Identification of soil bacteria expressing a symbiotic plasmid from Rhizobium leguminosarum bv. trofolii

1997 ◽  
Vol 43 (2) ◽  
pp. 164-177 ◽  
Author(s):  
S. Sivakumaran ◽  
B. D. W. Jarvis ◽  
P. J. Lockhart
Keyword(s):  
Dna Hybridization ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Sandy Loam ◽  
Rhizobium Tropici ◽  
Rhizobium Loti ◽  
Rrna Sequencing ◽  
Reference Strains ◽  
Good Agreement

A hundred strains of non-nodulating, Gram-negative, rod-shaped bacteria were isolated from clover–ryegrass pastures on three different soil types and from a sandy loam under lupins. When crossed with Escherichia coli PN200 containing the cointegrate plasmid pPN1, 11 transconjugants gained the ability to form nodules on the roots of white clover (Trifolium repens cv. Grasslands Huia). A nodA probe indicated that they had gained nodulation genes. The identities of these 11 strains and 4 others derived from earlier work on non-nodulating root nodule bacteria, were determined by ribotyping, DNA – DNA hybridization, and partial 16S rRNA sequencing. Good agreement was obtained between the three methods, and 11 of the strains were identified as Rhizobium leguminosarum (6), Rhizobium loti (2), Rhizobium etli (1), Rhizobium tropici (1), and Sinorhizobium meliloti (1). DNA –DNA hybridization indicated that the remaining four strains were related to the Rhizobium leguminosarum reference strains. The existence of several species of non-nodulating rhizobia in pasture soil, including species for which the normal host plant was absent, is discussed in relation to the fate of symbiotic plasmids from Rhizobium seed inoculants. It is also suggested that new species should be named for the geographical region from which they are first isolated rather than the host plant.Key words: Rhizobium, non-nodulating, nonsymbiotic, isolation, identification.

scholarly journals Conservation of noIR in the Sinorhizobium and Rhizobium Genera of the Rhizobiaceae Family

1998 ◽  
Vol 11 (12) ◽  
pp. 1186-1195 ◽  
Author(s):  
Ernö Kiss ◽  
Peter Mergaert ◽  
Boglàrka Olàh ◽  
Attila Kereszt ◽  
Christian Staehelin ◽  
...  
Keyword(s):  
Dna Binding ◽  
Primary Structure ◽  
Dna Hybridization ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Negative Regulation ◽  
Regulatory Proteins ◽  
Dna Binding Domain ◽  
Nod Factor ◽  
Homologous Sequences

In Sinorhizobium meliloti the NolR repressor displays differential negative regulation of nodulation genes and is required for optimal nodulation. Here, we demonstrate that the NolR function is not unique to S. meliloti but is also present in other species of the Rhizobiaceae family. DNA hybridization indicates the presence of nolR homologous sequences in species belonging to the Rhizobium and Sinorhizobium genera while no hybridization signal was detected in species from the Mesorhizobium, Bradyrhizo-bium, Azorhizobium, and Agrobacterium genera. We isolated the nolR gene from the Rhizobium leguminosarum bv. viciae strain TOM and showed that the TOM nolR gene acts similarly to S. meliloti nolR by repressing the expression of both the nodABCIJ and the nodD genes, resulting in decreased Nod factor production. The presence of a functional nolR gene in R. leguminosarum is correlated with an increased rate and extent of nodulation of pea. The conserved primary structure, the location of the DNA-binding domain, and the similar size of NolR proteins, compared with a family of small bacterial regulatory proteins including HlyU, SmtB, and the ArsR-type regulators, revealed that NolR belongs to this family.

scholarly journals Diversity and numbers of root-nodule bacteria (rhizobia) in Polish soils

2011 ◽  
Vol 74 (1) ◽  
pp. 83-86 ◽  
Author(s):  
Stefan Martyniuk ◽  
Jadwiga Oroń ◽  
Maria Martyniuk
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Nodule Bacteria ◽  
Root Nodule Bacteria ◽  
Plant Infection ◽  
Physical And Chemical ◽  
And Chemical Properties

