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Etude des phases précoces de la transduction des signaux environnementaux chez le lin : une approche protéomique

Abstract : Plants perceive and record environmental stimuli and, since they are unable to move, generally respond to these stimuli by modifying their growth and morphology. A key role in the perception of these stimuli is played by changes in the concentration of free calcium in different intracellular compartments as well as by signal transduction systems that depend on kinases to transmit information to the nucleus where a specific response is generated. In the work presented here, we have studied the effect on flax (Linum usitatissimum L.) or on Arabidopsis thaliana of abiotic stress (mechanical stress, exposure to low temperature, or exposure to non-thermal intensities of electromagnetic radiation at frequencies of 0.9 or 105 GHz). We have used the model of epidermal meristem production in flax to determine the effects of these different stresses in the presence or absence of calcium channel inhibitors or of calcium chelators. We have also developed a proteomic analysis of the flax hypocotyl in which we have formulated a statistical treatment to assess the significance of changes on 2-D gels of proteins. In parallel, we have developed a new method to see if these changes correspond to post-translational modifications by phosphorylation. This method, which is based on secondary ion mass spectrometry, can detect phosphorus in a spot or band after electrophoretic separation on a gel and may therefore be used to detect protein phosphorylation that can be difficult to detect by more traditional techniques. Our proteomic analysis of flax revealed that at least 4 proteins are involved in the rapid response to mechanical stimuli, 7 to a cold shock and 3 to irradiation at 0.9 GHz. 5 proteins were affected by calcium channel inhibitors and by the calcium chelator EGTA whilst 7 proteins were affected by a calcium depletion (which is required for the induction of meristems). Several of these stimuli (from two to four) had the same effect on the same group of 5 of these proteins, consistent with this group playing a fundamental role in signal transduction of abiotic stresses in flax. One of the proteins modified in response to cold shock was identified as saccharopine dehydrogenase. The absence of an appropriate database makes the identification of flax proteins difficult. We therefore resorted to the model plant, Arabidopsis thaliana, where we found 4 proteins affected both by cold shock and by irradiation for 2 h at 0.9 GHz, and 2 other proteins only affected by the irradiation. Two of the proteins affected by both stimuli were identified as carbonic anhydrase and as spermidine synthase. One of the proteins affected only by the irradiation at 0.9 GHz is homologous to the pherophorins. The data we have obtained contribute to our understanding of the initial phases of signal transduction of abiotic stresses in plants. In particular, we have made the unexpected discovery that plants perceive electromagnetic radiation at GHz frequencies and that they probably do this by using abiotic signal transduction pathways.
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https://tel.archives-ouvertes.fr/tel-00003381
Contributor : Marc Tafforeau <>
Submitted on : Tuesday, September 16, 2003 - 4:13:23 PM
Last modification on : Friday, October 23, 2020 - 4:52:28 PM
Long-term archiving on: : Friday, April 2, 2010 - 6:46:14 PM

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  • HAL Id : tel-00003381, version 1

Citation

Marc Tafforeau. Etude des phases précoces de la transduction des signaux environnementaux chez le lin : une approche protéomique. Biochimie [q-bio.BM]. Université de Rouen, 2002. Français. ⟨tel-00003381⟩

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