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Publikationen - Molekulare Signalverarbeitung

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Jablonická, V.; Ziegler, J.; Vatehová, Z.; Lišková, D.; Heilmann, I.; Obložinský, M.; Heilmann, M.; Inhibition of phospholipases influences the metabolism of wound-induced benzylisoquinoline alkaloids in Papaver somniferum L. J. Plant Physiol. 223, 1-8, (2018) DOI: 10.1016/j.jplph.2018.01.007

Benzylisoquinoline alkaloids (BIAs) are important secondary plant metabolites and include medicinally relevant drugs, such as morphine or codeine. As the de novo synthesis of BIA backbones is (still) unfeasible, to date the opium poppy plant Papaver somniferum L. represents the main source of BIAs. The formation of BIAs is induced in poppy plants by stress conditions, such as wounding or salt treatment; however, the details about regulatory processes controlling BIA formation in opium poppy are not well studied. Environmental stresses, such as wounding or salinization, are transduced in plants by phospholipid-based signaling pathways, which involve different classes of phospholipases. Here we investigate whether pharmacological inhibition of phospholipase A2 (PLA2, inhibited by aristolochic acid (AA)) or phospholipase D (PLD; inhibited by 5-fluoro-2-indolyl des-chlorohalopemide (FIPI)) in poppy plants influences wound-induced BIA accumulation and the expression of key biosynthetic genes. We show that inhibition of PLA2 results in increased morphinan biosynthesis concomitant with reduced production of BIAs of the papaverine branch, whereas inhibition of PLD results in increased production of BIAs of the noscapine branch. The data suggest that phospholipid-dependent signaling pathways contribute to the activation of morphine biosynthesis at the expense of the production of other BIAs in poppy plants. A better understanding of the effectors and the principles of regulation of alkaloid biosynthesis might be the basis for the future genetic modification of opium poppy to optimize BIA production.

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) DOI: 10.1016/j.jplph.2005.10.014

Plants respond to mechanical wounding or herbivore attack with a complex scenario of sequential, antagonistic or synergistic action of different signals leading to defense gene expression. Tomato plants were used as a model system since the peptide systemin and the lipid-derived jasmonic acid (JA) were recognized as essential signals in wound-induced gene expression. In this review recent data are discussed with emphasis on wound-signaling in tomato. The following aspects are covered: (i) systemin signaling, (ii) JA biosynthesis and action, (iii) orchestration of various signals such as JA, H2O2, NO, and salicylate, (iv) local and systemic response, and (v) amplification in wound signaling. The common occurrence of JA biosynthesis and systemin generation in the vascular bundles suggest JA as the systemic signal. Grafting experiments with JA-deficient, JA-insensitive and systemin-insensitive mutants strongly support this assumption.

Hause, B.; Vörös, K.; Kogel, K.-H.; Besser, K.; Wasternack, C.; A Jasmonate-responsive Lipoxygenase of Barley Leaves is Induced by Plant Activators but not by Pathogens J. Plant Physiol. 154, 459-462, (1999) DOI: 10.1016/S0176-1617(99)80283-1

Using the recently isolated eDNA clone LOX2 : Hv : 1 which codes for the most abundant jasmonateinducible lipoxygenase (LOX) in barley leaves (Vörös et al., 1998), we analysed the capability of different activators of systemic activated resistance (SAR) to induce the expression of that LOX. Upon treatment of barley leaves with salicylate, 2,6-dichloroisonicotinic acid and benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester, all these compounds were able to induce the expression of the LOX2 : Hv : 1 gene, whereas upon infection with the powdery mildew fungus (Blumeria graminis f. sp. hordei) mRNA accumulation was not detectable in compatible or in incompatible interactions. The induction of the LOX2 : Hv : 1 protein by SAR activators and the expression of different sets of genes induced by jasmonate and salicylate, respectively, are discussed in relation to defense responses against pathogenic fungi.

Wasternack, C.; Ortel, B.; Miersch, O.; Kramell, R.; Beale, M.; Greulich, F.; Feussner, I.; Hause, B.; Krumm, T.; Boland, W.; Parthier, B.; Diversity in octadecanoid-induced gene expression of tomato J. Plant Physiol. 152, 345-352, (1998) DOI: 10.1016/S0176-1617(98)80149-1

In tomato plants wounding leads to up-regulation of various plant defense genes via jasmonates (Ryan, 1992; Bergey et al., 1996). Using this model system of jasmonic acid (JA) signalling, we analyzed activity of octadecanoids to express JA-responsive genes. Leaf treatments were performed with naturally occurring octadecanoids and their molecular mimics such as coronatine or indanone conjugates. JA responses were recorded in terms of up- or down-regulation of various genes by analyzing transcript accumulation, and at least partially in vitro translation products and polypeptide pattern of leaf extracts. The data suggest: (i) 12-Oxo-phytodienoic acid and other intermediates of the octadecanoid pathway has to be ß-oxidized to give a JA response, (ii) Octadecanoids which can not be ß-oxidized are inactive, (iii) JA, its methyl ester (JM), and its amino acid conjugates are most active signals in tomato leaves leading to up regulation of mainly wound-inducible genes and down-regulation of mainly <house-keeping> genes, (iv) Some compounds carrying a JA/JM- or JA amino acid conjugate-like structure induce/repress only a subset of genes suggesting diversity of JA signalling.

Ratajczak, R.; Feussner, I.; Hause, B.; Böhm, A.; Parthier, B.; Wasternack, C.; Alteration of V-type H+-ATPase during methyljasmonate-induced senescence in barley (Hordeum vulgare L. cv. Salome) J. Plant Physiol. 152, 199-206, (1998) DOI: 10.1016/S0176-1617(98)80133-8

In barley leaves, the application of (−)-jasmonic acid or its methyl ester (JAME) induces a senescencelike phenotype. This is accompanied by the synthesis of abundant proteins, so-called jasmonate-induced proteins (JlPs). Here, we show that modifications of vacuolar H+-ATPase (V-ATPase) subunits are jasmo-nate inducible. Using immunofluorescence analysis, we demonstrate that V-ATPase of barley leaves is exclusively located at the tonoplast also upon JAME treatment. Total ATP-hydrolysis activity of microsomal fractions increased by a factor of 10 during 72 h of JAME-treatment, while Bafilomycin Ai-sensitive ATP-hydrolysis activity, which is usually referred to V-ATPase activity, increased by a factor of about 2 in tono-plast-enriched membrane fractions. Moreover, due to JAME treatment there was a pronounced increase in ATP-hydrolysis activity at pH 6.2. This activity was not affected by inhibitors of P-, F-, or V-ATPases. However, biochemical analysis of partially purified V-ATPase suggests, that this activity might be due at least in part to the V-ATPase. JAME-treatment seems to change biochemical properties of the V-ATPase, i.e. a shift of the pH optimum of activity to a more acidic pH and a decrease in Bafilomycin A1 sensitivity. This is accompanied by the appearance of several additional forms of V-ATPase subunits which might represent either different isoforms or post-translationally modified proteins. We suggest that these changes in properties of the V-ATPase, which is involved in house-keeping and stress responses, may be due to JAME-induced senescence to overcome concomitant changes of the vacuolar membrane.

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 (Erysiphe graminis f. sp. hordei) 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.
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