Using a sand pouch-plant infection method, populations of several species of root-nodule bacteria (rhizobia) were enumerated in eighty soils collected throughout Poland. <em>Rhizobium leguminosarum</em> bv. <em>viciae</em> (symbionts of pea, faba bean, vetch) and <em>R. leguminosarum</em> bv. <em>trifolii</em> (symbionts of clover) were detected in 77 and 76 soils, respectively. Most of these soils contained moderate and high numbers of these species of the rhizobia. Symbionts of beans, <em>R. leguminosarum</em> bv.<em> phaseoli</em>, were assessed in 76 soils; of this number 15 soils had no detectable populations of bean rhizobia and in 40 soils high or moderate numbers of these bacteria were found. <em>Bradyrhizobium</em> sp. (<em>Lupinus</em>), root-nodule bacteria of lupine and serradella, were absent in 19 soils, out of 80 tested, and 34 soils were colonised by high or moderate populations of bradyrhizobia. <em>Sinorhizobium meliloti</em>, rhizobia nodulating alfalfa, were sparse in the examined soils; with 56 soil containing no detectable numbers of <em>S. meliloti</em> and only 6 soils harbouring high or moderate populations of this species. The estimated numbers of the rhizobia in the studied soils were also related to some physical and chemical properties of these soils.

Characteristics of rhizobia nodulating beans in the central region of Minnesota

2004 ◽  
Vol 50 (12) ◽  
pp. 1023-1031 ◽  
Author(s):  
G R Bernal ◽  
B Tlusty ◽  
C Estevez de Jensen ◽  
P van Berkum ◽  
P H Graham
Keyword(s):  
Phaseolus Vulgaris ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Rhizobium Leguminosarum ◽  
Acid Methyl Ester ◽  
Rrna Gene ◽  
Rhizobium Tropici ◽  
Banding Patterns ◽  
Gene Sequence Analysis ◽  
Reference Strains

Until recently, beans (Phaseolus vulgaris L.) grown in Minnesota were rarely inoculated. Because of this, we hypothesized that bean rhizobia collected in Minnesota would either share characteristics identifiable with Rhizobium etli of Mesoamerican or Andean origin, introduced into the region as seed-borne contaminants, or be indigenous rhizobia from prairie species, such as Dalea spp. The latter organisms have been shown to nodulate and fix N2with Phaseolus vulgaris. Rhizobia recovered from the Staples, Verndale, and Park Rapids areas of Minnesota were grouped according to the results of BOXA1R–PCR fingerprint analysis into 5 groups, with only one of these having banding patterns similar to 2 of 4 R. etli reference strains. When representative isolates were subject to fatty acid - methyl ester analysis and 16S rRNA gene sequence analysis, the results obtained differed. 16S rRNA gene sequences of half the organisms tested were most similar to Rhizobium leguminosarum. Rhizobia from Dalea spp., an important legume in the prairie ecosystem, did not play a significant role as the microsymbiont of beans in this area. This appears to be due to the longer time needed for them to initiate infection in Phaseolus vulgaris. Strains of Rhizobium tropici IIB, including UMR1899, proved tolerant to streptomycin and captan, which are commonly applied as seed treatments for beans. Local rhizobia appeared to have very limited tolerance to these compounds.Key words: Rhizobium diversity, Phaseolus vulgaris, seed treatment, taxonomy.

Liming and choice of pasture species improve rhizobial persistence in an acidic chromosol (red-brown earth)

2005 ◽  
Vol 45 (3) ◽  
pp. 247 ◽  
Author(s):  
E. A. Roesner ◽  
N. A. Fettell ◽  
J. Brockwell
Keyword(s):  
Nitrogen Fixation ◽  
Soil Ph ◽  
Dry Matter ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Nodule Bacterium ◽  
Nitrogen Response ◽  
Barrel Medic ◽  
Medicago Species

