Influence de l'ozone et de la sécheresse sur le métabolisme carboné des aiguilles de pin d'Alep (Pinus halepensis Mill.) : étude de la régulation de la phosphoénolpyruvate carboxylase

Abstract : This study concerns the effects of ozone and/or drought on the physiology of aleppo pine (Pinus halapensis Mill.) and more particulary on carbon metabolism. Drought did induce some protection against the deleterious effects of ozone. Ozone on its own induced severe damages on needles, as shown by a decrease because of a potential increase of respiration. The stimulation of catabolic enzymes activities tend to confirm this hypothesis. These enzymes allow the production of components used for repair and protection processes against ozone damages. The anaplerotic pathway via phosphoenolpyruvate carboxylase (PEPc) was strongly stimulated under ozone, producing reducing power in the cytosol (via NADP malic enzyme) and Krebs cycle intermediates. This enzyme could limit carbon losses by respiration and could play a role in pH regulation. The increase in PEPc activity under ozone treatment led us to study the regulation of this enzyme under stresses. The cloning of PEPc cDNA has been realized. The regulation of the activity is complex and, under ozone, at first, PEPc protein and mRNA quantities were stimulated ; in a second phase of the experiment, the changes in PEPc activity seemed related to a regulation by posphorylation. On the contrary, the regulation of PEPc activity under the combination of ozone and drought was only related to a gene expression regulation. This work presents the first result on coniferous PEPc regulation under stress.
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Theses
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http://docnum.univ-lorraine.fr/prive/SCD_T_1999_0028_FONTAINE.pdf
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https://hal.univ-lorraine.fr/tel-01747059
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Submitted on : Thursday, March 29, 2018 - 10:50:18 AM
Last modification on : Monday, April 16, 2018 - 10:40:34 AM

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Véronique Fontaine. Influence de l'ozone et de la sécheresse sur le métabolisme carboné des aiguilles de pin d'Alep (Pinus halepensis Mill.) : étude de la régulation de la phosphoénolpyruvate carboxylase. Sciences agricoles. Université Henri Poincaré - Nancy 1, 1999. Français. ⟨NNT : 1999NAN10028⟩. ⟨tel-01747059⟩

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