Fungal diversity and natural occurrence of fusaproliferin,beauvericin, deoxynivalenol and nivalenol in wheat cultivated in Santa Fe Province,Argentina

The Fusarium diversity and the mycobiota associated with moldy wheat kernels from Santa Fe province, Argentine, was assessed. The wheat cultivated area in Santa Fe province is divided according to agrometeorological conditions into two zones: Zone I (north-central) and Zone II (south). The natural occurrence of Fusarium toxins BEA, FUP, DON and NIV was also determined. Cladosporium was the most abundant of the 19 genera identified, followed by Fusarium, Phoma and Alternaria. Zone II shows a predominance of F. graminearum and F. culmorum. In Zone I, DON was present in 13/32 samples (range 0.43–3.60 mg kg⁻¹) and NIV in 6/32 samples (range 0.11–0.40 mg kg⁻¹). In zone II, DON was found in 11/21 samples (range 0.57–9.50 mg kg⁻¹) and NIV in 4/21 samples (range 0.10–0.60 mg kg⁻¹). BEA and FP were not detected in both zones.     

Mycotoxins and fungi in wheat harvested during 1990 in test plots in the state of São Paulo,Brazil

Wheat from two cultivars with contrasting characteristics were harvested in ten experimental plots located in wheat producing areas of the State of São Paulo, Brazil. The samples (10 of each cultivar) were analyzed by a gaschromatographic method for deoxynivalenol (DON), nivalenol (NIV), diacetoxyscirpenol (DAS), toxins T-2 (T-2) and HT-2, T-2 tetraol, T-2 triol, and by a thin-layer chromatographic method for zearalenone (ZEN), aflatoxins B₁, B₂, G₁, G₂, ochratoxin A and sterigmatocystin. No mycotoxins were detected in 13 samples. DON was found in four samples (0.47–0.59 µg/g), NIV in three samples (0.16–0.40 µg/g), T-2 in two samples (0.40, 0.80 µg/g), DAS in one sample (0.60 µg/g), and ZEN in three samples (0.04–0.21 µg/g). The wheat samples were also examined for the incidence of fungi.Alternaria, Drechslera, Epicoccum andCladosporium were the prevailing genera. Among theFusarium spp.,F. semitectum was present in 19 samples andF. moniliforme in 18 samples. NoF. graminearum was isolated in the samples.Abbreviations DAS diacetoxyscirpenol - DON deoxynivalenol - NIV nivalenol - T-2 T-2 toxin - ZEN zearalenone     

Zearalenone, deoxynivalenol and fumonisins in mixed-feed for laying hens

Fusarium toxins are secondary metabolites produced byfungi of these genera in many commodities under certain conditions. A study was carried out to investigate the co-occurrence of zearalenone (ZEN), deoxynivalenol (DON) and fumonisins (FB₁ and FB₂) in 52 samples of mixed-feed for poultry contaminated withFusarium verticillioides. The zearalenone and deoxynivalenol were checked using immunoaffinity column and the extraction of fumonisin was performed by strong anion exchange (SAX) solid phase column. Detection and quantification were determined by high performance liquid chromatography (HPLC). The limit of detection was 5 μg/kg for ZEN, 100 μg/kg for DON and 50 and 100 μg/kg for FB₁ and FB₂ respectively.Fusarium toxins were detected in 20 samples. Sixteen samples were positive for ZEN (30.7%) presenting levels that ranged from 7.4 μg/kg to 61.4 μg/kg (mean=27.0 μg/kg). 13.5% of the samples presented contaminations of DON, with levels ranging from 100.0 μg/kg to 253 μg/kg (mean=l18.07 μg/kg). FB₁ was detected in 19.2% of samples, with levels ranging from 50.0 μg/kg to 110.0 μg/kg (mean=73.6 μg/kg). FB2 was not detected in any sample. In positive samples simultaneously contamination with two or three mycotoxins were detected in 9 of them (17.3%).     

