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Determinants of nodulation competitiveness in Rhizobium etli. Final report for period September 30, 1996--September 29, 1999  

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Nitrogen is a major limiting nutrient in crop production. Chemical fertilizers, which are used extensively to meet crop nitrogen requirements, contribute to the high energy inputs of modern agriculture and cause human health and environmental problems. Legumes and their bacterial associates have long been used in crop rotations to replenish soil nitrogen, but effective and reliable biological nitrogen fixation for beans is prevented by the lack of nodulation competitiveness of many Rhizobium strains used as inoculants. The result is that the inoculant strains will not occupy the host's nodules and no benefit will be derived from inoculation. Many indigenous soil strains of Rhizobium etli bv. phaseoli, the symbiont of bean, nodulate but fix little or no nitrogen, and therefore the nodulation competitiveness problem is significant for achieving maximum nitrogen benefit from bean crops. This project was directed toward developing an understanding of the basis of nodulation competitiveness.

Handelsman, Jo

2000-01-04

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Rhizobium etli taxonomy revised with novel genomic data and analyses.  

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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

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

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

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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...

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

2005-01-01

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

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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.

los Santos Alejandro

2011-04-01

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Isolation and characterization of Rhizobium etli mutants altered in degradation of asparagine.  

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Rhizobium etli mutants unable to grow on asparagine as the nitrogen and carbon source were isolated. Two kinds of mutants were obtained: AHZ1, with very low levels of aspartase activity, and AHZ7, with low levels of asparaginase and very low levels of aspartase compared to the wild-type strain. R. etli had two asparaginases differentiated by their thermostabilities, electrophoretic mobilities, and modes of regulation. The AHZ mutants nodulated as did the wild-type strain and had nitrogenase levels similar to that of the wild-type strain. PMID:9068657

Huerta-Zepeda, A; Ortuno, L; Du Pont, G; Duran, S; Lloret, A; Merchant-Larios, H; Calderon, J

1997-01-01

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A cysG mutant strain of Rhizobium etli pleiotropically defective in sulfate and nitrate assimilation.  

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By its inability to grow on sulfate as the sole sulfur source, a mutant strain (CTNUX8) of Rhizobium etli carrying Tn5 was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a cysG (siroheme synthetase)-homologous gene. By RNase protection assays, it was established that the cysG-like gene had a basal level of expression in thiosulfate- or cysteine-grown cells, which was induced when sulfate or methionine was used. Unlike its wild-type parent (strain CE3), the muta...

Tate, R.; Riccio, A.; Iaccarino, M.; Patriarca, E. J.

1997-01-01

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

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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.

González Víctor

2011-10-01

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A proteomic approach towards the analysis of salt tolerance in Rhizobium etli and Sinorhizobium meliloti strains.  

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Soluble proteins from the salt-tolerant Rhizobium etli strain EBRI 26 were separated by two-dimensional (2D) gel electrophoresis and visualised by Commassie staining. Six proteins are highly expressed after induction by 4% NaCl compared to the non-salt-stressed cells. These proteins have pI between 5 and 5.5 and masses of approximately 22, 25, 40, 65, 70, and 95 kDa. These proteins were analysed by Matrix-assisted laser adsorption ionization time of flight (MALDI-TOF) after digestion with trypsin. Despite having very good peptide mass fingerprint data, these proteins could not be identified, because the genome sequence of R. etli is not yet published. In a second approach, soluble proteins from salt-induced or non-salt-induced cultures from R. etli strain EBRI 26 were separately labelled with different fluorescent cyano-dyes prior to 2D difference in gel electrophoresis. Results revealed that 49 proteins are differentially expressed after the addition of sodium chloride. Fourteen proteins are overexpressed and 35 were downregulated. The genome of Sinorhizobium meliloti, a closely related species to R. etli, has been published. Similar experiments using Sinorhizobium meliloti strain 2011 identified four overexpressed and six downregulated proteins. Among the overexpressed protein is a carboxynospermidin decarboxylase, which plays an important role in the biosynthesis of spermidin (polyamine). The enzyme catalase is among the downregulated proteins. These proteins may play a role in salt tolerance. PMID:16604415

Shamseldin, Abdelaal; Nyalwidhe, Julius; Werner, Dietrich

2006-05-01

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Interaction Between the Biotin Carboxyl Carrier Domain and the Biotin Carboxylase Domain in Pyruvate Carboxylase from Rhizobium etli  

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Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To effect catalysis, the tethered biotin of PC must gain access to active sites in both the biotin carboxylase domain and the carboxyl transferase domain. Previous studies have demonstrated that a mutation of threonine 882 to alanine in PC from Rhizobium etli renders the carboxyl transferase domain inactive and favors the positioning of bioti...

Menefee, Ann L.; Zeczycki, Tonya N.; Kumar, Sudhanshu; Attwood, Paul V.; Wallace, John C.; Cleland, W. Wallace

2011-01-01

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

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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.

Mendoza-Hernández Guillermo

2010-10-01

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Cloning and characterization of a thermostable xylitol dehydrogenase from Rhizobium etli CFN42  

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An NAD+-dependent xylitol dehydrogenase from Rhizobium etli CFN42 (ReXDH) was cloned and overexpressed in Escherichia coli. The DNA sequence analysis revealed an open reading frame of 1,044 bp, capable of encoding a polypeptide of 347 amino acid residues with a calculated molecular mass of 35,858 Da. The ReXDH protein was purified as an active soluble form using GST affinity chromatography. The molecular mass of the purified enzyme was estimated to be ?34 kDa by sodium dodecyl sulfate–polyacrylamide gel and ?135 kDa with gel filtration chromatography, suggesting that the enzyme is a homotetramer. Among various polyols, xylitol was the preferred substrate of ReXDH with a Km=17.9 mM and kcat/Km=0.5 mM?1 s?1 for xylitol. The enzyme had an optimal pH and temperature of 9.5 and 70 °C, respectively. Heat inactivation studies revealed a half life of the ReXDH at 40 °C of 120 min and a half denaturation temperature (T1/2) of 53.1 °C. ReXDH showed the highest optimum temperature and thermal stability among the known XDHs. Homology modeling and sequence analysis of ReXDH shed light on the factors contributing to the high thermostability of ReXDH. Although XDHs have been characterized from several other sources, ReXDH is distinguished from other XDHs by its high thermostability

Tiwari, Manish Kumar; Lee, Hee-Jung

2010-01-01

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

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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...

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

1996-01-01

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

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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.

Beullens Serge

2008-12-01

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

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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 t1/2 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 Km of ReXDH was slightly altered from 17.9 to only 19.2 mM byimmobilization. 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 gh-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.

Zhang, Ye-Wang; Tiwari, Manish Kumar

2011-01-01

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Mechanisms of Inhibition of Rhizobium etli Pyruvate Carboxylase by l-Aspartate.  

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l-Aspartate is a regulatory feedback inhibitor of the biotin-dependent enzyme pyruvate carboxylase in response to increased levels of tricarboxylic acid cycle intermediates. Detailed studies of l-aspartate inhibition of pyruvate carboxylase have been mainly confined to eukaryotic microbial enzymes, and aspects of its mode of action remain unclear. Here we examine its inhibition of the bacterial enzyme Rhizobium etli pyruvate carboxylase. Kinetic studies demonstrated that l-aspartate binds to the enzyme cooperatively and inhibits the enzyme competitively with respect to acetyl-CoA. l-Aspartate also inhibits activation of the enzyme by MgTNP-ATP. The action of l-aspartate was not confined to inhibition of acetyl-CoA binding, because the acetyl-CoA-independent activity of the enzyme was also inhibited by increasing concentrations of l-aspartate. This inhibition of acetyl-CoA-independent activity was demonstrated to be focused in the biotin carboxylation domain of the enzyme, and it had no effect on the oxamate-induced oxaloacetate decarboxylation reaction that occurs in the carboxyl transferase domain. l-Aspartate was shown to competitively inhibit bicarbonate-dependent MgATP cleavage with respect to MgATP but also probably inhibits carboxybiotin formation and/or translocation of the carboxybiotin to the site of pyruvate carboxylation. Unlike acetyl-CoA, l-aspartate has no effect on the coupling between MgATP cleavage and oxaloacetate formation. The results suggest that the three allosteric effector sites (acetyl-CoA, MgTNP-ATP, and l-aspartate) are spatially distinct but connected by a network of allosteric interactions. PMID:25330457

Sirithanakorn, Chaiyos; Adina-Zada, Abdussalam; Wallace, John C; Jitrapakdee, Sarawut; Attwood, Paul V

2014-11-18

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

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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 insertion of an Omega-Km interposon within the PHB synthase structural gene (phaC). The identification and sequence of the R. etli phaC gene are also reported here. Physiological studies showed that the PHB-negative mutant strain was unable to synthesize PHB and excreted more lactate, acetate, pyruvate, beta-hydroxybutyrate, fumarate, and malate than the wild-type strain. The NAD+/NADH ratio in the mutant strain was lower than that in the parent strain. The oxidative capacity of the PHB-negative mutant was reduced. Accordingly, the ability to grow in minimal medium supplemented with glucose or pyruvate was severely diminished in the mutant strain. We propose that in free life PHB synthesis sequesters reductive power, allowing the tricarboxylic acid cycle to proceed under conditions in which oxygen is a limiting factor. In symbiosis with Phaseolus vulgaris, the PHB-negative mutant induced nodules that prolonged the capacity to fix nitrogen. PMID:8626293

Cevallos, M A; Encarnación, S; Leija, A; Mora, Y; Mora, J

1996-03-01

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Isolation, chemical structures and biological activity of the lipo-chitin oligosaccharide nodulation signals from Rhizobium etli.  

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Rhizobium etli is a microsymbiont of plants of the genus Phaseolus. Using mass spectrometry we have identified the lipo-chitin oligosaccharides (LCOs) that are produced by R. etli strain CE3. They are N-acetylglucosamine pentasaccharides of which the non-reducing residue is N-methylated and N-acylated with cis-vaccenic acid (C18:1) or stearic acid (C18:0) and carries a carbamoyl group at C4. The reducing residue is substituted at the C6 position with O-acetylfucose. Analysis of their biological activity on the host plant Phaseolus vulgaris shows that these LCOs can elicit the formation of nodule primordia which develop to the stage where vascular bundles are formed. The formation of complete nodule structures, including an organized vascular tissue, is never observed. Considering the very close resemblance of the R. etli LCO structures to those of R. loti (I. M. López-Lara, J. D. J. van den Berg, J. E. Thomas Oates, J. Glushka, B. J. J. Lugtenberg, H. P. Spaink, Mol Microbiol 15: 627-638, 1995) we tested the ability of R. etli strains to nodulate various Lotus species and of R. loti to nodulate P. vulgaris. The results show that R. etli is indeed able to nodulate Lotus plants. However, several Lotus species are only nodulated when an additional flavonoid independent transcription activator (FITA) nodD gene is provided. Phaseolus plants can also be nodulated by R. loti bacteria, but only when the bacteria contain a FITA nodD gene. Apparently, the type of nod gene inducers secreted by the plants is the major basis for the separation of Phaseolus and Lotus into different cross inoculation groups. PMID:8534845

Cárdenas, L; Domínguez, J; Quinto, C; López-Lara, I M; Lugtenberg, B J; Spaink, H P; Rademaker, G J; Haverkamp, J; Thomas-Oates, J E

1995-11-01

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A type III polyketide synthase from Rhizobium etli condenses malonyl CoAs to a heptaketide pyrone with unusually high catalytic efficiency  

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A novel type III polyketide synthase (RePKS) from Rhizobium etli produced a heptaketide pyrone using acetyl-CoA and six molecules of malonyl-CoA. Its catalytic efficiency (k(cat)/K-m = 5230 mM(-1) min(-1)) for malonyl CoA was found to be the highest ever reported. Molecular dynamics studies revealed the unique features of RePKS.

Jeya, Marimuthu; Kim, Tae-Su

2012-01-01

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Prevalence of the Rhizobium etli-like allele in genes coding for 16S rRNA among the indigenous rhizobial populations found associated with wild beans from the Southern Andes in Argentina.  

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A collection of rhizobial isolates from nodules of wild beans, Phaseolus vulgaris var. aborigineus, found growing in virgin lands in 17 geographically separate sites in northwest Argentina was characterized on the basis of host range, growth, hybridization to a nifH probe, analysis of genes coding for 16S rRNA (16S rDNA), DNA fingerprinting, and plasmid profiles. Nodules in field-collected wild bean plants were largely dominated by rhizobia carrying the 16S rDNA allele of Rhizobium etli. A similar prevalence of the R. etli allele was observed among rhizobia trapped from nearby soil. Intragroup diversity of wild bean isolates with either R. etli-like or Rhizobium leguminosarum bv. phaseoli-like alleles was generally found across northwest Argentina. The predominance of the R. etli allele suggests that in this center of origin of P. vulgaris the coevolution of Rhizobium spp. and primitive beans has resulted in this preferential symbiotic association. PMID:9726909

Aguilar, O M; López, M V; Riccillo, P M; González, R A; Pagano, M; Grasso, D H; Pühler, A; Favelukes, G

1998-09-01

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Insight into the carboxyl transferase domain mechanism of pyruvate carboxylase from Rhizobium etli  

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The effects of mutations in the active site of the carboxyl transferase domain of R. etli pyruvate carboxylase have been determined for the forward reaction to form oxaloacetate, the reverse reaction to form MgATP, the oxamate-induced decarboxylation of oxaloacetate, the phosphorylation of MgADP by carbamoyl phosphate and the bicarbonate-dependent ATPase reaction. Additional studies with these mutants examined the effect of pyruvate and oxamate on the reactions of the biotin carboxylase domai...

