Different species and symbiotic genotypes of field rhizobia can nodulate Phaseolus vulgaris in Tunisian soils

Abstract

A collection of 160 isolates of rhizobia nodulating Phaseolus vulgaris in three geographical regions in Tunisia was characterized by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-amplified 16S rDNA, nifH and nodC genes. Nine groups of rhizobia were delineated : Rhizobium gallicum biovar (bv.) gallicum, Rhizobium leguminosarum bv. phaseoli and bv. viciae, Rhizobium etli bv. phaseoli, Rhizobium giardinii bv. giardinii, and four groups related to species of the genus Sinorhizobium, Sinorhizobium meliloti, Sinorhizobium medicae and Sinorhizobium fredii. The most abundant rhizobial species were R. gallicum, R. etli, and R. leguminosarum encompassing 29^20% of the isolates each. Among the isolates assigned to R. leguminosarum, two-thirds were ineffective in nitrogen fixation with P. vulgaris and harbored a symbiotic gene typical of the biovar viciae. The S. fredii-like isolates did not nodulate soybean plants but formed numerous effective nodules on P. vulgaris. Comparison of nodC gene sequences showed that their symbiotic genotype was not related to that of S. fredii, but to that of the S. fredii-like reference strain GR-06, which was isolated from a bean plant grown in a Spanish soil. An additional genotype including 16% of isolates was found to be closely related to species of the genus Agrobacterium. However, when re-examined, these isolates did not nodulate their original host. ß

Rhizobium etli and Rhizobium gallicum Nodulate Common Bean ( Phaseolus vulgaris ) in a Traditionally Managed Milpa Plot in Mexico: Population Genetics and Biogeographic Implications

“…R. etli bv. phaseoli is found in regions where common bean has been introduced, such as Spain, France, Austria, Senegal, Gambia, and Tunisia (10,21,24,33,34,44). However, in these countries other Rhizobium species also nodulate this legume.…”

“…Rhizobium giardinii has been found only in European and Tunisian soils (3,21,34). Rhizobium gallicum has been found nodulating beans in Europe (3,21) and Tunisia (33,34), and one Mexican strain (strain FL27) has been identified as a member of this species (44).In Rhizobium a large proportion of the genome is composed of plasmids (16), which contribute significantly to the ecological fitness and symbiotic performance of rhizobial strains (6,8,16). The symbiotic genes for nodulation (nod) and nitrogen fixation (nif, fix) are located on the symbiotic plasmid (pSym).…”

“…Rhizobium tropici is present in acid soils of South America (31) and has been found in France (2) and several African countries (4, 10). Rhizobium giardinii has been found only in European and Tunisian soils (3,21,34). Rhizobium gallicum has been found nodulating beans in Europe (3,21) and Tunisia (33,34), and one Mexican strain (strain FL27) has been identified as a member of this species (44).…”

“…Rhizobium leguminosarum bv. phaseoli is commonly found in Europe, and it has also been reported to be present in Tunisia and Colombia (11,21,33,34). Rhizobium tropici is present in acid soils of South America (31) and has been found in France (2) and several African countries (4,10).…”

Rhizobium herbae sp. nov. and Rhizobium giardinii-related bacteria, minor microsymbionts of various wild legumes in China

“…phaseoli (Amarger et al, 1997). So far, several reports have claimed that this species can form root nodules on many other legumes besides P. vulgaris (Amarger et al, 1997;Herrera-Cervera et al, 1999;Mhamdi et al, 2002), including Desmanthus illinoensis (Beyhaut et al, 2006), Arachis hypogaea (Taurian et al, 2002(Taurian et al, , 2006, Kummerowia stipulacea, Aeschynomene indica (Kwon et al, 2005), Desmanthus leptolobus, Dalea purpurea, Psoralea esculenta, Prosopis juliflora (Benata et al, 2008;Beyhaut et al, 2006) and Prosopis alba (Iglesias et al, 2007).…”