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Boeriu C.G.,Wageningen UR Food and Biobased Research | Frissen A.E.,Wageningen UR Food and Biobased Research | Boer E.,Wageningen UR Plant Research International | Van Kekem K.,Wageningen UR Food and Biobased Research | And 2 more authors.
Journal of Molecular Catalysis B: Enzymatic

A mild and efficient method for the conversion of C-terminal esters of side-chain protected peptides into an amide function via enzyme-catalysed ammonolysis in organic media with low water content is described. Subtilisin A, the alkaline serine protease from Bacillus licheniformis, was used as biocatalyst and ammonium carbamate as source of ammonia. Response surface methodology (RSM) and central composite design were employed to estimate the effects of reaction parameters such as molar ratio of ammonia source to peptide methyl ester (2:1-10:1), composition of the solvent system (Bu tOH/DMF, % v/v, 70:30-95:5) and water concentration (0.2-0.8%) at different temperatures (30-50 °C) for the preparation of Z-Ala-Phe-NH 2 starting from Z-Ala-Phe-OMe. Optimum reaction conditions for maximum amide yield and minimum secondary hydrolysis were determined from cross-section analysis: temperature 30 °C, solvent composition Bu tOH/DMF 82.5:17.5 (v/v) containing 0.2% water (v/v) and molar ratio of ammonia source to peptide methyl ester of 10:1. The maximum yield of Z-Ala-Phe-NH2 was 87% after 21 h for a quantitative substrate conversion. The method proved to be generally applicable for the synthesis of C-terminal amides of dipeptides with different terminal amino acids and sequence. © 2010 Elsevier B.V. All rights reserved. Source

Palazzini J.M.,National University of Rio Cuarto | Alberione E.,Instituto Nacional de Tecnologia Agropecuaria | Torres A.,National University of Rio Cuarto | Donat C.,Bio ferm GmbH | And 2 more authors.
Biological Control

Fusarium head blight (FHB) mainly caused by Fusarium graminearum is a devastating disease that causes extensive yield and quality losses to wheat in humid and semi-humid regions of the world. The biocontrol effect of two bacterial strains on FHB incidence, severity and deoxynivalenol (DON) accumulation in wheat was evaluated in field trials during 2010 and 2011 at Marcos Juarez, Córdoba province, Argentina. Bacillus subtilis RC 218 and Brevibacillus sp. RC 263 applied at anthesis period were evaluated through several combinations of cell type, strains, inoculum density (104 and 106cfu/ml) and physiological modification. A significant and consistent biocontrol effect on FHB severity and DON contamination was observed in all the evaluated treatments during both 2010 and 2011 field trials. Reduction in FHB severity ranged 62-76% and 42-58% for 2010 and 2011 field trials, respectively. When evaluating the effect of the combined strains (104+104 and 106+106cfu/ml), a better biocontrol effect was observed in 2010 field trial. After biocontrol treatments, no DON accumulation was observed in wheat heads; meanwhile in control plots an average of 1372μg/kg DON was detected during the two trials. FHB incidence was significantly reduced by biocontrol treatments during the 2010 field trial but not during the 2011 field trial. The results showed the effectiveness of the two formulated biological control agents in reducing both FHB severity and DON accumulation by F. graminearum under semi controlled field conditions. © 2015 Elsevier Inc. Source

Kohl J.,Wageningen UR Plant Research International | Scheer C.,Foundation Kompetenzzentrum Obstbau Bodensee | Holb I.J.,Debrecen University | Holb I.J.,Hungarian Academy of Sciences | And 2 more authors.
Plant Disease