Zeczycki, Tonya N.; Maurice, Martin St; Jitrapakdee, Sarawut; Wallace, John C.; Attwood, Paul V.; Cleland, W. Wallace

2009-01-01

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

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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 organization. In contrast, strains belonging to other bean-nodulating species seem to have acquired only the pSym plasmid from R. etli. PMID:11976134

Brom, Susana; Girard, Lourdes; Garcia-de los Santos, Alejandro; Sanjuan-Pinilla, Julio M.; Olivares, Jose; Sanjuan, Juan

2002-01-01

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

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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 under these conditions. The R. etli rsh gene was found to restore (p)ppGpp accumulation to a ?relA ?spoT mutant of Escherichia coli. The R. etli Rsh protein consists of 744 amino acids, and the Tn5 insertion in LM01 results in the synthesis of a truncated protein of 329 amino acids; complementation experiments indicate that this truncated protein is still capable of (p)ppGpp hydrolysis. A second rsh mutant of R. etli, strain AC1, was constructed by inserting an ? element at the beginning of the rsh gene, resulting in a null allele. Both AC1 and LM01 were affected in Nod factor production, which was constitutive in both strains, and in nodulation; nodules produced by the rsh mutants in Phaseolus vulgaris were smaller than those produced by the wild-type strain and did not fix nitrogen. In addition, electron microscopy revealed that the mutant bacteroids lacked poly-?-hydroxybutyrate granules. These results indicate a central role for the stringent response in symbiosis. PMID:16030199

Calderon-Flores, Arturo; Du Pont, Gisela; Huerta-Saquero, Alejandro; Merchant-Larios, Horacio; Servin-Gonzalez, Luis; Duran, Socorro

2005-01-01

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

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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

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

2012-11-01

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Visualization of highly dynamic F-actin plus ends in growing phaseolus vulgaris root hair cells and their responses to Rhizobium etli nod factors.  

Science.gov (United States)

Legume plants secrete signaling molecules called flavonoids into the rhizosphere. These molecules activate the transcription of rhizobial nod genes, which encode proteins involved in the synthesis of signaling compounds named Nod factors (NFs). NFs, in turn, trigger changes in plant gene expression, cortical cell dedifferentiation and mitosis, depolarization of the root hair cell membrane potential and rearrangement of the actin cytoskeleton. Actin polymerization plays an important role in apical growth in hyphae and pollen tubes. Using sublethal concentrations of fluorescently labeled cytochalasin D (Cyt-Fl), we visualized the distribution of filamentous actin (F-actin) plus ends in living Phaseolus vulgaris and Arabidopsis root hairs during apical growth. We demonstrated that Cyt-Fl specifically labeled the newly available plus ends of actin microfilaments, which probably represent sites of polymerization. The addition of unlabeled competing cytochalasin reduced the signal, suggesting that the labeled and unlabeled forms of the drug bind to the same site on F-actin. Exposure to Rhizobium etli NFs resulted in a rapid increase in the number of F-actin plus ends in P. vulgaris root hairs and in the re-localization of F-actin plus ends to infection thread initiation sites. These data suggest that NFs promote the formation of F-actin plus ends, which results in actin cytoskeleton rearrangements that facilitate infection thread formation. PMID:24399235

Zepeda, Isaac; Sánchez-López, Rosana; Kunkel, Joseph G; Bañuelos, Luis A; Hernández-Barrera, Alejandra; Sánchez, Federico; Quinto, Carmen; Cárdenas, Luis

2014-03-01

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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)

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

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

2013-05-01

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

Science.gov (United States)

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 characterized transfer region of the nonsymbiotic, self-transmissible plasmid pRetCFN42a (C. Tun-Garrido, P. Bustos, V. González, and S. Brom, J. Bacteriol. 185:1681-1692, 2003), whereas the second mob region belongs to the symbiotic plasmid pRetCFN42d. The new transfer region identified contains a putative oriT and a typical conjugative (tra) gene cluster organization. Although pRetCFN42d had not previously been shown to be self-transmissible, mobilization of cosmids containing this tra region required the presence of a wild-type pRetCFN42d in the donor cell; the presence of multiple copies of this mob region in CFN42 also promoted conjugal transfer of the Sym plasmid pRetCFN42d. The overexpression of a small open reading frame, named yp028, located downstream of the putative relaxase gene traA, appeared to be responsible for promoting the conjugal transfer of the R. etli pSym under laboratory conditions. This yp028-dependent conjugal transfer required a wild-type pRetCFN42d traA gene. Our results suggest for the first time that the R. etli symbiotic plasmid is self-transmissible and that its transfer is subject to regulation. In wild-type CFN42, pRetCFN42d tra gene expression appears to be insufficient to promote plasmid transfer under standard laboratory conditions; gene yp028 may play some role in the activation of conjugal transfer in response to as-yet-unknown environmental conditions. PMID:15317780

Perez-Mendoza, Daniel; Dominguez-Ferreras, Ana; Munoz, Socorro; Soto, Maria Jose; Olivares, Jose; Brom, Susana; Girard, Lourdes; Herrera-Cervera, Jose A.; Sanjuan, Juan

2004-01-01

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Prevalence of the Rhizobium etli-Like Allele in Genes Coding for 16S rRNA among the Indigenous Rhizobial Populations Found Associated with Wild Beans from the Southern Andes in Argentina  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A collection of rhizobial isolates from nodules of wild beans, Phaseolus vulgaris var. aborigineus, found growing in virgin lands in 17 geographically separate sites in northwest Argentina was characterized on the basis of host range, growth, hybridization to a nifH probe, analysis of genes coding for 16S rRNA (16S rDNA), DNA fingerprinting, and plasmid profiles. Nodules in field-collected wild bean plants were largely dominated by rhizobia carrying the 16S rDNA allele of Rhizobium etli. A si...

Aguilar, O. Mario; Lo?pez, Mari?a Vero?nica; Riccillo, Pablo M.; Gonza?lez, Ramo?n A.; Pagano, Marcela; Grasso, Daniel H.; Pu?hler, Alfred; Favelukes, Gabriel

1998-01-01

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Effets de la double symbiose Rhizobium-Glomus spp. sur la croissance de Leucaena leucocephala (Lam. de Wit en pépinière, et dix mois après transplantation au Zaïre  

Directory of Open Access Journals (Sweden)

Full Text Available Effects of dual inoculation with Rhizobium and Glomus spp. on the growth of Leucaena leucocephala (Lam. de Wit in the nursery, and ten months after outplanting in Zaire. This work underlines the utility to inoculate in the nursery Leucaena leucocephala (Lam. de Wit, with efficient strains of Rhizobium and endomycorrhizal fungi, in order to ensure good initial plant growth after outplanting. In general, soil fumigation in the nursery allowed growth enhancement of control plants and the best effect of biofertilizers was obtained in the nursery and ten months after outplanting. Glomus vesiculiferum (Thaxter Gerdemann and Trappe associated or not with Rhizobium TAL 1145 likely produced the same effect by using natural soil in the nursery.

Bulakali, B.

1992-01-01

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Effets de la fertilisation azotée, de l'inoculation par Rhizobium sp. et du régime des pluies sur la production de la biomasse et la teneur en azote du pois chiche  

Directory of Open Access Journals (Sweden)

Full Text Available Effect of nitrogen fertilization, inoculation with Rhizobium sp. and precipitation on the biomass production and nitrogen content of chickpea. Water availability and soil fertility (especially soil N content are the major factors affecting chickpea yield in Mediterranean regions, characterized by low rainfall, poorly distributed and rapid mineralization of organic matter. In order to study the effect of N-fertilization and inoculation with Rhizobium on chickpea biomass production and N-content, field experiment were carried out at two stations of INRAT in northern Tunisia during two consecutive years, 2000-2001 and 2001-2002. Results showed that N-fertilization significantly increased shoot biomass and N-content while decreasing nodule mass. Inoculation with both the two Rhizobium strains resulted in nodule mass increase but the shoot N-content was not significantly affected. Regardless of the stations and treatments, rainfall decrease between the two years of the experiment significantly reduced shoot and root biomass while improving nodulation, especially at Oued Beja. However, the nodule developed under water deficit conditions was correlated with a very high decrease of the nitrogen fixed. Nevertheless, the mineral nitrogen apply in soil improved the N-content of aerial parts in the two stations, especially in waterless season.

Lachaâl M.

2009-01-01

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Rhizobial 16S rRNA and dnaK Genes: Mosaicism and the Uncertain Phylogenetic Placement of Rhizobium galegae  

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The phylogenetic relatedness among 12 agriculturally important species in the order Rhizobiales was estimated by comparative 16S rRNA and dnaK sequence analyses. Two groups of related species were identified by neighbor-joining and maximum-parsimony analysis. One group consisted of Mesorhizobium loti and Mesorhizobium ciceri, and the other group consisted of Agrobacterium rhizogenes, Rhizobium tropici, Rhizobium etli, and Rhizobium leguminosarum. Although bootstrap support for the placement o...

Eardly, B. D.; Nour, S. M.; Berkum, P.; Selander, R. K.

2005-01-01

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Diversity of rhizobia from nodules of the leguminous tree Gliricidia sepium, a natural host of Rhizobium tropici.  

Science.gov (United States)

The Rhizobium species that nodulate the legume tree Gliricidia sepium were analyzed by phenotypic characteristics (including nodule formation in different hosts), PCR-RFLP patterns and sequences of 16S rRNA genes, multilocus enzyme electrophoresis, and plasmid patterns. Strains of Rhizobium tropici type A and B, Sinorhizobium spp., and Rhizobium etli bv. phaseoli were encountered in G. sepium nodules and their presence depended on the site sampled. PMID:12115061

Acosta-Durán, Carlos; Martínez-Romero, Esperanza

2002-08-01

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Genome-wide detection of predicted non-coding RNAs in Rhizobium etli expressed during free-living and host-associated growth using a high-resolution tiling array  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Non-coding RNAs (ncRNAs play a crucial role in the intricate regulation of bacterial gene expression, allowing bacteria to quickly adapt to changing environments. In the past few years, a growing number of regulatory RNA elements have been predicted by computational methods, mostly in well-studied ?-proteobacteria but lately in several ?-proteobacteria as well. Here, we have compared an extensive compilation of these non-coding RNA predictions to intergenic expression data of a whole-genome high-resolution tiling array in the soil-dwelling ?-proteobacterium Rhizobium etli. Results Expression of 89 candidate ncRNAs was detected, both on the chromosome and on the six megaplasmids encompassing the R. etli genome. Of these, 11 correspond to functionally well characterized ncRNAs, 12 were previously identified in other ?-proteobacteria but are as yet uncharacterized and 66 were computationally predicted earlier but had not been experimentally identified and were therefore classified as novel ncRNAs. The latter comprise 17 putative sRNAs and 49 putative cis-regulatory ncRNAs. A selection of these candidate ncRNAs was validated by RT-qPCR, Northern blotting and 5' RACE, confirming the existence of 4 ncRNAs. Interestingly, individual transcript levels of numerous ncRNAs varied during free-living growth and during interaction with the eukaryotic host plant, pointing to possible ncRNA-dependent regulation of these specialized processes. Conclusions Our data support the practical value of previous ncRNA prediction algorithms and significantly expand the list of candidate ncRNAs encoded in the intergenic regions of R. etli and, by extension, of ?-proteobacteria. Moreover, we show high-resolution tiling arrays to be suitable tools for studying intergenic ncRNA transcription profiles across the genome. The differential expression levels of some of these ncRNAs may indicate a role in adaptation to changing environmental conditions.

Thijs Inge M

2010-01-01

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

Directory of Open Access Journals (Sweden)

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.

Simina Neo

2012-05-01

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

Science.gov (United States)

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

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

2013-09-01

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Phylogenetic relationships and host range of Rhizobium spp. that nodulate Phaseolus vulgaris L.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We determined the nucleotide sequences of 16S rRNA gene segments from five Rhizobium strains that have been isolated from tropical legume species. All share the capacity to nodulate Phaseolus vulgaris L., the common bean. Phylogenetic analysis confirmed that these strains are of two different chromosomal lineages. We defined the host ranges of two strains of Rhizobium etli and three strains of R. tropici, comparing them with those of the two most divergently related new strains. Twenty-two of...

Hernandez-lucas, I.; Segovia, L.; Martinez-romero, E.; Pueppke, S. G.

1995-01-01

36

Physiology of the Rhizobium-legume association  

International Nuclear Information System (INIS)

Rhizobium deoxyribonucleic acid has been detected within Vicia faba root cells by in situ hybridization and autoradiography after exposure of root apexes to Rhizobium viable cells. Reannealed regions are localized in the cortex cells; the presence of bacterial DNA is specific for the root tissue; labelled regions were not detectable within apexes exposed to non-nodulating strains or to bacteria other than Rhizobium; Rhizobium DNA was not detectable in tissues of plants other than its leguminous host

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Rhizobium gone native: unexpected plasmid stability of indigenous Rhizobium leguminosarum.  

Science.gov (United States)

Lateral transfer of bacterial plasmids is thought to play an important role in microbial evolution and population dynamics. However, this assumption is based primarily on investigations of medically or agriculturally important bacterial species. To explore the role of lateral transfer in the evolution of bacterial systems not under intensive, human-mediated selection, we examined the association of genotypes at plasmid-encoded and chromosomal loci of native Rhizobium, the nitrogen-fixing symbiont of legumes. To this end, Rhizobium leguminosarum strains nodulating sympatric species of native Trifolium were characterized genetically at plasmid-encoded symbiotic (sym) regions (nodulation AB and nodulation CIJT loci) and a repeated chromosomal locus not involved in the symbiosis with legumes. Restriction fragment length polymorphism analysis was used to distinguish genetic groups at plasmid and chromosomal loci. The correlation between major sym and chromosomal genotypes and the distribution of genotypes across host plant species and sampling location were determined using chi2 analysis. In contrast to findings of previous studies, a strict association existed between major sym plasmid and chromosomal genetic groups, suggesting a lack of successful sym plasmid transfer between major Rhizobium chromosomal types. These data indicate that previous observations of sym plasmid transfer in agricultural settings may seriously overestimate the rates of successful conjugation in systems not impacted by human activities. In addition, a nonrandom distribution of Rhizobium genotypes across host plant species and sampling site demonstrates the importance of both factors in shaping Rhizobium population dynamics. PMID:9144264

Wernegreen, J J; Harding, E E; Riley, M A

1997-05-13

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Denitrification by Rhizobium meliloti  

Energy Technology Data Exchange (ETDEWEB)

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

Rosen, A.