A case of sporotrichosis caused by two genetically differentSporothrix schenckii strains

A survey for the natural occurrence of Fusarium mycotoxins, deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN), in Dutch cereals (totaling 29 samples) harvested in 1984/1985, showed that 90%, 79% and 62% of samples were contaminated with DON, NIV and ZEN, respectively. Average contents (ng/g) in the total of positive samples were 221 (DON), 123 (NIV) and 61 (ZEN). Among the cereals examined, the highest concentrations (ng/g) was 3198 (DON), 1875 (NIV) and 677 (ZEN) in a yellow corn sample for animal feed. The results of this survey show that Dutch cereals were relatively significantly contaminated with Fusarium mycotoxins.     

A case report on a minor contamination of nivalenol in cereals harvested in Canada

An investigation for the occurrence of nivalenol (NIV), deoxynivalenol (DON) and zearalenone (ZEN) in cereals (ten wheat, one rye and one corn) harvested in Canada have been carried out using a procedure, which is rapid and sensitive for Fusarium mycotoxins. NIV, DON and ZEN were detected in 4, 9 and 9 out of ten wheat samples, and their average levels in the positives were 23 ng/g, 1257 ng/g and 9 ng/g, respectively. One rye and one corn were also contaminated with a minor amount of NIV. This is the first evidence for the natural occurrence of NIV in cereals grown in Canada, though its level was far less than DON.     

Aflatoxin B1, zearalenone and deoxynivalenol production by Aspergillus parasiticus and Fusarium graminearum in interactive cultures on irradiated corn kernels

The influence of inoculum size in the production of aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON) was determined when Aspergillus parasiticus NRRL 3000 and Fusarium graminearum ITEM 124 were cultured alone and in pairs on irradiated corn kernels at 28 °C and 0.97 water activity (aw). The highest levels of AFB1 produced by A. parasiticus were produced at the lowest levels of the inoculum (103 spores/ml). No significant differences were observed in ZEN and DON production at any inoculum level during the experimental period. When A. parasiticus was co-inoculated with F. graminearum both to the same inocula (106 spores/ml), AFB1 inhibition percentage were 60, 72 and 56% at 10, 20 and 35 days of incubation respectively, while at 106 spores/ml the percentages of inhibition were 34, 84 and 93% at 10, 20 and 35 days. In the mixture cultures A. parasiticus 103 × F. graminearum 106 spores/ml the percentage of inhibition of AFB1 oscillated in 99% during all the incubation. In the interaction A. parasiticus 106 spores/ml × F. graminearum 103 spores/ml the accumulation of AFB1 decreased in 80, 94 and 86% at 10, 20 and 35 days of incubation respectively. In single culture F. graminearum was inoculated with 10³ or 106 spores/ml and the highest levels of ZEN and DON were detected at 35 days of incubation. The levels oscillated in 538–622 μg/kg for ZEN and 870–834 μg/kg for DON respectively. In paired cultures there were no significant differences in the levels regardless of the spore concentrations during the incubation time. This revised version was published online in June 2006 with corrections to the Cover Date.     

Trichothecenes and Mycoflora in Wheat Harvested in Nine Locations in Buenos Aires Province, Argentina

A total of 120 freshly harvested wheat samples from the 2004 season in nine locations from Northern Buenos Aires Province, Argentina, were analysed for trichothecene natural occurrence and associated mycoflora, and for determining the influence of commonly used fungicide field treatment and the cultivar type on trichothecene contamination. The trichothecenes T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), diacetoxyscirpenol (DAS), nivalenol (NIV), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON) and 15-acetyldeoxynivalenol (15-ADON) were analysed by gas chromatography and electron capture detection. Detection limits ranged from 4 to 20 μg/kg. The isolation frequencies of species were calculated. Alternaria alternata, Fusarium graminearum, Fusarium poae and Fusarium semitectum were the predominant fungal species identified as endogenous mycoflora. The type of cultivar and the fungicide field treatment did not affect significantly the trichothecene contamination. The trichothecenes type A detected were HT-2 and T-2 triol toxins and the type B were DON, NIV and 3-ADON. Based on 120 samples the incidences were 21.7% for 3-ADON, 22.5% for HT-2, 27.5% for T-2 triol and 85% for DON. NIV was confirmed in one sample. Mean levels of trichothecene positive samples were between 7 and 2788 μg/kg.     

