Gwenola Gouesbet

Publications (50) View all

• Conference Proceeding: Plant responses to residual pesticide contaminations : possible impacts in a context of vegetated filter strips

  Cécile Sulmon, Anne-Antonella Serra, Ivan Couée, Gwenola Gouesbet
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  ABSTRACT: Agricultural activities use large amounts of pesticides in order to increase crop productivity. However, small proportions of applied pesticides reach intended targets, whereas the majority is dispersed in the environment, thus affecting soil and water quality. In order to reduce pesticide runoffs and improve water quality in agricultural landscapes, the Common Agricultural Policy and the Water Framework Directive have imposed installation of vegetated filter strips along fields bordering streams. These strips act as buffering systems mainly through water flux regulation, modification of physico-chemical environment and stimulation of microbial processes, all of these mechanisms being driven by plants. However, plants in vegetated filter strips are also subjected to chemical mixtures of pesticides and associated xenobiotics (adjuvants, metabolites), which potentially impact their development and physiology. Characterization of the effects of pesticide mixtures on plants and of the related plant responses is thus of particular interest to understand buffering functions of vegetated strips. Our studies detected significant levels of residual pesticides, such as glyphosate and tebuconazole, and degradation products, in soils of field margins located in northern Brittany (Zone Atelier Armorique, 35, France). Integrative analysis of physiological, metabolic and gene-expression responses of the model plant Arabidopsis thaliana was carried out in dose-response experiments and in comparative experiments of varying pesticide combinations. Field-margin contamination levels were found to have significant effects on plant growth and metabolism despite low levels of pesticides and the presence of hypothetically-inactive xenobiotic metabolites. In particular, the glyphosate metabolite aminomethylphosphonic acid and the atrazine metabolite hydroxyatrazine elicited significant physiological effects through changes of metabolic profiles and gene expression. Moreover, pesticide mixtures resulted in various interaction effects such as addition, or in contrast, antagonism, in comparison to the effects of individual pollutants. Residual pesticide mixtures could thus alter in the field functional abilities of plants to survive, develop and reproduce, leading to a decrease of buffering functions of vegetated filter strips. We recently identified, within local plant biodiversity, xenobiotic-tolerant species which were not impacted by residual pesticide treatments and which could contribute to enhance the efficiency of vegetated strips. Further work will focus on the involvement of such tolerant plants in the structuration of plant communities and the related buffer efficiency of vegetated filter strips. Remediation ability of xenobiotic-tolerant species, in terms of pesticide absorption and accumulation, will also be taken into account.
  4th International Multidisciplinary Conference on Hydrology and Ecology : emerging patterns, breakthroughs and challenges, Rennes, Brittany, France; 05/2013
• Article: Low environmentally relevant levels of bioactive xenobiotics and associated degradation products cause cryptic perturbations of metabolism and molecular stress responses in Arabidopsis thaliana.

  Anne-Antonella Serra, Andréïna Nuttens, Vanessa Larvor, David Renault, Ivan Couée, Cécile Sulmon, Gwenola Gouesbet
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  ABSTRACT: Anthropic changes and chemical pollution confront wild plant communities with xenobiotic combinations of bioactive molecules, degradation products, and adjuvants that constitute chemical challenges potentially affecting plant growth and fitness. Such complex challenges involving residual contamination and mixtures of pollutants are difficult to assess. The model plant Arabidopsis thaliana was confronted by combinations consisting of the herbicide glyphosate, the fungicide tebuconazole, the glyphosate degradation product aminomethylphosphonic acid (AMPA), and the atrazine degradation product hydroxyatrazine, which had been detected and quantified in soils of field margins in an agriculturally intensive region. Integrative analysis of physiological, metabolic, and gene expression responses was carried out in dose-response experiments and in comparative experiments of varying pesticide combinations. Field margin contamination levels had significant effects on plant growth and metabolism despite low levels of individual components and the presence of pesticide degradation products. Biochemical and molecular analysis demonstrated that these less toxic degradation products, AMPA and hydroxyatrazine, by themselves elicited significant plant responses, thus indicating underlying mechanisms of perception and transduction into metabolic and gene expression changes. These mechanisms may explain observed interactions, whether positive or negative, between the effects of pesticide products (AMPA and hydroxyatrazine) and the effects of bioactive xenobiotics (glyphosate and tebuconazole). Finally, the metabolic and molecular perturbations induced by low levels of xenobiotics and associated degradation products were shown to affect processes (carbon balance, hormone balance, antioxidant defence, and detoxification) that are likely to determine environmental stress sensitivity.
  Journal of Experimental Botany 05/2013; · 5.36 Impact Factor
• Article: Physiology and toxicology of hormone-disrupting chemicals in higher plants.

