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Publikationen - Molekulare Signalverarbeitung

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Publikation

Miersch, O.; Wasternack, C. Octadecanoid and jasmonate signaling in tomato leaves (<EM>Lycopersicon esculentum</EM> Mill.): Endogenous jasmonates do not induce jasmonate biosynthesis Biol. Chem. 381, 715-722, (2000)

Jasmonates and their precursors, the octadecanoids, are signals in stress-induced alteration of gene expression. Several mRNAs coding for enzymes of jasmonic acid (JA) biosynthesis are up-regulated upon JA treatment or endogenous rise of JA level. Here we inspected the positive feed back of endogenous JA on JA formation as well as its beta-oxidation steps. JA responsive gene expression was recorded in terms of proteinase inhibitor2 (pin2) mRNA accumulation. JA formed upon treatment of tomato (Lycopersicon esculentum cv. Moneymaker) leaves with JA derivatives carrying different length of the carboxylic acid side chain was quantified by gas chromatography-mass spectrometry (GC-MS). The data reveal that beta-oxidation of the side chain occurs up to a butyric acid moiety. The amount of JA formed from side-chain modified JA derivatives, correlated with pin2-mRNA accumulation. JA derivatives with a carboxylic side chain of 3, 5 or 7 carbon atoms were unable to form JA and to express on pin2, whereas even numbered derivatives were active. After treatment of tomato leaves with (10-2H)-(-)-12-oxophytoenoic acid, (4-2H)-(-)-JA and its methyl ester were formed and could be quantified separately from the endogenously unlabeled JA pool by GC-MS analysis via isotopic discrimination. The level of 8 nmol per g f.w. JA and its methyl ester originated exclusively from labeled 12-oxophytoenic acid. This and further data indicate that endogenous synthesis of the JA precursor 12-oxophytodienoic acid as well as of JA and its methyl ester are not induced in tomato leaves, suggesting that positive feedback in JA biosynthesis does not function in vivo.
Publikation

Schilling, S.; Manhart, S.; Hoffmann, T.; Ludwig, H.-H.; Wasternack, C.; Demuth, H.-U. Substrate specificity of glutaminyl cyclases from plants and animals Biol. Chem. 384, 1583-1592, (2003)

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Publikation

Sharma, V.K.; Monostori, T.; Hause, B.; Maucher, H.; Göbel, C.; Hornung, E.; Hänsch, R.; Bittner, F.; Wasternack, C.; Feussner, I.; Mendel, R.R.; Schulze, J. Genetic transformation of barley to modify expression of a 13-lipoxygenase Acta Biol. Szeged 49, 33-34 , (2005)

Immature scutella of barley were transformed with cDNA coding for a 13-li-poxygenase of barley (LOX-100) via particle bombardment. Regenerated plants were tested by PAT-assay, Western-analysis and PCR-screening. Immunocytochemical assay of T0 plants showed expression of the LOX cDNA both in the chloroplasts and in the cytosol, depending on the presence of the chloroplast signal peptide sequences in the cDNA. A few transgenic plants containing higher amounts of LOX-derived products have been found. These are the candidates for further analysis concerning pathogen resistance.
Publikation

Schilling, S.; Wasternack, C.; Demuth, H.U. Glutaminyl cyclases from animals and plants: a case of functionally convergent protein evolution Biol. Chem 389, 983-991, (2008) DOI: 10.1515/BC.2008.111

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Publikation

Bosch, M.; Wright, L. P.; Gershenzon, J.; Wasternack, C.; Hause, B.; Schaller, A.; Stintzi, A. Jasmonic acid and its precursor 12-oxophytodienoic acid control different aspects of constitutive and induced herbivore defenses in tomato Plant Physiology 166, 396-410, (2014) DOI: 10.1104/pp.114.237388

The jasmonate family of growth regulators includes the isoleucine conjugate of jasmonic acid (JA-Ile) and its biosynthetic precursor 12-oxophytodienoic acid (OPDA) as signaling molecules. In order to assess the relative contribution of JA/JA-Ile and OPDA to insect resistance in tomato, we silenced the expression of OPDA reductase (OPR3) by RNA interference. Consistent with a block in the biosynthetic pathway downstream of OPDA, OPR3-RNAi plants contained wild-type levels of OPDA but failed to accumulate JA or JA-Ile after wounding. JA/JA-Ile deficiency in OPR3-RNAi plants resulted in reduced trichome formation and impaired monoterpene and sesquiterpene production. The loss of these JA/JA-Ile-dependent defense traits rendered them more attractive to the specialist herbivore Manduca sexta with respect to feeding and oviposition. Oviposition preference resulted from reduced levels of repellant mono- and sesquiterpenes. Feeding preference, on the other hand, was caused by increased production of cis-3-hexenal acting as a feeding stimulant for M. sexta larvae in OPR3-RNAi plants. Despite impaired constitutive defenses and increased palatability of OPR3-RNAi leaves, larval development was indistinguishable on OPR3-RNAi and wild-type plants, and much delayed as compared to development on the JA/JA-Ile insensitive (jai1) mutant. Apparently, signaling through JAI1, the tomato ortholog of COI1 in Arabidopsis, is required for defense while the conversion of OPDA to JA/JA-Ile is not. Comparing the signaling activities of OPDA and JA/JA-Ile, we found that OPDA can substitute for JA/JA-Ile in the local induction of defense gene expression, but the production of JA/JA-Ile is required for a systemic response.
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