An experiment was conducted to determine the persistence of soil root-nodule bacteria as influenced by different rates of lime and the previous pasture species. The work was done at Condobolin, central-western New South Wales, on a chromosol (red-brown earth), acidic in the upper profile (pHCa 4.6), which was representative of soils for an extensive region of the eastern Australian wheat belt. In autumn 1997, the experimental area was treated with 4 rates (6.0 t/ha, 3.0 t/ha, 1.5 t/ha, nil) of finely-ground agricultural limestone and sown with 5 pasture species: lucerne (Medicago sativa), barrel medic (M. truncatula), subterranean clover (Trifolium subterraneum), rose clover (T. hirtum) and ryegrass (Lolium rigidum). The pastures were removed with herbicide and cultivation in September 2000. The land lay fallow for 9 months and then was sown to wheat (Triticum aestivum) in autumn 2001 and again in autumn 2002. The most probable numbers of soil (0–10 cm) populations of the root–nodule bacterium for Medicago species (Sinorhizobium meliloti) and for the Trifolium species (Rhizobium leguminosarum bv. trifolii) were counted in May 2001 and May 2002. Soil pH, which was significantly (P<0.05) elevated 12 months after liming, declined substantially during the next 4 years although there was no concomitant decline in the pH of unlimed soil. The pasture species were highly productive of both pasture dry matter and nitrogen. The majority of legume pasture nitrogen was a consequence of symbiotic nitrogen fixation. There was a small but significant (P<0.05) dry matter response to application of lime in lucerne and barrel medic, and a larger nitrogen response to liming in lucerne, barrel medic and rose clover. Nitrogen fixation by rose clover appeared suboptimal. It was assumed from the density of plants that large populations of rhizobia developed in the soil during the growth of the legumes. Nine months after removal of the pasture, rhizobia numbers had fallen to low levels but did not fall further during the following year. The initial fall was attributed to high soil temperatures and low soil moisture during the Condobolin summer. The population of rhizobia for Trifolium species was about twice that of the rhizobia for Medicago species but the difference was not statistically significant. Liming had an overriding influence on the size of rhizobial populations, except in plots that had previously grown ryegrass where numbers remained low irrespective of rate of liming. Overall, most probable numbers escalated with each increase in rate of liming, from 10/g soil in the nil lime plots to 708/g in the 6 t/ha lime plots. The rhizobial homology of the pasture species (i.e. Sinorhizobium meliloti for the Medicago species and Rhizobium leguminosarum bv. trifolii for the Trifolium species) had an underlying but major influence on most probable numbers and in determining which rhizobial species occurred more commonly. Estimated populations of rhizobia in soils from homologous legumes were about 8 times those found in soils from non-homologous legumes. The benefits of applying lime to this red-brown earth soil may not have been merely a consequence of correction of low soil pH; increased levels of calcium may also have had a role. The results are discussed in relation to re-establishment of legume leys after the cereal phase of the cropping system.

scholarly journals Characterization and genus identification of rhizobial symbionts from Caragana arborescens in western Canada

2013 ◽  
Vol 59 (6) ◽  
pp. 399-406 ◽  
Author(s):  
Judicaël Moukoumi ◽  
Russell K. Hynes ◽  
Timothy J. Dumonceaux ◽  
Jennifer Town ◽  
Nicolas Bélanger
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Strain Identification ◽  
Western Canada ◽  
Rhizobium Tropici ◽  
Surface Sterilization ◽  
Yeast Extract Mannitol ◽  
Caragana Arborescens ◽  
Encoding Genes

Naturally occurring nitrogen-fixing symbionts from root nodules of caragana (Caragana arborescens) growing in central Saskatchewan were isolated following surface sterilization of caragana root nodules and squashing and spreading of the contents on yeast extract – mannitol medium. The symbiotic nature of the strains was confirmed following inoculation onto surface-sterilized C. arborescens seed in a gnotobiotic Leonard jar system. The Rhizobium isolates from C. arborescens root nodules were intermediate in generation time (g) (mean g of 5 isolates was 6.41 h) compared with the fast growers, Rhizobium leguminosarum NRG457 (g: 4.44 h), Rhizobium tropici 899 (g: 3.19 h), and Sinorhizobium meliloti BALSAC (g: 3.45 h), but they were faster than the slow-growing Bradyrhizobium japonicum USDA 110 (g: 13.86 h) and similar to Mesorhizobium amorphae (g: 7.76 h). Nitrogen derived from fixation by measuring changes in δ15N natural abundance in plant tissue confirmed the effectiveness of the strains; approximately 80% N2 from fixation. Strain identification was carried out by determining the sequences of 3 genes: 16S rRNA-encoding genes, cpn60, and recA. This analysis determined that the symbiotic partner of Canadian C. arborescens belongs to the genus Mesorhizobium and seems more related to M. loti than to previously described caragana symbionts like M. caraganae. This is the first report of Mesorhizobium sp. nodulating C. arborescens in western Canada.

scholarly journals Occurrence of Choline and Glycine Betaine Uptake and Metabolism in the Family Rhizobiaceae and Their Roles in Osmoprotection

