The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Jonathan Arias - One of the best experts on this subject based on the ideXlab platform.
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Abiotic and biotic Stress differentially stimulate as-1 element activity in Arabidopsis
Plant Cell Reports, 2002Co-Authors: Julia C. Redman, J. Whitcraft, C. Johnson, Jonathan AriasAbstract:As-1-type cis-elements enhance the expression of putative plant protective genes in response to Xenobiotic chemical Stress. Here we investigate the effect of developmental changes on as-1-dependent transcription activities under basal and stimulus-induction conditions. We show that different Xenobiotic Stress cues give rise to distinct, differential patterns of as-1 activity in planta, which are further effected by developmental control. Moreover, transcription through as-1 is potentiated by infection with a virulent strain of Pseudomonas syringae, in line with recent genetic evidence indicating a role for this element and its cognate TGA transcription factors in host-defense gene responses. Our results here are consistent with the notion that inputs from both developmental and stimulus induction pathways define the complex spatial and temporal expression pattern of as-1 activity in plants.
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In vivo target promoter-binding activities of a Xenobiotic Stress-activated TGA factor.
The Plant journal : for cell and molecular biology, 2001Co-Authors: Christopher Johnson, Erin Boden, Mihir Desai, Pete E. Pascuzzi, Jonathan AriasAbstract:Summary Xenobiotic chemicals induce the expression of nuclear detoxification genes. A full understanding of this protective response will require characterization of its transcriptional regulatory machinery. We describe here the use of a recently developed plant chromatin immunoprecipitation (ChIP) assay to define nuclear promoter targets of TGA1a, a tobacco basic/leucine zipper transcription factor whose activity is potentiated by herbicide-induced Xenobiotic Stress. TGA1a selectively binds as-1-type cis-elements, which regulate transcription of putative detoxification and defense genes. With ChIP, we show that endogenous TGA1a binds as-1-containing promoter sequences of two tobacco glutathione S-transferase genes, GNT1 and GNT35. This binding activity is strongly enhanced by Xenobiotic Stress, as is expression of these genes. In contrast, TGA1a apparently does not bind in vivo to functional as-1 elements in promoters of PR-1a and PG13, genes whose expression is insensitive to this stimulus. The findings here thus discriminate between a number of possible functional promoter binding sites for a trans-regulatory factor, within the context of a signal response pathway.
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Regulation of DNA binding and trans-activation by a Xenobiotic Stress-activated plant transcription factor.
The Journal of biological chemistry, 2001Co-Authors: Christopher Johnson, Geraldine Glover, Jonathan AriasAbstract:Abstract As-1-typecis-elements augment transcription of both nuclear and pathogen genes in response to Stress and defense cues in plants. Basic/leucine zipper proteins termed “TGA factors” that specifically bind as-1 elements are likely candidates for mediating these transcription activities. Our earlier work has shown that 2,4-dichlorophenoxyacetic acid-induced Xenobiotic Stress enhancestrans-activation by a chimeric fusion protein of the yeast Gal4 binding domain and TGA1a, a TGA factor of tobacco. Here we demonstrate that Xenobiotic Stress also enhances the ability of native TGA1a to bind as-1 and activate transcription of a known target gene. In addition, the previously identified Xenobiotic Stress-responsive domain of TGA1a was found to inhibit this factor'strans-activation potential by a mechanism that appears to involve stimulus-reversible interactions with a nuclear repressor protein. Results from these and other studies can now be placed in the context of a working model to explain basal and Xenobiotic Stress-induced activities of TGA1a through its cognatecis-acting element.
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Chapter Six Designer basic/leucine-zipper proteins as regulators of plant detoxification genes
Recent Advances in Phytochemistry, 2001Co-Authors: Amir Rahbar, Christopher Johnson, Jonathan AriasAbstract:Publisher Summary This chapter discusses the contribution of plant basic/leucine zipper (bZIP) factors to the transcriptional regulatory processes, with an emphasis on the recent investigations of a tobacco bZIP factor that governs Xenobiotic Stress-activated transcription of detoxification genes. Animal and plant bZIP factors play key regulatory roles in stimulus–response pathways leading to changes in the rate of transcription of protective genes. This chapter illustrates how modifications of a plant bZIP factor can alter its response to stimulus. TGAla is a Xenobiotic Stress-activated bZIP factor of tobacco that activates transcription through as-1 -type cis -elements. Target genes that are regulated by TGAla are those that encode for glutathione- S -transferase (GST) isoenzymes, which are implicated in Xenobiotic detoxification. Investigations are under way to test whether the modified forms of TGAla and other TGA factors can stably affect the expression of these and other protective genes in plants.
