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Accueil du site → Doctorat → Tunisie → Thèse soutenue → 2006 → Perturbation du fonctionnement nodulaire sous stress salin et hydrique chez la symbiose rhizobium-haricot

Centre National des Sciences et Technologies Nucleaires, Tunis (2006)

Perturbation du fonctionnement nodulaire sous stress salin et hydrique chez la symbiose rhizobium-haricot

Harzalli Jebara, Salwa

Titre : Perturbation du fonctionnement nodulaire sous stress salin et hydrique chez la symbiose rhizobium-haricot

Auteur : Harzalli Jebara, Salwa

Etablissement : Centre National des Sciences et Technologies Nucleaires, Tunis

Grade : Doctorat 2006

Résumé
This work aims at the search for markers of tolerance to the osmotic stress and nodular efficiency of symbiosis Haricot Rhizobium. Thus, after having fixed the best period of hydroponic culture, we showed that a severe salt treatment generated an inhibition of the parameters of growth and nodulation. These inhibitions are accompanied by an inhibition of the enzymatic activities : ascorbate peroxidase (APX) and catalase (CAT), but an activation of peroxidase (POX) and superoxide dismutase (SOD), suggesting that these two antioxydants can be biochemical markers of the tolerance to salinity. To check the validity of these markers and to see the participation of the vegetable genotype in the response to the stress, we compared the effect of two concentrations salt 25 and 50 mM NaCe at two contrasting genotypes BAT477 tolerant and sensitive COCOT. This study illustrates the role of the vegetable genotype in the tolerance and efficiency and emphasize a significant result that SOD and POX constitute biochemical markers of tolerance to salinity. In order to ensure itself of the validity of this assumption in the event of water deficit stress, a treatment of 50 mM mannitol is applied to 16 symbioses formed by four genotypes of bean BAT477, COCOT, Flamingo and BRB17 inoculated by four strains of rhizobium CIAT899, 12 to 3, 1 to 6 and 8 to 3. This study permits us to make a screening of these symbioses according to their efficiency and their tolerance based on parameters of growth, of fixing and extent of the antioxydant enzymatic activities. It gets clear that the response of enzymatic antioxydants is in relation to the intrinsic potentialities of the partners of symbioses and appears to act as of the first stages of recognition plants bacterium. It will be retained that activities POX and SOD are markers of nodular tolerance. The CAT is the enzyme most connected to each partner of symbiosis and the APX would play a rather functional role. The heterogeneity of found answer indicates the great importance of the interaction of the two partners of symbiosis and of their contribution in great variability. The whole of results permits us to choose contrasting symbioses for better elucidating the mechanisms of nodular operation in response to the osmotic stress.

Mots clés : BACTERIA, KINETICS, LEGUMINOSAE, MAGNOLIOPHYTA, MAGNOLIOPSIDA, MICROORGANISMS, PLANTS, REACTION KINETICS

Présentation (IAEA / INIS)

Page publiée le 30 septembre 2018