Role of host sensitivity to Ptr ToxA in development of tan spot of wheat

T. L. Friesen, S. Ali, S. Kianian, L. J. Francl, J. B. Rasmussen

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Pyrenophora tritici-repentis race 2 produces Ptr ToxA, a host-selective toxin previously described as a pathogenicity factor for tan spot on wheat. The objective of this research was to evaluate the role of host sensitivity to toxin, conditioned by a single dominant gene on chromosome 5BL, in the disease development by race 2. An F2-derived F6 recombinant inbred population of 108 wheat lines, produced from crosses of toxin-sensitive, disease-susceptible cv. Kulm with the toxin-insensitive, disease-resistant cv. Erik segregated 1:1 for toxin reaction. However, the population was skewed toward resistance to race 2 of the fungus. Toxin reaction accounted for 24.4% of the genetic variance for disease. Heritability estimates suggested the presence of four to five genes that influence disease reaction in the population. Toxin-insensitive mutants, previously derived Kulm, were susceptible to race 2, although disease developed more slowly on the mutants than it did on the wild-type Kulm. The data indicate that sensitivity to Ptr ToxA influences disease severity in some host genotypes without defining susceptibility.

Original languageEnglish (US)
Pages (from-to)397-401
Number of pages5
Issue number4
StatePublished - Apr 1 2003


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