1996-10-01

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

Science.gov (United States)

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

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

2012-11-01

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Succinate transport in Rhizobium leguminosarum.  

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The transport of succinate was studied in an effective streptomycin-resistant strain of Rhizobium leguminosarum. High levels of succinate transport occurred when cells were grown on succinate, fumarate, or malate, whereas low activity was found when cells were grown on glucose, sucrose, arabinose, or pyruvate as the sole carbon source. Because of the rapid metabolism of succinate after transport into the cells, a succinate dehydrogenase-deficient mutant was isolated in which intracellular suc...

Finan, T. M.; Wood, J. M.; Jordan, D. C.

1981-01-01

 
 
 
 
41

Peritonitis due to Rhizobium radiobacter  

Directory of Open Access Journals (Sweden)

Full Text Available Rhizobium radiobacter (Agrobacterium radiobacter is an aerobicGram-negative rod belonging to Agrobacterium genus, a groupof phytopathogenic bacteria present in the soil that has beenimplicated in human opportunistic infections. We report a clinicalcase of bacterial peritonitis in a 5-year-old child with chronic renaldisease in peritoneal dialysis, who had a history of direct soilcontact identified. The infection was treated with ceftazidime andpiperaciline+tazobactam without relapses or the need to remove theperitoneal dialysis catheter.

Raquel Marta

2011-09-01

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En route vers la nano stabilisation de CLIC faisceau principale et focalisation finale  

CERN Document Server

Pour atteindre la luminosité voulue de CLIC, la taille transversale du faisceau doit être de l?ordre du nanomètre. Ceci nécessite une stabilité vibratoire des quadripôles du faisceau principal de 1 nm et même 0.1 nm pour les doublets de la focalisation finale. La nano technologie et la nano stabilisation sont des activités qui évoluent rapidement dans l?industrie et centres de recherche pour des applications très variées comme l?électronique, l?optique, la chimie voire la médecine. Cette présentation décrit les avancées techniques nécessaires pour atteindre l?objectif de CLIC et les projets et collaborations R&D prévus pour démontrer la faisabilité de la nano stabilisation de CLIC en 2010.

Artoos, K; Guinchard, M; Hauviller, Claude; Lackner, F; CERN. Geneva. TS Department

2008-01-01

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Melanin production by Rhizobium strains.  

Science.gov (United States)

Different Rhizobium and Bradyrhizobium strains were screened for their ability to produce melanin. Pigment producers (Mel) were found among strains of R. leguminosarum biovars viceae, trifolii, and phaseoli, R. meliloti, and R. fredii; none of 19 Bradyrhizobium strains examined gave a positive response. Melanin production and nod genes were plasmid borne in R. leguminosarum biovar trifolii RS24. In R. leguminosarum biovar phaseoli CFN42 and R. meliloti GR015, mel genes were located in the respective symbiotic plasmids. In R. fredii USDA 205, melanin production correlated with the presence of its smallest indigenous plasmid. PMID:16347690

Cubo, M T; Buendia-Claveria, A M; Beringer, J E; Ruiz-Sainz, J E

1988-07-01

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Reclassification of Rhizobium tropici type A strains as Rhizobium leucaenae sp. nov.  

Science.gov (United States)

Rhizobium tropici is a well-studied legume symbiont characterized by high genetic stability of the symbiotic plasmid and tolerance to tropical environmental stresses such as high temperature and low soil pH. However, high phenetic and genetic variabilities among R. tropici strains have been largely reported, with two subgroups, designated type A and B, already defined within the species. A polyphasic study comprising multilocus sequence analysis, phenotypic and genotypic characterizations, including DNA-DNA hybridization, strongly supported the reclassification of R. tropici type A strains as a novel species. Type A strains formed a well-differentiated clade that grouped with R. tropici, Rhizobium multihospitium, Rhizobium miluonense, Rhizobium lusitanum and Rhizobium rhizogenes in the phylogenies of the 16S rRNA, recA, gltA, rpoA, glnII and rpoB genes. Several phenotypic traits differentiated type A strains from all related taxa. The novel species, for which the name Rhizobium leucaenae sp. nov. is proposed, is a broad host range rhizobium being able to establish effective root-nodule symbioses with Leucaena leucocephala, Leucaena esculenta, common beans (Phaseolus vulgaris) and Gliricidia sepium. Strain CFN 299(T) (?=?USDA 9039(T)?=?LMG 9517(T)?=?CECT 4844(T)?=?JCM 21088(T)?=?IAM 14230(T)?=?SEMIA 4083(T)?=?CENA 183(T)?=?UMR1026(T)?=?CNPSo 141(T)) is designated the type strain of Rhizobium leucaenae sp. nov. PMID:21742822

Ribeiro, Renan Augusto; Rogel, Marco A; López-López, Aline; Ormeño-Orrillo, Ernesto; Barcellos, Fernando Gomes; Martínez, Julio; Thompson, Fabiano Lopes; Martínez-Romero, Esperanza; Hungria, Mariangela

2012-05-01

45

Processing and final destinations of residual sludges; Traitements et destinations finales des boues residuaires  

Energy Technology Data Exchange (ETDEWEB)

Most purification processes applied to urban and industrial residual effluents of biological or physico-chemical origin lead to a concentration of pollutants in the form of sludges or aqueous suspensions. These sludges represent voluminous wastes (95 to 99% of water content) and contain fermentescible organic matters and/or toxic compounds. Thus, the processing of these wastes is a difficult task which requires important investment and exploitation costs. In order to rationally solve this problem, a characterization of the ultimate waste and a proper selection of the processing file is needed. This paper deals with the characterization of sludges with an attempt of a general classification of wastes generated by the purification of urban and industrial residual waters. It examines todays processing possibilities taking into account their technical and economical aspects: 1 - characterization of residual wastes: origin, nature and composition, general physical and chemical characterization, main characteristics of the physical state, structural characterization and general classification; 2 - glimpse on the processing files and final destinations: methods of problem approach, processing goals; 3 - stabilization processes: chemical stabilization, aerobic digestion, anaerobic digestion; 4 - thickening and concentration processes (gravity and dynamical); 5 - conditioning and dehydration: dehydration techniques, conditioning processes, mechanical dehydration (filtering, centrifugation); 6 - final destinations: general considerations and regulations, agricultural valorization and recycling, disposal, incineration. (J.S.)

Boeglin, J.C. [Institut de Recherches Hydrologiques, IRH-environnement, 54 - Nancy (France); Institut de Promotion Industrielle, IPI- environnement indistriel, 68 - Colmar (France)

2000-09-01

46

Le Traversant à Mailhac (Aude) : un établissement de plaine du Bronze final IIIb et du premier âge du Fer  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Les fouilles menées entre 1997 et 2000 sur le site du Traversant à Mailhac (Aude) ont permis de mieux caractériser la nature de l'occupation de ce secteur d'habitat sis au pied de l'oppidum du Cayla, et déjà reconnu en leur temps par Odette et Jean Taffanel. Confrontés aux données issues des fouilles anciennes, les résultats obtenus permettent de restituer un modèle d'évolution de l'habitat entre le Bronze Final IIIb et le début du premier page du Fer. Ce schéma laisse entrevoir ?...

Gailledrat, Eric; Boisson, Hugues; Poupet, Pierre

2007-01-01

47

Congo Red Absorption by Rhizobium leguminosarum  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Kneen, Barbara E.; Larue, Thomas A.

1983-01-01

48

Phylogenetic relationships and host range of Rhizobium spp. that nodulate Phaseolus vulgaris L.  

Science.gov (United States)

We determined the nucleotide sequences of 16S rRNA gene segments from five Rhizobium strains that have been isolated from tropical legume species. All share the capacity to nodulate Phaseolus vulgaris L., the common bean. Phylogenetic analysis confirmed that these strains are of two different chromosomal lineages. We defined the host ranges of two strains of Rhizobium etli and three strains of R. tropici, comparing them with those of the two most divergently related new strains. Twenty-two of the 43 tested legume species were nodulated by three or more of these strains. All seven strains have broad host ranges that include woody species such as Albizia lebbeck, Gliricidia maculata, and Leucaena leucocephala. PMID:7618891

Hernandez-Lucas, I; Segovia, L; Martinez-Romero, E; Pueppke, S G

1995-07-01

49

Physiological role of calcium in legume-rhizobium symbiosis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-oxid...

Vasil’eva G.G.; Ischenko A.A.; Glyan’ko A.K.

2011-01-01

50

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

1981-01-01

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Identification and manipulation of Rhizobium phytohormone genes  

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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.

Ditta, G.S.

1988-06-27

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Effectiveness of Rhizobium Under Salinity Stress  

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Full Text Available This research work was conducted to evaluate the efficacy of Rhizobium trifolii in enhancing the salt tolerance of Trifolium alexandrinum (Berseem or Egyptian clover, protein value of fodder and nitrogen fixation in the soil. Three salinity levels (8,12, 16 dS m-1 were developed in a loamy soil in pots. A similar set of inoculated pots with Rhizobium trifolii was also arranged. Berseem crop was grown in both of the sets. The data indicated that total green and dry matter yield as well as root dry weight of berseem decreased consecutively with increase in salinity level while Rhizobium inoculation created a positive effect and these parameters remained significantly higher than the similar levels without inoculation. Nodulation and nodule dry weight was promoted markedly by inoculation and depressed significantly with consistent increase in salinity. Nitrogen percentage of berseem shoot increased with inoculation and decreased significantly at 8 dS m 1 but further increase in salinity had a little effect. Percent nitrogen of soil and nitrogen fixation in soil was enhanced significantly by inoculation and decreased significantly with increase in salinity. Inoculation was helpful to keep the protein content higher. Soil ECe and pH were lowered.

Nazir Hussain

2002-01-01

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

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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.

Del Bel Kate L

2003-01-01

54

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

Science.gov (United States)

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

Diange, Eboa Adolf; Lee, Sang-Seob

2013-06-01

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

Energy Technology Data Exchange (ETDEWEB)

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.

Hollingsworth, R.I.

1991-01-01

56

Variability among Rhizobium Strains Originating from Nodules of Vicia faba  

Science.gov (United States)

Rhizobium strains from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the strains. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium strains in the different geographical locations from which the strains originated. An investigation of pea strains with antibodies prepared against fava bean strains and restriction fragment length polymorphism analyses, targeting DNA regions coding for rRNA and nodulation, indicated that Rhizobium strains from V. faba nodules were distinguishable from those from Pisum sativum, V. villosa, and Trifolium spp. PMID:16535075

van Berkum, P.; Beyene, D.; Vera, F. T.; Keyser, H. H.

1995-01-01

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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)

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.

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

1986-10-01

58

Intragenomic diversity of Rhizobium leguminosarum bv. trifolii clover nodule isolates  

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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.

Marek-Kozaczuk Monika

2011-05-01

59

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

Science.gov (United States)

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

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

2014-01-01

60

Transfer of RP4 and R68.45 factors to Rhizobium.  

Science.gov (United States)

Two R factor were introduced by conjugation into Rhizobium trifolii and Rhizobium meliloti strains at a frequency of 10(-5) to 10(-6). Plasmids RP4 from Escherichia coli J53 and R68.45 from Pseudomonas aeruginosa PAO.25 were maintained stably in Rhizobium hosts and could be retransferred to other Rhizobium recipients. Some of the transconjugants were able to mobilize chromosome and transfer his or met genes in intra-, and interspecies matings. PMID:92171

Kowalczuk, E; Lorkiewicz, Z

1979-01-01

 
 
 
 
61

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

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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.

Lin, XG.

1993-01-01

62

Biologie, écologie et pêche des lamproies migratrices (agnathes amphihalins): rapport final - Troisième tranche fonctionnelle -  

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The pattern of growth larval habitat Petromyzon marinus et Lampetra sp..preferences was examined in 4th order rivers Livenne, Cère, Dronne and in the 6th order river Dordogne (modules from 279 to 2,5 m3/s). From shallow waters to deepwater areas, the same dredging technique was used while diving to catch burrowing larvae. Sampled sections of rivers were chosen downstream of one spawning ground at least. Larvae aggregated at sites presenting a soft river bed in deep macrohabitats or shallow w...

Taverny, C.; Urdaci, M.; Elie, A. M.; Beaulaton, L.; Ortusi, I.; Daverat, F.; Elie, P.

2005-01-01

63

Increased metabolic potential of Rhizobium spp. is associated with bacterial competitiveness.  

Science.gov (United States)

Of 105 rhizobial isolates obtained from nodules of commonly cultivated legumes, we selected 19 strains on the basis of a high rate of symbiotic plant growth promotion. Individual strains within the species Rhizobium leguminosarum bv. trifolii, R. leguminosarum bv. viciae, and Rhizobium etli displayed variation not only in plasmid sizes and numbers but also in the chromosomal 16S-23S internal transcribed spacer. The strains were tagged with gusA gene and their competitiveness was examined in relation to an indigenous population of rhizobia under greenhouse conditions. A group of 9 strains was thus isolated that were competitive in relation to native rhizobia in pot experiments. Nineteen selected competitive and uncompetitive strains were examined with respect to their ability to utilize various carbon and energy sources by means of commercial Biolog GN2 microplate test. The ability of the selected strains to metabolize a wide range of nutrients differed markedly and the competitive strains were able to utilize more carbon and energy sources than uncompetitive ones. A major difference concerned the utilization of amino and organic acids, which were metabolized by most of the competitive and only a few uncompetitive strains, whereas sugars and their derivatives were commonly utilized by both groups of strains. A statistically significant correlation between the ability to metabolize a broad range of substrates and nodulation competitiveness was found, indicating that metabolic properties may be an essential trait in determining the competitiveness of rhizobia. PMID:17898852

Wielbo, Jerzy; Marek-Kozaczuk, Monika; Kubik-Komar, Agnieszka; Skorupska, Anna

2007-08-01

64

Growth of Indigenous Rhizobium leguminosarum and Rhizobium meliloti in Soils Amended with Organic Nutrients.  

