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Sample records for rhizobium etli final

  1. Rhizobium etli asparaginase II

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    Huerta-Saquero, Alejandro; Evangelista-Martínez, Zahaed; Moreno-Enriquez, Angélica; Perez-Rueda, Ernesto

    2013-01-01

    Bacterial l-asparaginase has been a universal component of therapies for childhood acute lymphoblastic leukemia since the 1970s. Two principal enzymes derived from Escherichia coli and Erwinia chrysanthemi are the only options clinically approved to date. We recently reported a study of recombinant l-asparaginase (AnsA) from Rhizobium etli and described an increasing type of AnsA family members. Sequence analysis revealed four conserved motifs with notable differences with respect to the conserved regions of amino acid sequences of type I and type II l-asparaginases, particularly in comparison with therapeutic enzymes from E. coli and E. chrysanthemi. These differences suggested a distinct immunological specificity. Here, we report an in silico analysis that revealed immunogenic determinants of AnsA. Also, we used an extensive approach to compare the crystal structures of E. coli and E. chrysantemi asparaginases with a computational model of AnsA and identified immunogenic epitopes. A three-dimensional model of AsnA revealed, as expected based on sequence dissimilarities, completely different folding and different immunogenic epitopes. This approach could be very useful in transcending the problem of immunogenicity in two major ways: by chemical modifications of epitopes to reduce drug immunogenicity, and by site-directed mutagenesis of amino acid residues to diminish immunogenicity without reduction of enzymatic activity. PMID:22895060

  2. Metabolic Reconstruction and Modeling of Nitrogen Fixation in Rhizobium etli

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    Resendis-antonio, Osbaldo; Reed, Jennifer L.; Encarnacio?n, Sergio; Collado-vides, Julio; Palsson, Bernhard Ø.

    2007-01-01

    Rhizobiaceas are bacteria that fix nitrogen during symbiosis with plants. This symbiotic relationship is crucial for the nitrogen cycle, and understanding symbiotic mechanisms is a scientific challenge with direct applications in agronomy and plant development. Rhizobium etli is a bacteria which provides legumes with ammonia (among other chemical compounds), thereby stimulating plant growth. A genome-scale approach, integrating the biochemical information available for R. etli, constitutes an...

  3. Rhizobium etli taxonomy revised with novel genomic data and analyses.

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    López-Guerrero, Martha G; Ormeño-Orrillo, Ernesto; Velázquez, Encarna; Rogel, Marco A; Acosta, José Luis; Gónzalez, Victor; Martínez, Julio; Martínez-Romero, Esperanza

    2012-09-01

    The taxonomic position of Phaseolus vulgaris rhizobial strains with available sequenced genomes was examined. Phylogenetic analyses with concatenated conserved genomic fragments accounting for over half of each genome showed that Rhizobium strains CIAT 652, Ch24-10 (newly reported genome) and CNPAF 512 constituted a well-supported group independent from Rhizobium etli CFN 42(T). DNA-DNA hybridization results indicated that CIAT 652, Ch24-10 and CNPAF 512 could correspond to R. etli, although the hybridization values were at the borderline that distinguishes different species. In contrast, experimental hybridization results were higher (over 80%) with Rhizobium phaseoli type strain ATCC 14482(T) in congruence to phylogenetic and ANIm analyses. The latter criterion allowed the reclassification of R. etli strains 8C-3 and Brasil5 as R. phaseoli. It was therefore concluded, based on all the evidence, that the CIAT 652, Ch24-10, and CNPAF 512 strains should be reclassified as R. phaseoli in spite of several common features linking them to R. etli. The R. phaseoli and R. etli speciation process seems to be a more recent event than the speciation that has occurred among other sister species, such as R. leguminosarum-R. etli or R. rhizogenes-R. tropici. PMID:22858268

  4. Rhizobium etli asparaginase II: An alternative for acute lymphoblastic leukemia (ALL) treatment

    OpenAIRE

    Huerta-saquero, Alejandro; Evangelista-marti?nez, Zahaed; Moreno-enriquez, Ange?lica; Perez-rueda, Ernesto

    2013-01-01

    Bacterial l-asparaginase has been a universal component of therapies for childhood acute lymphoblastic leukemia since the 1970s. Two principal enzymes derived from Escherichia coli and Erwinia chrysanthemi are the only options clinically approved to date. We recently reported a study of recombinant l-asparaginase (AnsA) from Rhizobium etli and described an increasing type of AnsA family members. Sequence analysis revealed four conserved motifs with notable differences with respect to the cons...

  5. Effective Symbiosis between Rhizobium etli and Phaseolus vulgaris Requires the Alarmone ppGpp

    OpenAIRE

    Moris, Martine; Braeken, Kristien; Schoeters, Eric; Verreth, Christel; Beullens, Serge; Vanderleyden, Jos; Michiels, Jan

    2005-01-01

    The symbiotic interaction between Rhizobium etli and Phaseolus vulgaris, the common bean plant, ultimately results in the formation of nitrogen-fixing nodules. Many aspects of the intermediate and late stages of this interaction are still poorly understood. The R. etli relA gene was identified through a genome-wide screening for R. etli symbiotic mutants. RelA has a pivotal role in cellular physiology, as it catalyzes the synthesis of (p)ppGpp, which mediates the stringent response in bacteri...

  6. Housekeeping genes essential for pantothenate biosynthesis are plasmid-encoded in Rhizobium etli and Rhizobium leguminosarum

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    los Santos Alejandro

    2011-04-01

    Full Text Available Abstract Background A traditional concept in bacterial genetics states that housekeeping genes, those involved in basic metabolic functions needed for maintenance of the cell, are encoded in the chromosome, whereas genes required for dealing with challenging environmental conditions are located in plasmids. Exceptions to this rule have emerged from genomic sequence data of bacteria with multipartite genomes. The genome sequence of R. etli CFN42 predicts the presence of panC and panB genes clustered together on the 642 kb plasmid p42f and a second copy of panB on plasmid p42e. They encode putative pantothenate biosynthesis enzymes (pantoate-?-alanine ligase and 3-methyl-2-oxobutanoate hydroxymethyltransferase, respectively. Due to their ubiquitous distribution and relevance in the central metabolism of the cell, these genes are considered part of the core genome; thus, their occurrence in a plasmid is noteworthy. In this study we investigate the contribution of these genes to pantothenate biosynthesis, examine whether their presence in plasmids is a prevalent characteristic of the Rhizobiales with multipartite genomes, and assess the possibility that the panCB genes may have reached plasmids by horizontal gene transfer. Results Analysis of mutants confirmed that the panC and panB genes located on plasmid p42f are indispensable for the synthesis of pantothenate. A screening of the location of panCB genes among members of the Rhizobiales showed that only R. etli and R. leguminosarum strains carry panCB genes in plasmids. The panCB phylogeny attested a common origin for chromosomal and plasmid-borne panCB sequences, suggesting that the R. etli and R. leguminosarum panCB genes are orthologs rather than xenologs. The panCB genes could not totally restore the ability of a strain cured of plasmid p42f to grow in minimal medium. Conclusions This study shows experimental evidence that core panCB genes located in plasmids of R. etli and R. leguminosarum are indispensable for the synthesis of pantothenate. The unusual presence of panCB genes in plasmids of Rhizobiales may be due to an intragenomic transfer from chromosome to plasmid. Plasmid p42f encodes other functions required for growth in minimal medium. Our results support the hypothesis of cooperation among different replicons for basic cellular functions in multipartite rhizobia genomes.

  7. Regulatory Role of Rhizobium etli CNPAF512 fnrN during Symbiosis

    OpenAIRE

    Moris, Martine; Dombrecht, Bruno; Xi, Chuanwu; Vanderleyden, Jos; Michiels, Jan

    2004-01-01

    The Rhizobium etli CNPAF512 fnrN gene was identified in the fixABCX rpoN2 region. The corresponding protein contains the hallmark residues characteristic of proteins belonging to the class IB group of Fnr-related proteins. The expression of R. etli fnrN is highly induced under free-living microaerobic conditions and during symbiosis. This microaerobic and symbiotic induction of fnrN is not controlled by the sigma factor RpoN and the symbiotic regulator nifA or fixLJ, but it is due to positive...

  8. Genome Sequence of Rhizobium etli CNPAF512, a Nitrogen-Fixing Symbiont Isolated from Bean Root Nodules in Brazil ?

    OpenAIRE

    Fauvart, Maarten; Sa?nchez-rodri?guez, Aminael; Beullens, Serge; Marchal, Kathleen; Michiels, Jan

    2011-01-01

    Rhizobium etli is a Gram-negative soil-dwelling alphaproteobacterium that carries out symbiotic biological nitrogen fixation in close association with legume hosts. R. etli strains exhibit high sequence divergence and are geographically structured, with a potentially dramatic influence on the outcome of symbiosis. Here, we present the genome sequence of R. etli CNPAF512, a Brazilian isolate from bean nodules. We anticipate that the availability of genome sequences of R. etli strains from dist...

  9. Genomic lineages of Rhizobium etli revealed by the extent of nucleotide polymorphisms and low recombination

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    González Víctor

    2011-10-01

    Full Text Available Abstract Background Most of the DNA variations found in bacterial species are in the form of single nucleotide polymorphisms (SNPs, but there is some debate regarding how much of this variation comes from mutation versus recombination. The nitrogen-fixing symbiotic bacteria Rhizobium etli is highly variable in both genomic structure and gene content. However, no previous report has provided a detailed genomic analysis of this variation at nucleotide level or the role of recombination in generating diversity in this bacterium. Here, we compared draft genomic sequences versus complete genomic sequences to obtain reliable measures of genetic diversity and then estimated the role of recombination in the generation of genomic diversity among Rhizobium etli. Results We identified high levels of DNA polymorphism in R. etli, and found that there was an average divergence of 4% to 6% among the tested strain pairs. DNA recombination events were estimated to affect 3% to 10% of the genomic sample analyzed. In most instances, the nucleotide diversity (? was greater in DNA segments with recombinant events than in non-recombinant segments. However, this degree of recombination was not sufficiently large to disrupt the congruence of the phylogenetic trees, and further evaluation of recombination in strains quartets indicated that the recombination levels in this species are proportionally low. Conclusion Our data suggest that R. etli is a species composed of separated lineages with low homologous recombination among the strains. Horizontal gene transfer, particularly via the symbiotic plasmid characteristic of this species, seems to play an important role in diversity but the lineages maintain their evolutionary cohesiveness.

  10. Phaseolus vulgaris is nodulated in northern Spain by Rhizobium leguminosarum strains harboring two nodC alleles present in American Rhizobium etli strains: biogeographical and evolutionary implications.

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    García-Fraile, Paula; Mulas-García, Daniel; Peix, Alvaro; Rivas, Raúl; González-Andrés, Fernando; Velázquez, Encarna

    2010-08-01

    In this study a collection of rhizobial strains were isolated from effective nodules of Phaseolus vulgaris in a wide region of northern Spain, which is the major producer region of this legume in Spain. The analysis of their core genes, rrs, atpD, and recA, and the 16S-23S intergenic spacer showed that all isolates belong to the phylogenetic group of Rhizobium leguminosarum and some of them were identical to those of strains nodulating Vicia or Trifolium. None of the isolates was identified as Rhizobium etli; however, all of them carry the nodC alleles alpha and gamma harboured by American strains of this species. These alleles were also found in strains nodulating P. vulgaris in southern Spain identified as R. etli. These results suggest that R. etli was carried from America to Spain with common bean seeds, but that they could have found difficulties persisting in the soils of northern Spain, probably because of the climatic conditions. The symbiotic genes of this species could have been transferred, after the arrival of P. vulgaris, to strains of R. leguminosarum already present in northern Spanish soils. PMID:20725128

  11. Analysis of Rhizobium etli and of its symbiosis with wild Phaseolus vulgaris supports coevolution in centers of host diversification

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    Aguilar, O. Mario; Riva, Omar; Peltzer, Eitel

    2004-01-01

    Common beans (Phaseolus vulgaris) comprise three major geographic genetic pools, one in Mexico, Central America, and Colombia, another in the southern Andes, and a third in Ecuador and northern Peru. Species Rhizobium etli is the predominant rhizobia found symbiotically associated with beans in the Americas. We have found polymorphism in the common nodulation gene nodC among R. etli strains from a wide range of geographical origins, which disclosed three nodC types. The different nodC alleles...

  12. Role of trehalose in heat and desiccation tolerance in the soil bacterium Rhizobium etli

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    Reina-Bueno Mercedes

    2012-09-01

    Full Text Available Abstract Background The compatible solute trehalose is involved in the osmostress response of Rhizobium etli, the microsymbiont of Phaseolus vulgaris. In this work, we reconstructed trehalose metabolism in R. etli, and investigated its role in cellular adaptation and survival to heat and desiccation stress under free living conditions. Results Besides trehalose as major compatible solute, R. etli CE3 also accumulated glutamate and, if present in the medium, mannitol. Putative genes for trehalose synthesis (otsAB/treS/treZY, uptake (aglEFGK/thuEFGK and degradation (thuAB/treC were scattered among the chromosome and plasmids p42a, p42c, p42e, and p42f, and in some instances found redundant. Two copies of the otsA gene, encoding trehalose-6-P-synthase, were located in the chromosome (otsAch and plasmid p42a (otsAa, and the latter seemed to be acquired by horizontal transfer. High temperature alone did not influence growth of R. etli, but a combination of high temperature and osmotic stress was more deleterious for growth than osmotic stress alone. Although high temperature induced some trehalose synthesis by R. etli, trehalose biosynthesis was mainly triggered by osmotic stress. However, an otsAch mutant, unable to synthesize trehalose in minimal medium, showed impaired growth at high temperature, suggesting that trehalose plays a role in thermoprotection of R. etli. Desiccation tolerance by R. etli wild type cells was dependent of high trehalose production by osmotic pre-conditioned cells. Cells of the mutant strain otsAch showed ca. 3-fold lower survival levels than the wild type strain after drying, and a null viability after 4 days storage. Conclusions Our findings suggest a beneficial effect of osmotic stress in R. etli tolerance to desiccation, and an important role of trehalose on the response of R. etli to high temperature and desiccation stress.

  13. Enhanced expression of Rhizobium etli cbb? oxidase improves drought tolerance of common bean symbiotic nitrogen fixation.

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    Talbi, C; Sánchez, C; Hidalgo-Garcia, A; González, E M; Arrese-Igor, C; Girard, L; Bedmar, E J; Delgado, M J

    2012-09-01

    To investigate the involvement of Rhizobium etli cbb(3) oxidase in the response of Phaseolus vulgaris to drought, common bean plants were inoculated with the R. etli strain, CFNX713, overexpressing this oxidase in bacteroids (cbb(3)(+)) and subjected to drought conditions. The negative effect of drought on plant and nodule dryweight, nitrogen content, and nodule functionality was more pronounced in plants inoculated with the wild-type (WT) strain than in those inoculated with the cbb(3)(+) strain. Regardless of the plant treatment, bacteroids produced by the cbb(3)(+) strain showed higher respiratory capacity than those produced by the WT strain. Inoculation of plants with the cbb(3)(+) strain alleviated the negative effect of a moderate drought on the respiratory capacity of bacteroids and the energy charge of the nodules. Expression of the FixP and FixO components of the cbb(3) oxidase was higher in bacteroids of the cbb(3)(+) strain than in those of the WT strain under all experimental conditions. The decline in sucrose synthase activity and the decrease in dicarboxylic acids provoked by moderate drought stress were more pronounced in nodules from plants inoculated with the WT strain than in those inoculated with the cbb(3)(+) strain. Taken together, these results suggest that inoculation of plants with a R. etli strain having enhanced expression of cbb(3) oxidase in bacteroids reduces the sensitivity of P. vulgaris-R. etli symbiosis to drought and can modulate carbon metabolism in nodules. PMID:22511804

  14. The Rhizobium etli opt operon is required for symbiosis and stress resistance.

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    Vos, K; Braeken, K; Fauvart, M; Ndayizeye, M; Verhaert, J; Zachurzok, S; Lambrichts, I; Michiels, J

    2007-07-01

    Rhizobium etli is a Gram-negative root-colonizing soil bacterium capable of fixing nitrogen while living in symbiosis with its leguminous host Phaseolus vulgaris. A genome-wide screening for R. etli symbiotic mutants revealed a R. etli operon encoding an oligopeptide ABC-transporter (Opt), two redA homologous genes and one redB gene. Expression analysis showed this opt operon to be transcribed both under free-living and symbiotic conditions and expression levels were demonstrated to be growth-phase-dependent. Plants nodulated by R. etli opt mutants showed a reduced symbiotic nitrogen fixation activity (approximately 50% reduction). Growth experiments with opt mutants in the presence of oligopeptides as the sole nitrogen source confirmed the involvement of the opt genes in oligopeptide uptake. Further phenotypic analysis of the opt mutants revealed them to display an enhanced resistance to the oligopeptide antibiotic bacitracin, an increased susceptibility to the beta-lactam antibiotic ampicillin and a decreased osmotolerance. In conclusion, our results demonstrate that the opt operon plays a crucial role during symbiosis and stress resistance. PMID:17564602

  15. Tyrosinase from Rhizobium etli is involved in nodulation efficiency and symbiosis-associated stress resistance.

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    Piñero, Silvia; Rivera, Javier; Romero, David; Cevallos, Miguel Angel; Martínez, Alfredo; Bolívar, Francisco; Gosset, Guillermo

    2007-01-01

    Tyrosinase (EC 1.14.18.1) is a monophenol oxidase responsible for the synthesis of the black pigment known as melanin. The tyrosinase gene (melA) is plasmid-encoded in many rhizobial species. In Rhizobium etli CFN42, the genetic location of melA in the symbiotic plasmid (p42d) and its RpoN-NifA regulation suggest an involvement in symbiosis. In this work, we analyzed the symbiotic phenotype of a streptomycin-resistant derivative of CFN42 (CE3), a melA mutant (SP2) and a complemented strain (SP66), demonstrating that melA inactivation reduced nodule formation rate and diminished total nodule number by 27% when compared to the CE3 strain. The nitrogen fixation capacity of the mutant strain was not affected. Also, in vitro assays were performed where the resistance of CE3, SP2 and SP66 strains to H(2)O(2) was evaluated; the melA mutant strain was consistently less resistant to peroxide. In another series of experiments, Escherichia coli W3110 strain expressing R. etli melA displayed enhanced resistance to p-hydroxybenzoic, vanillinic and syringic acids, which are phenolic compounds frequently found in the soil. Our results are the first to demonstrate a specific role for tyrosinase in R. etli: this enzyme is required during early symbiosis, apparently providing resistance against reactive oxygen species and phenolic compounds generated as part of the plant protective responses. PMID:17693711

  16. The extracellular proteome of Rhizobium etli CE3 in exponential and stationary growth phase

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    Mendoza-Hernández Guillermo

    2010-10-01

    Full Text Available Abstract Background The extracellular proteome or secretome of symbiotic bacteria like Rhizobium etli is presumed to be a key element of their infection strategy and survival. Rhizobia infect the roots of leguminous plants and establish a mutually beneficial symbiosis. To find out the possible role of secreted proteins we analyzed the extracellular proteome of R. etli CE3 in the exponential and stationary growth phases in minimal medium, supplemented with succinate-ammonium. Results The extracellular proteins were obtained by phenol extraction and identified by LC-ESI MS/MS. We identified 192 and 191 proteins for the exponential and stationary phases respectively. Using the software Signal P, we predicted signal peptides for 12.95% and 35.60% of the proteins identified in the exponential and stationary phases, respectively, which could therefore be secreted by the Sec pathway. For the exponential growth phase, we found in abundance proteins like the ribosomal proteins, toxins and proteins belonging to the group "defence mechanisms". For the stationary growth phase, we found that the most abundant proteins were those with unknown function, and in many of these we identified characteristic domains of proteases and peptidases. Conclusions Our study provided the first dataset of the secretome of R. etli and its modifications, which may lead to novel insights into the adaptive response of different stages of growth. In addition, we found a high number of proteins with unknown function; these proteins could be analyzed in future research to elucidate their role in the extracellular proteome of R. etli.

  17. Defence of Rhizobium etli bacteroids against oxidative stress involves a complexly regulated atypical 2-Cys peroxiredoxin.

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    Dombrecht, Bruno; Heusdens, Christophe; Beullens, Serge; Verreth, Christel; Mulkers, Esther; Proost, Paul; Vanderleyden, Jos; Michiels, Jan

    2005-02-01

    In general, oxidative stress, the consequence of an aerobic lifestyle, induces bacterial antioxidant defence enzymes. Here we report on a peroxiredoxin of Rhizobium etli, prxS, strongly expressed under microaerobic conditions and during the symbiotic interaction with Phaseolus vulgaris. The microaerobic induction of the prxS-rpoN2 operon is mediated by the alternative sigma factor RpoN and the enhancer-binding protein NifA. The RpoN-dependent promoter is also active under low-nitrogen conditions through the enhancer-binding protein NtrC. An additional symbiosis-specific weak promoter is located between prxS and rpoN2. Constitutive expression of prxS confers enhanced survival and growth to R. etli in the presence of H2O2. Single prxS mutants are not affected in their symbiotic abilities or defence response against oxidative stress under free-living conditions. In contrast, a prxS katG double mutant has a significantly reduced (>40%) nitrogen fixation capacity, suggesting a functional redundancy between PrxS and KatG, a bifunctional catalase-peroxidase. In vitro assays demonstrate the reduction of PrxS protein by DTT and thioredoxin. PrxS displays substrate specificity towards H2O2 (Km = 62 microM) over alkyl hydroperoxides (Km > 1 mM). Peroxidase activity is abolished in both the peroxidatic (C56) and resolving (C156) cysteine PrxS mutants, while the conserved C81 residue is required for proper folding of the protein. Resolving of the R. etli PrxS peroxidatic cysteine is probably an intramolecular process and intra- and intersubunit associations were observed. Taken together, our data support, for the first time, a role for an atypical 2-Cys peroxiredoxin against oxidative stress in R. etli bacteroids. PMID:15686565

  18. Rhizobium etli USDA9032 Engineered To Produce a Phenazine Antibiotic Inhibits the Growth of Fungal Pathogens but Is Impaired in Symbiotic Performance?

    OpenAIRE

    Krishnan, Hari B.; Kang, Beom Ryong; Hari Krishnan, Ammulu; Kim, Kil Yong; Kim, Young Cheol

    2006-01-01

    Phenazine production was engineered in Rhizobium etli USDA9032 by the introduction of the phz locus of Pseudomonas chlororaphis O6. Phenazine-producing R. etli was able to inhibit the growth of Botrytis cinerea and Fusarium oxysporum in vitro. Black bean inoculated with phenazine-producing R. etli produced brownish Fix? nodules.

  19. Rhizobium etli asparaginase II: an alternative for acute lymphoblastic leukemia (ALL) treatment.

    Science.gov (United States)

    Huerta-Saquero, Alejandro; Evangelista-Martínez, Zahaed; Moreno-Enriquez, Angélica; Perez-Rueda, Ernesto

    2013-01-01

    Bacterial L-asparaginase has been a universal component of therapies for childhood acute lymphoblastic leukemia since the 1970s. Two principal enzymes derived from Escherichia coli and Erwinia chrysanthemi are the only options clinically approved to date. We recently reported a study of recombinant L-asparaginase (AnsA) from Rhizobium etli and described an increasing type of AnsA family members. Sequence analysis revealed four conserved motifs with notable differences with respect to the conserved regions of amino acid sequences of type I and type II L-asparaginases, particularly in comparison with therapeutic enzymes from E. coli and E. chrysanthemi. These differences suggested a distinct immunological specificity. Here, we report an in silico analysis that revealed immunogenic determinants of AnsA. Also, we used an extensive approach to compare the crystal structures of E. coli and E. chrysantemi asparaginases with a computational model of AnsA and identified immunogenic epitopes. A three-dimensional model of AsnA revealed, as expected based on sequence dissimilarities, completely different folding and different immunogenic epitopes. This approach could be very useful in transcending the problem of immunogenicity in two major ways: by chemical modifications of epitopes to reduce drug immunogenicity, and by site-directed mutagenesis of amino acid residues to diminish immunogenicity without reduction of enzymatic activity. PMID:22895060

  20. Differential Regulation of Rhizobium etli rpoN2 Gene Expression during Symbiosis and Free-Living Growth

    OpenAIRE

    Michiels, Jan; Moris, Martine; Dombrecht, Bruno; Verreth, Christel; Vanderleyden, Jos

    1998-01-01

    The Rhizobium etli rpoN1 gene, encoding the alternative sigma factor ?54 (RpoN), was recently characterized and shown to be involved in the assimilation of several nitrogen and carbon sources during free-living aerobic growth (J. Michiels, T. Van Soom, I. D’hooghe, B. Dombrecht, T. Benhassine, P. de Wilde, and J. Vanderleyden, J. Bacteriol. 180:1729–1740, 1998). We identified a second rpoN gene copy in R. etli, rpoN2, encoding a 54.0-kDa protein which displays 59% amino acid identity wit...

  1. Genetic and physiological characterization of a Rhizobium etli mutant strain unable to synthesize poly-beta-hydroxybutyrate.

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    Cevallos, M. A.; Encarnacio?n, S.; Leija, A.; Mora, Y.; Mora, J.

    1996-01-01

    Rhizobium etli accumulates poly-beta-hydroxybutyrate (PHB) in symbiosis and in free life. PHB is a reserve material that serves as a carbon and/or electron sink when optimal growth conditions are not met. It has been suggested that in symbiosis PHB can prolong nitrogen fixation until the last stages of seed development, but experiments to test this proposition have not been done until now. To address these questions in a direct way, we constructed an R. etli PHB-negative mutant by the inserti...

  2. Pleiotropic effects of a rel mutation on stress survival of Rhizobium etli CNPAF512

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    Beullens Serge

    2008-12-01

    Full Text Available Abstract Background The rel gene of Rhizobium etli (relRet, the nodulating endosymbiont of the common bean plant, determines the cellular level of the alarmone (pppGpp and was previously shown to affect free-living growth and symbiosis. Here, we demonstrate its role in cellular adaptation and survival in response to various stresses. Results Growth of the R. etli relRet mutant was strongly reduced or abolished in the presence of elevated NaCl levels or at 37°C, compared to the wild type. In addition, depending on the cell density, decreased survival of exponentially growing or stationary phase relRet mutant cells was obtained after H2O2, heat or NaCl shock compared to the wild-type strain. Survival of unstressed stationary phase cultures was differentially affected depending on the growth medium used. Colony forming units (CFU of relRet mutant cultures continuously decreased in minimal medium supplemented with succinate, whereas wild-type cultures stabilised at higher CFU levels. Microscopic examination of stationary phase cells indicated that the relRet mutant was unable to reach the typical coccoid morphology of the wild type in stationary phase cultures. Assessment of stress resistance of re-isolated bacteroids showed increased sensitivity of the relRet mutant to H2O2 and a slightly increased resistance to elevated temperature (45°C or NaCl shock, compared to wild-type bacteroids. Conclusion The relRet gene is an important factor in regulating rhizobial physiology, during free-living growth as well as in symbiotic conditions. Additionally, differential responses to several stresses applied to bacteroids and free-living exponential or stationary phase cells point to essential physiological differences between the different states.

  3. Covalent immobilization of recombinant Rhizobium etli CFN42 xylitol dehydrogenase onto modified silica nanoparticles.

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    Zhang, Ye-Wang; Tiwari, Manish Kumar; Jeya, Marimuthu; Lee, Jung-Kul

    2011-04-01

    Rare sugars have many applications in food industry, as well as pharmaceutical and nutrition industries. Xylitol dehydrogenase (XDH) can be used to synthesize various rare sugars enzymatically. However, the immobilization of XDH has not been performed to improve the industrial production of rare sugars. In this study, silica nanoparticles which have high immobilization efficiency were selected from among several carriers for immobilization of recombinant Rhizobium etli CFN42 xylitol dehydrogenase (ReXDH) and subjected to characterization. Among four different chemical modification methods to give different functional groups, the silica nanoparticle derivatized with epoxy groups showed the highest immobilization efficiency (92%). The thermostability of ReXDH was improved more than tenfold by immobilization on epoxy-silica nanoparticles; the t(1/2) of the ReXDH was enhanced from 120 min to 1,410 min at 40 °C and from 30 min to 450 min at 50 °C. The K(m) of ReXDH was slightly altered from 17.9 to only 19.2 mM by immobilization. The immobilized ReXDH had significant reusability, as it retained 81% activity after eight cycles of batch conversion of xylitol into L-xylulose. A?71% conversion and a productivity of 10.7 g?h(-1)l(-1) were achieved when the immobilized ReXDH was employed to catalyze the biotransformation of xylitol to L-xylulose, a sugar that has been used in medicine and in the diagnosis of hepatitis. These results suggest that immobilization of ReXDH onto epoxy-silica nanoparticles has potential industrial application in rare sugar production. PMID:21246353

  4. Regulatory proteins and cis-acting elements involved in the transcriptional control of Rhizobium etli reiterated nifH genes.

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    Valderrama, B.; Da?valos, A.; Girard, L.; Morett, E.; Mora, J.

    1996-01-01

    In Rhizobium etli the nitrogenase reductase genes are reiterated. Strain CE3 has three copies; nifHa and nifHb form part of nifHDK operons with the nitrogenase structural genes, while nifHc is linked to a truncated nifD homolog. Their sequences are identical up to 6 residues upstream from a sigma54-dependent promoter. A remarkable difference among them is the absence of canonical NifA binding sites upstream of nifHc while a canonical binding site is located 200 bp upstream of nifHa and nifHb....

  5. Genomic analysis of cyclic-di-GMP-related genes in rhizobial type strains and functional analysis in Rhizobium etli.

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    Gao, Shanjun; Romdhane, Samir Ben; Beullens, Serge; Kaever, Volkhard; Lambrichts, Ivo; Fauvart, Maarten; Michiels, Jan

    2014-05-01

    Rhizobia are soil bacteria that can fix nitrogen in symbiosis with leguminous plants or exist free living in the rhizosphere. Crucial to their complex lifestyle is the ability to sense and respond to diverse environmental stimuli, requiring elaborate signaling pathways. In the majority of bacteria, the nucleotide-based second messenger cyclic diguanosine monophosphate (c-di-GMP) is involved in signal transduction. Surprisingly, little is known about the importance of c-di-GMP signaling in rhizobia. We have analyzed the genome sequences of six well-studied type species (Bradyrhizobium japonicum, Mesorhizobium loti, Rhizobium etli, Rhizobium leguminosarum, Sinorhizobium fredii, and Sinorhizobium meliloti) for proteins possibly involved in c-di-GMP signaling based on the presence of four domains: GGDEF (diguanylate cyclase), EAL and HD-GYP (phosphodiesterase), and PilZ (c-di-GMP sensor). We find that rhizobia possess a high number of these proteins. Conservation analysis suggests that c-di-GMP signaling proteins modulate species-specific pathways rather than ancient rhizobia-specific processes. Two hybrid GGDEF-EAL proteins were selected for functional analysis, R. etli RHE_PD00105 (CdgA) and RHE_PD00137 (CdgB). Expression of cdgA and cdgB is repressed by the alarmone (p)ppGpp. cdgB is significantly expressed on plant roots and free living. Mutation of cdgA, cdgB, or both does not affect plant root colonization, nitrogen fixation capacity, biofilm formation, motility, and exopolysaccharide production. However, heterologous expression of the individual GGDEF and EAL domains of each protein in Escherichia coli strongly suggests that CdgA and CdgB are bifunctional proteins, possessing both diguanylate cyclase and phosphodiesterase activities. Taken together, our results provide a platform for future studies of c-di-GMP signaling in rhizobia. PMID:24728599

  6. Analysis of Rhizobium etli and of its symbiosis with wild Phaseolus vulgaris supports coevolution in centers of host diversification.

    Science.gov (United States)

    Aguilar, O Mario; Riva, Omar; Peltzer, Eitel

    2004-09-14

    Common beans (Phaseolus vulgaris) comprise three major geographic genetic pools, one in Mexico, Central America, and Colombia, another in the southern Andes, and a third in Ecuador and northern Peru. Species Rhizobium etli is the predominant rhizobia found symbiotically associated with beans in the Americas. We have found polymorphism in the common nodulation gene nodC among R. etli strains from a wide range of geographical origins, which disclosed three nodC types. The different nodC alleles in American strains show varying predominance in their regional distributions in correlation with the centers of bean genetic diversification (BD centers). By cross-inoculating wild common beans from the three BD centers with soils from Mexico, Ecuador, Bolivia, and Northwestern Argentina, the R. etli populations from nodules originated from Mexican soil again showed allele predominance that was opposite to those originated from Bolivian and Argentinean soil, whereas populations from Ecuadorian soil were intermediate. These results also indicated that the preferential nodulation of beans by geographically related R. etli lineages was independent of the nodulating environment. Coinoculation of wild common beans from each of the three BD centers with an equicellular mixture of R. etli strains representative of the Mesoamerican and southern Andean lineages revealed a host-dependent distinct competitiveness: beans from the Mesoamerican genetic pool were almost exclusively nodulated by strains from their host region, whereas nodules of beans from the southern Andes were largely occupied by the geographically cognate R. etli lineages. These results suggest coevolution in the centers of host genetic diversification. PMID:15340138

  7. Lipopolysaccharides of Rhizobium etli Strain G12 Act in Potato Roots as an Inducing Agent of Systemic Resistance to Infection by the Cyst Nematode Globodera pallida

    OpenAIRE

    Reitz, M.; Rudolph, K.; Schro?der, I.; Hoffmann-hergarten, S.; Hallmann, J.; Sikora, R. A.

    2000-01-01

    Recent studies have shown that living and heat-killed cells of the rhizobacterium Rhizobium etli strain G12 induce in potato roots systemic resistance to infection by the potato cyst nematode Globodera pallida. To better understand the mechanisms of induced resistance, we focused on identifying the inducing agent. Since heat-stable bacterial surface carbohydrates such as exopolysaccharides (EPS) and lipopolysaccharides (LPS) are essential for recognition in the symbiotic interaction between R...

  8. Conservation of Plasmid-Encoded Traits among Bean-Nodulating Rhizobium Species

    OpenAIRE

    Brom, Susana; Girard, Lourdes; Garci?a-de Los Santos, Alejandro; Sanjuan-pinilla, Julio M.; Olivares, Jose?; Sanjuan, Juan

    2002-01-01

    Rhizobium etli type strain CFN42 contains six plasmids. We analyzed the distribution of genetic markers from some of these plasmids in bean-nodulating strains belonging to different species (Rhizobium etli, Rhizobium gallicum, Rhizobium giardinii, Rhizobium leguminosarum, and Sinorhizobium fredii). Our results indicate that independent of geographic origin, R. etli strains usually share not only the pSym plasmid but also other plasmids containing symbiosis-related genes, with a similar organi...

  9. Characterization of the NifA-RpoN Regulon in Rhizobium etli in Free Life and in Symbiosis with Phaseolus vulgaris? †

    OpenAIRE

    Salazar, Emmanuel; Di?az-meji?a, J. Javier; Moreno-hagelsieb, Gabriel; Marti?nez-batallar, Gabriel; Mora, Yolanda; Mora, Jaime; Encarnacio?n, Sergio

    2010-01-01

    The NifA-RpoN complex is a master regulator of the nitrogen fixation genes in alphaproteobacteria. Based on the complete Rhizobium etli genome sequence, we constructed an R. etli CFN42 oligonucleotide (70-mer) microarray and utilized this tool, reverse transcription (RT)-PCR analysis (transcriptomics), proteomics, and bioinformatics to decipher the NifA-RpoN regulon under microaerobic conditions (free life) and in symbiosis with bean plants. The R. etli NifA-RpoN regulon was determined to con...

  10. The physiological effects and metabolic alterations caused by the expression of Rhizobium etli pyruvate carboxylase in Escherichia coli.

    Science.gov (United States)

    Gokarn, R R; Evans, J D; Walker, J R; Martin, S A; Eiteman, M A; Altman, E

    2001-07-01

    Oxaloacetate (OAA) plays an important role in the tricarboxylic acid cycle and for the biosynthesis of a variety of cellular compounds. Some microorganisms, such as Rhizobium etli and Corynebacterium glutamicum, are able to synthesize OAA during growth on glucose via either of the enzymes pyruvate carboxylase (PYC) or phosphoenolpyruvate carboxylase (PPC). Other microorganisms, including Escherichia coli, synthesize OAA during growth on glucose only via PPC because they lack PYC. In this study we have examined the effect that the R. etli PYC has on the physiology of E. coli. The expressed R. etli PYC was biotinylated by the native biotin holoenzyme synthase of E. coli and displayed kinetic properties similar to those reported for alpha4 PYC enzymes from other sources. R. etli PYC was able to restore the growth of an E. coli ppc null mutant in minimal glucose medium, and PYC expression caused increased carbon flow towards OAA in wild-type E. coli cells without affecting the glucose uptake rate or the growth rate. During aerobic glucose metabolism, expression of PYC resulted in a 56% increase in biomass yield and a 43% decrease in acetate yield. During anaerobic glucose metabolism, expression of PYC caused a 2.7-fold increase in succinate concentration, making it the major product by mass. The increase in succinate came mainly at the expense of lactate formation. However, in a mutant lacking lactate dehydrogenase activity, expression of PYC resulted in only a 1.7-fold increase in succinate concentration. The decreased enhancement of succinate formation in the /dh mutant was hypothesized to be due to accumulation of pyruvate and NADH, metabolites that affect the interconversion of the active and inactive form of the enzyme pyruvate formate-lyase. PMID:11499929

  11. Engineering the nifH Promoter Region and Abolishing Poly-?-Hydroxybutyrate Accumulation in Rhizobium etli Enhance Nitrogen Fixation in Symbiosis with Phaseolus vulgaris

    OpenAIRE

    Peralta, Humberto; Mora, Yolanda; Salazar, Emmanuel; Encarnacio?n, Sergio; Palacios, Rafael; Mora, Jaime

    2004-01-01

    Rhizobium etli, as well as some other rhizobia, presents nitrogenase reductase (nifH) gene reiterations. Several R. etli strains studied in this laboratory showed a unique organization and contained two complete nifHDK operons (copies a and b) and a truncated nifHD operon (copy c). Expression analysis of lacZ fusion demonstrated that copies a and b in strain CFN42 are transcribed at lower levels than copy c, although this copy has no discernible role during nitrogen fixation. To increase nitr...

  12. The Stringent Response Is Required for Amino Acid and Nitrate Utilization, Nod Factor Regulation, Nodulation, and Nitrogen Fixation in Rhizobium etli

    OpenAIRE

    Caldero?n-flores, Arturo; Du Pont, Gisela; Huerta-saquero, Alejandro; Merchant-larios, Horacio; Servi?n-gonza?lez, Luis; Dura?n, Socorro

    2005-01-01

    A Rhizobium etli Tn5 insertion mutant, LM01, was selected for its inability to use glutamine as the sole carbon and nitrogen source. The Tn5 insertion in LM01 was localized to the rsh gene, which encodes a member of the RelA/SpoT family of proteins. The LM01 mutant was affected in the ability to use amino acids and nitrate as nitrogen sources and was unable to accumulate (p)ppGpp when grown under carbon and nitrogen starvation, as opposed to the wild-type strain, which accumulated (p)ppGpp un...

  13. Identification of Functional mob Regions in Rhizobium etli: Evidence for Self-Transmissibility of the Symbiotic Plasmid pRetCFN42d

    OpenAIRE

    Pe?rez-mendoza, Daniel; Domi?nguez-ferreras, Ana; Mun?oz, Socorro; Soto, Mari?a Jose?; Olivares, Jose?; Brom, Susana; Girard, Lourdes; Herrera-cervera, Jose? A.; Sanjua?n, Juan

    2004-01-01

    An approach originally designed to identify functional origins of conjugative transfer (oriT or mob) in a bacterial genome (J. A. Herrera-Cervera, J. M. Sanjuán-Pinilla, J. Olivares, and J. Sanjuán, J. Bacteriol. 180:4583-4590, 1998) was modified to improve its reliability and prevent selection of undesired false mob clones. By following this modified approach, we were able to identify two functional mob regions in the genome of Rhizobium etli CFN42. One corresponds to the recently characte...

  14. Lipopolysaccharides of Rhizobium etli strain G12 act in potato roots as an inducing agent of systemic resistance to infection by the cyst nematode Globodera pallida.

    Science.gov (United States)

    Reitz, M; Rudolph, K; Schröder, I; Hoffmann-Hergarten, S; Hallmann, J; Sikora, R A

    2000-08-01

    Recent studies have shown that living and heat-killed cells of the rhizobacterium Rhizobium etli strain G12 induce in potato roots systemic resistance to infection by the potato cyst nematode Globodera pallida. To better understand the mechanisms of induced resistance, we focused on identifying the inducing agent. Since heat-stable bacterial surface carbohydrates such as exopolysaccharides (EPS) and lipopolysaccharides (LPS) are essential for recognition in the symbiotic interaction between Rhizobium and legumes, their role in the R. etli-potato interaction was studied. EPS and LPS were extracted from bacterial cultures, applied to potato roots, and tested for activity as an inducer of plant resistance to the plant-parasitic nematode. Whereas EPS did not affect G. pallida infection, LPS reduced nematode infection significantly in concentrations as low as 1 and 0.1 mg ml(-1). Split-root experiments, guaranteeing a spatial separation of inducing agent and challenging pathogen, showed that soil treatments of one half of the root system with LPS resulted in a highly significant (up to 37%) systemic induced reduction of G. pallida infection of potato roots in the other half. The results clearly showed that LPS of R. etli G12 act as the inducing agent of systemic resistance in potato roots. PMID:10919815

  15. FxkR provides the missing link in the fixL-fixK signal transduction cascade in Rhizobium etli CFN42.

    Science.gov (United States)

    Zamorano-Sánchez, David; Reyes-González, Alma; Gómez-Hernández, Nicolás; Rivera, Patricia; Georgellis, Dimitris; Girard, Lourdes

    2012-11-01

    Transcriptional control of the fixK gene in Rhizobium etli and R. leguminosarum bv. viciae is governed by a two-component signal transduction system that diverts from the conventional FixL-FixJ cascade that occurs in model rhizobia. Although a fixL gene, encoding a hybrid histidine kinase (hFixL), is present in R. etli, no fixJ, the cognate response regulator, has been identified. In this work, we present evidence that the pRet42f-located open reading frame RHE_PF00530 (fxkR) encodes a novel response regulator indispensable for fixKf activation under microaerobic growth. Moreover, results from complementation assays demonstrate that the activation of fixKf expression requires the presence of both hFixL and FxkR, and that the fxkR ortholog from R. leguminosarum bv. viciae is able to substitute for FxkR transcriptional control in R. etli. In addition, in these two organisms, hFixL- and FxkR-related proteins were identified in other bacteria, located in close proximity to a fixK-related gene. Using reporter fusions, site-directed mutagenesis, and electrophoretic mobility shift assays, we identified the FxkR binding site upstream from the transcriptional start site of fixKf. Similar to our previous observations for fixL and fixKf mutants, a null mutation in fxkR does not affect the symbiotic effectiveness of the strain. Thus, our findings reveal that FxkR is the long-standing missing key regulator that allows the transduction of the microaerobic signal for the activation of the FixKf regulon. PMID:22809273

  16. Enhanced nitrogen fixation in a Rhizobium etli ntrC mutant that overproduces the Bradyrhizobium japonicum symbiotic terminal oxidase cbb{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Soberon, M.; Lopez, O.; Morera, C.; Girard, M.L.; Tabche, M.L.; Miranda, J. [Univ. Nacional Autonoma de Mexico, Cuernavaca (Mexico)

    1999-05-01

    The ntrC gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. The cytochrome production pattern of a Rhizobium etli ntrC mutant (CFN2012) was studied. CO difference spectral analysis of membranes showed that CFN2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. CFN2012 produced two c-type cytochromes with molecular masses of 27 and 32 kDa in contrast with the wild-type strain, which produced only a 32-kDa c-tye cytochrome. The expression levels of the R. etli fix/NOQP operon, which codes for terminal oxidase cbb{sub 3}, were not affected by the ntrC mutation. However, the production levels of the two c-type cytochromes (27 and 32 kDa) were enhanced at least eightfold when the Bradyrhizobium japonicum fixNOQP operon was expressed in CFN2012 from the nptII promoter (pMSfix{sup c}), suggesting that these proteins are subunits FixO (27 kDa) and FixP (32 kDa) of cbb{sub 3} and that CFN2012/pMSfix{sup c} overproduced this terminal oxidase. CFN2012/pMSfix{sup c} showed a significant increase in its symbiotic performance as judged by the determination of nitrogenase activities of plants inoculated with this strain, suggesting that the overproduction of cbb{sub 3} terminal oxidase correlates with an enhancement in symbiotic nitrogen fixation.

  17. Elucidation of a novel lipid A ?-(1,1)-GalA transferase gene (rgtF) from Mesorhizobium loti: Heterologous expression of rgtF causes Rhizobium etli to synthesize lipid A with ?-(1,1)-GalA.

    Science.gov (United States)

    Brown, Dusty B; Muszynski, Artur; Carlson, Russell W

    2013-05-01

    An unusual ?-(1,1)-galacturonic acid (GalA) lipid A modification has been reported in the lipopolysaccharide of a number of interesting Gram-negative bacteria, including the nitrogen-fixing bacteria Azospirillum lipoferum, Mesorhizobium huakuii and M. loti, the stalk-forming bacterium Caulobacter crescentus and the hyperthermophilic bacterium Aquifex aeolicus. However, the ?-(1,1)-GalA transferase (GalAT) gene, which we have named RgtF, was not identified. Species of the Rhizobium genera produce lipid A with ?-(1,4')-GalA but not ?-(1,1)-GalA. The Rhizobium GalAT, RgtD, is the lipid A ?-(1-4')-GalAT which utilizes the lipid donor dodecaprenyl-phosphate GalA (Dod-P-GalA) for GalA transfer. An additional Rhizobium GalAT, RgtE, is required for the biosynthesis of Dod-P-GalA. We predicted candidate rgtF genes in bacterial species known to produce lipid A with ?-(1,1)-GalA. In order to determine the predicted rgtF gene function, we cloned the M. loti rgtF gene into an expression plasmid and introduced that plasmid into Rhizobium etli strains that do not contain the rgtF gene nor produce lipid A ?-(1,1)-GalA. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis combined with NMR studies revealed that the lipid As from these rgtF-complemented strains were modified with an additional ?-(1,1)-GalA attached to the proximal glucosamine. PMID:23283001

  18. Expressão dos genes nod de Rhizobium tropici, R. etli e R. leguminosarum bv. phaseoli e estabelecimento da nodulação do feijoeiro na presença de exsudatos de sementes de Mimosa flocculosa e Leucaena leucocephala / Expression of nod genes in Rhizobium tropici, R. etli, R. leguminosarum bv. phaseoli and bean nodulation in the presence of Mimosa flocculosa and Leucaena leucocephala seed exudates

    Scientific Electronic Library Online (English)

    F. M., Mercante; A. A., Franco.

    2000-06-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Na etapa inicial da troca de sinais moleculares entre macro e microssimbiontes, a interação do feijoeiro e estirpes de Rhizobium tropici, R. etli e R. leguminosarum bv. phaseoli foi avaliada pela expressão dos genes nod de estirpes bacterianas, contendo a fusão nodA::gusA. Esta avaliação foi efetuad [...] a por meio da atividade da enzima ß-glucuronidase, utilizando, como indutores, exsudatos liberados pelas sementes de Mimosa flocculosa e Leucaena leucocephala. Além disso, avaliou-se o efeito da adição desses exsudatos no estabelecimento da nodulação do feijoeiro, cv. Carioca. Nos testes "in vitro", a mistura de exsudatos de sementes de feijoeiro e M. flocculosa promoveu aumentos sinergísticos significativos na expressão dos genes nod, tanto das estirpes de R. tropici (CIAT 899/pGUS 32 e F 98.5/pGUS 32) quanto de R. etli (CFN 42/pGUS 32). Em condições controladas, a adição dos exsudatos, tanto de M. flocculosa quanto de L. leucocephala, proporcionou aumento significativo na nodulação inicial do feijoeiro, quando foi inoculada a estirpe CFN 42 (R. etli). A nodulação do feijoeiro cultivado em vasos com solo não foi inibida pelo suprimento de N-mineral, quando se inoculou a estirpe CIAT 899 (R. tropici) e foram fornecidos exsudatos de sementes de M. flocculosa. Abstract in english The first steps of molecular signal exchange between the bean plant and its Rhizobium spp. microsymbionts were studied. The effects on nodulation of the addition of seed exudates of two different leguminous tree plants, Mimosa flocculosa or Leucaena leucocephala, in the presence of R. tropici, R. et [...] li or R. leguminosarum bv. phaseoli were studied. The expression of nod genes was also measured "in vitro" by the activity of ß-glucuronidase on different genetically modified strains possessing the fusion nodA::gusA, using as inducers seed exudates from both leguminous trees. In general, a very complex interaction among the different inducers was observed. Seed exudates, both from Mimosa and Leucaena, led to a significant raise on initial nodulation of the bean plant when inoculated with the strain of R. etli CFN 42 but not when inoculated with R. tropici or R. leguminosarum bv. phaseoli. Mixed beans and Mimosa seed exudates presented a sinergistic effect on the expression of nod genes, measured by the activity of ß-glucuronidase, on strains of R. tropici (CIAT 899/pGUS 32, F 98.5/pGUS 32) and R. etli (CFN 42/pGUS 32). The addition of nitrogen did decrease common bean nodulation except when the plants were inoculated with the strain CIAT 899 (R. tropici) and supplied with seed exsudates from M. flocculosa.

  19. Near-full length sequencing of 16S rDNA and RFLP indicates that Rhizobium etli is the dominant species nodulating Egyptian winter Berseem clover (Trifolium alexandrinum L.).

    Science.gov (United States)

    Shamseldin, Abdelaal; Moawad, Hassan; Abd El-Rahim, Wafaa M; Sadowsky, Michael J

    2014-03-01

    Egyptian winter Berseem clover (EWBC) is one of the main important forage legume crops in Egypt that is used for animal feeding in winter and it occupies about 2.5 million feddans (Feddan=4200m(2)) in winter agricultural rotation systems. Forty-eight rhizobial isolates that nodulated this legume host from different geographical regions within Egypt were isolated. RFLP analyses of 16S rDNA (1.5kb) and whole ribosomal DNA (5kb), the sequencing of 16S rDNA, and the sequencing of nodC, nifH and house keeping genes were used to identify these isolates. The RFLP analysis of 16S rDNA (1.5kb) among 15 representative strains with three enzymes generated two genotypes. The largest genotype was similar to Rhizobium etli CFN42T (93.33%) except for strain 902 that failed to re-nodulate EWBC. RFLP analysis of complete ribosomal DNA (5kb) produced five genotypes. The majority of tested strains shared the genotype with R. etli CFN42T (53.33%). Only one strain (1002) shared the genotype with Rhizobium leguminosarum sv. trifolii 3023. The other four strains were comprised of two unique genotypes. Phylogenetic analysis of 16S rDNA sequences revealed that seven representative strains could be divided into two genetic clusters sharing the ancestral clad with R. etli CFN42T. A phylogenetic tree based on nodC gene sequence confirmed that all the examined strains shared the genetic lineage with R. leguminosarum sv. trifolii WSM1325. The phylogenetic trees of house keeping genes are supported strongly the identification of majority of strains as a novel symbiovar of R. etli with new lineages. PMID:24054695

  20. A C subunit of the plant nuclear factor NF-Y required for rhizobial infection and nodule development affects partner selection in the common bean-Rhizobium etli symbiosis.

    Science.gov (United States)

    Zanetti, María Eugenia; Blanco, Flavio A; Beker, María Pía; Battaglia, Marina; Aguilar, O Mario

    2010-12-01

    Legume plants are able to interact symbiotically with soil bacteria to form nitrogen-fixing root nodules. Although specific recognition between rhizobia and legume species has been extensively characterized, plant molecular determinants that govern the preferential colonization by different strains within a single rhizobium species have received little attention. We found that the C subunit of the heterotrimeric nuclear factor NF-Y from common bean (Phaseolus vulgaris) NF-YC1 plays a key role in the improved nodulation seen by more efficient strains of rhizobia. Reduction of NF-YC1 transcript levels by RNA interference (RNAi) in Agrobacterium rhizogenes-induced hairy roots leads to the arrest of nodule development and defects in the infection process with either high or low efficiency strains. Induction of three G2/M transition cell cycle genes in response to rhizobia was impaired or attenuated in NF-YC1 RNAi roots, suggesting that this transcription factor might promote nodule development by activating cortical cell divisions. Furthermore, overexpression of this gene has a positive impact on nodulation efficiency and selection of Rhizobium etli strains that are naturally less efficient and bad competitors. Our findings suggest that this transcription factor might be part of a mechanism that links nodule organogenesis with an early molecular dialogue that selectively discriminates between high- and low-quality symbiotic partners, which holds important implications for optimizing legume performance. PMID:21139064

  1. Regulation of tryptophan genes in Rhizobium leguminosarum.

    OpenAIRE

    Holmgren, E.; Crawford, I. P.

    1982-01-01

    Twelve tryptophan auxotrophs of Rhizobium leguminosarum were characterized biochemically. They were grown in complex and minimal media with several carbon sources, in both limiting and excess tryptophan. Missing enzyme activities allowed assignment of all mutant to the trpE, trpD, trpB, or trpA gene, confirming earlier results with the same mutants (Johnston et al., Mol. Gen. Genet. 165:323-330, 1978). In regulatory experiments, only the first enzyme of the pathway, anthranilate synthase, res...

  2. Coevolution in Rhizobium-legume symbiosis?

    Science.gov (United States)

    Martínez-Romero, Esperanza

    2009-08-01

    Legume nodules, specialized structures for nitrogen fixation, are probably the result of coevolution of plants and ancestral rhizobia. Among the evolutionary processes leading to legume radiation and divergence, coevolution with rhizobia might have occurred. Alternatively, bacteria could have been constantly selected by plants, with bacteria slightly influencing plant evolution (required to fulfill the criteria for a coevolutionary hypothesis). Evidence of bacterial effects on plant evolution is scarce but being searched for. Bacterial genetic plasticity may be indicative of the large capacity of Rhizobium to adapt to legumes. Events such as symbiotic replacement, easy recruitment of symbiotic bacteria by legume plants, and lateral transfer of symbiotic genes seem to erase the coevolutionary or selected relationships in rhizobial-legume symbiosis. In particular, the hypotheses proposed are (1) Rhizobium replaced Bradyrhizobium in a few hosts of the Phaseoleae tribe, Phaseolus vulgaris and P. coccineus; (2) Rhizobium etli as a species did not coevolve with bean; and (3) beta-Proteobacteria replaced alpha-Proteobacteria in South American mimosas. Novel results on symbiosis suggest a more complex evolutionary process for nodulation that may include multiple organisms, such as mycorrhiza, nematodes, and other bacteria in addition to rhizobia. PMID:19485766

  3. Multiplication and Viability of some Rhizobium Strains to be used as Inoculants for Agricultural Biomass Production

    Directory of Open Access Journals (Sweden)

    Simina Neo

    2012-05-01

    Full Text Available Rhizobia are well known for their capacity to establish a symbiosis with legumes. They inhabit root nodules, where they reduce atmospheric nitrogen and make it available to the plant. Biological nitrogen fixation is an important component of sustainable agriculture, and rhizobial inoculants have been applied frequently as biofertilizers. In this review we approach the subject of legumes inoculation in order to improve the nitrogen fixing capacity. In the first part of the experiment, the Rhizobium strains were cultivated on media indicated in the literature as optimal for bacterial growing and development in laboratory conditions. Afterwards, the Rhizobium strains that have grown and accumulate biomass were tested in different conditions of pH and salinity. The biomass accumulation was determinate by spectrophotometer. The obtained values shown that the Rhizobium strains tested can be used to inoculate the legumes cultivated on acid, basic and alkaline soils. Finally, the stability in real time of two strains of Rhizobium (Rhizobium meliloti and Rhizobium japonicum mixed with different supports was evaluated during a 6- months period. The supports studied were: peat, peat and calcium carbonate, zeolite, and ceramic. The highest number of viable cells at the end of the experiment was obtained in ceramic with Rhizobium japonicum (8x105 cells/gram, and the lowest number of viable cells was obtained in zeolite with Rhizobium meliloti (1,1x103 cells/gram.

  4. Oligo- and polysaccharide synthesis by Rhizobium leguminosarum and Rhizobium meliloti.

    OpenAIRE

    Breedveld, M. W.

    1992-01-01

    Rhizobium and Agrobacterium species are capable of synthesizing a variety of extracellular and cellular oligo- and polysaccharides. Changes in environmental conditions may all affect the composition, physical properties, and relative amounts of oligo- and polysaccharides. Interest in the field of Rhizobium polys accharides has resulted from a development in two distinct areas, (i) the role of oligo- and polysaccharides in the microbe- plant interaction, and (ii) studies on the physico- chemic...

  5. Novel Rhizobium lineages isolated from root nodules of the common bean (Phaseolus vulgaris L.) in Andean and Mesoamerican areas.

    Science.gov (United States)

    Ribeiro, Renan Augusto; Ormeño-Orrillo, Ernesto; Dall'Agnol, Rebeca Fuzinatto; Graham, Peter H; Martinez-Romero, Esperanza; Hungria, Mariangela

    2013-09-01

    The taxonomic affiliations of nineteen root-nodule bacteria isolated from the common bean (Phaseolus vulgaris L.) in Mexico, Ecuador and Brazil were investigated by analyses of 16S rRNA and of four protein-coding housekeeping genes. One strain from Mexico could be assigned to Rhizobium etli and two from Brazil to Rhizobium leucaenae, whereas another from Mexico corresponded to a recently described bean-nodulating species-level lineage related to R. etli and Rhizobium phaseoli. Ten strains isolated in Ecuador and Mexico corresponded to three novel Rhizobium lineages that fall into the R. phaseoli/R. etli/Rhizobium leguminosarum clade. One of those lineages, with representatives isolated mostly from Ecuador, seems to be dominant in beans from that Andean region. Only one of the Mexican strains clustered within the Rhizobium tropici clade, but as an independent lineage. Interestingly, four strains were affiliated with species within the Rhizobium radiobacter clade. The existence of yet non-described native Rhizobium lineages in both the Andean and Mesoamerican areas is discussed in relation to common-bean diversity and environmental conditions. PMID:23764913

  6. Genes encoding conserved hypothetical proteins localized in the conjugative transfer region of plasmid pRet42a from Rhizobium etli CFN42 participate in modulating transfer and affect conjugation from different donors

    Science.gov (United States)

    López-Fuentes, Eunice; Torres-Tejerizo, Gonzalo; Cervantes, Laura; Brom, Susana

    2015-01-01

    Among sequenced genomes, it is common to find a high proportion of genes encoding proteins that cannot be assigned a known function. In bacterial genomes, genes related to a similar function are often located in contiguous regions. The presence of genes encoding conserved hypothetical proteins (chp) in such a region may suggest that they are related to that particular function. Plasmid pRet42a from Rhizobium etli CFN42 is a conjugative plasmid containing a segment of approximately 30 Kb encoding genes involved in conjugative transfer. In addition to genes responsible for Dtr (DNA transfer and replication), Mpf (Mating pair formation) and regulation, it has two chp-encoding genes (RHE_PA00163 and RHE_PA00164) and a transcriptional regulator (RHE_PA00165). RHE_PA00163 encodes an uncharacterized protein conserved in bacteria that presents a COG4634 conserved domain, and RHE_PA00164 encodes an uncharacterized conserved protein with a DUF433 domain of unknown function. RHE_PA00165 presents a HTH_XRE domain, characteristic of DNA-binding proteins belonging to the xenobiotic response element family of transcriptional regulators. Interestingly, genes similar to these are also present in transfer regions of plasmids from other bacteria. To determine if these genes participate in conjugative transfer, we mutagenized them and analyzed their conjugative phenotype. A mutant in RHE_PA00163 showed a slight (10 times) but reproducible increase in transfer frequency from Rhizobium donors, while mutants in RHE_PA00164 and RHE_PA00165 lost their ability to transfer the plasmid from some Agrobacterium donors. Our results indicate that the chp-encoding genes located among conjugation genes are indeed related to this function. However, the participation of RHE_PA00164 and RHE_PA00165 is only revealed under very specific circumstances, and is not perceived when the plasmid is transferred from the original host. RHE_PA00163 seems to be a fine-tuning modulator for conjugative transfer. PMID:25642223

  7. Nodule initiation elicited by noninfective mutants of Rhizobium phaseoli.

    OpenAIRE

    Vandenbosch, K. A.; Noel, K. D.; Kaneko, Y.; Newcomb, E. H.

    1985-01-01

    Rhizobium phaseoli CE106, CE110, and CE115, originally derived by transposon mutagenesis (Noel et al., J. Bacteriol. 158:149-155, 1984), induced the formation of uninfected root nodule-like swellings on bean (Phaseolus vulgaris). Bacteria densely colonized the root surface, and root hair curling and initiation of root cortical-cell divisions occurred normally in mutant-inoculated seedlings, although no infection threads formed. The nodules were ineffective, lacked leghemoglobin, and were anat...

  8. Denitrification by Rhizobium meliloti

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, A.

    1996-10-01

    Rhizobium meliloti strains were investigated for their denitrification activity as free-living cells and in nodules on lucerne (Medicago sativa) roots. They were also investigated for presence of nitrous oxide reductase (nos) activity and for genes using a nosZ probe derived from the Pseudomonas stutzeri. To decide whether R. meliloti strains used as inoculants contribute to the total denitrification activity in a lucerne ley, strains with different denitrifying capacities were used in field and laboratory experiments. The nitrate reduction activity of R. meliloti during anaerobic respiration was compared with that of a strain of Pseudomonas aeruginosa. A great diversity in the denitrification activity was found within strains of R. meliloti, and four of thirteen investigated strains showed an obvious denitrification activity. Two denitrifying bacteria were used as references, one strain each of Bradyrhizobium japonicum and P. aeruginosa. All but one of the R. meliloti strains hybridized to the PstI-fragment of the nosZ-gene from P. stutzeri. Two sizes of the hybridizing fragment, 5 and 7 kb, were noticed. Nos activity was only shown in three R. meliloti strains, and these were all characterized by a high denitrification activity. The potential denitrification activity was about 20, 40, and 80 times higher than the actual denitrification activity for lucerne, fallow, and grass, respectively. The potential denitrification activity was almost the same in lucerne and grass planted soils. Compared with the unplanted soil, the presence of lucerne roots in the soil increased the actual denitrification activity, while roots of both plant species, grass and lucerne, increased the potential denitrification activity in the soil. 32 refs, 7 figs, 1 tab

  9. Rhizobium mesosinicum sp. nov., isolated from root nodules of three different legumes.

    Science.gov (United States)

    Lin, Dong Xu; Chen, Wen Feng; Wang, Feng Qin; Hu, Dong; Wang, En Tao; Sui, Xin Hua; Chen, Wen Xin

    2009-08-01

    Thirteen novel strains were isolated from root nodules of three different leguminous plants of the genera Albizia, Kummerowia and Dalbergia grown in China. Cells of these strains were Gram-negative, strictly aerobic, non-spore-forming, motile rods. Phylogenetic analysis of 16S rRNA gene sequences revealed that they belong to the genus Rhizobium. A representative strain, CCBAU 25010T, showed 98.8% 16S rRNA gene sequence similarity to its closest phylogenetic relative, Rhizobium sullae IS123T. The 16S-23S intergenic spacer (ITS) sequence of CCBAU 25010T shared 91.5 and 87.2% sequence similarity, respectively, with those of Rhizobium etli CFN 42T and Rhizobium leguminosarum LMG 14904T. Analysis of the sequences of the housekeeping genes atpD and recA was in agreement with the results of ITS sequence analysis. The nodC gene sequence of CCBAU 25010T was identical to that of Rhizobium tropici CFN 299. DNA-DNA hybridization values for strain CCBAU 25010T ranged from 20.7% (with Rhizobium mongolense USDA 1844T) to 34.4% (with R. leguminosarum USDA 2370T). Cell protein SDS-PAGE, BOX-PCR and several phenotypic characteristics, such as use of sole carbon sources and antibiotic resistance, could differentiate the novel strains from defined Rhizobium species. We therefore propose that the novel strains reported in this study form a novel species, Rhizobium mesosinicum sp. nov., with the type strain CCBAU 25010T (=LMG 24135T =JCM 14777T). PMID:19567587

  10. Genome sequence of Rhizobium sp. strain CCGE510, a symbiont isolated from nodules of the endangered wild bean Phaseolus albescens.

    Science.gov (United States)

    Servín-Garcidueñas, Luis E; Rogel, Marco A; Ormeño-Orrillo, Ernesto; Delgado-Salinas, Alfonso; Martínez-Romero, Julio; Sánchez, Federico; Martínez-Romero, Esperanza

    2012-11-01

    We present the genome sequence of Rhizobium sp. strain CCGE510, a nitrogen fixing bacterium taxonomically affiliated with the R. leguminosarum-R. etli group, isolated from wild Phaseolus albescens nodules grown in native pine forests in western Mexico. P. albescens is an endangered bean species phylogenetically related to P. vulgaris. In spite of the close host relatedness, Rhizobium sp. CCGE510 does not establish an efficient symbiosis with P. vulgaris. This is the first genome of a Rhizobium symbiont from a Phaseolus species other than P. vulgaris, and it will provide valuable new insights about symbiont-host specificity. PMID:23105056

  11. Analysis of cellular fatty acids and phenotypic relationships of Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium species using the Sherlock Microbial Identification System.

    Science.gov (United States)

    Tighe, S W; de Lajudie, P; Dipietro, K; Lindström, K; Nick, G; Jarvis, B D

    2000-03-01

    Previous studies have demonstrated that cellular fatty acid analysis is a useful tool for identifying unknown strains of rhizobia and establishing taxonomic relationships between the species. In this study, the fatty acid profiles of over 600 strains belonging to the genera Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium were evaluated using the gaschromatography-based Sherlock Microbial Identification System (MIS). Data collected with the MIS showed that the three phylogenetically defined biovars of the genus Agrobacterium formed discrete clusters, whilst species belonging to the genus Mesorhizobium formed three subclusters which were easily distinguished. These three subclusters contained Mesorhizobium ciceri and Mesorhizobium mediterraneum, Mesorhizobium tianshanense fatty acid group I and Mesorhizobium plurifarium, and Mesorhizobium huakuii and Mesorhizobium loti. The genus Sinorhizobium was composed of an individual position for Sinorhizobium meliloti and a large cluster comprising Sinorhizobium fredii, Sinorhizobium saheli, Sinorhizobium terangae, Sinorhizobium kostiense and Sinorhizobium arboris. S. meliloti contained significantly higher levels of the fatty acid 19:0 cyclo omega 8 cis and clustered with Rhizobium sp. (Hedysarum coronarium). However, discrimination between the species of genera Sinorhizobium and Rhizobium was a function of the concentration of 16:0 3-OH. The genus Rhizobium contained a single cluster containing Rhizobium sp. (Hedysarum coronarium), Rhizobium gallicum, Rhizobium leguminosarum and Rhizobium etli, along with individual positions for Rhizobium giardinii, Rhizobium tropici, Rhizobium galegae and Rhizobium hainanense. R. tropici and R. hainanense exhibited similarity to Agrobacterium biovar 2, whilst R. galegae was similar to Agrobacterium biovar 1. R. giardinii appeared unique, with comparatively little similarity to the other species. Analysis of the genus Bradyrhizobium revealed large differences from the other genera studied. Two subgroups of Bradyrhizobium elkanii were detected and easily distinguished from Bradyrhizobium japonicum. Bradyrhizobium liaoningense and Bradyrhizobium sp. (Arachis hypogaea), a group isolated from Chinese peanut plants, showed similarities to B. japonicum, whilst a subgroup of M. tianshanense appeared identical to Bradyrhizobium sp. (Arachis hypogaea). PMID:10758890

  12. Polyol metabolism by Rhizobium trifolii.

    OpenAIRE

    Primrose, S. B.; Ronson, C. W.

    1980-01-01

    In Rhizobium trifolii 7000, the polyols myo-inositol, xylitol, ribitol, D-arabitol, D-mannitol, D-sorbital, and dulcitol are metabolized by inducible nicotinamide adenine dinucleotide-dependent polyol dehydrogenases. Five different polyol dehydrogenases were recognized: inositol dehydrogenase, specific for inositil; ribitol dehydrogenase, specific for ribitol; D-arabitol dehydrogenase, which oxidized D-arabitol, D-mannitol, and D-sorbitol; xylitol dehydrogenase, which oxidized xylitol and D-s...

  13. Legume agglutinins that bind to Rhizobium meliloti.

    OpenAIRE

    Seegers, R.; Larue, T. A.

    1985-01-01

    A protein found in seeds and roots of alfalfa (Medicago sativa) was implicated in the specificity of the infection process, based on its binding to the symbiont Rhizobium meliloti. We found an agglutinin with similar properties in seeds and roots of sweet clover (Melilotis alba). The sweet clover differed from alfalfa in nodulation by a mutant strain of R. meliloti, but the agglutinins were indistinguishable by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Rhizobium agglutination...

  14. Effect of Plasmid pIJ1008 from Rhizobium leguminosarum on Symbiotic Function of Rhizobium meliloti

    OpenAIRE

    Bedmar, E. J.; Brewin, N. J.; Phillips, D. A.

    1984-01-01

    Plasmid pIJ1008, which carries determinants for uptake hydrogenase (Hup) activity, was transferred from Rhizobium leguminosarum to Rhizobium meliloti without impairing the capacity of the latter species to form root nodules on alfalfa. The plasmid was still present in rhizobia reisolated from the root nodules of 12 different alfalfa cultivars, but only low levels of Hup activity were detected in alfalfa.

  15. L’élision variable des /R/ et /l/ postconsonantiques finals en français méridional et septentrional : L’effet de l’âge, du lieu d’origine et des facteurs linguistiques

    OpenAIRE

    Myers Emily L.; Ranson Diana L.

    2014-01-01

    Cette étude vise à déterminer si l’élision des consonnes /R/ et /l/ postconsonantiques finales, comme dans autre et table, représente un changement en cours vers la perte de ces consonnes et un changement vers un effacement des différences de prononciation régionales. Pour tester ces hypothèses nous avons analysé le maintien et l’élision des consonnes /R/ et /l/ postconsonantiques dans la parole de 16 locutrices natives réparties en quatre groupes selon leurs âge et lieu d’o...

  16. Congo Red Absorption by Rhizobium leguminosarum

    OpenAIRE

    Kneen, Barbara E.; Larue, Thomas A.

    1983-01-01

    Congo red absorption is generally considered a contraindication of Rhizobium. However, R. leguminosarum takes up the dye on yeast extract-mannitol agar. The uptake of congo red varies among strains of R. leguminosarum, as shown elsewhere with strains of R. trifolii and R. meliloti. Congo red absorption does not distinguish rhizobia from other bacteria, but may be useful as a strain marker.

  17. Host-symbiont interactions-V. The structure of acidic extracellular polysaccharides secreted by Rhizobium leguminosarum and Rhizobium trifolii

    Energy Technology Data Exchange (ETDEWEB)

    Robertsen, B.K.; Aman, P.; Darvill, A.G.; McNeil, M.; Albersheim, P.

    1981-01-01

    The sequence of the glycosyl residues and the anomeric configurations of the glycosl linkages of the acidic polysaccharides secreted by Rhizobium leguminosarum 128c53, Rhizobium leguminosarum 128c63, Rhizobium trifolii NA30, and Rhizobium trifolii 0403 have been determined. Each of the glycosyl residues of these polysaccharides was determined to be in the D configuration and in the pyranose ring form. These results add support to the proposal that R. leguminosarum and R. trifolii have a particularly close genetic relationship. The significance of these results with regard to the possible function of these polysaccharides in the nodulation process is discussed. (JMT)

  18. Identification and manipulation of Rhizobium phytohormone genes

    Energy Technology Data Exchange (ETDEWEB)

    Ditta, G.S.

    1988-06-27

    The goal of this project was to determine whether phytohormone production by the gram-negative bacterium Rhizobium meliloti is required for successful modulation and symbiosis with alfalfa. specifically, we undertook the study of indoleacetic acid (IAA; auxin) production by R. meliloti and sought to create a mutant totally deficient in IAA biosynthesis. For many years it has been known that rhizobia are capable of synthesizing and excreting IAA, and it has often been suggested that this could be of importance for the initiation of root nodule development. Published work demonstrating the involvement of bacterial IAA genes in pathogenesis by Pseudomonas syringae and Agrobacterium tumefaciens further emphasized the need for this type of study in Rhizobium.

