Ubiquity of ToxA and absence of ToxB in Australian populations of Pyrenophora tritici-repentis
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Pyrenophora tritici-repentis, the causal organism of the necrotrophic foliar wheat disease tan spot [also known as yellow (leaf) spot in Australia] is an important disease in Australia and in many parts of the world. North American isolates of the pathogen have been shown to produce combinations of three host-specific toxins, ToxA, ToxB and ToxC. Each toxin interacts with a host sensitivity locus, respectively Tsn1, Tsc2 and Tsc1. The virulence of an isolate is partially correlated with the presence of these toxins and resistance in the host is associated with absence of the sensitivity loci. Breeding for resistance to tan spot can, therefore, be aided by knowledge of the prevalence of the toxin-encoding genes in local pathogen populations. Two of the toxins, A and B, are encoded by known genes and molecular tests for the genes have been developed. We screened a diverse collection of 119 tan spot isolates collected between 1984 and 2008 and from all affected regions of Australia (Queensland, New South Wales, Victoria and Western Australia). In all cases, the gene for ToxA was present and the gene for ToxB was absent. The implications for resistance breeding and epidemiology of the disease are discussed. We also define a diagnostic molecular marker for P. tritici-repentis
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Antoni, E.; Rybak, K.; Tucker, Madeline; Hane, J.; Solomon, P.; Drenth, A.; Shanka, M.; Oliver, Richard (2010)Pyrenophora tritici-repentis, the causal organism of the necrotrophic foliar wheat disease tan spot [alsoknown as yellow (leaf) spot in Australia] is an important disease in Australia and in many parts of the world. ...
The Tsn1-ToxA interaction in the wheat-Stagonospora nodorum pathosystem parallels that of the wheat-tan spot systemLiu, Z.; Friesen, T.; Ling, H.; Meinhardt, S.; Oliver, Richard; Rasmussen, J.; Faris, J. (2006)The wheat tan spot fungus (Pyrenophora tritici-repentis) produces a well-characterized host-selective toxin (HST) known as Ptr ToxA, which induces necrosis in genotypes that harbor the Tsn1 gene on chromosome 5B. In ...
The emergence of tan spot disease caused by toxigenic Pyrenophora tritici-repentis in Australia is not associated with increased deployment of toxin-sensitive cultivarsOliver, Richard; Lord, M.; Rybak, K.; Faris, J.; Solomon, P. (2008)The wheat disease tan (or yellow leaf) spot, caused by Pyrenophora tritici-repentis, was first described in the period 1934 to 1941 in Canada, India, and the United States. It was first noted in Australia in 1953 and only ...