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Carol L. Bender - One of the best experts on this subject based on the ideXlab platform.
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Coronatine and Abscission in Citrus
Journal of the American Society for Horticultural Science, 2003Co-Authors: Jacqueline K. Burns, Luis Pozo, Covadonga R. Arias, Brandon Hockema, Vidhya Rangaswamy, Carol L. BenderAbstract:Coronatine is a polyketide phytotoxin produced by several plant pathogenic Pseudomonas spp. The effect of Coronatine on abscission in Citrus sinensis L. Osbeck 'Hamlinʼ and 'Valenciaʼ orange fruit, leaves, fruitlets, and fl owers was determined. Coronatine at 200 mg·L-1 signifi cantly reduced fruit detachment force of mature fruit, and did not cause fruitlet or fl ower loss in 'Valenciaʼ. Cumulative leaf loss was 18% with Coronatine treatment. Coronafacic acid or coronamic acid, precursors to Coronatine in Pseudomonas syringae, did not cause mature fruit abscission. Ethylene production in mature fruit and leaves was stimulated by Coronatine treatment, and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and 12-oxo-phytodienoate reductase (12-oxo-PDAR) gene expression was upregulated. A slight chlorosis developed in the canopy of whole trees sprayed with Coronatine, and chlorophyll content was reduced rela- tive to adjuvant-treated controls. Leaves formed after Coronatine application were not chlorotic and had chlorophyll contents similar to controls. Comparison of Coronatine to the abscission compounds methyl jasmonate, 5-chloro-3- methyl-4-nitro-pyrazole and ethephon indicated differences in ethylene production and ACO and 12-oxo-PDAR gene expression between treatments. Leaf loss, chlorophyll reduction and low Coronatine yield during fermentation must be overcome for Coronatine to be seriously considered as an abscission material for citrus. Coronatine is a polyketide phytotoxin produced by several plant pathogenic Pseudomonas spp. (Mitchell 1982; Volksch and Wein- gart 1998). In compatible host-pathogen interactions, Coronatine was associated with virulence and symptom development. Coro- natine induces a diffuse nonhost-specifi c chlorosis after application
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Pseudomonas syringae Phytotoxins: Mode of Action, Regulation, and Biosynthesis by Peptide and Polyketide Synthetases
Microbiology and molecular biology reviews : MMBR, 1999Co-Authors: Carol L. Bender, Francisco Alarcón-chaidez, Dennis C. GrossAbstract:Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. Syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. Tabtoxin and phaseolotoxin are strongly antimicrobial and function by inhibiting glutamine synthetase and ornithine carbamoyltransferase, respectively. Genetic analysis has revealed the mechanisms responsible for toxin biosynthesis. Coronatine biosynthesis requires the cooperation of polyketide and peptide synthetases for the assembly of the coronafacic and coronamic acid moieties, respectively. Tabtoxin is derived from the lysine biosynthetic pathway, whereas syringomycin, syringopeptin, and phaseolotoxin biosynthesis requires peptide synthetases. Activation of phytotoxin synthesis is controlled by diverse environmental factors including plant signal molecules and temperature. Genes involved in the regulation of phytotoxin synthesis have been located within the Coronatine and syringomycin gene clusters; however, additional regulatory genes are required for the synthesis of these and other phytotoxins. Global regulatory genes such as gacS modulate phytotoxin production in certain pathovars, indicating the complexity of the regulatory circuits controlling phytotoxin synthesis. The Coronatine and syringomycin gene clusters have been intensively characterized and show potential for constructing modified polyketides and peptides. Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the Coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents.
