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Protective action of sulfoethyl glucan (SEG), a derivative of the cell wall glucan prepared from the baker's yeast Saccharomyces cerevisiae, was investigated in the maize seedlings infected by a plant pathogen Fusarium verticillioides (Sacc.). Several markers were assayed with the SEG addition and in the control experiments. Two evaluations were performed on the 7th and the 14th days. Addition of SEG led to the increased productivity parameters of the infected plants and maintained them at the level of non-infected plants during the 14 days of experiment. After seven days of cultivation, concentration of fusaric acid (=5-butylpyridine-2-carboxylic acid; FA) decreased in all infected plants cultivated in the presence of SEG when compared to that detected in the infected plants grown in the absence of SEG. After 14 days of cultivation, polysaccharide addition resulted in the reduction of FA concentration almost to 75% in comparison to the infected plants grown without polysaccharide addition. In the experiment, when exogenous FA was added to the growth medium, its concentration decreased up to 60% in the presence of SEG. Thus, it is feasible to assume that SEG binds and adsorbs FA, and, in this way, reduces its content and exerts protective action in plants against its toxic effect.

Roots of maize seedlings (cv. Pavla) infested by Fusarium verticillioides (10 5 /ml) were cultivated on Murashige-Skoog medium (MSM, Sigma, USA) containing CaCl 2 , IAA and kinetin. Simultaneously, a strain of the antagonistic fungus Trichoderma sp. and a sulphoethyl glucan (SEG) isolated from the cell walls of Saccharomyces cerevisiae, were added. Two evaluations (on 7 and 14 days) were done. Productivity parameters of leaves and roots (fwt, dwt, and length), disease severity index (DSI) and fusaric acid (FA) concentration were evaluated. Both Trichoderma sp. and SEG increased productivity parameters of plants in infested variants and maintained it on the level of control plants during 14 days of experiment. Trichoderma reduced the DSI, while SEG increased it. DSI correlated with FA concentration. A�er seven days of cultivation concentration of FA was lower in all infected variants cultivated concomitantly with agents, compared with the one without them. A�er 14 days of cultivation both agents reduced the concentration of FA up to 50% to the non-measurable concentration in variant with Trichoderma. In variant with positive control, where FA was added to SEG, its concentration decreased up to 30%. 1. growth medium, control 2. F. verticillioides 10 5 /ml spore concentration 3. F. verticillioides 10 5 /ml spore concentration with Trichoderma sp.10 6 /ml 4. F. verticillioides 10 5 /ml spore concentration with 0.025% SEG 5. Trichoderma sp. 10 6 /ml 6. 0.025% SEG After 7 days of cultivation as a toxin positive control 7) variant with 0.025% SEG and fusaric acid (FA) in a concentration 8.40 µg/ml was added according to the average level evaluated in situ samples (Nadubinská et al. 2002).In each variant 15 three-days-old seedlings were inserted, in two repetitions. All variants had volume of 200 ml and after 7 days of cultivation a fresh solution of MSM was added to maintain constant volume. We used the strain of F. verticillioides which produced FA in vitro. Plants were cultivated hydroponically in a special room under controlled conditions at temperature of 21/15°C day/night and 16/8 h photoperiod provided by white fluorescent lights, irradiance 180 µmol/m 2 /s, day/night relative humidity 80/60%.Evaluation of experimental results. After 7 and 14 days, the roots were separated from the leaves and evaluated for the degree of infestation, the content of FA, and productivity parameters: fresh weight (fwt), dry weight (dwt), and length. The longest roots and leaves were measured in each plant. To determine the dry weight, leaves and roots were dried separately at 105°C to constant weight. The data were subjected to standard statistical analysis, using SAS program 6. 08 (1990). The means where applicable were tested for significant differences, using the LSD (P < 0.05).Disease severity. The disease severity index (DSI) was rated on the 14 th day using a scale according to Kroon and Elgersma (1993) in plants of each treatment, using a 0 -5 disease index, where 0 indicated a healthy plant; 1 implied penalty of leave...

Fusaric acid (FA) is one of the most important secondary metabolites produced by <I>Fusarium oxysporum</I> (Schlecht) (FO), <I>F. solani</I> (Mart.) Appel & Wollenweber, and <I>F. moniliforme</I> Sheldon. It is toxic to humans, many plants, and microorganisms and it enhances the toxicity of fumonisin and trichothecene. A simple and rapid method for fusaric acid (FA) screening in <I>Fusarium</I> isolates was developed. In this study, several strains of <I>Fusarium oxysporum</I> were tested for their ability to produce FA by using a suitable race of <I>Bacillus subtilis</I> as the bioassay. A modified method using small agar blocks with the fungus producing FA was applied in the screening test. FA standard and <I>F. culmorum</I> were used as controls. The experimental <I>F. oxysporum</I> isolates and FA standard produced transparent zones on the plates with <I>Bacillus subtilis</I>. The differences in size of the transparent zones corresponded to the quantity of FA when thin-layer chromatography was used.

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