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A Xenobiotic-Stress-activated transcription factor and its cognate target genes are preferentially expressed in root tip meristems
Plant Molecular Biology, 2000Co-Authors: Susan Klinedinst, Mihir Desai, Pete Pascuzzi, Julia Redman, Jonathan AriasAbstract:In plants, as-1- type cis elements and their trans- acting factors confer tissue-specific and signal-responsive activities to the promoters of several glutathione S- transferase (GST) genes. Regulation of as-1 is widely thought to involve trans- acting factors that belong to a family of basic/leucine-zipper `TGA factors' that selectively bind this element. We have previously shown that TGA1a, a highly conserved TGA factor of tobacco, enhances transcription through as-1 in response to Xenobiotic-Stress cues. To better understand the functional contribution of this transcription factor to the expression of as-1- regulated genes, we have studied its tissue- and cell-specific localization in tobacco seedlings. We show here that the relative amount of TGA1a transcripts expressed in roots and shoots correlate with the as-1- regulated, basal-level expression of a GUS transgene and two putative target GST genes. In situ hybridization of intact seedlings demonstrated that TGA1a and these GST genes are preferentially expressed in root tip meristems. Similar findings were made with a gene-specific probe for PG13, a homologue of TGA1a, demonstrating that both factors are likely to be present in the same root meristem cells. Furthermore, TGA1a protein was immunologically detected exclusively in the primary root and its meristem. Collectively, these studies suggest that TGA1a, and perhaps PG13, may contribute to the expression of GST isoenzymes, especially in root tip meristems. The biological significance of these observations is discussed.
Gwenola Gouesbet - One of the best experts on this subject based on the ideXlab platform.
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Genome-Wide Transcriptional Profiling and Metabolic Analysis Uncover Multiple Molecular Responses of the Grass Species Lolium perenne Under Low-Intensity Xenobiotic Stress
Frontiers in Plant Science, 2015Co-Authors: Anne-antonella Serra, Cécile Sulmon, Ivan Couée, David Heijnen, Sophie Michon-coudouel, Gwenola GouesbetAbstract:Lolium perenne, which is a major component of pastures, lawns, and grass strips, can be exposed to Xenobiotic Stresses due to diffuse and residual contaminations of soil. L. perenne was recently shown to undergo metabolic adjustments in response to sub-toxic levels of Xenobiotics. To gain insight in such chemical Stress responses, a de novo transcriptome analysis was carried out on leaves from plants subjected at the root level to low levels of Xenobiotics, glyphosate, tebuconazole, and a combination of the two, leading to no adverse physiological effect. Chemical treatments influenced significantly the relative proportions of functional categories and of transcripts related to carbohydrate processes, to signaling, to protein-kinase cascades, such as Serine/Threonine-protein kinases, to transcriptional regulations, to responses to abiotic or biotic stimuli and to responses to phytohormones. Transcriptomics-based expressions of genes encoding different types of SNF1 (sucrose non-fermenting 1)-related kinases involved in sugar and Stress signaling or encoding key metabolic enzymes were in line with specific qRT-PCR analysis or with the important metabolic and regulatory changes revealed by metabolomic analysis. The effects of pesticide treatments on metabolites and gene expression strongly suggest that pesticides at low levels, as single molecule or as mixture, affect cell signaling and functioning even in the absence of major physiological impact. This global analysis of L. perenne therefore highlighted the interactions between molecular regulation of responses to Xenobiotics, and also carbohydrate dynamics, energy dysfunction, phytohormones and calcium signaling.
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Genome-wide interacting effects of sucrose and herbicide-mediated Stress in Arabidopsis thaliana: novel insights into atrazine toxicity and sucrose-induced tolerance.