  19. Expression of Rhizobium meliloti nod genes in Rhizobium and Agrobacterium backgrounds.

    OpenAIRE

    Yelton, M. M.; Mulligan, J. T.; Long, S. R.

    1987-01-01

    Rhizobium meliloti nod genes are required for the infection of alfalfa. Induction of the nodC gene depends on a chemical signal from alfalfa and on nodD gene expression. By using a nodC-lacZ fusion, we have shown that the induction of the R. meliloti nodC gene and the expression of nodD occur at almost normal levels in other Rhizobium backgrounds and in Agrobacterium tumefaciens, but not in Escherichia coli. Xanthomonas campestris, or Pseudomonas savastanoi. Our results suggest that bacterial...

  20. Portraits du dégénéré en fou, en primitif, en enfant et finalement en artiste.

    Directory of Open Access Journals (Sweden)

    Stéphane Legrand

    2004-04-01

    Full Text Available Cet article traite du concept de « dégénérescence », importé dans la psychiatrie française par Benedict-Auguste Morel dans les années 1850, et largement diffusé par la suite, dans ce champ ainsi que dans celui de la criminologie. On tente d’analyser la reconfiguration qu’impose ce concept au savoir psychiatrique en dégageant la manière dont il permet d’intégrer en un ensemble cohérent plusieurs modèles théoriques: un paradigme neurologique, une théorie de l’automatisme morbide, un certain évolutionnisme. Sur ces bases, on essaie d’établir les similitudes de fonds existant entre les conceptions psychiatrique et criminologique de la dégénérescence, en montrant qu’elles mobilisent le même réseau « structurant » d’analogies entre les figures de l’anormal (le fou, le sauvage, l’enfant, la femme, l’animal; et l’on s’efforce de montrer que ces théories promeuvent une logique dans laquelle les infractions aux différents types de normes (biologiques, sociales, morales, juridiques, psychologiques, économiques sont susceptibles de faire systématiquement référence les unes aux autres, de se traduire les unes dans les autres. Puis l’on caractérise les transformations que ce nouveau paradigme impose aux principes de la thérapeutique, de la pédagogie et de la prise en charge des malades mentaux et des déviants. Pour finir, on présente les éléments latents qui dans ce paradigme préparent et indiquent déjà sa remise en cause et son renversement à venir.This article deals with the concept of «degeneration», introduced by Benedict-Auguste Morel in the French psychiatry during the 1850s, and which widely spread afterwards, in this field as well as in the contemporary criminology. An analysis is tried of the changes imposed by this notion on the psychiatric knowledge, changes that resulted in the integration in a coherent system of three other paradigms: a neurological paradigm, a theory of pathological automatism, a certain kind of evolutionary theory. The author then tries to establish the existence of background similarities between the psychiatric and criminological theories of degeneration, namely in as much as they promote the same «structural» analogies between the various forms of abnormality (the madman, the primitive, the woman, the child, the animal; and it is shown that these theories also imply a logic in which all the transgressions of the different kinds of norms (biological, social, moral, juridical, psychological, economical tend to be systematically referred to one another, and translated into one another. Then a sketch is given of the changes imposed by this paradigm to the principles of therapy and pedagogy for the insane persons. And finally the author presents some of the themes that, in this paradigm, already prepare its deconstruction to come.

  1. Biodegradation of Phosphonomycin by Rhizobium huakuii PMY1

    OpenAIRE

    Mcgrath, John W.; Hammerschmidt, Friedrich; Quinn, John P.

    1998-01-01

    The biodegradation by Rhizobium huakuii PMY1 of up to 10 mM phosphonomycin as a carbon, energy, and phosphorus source with accompanying Pi release is described. This biodegradation represents a further mechanism of resistance to this antibiotic and a novel, phosphate-deregulated route for organophosphonate metabolism by Rhizobium spp.

  2. Characterization of the nodulation plasmid encoded chemoreceptor gene mcpG from Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Del Bel Kate L

    2003-01-01

    Full Text Available Abstract Background In general, chemotaxis in Rhizobium has not been well characterized. Methyl accepting chemotaxis proteins are sensory proteins important in chemotaxis of numerous bacteria, but their involvement in Rhizobium chemotaxis is unclear and merits further investigation. Results A putative methyl accepting chemotaxis protein gene (mcpG of Rhizobium leguminosarum VF39SM was isolated and characterized. The gene was found to reside on the nodulation plasmid, pRleVF39d. The predicted mcpG ORF displayed motifs common to known methyl-accepting chemotaxis proteins, such as two transmembrane domains and high homology to the conserved methylation and signaling domains of well-characterized MCPs. Phenotypic analysis of mcpG mutants using swarm plates did not identify ligands for this putative receptor. Additionally, gene knockouts of mcpG did not affect a mutant strain's ability to compete for nodulation with the wild type. Notably, mcpG was found to be plasmid-encoded in all strains of R. leguminosarum and R. etli examined, though it was found on the nodulation plasmid only in a minority of strains. Conclusions Based on sequence homology R. leguminosarum mcpG gene codes for a methyl accepting chemotaxis protein. The gene is plasmid localized in numerous Rhizobium spp. Although localized to the sym plasmid of VF39SM mcpG does not appear to participate in early nodulation events. A ligand for McpG remains to be found. Apparent McpG orthologs appear in a diverse range of proteobacteria. Identification and characterization of mcpG adds to the family of mcp genes already identified in this organism.

  3. Rhizobium halotolerans sp. nov., Isolated from chloroethylenes contaminated soil.

    Science.gov (United States)

    Diange, Eboa Adolf; Lee, Sang-Seob

    2013-06-01

    The strain designated as AB21(T) was isolated from chloroethylenes contaminated soil. Cells are gram-negative, aerobic, non-spore-forming, and motile rods. Phylogenetic analysis based on 16S rRNA gene sequence showed that it belonged to the genus Rhizobium, and was closely related to Rhizobium sullae IS 123(T) (97.4 %), Rhizobium yanglingense SH 22623(T) (97.2 %), Rhizobium gallicum R 602sp(T) (97.1 %), Rhizobium alamii GBV 016(T) (97.0 %), and Rhizobium monogolense USDA 1844(T) (97.0 %). It showed less than 97 % identity with the remaining Rhizobium species. This novel isolate grew optimally at 25-37 °C (optimum, 30 °C) and pH 6-9 (optimum, pH 8.0). It grew in the presence of 0-4 % (w/v) NaCl, tolerating a 4 % (w/v) NaCl. DNA-DNA hybridization experiment shows less than 53 % binding with closely related Rhizobium. Predominant quinone is ubiquinone (Q-10). The major fatty acids were summed feature 8 (composed of C(18:1) ?7c/C(18:1) ?6c), C(19:0) cyclo ?8c, and C(16:0). The G+C molar content is 62.5 mol%. Based on the polyphasic analysis, strain AB21(T) is referred to be a novel species of the genus Rhizobium for which the name Rhizobium halotolerans sp. nov. is proposed. The type strain is AB21(T) (=KEMC 224-056(T) = JCM 17536(T)). PMID:23377488

  4. (A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis)

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-01-01

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  5. Symbiotic Characteristics of Rhizobium leguminosarum bv. trifolii Isolates Which Represent Major and Minor Nodule-Occupying Chromosomal Types of Field-Grown Subclover (Trifolium subterraneum L.) †

    OpenAIRE

    Leung, K.; Wanjage, F. N.; Bottomley, P. J.

    1994-01-01

    The symbiotic effectiveness and nodulation competitiveness of Rhizobium leguminosarum bv. trifolii soil isolates were evaluated under nonsoil greenhouse conditions. The isolates which we used represented both major and minor nodule-occupying chromosomal types (electrophoretic types [ETs]) recovered from field-grown subclover (Trifolium subterraneum L.). Isolates representing four ETs (ETs 2, 3, 7, and 8) that were highly successful field nodule occupants fixed between 2- and 10-fold less nitr...

  6. Growth of fast- and slow-growing rhizobia on ethanol. [Bradyrhizobium sp. ; Rhizobium meliloti; Rhizobium loti; Rhizobium leguminosarum; Rhizobium fredii; Bradyrhizobium japonicum

    Energy Technology Data Exchange (ETDEWEB)

    Sadowsky, M.J.; Bohlool, B.B.

    1986-10-01

    Free-living soybean rhizobia and Bradyrhizobium spp. (lupine) have the ability to catabolize ethanol. Of the 30 strains of rhizobia examined, only the fast- and slow-growing soybean rhizobia and the slow-growing Bradyrhizobium sp (lupine) were capable of using ethanol as a sole source of carbon and energy for growth. Two strains from each of the other Rhizobium species examined (R. meliloti, R. loti, and R. leguminosarum biovars phaseoli, trifolii, and viceae) failed to grow on ethanol. One Rhizobium fredii (fast-growing) strain, USDA 191, and one (slow-growing) Bradyrhizobium japonicum strain, USDA 110, grew in ethanol up to concentrations of 3.0 and 1.0%, respectively. While three of the R. fredii strains examined (USDA 192, USDA 194, and USDA 205) utilized 0.2% acetate, only USDA 192 utilized 0.1% n-propanol. None of the three strains utilized 0.1% methanol, formate, or n-butanol as the sole carbon source.

  7. Rhizobium laguerreae sp. nov. nodulates Vicia faba on several continents.

    Science.gov (United States)

    Saïdi, Sabrine; Ramírez-Bahena, Martha-Helena; Santillana, Nery; Zúñiga, Doris; Álvarez-Martínez, Estela; Peix, Alvaro; Mhamdi, Ridha; Velázquez, Encarna

    2014-01-01

    Several fast-growing strains nodulating Vicia faba in Peru, Spain and Tunisia formed a cluster related to Rhizobium leguminosarum. The 16S rRNA gene sequences were identical to that of R. leguminosarum USDA 2370(T), whereas rpoB, recA and atpD gene sequences were phylogenetically distant, with sequence similarities of less than 96?%, 97?% and 94?%, respectively. DNA-DNA hybridization analysis showed a mean relatedness value of 43?% between strain FB206(T) and R. leguminosarum USDA 2370(T). Phenotypic characteristics of the novel strains also differed from those of the closest related species of the genus Rhizobium. Therefore, based on genotypic and phenotypic data obtained in this study, we propose to classify this group of strains nodulating Vicia faba as a novel species of the genus Rhizobium named Rhizobium laguerreae sp. nov. The type strain is FB206(T) (?=?LMG 27434(T)?=?CECT 8280(T)). PMID:24067731

  8. Rhizobium leguminosarum mutants incapable of normal extracellular polysaccharide production.

    OpenAIRE

    Napoli, C.; Albersheim, P.

    1980-01-01

    Mutants of Rhizobium leguminosarum which are deficient in normal polysaccharide production have been isolated and characterized. A correlation between diminished production of extracellular polysaccharide and reduced infection and nodulation efficiency has been observed.

  9. Intragenomic diversity of Rhizobium leguminosarum bv. trifolii clover nodule isolates

    Directory of Open Access Journals (Sweden)

    Marek-Kozaczuk Monika

    2011-05-01

    Full Text Available Abstract Background Soil bacteria from the genus Rhizobium are characterized by a complex genomic architecture comprising chromosome and large plasmids. Genes responsible for symbiotic interactions with legumes are usually located on one of the plasmids, named the symbiotic plasmid (pSym. The plasmids have a great impact not only on the metabolic potential of rhizobia but also underlie genome rearrangements and plasticity. Results Here, we analyzed the distribution and sequence variability of markers located on chromosomes and extrachromosomal replicons of Rhizobium leguminosarum bv. trifolii strains originating from nodules of clover grown in the same site in cultivated soil. First, on the basis of sequence similarity of repA and repC replication genes to the respective counterparts of chromids reported in R. leguminosarum bv. viciae 3841 and R. etli CFN42, chromid-like replicons were distinguished from the pool of plasmids of the nodule isolates studied. Next, variability of the gene content was analyzed in the different genome compartments, i.e., the chromosome, chromid-like and 'other plasmids'. The stable and unstable chromosomal and plasmid genes were detected on the basis of hybridization data. Displacement of a few unstable genes between the chromosome, chromid-like and 'other plasmids', as well as loss of some markers was observed in the sampled strains. Analyses of chosen gene sequences allowed estimation of the degree of their adaptation to the three genome compartments as well as to the host. Conclusions Our results showed that differences in distribution and sequence divergence of plasmid and chromosomal genes can be detected even within a small group of clover nodule isolates recovered from clovers grown at the same site. Substantial divergence of genome organization could be detected especially taking into account the content of extrachromosomal DNA. Despite the high variability concerning the number and size of plasmids among the studied strains, conservation of the location as well as dynamic distribution of the individual genes (especially replication genes of a particular genome compartment were demonstrated. The sequence divergence of particular genes may be affected by their location in the given genome compartment. The 'other plasmid' genes are less adapted to the host genome than the chromosome and chromid-like genes.

  10. Reiterated DNA Sequences in Rhizobium and Agrobacterium spp

    OpenAIRE

    Flores, M.; Gonza?lez, V.; Brom, S.; Marti?nez, E.; Pin?ero, D.; Romero, D.; Da?vila, G.; Palacios, R.

    1988-01-01

    Repeated DNA sequences are a general characteristic of eucaryotic genomes. Although several examples of DNA reiteration have been found in procaryotic organisms, only in the case of the archaebacteria Halobacterium halobium and Halobacterium volcanii [C. Sapienza and W. F. Doolittle, Nature (London) 295:384-389, 1982], has DNA reiteration been reported as a common genomic feature. The genomes of two Rhizobium phaseoli strains, one Rhizobium meliloti strain, and one Agrobacterium tumefaciens s...

  11. Optimization of Dairy Sludge for Growth of Rhizobium Cells

    Science.gov (United States)

    Singh, Ashok Kumar; Singh, Gauri; Gautam, Digvijay; Bedi, Manjinder Kaur

    2013-01-01

    In this study dairy sludge was evaluated as an alternative cultivation medium for Rhizobium. Growth of bacterial strains at different concentrations of Dairy sludge was monitored. Maximum growth of all strains was observed at 60% Dairy sludge concentration. At 60% optical density (OD) values are 0.804 for Rhizobium trifolii (MTCC905), 0.825 for Rhizobium trifolii (MTCC906), and 0.793 for Rhizobium meliloti (MTCC100). Growth pattern of strains was observed at 60% Dairy sludge along with different synthetic media (tryptone yeast, Rhizobium minimal medium and yeast extract mannitol). Growth in 60% Dairy sludge was found to be superior to standard media used for Rhizobium. Media were optimized using 60% dairy sludge along with different concentrations of yeast extract (1–7?g/L) and mannitol (7–13?g/L) in terms of optical density at different time intervals, that is, 24, 48 and 72 hours. Maximum growth was observed in 6?g/L of yeast extract and 12?g/L of mannitol at 48-hour incubation period in all strains. The important environmental parameters such as pH were optimized using 60% dairy sludge, 60% dairy sludge +6?g/L yeast extract, and 60% dairy sludge +12?g/L mannitol. The maximum growth of all strains was found at pH 7.0. The present study recommends the use of 60% dairy sludge as a suitable growth medum for inoculant production. PMID:24089690

  12. Pré-seleção de estirpes de Rhizobium sp. para amendoim Preliminary selection of peanut Rhizobium sp. strains

    OpenAIRE

    Antonio Roberto Giardini; Eli Sidney Lopes; André Martin Louis Neptune

    1984-01-01

    Um ensaio foi conduzido em casa de vegetação, com solução nutritiva isenta de N, com o objetivo de selecionar estirpes de Rhizobium eficientes fixadoras de N2, quando associadas com amendoim (Arachis hypogaea L.) cultivar Tatu. Foram testadas 35 estirpes de Rhizobium sp., isoladas de quinze diferentes espécies de leguminosas tropicais, e incluído um tratamento de inoculação com solo previamente cultivado com amendoim. Das 35 estirpes testadas, doze formaram nódulos e, entre essas, se...

  13. Absorción de cobre y características de Leucaena leucocephala asociada con Glomus spp. y Rhizobium en suelo contaminado del Río Lerma, México

    Directory of Open Access Journals (Sweden)

    Abdul Khalil Gardezi

    2006-01-01

    Full Text Available El objetivo de esta investigación fue evaluar (a la capacidad de absorción de Cu por Leucaena leucocephala y (b el efecto en sus características agronómicas al inocularse con hongos endomicorrízicos arbusculares y Rhizobium como alternativa para la fitorremediación de suelos agrícolas contaminados. El trabajo se realizó en condiciones de invernadero en suelo contaminado por Cu procedente de la parte alta de la cuenca del río Lerma, estado de México. Las plantas de Leucaena crecieron en bolsas de polietileno negro con 3 kg del suelo contaminado esterilizado o no esterilizado. Se aplicaron 0, 20 y 200 mg de Cu kg-1 de suelo contaminado tratado con Glomus sp. Zac-19, Glomus intraradices o sin Glomus, e inoculado con Rhizobium o sin Rhizobium. Se evaluaron la acumulación de Cu en las plantas, sus características agronómicas y el contenido final de Cu en el suelo. La acumulación de Cu en las plantas fue mayor en tallos que en hojas y se asoció a la disminución de su concentración en el suelo a través del tiempo. No hubo efecto de la esterilización del suelo sobre la acumulación de Cu, ni sobre las características agronómicas de las plantas, excepto sobre el número de nódulos de Rhizobium. Se observó significativamente (P < 0.05 mayor acumulación de Cu al incrementarse su concentración en el suelo, destacando un efecto positivo de 20 mg de Cu kg-1 de suelo al mejorar las características agronómicas. Las plantas con mejores características agronómicas disminuyeron su tendencia a la absorción de Cu en presencia simultánea de Glomus spp. y Rhizobium. Esto demuestra un efecto interactivo positivo de la doble inoculación endomicorriza más Rhizobium en la absorción de Cu por las plantas de Leucaena y aumenta su papel en el diseño de estrategias de reforestación y fitorremediación de suelos agrícolas contaminados por cobre.

  14. Delayed maturation of nodules reduces symbiotic effectiveness of the Lotus japonicus–Rhizobium sp. NGR234 interaction

    OpenAIRE

    Schumpp, Olivier; Cre?vecoeur, Miche?le; Broughton, William John; Deakin, William James

    2008-01-01

    Lotus japonicus, a model legume, develops an efficient, nitrogen-fixing symbiosis with Mesorhizobium loti that promotes plant growth. Lotus japonicus also forms functional nodules with Rhizobium sp. NGR234 and R. etli. Yet, in a plant defence-like reaction, nodules induced by R. etli quickly degenerate, thus limiting plant growth. In contrast, nodules containing NGR234 are long-lasting. It was found that NGR234 initiates nodule formation in a similar way to M. loti MAFF303099, but that the no...

  15. The beneficial effect of dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover

    Directory of Open Access Journals (Sweden)

    Lin, XG.

    1993-01-01

    Full Text Available Investigation on the effect of phosphorus on vesicular-arbuscular mycorrhizal infection, and dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover under field microplots and pot experiments was conducted on fluvo-aquic soils of semi-arid region in north China. The results showed that 60 kg P205 ha in form of superphosphate was the most favorable phosphorus level for vesicular-arbuscular mycorrhizal infection ; mycorrhizal infection, nodulation, dry weight of shoots and roots, total uptake of nitrogen, phosphorus and other elements, the final yields and recovery of phosphorus of white clover were significantly increased by vesicular-arbuscular mycorrhizal inoculation and dual inoculation with vesicular-arbuscular mycorrhizal fungi and rhizobium. The highest response of inoculation was obtained by adding fertilizer phosphorus at the level of 60 kg P205 ha in form of superphosphate.

  16. Phylogenetic diversity of Rhizobium strains nodulating diverse legume species growing in Ethiopia.

    Science.gov (United States)

    Degefu, Tulu; Wolde-meskel, Endalkachew; Frostegård, Åsa

    2013-06-01

    The taxonomic diversity of thirty-seven Rhizobium strains, isolated from nodules of leguminous trees and herbs growing in Ethiopia, was studied using multilocus sequence analyses (MLSA) of six core and two symbiosis-related genes. Phylogenetic analysis based on the 16S rRNA gene grouped them into five clusters related to nine Rhizobium reference species (99-100% sequence similarity). In addition, two test strains occupied their own independent branches on the phylogenetic tree (AC86a2 along with R. tibeticum; 99.1% similarity and AC100b along with R. multihospitium; 99.5% similarity). One strain from Milletia ferruginea was closely related (>99%) to the genus Shinella, further corroborating earlier findings that nitrogen-fixing bacteria are distributed among phylogenetically unrelated taxa. Sequence analyses of five housekeeping genes also separated the strains into five well-supported clusters, three of which grouped with previously studied Ethiopian common bean rhizobia. Three of the five clusters could potentially be described into new species. Based on the nifH genes, most of the test strains from crop legumes were closely related to several strains of Ethiopian common bean rhizobia and other symbionts of bean plants (R. etli and R. gallicum sv. phaseoli). The grouping of the test strains based on the symbiosis-related genes was not in agreement with the housekeeping genes, signifying differences in their evolutionary history. Our earlier studies revealing a large diversity of Mesorhizobium and Ensifer microsymbionts isolated from Ethiopian legumes, together with the results from the present analysis of Rhizobium strains, suggest that this region might be a potential hotspot for rhizobial biodiversity. PMID:23643092

  17. Un établissement rural de La Tène finale à Couesmes, La Tesserie (Indre-et-Loire A rural settlement from the final La Tène in La Tesserie (Couesmes, Indre-et-Loire, France

    Directory of Open Access Journals (Sweden)

    Bénédicte Quilliec

    2012-02-01

    Full Text Available Découvert en 2007, lors du diagnostic archéologique du projet de déviation de la RD766 de Château-la-Vallière (Indre-et-Loire, l’établissement rural de La Tesserie (commune de Couesmes a fait l’objet d’une fouille préventive par le Service de l’Archéologie du département d’Indre-et-Loire (SADIL, sous la direction scientifique de Bénédicte Quilliec, responsable d’opération durant l’hiver 2008-2009. Il s’agit d’un habitat de La Tène finale, organisé autour d’un enclos fossoyé quadrangulaire d’environ 60 m de côté et comprenant une douzaine de bâtiments de tailles et de fonctions différentes. Les connaissances sur ce type d’occupation sont encore lacunaires dans le département car elles sont soumises aux contraintes habituelles de l’archéologie préventive. Dans ces conditions, l’apport de la fouille de Couesmes est important car d’une part, toute la surface de l’établissement a été fouillée et la plupart des structures ont été fouillées intégralement et car, d’autre part, tout le mobilier a été étudié. Par ailleurs, certains aspects du site présentent un caractère suffisamment original pour contribuer à la caractérisation de l’habitat rural dans le centre de la Gaule à La Tène finale (architecture, dépôts d’objets.The La Tesserie site (Couesmes, Indre-et-Loire was found during an archaeological evaluation in 2007. This site is a rural dwelling located on 2.5 ha on the route of a future departmental road (RD766, Château-la-Vallière. Excavations were carried out during the winter 2008-2009 by Indre-et-Loire’s Departmental Archaeological Service (SADIL, managed by Bénédicte Quilliec. The settlement from the end of La Tène is organized around a quadrangular ditch (about 60 m side with different kinds of constructions (structures, functions, sizesKnowledge of this kind of site is still lacking because it depends directly on the archaeological survey as in the remainder of the Indre-et-Loire department. Therefore the excavation of La Tesserie was a great opportunity because the entire surface covered by the settlement was excavated providing useful information. In the light of the new data resulting from the study of several assemblies coming from varied structures, it is possible to better define the architectural constructions and identify the ceramic, bronze and iron furnishings and also animal bones and seeds. In addition this study enabled comparison to be made with various similar sites in the north of France.

  18. Physiological role of calcium in legume-rhizobium symbiosis

    Directory of Open Access Journals (Sweden)

    Vasil’eva G.G.

    2011-12-01

    Full Text Available Literature data on the physiological role of calcium (Ca2+ in legume-rhizobium symbiosis development on initial stages - the infection and symbiotic structures formation, are generalized. The questions about the Ca2+ function in plants, special feature the formation of legume-rhizobium symbiosis and role of calcium in the interaction of two organisms are considered. Data on the interaction of ROS and Ca2+ in the development of the legume-rhizobium symbiosis and the relationship of NADPH-oxidase activity with the calcium signaling system are analyzed. The special attention is given to the role of Ca22+-spiking and calcium and calmodulin-like kinase in the initiation of plant symbiotic ways operation leads to infection and the formation of symbiotic structures.

  19. Danish Rhizobium leguminosarum strains nodulating ‘Afghanistan’ pea (Pisum sativum)

    DEFF Research Database (Denmark)

    Jensen, Erik Steen; SØrensen, Lasse Holst

    1986-01-01

    A wild pea (Pisum sativum L.) native to Afghanistan normally known to be resisant to nodulation with European strains of Rhizobium leguminosarum was nodulated early and effectively in field soil in Denmark. Isolates from nodules formed effective nodules abundantly on 'Afghanistan' on reinfection under aseptic conditions. Five types differing in isoenzyme composition pattern were found among 15 isolates from 'Afghanistan' nodules. None were identical with 'Tom' strain from Turkey, which also forms effective nodules with 'Afghanistan'. The five types were also different with respect to isoenzyme pattern with Rhizobium leguminosarum strains isolated from a modern pea variety cultivated in the same field.

  20. Fast induction of biosynthetic polysaccharide genes lpxA, lpxE, and rkpI of Rhizobium sp. strain PRF 81 by common bean seed exudates is indicative of a key role in symbiosis.

    Science.gov (United States)

    Oliveira, Luciana Ruano; Rodrigues, Elisete Pains; Marcelino-Guimarães, Francismar Corrêa; Oliveira, André Luiz Martinez; Hungria, Mariangela

    2013-06-01

    Rhizobial surface polysaccharides (SPS) are, together with nodulation (Nod) factors, recognized as key molecules for establishment of rhizobia-legume symbiosis. In Rhizobium tropici, an important nitrogen-fixing symbiont of common bean (Phaseolus vulgaris L.), molecular structures and symbiotic roles of the SPS are poorly understood. In this study, Rhizobium sp. strain PRF 81 genes, belonging to the R. tropici group, were investigated: lpxA and lpxE, involved in biosynthesis and modification of the lipid-A anchor of lipopolysaccharide (LPS), and rkpI, involved in synthesis of a lipid carrier required for production of capsular polysaccharides (KPS). Reverse transcription quantitative PCR (RT-qPCR) analysis revealed, for the first time, that inducers released from common bean seeds strongly stimulated expression of all three SPS genes. When PRF 81 cells were grown for 48 h in the presence of seed exudates, twofold increases (p Rhizobium radiobacter and were more related to R. etli and Rhizobium leguminosarum, while rkpI was closer to the Sinorhizobium sp. group. Upregulation of lpxE, lpxA, and rkpI genes suggests that seed exudates can modulate production of SPS of Rhizobium sp. PRF81, leading to cell wall changes necessary for symbiosis establishment. PMID:23652766

  1. Rhizobium sophorae sp. nov. and Rhizobium sophoriradicis sp. nov., nitrogen-fixing rhizobial symbionts of the medicinal legume Sophora flavescens.

    Science.gov (United States)

    Jiao, Yin Shan; Yan, Hui; Ji, Zhao Jun; Liu, Yuan Hui; Sui, Xin Hua; Wang, En Tao; Guo, Bao Lin; Chen, Wen Xin; Chen, Wen Feng

    2015-02-01

    Five bacterial strains representing 45 isolates originated from root nodules of the medicinal legume Sophora flavescens were defined as two novel groups in the genus Rhizobium based on their phylogenetic relationships estimated from 16S rRNA genes and the housekeeping genes recA, glnII and atpD. These groups were distantly related to Rhizobium leguminosarum USDA 2370(T) (95.6?% similarity for group I) and Rhizobium phaseoli ATCC 14482(T) (93.4?% similarity for group II) in multilocus sequence analysis. In DNA-DNA hybridization experiments, the reference strains CCBAU 03386(T) (group I) and CCBAU 03470(T) (group II) showed levels of relatedness of 17.9-57.8 and 11.0-42.9?%, respectively, with the type strains of related species. Both strains CCBAU 03386(T) and CCBAU 03470(T) contained ubiquinone 10 (Q-10) as the major respiratory quinone and possessed 16?:?0, 18?:?0, 19?:?0 cyclo ?8c, summed feature 8 and summed feature 2 as major fatty acids, but did not contain 20?:?3 ?6,8,12c. Phenotypic features distinguishing both groups from all closely related species of the genus Rhizobium were found. Therefore, two novel species, Rhizobium sophorae sp. nov. for group I (type strain CCBAU 03386(T)?=?E5(T)?=?LMG 27901(T)?=?HAMBI 3615(T)) and Rhizobium sophoriradicis sp. nov. for group II (type strain CCBAU 03470(T)?=?C-5-1(T)?=?LMG 27898(T)?=?HAMBI 3510(T)), are proposed. Both groups were able to nodulate Phaseolus vulgaris and their hosts of origin (Sophora flavescens) effectively and their nodulation gene nodC was phylogenetically located in the symbiovar phaseoli. PMID:25385989

  2. Reseña del libro : Huyse, P. (2003). "Le y final dans les inscriptions moyen-perses et la loi rythmique proto-moyen-perse"

    OpenAIRE

    Cantera Glera, Alberto

    2006-01-01

    El autor hace una reseña del libro de : Huyse, P. (2003). "Le y final dans les inscriptions moyen-perses et la loi rythmique proto-moyen-perse". Paris : Association pour l'avancement des études iraniennes.

  3. Draft Genome Sequence of Rhizobium rhizogenes Strain ATCC 15834

    OpenAIRE

    Kajala, Kaisa; Coil, David A.; Brady, Siobhan M.

    2014-01-01

    Here, we present the draft genome of Rhizobium rhizogenes strain ATCC 15834. The genome contains 7,070,307 bp in 43 scaffolds. R. rhizogenes, also known as Agrobacterium rhizogenes, is a plant pathogen that causes hairy root disease. This hairy root induction has been used in biotechnology for the generation of transgenic root cultures.

  4. Draft Genome Sequence of Rhizobium rhizogenes Strain ATCC 15834.

    Science.gov (United States)

    Kajala, Kaisa; Coil, David A; Brady, Siobhan M

    2014-01-01

    Here, we present the draft genome of Rhizobium rhizogenes strain ATCC 15834. The genome contains 7,070,307 bp in 43 scaffolds. R. rhizogenes, also known as Agrobacterium rhizogenes, is a plant pathogen that causes hairy root disease. This hairy root induction has been used in biotechnology for the generation of transgenic root cultures. PMID:25359916

  5. [Studies on allelopathic effect of artemisinin on rhizobium].

    Science.gov (United States)

    Li, Qian; Wu, Yekuan; Huang, Jianguo

    2011-12-01

    Two strains of bean rhizobia, Rhizobium vigna 01 (slow-growing Rhizobium) and Rh. vigna 03 (fast-growing Rhizobium), were adopted to study allelopathic effect of artemisinin on the rhizobia. The results showed a significant inhibition of the reproduction and growth of rhizobium by artemisinin. After about 8 hours by adding 40 mg x L(-1) artemisinin into the culture medium, the number of rhizobia was less than half of those in normal culture. The utilization of sucrose and glucose by rhizobia decreased significantly as the concentration of artemisinin increased in the culture medium, which could be one of the main reasons for the inhibition of reproduction and growth of rhizobia by artemisinin. In addition, the activities of extracellular protease and acid phosphatase released from rhizobia decreased significantly as the concentrations of artemisinin increased. Artemisinin refluxed from Artemisia annua could thus inhibit the formation of root nodules and interfered with energy supply and reception between bacteroid and host cells. y = e(-ax) + b reflected the relationships between nitrogenase activities (y) and concentrations of artemisinin (x). In the culture medium with 48 mg x L(-1) of artemisinin, nitrogenase activities were about zero, resulting in the inactivation of nitrogenase in nodules formed. In general, artemisin in A. annua grown soils may inhibit the reproduction and growth of rhizobia, nodule formation and nitrogen biofixation, leading to less nitrogen supply, poor growth and development, and low yields of beans. PMID:22368850

  6. Draft Genome Sequence of Rhizobium rhizogenes Strain ATCC 15834

    Science.gov (United States)

    Kajala, Kaisa; Coil, David A.

    2014-01-01

    Here, we present the draft genome of Rhizobium rhizogenes strain ATCC 15834. The genome contains 7,070,307 bp in 43 scaffolds. R. rhizogenes, also known as Agrobacterium rhizogenes, is a plant pathogen that causes hairy root disease. This hairy root induction has been used in biotechnology for the generation of transgenic root cultures. PMID:25359916

  7. Rhizobium lemnae sp. nov., a bacterial endophyte of Lemna aequinoctialis.

    Science.gov (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2014-07-01

    Bacterial strain L6-16(T) was isolated from Lemna aequinoctialis. Cells were Gram-stain-negative, rod-shaped and motile with monopolar flagella. The phylogenetic analysis of its nearly complete 16S rRNA gene sequence revealed that strain L6-16(T) was a member of the genus Rhizobium. Its closest relative was Rhizobium tarimense PL-41(T) with a 16S rRNA gene sequence similarity value of 98.3%. Sequence similarity analysis of the housekeeping recA and atpD genes showed low levels of sequence similarity (nodC and nifH genes were not detected. The results obtained from phylogenetic analyses, phenotypic characterization and DNA-DNA hybridization indicated that strain L6-16(T) represents a novel species of the genus Rhizobium, for which the name Rhizobium lemnae sp. nov. is proposed. The type strain is L6-16(T) (?= NBRC 109339(T)?= BCC 55143(T)). PMID:24786354

  8. Diversity of Rhizobium leguminosarum from pea fields in Washington State

    Science.gov (United States)

    Rhizobia-mediated biological nitrogen (N) fixation in legumes contributes to yield potential in these crops and also provides residual fertilizer to subsequent cereals. Our objectives were to collect isolates of Rhizobium leguminosarum from several pea fields in Washington, examine genetic diversity...

  9. Genetic diversity of Rhizobium from nodulating beans grown in a variety of Mediterranean climate soils of Chile.

    Science.gov (United States)

    Baginsky, Cecilia; Brito, Belén; Scherson, Rosita; Pertuzé, Ricardo; Seguel, Oscar; Cañete, Alejandro; Araneda, Cristian; Johnson, Warren E

    2015-04-01

    In spite of potentially being an important source of rhizobial diversity and a key determinant of common bean productivity, there is a paucity of data on Rhizobium genetic variation and species composition in the important bean producing area of Chile and only one species has been documented (Rhizobium leguminosarum). In this study, 240 Rhizobium isolates from Torcaza bean (Phaseolus vulgaris L.) nodules established in the highest bean producing area in Chile (33°34'S-70°38'W and 37°36'S-71°47'W) were characterized by PCR-RFLP markers for nodC gene, revealing eight banding patterns with the polymorphic enzyme Hinf I. The locality of San Agustín de Aurora in Central Chile (35°32'S-71°29'W) had the highest level of diversity. Isolates were classified by species using PCR-RFLP markers for 16S rDNA gene and were confirmed by sequencing an internal fragment of the 16S rDNA gene. The results confirmed the presence of R. leguminosarum and three other species of rhizobia nodulating beans in South Central Chile (R. etli, R. tropici and R. leucaenae). R. tropici and R. leucaenae showed the least genetic variation and were most commonly identified in acid soils, while R. etli was the most common species in slightly acidic to moderately alkaline soils, with higher levels of organic matter content. R. leguminosarum was identified in almost all soils, was the most genetically diverse, and was the most common, being documented in soils with pH that ranged between 5.3 and 8.2, and with organic matter content between 2.1 and 4 %. PMID:25533847

  10. [A structural assessment of the role of the cell surface carbohydrates of Rhizobium in the Rhizobium/legume symbiosis]. Progress report, June 1989--June 1991

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, R.I.

    1991-12-31

    Research continued on the study of cell surface carbohydrates of Rhizobium. Objectives include: To characterize, at a structural level, the differences between the lipopolysaccharides of a representative number of strains from different Rhizobium species to determine which features of LPS structure are species-specific and might, therefore, be determinants of host specificity. Determine the effect(s) of nod gene induction on the structure of Rhizobium lipopolysaccharides and determine whether synthesis of a modified LPS molecule or a new surface glycoconjugate is initiated by nod gene induction. Develop a non-chemical means for rapidly screening large numbers of bacterial strains in order to determine which glycoconjugate structural features are conserved between strains of the same species. Provide the necessary structural information which, when coupled with developments in the rapidly expanding field of Rhizobium genetics, should lead to a clear understanding of the role of Rhizobium surface glycoconjugates in host/symbiont interactions. Progress is discussed.

  11. The Effect of Rhizobium spp. Inoculation on Seed Quality of Bean in Turkey

    OpenAIRE

    Cigdem KuCuk; Merih KivanC

    2008-01-01

    Rhizobium spp. (local isolate) was used to inoculate three bean (Phaseolus vulgaris L.) varieties; Akman 98, Goynuk 98 and Sehirali 90, in a factorial field experiment. The objective of the experiment was to study effect of inoculation on seed yield, protein range, seed weight, non-soaker capacity and hydration index. Rhizobium spp. inoculation and nitrogen fertilizer significantly increased characters tested. This study revealed that inoculation with Rhizobium spp. improved seed quality.

  12. Interaction of Azospirillum and Rhizobium Strains Leading to Inhibition of Nodulation

    OpenAIRE

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

    Rhizobium-Azospirillum interactions during establishment of Rhizobium-clover symbiosis were studied. When mixed cultures of Azospirillum and Rhizobium trifolii strains were simultaneously inoculated onto clover plants, no nodulation by R. trifolii was observed. R. trifolii ANU1030, which nodulated clover plants without attacking root hairs, i.e., does not cause root hair curling (Hac?), did not show inhibition of nodulation when inoculated together with Azospirillum strains. Isolation of ba...

  13. The effect of exogenous rhizobial lipopolysaccharide on symbiosis of Rhizobium leguminosarum bv. trifolii with red clover

    Directory of Open Access Journals (Sweden)

    Maria G?owacka

    1996-12-01

    Full Text Available The effectivity of symbiosis of Rhizobium leguminosarum bv. trifolii with red clover in the presence of exogenous lipopolysaccharide (LPS preparation was measured as a yield of green mass of infected plants. The addition of complete LPS that had been obtained from homological Rhizobium strains influenced significantly the growth of plants. In the presence of defective LPS of Rhizobium mutant the effectivity of symbiosis did not change.

  14. The effect of exogenous rhizobial lipopolysaccharide on symbiosis of Rhizobium leguminosarum bv. trifolii with red clover

    OpenAIRE

    Maria G?owacka; Agnieszka St?pie?; Sylwia Szyprowska

    1996-01-01

    The effectivity of symbiosis of Rhizobium leguminosarum bv. trifolii with red clover in the presence of exogenous lipopolysaccharide (LPS) preparation was measured as a yield of green mass of infected plants. The addition of complete LPS that had been obtained from homological Rhizobium strains influenced significantly the growth of plants. In the presence of defective LPS of Rhizobium mutant the effectivity of symbiosis did not change.

  15. The Effect of Rhizobium spp. Inoculation on Seed Quality of Bean in Turkey

    Directory of Open Access Journals (Sweden)

    Cigdem KuCuk

    2008-01-01

    Full Text Available Rhizobium spp. (local isolate was used to inoculate three bean (Phaseolus vulgaris L. varieties; Akman 98, Goynuk 98 and Sehirali 90, in a factorial field experiment. The objective of the experiment was to study effect of inoculation on seed yield, protein range, seed weight, non-soaker capacity and hydration index. Rhizobium spp. inoculation and nitrogen fertilizer significantly increased characters tested. This study revealed that inoculation with Rhizobium spp. improved seed quality.

  16. Regulation of phenolic catabolism in Rhizobium leguminosarum biovar trifolii

    Energy Technology Data Exchange (ETDEWEB)

    Parke, D. (Yale Univ., New Haven, CT (United States)); Rynne, F.; Glenn, A. (Murdoch Univ. (Australia))

    1991-09-01

    In members of the family Rhizobiaceae, many phenolic compounds are degraded by the protocatechuate branch of the {beta}-ketoadipate pathway, In this paper the authors describe a novel pattern of induction of protocatechuate (pca) genes in Rhizobium leguminosarum biovar trifolii. Isolation of pca mutant strains revealed that 4-hydroxybenzoate, quinate, and 4-coumarate are degraded via the protocatechuate pathway. At least three inducers govern catabolism of 4-hydroxybenzoate to succinyl coenzyme A and acetyl coenzyme A. The enzyme that catalyzes the initial step is induced by its substrate, whereas the catabolite {beta}-carboxy-cis, cis-muconate induces enzymes for the upper protocatechuate pathway, and {beta}-ketoadipate elicits expression of the enzyme for a subsequent step, {beta}-ketoadipate succinyl-coenzyme A transferase. Elucidation of the induction pattern relied in part on complementation of mutant Rhizobium strains by known subclones of Acinetobacter genes expressed off the lac promoter in a broad-host-range vector.

  17. Organization and expression of Rhizobium meliloti nitrogen fixation genes

    OpenAIRE

    Corbin, David; Barran, Leslie; Ditta, Gary

    1983-01-01

    The boundaries of a nif gene cluster in Rhizobium meliloti were determined by Tn5 mutagenesis. These genes are clustered within a 14- to 15-kilobase (kb) region that includes the nitrogenase structural genes. Sequences within 10 kb on either side of this region are devoid of symbiotically essential gene function. RNA blot analysis identified a 5- to 6-kb transcript that corresponds to the nitrogenase structural gene operon. The 5? end of this transcript and its polarity were determined by n...

  18. Nitrogenase reductase: A functional multigene family in Rhizobium phaseoli

    OpenAIRE

    Quinto, Carmen; La Vega, Humberto; Flores, Margarita; Leemans, Jan; Cevallos, Miguel Angel; Pardo, Marco Aurelio; Azpiroz, Ricardo; Lourdes Girard, Maria; Calva, Edmundo; Palacios, Rafael

    1985-01-01

    The complete coding sequence of the nitrogenase reductase gene (nifH) is present in three different regions of a Rhizobium phaseoli symbiotic plasmid. Homology between two of the regions containing nifH coding sequences extends over 5 kilobases. These in turn share 1.3 kilobases of homology with the third region. The nucleotide sequences of the three nitrogenase reductase genes were found to be identical. Site-directed insertion mutagenesis indicated that none of the three genes is indispensa...

  19. Dechlorination of Atrazine by a Rhizobium sp. Isolate

    OpenAIRE

    Bouquard, C.; Ouazzani, J.; Prome, J.; Michel-briand, Y.; Plesiat, P.

    1997-01-01

    A Rhizobium sp. strain, named PATR, was isolated from an agricultural soil and found to actively degrade the herbicide atrazine. Incubation of PATR in a basal liquid medium containing 30 mg of atrazine liter(sup-1) resulted in the rapid consumption of the herbicide and the accumulation of hydroxyatrazine as the only metabolite detected after 8 days of culture. Experiments performed with ring-labeled [(sup14)C]atrazine indicated no mineralization. The enzyme responsible for the hydroxylation o...

  20. Interstrain Competition between Representatives of Indigenous Serotypes of Rhizobium trifolii†

    OpenAIRE

    Demezas, David H.; Bottomley, Peter J.

    1986-01-01

    The symbiotic characteristics of Rhizobium trifolii strains 1-01 and 2-01 were evaluated both individually and in various combinations on two cultivars (Mt. Barker and Woogenellup) of subterranean clover (Trifolium subterraneum L.). Nodules were observed on day 8 independent of cultivar or strain. Cultivar differences were measured in nodulating efficiency by 1-01 since 54% of the primary nodules were formed on cv. Mt. Barker and only 15% were formed on cv. Woogenellup in the zone above, or 1...

  1. Host sanctions and the legume-rhizobium mutualism.

    OpenAIRE

    Kiers, Et; Rousseau, Ra; West, Sa; Denison, Rf

    2003-01-01

    Explaining mutualistic cooperation between species remains one of the greatest problems for evolutionary biology. Why do symbionts provide costly services to a host, indirectly benefiting competitors sharing the same individual host? Host monitoring of symbiont performance and the imposition of sanctions on 'cheats' could stabilize mutualism. Here we show that soybeans penalize rhizobia that fail to fix N(2) inside their root nodules. We prevented a normally mutualistic rhizobium strain from ...

  2. Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes

    OpenAIRE

    Engvild, Kjeld Christensen; Nielsen, G.

    2011-01-01

    Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and arabinose and other sugars as enzyme inducers. After electrophoresis the gels were separated into several slabs by a gel cutter. Each slab was stained for a particular enzyme. Among numerous ...

  3. Genetic transformation of Rhizobium leguminosarum by plasmid DNA.

    OpenAIRE

    Bullerjahn, G. S.; Benzinger, R. H.

    1982-01-01

    We demonstrated the genetic transformation of Rhizobium leguminosarum by R68.45 plasmid DNA by freezing and thawing cell suspensions in the presence of R68.45 plasmid DNA and 20 mM MgCl2. Clones resistant to kanamycin and tetracycline were recovered at a frequency of 10(-8) per recipient cell. No colonies that were doubly drug resistant were recovered in parallel control experiments.

  4. High-frequency rearrangements in Rhizobium leguminosarum bv. phaseoli plasmids.

    OpenAIRE

    Brom, S.; Garci?a Los Santos, A.; Lourdes Girard, M.; Da?vila, G.; Palacios, R.; Romero, D.

    1991-01-01

    High-frequency genomic rearrangements affecting the plasmids of Rhizobium leguminosarum bv. phaseoli CFN42 were analyzed. This strain contains six large plasmids ranging in size from 200 to 600 kb. In the absence of any selective pressure, we found 11 strains from 320 analyzed colonies that presented different kinds of plasmid-borne rearrangements, including sequence amplification, deletion, cointegration, and loss of plasmids. These data support the concept that the R. leguminosarum bv. phas...

  5. Genetic structure of a soil population of nonsymbiotic Rhizobium leguminosarum.

    OpenAIRE

    Segovia, L.; Pin?ero, D.; Palacios, R.; Marti?nez-romero, E.

    1991-01-01

    The genetic structure of a population of nonsymbiotic Rhizobium leguminosarum strains was determined by the electrophoretic mobilities of eight metabolic enzymes. Nonsymbiotic strains were isolated from the rhizosphere of bean plants and characterized by growth on differential media and at different temperatures, intrinsic antibiotic resistance, the lack of homology to a nifH probe, and their inability to form nodules on bean roots. All the isolates clustered with R. leguminosarum bv. phaseol...

  6. Evaluation of Nitrate Reductase Activity in Rhizobium japonicum†

    OpenAIRE

    Streeter, John G.; Devine, Paul J.

    1983-01-01

    Nitrate reductase activity was evaluated by four approaches, using four strains of Rhizobium japonicum and 11 chlorate-resistant mutants of the four strains. It was concluded that in vitro assays with bacteria or bacteroids provide the most simple and reliable assessment of the presence or absence of nitrate reductase. Nitrite reductase activity with methyl viologen and dithionite was found, but the enzyme activity does not confound the assay of nitrate reductase.

  7. Nitrogen fixation (nif) genes and large plasmids of Rhizobium japonicum.

    OpenAIRE

    Masterson, R. V.; Russell, P. R.; Atherly, A. G.

    1982-01-01

    The location of structural nitrogen-fixation genes was determined for the slow- and fast-growing types of Rhizobium japonicum. Slow-growing R. japonicum strains do not harbor structural nif genes, homologous to nifD and nifH, on large plasmids (100 to 200 megadaltons). In contrast, all fast-growing R. japonicum strains, except PRC194, contain structural nif genes on large plasmids.

  8. Rhizobium pongamiae sp. nov. from root nodules of Pongamia pinnata.

    Science.gov (United States)

    Kesari, Vigya; Ramesh, Aadi Moolam; Rangan, Latha

    2013-01-01

    Pongamia pinnata has an added advantage of N2-fixing ability and tolerance to stress conditions as compared with other biodiesel crops. It harbours "rhizobia" as an endophytic bacterial community on its root nodules. A gram-negative, nonmotile, fast-growing, rod-shaped, bacterial strain VKLR-01(T) was isolated from root nodules of Pongamia that grew optimal at 28°C, pH 7.0 in presence of 2% NaCl. Isolate VKLR-01 exhibits higher tolerance to the prevailing adverse conditions, for example, salt stress, elevated temperatures and alkalinity. Strain VKLR-01(T) has the major cellular fatty acid as C(18:1) ?7c (65.92%). Strain VKLR-01(T) was found to be a nitrogen fixer using the acetylene reduction assay and PCR detection of a nifH gene. On the basis of phenotypic, phylogenetic distinctiveness and molecular data (16S rRNA, recA, and atpD gene sequences, G + C content, DNA-DNA hybridization etc.), strain VKLR-01(T) = (MTCC 10513(T) = MSCL 1015(T)) is considered to represent a novel species of the genus Rhizobium for which the name Rhizobium pongamiae sp. nov. is proposed. Rhizobium pongamiae may possess specific traits that can be transferred to other rhizobia through biotechnological tools and can be directly used as inoculants for reclamation of wasteland; hence, they are very important from both economic and environmental prospects. PMID:24078904

  9. 78 FR 33437 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment

    Science.gov (United States)

    2013-06-04

    ...Antitrust Division United States v. Apple, Inc., et al.; Public Comments and...a Macmillan in United States v. Apple, Inc., et al., Civil Action No...STATES OF AMERICA, Plaintiff, v. APPLE, INC., et al., Defendants....

  10. Gene amplification in Rhizobium: identification and in vivo cloning of discrete amplifiable DNA regions (amplicons) from Rhizobium leguminosarum biovar phaseoli.

    OpenAIRE

    Flores, M.; Brom, S.; Stepkowski, T.; Girard, M. L.; Da?vila, G.; Romero, D.; Palacios, R.

    1993-01-01

    A genetic element that allows the positive selection of different genomic rearrangements was used to analyze DNA amplification in Rhizobium leguminosarum biovar phaseoli. Discrete amplifiable DNA regions (amplicons) were detected in different regions of the genome of the model strain CFN42, including the chromosome and several large plasmids. Amplicons were mobilized into Escherichia coli using a genetic approach that involves the introduction of an origin of replication active in E. coli and...

  11. Mobilization of a Sym plasmid from a fast-growing cowpea Rhizobium strain.

    OpenAIRE

    Morrison, N. A.; Cen, Y. H.; Chen, H. C.; Plazinski, J.; Ridge, R.; Rolfe, B. G.

    1984-01-01

    A large Sym plasmid from a fast-growing cowpea Rhizobium species was made mobilizable by cointegration with plasmid pSUP1011, which carries the oriT region of RP4. This mobilizable Sym plasmid was transferred to a number of Rhizobium strains, in which nodulation and nitrogen fixation functions for symbiosis with plants of the cowpea group were expressed.

  12. In Rhizobium japonicum the nitrogenase genes nifH and nifDK are separated.

    OpenAIRE

    Kaluza, K.; Fuhrmann, M.; Hahn, M.; Regensburger, B.; Hennecke, H.

    1983-01-01

    In contrast to Klebsiella pneumoniae or fast-growing Rhizobium species, such as R. meliloti, where the nitrogenase structural genes are clustered in one operon (nifHDK), in slow-growing Rhizobium japonicum 110, nifH and nifDK are on separate operons.

  13. Effects of nano-TiO2 on the agronomically-relevant Rhizobium-legume symbiosis

    Science.gov (United States)

    The impact of nano-TiO2 on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO2 did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-...

  14. Rhizobium pisi sv. trifolii K3.22 harboring nod genes of the Rhizobium leguminosarum sv. trifolii cluster.

    Science.gov (United States)

    Marek-Kozaczuk, Monika; Leszcz, Agnieszka; Wielbo, Jerzy; Wdowiak-Wróbel, Sylwia; Skorupska, Anna

    2013-06-01

    The taxonomic status of the Rhizobium sp. K3.22 clover nodule isolate was studied by multilocus sequence analysis (MLSA) of 16S rRNA and six housekeeping chromosomal genes, as well as by a subsequent phylogenic analysis. The results revealed full congruence with the Rhizobium pisi DSM 30132(T) core genes, thus supporting the same taxonomic position for both strains. However, the K3.22 plasmid symbiosis nod genes demonstrated high sequence similarity to Rhizobium leguminosarum sv. trifolii, whereas the R. pisi DSM 30132(T)nod genes were most similar to R. leguminosarum sv. viciae. The strains differed in the host range nodulation specificity, since strain K3.22 effectively nodulated red and white clover but not vetch, in contrast to R. pisi DSM 30132(T), which effectively nodulated vetch but was not able to nodulate clover. Both strains had the ability to form nodules on pea and bean but they differed in bean cultivar specificity. The R. pisi K3.22 and DSM 30132(T) strains might provide evidence for the transfer of R. leguminosarum sv. trifolii and sv. viciae symbiotic plasmids occurring in natural soil populations. PMID:23507586

  15. Sobrevivência e nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas / Survival and nodulation of Rhizobium tropici on common bean seeds treated with fungicides

    Scientific Electronic Library Online (English)

    Ademir Sérgio Ferreira de, Araújo; Ricardo Silva, Araújo.

    2006-06-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar a sobrevivência e a capacidade de nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas. O estudo foi realizado em laboratório e em casa de vegetação. Sementes de feijão (Phaseolus vulgaris) foram tratadas com seis diferentes fungicidas e [...] inoculadas com Rhizobium tropici estirpe CIAT 899. A sobrevivência do Rhizobium nas sementes foi avaliada no tempo 0 e 24 horas após o tratamento com fungicidas e a inoculação, utilizando o método do número mais provável (NMP). A nodulação do feijão, em plantio realizado no tempo 0 e 24 horas após o tratamento com fungicidas, e a inoculação foram avaliadas em solo com população estabelecida de Rhizobium nativo aos trinta dias após a emergência das plantas. A sobrevivência do Rhizobium inoculado nas sementes foi prejudicada pela aplicação dos fungicidas avaliados. A nodulação do feijoeiro foi reduzida pela aplicação dos fungicidas, quando o plantio foi realizado 24 horas após o tratamento das sementes. Entretanto, foram encontrados nódulos em todos os tratamentos, evidenciando que houve nodulação do Rhizobium nativo do solo. Abstract in english The aim of this work was to evaluate the survival and nodulation of Rhizobium tropici on common bean seeds treated with fungicides. The study was conduced out at laboratory and greenhouse conditions. Common bean (Phaseolus vulgaris) seeds were treated with six fungicides and inoculated with Rhizobiu [...] m tropici strain CIAT 899. The survival of Rhizobium on seeds was evaluated 0 and 24 hours after treatment with fungicides and inoculation, using the most probable number (MPN) method. The nodulation of common bean thirty days after plant emergence, in plantation conduced 0 and 24 hours after seeds treatment with fungicides and inoculation, was evaluated in soil with population of native Rhizobium. The fungicides harmed the survival of inoculated Rhizobium on seeds and, in plantation conduced 24 hours after seeds treatment, reduced the nodulation of common bean. However, nodules were found in all plants, suggesting nodulation by native Rhizobium of soil.

  16. Rhizobium meliloti nodulation genes: identification of nodDABC gene products, purification of nodA protein, and expression of nodA in Rhizobium meliloti.

    OpenAIRE

    Egelhoff, T. T.; Long, S. R.

    1985-01-01

    A set of conserved, or common, bacterial nodulation (nod) loci is required for host plant infection by Rhizobium meliloti and other Rhizobium species. Four such genes, nodDABC, have been indicated in R. meliloti 1021 by genetic analysis and DNA sequencing. An essential step toward understanding the function of these genes is to characterize their protein products. We used in vitro and maxicell Escherichia coli expression systems, together with gel electrophoresis and autoradiography, to detec...

  17. Split-Root Assays Using Trifolium subterraneum Show that Rhizobium Infection Induces a Systemic Response That Can Inhibit Nodulation of Another Invasive Rhizobium Strain

    OpenAIRE

    Sargent, Lucy; Huang, Shizhen Z.; Rolfe, Barry G.; Djordjevic, Michael A.

    1987-01-01

    Subterranean clover plants possessing two equally infectible and robust lateral root systems (“split roots”) were used in conjunction with several specific mutant strains (derived from Rhizobium trifolii ANU843) to investigate a systemic plant response induced by infective Rhizobium strains. This plant response controls and inhibits subsequent nodulation on the plant. When strain ANU843 was inoculated onto both root systems simultaneously or 24, 48, 72, or 96 h apart, an inhibitory respon...

  18. Transformation of Rhizobium meliloti 41 with plasmid DNA.

    OpenAIRE

    Kiss, G. B.; Ka?lma?n, Z.

    1982-01-01

    Plasmid pGV1106, a derivative of the wide-host-range plasmid S-a of the W incompatibility group, was introduced into Rhizobium meliloti 41 by plasmid-mediated mobilization to overcome the restriction of foreign DNA. The mobilized plasmid pKK2 differed from the original pGV1106 by an extra piece of DNA of 1.3 kilobase pairs which supposedly originated from pJB3JI used for mobilization. If pKK2 was isolated from R. meliloti 41, it could be successfully reintroduced by transformation. The transf...

  19. Mechanism of regulation of glucose transport in Rhizobium leguminosarum.

    OpenAIRE

    Vries, G. E.; Brussel, A. A.; Quispel, A.

    1982-01-01

    Multiple glucose transport systems were distinguished in Rhizobium leguminosarum. We found nonlinear Lineweaver-Burk plots for the uptake of glucose, 2-deoxy-D-glucose, and alpha-methyl-D-glucoside, and this implied the existence of at least two uptake mechanisms. Different patterns of inhibition of 2-deoxy-D-glucose uptake and alpha-methyl-D-glucoside uptake at 0.1 mM by various carbohydrates revealed differences in the stereospecificities of the transport systems. Osmotic shock treatment ab...

  20. Relations between Rhizobium and radiostimulation treatments of seeds

    International Nuclear Information System (INIS)

    In field experiments the effects of irradiation with 60Co isotope the seeds of round seeded peas (Pisum sativum L.), beans (Phaseolus vulgaris L.), soybeans (Glycine max. L./Merr.) and lucerne (Medicago sativa) were investigated. Rhizobium bacteria inoculation was carried out with the inoculator ''Rhizonit''. The green mass yield was determined for lucerne and the grain yield for the other plants. Irradiation induced flowering of peas 4-5 days earlier. The bean yields increased significantly on the influence of 1000 rad irradiation plus Rhizonit inoculation. For soybeans the yield response to Rhizonit proved to be significant. (author)

  1. Enhanced Symbiotic Performance by Rhizobium tropici Glycogen Synthase Mutants

    OpenAIRE

    Marroqui?, Silvia; Zorreguieta, Angeles; Santamari?a, Carmen; Temprano, Francisco; Sobero?n, Mario; Megi?as, Manuel; Downie, J. Allan

    2001-01-01

    We isolated a Tn5-induced Rhizobium tropici mutant that has enhanced capacity to oxidize N,N-dimethyl-p-phenylendiamine (DMPD) and therefore has enhanced respiration via cytochrome oxidase. The mutant had increased levels of the cytochromes c1 and CycM and a small increase in the amount of cytochrome aa3. In plant tests, the mutant increased the dry weight of Phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. The...

  2. Cloning and mutagenesis of the Rhizobium meliloti isocitrate dehydrogenase gene.

    OpenAIRE

    Mcdermott, T. R.; Kahn, M. L.

    1992-01-01

    The gene encoding Rhizobium meliloti isocitrate dehydrogenase (ICD) was cloned by complementation of an Escherichia coli icd mutant with an R. meliloti genomic library constructed in pUC18. The complementing DNA was located on a 4.4-kb BamHI fragment. It encoded an ICD that had the same mobility as R. meliloti ICD in nondenaturing polyacrylamide gels. In Western immunoblot analysis, antibodies raised against this protein reacted with R. meliloti ICD but not with E. coli ICD. The complementing...

  3. Genetic structure of natural populations of the nitrogen-fixing bacterium Rhizobium meliloti.

    Science.gov (United States)

    Eardly, B D; Materon, L A; Smith, N H; Johnson, D A; Rumbaugh, M D; Selander, R K

    1990-01-01

    The genetic structure of populations of the symbiotic nitrogen-fixing soil bacterium Rhizobium meliloti was examined by analysis of electrophoretically demonstrable allelic variation in 14 metabolic, presumably chromosomal, enzyme genes. A total of 232 strains were examined, most of which were isolated from southwest Asia, where there is an unsurpassed number of indigenous host species for R. meliloti. The collection consisted of 115 isolates recovered from annual species of Medicago in Syria, Turkey, and Jordan; 85 isolates cultured from two perennial species of Medicago (M. sativa [alfalfa] and M. falcata) in northern Pakistan and Nepal; and 32 isolates collected at various localities in North and South America, Europe, South Africa, New Zealand, and Australia, largely from M. sativa. Fifty distinctive multilocus genotypes (electrophoretic types [ETs]) were identified, and cluster analysis revealed two primary phylogenetic divisions separated at a genetic distance of 0.83. By the criterion of genetic differentiation conventionally applied in defining species limits among members of the family Enterobacteriaceae and certain other bacteria, the two primary divisions of R. meliloti represent distinct evolutionary species. Division A included 35 ETs represented by 209 strains from the eastern Mediterranean basin, northern Pakistan, Nepal, and various other localities worldwide. This division contained the nine commercial alfalfa inoculant strains examined. Division B included 15 ETs represented by 23 isolates, 21 of which were isolated from annual medic species growing in previously uninoculated soils in the eastern Mediterranean basin. The two remaining strains in division B, both representing the same ET, were isolated in the United States and Australia.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1689982

  4. Rhizobium pakistanensis sp. nov., isolated from groundnut (Arachis hypogaea) nodules grown in rainfed Pothwar, Pakistan.

    Science.gov (United States)

    Khalid, Rabia; Zhang, Yu Jing; Ali, Safdar; Sui, Xin Hua; Zhang, Xiao Xia; Amara, Ummay; Chen, Wen Xin; Hayat, Rifat

    2015-01-01

    A Gram-negative, white, non-motile, rod shaped bacterial strain BN-19(T) was isolated from a root nodule of groundnut (Arachis hypogaea) in Pakistan. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain BN-19(T) formed a subclade in the genus Rhizobium together with Rhizobium alkalisoli CCBAU 01393(T), Rhizobium vignae CCBAU 05176(T), Rhizobium huautlense SO2(T) and Rhizobium tarimense PL-41(T) with sequence similarities of 97.5, 97.3, 97.2 and 97.1 % respectively. Sequence analysis of housekeeping genes atpD, glnII and recA (with sequence similarities of ?92 %) confirmed the unique position of BN-19(T) in the genus Rhizobium. DNA-DNA relatedness between the strain BN-19(T) and R. alkalisoli CCBAU 01393(T), R. vignae CCBAU 05176(T), R. huautlense SO2(T) and R. tarimense PL-41(T) were 20.6, 22.5, 15.9 and 20.5 % respectively, further confirming that BN-19(T) represents a novel species in the genus Rhizobium. The DNA G + C content was 60.1 mol%. The dominant fatty acids of strain BN-19(T) were C19:0 cyclo ?8c, summed feature 2 (C14:0 3OH and/or C16:1 iso I) and summed feature 8 (C18:1 ?7c). Some phenotypic features also differentiate the strain BN-19(T) from the related species. On the basis of these results, strain BN-19(T) is considered to represent a novel species in the genus Rhizobium, for which the name Rhizobium pakistanensis sp. nov. is proposed. The type strain is BN-19(T) (=LMG 27895(T) = CCBAU 101086(T)). PMID:25391352

  5. Transposon mediation allows a symbiotic plasmid of Rhizobium leguminosarum bv. trifolii to become a symbiosis island in Agrobacterium and Rhizobium.

    Science.gov (United States)

    Nakatsukasa, Hiroki; Uchiumi, Toshiki; Kucho, Ken-Ichi; Suzuki, Akihiro; Higashi, Shiro; Abe, Mikiko

    2008-04-01

    The symbiotic plasmid (pSym) of Rhizobium leguminosarum bv. trifolii 4S5, which carries Tn5-mob, was successfully transferred into Agrobacterium tumefaciens A136 by using a conjugation method. The resulting transconjugants induced the development of ineffective nitrogen-fixing nodules on the roots of white clover seedlings. Depending on the manner in which the pSym was retained, the transconjugants were divided into two groups of strains, Afp and Afcs. pSym was retained as a plasmid in the Afp strains but was integrated into the int gene encoding a phage-related integrase on the linear chromosome of A. tumefaciens A136 in strain Afcs1 (one of the Afcs strains) to form a symbiosis island. Conjugation was performed between strain Afcs1 and R. leguminosarum bv. trifolii H1 (a pSym-cured derivative of wild-type strain 4S), and the Rhizobium H1tr strains were screened as transconjugants. Eighteen of the H1tr strains induced effective nitrogen-fixing nodules on the roots of the host plants. pSym was transferred into all of the transconjugants, except for strain H1tr1, at the same size as pSym of strain 4S5. In strain H1tr1, pSym was integrated into the chromosome as a symbiosis island. These data suggest that pSym can exist among Rhizobium and Agrobacterium strains both as a plasmid and as a symbiosis island with transposon mediation. PMID:18497485

  6. Ação de herbicidas sobre o crescimento de estirpes de Rhizobium tropici Herbicide action on the growth of Rhizobium tropici strains

    Directory of Open Access Journals (Sweden)

    J.B. Santos

    2006-09-01

    Full Text Available O objetivo deste trabalho foi avaliar o crescimento das estirpes de Rhizobium tropici BR 322 e BR 520, utilizadas como inoculantes na cultura do feijoeiro no Brasil, em meio de cultura à base de manitol e extrato de levedura (YM adicionado de diferentes herbicidas (bentazon, metolachlor, imazamox, fluazifop-p-butil, fomesafen e paraquat. Os herbicidas fluazifop-p-butil e fomesafen foram avaliados puros e em mistura comercial, em concentrações variando entre 0,0 e 49,23 mg L-1. O crescimento das estirpes de Rhizobium foi avaliado em espectrofotômetro ao longo de 100 horas de incubação, por meio da leitura da densidade ótica, a 560 nm, sendo, posteriormente, convertido em unidades formadoras de colônia por mL. Observou-se que o paraquat foi o herbicida com maior inibição do crescimento das estirpes avaliadas, seguido pela mistura comercial de fomesafen e fluazifop-p-butil. Para os demais herbicidas, a redução do crescimento não foi significativa. De modo geral, a estirpe BR 520 mostrou-se mais tolerante aos herbicidas testados, com exceção do paraquat. No ensaio de concentrações crescentes do fomesafen, isolado ou em mistura com fluazifop-p-butil, não foi possível determinar o I50 (concentração do herbicida que reduz em 50% o crescimento do rizóbio; a maior redução, de 31,1%, foi observada para a estirpe BR 322 na máxima concentração testada (49,23 mg L-1 da mistura comercial.This work aimed to evaluate the growth of Rhizobium tropici BR322 and BR 520 strains, used as inoculant on common bean in Brazil, in yeast extract manitol (YM medium supplemented with different herbicides (bentazon, metolachlor, imazamox, fluazifop-p-butyl, fomesafen and paraquat. Fluazifop-p-butyl and fomesafen were evaluated pure and in a commercial mixture with concentration varying from 0.0 to 49.23 mg L-1. Cell growth was assessed by optic density readings in a spectrophotometer at 560 nm, being later converted to colony forming units per mL. Paraquat caused higher inhibition of cell growth, followed by the commercial mixture fomesafen and fluazifop-p-butyl. For the other herbicides, growth reduction was not significant. In general, BR 520 strain was more tolerant to the tested herbicides, except to paraquat. The herbicide concentration I50, (which decreased Rhizobium growth in 50% could not be determined in the fomesafen concentrations tested, isolated or mixed to fluazifop-p-butyl. The highest reduction of 31.1% was observed in BR322 at the maximum tested concentration of the commercial mixture.

  7. Ação de herbicidas sobre o crescimento de estirpes de Rhizobium tropici / Herbicide action on the growth of Rhizobium tropici strains

    Scientific Electronic Library Online (English)

    J.B., Santos; A.A., Silva; M.D., Costa; A., Jakelaitis; R., Vivian; E.A., Santos.

    2006-09-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste trabalho foi avaliar o crescimento das estirpes de Rhizobium tropici BR 322 e BR 520, utilizadas como inoculantes na cultura do feijoeiro no Brasil, em meio de cultura à base de manitol e extrato de levedura (YM) adicionado de diferentes herbicidas (bentazon, metolachlor, imazamox, [...] fluazifop-p-butil, fomesafen e paraquat). Os herbicidas fluazifop-p-butil e fomesafen foram avaliados puros e em mistura comercial, em concentrações variando entre 0,0 e 49,23 mg L-1. O crescimento das estirpes de Rhizobium foi avaliado em espectrofotômetro ao longo de 100 horas de incubação, por meio da leitura da densidade ótica, a 560 nm, sendo, posteriormente, convertido em unidades formadoras de colônia por mL. Observou-se que o paraquat foi o herbicida com maior inibição do crescimento das estirpes avaliadas, seguido pela mistura comercial de fomesafen e fluazifop-p-butil. Para os demais herbicidas, a redução do crescimento não foi significativa. De modo geral, a estirpe BR 520 mostrou-se mais tolerante aos herbicidas testados, com exceção do paraquat. No ensaio de concentrações crescentes do fomesafen, isolado ou em mistura com fluazifop-p-butil, não foi possível determinar o I50 (concentração do herbicida que reduz em 50% o crescimento do rizóbio); a maior redução, de 31,1%, foi observada para a estirpe BR 322 na máxima concentração testada (49,23 mg L-1) da mistura comercial. Abstract in english This work aimed to evaluate the growth of Rhizobium tropici BR322 and BR 520 strains, used as inoculant on common bean in Brazil, in yeast extract manitol (YM) medium supplemented with different herbicides (bentazon, metolachlor, imazamox, fluazifop-p-butyl, fomesafen and paraquat). Fluazifop-p-buty [...] l and fomesafen were evaluated pure and in a commercial mixture with concentration varying from 0.0 to 49.23 mg L-1. Cell growth was assessed by optic density readings in a spectrophotometer at 560 nm, being later converted to colony forming units per mL. Paraquat caused higher inhibition of cell growth, followed by the commercial mixture fomesafen and fluazifop-p-butyl. For the other herbicides, growth reduction was not significant. In general, BR 520 strain was more tolerant to the tested herbicides, except to paraquat. The herbicide concentration I50, (which decreased Rhizobium growth in 50%) could not be determined in the fomesafen concentrations tested, isolated or mixed to fluazifop-p-butyl. The highest reduction of 31.1% was observed in BR322 at the maximum tested concentration of the commercial mixture.

  8. Microgravity effects on the legume/Rhizobium symbiosis

    Science.gov (United States)

    Urban, James E.

    1997-01-01

    Symbiotic nitrogen fixation is of critical importance to world agriculture and likely will be a critical part of life support systems developed for prolonged missions in space. Bacteroid formation, an essential step in an effective Dutch White Clover/Rhizobium leguminosarum bv trifolii symbiosis, is induced by succinic acid which is produced by the plant and which is bound and incorporated by the bacterium. Aspirin mimics succinate in its role as a bacteroid inducer and measures of aspirin binding mimiced measurements of succinate binding. In normal gravity (1×g), rhizobium bacteria immediately bound relatively high levels of aspirin (or succinate) in a readily reversible manner. Within a few seconds a portion of this initially bound aspirin became irreversibly bound. In the microgravity environment aboard the NASA 930 aircraft, rhizobia did not display the initial reversible binding of succinate, but did display a similar kinetic pattern of irreversible binding, and ultimately bound 32% more succinate (Acta Astronautica 36:129-133, 1995.) In normal gravity succinate treated cells stop dividing and swell to their maximum size (twice the normal cell volume) within a time equivalent to the time required for two normal cell doublings. Swelling in microgravity was tested in FPA and BPM sample holders aboard the space shuttle (USML-1, and STS-54, 57, and 60.) The behavior of cells in the two sample holders was similar, and swelling behavior of cells in microgravity was identical to behavior in normal gravity.

