TY - JOUR ID - 2084 TI - Selective desensitization of jasmonate- and pH-dependent signaling in the induction of benzophenanthridine biosynthesis in cells of Eschscholzia californica JO - Phytochemistry PY - 2003 SP - 491-500 AU - Färber, K. AU - Schumann, B. AU - Miersch, O. AU - Roos, W. AU - VL - 62 UR - DO - 10.1016/S0031-9422(02)00562-9 AB - The biosynthesis of benzophenanthridine alkaloids, phytoalexins of Eschscholzia californica, in cultured cells can be induced by a glycoprotein preparation from yeast, methyljasmonate, artificial acidification with permeant acids, or mild osmotic stress. Each of these stimuli strongly attenuated the subsequent response to the same stimulus (homologous desensitization). Elicitor contact and artificial acidification mutually desensitized the cells for either signal. In contrast, elicitor-treated cells maintained their responsiveness to methyljasmonate or hyperosmolarity (sorbitol). Elicitor concentrations that nearly saturated the alkaloid response did not cause a detectable increase of jasmonate content. Transient acidification of the cytoplasm is a necessary step of signaling by low elicitor concentrations but was not detectable after jasmonate treatment. Seen together, the data indicate the existence of a jasmonate-dependent and jasmonate-independent (ΔpH controlled) signal pathway towards the expression of benzophenanthridine biosynthesis. Selective desensitization allows either stimulus to activate a distinct share of the biosynthetic capacity of the cell and limits the accumulation of toxic defense metabolites.Yeast elicitor and jasmonate trigger alkaloid production via different signal pathways that show selective desensitization. Elicitor treatment (bottom cells) but not jasmonate (top cells) evokes intracellular pH shifts. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2082 TI - Saturation of two chromosome regions conferring resistance to SCMV with SSR and AFLP markers by targeted BSA JO - Theor. Appl. Genet. PY - 2003 SP - 485-493 AU - Dußle, C. AU - Quint, M. AU - Melchinger, A. AU - Xu, M. AU - Lübberstedt, T. AU - VL - 106 UR - DO - 10.1007/s00122-002-1107-x AB - Quantitative trait loci (QTLs) and bulked segregant analyses (BSA) identified the major genes Scmv1 on chromosome 6 and Scmv2 on chromosome 3, conferring resistance against sugarcane mosaic virus (SCMV) in maize. Both chromosome regions were further enriched for SSR and AFLP markers by targeted bulked segregant analysis (tBSA) in order to identify and map only markers closely linked to either Scmv1 or Scmv2. For identification of markers closely linked to the target genes, symptomless individuals of advanced backcross generations BC5 to BC9 were employed. All AFLP markers, identified by tBSA using 400 EcoRI/MseI primer combinations, mapped within both targeted marker intervals. Fourteen SSR and six AFLP markers mapped to the Scmv1 region. Eleven SSR and 18 AFLP markers were located in the Scmv2 region. Whereas the linear order of SSR markers and the window size for the Scmv2 region fitted well with publicly available genetic maps, map distances and window size differed substantially for the Scmv1 region on chromosome 6. A possible explanation for the observed discrepancies is the presence of two closely linked resistance genes in the Scmv1 region. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2080 TI - Effect of Dietary Constituents With Chemopreventive Potential on Adduct Formation of a Low Dose of the Heterocyclic Amines PhIP and IQ and Phase II Hepatic Enzymes JO - Nutr. Cancer PY - 2003 SP - 212-221 AU - Dingley, K. H. AU - Ubick, E. A. AU - Chiarappa-Zucca, M. L. AU - Nowell, S. AU - Abel, S. AU - Ebeler, S. E. AU - Mitchell, A. E. AU - Burns, S. A. AU - Steinberg, F. M. AU - Clifford, A. J. AU - VL - 46 UR - DO - 10.1207/S15327914NC4602_15 AB - We conducted a study to evaluate dietary chemopreventive strategies to reduce genotoxic effects of the carcinogens 2-amino-1-methyl-6-phenyl-imidazo[4,5-b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). PhIP and IQ are heterocyclic amines (HCAs) that are found in cooked meat and may be risk factors for cancer. Typical chemoprevention studies have used carcinogen doses many thousand-fold higher than usual human daily intake. Therefore, we