Science.gov (United States)

The ability of indigenous Rhizobium leguminosarum and Rhizobium meliloti to use organic nutrients as growth substrates in soil was assessed by indirect bacteriophage analysis. A total of 17 organic compounds, including 9 carbohydrates, 3 organic acids, and 5 amino acids, were tested (1,000 mug g) in three soils with different cropping histories. Four additional soils were screened with a glucose amendment. Nutrient amendments stimulated growth of indigenous rhizobia, allowing subsequent replication of indigenous bacteriophages. Phage populations were enumerated by plating soil extracts on 19 R. leguminosarum and 9 R. meliloti indicator strains, including root nodule isolates from the soils assayed. On the basis of indirect phage analysis, all soils contained native rhizobia similar to one or more of the indicator strains, although not all indicator strains were detected in soil. All organic compounds stimulated growth of indigenous rhizobia, but the growth response varied for each rhizobial strain depending on the nutrient, the nutrient concentration, and the soil. Indigenous rhizobia readily utilized most organic compounds except phenylalanine, glycine, and aspartic acid. The ability of indigenous rhizobia to utilize a wide range of organic compounds as growth substrates in situ indicates their ability to successfully compete with other soil bacteria for nutrients in these soils. PMID:16347530

Germida, James J

1988-01-01

65

Physiological role of calcium in legume-rhizobium symbiosis  

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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.

Vasil’eva G.G.

2011-12-01

66

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)

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

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

2013-06-01

67

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  

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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.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 Rhizobium 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.

Ademir Sérgio Ferreira de Araújo

2006-06-01

68

Removal of chromium using Rhizobium leguminosarum.  

Science.gov (United States)

The chromium (Cr(III) and Cr(VI)) removal capability of Rhizobium leguminosarum was checked by estimating the amount of chromium in the medium before and after inoculation. To determine the efficiency of R. leguminosarum in removal of chromium, the influence of physical and chemical parameters such as temperature, pH and different concentrations (0.1-1.0 mM) of trivalent (Cr(III)) and hexavalent (Cr(VI)) chromium were studied. The chromium removal in aqueous solution by different size of active and inactivated biomass and immobilized cells of R. leguminosarum in a packed-bed column was also carried out. Results showed that in a medium containing up to 0.5 mM concentration of both Cr(III) and Cr(VI), R. leguminosarum showed optimal growth. The maximum chromium removal was at pH 7.0 and 35°C. Active biomass removed 84.4 ± 3.6% of Cr(III) and 77.3 ± 4.3% of Cr(VI) in 24 h of incubation time. However, inactivated biomass removed maximum chromium after 36 h of incubation. Immobilized bacterial cells in a packed-bed column removed 86.4 ± 1.7% of Cr(III) and 83.8 ± 2.2% of Cr(VI) in 16 and 20 h of incubation time, respectively. PMID:22806858

Raaman, N; Mahendran, B; Jaganathan, C; Sukumar, S; Chandrasekaran, V

2012-02-01

69

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

DEFF Research Database (Denmark)

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.

Jensen, Erik Steen; SØrensen, Lasse Holst

1986-01-01

70

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

Science.gov (United States)

...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....

2013-06-04

71

78 FR 22298 - United States v. Apple, Inc., et al.; Public Comments and Response on Proposed Final Judgment  

Science.gov (United States)

...Antitrust Division United States v. Apple, Inc., et al.; Public Comments and...USA), Inc. in United States v. Apple, Inc., et al., Civil Action No...States of America, Plaintiff, v. Apple, Inc., et al., Defendants....

2013-04-15

72

Inoculação com Rhizobium e aplicação de nitrogênio em amendoim / Comparison among Rhizobium strains inoculations and nitrogen applications on peanut, in field conditions  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Existe, nas nossas condições, uma população autóctone de Rhizobium capaz de nodular o amendoim (Arachis hypogaea L.), mas pouco se sabe da contribuição do nitrogênio fixado para esta planta. Foram conduzidos dois ensaios no campo, em solo de baixa fertilidade, um no período "da seca" e outro no "das [...] águas", comparando o crescimento e a produção de plantas de amendoim inoculado com Rhizobium selecionado, com o de plantas noduladas pela população autóctone, adubadas ou não com nitrogênio. A nodulação das plantas inoculadas foi semelhante à observada nos tratamentos não inoculados, com ou sem nitrogênio. Na fase final do ciclo das plantas, houve maior acúmulo e maior taxa de absorção diária de nitrogênio nos tratamentos inoculados ou com adubação nitrogenada, do que no controle sem inoculação e sem nitrogênio. No ensaio da seca, não houve aumento de produção devido à adubação nitrogenada, ou à inoculação. No ensaio das águas, houve resposta à aplicação de nitrogênio no plantio. Os resultados de produção não foram coerentes com os da marcha de absorção de N. A produção de ensaio das águas foi equivalente a 3.400 kg/ha para o tratamento sem nitrogênio e sem inoculação. Abstract in english Two field experiments were carried out with peanut in the same area on a limed and fertilized "cerrado soil" (originally acidic and low fertility). The first experiment was carried out in the autumn/winter (dry season), and the second one in the subsequent spring/summer (wet season), in Campinas, St [...] ate of São Paulo, Brazil. Plant development and production of inoculated (three Rhizobium strains) and nitrogen fertilized treatments (at planting 25 and 45 days after planting) were compared with non-inoculated and non-N-fertilized control. Nodulation of inoculated plants was similar to those of non-inoculated, with or without nitrogen. Greater accumulations, and rates for average daily uptake of nitrogen were observed for inoculated as well as for nitrogen fertilized plants, as compared to the control. In the autumn/winter experiment there was no increase in pod production neither due to nitrogen or to inoculation. In the spring/summer experiment however, the pod production was higher with nitrogen (30kg/N/ha) at planting, although higher nitrogen accumulations in plant shoots (sampled 84 days after planting) were observed treatments with two of the three inoculated strains.

Antonio Roberto, Giardini; Eli Sidney, Lopes; Angelo, Savy Filho; André Martin Louis, Neptune.

73

Inoculação com Rhizobium e aplicação de nitrogênio em amendoim Comparison among Rhizobium strains inoculations and nitrogen applications on peanut, in field conditions  

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Full Text Available Existe, nas nossas condições, uma população autóctone de Rhizobium capaz de nodular o amendoim (Arachis hypogaea L., mas pouco se sabe da contribuição do nitrogênio fixado para esta planta. Foram conduzidos dois ensaios no campo, em solo de baixa fertilidade, um no período "da seca" e outro no "das águas", comparando o crescimento e a produção de plantas de amendoim inoculado com Rhizobium selecionado, com o de plantas noduladas pela população autóctone, adubadas ou não com nitrogênio. A nodulação das plantas inoculadas foi semelhante à observada nos tratamentos não inoculados, com ou sem nitrogênio. Na fase final do ciclo das plantas, houve maior acúmulo e maior taxa de absorção diária de nitrogênio nos tratamentos inoculados ou com adubação nitrogenada, do que no controle sem inoculação e sem nitrogênio. No ensaio da seca, não houve aumento de produção devido à adubação nitrogenada, ou à inoculação. No ensaio das águas, houve resposta à aplicação de nitrogênio no plantio. Os resultados de produção não foram coerentes com os da marcha de absorção de N. A produção de ensaio das águas foi equivalente a 3.400 kg/ha para o tratamento sem nitrogênio e sem inoculação.Two field experiments were carried out with peanut in the same area on a limed and fertilized "cerrado soil" (originally acidic and low fertility. The first experiment was carried out in the autumn/winter (dry season, and the second one in the subsequent spring/summer (wet season, in Campinas, State of São Paulo, Brazil. Plant development and production of inoculated (three Rhizobium strains and nitrogen fertilized treatments (at planting 25 and 45 days after planting were compared with non-inoculated and non-N-fertilized control. Nodulation of inoculated plants was similar to those of non-inoculated, with or without nitrogen. Greater accumulations, and rates for average daily uptake of nitrogen were observed for inoculated as well as for nitrogen fertilized plants, as compared to the control. In the autumn/winter experiment there was no increase in pod production neither due to nitrogen or to inoculation. In the spring/summer experiment however, the pod production was higher with nitrogen (30kg/N/ha at planting, although higher nitrogen accumulations in plant shoots (sampled 84 days after planting were observed treatments with two of the three inoculated strains.

Antonio Roberto Giardini

1985-01-01

74

[Studies on allelopathic effect of artemisinin on rhizobium].  

Science.gov (United States)

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

Li, Qian; Wu, Yekuan; Huang, Jianguo

2011-12-01

75

[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)

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.

Hollingsworth, R.I.

1991-12-31

76

Estirpes de Rhizobium tropici na inoculação do feijoeiro Rhizobium tropici strains for inoculation of the common bean  

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Full Text Available Avaliando o comportamento do feijoeiro inoculado com cinco estirpes de Rhizobium tropici e a adubação mineral com nitrogênio, sobre alguns fatores relacionados à sua produtividade, utilizou-se um delineamento experimental de blocos ao acaso, com oito tratamentos constituídos pela inoculação do feijoeiro cultivar IAC Carioca com cinco estirpes de Rhizobium tropici (CIAT 899 - estirpe referência; F35; F54; F81 e CM255, dois controles sem inoculação sendo um adubado com N na semeadura e em cobertura e outro sem adubação e um cultivar não nodulante (NORH 54 adubado; com seis repetições. Avaliaram-se: número de nódulos por planta; massa de material seco da parte aérea; teor de N nas folhas; número de vagens por planta; número de grãos por planta; número de grãos por vagem; peso de 100 grãos e produtividade de grãos. A inoculação de estirpes eficientes de Rhizobium em cultivar nodulante de feijoeiro, ou o cultivo deste em solos com população nativa eficiente, pode possibilitar a não utilização de nitrogênio em cobertura na cultura do feijoeiro, sem afetar a produtividade.To evaluate five Rhizobium tropici strains and N fertilization on the productivity components of the common bean (Phaseolus vulgaris L. crop, an experimental design of randomized blocks was used. The eight treatments consisted of five Rhizobium tropici strains (CIAT899; F35; F54; F81, and CM255, two controls without inoculation (30 kg ha-1 N with PK at sowing plus 30 kg ha-1 N as top dressing, and other without fertilization NPK with the IAC Carioca cultivar and one non-nodulating cultivar (NORH54. Number of nodules per plant, shoot dry mass, leaf N content, number of pods per plant, number of grains per plant, number of grains per pod, 100 grain weight, and grain yield, were evaluated. The nodulating cultivar with inoculation or in soil with efficient native population can eliminate the N top dressing with no decrease in yield.

Alessandro Nunes Ferreira

2000-09-01

77

75 FR 6709 - United States, et al. v. Ticketmaster Entertainment Inc. and Live Nation Inc.; Proposed Final...  

Science.gov (United States)

...United States, et al. v. Ticketmaster Entertainment Inc. and Live Nation Inc.; Proposed...America, et al. v. Ticketmaster Entertainment, Inc. and Live Nation, Inc., Civil...the proposed merger of Ticketmaster Entertainment, Inc. and Live Nation, Inc....

2010-02-10

78

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

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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.

Maria G?owacka

1996-12-01

79

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

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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.

Cigdem KuCuk

2008-01-01

80

Projet Levees (2010-2013). Ruptures diffuses et érosives des digues fluviales de protection contres les inondations. Rapport final  

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/ Ce rapport rend compte des résultats les plus importants du projet Levees “Ruptures diffuses et érosives des digues fluviales de protection contres les inondations” (2010-2013), subventionnés par la Direction de la recherche et de l’innovation (DRI) du Commissariat général au développement durable (CGDD), dans le cadre du programme “Concevoir et construire pour le développement durable” du Réseau Génie Civil et Urbain (RGCU-C2D2 ). Le projet Levees...

Bonelli, S.

2013-01-01

 
 
 
 
81

Glycerol utilization by Rhizobium leguminosarum requires an ABC transporter and affects competition for nodulation.  

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Plasmid curing has shown that the ability to use glycerol as a carbon source is plasmid-encoded in Rhizobium leguminosarum. We isolated the locus responsible for glycerol utilization from plasmid pRleVF39c in R. leguminosarum bv. viciae VF39. This region was analyzed by DNA sequencing and mutagenesis. The locus encompasses a gene encoding GlpR (a DeoR regulator), genes encoding an ABC transporter, and genes glpK and glpD, encoding a kinase and dehydrogenase, respectively. All the genes except the regulatory gene glpR were organized into a single operon, and were required for growth on glycerol. The glp operon was strongly induced by both glycerol and glycerol 3-phosphate, as well as by pea seed exudate. GlpR repressed the operon in the absence of inducer. Mutation of genes encoding the ABC transporter abolished all transport of glycerol in transport assays using radiolabelled glycerol. This confirms that, unlike in other organisms such as Escherichia coli and Pseudomonas aeruginosa, which use facilitated diffusion, glycerol uptake occurs by an active process in R. leguminosarum. Since the glp locus is highly conserved in all sequenced R. leguminosarum and Rhizobium etli strains, as well as in Sinorhizobium spp. and Agrobacterium spp. and other alphaproteobacteria, this process for glycerol uptake is probably widespread. Mutants unable to use glycerol were deficient in competitiveness for nodulation of peas compared with the wild-type, suggesting that glycerol catabolism confers an advantage upon the bacterium in the rhizosphere or in the infection thread. PMID:22343359

Ding, Hao; Yip, Cynthia B; Geddes, Barney A; Oresnik, Ivan J; Hynes, Michael F

2012-05-01

82

Rhizobium as a Biological Agent for Preventing Heavy Metal Stress  

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Full Text Available In the present study, Rhizobium was used as soil fertilizer to prevent the stress of lead on growing Pisum sativum. Three concentrations of lead were used (50, 100 and 200 ppm. for the irrigation of growing plants (two times. After sowing, M2 seeds were collected, then cytological and biochemical studies were carried out. The cytological analysis revealed that soil enriched with Rhizobium increased the rate of mitotic division. A significant increase in mitotic index was detected. The kind of chromosomal abnormalities observed were; disturbances, stickiness, diagonals, chromosome breakage and c-metaphases. Also, a significant reduction in the percentage of abnormalities was observed. Biochemical studies included the analysis of M2 seed proteins using SDS-PAGE, isozyme analysis for both esterase and peroxidase and element analysis of Pb and N.