  9. Oligogalacturonides: novel signaling molecules in Rhizobium-legume communications.

    Science.gov (United States)

    Moscatiello, Roberto; Baldan, Barbara; Squartini, Andrea; Mariani, Paola; Navazio, Lorella

    2012-11-01

    Oligogalacturonides are pectic fragments of the plant cell wall, whose signaling role has been described thus far during plant development and plant-pathogen interactions. In the present work, we evaluated the potential involvement of oligogalacturonides in the molecular communications between legumes and rhizobia during the establishment of nitrogen-fixing symbiosis. Oligogalacturonides with a degree of polymerization of 10 to 15 were found to trigger a rapid intracellular production of reactive oxygen species in Rhizobium leguminosarum bv. viciae 3841. Accumulation of H(2)O(2), detected by both 2',7'-dichlorodihydrofluorescein diacetate-based fluorescence and electron-dense deposits of cerium perhydroxides, was transient and did not affect bacterial cell viability, due to the prompt activation of the katG gene encoding a catalase. Calcium measurements carried out in R. leguminosarum transformed with the bioluminescent Ca(2+) reporter aequorin demonstrated the induction of a rapid and remarkable intracellular Ca(2+) increase in response to oligogalacturonides. When applied jointly with naringenin, oligogalacturonides effectively inhibited flavonoid-induced nod gene expression, indicating an antagonistic interplay between oligogalacturonides and inducing flavonoids in the early stages of plant root colonization. The above data suggest a novel role for oligogalacturonides as signaling molecules released in the rhizosphere in the initial rhizobium-legume interaction. PMID:22835276

  10. A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

    Energy Technology Data Exchange (ETDEWEB)

    Nadler, K.D.; Chen, Jing-Wen; John, T.R. (Michigan State Univ., East Lansing (USA)); Johnston, A.W.B. (The John Innes Institute, Norwich (England))

    1990-02-01

    Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of {sup 55}Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. The authors mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbiotically.

  11. A rhizobium leguminosarum mutant defective in symbiotic iron acquisition

    International Nuclear Information System (INIS)

    Iron acquisition by symbiotic Rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. Rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. The pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency. Several iron(III)-solubilizing agents, such as citrate, hydroxyquinoline, and dihydroxybenzoate, stimulated growth of 116 on low-iron solid medium; anthranilic acid, the R. leguminosarum siderophore, inhibited low-iron growth of 116. The initial rate of 55Fe uptake by suspensions of iron-starved 116 cells was 10-fold less than that of iron-starved wild-type cells. Electron microscopic observations revealed no morphological abnormalities in the small, white nodules induced by 116. Nodule cortical cells were filled with vesicles containing apparently normal bacteroids. No premature degeneration of bacteroids or of plant cell organelles was evident. The authors mapped pop-1 by R plasmid-mediated conjugation and recombination to the ade-27-rib-2 region of the R. leguminosarum chromosome. No segregation of pop-1 and the symbiotic defect was observed among the recombinants from these crosses. Cosmid pKN1, a pLAFR1 derivative containing a 24-kilobase-pair fragment of R. leguminosarum DNA, conferred on 116 the ability to grow on dipyridyl medium and to fix nitrogen symbioticallymedium and to fix nitrogen symbiotically

  12. Antimicrobial activities of Rhizobium sp. strains against Pseudomonas savastanoi, the agent responsible for the olive knot disease in Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Mourad, K.; Fadhila, K.; Chahinez, M.; Merien, R.; Philippe, L. de; Abdelkader, B.

    2009-07-01

    In the present investigation, six Rhizobium strains isolated from Algerian soil were checked for their antimicrobial activity against Pseudomonas savastanoi, the agent responsible for olive knot disease. Rhizobium sp. ORN 24 and ORN 83 were found to produce antimicrobial activities against Pseudomonas savastanoi. The antimicrobial activity produced by Rhizobium sp. ORN24 was precipitable with ammonium sulfate, between 1,000 and 10,000 KDa molecular weight, heat resistant but sensitive to proteases and detergents. These characteristics suggest the bacteriocin nature of the antimicrobial substance produced by Rhizobium sp. ORN24, named rhizobiocin 24. In contrast, the antimicrobial activity produced by Rhizobium sp. ORN83 was not precipitable with ammonium sulfate; it was smaller than 1,000 KDa molecular weight, heat labile, and protease and detergent resistant. These characteristics could indicate the relationship between the antimicrobial substance produced by Rhizobium sp. ORN 83 and the small bacteriocins described in other rhizobia. (Author) 51 refs.

  13. Paysage et implantations du Néolithique final à l'âge du Bronze ancien au Collet-Redon (Martigues, Bouches-du-Rhône)

    OpenAIRE

    Cauliez, Jessie; Blaise, Emilie; Cade, Catherine; Desse, Jean; Desse-berset, Nathalie; Durrenmath, Gilles; Gilabert, Cristophe; Martin, Sophie; Vella, Claude

    2007-01-01

    Depuis 1999, le site du Collet-Redon (Martigues, Bouches-du-Rhône) est réinvesti en vue d'acquérir de nouvelles données sur les diverses phases d'occupation ou de fréquentation qui se sont succédées depuis les premières installations au Néolithique final jusqu'à l'âge du Bronze ancien. Simultanément à l'ouverture d'une nouvelle zone de fouilles, plusieurs programmes d'étude sont engagés – architecturaux et paléoenvironnementaux – qui permettent une mise en parallèle des ?...

  14. Genome sequence of the acid-tolerant strain Rhizobium sp. LPU83.

    Science.gov (United States)

    Wibberg, Daniel; Tejerizo, Gonzalo Torres; Del Papa, María Florencia; Martini, Carla; Pühler, Alfred; Lagares, Antonio; Schlüter, Andreas; Pistorio, Mariano

    2014-04-20

    Rhizobia are important members of the soil microbiome since they enter into nitrogen-fixing symbiosis with different legume host plants. Rhizobium sp. LPU83 is an acid-tolerant Rhizobium strain featuring a broad-host-range. However, it is ineffective in nitrogen fixation. Here, the improved draft genome sequence of this strain is reported. Genome sequence information provides the basis for analysis of its acid tolerance, symbiotic properties and taxonomic classification. PMID:24556327

  15. Narrow- and Broad-Host-Range Symbiotic Plasmids of Rhizobium spp. Strains That Nodulate Phaseolus vulgaris

    OpenAIRE

    Brom, Susana; Martinez, Esperanza; Da?vila, Guillermo; Palacios, Rafael

    1988-01-01

    Agrobacterium transconjugants containing symbiotic plasmids from different Rhizobium spp. strains that nodulate Phaseolus vulgaris were obtained. All transconjugants conserved the parental nodulation host range. Symbiotic (Sym) plasmids of Rhizobium strains isolated originally from P. vulgaris nodules, which had a broad nodulation host range, and single-copy nitrogenase genes conferred a Fix+ phenotype to the Agrobacterium transconjugants. A Fix? phenotype was obtained with Sym plasmids of ...

  16. Studies on a novel insertion sequence, ISR11, isolated from rhizobium leguminosarum biovar viciae

    OpenAIRE

    O Brien, John

    1993-01-01

    An insertion sequence, ISRll, isolated from Rhizobium leguminosarum biovar viciae was studied in detail. Both strands of the entire element were sequenced. The inverted repeats (13bp) and target duplications (8bp) of the element had features in common with three other IS elements, I S R m 2 , IS66 and IS866 (from Rhizobium meliloti and Agrobacterium tumefaciens). The GENBANK and PIR sequence databases were searched for similarities to ISRll. The homologies found were to ...

  17. Genodiversity of dominant Rhizobium leguminosarum bv. Trifolii isolated from 11 types of soil in Serbia

    OpenAIRE

    Joši? Dragana; Mili?i? Bogi?; Mladenovi?-Drini? Snežana; Jarak Mirjana

    2008-01-01

    Rhizobium leguminosarum bv. trifolii is microsymbiont Trifolium pratense and Trifolium repens, which are very important legumes in Serbia. The natural nodulating population of those bacteria was collected and estimated biodiversity distribution by monitoring dominant genotypes of these bacteria. The population of Rhizobium leguminosarum bv. trifolii were collected from 50 marked locations of 11 types of soil in Serbia. 437 natural isolates, rescued from nodules of Trifolium repens or Trifoliu...

  18. The central domain of Rhizobium leguminosarum DctD functions independently to activate transcription.

    OpenAIRE

    Huala, E.; Stigter, J.; Ausubel, F. M.

    1992-01-01

    Sigma 54-dependent transcriptional activators such as Escherichia coli NtrC, Rhizobium meliloti NifA, and Rhizobium leguminosarum DctD share similar central and carboxy-terminal domains but differ in the structure and function of their amino-terminal domains. We have deleted the amino-terminal and carboxy-terminal domains of R. leguminosarum DctD and have demonstrated that the central domain of DctD, like that of NifA, is transcriptionally competent.

  19. Identification and characterization of symbiotic genes on the Rhizobium leguminosarum PRE sym-plasmid.

    OpenAIRE

    Schetgens, T. M. P.

    1986-01-01

    Bacteria of the genera Rhizobium and Bradyrhizobium are unique in their quality to form nitrogen-fixing root nodules in symbiosis with leguminous plants. In fast-growing Rhizobium bacteria the genes involved in host recognition and nodule development ( nod ) and in nitrogen fixation ( nif or fix ) are located on large sym -plasmids (for recent review see e.g. Ausubel, 1984).The aim of the present investigations was to identify symbiotic genes in R.leguminosarum PRE and to study their expressi...

  20. Dilution of Liquid Rhizobium Cultures To Increase Production Capacity of Inoculant Plants †

    OpenAIRE

    Somasegaran, Padmanabhan; Halliday, Jake

    1982-01-01

    Experiments were undertaken to test whether peat-based legume seed inoculants, which are prepared with liquid cultures that have been deliberately diluted, can attain and sustain acceptable numbers of viable rhizobia. Liquid cultures of Rhizobium japonicum and Rhizobium phaseoli were diluted to give 108, 107, or 106 cells per ml, using either deionized water, quarter-strength yeast-mannitol broth, yeast-sucrose broth, or yeast-water. The variously diluted cultures were incorporated into gamma...

  1. Effect of Steam Sterilization and Gamma Irradiation of Peat on Quality of Rhizobium Inoculants

    OpenAIRE

    Strijdom, Barend W.; Rensburg, Henri Jansen

    1981-01-01

    Data obtained by independent tests on each of 483 batches of Rhizobium inoculants for Glycine max, Medicago sativa, and Arachis hypogaea, manufactured commercially in South Africa, are reported and discussed. Whereas the average cell count per gram per batch was well in excess of 109, inoculants for G. max and M. sativa manufactured with peat treated with gamma irradiation at a dose of 50 kGr contained significantly higher numbers of Rhizobium cells than inoculants from peat which received 25...

  2. Energy supply for dinitrogen fixation by Azotobacter vinelandii and by bacteroids of Rhizobium leguminosarum

    OpenAIRE

    Laane, N. C. M.

    1980-01-01

    The central issue of this thesis is how obligate aerobes, such as Rhizobium leguminosarum bacteroids and Azotobacter vinelandii, generate and regulate the energy supply (in the form of ATP and reducing equivalents) for nitrogenase.In an effective Rhizobium -legume symbiosis, the actual reduction of dinitrogen into ammonia is carried out in the root nodules by bacteroids. In order to study this intriguing process on the level of the bacteroids, it is clear that bacteroids have to be isolated ...

  3. Use of combined inoculum of Azospirillum and Rhizobium in winged bean Psophocarpus tetragonolobus (L) D.C

    OpenAIRE

    Iruthayathas, Ee; Vlassak, K.

    1985-01-01

    The potential of using the free living N -fixing Azospirillum in increasing the nodulation and N2-fixation by Rhizobium in winged bean was analysed. Various strains of winged bean Rhizobium and several strains of Azospirillum were tested in combined inoculations. Substantial increases in nodulation, N2-fixation, shoot dry matter production and N gain due to the mixed inoculation were obtained in one Rhizobium strain namely KUL-BH and most of the Azospirillum strains used. The influence of Rhi...

  4. Sobrevivência e nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas

    Directory of Open Access Journals (Sweden)

    Araújo Ademir Sérgio Ferreira de

    2006-01-01

    Full Text Available O objetivo deste trabalho foi avaliar a sobrevivência e a capacidade de nodulação do Rhizobium tropici em sementes de feijão tratadas com fungicidas. O estudo foi realizado em laboratório e em casa de vegetação. Sementes de feijão (Phaseolus vulgaris foram tratadas com seis diferentes fungicidas e inoculadas com Rhizobium tropici estirpe CIAT 899. A sobrevivência do Rhizobium nas sementes foi avaliada no tempo 0 e 24 horas após o tratamento com fungicidas e a inoculação, utilizando o método do número mais provável (NMP. A nodulação do feijão, em plantio realizado no tempo 0 e 24 horas após o tratamento com fungicidas, e a inoculação foram avaliadas em solo com população estabelecida de Rhizobium nativo aos trinta dias após a emergência das plantas. A sobrevivência do Rhizobium inoculado nas sementes foi prejudicada pela aplicação dos fungicidas avaliados. A nodulação do feijoeiro foi reduzida pela aplicação dos fungicidas, quando o plantio foi realizado 24 horas após o tratamento das sementes. Entretanto, foram encontrados nódulos em todos os tratamentos, evidenciando que houve nodulação do Rhizobium nativo do solo.

  5. Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes

    DEFF Research Database (Denmark)

    Engvild, Kjeld Christensen; Nielsen, G.

    1985-01-01

    Sonieated extracts of rhizobia, especiaUy Rhizobium leguminosarum from pea and vetch, were run in horizontal starch gel electrophoresis in the cold. The rhizobia were grown on agar on a slime suppressing substrate of tryptone-yeast extract-CaCl2 with small amounts of mannitol, sorbitol and arabinose and other sugars as enzyme inducers. After electrophoresis the gels were separated into several slabs by a gel cutter. Each slab was stained for a particular enzyme. Among numerous enzyme systems tested we found useful variation in esterases (EC 3.1.1.1, EC 3.1.1.2), 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30), mannitol dehydrogenase (EC 1.1.1.67), and arabinose dehydrogenase (EC 1.1.1.46). It was possible to distinguish at least 7 different types of pea rhizobia among 16 strains isolated from one batch of 5 kg soil.

  6. Final Report: Research Study on Development of Environmental Friendly Spray-on Foam Insulation (SOFI) for the External Tank (ET)

    Science.gov (United States)

    Stuckey, James M.

    1996-01-01

    The selection and quantification of four foams using a more environmentally friendly HCFC-141b blowing agent replacing foams that used the CFC-11 blowing agent for the external tank (ET) LWT has been addressed along with problems and solutions that were encountered during verification. The effort on two lower density spray foams for the ET SLWT are presented, but predicted weight savings were not encouraging. Suggestions for possible problem solving are included along with a new approach for selecting foams for qualification as back-up foams for the foams used on the ET LWT. We investigated three resins for use as thermally sprayed coatings for corrosion prevention on metal. The best coating was obtained with a thermoplastic polyimide resin. This coating has a good chance of meeting ET requirements. Possible third generation blowing agents have been shown usable in polyurethane spray and pour foams, and solubility in isocyannate foam components are acceptable. We considered aerogels as insulation materials on space vehicles, and suggested a liner for a liquid oxygen (LOX) composite tank.

  7. Rhizobium grahamii sp. nov., from nodules of Dalea leporina, Leucaena leucocephala and Clitoria ternatea, and Rhizobium mesoamericanum sp. nov., from nodules of Phaseolus vulgaris, siratro, cowpea and Mimosa pudica.

    Science.gov (United States)

    López-López, Aline; Rogel-Hernández, Marco A; Barois, Isabelle; Ortiz Ceballos, Angel I; Martínez, Julio; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza

    2012-09-01

    Two novel related Rhizobium species, Rhizobium grahamii sp. nov. and Rhizobium mesoamericanum sp. nov., were identified by a polyphasic approach using DNA-DNA hybridization, whole-genome sequencing and phylogenetic and phenotypic characterization including nodulation of Leucaena leucocephala and Phaseolus vulgaris (bean). As similar bacteria were found in the Los Tuxtlas rainforest in Mexico and in Central America, we suggest the existence of a Mesoamerican microbiological corridor. The type strain of Rhizobium grahamii sp. nov. is CCGE 502(T) (= ATCC BAA-2124(T) = CFN 242(T) = Dal4(T) = HAMBI 3152(T)) and that of Rhizobium mesoamericanum sp. nov. is CCGE 501(T) (= ATCC BAA-2123(T) = HAMBI 3151(T) = CIP 110148(T) = 1847(T)). PMID:22081714

  8. Interacción micorriza vesiculo-arbuscular, Rhizobium leguminosa en un oxisol de los Llanos Orientales de Colombia

    Directory of Open Access Journals (Sweden)

    Satizabal E. Jorge H.

    1987-03-01

    Full Text Available En los dos primeros trabajos (la y lb, se evaluó la interacción entre cepas seleccionadas de Rhizobium (apropiadas para la leguminosa forrajera tropical Centrosema macrocarpum y especies (Entrophospora colombiana, Acaulospora longula, Glomus manihotis de micorriza vesiculo arbuscular (MVA, en un suelo esterilizado, fijador de P. Los experimentos se diferenciaron por las fuentes de P utilizadas. Por su mayor producción de materia seca, absorción de minerales, nodulación y infección por MVA, se destacaron las plantas inoculadas con cuales quiera de las cepas de FIlizobiumy Glomus manihotis (Experimento la o Acaulospora longula (Experimento lb. En la tercera investigación (Experimento II, se evalúo en Centrosema la interacción MVA, Rhizobiumo N-químico (niveles equivalentes a 0, 30,55, 105,0 + Rhiz. y 30 + Rhiz. kg N ha-1 y dosis de P (0, 20, 40 y 80 kg ha-1. Es aconsejable aplicar pequeñas dosis (30 kg ha-1 de N al momento de la siembra e inocular con Rhizobium. Plantas inoculadas con MVA presentaron su óptimo crecimiento con 40 kg P ha-1. Dosis de 80 kg P ha-1 favoreció la eficiencia de la bacteria más no la del hongo.In the first two works (la and lb we evaluated the interation between selected stumps of Rhizobium (appropiate for the tropical forage legumes Centrosema macrocarpum and species (Entrophospora colombiana, Acaulospora longula, Glomus manihotis of vesicular-arbuscular mycorrhiza (MVA, in a sterelize soil fixer of P. The two experiments are different because we used different P sources. For the best production of dry matter, absorption of minerals, nodulation and infection for MVA; rebounded the plants with the inoculation with any of the Rhizobium´s stumps and Glomus manihotis (Experiment la of Acaulospora longula (Experiment lb. In the third investigation (Experiment II we evaluated in Centrosema the interaction MVA. Rhizobium and chemical N (levels equivalent to 0,30. 55, 105, O + Rhizobium and 30 + Rhizobium kg N ha-1 and amount of P (O, 20, 40 and 80 kg ha-1. Is advisable to apply small amount (30 kg ha-1 of N fertilizer at the time of sowing the Centrosema and the inoculation with Rhizobium. The plants inoculated with MVA showed a best growing in the amount 40kg Pha -1 80 kg Pha -1 helped in the efficacy of the bacterium and it didn't help in the efficacy of the fungus.

  9. Hot-symbiont interactions. III. Purification and partial characterization of Rhizobium lipopolysaccharides

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, R.W.; Sanders, R.E.; Napoli, C.; Albersheim, P.

    1978-01-01

    The lipopolysaccharides of three strains each of Rhizobium leguminosarum, R. phasecoli, and R. trifolii have been purified and partially characterized. The last step in the purification procedure is gel filtration column chromatography using Sepharose 4B with the elution buffer consisting of ethylenediaminetetraacetic acid and triethylamine. Each of the lipopolysaccharides reported in this paper elutes as a symmetrical peak in the partially included volume of this Sepharose 4B column. The ration of 2-keto-3-deoxyoctonate acid (a sugar which is characteristic of lipopolysaccharides) to hexose is constant throughout the carbohydrate-containing peaks as they elute from the Sepharose 4B. The compositions and immunodominant structures of the purified lipopolysaccharides vary as much among strains of a single Rhizobium species as among the different species of Rhizobium. There is no obvious correlation between the nodulation group to which a Rhizobium belongs and the chemical composition or immunochemistry of the Rhizobium's lipopolysaccharide. There is extensive crosslysis by phage of strains of R. trifolii, R. phaseoli, and R. leguminosarum. This suggests that the receptors for these cross-lysing phage reside either in nonlipopolysaccharide structures or in common structures within the lipopolysaccharide which are not detected by compositional or immunochemical analysis.

  10. The isolation, enumeration, and characterization of Rhizobium bacteria of the soil in Wamena Biological Garden

    Directory of Open Access Journals (Sweden)

    SRI PURWANINGSIH

    2005-04-01

    Full Text Available The eleven soil samples have been isolated and characterized. The aims of the study were to get the pure culture and some data which described about enumeration and especially their characters in relation to the acids and bases reaction in their growth. The isolation of the bacteria use Yeast Extract Mannitol Agar medium (YEMA while the characterization by using YEMA medium mixed with Brom Thymol Blue and Congo Red indicators respectively. The results showed that eighteen isolates have been isolated which consisted of three low growing and fifteen fast growing bacteria. Two isolates were not indicated Rhizobium and sixteen were Rhizobium. Density of Rhizobium enumeration was varied which related to soil organic matter content. The enumeration bacteria in YEMA medium were in the range of 0.6 x 105 and 11.6 x 105 CFU /g soil. The highest population was found in soil sample of Wieb vegetation.

  11. Cultivar and Rhizobium Strain Effects on the Symbiotic Performance of Pea (Pisum sativum)

    DEFF Research Database (Denmark)

    SkØt, Leif

    1983-01-01

    The symbiotic performance of four pea (Pisum sativum L.) cultivars in combination with each of four strains of Rhizobium leguminosarum was studied in growth chamber experiments in order to estimate the effects of cultivars, strains and cultivar × strain interaction on the variation in dry weight, N content and dry weight/N ratio. At harvest 63 days after planting, cultivars accounted for 75% of the variation in dry weight, while the Rhizobium strains accounted for 63% of the variation in N-content and 70% of the variation in dry weight/N ratio. Cultivar × strain interactions were statistically significant, but of minor quantitative importance, accounting for 5–15% of the total variation. Rhizobium strains also influenced the partitioning of N between reproductive and vegetative plant parts and between root and shoot biomass.

  12. Effect of Rhizobium and Mycorhiza inoculation on the nursery growth of Acacia and Teline monspessulana

    International Nuclear Information System (INIS)

    In an experiment accomplished in the tree nursery Tisquesusa located in Madrid (Cundinamarca) was evaluated the effect of the inoculation with strains selected of foreign and Indigenous rhizobium and Arbuscular mycorrhizal fungi am (Glomus folescutolum) on the growth, nitrogen fixation, and micorrization of Acacia (Acacia decurrens) and Retamo (Teline monspessulana) that they are used In soils recovery by the Corporacion Autonoma Regional de Cundinamarca CAR. The studied species presented positive response to the inoculation with rhizobium; the indigenous strain DQ6-09, isolated in Guatavita (Cundinamarca), presented the better results in Retamo and also in Acacia alone and in mixture with the foreign strain T1881. The inoculation with fungi AM increased the heights, dry weights, phosphorus content and percentage of micorrization in Acacia and Retamo. The double inoculation with fungi ma and rhizobium it did not increase the nitrogen fixing of Acacia while in Retamo was presented a positive effect with the strain DQ6-09

  13. Biologic fixation of nitrogen in irradiated rhizobium strips

    International Nuclear Information System (INIS)

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-?). The D37 values for the rhizobial strain SEMIA 4077 were 43 J.m-2 (UV) and 32 Gy (R-?) and for the SEMIA 6145 were 45 J.m-2 (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  14. A Rhizobium selenitireducens protein showing selenite reductase activity.

    Science.gov (United States)

    Hunter, W J

    2014-03-01

    Biobarriers remove, via precipitation, the metalloid selenite (SeO??²) from groundwater; a process that involves the biological reduction of soluble SeO??² to insoluble elemental red selenium (Se?). The enzymes associated with this reduction process are poorly understood. In Rhizobium selenitireducens at least two enzymes are potentially involved; one, a nitrite reductase reduces SeO??² to Se? but another protein may also be involved which is investigated in this study. Proteins from R. selenitireducens cells were precipitated with ammonium sulfate and run on native electrophoresis gels. When these gels were incubated with NADH and SeO??² a band of precipitated Se? developed signifying the presence of a SeO??² reducing protein. Bands were cut from the gel and analyzed for peptides via LCMSMS. The amino acid sequences associated with the bands indicated the presence of an NADH:flavin oxidoreductase that resembles YP_001326930 from Sinorhizobium medicae. The protein is part of a protein family termed old-yellow-enzymes (OYE) that contain a flavin binding domain. OYE enzymes are often involved in protecting cells from oxidative stress and, due in part to an active site that has a highly accessible binding pocket, are generally active on a wide range of substrates. This report is the first of an OYE enzyme being involved in SeO??² reduction. PMID:24474405

  15. Effects of iron deficiency on heme biosynthesis in Rhizobium japonicum.

    Science.gov (United States)

    Roessler, P G; Nadler, K D

    1982-03-01

    The effects of iron deficiency on heme biosynthesis in Rhizobium japonicum were examined. Iron-deficient cells had a decreased maximum cell yield and a decreased cytochrome content and excreted protoporphyrin into the growth medium. The activities of the first two enzymes of heme biosynthesis, delta-aminolevulinic acid synthase (EC 2.3.1.37) and delta-aminolevulinic acid dehydrase (EC 4.2.1.24), were diminished in iron-deficient cells, but were returned to normal levels upon addition of iron to the cultures. The addition of iron salts, iron chelators, hemin, or protoporphyrin to cell-free extracts did not affect the activity of these enzymes. The addition of levulinic acid to iron-deficient cultures blocked protoporphyrin excretion and also resulted in high delta-aminolevulinic acid synthase and delta-aminolevulinic acid dehydrase activities. These results suggest the possibility that rhizobial heme biosynthesis in the legume root nodule may be affected by the release of iron from the host plant to the bacteroids. PMID:6277847

  16. Effect of Rhizobium Inoculants on Cowpea under Rainfed Condition

    Directory of Open Access Journals (Sweden)

    Sarker P. C.

    2001-01-01

    Full Text Available A 2-year on-farm experiment was conducted under rainfed condition to study the effect of Rhizobium inoculation (with or without chemical fertilizer and chemical fertilizer ( 0 and 50-30-20 Kg ha -1 P2O5, K2O and S on cowpea. Two sources of biofertilizer were used. Biofertilizer showed significantly higher yield attributes and seed yield of cowpea as compared to control. Biofertilizer of BARI source gave the highest cowpea seed yield (880 Kg ha -1 and the lowest seed yield (658 Kg ha -1 was obtained without biofertilizer. No significant difference was found between the two sources of bio-fertilizer. Chemical fertilizer showed better performance than control in case of seed yield and all yield contributing characters of cowpea. Interaction of bio-fertilizer and chemical fertilizer also showed statistically significant difference. PKS with biofertilizer of both BAU and BARI sources gave the highest seed yield (987 Kg ha -1 and the lowest seed yield (525 Kg ha -1 was obtained from control treatment. Though the highest average rate of return (4556% was found using biofertilizer of BARI source but on consideration of net return and also soil health, PKS with biofertilizer of BARI source where ARR was the second highest may be suggested for growing cowpea under rainfed condition.

  17. Rhizobium nepotum sp. nov. isolated from tumors on different plant species.

    Science.gov (United States)

    Pu?awska, Joanna; Willems, Anne; De Meyer, Sofie E; Süle, Sandor

    2012-06-01

    Five Gram-negative, rod-shaped, non-spore-forming bacteria were isolated from galls on different plant species in Hungary: strain 39/7(T) from Prunus cerasifera Myrobalan, strain 0 from grapevine var. Ezerjó, strain 7/1 from raspberry var. Findus and in Poland, strain C3.4.1 from Colt rootstock (Prunus avium × Prunus pseudocerasus) and strain CP17.2.2 from Prunus avium. Only one of these isolates, strain 0, is able to cause crown gall on different plant species. On the basis of 16S rRNA gene sequence similarity, the strains cluster together and belong to the genus Rhizobium and their closest relative is Rhizobium radiobacter (99.1%). Phylogenetic analysis of the novel strains using housekeeping genes atpD, glnA, gyrB, recA and rpoB revealed their distinct position separate from other known Rhizobium species and confirmed their relation to Rhizobium radiobacter. The major cellular fatty acids are 18:1 w7c, 16:0, 16:0 3OH, summed feature 2 (comprising 12:0 aldehyde, 16:1 iso I and/or 14:0 3OH) and summed feature 3 (comprising 16:1 w7c and/or 15 iso 2OH). DNA-DNA hybridization of strain 39/7(T) with the type strain of R. radiobacter LMG 140(T) revealed 45% DNA-DNA hybridization. Phenotypic and physiological properties differentiate the novel isolates from other closely related species. On the basis of the results obtained, the five isolates are considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium nepotum sp. nov. (type strain 39/7(T)=LMG 26435(T)=CFBP 7436(T)) is proposed. PMID:22463808

  18. Low temperature impact on protein content and peroxidase activity during pea inoculation with Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Akimova G.P.

    2010-11-01

    Full Text Available The study was focused on changes in protein content and peroxidase activity in pea roots subjected to infection with Rhizobium leguminosarum and to low temperature. The amount of protein and peroxidase activity were shown to change in the course of interaction with nodular bacteria and to depend on the temperature and root zones susceptibility to rhizobia. It was concluded that changes in the content of soluble protein and peroxidase activity witness adaptation changes in pea seedlings, hich facilitate normal course of metabolic processes and ensure regulation of plant interaction with Rhizobium in hypothermal conditions.

  19. Effect of Rhizobium Inoculation on Seedling Growth of Albizia niopides (Spruce Ex Bnth Burkart

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available Investigation was carried out on the effect of Rhizobium inoculation on the Seedling Growth and development of Albizia niopoides in a glass house at the International Institute of Tropical Agriculture (IITA Ibadan Nigeria. This involved isolation of Rhizobium from this species microbiologically. There were four treatments in all namely 1 mL Rhizobium inoculation; 5 mL Rhizobium inoculation; 10 mL Rhizobium inoculation and control (without Rhizobium inoculation. They were arranged in a randomized complete block design and replicated three times. The parameters considered went height, collar diameter, leaf number and leaf area. Significant differences were recorded among the treatments with respect to plant height. 10 mL Rhizobium inoculation gave maximum height of 93.6 cm; Diameter increment of 0.77 mm (14 WAP, leaf number 14.7 and leaf area 193.4. The inoculated treatments produced nodule number ranging between 336.7 and 496.0 while uninoculated treatment gave 247.6 nodules dry matter production was directly proportional to the quantity of Rhizobium inoculation applied. 10 mL Rhizobium broth produced the highest nodule dry matter of 24.7 g which was significantly different from the control (13.97 g. No significant difference was recorded among the treatment vis-a-vis leaf and root dry matter production by seedlings of A. niopoides. it is recommended that Rhizobia inoculation should be adopted for the establishment of some nitrogen fixing tree where native Rhizobia is not available.

  20. Nitrogen fixation ability of exopolysaccharide synthesis mutants of Rhizobium sp. strain NGR234 and Rhizobium trifolii is restored by the addition of homologous exopolysaccharides.

    OpenAIRE

    Djordjevic, S. P.; Chen, H.; Batley, M.; Redmond, J. W.; Rolfe, B. G.

    1987-01-01

    Several transposon Tn5-induced mutants of the broad-host-range Rhizobium sp. strain NGR234 produce little or no detectable acidic exopolysaccharide (EPS) and are unable to induce nitrogen-fixing nodules on Leucaena leucocephala var. Peru or siratro plants. The ability of these Exo- mutants to induce functioning nodules on Leucaena plants was restored by coinoculation with a Sym plasmid-cured (Nod- Exo+) derivative of parent strain NGR234, purified EPS from the parent strain, or the oligosacch...

  1. Inoculant Production with Diluted Liquid Cultures of Rhizobium spp. and Autoclaved Peat: Evaluation of Diluents, Rhizobium spp., Peats, Sterility Requirements, Storage, and Plant Effectiveness

    OpenAIRE

    Somasegaran, P.

    1985-01-01

    Fully grown broth cultures of various fast- and slow-growing rhizobia were deliberately diluted with various diluents before their aseptic incorporation into autoclaved peat in polypropylene bags (aseptic method) or mixed with the peat autoclaved in trays (tray method). In a factorial experiment with the aseptic method, autoclaved and irradiated peat samples from five countries were used to prepare inoculants with water-diluted cultures of three Rhizobium spp. When distilled water was used as...

  2. The impact of the EU ETS on electricity prices. Final report to DG Environment of the European Commission

    International Nuclear Information System (INIS)

    On February 2, 2009, a revised edition of the report has been released, including some adjustments and editorial corrections particularly in Section 2.2 and Appendix A. The present study analyses the impact of the EU Emissions Trading Scheme (ETS) on electricity prices, in particular on wholesale power markets across the EU. To study this impact, a variety of methodological approaches is used, including theoretical, empirical, model, literature and policy analyses. The study shows that a significant part of the costs of freely allocated CO2 emission allowances is passed through to power prices, resulting in higher electricity prices for consumers and additional ('windfall') profits for power producers. In addition, it discusses some policy implications of the pass-through of these costs. It concludes that the pass-through of CO2 costs to electricity prices is a rational, carbon-efficient policy, while the issue of windfall profits can be addressed by either taxing these profits or auctioning - rather than free allocations - of the emission allowances

  3. Visualization of Nodulation Gene Activity on the Early Stages of Rhizobium leguminosarum bv. viciae Symbiosis.

    Czech Academy of Sciences Publication Activity Database

    Chovanec, Pavel; Novák, Karel

    2005-01-01

    Ro?. 50, ?. 4 (2005), s. 323-331. ISSN 0015-5632 R&D Projects: GA ?R GA521/03/0192 Institutional research plan: CEZ:AV0Z50200510 Keywords : nodulation * rhizobium leguminosarum * vicia tetrasperma Subject RIV: EE - Microbiology, Virology Impact factor: 0.918, year: 2005

  4. Nodulation of Sesbania Species by Rhizobium (Agrobacterium) Strain IRBG74 and Other Rhizobia

    Science.gov (United States)

    Concatenated sequence analysis with 16S rRNA, rpoB and fusA genes identified a strain (IRBG74) isolated from root nodules of the aquatic legume Sesbania cannabina as a close relative of the plant pathogen Rhizobium radiobacter (syn. Agrobacterium tumefaciens). However, DNA:DNA hybridisation with R. ...

  5. Mass spectrometric analysis of chitin oligosaccharides produced by Rhizobium NodC protein in Escherichia coli.

    OpenAIRE

    Kamst, E.; Drift, K. M.; Thomas-oates, J. E.; Lugtenberg, B. J.; Spaink, H. P.

    1995-01-01

    A system for studying the in vivo activity of Rhizobium NodC protein in Escherichia coli has been developed. Using thin-layer chromatography, high-performance liquid chromatography, and mass spectrometry, we show that in this system R. leguminosarum bv. viciae NodC protein directs the synthesis of chitinpentaose, chitintetraose, chitintriose, and two as yet unidentified modified chitin oligosaccharides.

  6. Distribution of a Population of Rhizobium leguminosarum bv. trifolii among Different Size Classes of Soil Aggregates†

    OpenAIRE

    Mendes, Ieda C.; Bottomley, Peter J.

    1998-01-01

    A combination of the plant infection-soil dilution technique (most-probable-number [MPN] technique) and immunofluorescence direct count (IFDC) microscopy was used to examine the effects of three winter cover crop treatments on the distribution of a soil population of Rhizobium leguminosarum bv. trifolii across different size classes of soil aggregates (

  7. Genome Sequence of Rhizobium lupini HPC(L) Isolated from Saline Desert Soil, Kutch (Gujarat)

    OpenAIRE

    Agarwal, Leena; Purohit, Hemant J.

    2013-01-01

    The Rhizobium lupini strain HPC(L) was isolated from saline desert soil. It grows on minimal media supplemented with CaCO3 as a carbon source. It can also grow under both oligotrophic and heteroptrophic conditions. We report the annotated genome sequence of this strain in a 5.27-Mb scaffold.

  8. Detection and subcellular localization of two Sym plasmid-dependent proteins of Rhizobium leguminosarum biovar viciae.

    OpenAIRE

    Maagd, R. A.; Wijffelman, C. A.; Pees, E.; Lugtenberg, B. J.

    1988-01-01

    The previously described Sym plasmid-dependent 24-kilodalton rhi protein of Rhizobium leguminosarum biovar viciae was localized in the cytosol fraction. Another Sym plasmid-dependent protein of 50 kilodaltons is secreted into the growth medium, and its expression is dependent on both the nodD gene and a nod gene inducer.

  9. Fractionation of Rhizobium leguminosarum cells into outer membrane, cytoplasmic membrane, periplasmic, and cytoplasmic components.

    OpenAIRE

    Maagd, R. A.; Lugtenberg, B.

    1986-01-01

    Rhizobium leguminosarum cells were separated into four distinct fractions by using density gradient centrifugation for the separation of the outer and cytoplasmic membranes and lysozyme-EDTA treatment of whole cells for the isolation of the periplasmic and cytoplasmic fractions. These methods allowed the subcellular localization of R. leguminosarum proteins.

  10. The Viable-but-Nonculturable Condition Is Induced by Copper in Agrobacterium tumefaciens and Rhizobium leguminosarum

    OpenAIRE

    Alexander, Emily; Pham, Dat; Steck, Todd R.

    1999-01-01

    Many bacteria respond to changes in environmental conditions by entering the viable-but-nonculturable state. We have determined that copper can induce nutrient-starved Agrobacterium tumefaciens and Rhizobium leguminosarum cells to become viable but nonculturable. This is the first report of a chemical inducer of this condition.

  11. Nodulation of Sesbania species by Rhizobium (Agrobacterium) strain IRBG74 and other rhizobia.

    Science.gov (United States)

    Cummings, Stephen P; Gyaneshwar, Prasad; Vinuesa, Pablo; Farruggia, Frank T; Andrews, Mitchell; Humphry, David; Elliott, Geoffrey N; Nelson, Andrew; Orr, Caroline; Pettitt, Deborah; Shah, Gopit R; Santos, Scott R; Krishnan, Hari B; Odee, David; Moreira, Fatima M S; Sprent, Janet I; Young, J Peter W; James, Euan K

    2009-10-01

    Concatenated sequence analysis with 16S rRNA, rpoB and fusA genes identified a bacterial strain (IRBG74) isolated from root nodules of the aquatic legume Sesbania cannabina as a close relative of the plant pathogen Rhizobium radiobacter (syn. Agrobacterium tumefaciens). However, DNA:DNA hybridization with R. radiobacter, R. rubi, R. vitis and R. huautlense gave only 44%, 5%, 8% and 8% similarity respectively, suggesting that IRBG74 is potentially a new species. Additionally, it contained no vir genes and lacked tumour-forming ability, but harboured a sym-plasmid containing nifH and nodA genes similar to those in other Sesbania symbionts. Indeed, IRBG74 effectively nodulated S. cannabina and seven other Sesbania spp. that nodulate with Ensifer (Sinorhizobium)/Rhizobium strains with similar nodA genes to IRBG74, but not species that nodulate with Azorhizobium or Mesorhizobium. Light and electron microscopy revealed that IRBG74 infected Sesbania spp. via lateral root junctions under flooded conditions, but via root hairs under non-flooded conditions. Thus, IRBG74 is the first confirmed legume-nodulating symbiont from the Rhizobium (Agrobacterium) clade. Cross-inoculation studies with various Sesbania symbionts showed that S. cannabina could form fully effective symbioses with strains in the genera Rhizobium and Ensifer, only ineffective ones with Azorhizobium strains, and either partially effective (Mesorhizobium huakii) or ineffective (Mesorhizobium plurifarium) symbioses with Mesorhizobium. These data are discussed in terms of the molecular phylogeny of Sesbania and its symbionts. PMID:19555380

  12. Draft Genome Sequence of a Symbiotic Bacterium, Rhizobium vignae CCBAU 05176T

    OpenAIRE

    Liu, Yang; Yi, Zhiwei; Zeng, Runying

    2014-01-01

    The Rhizobium vignae strain CCBAU 05176T was isolated from a root nodule of Astragalus dahuricus grown in Hebei Province, China. It grows on yeast mannitol agar (YMA) supplemented with 0 to 2% (wt/vol) NaCl. We report the annotated genome sequence of this strain in a 6.34-Mb scaffold.

  13. Beta-2-linked glucans secreted by fast-growing species of Rhizobium

    Energy Technology Data Exchange (ETDEWEB)

    York, W.S.; McNeil, M.; Darvill, A.G.; Albersheim, P.

    1980-04-01

    Fast-growing species of Rhizobium were found to secrete low-molecular-weight ..beta..-2-linked glucans when cultured in synthetic liquid medium. These glucans are quite similar to ..beta..-2-linked glucans produced by species of Agrobacterium. No reducing terminus was detected in these glucans.

  14. Rhizobium subbaraonis sp. nov., an endolithic bacterium isolated from beach sand.

    Science.gov (United States)

    Ramana, Ch V; Parag, B; Girija, K R; Ram, B Raghu; Ramana, V Venkata; Sasikala, Ch

    2013-02-01

    Two strains (JC85(T) and JC108) of Gram-stain-negative, motile bacteria were isolated from endolithic beach sand samples on an oligotrophic medium. Based on the 16S rRNA gene sequence analysis, both strains were identified as belonging to the genus Rhizobium. Strain JC108 had 16S rRNA gene sequence similarity of 100?% with Rhizobium pusense NRCPB10(T) and formed a cluster with this strain. Strain JC85(T) had 96.9?% 16S rRNA gene sequence similarity and was 18?% related (based on DNA-DNA hybridization) to Rhizobium borbori DN316(T). With other strains of the genus Rhizobium, the 16S rRNA gene sequence similarity was less than 96.3?%. Strain JC85(T) could tolerate up to 3?% salinity, fix N(2), was resistant to ampicillin (10 µg) and was positive for catalase and oxidase. The major fatty acid was C(18?:?1)?7c (69?%) with minor amounts of C(19?:?0) cyclo ?8c (8.9?%), C(16?:?0) (6.9?%), C(12?:?0) (5.7?%) and C(19?:?1)?7c/C(19?:?1)?6c (2.2?%). Polar lipids of strain JC85(T) include two unidentified aminophospholipids (APL1,2), two unidentified phospholipids (PL1,2), phosphatidylcholine and four unidentified lipids (L1-4). Q-10 is the major quinone of strain JC85(T). Based on polyphasic taxonomic analysis, strain JC85(T) represents a novel species for which, the name Rhizobium subbaraonis JC85(T) is proposed. The type strain is JC85(T) (?=?DSM 24765(T)?=?KCTC 23614(T)). PMID:22544781

  15. Effects of Rhizobium inoculation on Trifolium resupinatum antioxidant system under sulfur dioxide pollution

    Directory of Open Access Journals (Sweden)

    Ladan Bayat

    2014-01-01

    Full Text Available Introduction: Plant growth stimulating rhizobacteria are beneficial bacteria that can cause resistance to various stresses in plants. One of these stresses is SO2 air pollution. SO2 is known as a strong damaging air pollutant that limits growth of plants. The aim of this study is evaluation of the effects of bacterial inoculation with native and standard Rhizobium on Persian clover root growth and antioxidants activity and capacity under air SO2 pollution. Materials and methods: In this study, 31 days plants (no-inoculated and inoculated with two strains of Rhizobium exposed to the different concentrations of SO2 (0 as a control, 0.5, 1, 1.5 and 2 ppm for 5 consecutive days and 2 hours per day. Results: Results showed different concentrations of SO2 had a significant effect on Persian clover root weight and antioxidant system. Increasing SO2 stress decreased root fresh and dry weight and antioxidant capacities (IC50 and increased antioxidant activities (I% of Persian clover leaves significantly in comparison to the control plants (under 0 ppm and increased SOD, CAT and GPX activity. Inoculation of Persian clover plants with native and standard Rhizobium increased root weight and did not show a significant effect on antioxidants activity and capacity, but interaction between Rhizobium inoculation and SO2 treatment reduced significantly the stress effects of high concentration of SO2 on root growth and antioxidants activity and capacity. In fact, level of this change of root growth and antioxidant system under SO2 pollution stress in inoculated plants was lower than in the non-inoculated plants. Discussion and conclusion: As a result, an increase in SO2 concentration caused a decrease in root weight, increase in antioxidants activity and capacity of Persian clover. Inoculation with Rhizobium strains could alleviate the effect of SO2 pollution on antioxidant system by effects on root growth.

  16. A small GTPase of the Rab family is required for root hair formation and preinfection stages of the common bean-Rhizobium symbiotic association.

    Science.gov (United States)

    Blanco, Flavio Antonio; Meschini, Eitel Peltzer; Zanetti, María Eugenia; Aguilar, O Mario

    2009-09-01

    Legume plants are able to establish a symbiotic relationship with soil bacteria from the genus Rhizobium, leading to the formation of nitrogen-fixing root nodules. Successful nodulation requires both the formation of infection threads (ITs) in the root epidermis and the activation of cell division in the cortex to form the nodule primordium. This study describes the characterization of RabA2, a common bean (Phaseolus vulgaris) cDNA previously isolated as differentially expressed in root hairs infected with Rhizobium etli, which encodes a protein highly similar to small GTPases of the RabA2 subfamily. This gene is expressed in roots, particularly in root hairs, where the protein was found to be associated with vesicles that move along the cell. The role of this gene during nodulation has been studied in common bean transgenic roots using a reverse genetic approach. Examination of root morphology in RabA2 RNA interference (RNAi) plants revealed that the number and length of the root hairs were severely reduced in these plants. Upon inoculation with R. etli, nodulation was completely impaired and no induction of early nodulation genes (ENODs), such as ERN1, ENOD40, and Hap5, was detected in silenced hairy roots. Moreover, RabA2 RNAi plants failed to induce root hair deformation and to initiate ITs, indicating that morphological changes that precede bacterial infection are compromised in these plants. We propose that RabA2 acts in polar growth of root hairs and is required for reorientation of the root hair growth axis during bacterial infection. PMID:19749154

  17. The nodC, nodG, and glgX genes of Rhizobium tropici strain PRF 81.

    Science.gov (United States)

    Oliveira, Luciana Ruano; Marcelino, Francismar Corrêa; Barcellos, Fernando Gomes; Rodrigues, Elisete Pains; Megías, Manuel; Hungria, Mariangela

    2010-08-01

    Rhizobium tropici is a diazotrophic microsymbiont of common bean (Phaseolus vulgaris L.) that encompasses important but still poorly studied tropical strains, and a recent significant contribution to the knowledge of the species was the publication of a genomic draft of strain PRF 81, which revealed several novel genes [Pinto et al. Funct Int Gen 9:263-270, 2009]. In this study, we investigated the transcription of nodC, nodG, and glgX genes, located in the nod operon of PRF 81 strain, by reverse-transcription quantitative PCR. All three genes showed low levels of transcription when the cells were grown until exponential growth phase in the presence of common-bean-seed exudates or of the root nod-gene inducer naringenin. However, when cells at the exponential phase of growth were incubated with seed exudates, transcription occurred after only 5 min, and nodC, nodG, and glgX were transcribed 121.97-, 14.86-, and 50.29-fold more than the control, respectively, followed by a rapid decrease in gene transcription. Much lower levels of transcription were observed in the presence of naringenin; furthermore, maximum transcription required 8 h of incubation for all three genes. In light of these results, the mechanisms of induction of the nodulation genes by flavonoids are discussed. PMID:20013017

  18. Characterization and symbiotic importance of acidic extracellular polysaccharides of Rhizobium sp. strain GRH2 isolated from acacia nodules.

    OpenAIRE

    Lopez-lara, I. M.; Orgambide, G.; Dazzo, F. B.; Olivares, J.; Toro, N.

    1993-01-01

    Rhizobium sp. wild-type strain GRH2 was originally isolated from root nodules of the leguminous tree Acacia cyanophylla and has a broad host range which includes herbaceous legumes, e.g., Trifolium spp. We examined the extracellular exopolysaccharides (EPSs) produced by strain GRH2 and found three independent glycosidic structures: a high-molecular-weight acidic heteropolysaccharide which is very similar to the acidic EPS produced by Rhizobium leguminosarum biovar trifolii ANU843, a low-molec...

  19. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp; Caracterizacao quimica dos geis produzidos pelas bacterias diazotroficas Rhizobium tropici e Mesorhizobium sp.

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Nilson Kobori [Departamento de Engenharia e Tecnologia de Alimentos, Instituto de Biociencias, Letras e Ciencias Exatas, Universidade Estadual Paulista, Sao Jose do Rio Preto - SP (Brazil); Aranda-Selverio, Gabriel; Exposti, Diego Tadeu Degli; Silva, Maria de Lourdes Corradi da [Departamento de Fisica, Quimica e Biologia, Faculdade de Ciencias e Tecnologia, Universidade Estadual Paulista, Presidente Prudente - SP (Brazil); Lemos, Eliana Gertrudes Macedo; Campanharo, Joao Carlos [Departamento de Tecnologia, Faculdade de Ciencias Agrarias e Veterinaria, Universidade Estadual Paulista, Jaboticabal - SP (Brazil); Silveira, Joana Lea Meira [Departamento de Bioquimica e Biologia Molecular, Universidade Federal do Parana, Curitiba - PR (Brazil)

    2012-07-01

    The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPSRT) and Mesorhizobium sp (EPSMR) are acidic heteropolysaccharide composed mainly of glucose and galactose in a molar ratio of 4:1 and 5:1 respectively, with traces of mannose ({approx} 1%). Chemical analysis showed the presence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPSRT and EPSMR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, {sup 1}H and {sup 13}C-NMR. (author)

  20. Genotypic Characterisation of Indigenous Rhizobium leguminosarum bv. viciae Field Population in Croatia

    Directory of Open Access Journals (Sweden)

    Mihaela Blažinkov

    2007-06-01

    Full Text Available Genetic diversity of thirteen Rhizobium legumnosarum bv. viciae strains isolated from different field sites in continental part of Croatia was investigated. All rhizobial isolates were obtained either from plants grown in pots containing soil samples or from field grown plants. The strains were analyzed for DNA polymorphism using two DNA fingerprinting methods - randomly amplified polymorphic DNA (RAPD-PCR and repetitive extragenomic palindromic- PCR (rep-PCR. Both methods resulted in very similar grouping of strains. Cluster analysis of rep- and RAPD-PCR profi les showed significant differences among Rh. leguminosarum bv. viciae isolates. The highest differences were detected among reference strains and all field isolates revealing considerable genetic diversity of rhizobial field populations. These results suggest the presence of adapted indigenous Rhizobium leguminosarum bv. viciae strains, probably with higher competitive ability, whose symbiotic properties have to be evaluated in further investigations.

  1. Symbiotic effectiveness of spontaneous antibiotic-resistant mutants of Rhizobium sp. Cicer nodulating chickpea (Cicer arietinum).

    Science.gov (United States)

    Sindhu, S S; Dadarwal, K R

    2001-03-01

    Spontaneous streptomycin-resistant mutants were isolated from two fast growing gum-producing strains Ca85 and Ca401 and from two moderately growing strains Ca181 and Ca534 of Rhizobium sp. Cicer. The nodulation ability and symbiotic effectiveness of the mutants relative to parent strains were evaluated on chickpea (Cicer arietinum) grown in sterilized chillum jars. Some mutants of strains Ca85 and Ca401 showed Nod phenotype whereas some mutants of strains Ca181 and Ca534 showed Nod(+) fix(-) phenotype. Other mutants also showed decreased nodule number and reduction in nitrogenase activity as well as in shoot dry weight as compared to inoculation with parental strains. The results showed that acquisition of streptomycin resistance in Rhizobium sp. Cicer strains is associated with decreased symbiotic effectiveness in chickpea, suggesting that antibiotic-resistant mutants first should be analyzed for symbiotic effectiveness before using these mutants for ecological studies or nodulation competitiveness. PMID:11297364

  2. Isolation and properties of an ultraviolet-sensitive mutant of Rhizobium trifolii

    Energy Technology Data Exchange (ETDEWEB)

    Walton, D.A.; Moseley, B.E.B. (Edinburgh Univ. (UK))

    1981-05-01

    In an attempt to isolate a strain of Rhizobium trifolii which could be highly mutated by ultraviolet light (u.v.), a u.v.-sensitive mutant was isolated using a semi-selective procedure. The mutant was not only 85 times more sensitive than the wild-type to the lethal effects of u.v., but was mutated at u.v. doses which had little mutagenic effect on the wild-type. Its sensitivity to the mutagenic agents methyl methanesulphonate and gamma rays was unaltered, but its spontaneous mutation frequencies for two antibiotic resistances were increased. The mutation conferring u.v. sensitivity was mapped on the chromosome of Rhizobium leguminosarum 300 in a position between the markers ser-2 and ade-88. Unsuccessful attempts were made to transfer into the u.v.-sensitive mutant any one of a number of plasmids known to decrease the lethality of u.v. and enhance its mutagenicity.

  3. Isolation and properties of an ultraviolet-sensitive mutant of Rhizobium trifolii

    International Nuclear Information System (INIS)

    In an attempt to isolate a strain of Rhizobium trifolii which could be highly mutated by ultraviolet light (u.v.), a u.v.-sensitive mutant was isolated using a semi-selective procedure. The mutant was not only 85 times more sensitive than the wild-type to the lethal effects of u.v., but was mutated at u.v. doses which had little mutagenic effect on the wild-type. Its sensitivity to the mutagenic agents methyl methanesulphonate and gamma rays was unaltered, but its spontaneous mutation frequencies for two antibiotic resistances were increased. The mutation conferring u.v. sensitivity was mapped on the chromosome of Rhizobium leguminosarum 300 in a position between the markers ser-2 and ade-88. Unsuccessful attempts were made to transfer into the u.v.-sensitive mutant any one of a number of plasmids known to decrease the lethality of u.v. and enhance its mutagenicity. (author)

  4. Efficacy of Various Rhizobium Strains to Different Varieties of Groundnut (Arachis hypogea L.

    Directory of Open Access Journals (Sweden)

    M. Aslam

    1999-01-01

    Full Text Available Groundnut variety BARD-699 produced significantly the most promising yield than that of variety BARI-89 at Attock, Fatehjang and NARC, Islamabad. Rhizobium strains, NC-92 was found to be less efficient as compared to TAL-1000; TAL-1371. Nodule dry mass and number of pods per plant were much higher than that of control treatment. Although a significant difference in growth and yield of both the varieties due to Rhizobium inoculation was observed but on average basis TAL-1000 and TAL-1371 gave significantly better response for both the varieties in improving growth and yield at all sites. Nevertheless, future prospects for groundnut production are good in Pakistan if the farmers are realized to practice inoculation technology in their fields.

  5. [Production of L(+)-tartaric acid by immobilized Rhizobium strain BK-20].

    Science.gov (United States)

    Lan, Xiang; Bao, Wenna; Pan, Haifeng; Xie, Zhipeng; Zhang, Jianguo

    2014-02-01

    The cis-epoxysuccinate hydrolase (CESH) from Rhizobium strain BK-20 is the key enzyme for L(+)-tartaric acid production. To establish a highly efficient and stable production process, we first optimized the enzyme production from Rhizobium strain BK-20, and then developed an immobilized cell-culture process for sustained production of L(+)-tartaric acid. The enzyme activity of free cells reached (3 498.0 +/- 142.6) U/g, and increased by 643% after optimization. The enzyme activity of immobilized cells reached (2 817.2 +/- 226.7) U/g, under the optimal condition with sodium alginate as carrier, cell concentration at 10% (W/V) and gel concentration at 1.5% (W/V). The immobilized cells preserved high enzyme activity and normal structure after 10 repeated batches. The conversion rate of the substrate was more than 98%, indicating its excellent production stability. PMID:24941753

  6. Mutations in Rhizobium phaseoli that lead to arrested development of infection threads.

    OpenAIRE

    Noel, K. D.; Vandenbosch, K. A.; Kulpaca, B.

    1986-01-01

    Two Rhizobium phaseoli mutants, isolated previously by Tn5 mutagenesis, elicited infection threads which ceased development prematurely, usually within root hairs. These infection threads were wide, globular, and otherwise altered in morphology, compared with normal infection threads. Anatomy and division of the root cortical cells during initial stages of nodule morphogenesis appeared normal. However, later nodule differentiation deviated considerably from normal development, and release of ...

  7. Legumes regulate Rhizobium bacteroid development and persistence by the supply of branched-chain amino acids.

    OpenAIRE

    Prell, J.; White, Jp; Bourdes, A.; Bunnewell, S.; Bongaerts, Rj; Poole, Ps

    2009-01-01

    One of the largest contributions to biologically available nitrogen comes from the reduction of N(2) to ammonia by rhizobia in symbiosis with legumes. Plants supply dicarboxylic acids as a carbon source to bacteroids, and in return they receive ammonia. However, metabolic exchange must be more complex, because effective N(2) fixation by Rhizobium leguminosarum bv viciae bacteroids requires either one of two broad-specificity amino acid ABC transporters (Aap and Bra). It was proposed that amin...

  8. Pathway of ?-Aminobutyrate Metabolism in Rhizobium leguminosarum 3841 and Its Role in Symbiosis?

    OpenAIRE

    Prell, Jurgen; Bourde?s, Alexandre; Karunakaran, Ramakrishnan; Lopez-gomez, Miguel; Poole, Philip

    2009-01-01

    Pea plants incubated in 15N2 rapidly accumulated labeled ?-aminobutyrate (GABA) in the plant cytosol and in bacteroids of Rhizobium leguminosarum bv. viciae 3841. Two pathways of GABA metabolism were identified in R. leguminosarum 3841. In the first, glutamate is formed by GABA aminotransferase (GabT), transferring the amino group from GABA to 2-oxoglutarate. In the second, alanine is formed by two ?-aminotransferases (OpaA and OpaB), transferring the amino group from GABA to pyruvate. Whil...

  9. Análisis genómico y funcional de los sistemas de Quorum Sensing en Rhizobium leguminosarum

    OpenAIRE

    Sanchez Can?izares, Carmen

    2013-01-01

    Rhizobium leguminosarum (Rl) es una alfa-proteobacteria capaz de establecer una simbiosis diazotrófica con distintas leguminosas. A pesar de la importancia de esta simbiosis en el balance global del ciclo del nitrógeno, muy pocos genomas de rhizobios han sido secuenciados, que aporten nuevos conocimientos relacionados con las características genéticas que contribuyen a importantes procesos simbióticos. Únicamente tres secuencias completas de Rl han sido publicadas: Rl bv. viciae 3841 y ...

  10. Genomic heterogeneity of strains nodulating chickpeas (Cicer arietinum L.) and description of Rhizobium mediterraneum sp. nov.

    Science.gov (United States)

    Nour, S M; Cleyet-Marel, J C; Normand, P; Fernandez, M P

    1995-10-01

    The genetic diversity of chickpea strains was studied by using 30 isolates obtained from nodules on chickpeas growing in uninoculated fields over a wide geographic range. The following taxonomic approaches were used: DNA-DNA relatedness analysis, restriction fragment length polymorphism analysis of the amplified 16S ribosomal DNA (rDNA) intergenic spacer (IGS), and total 16S rRNA sequence analysis. The division of chickpea-infective strains into two major phylogenetic groups (groups A and B) that has been described previously was confirmed by the polymorphism of the 16S IGS rDNA. We identified a total of five genomic species, including the previously described species Rhizobium ciceri. All of the group B strains except one were homogeneous and belonged to a single genomic species corresponding to R. ciceri. Group A was heterogeneous, containing three genomic species and five strains that remained unclassified, and its members had very different PCR restriction fragment length polymorphism profiles. The complete 16S rRNA sequences of strains representing the two major groups, R. ciceri UPM-Ca7T (T = type strain) and genomic species 2 strain UPM-Ca36T, exhibited 19 mismatches. Both of these strains belonged to the Rhizobium loti-Rhizobium huakuii branch; R. ciceri UPM-Ca7T was closely related to R. loti, and strain UPM-Ca36T was clearly separated from R. ciceri and closely related to R. huakuii. Thus, genomic species 2 could be distinguished from R. ciceri by its 16S rRNA sequence, by DNA relatedness data, by the polymorphism of the 16S IGS rDNAs, and by previously described multilocus enzyme electrophoresis results and phenotypic characteristics. Therefore, we propose that strains belonging to genomic species 2 should be classified in a new species, Rhizobium mediterraneum, and that strain UPM-Ca36 should be the type strain. PMID:7547282

  11. Relationship between Nif plasmids of fast-growing Rhizobium species and Ti plasmids of Agrobacterium tumefaciens.

    OpenAIRE

    Prakash, R. K.; Schilperoort, R. A.

    1982-01-01

    By use of the Southern blot hybridization technique the extent of DNA homology was determined between the Nif plasmid of a number of fast-growing Rhizobium species and Ti plasmids of the octopine (pTiAch5) and nopaline (pTiC58) type. DNA sequences common to these plasmids were located on functional maps of the Ti plasmids. No homology between Nif plasmids and the T region of Ti plasmids was detected.

  12. Symbiotic Effectiveness and Host-Strain Interactions of Rhizobium fredii USDA 191 on Different Soybean Cultivars †

    OpenAIRE

    Israel, Daniel W.; Mathis, James N.; Barbour, W. Mark; Elkan, Gerald H.

    1986-01-01

    Nodulation, acetylene reduction activity, dry matter accumulation, and total nitrogen accumulation by nodulated plants growing in a nitrogen-free culture system were used to compare the symbiotic effectiveness of the fast-growing Rhizobium fredii USDA 191 with that of the slow-growing Bradyrhizobium japonicum USDA 110 in symbiosis with five soybean (Glycine max (L.) Merr.) cultivars. Measurement of the amount of nitrogen accumulated during a 20-day period of vegetative growth (28 to 48 days a...

  13. Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

    OpenAIRE

    Zahran, Hamdi Hussein

    1999-01-01

    Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, ...

  14. Mutants of Pisum sativum (L.) altered in the symbiosis with Rhizobium leguminosarum.

    OpenAIRE

    Postma, Jenne Geert

    1990-01-01

    The studies on symbiotic nitrogen fixation between pea (Pisum sativum L.) and Rhizobium leguminosarum, which are described in this thesis, were carried out with the use of host mutants. Host mutants were obtained after mutagenic treatments of the seeds with ethyl methane sulphonate (EMS). Mutations were induced in genes which are directly or indirectly involved in the symbiosis. Using different types of host mutants, genetic, morphological-, biochemical- and physiological aspects of an altere...

  15. Introduction of the Escherichia coli gdhA gene into Rhizobium phaseoli: effect on nitrogen fixation.

    OpenAIRE

    Bravo, A.; Becerril, B.; Mora, J.

    1988-01-01

    Rhizobium phaseoli lacks glutamate dehydrogenase (GDH) and assimilates ammonium by the glutamine synthetase-glutamate synthase pathway. A strain of R. phaseoli harboring the Escherichia coli GDH structural gene (gdhA) was constructed. GDH activity was expressed in R. phaseoli in the free-living state and in symbiosis. Nodules with bacteroids that expressed GDH activity had severe impairment of nitrogen fixation. Also, R. phaseoli cells that lost GDH activity and assimilated ammonium by the gl...

  16. Rhizobium meliloti mutants unable to synthesize anthranilate display a novel symbiotic phenotype.

    OpenAIRE

    Barsomian, G. D.; Urzainqui, A.; Lohman, K.; Walker, G. C.

    1992-01-01

    Analyses of Rhizobium meliloti trp auxotrophs suggest that anthranilate biosynthesis by the R. meliloti trpE(G) gene product is necessary during nodule development for establishment of an effective symbiosis. trpE(G) mutants, as well as mutants blocked earlier along this pathway in aromatic amino acid biosynthesis, form nodules on alfalfa that have novel defects. In contrast, R. meliloti trp mutants blocked later in the tryptophan-biosynthetic pathway form normal, pink, nitrogen-fixing nodule...

  17. Chemotaxis of Rhizobium meliloti to the plant flavone luteolin requires functional nodulation genes.

    OpenAIRE

    Caetano-anolle?s, G.; Crist-estes, D. K.; Bauer, W. D.

    1988-01-01

    Luteolin is a phenolic compound from plants that acts as a potent and specific inducer of nodABC gene expression in Rhizobium meliloti. We have found that R. meliloti RCR2011 exhibits positive chemotaxis towards luteolin. A maximum chemotactic response was observed at 10(-8) M. Two closely related flavonoids, naringenin and apigenin, were not chemoattractants. The presence of naringenin but not apigenin abolished chemotaxis of R. meliloti towards luteolin. A large deletion in the nif-nod regi...

  18. Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in Rhizobium leguminosarum PRE

    OpenAIRE

    Klein Lankhorst, R. M.; Katinakis, P.; Kammen, A.; Bos, R. C.

    1988-01-01

    In membranes of Rhizobium leguminosarum bacteroids isolated from nitrogen-fixing pea root nodules, two different protein complexes with NADH dehydrogenase activity were detected. One of these complexes, with a molecular mass of 110 kilodaltons, was also found in membranes of free-living rhizobia, but the other, with a molecular mass of 550 kilodaltons, appeared to be present only in bacteroids. The bacteroid-specific complex, referred to as DH1, probably consists of at least four different su...

  19. Biosynthesis of a galactose-and galacturonic acid-containing polysaccharide in Rhizobium meliloti.

    OpenAIRE

    Ugalde, R. A.; Coira, J. A.; Brill, W. J.

    1986-01-01

    Previous work showed that two different strains derived from a culture of Rhizobium meliloti 102F51 differed with respect to phage specificity, agglutinability by alfalfa seed lectin, and synthesis of a galactose-containing polysaccharide (R. A. Ugalde, H. Handelsman, and W. J. Brill, J. Bacteriol. 166:148-154, 1986). Inner membranes from the more competitive strain incorporated galactose from UDP-galactose when a thermostable factor was present. This factor has now been identified as UDP-gal...

  20. Root colonization of maize and lettuce by bioluminescent Rhizobium leguminosarum biovar phaseoli.

    OpenAIRE

    Chabot, R.; Antoun, H.; Kloepper, J. W.; Beauchamp, C. J.

    1996-01-01

    Two strains of Rhizobium leguminosarum bv. phaseoli and three other plant growth-promoting rhizobacteria (PGPR) were examined for the potential of maize and lettuce root colonization. All of these strains were selected in vitro for their phosphate-solubilizing abilities. Maize and lettuce seeds were treated with derivatives of all strains marked with lux genes for bioluminescence and resistance to kanamycin and rifampin prior to planting in nonsterile Promix and natural soil. The introduced b...

  1. Rhizobium symbiotic genes required for nodulation of legume and nonlegume hosts

    OpenAIRE

    Marvel, Deborah J.; Torrey, John G.; Ausubel, Frederick M.

    1987-01-01

    Parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with Bradyrhizobium or Rhizobium species. The Bradyrhizobium strain Rp501, isolated from Parasponia nodules, also nodulates the legumes siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata). To test whether some of the same genes are involved in the early stages of legume and nonlegume nodulation, we generated transposon Tn5 insertions ...

  2. Influence of Azospirillum Strains on the Nodulation of Clovers by Rhizobium Strains

    OpenAIRE

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

    Mixed cultures of several Azospirillum and Rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with R. trifolii alone. Azospirillum strains affected the nodulation process at a precise cell ratio (R. trifolii/Azospirillum cells) and time of inoculation. All Azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by R. trifolii strains. When nonviable cel...

  3. On the operon structure of the nitrogenase genes of Rhizobium leguminosarum and Azotobacter vinelandii.

    OpenAIRE

    Krol, A. J. M.; Hontelez, J. G. J.; Roozendaal, B.; Kammen, A.

    1982-01-01

    The transcription of the nitrogenase genes in Rhizobium leguminosarum was studied by analysing total cellular RNA from bacteroids for the presence of nitrogenase messenger RNA. The RNA was separated by agarose gel electrophoresis and blotted onto nitrocellulose filters. Messenger RNA for nitrogenase was detected by hybridization with probes derived from plasmid pSA30, a recombinant plasmid carrying the nitrogenase genes of Klebsiella pneumoniae. In the same way nitrogenase mRNA was detected i...

  4. Construction of a marker system for the evaluation of competitiveness for legume nodulation in Rhizobium strains.

    Science.gov (United States)

    Sánchez-Cañizares, Carmen; Palacios, Jose

    2013-03-01

    A marker system has been set up for the analysis of competitiveness of Rhizobium leguminosarum strains for legume nodulation. The strains generated incorporate gusA and celB marker genes at identical positions and allow efficient scoring of single and double infections. Based on this system, we have found that strain UPM791 outcompetes 3841 for nodulation in pea. This technique will be useful to determine the effect of different traits on competitiveness. PMID:23305927

  5. Purification and Properties of Catechol 1,2-Dioxygenase from Rhizobium leguminosarum biovar viceae USDA 2370

    OpenAIRE

    Chen, Yung Pin; Lovell, Charles R.

    1990-01-01

    The catechol 1,2-dioxygenase of Rhizobium leguminosarum biovar viceae USDA 2370 was purified 296-fold, yielding a homogeneous preparation with a specific activity of 51.1 U mg of protein-1. The molecular weight of the native protein was 70,000, with two identical subunits of 34,500 and 1 g-atom of iron per mol. The optimum pH for catalytic activity was 9.0 to 9.5.

  6. Isolation of genes involved in nodulation competitiveness from Rhizobium leguminosarum bv. trifolii T24

    OpenAIRE

    Triplett, Eric W.

    1988-01-01

    Rhizobium leguminosarum bv. trifolii T24 produces a potent anti-rhizobial compound, trifolitoxin, and exclusively nodulates clover roots when in mixed inoculum with trifolitoxin-sensitive strains of R. leguminosarum bv. trifolii [Schwinghamer, E. A. & Belkengren R. P. (1968) Arch. Mikrobiol. 64, 130-145]. In the present study, the isolation of trifolitoxin production and resistance genes is described. A cosmid genomic library of T24 was prepared in pLAFR3. No trifolitoxin expression was obser...

  7. Higher Diversity of Rhizobium leguminosarum Biovar viciae Populations in Arable Soils than in Grass Soils

    OpenAIRE

    Palmer, K. M.; Young, J. P. W.

    2000-01-01

    The bacterial genetic diversity after long-term arable cultivation was compared with that under permanent grassland using replicated paired contrasts, Pea-nodulating Rhizobium leguminosarum populations were sampled from pairs of arable and grass sites at four locations in Yorkshire, United Kingdom, isolates were characterized using both chromosomal (16S-23S ribosomal DNA internal transcribed spacer PCR-restriction fragment length polymorphism) and plasmid (group-specific repC PCR amplificatio...

  8. Subcellular localization of the Rhizobium leguminosarum nodI gene product.

    OpenAIRE

    Schlaman, H. R.; Okker, R. J.; Lugtenberg, B. J.

    1990-01-01

    By the use of antibodies raised against a fusion protein of lacZ'-nodI (produced in Escherichia coli) which specifically react with NodI protein, it was shown that in wild-type Rhizobium leguminosarum biovar viciae NodI protein (i) is recovered with the cytoplasmic membrane fraction and (ii) is translated as part of the nodABCIJ operon. In addition, it was found that the bacterial chromosomal background strongly influences the expression of several nod genes.

  9. Expression of large plasmids in the endosymbiotic form of Rhizobium leguminosarum.

    OpenAIRE

    Krol, A. J. M.; Hontelez, J. G. J.; Bos, R. C.; Kammen, A.

    1980-01-01

    Isolated plasmid DNA from Rhizobium leguminosarum was hybridised with cellular RNA from broth-cultured bacteria and endosymbiotic bacteroids. From these hybridisation, experiments it is concluded that plasmid genes are strongly expressed in bacteroids and only weakly or not at all in bacteria. From the hybridisation of plasmid DNA with the cloned structural nif genes of Klebsiella pneumoniae it is shown that at least part of the nif genes are located on a plasmid.

  10. Isolation and characterization of a gene coding for a novel aspartate aminotransferase from Rhizobium meliloti.

    OpenAIRE

    Alfano, J. R.; Kahn, M. L.

    1993-01-01

    Aspartate aminotransferase (AAT) is an important enzyme in aspartate catabolism and biosynthesis and, by converting tricarboxylic acid cycle intermediates to amino acids, AAT is also significant in linking carbon metabolism with nitrogen metabolism. To examine the role of AAT in symbiotic nitrogen fixation further, plasmids encoding three different aminotransferases from Rhizobium meliloti 104A14 were isolated by complementation of an Escherichia coli auxotroph that lacks three aminotransfera...

