Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
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.
Publikation
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 PathogensJ. Plant Physiol.154459-462(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.
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.
Publikation
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.152199-206(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.