Occurrence ofAlternaria andFusarium mycotoxins in winter wheat from domestic crop in year 2003

The aim of this study was a monitoring of the occurrence ofAlternaria andFusarium mycotoxins in winter wheat from domestic crop in the year 2003. Altenuene was determined in 56 (100%) samples of winter wheat, range 14.5–41 μg/kg, mean 25 μg/kg. Alternariol was determined in 16 (28.6%) samples of winter wheat, range 6.3–22.1 μg/kg, mean 5.7 μ/kg. DON was determined in 42 (100%) samples of winter wheat, range 250–3500 μg/kg, mean 330 μg/kg. T2-toxin was determined in 42 (100%) samples of winter wheat, range 25–337 μg/kg, mean 99 μg/kg. ZEA was not determined in samples of winter wheat. Presented at the 26^th Mykotoxin-Workshop in Herrsching, Germary, May 17–19, 2004 Financial support. Supported (one part of experiments, the determination of Fusarium mycotoxins) by the Ministry of Agricu ture of the Czech Rebublic (Propect No QF3121)     

First survey on the natural occurrence of Fusarium mycotoxins in Bulgarian wheat

Wheat for human consumption (140 samples) was collected after harvest from all regions of Bulgaria. The 1995 crop year was characterized by heavy rainfall in the spring and summer months. The internal mycoflora of wheat samples was dominated by Fusarium spp. and Alternaria spp., and storage fungi were rarely present. The samples were analysed for contamination with Fusarium mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), using enzyme immunoassay methods. DON and ZEA were the predominant toxins, with a contamination frequency of 67% and 69%, respectively. The average levels of these toxins in positive samples were 180 g/kg (DON) and 17 g/kg (ZEA), maximum concentrations were 1800 g kg^–1 and 120 g kg^–1, respectively. Acetyl derivatives of DON, namely 3-AcDON and 15-AcDON, were found in 2.1 % and 0.7% of the samples, at at maximum level of about 100 g kg^–1. Only one sample was positive for T-2 (55 g/kg), DAS was not detected. This is the first report about the natural occurrence of a range of Fusarium mycotoxins in wheat for human consumption in Bulgaria.Abbreviations 3-AcDON 3-acetyldeoxynivalenol - 15-AcDON 15-acetyldeoxynivalenol - DAS diacetoxyscirpenol - DON deoxynivalenol - EIA enzyme immunoassay - T-2 T-2 toxin - ZEA zearalenone     

Critical Levels of Selenium in Different Crops Grown in an Alkaline Silty Loam Soil Treated with Selenite-Se

Critical levels of selenium in raya (Brassica juncea Czern L.), maize (Zea mays L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.) were worked out by growing these crops in an alkaline silty loam soil treated with different levels of selenite-Se ranging from 1 to 25 μg g⁻¹ soil. Significant decrease in dry matter yield was observed above a level of 5 μg Se g⁻¹ soil in raya and maize; 4 μg Se g⁻¹ soil in wheat and 10 μg Se g⁻¹ soil in rice shoots. The critical level of Se in plants above which significant decrease in yield would occur was found to be 104.8 μg g⁻¹ in raya, 76.9 μg g⁻¹ in maize, 41.5 μg g⁻¹ in rice and 18.9 μg g⁻¹ in wheat shoots. Significant coefficients of correlation were observed between Se content above the critical level and dry matter yield of raya as well as rice (r = −0.99, P ≤ 0.01), wheat (r = −0.97, P ≤ 0.01) and maize ((r = −0.96, P ≤ 0.01). A synergistic relationship was observed between S and Se content of raya (r = 0.96, P ≤ 0.01), wheat (r = 0.89, P ≤ 0.01), rice (r = 0.85, P ≤ 0.01) and maize (r = 0.84, P ≤ 0.01). Raya, maize and rice absorbed Se in levels toxic for animal consumption (i.e. > 5 mg Se kg⁻¹) when the soil was treated with more than 1.5 μg Se g⁻¹. In case of wheat, application of Se more than 3 μg g⁻¹ soil resulted in production of toxic plants.     