1999 ◽  
Vol 65 (5) ◽  
pp. 2072-2077 ◽  
Author(s):  
Eric Boncompagni ◽  
Magne Østerås ◽  
Marie-Christine Poggi ◽  
Daniel le Rudulier
Keyword(s):  
Glycine Betaine ◽  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum ◽  
Physiological Role ◽  
Betaine Aldehyde Dehydrogenase ◽  
Choline Uptake ◽  
Rhizobium Tropici ◽  
Mesorhizobium Loti ◽  
The Family

ABSTRACT The role of glycine betaine and choline in osmoprotection of various Rhizobium, Sinorhizobium,Mesorhizobium, Agrobacterium, andBradyrhizobium reference strains which display a large variation in salt tolerance was investigated. When externally provided, both compounds enhanced the growth of Rhizobium tropici,Sinorhizobium meliloti, Sinorhizobium fredii,Rhizobium galegae, Agrobacterium tumefaciens,Mesorhizobium loti, and Mesorhizobium huakuii, demonstrating their utilization as osmoprotectants. However, both compounds were inefficient for the most salt-sensitive strains, such asRhizobium leguminosarum (all biovars), Agrobacterium rhizogenes, Rhizobium etli, and Bradyrhizobium japonicum. Except for B. japonicum, all strains exhibit transport activity for glycine betaine and choline. When the medium osmolarity was raised, choline uptake activity was inhibited, whereas glycine betaine uptake was either increased in R. leguminosarum and S. meliloti or, more surprisingly, reduced in R. tropici, S. fredii, and M. loti. The transport of glycine betaine was increased by growing the cells in the presence of the substrate. With the exception ofB. japonicum, all strains were able to use glycine betaine and choline as sole carbon and nitrogen sources. This catabolic function, reported for only a few soil bacteria, could increase competitiveness of rhizobial species in the rhizosphere. Choline dehydrogenase and betaine-aldehyde dehydrogenase activities were present in the cells of all strains with the exception of M. huakuii and B. japonicum. The main physiological role of glycine betaine in the family Rhizobiaceae seems to be as an energy source, while its contribution to osmoprotection is restricted to certain strains.

scholarly journals The Lipid Lysyl-Phosphatidylglycerol Is Present in Membranes of Rhizobium tropici CIAT899 and Confers Increased Resistance to Polymyxin B Under Acidic Growth Conditions

2007 ◽  
Vol 20 (11) ◽  
pp. 1421-1430 ◽  
Author(s):  
Christian Sohlenkamp ◽  
Kanaan A. Galindo-Lagunas ◽  
Ziqiang Guan ◽  
Pablo Vinuesa ◽  
Sally Robinson ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Minimal Medium ◽  
Polymyxin B ◽  
Growth Conditions ◽  
Membrane Lipid ◽  
Low Ph ◽  
Wild Type ◽  
Rhizobium Tropici ◽  
Gram Negative ◽  
Inducible Genes

Lysyl-phosphatidylglycerol (LPG) is a well-known membrane lipid in several gram-positive bacteria but is almost unheard of in gram-negative bacteria. In Staphylococcus aureus, the gene product of mprF is responsible for LPG formation. Low pH-inducible genes, termed lpiA, have been identified in the gram-negative α-proteobacteria Rhizobium tropici and Sinorhizobium medicae in screens for acid-sensitive mutants and they encode homologs of MprF. An analysis of the sequenced bacterial genomes reveals that genes coding for homologs of MprF from S. aureus are present in several classes of organisms throughout the bacterial kingdom. In this study, we show that the expression of lpiA from R. tropici in the heterologous hosts Escherichia coli and Sinorhizobium meliloti causes formation of LPG. A wild-type strain of R. tropici forms LPG (about 1% of the total lipids) when the cells are grown in minimal medium at pH 4.5 but not when grown in minimal medium at neutral pH or in complex tryptone yeast (TY) medium at either pH. LPG biosynthesis does not occur when lpiA is deleted and is restored upon complementation of lpiA-deficient mutants with a functional copy of the lpiA gene. When grown in the low-pH medium, lpiA-deficient rhizobial mutants are over four times more susceptible to the cationic peptide polymyxin B than the wild type.