  11. Hydroxylated ornithine lipids increase stress tolerance in Rhizobium tropici CIAT899

    OpenAIRE

    Vences-guzma?n, Miguel A?ngel; Guan, Ziqiang; Ormen?o-orrillo, Ernesto; Gonza?lez-silva, Napoleo?n; Lo?pez-lara, Isabel M.; Marti?nez-romero, Esperanza; Geiger, Otto; Sohlenkamp, Christian

    2011-01-01

    Ornithine lipids (OLs) are widespread among gram-negative bacteria. Their basic structure consists of a 3-hydroxy fatty acyl group attached in amide linkage to the ?-amino group of ornithine and a second fatty acyl group ester-linked to the 3-hydroxy position of the first fatty acid. OLs can be hydroxylated within the secondary fatty acyl moiety and this modification has been related to increased stress tolerance. Rhizobium tropici, a nodule-forming ?-proteobacterium known for its stress to...

  12. Distribution of Symbiotic Genotypes in Rhizobium leguminosarum biovar viciae Populations Isolated Directly from Soils

    OpenAIRE

    Louvrier, P.; Laguerre, G.; Amarger, N.

    1996-01-01

    The distribution of symbiotic (Sym) plasmid types across background genotypes was investigated in two field populations of Rhizobium leguminosarum biovar viciae isolated directly from soils. PCR-based methods were used to characterize the background genotypes and the Sym gene types. Identical Sym gene types were associated with a variable range of background genotypes, while the same background genotype could harbor distinct Sym gene types. Random distributions of Sym gene types in the backgr...

  13. Slow-growing Rhizobium japonicum comprises two highly divergent symbiotic types.

    OpenAIRE

    Stanley, J.; Brown, G. G.; Verma, D. P.

    1985-01-01

    We examined the interrelationships of the genomes of 10 slow-growing strains of Rhizobium japonicum to provide a foundation for molecular genetic studies of these agriculturally important endosymbiotic bacteria of commercial soybeans. The degree of base substitution in and around known symbiotic genes (nif and presumptive nod), constitutively expressed genes (glnA and recA), and two other cloned sequences was estimated from restriction site variation by using cloned DNAs as hybridization prob...

  14. Hypoosmotic adaptation in Rhizobium meliloti requires beta-(1----2)-glucan.

    OpenAIRE

    Dylan, T.; Helinski, D. R.; Ditta, G. S.

    1990-01-01

    beta-(1----2)-Glucan, an unusual cyclic oligosaccharide, can be isolated from the periplasm of bacteria belonging to the family Rhizobiaceae. Data presented here suggest that the periplasmic beta-(1----2)-glucan of Rhizobium meliloti plays a major role in osmotic adaptation. First, growth of R. meliloti in a low-osmolarity medium causes a large accumulation of periplasmic beta-(1----2)-glucan. Second, mutations in the ndv genes, which prevent this accumulation of beta-(1----2)-glucan, reduce ...

  15. Transformation of pWWO in Rhizobium leguminosarum DPT to Engineer Toluene Degrading Ability for Rhizoremediation

    OpenAIRE

    Goel, Garima; Pandey, Piyush; Sood, Anchal; Bisht, Sandeep; Maheshwari, D. K.; Sharma, G. D.

    2011-01-01

    Rhizoremediation of organic xenobiotics is based on interactions between plants and their associated micro-organisms. The present work was designed to engineer a bacterial system having toluene degradation ability along with plant growth promoting characteristics for effective rhizoremediation. pWWO harboring the genes responsible for toluene breakdown was isolated from Pseudomonas putida MTCC 979 and successfully transformed in Rhizobium DPT. This resulted in a bacterial strain (DPTT) which ...

  16. Coexistence of Burkholderia, Cupriavidus, and Rhizobium sp. Nodule Bacteria on two Mimosa spp. in Costa Rica

    OpenAIRE

    Barrett, Craig F.; Parker, Matthew A.

    2006-01-01

    rRNA gene sequencing and PCR assays indicated that 215 isolates of root nodule bacteria from two Mimosa species at three sites in Costa Rica belonged to the genera Burkholderia, Cupriavidus, and Rhizobium. This is the first report of Cupriavidus sp. nodule symbionts for Mimosa populations within their native geographic range in the neotropics. Burkholderia spp. predominated among samples from Mimosa pigra (86% of isolates), while there was a more even distribution of Cupriavidus, Burkholderia...

  17. Three Replicons of Rhizobium sp. Strain NGR234 Harbor Symbiotic Gene Sequences

    OpenAIRE

    Flores, Margarita; Mavingui, Patrick; Girard, Lourdes; Perret, Xavier; Broughton, William J.; Marti?nez-romero, Esperanza; Da?vila, Guillermo; Palacios, Rafael

    1998-01-01

    Rhizobium sp. strain NGR234 contains three replicons: the symbiotic plasmid or pNGR234a, a megaplasmid (pNGR234b), and the chromosome. Symbiotic gene sequences not present in pNGR234a were analyzed by hybridization. DNA sequences homologous to the genes fixLJKNOPQGHIS were found on the chromosome, while sequences homologous to nodPQ and exoBDFLK were found on pNGR234b.

  18. Specific phases of root hair attachment in the Rhizobium trifolii-clover symbiosis.

    OpenAIRE

    Dazzo, F. B.; Truchet, G. L.; Sherwood, J. E.; Hrabak, E. M.; Abe, M.; Pankratz, S. H.

    1984-01-01

    The time course and orientation of attachment of Rhizobium trifolii 0403 to white clover root hairs was examined in slide cultures by light and electron microscopy. Inocula were grown for 5 days on defined BIII agar medium and represented the large subpopulation of fully encapsulated single cells which uniformly bind the clover lectin trifoliin A. When 10(7) cells or more were added per seedling, bacteria attached within minutes, forming randomly oriented clumps at the root hair tips. Several...

  19. Effects of Heavy Metal from Polluted Soils on the Rhizobium Diversity

    Directory of Open Access Journals (Sweden)

    Georgiana PLOPEANU

    2011-05-01

    Full Text Available Heavy metals adversely influence microorganisms, affecting their growth, abundance, genetic diversity, nodulation ability and efficacy. The aim of this study was to isolate and characterize free-leaving Rhizobium from soil which were artificially polluted with Cu (100, 250, and 500 mg kg-1 soil, Zn (300, 700, and 1500 mg kg-1 soil and Pb (50, 250, and 1000 mg kg-1 soil, but also with a mixture of all these metals, and cultivated with red clover (Trifolium pratense L., and to compare them with bacteria isolated from similar type of soil, but unpolluted. Rhizobia from soil were isolated on YMA medium with or without bromothymol blue (0.00125% as a pH-change indicator and the morpho-physiological characteristics of the colonies were examined. The number of Rhizobium was estimated using the most probable number method. Compared to the control, a decrease of rhizobia number and an increase of the metal concentration were observed. Several decameric primers (Operon Technology type were used and a reduced polymorphism among isolated bacteria was observed. Moreover, significant differences were observed among these strains and the collection strains used as reference. Also, when primers nodCF/nodCI for detection of nod genes were used, several amplicons were obtained, different from the results obtained with similar strains isolated from unpolluted soil. These results suggest that the survival „price” of the Rhizobium in such polluted area was the alteration of some genes, including those involved in symbiosis and, probably, in nitrogen fixation.

  20. Effects of nano-ZnO on the agronomically relevant Rhizobium-legume symbiosis.

    Science.gov (United States)

    Huang, Yu Chu; Fan, Ruimei; Grusak, Michael A; Sherrier, Janine D; Huang, C P

    2014-11-01

    The impact of nano-ZnO (nZnO) on Rhizobium-legume symbiosis was studied with garden pea and its compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure of peas to nZnO had no impact on germination, but significantly affected root length. Chronic exposure of plant to nZnO impacted its development by decreasing the number of the first- and the second-order lateral roots, stem length, leaf surface area, and transpiration. The effect of nZnO dissolution on phytotoxicity was also examined. Results showed that Zn(2+) had negative impact on plant development. Exposure of R. leguminosarum bv. viciae 3841 to nZnO brought about morphological changes by rendering the microbial cells toward round shape and damaging the bacterial surface. Furthermore, the presence of nZnO in the rhizosphere affected root nodulation, delayed the onset of nitrogen fixation, and caused early senescence of nodules. Attachment of nanoparticles on the root surface and dissolution of Zn(2+) are important factors affecting the phytotocity of nZnO. Hence, the presence of nZnO in the environment is potentially hazardous to the Rhizobium-legume symbiosis system. PMID:25124056

  1. Genodiversity of dominant Rhizobium leguminosarum bv. Trifolii isolated from 11 types of soil in Serbia

    Directory of Open Access Journals (Sweden)

    Joši? Dragana

    2008-01-01

    Full Text Available Rhizobium leguminosarum bv. trifolii is microsymbiont Trifolium pratense and Trifolium repens, which are very important legumes in Serbia. The natural nodulating population of those bacteria was collected and estimated biodiversity distribution by monitoring dominant genotypes of these bacteria. The population of Rhizobium leguminosarum bv. trifolii were collected from 50 marked locations of 11 types of soil in Serbia. 437 natural isolates, rescued from nodules of Trifolium repens or Trifolium pratense, were analyzed by phenotypic approach. We obtained 156 different isolates on the basis of differences in their IAR - intrinsic antibiotic resistance (five antibiotics and HMT- heavy methal tolerance (five heavy metals. We investigated 56 dominant isolates with more than three differences in IAR-HMT patterns by REP-PCR and RAPD fingerprinting (AP10 and SPH 1 primers. The results showed genodiversity of dominant Rhizobium leguminosarum bv. trifolii field isolates and offered the possibility to assess their changes on marked locations during time and under different environmental conditions and geographical distribution.

  2. Effects of nano-TiO? on the agronomically-relevant Rhizobium-legume symbiosis.

    Science.gov (United States)

    Fan, Ruimei; Huang, Yu Chu; Grusak, Michael A; Huang, C P; Sherrier, D Janine

    2014-01-01

    The impact of nano-TiO? on Rhizobium-legume symbiosis was studied using garden peas and the compatible bacterial partner Rhizobium leguminosarum bv. viciae 3841. Exposure to nano-TiO? did not affect the germination of peas grown aseptically, nor did it impact the gross root structure. However, nano-TiO? exposure did impact plant development by decreasing the number of secondary lateral roots. Cultured R. leguminosarum bv. viciae 3841 was also impacted by exposure to nano-TiO?, resulting in morphological changes to the bacterial cells. Moreover, the interaction between these two organisms was disrupted by nano-TiO? exposure, such that root nodule development and the subsequent onset of nitrogen fixation were delayed. Further, the polysaccharide composition of the walls of infected cells of nodules was altered, suggesting that the exposure induced a systemic response in host plants. Therefore, nano-TiO? contamination in the environment is potentially hazardous to the Rhizobium-legume symbiosis system. PMID:23933452

  3. Comparative effectiveness of different Rhizobium sp. for improving growth and yield of maize (Zea mays L.

    Directory of Open Access Journals (Sweden)

    Ijaz Mehboob, Zahir Ahmad Zahir, Muhammad Arshad, Muhammad Khalid

    2012-05-01

    Full Text Available During the last couple of decades, it has been demonstrated that rhizobia can associate with roots of non-legumes also without forming true nodules, and can promote their growth by using one or more of the direct or indirect mechanisms of actions. This work examines the growth and yield responses of maize to inoculation with different species of rhizobia, isolated from the root nodules of chickpea (Cicer arietinum L., lentil (Lens culinaris M. and mung bean (Vigna radiata L. in pots and fields. Twenty isolates of rhizobia were isolated from root nodules each of mung bean, lentil and chickpea and were screened under axenic conditions. On the basis of their promising performance under axenic conditions, nine most efficient isolates (three from each legume host were selected, characterized and further evaluated for their growth promoting activities by conducting pot and field experiments. Results of pot experiment revealed that maximum increase in grain yield, 1000 grain weight, N, P and K uptake (up to 47.89, 54.52, 73.46, 84.66 and 59.19% by CRI28, respectively, over un-inoculated control was produced by the isolate of Mesorhizobium ciceri. Whereas, maximum improvement in rest of the parameters was caused by the isolates of Rhizobium phaseoli (i.e. fresh biomass, straw yield and root length up to 36.30% by A18, 25.46% by S6 and 81.89% by A18, respectively over un-inoculated control. Rhizobium leguminosarum isolates came out to be the least effective among the species tested. Similarly, all the selected isolates improved the growth and yield attributing parameters in fields as well but with varying capacity compared with un-inoculated control. The selected isolates of Mesorhizobium ciceri and Rhizobium phaseoli again remained superior compared to the isolates of Rhizobium leguminosarum under field conditions. The results of this study imply that rhizobium species had potential to promote growth and yield of maize but this technology should be employed after appropriate site specific investigations of particular rhizobial specie with respect to specific non-leguminous crop variety to get maximum benefit in terms of better growth and yield.

  4. Evaluation of Bean (Phaseolus vulgaris Seeds Inoculation with Rhizobium phaseoli and Plant Growth Promoting Rhizobacteria on Yield and Yield Components

    Directory of Open Access Journals (Sweden)

    M. Yadegari

    2008-01-01

    Full Text Available To study the effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR and Rhizobium, on yield and yield components of common bean (Phaseolus vulgaris L. cultivars was investigated in 2 consecutive years under field condition of plant growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains were used in this study. Common bean seeds of three cultivars were inoculated with Rhizobium singly or in a combination with PGPR to evaluate their effect on growth characters. A significant variation of plant growth in response to inoculation with Rhizobium strains was observed. Treatment with PGPR significantly increased pod per plant, number of seeds per pod, weight of 100 seed, weight of seeds per plant, weight of pods per plant, total dry matter in R6 as well as seed yield and protein content. Co-inoculation with Rhizobium and PGPR demonstrated a significant increase in the yield and yield components. The results showed that all treatments of bacteria increased yield; however, strains Rb-133 with Pseudomonas fluorescens P-93 gave the highest seed yield, number of pods per plant, weight of 100 seed, seed protein yield, number seed per pod, seed protein yield.

  5. Effect of Rhizobial Management upon Rhizobial Population, Nodulation and Growth of Yard Long Beans (Vigna sesquipedalis L. A New Approach to Maximize Benefits from Rhizobium

    Directory of Open Access Journals (Sweden)

    W. Sinsiri

    2002-01-01

    Full Text Available The work aimed to investigate some benefits derived from Rhizobium technology. The results showed that management methods in retaining native Rhizobium being tested had a tremendous effect on population management, i.e. native Rhizobium could be maintained. However, Rhizobium has preferential level of selectivity to host. KKU 25 yard long bean plants had the highest level of rhizobia population followed by white seeded cultivar at day 30 and thereafter the amount of rhizobia population declined with time in all subplots whilst no population was detected from the control subplots. Native Rhizobium had significant potentiality for growth of yard long bean crop plants by supplying some certain amount of nitrogen being fixed from the atmosphere and the growth of yard long bean crop plants was similar to that of the control subplots that received nitrogen from chemical nitrogen fertilizer.

  6. The role of vesicular-arbuscular mycorrhiza in N2-fixed by legume-Rhizobium systems in phosphate-fixing agricultural soils

    International Nuclear Information System (INIS)

    The scarcity of available phosphate in many soils is a critical limiting factor in legume-Rhizobium-systems because it affects not only plant growth but nodulation and N2-fixation by the micro-symbiont. Hence, VA mycorrhizas, which are widespread in legumes, play an important role in the development of such crops and are thus of great interest for food production in the biosphere. This paper discusses the work developed in this laboratory in relation to the significance of VA mycorrhiza in N2-fixation within two legume-Rhizobium-systems: Medicago sativa (alfalfa)-Rhizobium meliloti and Hedysarum coronarium (sulla)-Rhizobium sp.. Several experiments have been carried out to study the interactions between natural and introduced VA endophytes and Rhizobium, and soluble phosphate fertilizer on growth, nodulation and N-uptake of the two test legumes in natural (unsterilized) agricultural soils. The tests were conducted under both pot and field conditions. (author)

  7. Random amplified polymorphic DNA analysis of effective Rhizobium sp. associated with beans cultivated in brazilian cerrado soils Caracterização, via RAPD, de estirpes efetivas de Rhizobium sp associadas ao feijoeiro cultivado em solos de cerrado no Brasil

    Directory of Open Access Journals (Sweden)

    Isnia Aparecida de Oliveira

    2000-03-01

    Full Text Available Efficient bean nodulating Rhizobium strains, isolated from different Brazilian cerrado soils, were characterized by RAPD. This study showed great genetic heterogeneity among R. tropici and R. leguminosarum bv. phaseoli strains and allowed the constitution of genetic clusters, besides indicating the most suitable primers for this characterization. The groups of genetically distinct strains can be used in competitiveness studies to select appropriate Rhizobium strains for bean inoculation in cerrado soils.Estirpes de Rhizobium eficientes na nodulação do feijoeiro, isoladas de diferentes solos da região do cultivo dessa leguminosa nos cerrados brasileiros, foram caracterizadas via RAPD. Esse estudo mostrou grande heterogeneidade genética entre as estirpes de R. tropici e R. leguminosarum bv. phaseoli testadas e permitiu a definição de grupos genéticos, além de indicar os "primers" mais adequados para essa caracterização. Os grupos de estirpes geneticamente distintas podem ser usados em estudos de competitividade, importantes para obtenção de resultados positivos na inoculação dessa leguminosa em solos de cerrado.

  8. Influence of a carbamate pesticide on growth, respiration (14C)-carbon metabolism and symbiosis of a Rhizobium sp

    International Nuclear Information System (INIS)

    Addition of aldicarb (2 methyl-2(methyl thio) propionaldehyde-O-methyl carbamoyl oxime) in the growth medium enhanced the growth of Rhizobium sp. (cowpea group) at 2ppm level while an inhibition was observed at the normal (5 ppm) and higher (10 ppm) concentrations. Respiration of the cells was also inhibited by 5 and 10 ppm levels of the chemical eventhough a stimulation was observed at 2 ppm (lower) concentration. The insecticide, when incorporated at 5 and 10 ppm levels in the medium increased the 14C-glucose incorporation and considerably altered the assimilation of the radioactive carbon in different fractions of rhizobium cells. Soil application of this insecticide (Temik 10 G) reduced the number of nodules formed and the total nitrogen content in cowpea plants inoculated with the Rhizobium sp. but enhanced the dry matter production of cowpea plants. (Auth.)

  9. Diversity of Rhizobium-Phaseolus vulgaris symbiosis: Overview and perspectives

    International Nuclear Information System (INIS)

    Common bean (Phaseolus vulgaris) has become a cosmopolitan crop, but was originally domesticated in the Americas and has been grown in Latin America for several thousand years. Consequently an enormous diversity of bean nodulating bacteria have developed and in the centers of origin the predominant species in bean nodules is R. etli. In some areas of Latin America, inoculation, which normally promotes nodulation and nitrogen fixation is hampered by the prevalence of native strains. Many other species in addition to R. etli have been found in bean nodules in regions where bean has been introduced. Some of these species such as R. leguminosarum bv. phaseoli, R. gallicum bv. phaseoli and R. giardinii bv. phaseoli might have arisen by acquiring the phaseoli plasmid from R. etli. Others, like R. trap id, are well adapted to acid soils and high temperatures and are good inoculants for bean under these conditions. The large number of rhizobia species capable of nodulating bean supports that bean is a promiscuous host and a diversity of bean-rhizobia interactions exists. Large ranges of dinitrogen fixing capabilities have been documented among bean cultivars and commercial beans have the lowest values among legume crops. Knowledge on bean symbiosis is still incipient but could help to improve bean biological nitrogen fixation. (author)

  10. Symbiotic effectiveness and ecological characterization of indigenous Rhizobium loti populations in Uruguay Eficiência simbiótica e caracterização ecológica de uma população nativa de Rhizobium loti no Uruguai

    Directory of Open Access Journals (Sweden)

    Amalia Baraibar

    1999-06-01

    Full Text Available The objectives of this work were to describe the distribution, density and seasonal variation of the indigenous populations of Rhizobium loti in different Uruguayan soils and to determine the symbiotic effectiveness and stress tolerance factors of different isolates, both with the aim of obtaining selected strains to re-introduce as inoculants in Lotus pastures. R. loti was present in ten soils studied and their densities varied from year to year and within each soil. All the isolates nodulated Lotus corniculatus effectively. The nodules in Lotus pedunculatus and Lotus subbiflorus were small, red on the surface and ineffective in nitrogen fixation. The study of 50 isolates from the ten soils showed high variability in their symbiotic efficiency and tolerance to pH. The indigenous population was acid tolerant in culture medium (pH 4.5, 83% of them could grow at pH 4.5 in 3 days. This work showed that there was a great diversity between the strains of R. loti isolated from Uruguayan soils and supports the importance of selecting among them the most efficient and resistant strains to be included in the inoculants.Os objetivos deste trabalho foram descrever a distribuição, densidade e variação sazonal de populações nativas de Rhizobium loti em diferentes solos uruguaios, e determinar a eficiência simbiótica e os fatores de tolerância a estresse de diversos isolados, tendo em vista a obtenção de cepas a serem reintroduzidas como inoculantes em pastagens de Lotus. Rhizobium loti estava presente em dez solos estudados, e suas densidades variavam de ano para ano e em cada solo. Todos os isolados nodularam efetivamente o Lotus corniculatus. Os nódulos no Lotus pedunculatus e no Lotus subbiflorus eram pequenos, vermelhos na superfície, e ineficazes na fixação de N. O estudo de 50 isolados dos dez solos mostraram alta variabilidade na sua eficiência simbiótica, e alta tolerância ao pH. A população nativa era tolerante à acidez em meio de cultura (pH 4,5; 83% dela pode crescer em pH 4,5 em três dias. O presente trabalho mostrou que há grande diversidade entre as cepas de R. loti isoladas de solos uruguaios, e acentua a importância de se selecionar entre elas as mais eficientes e resistentes, para serem incluídas como inoculantes.

  11. Isotopic discrimination of nitrogen associated with biological nitrogen fixation on the system Rhizobium versus beans (Phaseolus vulgaris L.)

    International Nuclear Information System (INIS)

    Two experiments were carried out in the greenhouse using a complete randomized experimental design. The first experiments was designed to assess the effect of three bean cultivars, inoculated with a mixture of efficient Rhizobium strains on the isotopic N discrimination at four development stages of beans plants. The second experiment was carried out to verify if there is any discrimination caused by the Rhizobium strains used. The plants of both experiments were grown in a N free medium, with 5 replicates. At the harvesting, ?N-15% was determined in the following parts of the bean plants: nodules, roots, shoots, cotyledons and pods. (author)

  12. Sequence and distribution of IS1312: evidence for horizontal DNA transfer from Rhizobium meliloti to Agrobacterium tumefaciens.

    OpenAIRE

    Deng, W.; Gordon, M. P.; Nester, E. W.

    1995-01-01

    Two novel insertion sequences, IS1312 and IS1313, were found in pTiBo542, the Ti plasmid of Agrobacterium tumefaciens strains Bo542 and A281. Nucleotide sequencing and Southern hybridization revealed that IS1312 and IS1313 are homologous to Rhizobium meliloti ISRm1 and ISRm2, respectively. IS1312, ISRm1, and another Agrobacterium insertion sequence, IS426, belong to the same IS3 family of insertion sequences; however, IS1312 is more closely related to the Rhizobium ISRm1 than it is to the Agr...

  13. Rhizobium Meliloti Genes Involved in Sulfate Activation: The Two Copies of Nodpq and a New Locus, Saa

    OpenAIRE

    Schwedock, J. S.; Long, S. R.

    1992-01-01

    The nitrogen-fixing symbiont Rhizobium meliloti establishes nodules on leguminous host plants. Nodulation (nod) genes used for this process are located in a cluster on the pSym-a megaplasmid of R. meliloti. These genes include nodP and nodQ (here termed nodPQ), which encode ATP sulfurylase and APS kinase, enzymes that catalyze the conversion of ATP and SO(4)(2-) into the activated sulfate form 3'-phosphoadenosine 5'-phosphosulfate (PAPS), an intermediate in cysteine synthesis. In Rhizobium, P...

  14. Expression of the nodulation gene nodA in Rhizobium meliloti and localization of the gene product in the cytosol

    OpenAIRE

    Schmidt, Ju?rgen; John, Michael; Wieneke, Ursula; Kru?ssmann, Heinz-dieter; Schell, Jeff

    1986-01-01

    The nodA gene of Rhizobium meliloti encodes a 21.8-kDa protein, which is conserved in several Rhizobium species. We overproduced the nodA protein as a fusion product with a portion of the ? cI repressor in Escherichia coli. This fusion protein was purified from inclusion bodies by gel and hydroxyapatite chromatography in the presence of NaDodSO4. Monospecific polyclonal antibodies against the hybrid protein were used to detect the nodA protein in the cytosol of E. coli and R. meliloti by imm...

  15. Isolation of Rhizobium leguminosarum (biovar trifolii) Strains from Ethiopian Soils and Symbiotic Effectiveness on African Annual Clover Species.

    Science.gov (United States)

    Friedericks, J B; Hagedorn, C; Vanscoyoc, S W

    1990-04-01

    Strains of Rhizobium leguminosarum (biovar trifolii) isolated from two Ethiopian soils or obtained from a commercial source were evaluated for symbiotic effectiveness on five African annual clover species. Numerous Rhizobium trifolii strains that exhibited varying levels of symbiotic effectiveness were isolated from both soils (a nitosol and a vertisol), and it was possible to identify strains that were highly effective for each clover species. The soil isolates were, as a group, superior to the strains from the commercial source. Several R. trifolii strains were found to be effective on more than one clover species, and there appeared to be at least two and possibly three distinct cross-inoculation effectiveness groups. PMID:16348157

  16. Toxicity assessment of herbicides quizalafop-p-ethyl and clodinafop towards Rhizobium pea symbiosis.

    Science.gov (United States)

    Ahemad, Munees; Khan, Mohammad Saghir

    2009-06-01

    In modern conventional agriculture, herbicides are frequently used to prevent yield losses due to weeds. Herbicides also affect negatively the productivity of legumes. With these considerations, we evaluated the effects of soil applications of different concentrations of quizalafop-p-ethyl and clodinafop on the performance of Rhizobium inoculated pea, grown in clay pots. In this study, the concentration of herbicides higher than the recommended rates of quizalafop-p-ethyl and clodinafop adversely affected the dry matter accumulation, symbiotic properties, grain yield and nutrient status of pea plants. Toxicity of quizalafop-p-ethyl and clodinafop to pea plants increased progressively with increase in rates of herbicides. Of the two herbicides, quizalafop-p-ethyl was more toxic than clodinafop. In contrast, when herbicide tolerant Rhizobium strain MRP1 was also used with herbicide, it increased the measured parameters at all concentrations. A maximum increase of 11%, 17%, 46%, 33%, 21% and 7% in the root N, shoot N, root P, shoot P, seed yield and seed protein, respectively, was observed when MRP1 was used with 120 microg quizalafop-p-ethyl kg(-1) soil while with 1,200 microg clodinafop kg(-1) soil it increased the root N, shoot N, root P, shoot P, seed yield and seed protein by 20%, 9%, 56%, 56%, 29% and 7%, respectively, compared with the un-inoculated but herbicide treated control. This study suggested that the toxic effects of herbicides on pea plants could be attenuated by applying growth promoting herbicide tolerant strain of Rhizobium under herbicide stressed soil environment. PMID:19290455

  17. Associação de Rhizobium sp. a duas leguminosas na tolerância à atrazina / Association of Rhizobium sp. with two legumes on atrazine tolerance

    Scientific Electronic Library Online (English)

    Danielle, Camargo; Kelly Lopes, Bispo; Luciane, Sene.

    2011-08-01

    Full Text Available A associação de bactérias a plantas tem sido estudada como uma possível tecnologia emergente, para fitorremediação de contaminantes, entre eles os herbicidas, que, por sua recalcitrância, ameaçam a qualidade do ambiente. O objetivo deste trabalho foi verificar a tolerância de mucuna-anã (Stizolobium [...] deeringianum Bort) e mucuna-preta (Stizolobium aterrimum Piper & Tracy), inoculadas e não inoculadas com Rhizobium sp., ao herbicida atrazina. Os tratamentos foram: plantas com inoculante + 0,1 g/m², 0,2 g/m² atrazina e sem atrazina (T1, T2 e T3, respectivamente), sem inoculante + 0,1 g/m², 0,2 g/m² atrazina e sem atrazina (T4, T5 e T6, respectivamente). O delineamento experimental utilizado foi inteiramente casualizado, com três repetições. Foram avaliados germinação, sobrevivência, número de nódulos, altura, biomassa verde, biomassa seca da parte aérea, após o crescimento das plantas por 50 dias em casa de vegetação. Nos tratamentos com inoculante, avaliou-se a porcentagem de germinação de plantas bioindicadoras (Bidens pilosa L.). Mucuna-preta e mucuna-anã demonstraram maior tolerância ao herbicida quando associadas ao Rhizobium. Os valores de sobrevivência de mucuna-preta, nas doses 0,1 e 0,2 g/m² de atrazina (T1 e T2), foram de 34 a 24% superiores aos observados nas mesmas doses, mas sem o inoculante (T4 e T5). Para mucuna-anã, T1 e T2 foram de 17 e 8% superiores a T4 e T5, respectivamente. As alturas médias de mucuna-anã em T1, T2 e T3 foram mais elevadas que em T4, T5 e T6, reforçando a importância do simbionte à resistência ao herbicida. Os resultados encontrados para as variáveis altura, biomassa verde e seca para mucuna-preta não apresentaram diferença estatística entre os tratamentos com e sem inoculante, mostrando uma resistência natural à atrazina e a possibilidade de atuar como planta remediadora. A germinação de B. pilosa indica uma possível degradação da atrazina no solo com ambas as espécies de mucunas inoculadas com Rhizobium sp. Abstract in english The association of bacteria with plants has been studied as a possible emerging technology for phytoremediation of contaminants, including herbicides, which pose as a threatening to environmental quality due to their recalcitrance. The aim of this study was to assess the tolerance of dwarf mucuna (S [...] tizolobium deeringianum Bort) and black mucuna (Stizolobium aterrimum Piper & Tracy) inoculated and uninoculated with Rhizobium to the herbicide atrazine. The treatments were: plants with inoculant + 0.1 g/m², 0.2 g/m² atrazine, and without atrazine (T1, T2 and T3, respectively), plants without inoculant + 0.1 g/m², 0.2 g/m² atrazine and without atrazine (T4, T5 and T6, respectively). The experiment was arranged in a completely randomized design, with three replications. Plants were grown in a greenhouse for 50 days and the variables germination, survival, number of nodules, height, green/dry biomass of the aerial part were evaluated. In the treatments with inoculants, the germination percentage of bioindicator plants (Bidens pilosa L.) was also evaluated. Black mucuna and dwarf mucuna showed greater tolerance to the herbicide when associated with Rhizobium. The survival rates of black mucuna at the doses 0.1 and 0.2 g/m² atrazine (T1 and T2) were 34 and 24% higher than those observed at the same doses, but without the inoculant (T4 and T5). For dwarf mucuna, T1 and T2 were 17 and 8% higher than T4 and T5, respectively. The average heights of dwarf mucuna in T1, T2 and T3 were higher than in T4, T5 and T6, reinforcing the importance of the symbiont to the herbicide resistance. The results found for the variables height, green and dry biomass for black mucuna were not significantly different among the treatments with and without inoculant, showing a natural resistance to atrazine and the possibility of acting as a remediation plant. The germination of B. pilosa indicates a possible degradation of atrazine in the soil by both mucuna species inoculated with Rhizobium sp.

  18. Mutagenesis in pea (Pisum sativum L.) as a tool for studying plant Rhizobium symbiosis

    International Nuclear Information System (INIS)

    Pea mutants for symbiotic characteristics were obtained by treating seeds with ethylmethanesulphonate. They consisted of 15 mutants with no nodules (nod-), 10 mutants with inefficient nodules (nod+fix-) and four hypernodulating mutants (nod++nts) that also express a nitrate tolerant character of nodulation and fixation; 6, 7 and 1 loci, respectively, were identified. Strain specificity was found between a (nod+fix-) mutant and two Rhizobium leguminosarum strains. These isogenic mutants were also used in an agronomic study of nitrogen nutrition and in a cytological study to determine the stage at which abortion of symbiosis occurs. (author). 16 refs

  19. Effects of Heavy Metal from Polluted Soils on the Rhizobium Diversity

    OpenAIRE

    Plopeanu, Georgiana; Dus?a, Mirela; Voaides?, Ca?ta?lina; Stan, Vasilica; Cornea, Ca?lina Petrut?a; Gament, Eugenia

    2011-01-01

    Heavy metals adversely influence microorganisms, affecting their growth, abundance, genetic diversity, nodulation ability and efficacy. The aim of this study was to isolate and characterize free-leaving Rhizobium from soil which were artificially polluted with Cu (100, 250, and 500 mg kg-1 soil), Zn (300, 700, and 1500 mg kg-1 soil) and Pb (50, 250, and 1000 mg kg-1 soil), but also with a mixture of all these metals, and cultivated with red clover (Trifolium pratense L.), and to compare them ...

  20. Rhizobium trifolii 0403 Is Capable of Growth in the Absence of Combined Nitrogen †

    OpenAIRE

    Urban, James E.; Davis, Lawrence C.; Brown, Susan J.

    1986-01-01

    Rhizobium trifolii 0403 was treated with 16.6 mM succinate and other nutrients and thereby induced to grow in nitrogen-free medium. The organism grew microaerophilically on either semisolid or liquid medium, fixing atmospheric nitrogen to meet metabolic needs. Nitrogen fixation was measured via 15N incorporation (18% 15N enrichment in 1.5 doublings) and acetylene reduction. Nitrogen-fixing cells had a Km for acetylene of 0.07 atm (ca. 7.09 kPa), required about 3% oxygen for optimum growth in ...

  1. Symbiotic Autoregulation of nifA Expression in Rhizobium leguminosarum bv. viciae

    OpenAIRE

    Marti?nez, Marta; Palacios, Jose? M.; Imperial, Juan; Ruiz-argu?eso, Toma?s

    2004-01-01

    NifA is the general transcriptional activator of nitrogen fixation genes in diazotrophic bacteria. In Rhizobium leguminosarum bv. viciae UPM791, the nifA gene is part of a gene cluster (orf71 orf79 fixW orf5 fixABCX nifAB) separated by 896 bp from an upstream and divergent truncated duplication of nifH (?nifH). Symbiotic expression analysis of genomic nifA::lacZ fusions revealed that in strain UPM791 nifA is expressed mainly from a ?54-dependent promoter (PnifA1) located upstream of orf71. ...

  2. Regulation of Rhizobium nitrogen fixation by the unadenylylated glutamine synthetase I system

    OpenAIRE

    Ludwig, Robert A.

    1980-01-01

    Rhizobium sp. 32H1 glutamine auxotrophs have a complex phenotype: a highly adenylylated glutamine synthetase [GS; L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] I and an undetectable GS II (GS II-). They are defective in the adenylylation cascade system for GS I. Prototrophic revertants are of two classes: those (3204 type) which retain the adenylylated GS I phenotype but become GS II+, and those (3205 type) which acquire a constitutive unadenylylated GS I but remain GS II-. Like the p...

  3. Isolation of a Rhizobium phaseoli cytochrome mutant with enhanced respiration and symbiotic nitrogen fixation.

    OpenAIRE

    Sobero?n, M.; Williams, H. D.; Poole, R. K.; Escamilla, E.

    1989-01-01

    Cultured cells of a Rhizobium phaseoli wild-type strain (CE2) possess b-type and c-type cytochromes and two terminal oxidases: cytochromes o and aa3. Cytochrome aa3 was partially expressed when CE2 cells were grown on minimal medium, during symbiosis, and in well-aerated liquid cultures in a complex medium (PY2). Two cytochrome mutants of R. phaseoli were obtained and characterized. A Tn5-mob-induced mutant, CFN4201, expressed diminished amounts of b-type and c-type cytochromes, showed an enh...

  4. Sym plasmid transfer to various symbiotic mutants of Rhizobium trifolii, R. leguminosarum, and R. meliloti.

    OpenAIRE

    Djordjevic, M. A.; Zurkowski, W.; Shine, J.; Rolfe, B. G.

    1983-01-01

    Two self-transmissible Sym(biosis) plasmids, one encoding pea-specific nodulation and nitrogen-fixation functions (plasmid pJB5JI) and the other encoding clover-specific nodulation and nitrogen-fixation functions (plasmid pBR1AN) were used to determine whether the symbiotic genes encoded on these plasmids are expressed in various members of the Rhizobiaceae. The host specificity of Rhizobium trifolii and R. leguminosarum Sym plasmid-cured strains could be directly determined by the transfer t...

  5. Immunogold localization of the NodC and NodA proteins of Rhizobium meliloti.

    OpenAIRE

    Johnson, D.; Roth, L. E.; Stacey, G.

    1989-01-01

    Monospecific, polyclonal antibodies to the nodC and nodA gene products of Rhizobium meliloti were used in combination with immunogold labeling and transmission electron microscopy to localize the NodC and NodA proteins in cultures of R. meliloti. Both NodC and NodA were detected in the cytoplasm and cell envelope in thin sections of free-living rhizobia treated with luteolin, a known inducer of nod gene expression; however, only NodC was detected on cell surfaces when immunolabeling was perfo...

  6. Involvement of Rhizobium leguminosarum nodulation genes in gene expression in pea root hairs.

    OpenAIRE

    Gloudemans, T.; Bhuvaneswari, T. V.; Moerman, M.; Brussel, T.; Kammen, A.; Bisseling, T.

    1989-01-01

    The mRNA population in pea root hairs was characterized by means of in vitro translation of total root hair RNA followed by 2-dimensional gel electrophoresis of the translation products. Root hairs contain several mRNAs not detectable in total RNA preparations from roots. Most of these root hair-specific mRNAs occur in elongating root hairs at higher levels than in mature root hairs. The expression of some genes in pea root hairs is typically affected by inoculation with Rhizobium leguminosar...

  7. Induction of Rhizobium meliloti nodC expression by plant exudate requires nodD.

    OpenAIRE

    Mulligan, J. T.; Long, S. R.

    1985-01-01

    The soil bacterium Rhizobium meliloti invades and establishes a symbiosis with host plants such as alfalfa. Bacterial nodulation (nod) genes are required for this invasion, but their mechanism of action and the timing of their expression are not known. We have used translational lacZ fusions to monitor expression of nodD and nodC, which are located in the cluster of four nod genes on the R. meliloti megaplasmid (pSym). nodD is expressed at comparable levels by broth-grown bacterial cells and ...

  8. Characterization of the lipopolysaccharide from a Rhizobium phaseoli mutant that is defective in infection thread development.

    OpenAIRE

    Carlson, R. W.; Kalembasa, S.; Turowski, D.; Pachori, P.; Noel, K. D.

    1987-01-01

    The lipopolysaccharide (LPS) from a Rhizobium phaseoli mutant, CE109, was isolated and compared with that of its wild-type parent, CE3. A previous report has shown that the mutant is defective in infection thread development, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that it has an altered LPS (K. D. Noel, K. A. VandenBosch, and B. Kulpaca, J. Bacteriol. 168:1392-1462, 1986). Mild acid hydrolysis of the CE3 LPS released a polysaccharide and an oligosaccharide, PS1 an...

  9. Physiological distinctions of pea symbiotic mutants with various nodulation level under inoculation by Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Akimova G. P.

    2012-11-01

    Full Text Available The study was focused on morphological and physiological peculiarities of pea plants with various nodulation ability under the infection by Rhizobium leguminosarum. Microscopic studies identified distinct features in formation of root nodules in different pea mutants. We revealed differences in the content of indole-acetic acid (IAA in mutants in the root zones differing by sensibility to R. leguminosarum. It was concluded that hormonal system of plants plays an important role in control of nodulation process, and emergence of mutations inducing disturbance of nodule-forming ability apparently depends on root hormonal status, in particular, IAA concentration ensuring both formation of nodule meristem and further organogenesis of the nodule.

  10. Environmental Factors Influencing Numbers of Rhizobium leguminosarum biovar trifolii and Its Bacteriophages in Two Field Soils

    OpenAIRE

    Lawson, Kerrie A.; Barnet, Yvonne M.; Mcgilchrist, Clyde A.

    1987-01-01

    Fluctuations in numbers of Rhizobium leguminosarum biovar trifolii and its bacteriophages in two fields with different soil types were followed during a 17-month period in 1981 and 1982. Mean levels of both phage and rhizobia varied significantly (P < 0.05) on different occasions, with rhizobial levels varying from 1.6 × 102 to 2.0 × 104 cell per g of soil and phage from 0 to 1.7 × 104 PFU/g of soil. Multivariate regression analysis showed rhizobial levels to be significantly and positivel...

  11. Effects of microgravity on the binding of acetylsalicylic acid by Rhizobium leguminosarum bv. trifolii

    Science.gov (United States)

    Urban, James E.; Gerren, Richard; Zoelle, Jeffery

    1995-07-01

    Bacteroids can be induced in vitro by treating growing Rhizobium leguminosarum bv. trifolii with succinic acid or succinic acid structural analogs like acetylsalicylic acid. Quantitating bacteroid induction by measuring acetylsalicylic binding under normal (1 g) conditions showed two forms of binding to occur. In one form of binding cells immediately bound comparatively high levels of acetylsalicylic acid, but the binding was quickly reversed. The second form of binding increased with time by first-order kinetics, and reached saturation in 40 s. Similar experiments performed in the microgravity environment aboard the NASA 930 aircraft showed only one form of binding and total acetylsalicylic acid bound was 32% higher than at 1 g.

  12. Purification of Rhizobium leguminosarum HypB, a nickel-binding protein required for hydrogenase synthesis.

    OpenAIRE

    Rey, L.; Imperial, J.; Palacios, J. M.; Ruiz-argu?eso, T.

    1994-01-01

    The products of the Rhizobium leguminosarum hyp gene cluster are necessary for synthesis of a functional uptake [NiFe] hydrogenase system in symbiosis with pea plants, and at least for HypB and HypF, a role in hydrogenase-specific nickel metabolism has been postulated (L. Rey, J. Murillo, Y. Hernando, E. Hidalgo, E. Cabrera, J. Imperial, and T. Ruiz-Argüeso, Mol. Microbiol. 8:471-481, 1993). The R. leguminosarum hypB gene product has been overexpressed in Escherichia coli and purified by imm...

  13. Parallel variation in isoenzyme and nitrogen fixation markers in a Rhizobium population

    DEFF Research Database (Denmark)

    Engvild, K.C.; Jensen, E.S.

    1990-01-01

    Twenty isolates of Rhizobium leguminosarum bv. viceae were isolated at random from one field and examined for symbiotic plasmid fragment length polymorphisms and for isoenzyme patterns. The latter are most probably chromosome markers. With one exception both methods separated the isolates into the same 13 different groups. The largest group was represented 7 times according to isoenzymes and 8 times according to RFLP. This fixed non-random association of plasmid and chromosomal genotypes is consistent with a clonal population structure; it indicates limited exchange of plasmids under natural conditions. Seventeen isolates of 11 groups were highly effective and 2 isolates in one group almost ineffective.

  14. Production of Rhizobium Inoculants for Lupinus nootkatensis on Nutrient-Supplemented Pumice

    OpenAIRE

    Einarsson, Sigurbjorn; Gudmundsson, Jon; Sverrisson, Halldor; Kristjansson, Jakob K.; Runolfsson, Sveinn

    1993-01-01

    The use of the legume Lupinus nootkatensis as a pioneer plant to fight soil erosion and to reclaim eroded soils in Iceland has been under development for a few years. Production of a robust, low-cost bacterial inoculant was therefore a prerequisite for the extended use of this plant. Volcanic pumice is a naturally expanded mineral which is available in vast amounts in Iceland. It was tested as a carrier for solid fermentation of Rhizobium lupini. Nutrient-supplemented pumice containing a smal...

  15. Purification and Characterization of an ?-Glucosidase from Rhizobium sp. (Robinia pseudoacacia L.) Strain USDA 4280

    OpenAIRE

    Berthelot, Karine; Delmotte, Francis M.

    1999-01-01

    A novel ?-glucosidase with an apparent subunit mass of 59 ± 0.5 kDa was purified from protein extracts of Rhizobium sp. strain USDA 4280, a nodulating strain of black locust (Robinia pseudoacacia L), and characterized. After purification to homogeneity (475-fold; yield, 18%) by ammonium sulfate precipitation, cation-exchange chromatography, hydrophobic chromatography, dye chromatography, and gel filtration, this enzyme had a pI of 4.75 ± 0.05. The enzyme activity was optimal at pH 6.0 to 6...

  16. Effect of Naturally Occurring nif Reiterations on Symbiotic Effectiveness in Rhizobium phaseoli

    OpenAIRE

    Romero, David; Singleton, Paul W.; Segovia, Lorenzo; Morett, Enrique; Bohlool, B. Ben; Palacios, Rafael; Da?vila, Guillermo

    1988-01-01

    Most naturally occurring strains of Rhizobium phaseoli possess reiteration of the nif genes. Three regions contain nitrogenase structural genes in strain CFN42. Two of these regions (a and b) have copies of nifH, nifD, and nifK, whereas the third region (c) contains only nifH. Strains containing mutations in either nif region a or nif region b had significantly diminished symbiotic effectiveness compared with the wild-type strain on the basis of nodule mass, total nitrogenase activity per pla...

  17. Conservation of structure and location of Rhizobium meliloti and Klebsiella pneumoniae nifB genes.

    OpenAIRE

    Buikema, W. J.; Klingensmith, J. A.; Gibbons, S. L.; Ausubel, F. M.

    1987-01-01

    Using transposon Tn5-mediated mutagenesis, an essential Rhizobium meliloti nitrogen fixation (nif) gene was identified and located directly downstream of the regulatory gene nifA. Maxicell and DNA sequence analysis demonstrated that the new gene is transcribed in the same direction as nifA and codes for a 54-kilodalton protein. In Klebsiella pneumoniae, the nifBQ operon is located directly downstream of a gene which is structurally and functionally homologous to the R. meliloti nifA gene. The...

  18. Excessive excretion of cyclic beta-(1,2)-glucan by Rhizobium trifolii TA-1.

    OpenAIRE

    Breedveld, M. W.; Zevenhuizen, L. P.; Zehnder, A. J.

    1990-01-01

    At 25 degrees C, the optimal temperature for growth of Rhizobium trifolii TA-1, extracellular and capsular polysaccharide (EPS and CPS) were the main carbohydrate products synthesized in mannitol-rich medium (10 g of mannitol and 1 g of glutamic acid per liter). In the same medium at 33 degrees C, EPS and CPS production was inhibited, and up to 3.9 g of cyclic beta-(1,2)-glucan was produced during an incubation period of 20 days with a total biomass of 0.55 g of protein. In a medium containin...

  19. Two Host-Inducible Genes of Rhizobium fredii and Characterization of the Inducing Compound

    OpenAIRE

    Sadowsky, M. J.; Olson, E. R.; Foster, V. E.; Kosslak, R. M.; Verma, D. P.

    1988-01-01

    Random transcription fusions with Mu d1(Kan lac) generated three mutants in Rhizobium fredii (strain USDA 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants Glycine max, Phaseolus vulgaris, and Vigna ungliculata. Two genes were isolated from a library of total plasmid DNA of one of the mutants, 3F1. These genes, present in tandem on a 4.2-kilobase HindIII fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the Rhizobi...

  20. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp

    International Nuclear Information System (INIS)

    The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPSRT) and Mesorhizobium sp (EPSMR) are acidic heteropolysaccharide composed mainly of glucose and galactose in a molar ratio of 4:1 and 5:1 respectively, with traces of mannose (? 1%). Chemical analysis showed the presence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPSRT and EPSMR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, 1H and 13C-NMR. (author)

  1. Rhizobium leguminosarum Biovar viciae Symbiotic Hydrogenase Activity and Processing Are Limited by the Level of Nickel in Agricultural Soils

    OpenAIRE

    Ureta, Ana-claudia; Imperial, Juan; Ruiz-argu?eso, Toma?s; Palacios, Jose M.

    2005-01-01

    Analysis of levels of hydrogenase processing and activity in Rhizobium leguminosarum biovar viciae bacteroids from pea (Pisum sativum) plants showed that the oxidation of nitrogenase-evolved hydrogen is limited by the availability of nickel in agricultural soils. This limitation was overcome by using an inoculant strain engineered for higher hydrogenase expression.

  2. The acetyl substituent of succinoglycan is not necessary for alfalfa nodule invasion by Rhizobium meliloti Rm1021.

    OpenAIRE

    Reuber, T. L.; Walker, G. C.

    1993-01-01

    Rhizobium meliloti Rm1021 requires a Calcofluor-binding exopolysaccharide, termed succinoglycan or EPS I, to invade alfalfa nodules. We have determined that a strain carrying a mutation in the exoZ locus produces succinoglycan that lacks the acetyl substituent. The exoZ mutant nodules alfalfa normally.

  3. Effectiveness and competing capacity of native Rhizobium strains evaluated in IX Region soils

    International Nuclear Information System (INIS)

    Symbiotic nitrogen fixation in legumes reaches its optimum when the host plants are nodulated by highly competitive and effective Rhizobium strains. With the purpose of assessing competition and nitrogen fixing capacity of native Rhizobium leguminosarum bio-var trifolii strains, a greenhouse test was carried out using white clover (Trifolium re-pens) and four kinds of soils, which represent the main agroecological areas of the IX Region. Eleven strains were evaluated, they were both native and collected and were streptomycin sulphate antibiotic resistant. A nitrogen and a nitrogen-less without inoculation testers were used as controls. All pots received a solution of ammonium sulphate marked with 10% 15 N a.e, equivalent to 10 kg ha-1 of N. Rye-grass was used as reference crop, cv. Nu-i. In general, the evaluated strains were very efficient. After three or four cuts they became the only source of nitrogen for the plants. They were also very competitive, getting to over 70% of root infection with regard to those present in soils. In Curacautin and Tolten soils, biological nitrogen fixation begins later than other soils evaluated, which is coincident with soils having a higher nitrogen content. Symbiosis occurs when the soil nitrogen content exhausts or diminishes. (author)

  4. Symbiont shift towards Rhizobium nodulation in a group of phylogenetically related Phaseolus species.

    Science.gov (United States)

    Servín-Garcidueñas, Luis E; Zayas-Del Moral, Alejandra; Ormeño-Orrillo, Ernesto; Rogel, Marco A; Delgado-Salinas, Alfonso; Sánchez, Federico; Martínez-Romero, Esperanza

    2014-10-01

    Bean plants from the Phaseolus genus are widely consumed and represent a nitrogen source for human nutrition. They provide biological fertilization by establishing root nodule symbiosis with nitrogen-fixing bacteria. To establish a successful interaction, bean plants and their symbiotic bacteria need to synchronize a proper molecular crosstalk. Within the Phaseolus genus, P. vulgaris has been the prominent species to study nodulation with Rhizobium symbionts. However the Phaseolus genus comprises diverse species whose symbionts have not been analyzed. Here we identified and studied nodule bacteria from representative Phaseolus species not previously analyzed and from all the described wild species related to P. vulgaris. We found Bradyrhizobium in nodules from most species representing all Phaseolus clades except in five phylogenetically related species from the P. vulgaris clade. Therefore we propose that Bradyrhizobium nodulation is common in Phaseolus and that there was a symbiont preference shift to Rhizobium nodulation in few related species. This work sets the basis to further study the genetic basis of this symbiont substitution. PMID:24952318

  5. Extended region of nodulation genes in Rhizobium meliloti 1021. I. Phenotypes of Tn5 insertion mutants

    International Nuclear Information System (INIS)

    Rhizobium meliloti Nod- mutant WL131, a derivative of wild-type strain 102F51, was complemented by a clone bank of wild-type R. meliloti 1021 DNA, and clone pRmJT5 was recovered. Transfer of pRmJT5 conferred alfalfa nodulation on other Rhizobium species, indicating a role in host range determination for pRmJT5. Mutagenesis of pRmJT5 revealed several segments in which transposon insertion causes delay in nodulation, and/or marked reduction of the number of nodules formed on host alfalfa plants. The set of mutants indicated five regions in which nod genes are located; one mutant, nod-216, is located in a region not previously reported to encode a nodulation gene. Other mutant phenotypes correlated with the positions of open reading frames for nodH, nodF and nodE, and with a 2.2-kb EcoRI fragment. A mutant in nodG had no altered phenotype in this strain. One nodulation mutant was shown to be a large deletion of the common nod gene region. The authors present a discussion comparing the various studies made on this extended nod gene region

  6. Characterization and mutational analysis of nodHPQ genes of Rhizobium sp. strain N33.

    Science.gov (United States)

    Cloutler, J; Laberge, S; Castonguay, Y; Antoun, H

    1996-11-01

    We have shown, by sequencing the nodulation gene region of Rhizobium sp. strain N33 previously isolated from the Canadian high arctic, that the nodHPQ genes are located in a 4.8-kb region downstream of nodBCIJ. The open reading frames of nodHPQ are 747, 906, and 1941 nucleotides long, respectively. The strain N33 genome contains one copy of nodH and two copies of nodPQ that are homologous to those genes in Rhizobium meliloti. Tn5 insertions in the nodHPQ genes of strain N33 did not affect the formation of nodules on the two homologous hosts, Astragalus cicer and Onobrychis viciifolia. Since strain N33 contains the nodBCIJHPQ genes and the recently sequenced nodAFEG genes, we looked for similar host range with R. meliloti. Strain N33 and R. meliloti strains A2 and RCR2011 were shown to induce the formation of root nodules on plants of O. viciifolia. However, strain N33, compared with R. meliloti strains, was able to elicit a few, white, empty, root nodules on Medicago sativa. R. meliloti strains, compared with strain N33, were shown to induce only few nodules containing bacteria on A. cicer. Induction of nod genes transcription in strain N33 was shown to be induced by a variety of flavonoid compounds that are different from those inducing nod genes from R. meliloti. PMID:8870271

  7. Legume seed exudates and Physcomitrella patens extracts influence swarming behavior in Rhizobium leguminosarum.

    Science.gov (United States)

    Tambalo, Dinah D; Vanderlinde, Elizabeth M; Robinson, Shawn; Halmillawewa, Anupama; Hynes, Michael F; Yost, Christopher K

    2014-01-01

    Plants are known to secrete chemical compounds that can change the behavior of rhizosphere-inhabiting bacteria. We investigated the effects of extracts from legume host plants on the swarming behavior of Rhizobium leguminosarum bv. viciae. We also investigated the effects on swarming when Rhizobium is exposed to extracts from an ancestor to vascular plants, the model bryophyte Physcomitrella patens. Lentil and faba bean seed exudates enhanced and inhibited swarming motility, respectively, whereas pea seed exudates had no observable effect on swarming. Swarming was also enhanced by the moss extracts. Exposure to lentil seed exudates and the moss extract increased flaA expression 2-fold, while faba bean seed exudates exposure decreased expression 3-fold, suggesting that the swarming effect could, in part, be due to regulation of flagellin gene expression. However, the exudates and extracts did not significantly affect flaA gene expression in planktonic motile cells, indicating that the response to flagellar regulation is specific to a physiology unique to the swarming cell. Transmission electron microscopy demonstrated that addition of the lentil seed exudate and the moss extract results in earlier differentiation into swarmer cells, which could contribute to the development of a larger swarming surface area. To gain further mechanistic insight into the effect of the moss extract on swarming, a moss strigolactone-deficient mutant (Ppccd8?) was tested. A reduction in the promotive effect was observed, suggesting that the plant hormone strigolactone may be a signalling molecule activating swarming motility in R. leguminosarum. PMID:24392922

  8. The role of GSTs in the tolerance of Rhizobium leguminosarum to cadmium.

    Science.gov (United States)

    Corticeiro, Sofia; Freitas, Rosa; Figueira, Etelvina

    2013-12-01

    A high intraspecific difference in cadmium (Cd) tolerance exits among Rhizobium leguminosarum strains. The higher tolerance to Cd appeared to be related to the efficiency of the glutathione (GSH)-Cd chelation mechanism, but it is not known how efficiency is influenced. Thus, in this work it was intended to investigate the traits behind the efficiency of intracellular Cd chelation by GSH. Glutathione-S-transferases (GST; EC 2.5.1.18) are a family of multi-functional dimeric proteins, found in both prokaryotes and eukaryotes, which are implicated in a variety of stress conditions. The common feature of these enzymes is to catalyze the conjugation of the sulfur atom of GSH with a large variety of hydrophobic toxic compounds of both endogenous and exogenous origin. Taking into account the reactions catalyzed by GSTs, it was hypothesized that they could be involved in the GSH-Cd complex formation in R. leguminosarum. Differences in GSTs activity between strains could explain variation in Cd chelation efficiency detected among strains and, consequently, discrepancy in tolerance to Cd. Thus, GST isoforms of R. leguminosarum strains with distinct tolerances to Cd were purified and their activity investigated. The relationship between chelation efficiency and enzymatic activity of GSTs was demonstrated, supporting the hypothesis that GSTs, in particular one isoform, was involved in the formation of GSH-Cd complexes and in the tolerance of Rhizobium to Cd. PMID:23907727

  9. Variability of isolated colonies in bean nodulating Rhizobium strains before and after exposure to high temperature

    Directory of Open Access Journals (Sweden)

    Raposeiras Rui

    2002-01-01

    Full Text Available Irregular response to bean plants to Rhizobium inoculation has been attributed to among other factors, low competitive ability, low N2 fixation efficiency and genetic instability of the symbiont. This genetic instability caused by high rates of genomic rearrangements and/or plasmid deletions can be accentuated by high temperatures. This fact may limit the utilization of these strains as inoculants, especially in tropical soils. In this study, the variability of isolated colonies derived from effective R. leguminosarum bv. phaseoli (SLP1.3 and BR 10.026 and R tropici (SLA2.2 and BR322 strains was evaluated before and after exposure to high temperatures (four consecutive thermal shocks at 45masculineC. This evaluation involved plant dry matter analysis of inoculated plants and genotypic (plasmid profile and genomic patterns via RAPD analysis of the Rhizobium strains. The results evidenced that high temperature improve the natural performance variability especially between isolated colonies from R. leguminosarum bv. phaseoli strains. The plasmid profile of isolated colonies from R. tropici strains were identical regardless of temperature treatment whereas isolated colonies from R. leguminosarum bv. phaseoli alterations were detected especially after the thermal treatment. The genomic patterns generated by AP-PCR showed more alterations and genetic variation in isolated colonies from R. leguminosarum bv. phaseoli strains indicating that R. tropici strains are more stable and lower affected by high temperature.

  10. Studies on Nodulation, Biochemical Analysis and Protein Profiles of Rhizobium Isolated From Indigofera species

    Directory of Open Access Journals (Sweden)

    Kumari, B. S.

    2010-01-01

    Full Text Available Nodulation characteristics in five species of Indigofera viz., I .trita, I. linnaei, I. astragalina, I. parviflora and I. viscosa was studied at regular intervals on the plants raised in garden soil. Among the species studied, highest average number of nodules per plant of 23 with maximum sized nodules of 8.0 mm diameter was observed in I. astragalina. Biochemical analysis of root nodules of I. astragalina revealed that the leghaemoglobin content of nodules and nitrogen content of root, shoot, leaves and nodules were gradually increased up to 60 DAS, and then decreased with increase in age. Rhizobium isolates of five species of Indigofera were isolated and screened for enzymatic activities and total cellular protein profiles. All the five isolates showed nitrate reductase, citrase, tryptophanase and catalase activity while much variation was observed for enzymes like gelatinase, urease, caseinase, lipase, amylase, lysine decarboxylase and protease activities. Among the isolates studied, only the isolate from I. viscosa has the ability to solubilize the insoluble tricalcium phosphate. All the Rhizobium isolates exhibit similarity in protein content, except the isolate from I. viscosa which showed one additional protein band.

  11. Characterization of NopP, a type III secreted effector of Rhizobium sp. strain NGR234.

    Science.gov (United States)

    Ausmees, Nora; Kobayashi, Hajime; Deakin, William J; Marie, Corinne; Krishnan, Hari B; Broughton, William J; Perret, Xavier

    2004-07-01

    The type three secretion system (TTSS) encoded by pNGR234a, the symbiotic plasmid of Rhizobium sp. strain NGR234, is responsible for the flavonoid- and NodD1-dependent secretion of nodulation outer proteins (Nops). Abolition of secretion of all or specific Nops significantly alters the nodulation ability of NGR234 on many of its hosts. In the closely related strain Rhizobium fredii USDA257, inactivation of the TTSS modifies the host range of the mutant so that it includes the improved Glycine max variety McCall. To assess the impact of individual TTSS-secreted proteins on symbioses with legumes, various attempts were made to identify nop genes. Amino-terminal sequencing of peptides purified from gels was used to characterize NopA, NopL, and NopX, but it failed to identify SR3, a TTSS-dependent product of USDA257. By using phage display and antibodies that recognize SR3, the corresponding protein of NGR234 was identified as NopP. NopP, like NopL, is an effector secreted by the TTSS of NGR234, and depending on the legume host, it may have a deleterious or beneficial effect on nodulation or it may have little effect. PMID:15231809

  12. Role of Rhizobium endoglucanase CelC2 in cellulose biosynthesis and biofilm formation on plant roots and abiotic surfaces

    Directory of Open Access Journals (Sweden)

    Robledo M

    2012-09-01

    Full Text Available Abstract Background The synthesis of cellulose is among the most important but poorly understood biochemical processes, especially in bacteria, due to its complexity and high degree of regulation. In this study, we analyzed both the production of cellulose by all known members of the Rhizobiaceae and the diversity of Rhizobium celABC operon predicted to be involved in cellulose biosynthesis. We also investigated the involvement in cellulose production and biofilm formation of celC gene encoding an endoglucanase (CelC2 that is required for canonical symbiotic root hair infection by Rhizobium leguminosarum bv. trifolii. Results ANU843 celC mutants lacking (ANU843?C2 or overproducing cellulase (ANU843C2+ produced greatly increased or reduced amounts of external cellulose micro fibrils, respectively. Calcofluor-stained cellulose micro fibrils were considerably longer when formed by ANU843?C2 bacteria rather than by the wild-type strain, in correlation with a significant increase in their flocculation in batch culture. In contrast, neither calcofluor-stained extracellular micro fibrils nor flocculation was detectable in ANU843C2+ cells. To clarify the role of cellulose synthesis in Rhizobium cell aggregation and attachment, we analyzed the ability of these mutants to produce biofilms on different surfaces. Alteration of wild-type CelC2 levels resulted in a reduced ability of bacteria to form biofilms both in abiotic surfaces and in planta. Conclusions Our results support a key role of the CelC2 cellulase in cellulose biosynthesis by modulating the length of the cellulose fibrils that mediate firm adhesion among Rhizobium bacteria leading to biofilm formation. Rhizobium cellulose is an essential component of the biofilm polysaccharidic matrix architecture and either an excess or a defect of this “building material” seem to collapse the biofilm structure. These results position cellulose hydrolytic enzymes as excellent anti-biofilm candidates.

  13. Sequence analysis of hypothetical lysine exporter genes of Rhizobium leguminosarum bv. trifolii from calamine old waste heaps and their evolutionary history.

    Science.gov (United States)

    Ole?ska, Ewa; Ma?ek, Wanda

    2013-05-01

    The aim of this study was to identify heavy metal detoxification system in Rhizobium leguminosarum bv. trifolii isolated from Trifolium repens inhabiting old (70-100 years) Zn-Pb waste heaps in Poland by PCR reaction with czcD1 and czcD2 primers. By sequence analysis, four different genotypes of obtained amplicons were identified among eight examined isolates. Their sequence similarity ranged 91-99 %. They indicated the highest sequence identity to the hypothetical lysine exporter gene of R. leguminosarum bv. trifolii WSM1325 (91-97 %) and 76-81 % sequence similarity to hypothetical lysine exporter genes of R. leguminosarum bv. trifolii WSM2304 and R. etli CFN42 and CIAT652. On phylogenetic tree of obtained amplicons, all four studied R. leguminosarum bv. trifolii genotypes formed common monophyletic cluster with R. leguminosarum bv. trifolii WSM1325 at 100 % bootstrap support showing that all four amplicons obtained in PCR with czcD1 and czcD2 primers are fragments of hypothetical lysine exporter gene (lysE). We also suggest that Lys efflux exporter may participate in heavy metal transport out of R. leguminosarum bv. trifolii cells. PMID:23322256

  14. Enhanced Survival and Nodule Occupancy of Pigeon pea Nodulating Rhizobium sp. ST1 expressing fegA Gene of Bradyrhizobium japonicum 61A152

    Directory of Open Access Journals (Sweden)

    G. Archana

    2009-01-01

    Full Text Available Problem statement: Rhizobial isolates belonging to genera (Rhizobium sp. and Mesorhizobium sp. in our laboratory produced only catecholate type of siderophores. Although FhuA and FegA (ferrichrome receptors homologs were found to be present in the sequenced genomes of few rhizobia (e.g., 1 in R. etli and 2 in Mesorhizobium sp. BNC1, laboratory isolates of the corresponding genera failed to utilize ferrichrome, a siderophore which is present in nanomolar concentrations in the soil. This inability was considered as a negative fitness factor with respect to rhizospheric colonization by these rhizobia. Approach: The 2.4 kb fegA gene (encoding ferrichrome receptor was amplified along with its native promoter from Bradyrhizobium japonicum 61A152 and cloned in a broad host range plasmid vector pUCPM18. The plasmid construct pFJ was transferred by conjugation into Rhizobium sp. ST1 to give transconjugant ST1pFJ12. The consequence of FegA expression on the transconjugant was tested under lab and soil conditions, using physiological experiments. Results: Ability of the transconjugant ST1pFJ12 to utilize ferrichrome and expression of a 79 kD protein band on the outer membrane of the transconjugant confirmed FegA expression. Transconjugant ST1pFJ12 exhibited increased growth rate as compared to the parent strain ST1, in minimal media containing ferrichrome as the sole iron source, confirming the positive effect of FegA expression. Inoculation of pigeon pea seedlings with transconjugant ST1pFJ12 led to a marked increase in plant growth parameters as compared to plants inoculated with the parent strain ST1, the effect being more pronounced when Ustilago maydis, a ferrichrome producer was co-inoculated in the systems. Nodule occupancy on pigeon pea plant when inoculated with the transconjugant ST1pFJ12 alone was 57% which increased to 66% when co-inoculated with U. maydis as compared with 37 and 30% respectively, seen with parental strain ST1 inoculation. Conclusion: The clear increase in nodule occupancy and higher rhizospheric colonization by the fegA transconjugants, presented in this study together with the previous research reported from our laboratory, led us to conclude that ferrichrome utilization ability played an important role in the rhizospheric colonization of the bioinoculant strains. Testing the ability to utilize hydroxamate siderophores therefore, holds prime importance in selecting an efficient biofertilizer strain.

  15. GAT 3 - fuel cells and their management (PACoGES). Progress report; GAT 3 - piles a combustible et leur gestion (PACoGES). Rapport final (juillet 2002 a juin 2004)

    Energy Technology Data Exchange (ETDEWEB)

    Lamy, C.

    2005-07-01

    The Topic Analysis Group PACoGES ('Piles a Combustible et leur Gestion') has conducted thoughts on fuel cells and their management with all the searchers concern with researches and developments on fuel cells and in particular on solid oxide fuel cells (SOFC, ITSOFC) running at high temperature (600 to 1000 C). This has concerned about 200 searchers working in about fifty laboratories (CNRS, CEA, EDF, GDF, INRETS, CNAM, Armines, and several industrial teams). Here is given the final report 2002-2004 concerning all the researches carried out by this Group. (O.M.)

  16. Genetic analysis of a region of the Rhizobium meliloti pSym plasmid specifying catabolism of trigonelline, a secondary metabolite present in legumes.

    OpenAIRE

    Boivin, C.; Barran, L. R.; Malpica, C. A.; Rosenberg, C.

    1991-01-01

    Genes controlling the catabolism of trigonelline, a secondary metabolite that is often present in legumes, are located on the pSym megaplasmid of Rhizobium meliloti. To investigate the role of bacterial trigonelline catabolism in the Rhizobium-legume symbiosis, we identified and characterized the R. meliloti RCR2011 genetic loci (trc) controlling trigonelline catabolism. Tn5-B20 mutagenesis showed that the trc region is a continuous DNA segment of 9 kb located 4 kb downstream of the nifAB and...

  17. Evaluation of Bean (Phaseolus vulgaris) Seeds Inoculation with Rhizobium phaseoli and Plant Growth Promoting Rhizobacteria on Yield and Yield Components

    OpenAIRE

    Yadegari, M.; Rahmani, H. A.; Noormohammadi, G.; Ayneband, A.

    2008-01-01

    To study the effect of co-inoculation with plant growth-promoting rhizobacteria (PGPR) and Rhizobium, on yield and yield components of common bean (Phaseolus vulgaris L.) cultivars was investigated in 2 consecutive years under field condition of plant growing evidence indicates that soil beneficial bacteria can positively affect symbiotic performance of rhizobia. PGPR strains Pseudomonas fluorescens P-93 and Azospirillum lipoferum S-21 as well as two highly effective Rhizobium strains ...

  18. The effect of culture filtrates of the saprophytic fungi isolated from peas and field peas roots and nodules on the growth of Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Helena Furga?-W?grzycka

    1987-06-01

    Full Text Available In the work the effect of culture filtrates of biotic series of 34 species of saprophytic fungi isolated from roots and root nodules of peas and field peas on the growth of Rhizobium leguminosarum was determined. The results obtained proved that the growth of Rhizobium leguminosarum was inhibited by culture filtrates of saprophytic fungi: Aspergillus niger, A.flavus, Cephalosporium roseum, Cylindrocarpon radicicola, Fusarium oxysporum, F. solani, Glocladium roseum, Penicillium notatum, P. janthinellum, Trichoderma lignorum, and T. viride.

  19. Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.).

    Science.gov (United States)

    Ahmad, Maqshoof; Zahir, Zahir A; Nazli, Farheen; Akram, Fareeha; Arshad, Muhammad; Khalid, Muhammad

    2013-12-01

    Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m(-1) under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean. PMID:24688532

  20. Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.)

    Scientific Electronic Library Online (English)

    Maqshoof, Ahmad; Zahir A., Zahir; Farheen, Nazli; Fareeha, Akram; Muhammad, Arshad; Muhammad, Khalid.

    1341-13-01

    Full Text Available SciELO Brazil | Language: English Abstract in english Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their [...] ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m-1 under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean.

  1. Efeito residual da vinhaça na população autóctone de Rhizobium do solo Residual effects of sugar cane vinasse on indigenous Rhizobia

    Directory of Open Access Journals (Sweden)

    Eli Sidney Lopes

    1986-01-01

    Full Text Available A adição de vinhaça na cultura canavieira tem sido praticada em áreas próximas às usinas de cana. Seria de interesse a avaliação do efeito da vinhaça no Rhizobium presente no solo (autóctone, uma vez que leguminosas têm sido indicadas para cultivo intercalar com a cana. Um experimento foi conduzido em casa de vegetação, com o objetivo de verificar a influência da aplicação contínua, durante três anos, de concentrações crescentes de vinhaça (0, 100 e 1.000 m³/ha/ano, com intervalos de seis meses entre aplicações, na população autóctone de Rhizobium que nodula amendoim, soja, feijão e crotalária. Em cada cultura, foram usados controle com solo sem adição da vinhaça e um tratamento inoculado com uma estirpe de Rhizobium de conhecida eficiência, recomendada para a cultura. Uma análise do efeito de uma dose adicional de 1,5 ppm do herbicida 2,4-D no tratamento com 100 m³/ha/ano foi também efetuada. Apesar de os resultados serem variados entre as culturas, ocorreram efeitos da vinhaça sobre a população de Rhizobium, causando aumentos de nodulação na crotalária e diminuição no amendoim. Não foram observados efeitos na nodulação do feijoeiro em nenhum dos tratamentos com a vinhaça, nem na soja, que nodulou somente com a dose mais elevada, sugerindo que o Rhizobium japonicum no solo estudado estava presente em baixo número. O tratamento com herbicida mostrou tendência de favorecer a nodulação e, conseqüentemente, a fixação biológica de N2, medida através do N na planta.The addition of vinasse on sugar cane plantations nearby alcohol fermentation plants is a common practice. Legumes are recommended to be intercropped with sugar cane. A greenhouse experiment was carried out with the objective of verifying the influence of continuous application of vinasse (0; 100 and 1000 m³/ha/year at six month interval during three years on soil rhizobia which nodulate peanuts, soybeans, dry-beans and crotalaria. Controls without vinasse and with efficient Rhizobium sp. strain were maintained. The effect of 2,4 D application on the 100 m³ vinasse/ha treatment was also studied. Although results were variable and dependent on crop, the addition of vinasse influenced the rhizobia population, causing for instance, reductions on nodulation of peanuts and increases on that of crotalaria; no effects were observed either on drybeans or soybeans. Indigenous population of soybean Rhizobiun was inexpressive. The herbicide treatment showed tendency to favour nodulation and consequently N2 fixation.

