Differential Phytotoxicity of Metabolic By-Products of Helminthosporium victoriae

Meehan, Frances; Murphy, H. C.

doi:10.1126/science.106.2751.270-a

Cited by 91 publications

(35 citation statements)

References 2 publications

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“…64 The necrotrophic fungus Cochliobolus victoriae, originally described as the causal agent of Victoria blight in oats, 65 secretes the toxin Victorin, required for pathogenicity. 66 This fungus hijacks HR via activation of a CC-NB-LRR protein LOV1, which confers sensitivity to victorin and susceptibility to C. victoriae in Arabidopsis. 67 In oats, loss of function mutations that eliminate toxin sensitivity and susceptiblility to C. victoriae also eliminate specific recognition and resistance to a biotrophic fungus, Puccinia coronata.…”

Section: Pathogen Strategies To Evade Cell Deathmentioning

confidence: 99%

Programmed cell death in the plant immune system

2011

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Cell death has a central role in innate immune responses in both plants and animals. Besides sharing striking convergences and similarities in the overall evolutionary organization of their innate immune systems, both plants and animals can respond to infection and pathogen recognition with programmed cell death. The fact that plant and animal pathogens have evolved strategies to subvert specific cell death modalities emphasizes the essential role of cell death during immune responses. The hypersensitive response (HR) cell death in plants displays morphological features, molecular architectures and mechanisms reminiscent of different inflammatory cell death types in animals (pyroptosis and necroptosis). In this review, we describe the molecular pathways leading to cell death during innate immune responses. Additionally, we present recently discovered caspase and caspase-like networks regulating cell death that have revealed fascinating analogies between cell death control across both kingdoms.

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Section: Pathogen Strategies To Evade Cell Deathmentioning

confidence: 99%

Programmed cell death in the plant immune system

2011

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“…Isolates of C. victoriae that produce victorin are pathogenic on susceptible A. sativa (Meehan and Murphy, 1947), whereas mutants or outcrosses that do not produce the toxin are nonpathogenic. Host susceptibility and victorin sensitivity are conferred by a dominant allele at the Vb locus (Litzenberger, 1949).…”

Section: Introductionmentioning

confidence: 99%

“…Victoria blight of Avena sativa (oat) is caused by the necrotrophic fungus, Cochliobolus victoriae (Meehan and Murphy, 1946), which is pathogenic because of the production of the hostspecific toxin, victorin (Meehan and Murphy, 1947). Isolates of C. victoriae that produce victorin are pathogenic on susceptible A. sativa (Meehan and Murphy, 1947), whereas mutants or outcrosses that do not produce the toxin are nonpathogenic.…”

Section: Introductionmentioning

confidence: 99%

Purification and Characterization of Serine Proteases That Exhibit Caspase-Like Activity and Are Associated with Programmed Cell Death in Avena sativa

2004

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Victoria blight of Avena sativa (oat) is caused by the fungus Cochliobolus victoriae, which is pathogenic because of the production of the toxin victorin. The victorin-induced response in sensitive A. sativa has been characterized as a form of programmed cell death (PCD) and displays morphological and biochemical features similar to apoptosis, including chromatin condensation, DNA laddering, cell shrinkage, altered mitochondrial function, and ordered, substrate-specific proteolytic events. Victorin-induced proteolysis of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is shown to be prevented by caspase-specific and general protease inhibitors. Evidence is presented for a signaling cascade leading to Rubisco proteolysis that involves multiple proteases. Furthermore, two proteases that are apparently involved in the Rubisco proteolytic cascade were purified and characterized. These proteases exhibit caspase specificity and display amino acid sequences homologous to plant subtilisin-like Ser proteases. The proteases are constitutively present in an active form and are relocalized to the extracellular fluid after induction of PCD by either victorin or heat shock. The role of the enzymes as processive proteases involved in a signal cascade during the PCD response is discussed.

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“…C. victoriae is pathogenic due to its production of victorin, a cyclized pentapeptide that acts as a host-selective toxin. Only oat genotypes that are sensitive to victorin are susceptible to C. victoriae infection, and treatment with victorin alone reproduces the symptoms of Victoria blight in sensitive oats (Meehan and Murphy, 1947). These symptoms include a programmed cell death response (Navarre and Wolpert, 1999;Yao et al, 2001Yao et al, , 2002Wolpert, 2002, 2004;Coffeen and Wolpert, 2004) and induction of host plant defense responses (Wheeler and Black, 1962;Shain and Wheeler, 1975;Mayama et al, 1986;Ullrich and Novacky, 1991).…”

Section: Introductionmentioning

confidence: 99%

Thioredoxinh5 Is Required for Victorin Sensitivity Mediated by a CC-NBS-LRR Gene inArabidopsis

2007

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The fungus Cochliobolus victoriae causes Victoria blight of oats (Avena sativa) and is pathogenic due to its production of victorin, which induces programmed cell death in sensitive plants. Victorin sensitivity has been identified in Arabidopsis thaliana and is conferred by the dominant gene LOCUS ORCHESTRATING VICTORIN EFFECTS1 (LOV1), which encodes a coiled-coil-nucleotide binding site-leucine-rich repeat protein. We isolated 63 victorin-insensitive mutants, including 59 lov1 mutants and four locus of insensitivity to victorin1 (liv1) mutants. The LIV1 gene encodes thioredoxin h5 (ATTRX5), a member of a large family of disulfide oxidoreductases. To date, very few plant thioredoxins have been assigned specific, nonredundant functions. We found that the victorin response was highly specific to ATTRX5, as the closely related ATTRX3 could only partially compensate for loss of ATTRX5, even when overexpressed. We also created chimeric ATTRX5/ATTRX3 proteins, which identified the central portion of the protein as important for conferring specificity to ATTRX5. Furthermore, we found that ATTRX5, but not ATTRX3, is highly induced in sensitive Arabidopsis following victorin treatment. Finally, we determined that only the first of the two active-site Cys residues in ATTRX5 is required for the response to victorin, suggesting that ATTRX5 function in the victorin pathway involves an atypical mechanism of action.

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Differential Phytotoxicity of Metabolic By-Products of Helminthosporium victoriae

Cited by 91 publications

References 2 publications

Programmed cell death in the plant immune system

Programmed cell death in the plant immune system

Purification and Characterization of Serine Proteases That Exhibit Caspase-Like Activity and Are Associated with Programmed Cell Death in Avena sativa

Thioredoxinh5 Is Required for Victorin Sensitivity Mediated by a CC-NBS-LRR Gene inArabidopsis

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