Activity of Ptr ToxA fromPyrenophora tritici-repentisrequires host metabolism

Kwon, C. Y.; Rasmussen, J. B.; Meinhardt, Steven W.

doi:10.1006/pmpp.1998.0151

Cited by 41 publications

(27 citation statements)

References 21 publications

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“…If ToxA did not interact with a high affinity receptor, we would expect that treatment with low amounts of toxin would result in diffuse and/or delayed cell death throughout the entire zone of infiltration, as opposed to concentrated necrotic symptoms near the point of treatment. ToxA activity is also temperature dependent (Kwon et al, 1998). Though energy dependence for ToxA activity has not been directly addressed, cell death caused by ToxA treatment requires light (Figure 4) and host metabolism (Kwon et al, 1998).…”

Section: Toxa Internalization Into Sensitive Wheat Cultivarsmentioning

confidence: 99%

“…ToxA activity is also temperature dependent (Kwon et al, 1998). Though energy dependence for ToxA activity has not been directly addressed, cell death caused by ToxA treatment requires light (Figure 4) and host metabolism (Kwon et al, 1998). ToxA activity can be reduced in a dose-dependent manner by coinfiltration of RGD-containing peptides (Meinhardt et al, 2002b;Manning et al, 2004) or by a nonfunctional mutantToxA protein containing an Asp-to-Glu mutation in the RGD motif (Manning et al, 2004).…”

Section: Toxa Internalization Into Sensitive Wheat Cultivarsmentioning

confidence: 99%

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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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Section: Toxa Internalization Into Sensitive Wheat Cultivarsmentioning

confidence: 99%

Section: Toxa Internalization Into Sensitive Wheat Cultivarsmentioning

confidence: 99%

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

2005

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“…Host sensitivity to ToxA is conferred by the presence of an as yet unidentified single dominant gene, Tsn1 (Ciuffetti et al, 1997;Gamba et al, 1998). Wheat cultivars harboring this gene are sensitive to the toxin and undergo a cell death reaction that involves a marked loss of membrane integrity and activation of cell signaling events involving unidentified protein kinases (Kwon et al, 1998;Rasmussen et al, 2004). No homologs of ToxA are present in the sequenced genome of M. graminicola isolate IPO323 (http://genome.jgi-psf.org/Mycgr1/Mycgr1.…”

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confidence: 99%

The Wheat Mitogen-Activated Protein Kinases TaMPK3 and TaMPK6 Are Differentially Regulated at Multiple Levels during Compatible Disease Interactions withMycosphaerella graminicola

2008

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Many race-or isolate-specific disease resistance responses of plants toward pathogens (incompatible interactions) invoke hypersensitive response (HR)-like programmed cell death (PCD) and the coordinated activation of mitogen-activated protein kinases homologous with Arabidopsis (Arabidopsis thaliana) AtMPK6 and AtMPK3 (or tobacco [Nicotiana tabacum] SIPK and WIPK), respectively. Resistance of wheat (Triticum aestivum) leaves to the necrotrophic fungal pathogen Mycosphaerella graminicola can also operate at an isolate/cultivar-specific level. We confirm here that resistance is achieved without any sign of HR-like PCD during the incompatible interaction. Instead, PCD is strictly associated with the compatible interaction and is triggered during disease symptom expression. A strong transcriptional activation of TaMPK3, the wheat homolog of Arabidopsis AtMPK3, was observed immediately preceding PCD and symptom development in the compatible interaction. Generation and use of TaMPK3-and TaMPK6-specific antibodies on western blots and in coupled immunoprecipitation-protein kinase assays demonstrated that the TaMPK3 protein also accumulated, and was subsequently posttranslationally activated, during the compatible interaction in parallel to PCD. In contrast, no increase in expression, protein levels, or posttranslational activation of TaMPK6 was observed at any stage of either compatible or incompatible interactions. However, the protein levels of TaMPK6 became markedly reduced during the compatible interaction coincident with the onset of TaMPK3 protein accumulation. These data highlight the emerging similarity between the signaling pathways triggered in a host plant during successful infection by a necrotrophic fungal pathogen and the resistance responses normally effective against biotrophs.

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“…The understanding of the role of toxin in disease development has progressed in recent years, but a large gap exists in our knowledge of events in the host associated with toxin action (Kwon et al, 1998). A toxin can have a role in inducing susceptibility and perhaps alternatively functioning as elicitors thus leading to accumulation of PR proteins and phytoalexins rendering the tissues resistant (Bailey and O'Connell, 1989).…”

Section: Discussionmentioning

confidence: 99%

Differential expression of defense‐related proteins of rice and sheath blight symptoms in response to active and inactiveRhizoctonia solanitoxin

Sriram¹,

Babu²,

Nandakumar³

et al. 2001

Archives Of Phytopathology And Plant Protection

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The effects of the phyotoxin from the fungal pathogen Rhizoctonia solani, causing sheath blight on the expression of defense-related proteins of rice were investigated. The toxin inactivated by chemical treatment and by the toxin-inactivating enzyme α-glucosidase produced by Trichoderma viride was used in the study along with the active toxin. Toxin inactivated by T. viride α-glucosidase and sodium periodate caused significantly less damage and electrolyte leakage to test plants. The active toxin and the pathogen induced chitinase and ß-1,3-glucanase synthesis in rice plants, while the inactivated toxin did not have any effect on the expression of these pathogenesis-related proteins. The toxin was found to suppress the peroxidase activity 72 h after inoculation and the inactivated toxin restored the activity as that of untreated plants. There was no remarkable change in phenylalanine ammonia lyase activity in rice sheath treated with both the forms of the toxin.

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Activity of Ptr ToxA fromPyrenophora tritici-repentisrequires host metabolism

Cited by 41 publications

References 21 publications

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

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

The Wheat Mitogen-Activated Protein Kinases TaMPK3 and TaMPK6 Are Differentially Regulated at Multiple Levels during Compatible Disease Interactions withMycosphaerella graminicola

Differential expression of defense‐related proteins of rice and sheath blight symptoms in response to active and inactiveRhizoctonia solanitoxin

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