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Réponses moléculaires du champignon ectomycorhizien Paxillus involutus aux métaux et effet de la symbiose sur la croissance et la survie de Betula pendula cultivé en sol pollué

Abstract : Molecular mechanisms underlying the response of the ectomycorrhizal fungi Paxillus involutus towards heavy metals have been studied. The availability of a P. involutus cDNA library has allowed the use of a cDNA macroarray hybridization, with 2040 cDNAs, to identify genes whose expression was modulated by cadmium (4 % of these clones were up or down regulated by Cd). Three cDNAs (from the cDNA library) coding for a superoxide dismutase (SOD), a metallothionein (MT) and a thioredoxin (TRX) have been characterized. The SOD and the MT functions have been demontrated respectively using a SOD-deleted bacteria and a MT-deleted yeast. The study of the SOD revealed a probable peroxysomal localization and mainly a regulation at the post-translational level. The expression study of MT and TRX has been performed using 3 metals : Cd, Cu et Zn and indicated an induction by only Cd and Cu. We have also measured the synthesis of non-protein thiols in P. involutus subjected to a Cd stress and demonstrated the overproduction of glutathion, the absence of phytochelatins and the presence of a unidentified component which could be a MT. We have also studied the impact of various P. involutus strains on different aspects of his host tree (birch) physiology grown on polluted soil. We have confirmed the filter function of P. involutus, but we also observed a weak survival rate of introduced fungal strains against indigenous strains.
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http://docnum.univ-lorraine.fr/prive/SCD_T_2003_0175_COURBOT.pdf
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https://hal.univ-lorraine.fr/tel-01746844
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Submitted on : Thursday, March 29, 2018 - 10:45:58 AM
Last modification on : Friday, February 5, 2021 - 3:43:04 AM

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Mikaël Courbot. Réponses moléculaires du champignon ectomycorhizien Paxillus involutus aux métaux et effet de la symbiose sur la croissance et la survie de Betula pendula cultivé en sol pollué. Sylviculture, foresterie. Université Henri Poincaré - Nancy 1, 2003. Français. ⟨NNT : 2003NAN10175⟩. ⟨tel-01746844⟩

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