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Chlorosis-inducing Phytotoxins Produced by Pseudomonas syringae
European Journal of Plant Pathology, 1999Co-Authors: Carol L. BenderAbstract:Pseudomonas syringae causes a wide range of symptoms on plants including blights, leaf spots, and galls. Phytotoxins generally enhance the virulence of phytopathogenic P. syringae, and their synthesis can substantially increase disease severity. Although several P. syringae phytotoxins cause chlorosis (Coronatine, phaseolotoxin, and tabtoxin), they are synthesized by unrelated biosynthetic pathways and have completely different modes of action. Phaseolotoxin and tabtoxin inhibit ornithine carbamoyltransferase and glutamine synthetase, respectively, whereas Coronatine functions as a mimic of methyl jasmonate in some plant species. This review focusses on the mode of action, genetics, biosynthesis and regulation of Coronatine, tabtoxin, and phaseolotoxin. Current techniques used to detect these toxins and phytotoxin-producing P. syringae pathovars are discussed. The utilization of toxin resistance genes in the development of transgenic plants with phytotoxin tolerance is also reviewed.
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Use of Tn5-gusA5 to investigate environmental and nutritional effects on gene expression in the Coronatine biosynthetic gene cluster of Pseudomonas syringae pv. glycinea
Canadian journal of microbiology, 1997Co-Authors: David A. Palmer, Carol L. Bender, Shashi B. SharmaAbstract:Pseudomonas syringae pv. glycinea PG4180 produces Coronatine (COR), a chlorosis-inducing phytotoxin that consists of the polyketide coronafacic acid (CFA) coupled via an amide bond to the ethylcyclopropyl amino acid coronamic acid (CMA). Both CFA and CMA function as intermediates in the pathway to Coronatine, and genes encoding their synthesis have been localized; however, the precise factors that regulate the production of COR and its precursors remain unclear. In the present study, a λ delivery system for Tn5-gusA5 was developed and used to obtain transcriptional fusions in the COR gene cluster. Selected carbon (fructose and xylose) and amino acid (isoleucine and valine) sources significantly decreased COR biosynthesis at the transcriptional level. Transcriptional activity in the COR gene cluster was temperature dependent with maximal expression at 18–24 °C and significantly less expression at 14 and 30 °C. Interestingly, changes in osmolarity and the addition of complex carbon and nitrogen sources to t...
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Identification and relatedness of Coronatine-producing Pseudomonas syringae pathovars by PCR analysis and sequence determination of the amplification products.
Applied and environmental microbiology, 1994Co-Authors: Stefan Bereswill, Peter Bugert, Beate Völksch, Matthias S. Ullrich, Carol L. Bender, Klaus GeiderAbstract:Production of the chlorosis-inducing phytotoxin Coronatine in the Pseudomonas syringae pathovars atropurpurea, glycinea, maculicola, morsprunorum, and tomato has been previously reported. DNA hybridization studies previously indicated that the Coronatine biosynthetic gene cluster is highly conserved among P. syringae strains which produce the toxin. In the present study, two 17-bp oligonucleotide primers derived from the Coronatine biosynthetic gene cluster of P. syringae pv. glycinea PG4180 were investigated for their ability to detect Coronatine-producing P. syringae strains by PCR analysis. The primer set amplified diagnostic 0.65-kb PCR products from genomic DNAs of five different Coronatine-producing pathovars of P. syringae. The 0.65-kb products were not detected when PCR experiments utilized nucleic acids of nonproducers of Coronatine or those of bacteria not previously investigated for Coronatine production. When the 0.65-kb PCR products were digested with ClaI, PstI, and SmaI, fragments of identical size were obtained for the five different pathovars of P. syringae. A restriction fragment length polymorphism was detected in the amplified region of P. syringae pv. atropurpurea, since this pathovar lacked a conserved PvuI site which was detected in the PCR products of the other four pathovars. The 0.65-kb PCR products from six strains comprising five different pathovars of P. syringae were cloned and sequenced. The PCR products from two different P. syringae pv. glycinea strains contained identical DNA sequences, and these showed relatedness to the sequence obtained for the pathovar morsprunorum. The PCR products obtained from the pathovars maculicola and tomato were the most similar to each other, which supports the hypothesis that these two pathovars are closely related.(ABSTRACT TRUNCATED AT 250 WORDS) Images
Robin E. Mitchell - One of the best experts on this subject based on the ideXlab platform.
