zur Suche springenzur Navigation springenzum Inhalt springen

Publikationen - Molekulare Signalverarbeitung

Sortieren nach: Erscheinungsjahr Typ der Publikation

Zeige Ergebnisse 1 bis 10 von 13.

Publikation

Stumpe, M.; Göbel, C.; Faltin, B.; Beike, A. K.; Hause, B.; Himmelsbach, K.; Bode, J.; Kramell, R.; Wasternack, C.; Frank, W.; Reski, R.; Feussner, I.; The moss Physcomitrella patens contains cyclopentenones but no jasmonates: mutations in allene oxide cyclase lead to reduced fertility and altered sporophyte morphology New Phytol. 188, 740-749, (2010) DOI: 10.1111/j.1469-8137.2010.03406.x

Two cDNAs encoding allene oxide cyclases (PpAOC1, PpAOC2), key enzymes in the formation of jasmonic acid (JA) and its precursor (9S,13S)‐12‐oxo‐phytodienoic acid (cis‐(+)‐OPDA), were isolated from the moss Physcomitrella patens.Recombinant PpAOC1 and PpAOC2 show substrate specificity against the allene oxide derived from 13‐hydroperoxy linolenic acid (13‐HPOTE); PpAOC2 also shows substrate specificity against the allene oxide derived from 12‐hydroperoxy arachidonic acid (12‐HPETE).In protonema and gametophores the occurrence of cis‐(+)‐OPDA, but neither JA nor the isoleucine conjugate of JA nor that of cis‐(+)‐OPDA was detected.Targeted knockout mutants for PpAOC1 and for PpAOC2 were generated, while double mutants could not be obtained. The ΔPpAOC1 and ΔPpAOC2 mutants showed reduced fertility, aberrant sporophyte morphology and interrupted sporogenesis.
Publikation

Fonseca, S.; Chini, A.; Hamberg, M.; Adie, B.; Porzel, A.; Kramell, R.; Miersch, O.; Wasternack, C.; Solano, R.; (+)-7-iso-Jasmonoyl-L-isoleucine is the endogenous bioactive jasmonate Nat. Chem. Biol. 5, 344-350, (2009) DOI: 10.1038/nchembio.161

Hormone-triggered activation of the jasmonate signaling pathway in Arabidopsis thaliana requires SCFCOI1-mediated proteasome degradation of JAZ repressors. (−)-JA-L-Ile is the proposed bioactive hormone, and SCFCOI1 is its likely receptor. We found that the biological activity of (−)-JA-L-Ile is unexpectedly low compared to coronatine and the synthetic isomer (+)-JA-L-Ile, which suggests that the stereochemical orientation of the cyclopentanone-ring side chains greatly affects receptor binding. Detailed GC-MS and HPLC analyses showed that the (−)-JA-L-Ile preparations currently used in ligand binding studies contain small amounts of the C7 epimer (+)-7-iso-JA-L-Ile. Purification of each of these molecules demonstrated that pure (−)-JA-L-Ile is inactive and that the active hormone is (+)-7-iso-JA-L-Ile, which is also structurally more similar to coronatine. In addition, we show that pH changes promote conversion of (+)-7-iso-JA-L-Ile to the inactive (−)-JA-L-Ile form, thus providing a simple mechanism that can regulate hormone activity through epimerization.
Publikation

Eschen-Lippold, L.; Rothe, G.; Stumpe, M.; Göbel, C.; Feussner, I.; Rosahl, S.; Reduction of divinyl ether-containing polyunsaturated fatty acids in transgenic potato plants Phytochemistry 68, 797-801, (2007) DOI: 10.1016/j.phytochem.2006.12.010

Oxygenated polyunsaturated fatty acids synthesized via the lipoxygenase pathway play a role in plant responses to pathogen attack. In solanaceous plants, the preferential stimulation of the 9-lipoxygenase pathway in response to pathogen infection leads to the formation of the divinyl ether-containing polyunsaturated fatty acids colneleic and colnelenic acid, as well as hydroxy and trihydroxy polyunsaturated fatty acids. To functionally assess the role of divinyl ethers, transgenic potato plants were generated which express an RNA interference construct directed against the pathogen-inducible 9-divinyl ether synthase. Efficient reduction of 9-divinyl ether synthase transcript accumulation correlated with reduced levels of colneleic and colnelenic acid. However, in response to infection with virulent Phytophthora infestans, the causal agent of late blight disease, no significant differences in pathogen biomass could be detected suggesting that the levels of antimicrobial divinyl ethers are not critical for defense against Phytophthora infestans in a compatible interaction.
Publikation

