The presence of the susceptibility gene, Tsn1, in some wheat lines and their reactions to ToxA infiltration produced by Pyrenophora tritici-repentis

The tan spot disease caused by Pyrenophora tritici-repentis is one of the most important diseases of wheat causing significant losses annually. The use of accurate, quick and cost-effective techniques, for evaluation of wheat lines to important diseases have been always considered by wheat breeders. In this study, reactions of 20 wheat lines to ToxA, the most important virulence factor of P. tritici-repentis, were evaluated using toxin infiltration approach. The results showed that 9 lines along with Grandin cv. as the susceptible cultivar, exhibited necrosis symptoms within 48 hours after toxin infiltration and, thus, were identified as the susceptible lines to ToxA. The remaining genotypes were identified as resistant lines to the toxin. In addition, PCR assays were used to detect the susceptibility gene, Tsn1, using gene-specific primers. The results showed that in susceptible lines a 380 bp band could be amplified revealing that Tsn1 gene was presented in these lines. All the resistant lines did not amplify Tsn1 gene and confirmed the results of toxin infiltration. The results of this study showed that this approach can be used for initial screening of wheat lines as a negative selection method for identification and subsequent elimination of susceptible lines from breeding programs.