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Publications - Stress and Develop Biology

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Publications

Kroj, T.; Rudd, J. J.; Nürnberger, T.; Gäbler, Y.; Lee, J.; Scheel, D.; Mitogen-activated Protein Kinases Play an Essential Role in Oxidative Burst-independent Expression of Pathogenesis-related Genes in Parsley J. Biol. Chem. 278, 2256-2264, (2003) DOI: 10.1074/jbc.M208200200

Plants are continuously exposed to attack by potential phytopathogens. Disease prevention requires pathogen recognition and the induction of a multifaceted defense response. We are studying the non-host disease resistance response of parsley to the oomycete, Phytophthora sojae using a cell culture-based system. Receptor-mediated recognition of P. sojae may be achieved through a thirteen amino acid peptide sequence (Pep-13) present within an abundant cell wall transglutaminase. Following recognition of this elicitor molecule, parsley cells mount a defense response, which includes the generation of reactive oxygen species (ROS) and transcriptional activation of genes encoding pathogenesis-related (PR) proteins or enzymes involved in the synthesis of antimicrobial phytoalexins. Treatment of parsley cells with the NADPH oxidase inhibitor, diphenylene iodonium (DPI), blocked both Pep-13-induced phytoalexin production and the accumulation of transcripts encoding enzymes involved in their synthesis. In contrast, DPI treatment had no effect upon Pep-13-induced PRgene expression, suggesting the existence of an oxidative burst-independent mechanism for the transcriptional activation ofPR genes. The use of specific antibodies enabled the identification of three parsley mitogen-activated protein kinases (MAPKs) that are activated within the signal transduction pathway(s) triggered following recognition of Pep-13. Other environmental challenges failed to activate these kinases in parsley cells, suggesting that their activation plays a key role in defense signal transduction. Moreover, by making use of a protoplast co-transfection system overexpressing wild-type and loss-of-function MAPK mutants, we show an essential role for post-translational phosphorylation and activation of MAPKs for oxidative burst-independentPR promoter activation.
Books and chapters

Scheel, D.; Blume, B.; Brunner, F.; Fellbrich, G.; Dalbøge, H.; Hirt, H.; Kauppinen, S.; Kroj, T.; Ligterink, W.; Nürnberger, T.; Tschöpe, M.; Zinecker, H.; zur Nieden, U.; Receptor-mediated signal transduction in plant defense 131-135, (2000)

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Publications

Ligterink, W.; Kroj, T.; zur Nieden, U.; Hirt, H.; Scheel, D.; Receptor-Mediated Activation of a MAP Kinase in Pathogen Defense of Plants Science 276, 2054-2057, (1997) DOI: 10.1126/science.276.5321.2054

Parsley cells recognize the fungal plant pathogenPhytophthora sojae through a plasma membrane receptor. A pathogen-derived oligopeptide elicitor binds to this receptor and thereby stimulates a multicomponent defense response through sequential activation of ion channels and an oxidative burst. An elicitor-responsive mitogen-activated protein (MAP) kinase was identified that acts downstream of the ion channels but independently or upstream of the oxidative burst. Upon receptor-mediated activation, the MAP kinase is translocated to the nucleus where it might interact with transcription factors that induce expression of defense genes.
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