Sharma, V. K.; Monostori, T.; Göbel, C.; Hänsch, R.; Bittner, F.; Wasternack, C.; Feussner, I.; Mendel, R. R.; Hause, B.; Schulze, J.; Transgenic barley plants overexpressing a 13-lipoxygenase to modify oxylipin signature Phytochemistry 67, 264-276, (2006) DOI: 10.1016/j.phytochem.2005.11.009

Three chimeric gene constructs were designed comprising the full length cDNA of a lipoxygenase (LOX) from barley (LOX2:Hv:1) including its chloroplast targeting sequence (cTP) under control of either (1) CaMV35S- or (2) polyubiquitin-1-promoter, whereas the third plasmid contains 35S promoter and the cDNA without cTP. Transgenic barley plants overexpressing LOX2:Hv:1 were generated by biolistics of scutella from immature embryos. Transformation frequency for 35S::LOX with or without cTP was in a range known for barley particle bombardment, whereas for Ubi::cTP-LOX no transgenic plants were detected. In general, a high number of green plantlets selected on bialaphos became yellow and finally died either in vitro or after potting. All transgenic plants obtained were phenotypically indistinguishable from wild type plants and all of them set seeds. The corresponding protein (LOX-100) in transgenic T0 and T1 plants accumulated constitutively to similar levels as in the jasmonic acid methyl ester (JAME)-treated wild type plants. Moreover, LOX-100 was clearly detectable immunocytochemically within the chloroplasts of untreated T0 plants containing the LOX-100-cDNA with the chloroplast target sequence. In contrast, an exclusive localization of LOX-100 in the cytoplasm was detectable when the target sequence was removed. In comparison to sorbitol-treated wild type leaves, analysis of oxylipin profiles in T2 progenies showed higher levels of jasmonic acid (JA) for those lines that displayed elevated levels of LOX-100 in the chloroplasts and for those lines that harboured LOX-100 in the cytoplasm, respectively. The studies demonstrate for the first time the constitutive overexpression of a cDNA coding for a 13-LOX in a monocotyledonous species and indicate a link between the occurrence of LOX-100 and senescence.
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) DOI: 10.1016/j.phytochem.2005.01.020

The peroxidation of polyunsaturated fatty acids, common to all eukaryotes, is mostly catalyzed by members of the lipoxygenase enzyme family of non-heme iron containing dioxygenases. Lipoxygenase products can be metabolized further in the oxylipin pathway by several groups of CYP74 enzymes. One prominent oxylipin is jasmonic acid (JA), a product of the 13-allene oxide synthase branch of the pathway and known as signaling substance that plays a role in vegetative and propagative plant development as well as in plant responses to wounding and pathogen attack. In barley roots, JA level increases upon colonization by arbuscular mycorrhizal fungi. Apart from this first result regarding JA, no information is available on the relevance of lipidperoxide metabolism in arbuscular mycorrhizal symbiosis. Thus we analyzed fatty acid and lipidperoxide patterns in roots of Medicago truncatula during mycorrhizal colonization. Levels of fungus-specific fatty acids as well as palmitic acid (16:0) and oleic acid (18:1 n − 9) were increased in mycorrhizal roots. Thus the degree of arbuscular mycorrhizal colonization of roots can be estimated via analysis of fungal specific esterified fatty acids. Otherwise, no significant changes were found in the profiles of esterified and free fatty acids. The 9- and 13-LOX products of linoleic and α-linolenic acid were present in all root samples, but did not show significant differences between mycorrhizal and non-mycorrhizal roots, except JA which showed elevated levels in mycorrhizal roots. In both types of roots levels of 13-LOX products were higher than those of 9-LOX products. In addition, three cDNAs encoding CYP74 enzymes, two 9/13-hydroperoxide lyases and a 13-allene oxide synthase, were isolated and characterized. The transcript accumulation of these three genes, however, was not increased in mycorrhizal roots of M. truncatula.
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-lipoxygenase 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