BMC Genomics, 2007Co-Authors: Fanny Ramel, Cécile Sulmon, Abdelhak El Amrani, Ivan Couée, Jean-pierre Renou, Francisco Cabello-hurtado, Ludivine Taconnat, Marie-laure Martin-magniette, Gwenola GouesbetAbstract:Background: Soluble sugars, which play a central role in plant structure and metabolism, are also involved in the responses to a number of Stresses, and act as metabolite signalling molecules that activate specific or hormone-crosstalk transduction pathways. The different roles of exogenous sucrose in the tolerance of Arabidopsis thaliana plantlets to the herbicide atrazine and oxidative Stress were studied by a transcriptomic approach using CATMA arrays. Results: Parallel situations of Xenobiotic Stress and sucrose-induced tolerance in the presence of atrazine, of sucrose, and of sucrose plus atrazine were compared. These approaches revealed that atrazine affected gene expression and therefore seedling physiology at a much larger scale than previously described, with potential impairment of protein translation and of reactive-oxygen species (ROS) defence mechanisms. Correlatively, sucrose-induced protection against atrazine injury was associated with important modifications of gene expression related to ROS defence mechanisms and repair mechanisms. These protection-related changes of gene expression did not result only from the effects of sucrose itself, but from combined effects of sucrose and atrazine, thus strongly suggesting important interactions of sucrose and Xenobiotic signalling or of sucrose and ROS signalling. Conclusion: These interactions resulted in characteristic differential expression of gene families such as ascorbate peroxidases, glutathione-S-transferases and cytochrome P450s, and in the early induction of an original set of transcription factors. These genes used as molecular markers will eventually be of great importance in the context of Xenobiotic tolerance and phytoremediation.
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Sugar-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses.
Plant cell reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-S-transferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
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Sucrose-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses
Plant Cell Reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-Stransferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
Ivan Couée - One of the best experts on this subject based on the ideXlab platform.
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Genome-Wide Transcriptional Profiling and Metabolic Analysis Uncover Multiple Molecular Responses of the Grass Species Lolium perenne Under Low-Intensity Xenobiotic Stress
Frontiers in Plant Science, 2015Co-Authors: Anne-antonella Serra, Cécile Sulmon, Ivan Couée, David Heijnen, Sophie Michon-coudouel, Gwenola GouesbetAbstract:Lolium perenne, which is a major component of pastures, lawns, and grass strips, can be exposed to Xenobiotic Stresses due to diffuse and residual contaminations of soil. L. perenne was recently shown to undergo metabolic adjustments in response to sub-toxic levels of Xenobiotics. To gain insight in such chemical Stress responses, a de novo transcriptome analysis was carried out on leaves from plants subjected at the root level to low levels of Xenobiotics, glyphosate, tebuconazole, and a combination of the two, leading to no adverse physiological effect. Chemical treatments influenced significantly the relative proportions of functional categories and of transcripts related to carbohydrate processes, to signaling, to protein-kinase cascades, such as Serine/Threonine-protein kinases, to transcriptional regulations, to responses to abiotic or biotic stimuli and to responses to phytohormones. Transcriptomics-based expressions of genes encoding different types of SNF1 (sucrose non-fermenting 1)-related kinases involved in sugar and Stress signaling or encoding key metabolic enzymes were in line with specific qRT-PCR analysis or with the important metabolic and regulatory changes revealed by metabolomic analysis. The effects of pesticide treatments on metabolites and gene expression strongly suggest that pesticides at low levels, as single molecule or as mixture, affect cell signaling and functioning even in the absence of major physiological impact. This global analysis of L. perenne therefore highlighted the interactions between molecular regulation of responses to Xenobiotics, and also carbohydrate dynamics, energy dysfunction, phytohormones and calcium signaling.
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Genome-wide interacting effects of sucrose and herbicide-mediated Stress in Arabidopsis thaliana: novel insights into atrazine toxicity and sucrose-induced tolerance.
BMC Genomics, 2007Co-Authors: Fanny Ramel, Cécile Sulmon, Abdelhak El Amrani, Ivan Couée, Jean-pierre Renou, Francisco Cabello-hurtado, Ludivine Taconnat, Marie-laure Martin-magniette, Gwenola GouesbetAbstract:Background: Soluble sugars, which play a central role in plant structure and metabolism, are also involved in the responses to a number of Stresses, and act as metabolite signalling molecules that activate specific or hormone-crosstalk transduction pathways. The different roles of exogenous sucrose in the tolerance of Arabidopsis thaliana plantlets to the herbicide atrazine and oxidative Stress were studied by a transcriptomic approach using CATMA arrays. Results: Parallel situations of Xenobiotic Stress and sucrose-induced tolerance in the presence of atrazine, of sucrose, and of sucrose plus atrazine were compared. These approaches revealed that atrazine affected gene expression and therefore seedling physiology at a much larger scale than previously described, with potential impairment of protein translation and of reactive-oxygen species (ROS) defence mechanisms. Correlatively, sucrose-induced protection against atrazine injury was associated with important modifications of gene expression related to ROS defence mechanisms and repair mechanisms. These protection-related changes of gene expression did not result only from the effects of sucrose itself, but from combined effects of sucrose and atrazine, thus strongly suggesting important interactions of sucrose and Xenobiotic signalling or of sucrose and ROS signalling. Conclusion: These interactions resulted in characteristic differential expression of gene families such as ascorbate peroxidases, glutathione-S-transferases and cytochrome P450s, and in the early induction of an original set of transcription factors. These genes used as molecular markers will eventually be of great importance in the context of Xenobiotic tolerance and phytoremediation.
