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Publikationen - Molekulare Signalverarbeitung

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Publikation

Wasternack, C.; Goetz, S.; Hellwege, A.; Forner, S.; Strnad, M.; Hause, B.; Another JA/COI1-independent role of OPDA detected in tomato embryo development Plant Signal Behav. 7, 1349-1353, (2012) DOI: 10.4161/psb.21551

Jasmonates (JAs) are ubiquitously occurring signaling compounds in plants formed in response to biotic and abiotic stress as well as in development. (+)-7-iso-jasmonoyl isoleucine, the bioactive JA, is involved in most JA-dependent processes mediated by the F-box protein COI1 in a proteasome-dependent manner. However, there is an increasing number of examples, where the precursor of JA biosynthesis, cis-(+)-12-oxophytodienoic acid (OPDA) is active in a JA/COI1-independent manner. Here, we discuss those OPDA-dependent processes, thereby giving emphasis on tomato embryo development. Recent data on seed coat-generated OPDA and its role in embryo development is discussed based on biochemical and genetic evidences.
Publikation

Stenzel, I.; Otto, M.; Delker, C.; Kirmse, N.; Schmidt, D.; Miersch, O.; Hause, B.; Wasternack, C.; ALLENE OXIDE CYCLASE (AOC) gene family members of Arabidopsis thaliana: tissue- and organ-specific promoter activities and in vivo heteromerization J. Exp. Bot. 63, 6125-6138, (2012) DOI: 10.1093/jxb/ers261

Jasmonates are important signals in plant stress responses and plant development. An essential step in the biosynthesis of jasmonic acid (JA) is catalysed by ALLENE OXIDE CYCLASE (AOC) which establishes the naturally occurring enantiomeric structure of jasmonates. In Arabidopsis thaliana, four genes encode four functional AOC polypeptides (AOC1, AOC2, AOC3, and AOC4) raising the question of functional redundancy or diversification. Analysis of transcript accumulation revealed an organ-specific expression pattern, whereas detailed inspection of transgenic lines expressing the GUS reporter gene under the control of individual AOC promoters showed partially redundant promoter activities during development: (i) In fully developed leaves, promoter activities of AOC1, AOC2, and AOC3 appeared throughout all leaf tissue, but AOC4 promoter activity was vascular bundle-specific; (ii) only AOC3 and AOC4 showed promoter activities in roots; and (iii) partially specific promoter activities were found for AOC1 and AOC4 in flower development. In situ hybridization of flower stalks confirmed the GUS activity data. Characterization of single and double AOC loss-of-function mutants further corroborates the hypothesis of functional redundancies among individual AOCs due to a lack of phenotypes indicative of JA deficiency (e.g. male sterility). To elucidate whether redundant AOC expression might contribute to regulation on AOC activity level, protein interaction studies using bimolecular fluorescence complementation (BiFC) were performed and showed that all AOCs can interact among each other. The data suggest a putative regulatory mechanism of temporal and spatial fine-tuning in JA formation by differential expression and via possible heteromerization of the four AOCs.
Publikation

Goetz, S.; Hellwege, A.; Stenzel, I.; Kutter, C.; Hauptmann, V.; Forner, S.; McCaig, B.; Hause, G.; Miersch, O.; Wasternack, C.; Hause, B.; Role of cis-12-Oxo-Phytodienoic Acid in Tomato Embryo Development Plant Physiol. 158, 1715-1727, (2012) DOI: 10.1104/pp.111.192658