  Ivan Couée, Anne-Antonella Serra, Fanny Ramel, Gwenola Gouesbet, Cécile Sulmon
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  ABSTRACT: Higher plants are exposed to natural environmental organic chemicals, associated with plant-environment interactions, and xenobiotic environmental organic chemicals, associated with anthropogenic activities. The effects of these chemicals result not only from interaction with metabolic targets, but also from interaction with the complex regulatory networks of hormone signaling. Purpose-designed plant hormone analogues thus show extensive signaling effects on gene regulation and are as such important for understanding plant hormone mechanisms and for manipulating plant growth and development. Some natural environmental chemicals also act on plants through interference with the perception and transduction of endogenous hormone signals. In a number of cases, bioactive xenobiotics, including herbicides that have been designed to affect specific metabolic targets, show extensive gene regulation effects, which are more in accordance with signaling effects than with consequences of metabolic effects. Some of these effects could be due to structural analogies with plant hormones or to interference with hormone metabolism, thus resulting in situations of hormone disruption similar to animal cell endocrine disruption by xenobiotics. These hormone-disrupting effects can be superimposed on parallel metabolic effects, thus indicating that toxicological characterisation of xenobiotics must take into consideration the whole range of signaling and metabolic effects. Hormone-disruptive signaling effects probably predominate when xenobiotic concentrations are low, as occurs in situations of residual low-level pollutions. These hormone-disruptive effects in plants may thus be of importance for understanding cryptic effects of low-dosage xenobiotics, as well as the interactive effects of mixtures of xenobiotic pollutants.
  Plant Cell Reports 04/2013; 32:933-941. · 2.27 Impact Factor
• Source

  Available from: Gwenola Gouesbet

  Article: Xenobiotic sensing and signalling in higher plants.

  Fanny Ramel, Cécile Sulmon, Anne-Antonella Serra, Gwenola Gouesbet, Ivan Couée
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  ABSTRACT: Anthropogenic changes and chemical pollution confront plant communities with various xenobiotic compounds or combinations of xenobiotics, involving chemical structures that are at least partially novel for plant species. Plant responses to chemical challenges and stimuli are usually characterized by the approaches of toxicology, ecotoxicology, and stress physiology. Development of transcriptomics and proteomics analysis has demonstrated the importance of modifications to gene expression in plant responses to xenobiotics. It has emerged that xenobiotic effects could involve not only biochemical and physiological disruption, but also the disruption of signalling pathways. Moreover, mutations affecting sensing and signalling pathways result in modifications of responses to xenobiotics, thus confirming interference or crosstalk between xenobiotic effects and signalling pathways. Some of these changes at gene expression, regulation and signalling levels suggest various mechanisms of xenobiotic sensing in higher plants, in accordance with xenobiotic-sensing mechanisms that have been characterized in other phyla (yeast, invertebrates, vertebrates). In higher plants, such sensing systems are difficult to identify, even though different lines of evidence, involving mutant studies, transcription factor analysis, or comparative studies, point to their existence. It remains difficult to distinguish between the hypothesis of direct xenobiotic sensing and indirect sensing of xenobiotic-related modifications. However, future characterization of xenobiotic sensing and signalling in higher plants is likely to be a key element for determining the tolerance and remediation capacities of plant species. This characterization will also be of interest for understanding evolutionary dynamics of stress adaptation and mechanisms of adaptation to novel stressors.
  Journal of Experimental Botany 04/2012; 63(11):3999-4014. · 5.36 Impact Factor
• Source

  Available from: Ivan Couée

  Article: Carbon dynamics, development and stress responses in Arabidopsis: involvement of the APL4 subunit of ADP-glucose pyrophosphorylase (starch synthesis).

  Cécile Sulmon, Gwenola Gouesbet, Fanny Ramel, Francisco Cabello-Hurtado, Christophe Penno, Nicole Bechtold, Ivan Couée, Abdelhak El Amrani
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  ABSTRACT: An Arabidopsis thaliana T-DNA insertional mutant was identified and characterized for enhanced tolerance to the singlet-oxygen-generating herbicide atrazine in comparison to wild-type. This enhanced atrazine tolerance mutant was shown to be affected in the promoter structure and in the regulation of expression of the APL4 isoform of ADP-glucose pyrophosphorylase, a key enzyme of the starch biosynthesis pathway, thus resulting in decrease of APL4 mRNA levels. The impact of this regulatory mutation was confirmed by the analysis of an independent T-DNA insertional mutant also affected in the promoter of the APL4 gene. The resulting tissue-specific modifications of carbon partitioning in plantlets and the effects on plantlet growth and stress tolerance point out to specific and non-redundant roles of APL4 in root carbon dynamics, shoot-root relationships and sink regulations of photosynthesis. Given the effects of exogenous sugar treatments and of endogenous sugar levels on atrazine tolerance in wild-type Arabidopsis plantlets, atrazine tolerance of this apl4 mutant is discussed in terms of perception of carbon status and of investment of sugar allocation in xenobiotic and oxidative stress responses.
  PLoS ONE 01/2011; 6(11):e26855. · 4.09 Impact Factor