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Sugar-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses.
Plant cell reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-S-transferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
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Sucrose-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses
Plant Cell Reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-Stransferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
Cécile Sulmon - One of the best experts on this subject based on the ideXlab platform.
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Genome-Wide Transcriptional Profiling and Metabolic Analysis Uncover Multiple Molecular Responses of the Grass Species Lolium perenne Under Low-Intensity Xenobiotic Stress
Frontiers in Plant Science, 2015Co-Authors: Anne-antonella Serra, Cécile Sulmon, Ivan Couée, David Heijnen, Sophie Michon-coudouel, Gwenola GouesbetAbstract:Lolium perenne, which is a major component of pastures, lawns, and grass strips, can be exposed to Xenobiotic Stresses due to diffuse and residual contaminations of soil. L. perenne was recently shown to undergo metabolic adjustments in response to sub-toxic levels of Xenobiotics. To gain insight in such chemical Stress responses, a de novo transcriptome analysis was carried out on leaves from plants subjected at the root level to low levels of Xenobiotics, glyphosate, tebuconazole, and a combination of the two, leading to no adverse physiological effect. Chemical treatments influenced significantly the relative proportions of functional categories and of transcripts related to carbohydrate processes, to signaling, to protein-kinase cascades, such as Serine/Threonine-protein kinases, to transcriptional regulations, to responses to abiotic or biotic stimuli and to responses to phytohormones. Transcriptomics-based expressions of genes encoding different types of SNF1 (sucrose non-fermenting 1)-related kinases involved in sugar and Stress signaling or encoding key metabolic enzymes were in line with specific qRT-PCR analysis or with the important metabolic and regulatory changes revealed by metabolomic analysis. The effects of pesticide treatments on metabolites and gene expression strongly suggest that pesticides at low levels, as single molecule or as mixture, affect cell signaling and functioning even in the absence of major physiological impact. This global analysis of L. perenne therefore highlighted the interactions between molecular regulation of responses to Xenobiotics, and also carbohydrate dynamics, energy dysfunction, phytohormones and calcium signaling.
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Genome-wide interacting effects of sucrose and herbicide-mediated Stress in Arabidopsis thaliana: novel insights into atrazine toxicity and sucrose-induced tolerance.
BMC Genomics, 2007Co-Authors: Fanny Ramel, Cécile Sulmon, Abdelhak El Amrani, Ivan Couée, Jean-pierre Renou, Francisco Cabello-hurtado, Ludivine Taconnat, Marie-laure Martin-magniette, Gwenola GouesbetAbstract:Background: Soluble sugars, which play a central role in plant structure and metabolism, are also involved in the responses to a number of Stresses, and act as metabolite signalling molecules that activate specific or hormone-crosstalk transduction pathways. The different roles of exogenous sucrose in the tolerance of Arabidopsis thaliana plantlets to the herbicide atrazine and oxidative Stress were studied by a transcriptomic approach using CATMA arrays. Results: Parallel situations of Xenobiotic Stress and sucrose-induced tolerance in the presence of atrazine, of sucrose, and of sucrose plus atrazine were compared. These approaches revealed that atrazine affected gene expression and therefore seedling physiology at a much larger scale than previously described, with potential impairment of protein translation and of reactive-oxygen species (ROS) defence mechanisms. Correlatively, sucrose-induced protection against atrazine injury was associated with important modifications of gene expression related to ROS defence mechanisms and repair mechanisms. These protection-related changes of gene expression did not result only from the effects of sucrose itself, but from combined effects of sucrose and atrazine, thus strongly suggesting important interactions of sucrose and Xenobiotic signalling or of sucrose and ROS signalling. Conclusion: These interactions resulted in characteristic differential expression of gene families such as ascorbate peroxidases, glutathione-S-transferases and cytochrome P450s, and in the early induction of an original set of transcription factors. These genes used as molecular markers will eventually be of great importance in the context of Xenobiotic tolerance and phytoremediation.
