Purification of a Cultivar-Specific Toxin from<i>Pyrenophora tritici-repentis,</i>Causal Agent of Tan Spot of Wheat

Tomás, A. Easdale; Gao, Feng; Reeck, Gerald R.; Bockus, W. W.; Leach, J. E.

doi:10.1094/mpmi-3-221

Cited by 143 publications

(81 citation statements)

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“…P. tritici-repentis produces various HSTs, each of which uniquely leads to progression of disease on wheat cultivars that are sensitive to that particular toxin (reviewed in De Wolf et al, 1998;Ciuffetti and Tuori, 1999;Strelkov and Lamari, 2003). Of the three HSTs thus far characterized from P. tritici-repentis, two-Ptr ToxA (Ballance et al, 1989;Tomas et al, 1990;Tuori et al, 1995;Zhang et al, 1997) and Ptr ToxB (Strelkov et al, 1998)-have been shown to be proteins, whereas Ptr ToxC is a low molecular weight compound (Effertz et al, 2002). For Ptr ToxA (hereafter called ToxA), the first protein HST to be isolated (Ballance et al, 1989;Tomas et al, 1990;Tuori et al, 1995;Zhang et al, 1997), sensitivity is conditioned by the presence of a single host locus, Tsn1, on the 5BL chromosome (Faris et al, 1996;Stock et al, 1996;Gamba et al, 1998;Anderson et al, 1999) and the ToxA gene in the fungus (Ballance et al, 1996;Ciuffetti et al, 1997); disease occurs only when both the genes are present.…”

Section: Introductionmentioning

confidence: 99%

“…As an HST, not only is ToxA required for toxicity but infiltrating leaves of sensitive wheat cultivars with ToxA alone results in symptom development (Ballance et al, 1989;Tomas et al, 1990;Tuori et al, 1995). As shown in the accompanying article (Manning and Ciuffetti, 2005), green fluorescent protein tagged ToxA exerts its toxic effect via internalization into sensitive wheat mesophyll cells.…”

Section: Introductionmentioning

confidence: 99%

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Structure of Ptr ToxA: An RGD-Containing Host-Selective Toxin fromPyrenophora tritici-repentis

et al. 2005

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Tan spot of wheat (Triticum aestivum), caused by the fungus Pyrenophora tritici-repentis, has significant agricultural and economic impact. Ptr ToxA (ToxA), the first discovered proteinaceous host-selective toxin, is produced by certain P. triticirepentis races and is necessary and sufficient to cause cell death in sensitive wheat cultivars. We present here the highresolution crystal structure of ToxA in two different crystal forms, providing four independent views of the protein. ToxA adopts a single-domain, b-sandwich fold of novel topology. Mapping of the existing mutation data onto the structure supports the hypothesized importance of an Arg-Gly-Asp (RGD) and surrounding sequence. Its occurrence in a single, solvent-exposed loop in the protein suggests that it is directly involved in recognition events required for ToxA action. Furthermore, the ToxA structure reveals a surprising similarity with the classic mammalian RGD-containing domain, the fibronectin type III (FnIII) domain: the two topologies are related by circular permutation. The similar topologies and the positional conservation of the RGD-containing loop raises the possibility that ToxA is distantly related to mammalian FnIII proteins and that to gain entry it binds to an integrin-like receptor in the plant host.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure of Ptr ToxA: An RGD-Containing Host-Selective Toxin fromPyrenophora tritici-repentis

et al. 2005

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“…The HSTs produced by P. tritici-repentis are both proteinaceous and nonproteinaceous. For instance, Ptr ToxA (ToxA) and ToxB are proteins (Ballance et al, 1989;Tomas et al, 1990;Tuori et al, 1995;Ciuffetti et al, 1998;Strelkov et al, 1999;Martinez et al, 2001), whereas ToxC appears to be a polar, nonionic, low-molecular-weight molecule (Effertz et al, 2002). Other toxins have been identified but not fully characterized (Tuori et al, 1995;Ciuffetti et al, 2002;Meinhardt et al, 2002a).…”

mentioning

confidence: 99%

“…ToxA was the first HST isolated that was shown to be a protein (Ballance et al, 1989;Tomas et al, 1990;Tuori et al, 1995) and the product of a single gene (Ballance et al, 1996;Ciuffetti et al, 1997). Transformation of a nonpathogenic isolate with the ToxA gene is sufficient to render that isolate pathogenic on ToxA-sensitive wheat lines (Ciuffetti et al, 1997).…”

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confidence: 99%

Localization of Ptr ToxA Produced by Pyrenophora tritici-repentis Reveals Protein Import into Wheat Mesophyll Cells

2005

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The plant pathogenic fungus Pyrenophora tritici-repentis secretes host-selective toxins (HSTs) that function as pathogenicity factors. Unlike most HSTs that are products of enzymatic pathways, at least two toxins produced by P. tritici-repentis are proteins and, thus, products of single genes. Sensitivity to these toxins in the host is conferred by a single gene for each toxin. To study the site of action of Ptr ToxA (ToxA), toxin-sensitive and -insensitive wheat (Triticum aestivum) cultivars were treated with ToxA followed by proteinase K. ToxA was resistant to protease, but only in sensitive leaves, suggesting that ToxA is either protected from the protease by association with a receptor or internalized. Immunolocalization and green fluorescent protein tagged ToxA localization demonstrate that ToxA is internalized in sensitive wheat cultivars only. Once internalized, ToxA localizes to cytoplasmic compartments and to chloroplasts. Intracellular expression of ToxA by biolistic bombardment into both toxin-sensitive and -insensitive cells results in cell death, suggesting that the ToxA internal site of action is present in both cell types. However, because ToxA is internalized only in sensitive cultivars, toxin sensitivity, and therefore the ToxA sensitivity gene, are most likely related to protein import. The results of this study show that the ToxA protein is capable of crossing the plant plasma membrane from the apoplastic space to the interior of the plant cell in the absence of a pathogen.

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“…Tomás and Bockus (1987), cited for first time the possible presence of a necrosis-inducing toxin. Five research groups have worked on the isolation and characterization of the Tox A using isolates obtained from Kansas, United State of America (Pt1c) (Ciuffetti et al, 1997;Tomás et al, 1990;Touri et al, 1995) and Canadá (82-124) (Ballance et al, 1989;Zhang et al, 1997). Only three groups have isolated and cloned the gene encoding for Tox A.…”

Section: The Host Selective Toxin Produced By Pyrenophora Tritici-repmentioning

confidence: 99%

Pyrenophora tritici-repentis, Causal Agent of Tan Spot: A Review of Intraspecific Genetic Diversity

Moreno¹,

Stenglein²,

Perelló³

2012

The Molecular Basis of Plant Genetic Diversity

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Purification of a Cultivar-Specific Toxin fromPyrenophora tritici-repentis,Causal Agent of Tan Spot of Wheat

Cited by 143 publications

References 0 publications

Structure of Ptr ToxA: An RGD-Containing Host-Selective Toxin fromPyrenophora tritici-repentis

Structure of Ptr ToxA: An RGD-Containing Host-Selective Toxin fromPyrenophora tritici-repentis

Localization of Ptr ToxA Produced by Pyrenophora tritici-repentis Reveals Protein Import into Wheat Mesophyll Cells

Pyrenophora tritici-repentis, Causal Agent of Tan Spot: A Review of Intraspecific Genetic Diversity

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