administered a low dose of [14C] PhIPand [3H] IQand utilized accelerator mass spectrometry to quantify PhIP adducts in the liver, colon, prostate, and blood plasma and IQadducts in the liver and blood plasma with high sensitivity. Diets supplemented with phenethylisothiocyanate (PEITC), genistein, chlorophyllin, or lycopene were evaluated for their ability to decrease adduct formation of [14C] PhIPand [3H] IQin rats. We also examined the effect of treatments on the activity of the phase II detoxification enzymes glutathione S-transferase (GST), UDP-glucuronyltransferase (UGT), phenol sulfotransferase (SULT) and quinone reductase (QR). PEITC and chlorophyllin significantly decreased PhIP-DNA adduct levels in all tissues examined, which was reflected by similar changes in PhIP binding to albumin in the blood. In contrast, genistein and lycopene tended to increase PhIP adduct levels. The treatments did not significantly alter the level of IQ-DNA or -protein adducts in the liver.With the exception of lycopene, the treatments had some effect on the activity of one or more hepatic phase II detoxification enzymes. We conclude that PEITC and chlorophyllin are protective of PhIP-induced genotoxicity after a low exposure dose of carcinogen, possibly through modification of HCA metabolism. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2079 TI - Peripheral regions of natural hammerhead ribozymes greatly increase their self-cleavage activity JO - EMBO J. PY - 2003 SP - 5561-5570 AU - De la Peña, M. AU - Gago, S. AU - Flores, R. AU - VL - 22 UR - DO - 10.1093/emboj/cdg530 AB - Natural hammerhead ribozymes are mostly found in some viroid and viroid‐like RNAs and catalyze their cis cleavage during replication. Hammerheads have been manipulated to act in trans and assumed to have a similar catalytic behavior in this artificial context. However, we show here that two natural cis‐acting hammerheads self‐cleave much faster than trans‐acting derivatives and other reported artificial hammerheads. Moreover, modifications of the peripheral loops 1 and 2 of one of these natural hammerheads induced a >100‐fold reduction of the self‐cleavage constant, whereas engineering a trans‐acting artificial hammerhead into a cis derivative by introducing a loop 1 had no effect. These data show that regions external to the central conserved core of natural hammerheads play a role in catalysis, and suggest the existence of tertiary interactions between these peripheral regions. The interactions, determined by the sequence and size of loops 1 and 2 and most likely of helices I and II, must result from natural selection and should be studied in order to better understand the hammerhead requirements in vivo. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2070 TI - Jasmonate and octadecanoid occurrence in tomato hairy roots. Endogenous level changes in response to NaCl JO - Plant Growth Regul. PY - 2003 SP - 21-27 AU - Abdala, G. AU - Miersch, O. AU - Kramell, R. AU - Vigliocco, A. AU - Agostini, E. AU - Forchetti, G. AU - Alemano, S. AU - VL - 40 UR - DO - 10.1023/A:1023016412454 AB - Jasmonic acid biosynthesis occurs in leaves and there is also evidence of a similar pathway in roots. The expression of lipoxygenase, allene oxide cyclase and low amounts of transcripts of allene oxide synthase in tomato roots indicates that some steps of the jasmonate synthesis may occur in these organs. Thus, the aim of the present work was to study the jasmonate and octadecanoid occurrence in tomato roots using isolated cultures of hairy roots. These were obtained by the transformation of cv. Pera roots with Agrobacterium rhyzogenes. Also we investigated the effect of NaCl stress on the endogenous levels of these compounds. Jasmonic acid, 12-oxophytodienoic acid and their methylated derivatives, as well as a jasmonate-isoleucine conjugate, were present in control hairy roots of 30 d of culture. The 12-oxophytodienoic acid and its methylated derivative showed higher levels than jasmonic acid and its methylated form, although the content of the conjugate was the same as that of jasmonic acid. After salinization of hairy roots for 14, 20 and 30 d, free jasmonates and octadecanoids were measured. Fourteen days after salt treatment, increased levels of these compounds were found, jasmonic acid and 12-oxophytodienoic acid showed the most remarkable rise. 11-OH-jasmonic acid was found at 14 d of culture in control and salt-treated hairy roots; whereas the 12-OH- form of jasmonic acid was only detected in the salt-treated hairy roots. Agrobacterium rhizogenes cultures did not produce jasmonates and/or octadecanoids. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2089 TI - Occurrence of the allene oxide cyclase in different organs and tissues of Arabidopsis thaliana JO - Phytochemistry PY - 2003 SP - 971-980 AU - Hause, B. AU - Stenzel, I. AU - Miersch, O. AU - Wasternack, C. AU - VL - 64 UR - DO - 10.1016/S0031-9422(03)00447-3 AB - Occurrence of an essential enzyme in jasmonate (JA) biosynthesis, the allene oxide cyclase, (AOC) was analyzed in different developmental stages and various organs of Arabidopsis thaliana plants by immuno blot analysis and immunocytological approaches. Levels of AOC and of the two preceding enzymes in JA biosynthesis increased during seedling development accompanied by increased levels of JA and 12-oxophytodienoic acid levels after 4 and 8 weeks. Most tissues including all vascular bundles and that of flower buds contain AOC protein. Flowers shortly before opening, however, contain AOC protein preferentially in ovules, stigma cells and vascular bundles, whereas in anthers and pollen AOC could not be detected. The putative roles of AOC and JA in development are discussed.The allene oxide cyclase (AOC) is an important enzyme in jasmonate biosynthesis. Levels and occurrence of AOC in different organs and tissues are altered during development of Arabidopsis thaliana. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2088 TI - Enzymes of Jasmonate Biosynthesis Occur in Tomato Sieve Elements JO - Plant Cell Physiol. PY - 2003 SP - 643-648 AU - Hause, B. AU - Hause, G. AU - Kutter, C. AU - Miersch, O. AU - Wasternack, C. AU - VL - 44 UR - DO - 10.1093/pcp/pcg072 AB - The allene oxide cyclase (AOC) is a plastid-located enzyme in the biosynthesis of the signaling compound jasmonic acid (JA). In tomato, AOC occurs specifically in ovules and vascular bundles [Hause et al. (2000)PlantJ. 24; 113]. Immunocytological analysis of longitudinal sections of petioles and flower stalks revealed the occurrence of AOC in companion cells (CC) and sieve elements (SE). Electron microscopic analysis led to the conclusion that the AOC-containing structures of SE are plastids. AOC was not detected in SE of 35S::AOCantisense plants. The enzymes preceding AOC in JA biosynthesis, the allene oxide synthase (AOS) and the lipoxygenase, were also detected in SE. In situ hybridization showed that the SE are free of AOC-mRNA suggesting AOC protein traffic from CC to SE via plasmodesmata. A control by in situ hybridization of AOS mRNA coding for a protein with a size above the exclusion limit of plasmodesmata indicated mRNA in CC and SE. The data suggest that SE carry the capacity to form 12-oxo-phytodienoic acid, the unique precursor of JA. Together with preferential generation of JA in vascular bundles [Stenzel et al. (2003)Plant J. 33: 577], the data support a role of JA in systemic wound signaling. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2086 TI - Biochemical and Molecular Characterization of a Hydroxyjasmonate Sulfotransferase from Arabidopsis thaliana JO - J. Biol. Chem. PY - 2003 SP - 17895-17900 AU - Gidda, S. K. AU - Miersch, O. AU - Levitin, A. AU - Schmidt, J. AU - Wasternack, C. AU - Varin, L. AU - VL - 278 UR - DO - 10.1074/jbc.M211943200 AB - 12-Hydroxyjasmonate, also known as tuberonic acid, was first isolated from Solanum tuberosum and was shown to have tuber-inducing properties. It is derived from the ubiquitously occurring jasmonic acid, an important signaling molecule mediating diverse developmental processes and plant defense responses. We report here that the gene AtST2a from Arabidopsis thaliana encodes a hydroxyjasmonate sulfotransferase. The recombinant AtST2a protein was found to exhibit strict specificity for 11- and 12-hydroxyjasmonate with Km values of 50 and 10 μm, respectively. Furthermore, 12-hydroxyjasmonate and its sulfonated derivative are shown to be naturally occurring inA. thaliana. The exogenous application of