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Contribution à l'étude des effets de l'ozone, de la sécheresse et du stress salin sur le métabolisme carboné du pin d'Alep (Pinus halepensis Mill.). Régulation de la rubisco et de la rubisco activase

Abstract : The decline of aleppo pine forests (Pinus halepensis M.) observed in natural conditions have prompted research concerning the effects of abiotic stresses on this species. For this purpose, the effects of ozone, water stress and salt stress on aleppo pine's carbon metabolism were carried out in this study. Ozone did induce chlorotic mottles, linked to a decrease in chlorophyll content. A decline in total rubiseo activity, and an increase in the activities of several enzymes associated to the catabolic pathway such as pyruvate kinase (PK), phosphoenolpyruvate carboxylase (PEPc) and malic enzymes (EM-NAD and EM-NADP) were shown in needles of pines submitted to ozone. These results tend to show that an increase in compounds potentially used in detoxifying repair processes is occuring under ozone stress. Water and salt stresses would limit the deleterious effects of ozone on plant metabolism, presumably by inducing stomatal closure which would limit the pollutant input into the leaves. Studies on the regulation of rubisco and rubisco aetivase, were undertaken at a molecular level in needles of pines submitted to ozone and/or drought. For this purpose, the cloning of cDNA fragments coding for rubisco large subunit (LSU) and for rubisco activase (RCA) was realized, allowing a phylogenetic analysis of both proteins. A decrease of LSU and RCA protein quantities, associated to a transcriptional regulation, was shown in response to ozone,> suggesting a potential coregulation of both proteins in those particular conditions. Even though the effects of drought on the large subunit of rubisco and on rubisco activase were similar, no correlation between the effects of this stress on the two proteins could be drawn. When ozone was combined to drought, a difference in the regulation of rubisco large subunit and of rubisco activase was shown. Under those conditions, rubisco large subunit was under a transcriptional control whereas rubisco activase was under a post transcriptionnal regulation. For the very first time in this study, a conifer' s rubisco activase is partially cloned and its regulation studied in reponse to abiotic constraints.
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http://docnum.univ-lorraine.fr/prive/SCD_T_2000_0086_PELLOUX.pdf
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https://hal.univ-lorraine.fr/tel-01746462
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Submitted on : Thursday, March 29, 2018 - 10:38:17 AM
Last modification on : Thursday, December 17, 2020 - 1:57:11 PM

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  • HAL Id : tel-01746462, version 1

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Jérôme Pelloux. Contribution à l'étude des effets de l'ozone, de la sécheresse et du stress salin sur le métabolisme carboné du pin d'Alep (Pinus halepensis Mill.). Régulation de la rubisco et de la rubisco activase. Sylviculture, foresterie. Université Henri Poincaré - Nancy 1, 2000. Français. ⟨NNT : 2000NAN10086⟩. ⟨tel-01746462⟩

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