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Publikationen - Molekulare Signalverarbeitung

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Publikation

Goetz, S., Hellwege, A., Stenzel, I., Kutter, C., Hauptmann, V., Forner, S., Mc Caig, B., Hause, G., Miersch, O., Wasternack, C. & Hause, B. Role of cis-12-oxo-phytodienoic acid in tomato embryo development. Plant Physiol 158 (4), 1715-1727, (2012)

Oxylipins including jasmonates are signaling compounds in plant growth, development, and responses to biotic and abiotic stresses. In Arabidopsis (Arabidopsis thaliana) most mutants affected in jasmonic acid (JA) biosynthesis and signaling are male sterile, whereas the JA-insensitive tomato (Solanum lycopersicum) mutant jai1 is female sterile. The diminished seed formation in jai1 together with the ovule-specific accumulation of the JA biosynthesis enzyme allene oxide cyclase (AOC), which correlates with elevated levels of JAs, suggest a role of oxylipins in tomato flower/seed development. Here, we show that 35S::SlAOC-RNAi lines with strongly reduced AOC in ovules exhibited reduced seed set similarly to the jai1 plants. Investigation of embryo development of wild-type tomato plants showed preferential occurrence of AOC promoter activity and AOC protein accumulation in the developing seed coat and the embryo, whereas 12-oxo-phytodienoic acid (OPDA) was the dominant oxylipin occurring nearly exclusively in the seed coat tissues. The OPDA- and JA-deficient mutant spr2 was delayed in embryo development and showed an increased programmed cell death in the developing seed coat and endosperm. In contrast, the mutant acx1a, which accumulates preferentially OPDA and residual amount of JA, developed embryos similar to the wild type, suggesting a role of OPDA in embryo development. Activity of the residual amount of JA in the acx1a mutant is highly improbable since the known reproductive phenotype of the JA-insensitive mutant jai1 could be rescued by wound-induced formation of OPDA. These data suggest a role of OPDA or an OPDA-related compound for proper embryo development possibly by regulating carbohydrate supply and detoxification.

Publikation

Stenzel, I., Ischebeck, T., Quint, M. & Heilmann, I. Variable regions of PI4P 5-kinases direct PtdIns(4,5)P2 towards alternative regulatory functions in tobacco pollen tubes Front. Plant Sci 2, 114, (2012)

The apical plasma membrane of pollen tubes contains different PI4P 5-kinases that all produce phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2] but exert distinct cellular effects. In the present example, overexpression of Arabidopsis AtPIP5K5 or tobacco NtPIP5K6-1 caused growth defects previously attributed to increased pectin secretion. In contrast, overexpression of Arabidopsis AtPIP5K2 caused apical tip swelling implicated in altering actin fine structure in the pollen tube apex. AtPIP5K5, NtPIP5K6-1, and AtPIP5K2 share identical domain structures. Domains required for correct membrane association of the enzymes were identified by systematic deletion of N-terminal domains and subsequent expression of fluorescence-tagged enzyme truncations in tobacco pollen tubes. A variable linker region (Lin) contained in all PI4P 5-kinase isoforms of subfamily B, but not conserved in sequence, was recognized to be necessary for correct subcellular localization of AtPIP5K5, NtPIP5K6-1, and AtPIP5K2. Deletion of N-terminal domains including the Lin domain did not impair catalytic activity of recombinant AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 in vitro; however, the presence of the Lin domain was necessary for in vivo effects on pollen tube growth upon overexpression of truncated enzymes. Overexpression of catalytically inactive variants of AtPIP5K5, NtPIP5K6-1, or AtPIP5K2 did not influence pollen tube growth, indicating that PtdIns(4,5)P2 production rather than structural properties of PI4P 5-kinases was relevant for the manifestation of growth phenotypes. When Lin domains were swapped between NtPIP5K6-1 and AtPIP5K2 and the chimeric enzymes overexpressed in pollen tubes, the chimeras reciprocally gained the capabilities to invoke tip swelling or secretion phenotypes, respectively. The data indicate that the Lin domain directed the enzymes into different regulatory contexts, possibly contributing to channeling of PtdIns(4,5)P2 at the interface of secretion and actin cytoskeleton.

Publikation

Miersch, O., Neumerkel, J., Dippe, M., Stenzel, I. & Wasternack, C. Hydroxylated jasmonates are commonly occurring metabolites of jasmonic acid and contribute to a partial switch-off in jasmonate signaling New Phytologist 177, 114-127, (2008)

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Publikation

Stenzel, I., Hause, B., Proels, R., Miersch, O., Oka, M., Roitsch, T. & Wasternack, C. The AOC promoter of tomato is regulated by developmental and environmental stimuli Phytochemistry 69, 1859-1869, (2008)

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Publikation

Schilling, S., Stenzel, I., von Bohlen, A., Wermann, M., Schulz, K., Demuth, H.-U. & Wasternack, C. Isolation and characterization of the glutaminyl cyclases from Solanum tuberosum and Arabidopsis thaliana: implications for physiological functions Biol. Chem 388, 145-153, (2007)

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Publikation

Wasternack, C., Stenzel, I., Hause, B., Hause, G., Kutter, C., Maucher, H., Neumerkel, J., Feussner, I. & Miersch, O. The wound response in tomato Role of jasmonic acid J. Plant Physiol. 163, 297-306, (2006)

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Publikation

Stumpe, M., Carsjens, J.G., Stenzel, I., Göbel, C., Lang, I., Pawlowski, K., Hause, B. & Feussner, I. Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula Phytochemistry 66, 781-791, (2005)

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Publikation

Isayenkov, S., Mrosk, C., Stenzel, I., Strack, D. & Hause, B. Suppression of allene oxide cyclase in hairy roots of Medicago truncatula reduces jasmonate levels and the degree of mycorrhization with Glomus intraradices Plant Physiol. 139, 1401-1410, (2005)

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Publikation

Köck, M., Groß, N., Stenzel, I. & Hause, G. Phloem-specific expression of the wound-inducible ribonuclease LE from tomato (Lycopersicon esculentum cv. Lukullus) Planta 219, 233-242, (2004)

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Publikation

Maucher, H., Stenzel, I., Miersch, O., Stein, N., Prasad, M., Zierold, U., Schweizer, P., Dorer, C., Hause, B. & Wasternack, C. The allene oxide cyclase of barley (Hordeum vulgare L.) - cloning and organ-specific expression Phytochemistry 65, 801-811, (2004)

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