methyljasmonate to A. thaliana plants led to increased levels of both metabolites, whereas treatment with 12-hydroxyjasmonate led to increased level of 12-hydroxyjasmonate sulfate without affecting the endogenous level of jasmonic acid. AtST2a expression was found to be induced following treatment with methyljasmonate and 12-hydroxyjasmonate. In contrast, the expression of the methyljasmonate-responsive gene Thi2.1, a marker gene in plant defense responses, is not induced upon treatment with 12-hydroxyjasmonate indicating the existence of independent signaling pathways responding to jasmonic acid and 12-hydroxyjasmonic acid. Taken together, the results suggest that the hydroxylation and sulfonation reactions might be components of a pathway that inactivates excess jasmonic acid in plants. Alternatively, the function of AtST2a might be to control the biological activity of 12-hydroxyjasmonic acid. A2 - C1 - Bioorganic Chemistry; Molecular Signal Processing ER - TY - JOUR ID - 2124 TI - Jasmonate biosynthesis and the allene oxide cyclase family of Arabidopsis thaliana JO - Plant Mol. Biol. PY - 2003 SP - 895-911 AU - Stenzel, I. AU - Hause, B. AU - Miersch, O. AU - Kurz, T. AU - Maucher, H. AU - Weichert, H. AU - Ziegler, J. AU - Feussner, I. AU - Wasternack, C. AU - VL - 51 UR - DO - 10.1023/A:1023049319723 AB - In biosynthesis of octadecanoids and jasmonate (JA), the naturally occurring enantiomer is established in a step catalysed by the gene cloned recently from tomato as a single-copy gene (Ziegler et al., 2000). Based on sequence homology, four full-length cDNAs were isolated from Arabidopsis thaliana ecotype Columbia coding for proteins with AOC activity. The expression of AOCgenes was transiently and differentially up-regulated upon wounding both locally and systemically and was induced by JA treatment. In contrast, AOC protein appeared at constitutively high basal levels and was slightly increased by the treatments. Immunohistochemical analyses revealed abundant occurrence of AOC protein as well as of the preceding enzymes in octadecanoid biosynthesis, lipoxygenase (LOX) and allene oxide synthase (AOS), in fully developed tissues, but much less so in 7-day old leaf tissues. Metabolic profiling data of free and esterified polyunsaturated fatty acids and lipid peroxidation products including JA and octadecanoids in wild-type leaves and the jasmonate-deficient mutant OPDA reductase 3 (opr3) revealed preferential activity of the AOS branch within the LOX pathway. 13-LOX products occurred predominantly as esterified derivatives, and all 13-hydroperoxy derivatives were below the detection limits. There was a constitutive high level of free 12-oxo-phytodienoic acid (OPDA) in untreated wild-type and opr3 leaves, but an undetectable expression of AOC. Upon wounding opr3 leaves exhibited only low expression of AOC, wounded wild-type leaves, however, accumulated JA and AOC mRNA. These and further data suggest regulation of JA biosynthesis by OPDA compartmentalization and a positive feedback by JA during leaf development. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2123 TI - Differential expression of the LePS2 phosphatase gene family in response to phosphate availability, pathogen infection and during development JO - Physiol. Plant. PY - 2003 SP - 138-146 AU - Stenzel, I. AU - Ziethe, K. AU - Schurath, J. AU - Hertel, S. C. AU - Bosse, D. AU - Köck, M. AU - VL - 118 UR - DO - 10.1034/j.1399-3054.2003.00091.x AB - In this study, we report the cloning of the three‐member LePS2 gene family of acid phosphatases via subtractive screening of a cDNA library of Pi‐starved cultivated tomato cells (Lycopersicon esculentum Mill. cv. Lukullus). As members of the plant Pi‐starvation response, LePS2 genes were tightly regulated in cultivated cells and tomato seedlings by Pi availability. The LePS2 enzymes which are most likely expressed in the cytoplasma could be involved in processes that are accompanied by degradation of phosphorylated organic substrates. Independently from exogenous phosphate supply LePS2 expression was detected in tomato endosperm during germination. LePS2 genes were differentially induced after infection with the bacterial pathogen Pseudomonas syringae and in the early stages of flower development. Using RT–PCR it was found that the gene LePS2B was the most abundant transcript in phosphate‐depleted cells, but a reduced expression was determined in floral buds and it was not found during pathogen interaction. In this respect, it is interesting that the promoter sequences of the LePS2 genes are also divergent. LePS2 gene products may have functions in developmental processes which are restricted to distinct plant tissues or cell types. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2122 TI - Allene oxide cyclase dependence of the wound response and vascular bundle-specific generation of jasmonates in tomato - amplification in wound signalling JO - Plant J. PY - 2003 SP - 577-589 AU - Stenzel, I. AU - Hause, B. AU - Maucher, H. AU - Pitzschke, A. AU - Miersch, O. AU - Ziegler, J. AU - Ryan, C. A. AU - Wasternack, C. AU - VL - 33 UR - DO - 10.1046/j.1365-313X.2003.01647.x AB - The allene oxide cyclase (AOC)‐catalyzed step in jasmonate (JA) biosynthesis is important in the wound response of tomato. As shown by treatments with systemin and its inactive analog, and by analysis of 35S::prosysteminsense and 35S::prosysteminantisense plants, the AOC seems to be activated by systemin (and JA) leading to elevated formation of JA. Data are presented on the local wound response following activation of AOC and generation of JA, both in vascular bundles. The tissue‐specific occurrence of AOC protein and generation of JA is kept upon wounding or other stresses, but is compromised in 35S::AOCsense plants, whereas 35S::AOCantisense plants exhibited residual AOC expression, a less than 10% rise in JA, and no detectable expression of wound response genes. The (i) activation of systemin‐dependent AOC and JA biosynthesis occurring only upon substrate generation, (ii) the tissue‐specific occurrence of AOC in vascular bundles, where the prosystemin gene is expressed, and (iii) the tissue‐specific generation of JA suggest an amplification in the wound response of tomato leaves allowing local and rapid defense responses. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - JOUR ID - 2117 TI - Substrate Specificity of Glutaminyl Cyclases from Plants and Animals JO - Biol. Chem. PY - 2003 SP - 1583-1592 AU - Schilling, S. AU - Manhart, S. AU - Hoffmann, T. AU - Ludwig, H.-H. AU - Wasternack, C. AU - Demuth, H.-U. AU - VL - 384 UR - DO - 10.1515/BC.2003.175 AB - Glutaminyl cyclases (QC) catalyze the intramolecular cyclization of N-terminal glutamine residues of peptides and proteins. For a comparison of the substrate specificity of human and papaya QC enzymes, a novel continuous assay was established by adapting an existing discontinuous method. Specificity constants (kcat/Km) of dipeptides and dipeptide surrogates were higher for plant QC, whereas the selectivity for oligopeptides was similar for both enzymes. However, only the specificity constants of mammalian QC were dependent on size and composition of the substrates. Specificity constants of both enzymes were equally pH-dependent in the acidic pH-region, revealing a pKa value identical to the pKa of the substrate, suggesting similarities in the substrate conversion mode. Accordingly, both QCs converted the L-?homoglutaminyl residue in the peptide H-?homoGln-Phe-Lys-Arg-Leu-Ala-NH2 and the glutaminyl residues of the branched peptide H-Gln-Lys(Gln)-Arg-Leu-Ala-NH2 as well as the partially cyclized peptide H-Gln-cyclo( N?-Lys-Arg-Pro-Ala-Gly-Phe). In contrast, only QC from C. papaya was able to cyclize a methylated glutamine residue, while this compound did not even inhibit human QC-catalysis, suggesting distinct substrate recognition pattern. The conversion of the potential physiological substrates gastrin, neurotensin and [GlN1]-fertilization promoting peptide indicates that human QC may play a key role in posttranslational modification of most if not all pGlu-containing hormones. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2116 TI - Identification of Human Glutaminyl Cyclase as a Metalloenzyme JO - J. Biol. Chem. PY - 2003 SP - 49773-49779 AU - Schilling, S. AU - Niestroj, A. J. AU - Rahfeld, J.-U. AU - Hoffmann, T. AU - Wermann, M. AU - Zunkel, K. AU - Wasternack, C. AU - Demuth, H.