Molecular aspects of host-pathogen interactions in tan spot of wheat

In the wheat-Pyrenophora tritici-repentis pathosystem, the determination of susceptibility appears to be governed by interactions involving host-selec tive toxins. Two protein toxins have been identified and characterized for this pathosystem. This paper symmarizes the development in our knowledge of the necrosis-inducing toxin and the encoding gene. The nature of the host responses to fungal isolates and to the necrosis- and chlorosis-inducing to xins are also addressed.