Oxylipins including jasmonates are signaling compounds in plant growth, development, and responses to biotic and abiotic stresses. In Arabidopsis (Arabidopsis thaliana) most mutants affected in jasmonic acid (JA) biosynthesis and signaling are male sterile, whereas the JA-insensitive tomato (Solanum lycopersicum) mutant jai1 is female sterile. The diminished seed formation in jai1 together with the ovule-specific accumulation of the JA biosynthesis enzyme allene oxide cyclase (AOC), which correlates with elevated levels of JAs, suggest a role of oxylipins in tomato flower/seed development. Here, we show that 35S::SlAOC-RNAi lines with strongly reduced AOC in ovules exhibited reduced seed set similarly to the jai1 plants. Investigation of embryo development of wild-type tomato plants showed preferential occurrence of AOC promoter activity and AOC protein accumulation in the developing seed coat and the embryo, whereas 12-oxo-phytodienoic acid (OPDA) was the dominant oxylipin occurring nearly exclusively in the seed coat tissues. The OPDA- and JA-deficient mutant spr2 was delayed in embryo development and showed an increased programmed cell death in the developing seed coat and endosperm. In contrast, the mutant acx1a, which accumulates preferentially OPDA and residual amount of JA, developed embryos similar to the wild type, suggesting a role of OPDA in embryo development. Activity of the residual amount of JA in the acx1a mutant is highly improbable since the known reproductive phenotype of the JA-insensitive mutant jai1 could be rescued by wound-induced formation of OPDA. These data suggest a role of OPDA or an OPDA-related compound for proper embryo development possibly by regulating carbohydrate supply and detoxification.
Publikation

Brandt, R.; Salla-Martret, M.; Bou-Torrent, J.; Musielak, T.; Stahl, M.; Lanz, C.; Ott, F.; Schmid, M.; Greb, T.; Schwarz, M.; Choi, S.-B.; Barton, M. K.; Reinhart, B. J.; Liu, T.; Quint, M.; Palauqui, J.-C.; Martínez-García, J. F.; Wenkel, S.; Genome-wide binding-site analysis of REVOLUTA reveals a link between leaf patterning and light-mediated growth responses Plant J. 72, 31-42, (2012) DOI: 10.1111/j.1365-313X.2012.05049.x

Unlike the situation in animals, the final morphology of the plant body is highly modulated by the environment. During Arabidopsis development, intrinsic factors provide the framework for basic patterning processes. CLASS III HOMEODOMAIN LEUCINE ZIPPER (HD‐ZIPIII) transcription factors are involved in embryo, shoot and root patterning. During vegetative growth HD‐ZIPIII proteins control several polarity set‐up processes such as in leaves and the vascular system. We have identified several direct target genes of the HD‐ZIPIII transcription factor REVOLUTA (REV) using a chromatin immunoprecipitation/DNA sequencing (ChIP‐Seq) approach. This analysis revealed that REV acts upstream of auxin biosynthesis and affects directly the expression of several class II HD‐ZIP transcription factors that have been shown to act in the shade‐avoidance response pathway. We show that, as well as involvement in basic patterning, HD‐ZIPIII transcription factors have a critical role in the control of the elongation growth that is induced when plants experience shade. Leaf polarity is established by the opposed actions of HD‐ZIPIII and KANADI transcription factors. Finally, our study reveals that the module that consists of HD‐ZIPIII/KANADI transcription factors controls shade growth antagonistically and that this antagonism is manifested in the opposed regulation of shared target genes.
Publikation

Ortel, B.; Atzorn, R.; Hause, B.; Feussner, I.; Miersch, O.; Wasternack, C.; Jasmonate-induced gene expression of barley (Hordeum vulgare) leaves - the link between jasmonate and abscisic acid Plant Growth Regul. 29, 113-122, (1999) DOI: 10.1023/A:1006212017458

In barley leaves a group of genes is expressed in response to treatment with jasmonates and abscisic acid (ABA) [21]. One of these genes coding for a jasmonate-induced protein of 23 kDa (JIP-23) was analyzed to find out the link between ABA and jasmonates by recording its expression upon modulating independently, the endogenous level of both of them. By use of inhibitors of JA synthesis and ABA degradation, and the ABA-deficient mutant Az34, as well as of cultivar-specific differences, it was shown that endogenous jasmonate increases are necessary and sufficient for expression of this gene. The endogenous rise of ABA did not induce synthesis of JIP-23, whereas exogenous ABA did not act via jasmonates. Different signalling pathways are suggested and discussed.
Publikation