-U. AU - VL - 278 UR - DO - 10.1074/jbc.M309077200 AB - Human glutaminyl cyclase (QC) was identified as a metalloenzyme as suggested by the time-dependent inhibition by the heterocyclic chelators 1,10-phenanthroline and dipicolinic acid. The effect of EDTA on QC catalysis was negligible. Inactivated enzyme could be fully restored by the addition of Zn2+ in the presence of equimolar concentrations of EDTA. Little reactivation was observed with Co2+ and Mn2+. Other metal ions such as K+, Ca2+, and Ni2+ were inactive under the same conditions. Additionally, imidazole and imidazole derivatives were identified as competitive inhibitors of QC. An initial structure activity-based inhibitor screening of imidazole-derived compounds revealed potent inhibition of QC by imidazole N-1 derivatives. Subsequent data base screening led to the identification of two highly potent inhibitors, 3-[3-(1H-imidazol-1-yl)propyl]-2-thioxoimidazolidin-4-one and 1,4-bis-(imidazol-1-yl)-methyl-2,5-dimethylbenzene, which exhibited respective Ki values of 818 ± 1 and 295 ± 5 nm. The binding properties of the imidazole derivatives were further analyzed by the pH dependence of QC inhibition. The kinetically obtained pKa values of 6.94 ± 0.02, 6.93 ± 0.03, and 5.60 ± 0.05 for imidazole, methylimidazole, and benzimidazole, respectively, match the values obtained by titrimetric pKa determination, indicating the requirement for an unprotonated nitrogen for binding to QC. Similarly, the pH dependence of the kinetic parameter Km for the QC-catalyzed conversion of H-Gln-7-ami-no-4-methylcoumarin also implies that only N-terminally unprotonated substrate molecules are bound to the active site of the enzyme, whereas turnover is not affected. The results reveal human QC as a metal-dependent transferase, suggesting that the active site-bound metal is a potential site for interaction with novel, highly potent competitive inhibitors. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2111 TI - Identification of genetically linked RGAs by BAC screening in maize and implications for gene cloning, mapping and MAS JO - Theor. Appl. Genet. PY - 2003 SP - 1171-1177 AU - Quint, M. AU - Dußle, C. M. AU - Melchinger, A. E. AU - Lübberstedt, T. AU - VL - 106 UR - DO - 10.1007/s00122-002-1105-z AB - The resistance gene analogue (RGA) pic19 in maize, a candidate for sugarcane mosaic virus (SCMV) resistance gene (R gene) Scmv1, was used to screen a maize BAC library to identify homologous sequences in the maize genome and to investigate their genomic organisation. Fifteen positive BAC clones were identified and could be classified into five physically independent contigs consisting of overlapping clones. Genetic mapping clustered three contigs into the same genomic region as Scmv1 on chromosome 6S. The two remaining contigs mapped to the same region as a QTL for SCMV resistance on chromosome 1. Thus, RGAs mapping to a target region can be successfully used to identify further-linked candidate sequences. The pic19 homologous sequences of these clones revealed a sequence similarity of 94–98% on the nucleotide level. The high sequence similarity reveals potential problems for the use of RGAs as molecular markers. Their application in marker-assisted selection (MAS) and the construction of high-density genetic maps is complicated by the existence of closely linked homologues resulting in 'ghost' marker loci analogous to 'ghost' QTLs. Therefore, implementation of genomic library screening, including genetic mapping of potential homologues, seems necessary for the safe application of RGA markers in MAS and gene isolation. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2106 TI - Multiple Hormones Act Sequentially to Mediate a Susceptible Tomato Pathogen Defense Response JO - Plant Physiol. PY - 2003 SP - 1181-1189 AU - O'Donnell, P. J. AU - Schmelz, E. AU - Block, A. AU - Miersch, O. AU - Wasternack, C. AU - Jones, J. B. AU - Klee, H. J. AU - VL - 133 UR - DO - 10.1104/pp.103.030379 AB - Phytohormones regulate plant responses to a wide range of biotic and abiotic stresses. How a limited number of hormones differentially mediate individual stress responses is not understood. We have used one such response, the compatible interaction of tomato (Lycopersicon esculentum) and Xanthomonas campestris pv vesicatoria (Xcv), to examine the interactions