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Production of Anti-idiotypic Monoclonal Antibody Mimics for Coronatine
Food and Agricultural Immunology, 2002Co-Authors: William T. Jones, Dawn Harvey, Robin E. MitchellAbstract:Coronatine (COR) is composed of two structural components, coronafacic acid (CFA) and the amino acid coronamic acid (CMA), which are joined by an amide bond. Monoclonal anti-idiotypic antibodies were prepared and used in competitive ELISAs. Monoclonal antibodies (MAbs) were secreted by hybridoma cell lines prepared from mice immunized with two different idiotypic MAbs, 11B8 and 11G8 that predominantly recognized the CMA or CFA residues, respectively. Hybridoma cell lines secreting high affinity MAbs 4D5 (anti 11B8) and 4H10 (anti 11G8) were isolated. MAb 4D5 predominantly mimicked the coronamyl amide features of Coronatine whereas 4H10 mimicked the coronafacoyl amide of COR. Immunoassays were developed using each of these antibodies. COR could be quantified in the range 1-1000 ngml m 1 (limit of detection
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Coronamic acid, an intermediate in Coronatine biosynthesis by Pseudomonas syringae
Phytochemistry, 1994Co-Authors: Robin E. Mitchell, Scott A. Young, Carol L. BenderAbstract:Abstract Experiments were undertaken on the biosynthetic pathway to Coronatine in Pseudomonas syringae pv. glycinea, using mutants blocked in Coronatine synthesis, wild type strains and radioactive labelling with l -[U-14C] isoleucine and 14C-coronamic acid. Evaluation of the kinetics of Coronatine appearance in the medium revealed an initial exponential phase with a maximum rate of 0.86 μmol hr− 1 culture− 1 after 3.1 days growth. Beyond this the rate declined to a steady rate of 0.20 μmol hr− 1 culturet $ 1. With P. syringae 4185, 8.6% Of l -[U-14C] isoleucine added at three days growth was incorporated into Coronatine during a 90 min exposure period. At the same time there was negligible incorporation (0.04%) to coronamic acid. Two mutants blocked in Coronatine synthesis were shown to produce coronamic acid by isolation and purification of this product from culture supernatants. l -[U-14C]Isoleucine was added to one of these mutants at four days growth and 1.9% of the radioactivity was incorporated into coronamic acid, these data showed that coronamic acid is a distinct biosynthetic entity. However, the Coronatine-producing strain from which these mutants were derived, P. syringae 4180, showed only 0.08% incorporation into a coronamic acid fraction, although culture supernatants after five days growth did reveal a trace of coronamic acid as detected by ninhydrin after electrophoresis and chromatography on thin layer cellulose plates. When a three-day culture of P. syringae 4185 was fed coronamic acid prior to 14C-isoleucine, a 3.7-fold reduction in the incorporation of label into Coronatine occurred; instead the radioactivity was diverted to extracelluar coronamic acid which showed 7% incorporation. This result demonstrates that coronamic acid is a biosynthetic intermediate of Coronatine. Pseudomonas syringae 4185 very efficiently utilized 14C-coronamic acid, giving 94% incorporation into Coronatine after 90 min exposure in a four-day culture, showing the specific utilization of this compound. Other experiments were undertaken to evaluate the possible involvement of coronafacoylisoleucines in the biosynthesis of Coronatine, by use of a cormutant blocked in coronafacic acid synthesis, with the conclusion that this was not an operative pathway to Coronatine.
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Physical and functional characterization of the gene cluster encoding the polyketide phytotoxin Coronatine in Pseudomonas syringae pv. glycinea.
Journal of bacteriology, 1992Co-Authors: S A Young, Robin E. Mitchell, S K Park, C Rodgers, Carol L. BenderAbstract:Pseudomonas syringae pv. glycinea PG4180 produces the polyketide phytotoxin Coronatine. The Coronatine synthesis genes in PG4180 were previously shown to reside on a 90-kb plasmid designated p4180A. In the present study, clones containing a 34-kb region of p4180A were saturated with Tn5, and 71 unique mutations were recombined into p4180A by marker exchange. The effect of each mutation on Coronatine synthesis was determined by analyzing the organic acids produced by the mutants by reverse-phase high-performance liquid chromatography. The organic acids of selected mutants were derivatized to their methyl esters and analyzed by gas chromatography and gas chromatography-mass spectrometry. Mutations in a 20.5-kb region of p4180A completely blocked the synthesis of coronafacic acid and Coronatine. Mutations within a 4.4-kb region of p4180A prevented the formation of Coronatine but allowed for production of coronafacic acid, coronafacoylvaline, coronafacoylisoleucine, and coronafacoylalloisoleucine. The phenotypes of selected mutants were further confirmed in feeding experiments in which coronafacic acid or coronamic acid was added to the culture media. The results of this study allow us to speculate on the likely sequence of steps in the later stages of Coronatine biosynthesis.