  2. The morphogenesis of lupine root nodules during infection by Rhizobium lupini

    Directory of Open Access Journals (Sweden)

    W?adys?aw Golinowski

    1987-12-01

    Full Text Available The development of root nodules in Lupinus luteus infected by Rhizobium lupini was studied using cytological methods. The results obtained from examination of material sampled 6, 9, 13, 15, 20, 29 and 60 days after infection are given. The successive stages of development are described and the cytological characteristics of the tissue are presented. The mitotic divisions of the root cortex parenchyma cells, which initiated the formation of the nodule primordium, were accompanied by structural changes in the root hairs and divisions in the root pericycle. The development of the nodule was associated with the activity of the lateral meristems, which encompass both the infected cells and cells not containing bacteroids Characteristics of bacteria found in the symplast and apoplast of the bacteroid tissue are given.

  3. Comparison of characteristics of the nodX genes from various Rhizobium leguminosarum strains.

    Science.gov (United States)

    Ovtsyna, A O; Rademaker, G J; Esser, E; Weinman, J; Rolfe, B G; Tikhonovich, I A; Lugtenberg, B J; Thomas-Oates, J E; Spaink, H P

    1999-03-01

    We have analyzed the nucleotide sequences of the nodX genes from two strains of Rhizobium leguminosarum bv. viciae able to nodulate Afghan peas (strains A1 and Himalaya) and from two strains of R. leguminosarum bv. trifolii (ANU843 and CSF). The nodX genes of strains A1 and ANU843 were shown to be functional for the induction of nodules on Afghan peas. To analyze the cause of phenotypic differences of strain A1 and strain TOM we have studied the composition of the lipochitin-oligosaccharides (LCOs) produced by strain A1 after induction by the flavonoid naringenin or various pea root exudates. The structural analysis of the LCOs by mass spectrometry revealed that strain A1 synthesizes a family of at least 23 different LCOs. The use of exudates instead of naringenin resulted only in quantitative differences in the ratios of various LCOs produced. PMID:10065561

  4. Biosynthesis of a galactose-and galacturonic acid-containing polysaccharide in Rhizobium meliloti.

    Science.gov (United States)

    Ugalde, R A; Coira, J A; Brill, W J

    1986-10-01

    Previous work showed that two different strains derived from a culture of Rhizobium meliloti 102F51 differed with respect to phage specificity, agglutinability by alfalfa seed lectin, and synthesis of a galactose-containing polysaccharide (R. A. Ugalde, H. Handelsman, and W. J. Brill, J. Bacteriol. 166:148-154, 1986). Inner membranes from the more competitive strain incorporated galactose from UDP-galactose when a thermostable factor was present. This factor has now been identified as UDP-galacturonic acid. UDP-glucuronic acid was also active as a donor; however, this activity may be due to the presence of a 4-epimerase. Galacturonic acid, together with galactose, is incorporated into the reaction product, which appears to be a polysaccharide formed by several repeating units of these two monosaccharides. Partial acid hydrolysis liberates the disaccharide with galactose at the reducing end. PMID:3759905

  5. Biodegradation of hazardous triphenylmethane dye methyl violet by Rhizobium radiobacter (MTCC 8161).

    Science.gov (United States)

    Parshetti, Ganesh; Saratale, Ganesh; Telke, Amar; Govindwar, Sanjay

    2009-09-01

    Rhizobium radiobacter MTCC 8161 completely decolorized methyl violet (10 mg l(-1)) within 8 h both at static and shaking conditions. The decolorization time increased with increasing dye concentration. The effect of different carbon and nitrogen sources on the decolorization of methyl violet was studied. The maximum decolorization was observed in the presence of sucrose (1%) and urea (1%). UV-Visible, HPLC and FTIR analysis of extracted products confirmed biodegradation of methyl violet. The significant increase in the activities of lignin peroxidase and aminopyrine N-demethylase in the cells obtained after decolorization indicated involvement of these enzymes in the decolorization process. In addition to methyl violet, this strain also shows an ability to decolorize various industrial dyes, (red HE7B, yellow 4G, blue 2B, navy blue HE22, red M5B and red HE3B). PMID:19322828

  6. Asymptomatic catheter related Rhizobium radiobacter infection in a haploidentical hemapoetic stem cell recipient.

    Science.gov (United States)

    Erol Cipe, Funda; Do?u, Figen; Sucuo?lu, Deniz; Aysev, Derya; Ikincio?ullar?, Aydan

    2010-08-01

    Catheter related infections are reported as one of the most common source of nosocomial infections. Rhizobium radibacter infections are generally manifested by fever and leukocytosis. Here, a 14 months-old girl diagnosed as T (-) B (-) NK (+) severe combined immunodeficiency (SCID) is presented. She had received repeated (x3) unconditioned haploidentical hematopoetic stem cell transplantations. During the follow-up, she has been arised an asymptomatic infection with R. Radiobacter, which was isolated from central venous catheter and peripheral blood while she was clinically stable, free of symptoms, fever or leukocytosis. She was treated successfully with cefepime and amikacin and did not require catheter removal. So, it is once more clear that the blood cultures should be obtained on regular basis from all patients with an intravascular device, even they were asymptomatic. PMID:20818107

  7. Isolation and Identification of Rhizobium Bacteriophages in Guilan and Isfahan Provinces, Iran

    Directory of Open Access Journals (Sweden)

    2008-01-01

    Full Text Available Rhizobia are one of the most important nitrogen fixing bacteria which interact specifically with legume species and induce formation of root nodules. Selective elimination of rhizobia is induced by rhizobiophages in soil. Bacteriophages can also be used for phage typing in epidemiological studies. Rhizobia were isolated from root nodules of Cicer arietinum L., Phaseolus vulgaris L. and Trigonella foenum-graecum L. plants grown in Jir-Gavabar of Roudsar and 3 areas of Isfahan. Four rhizobiophages were isolated from the same soils and purified. Morphology of the phages were studied by electron microscopy. Based on morphological features, the phages appear to be members of Myoviridae, Siphoviridae and Microviridae families. It was found for the first time that phages rather than siphoviridae are also able to infect Rhizobium leguminosarum bv. viciae ( Cicer arietinum L..

  8. Functional characterization of aroA from Rhizobium leguminosarum with significant glyphosate tolerance in transgenic Arabidopsis.

    Science.gov (United States)

    Han, Jing; Tian, Yong-Sheng; Xu, Jing; Wang, Li-Juan; Wang, Bo; Peng, Ri-He; Yao, Quan-Hong

    2014-09-01

    Glyphosate is the active component of the top-selling herbicide, the phytotoxicity of which is due to its inhibition of the shikimic acid pathway. 5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS) is a key enzyme in the shikimic acid pathway. Glyphosate tolerance in plants can be achieved by the expression of a glyphosate-insensitive aroA gene (EPSPS). In this study, we used a PCR-based two-step DNA synthesis method to synthesize a new aroA gene (aroAR. leguminosarum) from Rhizobium leguminosarum. In vitro glyphosate sensitivity assays showed that aroAR. leguminosarum is glyphosate tolerant. The new gene was then expressed in E. coli and key kinetic values of the purified enzyme were determined. Furthermore, we transformed the aroA gene into Arabidopsis thaliana by the floral dip method. Transgenic Arabidopsis with the aroAR. leguminosarum gene was obtained to prove its potential use in developing glyphosate-resistant crops. PMID:24836188

  9. Impact of Salicylic Acid on Symbiotic Relations Between Peas and Rhizobium leguminosarum bv. viceae

    Directory of Open Access Journals (Sweden)

    A.K. Glyanko

    2004-01-01

    Full Text Available The study was targeted at the investigation of exogenous salicylic acid (SA impact on bacteria proliferation in vitro, rhizobia penetration in the root tissues, the SA and hydrogen peroxide (H2O2 content in the root seedlings under inoculation of pea by compatible strain Rhizobium leguminosarum bv. viceae. Depending on the concentration SA either did not affect (0.0036-0.014 mM rhizobia proliferation or suppressed their growth (0.07-0.2 mM in vitro. Exogenous SA (0.2 mM inhibited rhizobia penetration in the root tissues (by 2 and 5 times depending on pH medium and contributed to the increase of endogenous SA and H2O2 content in the tissues. Various possible mechanisms of SA impact on rhizobial symbiosis are discussed.

  10. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain TA1.

    Science.gov (United States)

    Reeve, Wayne; Tian, Rui; De Meyer, Sofie; Melino, Vanessa; Terpolilli, Jason; Ardley, Julie; Tiwari, Ravi; Howieson, John; Yates, Ronald; O'Hara, Graham; Ninawi, Mohamed; Teshima, Hazuki; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Ovchinnikova, Galina; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Pitluck, Sam; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii strain TA1 is an aerobic, motile, Gram-negative, non-spore-forming rod that is an effective nitrogen fixing microsymbiont on the perennial clovers originating from Europe and the Mediterranean basin. TA1 however is ineffective with many annual and perennial clovers originating from Africa and America. Here we describe the features of R. leguminosarum bv. trifolii strain TA1, together with genome sequence information and annotation. The 8,618,824 bp high-quality-draft genome is arranged in a 6 scaffold of 32 contigs, contains 8,493 protein-coding genes and 83 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program. PMID:24976881

  11. Genome sequence of the South American clover-nodulating Rhizobium leguminosarum bv. trifolii strain WSM597.

    Science.gov (United States)

    Reeve, Wayne; Terpolilli, Jason; Melino, Vanessa; Ardley, Julie; Tian, Rui; De Meyer, Sofie; Tiwari, Ravi; Yates, Ronald; O'Hara, Graham; Howieson, John; Ninawi, Mohamed; Held, Brittany; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Ivanova, Natalia; Ovchinnikova, Galina; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii strain WSM597 is an aerobic, motile, Gram-negative, non-spore-forming rod isolated from a root nodule of the annual clover Trifolium pallidum L. growing at Glencoe Research Station near Tacuarembó, Uruguay. This strain is generally ineffective for nitrogen (N2) fixation with clovers of Mediterranean, North American and African origin, but is effective on the South American perennial clover T. polymorphum Poir. Here we describe the features of R. leguminosarum bv. trifolii strain WSM597, together with genome sequence information and annotation. The 7,634,384 bp high-quality-draft genome is arranged in 2 scaffolds of 53 contigs, contains 7,394 protein-coding genes and 87 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program. PMID:24976883

  12. Genome sequence of the Trifolium rueppellianum -nodulating Rhizobium leguminosarum bv. trifolii strain WSM2012.

    Science.gov (United States)

    Reeve, Wayne; Melino, Vanessa; Ardley, Julie; Tian, Rui; De Meyer, Sofie; Terpolilli, Jason; Tiwari, Ravi; Yates, Ronald; O'Hara, Graham; Howieson, John; Ninawi, Mohamed; Held, Brittany; Bruce, David; Detter, Chris; Tapia, Roxanne; Han, Cliff; Wei, Chia-Lin; Huntemann, Marcel; Han, James; Chen, I-Min; Mavromatis, Konstantinos; Markowitz, Victor; Szeto, Ernest; Ivanova, Natalia; Mikhailova, Natalia; Pagani, Ioanna; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii WSM2012 (syn. MAR1468) is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an ineffective root nodule recovered from the roots of the annual clover Trifolium rueppellianum Fresen growing in Ethiopia. WSM2012 has a narrow, specialized host range for N2-fixation. Here we describe the features of R. leguminosarum bv. trifolii strain WSM2012, together with genome sequence information and annotation. The 7,180,565 bp high-quality-draft genome is arranged into 6 scaffolds of 68 contigs, contains 7,080 protein-coding genes and 86 RNA-only encoding genes, and is one of 20 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Community Sequencing Program. PMID:24976885

  13. Rhizobium miluonense sp. nov., a symbiotic bacterium isolated from Lespedeza root nodules.

    Science.gov (United States)

    Gu, Chun Tao; Wang, En Tao; Tian, Chang Fu; Han, Tian Xu; Chen, Wen Feng; Sui, Xin Hua; Chen, Wen Xin

    2008-06-01

    Seventeen strains of lespedeza rhizobia, a previously defined novel group, were further characterized by comparison with phylogenetically related species using a polyphasic approach, including SDS-PAGE of whole-cell proteins, PCR-based restriction fragment length polymorphism analysis of ribosomal intergenic spacer sequences, determination of DNA G+C contents, DNA-DNA hybridization and analysis of phenotypic features. Based on data obtained in the present and previous studies, a novel species, Rhizobium miluonense sp. nov., is proposed for these strains. The type strain of R. miluonense is CCBAU 41251(T) (=LMG 24208(T)=HAMBI 2971(T)). Strain CCBAU 41251(T) could form ineffective nodules on Phaseolus vulgaris in addition to its original host Lespedeza chinensis. PMID:18523179

  14. Expression of the symbiotic plasmid from Rhizobium leguminosarum biovar trifolii in Sphingobacterium multivorum.

    Science.gov (United States)

    Fenton, M; Jarvis, B D

    1994-10-01

    An inoculant strain of Rhizobium leguminosarum biovar trifolii containing a Tn5 marked symbiotic plasmid transferred this plasmid by conjugation to Sphingobacterium multivorum, an organism that can be found in soil. The transconjugant bacteria nodulated the roots of white clover (Trifolium repens) seedlings but did not fix atmospheric nitrogen. Microscopic examination revealed abnormal nodule structures. Bacteria isolated from the nodules were shown to be closely related to the recipient S. multivorum and Southern blots of genomic digests probed with nodA DNA confirmed that the transconjugants contained symbiotic genes. This is the first report of the spontaneous transfer, by conjugation, of a symbiotic plasmid from R. leguminosarum biovar trifolii to S. multivorum. PMID:8000966

  15. Effect of aluminum on the production of siderophore by Rhizobium sp. (Cicer arietinum).

    Science.gov (United States)

    Roy, N; Chakrabartty, P K

    2000-07-01

    Rhizobium sp. strain BICC 651 in the presence of 100 microM Al3+ produced a threefold higher level of siderophore than in the control culture under iron limitation during the stationary phase. Al3+ in increasing concentrations resulted in decreased growth, and the effect was alleviated by the addition of iron. Siderophore production decreased gradually in Al3+-treated culture as well as in the control with the addition of increasing concentrations of Fe3+, and at 50 microM Fe3+ the level of siderophore was practically undetectable. The siderophore binds Fe3+ and also Al3+. The outer membrane protein profiles of the bacteria grown in the presence or absence of Al3+ were indistinguishable. PMID:10919391

  16. Effect of Rhizobium inoculation of seeds and foliar fertilization on productivity of Pisum sativum L.

    Directory of Open Access Journals (Sweden)

    Tadeusz Zaj?c

    2013-07-01

    Full Text Available Pea (Pisum sativum L. is the second most important grain legume crop in the world which has a wide array of uses for human food and fodder. One of the major factors that determines the use of field pea is the yield potential of cultivars. Presently, pre-sowing inoculation of pea seeds and foliar application of microelement fertilizers are prospective solutions and may be reasonable agrotechnical options. This research was undertaken because of the potentially high productivity of the 'afila' morphotype in good wheat complex soils. The aim of the study was to determine the effect of vaccination with Rhizobium and foliar micronutrient fertilization on yield of the afila pea variety. The research was based on a two-year (2009–2010 controlled field experiment, conducted in four replicates and carried out on the experimental field of the Bayer company located in Modzurów, Silesian region. experimental field soil was Umbrisol – slightly degraded chernozem, formed from loess. Nitragina inoculant, as a source of symbiotic bacteria, was applied before sowing seeds. Green area index (GAI of the canopy, photosynthetically active radiation (PAR, and normalized difference vegetation index (NDVI were determined at characteristic growth stages. The presented results of this study on symbiotic nitrogen fixation by leguminous plants show that the combined application of Nitragina and Photrel was the best combination for productivity. Remote measurements of the pea canopy indexes indicated the formation of the optimum leaf area which effectively used photosynthetically active radiation. The use of Nitragina as a donor of effective Rhizobium for pea plants resulted in slightly higher GAI values and the optimization of PAR and NDVI. It is not recommended to use foliar fertilizers or Nitragina separately due to the slowing of pea productivity.

  17. Final comment to the results of Bustamante et al. on discrete Rossby/drift wave resonant and quasi-resonant triads

    CERN Document Server

    Kartashov, A

    2013-01-01

    In this final note we demonstrate that the authors of manuscripts arXiv:1210.2036, arXiv:1309.0405 and arXiv:1309.5513 use mathematical notations and notions sometimes in the standard meaning and sometimes in a sense which differs from the standard. As this specific use is not defined beforehand, the authors' statements are self-contradictory which makes any further scientific discussion meaningless.

  18. Interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol / Interaction among Tsukamurella paurometabola C-924 and Rhizobium leguminosarum biovar phaseoli CFH in bean plants

    Scientific Electronic Library Online (English)

    Marieta, Marín Bruzos; Jesús, Mena Campos; Pavel, Chaveli Chávez; Rolando, Morán Valdivia; Eulogio, Pimentel Vázquez.

    2013-01-01

    Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish En el estudio se evaluaron, mediante análisis de los parámetros fenológicos de las plantas, la interacción de Tsukamurella paurometabola C-924 con Rhizobium leguminosarum biovar phaseoli CFH en el cultivo de frijol. Se emplearon cuatro tratamientos: plantas sin inocular (control), inoculadas con T. [...] paurometabola C-924, inoculadas con R. leguminosarum biovar phaseoli CFH e inoculadas con ambas cepas. Se observaron diferencias significativas (P Abstract in english The experiment was carried out to evaluate the interaction between Tsukamurella paurometabola C-924 and Rhizobium leguminosarum biovar phaseoli CFH in bean plants. Treatments consisted of non-inoculated plants (control), plants inoculated with T. paurometabola C-924, inoculated with R. leguminosarum [...] biovar phaseoli CFH and inoculated with both strains. The application of the microorganisms single or in coinoculation improved the germination of seeds. T. paurometabola C-924 did not enhanced Rhizobium nodulation. However, no significant differences were found among treatments for shoot height and diameter. There was an increase in number of leaves in the plants inoculated with T. paurometabola C-924. We concluded that the interaction between T. paurometabola C-924 and R. leguminosarum biovar phaseoli CFH improved the number of leaves and the germination of seeds and even though T. paurometabola C-924 did not enhance nodulation, this fact did not affect the plants growth.

  19. Random amplified polymorphic DNA analysis of effective Rhizobium sp. associated with beans cultivated in brazilian cerrado soils / Caracterização, via RAPD, de estirpes efetivas de Rhizobium sp associadas ao feijoeiro cultivado em solos de cerrado no Brasil

    Scientific Electronic Library Online (English)

    Isnia Aparecida de, Oliveira; Maria José, Vasconcellos; Lucy, Seldin; Edilson, Paiva; Milton Alexandre, Vargas; Nadja Maria Horta de, Sá.

    2000-03-01

    Full Text Available SciELO Brazil | Language: English Abstract in portuguese Estirpes de Rhizobium eficientes na nodulação do feijoeiro, isoladas de diferentes solos da região do cultivo dessa leguminosa nos cerrados brasileiros, foram caracterizadas via RAPD. Esse estudo mostrou grande heterogeneidade genética entre as estirpes de R. tropici e R. leguminosarum bv. phaseoli [...] testadas e permitiu a definição de grupos genéticos, além de indicar os "primers" mais adequados para essa caracterização. Os grupos de estirpes geneticamente distintas podem ser usados em estudos de competitividade, importantes para obtenção de resultados positivos na inoculação dessa leguminosa em solos de cerrado. Abstract in english Efficient bean nodulating Rhizobium strains, isolated from different Brazilian cerrado soils, were characterized by RAPD. This study showed great genetic heterogeneity among R. tropici and R. leguminosarum bv. phaseoli strains and allowed the constitution of genetic clusters, besides indicating the [...] most suitable primers for this characterization. The groups of genetically distinct strains can be used in competitiveness studies to select appropriate Rhizobium strains for bean inoculation in cerrado soils.

  20. Dual inoculation with an Aarbuscular Mycorrhizal fungus and Rhizobium to facilitate the growth of alfalfa on coal mine substrates

    Energy Technology Data Exchange (ETDEWEB)

    Wu, F.Y.; Bi, Y.L.; Wong, M.H. [China University of Mining & Technology, Beijing (China)

    2009-07-01

    A pot experiment was conducted to investigate the effects of Glomus mosseae and Rhizobium on Medicago sativa grown on three types of coal mine substrates, namely a mixture of coal wastes and sands (CS), coal wastes and fly ash (CF), and fly ash (FA). Inoculation with Rhizobium alone did not result in any growth response but G. mosseae alone displayed a significant effect on plant growth. G. mosseae markedly increased the survival rate of M. sativa in CS substrate. In CF and FA substrates the respective oven dry weights of M. sativa inoculated with G. mosseae were 1.8 and 5.1 times higher than those without inoculation. Based on nitrogen (N), phosphorus (P) and potassium (K) uptake and legume growth, the results also show that dual inoculation in CS and CF substrates elicited a synergistic effect. This indicates that inoculation with arbuscular mycorrhizal (AM) fungi may be a promising approach for revegetation of coal mine substrates.

  1. Characterisation of SalRAB a Salicylic Acid Inducible Positively Regulated Efflux System of Rhizobium leguminosarum bv viciae 3841

    OpenAIRE

    Tett, Adrian J.; Karunakaran, Ramakrishnan; Poole, Philip S.

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively ...

  2. Transcriptomic analysis of Rhizobium leguminosarum biovar viciae in symbiosis with host plants Pisum sativum and Vicia cracca.

    OpenAIRE

    Karunakaran, R.; Ramachandran, Vk; Seaman, Jc; East, Ak; Mouhsine, B.; Mauchline, Th; Prell, J.; Skeffington, A.; Poole, Ps

    2009-01-01

    Rhizobium leguminosarum bv. viciae forms nitrogen-fixing nodules on several legumes, including pea (Pisum sativum) and vetch (Vicia cracca), and has been widely used as a model to study nodule biochemistry. To understand the complex biochemical and developmental changes undergone by R. leguminosarum bv. viciae during bacteroid development, microarray experiments were first performed with cultured bacteria grown on a variety of carbon substrates (glucose, pyruvate, succinate, inositol, acetate...

  3. Hydrogenase genes from Rhizobium leguminosarum bv. viciae are controlled by the nitrogen fixation regulatory protein?NifA

    OpenAIRE

    Brito, Bele?n; Marti?nez, Marta; Ferna?ndez, Domingo; Rey, Luis; Cabrera, Ezequiel; Palacios, Jose? Manuel; Imperial, Juan; Ruiz-argu?eso, Toma?s

    1997-01-01

    Rhizobium leguminosarum bv. viciae expresses an uptake hydrogenase in symbiosis with peas (Pisum sativum) but, unlike all other characterized hydrogen-oxidizing bacteria, cannot express it in free-living conditions. The hydrogenase-specific transcriptional activator gene hoxA described in other species was shown to have been inactivated in R. leguminosarum by accumulation of frameshift and deletion mutations. Symbiotic transcription of hydrogenase structural genes hupSL originates from a ?2...

  4. Characterization of Rhizobium naphthalenivorans sp. nov. with special emphasis on aromatic compound degradation and multilocus sequence analysis of housekeeping genes.

    Science.gov (United States)

    Kaiya, Shinichi; Rubaba, Owen; Yoshida, Naoko; Yamada, Takeshi; Hiraishi, Akira

    2012-01-01

    Three strains of aerobic chemoorganotrophic naphthalene-degrading bacteria (designated TSY03b(T), TSY04, and TSW01) isolated from sediment of a polychlorinated-dioxin-transforming microcosm were characterized. These strains had Gram-negative-stained, rod-shaped cells measuring 0.6?0.9 ?m in width and 1.2?3.0 ?m in length and were motile by means of peritrichous flagella. Naphthalene was utilized as the sole carbon and energy source, and the transcription of a putative aromatic-ring hydroxylating gene was inducible by naphthalene. The major component of cellular fatty acids was summed feature 8 (C18:1?7c and/or C18:1?6c), and significant proportions of C18:0 and C19:0 cyclo ?8cis were also found. The major respiratory quinone was ubiquinone-10. The G+C content of the DNA was 60.3?60.9 mol%. Phylogenetic analyses by studying sequence information on the housekeeping atpD, dnaK, glnII, gyrB, and recA genes as well as on 16S rRNA genes and the 16S-23S rDNA internal transcribed spacer region revealed that the strains grouped with members of the genus Rhizobium, with Rhizobium selenitireducens as their closest relative but formed a distinct lineage at the species level. This was confirmed by genomic DNA-DNA hybridization studies. These phenotypic, genotypic, and phylogenetic data strongly suggest that our isolates should be classified under a novel species of the genus Rhizobium. Thus, we propose the name Rhizobium naphthalenivorans sp. nov. to accommodate the novel isolates. The type strain is TSY03b(T) (= NBRC 107585T = KCTC 23252T). PMID:22878739

  5. Efeito residual da vinhaça na população autóctone de Rhizobium do solo Residual effects of sugar cane vinasse on indigenous Rhizobia

    OpenAIRE

    Eli Sidney Lopes; Sonia Cristina Perón; Edilberto Princi Portugal; Antonio Roberto Giardini

    1986-01-01

    A adição de vinhaça na cultura canavieira tem sido praticada em áreas próximas às usinas de cana. Seria de interesse a avaliação do efeito da vinhaça no Rhizobium presente no solo (autóctone), uma vez que leguminosas têm sido indicadas para cultivo intercalar com a cana. Um experimento foi conduzido em casa de vegetação, com o objetivo de verificar a influência da aplicação contínua, durante três anos, de concentrações crescentes de vinhaça (0, 100 e 1.000 m³/ha/ano), co...

  6. Role of Rhizobium endoglucanase CelC2 in cellulose biosynthesis and biofilm formation on plant roots and abiotic surfaces

    OpenAIRE

    Robledo, M.; Rivera, L.; Jime?nez-zurdo, Jose I.; Rivas, R.; Dazzo, F.; Vela?zquez, E.; Marti?nez-molina, E.; Hirsch, Ann M.; Mateos, Pedro F.

    2012-01-01

    Abstract Background The synthesis of cellulose is among the most important but poorly understood biochemical processes, especially in bacteria, due to its complexity and high degree of regulation. In this study, we analyzed both the production of cellulose by all known members of the Rhizobiaceae and the diversity of Rhizobium celABC operon predicted to be involved in cellulose biosynthesis. We also investigated the involvement in cellulose production and biofilm formation of celC gene encodi...

  7. Extracellular polysaccharides are involved in the attachment of Azospirillum brasilense and Rhizobium leguminosarum to arbuscular mycorrhizal structures

    OpenAIRE

    Perotto, S.; Bonfante, P.; Balestrini, R.; Andreotti, S.; Bianciotto, V.

    2009-01-01

    Arbuscular mycorrhizal (AM) fungi, one of the most important component of the soil microbial community, establish physical interactions with naturally occurring and genetically modified bacterial biofertilizers and biopesticides, commonly referred to as plant growth-promoting rhizobacteria (PGPR). We have used a genetic approach to investigate the bacterial components possibly involved in the attachment of two PGPR (Azospirillum and Rhizobium) to AM roots and AM fungal structures. Mutants aff...

  8. PssP2 Is a Polysaccharide Co-Polymerase Involved in Exopolysaccharide Chain-Length Determination in Rhizobium leguminosarum

    OpenAIRE

    Marczak, Ma?gorzata; Matysiak, Paulina; Kutkowska, Jolanta; Skorupska, Anna

    2014-01-01

    Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes iden...

  9. Purification and Characterization of the Lipid A 1-Phosphatase LpxE of Rhizobium leguminosarum*S?

    OpenAIRE

    Karbarz, Mark J.; Six, David A.; Raetz, Christian R. H.

    2009-01-01

    LpxE, a membrane-bound phosphatase found in Rhizobium leguminosarum and some other Gram-negative bacteria, selectively dephosphorylates the 1-position of lipid A on the outer surface of the inner membrane. LpxE belongs to the family of lipid phosphate phosphatases that contain a tripartite active site motif and six predicted transmembrane helices. Here we report the purification and characterization of R. leguminosarum LpxE. A modified lpxE gene, encoding a protein ...

  10. Phenotype profiling of Rhizobium leguminosarum bv. trifolii clover nodule isolates reveal their both versatile and specialized metabolic capabilities

    OpenAIRE

    Mazur, Andrzej; Stasiak, Graz?yna; Wielbo, Jerzy; Koper, Piotr; Kubik-komar, Agnieszka; Skorupska, Anna

    2013-01-01

    Rhizobium leguminosarum bv. trifolii (Rlt) are soil bacteria inducing nodules on clover, where they fix nitrogen. Genome organization analyses of 22 Rlt clover nodule isolates showed that they contained 3–6 plasmids and majority of them possessed large (>1 Mb), chromid-like replicon with exception of four Rlt strains. The Biolog phenotypic profiling comprising utilization of C, N, P, and S sources and tolerance to osmolytes and pH revealed metabolic versatility of the Rlt strains. Statisti...

  11. Lipid A biosynthesis in Rhizobium leguminosarum: role of a 2-keto-3-deoxyoctulosonate-activated 4' phosphatase.

    OpenAIRE

    Price, N. P.; Jeyaretnam, B.; Carlson, R. W.; Kadrmas, J. L.; Raetz, C. R.; Brozek, K. A.

    1995-01-01

    Lipid A from several strains of the N2-fixing bacterium Rhizobium leguminosarum displays significant structural differences from Escherichia coli lipid A, one of which is the complete absence of phosphate groups. However, the first seven enzymes of E. coli lipid A biosynthesis, leading from UDP-GlcNAc to the phosphorylated intermediate, 2-keto-3-deoxyoctulosonate (Kdo2)-lipid IVA, are present in R. leguminosarum. We now describe a membrane-bound phosphatase in R. leguminosarum extracts that r...

  12. Differential roles of HypC and HupF proteins for hydrogenase synthesis in Rhizobium leguminosarum.

    OpenAIRE

    Albareda Contreras, Marta; Manyani, Hamid; Brito Lopez, Maria Belen; Bo?ck, August; Imperial Ro?denas, Juan; Ruiz Argu?eso, Tomas-andres; Palacios Alberti, Jose Manuel

    2010-01-01

    Some diazotrophic bacteria induce [NiFe] hydrogenases to recycle the hydrogen evolved by nitrogenase during the nitrogen fixation process. Biosynthesis of Rhizobium leguminosarum [FeNi] hydrogenase requires a number of accessory proteins (products of hup and hyp genes) that mediate the incorporation of Ni and Fe into the active site. Among them, HypC-paralog HupF and HupK are present in bacteria that synthesize hydrogenase in the presence of oxygen. Hydrogenase activity in mutant strains ...

  13. Identification of Rhizobium leguminosarum genes and signal compounds involved in the induction of early nodulin gene expression.

    OpenAIRE

    Scheres, B. J. G.; Wiel, C.; Zalensky, A.; Hirsch, A.; Kammen, A.; Bisseling, T.

    1989-01-01

    The process of root nodule formation on legumes, induced by Rhizobium, can be looked upon as a sequence of several distinct steps. These steps have been defined by cytological studies on developing wild-type root nodules, and by analyses of nodules formed by either plant or bacterial mutants. Nowadays attachment of bacteria, root hair deformation and curling, induction of cortical cell division, infection thread formation, nodule development, bacterial release from infection th...

  14. Effects of Carrier and Temperature on Survival of Rhizobium spp. in Legume Inocula: Development of an Improved Type of Inoculant †

    OpenAIRE

    Kremer, Robert J.; Peterson, Harold L.

    1983-01-01

    The effects of inoculant carrier, temperature, and storage period on the survival of Rhizobium strains were determined by plate count and most-probable-number analyses. Preliminary experiments showed that survival of rhizobia was affected by each of these factors and their interactions. Results of further studies indicated that six strains of rhizobia survived better at high temperatures when lyophilized and suspended in an oil carrier as compared to finely ground peat. The oil base inocula c...

  15. The beneficial effect of dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover

    OpenAIRE

    Lin, Xg; Hao, Wy; Wu, Th

    1993-01-01

    Investigation on the effect of phosphorus on vesicular-arbuscular mycorrhizal infection, and dual inoculation of vesicular-arbuscular mycorrhizae + rhizobium on growth of white clover under field microplots and pot experiments was conducted on fluvo-aquic soils of semi-arid region in north China. The results showed that 60 kg P205 ha in form of superphosphate was the most favorable phosphorus level for vesicular-arbuscular mycorrhizal infection ; mycorrhizal infection, nodulation, dry weight ...

  16. Evidence Suggesting Protozoan Predation on Rhizobium Associated with Germinating Seeds and in the Rhizosphere of Beans (Phaseolus vulgaris L.)

    OpenAIRE

    Ramirez, Carlos; Alexander, Martin

    1980-01-01

    Changes in populations of microorganisms around germinating bean (Phaseolus vulgaris L.) seeds, in the rhizosphere of bean, and in a model rhizosphere were studied. Strains of Rhizobium phaseoli that were resistant to streptomycin and thiram were used, and as few as 300 R. phaseoli cells per g of soil could be enumerated with a selective medium that was devised. A direct role was not evident for bacterial competitors, lytic bacteria, antibiotic-producing microorganisms, bacteriophages, and Bd...

  17. Biosynthesis of Rhizobium trifolii capsular polysaccharide: enzymatic transfer of pyruvate substitutions into lipid-bound saccharide intermediates.

    OpenAIRE

    Gardiol, A. E.; Dazzo, F. B.

    1986-01-01

    The activity of capsular polysaccharide pyruvyltransferase catalyzing the pyruvylation of acidic heteropolysaccharide was measured in Rhizobium trifolii 843 and 0403 rif. This enzyme activity was determined with EDTA-treated cells, uridine diphosphate-sugar precursors, and phosphoenol [1-14C]pyruvate. Activity was measured by the incorporation of radioactivity into organic solvent-soluble glycoconjugates. Enzymatic pyruvylation of capsular polysaccharide occurred from phosphoenolpyruvate at t...

  18. Identification and Characterization of RibN, a Novel Family of Riboflavin Transporters from Rhizobium leguminosarum and Other Proteobacteria

    OpenAIRE

    Garci?a Angulo, Vi?ctor A.; Bonomi, Herna?n R.; Posadas, Diana M.; Serer, Mari?a I.; Torres, Alfredo G.; Zorreguieta, A?ngeles; Goldbaum, Fernando A.

    2013-01-01

    Rhizobia are symbiotic bacteria able to invade and colonize the roots of legume plants, inducing the formation of nodules, where bacteria reduce atmospheric nitrogen (N2) to ammonia (NH3). Riboflavin availability influences the capacity of rhizobia to survive in the rhizosphere and to colonize roots. In this study, we identified the RL1692 gene of Rhizobium leguminosarum downstream of a flavin mononucleotide (FMN) riboswitch. RL1692 encodes a putative transmembrane permease with two EamA doma...

  19. Rhizobium leguminosarum CFN42 genetic regions encoding lipopolysaccharide structures essential for complete nodule development on bean plants.

    OpenAIRE

    Cava, J. R.; Elias, P. M.; Turowski, D. A.; Noel, K. D.

    1989-01-01

    Eight symbiotic mutants defective in lipopolysaccharide (LPS) synthesis were isolated from Rhizobium leguminosarum biovar phaseoli CFN42. These eight strains elicited small white nodules lacking infected cells when inoculated onto bean plants. The mutants had undetectable or greatly diminished amounts of the complete LPS (LPS I), whereas amounts of an LPS lacking the O antigen (LPS II) greatly increased. Apparent LPS bands that migrated between LPS I and LPS II on sodium dodecyl sulfate-polya...

  20. Protein-Protein Interactions within Type III Secretion System-Dependent Pili of Rhizobium sp. Strain NGR234?

    OpenAIRE

    Saad, Maged M.; Staehelin, Christian; Broughton, William J.; Deakin, William J.

    2007-01-01

    Pili synthesized by the type III secretion system of Rhizobium species strain NGR234 are essential for protein secretion and thus for efficient symbiosis with many legumes. Isolation and partial purification of these pili showed that they are composed of at least three proteins, NopA, NopB, and NopX. Using biochemical assays, we show here that these proteins interact directly with one another.

  1. Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress

    OpenAIRE

    Gomes Douglas; Batista Jesiane Stefânia da Silva; Schiavon Aline; Andrade Diva; Hungria Mariangela

    2012-01-01

    Abstract Background Rhizobium tropici strain PRF 81 (= SEMIA 4080) has been used in commercial inoculants for application to common-bean crops in Brazil since 1998, due to its high efficiency in fixing nitrogen, competitiveness against indigenous rhizobial populations and capacity to adapt to stressful tropical conditions, representing a key alternative to application of N-fertilizers. The objective of our study was to obtain an overview of adaptive responses to heat stress of strain PRF 81, ...

  2. Two rhizobacterial strains, individually and in interactions with Rhizobium sp., enhance fusarial wilt control, growth, and yield in pigeon pea.

    Science.gov (United States)

    Dutta, Swarnalee; Morang, Pranjal; Kumar S, Nishanth; Dileep Kumar, B S

    2014-09-01

    A Pseudomonas aeruginosa strain, RRLJ 04, and a Bacillus cereus strain, BS 03, were tested both individually and in combination with a Rhizobium strain, RH 2, for their ability to enhance plant growth and nodulation in pigeon pea (Cajanus cajan L.) under gnotobiotic, greenhouse and field conditions. Both of the rhizobacterial strains exhibited a positive effect on growth in terms of shoot height, root length, fresh and dry weight, nodulation and yield over the non-treated control. Co-inoculation of seeds with these strains and Rhizobium RH 2 also reduced the number of wilted plants, when grown in soil infested with Fusarium udum. Gnotobiotic studies confirmed that the suppression of wilt disease was due to the presence of the respective PGPR strains. Seed bacterization with drug-marked mutants of RRLJ 04 and BS 03 confirmed their ability to colonize and multiply along the roots. The results suggest that co-inoculation of these strains with Rhizobium strain RH 2 can be further exploited for enhanced growth, nodulation and yield in addition to control of fusarial wilt in pigeon pea. PMID:25224506

  3. Symbiont effect of Rhizobium bacteria and vesicular arbuscular mycorrhizal fungi on Pisum sativum in recultivated mine spoils

    Energy Technology Data Exchange (ETDEWEB)

    Biro, B.; Voros, I.; Kovespechy, K.; Szegi, J. (Hungarian Academy of Sciences, Budapest (Hungary). Soil Science and Agricultural Chemistry Research Institute)

    The frequency (F%) of spontaneous endomycorrhizal fungal infection (AMF) and the root modulation of Pisum sativum L, was studied after 8 and 15 years of recultivation in 4 soils (andesitic tuff yellow sand, yellow clay, and grey clay) disturbed by mining activities. The effects of Rhizobium inoculation and the interaction of both microsymbionts with plant production were also examined along with humus content and the humus stability coefficient, in the following variations: control, NPK fertilizer, NPK+lignite, NPK+straw and sewage sludge. Dump spoils originating from deep geological layers were poor in organic materials. After 12 years of recultivation, the humus content increased significantly. No such increase was noted in grey clay and the natural, brown forest soil used as an undisturbed (control) sample. The degradation of soils by mining brings about a decrease in the rhizobial and mycorrhizal population, so the number of spontaneous Rhizobium nodules is relatively low and does not influence the yield of peas. Inoculation with a selected effective strain of Rhizobium leguminosarum bv. viceae, however, enhanced dry matter production in these microbiologically degraded soils. Although the frequency of AMF infection was also higher after rhizobial inoculation, no positive correlation was found between dry matter production of peas and the F% of AMF. Spoils treated with lignite, straw, and sewage sludge had an especially high level of spontaneous mycorrhizal populations, indicating that organic materials had a favorable effect on the recultivation processes and fertility of mine spoils.

  4. Quantitative analysis of the naringenin-inducible proteome in Rhizobium leguminosarum by isobaric tagging and mass spectrometry.

    Science.gov (United States)

    Tolin, Serena; Arrigoni, Giorgio; Moscatiello, Roberto; Masi, Antonio; Navazio, Lorella; Sablok, Gaurav; Squartini, Andrea

    2013-06-01

    The rhizobium-legume interaction is a critical cornerstone of crop productivity and environmental sustainability. Its potential improvement relies on elucidation of the complex molecular dialogue between its two partners. In the present study, the proteomic patterns of gnotobiotic cultures of Rhizobium leguminosarum bv. viciae 3841 grown for 6 h in presence or absence of the nod gene-inducing plant flavonoid naringenin (10 ?M) were analyzed using the iTRAQ approach. A total of 1334 proteins were identified corresponding to 18.67% of the protein-coding genes annotated in the sequenced genome of bv. viciae 3841. The abundance levels of 47 proteins were increased upon naringenin treatment showing fold change ratios ranging from 1.5 to 25 in two biological replicates. Besides the nod units, naringenin enhanced the expression of a number of other genes, many of which organized in operons, including ?(1-2) glucan production and secretion, succinoglycan export, the RopA outer membrane protein with homology to an oligogalacturonide-specific porin motif, other enzymes for carbohydrate and amino acid metabolism, and proteins involved in the translation machinery. Data were validated at the transcriptional and phenotypic levels by RT-PCR and an assay of secreted sugars in culture supernatants, respectively. The current approach provides not only a high-resolution analysis of the prokaryotic proteome but also unravels the rhizobium molecular dialogue with legumes by detecting the enhanced expression of several symbiosis-associated proteins, whose flavonoid-dependency had not yet been reported. PMID:23580418

  5. Calcium-dependent regulation of genes for plant nodulation in Rhizobium leguminosarum detected by iTRAQ quantitative proteomic analysis.

    Science.gov (United States)

    Arrigoni, Giorgio; Tolin, Serena; Moscatiello, Roberto; Masi, Antonio; Navazio, Lorella; Squartini, Andrea

    2013-11-01

    Rhizobia, the nitrogen-fixing bacterial symbionts of legumes, represent an agricultural application of primary relevance and a model of plant-microbe molecular dialogues. We recently described rhizobium proteome alterations induced by plant flavonoids using iTRAQ. Herein, we further extend that experimentation, proving that the transient elevation in cytosolic calcium is a key signaling event necessary for the expression of the nodulation (nod) genes. Ca(2+) involvement in nodulation is a novel issue that we recently flagged with genetic and physiological approaches and that hereby we demonstrate also by proteomics. Exploiting the multiple combinations of 4-plex iTRAQ, we analyzed Rhizobium leguminosarum cultures grown with or without the nod gene-inducing plant flavonoid naringenin and in the presence or absence of the extracellular Ca(2+) chelator EGTA. We quantified over a thousand proteins, 189 of which significantly altered upon naringenin and/or EGTA stimulation. The expression of NodA, highly induced by naringenin, is strongly reduced when calcium availability is limited by EGTA. This confirms, from a proteomic perspective, that a Ca(2+) influx is a necessary early step in flavonoid-mediated legume nodulation by rhizobia. We also observed other proteins affected by the different treatments, whose identities and roles in nodulation and rhizobium physiology are likewise discussed. PMID:24041410

  6. Evolución del tamaño y del peso del fruto de kiwi (Actinidia deliciosa (A. Chev.) Liang et Fergurson) cultivar "Hayward" durante la etapa final de crecimiento / Evolution of the size and weight of "Hayward" kiwifruit (Actinidia deliciosa (A. Chev.) Liang et Fergurson) cultivar during the final stage of growth

    Scientific Electronic Library Online (English)

    Mónica G, Ontivero Urquiza; Héctor Abel, Altube; Leonardo, Baghin.

    2012-12-01

    Full Text Available Se realizó un ensayo durante tres años consecutivos con el fin de monitorear la evolución del tamaño y del peso de los frutos de una plantación comercial de kiwi variedad Hayward ubicada en la provincia de Córdoba. El objetivo fue determinar la evolución del peso y del tamaño del fruto durante la et [...] apa final de crecimiento. Se seleccionaron doce plantas representativas y se realizaron cosechas durante cuatro semanas en tres años sucesivos desde el 4/3 al 24/3, a partir de que los frutos alcanzaron 5° Brix. Las variables evaluadas fueron: peso del fruto, longitud del fruto, diámetro mayor y menor al momento de la cosecha y luego de seis días a temperatura ambiente. El peso del fruto se incrementó desde un valor mínimo de 83,71 g a 121,1 g. La pérdida de peso luego de seis días fue desde un mínimo de 3,11 g a un máximo de 6,01 g. La longitud pasó de 54,73 mm a 64,20 mm. El diámetro mayor pasó de 52,12 mm a 59,7 mm, presentando una disminución después de seis días de un mínimo de 0,27 mm a un máximo 7,12 mm. El diámetro menor pasó de 42 mm a 54,41 mm entre la primera y la cuarta cosecha. Todas las variables presentaron un incremento en la medida en que atrasaba la cosecha, lo que justifica una cosecha más tardía, en función del tamaño de los frutos. Abstract in english A follow-up trial of the evolution of fruit size and fruit weight of a "Hayward" kiwifruit cultivar was conducted in a commercial plantation in the province of Córdoba during three consecutive years. Twelve representative plants were selected and kiwifruit were harvested during three consecutive yea [...] rs, during four weeks, from March 4th to March 24th, when they reached 5° Brix. The examined variables were fruit weight, fruit length, major diameter and minor diameter of the fruit at the moment of harvest and after six days at room temperature. Fruit weight increased from a minimum value of 83.71 g to 121.1 g. After six days, the weight loss varied from a minimum of 3.11 g to a maximum of 6.01 g. Fruit length went from 54.73 mm to 64.20 mm. The major diameter varied from 52.12 mm to 59.7 mm presenting a decrease after six days from a minimum of 0.27 mm to a maximum of 7.12 mm. The minor diameter went from 42 mm to 54.41 mm between the first and the fourth harvest. All the variables showed an increase as the harvest was delayed, which seems to justify a later harvest considering the size of the fruit.

  7. Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.)

    OpenAIRE

    Ormeño-Orrillo Ernesto; Menna Pâmela; Almeida Luiz Gonzaga P; Ollero Francisco Javier; Nicolás Marisa Fabiana; Pains Rodrigues Elisete; Shigueyoshi Nakatani Andre; Silva Batista Jesiane Stefânia; Oliveira Chueire Ligia Maria; Souza Rangel Celso; Ribeiro Vasconcelos Ana Tereza; Megías Manuel; Hungria Mariangela; Martínez-Romero Esperanza

    2012-01-01

    Abstract Background Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are ?-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris) in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobia...

  8. INTERACCIÓN RHIZOBIUM LEGUMINOSARUM BV TRIFOLII Y HONGOS MICORRÍCICOS EN UN ANDISOL CON DIFERENTES NIVELES DE SATURACIÓN DE ALUMINIO INTERACTION OF RHIZOBIUM LEGUMINOSARUM BV TRIFOLII AND MYCORRHIZAL FUNGI IN AN ANDISOL AT DIFFERENT LEVELS OF ALUMINIUM SATURATION

    Directory of Open Access Journals (Sweden)

    Claudia G Castillo R

    2008-01-01

    Full Text Available La fitotoxicidad por Al es una seria limitante de la productividad de praderas crecidas sobre suelos volcánicos afectando la nodulación y efectividad de los Rhizobium. El objetivo del estudio consistió en seleccionar cepas de Rhizobium de colección para estudiar su efectividad en Trifolium repens crecido en un Andisol con cepas nativas y distinta saturación de Al. Para ello se evaluó previamente en caldo nutritivo la tolerancia a la acidez y toxicidad por Al de 12 cepas de colección mediante control de curvas de crecimiento. Paralelamente, se inocularon los Rhizobium en un Andisol para evaluar su efectividad mediante rendimiento de Trifolium pratense. Se seleccionaron las cepas R-109, R-113 y R-115 para inocularlas en el Andisol utilizando cuatro tratamientos: suelo adicionado de 2 Mg CaCO3 ha-1 (SAl1, un testigo (SAl2 y suelo adicionado de dos niveles de saturación Al (SAl1, SAl4 utilizando Trifolium repens como hospedero. Las plantas mostraron capacidad para asociarse con las especies inoculadas presentando mayor efectividad R-113-SAl1 sinergismo positivo expresado en variables microbiológicas como nodulación (16 nódulos maceta-1, esporas de hongos micorrícicos arbusculares, HMA (384 esporas 100g-1, colonización HMA (45% junto con variables agronómicas alcanzándose un incremento de biomasa foliar (93,5% frente al testigo. Niveles más elevados de Al afectaron la inoculación con cepas de colección; así, con R-109 se obtuvo el menor crecimiento radical y nodulación respecto al suelo natural mientras que R-113 fue la cepa más efectiva.Aluminium phytotoxicity is a serious limitation of the productivity of prairies growing on volcanic soil by affecting nodulation and effectiveness of Rhizobium. The aim of this study was to select Rhizobium strains to determine the effect as inoculant on Trifolium repens cropped in an Andisol with different aluminium saturation levels. Acidity tolerance (pH 4.5 and 6.0 of twelve Rhizobium strains of collection at three Al levels (100, 200, 300 µM was evaluated in mineral nutritive medium vitro. Simultaneously, in a greenhouse trial, strains effectivity were tested by inoculation of Trifolium pratense growing in an acidic Andisol and compared with dry matter accumulation produced by native strains. According to the results of this two trials, three Rhizobium strains (R-109, R-113 and R-115 were selected to study the effect of their inoculation on Trifolium repens growth cropped in an Andisol at four Al saturation levels (SAl1 to SAl4. In addition, the effect on arbuscular mycorrhizal propagules was also studied. Plants showed different capacity for association with the inoculated strains giving the best response R-113 at SAl1 level with positive synergism expressed by microbiological parameters such as high nodulation (16 nodules pot-1, AMF spore number (384 spores 100 g-1, root colonization percentage (45%, together with agronomical variables with an increase of aerial phytomass (93,5% in comparison with the control. Higher Al levels had an deleterious effect on the inoculation of collection strains; therefore, with R-109 strain inoculation the smallest root growth and nodulation were observed in comparison with soil with native strains whereas R-113 was the more effective one.

  9. Influence of host cultivars and Rhizobium species on the growth and symbiotic performance of Phaseolus vulgaris under salt stress.

    Science.gov (United States)

    Bouhmouch, Ilham; Souad-Mouhsine, Bouchra; Brhada, Fatiha; Aurag, Jamal

    2005-10-01

    In order to study the effect of salt stress on the Rhizobium-common bean symbiosis, we investigated the response of both partners, separately and in symbiosis. The comparison of the behaviour of five cultivars of Phaseolus vulgaris differing in seed colour, growing on nitrates and different concentrations of NaCl, showed genotypic variation with respect to salt tolerance. Coco Blanc was the most sensitive cultivar, whereas SMV 29-21 was the most tolerant one. At the Rhizobium level, two strains previously selected for their salt tolerance were used: Rhizobium tropici strain RP163 and Rhizobium giardinii strain RP161. Their relative growth was moderately decreased at 250mM NaCl, but they were able to grow at a low rate in the presence of 342 mM NaCl. Their viability at the minimal inhibitory concentration was slightly affected. The effect of salinity on Rhizobium-plant association was studied by using the tolerant variety SMV 29-21 and the sensitive one Coco Blanc inoculated separately with both strains. In the absence of salinity, the strains induced a significantly higher number of nodules on the roots of the cultivar SMV 29-21 compared to those of Coco Blanc. Concerning effectiveness, both strains were similarly effective with SMV 29-21, but not with Coco Blanc. In the presence of salinity, Coco Blanc was more severely affected when associated with RP163 than with RP161. Salinity affected the nodulation development more than it affected the infection steps. Neither of the two strains was able to nodulate SMV 29-21 under saline conditions, in spite of the fact that this was considered the most salt-tolerant variety. The unsuccessful nodulation of SMV 29-21 could be related to the inhibition by salt of one or more steps of the early events of the infection process. In conclusion, N-fixing plants were found to be more sensitive to salt stress than those depending on mineral nitrogen. Evidence presented here suggests that a best symbiotic N2 fixation under salinity conditions could be achieved if both symbiotic partners, as well as the different steps of their interaction (early events, nodule formation, activity, etc.), are all tolerant to this stress. PMID:16255168

  10. Selection of Rhizobium strain from Wonogiri, Central Java on the growth of soybean (Glycine max L. on the sand sterile medium in greenhouse

    Directory of Open Access Journals (Sweden)

    SRI PURWANINGSIH

    2005-07-01

    Full Text Available An experiment on the selection of Rhizobium strain from Wonogiri, Central Java on the growth of soybean (Glycine max L. on the sand sterile medium in green house. The aim of the experiment the selection and potency of the Rhizobium strain to increase the growth of soybean. The experiment was carried out in green house condition in Microbiology Division, Research Center for Biology-LIPI with sterile sand medium. The research design was Completely Randomized Design with three replications for each treatment. The Rhizobium strains used were 1 W (isolated from bean, Vigna radiata, 2 W (isolated from soybean, 3 W (isolated from bean, 4 W (isolated from soybean, 5 W (isolated from soybean, 6 W (isolated from peanut, Arachis hypogaea, 7 W (isolated from peanut, 8 W (isolated from peanut, the controls were uninoculated with Rhizobium strain and without urea fertilizer (K1, uninoculated and with urea fertilizer equal 100 kg/ha (K2. The plants were harvested after 50 days, the variable of investigation were the dry weight of canopy, roots, nodules root, total plants, number of nodules and ‘symbiotic capacity”. The results showed that all of experiment plant which be inoculated with Rhizobium able to form nodule. Strain of 2 W (isolated from soybean has given the best effects on the growth of soybean.

  11. Final Environmental Statement related to the operation of Wolf Creek Generating Station, Unit No. 1. Docket No. STN 50-482, Kansas Gas and Electric Company, et al

    International Nuclear Information System (INIS)

    This final environmental statement contains the second assessment of the environmental impact associated with operation of Wolf Creek Generating Station Unit 1 pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR Part 51, as amended, of the NRC's regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial- and aquatic-ecological impacts will be small. Air-quality impacts will also be small. However, steam fog from the station's cooling lake has the potential for reducing visibility over nearby roads and bridges. A fog-monitoring program for roads and bridges near the lake has been recommended. Impacts to historic and prehistoric sites will be negligible. Chemical discharges to the Neosho River are expected to have no appreciable impacts on water quality under normal conditions and will be required to meet conditions of the station's NPDES permit. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission line facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial. The action called for is the issuance of an operating license for the Wolf Creek Generating Station Unit 1

  12. Perturabation of nodular operation under salt and water deficit stress in rhizobium common bean symbiosis

    International Nuclear Information System (INIS)

    This work aims at the search for markers of tolerance to the osmotic stress and nodular efficiency of symbiosis Haricot Rhizobium. Thus, after having fixed the best period of hydroponic culture, we showed that a severe salt treatment generated an inhibition of the parameters of growth and nodulation. These inhibitions are accompanied by an inhibition of the enzymatic activities: ascorbate peroxidase (APX) and catalase (CAT), but an activation of peroxidase (POX) and superoxide dismutase (SOD), suggesting that these two antioxydants can be biochemical markers of the tolerance to salinity. To check the validity of these markers and to see the participation of the vegetable genotype in the response to the stress, we compared the effect of two concentrations salt 25 and 50 mM NaCe at two contrasting genotypes BAT477 tolerant and sensitive COCOT. This study illustrates the role of the vegetable genotype in the tolerance and efficiency and emphasize a significant result that SOD and POX constitute biochemical markers of tolerance to salinity. In order to ensure itself of the validity of this assumption in the event of water deficit stress, a treatment of 50 mM mannitol is applied to 16 symbioses formed by four genotypes of bean BAT477, COCOT, Flamingo and BRB17 inoculated by four strains of rhizobium CIAT899, 12 to 3, 1 to 6 and 8 to 3. This study permits us to make a screening of these symbioses according to their efficiency and their tolerance based on parameters of growteir tolerance based on parameters of growth, of fixing and extent of the antioxydant enzymatic activities. It gets clear that the response of enzymatic antioxydants is in relation to the intrinsic potentialities of the partners of symbioses and appears to act as of the first stages of recognition plants bacterium. It will be retained that activities POX and SOD are markers of nodular tolerance. The CAT is the enzyme most connected to each partner of symbiosis and the APX would play a rather functional role. The heterogeneity of found answer indicates the great importance of the interaction of the two partners of symbiosis and of their contribution in great variability. The whole of results permits us to choose contrasting symbioses for better elucidating the mechanisms of nodular operation in response to the osmotic stress. (author). 282 refs

  13. Chrysoeriol and Luteolin Released from Alfalfa Seeds Induce nod Genes in Rhizobium meliloti1

    Science.gov (United States)

    Hartwig, Ueli A.; Maxwell, Carl A.; Joseph, Cecillia M.; Phillips, Donald A.

    1990-01-01

    Flavonoid signals from alfalfa (Medicago sativa L.) seed and root exudates induce transcription of nodulation (nod) genes in Rhizobium meliloti. The flavone luteolin previously was isolated from alfalfa seeds by other workers and identified as the first nod gene inducer for R. meliloti. Our recent study of `Moapa 69' alfalfa root exudates found no luteolin but did identify three other nod gene inducers: 4,4?-dihydroxy-2?-methoxychalcone, 4?,7-dihydroxyflavone, and 4?,7-dihydroxyflavanone. The goal of the current study was to identify and quantify nod gene-inducing flavonoids that may influence Rhizobium populations around a germinating alfalfa seed. Aqueous rinses of Moapa 69 alfalfa seeds were collected and assayed for induction of a nodABC-lacZ fusion in R. meliloti. During the first 4 hours of imbibition, total nod gene-inducing activity was released from seeds at 100-fold higher rates than from roots of 72-hour-old seedlings. Five flavonoids were purified and identified by spectroscopic analyses (ultraviolet/visible absorbance, proton nuclear magnetic resonance, and mass spectroscopy) and comparison with authentic standards. Two very active nod gene-inducing flavonoids, chrysoeriol (3?-methoxyluteolin) and luteolin, were identified in seed rinses. Luteolin required a higher concentration (18 nanomolar) than chrysoeriol (5 nanomolar) for half-maximum induction of nodABC-lacZ in R. meliloti, and both were less active than 4,4?-dihydroxy-2?-methoxychalcone (2 nanomolar) from root exudates. Seeds exuded three other luteolin derivatives: luteolin-7-O-glucoside, 5-methoxyluteolin, and 3?,5-dimethoxyluteolin. Their combined quantities were 24-fold greater than that of luteolin plus chrysoeriol. Most nod gene-inducing activity of these luteolin derivatives apparently is associated with degradation to luteolin and chrysoeriol. However, their presence in large quantities suggests that they may contribute significantly to nod gene-inducing activity in the soil. These results indicate the importance of germinating seeds as a source of nod gene-inducing flavonoids and emphasize the quantitative and qualitative differences in those compounds around the seed and root. PMID:16667231

  14. “Item perrexil, mostarda, lechugas et rauanos”. Notas sobre la alimentación de mineros alemanes en Pamplona a finales del siglo XIV (1392

    Directory of Open Access Journals (Sweden)

    Serrano Larráyoz, Fernando

    2008-06-01

    Full Text Available The present article represents an approximation to the food of some German miners settled in Pamplona at the end of the 14th century, to carry out a series of assays intended to determine the kind of metals present in the ore and their actual proportion, with the purpose to verify the profitability of some seams found at Five Villages. Their food accounting for approximately one and a half months, give us first hand information of their habits and of those sharing the table with them. To a certain extent, it is possible to extrapolate these practices to the ones of part of Navarra's salary earners. In them, we could sense certain customs or preferences characteristic of North Europe.

    El presente artículo es una aproximación a la alimentación de unos mineros alemanes que, a finales del siglo XIV, se asientan en Pamplona con el fin de realizar una serie de ensayos (averiguación de los metales que contiene la mena —el mineral metalífero—, y la proporción en que cada uno está con el peso de ella en los que determinar la rentabilidad de algunos filones mineros encontrados en la zona de las Cinco Villas. Las cuentas de los gastos que realizan en alimentación, en aprox. mes y medio, nos acercan de primera mano a los hábitos de estos hombres y de quienes les acompañan en la mesa. Unas prácticas que es posible extrapolar, en cierta medida, a parte de la menestralía navarra, y en las que podemos intuir ciertas costumbres (o gustos propios de la Europa del Norte.

  15. Genomic analysis of cyclic-di-GMP-related genes in rhizobial type strains and functional analysis in Rhizobium etli

    OpenAIRE

    Gao, Shanjun; Ben Romdhane, Samir; Beullens, Serge; Kaever, Volkhard; Lambrichts, Ivo; Fauvart, Maarten; Michiels, Jan

    2014-01-01

    Rhizobia are soil bacteria that can fix nitrogen in symbiosis with leguminous plants or exist free living in the rhizosphere. Crucial to their complex lifestyle is the ability to sense and respond to diverse environmental stimuli, requiring elaborate signaling pathways. In the majority of bacteria, the nucleotide-based second messenger cyclic diguanosine monophosphate (c-di-GMP) is involved in signal transduction. Surprisingly, little is known about the importance of c-di-GMP signaling in rhi...

  16. Study of final states involving 2 particle jets and missing energy with the DELPHI detector at LEP; Etude des etats finals contenant deux jets de particules et de l'energie manquante avec le detecteur DELPHI a LEP

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer Ribas, E

    2000-05-09

    The observation of the Higgs boson would be of great importance for the understanding of the electroweak symmetry breaking. In the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM), the lightest Higgs boson is neutral and scalar, and its mass must be less than 130 GeV/c{sup 2}. In this thesis, we have studied events characterized by the presence of two particle jets and missing energy. This is a very clear signature of the production of the Higgs boson in association with a Z{sup 0} boson. This production is followed by the decay of the Higgs boson into a bb-bar pair and the Z{sup 0} boson in {nu}{nu}-bar pair. In these studies, it is important to detect all particles in order to achieve a good resolution in energy. For these reasons, we have devoted ourselves to improving DELPHI's hermeticity mainly in the regions located at 40 deg C and 140 deg C. Using the data collected by the DELPHI detector at LEP in 1998 and in 1999 at four different energies in the centre of mass ({radical}s = 189, 196, 200 and 202 GeV), no signal has been observed, allowing us to exclude the Higgs boson at 95 % confidence level up to a mass of: m{sub H} > 98.0 (98.5) GeV/c{sup 2} at 95% C.L. this analysis; m{sub H} > 103.9 (106.3) GeV/c{sup 2} at 95% C.L. DELPHI combined. The values in parentheses show the expected limits and indicate the sensitivity of the analysis. If these results are interpreted in the framework of the MSSM we obtain: m{sub h} > 85.0 (85.3) GeV/c{sup 2} at 95% C.L. Studying the same topology, we have also searched for a Higgs boson decaying into a pair of non detectable particles (Invisible Higgs) in association with a Z{sup 0} boson decaying into a quark/antiquark pair. In this case too, no signal has been observed, which can be translated into a lower limit on the mass of the Higgs boson at 95% confidence level: m{sub h{sub inv}} > 105.5 (105.3) GeV/c{sup 2} at 95% C.L. Finally, we have measured the production cross section of a pair of Z{sup 0} bosons where one decays to a quark/antiquark pair (all flavours) and the other to a pair of neutrinos. The result is in very good agreement with the value predicted by the Standard Model: {sigma}{sup NC02}/{sigma}{sup MS} = 0.94{+-}0.25 this analysis; {sigma}{sup NC02}/{sigma}{sup MS} = 1.04{+-}0.12 DELPHI combined. (author)

  17. Transfer of the symbiotic plasmid from Rhizobium leguminosarum biovar trifolii to Agrobacterium tumefaciens.

    Science.gov (United States)

    Abe, Mikiko; Kawamura, Ryoichi; Higashi, Shiro; Mori, Seiichiro; Shibata, Motoyoshi; Uchiumi, Toshiki

    1998-02-01

    This study examined the symbiotic properties of Agrobacterium transconjugants isolated by transferring a Tn5-mob-marked derivative of the 315 kb megaplasmid pRt4Sa from Rhizobium leguminosarum bv. trifolii 4S (wild-type strain) to Agrobacterium tumefaciens A136 as the recipient. The genetic characteristics of the AT4S transconjugant strains were ascertained by random amplified polymorphic DNA (RAPD) analyses and Southern hybridization using Tn5-mob and nod genes as probes. Several of these AT4S transconjugants carrying pRt4Sa were able to nodulate roots of the normal legume host, white clover. In addition, some AT4S transconjugant strains were able to induce nodules on other leguminous plants, including alfalfa and hairy vetch. A characteristic bacteroid differentiation was observed in clover and alfalfa nodules induced by the AT4S-series strains, although nitrogen-fixing activity (acetylene reduction) was not found. Furthermore, strain H1R1, obtained by retracing transfer of the pRt4Sa::Tn5-mob from strain AT4Sa to strain H1 (pRt4Sa cured derivative of 4S), induced Fix(+) nodules on clover roots. These results indicate the evidence that only nod genes can be expressed in the Agrobacterium background. PMID:12501295

  18. Osmotic control of glycine betaine biosynthesis and degradation in Rhizobium meliloti

    International Nuclear Information System (INIS)

    Intracellular accumulation of glycine betaine has been shown to confer an enhanced level of osmotic stress tolerance in Rhizobium meliloti. In this study, the authors used a physiological approach to investigate the mechanism by which glycine betaine is accumulated in osmotically stressed R. meliloti. Results from growth experiments, 14C labeling of intermediates, and enzyme activity assays are presented. The results provide evidence for the pathway of biosynthesis and degradation of glycine betaine and the osmotic effects on this pathway. High osmolarity in the medium decreased the activities of the enzymes involved in the degradation of glycine betaine but not those of enzymes that lead to its biosynthesis from choline. Thus, the concentration of the osmoprotectant glycine betaine is increased in stressed cells. This report demonstrates the ability of the osmolarity of the growth medium to regulate the use of glycine betaine as a carbon and nitrogen source or as an osmoprotectant. The mechanisms of osmoregulation in R. meliloti and Escherichia coli are compared

  19. Characterization of extrachromosomal replicons present in the extended host range Rhizobium sp. LPU83.

    Science.gov (United States)

    Torres Tejerizo, Gonzalo; Del Papa, María Florencia; de los Angeles Giusti, María; Draghi, Walter; Lozano, Mauricio; Lagares, Antonio; Pistorio, Mariano

    2010-11-01

    In several rhizobia, bacteria that inhabit the soil in free-living conditions and associate in symbiosis with the root of legumes as nitrogen-fixing organisms, plasmid DNA can constitute a high percentage of the genome. We have characterized acid-tolerant isolates of rhizobia-here represented by the strain Rhizobium sp. LPU83-that have an extended nodulation-host range including alfalfa, the common bean, and Leucena leucocephala. In this study we analyzed the plasmids of R. sp. LPU83 in order to characterize their role in the evolution of Medicago symbionts and their involvement in symbiotic behavior. The pLPU83a plasmid was found to be transmissible with no associated phenotypic traits. The symbiotic plasmid pLPU83b could be transferred at very low frequencies under laboratory conditions only when pLPU83a was present; could restore nodulation to a strain cured of its symbiotic plasmid, S. meliloti A818; but could not restore the full nitrogen fixation associated with alfalfa. PMID:20621118

  20. Diversity and specificity of Rhizobium leguminosarum biovar viciae on wild and cultivated legumes.

    Science.gov (United States)

    Mutch, Lesley A; Young, J Peter W

    2004-08-01

    The symbiotic partnerships between legumes and their root-nodule bacteria (rhizobia) vary widely in their degree of specificity, but the underlying reasons are not understood. To assess the potential for host-range evolution, we have investigated microheterogeneity among the shared symbionts of a group of related legume species. Host specificity and genetic diversity were characterized for a soil population of Rhizobium leguminosarum biovar viciae (Rlv) sampled using six wild Vicia and Lathyrus species and the crop plants pea (Pisum sativum) and broad bean (Vicia faba). Genetic variation among 625 isolates was assessed by restriction fragment length polymorphism (RFLP) of loci on the chromosome (ribosomal gene spacer) and symbiosis plasmid (nodD region). Broad bean strongly favoured a particular symbiotic genotype that formed a distinct phylogenetic subgroup of Rlv nodulation genotypes but was associated with a range of chromosomal backgrounds. Host range tests of 80 isolates demonstrated that only 34% of isolates were able to nodulate V. faba. By contrast, 89% were able to nodulate all the local wild hosts tested, so high genetic diversity of the rhizobial population cannot be ascribed directly to the diversity of host species at the site. Overall the picture is of a population of symbionts that is diversified by plasmid transfer and shared fairly indiscriminately by local wild legume hosts. The crop species are less promiscuous in their interaction with symbionts than the wild legumes. PMID:15245415

  1. Escherichia coli BdcA controls biofilm dispersal in Pseudomonas aeruginosa and Rhizobium meliloti

    Directory of Open Access Journals (Sweden)

    Wood Thomas K

    2011-10-01

    Full Text Available Abstract Background Previously we showed that BdcA controls Escherichia coli biofilm dispersal by binding the ubiquitous bacterial signal cyclic diguanylate (c-di-GMP; upon reducing the concentration of c-di-GMP, the cell shifts to the planktonic state by increasing motility, decreasing aggregation, and decreasing production of biofilm adhesins. Findings Here we report that BdcA also increases biofilm dispersal in other Gram-negative bacteria including Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhizobium meliloti. BdcA binds c-di-GMP in these strains and thereby reduces the effective c-di-GMP concentrations as demonstrated by increases in swimming motility and swarming motility as well as by a reduction in extracellular polysaccharide production. We also develop a method to displace existing biofilms by adding BdcA via conjugation from E. coli in mixed-species biofilms. Conclusion Since BdcA shows the ability to control biofilm dispersal in diverse bacteria, BdcA has the potential to be used as a tool to disperse biofilms for engineering and medical applications.

  2. Bacterial genospecies that are not ecologically coherent: population genomics of Rhizobium leguminosarum.

    Science.gov (United States)

    Kumar, Nitin; Lad, Ganesh; Giuntini, Elisa; Kaye, Maria E; Udomwong, Piyachat; Shamsani, N Jannah; Young, J Peter W; Bailly, Xavier

    2015-01-01

    Biological species may remain distinct because of genetic isolation or ecological adaptation, but these two aspects do not always coincide. To establish the nature of the species boundary within a local bacterial population, we characterized a sympatric population of the bacterium Rhizobium leguminosarum by genomic sequencing of 72 isolates. Although all strains have 16S rRNA typical of R. leguminosarum, they fall into five genospecies by the criterion of average nucleotide identity (ANI). Many genes, on plasmids as well as the chromosome, support this division: recombination of core genes has been largely within genospecies. Nevertheless, variation in ecological properties, including symbiotic host range and carbon-source utilization, cuts across these genospecies, so that none of these phenotypes is diagnostic of genospecies. This phenotypic variation is conferred by mobile genes. The genospecies meet the Mayr criteria for biological species in respect of their core genes, but do not correspond to coherent ecological groups, so periodic selection may not be effective in purging variation within them. The population structure is incompatible with traditional 'polyphasic taxonomy' that requires bacterial species to have both phylogenetic coherence and distinctive phenotypes. More generally, genomics has revealed that many bacterial species share adaptive modules by horizontal gene transfer, and we envisage a more consistent taxonomic framework that explicitly recognizes this. Significant phenotypes should be recognized as 'biovars' within species that are defined by core gene phylogeny. PMID:25589577

  3. Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti1

    Science.gov (United States)

    Hartwig, Ueli A.; Joseph, Cecillia M.; Phillips, Donald A.