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Sugar-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses.
Plant cell reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-S-transferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
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Sucrose-induced tolerance to the herbicide atrazine in Arabidopsis seedlings involves activation of oxidative and Xenobiotic Stress responses
Plant Cell Reports, 2006Co-Authors: Cécile Sulmon, Gwenola Gouesbet, Abdelhak El Amrani, Ivan CouéeAbstract:Exogenous sucrose confers to Arabidopsis seedlings a very high level of tolerance to the herbicide atrazine that cannot be ascribed to photoheterotrophic growth. Important differences of atrazine tolerance between sucrose and glucose treatments showed that activation of chloroplast biogenesis per se could not account for induced tolerance. Sucrose-induced acquisition of defence mechanisms was shown by the gene expression pattern of a chloroplastic iron superoxide dismutase and by enhancement of whole-cell glucose-6-phosphate dehydrogenase activity. Activation of these defence mechanisms depended on both soluble sugar and atrazine. Moreover, acquisition of sucrose protection was shown to unmask atrazine-induced gene expression, such as that of a cytosolic glutathione-Stransferase, which remained otherwise cryptic because of the lethal effects of atrazine in the absence of soluble sugars.
Roger N. F. Thorneley - One of the best experts on this subject based on the ideXlab platform.
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a novel Stress acclimation response in spirodela punctata lemnaceae 2 4 6 trichlorophenol triggers an increase in the level of an extracellular peroxidase capable of the oxidative dechlorination of this Xenobiotic pollutant
Plant Cell and Environment, 2004Co-Authors: Marcel A. K. Jansen, Lionel Hill, Roger N. F. ThorneleyAbstract:Peroxidases are haem-containing enzymes capable of oxidizing a wide range of substrates. This article describes the presence of peroxidase activity in the growth medium of axenic Spirodela punctata (Lemnaceae) cultures. It was found that the release of extracellular peroxidase activity is specifically enhanced by phytotoxic, halogenated phenols but not by other abiotic Stress-factors, elicitors or plant metabolites. Based on the concentration dependence of 2,4,6-trichlorophenol (TCP)-enhanced peroxidase release, it is concluded that release is not simply a consequence of physiological damage, but rather requires metabolically healthy fronds. In vitro studies (UV/VIS spectroscopy and liquid chromatographylmass spectrometry) show that the extracellular duckweed peroxidase (SpEx), which was partially purified from Spirodela growth medium, is capable of catalysing the oxidative dechlorination of TCP with hydrogen peroxide as the electron acceptor. It is proposed that the ability of S. punctata to specifically sense environmentally persistent phytotoxic chlorophenols, and to respond by increasing extracellular levels of a peroxidase capable of catalysing their oxidative dechlorination, is part of the protection strategy of this aquatic plant against Xenobiotic Stress.
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A novel Stress‐acclimation response in Spirodela punctata (Lemnaceae): 2,4,6‐trichlorophenol triggers an increase in the level of an extracellular peroxidase, capable of the oxidative dechlorination of this Xenobiotic pollutant
Plant Cell and Environment, 2004Co-Authors: Marcel A. K. Jansen, Lionel Hill, Roger N. F. ThorneleyAbstract:Peroxidases are haem-containing enzymes capable of oxidizing a wide range of substrates. This article describes the presence of peroxidase activity in the growth medium of axenic Spirodela punctata (Lemnaceae) cultures. It was found that the release of extracellular peroxidase activity is specifically enhanced by phytotoxic, halogenated phenols but not by other abiotic Stress-factors, elicitors or plant metabolites. Based on the concentration dependence of 2,4,6-trichlorophenol (TCP)-enhanced peroxidase release, it is concluded that release is not simply a consequence of physiological damage, but rather requires metabolically healthy fronds. In vitro studies (UV/VIS spectroscopy and liquid chromatographylmass spectrometry) show that the extracellular duckweed peroxidase (SpEx), which was partially purified from Spirodela growth medium, is capable of catalysing the oxidative dechlorination of TCP with hydrogen peroxide as the electron acceptor. It is proposed that the ability of S. punctata to specifically sense environmentally persistent phytotoxic chlorophenols, and to respond by increasing extracellular levels of a peroxidase capable of catalysing their oxidative dechlorination, is part of the protection strategy of this aquatic plant against Xenobiotic Stress.
