ARS | Publication request: Rhizobia from Lanzarote, the Canary Islands, that nodulate Phaseolus vulgaris have characteristics in common with LMW RNA group II Sinorhizobium meliloti of Medicago, Melilotus and Trigonella from soils of mainland Spain

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2009
Publication Date: March 1, 2009
Citation: Zurdo-Pineiro, J.L., Garcia-Fraile, P., Rivas, R., Leon-Barrios, M., Willems, A., Mateos, P.F., Martinez-Molina, E., Velazquez, E., Van Berkum, P.B. 2009. Rhizobia from Lanzarote, the Canary Islands, that nodulate Phaseolus vulgaris have characteristics in common with LMW RNA group II Sinorhizobium meliloti of Medicago, Melilotus and Trigonella from soils of mainland Spain. Applied and Environmental Microbiology. 75:2354-2359.

Interpretive Summary: Fertilizers are necessary to produce crops, but the disadvantage is that fossil fuels are used to produce these fertilizers. A family of plants know as legumes, including common bean, do not require fertilizer application for growth because they can form specialized structures on their roots that contain bacteria known as rhizobia. The rhizobia use atmospheric nitrogen to produce fertilizer in the plant so the farmer does not have to apply fertilizer. Rhizobia are added at the time of sowing instead of the fertilizer. However, the choice of the rhizobia to produce an optimum crop is difficult because little is known about their genetic variability and the cause of this variability. In this research, we discovered that rhizobia of alfalfa and common bean share genetic information, which is a major process causing the variability. This information will be valuable to scientists who wish to increase efficieny of legume crop production by not using fertilizer.

Technical Abstract: Several isolates from nodules of Phaseolus vulgaris grown in soil of Lanzarote, an island of the Canaries, had electrophoretic LMW RNA patterns identical with a less common pattern within S. meliloti (assigned as group II) obtained from nodules of alfalfa and alfalfa-related legumes grown in northern Spain. LMW RNA group II isolates were distinguishable by two conserved inserts of 20 and 46 bp in the 16S-23S ITS region that were not present in isolates of S. meliloti placed within LMW RNA group I. Group II isolates from P. vularis nodulated bean but not Medicago sativa while those recovered from Medicago, Melilotus and Trigonella nodulated both host legumes. The bean isolates also were distinguished from those of Medicago, Melilotus and Trigonella by nodC sequence analysis. The nodC sequence of the bean isolates were most similar to those reported for S. meliloti bv mediterranense and S. fredii bv mediterranense (GenBank accessions DQ333891 and AF217267) while the other group II isolates harbored nodC gene sequences characteristic of S. meliloti and S. medicae. None of the isolates of bean from Lanzarote were placed within the genus Rhizobium, which perhaps would be inconsistent with seed-borne transmission of R. etli from the Americas to the Canaries as an explanation for the presence of bean-nodulating rhizobia in soils of Lanzarote.