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Publikationen - Stress- und Entwicklungsbiologie

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Publikation

Clemens, S.; Schroeder, J.I.; Degenkolb, T. Caenorhabditis elegans expresses a functional phytochelatin synthase Eur. J. Biochem. 268, 3640-3643, (2001) DOI: 10.1046/j.1432-1327.2001.02293.x

The formation of phytochelatins, small metal-binding glutathione-derived peptides, is one of the well-studied responses of plants to toxic metal exposure. Phytochelatins have also been detected in some fungi and some marine diatoms. Genes encoding phytochelatin synthases (PCS) have recently been cloned from Arabidopsis, wheat and Schizosaccharomyces pombe. Surprisingly, database searches revealed the presence of a homologous gene in the Caenorhabditis elegans genome, DDBJ/EMBL/GenBank accession no. 266513. Here we show that C. elegans indeed expresses a gene coding for a functional phytochelatin synthase. CePCS complements the Cd2+ sensitivity of a Schizosaccharomyces pombe PCS knock-out strain and confers phytochelatin synthase activity to these cells. Thus, phytochelatins may play a role for metal homeostasis also in certain animals.
Publikation

Nürnberger, T.; Scheel, D. Signal transmission in the plant immune response Trends in Plant Science 6, 372-379, (2001)

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Publikation

Göbel, C.; Feussner, I.; Schmidt, A.; Scheel, D.; Sanchez-Serrano, J.; Hamberg, M.; Rosahl, S. Oxylipin profiling reveals the preferential stimulation of the 9-lipoxygenase pathway in elicitor-treated potato cells J Biol Chem 276, 6267-6273, (2001)

Lipoxygenases are key enzymes in the synthesis of oxylipins and play an important role in the response of plants to wounding and pathogen attack. In cultured potato cells treated with elicitor from Phytophthora infestans, the causal agent of late blight disease, transcripts encoding a linoleate 9-lipoxygenase and a linoleate 13-lipoxygenase accumulate. However, lipoxygenase activity assays and oxylipin profiling revealed only increased 9-lipoxygenase activity and formation of products derived therefrom, such as 9-hydroxy octadecadienoic acid and colneleic acid. Furthermore, the 9-lipoxygenase products 9(S),10(S),11(R)-trihydroxy- 12(Z)-octadecenoic and 9(S),10(S),11(R)-trihydroxy-12(Z),15(Z)-octadecadienoic acid were identified as novel, elicitor-inducible oxylipins in potato, suggesting a role of these compounds in the defense response against pathogen attack. Neither 13-lipoxygenase activity nor 13-lipoxygenase products were detected to higher amounts in potato cells after elicitation. Thus, formation of products by the 9-lipoxygenase pathway including the enzymes hydroperoxide reductase, divinyl ether synthase and epoxy alcohol synthase is preferentially stimulated in cultured potato cells in response to treatment with P. infestans elicitor. Moreover, elicitor-induced accumulation of desaturase transcripts and increased phospholipase A2 activity after elicitor treatment suggest that substrates for the lipoxy- genase pathway might be provided by de novo synthesis and subsequent release from lipids of the endomembrane system.
Publikation

Lee, J.; Klüsener, B.; Tsiamis, G.; Stevens, C.; Neyt, C; Tampakaki, A.P.; Panopoulos, N.J.; Nöller, J.; Weiler, E.W.; Cornelis, G.R.; Mansfield, J.W.; Nürnberger, T. HrpZPsph from the plant pathogen <EM>Pseudomonas syringae</EM> pv. phaseolicola is exported by the type III secretion pathway and forms an ion-conducting pore in vitro Proc. Natl. Acad. Sci. U.S.A. 98, 289-294, (2001)

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Publikation

Clemens, S. Molecular mechanisms of plant metal homeostasis and tolerance Planta 212, 475-486, (2001)