S.M. Abbas

2004-01-01

83

Factors Affecting the Efficiency of Symbiotic Nitrogen Fixation by Rhizobium  

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Full Text Available Recent reports pointed to a decline in agricultural dependence on symbiotic nitrogen fixation, and in the use of rhizobial inoculants. The aim of the present review was to study the environmental factors that affect the efficiency of symbiotic nitrogen fixation by Rhizobium in soil. These factors included pH, salinity, moisture, temperature, microorganisms, organic matter and soil texture. The overall conclusion is that symbiotic nitrogen fixation by Rhizobium is a critical biological process. Environmental stresses are generally the limiting factors of the symbiotic nitrogen fixation. With the selection of the appropriate legume and rhizobial inoculant, nitrogen fixation can be increased and concomitantly food production can be improved even under environmentally stressed conditions.

Abdullah M. K. Al-Falih

2002-01-01

84

Regulation of phenolic catabolism in Rhizobium leguminosarum biovar trifolii  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1991-09-01

85

Impact of heavy metals on an arctic rhizobium  

Energy Technology Data Exchange (ETDEWEB)

Bacteria belonging to the genus Rhizobium, when residing in the root nodules of leguminous plants, fix nitrogen and thus contribute very significantly to the global nitrogen and thus contribute very significantly to the global nitrogen budget. Although there is paucity of data concerning the effects of metal pollutants on these agronomically important organisms, their negative impact on the nitrogen fixing ability of these microbes is evident. As rhizobia from root nodules of arctic legumes have been demonstrated to contribute significantly to the ecological balance in this region, the impact of some metals, found in elevated amounts in acidic surroundings on this unique Rhizobium has been assessed. In this paper the ability of the microbe to tolerate abnormal levels of manganese and aluminum is reported and the effectiveness of iron in reversing cadmium toxicity is also discussed.

Appanna, V.D. (Laurentian Univ., Sudbury, Ontario (Canada))

1991-03-01

86

Recombinant Rhizobium meliloti strains with extra biotin synthesis capability.  

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The growth of Rhizobium meliloti 1021 in an experimental alfalfa (Medicago sativa L.) rhizosphere was stimulated by adding nanomolar amounts of biotin. To overcome this biotin limitation, R. meliloti strains were constructed by conjugating the Escherichia coli biotin synthesis operon into biotin auxotroph R. meliloti 1021-B3. Transconjugant strains Rm1021-WS10 and Rm1021-WS11 grew faster in vitro and achieved a higher cell density than did R. meliloti 1021 and overproduced biotin on a defined...

Streit, W. R.; Phillips, D. A.

1996-01-01

87

Interstrain Competition between Representatives of Indigenous Serotypes of Rhizobium trifolii†  

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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...

Demezas, David H.; Bottomley, Peter J.

1986-01-01

88

Transport and catabolism of D-mannose in Rhizobium meliloti.  

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Rhizobium meliloti L5-30 grows on D-mannose as the sole carbon source. The catabolic pathway of D-mannose was characterized. The following activities were present: mannose transport system, mannokinase, and mannosephosphate isomerase. Several mannose-negative mutants were selected; they were classified into three functional groups: group I, mannokinase and mannosephosphate isomerase defective: group II, mannokinase defective; and group III, mannosephosphate isomerase defective. Mannose uptake...

Arias, A.; Gardiol, A.; Marti?nez-drets, G.

1982-01-01

89

Root Exudates of Various Host Plants of Rhizobium leguminosarum Contain Different Sets of Inducers of Rhizobium Nodulation Genes.  

Science.gov (United States)

Rhizobium promoters involved in the formation of root nodules on leguminous plants are activated by flavonoids in plant root exudate. A series of Rhizobium strains which all contain the inducible Rhizobium leguminosarum nodA promoter fused to the Escherichia coli lacZ gene, and which differ only in the source of the regulatory nodD gene, were recently used to show that the regulatory nodD gene determines which flavonoids are able to activate the nodA promoter (HP Spaink, CA Wijffelman, E Pees, RJH Okker, BJJ Lugtenberg 1987 Nature 328: 337-340). Since these strains therefore are able to discriminate between various flavonoids, they were used to determine whether or not plants that are nodulated by R. leguminosarum produce different inducers. After chromatographic separation of root exudate constituents from Vicia sativa L. subsp. nigra (L.), V. hirsuta (L.) S.F. Gray, Pisum sativum L. cv Rondo, and Trifolium subterraneum L., the fractions were tested with a set of strains containing a nodD gene of R. leguminosarum, R. trifolii, or Rhizobium meliloti, respectively. It appeared that the source of nodD determined whether, and to what extent, the R. leguminosarum nodA promoter was induced. Lack of induction could not be attributed to the presence of inhibitors. Most of the inducers were able to activate the nodA promoter in the presence of one particular nodD gene only. The inducers that were active in the presence of the R. leguminosarum nodD gene were different in each root exudate. PMID:16666070

Zaat, S A; Wijffelman, C A; Mulders, I H; van Brussel, A A; Lugtenberg, B J

1988-04-01

90

Preliminary data on some correlations of Rhizobium and radio-stimulation seed treatments  

International Nuclear Information System (INIS)

The seeds of peas, beans, soy-beans and lucerne were treated with 60Co-irradiation (4-10 Gray). The size of the roots and the quantity of seed-crop were measured. Irradiation by itself had no significant effect. Treatment with Rhizobium bacteria and with Rhizobium plus irradiation had considerable positive effects. (L.E.)

91

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

Science.gov (United States)

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

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

2013-06-01

92

Functional and evolutionary relatedness of genes for exopolysaccharide synthesis in Rhizobium meliloti and Rhizobium sp. strain NGR234.  

Science.gov (United States)

Rhizobium meliloti SU47 and Rhizobium sp. strain NGR234 produce distinct exopolysaccharides that have some similarities in structure. R. meliloti has a narrow host range, whereas Rhizobium strain NGR234 has a very broad host range. In cross-species complementation and hybridization experiments, we found that several of the genes required for the production of the two polysaccharides were functionally interchangeable and similar in evolutionary origin. NGR234 exoC and exoY corresponded to R. meliloti exoB and exoF, respectively. NGR234 exoD was found to be an operon that included genes equivalent to exoM, exoA, and exoL in R. meliloti. Complementation of R. meliloti exoP, -N, and -G by NGR234 R'3222 indicated that additional equivalent genes remain to be found on the R-prime. We were not able to complement NGR234 exoB with R. meliloti DNA. In addition to functional and evolutionary equivalence of individual genes, the general organization of the exo regions was similar between the two species. It is likely that the same ancestral genes were used in the evolution of both exopolysaccharide biosynthetic pathways and probably of pathways in other species as well. PMID:2203745

Zhan, H J; Gray, J X; Levery, S B; Rolfe, B G; Leigh, J A

1990-09-01

93

Toxicity testing of heavy metals with the Rhizobium-legume symbiosis: High sensitivity to cadmium and arsenic compounds.  

Science.gov (United States)

Legume root nodules are the site of biological nitrogen fixation in the Rhizobium-legume symbiosis. Nodules are structures unique to this symbiosis and they are morphologically as well as physiologically distinct from other plant organs. Organic substances affecting the macro- or microsymbionts vitality, such as PAHs (WETZEL: et al., 1991), reduce nodulation even before visible damage to the plant can be detected. We present data that the formation of nodules (nodulation) may also serve for ecotoxicological evaluation of heavy metals in different binding states. Tests were performed in petri dishes with alfalfa (lucerne) seedlings inoculated with Rhizobium meliloti. Cultivation took place in growth cabinets with carefully standardized and documented growth conditions. Data from stressed plants was recorded after 14 days of cultivation on contaminated substrate. A dose responsive decrease in nodulation was found after application of cadmium acetate, cadmium iodide, cadmium chloride, sodium salts of arsenate and arsenite, arsenic pentoxide, and lead nitrate, whereas lead acetate showed no effect up to a concentration of 3 microM. The dose response curves were used to calculate EC10, EC50 and EC90 values. EC50 values for cadmium compounds range from 1.5 to 9.5 pM. Testing different arsenic compounds results in EC50 from 2.6 to 20.1 microM. EC50 of lead nitrate is 2.2 microM. The sensitivity, reproducibility and reliability of this test system is discussed compared to established biotests. PMID:19002625

Neumann, H; Bode-Kirchhoff, A; Madeheim, A; Wetzel, A

1998-01-01

94

Two genes that regulate exopolysaccharide production in Rhizobium meliloti.  

Science.gov (United States)

We describe a new Rhizobium meliloti gene, exoX, that regulates the synthesis of the exopolysaccharide, succinoglycan, exoX resembled the psi gene of R. leguminosarum bv. phaseoli and the exoX gene of Rhizobium sp. strain NGR234 in its ability to inhibit exopolysaccharide synthesis when present in multiple copies, exoX did not appear to regulate the expression of exoP. The effect of exoX was counterbalanced by another R. meliloti gene, exoF. exoF is equivalent to Rhizobium sp. strain NGR234 exoY and resembles R. leguminosarum bv. phaseoli pss2 in its mutant phenotype and in portions of its deduced amino acid sequence. The effect of exoF on the succinoglycan-inhibiting activity of exoX depended on the relative copy numbers of the two genes. exoX-lacZ fusions manifested threefold-higher beta-galactosidase activities in exoF backgrounds than in the wild-type background. exoX mutants produced increased levels of succinoglycan. However, the exoF gene was required for succinoglycan synthesis even in an exoX mutant background. exoF did not affect the expression of exoP. Strains containing multicopy exoX formed non-nitrogen-fixing nodules on alfalfa that resembled nodules formed by exo mutants defective in succinoglycan synthesis. exoX mutants formed nitrogen-fixing nodules, indicating that, if the inhibition of succinoglycan synthesis within the nodule is necessary for nitrogen fixation, then exoX is not required for this inhibition. We present indirect evidence that succinoglycan synthesis within the nodule is not necessary for bacteroid function. PMID:2118508

Zhan, H J; Leigh, J A

1990-09-01

95

Regulation of phosphate assimilation in Rhizobium (Sinorhizobium) meliloti.  

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We report the isolation of phoB and phoU mutants of the bacterium Rhizobium (Sinorhizobium) meliloti. These mutants form N2-fixing nodules on the roots of alfalfa plants. R. meliloti mutants defective in the phoCDET (ndvF) encoded phosphate transport system grow slowly in media containing 2 mM Pi, and form nodules which fail to fix nitrogen (Fix-). We show that the transfer of phoB or phoU insertion mutations into phoC mutant strains restores the ability of these mutants to: (i) form normal N...

Bardin, S. D.; Finan, T. M.

1998-01-01

96

Cloning and mutagenesis of the Rhizobium meliloti isocitrate dehydrogenase gene.  

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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...

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

1992-01-01

97

Large-Scale Production of Rhizobium meliloti on Whey †  

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Whey, a by-product of the cheese industry, can sustain the growth of fast-growing rhizobia. To avoid any latency of growth, rhizobial inoculum must be prepared under inducing conditions. In unsupplemented whey, the number of cells of Rhizobium meliloti Balsac reached 5 × 109 CFU/ml in 48 h of incubation. This is comparable to the yield obtained with yeast-mannitol broth, the standard medium for the growth of rhizobia. In raw whey supplemented with yeast extract (1.0 g/liter) and phosphate (0...

Bissonnette, N.; Lalande, R.; Bordeleau, L. M.

1986-01-01

98

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)

99

studies On Legume-rhizobium And Mycorrihizal Interaction Withspecial Reference To Phaseolusradiatusl. And Phaseolus Aconitifoliusjacq.  

Directory of Open Access Journals (Sweden)

Full Text Available The study was initiated to determine the influence of VAM fungi on a Rhizobium- legume interaction. The pot culture experiment was conducted during rabbi season with seed of Phaseolu sradiatus.L.and PhaseolusaconitifoliusJacq.and Leonard jar experiment was conducted for Phaseolusa conitifolius.The different inoculations of Rhizobium and Mycorrihizawere incorporated. During the period of experiment, samples were analysed for nodule numbers, dry weight of nodules,freshweight, dry weight of plant, yield of pods, and length of plant and percentage of Mycorrihizalcolonization. The results revealed that dual inoculation of Rhizobium with VAM enhanced seed yield of chickpea and golden- green gram.

Sunil A. Gosavi

2013-08-01

100

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)

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.

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

2006-09-01

 
 
 
 
101

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 crescime...

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

2006-01-01

102

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)

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.

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

103

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)

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.

J.B. Santos

2006-09-01

104

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

En la presente investigación, seis cepas de Rhizobium aisladas de suelos argelinos fueron estudiadas para conocer su actividad antimicrobiana contra Pseudomonas savastanoi, el agente causante de la tuberculosis del olivo. Rhizobium sp. ORN 24 y ORN 83 produjeron actividad antimicrobiana contra Pseudomonas savastanoi. La actividad antimicrobiana producida por Rhizobium sp. ORN 24 precipitó con sulfato amónico, tuvo un peso molecular entre 1000 y 10000 KDa, fue resistente al calor pero sensible a proteasas y detergentes. Estas características sugieren que la sustancia antimicrobial producida por Rhizobium sp. ORN 24 es la bacteriocina natural conocida como rizobiocina 24. Por el contrario, la actividad antimicrobiana producida por Rhizobium sp. ORN83 no fue precipitable con sulfato amónico, y tuvo un peso molecular menor de 1000 KDa, fue lábil al calor y resistente a detergentes y proteasas. Estas características podrían indicar una relación de la sustancia antimicrobiana producida por Rhizobium sp. ORN83 con la “pequeña” bacteriocina descrita en otros Rhizobium.

