Relative genetic structure of a population of Rhizobium meliloti isolated directly from soil and from nodules of alfalfa (Medicago sativa) and sweet clover (Melilotus alba)

Bromfield, E. S. P.; Barran, L. R.; Wheatcroft, Roger

doi:10.1111/j.1365-294x.1995.tb00207.x

Cited by 61 publications

(50 citation statements)

References 22 publications

(11 reference statements)

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“…Both fava bean and pea plants are able to discriminate among the diversity of rhizobial genotypes that are present in soil. Similar results were reported previously for other legumes (6,16,51). Furthermore, relatively small differences in frequencies of R. leguminosarum bv.…”

Section: Discussionsupporting

confidence: 81%

“…Dominance of particular rhizobial genotypes in nodules may result from a higher abundance in soil rather than a greater nodulation competitiveness, as shown for certain genotypes within Sinorhizobium meliloti indigenous populations (6,16,43). This may explain the finding that nodule-dominant genotypes from soil populations do not necessarily show superior competitiveness for nodulation compared to minor occupants when evaluated under nonsoil conditions (7,27,31).…”

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confidence: 53%

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Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

Laguerre

Louvrier

Allard

et al. 2003

Appl Environ Microbiol

137

172

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Populations of Rhizobium leguminosarum biovar viciae were sampled from two bulk soils, rhizosphere, and nodules of host legumes, fava bean (Vicia faba) and pea (Pisum sativum) grown in the same soils. Additional populations nodulating peas, fava beans, and vetches (Vicia sativa) grown in other soils and fava beannodulating strains from various geographic sites were also analyzed. The rhizobia were characterized by repetitive extragenomic palindromic-PCR fingerprinting and/or PCR-restriction fragment length polymorphism (RFLP) of 16S-23S ribosomal DNA intergenic spacers as markers of the genomic background and PCR-RFLP of a nodulation gene region, nodD, as a marker of the symbiotic component of the genome. Pairwise comparisons showed differences among the genetic structures of the bulk soil, rhizosphere, and nodule populations and in the degree of host specificity within the Vicieae cross-inoculation group. With fava bean, the symbiotic genotype appeared to be the preponderant determinant of the success in nodule occupancy of rhizobial genotypes independently of the associated genomic background, the plant genotype, and the soil sampled. The interaction between one particular rhizobial symbiotic genotype and fava bean seems to be highly specific for nodulation and linked to the efficiency of nitrogen fixation. By contrast with bulk soil and fava bean-nodulating populations, the analysis of pea-nodulating populations showed preferential associations between genomic backgrounds and symbiotic genotypes. Both components of the rhizobial genome may influence competitiveness for nodulation of pea, and rhizosphere colonization may be a decisive step in competition for nodule occupancy.

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Section: Discussionsupporting

confidence: 81%

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confidence: 53%

Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

Laguerre

Louvrier

Allard

et al. 2003

Appl Environ Microbiol

137

172

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“…En este sentido, la clasificación propuesta por Jordan en 1984, no indicó formas extremas o intermedias, probablemente debido al muestreo reducido de leguminosas, el cual no fue representativo de la población total (Martí-nez-Romero & Caballero-Mellado 1996). Por lo tanto, se ha señalado la inconveniencia de tomar en cuenta sólo los aislamientos nodulares, porque se pasa por alto la gran diversidad de los grupos de rizobios existentes en el suelo (Bromfield et al 1995), además, se conoce la existencia de un grupo de rizobios no simbióti-cos presentes en él (Sullivan et al 1996). Este criterio es relativo y subjetivo (Bécquer et al 2000), puesto que va a depender en parte de las condiciones del medio de cultivo, las cuales son: composición, pH, temperatura y origen de la cepa, sean provenientes de un aislamiento nodular o de repiques frecuentes de cepas ya aisladas y conservadas en el laboratorio, factores que modifican la velocidad de crecimiento.…”

Section: Discussionunclassified

Caracterización fenotípica y genotípica de doce rizobios aislados de diversas regiones geográficas de Venezuela

