Echter Mehltau an Petersilie – Erarbeitung von Screeningmethoden für die Resistenzzüchtung

Powdery mildew occurs increasingly on parsley during hot summer periods, which has already become the main problem in some cultures when potted. Therefore a screening system of parsley is being elaborated in a cooperation project to be able to check breeding material for resistance and develop varieties resistant to powdery mildew. The project aims to find a screening system well practicable under greenhouse conditions for a multitude of breeding material. This requires both finding optimal conditions as well as climatic factors for best infection and development of the pathogen and simple rating methods. Investigations into sporulation, germination of spores, and incubation period have revealed that they are influenced by temperature and relative humidity. 25 °C and 70 % rf have proved to be the best conditions for powdery mildew to develop most effectively. Selecting aggressive isolates is another important impact factor for screening system methods. A collection of 16 isolates sent in from all over Germany could not only show their exclusive affiliation to the genus Erysiphe but also their differences in aggressiveness. This will support an effective selection of isolates for the screening system. The remaining year of the project will see comparative studies of the aggressive isolates on 20 varieties in greenhouse and field trials to evaluate the method. Rating methods applied so far will be optimized to detect differences in the susceptibility to powdery mildew most clearly

Falscher Mehltau an Gurke - Regulierung durch gezielte Klimaführung und Sortenwahl im Unterglasanbau

Pseudoperonospora cubensis (downy mildew) is an aggressive fungal pathogen of cucumber. In 2007, glasshouse experiments with organically grown cucumber (´Airbus`, ´Juliandra`) were performed to investigate the effects of a climate strategy “conventional” versus “dehumidified” on the development of the downy mildew epidemic. In both climate strategies the commanding variable for ventilation is the temperature; in the strategy “conventional” the established set point for ventilation is 22 °C, whereas in the climate strategy “dehumidified” the set point for ventilation varies from 18 °C to 23.5 °C, depending on the humidity. The results show that the climate “dehumidified” lowers the occurrence of downy mildew significantly

Entwicklung eines biologischen Pflanzenschutzmittels aus Süßholz zur Anwendung an Freilandgemüse

The plant extract from Glycyrrhiza glabra (liquorice) has a proven efficacy against Oomycetes in several vegetable crops under controlled conditions (greenhouse), however the liquorice extract shows varying efficacy when applied in the field. Therefore, a joint project funded by the Federal Institute for Agriculture and Food (Bundesanstalt für Landwirtschaft und Ernährung, BLE) aims to develop a plant protection product based on liquorice extract, which is highly effective in the field against Pseudoperonospora cubensis and Phytophthora infestans. Semi-field systems in cucumber and tomato have been established to test novel extract formulations on rainfastness and UV stability as well as on application parameters to maximize disease control. The results of three selected liquorice extract formulations demonstrate the effects of simulated rain and sun exposure on the biological activity in the semi-field systems. None of the tested formulations proved efficiently stable to rain and sun exposure. In addition, first results of a cucumber field trial will be presented. The testing for more stable liquorice extract formulations will be continued

Untersuchung von Salatsorten/-linien auf Feldresistenz gegenüber Falschem Mehltau

Eleven lettuce cultivars were tested for field resistance against Bremia lactucae. Although the presence of a large number of physiological races of Bremia lactucae was evidenced to be present in various German regions, preliminary results show two lettuce cultivars with a promisingly low susceptibility to downy mildew in three different locations

Falscher Mehltau an Gurken – Regulierungsmöglichkeiten im ökologischen Freilandgemüseanbau und unter Glas

To increase the yield of organically grown cucumber a lot of investigations were carried out in the last years. The influence of sowing and planting was compared and the susceptibility of different varieties as well as the influence of plant extracts was investigated in field trials. Planting resulted in an earlier harvest with a higher yield. Further effort in breeding resistant varieties with higher yield is needed. Also, the efficacy of plant strengthening products and plant extracts must still be improved. Regulation by specific climate strategy under glass was successful to avoid or delay the infection with Pseudoperonosproa cubensis

Solid-Phase Extraction of Aquatic Organic Matter: Loading-Dependent Chemical Fractionation and Self-Assembly

Dissolved organic matter (DOM) is an important component in marine and freshwater environments and plays a fundamental role in global biogeochemical cycles. In the past, optical and molecular-level analytical techniques evolved and improved our mechanistic understanding about DOM fluxes. For most molecular chemical techniques, sample desalting and enrichment is a prerequisite. Solid-phase extraction has been widely applied for concentrating and desalting DOM. The major aim of this study was to constrain the influence of sorbent loading on the composition of DOM extracts. Here, we show that increased loading resulted in reduced extraction efficiencies of dissolved organic carbon (DOC), fluorescence and absorbance, and polar organic substances. Loading-dependent optical and chemical fractionation induced by the altered adsorption characteristics of the sorbent surface (styrene divinylbenzene polymer) and increased multilayer adsorption (DOM self-assembly) can fundamentally affect biogeochemical interpretations, such as the source of organic matter. Online fluorescence monitoring of the permeate flow allowed to empirically model the extraction process and to assess the degree of variability introduced by changing the sorbent loading in the extraction procedure. Our study emphasizes that it is crucial for sample comparison to keep the relative DOC loading (DOCload [wt %]) on the sorbent always similar to avoid chemical fractionation

Downy mildew of organically grown cucumbers in the greenhouse – differences in susceptibility of varieties?