Miersch, O.; Kramell, R.; Parthier, B.; Wasternack, C.; Structure–activity relations of substituted, deleted or stereospecifically altered jasmonic acid in gene expression of barley leaves Phytochemistry 50, 353-361, (1999) DOI: 10.1016/S0031-9422(98)00597-4

Jasmonic acid and 66 structurally related compounds were tested to find the structural requirements which induce the expression of jasmonate-responsive genes in barley. An intact cyclopentanone ring as well as a pentenyl side chain exhibiting only minor alterations are necessary for this activity. The (−)-enantiomeric and the (+)-7-iso-enantiomeric structure increase activity of jasmonoyl compounds.
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

Miersch, O.; Bohlmann, H.; Wasternack, C.; Jasmonates and related compounds from Fusarium oxysporum Phytochemistry 50, 517-523, (1999) DOI: 10.1016/S0031-9422(98)00596-2

The culture filtrate of Fusarium oxysporum f sp matthiolae was inspected on the occurrence of jasmonates and related compounds. Among compounds described for the first time of biological origin are 7-iso-cucurbic acid, (1S,2S)- and (1S,2R)-3-oxo-2-pentylcyclopentane-1-butyric acid, (1S,2S)- and (1S,2R)-3-oxo-2-(2Z-pentenyl)cyclopentane-1-hexanoic acid, (1S,2S)- and (1S,2R)-3-oxo-2-pentylcyclopentane-1-hexanoic acid, (1S,2S)-3-oxo-2-(2Z-pentenyl)cyclopentane-1-octanoic acid, (1S,2S)-3-oxo-2-pentylcyclopentane-1-octanoic acid and N-[9,10-dihydro-7-iso-jasmonoyl]-(S)-isoleucine. The following metabolites were identified for the first time for this fungus: (−)-Jasmonic acid, 9,10-dihydrojasmonic acid and N-[(−)-jasmonoyl-(S)]-isoleucine were major constituents of the culture filtrate, whereas as minor metabolites occurred N-[9,10-dihydrojasmonoyl]-(S)-isoleucine, cucurbic acid and 3-oxo-2-(2Z-pentenyl)cyclopentane-1-butyric acid, 3-oxo-2-(2Z-pentenyl)cyclopentane-1-octanoic acid and 3-oxo-2-pentylcyclopentane-1-octanoic acid. All cyclopentanones found carried a cis- or trans-attached side chain. Didehydro-jasmonates, hydroxylated jasmonates or 12-oxophytodienoic acid could not be detected in the culture filtrate.
Publikation

Kramell, R.; Miersch, O.; Schneider, G.; Wasternack, C.; Liquid chromatography of jasmonic acid amine conjugates Chromatographia 49, 42-46, (1999) DOI: 10.1007/BF02467185

Racemic jasmonic acid (3R,7R/3S,7S)-(±)-JA) was chemically conjugated with different biogenic amines originating from aliphatic and aromatic α-amino acids by decarboxylation. The resulting isomeric compounds were subjected to reversed-phase high-performance liquid chromatography (HPLC) and to HPLC on the chiral stationary phases Chiralpak AS and Nucleodex β-PM. Under reversed-phase conditions, all the homologous amine derivatives tested could be separated from each other except the JA-conjugates containing 2-phenyl-ethylamine and 3-methylbutylamine. On both chiral supports the (3R,7R)-(−)-JA conjugates eluted earlier than those of the enantiomeric counterpart (3S,7S)-(+)-JA. On Chiralpak AS all the isomers studied could be separated to baseline with a mobile phase containingn-hexane and 2-propanol. The calculated resolution factors were between 1.80 and 4.17. The pairs of isomers were also chromatographed on the cyclodextrin stationary phase Nucleodex β-PM with methanol-triethylammonium acetate buffer as mobile phase. Under these conditions resolution factors were between 0.74 and 1.29. The individual isomers were chiroptically characterized by measurement of their circular dichroism.
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.
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