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Publikationen - Molekulare Signalverarbeitung

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Publikation

Wasternack, C.; Atzorn, R.; Pena-Cortes, H.; Parthier, B. Alteration of gene expression by jasmonate and ABA in tobacco and tomato J. Plant Physiol. 147, 503-510, (1996)

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Publikation

Hause, B.; Kogel, K.-H.; Parthier, B.; Wasternack, C. In barley leaf cells, jasmonates do not act as a signal during compatible or incompatible interactions with the powdery mildew fungus (<i>Erysiphe graminis</i> f. sp. <i>hordei</i>) J. Plant Physiol. 150, 127-132, (1997) DOI: 10.1016/S0176-1617(97)80191-5

We have studied a possible function of jasmonates as mediators in the host-pathogen interaction of barley (Hordeum vulgare L.) with the powdery mildew fungus Egh (Erysiphe graminis f. sp. hordei). Previous findings from whole-leaf extracts demonstrated that (i) extracts from infected barley leaves did not contain enhanced levels of jasmonates, (ii) transcripts of jasmonate-inducible genes were not expressed upon infection, and (iii) exogenous application of jasmonates did not induce resistance to Egh (Kogel et al., 1995). Nevertheless, the question arises whether or not jasmonates are involved in the interaction of barley with the powdery mildew fungus at the local site of infection. Using an immunocytological approach the analysis of leaf cross-sections from a susceptible barley cultivar and its near-isogenic mlo5-resistant line revealed no accumulation of JIP-23, the most abundant jasmonate inducible protein, neither in epidermal cells attacked by the pathogen nor in adjacent mesophyll cells. As a positive control, cross-sections from methyl jasmonate-treated leaf segments showed a strong signal for JIP-23 accumulation. Because the presence of the jasmonate-inducible protein is highly indicative for an already low threshold level of endogenous jasmonate (Lehmann et al., 1995), the lack of JIP-23 accumulation at the sites of attempted fungal infection clearly demonstrates the absence of enhanced levels of jasmonates. This excludes even a local rise of jasmonate confined to those single cells penetrated (Mlo genotype) or attacked (mlo5 genotype) by the fungus.
Publikation

Feussner, I.; Fritz, I.G.; Hause, B.; Ullrich, W.R.; Wasternack, C. Induction of a new lipoxygenase form in cucumber leaves by salicylic acid or 2,6-dichloroisonicotinic acid Bot. Acta 110, 101-108, (1997) DOI: 10.1111/j.1438-8677.1997.tb00616.x

Changes in lipoxygenase (LOX) protein pattern and/or activity were investigated in relation to acquired resistance of cucumber (Cucumis sativus L.) leaves against two powdery mildews, Sphaerotheca fuliginea (Schlecht) Salmon and Erysiphe cichoracearum DC et Merat. Acquired resistance was established by spraying leaves with salicylic acid (SA) or 2,6-dichloroisonicotinic acid (INA) and estimated in whole plants by infested leaf area compared to control plants. SA was more effective than INA. According to Western blots, untreated cucumber leaves contained a 97 kDa LOX form, which remained unchanged for up to 48 h after pathogen inoculation. Upon treatment with SA alone for 24 h or with INA plus pathogen, an additional 95 kDa LOX form appeared which had an isoelectric point in the alkaline range. For the induction of this form, a threshold concentration of 1 mM SA was required, higher SA concentrations did not change LOX-95 expression which remained similar between 24 h and 96 h but further increased upon mildew inoculation. Phloem exudates contained only the LOX-97 form, in intercellular washing fluid no LOX was detected. dichloroisonicotinic localization revealed LOX protein in the cytosol of the mesophyll cells without differences between the forms.
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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