Root Nodule Bacteria and Leguminous Plants

Fred, E. B.; Baldwin, I. L.; McCoy, Elizabeth; Starkey, Robert L.

doi:10.1097/00010694-193302000-00006

Cited by 210 publications

(169 citation statements)

References 38 publications

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“…Until 1982, all bacteria isolated from root nodules were classified in the genus Rhizobium, and speciation was based on the formation of nodules with certain host plants, establishing the 'cross-inoculation group' concept (Fred et al, 1932;Jordan, 1982). Based on morphological and physiological patterns, the bacteria were then split into the genera Bradyrhizobium, which included relatively slow growers Abbreviation: IGS, intergenic spacer.…”

Section: Introductionmentioning

confidence: 99%

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Germano

Menna

Mostasso

et al. 2006

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLO

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Genetic diversity in tropical rhizobial species is still poorly known. With the aim of increasing this knowledge, three ribosomal regions of 119 strains belonging to the official Brazilian culture collection of rhizobia and classified as Bradyrhizobium based on morphological and physiological characteristics in vitro were analysed by RFLP-PCR. The strains were isolated from 33 legume species, representing nine tribes and all three subfamilies; they all form very effective N 2 -fixing nodules and 43 of them are recommended for use in Brazilian commercial inoculants as the most effective for their hosts. For the 16S rRNA gene, type and reference strains of Bradyrhizobium japonicum fell into two major clusters, joined at a level of similarity of 50 %, which included 52 strains, 90 % of which were isolated from soybean. Two other clusters, joined at a similarity of 53 %, included reference strains of Bradyrhizobium elkanii, but not USDA 76 T ; furthermore, two other major clusters were identified and all strains were clustered at a final level of similarity of only 28 %. For the intergenic spacer (IGS) between genes coding for the 16S and 23S rRNA, strains were clustered at a final level of similarity of 27 %. Reference strains of B. japonicum fell into a major group with 51 strains, 84 % isolated from soybean, with a similarity of 59 %, while strains of B. elkanii fell into another major group, with a similarity of 55 %, clustering 44 strains, 59 % of which were isolated from hosts other than soybean. New clusters were also observed for the IGS region. The largest number of differences was detected in the analysis of the 23S rRNA gene, and 16 groups and isolated strains were joined at a very low level of similarity (16 %). In a combined analysis with the three ribosomal regions, the majority of strains isolated from soybean clustered with a similarity of 54 % with type and reference strains of B. japonicum, while most strains isolated from Brazilian indigenous legume species grouped with B. elkanii at a level of similarity of 46 %. All strains were clustered at a very low level of similarity (27 %), and at least two new clusters were clearly defined. These new clusters might be related to intraspecific differences or to novel subspecies, or even to novel species; indeed, strains from one of these clusters show higher 16S rRNA gene sequence similarity to members of the genus Burkholderia. The results obtained in this study emphasize the high level of diversity of symbiotic diazotrophic bacteria in the tropics that still remains to be determined. INTRODUCTIONThe Leguminosae (known as the Fabaceae in the USA) is one of the largest families of plants, with over 18 000 species classified into around 650 genera, representing approximately one-twelfth of all known flowering plants and occupying nearly all terrestrial biomes (Polhill & Raven, 1981). Many species within this family are capable of establishing symbioses with a group of bacteria collectively called rhizobia, of which the most important feature is the capacity...

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Section: Introductionmentioning

confidence: 99%

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Germano

Menna

Mostasso

et al. 2006

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLO

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“…Groundnut (Arachis hypogaea L.), which is an important food legume in several developing countries, is nodulated by members of the cowpea miscellany (Fred et al, 1932;Buchanan and Gibson, 1974). This large heterogeneous group of rhizobia is characterized by a high degree of symbiotic promiscuity, and members are thought to be slow growing and alkaline producing.…”

Section: Introductionmentioning

confidence: 99%

Abundance and characterization of cowpea miscellany Rhizobium from sudanese soils

Hadad¹,

Loynachan²

1985

Soil Biology and Biochemistry

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“…The nitrogen-fixing ability of soybean, alfalfa, and clover is of great practical importance because of the large areas planted with these crops. However, the species most often used in basic research on nitrogen fixation is the pea, Pisum sativum L, which has served as an experimental model since the earliest investigations (Fred et al 1932). Pea is particularly useful for genetic studies because there are many well-defined marker loci that can be used to locate genes on the linkage map (Weeden et al 1993).…”

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confidence: 99%

Non-nodulating Mutants of Pisum Sativum (L.) cv. Sparkle

Kneen

Weeden

LaRue

1994

Journal of Heredity

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Eleven pea mutants, displaying a greatly reduced number of root nodules or lacking such nodules completely, were obtained by screening the M 2 progeny of mutagenized Pisum sativum cv. Sparkle. The mutant alleles conditioning the altered nodulation phenotypes were recessive to the wild-type alleles. Eight of the mutants possessed a normal growth habit except for the complete lack of nodules. Pairwise crosses among these mutants indicated that five distinct loci had been affected. The remaining three mutants formed few nodules and also had altered root or shoot growth habit. Each of these pleiotropic mutants was coded by a distinct gene. The eight genes identified are designated sym7, sym8, sym9, sym10, sym11, sym15, sym16, and sym17, signifying their involvement in the pea/Rhizobium symbiosis. The locations of most of these sym genes were determined by classical linkage mapping. The loci were distributed on at least five of the seven chromosomes.

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Root Nodule Bacteria and Leguminous Plants

Cited by 210 publications

References 38 publications

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

RFLP analysis of the rRNA operon of a Brazilian collection of bradyrhizobial strains from 33 legume species

Abundance and characterization of cowpea miscellany Rhizobium from sudanese soils

Non-nodulating Mutants of Pisum Sativum (L.) cv. Sparkle

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