Pathogenicity Patterns of Austrian Common Bunt Isolates on 42 Winter Wheat ( <i> <scp>Triticum aestivum</scp> L </i> .) Lines

ABSTRACT In organic winter wheat ( Triticum aestivum L.), common bunt (CB) caused by Tilletia caries and Tilletia laevis is one of the most serious diseases affecting grain yield and quality. Most cultivars are susceptible to CB, and even if a cultivar possesses resistance against a certain race, it may be susceptible to another one. We examined differences in pathogenicity patterns of eight Austrian isolates using a panel of 42 wheat genotypes, including the bunt differential set. CB incidence was assessed in artificially inoculated field trials in 2 years. Thirteen genotypes were highly resistant, with less than 1% incidence across years and isolates. Although the tested CB isolates could be differentiated in a GGE biplot analysis, the differences were mainly quantitative rather than qualitative, most likely due to the narrow geographic area in which the isolates were collected. Based on these results, we conclude that breeding for CB resistance should focus on local adaptation since variation in pathogenicity patterns exists even among isolates from a very confined region.