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Plasticité moléculaire de deux écotypes de pin maritime soumis à un stress osmotique

Abstract : Among abiotic stresses, water deficit is probably the most severe limiting factor of plant
growth and development. In South-Western France climatologists predict a significant
increase of temperature combined with lower rainfall during the growing period for the next
century. Such modifications will place forest trees in the presence of new and sudden
environmental constraints. It is therefore essential to know if these organisms will be able to
face such climatic changes. In other words, if plantation of improved varieties will maintain
the present level of productivity with lower water availability as well as sustain severe
drought episodes. The capacity of these organisms to adapt to such perturbations will depend
on both their phenotypic plasticity and their genetic diversity. In the frame of this thesis, we
studied molecular plasticity of maritime pine seedlings grown in hydroponics and exposed to
osmotic stress using polyethylene glycol as osmoticum. A factorial design crossing two
ecotypes (France & Morocco) by different levels of stress (short & long term) was used to
study the transcriptomic and proteomic responses of the root system. Our investigations
focused on accumulation of 7,000 transcripts and 1,200 proteins. Statistical analysis revealed
differentially expressed genes according to ecotype and condition effects. More interesting
was genes whose molecular plasticity was genetically controlled, revealing ecotype dependent
strategy to response to the imposed stresses. The adaptive significance of these genes could be
confirmed by analysing their patterns of nucleotidic diversity with the main objective of
detecting molecular signature of natural selection.
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Submitted on : Monday, November 20, 2006 - 7:15:56 PM
Last modification on : Friday, October 23, 2020 - 4:34:04 PM

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Philippe Chaumeil. Plasticité moléculaire de deux écotypes de pin maritime soumis à un stress osmotique. Biochimie [q-bio.BM]. Université Henri Poincaré - Nancy I, 2006. Français. ⟨tel-00115272⟩

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