2009-06-01

105

A rhizobium leguminosarum mutant defective in symbiotic iron acquisition  

Energy Technology Data Exchange (ETDEWEB)

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.

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

106

Microgravity effects on the legume/Rhizobium symbiosis  

Science.gov (United States)

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.

Urban, James E.

1997-01-01

107

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

108

Oligogalacturonides: novel signaling molecules in Rhizobium-legume communications.  

Science.gov (United States)

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

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

2012-11-01

109

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

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Full Text Available 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, sete foram eficientes fixadoras de nitrogênio. Das doze estirpes que nodularam, sete foram isoladas de leguminosas da tribo Hedysareae (à qual pertence o género Arachis e, destas, apenas quatro foram eficientes fixadoras de nitrogênio. O peso e o número de nódulos não se mostraram como critérios adequados para avaliação da eficiência.An experiment was carried out in Leonard jars, in the greenhouse, with nitrogen-free nutrient solution to test the efficiency of 35 strains of rhizobia isolated from 15 species of tropical legumes. Twelve of the tested strains were capable of nodule formation in peanut. Seven of those strains were isolated from the trible Hedysareae, which includes the genus Arachis. Only four of the rhizobia strains with inducing nodulation were effective. Dry weight and number of nodules were not good criteria for evaluating effectiveness.

Antonio Roberto Giardini

1984-01-01

110

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 diferent [...] es 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, sete foram eficientes fixadoras de nitrogênio. Das doze estirpes que nodularam, sete foram isoladas de leguminosas da tribo Hedysareae (à qual pertence o género Arachis) e, destas, apenas quatro foram eficientes fixadoras de nitrogênio. O peso e o número de nódulos não se mostraram como critérios adequados para avaliação da eficiência. Abstract in english An experiment was carried out in Leonard jars, in the greenhouse, with nitrogen-free nutrient solution to test the efficiency of 35 strains of rhizobia isolated from 15 species of tropical legumes. Twelve of the tested strains were capable of nodule formation in peanut. Seven of those strains were i [...] solated from the trible Hedysareae, which includes the genus Arachis. Only four of the rhizobia strains with inducing nodulation were effective. Dry weight and number of nodules were not good criteria for evaluating effectiveness.

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

111

Nitrogen fixing capacity of some soybean cultivars inoculated with different Rhizobium japonicum strains  

International Nuclear Information System (INIS)

The nitrogen-fixing efficiency of different Rhizobium japonicum strains was tested. The strains were inoculated into three soybean cultivars and grain yield, total nitrogen content and nitrogen-fixing capacity were determined. 4 refs, 1 tab

112

Natural variation in symbiotic nitrogen-fixing Rhizobium and Frankia spp.  

Science.gov (United States)

A description is given of the natural variation in nitrogen-fixing Rhizobium and Frankia spp. strains and the ability to form root nodules on compatible host plants. Arguments are given for the hypothesis that co-evolution has taken place through mutual interaction of host plants and indigenous Rhizobium and Frankia populations in the soil leading to most efficient symbiotic associations. The significance of root nodules as selective enrichment cultures of particular strains in natural and cultivated soils is exemplified by Rhizobium leguminosarum on various ecotypes of Pisum sativum and with Frankia sp. on various actinorhizal plants, in particular Alnus spp., in different geographic regions. The importance of a host-dependent distribution of Rhizobium and Frankia spp. for agriculture and forestry is discussed. PMID:6397130

Lie, T A; Akkermans, A D; van Egeraat, A W

1984-01-01

113

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-07-01

114

Effect of Rhizobium sp., on Growth of Pathogenic Fungi under in vitro Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available In a laboratory study chickpea root nodulating bacterium Rhizobium sp., strain Thal-8 significantly inhibited the growth of pathogenic fungi (Alternaria alternata, Fusarium sp. Ascochyta rabiei, Drechslera sp. and Curvularia sp. in potato dextrose agar media. The inhibition rate displayed differences in accordance with different fungi cultures. However, the inhibitory effect of Rhizobium sp., strain Thal-8 occurred most on pure cultures growth of Alternaria alternata and Drechslera sp. (54 and 45%, respectively and least on Curvularia sp. (3%.

Tabassam Sharif

2003-01-01

115

Rhizobium as a Biological Agent for Preventing Heavy Metal Stress  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the present study, Rhizobium was used as soil fertilizer to prevent the stress of lead on growing Pisum sativum. Three concentrations of lead were used (50, 100 and 200 ppm.) for the irrigation of growing plants (two times). After sowing, M2 seeds were collected, then cytological and biochemical studies were carried out. The cytological analysis revealed that soil enriched with Rhizobium increased the rate of mitotic division. A significant increase in mitot...

Abbas, S. M.; Kamel, E. A.

2004-01-01

116

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

Science.gov (United States)

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

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

2014-04-20

117

75 FR 29647 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for...  

Science.gov (United States)

...of Documents. Prices of new books are listed in the first FEDERAL...OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 930 [Doc...Year AGENCY: Agricultural Marketing Service, USDA. ACTION: Final...crop year under the Federal marketing order regulating tart...

2010-05-27

118

77 FR 36115 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for...  

Science.gov (United States)

...of Documents. Prices of new books are listed in the first FEDERAL...OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 930 [Doc...Cherries AGENCY: Agricultural Marketing Service, USDA. ACTION: Final...2011-12 crop year under the marketing order for tart cherries...

2012-06-18

119

76 FR 10471 - Tart Cherries Grown in the States of Michigan, et al.; Final Free and Restricted Percentages for...  

Science.gov (United States)

...of Documents. Prices of new books are listed in the first FEDERAL...OF AGRICULTURE Agricultural Marketing Service 7 CFR Part 930 [Doc...Cherries AGENCY: Agricultural Marketing Service, USDA. ACTION: Final...percentages under the tart cherry marketing order for the 2010-2011...

2011-02-25

120

Rhizobium vallis sp. nov., isolated from nodules of three leguminous species.  

Science.gov (United States)

Four bacterial strains isolated from root nodules of Phaseolus vulgaris, Mimosa pudica and Indigofera spicata plants grown in the Yunnan province of China were identified as a lineage within the genus Rhizobium according to the analysis of 16S rRNA gene sequences, sharing most similarity with Rhizobium lusitanum P1-7(T) (99.1 % sequence similarity) and Rhizobium rhizogenes IAM 13570(T) (99.0 %). These strains also formed a distinctive group from the reference strains for defined species of the genus Rhizobium in a polyphasic approach, including the phylogenetic analyses of the 16S rRNA gene and housekeeping genes (recA, atpD, glnII), DNA-DNA hybridization, BOX-PCR fingerprinting, phenotypic characterization, SDS-PAGE of whole-cell proteins, and cellular fatty acid profiles. All the data obtained in this study suggested that these strains represent a novel species of the genus Rhizobium, for which the name Rhizobium vallis sp. nov. is proposed. The DNA G+C content (mol%) of this species varied between 60.9 and 61.2 (T(m)). The type strain of R. vallis sp. nov. is CCBAU 65647(T) ( = LMG 25295(T) =HAMBI 3073(T)), which has a DNA G+C content of 60.9 mol% and forms effective nodules on Phaseolus vulgaris. PMID:21131504

Wang, Fang; Wang, En Tao; Wu, Li Juan; Sui, Xin Hua; Li, Ying; Chen, Wen Xin

2011-11-01

 
 
 
 
121

High lipid productivity of an Ankistrodesmus-Rhizobium artificial consortium.  

Science.gov (United States)

Microalgae have great potential as alternative productive platforms for sustainable production of bioenergy, food, feed and other commodities. Process optimization to realize the claimed potential often comprises strains selection and improvement and also developing of more efficient cultivation, harvesting and downstream processing technology. In this work we show that inoculation with the bacterium Rhizobium strain 10II resulted in increments of up to 30% in chlorophyll, biomass and lipids accumulation of the oleaginous microalgae Ankistrodesmus sp. strain SP2-15. Inoculated cultures have reached a high lipid productivity of up to 112 mg L(-1) d(-1) after optimization. The resulting biomass presented significant levels of ?3 fatty acids including stearidonic acid, suggesting potential as an alternative land-based source of essential fatty acids. PMID:23948276

Do Nascimento, Mauro; Dublan, Maria de los Angeles; Ortiz-Marquez, Juan Cesar Federico; Curatti, Leonardo

2013-10-01

122

Transposition of Tn 1 to the Rhizobium meliloti genome.  

Science.gov (United States)

A derivative of the IncP1 plasmid RP4, carrying the thermoinducible prophage Mucts62, was obtained in Escherichia coli K12 J53 (RP4). It was impossible to maintain the hybrid plasmid RP4::Mucts62 in Rhizobium meliloti GR4. Thus, it was used as a vehicle for introducing the ampicillin-resistant transposon Tn1 into the R. meliloti genome. Transposition of Tn1 did not generate auxotrophic strains, suggesting that the insertion of Tn1 into the R. meliloti genome was relatively specific. Two chromosomal hot spots for Tn1 insertion were identified by cotransductional analysis, after general transduction by phage DF2. Plasmid-curing experiments, carried out by heat treatment, revealed that symbiotic plasmid(s) also contain at least one site for Tn1 insertion. PMID:6258027

Casadesús, J; Iáñez, E; Olivares, J

1980-01-01

123

Differences between strains of Rhizobium in sensitivity to canavanine  

International Nuclear Information System (INIS)

Four strains of rhizobia that nodulate canavanine-synthesizing legumes and four strains that nodulate noncanavanine-synthesizing legumes were tested for sensitivity to L-canavanine. The effect of canavanine on growth depends upon the strain of Rhizobium tested rather than the canavanine synthesizing capability of the host legume. In both groups of rhizobia, some strains were inhibited in growth by canavanine. Canavanine enhancement of growth was observed in rhizobia that nodulate noncanavanine-synthesizing legumes. Canavanine was found to enhance the incorporation of 3H-uridine and 3H-L-leucine into trichloroacetic acid insoluble fractions of starved cells of two strains of rhizobia tested. This demonstrated that under certain conditions, some rhizobia can detoxify canavanine and utilize it in synthetic processes

124

Biosynthesis of succinoglycan, a symbiotically important exopolysaccharide of Rhizobium meliloti.  

Science.gov (United States)

The exo genes of Rhizobium meliloti are needed for the synthesis of an acidic exopolysaccharide, succinoglycan. We have assigned biosynthetic roles to the products of the exo genes by characterizing succinoglycan biosynthetic intermediates from exo mutant strains. We propose a model of succinoglycan biosynthesis in which the products of the exoY and exoF genes function in the addition of the first sugar, galactose, to the lipid carrier; the products of the exoA, exoL, exoM, exoO, exoU, and exoW genes function in subsequent sugar additions; and the product of the exoV gene functions in the addition of pyruvate. The products of the exoP, exoQ, and exoT genes are required for polymerization of the octasaccharide subunits or transport of the completed polymer. PMID:8343955

Reuber, T L; Walker, G C

1993-07-30

125

Strain identification in Rhizobium by starch gel electrophoresis of isoenzymes  

DEFF Research Database (Denmark)

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.

Engvild, Kjeld Christensen

1985-01-01

126

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

127

Genotypic and Phenotypic Comparisons of Chromosomal Types within an Indigenous Soil Population of Rhizobium leguminosarum bv. trifolii.  

Science.gov (United States)

The relative genetic similarities of 200 isolates of Rhizobium leguminosarum bv. trifolii recovered from an Oregon soil were determined at 13 enzyme loci by multilocus enzyme electrophoresis (MLEE). These isolates represented 13 antigenically distinct serotypes recovered from nodules formed on various clover species. The MLEE-derived levels of relatedness among isolates of R. leguminosarum bv. trifolii were found to be in good agreement with the levels of relatedness established by using repetitive (repetitive extragenic palindromic and enterobacterial repetitive intergeneric consensus) sequences and the PCR technique and with levels of relatedness from previously published DNA reassociation studies. BIOLOG substrate utilization patterns showed that isolates within an electrophoretic type (ET) were phenotypically more similar to each other than to isolates of other ETs. The soil isolates were represented by 53 ETs which could be clustered into seven groups (groups B, E, G, H1, H2, I, and J). Evidence for multilocus structure within the population was obtained, and group B was identified as the primary creator of the disequilibrium. Of 75 isolates belonging to the nodule-dominant serotype AS6 complex, 72 were found in group B. Isolates WS2-01 and WS2-02 representing nodule-dominant serotypes recovered from subclover grown at another Oregon site were also found in group B. Isolates representing the most numerous ETs in group B (ETs 2 and 3) were either suboptimally effective or completely ineffective at fixing nitrogen on six different clover species. Another four groups of isolates (groups A, C, D, and F) were identified when 32 strains of diverse origins were analyzed by MLEE and incorporated into the cluster analysis. Group A was most dissimilar in comparisons with other groups and contained strain USDA 2124 (T24), which produces trifolitoxin and has unique symbiotic characteristics. PMID:16349171

Leung, K; Strain, S R; de Bruijn, F J; Bottomley, P J

1994-02-01

128

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)

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

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

2012-09-01

129

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1978-01-01

130

Rhizobium strains competitiveness on bean nodulation in Cerrado soils Capacidade competitiva de estirpes de Rhizobium na nodulação do feijoeiro em solos de Cerrado  

Directory of Open Access Journals (Sweden)

Full Text Available The objective of this work was to identify the most competitive and effective Rhizobium strains in order to increase common bean yield by nitrogen fixation as alternative or complementation to the nitrogen fertilization. Competitiveness tests were lead in axenic conditions, in Cerrado soil pots and in three field experiments, with native Rhizobium strains that were previously identified, according to their effectiveness and genetic variability. The identification of strains in nodules was performed using serological tests (axenic conditions - agglutination and enzyme linked immunosorbent (Elisa assays - and random amplified polymorfic DNA (RAPD (Cerrado soil. Plant yield was determined using the dry weight (greenhouse conditions, total N and grain yield (field experiments. Among the analyzed Rhizobium strains, native strain SLA 2.2 and commercial strain CIAT 899 were the dominant nodules in plants of the most productive plots, presenting yield productivity similar or higher to those obtained in treatments where 20 kg ha-1 of N were applied.O objetivo deste trabalho foi identificar as estirpes de Rhizobium mais efetivas e competitivas, a fim de maximizar a produtividade do feijoeiro por meio da fixação de nitrogênio, como alternativa à adubação nitrogenada. Foram conduzidos testes de competitividade em condições axênicas, em vasos com solo do Cerrado e em três experimentos de campo, com estirpes de Rhizobium nativas, previamente selecionadas quanto à efetividade e à variabilidade genética. A identificação das estirpes nos nódulos foi efetuada por meio das técnicas de aglutinação e ensaio imunoabsorvente de ligação de enzimas (Elisa, em condições de casa de vegetação, e pela técnica de DNA polimórfico amplificado ao acaso (RAPD, em solo de Cerrado. A produtividade das plantas foi determinada pela produção de matéria seca, teor de N e produção de grãos (condições de campo. A estirpe nativa SLA 2.2 e a estirpe comercial CIAT 899 foram dominantes nos nódulos das plantas das parcelas mais produtivas, com índices de produtividade iguais ou superiores aos obtidos nos tratamentos em que foram aplicados 20 kg ha-1 de N.

