Resistance to Tan Spot and Insensitivity to Ptr ToxA in Wheat
2011
Noriel, Angelo Jay | Sun, Xiaochun | Bockus, Willium | Bai, Guihua
Tan spot, caused by the fungus Pyrenophora tritici-repentis, is an important foliar disease of wheat (Triticum aestivum L.) worldwide. Growing resistant cultivars is an effective approach to reduce the losses caused by the disease. To identify resistance genes in common wheat, 380 wheat accessions from different geographical origins were evaluated for resistance to P. tritici-repentis race 1, the predominant race in the Great Plains of the United States and western Canada, and insensitivity to Ptr ToxA, a host-selective toxin produced by race 1. Most accessions tested (60%) were resistant and only 93 accessions (24%) were as susceptible as TAM 105, the susceptible control. Among 379 accessions, 230 were insensitive to Ptr ToxA, but only 158 of them showed resistance to race 1. A weak correlation between tan spot score and sensitivity to Ptr ToxA suggests that pathogenicity factors other than Ptr ToxA (like Ptr ToxC) also contributed to tan spot development in these accessions. The accessions with resistance to tan spot identified in this study should be useful sources for developing new tan spot resistant cultivars.
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