    1991-01-01

    Alfalfa (Medicago sativa L.) releases different flavonoids from seeds and roots. Imbibing seeds discharge 3?,4?,5,7-substituted flavonoids; roots exude 5-deoxy molecules. Many, but not all, of these flavonoids induce nodulation (nod) genes in Rhizobium meliloti. The dominant flavonoid released from alfalfa seeds is identified here as quercetin-3-O-galactoside, a molecule that does not induce nod genes. Low concentrations (1-10 micromolar) of this compound, as well as luteolin-7-O-glucoside, another major flavonoid released from germinating seeds, and the aglycones, quercetin and luteolin, increase growth rate of R. meliloti in a defined minimal medium. Tests show that the 5,7-dihydroxyl substitution pattern on those molecules was primarily responsible for the growth effect, thus explaining how 5-deoxy flavonoids in root exudates fail to enhance growth of R. meliloti. Luteolin increases growth by a mechanism separate from its capacity to induce rhizobial nod genes, because it still enhanced growth rate of R. meliloti lacking functional copies of the three known nodD genes. Quercetin and luteolin also increased growth rate of Pseudomonas putida. They had no effect on growth rate of Bacillus subtilis or Agrobacterium tumefaciens, but they slowed growth of two fungal pathogens of alfalfa. These results suggest that alfalfa can create ecochemical zones for controlling soil microbes by releasing structurally different flavonoids from seeds and roots. PMID:16668056

  4. Enhancement of the nitrogen fixation efficiency of genetically-engineered Rhizobium with high catalase activity.

    Science.gov (United States)

    Orikasa, Yoshitake; Nodasaka, Yoshinobu; Ohyama, Takuji; Okuyama, Hidetoshi; Ichise, Nobutoshi; Yumoto, Isao; Morita, Naoki; Wei, Min; Ohwada, Takuji

    2010-10-01

    The vktA catalase gene, which had been cloned from Vibrio rumoiensis S-1T having extraordinarily high catalase activity, was introduced into the root nodule bacterium, Rhizobium leguminosarum bv. phaseoli USDA 2676. The catalase activity of the vktA-transformed R. leguminosarum cells (free-living) was three orders in magnitude higher than that of the parent cells and this transformant could grow in a higher concentration of exogenous hydrogen peroxide (H2O2). The vktA-transformant was inoculated to the host plant (Phaseolus vulgaris L.) and the nodulation efficiency was evaluated. The results showed that the nitrogen-fixing activity of nodules was increased 1.7 to 2.3 times as compared to the parent. The levels of H2O2 in nodules formed by the vktA-transformant were decreased by around 73%, while those of leghemoglobins (Lba and Lbb) were increased by 1.2 (Lba) and 2.1 (Lbb) times compared with the parent. These results indicated that the increase of catalase activity in rhizobia could be useful to improve the nitrogen-fixing efficiency of nodules by the reduction of H2O2 content concomitantly with the enhancement of leghemoglobins contents. PMID:20547375

  5. Bacterial genospecies that are not ecologically coherent: population genomics of Rhizobium leguminosarum

    Science.gov (United States)

    Kumar, Nitin; Lad, Ganesh; Giuntini, Elisa; Kaye, Maria E.; Udomwong, Piyachat; Shamsani, N. Jannah; Young, J. Peter W.; Bailly, Xavier

    2015-01-01

    Biological species may remain distinct because of genetic isolation or ecological adaptation, but these two aspects do not always coincide. To establish the nature of the species boundary within a local bacterial population, we characterized a sympatric population of the bacterium Rhizobium leguminosarum by genomic sequencing of 72 isolates. Although all strains have 16S rRNA typical of R. leguminosarum, they fall into five genospecies by the criterion of average nucleotide identity (ANI). Many genes, on plasmids as well as the chromosome, support this division: recombination of core genes has been largely within genospecies. Nevertheless, variation in ecological properties, including symbiotic host range and carbon-source utilization, cuts across these genospecies, so that none of these phenotypes is diagnostic of genospecies. This phenotypic variation is conferred by mobile genes. The genospecies meet the Mayr criteria for biological species in respect of their core genes, but do not correspond to coherent ecological groups, so periodic selection may not be effective in purging variation within them. The population structure is incompatible with traditional ‘polyphasic taxonomy? that requires bacterial species to have both phylogenetic coherence and distinctive phenotypes. More generally, genomics has revealed that many bacterial species share adaptive modules by horizontal gene transfer, and we envisage a more consistent taxonomic framework that explicitly recognizes this. Significant phenotypes should be recognized as ‘biovars' within species that are defined by core gene phylogeny. PMID:25589577

  6. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI565.

    Science.gov (United States)

    Reeve, Wayne; Drew, Elizabeth; Ballard, Ross; Melino, Vanessa; Tian, Rui; De Meyer, Sofie; Brau, Lambert; Ninawi, Mohamed; Teshima, Hazuki; Goodwin, Lynne; Chain, Patrick; Liolios, Konstantinos; Pati, Amrita; Mavromatis, Konstantinos; Ivanova, Natalia; Markowitz, Victor; Woyke, Tanja; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii SRDI565 (syn. N8-J) is an aerobic, motile, Gram-negative, non-spore-forming rod. SRDI565 was isolated from a nodule recovered from the roots of the annual clover Trifolium subterraneum subsp. subterraneum grown in the greenhouse and inoculated with soil collected from New South Wales, Australia. SRDI565 has a broad host range for nodulation within the clover genus, however N2-fixation is sub-optimal with some Trifolium species and ineffective with others. Here we describe the features of R. leguminosarum bv. trifolii strain SRDI565, together with genome sequence information and annotation. The 6,905,599 bp high-quality-draft genome is arranged into 7 scaffolds of 7 contigs, contains 6,750 protein-coding genes and 86 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project. PMID:24976879

  7. ABC transport is inactivated by the PTS(Ntr) under potassium limitation in Rhizobium leguminosarum 3841.

    Science.gov (United States)

    Untiet, Verena; Karunakaran, Ramakrishnan; Krämer, Maria; Poole, Philip; Priefer, Ursula; Prell, Jürgen

    2013-01-01

    PTS(Ntr) is a regulatory phosphotransferase system in many bacteria. Mutation of the PTS(Ntr) enzymes causes pleiotropic growth phenotypes, dry colony morphology and a posttranslational inactivation of ABC transporters in Rhizobium leguminosarum 3841. The PTS(Ntr) proteins EI(Ntr) and 2 copies of EIIA(Ntr) have been described previously. Here we identify the intermediate phosphocarrier protein NPr and show its phosphorylation by EI(Ntr) in vitro. Furthermore we demonstrate that phosphorylation of EI(Ntr) and NPr is required for ABC transport activation and that the N-terminal GAF domain of EI(Ntr) is not required for autophosphorylation. Previous studies have shown that non-phosphorylated EIIA(Ntr) is able to modulate the transcriptional activation of the high affinity potassium transporter KdpABC. In R. leguminosarum 3841 kdpABC expression strictly depends on EIIA(Ntr). Here we demonstrate that under strong potassium limitation ABC transport is inactivated, presumably by non-phosphorylated EIIA(Ntr). This is to our knowledge the first report where PTS(Ntr) dictates an essential cellular function. This is achieved by the inverse regulation of two important ATP dependent transporter classes. PMID:23724079

  8. Rhizobium alters inducible defenses in broad bean, Vicia faba

    Directory of Open Access Journals (Sweden)

    Edward Brian Mondor

    2011-11-01

    Full Text Available Conversion of inorganic nitrogen by mutualistic nitrogen-fixing bacteria is essential for plant growth and reproduction, as well as the development of chemical and mechanical defenses. It is unclear, however, how these bacteria alter co-occurring symbioses at higher trophic levels; e.g., extrafloral nectary (EFN induction, in response to herbivory, to attract defensive mutualists. We hypothesized that plants colonized by nitrogen-fixing bacteria would mount a larger inducible, defensive response than plants lacking symbioses, as defensive traits are costly. We predicted that bean plants, Vicia faba L., harboring Rhizobium leguminosarum bv. viciae Frank would produce more EFNs upon leaf damage, than plants lacking the symbionts, as EFN induction in V. faba is resource-dependent. Here we report that V. faba colonized by R. leguminosarum produced similar numbers of EFNs as did plants without symbionts. Plants with symbionts, however, produced significantly fewer EFNs over 1 week in response to leaf damage, than those without leaf damage. As such, nitrogen-fixing bacteria may not always benefit the host plant, but rather, the utility of these bacteria may be dependent on the prevailing ecological conditions.

  9. Isolation of Rhizobium Spp. Bacteria which as Used Microbial Fertilizer from Wild Leguminosarum Plants

    Directory of Open Access Journals (Sweden)

    Hatice Ö?ütcü

    2014-04-01

    Full Text Available In our study used wild leguminous plants (Medicago sativa, M. lupulina and M. varia Erzurum belongs to the high altitude (2000 - 2500m regions ( Palandöken mountain, Alibaba mountain, Turnagöl mountain, Hasanbaba mountain, E?erli mountain, Y?ld?r?m mountain, Çubuklu mountain, Deveboynu locality, Kayakyolu locality, Telsizler and Dumlu hill were collected during the months of June and July. Nodules were obtained from this plant were sterilized, YMA (Yeast Mannitol Agar plates were streaked and petri dishes 28+1ºC were incubated for 3-5 days. Colonies appear after incubation typically constitute (white, clear or slightly opaque, mucosity, round, raised 39 isolates were selected and transferred to tubes and refrigerated YMA were stored at +4ºC. In the next stage, cytological and biochemical analyzes of these isolates were studied to determine. For this purpose isolates; YMA containing bromothymol blue and congo red reproduction, gram stain reaction, movement and subjected to catalase and oxidase tests were evaluated. The cytological and biochemical analysis of results showed that 28 of 39 strains belonged to Rhizobium spp.

  10. Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI943.

    Science.gov (United States)

    Reeve, Wayne; Drew, Elizabeth; Ballard, Ross; Melino, Vanessa; Tian, Rui; De Meyer, Sofie; Brau, Lambert; Ninawi, Mohamed; Daligault, Hajnalka; Davenport, Karen; Erkkila, Tracy; Goodwin, Lynne; Gu, Wei; Munk, Christine; Teshima, Hazuki; Xu, Yan; Chain, Patrick; Kyrpides, Nikos

    2013-12-20

    Rhizobium leguminosarum bv. trifolii SRDI943 (strain syn. V2-2) is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from a root nodule of Trifolium michelianum Savi cv. Paradana that had been grown in soil collected from a mixed pasture in Victoria, Australia. This isolate was found to have a broad clover host range but was sub-optimal for nitrogen fixation with T. subterraneum (fixing 20-54% of reference inoculant strain WSM1325) and was found to be totally ineffective with the clover species T. polymorphum and T. pratense. Here we describe the features of R. leguminosarum bv. trifolii strain SRDI943, together with genome sequence information and annotation. The 7,412,387 bp high-quality-draft genome is arranged into 5 scaffolds of 5 contigs, contains 7,317 protein-coding genes and 89 RNA-only encoding genes, and is one of 100 rhizobial genomes sequenced as part of the DOE Joint Genome Institute 2010 Genomic Encyclopedia for Bacteria and Archaea-Root Nodule Bacteria (GEBA-RNB) project. PMID:24976880

  11. Rhizobium Strain Effects on Yield and Bleeding Sap Amino Compounds in Pisum sativum.

    DEFF Research Database (Denmark)

    Rosendahl, Lis

    1984-01-01

    Bleeding sap composition, dry matter production and N distribution in pea (P. sativum L. cv. Bodil) grown with and without nitrate and nodulated with either R. leguminosarum strain 128c53 or strain 1044 were compared. Nitrate increased the total dry matter production of both symbioses, but decreased both the proportions of belowground dry matter to total dry matter production and nodule dry matter to total belowground dry matter production. The total dry matter yield and N accumulation was greater in the symbiosis with strain 1044, whereas the accumulation of N in the roots plus nodules relative to the total N-accumulation was greater with strain 128c53 due to a higher production of nodule tissue. The root bleeding sap of the symbiosis with the greater yield (strain 1044) contained high levels of asparagine and aspartic acid. In the 128c53 symbiosis, glutamine plus homoserine accounted for a higher percentage of the organic solutes transporting newly assimilated N from the root system than in the association with 1044. The Rhizobium strain effect on amino compound composition of the bleeding sap may indicate an influence of the bacteroids on either the N-assimilatory enzyme system in the plant cytosol, or on the pools of the Krebs cycle intermediates or related compounds in the nodules.

  12. Evaluación de diferentes sistemas de fermentación para la producción de ácido indolacético por Rhizobium sp

    Directory of Open Access Journals (Sweden)

    Beatriz Altuna

    2006-01-01

    Full Text Available Las investigaciones relacionadas con la producción microbiológica de hormonas de crecimiento vegetal tienen hoy amplia actualidad, no sólo por los efectos beneficiosos que éstas producen en diversos cultivos, sino también por su alta compatibilidad con el ambiente. Un ejemplo interesante de ello lo constituye el ácido indolacético. En esta investigación se describe la producción de AIA en un cultivo intermitente con una cepa de Rhizobium sp. Pudo comprobarse que la relación de formación biomasa-producto obedece a una clasificación del tipo "parcialmente asociada". La velocidad o rapidez específica de proliferación ("crecimiento" máxima fue de 0.12 h-1, alcanzando la concentración de AIA valores de 340 mg/l. Dos sistemas de biorreacción del tipo intermitente incrementado ("fed-batch" fueron evaluados, mostrando el sistema de alimentación exponencial ventajas significativas en el proceso al obtenerse valores de productividades máximas de 16 mg/l-h, es decir, incrementos en esta respuesta del 60 % y concentraciones de AIA máximas de 467 mg/l.

  13. Competitiveness of Rhizobium trifolii Strains Associated with Red Clover (Trifolium pratense L.) in Mississippi Soils.

    Science.gov (United States)

    Materon, L A; Hagedorn, C

    1982-11-01

    Five strains of Rhizobium trifolii were evaluated in competition with indigenous populations in nodulating red clover (Trifolium pratense L.) cv. Kenland in two different soils in Mississippi. Double antibiotic resistance acquisition was used to measure the proportion of nodules occupied by the introduced mutant strains. In vertisol soil, strains RP113-7, 162BB1, LM1, and 162P17 were recovered in at least 94% of the assayed nodules, whereas TA1 was found in 83.8% of the nodules. At an ultisol location, significant differences were detected within the introduced rhizobia. Strain RP113-7 was recovered at very high rates (99.2% of the assayed nodules), whereas strains 162BB1, LM1, 162P17, and TA1 were all found in 84.9 to 96.0% of the nodules sampled. Forage yield and percent crude protein levels were lower with the less effective but competitive strain (TA1) at both locations. Results indicated that more effective strains of R. trifolii can increase red clover production and symbiotic nitrogen fixation under different environmental conditions in Mississippi. PMID:16346130

  14. Effect of Leguminous Lectins on the Growth of Rhizobium tropici CIAT899

    Directory of Open Access Journals (Sweden)

    Mayron Alves de Vasconcelos

    2013-05-01

    Full Text Available Rhizobium tropici is a Gram-negative bacterium that induces nodules and fixed atmospheric nitrogen in symbiotic association with Phaseolus vulgaris (common bean and some other leguminous species. Lectins are proteins that specifically bind to carbohydrates and, consequently, modulate different biological functions. In this study, the d-glucose/ d-mannose-binding lectins (from seeds of Dioclea megacarpa, D. rostrata and D. violacea and D-galactose-binding lectins (from seeds of Bauhinia variegata, Erythina velutina and Vatairea macrocarpa were purified using chromatographic techniques and evaluated for their effect on the growth of R. tropici CIAT899. All lectins were assayed with a satisfactory degree of purity according to SDS-PAGE analysis, and stimulated bacterial growth; in particular, the Dioclea rostrata lectin was the most active among all tested proteins. As confirmed in the present study, both d-galactose- and d-glucose/d-mannose-binding lectins purified from the seeds of leguminous plants may be powerful biotechnological tools to stimulate the growth of R. tropici CIAT99, thus improving symbiotic interaction between rhizobia and common bean and, hence, the production of this field crop.

  15. Study of the basis for the competitiveness of Rhizobium japonicum in the nodulation of soybean

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, W.

    1990-06-01

    The overall goal of our studies was to identify cellular and molecular characteristics of rhizobia that are important to root colonization and symbiotic infection in competition with indigenous soil microbes. Rhizobia were found to respond to specific host flavonoids as chemoattractants as well as nodulation gene inducers. Motility and chemotaxis contributed significantly to the efficiency of symbiotic interactions, but not to colonization of root tips, where bacterial dispersal depended primarily on passive movement by root cell elongation. Co-inoculation of Rhizobium nod gene mutants with each other and with the wild-type showed that the mutants could help the wild-type, but not each other, to initiate nodules. Mutants with defective host specificity genes were the only ones capable of helping the wild-type in an additive or synergistic manner. Alfalfa was shown to have rapid, systemic feedback regulation suppressing nodule formation in younger parts of the root system in response to initiation of the first nodules. Root mucilage and exudate components were found to affect attachment of rhizobia to root surfaces. Methods for optimal surface sterilization of legume seeds were examined. 5 refs.

  16. Transformation of pWWO in Rhizobium leguminosarum DPT to Engineer Toluene Degrading Ability for Rhizoremediation.

    Science.gov (United States)

    Goel, Garima; Pandey, Piyush; Sood, Anchal; Bisht, Sandeep; Maheshwari, D K; Sharma, G D

    2012-06-01

    Rhizoremediation of organic xenobiotics is based on interactions between plants and their associated micro-organisms. The present work was designed to engineer a bacterial system having toluene degradation ability along with plant growth promoting characteristics for effective rhizoremediation. pWWO harboring the genes responsible for toluene breakdown was isolated from Pseudomonas putida MTCC 979 and successfully transformed in Rhizobium DPT. This resulted in a bacterial strain (DPT(T)) which had the ability to degrade toluene as well as enhance growth of host plant. The frequency of transformation was recorded 5.7 × 10(-6). DPT produced IAA, siderophore, chitinase, HCN, ACC deaminase, solubilized inorganic phosphate, fixed atmospheric nitrogen and inhibited the growth of Fusarium oxysporum and Macrophomina phaseolina in vitro. During pot assay, 50 ppm toluene in soil was found to inhibit the germination of Cajanus cajan seeds. However when the seeds bacterized with toluene degrading P. putida or R. leguminosarum DPT were sown in pots, again no germination was observed. Non-bacterized as well as bacterized seeds germinated successfully in toluene free soil as control. The results forced for an alternative mode of application of bacteria for rhizoremediation purpose. Hence bacterial suspension was mixed with soil having 50 ppm of toluene. Germination index in DPT treated soil was 100% while in P. putida it was 50%. Untreated soil with toluene restricted the seeds to germinate. PMID:23729882

  17. Effect of Rhizobium japonicum Inoculum Doses (Liquid Culture) on the Growth and Seed Yield of Soybean Crop

    OpenAIRE

    Oad, F. C.; Kumar, L.; Biswas, J. K.

    2002-01-01

    The field experiments were conducted during 2000 at Tandojam, Pakistan to evaluate the effect of Rhizobium japonicum inoculum doses of liquid culture on the growth and seed yield of soybean crop. One liter liquid culture medium was prepared by standard procedure by adding 0.5g K2HPO4, 0.2g MgSO4, 0.1g NaCl, 0.05g yeast extract, 10.0g Minitol, and 1000ml distilled water. Six Rhizobium japonicum doses (10, 15, 20, 25, 30 ml, and untreated control were laid-down in Randomized Complete Block Desi...

  18. Rhizobium meliloti nodA and nodB genes are involved in generating compounds that stimulate mitosis of plant cells

    OpenAIRE

    Schmidt, Ju?rgen; Wingender, Ruth; John, Michael; Wieneke, Ursula; Schell, Jeff

    1988-01-01

    The nodB gene of Rhizobium meliloti encodes a 23.8-kDa protein that is conserved in several Rhizobium species. Monospecific polyclonal antibodies against NodB were used to localize this protein in the cytosol of R. meliloti and Escherichia coli cells containing nodABC genes. In comparison to the NodA and NodC proteins, NodB is synthesized in a disproportionately low amount. The NodA and NodB proteins are involved in generating small, heat-stable compounds that stimulate the mitosis of various...

  19. The central domain of Rhizobium meliloti NifA is sufficient to activate transcription from the R. meliloti nifH promoter.

    OpenAIRE

    Huala, E.; Ausubel, F. M.

    1989-01-01

    The Rhizobium meliloti nifA product (NifA) shares extensive homology in its central region and at its C-terminal end with Rhizobium leguminosarum DctD and with NtrC from several species. All three proteins are transcriptional activators of NtrA (RpoN)-RNA polymerase-dependent promoters. Several large deletions of R. meliloti NifA were constructed to investigate the role of the conserved and divergent domains of NifA in transcriptional activity and posttranscriptional regulation by oxygen. The...

  20. Procedure for Obtaining Efficient Root Nodulation of a Pea Cultivar by a Desired Rhizobium Strain and Preempting Nodulation by Other Strains

    OpenAIRE

    Fobert, P. R.; Roy, N.; Nash, J. H. E.; Iyer, V. N.

    1991-01-01

    The specificity between the sym-2 gene bred into certain cultivars of pea (Pisum sativum L.) and the nodX gene, present only rarely in isolates of Rhizobium leguminosarum, can be exploited to preempt competition or nodulation blocking by a Rhizobium strain indigenous to a soil environment. The principle is to isolate an R. leguminosarum strain prevalent in a locale, convert it into a strain that will nodulate a desirable pea cultivar carrying sym-2 by establishing nodX in it, and then use the...

  1. Biological nitrogen fixation by Rhizobium sp. native gliricidia (Gliricidia sepium [Jacq.] Kunth ex Walp.) under greenhouse conditions / Fijación biológica de nitrógeno por Rhizobium sp. nativo de matarratón (Gliricidia sepium [Jacq.] Kunth ex Walp.) bajo condiciones de invernadero

    Scientific Electronic Library Online (English)

    Juan Guillermo, Cubillos-Hinojosa; Pablo Ernesto, Milian-Mindiola; Jorge Luis, Hernández-Mulford.

    2011-12-01

    Full Text Available SciELO Colombia | Language: English Abstract in spanish Se realizó un experimento bajo condiciones de invernadero con el fin de evaluar la asociación y fijación biológica de nitrógeno (FBN) en seis cepas nativas de Rhizobium sp. aisladas de nódulos de matarratón y una cepa comercial (Rhizobiol©). Las suspensiones de 106 y 108 células/mL para cada una de [...] las cepas estudiadas y aplicadas en dos ensayos separados: el primero con semillas y la segundo con plántulas de 35 días de edad matarratón. En el ensayo de semilla se calcula el porcentaje acumulado de germinación durante 7 días. En ambos ensayos, después de 42 días en las semillas y 52 días en plántulas se determinó la altura y diámetro del tallo, número de hojas, peso seco de la parte aérea, número de nódulos por planta y el porcentaje de nitrógeno. Todos los tratamientos estimularon la germinación, el crecimiento y FBN, siendo mejor en las cepas nativas a una concentración de 108 células/mL, en comparación con la cepa comercial y el control. Estos resultados indican el efecto positivo ejercido por Rhizobium sp., en la promoción del crecimiento y FBN, que podrían ser utilizados para estudios adicionales para determinar la producción de un biofertilizante, permitiendo potenciar la producción de cultivos de matarratón como alimento de ganado bovino como fuente de proteína en el Centro de Biotecnología del Caribe Abstract in english An experiment was conducted under greenhouse conditions in order to evaluate the association and biological nitrogen fixation (BNF), six native strains of Rhizobium sp isolated from nodules gliricidia and a commercial strain (Rhizobiol©). Suspensions of 106 and 108 cells/mL for each of the strains s [...] tudied and applied in two separate trials: the first with seeds and the second with seedlings 35 days of age gliricidia. In the seed test is calculated the cumulative percentage of germination for 7 days. In both trials after 42 days in seeds and seedlings 52 days in length was measured and stem diameter, leaf number, dry weight of aerial parts, number of nodules/plant and percentage of nitrogen. All treatments stimulated germination, growth and BNF, being better in the native strains at a concentration of 108 cells/mL, compared with the commercial strain and the control. These results indicate the positive effect exerted by Rhizobium sp., in promoting growth and BNF, which could be used for further studies to establish the production of a biofertilizer, allowing potentiate the production of crops by gliricidia for food arich cattle as source of protein in the Caribbean Biotechnology Center

  2. Inoculação do feijoeiro com Rhizobium tropici associada à exsudato de Mimosa flocculosa com diferentes doses de nitrogênio Rhizobium tropici associated with Mimosa flocculosa exudates inoculation effect on bean plants under different nitrogen rates

    Directory of Open Access Journals (Sweden)

    Eulene Francisco da Silva

    2009-01-01

    Full Text Available O presente estudo teve como objetivo avaliar os efeitos da inoculação de rizóbio, associada à adição de exsudatos de sementes de Mimosa flocculosa, e/ou de N-mineral nas características agronômicas do feijoeiro, em sucessão à soja e ao milho. O delineamento experimental foi em blocos casualizados, com quatro repetições, sendo os tratamentos dispostos em parcelas sub-subdivididas. As culturas soja e milho antecessoras à cultura do feijoeiro formaram as parcelas. As subparcelas foram constituídas pelos tratamentos: testemunha sem inoculação, inoculação de Rhyzobium tropici, estirpes CIAT 899 e PRF 81 e a associação deste com os exsudados das sementes de Mimosa flocculosa. As sub-subparcelas constituiram-se de quatro doses de N aplicadas em cobertura: 0, 40, 80 e 120 kg ha-1. A inoculação de rizóbio associada à adição de exsudato de sementes de Mimosa flocculosa contribuiu para o melhor desenvolvimento da parte aérea do feijoeiro. A adubação nitrogenada reduziu, de forma linear, a nodulação do feijoeiro. O milho como cultura antecessora ao feijão contribuiu para o aumento do peso de 100 grãos e a adição de N combinado não contribuiu para o aumento do número de vagens por planta e produtividade de grãos do feijoeiro, independente da dose utilizada.The aim of this work was to evaluate the effect of the Rhizobium inoculation, associated with seed exudates of Mimosa flocculosa, under different rates of nitrogen fertilization was evaluated in bean crops following soybean (Glycine max L. Merril and corn (Zea mays L.. The experimental design was randomized blocks with four replications, with treatments arranged in sub-divided parcels. The parcels were constituted of two summer crops preceding the common bean crop: soybean and corn. In the sub-parcels three treatments involving inoculation of the common bean seeds were considered: control treatment without inoculation; bean seeds inoculated with Rhizobium tropici, strains CIAT 899 and PRF 81, and the association of Rhizobium with the exudates of the Mimosa flocculosa seeds. The sub-subparcels received of four doses of nitrogen fertilization applied on covering: 0, 40, 80 and 120 kg ha-1 N. The inoculation of Rhizobium associated with the addition of exudates of Mimosa flocculosa seeds resulted in higher shoot dry weight. Besides that, the nitrogen fertilization, on the tested doses, reduced, in a linear way, the nodulation of the bean plant. It was also verified that corn as a preceding crop for bean has contributed to the increase of the weight of 100 grains, while the addition of combined N did not contribute to the improvement on the number of beans per plant, neither of the grain yield of bean plants, independent of the dose that was used.

  3. Effects of high temperature on survival, symbiotic performance and genomic modifications of bean nodulating Rhizobium strains / Sobrevivência, fixação de nitrogênio e modificações genéticas em estirpes de Rhizobium sp. efetivas na nodulação do feijoeiro, expostas à altas temperaturas

    Scientific Electronic Library Online (English)

    Patrícia P., Pinto; Ruy, Raposeiras; Andrea M., Macedo; Lucy, Seldin; Edilson, Paiva; Nadja M.H., Sá.

    1998-10-01

    Full Text Available SciELO Brazil | Language: English Abstract in portuguese Altas temperaturas podem afetar a sobrevivência, estabelecimento e as propriedades simbióticas em estirpes de Rhizobium. As estirpes capazes de nodular o feijoeiro têm sido consideradas particularmente sensíveis, porque nessas estirpes é comum a ocorrência de recombinações e/ou deleções genômicas co [...] mprometendo, muitas vezes, a sua utilização como inoculantes. Neste trabalho, procurou-se avaliar a capacidade de crescimento e sobrevivência em temperaturas elevadas de estirpes de Rhizobium efetivas na fixação de nitrogênio no feijoeiro isoladas dos cerrados, bem como avaliar suas características fenotípicas e genotípicas após choque térmico. A capacidade de sobrevivência à temperaturas elevadas, avaliada após choques térmicos sucessivos (45ºC por 4 horas) mostrou ser uma característica própria de cada estirpe, independente de sua termotolerância, que aparentemente foi mais acentuada nas estirpes de R. tropici. Algumas estirpes de R. leguminosarum bv. phaseoli mostraram alterações significativas (Duncan 5% de probabilidade) nas suas características fenotípicas (produção de matéria seca) após choques térmicos e nos seus padrões genômicos evidenciados pela técnica de AP-PCR. As estirpes de R. tropici foram aparentemente mais estáveis não sendo detectadas alterações fenotípicas significativas e com exceção da estirpe FJ2.21, após choque térmico e inoculação na planta hospedeira, mantiveram o padrão genômico original. Abstract in english High temperatures can affect the survival, establishment and symbiotic properties of Rhizobium strains. Bean nodulating Rhizobium strains are considered particularly sensitive because on this strains genetic recombinations and/or deletions occur frequently, thus compromising the use of these bacteri [...] a as inoculants. In this study R. tropici and R. leguminosarum bv. phaseoli strains isolated from Cerrado soils were exposed to thermal stress and the strains’ growth, survival and symbiotic relationships as well as alterations in their genotypic and phenotypic characteristics were analyzed. After successive thermal shocks at 45ºC for four hours, survival capacity appeared to be strain-specific, independent of thermo-tolerance and was more apparent in R. tropici strains. Certain R. leguminosarum bv. phaseoli strains had significant alterations in plant dry weight and DNA patterns obtained by AP-PCR method. R. tropici strains (with the exception of FJ2.21) were more stable than R. leguminosarum bv. phaseoli strains because no significant phenotypic alterations were observed following thermal treatments and they maintained their original genotypic pattern after inoculation in plants.

  4. Effects of high temperature on survival, symbiotic performance and genomic modifications of bean nodulating Rhizobium strains Sobrevivência, fixação de nitrogênio e modificações genéticas em estirpes de Rhizobium sp. efetivas na nodulação do feijoeiro, expostas à altas temperaturas

    Directory of Open Access Journals (Sweden)

    Patrícia P. Pinto

    1998-10-01

    Full Text Available High temperatures can affect the survival, establishment and symbiotic properties of Rhizobium strains. Bean nodulating Rhizobium strains are considered particularly sensitive because on this strains genetic recombinations and/or deletions occur frequently, thus compromising the use of these bacteria as inoculants. In this study R. tropici and R. leguminosarum bv. phaseoli strains isolated from Cerrado soils were exposed to thermal stress and the strains’ growth, survival and symbiotic relationships as well as alterations in their genotypic and phenotypic characteristics were analyzed. After successive thermal shocks at 45ºC for four hours, survival capacity appeared to be strain-specific, independent of thermo-tolerance and was more apparent in R. tropici strains. Certain R. leguminosarum bv. phaseoli strains had significant alterations in plant dry weight and DNA patterns obtained by AP-PCR method. R. tropici strains (with the exception of FJ2.21 were more stable than R. leguminosarum bv. phaseoli strains because no significant phenotypic alterations were observed following thermal treatments and they maintained their original genotypic pattern after inoculation in plants.Altas temperaturas podem afetar a sobrevivência, estabelecimento e as propriedades simbióticas em estirpes de Rhizobium. As estirpes capazes de nodular o feijoeiro têm sido consideradas particularmente sensíveis, porque nessas estirpes é comum a ocorrência de recombinações e/ou deleções genômicas comprometendo, muitas vezes, a sua utilização como inoculantes. Neste trabalho, procurou-se avaliar a capacidade de crescimento e sobrevivência em temperaturas elevadas de estirpes de Rhizobium efetivas na fixação de nitrogênio no feijoeiro isoladas dos cerrados, bem como avaliar suas características fenotípicas e genotípicas após choque térmico. A capacidade de sobrevivência à temperaturas elevadas, avaliada após choques térmicos sucessivos (45ºC por 4 horas mostrou ser uma característica própria de cada estirpe, independente de sua termotolerância, que aparentemente foi mais acentuada nas estirpes de R. tropici. Algumas estirpes de R. leguminosarum bv. phaseoli mostraram alterações significativas (Duncan 5% de probabilidade nas suas características fenotípicas (produção de matéria seca após choques térmicos e nos seus padrões genômicos evidenciados pela técnica de AP-PCR. As estirpes de R. tropici foram aparentemente mais estáveis não sendo detectadas alterações fenotípicas significativas e com exceção da estirpe FJ2.21, após choque térmico e inoculação na planta hospedeira, mantiveram o padrão genômico original.

  5. Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.

    Directory of Open Access Journals (Sweden)

    Ormeño-Orrillo Ernesto

    2012-12-01

    Full Text Available Abstract Background Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 are ?-Proteobacteria that establish nitrogen-fixing symbioses with a range of legume hosts. These strains are broadly used in commercial inoculants for application to common bean (Phaseolus vulgaris in South America and Africa. Both strains display intrinsic resistance to several abiotic stressful conditions such as low soil pH and high temperatures, which are common in tropical environments, and to several antimicrobials, including pesticides. The genetic determinants of these interesting characteristics remain largely unknown. Results Genome sequencing revealed that CIAT 899 and PRF 81 share a highly-conserved symbiotic plasmid (pSym that is present also in Rhizobium leucaenae CFN 299, a rhizobium displaying a similar host range. This pSym seems to have arisen by a co-integration event between two replicons. Remarkably, three distinct nodA genes were found in the pSym, a characteristic that may contribute to the broad host range of these rhizobia. Genes for biosynthesis and modulation of plant-hormone levels were also identified in the pSym. Analysis of genes involved in stress response showed that CIAT 899 and PRF 81 are well equipped to cope with low pH, high temperatures and also with oxidative and osmotic stresses. Interestingly, the genomes of CIAT 899 and PRF 81 had large numbers of genes encoding drug-efflux systems, which may explain their high resistance to antimicrobials. Genome analysis also revealed a wide array of traits that may allow these strains to be successful rhizosphere colonizers, including surface polysaccharides, uptake transporters and catabolic enzymes for nutrients, diverse iron-acquisition systems, cell wall-degrading enzymes, type I and IV pili, and novel T1SS and T5SS secreted adhesins. Conclusions Availability of the complete genome sequences of CIAT 899 and PRF 81 may be exploited in further efforts to understand the interaction of tropical rhizobia with common bean and other legume hosts.

  6. Isolation of the Rhizobium leguminosarum NodF nodulation protein: NodF carries a 4'-phosphopantetheine prosthetic group.

    OpenAIRE

    Geiger, O.; Spaink, H. P.; Kennedy, E. P.

    1991-01-01

    Rhizobium species produce a protein product of the nodF gene that has a limited but recognizable homology to the well-characterized acyl carrier protein (ACP) of Escherichia coli. NodF functions together with NodE in generating a host-specific response to the plant host in the interchange of signals leading to the effective nodulation of roots (H.P. Spaink, J. Weinman, M.A. Djordjevic, C.A. Wijffelman, R.J.H. Okker, and B. J.J. Lugtenberg, EMBO J. 8:2811-2818, 1989; B. Scheres, C. van de Wiel...

  7. Legume-bacterium (Rhizobium Association-Symbiosis, A Marriage of Convenience, Necessary Evil or Bacterium Taken Hostage by the Legume

    Directory of Open Access Journals (Sweden)

    F. Azam

    2001-01-01

    Full Text Available Nitrogen (N is the key nutrient element, limiting crop production under most situations. A major reason for insufficient N supplies being its presence in soil in organic forms which must be mineralized before being used by the plants. However, leguminous plants are equipped with the facility to acquire a major portion of N directly from atmospheric N2 through bacterial fixation (reduction. The bacteria (Rhizobium spp reside inside the special structures on plant roots i.e., nodules and reduce atmospheric N at the expense of C supplied by the plant. This paper presents an analysis of the nature of association between the legume and bacterium.

  8. Transcription patterns of Rhizobium meliloti symbiotic plasmid pSym: identification of nifA-independent fix genes.

    OpenAIRE

    David, M.; Domergue, O.; Pognonec, P.; Kahn, D.

    1987-01-01

    We performed a systematic survey of transcription of a large region of the Rhizobium meliloti symbiotic plasmid pSym. This led to the discovery of two new sequences induced during symbiosis. The first sequence was linked to the known nitrogen fixation (nif-fix) gene cluster, and its expression depended on the nifA gene product. The second sequence was a novel fix locus (M.-H. Renalier, J. Batut, J. Ghai, B. Terzaghi, M. Gherardi, M. David, A.-M. Garnerone, J. Vasse, G. Truchet, T. Huguet, and...

  9. DNA sequence of the Rhizobium leguminosarum nodulation genes nodAB and C required for root hair curling.

    OpenAIRE

    Rossen, L.; Johnston, A. W.; Downie, J. A.

    1984-01-01

    A 3.2kb fragment of DNA cloned from Rhizobium leguminosarum has been shown to contain the genes necessary for the induction of root hair curling, the first observed step in the infection of leguminous plants by R. leguminosarum. The DNA sequence of this region has been determined and three open reading frames were identified: genes corresponding to these open reading frames have been called nodA, nodB and nodC and are transcribed in that order. Mutations within the nodC gene completely blocke...

  10. Physical and genetic map of a Rhizobium meliloti nodulation gene region and nucleotide sequence of nodC.

    OpenAIRE

    Jacobs, T. W.; Egelhoff, T. T.; Long, S. R.

    1985-01-01

    Infection of alfalfa by the soil bacterium Rhizobium meliloti proceeds by deformation of root hairs and bacterial invasion of host tissue by way of an infection thread. We studied an 8.7-kilobase (kb) segment of the R. meliloti megaplasmid, which contains genes required for infection. Site-directed Tn5 mutagenesis was used to examine this fragment for nodulation genes. A total of 81 R. meliloti strains with mapped Tn5 insertions in the 8.7-kb fragment were evaluated for nodulation phenotype o...

  11. Transmembrane orientation and receptor-like structure of the Rhizobium meliloti common nodulation protein NodC

    OpenAIRE

    John, Michael; Schmidt, Ju?rgen; Wieneke, Ursula; Kru?ssmann, Heinz-dieter; Schell, Jeff

    1988-01-01

    The 46.8-kd NodC protein of Rhizobium meliloti is a membrane protein, essential for nodule formation. Gene fusions of nodC to a portion of the ? cI repressor gene were used to define the membrane-anchor domain which is necessary for membrane insertion of the NodC protein into the membrane. The transmembrane orientation of NodC was confirmed by surface-specific radiolabeling and proteolysis experiments. A highly hydrophobic transmembrane-anchor domain was found near the carboxyl terminus, sep...

  12. Impact of Salicylic Acid on Symbiotic Relations Between Peas and Rhizobium leguminosarum bv. viceae

    OpenAIRE

    Glyanko, A. K.; Makarova, L. E.; Luzova, G. B.; Mironova, N. V.; Vasilieva, G. G.

    2004-01-01

    The study was targeted at the investigation of exogenous salicylic acid (SA) impact on bacteria proliferation in vitro, rhizobia penetration in the root tissues, the SA and hydrogen peroxide (H2O2) content in the root seedlings under inoculation of pea by compatible strain Rhizobium leguminosarum bv. viceae. Depending on the concentration SA either did not affect (0.0036-0.014 mM) rhizobia proliferation or suppressed their growth (0.07-0.2 mM) in vitro. Exogenous SA (0.2 mM) inhibited ...

  13. Biological Control of Crown Gall on Grapevine and Root Colonization by Nonpathogenic Rhizobium vitis Strain ARK-1

    OpenAIRE

    Kawaguchi, Akira

    2013-01-01

    A nonpathogenic strain of Rhizobium vitis ARK-1 was tested as a biological control agent for grapevine crown gall. When grapevine roots were soaked in a cell suspension of strain ARK-1 before planting in the field, the number of plants with tumors was reduced. The results from seven field trials from 2009 to 2012 were combined in a meta-analysis. The integrated relative risk after treatment with ARK-1 was 0.15 (95% confidence interval: 0.07–0.29, P

  14. Analysis of Quorum-Sensing-Dependent Control of Rhizosphere-Expressed (rhi) Genes in Rhizobium leguminosarum bv. viciae

    OpenAIRE

    Rodelas, Belen; Lithgow, James K.; Wisniewski-dye, Florence; Hardman, Andrea; Wilkinson, Adam; Economou, Anastassios; Williams, Paul; Downie, J. Allan

    1999-01-01

    The rhi genes of Rhizobium leguminosarum biovar viciae are expressed in the rhizosphere and play a role in the interaction with legumes, such as the pea. Previously (K. M. Gray, J. P. Pearson, J. A. Downie, B. E. A. Boboye, and E. P. Greenberg, J. Bacteriol. 178:372–376, 1996) the rhiABC operon had been shown to be regulated by RhiR and to be induced by added N-(3-hydroxy-7-cis-tetradecenoyl)-l-homoserine lactone (3OH,C14:1-HSL). Mutagenesis of a cosmid carrying t...

  15. Involvement of Genes on a Megaplasmid in the Acid-Tolerant Phenotype of Rhizobium leguminosarum Biovar Trifolii

    OpenAIRE

    Chen, Hancai; Gartner, Elena; Rolfe, Barry G.

    1993-01-01

    The acid-tolerant Rhizobium leguminosarum biovar trifolii strain ANU1173 exhibited several new phenotypes when cured of its symbiotic (Sym) plasmid and the second largest megaplasmid. Strain P22, which has lost these two plasmids, had reduced exopolysaccharide production and cell mobility on TY medium. The parent strain ANU1173 was able to grow easily in laboratory media at pH 4.5, whereas the derivative strain P22 was unable to grow in media at a pH of

  16. Response of chickpea (cicer arietinum L.) to various levels of phosphorus and rhizobium inoculation under rainfed condition

    International Nuclear Information System (INIS)

    A field experiment was conducted to evaluate the effect of phosphorus (P) levels and Rhizobium inoculation on yield-components and grain-yield of (chickpea c.v. NIFA-88) under rain fed conditions at Arid Zone Research Institute, Dera Ismail Khan, during 2003- 04. The treatments consisted of P levels; 0, 30, 60 and 90 kg ha-I, with and without inoculum. A basal dose of 20 kg ha-l nitrogen was applied just before sowing, at the time of seedbed preparation. The experiment was laid out according to the randomized complete block design, with three replications. The results showed significant variation in number of pods per plant, 1000 seed weight and grain yield, with the application of P and Rhizobium inoculum. The maximum number of pods per plant (25.00) was recorded in the plots receiving 60 kg P/sub 2/ O/sub 5/ h a/sup -l/ plus inoculum, but was statistically at par with the pods produced by the treatment of 90 kg P/sub 2/ O/sub 5/ ha-l plus inoculum (24.67). Phosphorus levels plus inoculum gave 11.87 percent increased number of pods per plant over mere P levels. Similarly, the maximum 1000 seed weight of 197.0 g was recorded at the rate 90 and 60 kg P/sub 2/O/sub 5/ ha-1 plus inoculum and 90 kg P/sub 2/ O/sub 5/ ha-l alone. The highest grain-yield of 1,317 kg ha/sup -l/ was obtained from the treatments where P was applied at the rate 90 and 60 kg ha-I with inoculum. The grain yield was increased 8.54 percent when P levels were applied with inoculums, as compared to Pa applied with inoculums, as compared to Palone, on average basis. Hence, it can be concluded from the study that (I) Rhizobium inoculum application alone can increase yield, and (II) 60 kg P/sub 2/ O/sub 5/ ha-l is the most economical dose to be used with Rhizobium inoculum for obtaining higher grain-yield of chickpea. (author)

  17. Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor

    OpenAIRE

    Bonomi, Herna?n R.; Posadas, Diana M.; Paris, Gasto?n; Carrica, Mariela Del Carmen; Frederickson, Marcus; Pietrasanta, Li?a Isabel; Bogomolni, Roberto A.; Zorreguieta, Angeles; Goldbaum, Fernando A.

    2012-01-01

    Rhizobium leguminosarum is a soil bacterium that infects root hairs and induces the formation of nitrogen-fixing nodules on leguminous plants. Light, oxygen, and voltage (LOV)-domain proteins are blue-light receptors found in higher plants and many algae, fungi, and bacteria. The genome of R. leguminosarum bv. viciae 3841, a pea-nodulating endosymbiont, encodes a sensor histidine kinase containing a LOV domain at the N-terminal end (R-LOV-HK). R-LOV-HK has a typical LOV domain absorption spec...

  18. Organization and partial sequence of a DNA region of the Rhizobium leguminosarum symbiotic plasmid pRL6JI containing the genes fixABC, nifA, nifB and a novel open reading frame

    OpenAIRE

    Gro?nger, Petra; Manian, Sundaram S.; Reila?nder, Helmut; O´connell, Michael; Priefer, Ursula B.; Pu?hler, Alfred

    1987-01-01

    By hybridization and heteroduplex studies the fixABC and nifA genes of the Rhizobium leguminosarum symbiotic plasmid pRL6JI have been identified. DNA sequencing of the region containing nifA showed an open reading frame of 1557 bp encoding a protein of 56, 178 D. Based on sequence homology, this ORF was confirmed to correspond to the nifA gene. Comparison of three nifA proteins (Klebsiella pneumoniae, Rhizobium meliloti, Rhizobium leguminosarum) revealed only a weak relationship in their N-te...

  19. Identification of protein secretion systems and novel secreted proteins in Rhizobium leguminosarum bv. viciae

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    Krehenbrink Martin

    2008-01-01

    Full Text Available Abstract Background Proteins secreted by bacteria play an important role in infection of eukaryotic hosts. Rhizobia infect the roots of leguminous plants and establish a mutually beneficial symbiosis. Proteins secreted during the infection process by some rhizobial strains can influence infection and modify the plant defence signalling pathways. The aim of this study was to systematically analyse protein secretion in the recently sequenced strain Rhizobium leguminosarum bv. viciae 3841. Results Similarity searches using defined protein secretion systems from other Gram-negative bacteria as query sequences revealed that R. l. bv. viciae 3841 has ten putative protein secretion systems. These are the general export pathway (GEP, a twin-arginine translocase (TAT secretion system, four separate Type I systems, one putative Type IV system and three Type V autotransporters. Mutations in genes encoding each of these (except the GEP were generated, but only mutations affecting the PrsDE (Type I and TAT systems were observed to affect the growth phenotype and the profile of proteins in the culture supernatant. Bioinformatic analysis and mass fingerprinting of tryptic fragments of culture supernatant proteins identified 14 putative Type I substrates, 12 of which are secreted via the PrsDE, secretion system. The TAT mutant was defective for the symbiosis, forming nodules incapable of nitrogen fixation. Conclusion None of the R. l. bv. viciae 3841 protein secretion systems putatively involved in the secretion of proteins to the extracellular space (Type I, Type IV, Type V is required for establishing the symbiosis with legumes. The PrsDE (Type I system was shown to be the major route of protein secretion in non-symbiotic cells and to secrete proteins of widely varied size and predicted function. This is in contrast to many Type I systems from other bacteria, which typically secrete specific substrates encoded by genes often localised in close proximity to the genes encoding the secretion system itself.

  20. Nodulation gene factors and plant response in the Rhizobium-legume symbiosis. [Nodulation

    Energy Technology Data Exchange (ETDEWEB)

    Long, S.R.

    1990-01-01

    Our original application aimed to identify genes outside the common nod region involved in nodulation and host range of alfalfa. This has been revised by adding other studies on nodulation gene action and removing molecular studies of gene action. Our restated goals and progress are as follows. An early goal was identification and characterization of additional nodulation genes. By means of transposon mutagenesis, mapping and marker exchange we have established 87 independent mutations in a 20kb area represented by plasmid pRmJT5. We discovered four new genes: nodP, nodD3, syrA and syrM. The sequence, start site and protein product for nodFe, nodG, and nodH were also identified. Regulation of nod FEGH was studied. nod FEGH can be induced by luteolin in the presence of noodle; nodD1; noD3 and syrM, a symbiotic regulator gene also increase transcription of nod FEGH. syrA will interact with syrM; syrM also regulates exopolysaccharide genes and is believed to be a master regulator. As part of these studies, an in vitro transcription/translation system for Rhizobium was developed. Adjacent to nodP we discussed nodQ, nodPQ occurrs in two highly consumed copies. nodQ appears by sequence analysis to be similar to initiation and elongation factors, with the highest homology in the GDP binding domain. We have also investigated the nod strain, WL131. WL131 has an insertion, ISRm3, interrupting nodG, and a nonsase mutation in nodH, nodH is responsible for the lack of nodulation. We are currently investigating supernatant factors, host range effects C by spot inoculation, glucaronidase fusion proteins, and are developing, a single root hair inoculation protocol. 7 refs., 6 figs., 1 tab.

  1. Optimización de las condiciones de fermentación para la producción de polihidroxibutirato por Rhizobium tropici

    Directory of Open Access Journals (Sweden)

    Yuliet Franco

    2009-01-01

    Full Text Available Los polihidroxialcanoatos (PHAs, son poliésteres acumulados intracelularmente como materiales de reserva de carbono y energía por varios microorganismos. El representante más común de esta familia es el poli-b-hidroxibutirato (PHB. Estos biopolímeros se consideran buenos sustitutos de los plásticos sintéticos derivados del petróleo por ser biodregadrables. Sin embargo, la mayor desventaja para la comercialización de los PHA son sus elevados costos de producción comparados con los plásticos derivados del petróleo. La optimización del proceso de fermentación, es una de las estrategias más utilizadas para reducir estos costos. Este trabajo tuvo como objetivos determinar el valor óptimo de pH inicial de la fermentación para la producción de PHB, así como optimizar las condiciones de agitación y aeración del proceso para el rendimiento producto biomasa y para la acumulación de PHB por la cepa Rhizobium tropici 3. La optimización del pH inicial se realizó en zaranda orbital ajustando el valor entre 6 y 8 y se modeló la relación entre el pH y la concentración de PHB (g · L-1 mediante la utilización de polinomios ortogonales. Se definió que el pH inicial óptimo con el cual se asegura la mayor producción de PHB es 6,58 ± 0,2. La búsqueda de los valores óptimos de agitación-aeración para la producción de PHB y para el rendimiento producto-biomasa, se realizó mediante el empleo de un diseño central compuesto Box-Wilson. Las fermentaciones se realizaron en un fermentador de 7,5 L con 5 L de medio de cultivo optimizado. Se determinó que los valores óptimos para la producción fueron 500 r · min-1 y 1 vvm (volumen de aire por minuto por volumen de medio de cultivo para la agitación y la aeración respectivamente y para el rendimiento producto-biomasa, los valores óptimos fueron 472 r · min-1 y 1,55 vvm.

  2. Production of Poly &beta-Hydroxybutyric Acid (PHB by Rhizobium elti and Pseudomonas stutzeri

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    Elsayed B. Belal

    2013-11-01

    Full Text Available The amount of chemosynthetic plastic waste increases every year and exact time for its degradation is unknown. Two poly &beta-Hydroxybutyric producing bacteria from different microbial sources were isolated and characterized for their morphological, biochemical properties. Based on their 16S rDNA, they were identified as Rhizobium elti E1 and Pseudomonas stutzeri E114. The bacterial strains were screened for PHB production and compared for the intensity of fluorescence using Nile red staining methods. PHB production conditions were optimized with different carbon and nitrogen sources, the highest PHB production was observed with mannitol, sucrose and ammonium sulphate by R. elti and P. stutzeri, respectively. Regarding incubation time as well as temperature and pH, optimum PHB production conditions were 48 h, 30?C and 7, respectively. R. elti P. stutzeri are capable of accumulating appreciable levels of PHB from glucose, xylose, lactose, whey, molasses, sugar cane bagasse, rice straw hydroysate when 2% from all substrates were used an alternative carbon for the PHB production. Ammonium sulphate was the best nitrogen source. C/N ratio was also one of the factors that affected the production of PHB. The ratio of C/N that reaches 20:1 was considered the best ratio to produce the highest production of PHB. The highest yield of PHB was done by P. stutzeri more than R. elti. The present study provide the useful data about the optimized conditions for PHB production by R. elti and P. stutzeri that can be utilized for industrial production of PHB, a fast emerging alternative of non biodegradable plastics.

  3. Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress

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    Gomes Douglas

    2012-05-01

    Full Text Available Abstract Background Rhizobium tropici strain PRF 81 (= SEMIA 4080 has been used in commercial inoculants for application to common-bean crops in Brazil since 1998, due to its high efficiency in fixing nitrogen, competitiveness against indigenous rhizobial populations and capacity to adapt to stressful tropical conditions, representing a key alternative to application of N-fertilizers. The objective of our study was to obtain an overview of adaptive responses to heat stress of strain PRF 81, by analyzing differentially expressed proteins when the bacterium is grown at 28°C and 35°C. Results Two-dimensional gel electrophoresis (2DE revealed up-regulation of fifty-nine spots that were identified by MALDI-TOF/TOF-TOF. Differentially expressed proteins were associated with the functional COG categories of metabolism, cellular processes and signaling, information storage and processing. Among the up-regulated proteins, we found some related to conserved heat responses, such as molecular chaperones DnaK and GroEL, and other related proteins, such as translation factors EF-Tu, EF-G, EF-Ts and IF2. Interestingly, several oxidative stress-responsive proteins were also up-regulated, and these results reveal the diversity of adaptation mechanisms presented by this thermotolerant strain, suggesting a cross-talk between heat and oxidative stresses. Conclusions Our data provide valuable protein-expression information relevant to the ongoing genome sequencing of strain PRF 81, and contributes to our still-poor knowledge of the molecular determinants of the thermotolerance exhibited by R. tropici species.

  4. Genome Sequences of the Lignin-Degrading Pseudomonas sp. Strain YS-1p and Rhizobium sp. Strain YS-1r Isolated from Decaying Wood

    Science.gov (United States)

    Prabhakaran, Madhu; Couger, Matthew B.; Jackson, Colin A.; Weirick, Tyler

    2015-01-01

    Pseudomonas sp. strain YS-1p and Rhizobium sp. strain YS-1r were isolated from a lignin-degrading enrichment culture. The isolates degraded lignin-derived monomers, dimers, alkali lignin, and, to a smaller extent (3% to 5%), lignin in switch grass and alfalfa. Genome analysis revealed the presence of a variety of lignin-degrading genes. PMID:25744986

  5. Roles of flagella, lipopolysaccharide, and a Ca2+-dependent cell surface protein in attachment of Rhizobium leguminosarum biovar viciae to pea root hair tips.

    OpenAIRE

    Smit, G.; Kijne, J. W.; Lugtenberg, B. J.

    1989-01-01

    The relationship between Ca2+-dependent cell surface components of Rhizobium leguminosarum biovar viciae, motility, and ability to attach to pea root hair tips was investigated. In contrast to flagella and lipopolysaccharide, a small protein located on the cell surface was identified as the Ca2+-dependent adhesin.

  6. Genome Sequences of the Lignin-Degrading Pseudomonas sp. Strain YS-1p and Rhizobium sp. Strain YS-1r Isolated from Decaying Wood.

    Science.gov (United States)

    Prabhakaran, Madhu; Couger, Matthew B; Jackson, Colin A; Weirick, Tyler; Fathepure, Babu Z

    2015-01-01

    Pseudomonas sp. strain YS-1p and Rhizobium sp. strain YS-1r were isolated from a lignin-degrading enrichment culture. The isolates degraded lignin-derived monomers, dimers, alkali lignin, and, to a smaller extent (3% to 5%), lignin in switch grass and alfalfa. Genome analysis revealed the presence of a variety of lignin-degrading genes. PMID:25744986

  7. Draft Genome Sequence of Rhizobium mesoamericanum STM3625, a Nitrogen-Fixing Symbiont of Mimosa pudica Isolated in French Guiana (South America).

    Science.gov (United States)

    Moulin, Lionel; Mornico, Damien; Melkonian, Rémy; Klonowska, Agnieszka

    2013-01-01

    Rhizobium mesoamericanum STM3625 is a Mimosa pudica symbiont isolated in French Guiana. This strain serves as a model bacterium for comparison of adaptation to mutualism (symbiotic traits, bacterial genetic programs for plant infection) between alpha and beta rhizobial symbionts of Mimosa pudica. PMID:23405314

  8. Accumulation of lipochitin oligosaccharides and NodD-activating compounds in an efficient plant--Rhizobium nodulation assay.

    Science.gov (United States)

    Tak, Teun; van Spronsen, Paulina C; Kijne, Jan W; van Brussel, Anton A N; Boot, Kees J M

    2004-07-01

    During legume plant--Rhizobium spp. interactions, leading to the formation of nitrogen-fixing root nodules, the two major determinants of host plant-specificity are plant-produced nod gene inducers (NodD protein activating compounds) and bacterial lipochitin oligosaccharides (LCOs or Nod factors). In a time course, we describe the accumulation of LCOs in an efficient nodulation assay with Vicia sativa subsp. nigra and Rhizobium leguminosarum, in connection with the presence of NodD-activating compounds in the exudate of V. sativa roots. Relatively small amounts of both LCOs and NodD-activating compounds were found to be required for initiation of nodulation during the first days after inoculation. A strong increase in the amount of NodRlv-V[18:4,Ac] LCOs preceded root infection and nodule primordium formation. In contrast to the situation with non-nodulating rhizobia and nonmitogenic LCOs, the amount of NodD-activating compounds in the culture medium remained small after addition of nodulating rhizobia or mitogenic LCOs. Furthermore, addition of nodulating rhizobia or mitogenic LCOs resulted in nearly complete inhibition of root hair formation and elongation, whereas nonmitogenic LCOs stimulated root hair growth. Retention of NodD-activating compounds in the root may inhibit root hair growth. PMID:15242176

  9. Role of Some Chemical Compounds on the Detoxification of Rhizobium leguminsarum biovar vicia by Some Heavy Metals

    Directory of Open Access Journals (Sweden)

    Sanaa Mostafa El-Deeb

    2005-01-01

    Full Text Available The toxic effect of different concentrations of some heavy metals (Cadmium, Zinc and Lead on the growth of cultured Rhizobium leguminsarum biovar vicia was studied and their LD50 toxicity were determined. The 50% inhibition of bacterial growth was achieved by contaminating the culture with 2.1 ?M of Cadmium, 30 ?M of Zinc or 290 ?M of Lead. In attempts to counteract the toxic effect of these heavy metals, several compounds were tested to reactivate the Rhizobium growth and to abolish the toxic effect, either partially or totally, which is caused by the presence of heavy metals (as in case of presence of sewage sludge. Positive results were obtained from the addition of some of these compounds as: Mannitol and Glutamate, 5,7 dihydroxyflavone, Thiamine hydrochloride, Calcium chloride and Calcium ionophore A23187. Their most effective concentrations were determined for each compound in the presence of each heavy metal at its concentration of LD50. An average recovery in bacterial growth, in presence of each of Cadmium, Zinc and Lead, individually, were as fellows: 97, 90, 88, 84 and 83%, due to the individual addition of 214 mM mannitol + 42 mM glutamate, 0.96 mM thiamine hydrochloride, 7.79 mM calcium chloride, 2.98 x 10-3 mM calcium ionophore A23187 and 0.69 mM of 5,7-dihydroxy flavone, resepectively.

  10. Population structure of root nodulating Rhizobium leguminosarum in Vicia cracca populations at local to regional geographic scales.

    Science.gov (United States)

    Van Cauwenberghe, Jannick; Verstraete, Brecht; Lemaire, Benny; Lievens, Bart; Michiels, Jan; Honnay, Olivier

    2014-12-01

    The genetic diversity and population structure of about 350 Rhizobium leguminosarum biovar viciae isolates from Vicia cracca were analysed. A hierarchical sampling design was used covering three regions, one region in Belgium and two in France, in which multiple local V. cracca populations were sampled. Rhizobium isolates were genotyped using RAPD and by sequencing two chromosomal housekeeping genes (glnII and recA) and one plasmid-borne gene (nodC). Twenty-six nodC types and sixty-seven chromosomal types were identified, many of which appeared to be regional or local endemics. We found strong genetic differentiation both among V. cracca populations that are separated by only a few kilometres, and among regions that are 50 to 350km apart. Despite significant plasmid exchange, chromosomal and nod types were similarly structured among host populations and regions. We found two lineages of which one prevailed in the Belgian region while the other dominated the French regions. Although a significant correlation between genetic differentiation and geographic distance was found, it is deemed more likely that the observed biogeographic patterns are rather due to coevolutionary interactions and environmental pressures. Furthermore, the impact of recombination on the chromosomal differentiation was found to be considerable. PMID:25199986

  11. Lipid A biosynthesis in Rhizobium leguminosarum: Role of a 2-keto-3-deoxyoctulosonate-activated 4{prime} phosphatase

    Energy Technology Data Exchange (ETDEWEB)

    Price, N.P.J.; Jeyaretnam, B.; Carlson, R.W. [Univ. of Georgia, Athens, GA (United States)] [and others

    1995-08-01

    Lipid A from several strains of the N{sub 2}-fixing bacterium Rhizobium leguminosarum displays significant structural differences from Escherichia coli lipid A, one of which is the complete absence of phosphate groups. However, the first seven enzymes of E. coli lipid A biosynthesis, leading from UDP-GlcNAc to the phosphorylated intermediate, 2-keto-3-deoxyoctulosonate (Kdo{sub 2})-lipid IV{sub A}, are present in R. leguminosarum. We now describe a membrane-bound phosphatase in R. leguminosarum extracts that removes the 4{prime} phosphate of Kdo{sub 2}-lipid IV{sub A}. The 4{prime} phosphatase is selective for substrates containing the Kdo domain. It is present in extracts of R. leguminosarum biovars phaseoli, viciae, and trifolii but is not detectable in E. coli and Rhizobium meliloti. A nodulation-defective strain (24AR) of R. leguminosarum bovar trifolii, known to contain a 4{prime} phosphate residue on its lipid A, also lacks measurable 4{prime} phosphatase activity. the Kdo-dependent 4{prime} phosphatase appears to be a key reaction in a pathway for generating phosphate-deficient lipid A.

  12. Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation

    Energy Technology Data Exchange (ETDEWEB)

    Skorupska, A.; Derylo, M. [Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland)

    1993-12-31

    A 5.4 kb BamHI fragment of Rhizobium leguminosarum (R.l.) bv. trifolii TA1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). This fragment was strongly hybridized to the total DNA from DNA from R.l. bv. viciae and bv. phaseoli digested with EcoRI. No homology was found with total DNA of R. melilotic and Rhizobium sp. NGR 234. The exo genes R.l. bv. trifolii TA1 conjugally introduced into R.l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abortive and did not fix nitrogen. On the other hand, Phaseolus beans infected with R.l. bv. trifolii exo genes formed the nitrogen-fixing nodules. It can be conduced that additional copies of exo genes introduced into wild type R.l. strains can disturb the synthesis of acidic exopolysaccharides and affect symbiosis of the plants forming indeterminate nodules, but do not affect symbiosis of the plants forming the determinate nodules. (author). 29 refs, 2 figs, 2 tabs.

  13. Rhizobium leguminosarum is the symbiont of lentils in the Middle East and Europe but not in Bangladesh.

    Science.gov (United States)

    Harun-or Rashid, M; Gonzalez, Javier; Young, J Peter W; Wink, Michael

    2014-01-01

    Lentil is the oldest of the crops that have been domesticated in the Fertile Crescent and spread to other regions during the Bronze Age, making it an ideal model to study the evolution of rhizobia associated with crop legumes. Housekeeping and nodulation genes of lentil-nodulating rhizobia from the region where lentil originated (Turkey and Syria) and regions to which lentil was introduced later (Germany and Bangladesh) were analyzed to determine their genetic diversity, population structure, and taxonomic position. There are four different lineages of rhizobia associated with lentil nodulation, of which three are new and endemic to Bangladesh, while Mediterranean and Central European lentil symbionts belong to the Rhizobium leguminosarum lineage. The endemic lentil grex pilosae may have played a significant role in the origin of these new lineages in Bangladesh. The presence of R. leguminosarum with lentil at the center of origin and in countries where lentil was introduced later suggests that R. leguminosarum is the original symbiont of lentil. Lentil seeds may have played a significant role in the initial dispersal of this Rhizobium species within the Middle East and on to other countries. Nodulation gene sequences revealed a high similarity to those of symbiovar viciae. PMID:24033582

  14. Expression of Rhizobium leguminosarum CFN42 genes for lipopolysaccharide in strains derived from different R. leguminosarum soil isolates

    Energy Technology Data Exchange (ETDEWEB)

    Brink, B.A.; Noel, K.D. (Marquette Univ., Milwaukee, WI (USA)); Miller, J.; Carlson, R.W. (Eastern Illinois Univ., Charlston (USA))

    1990-02-01

    Two mutant derivatives of Rhizobium leguminosarum ANU843 defective in lipopolysaccharide (LPS) were isolated. The LPSs of both mutants lacked O antigen and some sugar residues of the LPS core oligosaccharides. Genetic regions previously cloned from another Rhizobium leguminosarum wild-type isolate, strain CFN42, were used to complement these mutants. One mutant was complemented to give LPS that was apparently identical to the LPS of strain ANU843 in antigenicity, electrophoretic mobility, and sugar composition. The other mutant was complemented by a second CFN42lps genetic region. In this case the resulting LPS contained O-antigen sugars characteristic of donor strain CFN42 and reacted weakly with antiserum against CFN42 cells, but did not react detectably with antiserum against ANU843 cells. Therefore, one of the CFN42 lps genetic regions specifies a function that is conserved between the two R. leguminosarum wild-type isolates, whereas the other region, at least in part, specifies a strain-specific LPS structure. Transfer of these two genetic regions into wild-type strains derived from R. leguminosarum ANU843 and 128C53 gave results consistent with this conclusion. The mutants derived from strain ANU843 elicited incompletely developed clover nodules that exhibited low bacterial populations and very low nitrogenase activity. Both mutants elicited normally developed, nitrogen-fixing clover nodules when they carried CFN42 lps DNA that permitted synthesis of O-antigen-containing LPS, regardless of whether the O antigen was the one originally made by strain ANU843.

  15. Homo- and heterotypic interactions between Pss proteins involved in the exopolysaccharide transport system in Rhizobium leguminosarum bv. trifolii.

    Science.gov (United States)

    Marczak, Ma?gorzata; D?wierzy?ska, Monika; Skorupska, Anna

    2013-04-01

    Rhizobium leguminosarum produces large amounts of exopolysaccharide (EPS) that has been shown to be an important determinant of successful nitrogen-fixing symbiosis with legume plants. EPS is assembled in a Wzx/Wzy-dependent manner, and proteins involved in the process are proposed to form a complex that enables coupling the synthesis of EPS subunits with their polymerization and transport. Pss proteins, which are encoded within the chromosomal polysaccharide synthesis cluster of Rhizobium leguminosarum bv. trifolii TA1, were subjected to interaction analysis. PssN was shown to form multimeric complexes in the outer membrane and interact with the extracellular PssO protein and the inner membrane oligomeric PssP co-polymerase. PssO was demonstrated to form oligomers in the presence of the cross-linker. Bacterial two-hybrid analysis showed that PssP interacts with PssL and PssT, counterparts of Gram-negative bacteria Wzx and Wzy proteins. Membrane topology of PssT is discussed in the context of its plausible Wzy-like polymerase activity, interactions with PssP and a possible impact of these interactions on EPS polymerization and chain length determination. The importance of protein-protein and putative protein-polysaccharide interactions in EPS transport is discussed. A topology model for the EPS transport system, with highlights on localization, functions and interactions between the Pss proteins, is proposed. PMID:23241669

  16. Genetic Factors in Rhizobium Affecting the Symbiotic Carbon Costs of N2 Fixation and Host Plant Biomass Production

    DEFF Research Database (Denmark)

    SkØt, L.; Hirsch, P. R.

    1986-01-01

    The effect of genetic factors in Rhizobium on host plant biomass production and on the carbon costs of N2 fixation in pea root nodules was studied. Nine strains of Rhizobium leguminosarum were constructed, each containing one of three symbiotic plasmids in combination with one of three different genomic backgrounds. The resulting strains were tested in symbiosis with plants of Pisum sativum using a flow-through apparatus in which nodule nitrogenase activity and respiration were measured simultaneously under steady state conditions. Nodules formed by strains containing the background of JI6015 had the lowest carbon costs of N2 fixation (7.10–8.10 ?mol C/?mol N2), but shoot dry weight of those plants was also smaller than that of plants nodulated by strains with the background of B151 or JI8400. Nodules formed by these two strain types had carbon costs of N2 fixation varying between 11.26 and 13.95 ?mol C/?mol N2. The effect of symbiotic plasmids on the carbon costs was relatively small. A time-course experiment demonstrated that nodules formed by a strain derived from JI6015 were delayed in the onset of nitrogenase activity and had a lower rate of activity compared to nodules induced by a strain with the background of B151. The relationship between nitrogenase activity, carbon costs of N2 fixation and host plant biomass production is discussed.

  17. Characterization and symbiotic importance of acidic extracellular polysaccharides of Rhizobium sp. strain GRH2 isolated from acacia nodules.

    Science.gov (United States)

    Lopez-Lara, I M; Orgambide, G; Dazzo, F B; Olivares, J; Toro, N

    1993-05-01

    Rhizobium sp. wild-type strain GRH2 was originally isolated from root nodules of the leguminous tree Acacia cyanophylla and has a broad host range which includes herbaceous legumes, e.g., Trifolium spp. We examined the extracellular exopolysaccharides (EPSs) produced by strain GRH2 and found three independent glycosidic structures: a high-molecular-weight acidic heteropolysaccharide which is very similar to the acidic EPS produced by Rhizobium leguminosarum biovar trifolii ANU843, a low-molecular-weight native heterooligosaccharide resembling a dimer of the repeat unit of the high-molecular-weight EPS, and low-molecular-weight neutral beta (1,2)-glucans. A Tn5 insertion mutant derivative of GRH2 (exo-57) that fails to form acidic heteropolysaccharides was obtained. This Exo- mutant formed nitrogen-fixing nodules on Acacia plants but infected a smaller proportion of cells in the central zone of the nodules than did wild-type GRH2. In addition, the exo-57 mutant failed to nodulate several herbaceous legume hosts that are nodulated by wild-type strain GRH2. PMID:8491702

  18. Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation

    International Nuclear Information System (INIS)

    A 5.4 kb BamHI fragment of Rhizobium leguminosarum (R.l.) bv. trifolii TA1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). This fragment was strongly hybridized to the total DNA from DNA from R.l. bv. viciae and bv. phaseoli digested with EcoRI. No homology was found with total DNA of R. melilotic and Rhizobium sp. NGR 234. The exo genes R.l. bv. trifolii TA1 conjugally introduced into R.l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abortive and did not fix nitrogen. On the other hand, Phaseolus beans infected with R.l. bv. trifolii exo genes formed the nitrogen-fixing nodules. It can be conduced that additional copies of exo genes introduced into wild type R.l. strains can disturb the synthesis of acidic exopolysaccharides and affect symbiosis of the plants forming indeterminate nodules, but do not affect symbiosis of the plants forming the determinate nodules. (author). 29 refs, 2 figs, 2 tabs

  19. Respuesta de combinaciones Rhizobium - Clitoria ternatea en condiciones de estrés salino en el Valle del Cauto en Cuba / Response of Rhizobium - Clitoria ternatea combinations under salt stress in the Cauto Valley in Cuba

    Scientific Electronic Library Online (English)

    Raúl Carlos, López Sánchez; Roeland, Samson; Patrick, Vandamme; Bettina, Eichler-Löbermann; Ernesto, Gómez Padilla.