BERGER, S.; Weichert, H.; Porzel, A.; Wasternack, C.; Kühn, H.; Feussner, I.; Enzymatic and non-enzymatic lipid peroxidation in leaf development BBA-Mol. Cell Biol. Lipids 1533, 266-276, (2001) DOI: 10.1016/S1388-1981(01)00161-5

Enzymatic and non-enzymatic lipid peroxidation has been implicated in programmed cell death, which is a major process of leaf senescence. To test this hypothesis we developed a high-performance liquid chromatography (HPLC) method for a simultaneous analysis of the major hydro(pero)xy polyenoic fatty acids. Quantities of lipid peroxidation products in leaves of different stages of development including natural senescence indicated a strong increase in the level of oxygenated polyenoic fatty acids (PUFAs) during the late stages of leaf senescence. Comprehensive structural elucidation of the oxygenation products by means of HPLC, gas chromatography/mass spectrometry and 1H nuclear magnetic resonance suggested a non-enzymatic origin. However, in some cases a small share of specifically oxidized PUFAs was identified suggesting involvement of lipid peroxidizing enzymes. To inspect the possible role of enzymatic lipid peroxidation in leaf senescence, we analyzed the abundance of lipoxygenases (LOXs) in rosette leaves of Arabidopsis. LOXs and their product (9Z,11E,13S,15Z)-13-hydroperoxy-9,11,15-octadecatrienoic acid were exclusively detected in young green leaves. In contrast, in senescing leaves the specific LOX products were overlaid by large amounts of stereo-random lipid peroxidation products originating from non-enzymatic oxidation. These data indicate a limited contribution of LOXs to total lipid peroxidation, and a dominant role of non-enzymatic lipid peroxidation in late stages of leaf development.
Publikation

Miersch, O.; Porzel, A.; Wasternack, C.; Microbial conversion of jasmonates - hydroxylations by Aspergillus niger Phytochemistry 50, 1147-1152, (1999) DOI: 10.1016/S0031-9422(98)00698-0

Aspergillus niger is able to hydroxylate the pentenyl side chain of (−)-jasmonic acid (JA) leading to (11S)- (−)-hydroxy-JA/ (11R)- (−)-hydroxy-JA (2:1) and (−)-11,12-didehydro-JA. Methyl (−)-jasmonate (JA-Me) is converted upon hydrolysis. During prolonged cultivation or at non-optimized isolation procedures, the 11-hydroxy- (9Z)-pentenyl side chain may isomerize to (10E)-9-hydroxy- and (9E)-11-hydroxy-compounds by allylic rearrangement. The fungus hydroxylates (±)-9,10-dihydro-JA at position C-11 into 11j-hydroxy-9,10-dihydro-JA. As JA-Me, the methyl dihydro-JA is hydroxylated only upon hydrolysis into the free acid.
Publikation

Kramell, R.; Porzel, A.; Miersch, O.; Schneider, G.; Wasternack, C.; Chromatographic resolution of peptide-like conjugates of jasmonic acid and of cucurbic acid isomers J. Chromatogr. A 847, 103-107, (1999) DOI: 10.1016/S0021-9673(99)00335-0

The chiral separation of peptide-like conjugates of jasmonic acid and of cucurbic acid isomers was investigated by liquid chromatography on Chiralpak AS and Nucleodex β-PM. The retention sequences reflect distinct chromatographic properties with respect to the chirality of the jasmonic acid part or of the cucurbic acid isomers. The chromatographic behaviour of the amide conjugates on a reversed-phase C18 column provides evidence for the resolution of diastereomeric conjugates depending on the chirality of both constituents of the conjugate molecule. The chromatographic procedures are suitable for the analytical and preparative separation of such conjugates.
Bücher und Buchkapitel

Kramell, R.; Porzel, A.; Miersch, O.; Schneider, G.; Characterization of Isoleucine Conjugates of Cucurbic Acid Isomers by Reversed-Phase and Chiral High-Performance Liquid Chromatography 77-78, (1998)

0
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
IPB Mainnav Search