Ruy Raposeiras

2006-03-01

131

SYNERGISTIC INTERACTION BETWEEN ARBUSCULAR MYCORRHIZAL FUNGI, RHIZOBIUM AND PHOSPHATE SOLUBILISING BACTERIA ON VIGNA UNGUICULATA (L VERDC.  

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Full Text Available Green house pot experiments were conducted to evaluate the effect of Arbuscular Mycorrhizal(AM Fungi (Funneliformis mosseae along with the dual inoculation of AM fungi (Funneliformis mosseae with Rhizobium, Phosphate solubilising bacteria (PSB and a triple inoculation of AM Fungi (Funneliformis mosseae, Rhizobium, and PSB in Vigna unguiculata (L Verdc. Growth parameters such as plant height, dry weight of root and shoot, spore number, per cent root colonization, number of nodules was recorded and P and N uptake were estimated at the intervals of 15, 30 and 45 days. Results revealed that inoculation of AM Fungi (Funneliformis mosseae + Rhizobium+ PSB showed an increase in all the growth parameters when compared with dual inoculation. The combined inoculation of bacteria and AM fungi evidence provide that these two organisms are synergistically involved in the beneficial effects of Vigna unguiculata (L Verdc.

Romana M Mirdhe* and HC Lakshman

2014-05-01

132

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

DEFF Research Database (Denmark)

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.

SkØt, Leif

1983-01-01

133

Yield response of fidders (berseem, shaftal, and lucerne) to rhizobium inclulation  

International Nuclear Information System (INIS)

Investigations were carried out to know the effect of Rhizobium inoculation on the fodder yield and nitrogen fixation of berseem, shaftal and lucerne in y clay loam soil in a pot culture experiment. A basal dressing of nitrogen, phosphorus (P/sub 2/O/sub 5/) and Potash (K/sub 2/O) at 20,80,40 Kg/ha as urea, single superphosphate and potassium sulphate were applied to each pot. The results revealed that Rhizobium inoculation significantly increased the green fodder yield in four cuttings of berseem by 35 to 147 percent of shaftal by 41 to 60 percent and of lucerne by 41 to 74 percent. Shoos N-yield in four cuttings exhibited a significant increasing trend by 21 to 158 percent in berseem, 40 to 69 percent in shaftal and 41 to 78 percent in lucerne due to biological nitrogen fixation as a result of Rhizobium inoculation. (author)

134

Herbivores alter the fitness benefits of a plant-rhizobium mutualism  

Science.gov (United States)

Mutualisms are best understood from a community perspective, since third-party species have the potential to shift the costs and benefits in interspecific interactions. We manipulated plant genotypes, the presence of rhizobium mutualists, and the presence of a generalist herbivore and assessed the performance of all players in order to test whether antagonists might alter the fitness benefits of plant-rhizobium mutualism, and vice versa how mutualists might alter the fitness consequences of plant-herbivore antagonism. We found that plants in our experiment formed more associations with rhizobia (root nodules) in the presence of herbivores, thereby increasing the fitness benefits of mutualism for rhizobia. In contrast, the effects of rhizobia on herbivores were weak. Our data support a community-dependent view of these ecological interactions, and suggest that consideration of the aboveground herbivore community can inform ecological and evolutionary studies of legume-rhizobium interactions.

Heath, Katy D.; Lau, Jennifer A.

2011-03-01

135

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

Directory of Open Access Journals (Sweden)

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.

SRI PURWANINGSIH

2005-04-01

136

Studies on mutation and repair in Rhizobium japonicum  

International Nuclear Information System (INIS)

In the presence of NTG, Rhizobium japonicum loses viability very rapidly. 50% survival is achieved within 4 mins using 50 ?gm/ml. When a constant time of 30 min is maintained then a concentration of 18 ?gm/ml gives 50% survival. The low doses of NTG did not yield any auxotrophs. The antibiotics like penicillion, ampicillin and streptopenicillin were used as agents for enrichment of mutants, ampicillin was quite effective. A fairly efficient mechanism for repair from U.V. damage appears to exist. A greater part of this repair is due to the prevalence of dark repair mechanism. Mutants with increased sensitivity to U.V. repair failed to transform normally suggesting that the two processes of U.V. repair and genetic recombination may be related. The levels of deoxyribonucleases increased at the competent state. The activity at pH 7.5 and 8.4 but not at 5.5 was greater towards irradiated DNA, a prerequisite for any enzyme involved in U.V. repair. (author)

137

Differentiating Indigenous Soybean Bradyrhizobium and Rhizobium spp. of Indian Soils.  

Science.gov (United States)

Soybean is extensively cultivated worldwide and is the largest source of biologically fixed nitrogen among legumes. It is nodulated by both slow and fast growing rhizobia. Indigenous soybean rhizobia in Vertisols of central India were assessed for utilization of 35 carbon sources and intrinsic resistance to 19 antibiotics. There was greater utilization of trehalose and raffinose by fast growers (87 and 73 % by fast vs. 35 and 30 % by slow growers); but slow growers had higher ability to utilize glucosamine (75 % by slow vs. 33 % by fast growers). A larger proportion of slow growers were resistant to vancomycin, polymyxin-B and rifampicin (70, 65 and 55 %) compared to fast growers (13, 7 and 7 % each). Among the two 16S rRNA sequence types in the slow growers, those belonging to Bradyrhizobium spp. utilized glucosamine while those belonging to Rhizobium radiobacter did not. All the fast growers had 16S rRNA homology to R. radiobacter and majority could not utilize glucosamine. It is suggested that during initial isolations and screening of rhizobia in strain selection programmes, using carbon sources like glucosamine and antibiotics like vancomycin, polymyxin-B and rifampicin in the media may provide a simple way of distinguishing Bradyrhizobium strains from R. radiobacter among the slow growers. PMID:25320421

Ansari, Parveen G; Rao, D L N

2014-06-01

138

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

Science.gov (United States)

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

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

2012-06-01

139

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

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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.

Akimova G.P.

2010-11-01

140

Genetic characterization and nitrogen fixation capacity of Rhizobium strains on common bean / Caracterização genética e capacidade de fixação de nitrogênio de estirpes de Rhizobium em feijoeiro  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste trabalho foi a caracterização genética de quatro novas estirpes de Rhizobium e a avaliação de sua capacidade de fixação de N2 e nodulação, comparadas a estirpes comerciais e à população nativa de rizóbios de um Latossolo Vermelho. Dois experimentos foram conduzidos em blocos ao acas [...] o, em casa de vegetação. No primeiro experimento, conduzido em tubetes com vermiculita, avaliaram-se a nodulação e a capacidade de fixação das novas estirpes, em comparação com as estirpes comerciais CIAT-899 e PRF-81 e com a população nativa do solo. Das colônias puras isoladas, extraiu-se o DNA genômico e realizou-se o seqüenciamento do espaço intergênico, para a caracterização genética das estirpes e da população nativa de rizóbios. O segundo experimento foi realizado em vasos com solo, para determinação da produtividade e da nodulação do feijoeiro, cultivar Pérola, com o uso das estirpes isoladamente ou em mistura com a PRF-81. A população nativa do solo foi identificada como Rhizobium sp. e se mostrou ineficiente na fixação de nitrogênio. Foram encontradas três espécies de Rhizobium entre as quatro novas estirpes. As estirpes LBMP-4BR e LBMP-12BR estão entre as que têm maior capacidade de nodulação e fixação de N2, e apresentam respostas diferenciadas quando misturadas à PRF-81. Abstract in english This study aimed to genetically characterize four new Rhizobium strains, and to evaluate their nodulation and fixation capacity compared to commercial strains and to native rhizobia population of a Brazilian Rhodic Hapludox. Two experiments were carried out in randomized blocks design, under greenho [...] use conditions, in 2007. In the first experiment, the nodulation and nitrogen fixation capacity of new strains were evaluated, in comparison to the commercial strains CIAT-899 and PRF-81 and to native soil population. It was carried out in plastic tubes filled with vermiculite. DNA extractions and PCR sequencing of the intergenic space were made from the isolated pure colonies, in order to genetically characterize the strains and the native rhizobia population. In the second experiment, the nodulation and productivity of common beans Perola cultivar were determined, with the use of evaluated strains, alone or in mixture with PRF-81 strain. It was carried out in pots filled with soil. The native soil population was identified as Rhizobium sp. and was inefficient in nitrogen fixation. Three different Rhizobium species were found among the four new strains. The LBMP-4BR and LBMP-12BR new strains are among the ones with greatest nodulation and fixation capacity and exhibit differential responses when mixed to PRF-81.

Tehuni Orlando, González; João Carlos, Campanharo; Eliana Gertrudes de Macedo, Lemos.

1177-11-01

 
 
 
 
141

Genetic characterization and nitrogen fixation capacity of Rhizobium strains on common bean Caracterização genética e capacidade de fixação de nitrogênio de estirpes de Rhizobium em feijoeiro  

Directory of Open Access Journals (Sweden)

Full Text Available This study aimed to genetically characterize four new Rhizobium strains, and to evaluate their nodulation and fixation capacity compared to commercial strains and to native rhizobia population of a Brazilian Rhodic Hapludox. Two experiments were carried out in randomized blocks design, under greenhouse conditions, in 2007. In the first experiment, the nodulation and nitrogen fixation capacity of new strains were evaluated, in comparison to the commercial strains CIAT-899 and PRF-81 and to native soil population. It was carried out in plastic tubes filled with vermiculite. DNA extractions and PCR sequencing of the intergenic space were made from the isolated pure colonies, in order to genetically characterize the strains and the native rhizobia population. In the second experiment, the nodulation and productivity of common beans Perola cultivar were determined, with the use of evaluated strains, alone or in mixture with PRF-81 strain. It was carried out in pots filled with soil. The native soil population was identified as Rhizobium sp. and was inefficient in nitrogen fixation. Three different Rhizobium species were found among the four new strains. The LBMP-4BR and LBMP-12BR new strains are among the ones with greatest nodulation and fixation capacity and exhibit differential responses when mixed to PRF-81.O objetivo deste trabalho foi a caracterização genética de quatro novas estirpes de Rhizobium e a avaliação de sua capacidade de fixação de N2 e nodulação, comparadas a estirpes comerciais e à população nativa de rizóbios de um Latossolo Vermelho. Dois experimentos foram conduzidos em blocos ao acaso, em casa de vegetação. No primeiro experimento, conduzido em tubetes com vermiculita, avaliaram-se a nodulação e a capacidade de fixação das novas estirpes, em comparação com as estirpes comerciais CIAT-899 e PRF-81 e com a população nativa do solo. Das colônias puras isoladas, extraiu-se o DNA genômico e realizou-se o seqüenciamento do espaço intergênico, para a caracterização genética das estirpes e da população nativa de rizóbios. O segundo experimento foi realizado em vasos com solo, para determinação da produtividade e da nodulação do feijoeiro, cultivar Pérola, com o uso das estirpes isoladamente ou em mistura com a PRF-81. A população nativa do solo foi identificada como Rhizobium sp. e se mostrou ineficiente na fixação de nitrogênio. Foram encontradas três espécies de Rhizobium entre as quatro novas estirpes. As estirpes LBMP-4BR e LBMP-12BR estão entre as que têm maior capacidade de nodulação e fixação de N2, e apresentam respostas diferenciadas quando misturadas à PRF-81.

