viticola </it>genes expressed during infection, together with their functional annotations. This will help to elucidate the molecular basis of the infection process and identify genes and chemicals that could help to inhibit the pathogen.</p

Evaluation of a oxygenate based plant protection treatment in viticulture against fungal diseases

Over the last decades the use of pesticides in vine protection, e.g. copper is under severe discussion and is becoming a major concern in viticulture. Since the effectiveness of oxygenates against various microorganisms had been proven in the medical field a strategy for oxygenate-based plant protection was developed and evaluated over three vintages. The production of the oxygenate is following the Criegee-mechanism using O3 and unsaturated natural plant derived fatty acids forming so called ozonides. Therefore the effect of the treatment has been evaluated in a holistic approach, covering the efficiency against fungal diseases, protection of desired beneficial insects, the micro flora, various secondary metabolites of the grapevine and the resulting sensory profile of the wines. The biological effectiveness has been measured by using different in-vivo and in-vitro studies. The influence on desired berry compounds, e.g. anthocyanins, have been determined by classical GC-MS and HPLC methods. Positive effects against downy and powdery mildew could be demonstrated. No negative effects against insects, naturally occurring microorganisms, and desired berry compounds were observed. Even spontaneous fermentation was not inhibited. Quantitative descriptive sensory analysis as well as CATA/RATA showed no negative effect of the treatment

Bericht vom Fachgespräch zur Rolle von Schild- und Schmierläusen als Virusvektoren im Weinbau am Oberrhein – Management und Beratungsempfehlung

Am 07.04.2022 fand am Institut für Pflanzenschutz in Obst- und Weinbau in Siebeldingen ein Fachgespräch zur Rolle von Schild- und Schmierläusen als Virusvektoren im Weinbau am Oberrhein statt, in deme in Situationsbericht der Weinbaugebiete am Oberrhein sowie Management- und Beratungsempfehlungen erarbeitet warden sollten. Hierzu wir hier berichtet.On April 7, 2022, an expert meeting on the role of scale and mealybugs as virus vectors in viticulture in Siebeldingen in the Upper Rhine region was held at the Institute for Plant Protection in Fruit Crops and Viticulture. The aim of the meeting was to develop a situation report for the viticulture areas in the Upper Rhine region as well as management and advisory recommendations. We report on this here

Rpv3–1 mediated resistance to grapevine downy mildew is associated with specific host transcriptional responses and the accumulation of stilbenes

Background: European grapevine cultivars (Vitis vinifera spp.) are highly susceptible to the downy mildew pathogen Plasmopara viticola. Breeding of resistant V. vinifera cultivars is a promising strategy to reduce the impact of disease management. Most cultivars that have been bred for resistance to downy mildew, rely on resistance mediated by the Rpv3 (Resistance to P. viticola) locus. However, despite the extensive use of this locus, little is known about the mechanism of Rpv3-mediated resistance. Results: In this study, Rpv3-mediated defense responses were investigated in Rpv3+ and Rpv3ˉ grapevine cultivars following inoculation with two distinct P. viticola isolates avrRpv3+ and avrRpv3ˉ, with the latter being able to overcome Rpv3 resistance. Based on comparative microscopic, metabolomic and transcriptomic analyses, our results show that the Rpv3–1-mediated resistance is associated with a defense mechanism that triggers synthesis of fungi-toxic stilbenes and programmed cell death (PCD), resulting in reduced but not suppressed pathogen growth and development. Functional annotation of the encoded protein sequence of genes significantly upregulated during the Rpv3–1-mediated defense response revealed putative roles in pathogen recognition, signal transduction and defense responses. Conclusion: This study used histochemical, transcriptomic and metabolomic analyses of Rpv3+ and susceptible cultivars inoculated with avirulent and virulent P. viticola isolates to investigate mechanism underlying the Rpv3–1-mediated resistance response. We demonstrated a strong correlation between the expressions of stilbene biosynthesis related genes, the accumulation of fungi-toxic stilbenes, pathogen growth inhibition and PCD

Management of grapevine trunk diseases: knowledge transfer, current strategies and innovative strategies adopted in Europe

Since the early 1990s, grapevine trunk diseases (GTDs) have posed threats for viticulture. Esca complex, Eutypa- and Botryosphaeria- diebacks, mostly detected in adult vineyards, are currently responsible for considerable economic losses in the main vine-growing areas of the world. Other GTDs, such as Petri- (Esca complex) and Black-foot diseases, are emerging problems in grapevine nurseries (resulting in grafting failures and/or loss of saleable plants) and in young vineyards. The impacts of GTDs in modern viticulture depend on several factors, some related to their complexity, and others linked to host plant characteristics, changes in vineyard management and to the scarcity of simple tools for their control. For these reasons control of GTDs remains difficult, also depending on knowledge transfer from research to field and vice versa. This paper outlines the main preventive and curative techniques currently applied, scientifically tested or not that have resulted from the outcomes of “Winetwork”, a European Union funded project with special emphasis on the promising and innovative approaches.