    2011-06-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se estudió la respuesta de Clitoria ternatea en condiciones de estrés salino a la inoculación con aislamientos nativos y cepas comerciales de rizobios. El estudio se realizó en condiciones de invernadero y de campo. El efecto de tres cepas de rizobio (Jd19, 1031 y 1032) en el rendimiento y parámetro [...] s de la fijación de nitrógeno se comparó con el testigo y el tratamiento con fertilización nitrogenada. En el experimento en invernadero los mejores resultados para el rendimiento y parámetros de fijación de nitrógeno se encuentran con el aislamiento nativo de rizobio Jd19. En este tratamiento se encontraron los valores más altos de peso seco de masa aérea y raíces y de acumulación de nitrógeno. Además en el tratamiento con el aislamiento Jd19 se mostraron los valores más altos de relación K:Na, contenido de ureidos, clorofila a y b en el tallo y el mejor índice de efectividad de la inoculación. En el experimento de campo el tratamiento con el aislamiento Jd19 tuvo el mejor efecto positivo en comparación con el resto de los tratamientos. Los resultados indican que la combinación Clitoria ternatea-Jd19 es más eficiente en condiciones de estrés salino, y es posible su introducción a amplia escala en suelos afectados por la salinidad. Abstract in english The purpose of the present study was to examine response of Clitoria tarnatea under salt stress to inoculation with native isolates and commercial strains of Rhizobium. This study was carried out both in greenhouse and field conditions. Effects of three Rhizobium strains (Jd19, 1031 and 1032) were c [...] ompared to control and mineral N fertilization regarding yield and nitrogen fixation parameters. In the greenhouse experiment the best results for yield and nitrogen fixation parameters were found for the Jd19 native isolate treatment, where the highest dry weight of both shoots and roots and also of nitrogen uptake were observed. Besides, this treatment showed the highest K:Na ratio, as well as of contents of ureides, of a and b chlorophyll in stem and the best inoculation effectiveness index. In the field test, the Jd19 treatment showed the best positive effect in comparison to the other treatments. Results indicate that the Clitoria ternatea-Jd19 Rhizobium strain combination is the most efficient under salt stress and also that its wide scale introduction in saline soils is possible.

  20. Effects of rhizobium, arbuscular mycorrhizal fungi and anion content of simulated rain on subterranean clover.

    Science.gov (United States)

    Shafer, S R; Schoeneberger, M M; Horton, S J; Davey, C B; Miller, J E

    1996-01-01

    An experiment was conducted to determine the extent to which rhizobia, mycorrhizal fungi, and anions in simulated rain affect plant growth response to acid deposition. Germinating subterranean clover seeds were planted in steam-pasteurized soil in pots and inoculated with Rhizobium leguminosarum, Glomus intraradices, Glomus etunicatum, R. leguminosarum + G. intraradices, R. leguminosarum + G. etunicatum, or no microbial symbionts. Beginning 3 weeks later, plants and the soil surface were exposed to simulated rain in a greenhouse on 3 days week(-1) for 12 weeks. Rain solutions were deionized water amended with background ions only (pH 5.0) or also adjusted to pH 3.0 with HNO3 only, H2SO4 only, or a 50/50 mixture of the two acids. Glomus intraradices colonized plant roots poorly, and G. intraradices-inoculated plants responded like nonmycorrhizal plants to rhizobia and rain treatments. Variation in plant biomass attributable to different rain formulations was strongest for G. etunicatum-inoculated plants, and the effect of rain formulation differed with respect to nodulation by rhizobia. The smallest plants at the end of the experiment were noninoculated plants exposed to rains (0.38 g mean dry weight total for 3 plants pot(-1)). Among nonnodulated plants infected by G. etunicatum, those exposed to HNO3 rain were largest, followed by plants exposed to HNO3 + H2SO4, pH 5.0, and H2SO4 rain, in that order. Among plants inoculated with both R. leguminosarum + G. etunicatum, however, the greatest biomass occurred with pH 5.0 rains, resulting in the largest plants in the study (1.00 g/3 plants). Treatment-related variation among root and shoot biomass data reflected those for whole-plant biomass. Based on quantification of biomass and N concentrations in shoot and root tissues, total N content of plants inoculated with G. etunicatum alone and exposed to the HNO3 + H2SO4 rains was approximately the same as plants inoculated with R. leguminosarum + G. entunicatum and exposed to pH 5 rains. Thus, the acid-mixture rains and rhizobia under no acid deposition provided approximately equal amounts of N in biomass. The significant interactions among rain formulation and the symbiotic status of the plants suggest that conclusions concerning the impact of acid deposition on plants in the environment cannot be considered reliable because most experiments on which such assessments are based have not tested confounding influences of microorganisms and precipitation characteristics. PMID:15091411

  1. Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium / Rheological properties and effect of the salt addition on the exopolysaccharides viscosity produced by bacteria of Rhizobium genus

    Scientific Electronic Library Online (English)

    Gabriel, Aranda-Selverio; Ana Lúcia Barretto, Penna; Luciana Frizarin, Campos-Sás; Osvaldo dos, Santos Junior; Ana Flora Dalberto, Vasconcelos; Maria de Lourdes Corradi da, Silva; Eliana Gertrudes Macedo, Lemos; João Carlos, Campanharo; Joana Léa Meira, Silveira.

    Full Text Available [...] Abstract in english Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4) produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of t [...] hese molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.

  2. Evaluation finale INTERREG III Suisse

    OpenAIRE

    Schnell, Klaus-dieter; Pfister Giauque, Barbara

    2006-01-01

    Entre 2000 et 2006, la Confédération a participé à hauteur de 39 millions de francs à l'initiative communautaire européenne INTERREG III, afin de soutenir la coopération transfrontalière, transnationale et interrégionale. L'évaluation finale de ce programme, réalisée en collaboration entre l'IDT-HSG et la C.E.A.T., doit permettre de rendre compte de l'utilisation de ces fonds et de tirer le bilan des réalisations. A l'avenir, la promotion de la coopé...

  3. Phenotype profiling of Rhizobium leguminosarum bv. trifolii clover nodule isolates reveal their both versatile and specialized metabolic capabilities.

    Science.gov (United States)

    Mazur, Andrzej; Stasiak, Gra?yna; Wielbo, Jerzy; Koper, Piotr; Kubik-Komar, Agnieszka; Skorupska, Anna

    2013-04-01

    Rhizobium leguminosarum bv. trifolii (Rlt) are soil bacteria inducing nodules on clover, where they fix nitrogen. Genome organization analyses of 22 Rlt clover nodule isolates showed that they contained 3-6 plasmids and majority of them possessed large (>1 Mb), chromid-like replicon with exception of four Rlt strains. The Biolog phenotypic profiling comprising utilization of C, N, P, and S sources and tolerance to osmolytes and pH revealed metabolic versatility of the Rlt strains. Statistical analyses of our results showed a clear bias toward specific metabolic preferences, tolerance to unfavorable osmotic conditions, and increased nodulation activity of the strains having smaller amount of extrachromosomal DNA. The K5.4 and K4.15 lacking a large megaplasmid possessed substantially diverse metabolism and belonged to effective clover inoculants. In conclusion, besides overall metabolic versatility, some metabolic specialization may enable rhizobia to persist in variable environments and to compete successfully with other bacteria. PMID:23417392

  4. Morphogenesis of root nodules in white clover. I. Effective root nodules induced by the wild type Rhizobium leguminosarium biovar. trifolii

    Directory of Open Access Journals (Sweden)

    Barbara ?otocka

    1997-12-01

    Full Text Available The research aimed at investigating the morphogenesis of cylindrical root nodules in Trifolium repens L. induced by the wild type Rhizobium leguminosarum biovar. trifolii strain 24. It has been demonstrated that the ontogenesis of a nodule begins with a transverse division of cells of the pericycle followed by the dedifferentiation and divisions of cells of the endodermis and inner layers of the primary root cortex. Shifting of the nodule meristem from its initially lateral to the apical position characteristic for cylindrical nodules was observed. Bacteroidal, cortical and vascular tissues of the nodule are described up to 42 days after inoculation. At that time typical degraded zone had not yet appeared in the nodules.

  5. Extracellular polysaccharides are involved in the attachment of Azospirillum brasilense and Rhizobium leguminosarum to arbuscular mycorrhizal structures

    Directory of Open Access Journals (Sweden)

    V Bianciotto

    2009-12-01

    Full Text Available Arbuscular mycorrhizal (AM fungi, one of the most important component of the soil microbial community, establish physical interactions with naturally occurring and genetically modified bacterial biofertilizers and biopesticides, commonly referred to as plant growth-promoting rhizobacteria (PGPR. We have used a genetic approach to investigate the bacterial components possibly involved in the attachment of two PGPR (Azospirillum and Rhizobium to AM roots and AM fungal structures. Mutants affected in extracellular polysaccharides (EPS have been tested in in vitro adhesion assays and shown to be strongly impaired in the attachment to both types of surfaces as well as to quartz fibers. Anchoring of rhizobacteria to AM fungal structures may have special ecological and biotechnological significance because it may facilitate colonisation of new rhizospheres by the bacteria, and may be an essential trait for the development of mixed inocula.

  6. Rhizobium nodulation protein NodC is an important determinant of chitin oligosaccharide chain length in Nod factor biosynthesis.

    Science.gov (United States)

    Kamst, E; Pilling, J; Raamsdonk, L M; Lugtenberg, B J; Spaink, H P

    1997-04-01

    Synthesis of chitin oligosaccharides by NodC is the first committed step in the biosynthesis of rhizobial lipochitin oligosaccharides (LCOs). The distribution of oligosaccharide chain lengths in LCOs differs between various Rhizobium species. We expressed the cloned nodC genes of Rhizobium meliloti, R. leguminosarum bv. viciae, and R. loti in Escherichia coli. The in vivo activities of the various NodC proteins differed with respect to the length of the major chitin oligosaccharide produced. The clearest difference was observed between strains with R. meliloti and R. loti NodC, producing chitintetraose and chitinpentaose, respectively. In vitro experiments, using UDP-[14C]GlcNAc as a precursor, show that this difference reflects intrinsic properties of these NodC proteins and that it is not influenced by the UDP-GlcNAc concentration. Analysis of oligosaccharide chain lengths in LCOs produced by a R. leguminosarum bv. viciae nodC mutant, expressing the three cloned nodC genes mentioned above, shows that the difference in oligosaccharide chain length in LCOs of R. meliloti and R. leguminosarum bv. viciae is due only to nodC. The exclusive production of LCOs which contain a chitinpentaose backbone by R. loti strains is not due to NodC but to end product selection by Nod proteins involved in further modification of the chitin oligosaccharide. These results indicate that nodC contributes to the host specificity of R. meliloti, a conclusion consistent with the results of several studies which have shown that the lengths of the oligosaccharide backbones of LCOs can strongly influence their activities on host plants. PMID:9079892

  7. Impact of dual inoculation with Rhizobium and PGPR on growth and antioxidant status of Vicia faba L. under copper stress.

    Science.gov (United States)

    Fatnassi, Imen Challougui; Chiboub, Manel; Saadani, Omar; Jebara, Moez; Jebara, Salwa Harzalli

    2015-04-01

    Plant-growth-promoting bacteria (PGPR) may help reduce the toxicity of heavy metals in plants in polluted environments. In this work, the effects of dual inoculation with Rhizobium and PGPR strains on the growth of Vicia faba grown under copper stress were assessed during hydroponic culture. Growth parameters, copper (Cu) accumulation and antioxidant enzyme activities were studied. Copper concentrations above 1mM damaged plant growth, but co-inoculation reduced its harmful effect. Co-inoculation of plants treated with 1mM Cu and 2mM Cu increased the dry weights as compared with Cu-treated and uninoculated plants. However, it decreased copper uptake up to 80% in the roots of 1-mM-Cu-treated plants as compared to non-inoculated control. Copper tolerance in Vicia faba is linked to the activity of antioxidant systems that are modulated by metal concentrations: both superoxide dismutase (SOD) and catalase (CAT) were higher in the presence of Cu; a lower Cu dose of 0.5mM stimulated ascorbate peroxidase (APX) and/or peroxidase (POX) activities in shoots and roots; however in nodules CAT appeared to be the main peroxidase in H2O2 scavenging. The 1mM Cu treatment enhanced SOD, CAT and APX activities in roots and only SOD and POX were activated in shoots. All enzyme activities were inhibited by inoculation of 2mM Cu. The effect of inoculation with copper-accumulating PGPRs and the status of the antioxidant enzyme system were linked to changes in the copper tolerance status of Vicia faba. Our results suggested that Vicia faba inoculation with Rhizobium and PGPR Enterobacter clocae and Pseudomonas sp. could help to alleviate copper stress under hydroponic conditions. This result should be tested under field conditions for soil fertilization and phytostabilisation purposes. PMID:25747267

  8. Screening of isolates and strains of Rhizobium leguminosarum biovar trifolii for heavy metal resistance using buffered media

    Energy Technology Data Exchange (ETDEWEB)

    Chaudri, A.M.; McGrath, S.P. (AFRC Inst. of Arable Crops Research, Harpenden, Herts (United Kingdom). Soil Science Dept.); Giller, K.E. (Univ. of London, Ashford, Kent (United Kingdom). Wye College, Dept. of Biochemistry and Biological Sciences); Angle, J.S. (Univ. of Maryland, College Park, MD (United States). Dept. of Agronomy); Chaney, R.L. (USDA Agricultural Research Service, Environmental Chemistry Lab., Beltsville, MD (United States))

    1993-09-01

    The computer program GEOCHEM-PC was used to calculate the metal ion activities of Cu, Zn, Cd, and Ni in defined media amended with various metal ion buffers at pH 6.6 or 6.0 so that the lowest-observed-effect concentrations (LOECs) of these metals to isolates and strains of Rhizobium leguminosarum biovar trifolii could be determined. Strains from the U.S. Department of Agriculture (USDA) Beltsville (MD) Rhizobium culture collection were generally more tolerant of the metals than any of the isolates from the sludge-treated soil (S-isolates) and those from farm-yard manure-treated soil (F-isolates), although the S- were more metal resistant than the F-isolates. All isolates and strains, however, tolerated much larger concentrations in the buffered systems than those found in the solutions of soils from which they originated. Copper toxicity, using iminodiacetate (IDA), occurred for the F- and S-isolates and USDA strains at concentrations of 16, 47, and 430 [mu]g mL[sup [minus]1], respectively, corresponding to predicted ion activities of 0.002, 0.006, and 0.06 [mu]g ml[sup [minus]1], respectively. The Zn LOECs for the F- and S-isolates, without a buffer, occurred at concentrations of 47 and 207 [mu]g ml[sup [minus]1], respectively, corresponding to predicted ion activities of 37 and 157 [mu]g ml[sup [minus]1], respectively. No toxicity occurred when nitrilotriacetate was used for Cd up to concentrations of 356 [mu]g ml[sup [minus]1]. Nickel concentrations up to 0.6 [mu]g ml[sup [minus]1] had no effect with ethylene-bis(oxyethylenenitrilo)tetraacetate and up to 186 [mu]g ml[sup [minus]1] with IDA.

  9. Improvement of Canola (Brassica napus L.) Inoculated with Rhizobium, Azospirillum and/or Mycorrhizal Fungi Under Salinity Stress

    International Nuclear Information System (INIS)

    Bio fertilization technology was applied for improving canola plant growth and nutrient acquisition in sandy saline soil ,as a biological mean used to develop plant growth and nutrient uptake under salinity stress. Canola was cultivated in pots packed at rate of 7 kg saline sandy soil pot-1, and inoculated with Rhizobium leguminosarum biovar viceae, Azospirillum brasilense strain no. 40 and arbuscular mycorrhizal fungi either solely or in combinations of them. Nitrogen fertilizer was added in form (15NH4)2SO4 with 5%15N atom excess at rate of 0.99 g N pot-1. Maximum dry matter accumulation induced by composite inoculation (Rh + Azo + AM). Na concentrations were frequently affected by Rhizobium and /or mycorrhizae while K was affected by Azospirillum and /or mycorrhizae. Azospirillum enhanced Ca uptake whereas Mg content was responded well to composite inoculants of Rh + Azo + AM. Dual inoculation with Rh + Azo resulted in the highest values of N uptake by plant. Similar effect was noticed with P uptake when dual inoculums of Azo + AM were applied. Data of 15N isotope showed that the highest portion and value of N2-fixed was recorded with composite inoculums followed by dual inoculations. On the other hand, the infection with AM fungi gave the highest proportion of N derived from fertilizer as compared to other inoculants or uninoculated control. In the same trend, the feculated control. In the same trend, the fertilizer use efficiency (FUE%) was enhanced by AM infection. Dual inoculums of Rh + Azo induced highest content of proline in leaves. (Authors)

  10. Integration ofhup cosmid pHU52 into the chromosomal DNA ofCicer-Rhizobium using Tn5 as an homologous sequence.

    Science.gov (United States)

    Kunnimalaiyaan, M; Lodha, M L; Sreekumar, K R

    1992-11-01

    Cosmid pHU52, which carrieshup genes ofBradyrhizobium japonicum, has been integrated into theCicer-Rhizobium G36-84 genome via Tn5-mediated homologous recombination. Tn5 was inserted into both the cosmid pHU52 and the chromosome ofCicer-Rhizobium to provide a region of DNA homology, without affecting the expression of necessary genes. An incompatible plasmid, pPH1JI, was used to select those few cells that had undergone recombination. The integration of the cosmid was demonstrated by Southern blot analysis. Chromosomal integration of thehup genes maximized stability and minimized the potential for their horizontal transfer to other bacterial species. The integratedhup genes were found to expressex planta as well in nodules. The method described illustrates how a given gene can be stably integrated into the chromosome. PMID:24425601

  11. Promoter analysis of a soybean nuclear gene coding for nodulin-23, a nodule-specific polypeptide involved in symbiosis with Rhizobium

    OpenAIRE

    Wong, S. L.; Verma, D. P. S.

    1985-01-01

    Soybean nodulin-23 gene, induced in nodules formed due to symbiosis with Rhizobium, was found to contain multiple sequences capable of acting as eucaryotic and procaryotic promoters. The transcription start sites of this gene were localized by S1 nuclease mapping, primer extension with nodule mRNA and in vitro run-off transcription analysis. A major transcription start site was observed by S1 mapping; however, the primer extension revealed a second start site. Sequence analysis showed the pre...

  12. Endogenous lectins from cultured soybean cells: isolation of a protein immunologically cross-reactive with seed soybean agglutinin and analysis of its role in binding of Rhizobium japonicum

    OpenAIRE

    1986-01-01

    Incubation of Rhizobium japonicum with the cultured soybean cell line SB-1, originally derived from the roots of Glycine max, resulted in specific adhesion of the bacteria to the plant cells. This binding interaction appears to be mediated via carbohydrate recognition, since galactose can inhibit the heterotypic adhesion but glucose cannot. Affinity chromatography, on a Sepharose column derivatized with N- caproyl-galactosamine, of the supernatant fraction of a SB-1 cell suspension after enzy...

  13. The Nodulation of Alfalfa by the Acid-Tolerant Rhizobium sp. Strain LPU83 Does Not Require Sulfated Forms of Lipochitooligosaccharide Nodulation Signals?

    Science.gov (United States)

    Torres Tejerizo, Gonzalo; Del Papa, María Florencia; Soria-Diaz, M. Eugenia; Draghi, Walter; Lozano, Mauricio; Giusti, María de los Ángeles; Manyani, Hamid; Megías, Manuel; Gil Serrano, Antonio; Pühler, Alfred; Niehaus, Karsten; Lagares, Antonio; Pistorio, Mariano

    2011-01-01

    The induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [NFs]). The nature of the chemical substitution on the NFs depends on the particular rhizobium and contributes to the host specificity imparted by the NFs. We present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the NFs associated with the broad-host-range Rhizobium sp. strain LPU83, a bacterium capable of nodulating at least alfalfa, bean, and Leucena leucocephala. The nod gene cluster was located on the plasmid pLPU83b. The organization of the cluster showed synteny with those of the alfalfa-nodulating rhizobia, Sinorhizobium meliloti and Sinorhizobium medicae. Interestingly, the strongest sequence similarity observed was between the partial nod sequences of Rhizobium mongolense USDA 1844 and the corresponding LPU83 nod genes sequences. The phylogenetic analysis of the intergenic region nodEG positions strain LPU83 and the type strain R. mongolense 1844 in the same branch, which indicates that Rhizobium sp. strain LPU83 might represent an early alfalfa-nodulating genotype. The NF chemical structures obtained for the wild-type strain consist of a trimeric, tetrameric, and pentameric chitin backbone that shares some substitutions with both alfalfa- and bean-nodulating rhizobia. Remarkably, while in strain LPU83 most of the NFs were sulfated in their reducing terminal residue, none of the NFs isolated from the nodH mutant LPU83-H were sulfated. The evidence obtained supports the notion that the sulfate decoration of NFs in LPU83 is not necessary for alfalfa nodulation. PMID:20971905

  14. The Nodulation of Alfalfa by the Acid-Tolerant Rhizobium sp. Strain LPU83 Does Not Require Sulfated Forms of Lipochitooligosaccharide Nodulation Signals?

    OpenAIRE

    Torres Tejerizo, Gonzalo; Del Papa, Mari?a Florencia; Soria-diaz, M. Eugenia; Draghi, Walter; Lozano, Mauricio; Giusti, Mari?a Los A?ngeles; Manyani, Hamid; Megi?as, Manuel; Gil Serrano, Antonio; Pu?hler, Alfred; Niehaus, Karsten; Lagares, Antonio; Pistorio, Mariano

    2010-01-01

    The induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [NFs]). The nature of the chemical substitution on the NFs depends on the particular rhizobium and contributes to the host specificity imparted by the NFs. We present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the NFs associated with the broad-ho...

  15. Modulation of development, growth dynamics, wall crystallinity, and infection sites in white clover root hairs by membrane chitolipooligosaccharides from Rhizobium leguminosarum biovar trifolii.

    OpenAIRE

    Dazzo, F. B.; Orgambide, G. G.; Philip-hollingsworth, S.; Hollingsworth, R. I.; Ninke, K. O.; Salzwedel, J. L.

    1996-01-01

    We used bright-field, time-lapse video, cross-polarized, phase-contrast, and fluorescence microscopies to examine the influence of isolated chitolipooligosaccharides (CLOSs) from wild-type Rhizobium leguminosarum bv. trifolii on development of white clover root hairs, and the role of these bioactive glycolipids in primary host infection. CLOS action caused a threefold increase in the differentiation of root epidermal cells into root hairs. At maturity, root hairs were significantly longer bec...

  16. Sequence Analysis of Hypothetical Lysine Exporter Genes of Rhizobium leguminosarum bv. trifolii from Calamine Old Waste Heaps and Their Evolutionary History

    OpenAIRE

    Olen?ska, Ewa; Ma?ek, Wanda

    2013-01-01

    The aim of this study was to identify heavy metal detoxification system in Rhizobium leguminosarum bv. trifolii isolated from Trifolium repens inhabiting old (70–100 years) Zn–Pb waste heaps in Poland by PCR reaction with czcD1 and czcD2 primers. By sequence analysis, four different genotypes of obtained amplicons were identified among eight examined isolates. Their sequence similarity ranged 91–99 %. They indicated the highest sequence identity to the hypothetical lysine exporter gen...

  17. Mutation in the pssA Gene Involved in Exopolysaccharide Synthesis Leads to Several Physiological and Symbiotic Defects in Rhizobium leguminosarum bv. trifolii

    OpenAIRE

    Monika Janczarek; Kamila Rachwa?

    2013-01-01

    The symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii 24.2 secretes large amounts of acidic exopolysaccharide (EPS), which plays a crucial role in establishment of effective symbiosis with clover. The biosynthesis of this heteropolymer is conducted by a multi-enzymatic complex located in the bacterial inner membrane. PssA protein, responsible for the addition of glucose-1-phosphate to a polyprenyl phosphate carrier, is involved in the first step of EPS synthesis. In th...

  18. Flavonoids induce Rhizobium leguminosarum to produce nodDABC gene-related factors that cause thick, short roots and root hair responses on common vetch.

    OpenAIRE

    Zaat, S. A.; Brussel, A. A.; Tak, T.; Pees, E.; Lugtenberg, B. J.

    1987-01-01

    Rhizobium leguminosarum produced a factor(s) that caused thick, short roots (Tsr phenotype) as well as root hair induction (Hai phenotype) and deformation (Had phenotype) in Vicia sativa plants upon incubation with root exudate or with one of the nod gene inducers naringenin or apigenin; this was a nodDABC gene-dependent process. Detection of the Hai and Had phenotypes was much more sensitive than that of the Tsr phenotype.

  19. Root colonization of different plants by plant-growth-promoting Rhizobium leguminosarum bv. trifolii R39 studied with monospecific polyclonal antisera.

    OpenAIRE

    Schloter, M.; Wiehe, W.; Assmus, B.; Steindl, H.; Becke, H.; Ho?flich, G.; Hartmann, A.

    1997-01-01

    Monospecific polyclonal antisera raised against Rhizobium leguminosarum bv. trifolii R39, a bacterium which was isolated originally from red clover nodules, were used to study the colonization of roots of leguminous and nonleguminous plants (Pisum sativum, Lupinus albus, Triticúm aestivum, and Zea mays) after inoculation. Eight weeks after inoculation of soil-grown plants, between 0.1 and 1% of the total bacterial population in the rhizospheres of all inoculated plants were identified as R. ...

  20. Formation in Rhizobium and Agrobacterium spp. of a 235-kilodalton protein intermediate in beta-D(1-2) glucan synthesis.

    OpenAIRE

    Zorreguieta, A.; Ugalde, R. A.

    1986-01-01

    beta-D(1-2) Glucan was synthesized by Agrobacterium and Rhizobium spp. in vitro with enzymes from the internal membranes upon the addition of UDF glucose and Mg2+ or Mn2+. An intermediate containing protein and beta-D(1-2) glucan was formed during the reaction. It could be precipitated with trichloroacetic acid or separated by polyacrylamide gel electrophoresis under denaturing conditions. After detection with Coomassie blue or a radioactive substrate, the intermediate appeared as a 235-kilod...

  1. Rhizobium paranaense sp. nov., an effective N2-fixing symbiont of common bean (Phaseolus vulgaris L.) with broad geographical distribution in Brazil.

    Science.gov (United States)

    Dall'Agnol, Rebeca Fuzinatto; Ribeiro, Renan Augusto; Delamuta, Jakeline Renata Marçon; Ormeño-Orrillo, Ernesto; Rogel, Marco Antonio; Andrade, Diva Souza; Martínez-Romero, Esperanza; Hungria, Mariangela

    2014-09-01

    Nitrogen (N), the nutrient most required for plant growth, is key for good yield of agriculturally important crops. Common bean (Phaseolus vulgaris L.) can benefit from bacteria collectively called rhizobia, which are capable of fixing atmospheric nitrogen (N2) in root nodules and supplying it to the plant. Common bean is amongst the most promiscuous legume hosts; several described species, in addition to putative novel ones have been reported as able to nodulate this legume, although not always effectively in terms of fixing N2. In this study, we present data indicating that Brazilian strains PRF 35(T), PRF 54, CPAO 1135 and H 52, currently classified as Rhizobium tropici, represent a novel species symbiont of common bean. Morphological, physiological and biochemical properties differentiate these strains from other species of the genus Rhizobium, as do BOX-PCR profiles (less than 60?% similarity), multilocus sequence analysis with recA, gyrB and rpoA (less than 96.4?% sequence similarity), DNA-DNA hybridization (less than 50?% DNA-DNA relatedness), and average nucleotide identity of whole genomes (less than 92.8.%). The novel species is effective in nodulating and fixing N2 with P. vulgaris, Leucaena leucocephala and Leucaena esculenta. We propose the name Rhizobium paranaense sp. nov. for this novel taxon, with strain PRF 35(T) (?=?CNPSo 120(T)?=?LMG 27577(T)?=?IPR-Pv 1249(T)) as the type strain. PMID:24972614

  2. Forestación de un terreno decapitado con Robinia pseudoacacia inoculada con Rhizobium spp. y Glomus deserticola Afforestation of a desurfaced field with Robinia pseudoacacia inoculated with Rhizobium spp. and Glomus deserticola

    Directory of Open Access Journals (Sweden)

    Alejandro E Ferrari

    2010-07-01

    Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L. con una cepa efectiva de Rhizobium y un hongo de micorrizas arbusculares (Glomus deserticola en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%, especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados.Many agricultural lands in Buenos Aires Province (Argentina have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was to assay the effects of inoculation of black locust (Robinia pseudoacacia L. with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O, in Buenos Aires Province (Argentina. The development of inoculated black locust was compared with non-inoculated (control black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.. Survival after two months was very good (>77%, especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches, both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

  3. Forestación de un terreno decapitado con Robinia pseudoacacia inoculada con Rhizobium spp. y Glomus deserticola / Afforestation of a desurfaced field with Robinia pseudoacacia inoculated with Rhizobium spp. and Glomus deserticola

    Scientific Electronic Library Online (English)

    Alejandro E, Ferrari; Carlos A, Esparrach; Mario A, Galetti; Luis G, Wall.

    2010-07-01

    Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L.) con una cepa efectiva de Rhizobium y un hongo [...] de micorrizas arbusculares (Glomus deserticola) en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%), especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones) que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados. Abstract in english Many agricultural lands in Buenos Aires Province (Argentina) have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was [...] to assay the effects of inoculation of black locust (Robinia pseudoacacia L.) with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O), in Buenos Aires Province (Argentina). The development of inoculated black locust was compared with non-inoculated (control) black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.). Survival after two months was very good (>77%), especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches), both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

  4. Establecimiento y respuestas fisiológicas de la simbiosis Rhizobium tropici-Leucaena leucocephala en presencia de fenantreno y naftaleno / Establishment and physiological responses of the Rhizobium tropici-Leucaena leucocephala symbiosis in presence of phenanthrene and naphtalene

    Scientific Electronic Library Online (English)

    Carlos, LÓPEZ-ORTIZ; Ronald, FERRERA-CERRATO; Alejandro, ALARCÓN; Juan José, ALMARAZ; Esperanza, MARTÍNEZ-ROMERO; Ma. Remedios, MENDOZA-LÓPEZ.

    2012-11-01

    Full Text Available Este estudio evaluó el establecimiento de la simbiosis entre Rhizobium tropici CIAT899 y Leucaena leucocephala (Lam.) en sistemas contaminados con naftaleno (NAF) y fenantreno (FEN) y la respuesta de la planta con el contenido de compuestos fenólicos totales (CFT), actividad antioxidante total (AAT) [...] y contenido total de clorofilas (Clo-roT) y carotenos (CaT). A los 31 días, el NAF tuvo efectos negativos en la formación de nódulos, retardando su aparición hasta el día 25 en presencia de 100 mg/L. Ante 20 mg FEN/L, las plantas de L. leucocephala no mostraron diferencias significativas en la formación de nódulos con respecto al testigo, mientras que a 60 y 100 mg FEN/L la nodulación disminuyó significativamente en 52 %. La inoculación con R. tropici incrementó el peso seco total (PST) hasta en 150 % comparado con las plantas no inoculadas. El CFT en hoja fue significativamente mayor en los tratamientos no inoculados en comparación con aquellos inoculados con R. tropici y significativamente mayor ante FEN que con NAF. Para ambos contaminantes, la concentración de 100 mg/L produjo mayor CFT y AAT en comparación con 20 y 60 mg/L. Para el caso de raíz, los tratamientos sin contaminantes en ausencia de R. tropici presentaron mayor CFT y AAT. Para los nódulos, la AAT incrementó significativamente ante NAF, mientras que ante FEN disminuyó. El NAF o el FEN redujeron significativamente el contenido de CloroT, el cual fue significativamente mayor en plantas con Rhizobium en comparación con las plantas no inoculadas. El contenido de CaT en plantas no inoculadas incrementó en presencia de NAF y FEN. Abstract in english This study evaluated the establishment of the symbiosis between Rhizobium tropici CIAT899 and Leucaena leucocephala (Lam.) under contaminated systems with naphtalene (NAF) and phenanthrene (FEN), as well as the physiological plants responses such as total content of phenolic compounds (CFT), total a [...] ntioxidant activity (AAT) and the content of chlorophylls (CloroT) and carotenoids (CaT). After 31 days, NAF had more significant negative effects on nodulation by delaying the formation of nodules until the day 25 at 100 mg/L. In the presence of 20 mg FEN/L, L. leucocephala plants did not show significant differences on the number of nodules when compared to the control, while nodulation decreased 52 % at 60 and 100 mg FEN/L. Inoculation with R. tropici resulted in significant increases of PST (>150 %) in comparison to non-inoculated plants. The foliar content of CFT was significantly greater at non-inoculated treatments in respect to those with R. tropici, and significantly higher in plants exposed to FEN than NAF. For both hydrocarbons, the concentration of 100 mg/L resulted in greater CFT and AAT when compared to 20 or 60 mg/L. For roots, treatments without contamination and R. tropici had more content of CFT and AAT. The AAT in nodules significantly increased due to NAF, while a significant reduction was observed in FEN treatments. Either NAF or FEN did not significantly affect the content of CloroT, although this content was significantly greater in plants with R. tropici than non-inoculated plants. The CaT content significantly increased at non-inoculated plants exposed to NAF and/or FEN.

  5. Synergistic interaction of Rhizobium leguminosarum bv. viciae and arbuscular mycorrhizal fungi as a plant growth promoting biofertilizers for faba bean (Vicia faba L.) in alkaline soil.

    Science.gov (United States)

    Abd-Alla, Mohamed Hemida; El-Enany, Abdel-Wahab Elsadek; Nafady, Nivien Allam; Khalaf, David Mamdouh; Morsy, Fatthy Mohamed

    2014-01-20

    Egyptian soils are generally characterized by slightly alkaline to alkaline pH values (7.5-8.7) which are mainly due to its dry environment. In arid and semi-arid regions, salts are less concentrated and sodium dominates in carbonate and bicarbonate forms, which enhance the formation of alkaline soils. Alkaline soils have fertility problems due to poor physical properties which adversely affect the growth and the yield of crops. Therefore, this study was devoted to investigating the synergistic interaction of Rhizobium and arbuscular mycorrhizal fungi for improving growth of faba bean grown in alkaline soil. A total of 20 rhizobial isolates and 4 species of arbuscular mycorrhizal fungi (AMF) were isolated. The rhizobial isolates were investigated for their ability to grow under alkaline stress. Out of 20 isolates 3 isolates were selected as tolerant isolates. These 3 rhizobial isolates were identified on the bases of the sequences of the gene encoding 16S rRNA and designated as Rhizobium sp. Egypt 16 (HM622137), Rhizobium sp. Egypt 27 (HM622138) and Rhizobium leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The best alkaline tolerant was R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The effect of R. leguminosarum bv. viciae STDF-Egypt 19 and mixture of AMF (Acaulospora laevis, Glomus geosporum, Glomus mosseae and Scutellospora armeniaca) both individually and in combination on nodulation, nitrogen fixation and growth of Vicia faba under alkalinity stress were assessed. A significant increase over control in number and mass of nodules, nitrogenase activity, leghaemoglobin content of nodule, mycorrhizal colonization, dry mass of root and shoot was recorded in dual inoculated plants than plants with individual inoculation. The enhancement of nitrogen fixation of faba bean could be attributed to AMF facilitating the mobilization of certain elements such as P, Fe, K and other minerals that involve in synthesis of nitrogenase and leghaemoglobin. Thus it is clear that the dual inoculation with Rhizobium and AMF biofertilizer is more effective for promoting growth of faba bean grown in alkaline soils than the individual treatment, reflecting the existence of synergistic relationships among the inoculants. PMID:23920230

  6. Produção de mudas de acácia colonizadas com micorrizas e rizóbio em diferentes recipientes Production of acacia plants colonized with mycorrhizas and rhizobium in different recipients

    Directory of Open Access Journals (Sweden)

    Jolimar Antonio Schiavo

    2003-02-01

    Full Text Available Realizou-se um experimento em casa de vegetação, com o objetivo de avaliar diferentes métodos na produção de mudas de Acacia mangium Willd, colonizadas com fungos micorrízicos arbusculares (FMAs e rizóbio. O delineamento experimental foi o inteiramente casualizado num esquema fatorial 4x2 (controle, FMAs, rizóbio e FMAs + rizóbio x blocos prensados e tubetes de plástico, com seis repetições. Os blocos prensados foram confeccionados com substratos orgânicos (bagaço de cana + torta de filtro de usina açucareira e vermiculita, colocados em fôrma metálica de 60x40x20 cm e prensados a 10 kgf cm-2, a fim de proporcionar agregação do material. A inoculação do rizóbio foi realizada com estirpe selecionada para a espécie (Br 3609, Br 6009. A inoculação de FMAs foi feita no momento da confecção dos blocos. Mudas de Acacia mangium que receberam inóculo de FMAs + rizóbio e produzidas em blocos prensados apresentaram maior produção de matéria seca e conteúdo de N na parte aérea. O conteúdo de P na parte aérea é significativamente maior somente nas mudas infectadas com os FMAs, independentemente do tipo de recipiente.A greenhouse experiment was carried out in order to evaluate different methods to produce Acacia mangium Willd plant seedlings, inoculated with arbuscular mycorrhizal fungi (AMF and rhizobium. A completely randomized design in a factorial scheme 4x2 (control, AMF, rhizobium and AMF + rhizobium x pressed blocks and plastic tubes, with six repetitions was used. The pressed blocks used to produce Acacia mangium plants were made with organic residue from sugarcane (sugarcane bagasse + filter cake and vermiculite. The inoculation with rhizobium was done with selected strain (Br 3609, Br 6009. The inoculation with AMF was done at the time when pressed blocks were made. Acacia mangium plants inoculated with both AMF + rhizobium led to a significant increase in dry matter yield and N content of shoot plants, only in pressed blocks. Phosphorus content of shoot plants is significantly higher in seedlings inoculated only with AMF, and it is independent of the plant production system.

  7. Selecting in vitro of Rhizobiumfor tolerance to acidity and aluminium Selección in vitro de Rhizobium tolerante a acidez y aluminio

    Directory of Open Access Journals (Sweden)

    Campos Segura Ricardo

    1995-12-01

    Full Text Available Fifty strains of Rhizobium tropiciisolated of Sabana de Bogotá soils and foreigns collections were screened for tolerance of acidity and aluminium in liquid and sol id culture. Assesment of visible turbidity and colonies growth, respectively, indicated five
    (5 strains tolerant of pH 4.5 and pH 5.0 and 10 or 20 u M Aluminium. Strains that tolerated the 10 west pH values in culture were tolerant of the highest aluminium concentrations
    The cultural test should be used to predict the ability of Rhizobium to growth and for use as inoculants in low pH area.La apertura económica puso de presente la obligación de revisar las formas de producción de los cultivos comerciales, Con el fin de competir adecuadamente en mercados internacionales. Actualmente, leguminosas, como el frijol (Phaseolus vulgarís se presentan, actualmente, como cultivo alternativo para reemplazar cultivos tradicionales en la Sabana de Bogotá. Existe un alto porcentaje de suelos ácidos en Colombia, así como problemas nutricionales, en los cuales la deficiencia de nitrógeno es muy común. El presente trabajo se realizó con el objetivo de seleccionar "in vitro" cepas de Rizobium tropici tolerantes a acidez y aluminio, en medios de cultivo diferentes. Inicialmente se hizo una preselección "in vitro" de cepas tolerantes a tres niveles de pH 4,0; 4,5 y 5,0, utilizando el medio líquido de Wood y Cooper y usando 50 cepas entre nativas y foráneas. En este caso, se seleccionaron las cepas RC 92, RC 117, C 7, C 11, C 14, C 53, Nifta1182, RC 70, RC 85, CIAT 899, CIAT 144 y Niftal 241. Posteriormente, se realizó una selección "in vitro" de cepas tolerantes a dos niveles de pH: 4,5 y 5,0 y a
    cuatro niveles de aluminio: 0,5; 10 y 20 M, utilizando dos fuentes de aluminio: AlCl3 y ALK(S042 y empleando dos medios de cultivo: el líquido de Wood y Cooper y el sólido de Keyser y Munns. Las cepas RC 85, C 11, CIAT 899, CIAT 144 y Niftal 182, fueron seleccionadas como las de mejor
    comportamiento.

  8. Bouvard et Pécuchet et le savoir médical

    Directory of Open Access Journals (Sweden)

    Norioki Sugaya

    2009-01-01

    Full Text Available Le présent article a pour objet le dossier médical que Flaubert a constitué pour la préparation du chapitre III de Bouvard et Pécuchet. Ce dossier considérable, qui contient des notes de lecture prises par le romancier en vue de la rédaction du chapitre médical, nous permet de comprendre à quel point le « comique d’idées » propre au roman encyclopédique est le produit d’un travail intense sur le savoir. L’écriture romanesque de Bouvard explore en effet les configurations épistémologiques de chaque discipline, et met au jour surtout ses apories et ses insuffisances. Nous nous proposons donc d’aborder le dossier médical pour saisir le sens de l’excès documentaire pour l’esthétique flaubertienne. Notre étude se compose de trois parties. D’abord, nous étudierons la composition du dossier en nous demandant quels ouvrages médicaux a lu l’auteur de Bouvard. Ensuite, nous essaierons d’examiner le travail critique de Flaubert pratiqué sur les discours du savoir, en particulier la manière dont il traque et construit des contradictions. Enfin, nous analyserons un épisode du roman, celui de la fièvre typhoïde de Gouy, dont l’étude de la genèse nous montrera l’inscription de l’épistémologique dans la représentation romanesque.This article proposes to study the medical documents gathered by Flaubert for the preparation of Chapter III of Bouvart et Pécuchet. This substantial file, which contains reading notes taken by the novelist for the writing of the medical chapter, allows us to understand to what extent the “comic of ideas”, characteristic of the encyclopedic novel, is the result of an intensive work on knowledge. Indeed, the novelistic writing of Bouvard explores the epistemological configurations of each discipline, and in particular reveals its aporia and its insufficiencies. We have chosen to focus on the medical file in order to understand the meaning of the documentary excess with respect toFlaubert’s esthetics. First we shall study the components of the file, identifying the medical works read by the author of Bouvard. Then we will examine Flaubert’s critical reflection on knowledge, in particular the way he hunts down and constructs contradictions. Finally, we will analyze an episode in the novel, that of Gouy’s typhoid fever. We shall study its genesis which will show the presence of the epistemological in the art of the novel.

  9. Production of (S)-4-chloro-3-hydroxybutyrate by microbial resolution using hydrolase from Rhizobium sp. DS-S-51.

    Science.gov (United States)

    Nakagawa, Atsushi; Suzuki, Takahiro; Kato, Ko; Shinmyo, Atsuhiko; Suzuki, Toshio

    2008-04-01

    (S)-4-Chloro-3-hydroxybutyrate (CHB) is essential for the synthesis of biologically and pharmacologically important compounds. Rhizobium sp. DS-S-51 isolated from soil samples showed hydrolytic activity toward (R)-CHB in the racemate to (R)-3-hydroxy-gamma-butyrolactone (HL) under a simple composition of the reaction. Residual (S)-CHB was obtained with high optical purity. The gene encoding the enzyme concerned, designated CHB hydrolase, was isolated from DS-S-51, and the gene was highly expressed in Escherichia coli JM109. When the resolution of racemic methyl CHB (CHBM) as a substrate was performed using this recombinant cell, JM109 (pKK-R1), the hydrolytic activity was found to be 40-fold greater than that of DS-S-51, and the maximum concentration of the substrate added increased 2-fold. Moreover, (R)-HL was also obtained without decreasing the optical purity compared with that when (R)-CHBM was used as a substrate. PMID:18499045

  10. Population Genomics Analysis of Legume Host Preference for Specific Rhizobial Genotypes in the Rhizobium leguminosarum bv. viciae Symbioses.

    Science.gov (United States)

    Jorrin, Beatriz; Imperial, Juan

    2015-03-01

    Rhizobium leguminosarum bv. viciae establishes root nodule symbioses with several legume genera. Although most isolates are equally effective in establishing symbioses with all host genera, previous evidence suggests that hosts select specific rhizobial genotypes among those present in the soil. We have used population genomics to further investigate this observation. Pisum sativum, Lens culinaris, Vicia sativa, and V. faba plants were used to trap rhizobia from a well-characterized soil, and pooled genomic DNA from 100 isolates from each plant were sequenced. Sequence reads were aligned to the R. leguminosarum bv. viciae 3841 reference genome. High overall conservation of sequences was observed in all subpopulations, although several multigenic regions were absent from the soil population. A large fraction (16 to 22%) of sequence reads could not be recruited to the reference genome, suggesting that they represent sequences specific to that particular soil population. Although highly conserved, the 16S to 23S ribosomal RNA gene region presented single nucleotide polymorphisms (SNP) regarding the reference genome, but no striking differences could be found among plant-selected subpopulations. Plant-specific SNP patterns were, however, clearly observed within the nod gene cluster, supporting the existence of a plant preference for specific rhizobial genotypes. This was also shown after genome-wide analysis of SNP patterns. PMID:25514682

  11. Predominant nifH transcript phylotypes related to Rhizobium rosettiformans in field-grown sugarcane plants and in Norway spruce.

    Science.gov (United States)

    Burbano, Claudia Sofía; Liu, Yuan; Rösner, Kim Leonie; Reis, Veronica Massena; Caballero-Mellado, Jesus; Reinhold-Hurek, Barbara; Hurek, Thomas

    2011-06-01

    Although some sugarcane cultivars may benefit substantially from biological nitrogen fixation (BNF), the responsible bacteria have been not identified yet. Here, we examined the active diazotrophic bacterial community in sugarcane roots from Africa and America by reverse transcription (RT)-PCR using broad-range nifH-specific primers. Denaturing gradient gel electrophoresis (DGGE) profiles obtained from sugarcane showed a low diversity at all sample locations with one phylotype amounting up to 100% of the nifH transcripts. This major phylotype has 93.9-99.6% DNA identity to the partial nifH sequence from a strain affiliated with Rhizobium rosettiformans. In addition, nifH transcripts of this phylotype were also detected in spruce roots sampled in Germany, where they made up 91% of nifH transcripts detected. In contrast, in control soil or shoot samples two distinct nifH transcript sequences distantly related to nifH from Sulfurospirillum multivorans or Bradyrhizobium elkanii, respectively, were predominant. These results suggest that R. rosettiformans is involved in root-associated nitrogen fixation with sugarcane and spruce, plants that do not form root-nodule symbioses. PMID:23761284

  12. Biofiltration of residual fertilizer nitrate and atrazine by Rhizobium meliloti in saturated and unsaturated sterile soil columns.

    Science.gov (United States)

    Mehmannavaz, R; Prasher, S O; Markarian, N; Ahmad, D

    2001-04-15

    This study was undertaken to investigate whether microbial bioaugmentation of subsurface soil with subsurface irrigation could be used as a biofiltration/biocontrol technology for agricultural pollutants. Nine Plexiglas columns, 458 mm long x 139 mm in diameter, were packed with a sterilized sandy loam soil. Subsurface irrigation, through a controlled water table management system, was used to deliver bacteria, Rhizobium meliloti A-025, to the soil and to maintain aerobic (unsaturated) or anaerobic (saturated) conditions in the columns. Nitrate and atrazine, a fertilizer and a corn herbicide, were applied to the soil surface, and leaching was affected by simulated rainfall events. The soil and drainage waters were analyzed for nitrate and atrazine residues after each rainfall simulation throughout the experimental period during which the soil was kept saturated for a total of 80 days and unsaturated for a total of 70 days. The monitoring of transport and survival of the implanted bacterial strain (A-025) showed that subsurface irrigation was successful in introducing and transporting the bacteria throughout the soil columns. During the saturated period, significantly more (95% probability) nitrate-N leached into the drainage waters from the control columns than from the bioaugmented columns; the increase being 450% or more for the abiotic control columns. The amount of atrazine that leached into the drainage waters during the unsaturated period was also significantly more from control columns as opposed to bioaugmented columns, with the increase being 262%. PMID:11329710

  13. Extended region of nodulation genes in Rhizobium meliloti 1021. II. Nucleotide sequence, transcription start sites and protein products

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.F.; Swanson, J.A.; Mulligan, J.T.; Long, S.R.

    1987-10-01

    The authors have established the DNA sequence and analyzed the transcription and translation products of a series of putative nodulation (nod) genes in Rhizobium meliloti strain 1021. Four loci have been designated nodF, nodE, nodG and nodH. The correlation of transposon insertion positions with phenotypes and open reading frames was confirmed by sequencing the insertion junctions of the transposons. The protein products of these nod genes were visualized by in vitro expression of cloned DNA segments in a R. meliloti transcription-translation system. In addition, the sequence for nodG was substantiated by creating translational fusions in all three reading frames at several points in the sequence; the resulting fusions were expressed in vitro in both E. coli and R. meliloti transcription-translation systems. A DNA segment bearing several open reading frames downstream of nodG corresponds to the putative nod gene mutated in strain nod-216. The transcription start sites of nodF and nodH were mapped by primer extension of RNA from cells induced with the plant flavone, luteolin. Initiation of transcription occurs approximately 25 bp downstream from the conserved sequence designated the nod box, suggesting that this conserved sequence acts as an upstream regulator of inducible nod gene expression. Its distance from the transcription start site is more suggestive of an activator binding site rather than an RNA polymerase binding site.

  14. Extended region of nodulation genes in Rhizobium meliloti 1021. II. Nucleotide sequence, transcription start sites and protein products

    International Nuclear Information System (INIS)

    The authors have established the DNA sequence and analyzed the transcription and translation products of a series of putative nodulation (nod) genes in Rhizobium meliloti strain 1021. Four loci have been designated nodF, nodE, nodG and nodH. The correlation of transposon insertion positions with phenotypes and open reading frames was confirmed by sequencing the insertion junctions of the transposons. The protein products of these nod genes were visualized by in vitro expression of cloned DNA segments in a R. meliloti transcription-translation system. In addition, the sequence for nodG was substantiated by creating translational fusions in all three reading frames at several points in the sequence; the resulting fusions were expressed in vitro in both E. coli and R. meliloti transcription-translation systems. A DNA segment bearing several open reading frames downstream of nodG corresponds to the putative nod gene mutated in strain nod-216. The transcription start sites of nodF and nodH were mapped by primer extension of RNA from cells induced with the plant flavone, luteolin. Initiation of transcription occurs approximately 25 bp downstream from the conserved sequence designated the nod box, suggesting that this conserved sequence acts as an upstream regulator of inducible nod gene expression. Its distance from the transcription start site is more suggestive of an activator binding site rather than an RNA polymerase binding sitee

  15. Biological control of crown gall on grapevine and root colonization by nonpathogenic Rhizobium vitis strain ARK-1.

    Science.gov (United States)

    Kawaguchi, Akira

    2013-01-01

    A nonpathogenic strain of Rhizobium vitis ARK-1 was tested as a biological control agent for grapevine crown gall. When grapevine roots were soaked in a cell suspension of strain ARK-1 before planting in the field, the number of plants with tumors was reduced. The results from seven field trials from 2009 to 2012 were combined in a meta-analysis. The integrated relative risk after treatment with ARK-1 was 0.15 (95% confidence interval: 0.07-0.29, P0.001), indicating that the disease incidence was significantly reduced by ARK-1. In addition, the results from four field trials from 2007 to 2009 using R. vitis VAR03-1, a previously reported biological control agent for grapevine crown gall, were combined in a meta-analysis. The integrated relative risk after treatment with VAR03-1 was 0.24 (95% confidence interval: 0.11-0.53, P0.001), indicating the superiority of ARK-1 in inhibiting grapevine crown gall over VAR03-1 under field conditions. ARK-1 did not cause necrosis on grapevine shoot explants. ARK-1 established populations on roots of grapevine tree rootstock and persisted inside roots for two years. PMID:23708779

  16. Biologic fixation of nitrogen in irradiated rhizobium strips; Fixacao biologica do nitrogenio em estirpes de rizobianas irradiadas

    Energy Technology Data Exchange (ETDEWEB)

    Caribe, Rebeka Alves; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

    2002-07-01

    Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-{gamma}). The D{sub 37} values for the rhizobial strain SEMIA 4077 were 43 J.m{sup -2} (UV) and 32 Gy (R-{gamma}) and for the SEMIA 6145 were 45 J.m{sup -2} (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

  17. Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.X.; Kosier, B.; Priefer, U.B. [Rheinisch-Westfaelische TH Aachen, Aachen (Germany)

    2001-09-01

    A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv, viciae genotypes in the absence of its host plant.

  18. Characterisation of SalRAB a salicylic acid inducible positively regulated efflux system of Rhizobium leguminosarum bv viciae 3841.

    Science.gov (United States)

    Tett, Adrian J; Karunakaran, Ramakrishnan; Poole, Philip S

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants. PMID:25133394

  19. A previously uncharacterized tetratricopeptide-repeat-containing protein is involved in cell envelope function in Rhizobium leguminosarum.

    Science.gov (United States)

    Neudorf, Kara D; Vanderlinde, Elizabeth M; Tambalo, Dinah D; Yost, Christopher K

    2015-01-01

    Rhizobium leguminosarum is a soil bacterium that is an intracellular symbiont of leguminous plants through the formation of nitrogen-fixing root nodules. Due to the changing environments that rhizobia encounter, the cell is often faced with a variety of cell altering stressors that can compromise the cell envelope integrity. A previously uncharacterized operon (RL3499-RL3502) has been linked to proper cell envelope function, and mutants display pleiotropic phenotypes including an inability to grow on peptide-rich media. In order to identify functional partners to the operon, suppressor mutants capable of growth on complex, peptide-rich media were isolated. A suppressor mutant of a non-polar mutation to RL3500 was chosen for further characterization. Transposon mutagenesis, screening for loss of the suppressor phenotype, led to the identification of a Tn5 insertion in an uncharacterized tetratricopeptide-repeat-containing protein RL0936. Furthermore, RL0936 had a 3.5-fold increase in gene expression in the suppressor strain when compared with the WT and a 1.5-fold increase in the original RL3500 mutant. Mutation of RL0936 decreased desiccation tolerance and lowered the ability to form biofilms when compared with the WT strain. This work has identified a potential interaction between RL0936 and the RL3499-RL3502 operon that is involved in cell envelope development in R. leguminosarum, and has described phenotypic activities to a previously uncharacterized conserved hypothetical gene. PMID:25370751

  20. Genome sequence of Rhizobium leguminosarum bv trifolii strain WSM1689, the microsymbiont of the one flowered clover Trifolium uniflorum.

    Science.gov (United States)

    Terpolilli, Jason; Rui, Tian; Yates, Ron; Howieson, John; Poole, Philip; Munk, Christine; Tapia, Roxanne; Han, Cliff; Markowitz, Victor; Tatiparthi, Reddy; Mavrommatis, Konstantinos; Ivanova, Natalia; Pati, Amrita; Goodwin, Lynne; Woyke, Tanja; Kyrpides, Nikos; Reeve, Wayne

    2014-06-15

    Rhizobium leguminosarum bv. trifolii is a soil-inhabiting bacterium that has the capacity to be an effective N2-fixing microsymbiont of Trifolium (clover) species. R. leguminosarum bv. trifolii strain WSM1689 is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from a root nodule of Trifolium uniflorum collected on the edge of a valley 6 km from Eggares on the Greek Island of Naxos. Although WSM1689 is capable of highly effective N2-fixation with T. uniflorum, it is either unable to nodulate or unable to fix N2 with a wide range of both perennial and annual clovers originating from Europe, North America and Africa. WSM1689 therefore possesses a very narrow host range for effective N2 fixation and can thus play a valuable role in determining the geographic and phenological barriers to symbiotic performance in the genus Trifolium. Here we describe the features of R. leguminosarum bv. trifolii strain WSM1689, together with the complete genome sequence and its annotation. The 6,903,379 bp genome contains 6,709 protein-coding genes and 89 RNA-only encoding genes. This multipartite genome contains six distinct replicons; a chromosome of size 4,854,518 bp and five plasmids of size 667,306, 518,052, 341,391, 262,704 and 259,408 bp. This rhizobial genome is one of 20 sequenced as part of a DOE Joint Genome Institute 2010 Community Sequencing Program. PMID:25197438

  1. Cloning and characterization of a galactitol 2-dehydrogenase from Rhizobium legumenosarum and its application in D-tagatose production.

    Science.gov (United States)

    Jagtap, Sujit Sadashiv; Singh, Ranjitha; Kang, Yun Chan; Zhao, Huimin; Lee, Jung-Kul

    2014-05-10

    Galactitol 2-dehydrogenase (GDH) belongs to the protein subfamily of short-chain dehydrogenases/reductases and can be used to produce optically pure building blocks and for the bioconversion of bioactive compounds. An NAD(+)-dependent GDH from Rhizobium leguminosarum bv. viciae 3841 (RlGDH) was cloned and overexpressed in Escherichia coli. The RlGDH protein was purified as an active soluble form using His-tag affinity chromatography. The molecular mass of the purified enzyme was estimated to be 28kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 114kDa by gel filtration chromatography, suggesting that the enzyme is a homotetramer. The enzyme has an optimal pH and temperature of 9.5 and 35°C, respectively. The purified recombinant RlGDH catalyzed the oxidation of a wide range of substrates, including polyvalent aliphatic alcohols and polyols, to the corresponding ketones and ketoses. Among various polyols, galactitol was the preferred substrate of RlGDH with a Km of 8.8mM, kcat of 835min(-1) and a kcat/Km of 94.9min(-1)mM(-1). Although GDHs have been characterized from a few other sources, RlGDH is distinguished from other GDHs by its higher specific activity for galactitol and broad substrate spectrum, making RlGDH a good choice for practical applications. PMID:24731824

  2. Genetic characterization of a novel rhizobial plasmid conjugation system in Rhizobium leguminosarum bv. viciae strain VF39SM.

    Science.gov (United States)

    Ding, Hao; Yip, Cynthia B; Hynes, Michael F

    2013-01-01

    Rhizobium leguminosarum strain VF39SM contains two plasmids that have previously been shown to be self-transmissible by conjugation. One of these plasmids, pRleVF39b, is shown in this study to carry a set of plasmid transfer genes that differs significantly from conjugation systems previously studied in the rhizobia but is similar to an uncharacterized set of genes found in R. leguminosarum bv. trifolii strain WSM2304. The entire sequence of the transfer region on pRleVF39b was determined as part of a genome sequencing project, and the roles of the various genes were examined by mutagenesis. The transfer region contains a complete set of mating pair formation (Mpf) genes, a traG gene, and a relaxase gene, traA, all of which appear to be necessary for plasmid transfer. Experimental evidence suggested the presence of two putative origins of transfer within the gene cluster. A regulatory gene, trbR, was identified in the region between traA and traG and was mutated. TrbR was shown to function as a repressor of both trb gene expression and plasmid transfer. PMID:23144250

  3. Isolation and structural identification of the trihydroxamate siderophore vicibactin and its degradative products from Rhizobium leguminosarum ATCC 14479 bv. trifolii.

    Science.gov (United States)

    Wright, William; Little, James; Liu, Fang; Chakraborty, Ranjan

    2013-04-01

    The Rhizobia are a group of free-living soil bacteria known for their ability to symbiotically infect the roots of specific host plants as well as to produce siderophores in order to compete with other microorganisms for the limited availability of iron in the rhizosphere. In this study, Rhizobium leguminosarum ATCC 14479, which preferentially infects the red clover Trifolium pratense, was found to produce the trihydroxamate siderophore vicibactin (C33H55N6O15) under iron restricted conditions. In addition, two other iron-binding, siderophore-like compounds: C20H36N4O10, C31H55N6O15, were isolated and purified from the culture media. Due to the structural similarity of the latter compounds to vicibactin based on electrospray-mass spectrometry and nuclear magnetic resonance data, these heretofore unreported molecules are thought to be either modified or degraded products of vicibactin. Although vicibactin has previously been found to be commonly produced by other rhizobial strains, this is the first time it has been chemically characterized from a clover infecting strain of R. leguminosarum. PMID:23361163

  4. Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor.

    Science.gov (United States)

    Bonomi, Hernán R; Posadas, Diana M; Paris, Gastón; Carrica, Mariela del Carmen; Frederickson, Marcus; Pietrasanta, Lía Isabel; Bogomolni, Roberto A; Zorreguieta, Angeles; Goldbaum, Fernando A

    2012-07-24

    Rhizobium leguminosarum is a soil bacterium that infects root hairs and induces the formation of nitrogen-fixing nodules on leguminous plants. Light, oxygen, and voltage (LOV)-domain proteins are blue-light receptors found in higher plants and many algae, fungi, and bacteria. The genome of R. leguminosarum bv. viciae 3841, a pea-nodulating endosymbiont, encodes a sensor histidine kinase containing a LOV domain at the N-terminal end (R-LOV-HK). R-LOV-HK has a typical LOV domain absorption spectrum with broad bands in the blue and UV-A regions and shows a truncated photocycle. Here we show that the R-LOV-HK protein regulates attachment to an abiotic surface and production of flagellar proteins and exopolysaccharide in response to light. Also, illumination of bacterial cultures before inoculation of pea roots increases the number of nodules per plant and the number of intranodular bacteroids. The effects of light on nodulation are dependent on a functional lov gene. The results presented in this work suggest that light, sensed by R-LOV-HK, is an important environmental factor that controls adaptive responses and the symbiotic efficiency of R. leguminosarum. PMID:22773814

  5. Complete genome sequence of Rhizobium leguminosarum bv. trifolii strain WSM1325, an effective microsymbiont of annual Mediterranean clovers.

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, Wayne [Murdoch University, Perth, Australia; O' Hara, Graham [Murdoch University, Perth, Australia; Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Ardley, Julie [Murdoch University, Perth, Australia; Brau, Lambert [Murdoch University, Perth, Australia; Nandesena, Kemanthi [Murdoch University, Perth, Australia; Tiwari, Ravi [Murdoch University, Perth, Australia; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Han, Cliff [Los Alamos National Laboratory (LANL); Brettin, Thomas S [ORNL; Land, Miriam L [ORNL; Ovchinnikova, Galina [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Melino, Vanessa [Murdoch University, Perth, Australia; Denton, Matthew [Department of Primary Industries, Victoria, Australia; Yates, Ron [Murdoch University, Perth, Australia; Howieson, John [Murdoch University, Perth, Australia

    2010-01-01

    Rhizobium leguminosarum bv trifolii is a soil-inhabiting bacterium that that has the capacity to be an effective nitrogen fixing microsymbiont of a diverse range of annual Trifolium (clover) species. Strain WSM1325 is an aerobic, motile, non-spore forming, Gram-negative rod isolated from root nodules collected in 1993 from the Greek Island of Serifos. WSM1325 is manufactured commercially in Australia as an inoculant for a broad range of annual clovers of Mediterranean origin due to its superior attributes of saprophytic competence, nitrogen fixation and acid-tolerance. Here we describe the basic features of this organism, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a microsymbiont of annual clovers. We reveal that its genome size is 7,418,122 bp encoding 7,232 protein-coding genes and 61 RNA-only encoding genes. This multipartite genome contains 6 distinct replicons; a chromosome of size 4,767,043 bp and 5 plasmids of size 828,924, 660,973, 516,088, 350,312 and 294,782 bp.

  6. Multilocus sequence-based analysis delineates a clonal population of Agrobacterium (Rhizobium) radiobacter (Agrobacterium tumefaciens) of human origin.

    Science.gov (United States)

    Aujoulat, Fabien; Jumas-Bilak, Estelle; Masnou, Agnès; Sallé, Fanny; Faure, Denis; Segonds, Christine; Marchandin, Hélène; Teyssier, Corinne

    2011-05-01

    The genus Agrobacterium includes plant-associated bacteria and opportunistic human pathogens. Taxonomy and nomenclature within the genus remain controversial. In particular, isolates of human origin were all affiliated with the species Agrobacterium (Rhizobium) radiobacter, while phytopathogenic strains were designated under the synonym denomination Agrobacterium tumefaciens. In order to study the relative distribution of Agrobacterium strains according to their origins, we performed a multilocus sequence-based analysis (MLSA) on a large collection of 89 clinical and environmental strains from various origins. We proposed an MLSA scheme based on the partial sequence of 7 housekeeping genes (atpD, zwf, trpE, groEL, dnaK, glnA, and rpoB) present on the circular chromosome of A. tumefaciens C58. Multilocus phylogeny revealed that 88% of the clinical strains belong to genovar A7, which formed a homogeneous population with linkage disequilibrium, suggesting a low rate of recombination. Comparison of genomic fingerprints obtained by pulsed-field gel electrophoresis (PFGE) showed that the strains of genovar A7 were epidemiologically unrelated. We present genetic evidence that genovar A7 may constitute a human-associated population distinct from the environmental population. Also, phenotypic characteristics, such as culture at 42°C, agree with this statement. This human-associated population might represent a potential novel species in the genus Agrobacterium. PMID:21398532

  7. Genetic diversity of indigenous Rhizobium leguminosarum bv. viciae isolates nodulating two different host plants during soil restoration with alfalfa.

    Science.gov (United States)

    Zhang, X X; Kosier, B; Priefer, U B

    2001-09-01

    A total of 360 Rhizobium leguminosarum bv. viciae strains was isolated from three brown-coal mining restoration fields of different age and plant cover (without and in the first and second year of alfalfa, Medicago sativa, cultivation) using two host species (Vicia hirsuta and Pisum sativum) as capture plants. The strains were genetically typed by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-generated 16S-23S ribosomal DNA intergenic spacer regions (IGS-RFLP) and characterized by plasmid profiles and RFLP analysis of amplified nodABC genes. The R. leguminosarum bv. viciae population was dominated by the same group of strains (irrespective of the trap plant used). According to type richness, the genetic diversity of indigenous R. leguminosarum in the second year of restoration was lower than in the first year and it resembled that of the fallow field, except for plasmid types, in which it was higher than that of the fallow field. Some of the less frequent nodABC genotypes were associated with distinct chromosomal IGS genotypes and symbiotic plasmids (pSyms) of different sizes, indicating that horizontal transfer and rearrangements of pSym can occur in natural environments. However, the dominant pSym and chromosomal genotypes were strictly correlated suggesting a genetically stable persistence of the prevailing R. leguminosarum bv. viciae genotypes in the absence of its host plant. PMID:11555271

  8. Identification and assessment of symbiotic effectiveness of phage-typed Rhizobium leguminosarum strains on lentil (Lens culinaris Medik) cultivars.

    Science.gov (United States)

    Jaiswal, Sanjay Kumar; Dhar, Banshi

    2011-05-01

    Symbiotic effectiveness of 19 indigenous and two exotic (USDA 2426 and USDA 2431) strains of lentil Rhizobium belonging to different phage-sensitive and phage-resistant groups was compared under axenic condition. Four strains (USDA 2431, BHULR 104, BHULR 113, and BHULR 115) sensitive to different phages were found significantly superior over others in terms of nodule number, acetylene reduction activity, and total dry weight per plant. Inoculation response of these strains was then evaluated on six lentil cultivars under field condition. A significant symbiotic interaction between rhizobial strains and lentil cultivars was observed. Grain yield enhancement was noticed by the compatible interaction of lentil cultivars HUL-57, L-4147, K-75, and PL-4/DPL-15/DPL-62 with rhizobial strains USDA 2431, BHULR 104, BHULR 113, and BHULR 115, respectively. The authentication of rhizobial strains was accomplished through 16S rDNA sequence analysis. All rhizobial strains had close matching with R. leguminosarum bv. viciae strains. The results have shown that phages can trustfully help selecting out the symbiotically efficient most rhizobial strains for advantageous use with lentil cultivars, in order to strengthen the BNF-based future lentil breeding programs. PMID:21327559

  9. Enhanced Synthesis of Antioxidant Enzymes, Defense Proteins and Leghemoglobin in Rhizobium-Free Cowpea Roots after Challenging with Meloydogine incognita

    Directory of Open Access Journals (Sweden)

    Jose T. A. Oliveira

    2014-11-01

    Full Text Available The root knot nematodes (RKN, Meloydogine spp., particularly Meloidogyne incognita and Meloidogyne javanica species, parasitize several plant species and are responsible for large annual yield losses all over the world. Only a few available chemical nematicides are still authorized for RKN control owing to environmental and health reasons. Thus, plant resistance is currently considered the method of choice for controlling RKN, and research performed on the molecular interactions between plants and nematodes to identify genes of interest is of paramount importance. The present work aimed to identify the differential accumulation of root proteins of a resistant cowpea genotype (CE-31 inoculated with M. incognita (Race 3 in comparison with mock-inoculated control, using 2D electrophoresis assay, mass spectrometry identification and gene expression analyses by RT-PCR. The results showed that at least 22 proteins were differentially represented in response to RKN challenge of cowpea roots mainly within 4–6 days after inoculation. Amongst the up-represented proteins were SOD, APX, PR-1, ?-1,3-glucanase, chitinases, cysteine protease, secondary metabolism enzymes, key enzymes involved in ethylene biosynthesis, proteins involved in MAPK pathway signaling and, surprisingly, leghemoglobin in non-rhizobium-bacterized cowpea. These findings show that an important rearrangement in the resistant cowpea root proteome occurred following challenge with M. incognita.

  10. Integrated use of Rhizobium leguminosarum, Plant Growth Promoting Rhizobacteria and Enriched Compost for Improving Growth, Nodulation and Yield of Lentil (Lens culinaris Medik.) Uso Integrado de Rhizobium leguminosarum, Rizobacterias Promotoras de Crecimiento Vegetal y Compost Enriquecido para Mejorar el Crecimiento, Nodulación y Rendimiento de Lenteja (Lens culinaris Medik.)

    OpenAIRE

    Muhammad Asif Iqbal; Muhammad Khalid; Sher Muhammad Shahzad; Maqshoof Ahmad; Nawaf Soleman; Naeem Akhtar

    2012-01-01

    Maintenance of high bacterial population in the rhizosphere improves the efficiency of these organisms. This high bacterial population can be maintained by the application of enriched compost which supports their growth and activities. Thus integrated use of Rhizobium, plant growth promoting rhizobacteria (PGPR) containing 1-aminocyclopropane-1-carboxylate deaminase (ACC-deaminase) and P-enriched compost (PEC) could be highly effective for promoting growth, nodulation, and yield of lentil (Le...

  11. Efficacy of Rhizobium and Pseudomonas strains to improve physiology, ionic balance and quality of mung bean under salt-affected conditions on farmer's fields.

    Science.gov (United States)

    Ahmad, Maqshoof; Zahir, Zahir A; Khalid, Muhammad; Nazli, Farheen; Arshad, Muhammad

    2013-02-01

    High ethylene concentration under different environmental stresses such as salinity is one of the contributing factors for premature senescence of different plant parts. Plants under salinity stress produce increased levels of ethylene which inhibit the plant growth and physiology thus deteriorating the quality of the produce. Some plant growth promoting rhizobacteria (PGPR) have the ability to improve quality of crops through reduction in detrimental effects of salinity on plant growth and physiology by lowering endogenous level of ethylene along with other mechanisms. Two field trials were conducted to evaluate the Rhizobium and Pseudomonas containing ACC-deaminase for their efficacy to reduce the effect of salinity on physiology, ionic and nutrient balance of mung bean. Results showed that salinity stress adversely affected the physiological parameters of mung bean. It decreased the CO(2) assimilation, stomatal conductance of water, relative water content, photosynthetic rate, transpiration rate and chlorophyll contents in mung bean but inoculation of either Rhizobium or Pseudomonas alone reduced adverse effect of salinity significantly. However, co-inoculation with Rhizobium and Pseudomonas was the most effective treatment and it diluted the adverse effects of salinity on relative water contents and CO(2) assimilation rate thus improving the photosynthetic rate, water use efficiency and chlorophyll content over the un-inoculated control. Co-inoculation improved the ionic balance and also increased the phosphorus and protein concentration in grain of mung bean. The results suggested that these strains could be effectively used to improve the growth, physiology and quality of mung bean under salt-affected conditions. PMID:23262185

  12. Induction of nitrogen-fixing nodules on clover requires only 32 kilobase pairs of DNA from the Rhizobium trifolii symbiosis plasmid.

    OpenAIRE

    Innes, R. W.; Hirose, M. A.; Kuempel, P. L.

    1988-01-01

    Overlapping subclones from the Rhizobium trifolii symbiosis plasmid pRt843a were generated by using in vivo and in vitro methods. Subclones were assayed for symbiotic phenotype by introducing them into a derivative of R. trifolii ANU843 cured of its symbiosis plasmid and testing the transconjugant strains for the ability to induce nitrogen-fixing nodules on clover. One subclone spanning 32 kilobase pairs (kb) of DNA from pRt843a was found to restore nitrogen fixation ability. This subclone in...

  13. The Pea Nodule Environment Restores the Ability of a Rhizobium leguminosarum Lipopolysaccharide acpXL Mutant To Add 27-Hydroxyoctacosanoic Acid to Its Lipid A

    OpenAIRE

    Vedam, Vinata; Kannenberg, Elmar; Datta, Anup; Brown, Dusty; Haynes-gann, Janine G.; Sherrier, D. Janine; Carlson, Russell W.

    2006-01-01

    Members of the Rhizobiaceae contain 27-hydroxyoctacosanoic acid (27OHC28:0) in their lipid A. A Rhizobium leguminosarum 3841 acpXL mutant (named here Rlv22) lacking a functional specialized acyl carrier lacked 27OHC28:0 in its lipid A, had altered growth and physiological properties (e.g., it was unable to grow in the presence of an elevated salt concentration [0.5% NaCl]), and formed irregularly shaped bacteroids, and the synchronous division of this mutant and the host plant-derived symbios...