A survey on the occurrence of mycotoxins in wheat and maize from western Romania

Samples of wheat (n = 25) and maize (n = 30) for animal consumption, collected in 1997 after harvest from western Romania, were analyzed by enzyme immunoassays for mycotoxin contamination. Toxins analyses included deoxynivalenol (DON), 3-acetylDON, 15- acetylDON, fusarenone X (FX), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), zearalenone (ZEA), fumonisin B1 (FB1), aflatoxin B1 (AFB1), ochratoxin A (OA), and citrinin (CT). DON and acetylDONs were the major contaminants in wheat (100%) and maize (46%). Median values for DON, 3-acetylDON, and 15-acetylDON were 880 μg kg-1, 66 μg kg- 1, and 150 μg kg-1 in wheat, and 890 μg kg-1, 180 μg kg-1, and 620 μg kg- 1 in maize, respectively. Additionally, 3,15-diacetylDON was detected in some samples by HPLC-EIA analysis. All samples were negative for FX (<150 μg kg-1). T-2 was found in wheat (n = 6) and maize (n = 1) at levels between 13 and 63 μg kg- 1. DAS (2.6 μg kg-1) was found in one maize sample. ZEA occurred in all wheat and in four maize samples, median values were 10 μg kg-1 and 250 μg kg-1, respectively. One maize sample contained FB1 (140 μg kg-1). All samples were AFB1-negative (<4 μg kg-1). OA was found in one wheat sample (37 μg kg- 1), CT was found in one maize sample (580 μg kg- 1). This first reported natural occurrence of a range of mycotoxins in Romanian feeding stuff shows that DON and acetyl DONs may be present at levels which may affect animal production. This revised version was published online in June 2006 with corrections to the Cover Date.     

Co-occurrence of mycotoxins in swine feed produced in Portugal

A total of 404 samples of commercial swine feed from Portugal feed mills were analysed by HPLC methods for the presence of mycotoxins: 277 samples of feed for fattening pigs were analysed for ochratoxin A (OTA), zearalenone (ZEA), and deoxynivalenol (DON), and 127 samples of feed for sows were analysed for ZEA and fumonisins (FB₁ + FB₂). Concerning feed for fattening pigs, 21 (7.6%) samples were positive for OTA, (2–6.8 μg/kg), 69 (24.9%) were positive for ZEA (5–73 μg/kg), and 47 (16.9%) were positive for DON (100–864 μg/kg). In feed for sows, the results showed 29.9% of positive samples for ZEA (5–57.7 μg/kg) and 8.7% positive samples for FB₁ and FB₂ (50–391.4 μg/kg). Co-occurrence of DON/ZEA was found most frequently, but simultaneous contamination with OTA/ZEA and OTA/DON was also found.     