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Conservation of plasmid DNA sequences in Coronatine-producing pathovars of Pseudomonas syringae.
Applied and environmental microbiology, 1991Co-Authors: Carol L. Bender, Scott A. Young, Robin E. MitchellAbstract:In Pseudomonas syringae pv. tomato PT23.2, plasmid pPT23A (101 kb) is involved in synthesis of the phytotoxin Coronatine. The physical characterization of mutations that abolished Coronatine production indicated that at least 30 kb of pPT23A DNA are required for toxin synthesis. In the present study, {sup 32}P-labeled DNA fragments from the 30-kb region of pPT23A hybridized to plasmid DNAs from several Coronatine-producing pathovars of P. syringae under conditions of high stringency. These experiments indicated that this region of pPT23A was strongly conserved in large plasmids (90 to 105 kb) that reside in P. syringae pv. atropurpurea, glycinea, and morsprunorum. The functional significance of the observed homology was demonstrated in marker-exchange experiments in which Tn5-inactivated sequences from the 30-kb region of pPT23A were used to mutate Coronatine synthesis genes in the three heterologous pathovars. Physical characterization of the Tn5 insertions generated by marker exchange indicated that genes controlling Coronatine synthesis in P. syringae pv. atropurpurea 1304, glycinea 4180, and morsprunorum 567 and 3714 were located on the large indigenous plasmids where homology was originally detected. Therefore, Coronatine biosynthesis genes are strongly conserved in the plasmid DNAs of four producing pathovars, despite their disparate origins (California, Japan, New Zealand, Great Britain, andmore » Italy).« less
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Coronatine analogues produced by Xanthomonas campestris pv Phormiicola
Phytochemistry, 1991Co-Authors: Robin E. MitchellAbstract:Abstract Liquid cultures of Xanthomonas campestris pv phormiicola were found to contain two analogues of Coronatine lacking the cyclopropane ring structure, and no trace of either Coronatine or norCoronatine. The two compounds were isolated and fully characterised by NMR, MS, hydrolysis and GC of hydrolysis products, as N -coronafacoyl- l -valine and N -coronafacoyl- l -isoleucine. A survey of 12 strains from 10 other X. campestris pathovars did not locate another source of production of these compounds, whereas all three strains of X. campestris pv phormiicola examined produced comparable levels of both compounds. This is the first report of phytotoxins biosynthetically derived from coronafacic acid outside of the genus Pseudomonas . The implications of these findings to the biosynthesis of the cyclopropane ring structure of Coronatine are discussed.
Liusheng Duan - One of the best experts on this subject based on the ideXlab platform.
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Data-Independent Acquisition Proteomics Unravels the Effects of Iron Ions on Coronatine Synthesis in Pseudomonas syringae pv. tomato DC3000.
Frontiers in microbiology, 2020Co-Authors: Liu Shaojin, Hao Tian, Yu Chunxin, Weiming Tan, Jie Zhang, Jiang Feng, Liusheng DuanAbstract:Coronatine (COR) is a new type of plant growth regulator that is produced by Pseudomonas syringae pathovars and plays an important role in modulating plant growth, development, and tolerance to multiple stresses, but the factors affecting Coronatine production are not very clear. In this study, the effects of FeCl3 on the yield of Coronatine was researched and the independent data acquisition (DIA) approach, which is a proteomic quantitative analysis method, was applied to quantitatively trace Coronatine production and proteomic changes in Pseudomonas syringae pv. tomato DC3000 under different FeCl3 culture conditions. The results showed that Coronatine production increased with the addition of FeCl3, and that there was significant upregulation in the expression of proteins related to Coronatine synthesis and regulation. In addition, FeCl3 also affected the expression of related proteins involved in various metabolic pathways such as glycolysis and the tricarboxylic acid (TCA) cycle. Moreover, various precursors such as isoleucine and succinate semialdehyde, as well as other related proteins involved in the Coronatine synthesis pathway were significantly differentially expressed. Our findings revealed the dynamic regulation of Coronatine production by FeCl3 at the protein level, and proved the potential of using the DIA method to track the dynamic changes of the Pseudomonas syringae pv. tomato DC3000 proteome during Coronatine production, providing an important reference for future research on the regulatory mechanism of Coronatine biosynthesis and theoretical support for Coronatine fermentation production.