  14. Reduction in Pathogen Populations at Grapevine Wound Sites is Associated with the Mechanism Underlying the Biological Control of Crown Gall by Rhizobium vitis Strain ARK-1

    OpenAIRE

    Kawaguchi, Akira

    2014-01-01

    A nonpathogenic strain of Rhizobium (=Agrobacterium) vitis, ARK-1, limited the development of grapevine crown gall. A co-inoculation with ARK-1 and the tumorigenic strain VAT07-1 at a 1:1 cell ratio resulted in a higher population of ARK-1 than VAT07-1 in shoots without tumors, but a significantly lower population of ARK-1 than VAT07-1 in grapevine shoots with tumors. ARK-1 began to significantly suppress the VAT07-1 population 2 d after the inoculation. This result indicated that ARK-1 reduc...

  15. [Influence of calcium and rhizobial infections (Rhizobium leguminosarum) on the dynamics of nitric oxide (NO) content in roots of etiolated pea (Pisum sativum L.) seedlings].

    Science.gov (United States)

    2014-01-01

    The effect of exogenous calcium (Ca2+) and rhizobial infections (Rhizobium leguminosarum bv viceae) on the dynamics of the level of nitric oxide (NO) was studied in cross cuts of roots of two-day-old etiolated pea seedlings (Pisum sativum L.) using a DAF-2DA fluorescent probe. Fluctuations of the NO level, indicating the presence of a rhythm in the generation of NO in roots, were observed during the incubation of seedlings in water, a CaCl2 solution, and with rhizobial infections. Exogenous factors (Ca2+ and two rhizobial stamms) change the time dynamics of the NO level in comparison with the control (water). PMID:25726667

  16. Conservation of PcaQ, a transcriptional activator of pca genes for catabolism of phenolic compounds, in Agrobacterium tumefaciens and Rhizobium species.

    OpenAIRE

    Parke, D.

    1996-01-01

    In Agrobacterium tumefaciens A348, control of five genes for catabolism of the phenolic compound protocatechuate to beta-ketoadipate is exerted by the gene pcaQ. The product of pcaQ is a transcriptional activator which is distinct from regulators of the beta-ketoadipate pathway characterized in other bacterial groups. An investigation of whether pcaQ is present and conserved in related Rhizobium species employed Southern hybridization and an agrobacterial pcaD::LacZ promoter probe plasmid. Th...

  17. Proteins Exported via the PrsD-PrsE Type I Secretion System and the Acidic Exopolysaccharide Are Involved in Biofilm Formation by Rhizobium leguminosarum

    OpenAIRE

    Russo, Daniela M.; Williams, Alan; Edwards, Anne; Posadas, Diana M.; Finnie, Christine; Dankert, Marcelo; Downie, J. Allan; Zorreguieta, Angeles

    2006-01-01

    The type I protein secretion system of Rhizobium leguminosarum bv. viciae encoded by the prsD and prsE genes is responsible for secretion of the exopolysaccharide (EPS)-glycanases PlyA and PlyB. The formation of a ring of biofilm on the surface of the glass in shaken cultures by both the prsD and prsE secretion mutants was greatly affected. Confocal laser scanning microscopy analysis of green-fluorescent-protein-labeled bacteria showed that during growth in minimal medium, R. leguminosarum wi...

  18. A Rhizobium meliloti mutant that forms ineffective pseudonodules in alfalfa produces exopolysaccharide but fails to form beta-(1----2) glucan.

    OpenAIRE

    Geremia, R. A.; Cavaignac, S.; Zorreguieta, A.; Toro, N.; Olivares, J.; Ugalde, R. A.

    1987-01-01

    A mutant of Rhizobium meliloti that elicited the formation of inactive nodules in alfalfa was found not to form beta-(1----2) glucan in vivo or in vitro. It was nonmotile because it lacks flagella. The 235-kilodalton protein which acts as an intermediate in beta-(1----2) glucan synthesis was undetectable in the mutant. These properties of the mutant are common to those of chvB mutants of Agrobacterium tumefaciens. Exopolysaccharide formation by the R. meliloti mutant was about double that by ...

  19. Development of a Real-Time PCR Assay for Detection and Quantification of Rhizobium leguminosarum Bacteria and Discrimination between Different Biovars in Zinc-Contaminated Soil?

    OpenAIRE

    Macdonald, Catriona A.; Clark, Ian M.; Hirsch, Penny R.; Zhao, Fang-jie; Mcgrath, Steve P.

    2011-01-01

    Primers were designed to target 16S rRNA and nodD genes of Rhizobium leguminosarum from DNA extracted from two different soil types contaminated with Zn applied in sewage sludge. Numbers of rhizobia estimated using 16S rRNA gene copy number showed higher abundance than those estimated by both nodD and the most-probable-number (MPN) enumeration method using a plant trap host. Both 16S rRNA gene copies and the MPN rhizobia declined with increased levels of Zn contamination, as did the abundance...

  20. Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale; Etude des vibrations et de la stabilisation a l'echelle sous-nanometrique des doublets finaux d'un collisionneur lineaire

    Energy Technology Data Exchange (ETDEWEB)

    Bolzon, B

    2007-11-15

    CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

  1. Dual role of HupF in the biosynthesis of [NiFe] hydrogenase in Rhizobium leguminosarum

    Directory of Open Access Journals (Sweden)

    Albareda Marta

    2012-11-01

    Full Text Available Abstract Background [NiFe] hydrogenases are enzymes that catalyze the oxidation of hydrogen into protons and electrons, to use H2 as energy source, or the production of hydrogen through proton reduction, as an escape valve for the excess of reduction equivalents in anaerobic metabolism. Biosynthesis of [NiFe] hydrogenases is a complex process that occurs in the cytoplasm, where a number of auxiliary proteins are required to synthesize and insert the metal cofactors into the enzyme structural units. The endosymbiotic bacterium Rhizobium leguminosarum requires the products of eighteen genes (hupSLCDEFGHIJKhypABFCDEX to synthesize an active hydrogenase. hupF and hupK genes are found only in hydrogenase clusters from bacteria expressing hydrogenase in the presence of oxygen. Results HupF is a HypC paralogue with a similar predicted structure, except for the C-terminal domain present only in HupF. Deletion of hupF results in the inability to process the hydrogenase large subunit HupL, and also in reduced stability of this subunit when cells are exposed to high oxygen tensions. A ?hupF mutant was fully complemented for hydrogenase activity by a C-terminal deletion derivative under symbiotic, ultra low-oxygen tensions, but only partial complementation was observed in free living cells under higher oxygen tensions (1% or 3%. Co-purification experiments using StrepTag-labelled HupF derivatives and mass spectrometry analysis indicate the existence of a major complex involving HupL and HupF, and a less abundant HupF-HupK complex. Conclusions The results indicate that HupF has a dual role during hydrogenase biosynthesis: it is required for hydrogenase large subunit processing and it also acts as a chaperone to stabilize HupL when hydrogenase is synthesized in the presence of oxygen.

  2. Rhizobium tibeticum activated with a mixture of flavonoids alleviates nickel toxicity in symbiosis with fenugreek (Trigonella foenum graecum L.).

    Science.gov (United States)

    Abd-Alla, Mohamed Hemida; Bashandy, Shymaa Ryhan; Bagy, Magdy Khalil; El-enany, Abdel-Wahab Elsadk

    2014-07-01

    The objective of this study is to explore the response of an activated Rhizobium tibeticum inoculum with a mixture of hesperetin (H) and apigenin (A) to improve the growth, nodulation, and nitrogen fixation of fenugreek (Trigonella foenum graecum L.) grown under nickel (Ni) stress. Three different sets of fenugreek seed treatments were conducted, in order to investigate the activated R. tibeticum pre-incubation effects on nodulation, nitrogen fixation and growth of fenugreek under Ni stress. Group (I): uninoculated seeds with R. tibeticum, group (II): inoculated seeds with uninduced R. tibeticum group (III): inoculated seeds with induced R. tibeticum. The present study revealed that Ni induced deleterious effects on rhizobial growth, nod gene expression, nodulation, phenylalanine ammonia-lyase (PAL) and glutamine synthetase activities, total flavonoids content and nitrogen fixation, while the inoculation with an activated R. tibeticum significantly improved these values compared with plants inoculated with uninduced R. tibeticum. PAL activity of roots plants inoculated with induced R. tibeticum and grown hydroponically at 75 and 100 mg L(-1) Ni and was significantly increased compared with plants receiving uninduced R. tibeticum. The total number and fresh mass of nodules, nitrogenase activity of plants inoculated with induced cells grown in soil treated up to 200 mg kg(-1) Ni were significantly increased compared with plants inoculated with uninduced cells. Plants inoculated with induced R. tibeticum dispalyed a significant increase in the dry mass compared with those treated with uninduced R. tibeticum. Activation of R. tibeticum inoculum with a mixture of hesperetin and apigenin has been proven to be practically important in enhancing nodule formation, nitrogen fixation and growth of fenugreek grown in Ni contaminated soils. PMID:24740320

  3. Rhizobium NodI and NodJ proteins play a role in the efficiency of secretion of lipochitin oligosaccharides.

    Science.gov (United States)

    Spaink, H P; Wijfjes, A H; Lugtenberg, B J

    1995-11-01

    Thin-layer chromatographic analysis of extracts of D-[1-14C]glucosamine-labelled rhizobia was used to analyze the effects of nodI, nodJ, and nodT on secretion of lipochitin oligosaccharide (LCO) signal molecules. Secretion was analyzed by comparing quantities of radiolabelled LCOs present in the cellular and spent growth medium fractions. A second rapid and sensitive method was introduced to estimate the secreted LCO fractions by using D-[1-14C]glucosamine-labelled cells grown in medium supplemented with chitinase. At various times after induction of LCO synthesis, the quantity of degradation products of LCOs was compared with the amount of nondegraded LCOs. In wild-type strains of Rhizobium leguminosarum biovars viciae and trifolii the nodI and nodJ genes (but not the nodT gene) strongly enhance the secretion of LCOs during the first 5 h after the induction of LCO synthesis. In LCO-overproducing strains the enhancement of secretion was observed only during the first 3 h after induction. At times later than 5 h after induction, a significant influence of the presence of the nodI and nodJ genes on LCO secretion was detectable neither in the wild type nor in LCO-overproducing strains. By using plasmids in which the nodI and nodJ genes are cloned separately under control of a flavonoid-inducible promoter, it was shown that both genes are needed for a wild-type level of LCO secretion. Therefore, these results demonstrate that nodI and nodJ play a role in determining the efficiency of LCO secretion. PMID:7592394

  4. Functional relationships between plasmids and their significance for metabolism and symbiotic performance of Rhizobium leguminosarum bv. trifolii.

    Science.gov (United States)

    Stasiak, Gra?yna; Mazur, Andrzej; Wielbo, Jerzy; Marczak, Ma?gorzata; Zebracki, Kamil; Koper, Piotr; Skorupska, Anna

    2014-11-01

    Rhizobium leguminosarum bv. trifolii TA1 (RtTA1) is a soil bacterium establishing a highly specific symbiotic relationship with clover, which is based on the exchange of molecular signals between the host plant and the microsymbiont. The RtTA1 genome is large and multipartite, composed of a chromosome and four plasmids, which comprise approximately 65 % and 35 % of the total genome, respectively. Extrachromosomal replicons were previously shown to confer significant metabolic versatility to bacteria, which is important for their adaptation in the soil and nodulation competitiveness. To investigate the contribution of individual RtTA1 plasmids to the overall cell phenotype, metabolic properties and symbiotic performance, a transposon-based elimination strategy was employed. RtTA1 derivatives cured of pRleTA1b or pRleTA1d and deleted in pRleTA1a were obtained. In contrast to the in silico predictions of pRleTA1b and pRleTA1d, which were described as chromid-like replicons, both appeared to be completely curable. On the other hand, for pRleTA1a (symbiotic plasmid) and pRleTA1c, which were proposed to be unessential for RtTA1 viability, it was not possible to eliminate them at all (pRleTA1c) or entirely (pRleTA1a). Analyses of the phenotypic traits of the RtTA1 derivatives obtained revealed the functional significance of individual plasmids and their indispensability for growth, certain metabolic pathways, production of surface polysaccharides, autoaggregation, biofilm formation, motility and symbiotic performance. Moreover, the results allow us to suggest broad functional cooperation among the plasmids in shaping the phenotypic properties and symbiotic capabilities of rhizobia. PMID:24839164

  5. PssP2 is a polysaccharide co-polymerase involved in exopolysaccharide chain-length determination in Rhizobium leguminosarum.

    Science.gov (United States)

    Marczak, Ma?gorzata; Matysiak, Paulina; Kutkowska, Jolanta; Skorupska, Anna

    2014-01-01

    Production of extracellular polysaccharides is a complex process engaging proteins localized in different subcellular compartments, yet communicating with each other or even directly interacting in multicomponent complexes. Proteins involved in polymerization and transport of exopolysaccharide (EPS) in Rhizobium leguminosarum are encoded within the chromosomal Pss-I cluster. However, genes implicated in polysaccharide synthesis are common in rhizobia, with several homologues of pss genes identified in other regions of the R. leguminosarum genome. One such region is chromosomally located Pss-II encoding proteins homologous to known components of the Wzx/Wzy-dependent polysaccharide synthesis and transport systems. The pssP2 gene encodes a protein similar to polysaccharide co-polymerases involved in determination of the length of polysaccharide chains in capsule and O-antigen biosynthesis. In this work, a mutant with a disrupted pssP2 gene was constructed and its capabilities to produce EPS and enter into a symbiotic relationship with clover were studied. The pssP2 mutant, while not altered in lipopolysaccharide (LPS), displayed changes in molecular mass distribution profile of EPS. Lack of the full-length PssP2 protein resulted in a reduction of high molecular weight EPS, yet polymerized to a longer length than in the RtTA1 wild type. The mutant strain was also more efficient in symbiotic performance. The functional interrelation between PssP2 and proteins encoded within the Pss-I region was further supported by data from bacterial two-hybrid assays providing evidence for PssP2 interactions with PssT polymerase, as well as glycosyltransferase PssC. A possible role for PssP2 in a complex involved in EPS chain-length determination is discussed. PMID:25268738

  6. Mutation of praR in Rhizobium leguminosarum enhances root biofilms, improving nodulation competitiveness by increased expression of attachment proteins.

    Science.gov (United States)

    Frederix, Marijke; Edwards, Anne; Swiderska, Anna; Stanger, Andrew; Karunakaran, Ramakrishnan; Williams, Alan; Abbruscato, Pamela; Sanchez-Contreras, Maria; Poole, Philip S; Downie, J Allan

    2014-08-01

    In Rhizobium leguminosarum bv. viciae, quorum-sensing is regulated by CinR, which induces the cinIS operon. CinI synthesizes an AHL, whereas CinS inactivates PraR, a repressor. Mutation of praR enhanced biofilms in vitro. We developed a light (lux)-dependent assay of rhizobial attachment to roots and demonstrated that mutation of praR increased biofilms on pea roots. The praR mutant out-competed wild-type for infection of pea nodules in mixed inoculations. Analysis of gene expression by microarrays and promoter fusions revealed that PraR represses its own transcription and mutation of praR increased expression of several genes including those encoding secreted proteins (the adhesins RapA2, RapB and RapC, two cadherins and the glycanase PlyB), the polysaccharide regulator RosR, and another protein similar to PraR. PraR bound to the promoters of several of these genes indicating direct repression. Mutations in rapA2, rapB, rapC, plyB, the cadherins or rosR did not affect the enhanced root attachment or nodule competitiveness of the praR mutant. However combinations of mutations in rapA, rapB and rapC abolished the enhanced attachment and nodule competitiveness. We conclude that relief of PraR-mediated repression determines a lifestyle switch allowing the expression of genes that are important for biofilm formation on roots and the subsequent initiation of infection of legume roots. PMID:24942546

  7. Functional and expression analysis of the metal-inducible dmeRF system from Rhizobium leguminosarum bv. viciae.

    Science.gov (United States)

    Rubio-Sanz, L; Prieto, R I; Imperial, J; Palacios, J M; Brito, B

    2013-10-01

    A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel- and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria. PMID:23934501

  8. Autotrophic growth of H2-uptake-positive strains of Rhizobium japonicum in an atmosphere supplied with hydrogen gas.

    Science.gov (United States)

    Hanus, F J; Maier, R J; Evans, H J

    1979-04-01

    Previous research from this laboratory has demonstrated CO(2)-fixing and H(2)-uptake capacities of certain strains of Rhizobium japonicum. In this report we have shown that SR, a H(2)-uptake-positive (Hup(+)) strain of R. japonicum, is capable of autotrophic growth with H(2) as the energy source. Growth occurred on mineral salts/vitamins/Noble agar, mineral salts/vitamins liquid medium (0.27 mug of C as vitamins per ml), and in mineral salts liquid medium with no added vitamins when cultures were provided with NH(4)Cl and incubated in an atmosphere containing H(2), CO(2), O(2), and N(2). Little or no growth occurred when either H(2) or CO(2) was omitted from the atmosphere or when the culture was inoculated with SR3, a Hup(-) mutant of SR. Growth was measured by protein synthesis, fixed organic carbon, and increase in cell number in liquid cultures. The organism that grew autotrophically was verified as R. japonicum by (i) apparent purity on streak plates; (ii) retention of the double antibiotic resistance markers; and (iii) its capability to nodulate soybeans. H(2)- and CO(2)-supported growth was demonstrated for three additional Hup(+) wild-type R. japonicum strains (USDA 136, 3I1b 6, and 3I1b 143), while three Hup(-) wild-type strains (USDA 120, 3I1b 144, and USDA 117) were incapable of growth on the Noble agar medium containing mineral salts/vitamins in the H(2)/CO(2)/O(2)/N(2) atmosphere. This demonstrated capability of Hup(+)R. japonicum strains to grow autotrophically requires revision of current concepts regarding conditions for survival and competition of these bacteria in the soil and their relationships to other microorganisms. PMID:287019

  9. Modulation of rosR Expression and Exopolysaccharide Production in Rhizobium leguminosarum bv. trifolii by Phosphate and Clover Root Exudates

    Directory of Open Access Journals (Sweden)

    Anna Skorupska

    2011-06-01

    Full Text Available The acidic exopolysaccharide (EPS secreted in large amounts by the symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii is required for the establishment of an effective symbiosis with the host plant Trifolium spp. EPS biosynthesis in rhizobia is a very complex process regulated at both transcriptional and post-transcriptional levels and influenced by various nutritional and environmental conditions. The R. leguminosarum bv. trifolii rosR gene encodes a transcriptional regulator with a C2H2 type zinc-finger motif involved in positive regulation of EPS synthesis. In silico sequence analysis of the 450-bp long rosR upstream region revealed the presence of several inverted repeats (IR1 to IR6 and motifs with significant identity to consensus sequences recognized by PhoB and LysR-type proteins associated with phosphate- and flavonoid-dependent gene regulation in R. leguminosarum. Using a set of sequentially truncated rosR-lacZ transcriptional fusions, the role of the individual motifs and the effect of phosphate and clover root exudates on rosR expression were established. In addition, the significance of IR4 inverted repeats in the repression, and P2–10 hexamer in the activation of rosR transcription, respectively, was found. The expression of rosR increased in the presence of phosphate (0.1–20 mM and clover root exudates (10 ?M. PHO boxes and the LysR motif located upstream of the rosR translation start site were engaged in the regulation of rosR transcription. The synthesis of EPS and biofilm formation decreased at high phosphate concentrations, but increased in the presence of clover root exudates, indicating a complex regulation of these processes.

  10. Identification and characterization of RibN, a novel family of riboflavin transporters from Rhizobium leguminosarum and other proteobacteria.

    Science.gov (United States)

    García Angulo, Víctor A; Bonomi, Hernán R; Posadas, Diana M; Serer, María I; Torres, Alfredo G; Zorreguieta, Ángeles; Goldbaum, Fernando A

    2013-10-01

    Rhizobia are symbiotic bacteria able to invade and colonize the roots of legume plants, inducing the formation of nodules, where bacteria reduce atmospheric nitrogen (N2) to ammonia (NH3). Riboflavin availability influences the capacity of rhizobia to survive in the rhizosphere and to colonize roots. In this study, we identified the RL1692 gene of Rhizobium leguminosarum downstream of a flavin mononucleotide (FMN) riboswitch. RL1692 encodes a putative transmembrane permease with two EamA domains. The presence of an FMN riboswitch regulating a transmembrane protein is usually observed in riboflavin transporters, suggesting that RL1692 may be involved in riboflavin uptake. The product of RL1692, which we named RibN, is conserved in members of the alpha-, beta-, and gammaproteobacteria and shares no significant identity with any riboflavin transporter previously identified. In this work, we show that RibN is localized in the membrane cellular fraction and its expression is downregulated by riboflavin. By heterologous expression in a Brucella abortus mutant auxotrophic for riboflavin, we demonstrate that RibN possesses flavin transport activity. Similarly, we also demonstrate that RibN orthologues from Ochrobactrum anthropi and Vibrio cholerae (which lacks the FMN riboswitch) are able to transport riboflavin. An R. leguminosarum ribN null mutant exhibited lower nodule occupancy levels in pea plants during symbiosis assays. Thus, we propose that RibN and its homologues belong to a novel family of riboflavin transporters. This work provides the first experimental description of riboflavin transporters in Gram-negative bacteria. PMID:23935051

  11. Occurrence of polyamines in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici in response to salt stress.

    Science.gov (United States)

    López-Gómez, Miguel; Cobos-Porras, Libertad; Hidalgo-Castellanos, Javier; Lluch, Carmen

    2014-11-01

    Polyamines (PAs) are low molecular weight aliphatic compounds that have been shown to be an important part of plant responses to salt stress. For that reason in this work we have investigated the involvement of PAs in the response to salt stress in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici. The level and variety of PAs was higher in nodules, compared to leaves and roots, and in addition to the common PAs (putrescine, spermidine and spermine) we found homospermidine (Homspd) as the most abundant polyamine in nodules. UPLC-mass spectrometry analysis revealed the presence of 4-aminobutylcadaverine (4-ABcad), only described in nodules of Vigna angularis before. Indeed, the analysis of different nodular fractions revealed higher level of 4-ABcad, as well as Homspd, in bacteroids which indicate the production of these PAs by the bacteria in symbiosis. The genes involved in PAs biosynthesis in nodules displayed an induction under salt stress conditions which was not consistent with the decline of free PAs levels, probably due to the nitrogen limitations provoked by the nitrogenase activity depletion and/or the conversion of free PAs to theirs soluble conjugated forms, that seems to be one of the mechanisms involved in the regulation of PAs levels. On the contrary, cadaverine (Cad) and 4-ABcad concentrations augmented by the salinity, which might be due to their involvement in the response of bacteroids to hyper-osmotic conditions. In conclusion, the results shown in this work suggest the alteration of the bacteroidal metabolism towards the production of uncommon PAs such as 4-ABcad in the response to salt stress in legume root nodules. PMID:25220497

  12. VsENOD5, VsENOD12 and VsENOD40 expression during Rhizobium-induced nodule formation on Vicia sativa roots.

    DEFF Research Database (Denmark)

    Vijn, I; Yang, W C

    1995-01-01

    We isolated ENOD5, ENOD12 and ENOD40 homologues from Vicia sativa and studied their expression pattern during Rhizobium-induced nodule formation. Comparison of the VsENOD40 nucleotide sequence with the pea, soybean and alfalfa ENOD40 sequences showed that the sequences contain two conserved regions, called region I and region II. Comparison of all the potential open reading frames (ORFs) showed that all the five different ENOD40 clones encode a highly conserved small polypeptide of 12 or 13 amino acids encoded by an ORF located in region I. Furthermore we studied with in situ hybridization the expression pattern of VsENOD5, VsENOD12 and VsENOD40 during Rhizobium-induced nodule formation. Although the expression of these genes is largely similar to that of the pea counterparts, differences where found for the expression of VsENOD12 and VsENOD40 in Vicia. VsENOD12 is expressed in the whole prefixation zone II, whereas in pea ENOD12 is only expressed in the distal part of this zone. VsENOD40 is expressed in the uninfected cells of interzone II-III, while in pea ENOD40 is expressed in both the uninfected and infected cells of this zone. Udgivelsesdato: 1995-Sep

  13. Rhizobium nodulation protein NodA is a host-specific determinant of the transfer of fatty acids in Nod factor biosynthesis.

    Science.gov (United States)

    Ritsema, T; Wijfjes, A H; Lugtenberg, B J; Spaink, H P

    1996-04-24

    In the biosynthesis of lipochitin oligosaccharides (LCOs) the Rhizobium nodulation protein NodA plays an essential role in the transfer of an acyl chain to the chitin oligosaccharide acceptor molecule. The presence of nodA in the nodABCIJ operon makes genetic studies difficult to interpret. In order to be able to investigate the biological and biochemical functions of NodA, we have constructed a test system in which the nodA, nodB and nodC genes are separately present on different plasmids. Efficient nodulation was only obtained if nodC was present on a low-copy-number vector. Our results confirm the notion that nodA of Rhizobium leguminosarum biovar viciae is essential for nodulation on Vicia. Surprisingly, replacement of R. l. by viciae nodA by that of Bradyrhizobium sp. ANU289 results in a nodulation-minus phenotype on Vicia. Further analysis revealed that the Bradyrhizobium sp. ANU289 NodA is active in the biosynthesis of LCOs, but is unable to direct the transfer of the R. l. by, viciae nodFE-dependent multi-unsaturated fatty acid to the chitin oligosaccharide acceptor. These results lead to the conclusion that the original notion that nodA is a common nod gene should be revised. PMID:8628246

  14. Genetic analysis of the Rhizobium meliloti exoYFQ operon: ExoY is homologous to sugar transferases and ExoQ represents a transmembrane protein.

    Science.gov (United States)

    Müller, P; Keller, M; Weng, W M; Quandt, J; Arnold, W; Pühler, A

    1993-01-01

    The nucleotide sequence of a 4.8-kb ClaI-EcoRI DNA fragment of megaplasmid 2 of Rhizobium meliloti Rm2011 involved in succinoglucan (EPS I) synthesis and nodule infection was determined. Four open reading frames (ORFs) were identified on this fragment. A mutational analysis revealed that these ORFs represent genes that were termed exoX, exoY, exoF, and exoQ. The locations of transposon insertions in these exo genes were determined at the nucleotide level. Plasmid integration mutagenesis revealed that the genes exoY, exoF, and exoQ are organized in an operon. The exoX gene running in opposite direction forms a monocistronic transcriptional unit. The exoX gene was shown to negatively influence the amount of EPS I synthesized. The exoY gene is coding for a membrane associated protein homologous to the C-terminal part of the Xanthomonas campestris glucosyltransferase GumD and the Salmonella typhimurium galactose transferase RfbP. ExoF, a probable periplasmatic protein, is nearly identical to the protein encoded by ORF1 of Rhizobium sp. strain NGR234. ExoQ is most probably a membrane associated protein as deduced by its hydrophobic structural features. All three genes of the exoYFQ operon were shown to be essential for succinoglucan synthesis and nodule infection. PMID:8439670

  15. Reduction in pathogen populations at grapevine wound sites is associated with the mechanism underlying the biological control of crown gall by rhizobium vitis strain ARK-1.

    Science.gov (United States)

    Kawaguchi, Akira

    2014-09-17

    A nonpathogenic strain of Rhizobium (=Agrobacterium) vitis, ARK-1, limited the development of grapevine crown gall. A co-inoculation with ARK-1 and the tumorigenic strain VAT07-1 at a 1:1 cell ratio resulted in a higher population of ARK-1 than VAT07-1 in shoots without tumors, but a significantly lower population of ARK-1 than VAT07-1 in grapevine shoots with tumors. ARK-1 began to significantly suppress the VAT07-1 population 2 d after the inoculation. This result indicated that ARK-1 reduced the pathogen population at the wound site through biological control. Although ARK-1 produced a zone of inhibition against other tumorigenic Rhizobium spp. in in vitro assays, antibiosis depended on the culture medium. ARK-1 did not inhibit the growth of tumorigenic R. radiobacter strain AtC1 in the antibiosis assay, but suppressed the AtC1-induced formation of tumors on grapevine shoots, suggesting that antibiosis by ARK-1 may not be the main mechanism responsible for biological control. PMID:25077443

  16. Polymorphic infection and organogenesis patterns induced by a Rhizobium leguminosarum isolate from Lotus root nodules are determined by the host genotype.

    Science.gov (United States)

    Gossmann, Jasmin A; Markmann, Katharina; Brachmann, Andreas; Rose, Laura E; Parniske, Martin

    2012-10-01

    To sample the natural variation in genes controlling compatibility in the legume-rhizobium symbiosis, we isolated rhizobia from nodules of endemic Lotus species from 21 sites across Europe. The majority of isolates were identified as Mesorhizobium- or Bradyrhizobium-related and formed nitrogen-fixing root nodules on Lotus corniculatus and L. pendunculatus, respectively, thus confirming previously defined cross-inoculation groups. Rhizobium leguminosarum (Rl) strain Norway, isolated from L. corniculatus nodules, displayed an exceptional phenotypic variation on different Lotus genotypes. On L. burttii, Rl Norway formed infected nodules, whereas tumors and elongated infected swellings were induced on L. glaber and L. japonicus ecotype Nepal, respectively. A symbiosis- and Nod-factor-responsive promoter:uidA fusion was strongly and rapidly induced in L. japonicus Gifu, but infection threads or signs of nodule organogenesis were absent. This complex phenotypic pattern was not mimicked by either of three engineered R. leguminosarum bv viciae strains producing different Nod-factor variants. Intriguingly, Rl Norway formed infection threads on Pisum sativum cv Sparkle, but failed to induce organogenesis. Rl Norway thus uncovered variation in symbiotic capabilities among diploid Lotus species and ecotypes that are obscured by optimally adapted M. loti strains. These contrasting infection and organogenesis phenotypes reveal recent diversification of recognition determinants in Lotus. PMID:22950721

  17. Mutation in the pssA Gene Involved in Exopolysaccharide Synthesis Leads to Several Physiological and Symbiotic Defects in Rhizobium leguminosarum bv. trifolii

    Directory of Open Access Journals (Sweden)

    Monika Janczarek

    2013-12-01

    Full Text Available The symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii 24.2 secretes large amounts of acidic exopolysaccharide (EPS, which plays a crucial role in establishment of effective symbiosis with clover. The biosynthesis of this heteropolymer is conducted by a multi-enzymatic complex located in the bacterial inner membrane. PssA protein, responsible for the addition of glucose-1-phosphate to a polyprenyl phosphate carrier, is involved in the first step of EPS synthesis. In this work, we characterize R. leguminosarum bv. trifolii strain Rt270 containing a mini-Tn5 transposon insertion located in the 3'-end of the pssA gene. It has been established that a mutation in this gene causes a pleiotropic effect in rhizobial cells. This is confirmed by the phenotype of the mutant strain Rt270, which exhibits several physiological and symbiotic defects such as a deficiency in EPS synthesis, decreased motility and utilization of some nutrients, decreased sensitivity to several antibiotics, an altered extracellular protein profile, and failed host plant infection. The data of this study indicate that the protein product of the pssA gene is not only involved in EPS synthesis, but also required for proper functioning of Rhizobium leguminosarum bv. trifolii cells.

  18. Mutation in the pssA gene involved in exopolysaccharide synthesis leads to several physiological and symbiotic defects in Rhizobium leguminosarum bv. trifolii.

    Science.gov (United States)

    Janczarek, Monika; Rachwa?, Kamila

    2013-01-01

    The symbiotic nitrogen-fixing bacterium Rhizobium leguminosarum bv. trifolii 24.2 secretes large amounts of acidic exopolysaccharide (EPS), which plays a crucial role in establishment of effective symbiosis with clover. The biosynthesis of this heteropolymer is conducted by a multi-enzymatic complex located in the bacterial inner membrane. PssA protein, responsible for the addition of glucose-1-phosphate to a polyprenyl phosphate carrier, is involved in the first step of EPS synthesis. In this work, we characterize R. leguminosarum bv. trifolii strain Rt270 containing a mini-Tn5 transposon insertion located in the 3'-end of the pssA gene. It has been established that a mutation in this gene causes a pleiotropic effect in rhizobial cells. This is confirmed by the phenotype of the mutant strain Rt270, which exhibits several physiological and symbiotic defects such as a deficiency in EPS synthesis, decreased motility and utilization of some nutrients, decreased sensitivity to several antibiotics, an altered extracellular protein profile, and failed host plant infection. The data of this study indicate that the protein product of the pssA gene is not only involved in EPS synthesis, but also required for proper functioning of Rhizobium leguminosarum bv. trifolii cells. PMID:24317432

  19. Biodiversity of Mimosa pudica rhizobial symbionts (Cupriavidus taiwanensis, Rhizobium mesoamericanum) in New Caledonia and their adaptation to heavy metal-rich soils.

    Science.gov (United States)

    Klonowska, Agnieszka; Chaintreuil, Clémence; Tisseyre, Pierre; Miché, Lucie; Melkonian, Rémy; Ducousso, Marc; Laguerre, Gisèle; Brunel, Brigitte; Moulin, Lionel

    2012-09-01

    Rhizobia are soil bacteria able to develop a nitrogen-fixing symbiosis with legumes. They are taxonomically spread among the alpha and beta subclasses of the Proteobacteria. Mimosa pudica, a tropical invasive weed, has been found to have an affinity for beta-rhizobia, including species within the Burkholderia and Cupriavidus genera. In this study, we describe the diversity of M. pudica symbionts in the island of New Caledonia, which is characterized by soils with high heavy metal content, especially of Ni. By using a plant-trapping approach on four soils, we isolated 96 strains, the great majority of which belonged to the species Cupriavidus taiwanensis (16S rRNA and recA gene phylogenies). A few Rhizobium strains in the newly described species Rhizobium mesoamericanum were also isolated. The housekeeping and nod gene phylogenies supported the hypothesis of the arrival of the C. taiwanensis and R. mesoamericanum strains together with their host at the time of the introduction of M. pudica in New Caledonia (NC) for its use as a fodder. The C. taiwanensis strains exhibited various tolerances to Ni, Zn and Cr, suggesting their adaptation to the specific environments in NC. Specific metal tolerance marker genes were found in the genomes of these symbionts, and their origin was investigated by phylogenetic analyses. PMID:22512707

  20. Evaluation of the coal-degrading ability of Rhizobium and Chelatococcus strains isolated from the formation water of an Indian coal bed.

    Science.gov (United States)

    Singh, Durgesh Narain; Tripathi, Anil Kumar

    2011-11-01

    The rise in global energy demand has prompted researches on developing strategies for transforming coal into a cleaner fuel. This requires isolation of microbes with the capability to degrade complex coal into simpler substrates to support methanogenesis in the coal beds. In this study, aerobic bacteria were isolated from an Indian coal bed that can solubilize and utilize coal as the sole source of carbon. The six bacterial isolates capable of growing on coal agar medium were identified on the basis of their 16S rRNA gene sequences, which clustered into two groups; Group I isolates belonged to the genus Rhizobium, whereas Group II isolates were identified as Chelatococcus species. Out of the 4 methods of whole genome fingerprinting (ERIC-PCR, REP-PCR, BOX-PCR, and RAPD), REPPCR showed maximum differentiation among strains within each group. Only Chelatococcus strains showed the ability to solubilize and utilize coal as the sole source of carbon. On the basis of 16S rRNA gene sequence and the ability to utilize different carbon sources, the Chelatococcus strains showed maximum similarity to C. daeguensis. This is the first report showing occurrence of Rhizobium and Chelatococcus strains in an Indian coal bed, and the ability of Chelatococcus isolates to solubilize and utilize coal as a sole source of carbon for their growth. PMID:22127119

  1. Effect of aldicarb on growth and radio-carbon (14C) and radio-phosphorus (32P) assimilation by Rhizobium japonicum

    International Nuclear Information System (INIS)

    In vitro studies on the effect of aldicarb (2-methyl-2-(methyl thio) propionaldehde-o-methyl carbamoyl oxime), a soil applied systemic insecticide, on Rhizobium japonicum revealed that the chemical (at 1,2 and 5 ppm levels) stimulated the growth of the organism initially upto 48 hr which declined thereafter upto 72 hr. The incorporation of 14C-glucose by the cells considerably reduced due to the insecticide treatment. The production of extracellular, water-soluble slime (polysacchardes) was also reduced considerably with increased concentrations of the chemical. However, the incorporation of 14C-radio-activity in the extracellular slime generally enhanced due to the treatment, upto 6 hr after injection of the radioactivity, which declined significantly later at 15 hr, indicating a qualitative difference in the extracellular polysaccharides produced by the insecticide treated cells. The insecticide treatment drastically reduced the incorporation of 32P-disodium hydrogen phosphate into Rhizobium cells, but enhanced the specific activity of the extracellular polysacchrides. (author)

  2. FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Lettenmaier, Dennis [University of Washsington

    2012-05-26

    We proposed to extend Maurer’s data sets through at least 2005 (to include extreme drought years in the Colorado basin). We updated and verified the forcings for tmin, tmax, and precipitation over the Colorado River basin at 1/8-deg spatial resolution through November 2008, with the potential to alter the resolution as needed (we subsequently extended the Maurer et al data set over the entire continental U.S. at 1/16 degree spatial resolution; see Livneh et al., 2013). We proposed to use either MODIS-based land cover data for recent years, or modification of the existing fixed seasonal cycle used in VIC (based on University of Maryland land cover data) to represent interannual variations in vegetation characteristics such as leaf area index (LAI) particularly in drought years. We assessed model performance with respect to evapotranspiration estimation through comparison of the model predictions with ground observations and in experiments that use time-varying and fixed seasonal LAI cycles (based on University of Maryland land cover data) in a test region of northwestern Mexico where the ground ET observations from eddy covariance tower sites are available for the period from 2001 to 2008 (Tang et al., 2011). We also proposed to implement statistical downscaling with an adjustment to constrain precipitation changes at the GCM level. These simulations were performed, using 20 IPCC AR4 GCMs over the Colorado River basin with two global emissions scenarios, and are reported in Vano et al., 2014. Task 2: Coupled model implementation We proposed to implement the “standard” climate version of WRF, as used by collaborator Ruby Leung in NARCCAP simulations (see Section 5.4), and perform tests to assure that model output for runs equivalent to NARCCAP Phase 1 (reanalysis boundary conditions) are consistent. We proposed do test sensitivity to higher spatial resolution. We made a run of 11 years’ length with the “standard” version of WRF, forced by NCEP/DOE with the same spatial resolution as WRF in NARCCAP, with a slightly different domain designed to cover the Colorado River basin. We also compared the sensitivity of standard WRF simulations to different spatial resolutions (50 km, 25 km and 16 km). We proposed to implement the WRF-VIC version, and to evaluate differences between the “standard” WRF version (with CLM as the land scheme) and WRF-VIC. As part of a companion project (Regional Arctic Climate Model; RACM), we have linked the macroscale hydrologic model VIC (Variable Infiltration Capacity) with WRF through the CCSM coupling architecture CPL7. We decided to defer making new model runs with VIC over the Colorado basin and rather to focus on analysis of NARCCAP results. Our preliminary results from analysis of NARCCAP current and future climate results (reported in Gao et al., 2011) indicate that CRCM has a cold bias; HRM3 has a warm bias; and ECPC and CRCM have a wet bias over the Colorado River basin. Task 3: Retrospective coupled model simulations We proposed to compare the climatology of key land surface and atmospheric variables from the retrospective RCM and GCM runs, as well as 1/8-degree as the historical North American Land Data Assimilation System dataset (Maurer et al., 2002) to evaluate the ability of each of the RCMs and GCMs to reproduce characteristics of observed climate. In addition to the NARCCAP runs analyzed under Task 2, we also evaluated an ECHAM5/WRF run performed by Eric Salathe and HadCM3/WRF run performed by Francina Dominguez (University of Arizona). Results of the retrospective RCM runs indicate that they capture the primary features of the observed land–surface water budget and surface temperature better than their host GCMs. Although the RCMs do not have significantly improved simulations of precipitation relative to the GCMs, their ability to better represent surface temperature in mountainous regions has important effects on simulations of evapotranspiration, snowpack, and runoff. This improved skill in simulating temperature is important for detecting climate change signals

  3. Micorriza arbuscular e rizóbios no enraizamento e nutrição de mudas de angico-vermelho / Arbuscular mycorrhizae and rhizobium in rooting and nutrition of angico-vermelho seedlings

    Scientific Electronic Library Online (English)

    Poliana Coqueiro, Dias; Muriel da Silva Folli, Pereira; Maria Catarina, MegumiKasuya; Haroldo Nogueira de, Paiva; Leandro Silva de, Oliveira; Aloisio, Xavier.

    1027-10-01

    Full Text Available O objetivo deste estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs) e rizóbio no enraizamento, crescimento e nutrição de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth) Brenan) propagadas via miniestaquia. Foram utilizadas seis progênies, das quais foram [...] confeccionadas miniestacas com um par de folhas inteiras, bem como tubetes de 55 cm³ contendo substrato comercial Bioplant®. Foram testados quatro tratamentos: 8 kg m-3 de superfosfato simples (SS) misturados ao substrato; 4 kg m-3 de SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato e adição de suspensão contendo rizóbios; e 4 kg m-3 de SS e adição de suspensão contendo rizóbios e 5 g de solo contendo esporos de FMAs. Não houve interação entre os tratamentos para percentagem de sobrevivência das miniestacas e percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, na saída da casa de vegetação (30 dias) e da casa de sombra (40 dias), provavelmente em função do sistema radicular ainda estar em formação. Houve diferenças entre as progênies para percentagem de sobrevivência das miniestacas, percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, altura, diâmetro de colo e massa seca da parte aérea. As avaliações das características de crescimento das miniestacas enraizadas, principalmente com relação à sobrevivência a pleno sol (140 dias), evidenciam a eficiência dos rizóbios e FMAs na produção de mudas desta espécie. Conclui-se que a associação simbiótica com rizóbio e/ou FMA favorece a produção de mudas de A. macrocarpa via miniestaquia. Abstract in english The objective of this study was to evaluate the effect of inoculation of arbuscular mycorrhizae fungi (AMF) and rhizobium on rooting, growth and nutrition of seedlings of angico-red (Anadenanthera macrocarpa (Benth) Brenan) propagated by minicutting. Six progenies were used, of which were prepared c [...] uttings with a pair of complete leaves. It was used a 55 cm³container filled with commercial substrate Bioplant®. Four treatments were tested: 8 kg m-3 of superphosphate (SS) added to substrate; 4 kg m-3 SS added to substrate; 4 kg m-3 SS added to substrate and adition of a suspension solution containing rhizobium; 4 kg m-3 SS and suspension solution containing rhizobium plus 5 g of soil contaminated by AMF spores. There was no interaction among treatments for survival rate of cuttings and roots observed at bottom of the container, evaluated in the greenhouse exit (30 days) and the shade house exit (40 days), probably because the root system was still in formation. There were differences among the progeny for survival rate of the shoots, the percentage of cuttings with roots observed at bottom of the container, height, stem diameter and shoot dry weight. The evaluations of the growth characteristics of the cuttings in, particularly with respect to survival at full sun (140 days), demonstrate the efficiency of rhizobium and AMF on seedling production of this species. We conclude that the symbiotic association with rhizobium and / or FMA favors the production of seedlings of A. macrocarpa by minicutting.

  4. Micorriza arbuscular e rizóbios no enraizamento e nutrição de mudas de angico-vermelho Arbuscular mycorrhizae and rhizobium in rooting and nutrition of angico-vermelho seedlings

    Directory of Open Access Journals (Sweden)

    Poliana Coqueiro Dias

    2012-12-01

    Full Text Available O objetivo deste estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs e rizóbio no enraizamento, crescimento e nutrição de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth Brenan propagadas via miniestaquia. Foram utilizadas seis progênies, das quais foram confeccionadas miniestacas com um par de folhas inteiras, bem como tubetes de 55 cm³ contendo substrato comercial Bioplant®. Foram testados quatro tratamentos: 8 kg m-3 de superfosfato simples (SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato e adição de suspensão contendo rizóbios; e 4 kg m-3 de SS e adição de suspensão contendo rizóbios e 5 g de solo contendo esporos de FMAs. Não houve interação entre os tratamentos para percentagem de sobrevivência das miniestacas e percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, na saída da casa de vegetação (30 dias e da casa de sombra (40 dias, provavelmente em função do sistema radicular ainda estar em formação. Houve diferenças entre as progênies para percentagem de sobrevivência das miniestacas, percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, altura, diâmetro de colo e massa seca da parte aérea. As avaliações das características de crescimento das miniestacas enraizadas, principalmente com relação à sobrevivência a pleno sol (140 dias, evidenciam a eficiência dos rizóbios e FMAs na produção de mudas desta espécie. Conclui-se que a associação simbiótica com rizóbio e/ou FMA favorece a produção de mudas de A. macrocarpa via miniestaquia.The objective of this study was to evaluate the effect of inoculation of arbuscular mycorrhizae fungi (AMF and rhizobium on rooting, growth and nutrition of seedlings of angico-red (Anadenanthera macrocarpa (Benth Brenan propagated by minicutting. Six progenies were used, of which were prepared cuttings with a pair of complete leaves. It was used a 55 cm³container filled with commercial substrate Bioplant®. Four treatments were tested: 8 kg m-3 of superphosphate (SS added to substrate; 4 kg m-3 SS added to substrate; 4 kg m-3 SS added to substrate and adition of a suspension solution containing rhizobium; 4 kg m-3 SS and suspension solution containing rhizobium plus 5 g of soil contaminated by AMF spores. There was no interaction among treatments for survival rate of cuttings and roots observed at bottom of the container, evaluated in the greenhouse exit (30 days and the shade house exit (40 days, probably because the root system was still in formation. There were differences among the progeny for survival rate of the shoots, the percentage of cuttings with roots observed at bottom of the container, height, stem diameter and shoot dry weight. The evaluations of the growth characteristics of the cuttings in, particularly with respect to survival at full sun (140 days, demonstrate the efficiency of rhizobium and AMF on seedling production of this species. We conclude that the symbiotic association with rhizobium and / or FMA favors the production of seedlings of A. macrocarpa by minicutting.

  5. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    R Paul Drake

    2004-01-12

    OAK-B135 This is the final report from the project Hydrodynamics by High-Energy-Density Plasma Flow and Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications. This project supported a group at the University of Michigan in the invention, design, performance, and analysis of experiments using high-energy-density research facilities. The experiments explored compressible nonlinear hydrodynamics, in particular at decelerating interfaces, and the radiation hydrodynamics of strong shock waves. It has application to supernovae, astrophysical jets, shock-cloud interactions, and radiative shock waves.

  6. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Susanne

    2015-02-09

    We participated in a FASTER SCM intercomparison for which we ran our SCM for 3 years at the SGP to analyze statistics of the precipitation field (Song et al., 2013). An important feature of these simulations was the use of relaxation forcing to observed T, q, which decouples the model convection from the forcing and allows precipitation errors to emerge. Because the GISS cumulus parameterization includes a trigger that prevents convection until sufficient lifting is present, and because convection at the SGP is usually triggered by mesoscale motions that are not represented in the forcing when relaxation is applied, the duration of SCM precipitation is shorter than observed (Del Genio and Wolf, 2012) and thus its mean precipitation less than observed. However, its diurnal cycle phase is correct, and it is the only operational cumulus parameterization in the intercomparison that does not produce excessive warm season precipitation under weak large-scale forcing conditions.

  7. RHIZOBIUM ETLI USDA9032 ENGINEERED TO PRODUCE A PHENAZINE ANTIBIOTIC INHIBITS THE GROWTH OF FUNGAL PATHOGENS BUT IS IMPAIRED IN SYMBIOTIC PERFORMANCE

    Science.gov (United States)

    Phenazine antibiotics produced by Pseudomonas spp. play a major role in preventing various plant diseases. In this study, the phenazine biosynthesis locus of P. chlororaphis O6, a plant growth-promoting rhizobacteria (PGPR), was introduced into several symbiotic bacteria belonging to the family Rh...

  8. Final environmental statement related to the operation of Catawba Nuclear Station, Units 1 and 2. Docket Nos. 50-413 and 50-414, Duke Power Company, et al

    International Nuclear Information System (INIS)

    This Final Environmental Statement contains the second assessment of the environmental impact associated with the operation of the Catawba Nuclear Station, Units 1 and 2, pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR 51, as amended, of the NRC regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial and aquatic-ecological impacts will be small. Operational impacts to historic and archeological sites will be negligible. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial

  9. C. Petrone et al.: "Magnetic measurement of the model magnet QD0 designed for the CLIC final focus beam transport line." CERN TE-MSC Internal Note, EDMS Nr: 1184196

    CERN Document Server

    Arpaia, Pasquale; Petrone, Carlo; Russenschuck, Stephan; Walckiers, Louis

    2012-01-01

    This note presents the results of the magnetic measurements performed on QD0, model magnet for the final focus transport line for CLIC (Fig. 1). This high-gradient, hybrid quadrupole has a yoke length of 0.1 m and an aperture of 8.3 mm. ND2Fe14B Permanent magnet blocks provide a gradient of 150 T/m, which can be further increased to 530 T/m when the four coils are excited to 18.3 A. The request was to measure the strength of the field and the multipole coefficients at different currents. The measurement of the field strength, by means of the single stretched wire system, was done in December 2011 in the I8 laboratory. The measurement of the multipole was done by means of the oscillating wire system [1][2].

  10. Synthesis and adsorption properties of titanosilicates ETS-4 and ETS-10 from fly ash

    International Nuclear Information System (INIS)

    Highlights: ? Titanosilicates (ETS-4 and ETS-10) have been synthesized from waste fly ash. ? These materials showed similar properties to those prepared from traditional starting materials. ? The supernatant liquid after product formation (ETS-4) can be recycled and the final by-product is NaCl. ? These materials can be used for CO2/CH4 and N2 adsorption. - Abstract: ETS-4 and ETS-10 titanosilicates were prepared from fly ash and anatase, as silica and titanium sources respectively, via a hydrothermal procedure for the first time. The fusion of fly ash by alkali was carried out at a relatively low temperature and the use potassium fluoride salt was avoided in the synthesis of ETS. The by-product of this process is mainly NaCl, which is a useful source material for industry. The energy efficiency and yield of the synthesis process was improved by directly recycling the final filtrate after recovering the product viz ETS-4. All the ETS materials were characterized in terms of structural morphology, thermal stability and surface/pore properties. The properties of ETS-4 prepared from fly ash by the filtrate recycling method were comparable to that from commercial sources. The results show that ETS type materials can be prepared from cheaper resources, with good purity, comparable physico-chemical properties as well as excellent adsorption properties with lower environmental impact.

  11. Imprensa política e pensamento republicano no Paraná no final do XIX / Presse politique et pensée républicaine dans l'état du Paraná à la fin du XIXème siècle / Political journalism and republican thought in late 19th century Paraná

    Scientific Electronic Library Online (English)

    Amélia Siegel, Corrêa.

    2009-02-01

    Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A crise do regime monárquico brasileiro veio acompanhada do surgimento e da expansão do movimento republicano, no final do século XIX. No período, a imprensa não somente colocou-se como palco dos debates institucionais, como também teve papel de poder informal, vinculado ao governo e à organização p [...] artidária. Tratava-se de uma imprensa de opinião, que tinha como um de seus eixos os comentários partidários. As colunas dos jornais eram usadas para escrever anonimamente o que não podia ser dito publicamente na Assembléia, Senado ou Câmara, constituindo um fórum de discussão alternativo à tribuna. Este artigo busca recuperar os modelos de República que circularam nesses periódicos paranaenses, relacionando-os com as configurações nas quais estavam inseridos e com a posição que ocupavam no campo do poder local e nacional. Todavia, vale lembrar que os ideários republicanos dominantes não foram disseminados sem resistência no Paraná; ao contrário, foram detectados e combatidos localmente, porém sem força política suficiente. Parte-se da perspectiva bourdiesiana de que os discursos não são unicamente signos destinados a serem compreendidos e decifrados, mas também indicativos de status, que se propõem a ser valorados e apreciados, e de autoridade, a serem cridos e obedecidos, por constituírem um objeto da luta simbólica pelo poder. A análise dos discursos republicanos mostra que a política paranaense do final do século XIX era mais um resultado de alianças e desavenças entre grupos do que fruto de posicionamentos ideológicos. Os discursos serviam, majoritariamente, como armas retóricas utilizadas para orientar o enfrentamento intra-elites, movido pelo desejo de participação, o que fez com que tivesse um caráter genérico, alicerçado na concepção do fim dos privilégios, embora sem a ampliação da cidadania. Abstract in english The crisis of the Brazilian monarchical regime was accompanied by the emergence and expansion of the republican movement at the end of the 19th century. During that period, the press not only became the stage of institutional debates but also had the role of an informal power, linked to the governme [...] nt and political party organization. It was a press that expressed opinions and created a space for partisan commentary. Newspaper columns were used to anonymously air that which could not be expressed publicly in the Legislative Assembly, the Senate or the House of Representatives, thus constituting an alternative tribune for debate. This article seeks to give voice to the different republican models that circulated within these state of Paraná newspapers, relating them to the configurations they were a part of and with the position that they held within local and national fields of power. Furthermore, it is important to recognize that the dominant republican ideas were not disseminated without resistance: rather, they were heard and combated at the local level, although efforts in this regard remained lacking in political force. Our analysis incorporates the Bourdieusian perspective according to which discourses are not only signs to be understood and decoded but also status indicators -seeking to be validated and evaluated - and forms of authority, seeking to be believed and obeyed; in both cases, object of struggles over symbolic power. Analysis of republican discourse shows that Paraná state politics of the late 19th century was more a result of alliances and tensions between groups than the fruit of clear ideological stands. Discourses served mostly as rhetorical weapons which were used to orient intra-elite conflict, moved by the desire for participation. This gave them a generic character, based on a notion of putting an end to privilege without widening citizenship rights.

  12. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Robert C. [Texas A& M University; Kamon, Teruki [Texas A& M University; Toback, David [Texas A& M University; Safonov, Alexei [Texas A& M University; Dutta, Bhaskar [Texas A& M University; Dimitri, Nanopoulos [Texas A& M University; Pope, Christopher [Texas A& M University; White, James [Texas A& M University

    2013-11-18

    Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

  13. Co-inoculation with Rhizobium and plant growth promoting rhizobacteria (PGPR for inducing salinity tolerance in mung bean under field condition of semi arid climate

    Directory of Open Access Journals (Sweden)

    Muhammad Aamir

    2013-04-01

    Full Text Available Salinity stress severely affects the growth, nodulation and yield of mung bean (Vigna radiata L.. However, its growth can be improved under salinity stress by inoculation/co-inoculation with rhizobia and plant growth promoting rhizobacteria (PGPR containing 1-Aminocyclopropane-1-carboxylic acid (ACC deaminase enzyme. ACC-deaminase containing bacteria regulate the stress induced ethylene production by hydrolyzing the ACC (immediate precursor of ethylene into ammonia and ketobutyric acid, thus improve plant growth by lowering the ethylene level. A study was conducted under salt affected field conditions where pre-isolated strains of Rhizobium and PGPR were used alone as well as in combination for mitigating the salinity stress on growth, nodulation and yield of mung bean by following the randomized complete block design (RCBD. The data were recorded and analyzed statistically to see the difference among treatments.

  14. Compatibilidade entre a inoculação de rizóbios e fungicidas aplicados em sementes de feijoeiro-comum / Compatibility between rhizobium inoculation and fungicide application in seeds of common beans

    Scientific Electronic Library Online (English)

    Maurício Rocha, Kintschev; Augusto César Pereira, Goulart; Fábio Martins, Mercante.

    2014-12-01

    Full Text Available O objetivo do presente estudo foi avaliar os efeitos do tratamento de sementes de feijoeiro com diferentes fungicidas na sobrevivência de estirpe de Rhizobium tropici (SEMIA 4077) e Rhizobium freirei (SEMIA 4080), na nodulação das plantas e na produtividade da cultura. Foram conduzidos dois ensaios [...] em substrato esterilizado, sob condições de casa de vegetação e um ensaio no campo experimental da Embrapa Agropecuária Oeste, em Dourados, MS, num Latossolo Vermelho distroférrico típico. Os fungicidas (princípios ativos) utilizados nos ensaios foram: (1) carbendazim + tiram (Produto A); (2) carbendazim + tiram (Produto B); (3) carboxin + tiram; (4) fludioxonil + metalaxil-M; (5) fludioxonil + metalaxil-M + tiabendazol; (6) fluazinam + tiofanato metílico; (7) fipronil + tiofanato metílico + piraclostrobina; (8) clorotalonil + tiofanato metílico. A sobrevivência das estirpes de R. tropici inoculadas nas sementes de feijoeiro foi afetada pela aplicação dos fungicidas, principalmente por aqueles com modo de ação de contato. Observou-se ainda, com a aplicação dos fungicidas, redução na nodulação das plantas de feijoeiro, especialmente da massa nodular, tanto nos ensaios conduzidos em substrato esterilizado, em casa de vegetação, quanto no experimento a campo, onde também observou-se redução na produtividade do feijoeiro pela aplicação da maioria dos fungicidas avaliados. Os fungicidas que mais afetaram o rendimento de grãos foram carbendazim + tiram (Produto B) e carboxin + tiram. Os produtos fipronil + tiofanato metílico + piraclostrobina, fludioxonil + metalaxil-M + tiabendazol e fludioxonil + metalaxil-M não afetaram a produtividade da cultura, embora a massa seca de nódulos tenha sido reduzida em todos os ensaios. Abstract in english The aim of this study was to evaluate the effects of treatment of common bean seeds with different fungicides on the survival of strains of Rhizobium tropici (SEMIA 4077) and Rhizobium freirei (SEMIA 4080), as well as on plant nodulation and on crop yield. Two experiments were carried out in sterili [...] zed substrate, under greenhouse conditions and in the experimental field of Embrapa Western Agriculture, in Dourados, Mato Grosso do Sul State, in a typical Oxisol. The fungicides (active ingredients) used in the experiments were: (1) carbendazim + thiram (Product A), (2) carbendazim + thiram (Product B), (3) carboxin + thiram, (4) fludioxonil + metalaxyl-M, (5) fludioxonil + metalaxyl-M + thiabendazole, (6) fluazinam + methyl thiophanate, (7) fipronil + methyl thiophanate + pyraclostrobin, (8) chlorothalonil + methyl thiophanate. The survival of R. tropici strains inoculated in bean seeds was affected by the application of fungicides, especially contact fungicides. In addition, fungicide application led to a reduction in the nodulation of bean plants, especially for nodular mass, either in assays carried out on sterilized substrate, in a greenhouse, or in the field experiment, where grain yield reduction was also noted with the use of most evaluated fungicides. The fungicides that mostly affected grain yield were carbendazim + thiram (Product B) and carboxin + thiram. The products fipronil + thiophanate methyl + pyraclostrobin, fludioxonil + metalaxyl-M + thiabendazole and fludioxonil + metalaxyl-M did not affect the crop yield, although the dry weight of nodules was reduced in all trials.

  15. Greenhouse effect gases sources and sinks (CO{sub 2}, CH{sub 4}, N{sub 2}O) in grasslands and reduction strategies. Greenhouse effect gases prairies. Final report of the second part of the project. April 2004; Sources et puits de gaz a effet de serre (CO{sub 2}, CH{sub 4}, N{sub 2}O) en prairie paturee et strategies de reduction. GES-Prairies. Rapport final de la seconde tranche du projet. Avril 2004

    Energy Technology Data Exchange (ETDEWEB)

    Soussana, J.F

    2004-04-15

    The project 'GES-Prairies' (Greenhouse Gases - Grasslands) had two main objectives: 1. To measure more accurately the fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O of French grasslands and determine the greenhouse gas (GHG) balance of these areas. 2. To calculate the net GHG emissions of cattle production farms and finally to propose and evaluate some management scenarios leading to a reduction of GHG emissions. This project deals with three different spatial scales: the field scale, the farm scale and finally, the regional scale. At the field scale, during two years, fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O were measured in a mid-mountain permanent grassland, previously managed intensively by cutting and grazing (Laqueuille, Auvergne, France). Results from the first complete year of measurements show that the extensification process (reduction of the stocking rate and stopping N fertilization) allows to stock more carbon in the ecosystem. At the farm scale, We developed a model (FARMSIM, coupled to PASIM) able to simulate the GHG balance of a livestock farm. FARMSIM has been tested with data obtained from a mixed livestock farm in Lorraine (dairy and meat production, annual average stocking rate = 1.3 LU ha{sup -1}) of 100 ha (including 76 ha of grasslands and 21 of annual crops). The results indicate a net emission of 175 t equivalent C-CO{sub 2} for this farm. If expressed per unit of product, it represents 1.34 t equivalent C-CO{sub 2} per LU and per year or 0.54 kg CO{sub 2} per kg of milk and per year. At the regional scale/. The PASIM model has been used to simulate the European grasslands with a spatial resolution of 1' (about 200 * 200 km). For each grid cell, a sensibility analysis allowed to determine the N application which correspond to 30% of the N application that would maximize the annual yield of the pasture. Simulation runs on mixed systems (combining grazing and cutting) show that almost one half of the grassland area is, on average, used for cutting. These simulations predict N{sub 2}O emission factors that are relatively stable for the different grid cells across Europe wit values ranging between 1 and 2% in cut systems and between 3 and 4% under grazing (with organic N application through faeces and urine deposition). Under cutting, the simulations predict a important annual C storage (varying between 0.5 to 6 t C ha-1 y-1). However one must consider that an important part of this storage occurs in the harvested forage. C storage in grazed grasslands (0.3 to 2 t C ha-1 y-1) is lower than in cut grasslands. The simulations indicates therefore that cut grassland could represent an important net GHG sink. In France, the amplitude of this sink could vary between 0.5 and 2 t C CO{sub 2} equivalent ha-1 y-1. The simulations combining cut and grazed grassland, in proportion to the dietary needs, show that,in France, these systems would be a net GHG sink of 2 to 3 t C CO{sub 2} equivalent ha-1 y-1. More realistic results would be obtained if the differences between farming systems were taken into account more specifically. (author)

  16. RapA2 is a calcium-binding lectin composed of two highly conserved cadherin-like domains that specifically recognize Rhizobium leguminosarum acidic exopolysaccharides.

    Science.gov (United States)

    Abdian, Patricia L; Caramelo, Julio J; Ausmees, Nora; Zorreguieta, Angeles

    2013-01-25

    In silico analyses have revealed a conserved protein domain (CHDL) widely present in bacteria that has significant structural similarity to eukaryotic cadherins. A CHDL domain was shown to be present in RapA, a protein that is involved in autoaggregation of Rhizobium cells, biofilm formation, and adhesion to plant roots as shown by us and others. Structural similarity to cadherins suggested calcium-dependent oligomerization of CHDL domains as a mechanistic basis for RapA action. Here we show by circular dichroism spectroscopy, light scattering, isothermal titration calorimetry, and other methods that RapA2 from Rhizobium leguminosarum indeed exhibits a cadherin-like ?-sheet conformation and that its proper folding and stability are dependent on the binding of one calcium ion per protein molecule. By further in silico analysis we also reveal that RapA2 consists of two CHDL domains and expand the range of CHDL-containing proteins in bacteria and archaea. However, light scattering assays at various concentrations of added calcium revealed that RapA2 formed neither homo-oligomers nor hetero-oligomers with RapB (a distinct CHDL protein), indicating that RapA2 does not mediate cellular interactions through a cadherin-like mechanism. Instead, we demonstrate that RapA2 interacts specifically with the acidic exopolysaccharides (EPSs) produced by R. leguminosarum in a calcium-dependent manner, sustaining a role of these proteins in the development of the biofilm matrix made of EPS. Because EPS binding by RapA2 can only be attributed to its two CHDL domains, we propose that RapA2 is a calcium-dependent lectin and that CHDL domains in various bacterial and archaeal proteins confer carbohydrate binding activity to these proteins. PMID:23235153

  17. Proteins Exported via the PrsD-PrsE Type I Secretion System and the Acidic Exopolysaccharide Are Involved in Biofilm Formation by Rhizobium leguminosarum

    Science.gov (United States)

    Russo, Daniela M.; Williams, Alan; Edwards, Anne; Posadas, Diana M.; Finnie, Christine; Dankert, Marcelo; Downie, J. Allan; Zorreguieta, Angeles

    2006-01-01

    The type I protein secretion system of Rhizobium leguminosarum bv. viciae encoded by the prsD and prsE genes is responsible for secretion of the exopolysaccharide (EPS)-glycanases PlyA and PlyB. The formation of a ring of biofilm on the surface of the glass in shaken cultures by both the prsD and prsE secretion mutants was greatly affected. Confocal laser scanning microscopy analysis of green-fluorescent-protein-labeled bacteria showed that during growth in minimal medium, R. leguminosarum wild type developed microcolonies, which progress to a characteristic three-dimensional biofilm structure. However, the prsD and prsE secretion mutants were able to form only an immature biofilm structure. A mutant disrupted in the EPS-glycanase plyB gene showed altered timing of biofilm formation, and its structure was atypical. A mutation in an essential gene for EPS synthesis (pssA) or deletion of several other pss genes involved in EPS synthesis completely abolished the ability of R. leguminosarum to develop a biofilm. Extracellular complementation studies of mixed bacterial cultures confirmed the role of the EPS and the modulation of the biofilm structure by the PrsD-PrsE secreted proteins. Protein analysis identified several additional proteins secreted by the PrsD-PrsE secretion system, and N-terminal sequencing revealed peptides homologous to the N termini of proteins from the Rap family (Rhizobium adhering proteins), which could have roles in cellular adhesion in R. leguminosarum. We propose a model for R. leguminosarum in which synthesis of the EPS leads the formation of a biofilm and several PrsD-PrsE secreted proteins are involved in different aspects of biofilm maturation, such as modulation of the EPS length or mediating attachment between bacteria. PMID:16740954

  18. Uso de micorrizas e rizóbio em cultivo consorciado de eucalipto e sesbânia: II - Absorção e eficiência de utilização de fósforo e frações fosfatadas Use of mycorrhizas and rhizobium in intercropping system of eucalyptus and sesbania: II - Phosphorus uptake and efficiency of use and phosphate phosphate -fractions

    Directory of Open Access Journals (Sweden)

    L. A. Rodrigues

    2003-08-01

    Full Text Available Realizou-se um experimento em casa de vegetação com o objetivo de avaliar os efeitos de fungos micorrízicos arbusculares (FMAs e rizóbio na absorção e eficiência de utilização de P e nas frações fosfatadas em mudas de Eucalyptus grandis, cultivadas em consorciação com Sesbania virgata. Os tratamentos foram: inoculação ou não com FMAs em ambas as espécies de plantas e inoculação ou não com rizóbio na S. virgata, com quatro repetições. Ambas as plantas foram cultivadas em vasos de 6 L de capacidade, durante 100 dias, quando foram colhidas. A inoculação com FMAs ou FMAs + rizóbio aumentou o conteúdo de P no eucalipto, enquanto a inoculação com rizóbio, FMAs ou FMAs + rizóbio aumentou a eficiência de utilização de P. Nas frações de P, avaliadas nas folhas de eucalipto, observou-se aumento do fósforo total solúvel em ácido (PST nos tratamentos com inoculação de rizóbio ou FMAs + rizobio. Nos tratamentos com inoculação com rizóbio, FMAs, FMAs+rizóbio ou sem inoculação, observou-se que 81, 32, 91 e 68%, respectivamente, do PST foram encontrados como fósforo orgânico (Po. Em uma avaliação conjunta das frações fosfatadas e do conteúdo de P na parte aérea do eucalipto, o que aparentemente influenciou o aumento do PST e do Po não foi o conteúdo interno de P na planta, mas, sim, a inoculação do rizóbio na sesbânia.The effects of arbuscular mycorrhizal fungi (AMF and Rhizobium on P uptake and efficiency of use, as well as on the P fractions of Eucalyptus grandis grown in an intercropping system with Sesbania virgata were evaluated under greenhouse conditions. The treatments were: with or without inoculation with AMF of both plant species and with or without inoculation with Rhizobium of S. virgata plants only, in four replications. The two plant species were grown together in pots with a volume of 6 L for 100 days. Inoculations with AMF or with AMF + Rhizobium increased the P content in Eucalyptus plants, while inoculations with Rhizobium, AMF, or with AMF + Rhizobium increased the P utilization efficiency. An increase of total acid-soluble P (PTS in the treatments inoculated with Rhizobium or AMF + Rhizobium was observed in the P fractions of the analyzed Eucalyptus plant leaves. In the inoculation treatments with Rhizobium, AMF, and AMF + Rhizobium, and the control (uninoculated 81, 32, 91, and 68%, respectively, of the PST in the leaves of Eucalyptus plants were found in organic-P (Po form. An evaluation of both the P fractions and P contents of Eucalyptus shoots suggests that the increase of PST and organic-P was caused by the inoculation of Rhizobium in sesbania plants, and not by the internal P plant content.

  19. Characterization and functional analysis of seven flagellin genes in Rhizobium leguminosarum bv. viciae. Characterization of R. leguminosarum flagellins

    Directory of Open Access Journals (Sweden)

    Tambalo Dinah D

    2010-08-01

    Full Text Available Abstract Background Rhizobium leguminosarum bv. viciae establishes symbiotic nitrogen fixing partnerships with plant species belonging to the Tribe Vicieae, which includes the genera Vicia, Lathyrus, Pisum and Lens. Motility and chemotaxis are important in the ecology of R. leguminosarum to provide a competitive advantage during the early steps of nodulation, but the mechanisms of motility and flagellar assembly remain poorly studied. This paper addresses the role of the seven flagellin genes in producing a functional flagellum. Results R. leguminosarum strains 3841 and VF39SM have seven flagellin genes (flaA, flaB, flaC, flaD, flaE, flaH, and flaG, which are transcribed separately. The predicted flagellins of 3841 are highly similar or identical to the corresponding flagellins in VF39SM. flaA, flaB, flaC, and flaD are in tandem array and are located in the main flagellar gene cluster. flaH and flaG are located outside of the flagellar/motility region while flaE is plasmid-borne. Five flagellin subunits (FlaA, FlaB, FlaC, FlaE, and FlaG are highly similar to each other, whereas FlaD and FlaH are more distantly related. All flagellins exhibit conserved amino acid residues at the N- and C-terminal ends and are variable in the central regions. Strain 3841 has 1-3 plain subpolar flagella while strain VF39SM exhibits 4-7 plain peritrichous flagella. Three flagellins (FlaA/B/C and five flagellins (FlaA/B/C/E/G were detected by mass spectrometry in the flagellar filaments of strains 3841 and VF39SM, respectively. Mutation of flaA resulted in non-motile VF39SM and extremely reduced motility in 3841. Individual mutations of flaB and flaC resulted in shorter flagellar filaments and consequently reduced swimming and swarming motility for both strains. Mutant VF39SM strains carrying individual mutations in flaD, flaE, flaH, and flaG were not significantly affected in motility and filament morphology. The flagellar filament and the motility of 3841 strains with mutations in flaD and flaG were not significantly affected while flaE and flaH mutants exhibited shortened filaments and reduced swimming motility. Conclusion The results obtained from this study demonstrate that FlaA, FlaB, and FlaC are major components of the flagellar filament while FlaD and FlaG are minor components for R. leguminosarum strains 3841 and VF39SM. We also observed differences between the two strains, wherein FlaE and FlaH appear to be minor components of the flagellar filaments in VF39SM but these flagellin subunits may play more important roles in 3841. This paper also demonstrates that the flagellins of 3841 and VF39SM are possibly glycosylated.

  20. The "missing" typical Rhizobium leguminosarum O antigen is attached to a fatty acylated glycerol in R. leguminosarum bv. trifolii 4S, a strain that also lacks the usual tetrasaccharide "core" component.

    OpenAIRE

    Cedergren, R. A.; Wang, Y.; Hollingsworth, R. I.

    1996-01-01

    Rhizobium leguminosarum bv. trifolii 4S has a lipopolysaccharide O antigen that lacks galactose and many of the typical glycosyl components found in related strains. Here, we show that it also lacks the typical core tetrasaccharide but synthesizes an alternative glycolipid that contains galactose and the typical O-antigen glycosyl components, suggesting that in this strain, the O antigen is transferred to an alternative lipid acceptor.