Apple scab, caused by Venturia inaequalis, is the most important disease in apple production, reducing yield and quality of fruit. Control of apple scab in commercial orchards currently depends on multiple applications of fungicides. The potential of the antagonistic isolate Cladosporium cladosporioides H39, originating from a sporulating colony of V. inaequalis, to control apple scab development was tested in eight trials during 2 years in orchards in Eperjeske (Hungary), Dabrowice (Poland), and Bavendorf (Germany) planted with different cultivars. Treatments were conducted as calendar sprays or after infection periods. Additional trials in an orchard in Randwijk (The Netherlands) focused on the effect of timing of antagonist application before or after infection periods. The overall results of the field trials consistently showed—for the first time—that stand-alone applications of the antagonist C. cladosporioides H39 can reduce apple scab in leaves and fruit. This was demonstrated in an organic growing system as well as in conventional orchards by spray schedules applied during the primary or the summer season. In both systems, the same control levels could be reached as with common fungicide schedules. Efficacies reached 42 to 98% on leaf scab incidence and 41 to 94% on fruit scab. The antagonist was also effective if applied one or even several days (equivalent to approximately 300 to 2,000 degree h) after infection events in several field trials and a trial conducted in Randwijk with single-spray applications at different intervals before or after infection events. Better understanding of the biology of the antagonist will help to further exploit its use in apple scab control. © 2015 The American Phytopathological Society. Source

Aarts H.F.M.,Wageningen UR Plant Research International | Humphreys J.,Teagasc | Le Gall A.,Institute Of Lelevage
Journal of Agricultural Science

Substantial improvements of agricultural systems are necessary to meet the future requirements of humanity. However, current agricultural knowledge and information systems are generally not well suited to meet the necessary improvements in productivity and sustainability. For more effective application of research output, research producers and research consumers should not be considered as separate individuals in the knowledge chain but as collaborating partners creating synergy. The current paper investigates the relationships between scientists and stakeholders and identifies approaches to increase the effectiveness of their communication. On-farm research has proven to be an effective means of improving exploitation of research output at farm level because it connects all relevant partners in the process. Furthermore, pilot farms can act as an effective platform for communication and dissemination. Regional networks of pilot farms should be established and connected across regions. © Cambridge University Press 2014. Source

Palazzini J.M.,National University of Rio Cuarto | Groenenboom-de Haas B.H.,Wageningen UR Plant Research International | Torres A.M.,National University of Rio Cuarto | Kohl J.,Wageningen UR Plant Research International | Chulze S.N.,National University of Rio Cuarto
Plant Pathology

The biocontrol effect of Clonostachys rosea (strains 016 and 1457) on Fusarium graminearum, F. avenaceum, F. verticillioides, F. langsethiae, F. poae, F. sporotrichioides, F. culmorum and Microdochium nivale was evaluated on naturally infected wheat stalks exposed to field conditions for 180 days. Experiments were conducted at two locations in Argentina, Marcos Juarez and Río Cuarto. Antagonists were applied as conidial suspensions at two inoculum levels. Pathogens were quantified by TaqMan real-time qPCR. During the first year at Marcos Juarez, biocontrol was observed in one antagonist treatment for F. graminearum after 90 days (73% reduction) but after 180 days, the pathogen decreased to undetectable levels. During the second year, biocontrol was observed in three antagonist treatments for F. graminearum and F. avenaceum (68·3% and 98·9% DNA reduction, respectively, after 90 days). Fusarium verticillioides was not controlled at Marcos Juarez. At Río Cuarto, biocontrol effects were observed in several treatments at different intervals, with a mean DNA reduction of 88·7% for F. graminearum and F. avenaceum, and 100% reduction for F. verticillioides in two treatments after 180 days. Populations of F. avenaceum and F. verticillioides were stable; meanwhile, F. graminearum population levels varied during the first 90 days, and low levels were observed after 180 days. The other pathogens were not detected. The study showed that wheat stalks were important reservoirs for F. avenaceum and F. verticillioides populations but less favourable for F. graminearum survival. Clonostachys rosea (strain 1457) showed potential to reduce the Fusarium spp. on wheat stalks. © 2012 The Authors Plant Pathology © 2012 BSPP. Source

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