Der Falsche Mehltau (Pseudoperonospora cubensis) an Gurken stellt einen limitierenden Faktor für den ökolo­gischen Anbau von Schlangengurken unter Glas dar. Auf dem Markt angebotene Sorten weisen unterschiedliche Anfälligkeiten für Echten Mehltau auf. Über die Anfälligkeit für Falschen Mehltau liegen jedoch derzeit keine Informationen vor. Mit dem Ziel, Unterschiede in der Anfälligkeit der Sorten für Falschen Mehltau zu benennen, wurde ein ausgewähltes Sortiment von 20 marktgängigen Schlangengurkensorten im Gewächshaustest vergleichend geprüft. Dabei zeigte sich, dass alle Sorten anfällig für Falschen Mehltau waren; einige Sorten zeigten jedoch einen etwas geringeren Befall als andere. Momentan stellt die Sortenwahl kein geeignetes Instrument dar, um den Befall mit Falschem Mehltau deutlich zu redu­zieren. Um für die Praxis relevante Empfehlungen aussprechen zu können, sind weiterführende Untersuchungen in Zusammenhang mit den Ertragsdaten notwendig.    Dowy mildew (Pseudoperonospora cubensis) is one of several diminishing factors of organically grown cucumbers in the greenhouse. Varieties available on the market exhibit different degrees of susceptibility to powdery mildew while little is known about susceptibility to downy mildew. With the objective to find differences in the degree of susceptibility 20 selected varieties disposable on the market were tested and compared. The results revealed that all varieties were susceptible, but at several varieties showed a lower severity of the disease. Selecting varieties thus does not constitute a suitable instrument to reduce the infestation with downy mildew to a considerable extent as for their yield. To publish recommendations for growers a lot of work is to be done especially disease severity associated with yield.   &nbsp

Diclofenac does not interact with codeine metabolism in vivo: A study in healthy volunteers

BACKGROUND: Previously, we have demonstrated a marked inhibition of codeine glucuronidation by diclofenac in human liver tissue homogenate. We therefore aimed to investigate whether diclofenac inhibits glucuronidation of codeine also in vivo in healthy volunteers. METHODS: In a randomised, placebo-controlled, double-blind, cross-over study, 12 healthy volunteers received a singe of 100 mg codeine phosphate plus 50 mg diclofenac sodium or codeine phosphate plus placebo. Over a 36 hour period serum concentrations of codeine and its metabolites as well as urinary excretion were analysed using LC-mass spectrometry. Side effects were recorded and analgesic efficacy was determined using the cold pressor test (0–6 h). RESULTS: A single dose of diclofenac did not alter the formation of codeine-6-glucuronide in healthy volunteers. Metabolic clearance of codeine to morphine was not affected by diclofenac. In terms of side effects, both treatments were well tolerated. Diclofenac did not significantly influence the analgesic effects of codeine in the cold pressor test. CONCLUSIONS: In contrast to recent in vitro data, a single oral dose of diclofenac did not alter the glucuronidation of codeine in healthy volunteers

Solution Structure of Human Proguanylin: The role of a hormone prosequence

The endogenous ligand of guanylyl cyclase C, guanylin, is produced as the 94-amino-acid prohormone proguanylin, with the hormone guanylin located at the COOH terminus of the prohormone. The solution structure of proguanylin adopts a new protein fold and consists of a three-helix bundle, a small three-stranded {beta}-sheet of two NH2-terminal strands and one COOH-terminal strand, and an unstructured linker region. The sequence corresponding to guanylin is fixed in its bioactive topology and is involved in interactions with the NH2-terminal {beta}-hairpin: the hormone region (residues 80–94) partly wraps around the first 4 NH2-terminal residues that thereby shield parts of the hormone surface. These interactions provide an explanation for the negligible bioactivity of the prohormone as well as the important role of the NH2-terminal residues in the disulfide-coupled folding of proguanylin. Since the ligand binding region of guanylyl cyclase C is predicted to be located around an exposed {beta}-strand, the intramolecular interactions observed between guanylin and its prosequence may be comparable with the guanylin/receptor interaction

Süßholz (Glycyrrhiza glabra) - Extrakt zur Regulierung von Falschem Mehltau im Öko-Gemüseanbau

A raw extract of licorice (Glycyrrhiza glabra) was tested against downy mildew in vegetables under semi-commercial conditions. In two greenhouse trials in cucumber, efficacies of ca. 70% were achieved (3% extract concentration) in either 7 or 10-11 day application intervals. Under open field conditions, weekly treatments resulted in ca. 2 week retardation of disease. In open field trials in lettuce, efficacies after weekly application of 5% G. glabra extract were variable, depending on disease pressure. In contrast, on lettuce seedlings in climate chambers, the extract reduced disease incidence of Bremia lactucae by 66 to 100%. In onion, applications of the extract at 6% concentration failed to control Peronospora destructor, despite of high efficacies under controlled conditions in the greenhouse. Overall, the G. glabra raw extract was highly effective in protected vegetables. Under field conditions low efficacies were most likely due to reduced rain fastness or UV-stability