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Coronatine inhibits mesocotyl elongation by promoting ethylene production in etiolated maize seedlings
Plant Growth Regulation, 2019Co-Authors: Yingru Liu, Yuyi Zhou, Guanmin Huang, Nana Zhu, Mingcai Zhang, Liusheng DuanAbstract:Maize (Zea mays L.) is one of the most important cereal crops in the world. In order to survive, plants must regulate their growth in response to multiple developmental and environmental cues, including modulating lodging stress. Coronatine is a chlorosis-inducing non-host-specific phytotoxin produced by several members of the Pseudomonas syringe group of pathovars, which can lead to leaf chlorosis, anthocyanin production, and growth inhibition. In this study, we investigated the physiological mechanism for Coronatine during maize mesocotyl growth and development. Using ethephon as a positive control, we found that Coronatine inhibited the elongation of mesocotyls in maize B73 etiolated seedlings which was related to ethylene production. Both Coronatine and ethephon increased mesocotyls coarsening by increasing the cell diameter and shortened it by inhibiting cell elongation. Coronatine also thickened cell walls in longitudinal and transverse sections by increasing the expression of the cellulose lignin synthesis gene ZmEXT. To further verify the correlation between Coronatine and ethephon during mesocotyl growth, we detected the release of endogenous ethylene and the expression of ZmACOs and ZmACSs. We found that Coronatine increased the ethylene production while inhibiting auxin synthesis, thereby inhibiting mesocotyl growth.
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Phytotoxin Coronatine enhances heat tolerance via maintaining photosynthetic performance in wheat based on Electrophoresis and TOF-MS analysis
Scientific reports, 2015Co-Authors: Yuyi Zhou, Mingcai Zhang, Xiaoli Tian, Liusheng DuanAbstract:Coronatine (COR) is a phytotoxin produced by Pseudomonas syringae. Its structure is similar to Jasmonates, which play a number of diverse roles in plant defense. Both have the COI1 plant receptor, so Coronatine can manipulate plant hormone signaling to access nutrients and counteract defense responses. In addition to the hormone system, Coronatine affects plant nitrogenous metabolism and chloroplast ultrastructure. In this study, we first examined a typical nitrogen-losing phenotype, and used the polyacrylamide gel approach to demonstrate soluble total protein patterns in a time-course experiment under different temperature conditions. We then employed dimensional gel electrophoresis technology (2-DE) and MALDI-TOF-MS to sequester and identify the sensitive proteins. We found a total of 27 Coronatine sensitive proteins, 22 of which were located in the chloroplast and 6 of which were directly involved in photosynthesis. Finally, we measured levels of chlorophyll and photosynthetic performance to reveal the phenotypic effect of these proteins. Taken together, these results demonstrated that Coronatine enhanced heat tolerance by regulating nitrogenous metabolism and chloroplast ultrastructure to maintain photosynthetic performance and reduce yield loss under heat stress.