Genotypic variation in zinc efficiency and resistance to crown rot disease (Fusarium graminearum Schw. Group 1) in wheat

A crown rot disease in wheat caused by the fungusFusarium graminearum Schw. Group 1 is a widespread problem in chronically Zn-deficient Australian soils. A link between crown rot and Zn deficiency was established by Sparrow and Graham (1988). This paper reports a test of a further hypothesis, that wheat genotypes more efficient at extracting zinc from low-zinc soils are more resistant to infection by this pathogen. Three wheat cultivars (Excalibur, Songlen and Durati) of differential Zn efficiency were tested at three zinc levels (0.05, 0.5 and 2.0 mg Zn kg⁻¹ of soil) and three levels ofF. graminearum S. Group 1 inoculum (0.1 g and 0.3 g kg⁻¹ live chaff-inoculum and control having 0.1 g kg⁻¹ dead chaff inoculum). Six weeks after sowing dry matter production of shoots and roots was decreased byFusarium inoculation at 0.05 mg and 0.5 mg kg⁻¹ applied Zn.Fusarium inoculum at 0.1 g was as effective as 0.3 g kg⁻¹ for infection and decreasing dry matter. The infection at the basal part of culm decreased significantly by increasing the rate of Zn application. Excalibur, a Zn-efficient cultivar (tolerant to Zn deficiency) produced significantly more shoot and root dry matter, and showed less disease infection compared with Zn-inefficient cultivars (Durati and Songlen) at low (0.05 mg Zn kg⁻¹ soil) and medium (0.5 mg Zn kg⁻¹ soil) Zn fertilization rates. Higher rate of Zn fertilization (2.0 mg Zn kg⁻¹ soil) reduced the disease level in Durati to the level of Excalibur but the disease level of Songlen was still high, indicating its high Zn requirement and or sensitivity to crown rot. The data on Zn uptake show that Excalibur, being Zn-efficient, was able to scavenge enough Zn from Zn-deficient soil, we suggest that besides sustaining growth Excalibur was able to build and maintain resistance to the pathogen; inefficient cultivars needed extra Zn fertilization to achieve performance comparable to that of Excalibur. The present study indicates that growing Zn-efficient cultivars of wheat along with judicious use of Zn fertilizer in Zn-deficient areas where crown rot is a problem may sustain wheat production by reducing the severity of the disease as well as by increasing the plant vigour through improved Zn nutrition. ei]Section editor: R Rodriques-Kalana     

Natural and induced cadmium-accumulation in poplar and willow: Implications for phytoremediation

Potentially poplars and willows may be used for the in situ decontamination of soils polluted with Cd, such as pasturelands fertilised with Cd-rich superphosphate fertiliser. Poplar (Kawa and Argyle) and willow (Tangoio) clones were grown in soils containing a range (0.6–60.6 μg g⁻¹ dry soil) of Cd concentrations. The willow clone accumulated significantly more Cd (9–167 μg g⁻¹ dry matter) than the two poplar clones (6–75 μg g⁻¹), which themselves were not significantly different. Poplar trees (Beaupré) sampled in situ from a contaminated site near the town of Auby, Northern France, were also found to accumulate significant quantities (up to 209 μg g⁻¹) of Cd. The addition of chelating agents (0.5 and 2 g kg⁻¹ EDTA, 0.5 g kg⁻¹ DTPA and 0.5 g kg⁻¹NTA) to poplar (Kawa) clones caused a temporary increase in uptake of Cd. However, two of the chelating agents (2 g kg⁻¹ EDTA and 0.5 g kg⁻¹ NTA) also resulted in a significant reduction in growth, as well as abscission of leaves. If the results obtained in these pot experiments can be realised in the field, then a single crop of willows could remove over 100 years worth of fertiliser-induced Cd contamination from pasturelands. This revised version was published online in June 2006 with corrections to the Cover Date.     

Mycotoxins in laboratory rodent feed

Twenty-one batches of fixed-formula rodent diets from three feed manufacturers were tested for the presence of five mycotoxins: deoxynivalenol (DON), nivalenol (NIV), HT-2 toxin, T-2 toxin and ochratoxin A (OTA). Five batches were also tested for the presence of zearalenone (ZEN) and six batches for aflatoxins. Detectable levels of DON (up to 298 microg/kg), NIV (up to 118 microg/kg), OTA (up to 3.1 microg/kg) or ZEN (up to 26.7 microg/kg) were found in samples from all manufacturers. Three batches contained two (DON or NIV and OTA or ZEN) and one batch contained three (DON, OTA and ZEN) different mycotoxins. Aflatoxins, T-2 and HT-2 were not detected in any of the batches. The concentrations of mycotoxins detected in the feed were low, but indicated that feed ingredients, probably the cereal ingredients, were contaminated by mycotoxins. Since mycotoxins are known to have toxic and/or immunosuppressive effects, non-contaminated ingredients should be used for production of laboratory animal feed. The results imply that an improved quality control of ingredients used for laboratory rodent feed should be implemented.     

