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    A European Database of Fusarium graminearum and F-culmorum Trichothecene Genotypes
    (Frontiers Media Sa, 2016) Pasquali, Matias; Beyer, Marco; Logrieco, Antonio; Audenaert, Kris; Balmas, Virgilio; Basler, Ryan; Vogelgsang, Susanne; Koycu, Nagehan D.
    Fusarium species, particularly Fusarium graminearum and F culmorum, are the main cause of trichothecene type B contamination in cereals. Data on the distribution of Fusarium trichothecene genotypes in cereals in Europe are scattered in time and space. Furthermore, a common core set of related variables (sampling method, host cultivar, previous crop, etc.) that would allow more effective analysis of factors influencing the spatial and temporal population distribution, is lacking. Consequently, based on the available data, it is difficult to identify factors influencing chemotype distribution and spread at the European level. Here we describe the results of a collaborative integrated work which aims (1) to characterize the trichothecene genotypes of strains from three Fusarium species, collected over the period 2000-2013 and (2) to enhance the standardization of epidemiological data collection. Information on host plant, country of origin, sampling location, year of sampling and previous crop of 1147 F graminearurn, 479 F culmorum, and 3 F cortaderiae strains obtained from 17 European countries was compiled and a map of trichothecene type B genotype distribution was plotted for each species. All information on the strains was collected in a freely accessible and updatable database (www.catalogueeu.luxmcc.lu), which will serve as a starting point for epidemiological analysis of potential spatial and temporal trichothecene genotype shifts in Europe. The analysis of the currently available European dataset showed that in F. grarninearum, the predominant genotype was 15-acetyldeoxynivalenol (15-ADON) (82.9%), followed by 3-acetyldeoxynivalenol (3-ADON) (13.6%), and nivalenol (NIV) (3.5%). In F culmorum, the prevalent genotype was 3-ADON (59.9%), while the NIV genotype accounted for the remaining 40.1%. Both, geographical and temporal patterns of trichothecene genotypes distribution were identified.
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    Cold Climate Winegrape Cultivar Sensitivity to Sulfur in the Northern Great Plains Region of the United States
    (Amer Soc Horticultural Science, 2017) Koycu, Nagehan D.; Stenger, John E.; Hatterman-Valenti, Harlene M.
    Elemental sulfur is commonly applied for powdery mildew (Erysiphe necator) protection on winegrape (Vitis sp.). The product may be used in a diversified, integrated disease management system to help prevent fungicide resistance to products with other modes of action. Additionally, sulfur may be used as a control option in organic systems. Applications of sulfur have been known to cause phytotoxic injury to susceptible winegrape cultivars, particularly those stemming from fox grape (Vitis labrusca) parentage. To improve recommendations to producers in the northern Great Plains region of the United States, a comparison of injury incidence and severity, as well as effects on yield characteristics was undertaken for 13 regional cultivars exposed to three sulfur rates (0, 2.4, and 4.8 lb/acre a.i.) at a North Dakota State University Research Station near Absaraka, ND. Overall, four cultivars (Bluebell, Baltica, Sabrevois, and King of the North) of the 13 cultivars tested showed phytotoxic symptoms. Injury severity and incidence of these cultivars differed between years and across rates. 'Bluebell' showed consistent and severe sulfur injury symptoms. Injury to the other three susceptible cultivars tended to vary by the given environment, with King of the North generally showing the lowest injury response. Injury symptoms were not found to be associated with the overall yield or cluster weight. Results suggest that alternative spray programs that exclude sulfur- based fungicides should be recommended for ' Bluebell', 'Baltica', 'Sabrevois', and 'King of the North', whereas sulfur- based fungicides may be applied to 'Alpenglow', 'ES 12- 6- 18', 'Frontenac', 'Frontenac Gris', 'La Crescent', 'Marquette', 'Somerset Seedless', 'St. Croix', and 'Valiant'. Observations on fruit ripening in 2014 suggest that future research is needed to determine if a reduction of fruit quality may occur in some seasons with repeated sulfur applications or with successive annual sulfur applications for susceptible cultivars if used in an organic production system.
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    T-Resveratrol Accumulation and Polygalacturonase Inhibition During Infection of Grape Berries By Botrytis Cinerea
    (Springer, 2014) Koycu, Nagehan D.; Özer, Nuray; Martignoni, D.; Aleandri, M. P.; Timperio, A.; Magro, P.; Chilosi, G.
    The resistance of immature grape berries to Botrytis cinerea Pers. ex Fr. results from a combination of factors, among which the accumulation of the stilbene phytoalexin t-resveratrol. Stilbene accumulation is thought to be induced by oligogalacturonides (OGs) which are released from the plant cell wall during tissue maceration catalysed by polygalacturonases (PGs) produced by necrotrophic fungal pathogens. Inhibitors of PG activity, the polygalacturonase-inhibiting proteins (PGIPs), have the capability to slow the hydrolytic activity of PGs and favour the accumulation of active OGs. In the present work we have observed that artificial inoculation of grape inflorescences and immature berries at bloom and post bloom, leads to severe infection of the rachis, while lesions on young berries did not result in the development of the disease, but in the development of necrotic spots and rings. PG was detectable in berry tissues, but its secretion was significantly lower than in infected leaves. Tissues of immature berries reacted to B. cinerea inoculation by a marked accumulation of t-resveratrol. PG produced during spore germination of B. cinerea elicited t-resveratrol accumulation. Apoplastic fluids (AFs) from immature berries and leaves were found to inhibit total PG activity produced by B. cinerea, indicating the involvement of a proteinaceous or non-proteinaceous PG inhibitor, or both, as intercellular defence mechanisms. Taken together, our results suggest that the inhibition of PG produced by B. cinerea mediated by a putative PG inhibitor during the early stages of infection of immature grape berries plays a central role in promoting accumulation of t-resveratrol and, consequently, the restriction of pathogen spread.