Fusarium head blight (FHB, scab) is a fungal disease of wheat and other small cereals that is found in both temperate and semi-tropical regions. FHB causes severe yield and quality losses, but the most-serious concern is the possible mycotoxin contamination of cereal food and feed. Breeding for FHB resistance by conventional selection is feasible, but tedious and expensive. This study was conducted to identify and map DNA markers associated with FHB resistance genes in wheat. A population of 364 F(1)-derived doubled-haploid (DH) lines from the cross 'CM-82036' (resistant)/'Remus' (susceptible) was evaluated for Type II resistance (spread within the spike) during 2 years under field conditions. Marker analysis was performed on 239 randomly chosen DH lines. Different marker types were applied, with an emphasis on AFLP and SSR markers. Analysis of variance, as well as simple and composite interval mapping, were applied. Three genomic regions were found significantly associated with FHB resistance. The most-prominent effect was detected on the short arm of chromosome 3B, explaining up to 60% of the phenotypic variance for Type II FHB resistance. A further QTL was located on chromosome 5A and a third one on 1B. The QTL regions on 3B and 5A were tagged with flanking SSR markers, the 1B QTL was found associated with the high-molecular-weight glutenin locus. These results indicate that FHB resistance is under control of a few major QTLs operating together with unknown numbers of minor genes. Marker-assisted selection for these major QTLs involved in FHB resistance appears feasible and should accelerate the development of resistant and agronomically improved wheat cultivars.

We investigated the hypothesis that resistance to deoxynivalenol (DON) is a major resistance factor in the Fusarium head blight (FHB) resistance complex of wheat. Ninety-six double haploid lines from a cross between 'CM-82036' and 'Remus' were examined. The lines were tested for DON resistance after application of the toxin in the ear, and for resistances to initial infection and spread of FHB after artificial inoculation with Fusarium spp. Toxin application to flowering ears induced typical FHB symptoms. Quantitative trait locus (QTL) analyses detected one locus with a major effect on DON resistance (logarithm of odds = 53.1, R2 = 92.6). The DON resistance phenotype was closely associated with an important FHB resistance QTL, Qfhs.ndsu-3BS, which previously was identified as governing resistance to spread of symptoms in the ear. Resistance to the toxin was correlated with resistance to spread of FHB (r = 0.74, P < 0.001). In resistant wheat lines, the applied toxin was converted to DON-3-O-glucoside as the detoxification product. There was a close relation between the DON-3-glucoside/DON ratio and DON resistance in the toxin-treated ears (R2 = 0.84). We conclude that resistance to DON is important in the FHB resistance complex and hypothesize that Qfhs.ndsu-3BS either encodes a DON-glucosyl-transferase or regulates the expression of such an enzyme.

Fusarium head blight (FHB) or scab caused by Fusarium Link: Fr. spp. is a widespread disease of cereals, causing significant yield losses and contaminating cereal products with mycotoxins. The complex inheritance of resistance has hampered progress in breeding resistant, agronomically adapted cultivars. To streamline breeding for FHB resistance, we estimated genetic and environmental variance components and broad‐sense heritability in two winter wheat (Triticum aestivum L.) populations, determined the association of FHB resistance with other traits (flowering date, plant height, and awnedness), and determined the level of maternal effects on FHB resistance. The moderately susceptible Austrian cultivar Capo was crossed with two resistant lines, one from Hungary (UNG‐226) and one from the Netherlands (SVP‐72017). A hierarchical design was applied to develop recombinant F4‐derived lines. Head blight resistance was measured by visual assessment of disease symptoms in artificially inoculated, mist‐irrigated field experiments during 2 yr. Artificial inoculation and mist irrigation led to reproducible FHB infections. High broad‐sense heritabilities (H > 0.75) were measured for FHB resistance, allowing for considerable progress by selection. The magnitude of additive genetic variance was greater than additive × additive epistatic variance. Despite a significant negative correlation between visual FHB symptoms and plant height true(r=−0.37true), the successful selection of short and FHB resistant genotypes should be feasible. In only one population, awned progeny showed slightly reduced FHB. Reciprocal effects were significant in one cross only. The development of FHB resistant cultivars should be possible by phenotypic selection under epidemic conditions, and should be largely independent of plant height, flowering date, awnedness, and genotype of the maternal parent within a cross.

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To determine whether resistance to Fusarium head blight in winter wheat is horizontal and non-species specific, 25 genotypes from five European countries were tested at six locations across Europe in the years 1990, 1991, and 1992. The five genotypes from each country had to cover the range from resistant to susceptible. The locations involved were Wageningen, Vienna, Rennes, Hohenheim, Oberer Lindenhof, and Szeged. In total, 17 local strains of Fusarium culmorum, F. graminearum, and F. nivale were used for experimental inoculation. One strain, F. culmorum IPO 39-01, was used at all locations. Best linear unbiased predictions (BLUPs) for the head blight ratings of the genotypes were formed within each particular location for each combination of year and strain. The BLUPs over all locations were collected in a genotype-by environment table in which the genotypic dimension consisted of the 25 genotypes, while the environmental dimension was made up of 59 year-by-strain-by-location combinations. A multiplicative model was fitted to the genotype by-environment interaction in this table. The inverses of the variances of the genotype-by-environment BLUPs were used as weights. Interactions between genotypes and environments were written as sums of products between genotypic scores and environmental scores. After correction for year-by-location influence very little variation in environmental scores could be ascribed to differences between strains. This provided the basis for the conclusion that the resistance to Fusarium head blight in winter wheat was of the horizontal and non-species specific type. There was no indication for any geographical pattern in virulence genes. Any reasonable aggressive strain, a F. culmorum strain for the cool climates and a F. graminearum strain for the warmer humid areas, should be satisfactory for screening purposes.