Genetic diversity of rhizobia associated with root nodules of white lupin (Lupinus albus L.) in Tunisian calcareous soils

Tounsi-Hammami Soumaya, Le Roux Christine, Dhane-Fitouri Sana, De Lajudie Philippe, Duponnois Robin, Ben Jeddi Faysal. 2019. Genetic diversity of rhizobia associated with root nodules of white lupin (Lupinus albus L.) in Tunisian calcareous soils. Systematic and Applied Microbiology, 42 (4) : 448-456.

https://doi.org/10.1016/j.syapm.2019.04.002

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Quartile : Q2, Sujet : BIOTECHNOLOGY & APPLIED MICROBIOLOGY / Quartile : Q2, Sujet : MICROBIOLOGY

Résumé : With a view to introducing white lupin (Lupinus albus L.) for cultivation in Tunisian calcareous soils, compatible indigenous rhizobia for nitrogen-fixing symbiosis were investigated and characterized. Two L. albus varieties, Mekna and Lumen, were used to trap rhizobia in soil samples collected from 56 sites with high active lime contents (0–49%). Nodulation occurred in only 15 soils. The local variety, Mekna, developed significantly more root nodules and had a trapping capacity in more soils than the imported variety Lumen. A phylogenetic analysis based on the partial 16S-23S ribosomal RNA internal transcribed spacer region (ITS) and multi-locus sequence analysis (MLSA) of three chromosomal housekeeping genes, recA, atpD and dnaK, showed that strains were affiliated to Agrobacterium, Rhizobium, and Neorhizobium, with large internal diversity, including separate lineages. Infectivity tests highlighted some nodulation specificity at the plant variety level, since the strains originating from Mekna could only nodulate this variety, while strains trapped in Lumen could nodulate both varieties. When inoculated, almost all strains resulted in a significant increase in plant shoot dry weight on L. albus. Although Agrobacterium sp. strains isolated from L. albus could nodulate and had a plant growth promoting effect, no nodA and nodC genes could be amplified. This is discussed together with the absence of bradyrhizobia and the general infrequency of L. albus–nodulating rhizobia in Tunisian soils. The adapted and efficient rhizobial strains reported here were promising candidates for inoculant development and represent a contribution towards successful cultivation of L. albus in Tunisia, especially the most promising Mekna variety.

Mots-clés Agrovoc : Lupinus albus, sol calcaire, nodosité racinaire, variation génétique, Rhizobium, Agrobacterium, phylogénie

Mots-clés géographiques Agrovoc : Tunisie

Mots-clés libres : Lupinus albus, Calcareous, Soils, Agrobacterium, MLSA, Rhizobium, Neorhizobium

Classification Agris : F30 - Génétique et amélioration des plantes
P30 - Sciences et aménagement du sol
F01 - Culture des plantes

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

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