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Publications - Stress and Develop Biology

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Publications

Qutob, D.; Kemmerling, B.; Brunner, F.; Küfner, I.; Engelhardt, S.; Gust, A. A.; Luberacki, B.; Seitz, H. U.; Stahl, D.; Rauhut, T.; Glawischnig, E.; Schween, G.; Lacombe, B.; Watanabe, N.; Lam, E.; Schlichting, R.; Scheel, D.; Nau, K.; Dodt, G.; Hubert, D.; Gijzen, M.; Nürnberger, T.; Phytotoxicity and Innate Immune Responses Induced by Nep1-Like Proteins Plant Cell 18, 3721-3744, (2006) DOI: 10.1105/tpc.106.044180

We show that oomycete-derived Nep1 (for necrosis and ethylene-inducing peptide1)–like proteins (NLPs) trigger a comprehensive immune response in Arabidopsis thaliana, comprising posttranslational activation of mitogen-activated protein kinase activity, deposition of callose, production of nitric oxide, reactive oxygen intermediates, ethylene, and the phytoalexin camalexin, as well as cell death. Transcript profiling experiments revealed that NLPs trigger extensive reprogramming of the Arabidopsis transcriptome closely resembling that evoked by bacteria-derived flagellin. NLP-induced cell death is an active, light-dependent process requiring HSP90 but not caspase activity, salicylic acid, jasmonic acid, ethylene, or functional SGT1a/SGT1b. Studies on animal, yeast, moss, and plant cells revealed that sensitivity to NLPs is not a general characteristic of phospholipid bilayer systems but appears to be restricted to dicot plants. NLP-induced cell death does not require an intact plant cell wall, and ectopic expression of NLP in dicot plants resulted in cell death only when the protein was delivered to the apoplast. Our findings strongly suggest that NLP-induced necrosis requires interaction with a target site that is unique to the extracytoplasmic side of dicot plant plasma membranes. We propose that NLPs play dual roles in plant pathogen interactions as toxin-like virulence factors and as triggers of plant innate immune responses.
Publications

Brunner, F.; Rosahl, S.; Lee, J.; Rudd, J. J.; Geiler, C.; Kauppinen, S.; Rasmussen, G.; Scheel, D.; Nürnberger, T.; Pep-13, a plant defense-inducing pathogen-associated pattern from Phytophthora transglutaminases EMBO J. 21, 6681-6688, (2002) DOI: 10.1093/emboj/cdf667

Innate immunity, an ancient form of defense against microbial infection, is well described for animals and is also suggested to be important for plants. Discrimination from self is achieved through receptors that recognize pathogen‐associated molecular patterns (PAMPs) not found in the host. PAMPs are evolutionarily conserved structures which are functionally important and, thus, not subject to frequent mutation. Here we report that the previously described peptide elicitor of defense responses in parsley, Pep‐13, constitutes a surface‐exposed fragment within a novel calcium‐dependent cell wall transglutaminase (TGase) from Phytophthora sojae . TGase transcripts and TGase activity are detectable in all Phytophthora species analyzed, among which are some of the most destructive plant pathogens. Mutational analysis within Pep‐13 identified the same amino acids indispensable for both TGase and defense‐eliciting activity. Pep‐13, conserved among Phytophthora TGases, activates defense in parsley and potato, suggesting its function as a genus‐specific recognition determinant for the activation of plant defense in host and non‐host plants. In summary, plants may recognize PAMPs with characteristics resembling those known to trigger innate immune responses in animals.
Publications

Brunner, F.; Wirtz, W.; Rose, J. K. C.; Darvill, A. G.; Govers, F.; Scheel, D.; Nürnberger, T.; A β-glucosidase/xylosidase from the phytopathogenic oomycete, Phytophthora infestans Phytochemistry 59, 689-696, (2002) DOI: 10.1016/S0031-9422(02)00045-6

An 85-kDa β-glucosidase/xylosidase (BGX1) was purified from the axenically grown phytopathogenic oomycete, Phytophthora infestans. The bgx1 gene encodes a predicted 61-kDa protein product which, upon removal of a 21 amino acid leader peptide, accumulates in the apoplastic space. Extensive N-mannosylation accounts for part of the observed molecular mass difference. BGX1 belongs to family 30 of the glycoside hydrolases and is the first such oomycete enzyme deposited in public databases. The bgx1 gene was found in various Phytophthora species, but is apparently absent in species of the related genus, Pythium. Despite significant sequence similarity to human and murine lysosomal glucosylceramidases, BGX1 demonstrated neither glucocerebroside nor galactocerebroside-hydrolyzing activity. The native enzyme exhibited glucohydrolytic activity towards 4-methylumbelliferyl (4-MU) β-d-glucopyranoside and, to lesser extent, towards 4-MU-d-xylopyranoside, but not towards 4-MU-β-d-glucopyranoside. BGX1 did not hydrolyze carboxymethyl cellulose, cellotetraose, chitosan or xylan, suggesting high substrate specificity and/or specific cofactor requirements for enzymatic activity.A β-glucosidase/xylosidase was purified from the phytopathogenic oomycete, Phytophthora infestans. The encoding gene is the first such sequence reported from a species of the kingdom chromista.
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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