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Effects of dapA gene deletion on Coronatine biosynthesis in Pseudomonas syringae pv. glycinea PG4180
World Journal of Microbiology and Biotechnology, 2010Co-Authors: Jiachang Zhang, Liusheng Duan, A. Egrinya Eneji, Bo ZhangAbstract:Coronatine (COR) is a structural and functional analogue of jasmonic acid that might be employed in agriculture to elicit plant resistance against various aggressors. However, the yield of COR is low both in chemosynthesis and biosynthesis, so broad investigation of COR is difficult. Coronatine combines two distinct components: coronafacic acid (CFA) and coronamic acid (CMA). Synthesis of both CMA and CFA is involved in l-isoleucine metabolism, so the objective of this work was to investigate if COR production can be improved by regulating amino acid biosynthesis in P. syringae pv. glycinea. Inhibition of dihydrodipicolinate synthase was achieved by removing the dapA gene via homologous recombination, which resulted in a COR yield by the dapA − mutant of about 1.5-fold greater than the wild strain. Thus, regulation of amino acid metabolism is a feasible way to increase COR production, which could be a more effective method than adding substrates into culture medium.
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Effects of Coronatine on Growth, Gas Exchange Traits, Chlorophyll Content, Antioxidant Enzymes and Lipid Peroxidation in Maize (Zea mays L.) Seedlings under Simulated Drought Stress
Plant Production Science, 2008Co-Authors: Baoqing Wang, Xiaoli Tian, A. Egrinya Eneji, Zhixi Zhai, Liusheng DuanAbstract:Coronatine is a phytotoxin that affects the accumulation of defence-related metabolites in plants but information on how its effects may be mediated by environmental stress is scanty. An experiment...
D A Cuppels - One of the best experts on this subject based on the ideXlab platform.
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Molecular and Physiological Characterization of Pseudomonas syringae pv. tomato and Pseudomonas syringae pv. maculicola Strains That Produce the Phytotoxin Coronatine.
Applied and environmental microbiology, 1995Co-Authors: D A Cuppels, T AinsworthAbstract:The chlorosis-inducing phytotoxin Coronatine is produced by several Pseudomonas syringae pathovars, including glycinea, morsprunorum, atropurpurea, and the closely related tomato and maculicola. To date, all Coronatine-producing pv. glycinea, morsprunorum, and atropurpurea strains that have been examined carry the gene cluster that controls toxin production on a large plasmid. In the present study the genomic location of the Coronatine gene cluster was determined for Coronatine-producing strains of the pv. tomato-maculicola group by subjecting their genomic DNA to pulsed-field electrophoresis and Southern blot analysis with a hybridization probe from the Coronatine gene cluster. The cluster was chromosomally borne in 10 of the 22 strains screened. These 10 strains infected both crucifers and tomatoes but could not use sorbitol as a sole source of carbon. The remaining 12 Coronatine-producing strains had plasmid-borne toxin gene clusters and used sorbitol as a carbon source. Only one of these strains was pathogenic on both crucifers and tomatoes; the remainder infected just tomatoes. Restriction fragment length polymorphism analysis of the pv. tomato-maculicola Coronatine gene clusters was performed with probes from P. syringae pv. tomato DC3000, a tomato and crucifer pathogen. Although the Coronatine cluster appeared, in general, to be highly conserved across the pv. tomato-maculicola group, there were significant differences between plasmid-borne and chromosomally borne genes. The extensively studied Coronatine cluster of pv. glycinea 4180 closely resembled the plasmid-borne clusters of the pv. tomato-maculicola group.
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Characterization of a DNA region required for production of the phytotoxin Coronatine by Pseudomonas syringae pv. tomato
Molecular Plant-Microbe Interactions, 1991Co-Authors: V. L. Morris, D A CuppelsAbstract:The object of this study is to characterize in detail the Coronatine cor genes located on pEC18. Using transposon saturation mutagenesis and functional complementation analysis we have shown that the cor genes of pEC18 are tightly clustered and are organized into several complementation groups
John Turner - One of the best experts on this subject based on the ideXlab platform.
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Coi1-dependent expression of an Arabidopsis vegetative storage protein in flowers and siliques and in response to Coronatine or methyl jasmonate.
