|Ali, S. - PLNT PATH NDSU, FARGO, ND|
|Francl, L. - PLNT PATH NDSU, FARGO, ND|
|Rasmussen, J. - PLNT PATH NDSU, FARGO, ND|
Submitted to: Tan Spot International Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2002
Publication Date: September 1, 2003
Citation: Friesen, T.L., Ali, S., Francl, L.J., Rasmussen, J.B. 2003. REACTION OF RACE 2 OF THE TAN SPOT FUNGUS ON WHEAT MUTANTS INSENSITIVE TO PTR TOX A.. Tan Spot International Workshop Proceedings. pg 108-112 Technical Abstract: Pyrenophora tritici-repentis race 2, causal agent of tan spot of wheat, produces the host-selective toxin Ptr ToxA that has been described as a pathogenicity factor necessary for the establishment of race 2 disease on wheat. We previously isolated and genetically characterized three toxin-insensitive mutants derived from the toxin-sensitive and tan spot susceptible wheat cultivar Kulm (Phytopathology 92:38-42). In the current work, these mutants were found to be susceptible to race 2, although disease developed more slowly on the mutants than it did on the wild type Kulm. Homozygous toxin-insensitive F3 families derived from crosses between Kulm and each mutant were also susceptible to race 2, but lesions developed more slowly than on each of the homozygous toxin-sensitive F3 families. The data suggest that Ptr ToxA may be a virulence factor that influences the speed of disease development by race 2 rather than a pathogenicity factor that is required for disease.