Marquina¹,

González²,

Castro³

2010

RBT

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Phenotypic and genotypic characterization of twelve rhizobial isolates from different regions of Venezuela. Rhizobial taxonomy and systematics have progressed substantially, nevertheless, few studies have been developed on venezuelan species. This study evaluated the phenotypic and genetic variation between 12 venezuelan indigenous rhizobial isolates and 10 international referential strains, by phenotypical traits and DNA molecular markers. in this regard, a PCR-RFLP of the 16S rDNA gene, the presence of large plasmids, metabolic assays in solid media, salinity resistance, pH and temperature growth conditions, and intrinsic antibiotic resistance were assayed. in reference to the phenotypic attributes, we recognized three main groups: A group i, which comprised all the strains metabolizing between 67.5%-90% of the C and N sources. They were also acid-tolerant, as well as acid producers, capable of growing at 40ºC and in high salinity conditions (2-2.5% NaCl). With regard to the antibiotic sensitivity, this group was susceptible to a 30% of the antibiotic assayed. Strains belonging to Group ii exhibited a lower salt tolerance (0.1-1.5%NaCl), as well as a lower acid tolerance, since they grew well at pH values equal or higher than 5.0. This group appeared to be resistant to all of the antibiotics assayed and only metabolized between 52.5%-82.5% of the C and N sources. Group iii was represented by a single bacterial strain: it has a extremely low salt tolerance (0.1% NaCl). This strain grew at a pH equal or higher than 5.6, was susceptible to 50% of the antibiotics assayed and metabolized 72% of the C and N sources. On the basis of a PCR-RFLP of the 16S rDNA, three groups were also obtained. Members of the group A showed a close resemblance to Rhizobium tropici CiAT 899 and Sinorhizobium americanum CFN-Ei 156, while Group B was closely related to Bradyrhizobium spp. Group C, was also represented by only one isolate. The Trebol isolate, was the only one strain able to form nodules and does not appear to be related to any of the referential rhizobial strains, suggesting a possible symbiotic horizontal gene transfer. Finally, in this work, there are evidences of a genetic diversity in the venezuelan rhizobial strains. A different geographical origin is perhaps an important factor affecting the diversity of the indigenous rhizobia in this study. Rev. Biol. Trop. 59 (3): 1017-1036. Epub 2011 September 01.Key words: Rhizobium, Bradyrhizobium, phenotypic characterization, PCR-RFLP, 16S rDNA.Las bacterias denominadas comúnmen-te rizobios presentan varias formas de vida; pueden comportarse como saprófitos en el suelo establecer una asociación simbiótica y formar nódulos con las raíces y tallos de las leguminosas, donde tiene lugar la reducción del nitrógeno atmosférico en amonio, el cual es transportado a la planta y convertido en biomoléculas esenciales, o bien estar presentes como endófito en raíces de diferentes especies vegetales, donde ejercen efectos promotores del crecimiento (Wang et al. 2001).La taxonomía ...

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“…There may be differences between the population densities of different strains in soil and these differences may infl uence the outcome of nodulation. Dominance of a particular rhizobial strain in nodules may result from its higher abundance in soil as reported in Ensifer meliloti indigenous for a population [11][12][13] or may not be correlated [14][15][16]. Use of three predominant strains as inoculants showed that one strain formed majority of the nodules while the other two were minor occupants in the nodules.…”

Section: Introductionmentioning

confidence: 99%

Molecular diversity, effectiveness and competitiveness of indigenous rhizobial population infecting mungbean Vigna radiata (L. Wilczek) under semi-arid conditions

Kundu

Dudeja

2008

Indian J Microbiol

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Nodules from mungbean crop raised for the fi rst time at Ram Dhan Singh (RDS) farm of Chaudhary Charan Singh (CCS) Haryana Agricultural University, Hisar were collected from 17 different locations. Twentyfi ve mungbean rhizobia were isolated and authenticated by plant infection test. DNA of all these rhizobia was extracted purifi ed and amplifi ed using enterobacterial repetitive intergenic consensus (ERIC) primers. All the mungbean rhizobial isolates were clustered into 4 groups at 65% of similarity and were further divided into 17 subclusters at 80% of similarity. All the 4 types of rhizobia were not present at any of the location and group 2 or 4 rhizobia were invariably present. Effi cacy of these rhizobia in terms of nodulation, nitrogen uptake and chlorophyll a fl uorescence was determined under pot culture conditions. Strain MB 307 showed maximum nitrogen uptake of 31.9 mg N plant -1 followed by strain MB 1205, MB 1206(2), MB 308, MB 1524 and strain MB 1521 was found to be the least effi cient in terms of N 2 fi xation. Nodule occupancy by different rhizobia ranged from 5.5 to 40.3%. Most of the strains belonging to the 2nd group which clustered maximum number of strains were comparatively better competitors and formed 19.5-40.3% of the nodules and were also effective. Isolate MB 307, the most effi cient strain, was found to have nodule occupancy of 31.5%. Such type of predominant, effi cient and better competitor strains should be selected for enhancing nodule competitiveness.

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Relative genetic structure of a population of Rhizobium meliloti isolated directly from soil and from nodules of alfalfa (Medicago sativa) and sweet clover (Melilotus alba)

Cited by 61 publications

References 22 publications

Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

Compatibility of Rhizobial Genotypes within Natural Populations of Rhizobium leguminosarum Biovar viciae for Nodulation of Host Legumes

Caracterización fenotípica y genotípica de doce rizobios aislados de diversas regiones geográficas de Venezuela

Molecular diversity, effectiveness and competitiveness of indigenous rhizobial population infecting mungbean Vigna radiata (L. Wilczek) under semi-arid conditions

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