Reactivity with legume lectins of three monoclonal antibodies made against the Lathyrus odoratus lectin

Three murine IgG1 monoclonal antibodies (MoAb) were produced against the glucose/mannose-specific two-chain mitogen from seeds of Lathyrus odoratus (sweet pea) belonging to the Vicieae tribe of the Leguminosae family. Their antigenic specificities were tested against subunits of two-chain and one-chain legume lectins separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and electrotransferred to nitrocellulose filters. Different binding to native and detergent-treated lectins in dot-blots indicated that two of the antibodies bound to conformational epitopes which by immunoblotting were shown to be expressed on the heavy subunits from all the five tested two-chain lectins and on the six one-chain lectins, including PHA (Phaseolus vulgaris) and Con A (Canavalia ensiformis). However, ELISA cross-inhibition studies showed that these two antibodies bound to different epitopes on the lectin molecules. The third MoAb reacted with a continuous epitope not revealed by classical taxonomy since only three of five heavy subunits of the two-chain lectins stained with the antibody. Comparison of the known amino-acid sequences of the chains indicates eight positions as possible binding sites for this antibody.     

Influence of N-fertilization and Fungicide Strategies on Fusarium Head Blight Severity and Mycotoxin Content in Winter Wheat

Nitrogen (N) fertilization and fungicide applications are still subject to discussion concerning the influence on Fusarium head blight (FHB) and related mycotoxin accumulation. Field studies were made in 2000–2001 and 2001–2002 to investigate the effect of two N‐rates and 11 plant protection treatments on FHB severity and the content of FHB‐related mycotoxins, namely deoxynivalenol (DON) and zearalenone (ZEA) under conditions of natural infection. The treatments applied can be summarized as (i) an integrated approach using a decision support system, (ii) the use of two plant strengtheners, Bion^® (benzo [1,2,3]thiadiazole‐7‐carbothioic acid S‐methyl‐ester, BTH) and a compound based on the biomass of the cyanobacterium Spirulina platensis, (iii) the use of plant strengtheners in combination with a broad‐spectrum fungicide and (iv) common fungicide strategies against foliar diseases. Fusarium infections as well as the analysed mycotoxins were observed at low levels in both years. Disease severity was significantly increased by conventional N‐fertilization only in 2001. Neither FHB severity nor mycotoxin accumulation was significantly influenced by any of the treatments, although treatments without fungicides appeared to lead to lower disease severities. In 2002, there was a tendency towards higher disease severities when common fungicide strategies were applied. Mycotoxin contamination was found in grain samples from both years. In 2001 DON was mainly traceable, whereas in 2002 ZEA was also detected. Mycotoxin contamination was influenced by N‐fertilization rather than by the treatments. In 2001, the DON content was significantly increased due to the conventional N‐supply. Our results indicate that less intensive fungicide strategies, including plant strengtheners, are no worse than common fungicide strategies under conditions of low FHB severity and mycotoxin accumulation. Immoderate N‐fertilization however, can increase mycotoxin levels significantly even under conditions unfavourable for Fusarium spp.