In vitro degradation of zearalenone by Bacillus subtilis

Zearalenone (ZEN) is a non-steroidal estrogen produced by many Fusarium species in cereals and other plants, and is frequently implicated in safety of foods and feeds. A ZEN-degrading microorganism has been isolated and identified as a Bacillus subtilis subspecies. It degraded 99% ZEN (1 mg kg⁻¹) in liquid medium after 24 h and more than 95% of ZEN (0.25 mg kg⁻¹) could be degraded after 48 h in a solid-state fermentation. This isolate can thus be used to decontaminate raw materials, like grains, to reduce the mycotoxin concentration.     

Biogeochemical conditions and ice algal photosynthetic parameters in Weddell Sea ice during early spring

Physical, biogeochemical and photosynthetic parameters were measured in sea ice brine and ice core bottom samples in the north-western Weddell Sea during early spring 2006. Sea ice brines collected from sackholes were characterised by cold temperatures (range −7.4 to −3.8°C), high salinities (range 61.4–118.0), and partly elevated dissolved oxygen concentrations (range 159–413 μmol kg⁻¹) when compared to surface seawater. Nitrate (range 0.5–76.3 μmol kg⁻¹), dissolved inorganic phosphate (range 0.2–7.0 μmol kg⁻¹) and silicic acid (range 74–285 μmol kg⁻¹) concentrations in sea ice brines were depleted when compared to surface seawater. In contrast, NH₄ ⁺ (range 0.3–23.0 μmol kg⁻¹) and dissolved organic carbon (range 140–707 μmol kg⁻¹) were enriched in the sea ice brines. Ice core bottom samples exhibited moderate temperatures and brine salinities, but high algal biomass (4.9–435.5 μg Chl a l⁻¹ brine) and silicic acid depletion. Pulse amplitude modulated fluorometry was used for the determination of the photosynthetic parameters F _v/F _m, α, rETR_max and E _k. The maximum quantum yield of photosystem II, F _v/F _m, ranged from 0.101 to 0.500 (average 0.284 ± 0.132) and 0.235 to 0.595 (average 0.368 ± 0.127) in the sea ice internal and bottom communities, respectively. The fluorometric measurements indicated medium ice algal photosynthetic activity both in the internal and bottom communities of the sea ice. An observed lack of correlation between biogeochemical and photosynthetic parameters was most likely due to temporally and spatially decoupled physical and biological processes in the sea ice brine channel system, and was also influenced by the temporal and spatial resolution of applied sampling techniques.     

Natural Occurrence of 16 Fusarium Toxins in Grains and Feedstuffs of Plant Origin from Germany

