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Diversity and affectiveness of rhizobial strains from Gliricidia sepium native to Reunion Island, Kenya and New Caledonia

Thiao M., Neyra M., Isidore E., Sylla S., Lesueur D.. 2004. World Journal of Microbiology and Biotechnology, 20 : p. 703-709.

The aim of this study was to use several approaches to assess the diversity occuring in a collection of rhizobial strains that had been isolated from Gliricidia sepium (Jacq.) Walp. originating from Kenya, Reunion Island and New Caledonia. Results showed that G. sepium establishes an effective symbiosis only with fast-growing rhizobia. This suggests that this legume nodulates preferentially with this type of rhizobia, although ineffective nodules were observed on root systems of plants inoculated with slow-growing rhizobia. It was possible to distinguish several groups of strains which have the same behaviour in terms of utilization of amino acids and sources of carbon and intrinsic resistance to antibiotics and salinity. Six molecular groups were distinguished by profiles obtained using PCR/RFLP techniques. No relationship was demonstrated between phenotypic groups and molecular groups. Neither was it possible to find a relationship between the geographic origins of the strains and their distribution in the several phenotypic and/or molecular groups. In an experiment carried out under glasshouse conditions, we observed that all strains from the collection significantly improved the growth of G. sepium cultivated in a substrate totally devoid of nitrogen. The strain GsK5 induced the greatest stimulation of plant growth. (Résumé d'auteur)

Mots-clés : ressource génétique; symbiose; biologie moléculaire; fixation de l'azote; gliricidia sepium; kenya; réunion

Thématique : Biologie du sol; Physiologie et biochimie végétales

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