A rhizobial homolog of IHF stimulates transcription of dctA in Rhizobium leguminosarum but not in Sinorhizobium meliloti

Gene ◽  
1999 ◽  
Vol 238 (2) ◽  
pp. 489-500 ◽  
Author(s):  
John Sojda ◽  
Baohua Gu ◽  
Joon Lee ◽  
Timothy R Hoover ◽  
B.Tracy Nixon
Keyword(s):  
Sinorhizobium Meliloti ◽  
Rhizobium Leguminosarum

scholarly journals Alfalfa Root Nodule Invasion Efficiency Is Dependent on Sinorhizobium melilotiPolysaccharides

2000 ◽  
Vol 182 (15) ◽  
pp. 4310-4318 ◽  
Author(s):  
Brett J. Pellock ◽  
Hai-Ping Cheng ◽  
Graham C. Walker
Keyword(s):  
Molecular Weight ◽  
Sinorhizobium Meliloti ◽  
Root Nodule ◽  
Fluorescent Protein ◽  
Infection Thread ◽  
Low Molecular Weight ◽  
Infection Threads ◽  
Green Fluorescent ◽  
K Antigen ◽  
Alfalfa Root

ABSTRACT The soil bacterium Sinorhizobium meliloti is capable of entering into a nitrogen-fixing symbiosis with Medicago sativa (alfalfa). Particular low-molecular-weight forms of certain polysaccharides produced by S. meliloti are crucial for establishing this symbiosis. Alfalfa nodule invasion by S. meliloti can be mediated by any one of three symbiotically important polysaccharides: succinoglycan, EPS II, or K antigen (also referred to as KPS). Using green fluorescent protein-labeled S. meliloti cells, we have shown that there are significant differences in the details and efficiencies of nodule invasion mediated by these polysaccharides. Succinoglycan is highly efficient in mediating both infection thread initiation and extension. However, EPS II is significantly less efficient than succinoglycan at mediating both invasion steps, and K antigen is significantly less efficient than succinoglycan at mediating infection thread extension. In the case of EPS II-mediated symbioses, the reduction in invasion efficiency results in stunted host plant growth relative to plants inoculated with succinoglycan or K-antigen-producing strains. Additionally, EPS II- and K-antigen-mediated infection threads are 8 to 10 times more likely to have aberrant morphologies than those mediated by succinoglycan. These data have important implications for understanding how S. meliloti polysaccharides are functioning in the plant-bacterium interaction, and models are discussed.

Nodulation studies on legumes exotic to Australia: symbiotic relationships between Chamaecytisus palmensis (tagasaste) and Lotus spp

1994 ◽  
Vol 34 (3) ◽  
pp. 385 ◽  
Author(s):  
RR Gault ◽  
A Pilka ◽  
DM Hebb ◽  
J Brockwell
Keyword(s):  
Host Plants ◽  
Root Nodule ◽  
Pattern Analysis ◽  
Analysis Procedure ◽  
Nodule Bacteria ◽  
Symbiotic Relationships ◽  
The Third ◽  
Rhizobium Loti ◽  
Wide Range ◽  
Bradyrhizobium Sp

Strains of rhizobia were isolated from soil around the roots of tagasaste (Chamaecytisus palmensis) growing at 15 widely separated locations in south-eastem Australia. A further collection of strains of both Rhizobium loti and Bradyrhizobium sp. (Lotus) was assembled from 18 legumes including Lotus and other species symbiotically related to Lotus. The strains were used to inoculate tagasaste and 4 species of Lotus in experiments conducted under bacteriologically controlled conditions in a temperature-controlled glasshouse. Tagasaste formed nodules and fixed N2 with all of its homologous rhizobia but there was a wide range of effectiveness among the 15 strains. Tagasaste also formed nodules with each of the 18 strains from other species but fixed N2 with only 10. Four species of Lotus were inoculated with 3 tagasaste strains. One strain nodulated each species and fixed N2 with L. conimhricensis and L. corniculatus but not with L. parviflorus or L. pedunculatus. A second tagasaste strain formed nodules with all 4 Lotus spp. but did not fix N2, while the third nodulated only L. pedunculatus but did not fix N2. A pattern analysis based on the nodulating ability of the host plants in association with 21 strains showed that tagasaste and L. corniculatus formed 1 symbiotic group, and the other 3 Lotus species formed a third group. The pattern analysis procedure based on nodulating capacity of 21 rhizobial strains in association with the 5 host species indicated substantial symbiotic diversity within the collection, with the strains comprising 8 different symbiotic groups. No strain was highly effective on both tagasaste and any of the 4 species of Lotus. Data were insufficient to classify the root-nodule bacteria of tagasaste as either Rhizobium loti or Bradyrhizobium sp. (Lotus).

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