A total of 220 samples comprising cereals, cereal byproducts, corn plants and corn silage as well as non-grain based feedstuffs was randomly collected during 2000 and 2001 from sources located in Germany and analysed for 16 Fusarium toxins. The trichothecenes scirpentriol (SCIRP), 15-monoacetoxyscirpenol (MAS), diacetoxyscirpenol (DAS), T-2 tetraol, T-2 triol, HT-2 and T-2 toxin (HT-2, T-2), neosolaniol (NEO), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivealenol (15-ADON), nivalenol (NIV) and fusarenon-X (FUS-X) were determined by gas chromatography/mass spectrometry. Zearalenone (ZEA) and α- and β-zearalenol (α- and β-ZOL) were analysed by high performance liquid chromatography with fluorescence and UV-detection. Detection limits ranged between 1 and 19 μg/kg. Out of 125 samples of a group consisting of wheat, oats, corn, corn byproducts, corn plants and corn silage only two wheat samples did not contain any of the toxins analysed. Based on 125 samples the incidences were at 2–11% for DAS, NEO, T-2 Triol, FUS-X, α- and β-ZOL, at 20–22% for SCIRP, MAS, T-2 tetraol and 3-ADON, at 44–74% for HT-2, T-2, 15-ADON, NIV and ZEA, and at 94% for DON. Mean levels of positive samples were between 6 and 758 μg/kg. Out of 95 samples of a group consisting of hay, lupines, peas, soya meal, rapeseed meal and other oilseed meals, 64 samples were toxin negative. DAS, T-2 triol, NEO and FUS-X were not detected in any sample. The incidences of DON and ZEA were at 14 and 23% respectively, those of the other toxins between 1–4%, mean levels of positive samples were between 5 and 95 μg/kg.     

Studies on inositol-mediated expression of MAL gene encoding maltase and phospholipid biosynthesis in Schizosaccharomyces pombe

In this study, the effects of inositol addition on expression of the MAL gene encoding maltase and phosphatidylinositol (PI) biosynthesis in Schizosaccharomyces pombe (a naturally inositol-requiring strain) were examined. We found that specific maltase activity was at its maximum when the concentration of added inositol reached 6 μg ml⁻¹ in a synthetic medium containing 2.0% (w/v) glucose. When the concentration of added inositol was 1 μg ml⁻¹ in the medium, repression of MAL gene expression occurred at glucose concentration higher than 0.2% (w/v). However, when S. pombe was cultured in the synthetic medium containing 6 μg ml⁻¹, repression of maltase gene expression occurred only at initial glucose concentration above 1.0% (w/v). More mRNA encoding maltase was detected in the cells grown in the medium with 6 μg ml⁻¹ inositol than in those grown in the same medium with 1 μg ml⁻¹ inositol. These results demonstrate that higher inositol concentrations in the synthetic medium could derepress MAL gene expression in S. pombe. PI content of the yeast cells grown in the synthetic medium with 6 μg ml⁻¹ of inositol was higher than that of the yeast cells grown in the same medium with 1 μg ml⁻¹ of inositol. This means that PI may be involved in the derepression of MAL gene expression in S. pombe.     

Antifungal activity of methanol extracts from spikes of Triticum spelta and Triticum aestivum genotypes differing in their response to Fusarium culmorum inoculation

The total concentrations of free phenolic compounds and peroxidase were determined in spikes (collected at the flowering stage) of some spelt and common wheat cultivars differing in their response to F. culmorum infection. The antifungal activity of methanol extracts obtained from spikes was also evaluated. The tested genotypes differed significantly in their response to inoculation. The most resistant were Torka and Zebra among common wheat cultivars, and Weisser Grannenspelz among spelt cultivars. The average content of free phenolic compounds in spikes of spelt and common wheat was 1246.56 μg g⁻¹ and 1236.58 μg g⁻¹, respectively. The cultivars whose spikes contained the largest amounts of phenols showed the weakest response to F. culmorum infection. No significant differences were observed with regard to peroxidase content, which was 5.22 U g⁻¹ in common wheat spikes and 5.14 U g⁻¹ in spelt spikes. Methanol extracts from spikes of all wheat cultivars contained antifungal substances. The extracts from spelt spikes inhibited the growth of F. culmorum on PDA to a lesser degree than the extracts from common wheat spikes. This corresponds to the results of field trials, in which T. spelta generally exhibited a stronger response to F. culmorum infection than common wheat. The high correlation (r = 0.816) between mycelium growth inhibition on the medium and F. culmorum infection indicates that an evaluation of the antifungal activity of extracts from spikes may be used for the selection of breeding materials directed towards increased resistance to Fusarium head blight.