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Publikation

Stumpe, M.; Kandzia, R.; Göbel, C.; Rosahl, S.; Feussner, I. A pathogen-inducible divinyl ether synthase (CYP74D) from elicitor-treated potato suspension cells FEBS Lett 507, 371-376, (2001)

In elicitor-treated potato cells, 9-lipoxygenase-derived oxylipins accumulate with the divinyl ether colneleic acid as the major metabolite. Here, the identification of a potato cDNA is described, whose predicted amino acid sequence corresponds to divinyl ether synthases, belonging to the recently identified new P450 subfamily CYP74D. The recombinant protein was expressed in Escherichia coli and shown to metabolize 9-hydroperoxy linoleic acid to colneleic acid at pH 6.5. This fatty acid derivative has been implicated in functioning as a plant antimicrobial compound. RNA blot analyses revealed accumulation of divinyl ether synthase transcripts both upon infiltration of potato leaves with Pseudomonas syringae and after infection with Phytophthora infestans.
Publikation

Lee, J.; Klessig, D.F.; Nürnberger, T. A harpin binding site in tobacco plasma membranes mediates activation of the pathogenesis-related gene HIN1 independent of extracellular calcium but dependent on mitogen-activated protein kinase activity Plant Cell 13, 1079-1093, (2001)

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Publikation

Cazalé, A.C.; Clemens, S. <em>Arabidopsis thaliana</em> expresses a second functional phytochelatin synthase FEBS Lett. 507, 215-219, (2001) DOI: 10.1016/S0014-5793(01)02976-3

Phytochelatins represent a major detoxifying pathway for heavy metals in plants and many other organisms. The Arabidopsis thaliana CAD1 (=AtPCS1) gene encodes a phytochelatin synthase and cad1 mutants are phytochelatin deficient and cadmium hypersensitive. The Arabidopsis genome contains a highly homologous gene, AtPCS2, of which expression and function were studied in order to understand the apparent non-redundancy of the two genes. Low constitutive AtPCS2 expression is detected in all plant organs analyzed. The AtPCS2 gene encodes a functional phytochelatin synthase as shown by expression in Saccharomyces cerevisiae and the complementation of a Schizosaccharomyces pombe phytochelatin synthase knockout strain.
Publikation

Sakaki, T.; Zähringer, U.; Warnecke, D.C.; Fahl, A.; Knogge, W.; Heinz, E. Sterol glycosides and cerebrosides accumulate in <EM>Pichia pastoris</EM>, <EM>Rhynchosporium secalis</EM>, and other fungi under normal conditions or under heat shock and ethanol stress Yeast 18, 679-695 , (2001)

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Publikation

Clemens, S. Developing tools for phytoremediation: towards a molecular understanding of plant metal tolerance and accumulation Int. J. Occup. Med. Environm. Health 14, 235-239, (2001)

Certain plant species and genotypes are able to accumulate large quantities of heavy metals in their shoots. Based on this trait the concept of phytoremediation was developed, i.e. the use of metal hyperaccumulating plants for the cleansing of contaminated soils and water. In order to more efficiently use this capacity, an engineering of plants might be needed. However, very little is known about the underlying molecular mechanisms. Our work is focussing on the identification and characterization of plant genes involved in plant metal uptake, tolerance and accumulation. Phytochelatins are small glutathione-derived metal-binding peptides which are part of the plant metal detoxification system. Genes encoding phytochelatin synthases have been cloned and are now being studied with regard to their regulation, biochemistry and biotechnological potential. Another project aimes at the dissection of metal responses in the metallophyte Arabidopsis halleri. This plant, a close relative to the model plant Arabidopsis thaliana, is Cd hypertolerant and Zn hyperaccumulating. It grows, for instance, on medieval mining sites in the Harz mountains in Germany and in many other metal-contaminated sites in Central Europe. We have isolated metal-regulated genes from A. halleri and molecularly analyzed interesting candidate genes with regard to their function and involvement in metal accumulation and tolerance.
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