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Deoxynivalenol (DON), moniliformin (MON) and zearalenone (ZON) are the most important mycotoxins detected in Fusarium infected wheat grains in Austria. Our goal was to identify an evaluation method for Fusarium head blight (FHB) symptoms, which is closely related to the toxin content in grains of artificially inoculated wheat genotypes. In total 108 wheat lines with varying FHB resistance were treated with F. culmorum(DON producer), F. avenaceum(MON producer) or F. graminearum(ZON producer). Several FHB evaluation methods were investigated and the data were correlated with the mycotoxin content of the grains. Data on the visual scores of the FHB development in the field, percentage of Fusarium damaged kernels and specific grain weight showed acceptable correlations with the DON content (r=0.75-0.81). MON contamination was closely related to the percentage of Fusarium damaged kernels (r=0.70). No suitable method was identified to predict ZON concentrations. Only in grain samples of highly resistant genotypes consistently a low ZON content was measured.

Abstract:  Fusarium head blight (FHB or scab) caused by Fusarium spp. is a widespread disease of cereals causing yield and quality losses and contaminating cereal products with mycotoxins. The breeding of resistant varieties is the method of choice for controlling the disease. Unfortunately, the genetic basis of scab resistance is still poorly understood. We present the results of a back-cross reciprocal monosomic analysis of FHB resistance using the highly resistant Hungarian winter wheat line ‘U-136.1’ and the highly susceptible cultivar ‘Hobbit-sib’. Resistance testing was performed in a field trial artificially inoculated with a Fusarium culmorum conidial suspension. Five hemizygous families containing ‘U-136.1’ chromosomes 6B, 5A, 6D, 1B, and 4B had a visually reduced spread of infection compared to lines having the ‘Hobbit-sib’ chromosome. Chromosome 2B from ‘U-136.1’ had an increased spread of infection. The critical chromosomes controlling seed weight were 6D, 3B, 5A, and 6B while those controlling deoxynivalenol (DON) content were homoeologous groups 2 and 6, although the latter effects were not significant due to a high coefficient of variation. Results from this and other studies show that chromosomes 6D, 6B, 5A, 4D, and 7A have frequently been associated with scab resistance in a number of wheat cultivars. Research groups now attempting to map scab resistance in wheat using markers should pay special attention to the above-mentioned chromosomes.

The aim of this work was to identify a disease parameter with which the mycotoxin content in kernels of artificially inoculated wheat genotypes can be predicted for breeding purposes. In total 108 winter and spring wheat genotypes, the resistance of which varied from highly resistant to very susceptible, were artificially inoculated with a F. culmorumisolate known to produce large amounts of deoxynivalenol (DON). Several field and laboratory parameters were investigated and the data were correlated with the DON content of the harvested wheat kernels. Correlation coefficients varied (in absolute values) from 0.33 to 0.81. It is concluded that for practical breeding purposes visual scores of the disease on the field (e.g. the area under the disease progress curve: r = 0.81) or the percentage of bleached kernels in the harvested samples (r = 0.76) give a good estimation of the DON content for a reasonable labour input.