Roles of the TSN1 and TSC2 Genes in Conferring Susceptibility of Durum Wheat to Tan Spot and Septoria Nodorum Blotch

Tan spot is an important disease caused by the necrotrophic fungus Pyrenophora triticirepentis. Two common necrotrophic effectors produced by this fungus are Ptr ToxA and Ptr ToxB, which recognize host sensitivity genes Tsn1 and Tsc2, respectively. In this research, a tetraploid recombinant inbred line population was evaluated for reaction to the Ptr ToxA and Ptr ToxB-producing isolates 86-124 (race 2) and DW5 (race 5). The results indicated that a compatible Tsc2-Ptr ToxB interaction accounted for 26% of the disease variation, which states that this interaction plays a significant role in the development of tan spot. On the contrary, the Tsn1-Ptr ToxA interaction was not associated with tan spot caused by 86-124. However, evaluation of a ToxA-producing isolate of Parastagonospora nodorum, indicated that the Tsn1- ToxA interaction accounted for 38% of the variation. Therefore, the Tsn1-ToxA interaction played a significant role in the development of septoria nodorum blotch, but not tan spot