of jasmonic acid (JA), ethylene, and salicylic acid (SA). The role of JA was assessed using an antisense allene oxide cyclase transgenic line and the def1 mutant to suppress Xcv-induced biosynthesis of jasmonates. Xcv growth was limited in these lines as was subsequent disease symptom development. No increase in JA was detected before the onset of terminal necrosis. The lack of a detectable increase in JA may indicate that an oxylipin other than JA regulates basal resistance and symptom proliferation. Alternatively, there may be an increase in sensitivity to JA or related compounds following infection. Hormone measurements showed that the oxylipin signal must precede subsequent increases in ethylene and SA accumulation. Tomato thus actively regulates the Xcv-induced disease response via the sequential action of at least three hormones, promoting expansive cell death of its own tissue. This sequential action of jasmonate, ethylene, and SA in disease symptom development is different from the hormone interactions observed in many other plant-pathogen interactions. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2104 TI - Citrus psorosis virus RNA 1 is of negative polarity and potentially encodes in its complementary strand a 24K protein of unknown function and 280K putative RNA dependent RNA polymerase JO - Virus Res. PY - 2003 SP - 49-61 AU - Naum-Onganı́a, G. AU - Gago-Zachert, S. AU - Peña, E. AU - Grau, O. AU - Laura Garcia, M. AU - VL - 96 UR - DO - 10.1016/S0168-1702(03)00172-2 AB - Citrus psorosis virus (CPsV), the type member of genus Ophiovirus, has three genomic RNAs. Complete sequencing of CPsV RNA 1 revealed a size of 8184 nucleotides and Northern blot hybridization with chain specific probes showed that its non-coding strand is preferentially encapsidated. The complementary strand of RNA 1 contains two open reading frames (ORFs) separated by a 109-nt intergenic region, one located near the 5′-end potentially encoding a 24K protein of unknown function, and another of 280K containing the core polymerase motifs characteristic of viral RNA-dependent RNA polymerases (RdRp). Comparison of the core RdRp motifs of negative-stranded RNA viruses, supports grouping CPsV, Ranunculus white mottle virus (RWMV) and Mirafiori lettuce virus (MiLV) within the same genus (Ophiovirus), constituting a monophyletic group separated from all other negative-stranded RNA viruses. Furthermore, RNAs 1 of MiLV, CPsV and RWMV are similar in size and those of MiLV and CPsV also in genomic organization and sequence. A2 - C1 - Molecular Signal Processing ER - TY - JOUR ID - 2102 TI - Novel plasmid vectors for homologous transformation of barley (Hordeum vulgare L.) with JIP23 cDNA in sense and antisense orientation JO - Cereal Res. Commun. PY - 2003 SP - 17-24 AU - Monostori, T. AU - Schulze, J. AU - Sharma, V. K. AU - Maucher, H. AU - Wasternack, C. AU - Hause, B. AU - VL - 31 UR - DO - 10.1007/BF03543245 AB - The most abundant jasmonate-induced protein (JIP) in barley leaves is a 23 kDa protein (JIP23). Its function, however, is unknown. In order to analyze its function by homologous transformation, new plasmid vectors have been constructed. They carry the cDNA coding for JIP23 in sense or antisense orientation under the control of the Ubi-1-promoter as well as the pat resistance gene under the control of the 35S promoter. Barley mesophyll protoplasts were transiently transformed with the sense constructs. PAT activity and immunological detection of JIP23 could be achieved in transformed protoplasts but not in untransformed protoplasts indicating that the construct was active. Thus, these new vectors are suitable for stable transformation of barley. Carrying a multiple cloning site (MCS), these vectors can be used now in a wide range of transformation of barley. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - CHAP ID - 149 TI - Shift in Fatty Acid and Oxylipin Pattern of Tomato Leaves Following Overexpression of the Allene Oxide Cyclase T2 - Advanced Research on Plant Lipids PB - PY - 2003 SP - 275-278 AU - Weichert, H. AU - Maucher, H. AU - Hornung, E. AU - Wasternack, C. AU - Feussner, I. AU - VL - UR - DO - 10.1007/978-94-017-0159-4_64 AB - Polyunsaturated fatty acids (PUFAs) are a source of numerous oxidation products, the oxylipins. In leaves, α-linolenic acid (α-LeA) is the preferential substrate for lipid peroxidation reactions. This reaction may be catalyzed either by a 9-lipoxygenase (9-LOX) or by a 13-LOX and oxygen is inserted regioselectively as well as stereospecifically leading to formation of 13S- or 9S-hydroperoxy octadecatrienoic acid (13-/9-HPOT; Brash, 1999). At least, seven different enzyme families or reaction branches within the LOX pathway can use these HPOTs or other hydroperoxy PUFAs leading to (i) keto-PUFAs (LOX); (ii) epoxy hydroxy-PUFAs (epoxy alcohol synthase, EAS); (iii) octadecanoids and jasmonates (allene oxide synthase, AOS); (iv) leaf aldehydes and leaf alcohols (hydroperoxide lyase, HPL); (v) hydroxy PUFAs (reductase); (vi) divinyl ether PUFAs (divinyl ether synthase, DES); and (vii) epoxy- or dihydrodiol-PUFAs (peroxygenase, PDX; Fig. 1; Feussner and Wasternack, 2002). A2 - C1 - Molecular Signal Processing ER - TY - CHAP ID - 147 TI - The Lipoxygenase Pathway in Mycorrhizal Roots of Medicago Truncatula T2 - Advanced Research on Plant Lipids PB - PY - 2003 SP - 287-290 AU - Stumpe, M. AU - Stenzel, I. AU - Weichert, H. AU - Hause, B. AU - Feussner, I. AU - VL - UR - DO - 10.1007/978-94-017-0159-4_67 AB - Mycorrhizas are by far the most frequent occurring beneficial symbiotic interactions between plants and fungi. Species in >80% of extant plant families are capable of establishing an arbuscular mycorrhiza (AM). In relation to the development of the symbiosis the first molecular modifications are those associated with plant defense responses, which seem to be locally suppressed to levels compatible with symbiotic interaction (Gianinazzi-Pearson, 1996). AM symbiosis can, however, reduce root disease caused by several soil-borne pathogens. The mechanisms underlying this protective effect are still not well understood. In plants, products of the enzyme lipoxygenase (LOX) and the corresponding downstream enzymes, collectively named LOX pathway (Fig. 1B), are involved in wound healing, pest resistance, and signaling, or they have antimicrobial and antifungal activity (Feussner and Wasternack, 2002). The central reaction in this pathway is catalyzed by LOXs leading to formation of either 9- or 13-hydroperoxy octadeca(di/trien)oic acids (9/13-HPO(D/T); Brash, 1999). Thus LOXs may be divided into 9- and 13-LOXs (Fig. 1A). Seven different reaction branches within this pathway can use these hydroperoxy polyenoic fatty acids (PUFAs) leading to (i) keto PUFAs by a LOX; (ii) epoxy hydroxy-fatty acids by an epoxy alcohol synthase (EAS); (iii) octadecanoids and jasmonates via allene oxide synthase (AOS); (iv) leaf aldehydes and leaf alcohols via fatty acid hydroperoxide lyase (HPL); (v) hydroxy PUFAs (reductase); (vi) divinyl ether PUFAs via divinyl ether synthase (DES); and (vii) epoxy- or dihydrodiolPUFAs via peroxygenase (PDX; Feussner and Wasternack, 2002). AOS, HPL and DES belong to one subfamily of P450-containing enzymes, the CYP74 family (Feussner and Wasternack, 2002). Here, the involvement of this CYP74 enzyme family in mycorrhizal roots of M. truncatula during early stages of AM symbiosis formation was analyzed. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER - TY - CHAP ID - 145 TI - Transcriptional Activation of Jasmonate Biosynthesis Enzymes is not Reflected at Protein Level T2 - Advanced Research on Plant Lipids PB - PY - 2003 SP - 267-270 AU - Stenzel, I. AU - Hause, B. AU - Feussner, I. AU - Wasternack, C. AU - VL - UR - DO - 10.1007/978-94-017-0159-4_62 AB - Jasmonic acid (JA) and its precursor 12-oxo phytodienoic acid (OPDA) are lipid-derived signals in plant stress responses and development (Wasternack and Hause, 2002). Within the wound-response pathway of tomato, a local response of expression of defense genes such as the proteinase inhibitor 2 gene (PIN2) is preceded by a rise in JA (Herde et al., 1996; Howe et al., 1996) and ethylene (O’Donnell et al., 1996). Mutants affected in JA biosynthesis such as defl (Howe et al., 1996) or spr-2 (Li et al., 2002) clearly indicated that JA biosynthesis is an ultimate part of wound signaling. It is less understood, however, how the rise in JA is regulated. A2 - C1 - Molecular Signal Processing; Cell and Metabolic Biology ER -