Plant physiology, 1995Co-Authors: Celso Eduardo Benedetti, Daoxin Xie, John TurnerAbstract:The phytotoxin Coronatine and the plant growth regulator methyl jasmonate (MeJA) inhibit the growth of Arabidopsis seedlings. Coronatine and MeJA induced the accumulation of an approximately 29-kD protein in wild-type seedlings but not in seedlings of the coi1 mutant, which is insensitive to both compounds. The approximately 29-kD protein was recognized not only by antibodies raised against the partially purified polypeptide, but also by antibodies raised against vegetative storage proteins (VSPs) from soybean (29 kD) and poplar (32 kD). In the absence of added MeJA/Coronatine, the VSP-like protein was highly expressed in flowers and siliques but not in seeds, seedlings, or mature leaves of wild-type Arabidopsis. By contrast, this protein could not be detected in coi1 seedlings treated with Coronatine or MeJA, and it was found in very low levels in the male sterile flowers of coi1. A transcript corresponding to the gene of the Arabidopsis 27-kD VSP precursor shows the same pattern of expression as the VSP-like protein. Significantly, the VSP-like protein was not detected in green siliques or seeds obtained from coi1 flowers fertilized with wild-type pollen. We conclude that the VSP-like protein is normally expressed in maternal tissues, where it is regulated by COI1, but is not essential for the development of siliques.
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Arabidopsis Mutants Selected for Resistance to the Phytotoxin Coronatine Are Male Sterile, Insensitive to Methyl Jasmonate, and Resistant to a Bacterial Pathogen.
The Plant cell, 1994Co-Authors: Bart J. F. Feys, Celso Eduardo Benedetti, Christopher N. Penfold, John TurnerAbstract:The phytotoxin Coronatine and the plant growth regulator methyl jasmonate (MeJA) caused similar growth-inhibitory effects on Arabidopsis seedlings. To test whether these two compounds have similar action, 14 independent coi1 (Coronatine-insensitive) mutants of Arabidopsis were selected. The mutants segregated as single recessive Mendelian markers, and all were alleles at the coi1 locus. All coi1 mutants were also insensitive to MeJA and were male sterile. Both Coronatine and MeJA inhibited root growth, stimulated anthocyanin accumulation, and increased the level of two proteins of ~31 and ~29 kD detected in SDS-polyacrylamide gels of wild-type Arabidopsis but caused none of these effects in the coi1 mutant. Coronatine and MeJA also induced the systemic appearance of proteinase inhibitor activity in tomato. The male-sterile flowers of the coi1 mutant produced abnormal pollen and had reduced level of an ~31-kD protein, which was abundant in the wild-type flowers. A Coronatine-producing strain of Pseudomonas syringae grew in leaves of wild-type Arabidopsis to a population more than 100 times greater than it reached in the coi1 mutant. We conclude that Coronatine mimics the action of MeJA and that coi1 controls a step in MeJA perception/response and in flower development.
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The Stimulation of Ethylene Synthesis in Nicotiana tabacum Leaves by the Phytotoxin Coronatine
Plant physiology, 1992Co-Authors: Janette S. Kenyon, John TurnerAbstract:Coronatine is a chlorosis-inducing toxin produced by the plant pathogen Pseudomonas syringae pv atropurpurea. This bacterium is the causal agent of chocolate spot disease, in which brown lesions with chlorotic margins develop on the leaves of Lolium multiflorum Lam. Among the many physiological changes to plants caused by Coronatine is the stimulation of ethylene production from bean leaves. The ethyl-substituted side chain of Coronatine is an analog of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC). We have examined the question of whether part or all of the released ethylene comes from the breakdown of Coronatine itself. The rate of ethylene release from leaves of Nicotiana tabacum was proportional to the concentration of Coronatine applied to the leaf surface. The lowest effective concentration of Coronatine, applied to leaves at 15 pmol cm−2 of leaf area, resulted in the production of 44 pmol of ethylene cm−2 over a period of 4 h. The maximum rate of ethylene production occurred 28 to 32 h after application of Coronatine. The specific activity of ethylene produced by discs cut from Coronatine-treated Nicotiana tabacum leaves floating on a solution containing 10 mm [U-14C]methionine was consistent with its exclusive origin from methionine. ACC accumulated in the Coronatine-treated tissue. ACC synthase activity increased in Phaseolus aureus hypocotyls during a 6-h treatment with Coronatine. Thus, Coronatine induces the synthesis of ethylene from methionine.