Tehuni Orlando González

2008-09-01

142

Genetic characterization and nitrogen fixation capacity of Rhizobium strains on common bean / Caracterização genética e capacidade de fixação de nitrogênio de estirpes de Rhizobium em feijoeiro  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo deste trabalho foi a caracterização genética de quatro novas estirpes de Rhizobium e a avaliação de sua capacidade de fixação de N2 e nodulação, comparadas a estirpes comerciais e à população nativa de rizóbios de um Latossolo Vermelho. Dois experimentos foram conduzidos em blocos ao acas [...] o, em casa de vegetação. No primeiro experimento, conduzido em tubetes com vermiculita, avaliaram-se a nodulação e a capacidade de fixação das novas estirpes, em comparação com as estirpes comerciais CIAT-899 e PRF-81 e com a população nativa do solo. Das colônias puras isoladas, extraiu-se o DNA genômico e realizou-se o seqüenciamento do espaço intergênico, para a caracterização genética das estirpes e da população nativa de rizóbios. O segundo experimento foi realizado em vasos com solo, para determinação da produtividade e da nodulação do feijoeiro, cultivar Pérola, com o uso das estirpes isoladamente ou em mistura com a PRF-81. A população nativa do solo foi identificada como Rhizobium sp. e se mostrou ineficiente na fixação de nitrogênio. Foram encontradas três espécies de Rhizobium entre as quatro novas estirpes. As estirpes LBMP-4BR e LBMP-12BR estão entre as que têm maior capacidade de nodulação e fixação de N2, e apresentam respostas diferenciadas quando misturadas à PRF-81. Abstract in english This study aimed to genetically characterize four new Rhizobium strains, and to evaluate their nodulation and fixation capacity compared to commercial strains and to native rhizobia population of a Brazilian Rhodic Hapludox. Two experiments were carried out in randomized blocks design, under greenho [...] use conditions, in 2007. In the first experiment, the nodulation and nitrogen fixation capacity of new strains were evaluated, in comparison to the commercial strains CIAT-899 and PRF-81 and to native soil population. It was carried out in plastic tubes filled with vermiculite. DNA extractions and PCR sequencing of the intergenic space were made from the isolated pure colonies, in order to genetically characterize the strains and the native rhizobia population. In the second experiment, the nodulation and productivity of common beans Perola cultivar were determined, with the use of evaluated strains, alone or in mixture with PRF-81 strain. It was carried out in pots filled with soil. The native soil population was identified as Rhizobium sp. and was inefficient in nitrogen fixation. Three different Rhizobium species were found among the four new strains. The LBMP-4BR and LBMP-12BR new strains are among the ones with greatest nodulation and fixation capacity and exhibit differential responses when mixed to PRF-81.

Tehuni Orlando, González; João Carlos, Campanharo; Eliana Gertrudes de Macedo, Lemos.

143

Étude dans les états finals dileptoniques de différentes propriétés des paires top-antitop avec les détecteurs D0 et ATLAS  

CERN Document Server

Les études de différentes propriétés des paires top-antitop dans l’état final dileptonique sont présentées dans cette thèse. Deux analyses ont été réalisées dans des expériences différentes : l’une à D0 auprès du Tevatron, l’autre dans ATLAS auprès du LHC. Les deux collisionneurs étant différents, les mesures qui y sont réalisées sont complémentaires pour les études des propriétés du top.  La première analyse, réalisée dans l’expérience D0, a consisté à faire une mesure simultanée de la section efficace de production des paires top-antitop et du rapport d’embranchement t -> Wb Cette mesure a été réalisée dans le canal dileptonique avec un lot de données correspondant à une luminosité de 5,4 fb?¹. Elle a ensuite été combinée avec la mesure réalisée dans le canal semileptonique pour obtenir une précision de 8% sur la section efficace, comparable à la précision des calculs théoriques. La deuxième analyse présentée, réalisée dans l’expérience A...

Deterre, Cécile; Déliot, Frédéric

144

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

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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.

2007-01-01

145

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

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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 inoculan...

Danielle Camargo; Kelly Lopes Bispo; Luciane Sene

2011-01-01

146

In vitro activity of the nitrogen fixation regulatory protein FIXJ from Rhizobium meliloti.  

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Cell extracts of an Escherichia coli strain that overproduces the regulatory protein FIXJ from Rhizobium meliloti promoted transcription of fixK, a known FIXJ-dependent gene, in a coupled transcription-translation assay. Activation by FIXJ was dependent on the sigma 70 holoenzyme form of RNA polymerase.

Batut, J.; Santero, E.; Kustu, S.

1991-01-01

147

Stimulation of indole-3-acetic acid production in Rhizobium by flavonoids.  

Science.gov (United States)

Flavonoids activate nod gene expression in Rhizobium resulting in the synthesis of Nod signals which trigger organogenesis in the host plant. This paper shows that nod-inducers also stimulate the production of the phytohormone IAA (indole-3-acetic acid). PMID:2026265

Prinsen, E; Chauvaux, N; Schmidt, J; John, M; Wieneke, U; De Greef, J; Schell, J; Van Onckelen, H

1991-04-22

148

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

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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.

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

1999-01-01

149

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

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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.

Agarwal, Leena; Purohit, Hemant J.

2013-01-01

150

Populasi Bakteri Rhizobium di Tanah pada beberapa Tanaman dari Pulau Buton, Kabupaten Muna, Propinsi Sulawesi Tenggara  

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Full Text Available The research was conducted in order to know population of Rhizobium bacteria in the soil at several plant from Buton island, Muna regency, Southeast Sulawesi. The purpose of the study was to get the population data and pure cultures of Rhizobium bacteria. Rhizobium bacteria were isolated from 13 sample from rhizosphere of fruit plant, 14 sample soil from rhizosphere of yield plant, 5 sample soil from rhizosphere of horticulture plant, and 8 samples soil was from forest plant. Isolation was conducted in standard medium of Yeast Extract Mannitol Agar (YEMA, the inoculation at (27-280C, and the population was counted by plate count methods. The growth characteristic of strain was observed by using YEMA medium mixed respectively with Brom Thymol Blue and Congo Red as an indicators. The population of Rhizobium bacteria was in the range of 7-115 × 105 CFU g-1 soil, and the highest population was found from the sample soil from rhizosphere with Ipomea batatas plant. Forty nine gave of pure culture, thirty five isolates can be grouped as fast growing, while fourteen can be grouped as slow growing.

Sri Purwaningsih

2009-01-01

151

[Primary study on acid tolerance mechanism of a wild aciduric Rhizobium strain isolated from Pueraria lobata].  

Science.gov (United States)

An aciduric Rhizobium strain, named as PR389, was isolated from the nodule of wild Pueraria lobata which grew in yellow soil (pH 4.6) on the Jin-yun Mountain in Bei-bei, Chong-qing city. The isolated strain, which could grow under pH 4.6 distinct from the optimal pH 6.5-7.5 for rhizobium, showed some typical features of aciduric rhizobium. This was also confirmed by the proton flux assay. Compared to the acid-sensitive Rhizobium strain PR21, the cell membrane of PR389 could hold back excessive H entering cell. This feature can protect PR389 from harm of acid. In the test of acid tolerance, the aciduric ability of strain PR389 under low acidic (pH 3.8) was restrained by antibiotic chloramphenicol. It was speculated that special proteins in the cells of PR389 could be induced and synthesized in acidic environment. PMID:17037073

Gu, Jian-ping; Zhang, Lei; Wei, Shi-qing; Zhang, Qin; Fang, De-hua

2006-08-01

152

Genetic analysis of a cluster of genes required for synthesis of the calcofluor-binding exopolysaccharide of Rhizobium meliloti.  

Science.gov (United States)

Rhizobium meliloti produces an acidic, Calcofluor-binding exopolysaccharide which plays a role in nodulation of alfalfa plants by this bacterium. We constructed and mapped 102 transposon insertions in a 48-kilobase (kb) region previously shown to contain several exo genes. Mutations affecting production of the Calcofluor-binding exopolysaccharide were clustered in a 22-kb region and fell into 12 complementation groups. Strains carrying mutations in seven of the complementation groups (exoA, exoB, exoF, exoL, exoM, exoP, and exoQ) produced no Calcofluor-binding exopolysaccharide and induced non-nitrogen-fixing nodules on alfalfa. Mutants in an eighth complementation group, exoH (Leigh et al., Cell 51:579-587, 1987), produce an altered exopolysaccharide and also induce the formation of non-nitrogen-fixing nodules. Mutants in the remaining four complementation groups produced less Calcofluor-binding material than the wild type. Mutants carrying mutations in two of these complementation groups (exoK and exoN) formed apparently normal, nitrogen-fixing nodules, while mutants in the other two groups (exoG and exoJ) formed normal nodules less efficiently than the wild type. PMID:2842306

Long, S; Reed, J W; Himawan, J; Walker, G C

1988-09-01

153

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

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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.

Ladan Bayat

2014-01-01

154

Evaluation de l'impact bioclinique et social, individuel et collectif, du traitement ARV chez des patients VIH-1 pris en charge depuis 10 ans dans le cadre de l'ISAARV - Cohorte ANRS 1215. Rapport final  

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Ce rapport rassemble les résultats des études réalisées entre 2009 et 2011 au Sénégal dans le cadre du programme de recherche ANRS 1215 qui avait pour objectif de documenter l'impact à long terme de la prise en charge thérapeutique par les médicaments antirétroviraux. Les 400 participants de la cohorte ANRS 1215 ont débuté leur traitement entre 1998 et 2002, ils font partie des premières personnes vivant avec le VIH en Afrique à avoir reçu des traitements ARV. Ces études ont ?...

Taverne, Bernard; Desclaux, Alice; Sow, Papa-salif; Delaporte, Eric; Ndoye, Ibra

2012-01-01

155

Mass Spectrometric Quantification of Indole-3-Acetic Acid in Rhizobium Culture Supernatants: Relation to Root Hair Curling and Nodule Initiation  

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Indole-3-acetic acid (IAA) has been unequivocally identified in culture supernatants of Rhizobium strains by gas chromatography-mass spectrometry. A method for accurately quantitating IAA in bacterial culture supernatants, employing deuterium-labeled IAA as an internal standard, has been developed. Similar IAA concentrations were found in culture supernatants of chosen Rhizobium mutants (defective in nodule formation) and their corresponding parent strains. Since some of the mutants are known...

Badenoch-jones, Jane; Summons, R. E.; Djordjevic, M. A.; Shine, J.; Letham, D. S.; Rolfe, B. G.

1982-01-01

156

First genomic analysis of the broad-host-range Rhizobium sp. LPU83 strain, a member of the low-genetic diversity Oregon-like Rhizobium sp. group.  

Science.gov (United States)

Alfalfa (Medicago sativa) is the most cultivated forage legume for cattle and animal feeding, occupying about 32 million hectares over the world. Management of the N?-fixing symbiosis of this plant to maximize crop production is therefore an important objective. A fundamental constraint to this aim emerges when a moderately low soil pH hampers the establishment of an effective symbiosis with indigenous and/or inoculated rhizobia. Besides the association of alfalfa with Ensifer (Sinorhizobium) meliloti, this legume is able to establish a symbiosis with Ensifer (Sinorhizobium) medicae and with less characterized types of rhizobia, such as the Oregon-like strains, Rhizobium sp. Or191 initially isolated in the USA, and the Rhizobium sp. LPU83 strain, from Argentina. These strains are acid-tolerant, highly competitive for acidic-soil-alfalfa nodulation, but inefficient for biological nitrogen fixation with alfalfa. These features position the Oregon-like rhizobia as strains of potential risk in agricultural soils compared with the efficient symbiont E. meliloti. Moreover, the collected genetic information has revealed that the genomic structure of these rhizobial isolates is complex in terms of sequence similarities shared with other rhizobia. Such a "patched" genetic composition has obviously imposed severe restrictions to the classical taxonomy of these rhizobia. In this work we summarize the accumulated knowledge about the Oregon-like rhizobia and present a phylogenetic analysis based on genome sequence data of Rhizobium sp. LPU83 obtained by a high-throughput sequencing on the Genome Sequencer FLX Titanium platform. The accessibility of the complete genomic sequence will release up more experimental possibilities since this information will then enable biochemical studies as well as proteomics and transcriptomics approaches. PMID:21329739

Tejerizo, Gonzalo Torres; Del Papa, María Florencia; Draghi, Walter; Lozano, Mauricio; Giusti, María de Los Ángeles; Martini, Carla; Salas, María Eugenia; Salto, Ileana; Wibberg, Daniel; Szczepanowski, Rafael; Weidner, Stefan; Schlüter, Andreas; Lagares, Antonio; Pistorio, Mariano

2011-08-20

157

Caracterização química dos géis produzidos pelas bactérias diazotróficas Rhizobium tropici e Mesorhizobium sp. Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp.  

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Full Text Available The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPS RT and Mesorhizobium sp (EPS MR 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 EPS RT and EPS MR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, ¹H and 13C-NMR.

Nilson Kobori Monteiro

2012-01-01

158

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1981-05-01

159

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)

160

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

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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.

Mihaela Blažinkov

2007-06-01

 
 
 
 
161

Formation of tumor-like structures on legume roots by Rhizobium.  

Science.gov (United States)

Tumor-like structures appeared on the roots of Medicago sativa, Alysicarpus vaginalis, and Trifolium pratense inoculated with a non-nodulating strain of Rhizobium trifolii or with irradiated cultures of either of two nodulating Rhizobium strains. The structures were composed of disorganized plant tissues which, on the basis of microscopic examination, were devoid of bacterial cells. Rhizobia which could nodulate legumes of one cross-inoculation group and which were able to induce formation of such tumor-like structures on plants of a second cross-inoculation group were isolated from extracts of these root growths. The apparent tumorogenic activity of some of the rhizobia, but not their nodulating capacity, was lost when the bacteria were transferred in laboratory media. PMID:4995381

MacGregor, A N; Alexander, M

1971-03-01

162

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

Science.gov (United States)

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

Sánchez-Cañizares, Carmen; Palacios, Jose

2013-03-01

163

Common loci for Agrobacterium tumefaciens and Rhizobium meliloti exopolysaccharide synthesis and their roles in plant interactions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mutants of Rhizobium meliloti have been isolated which are deficient in exopolysaccharide (EPS) production and effective nodulation of alfalfa (J. A. Leigh, E. R. Signer, and G. C. Walker, Proc. Natl. Acad. Sci. USA 82:6231-6235, 1985). We isolated approximately 100 analogous EPS-deficient (Exo) mutants of the closely related plant pathogen Agrobacterium tumefaciens, including strains whose EPS deficiencies were specifically complemented by each of five cloned R. meliloti exo loci. We also cl...

Cangelosi, G. A.; Hung, L.; Puvanesarajah, V.; Stacey, G.; Ozga, D. A.; Leigh, J. A.; Nester, E. W.

1987-01-01

164

Genetic diversity of an Italian Rhizobium meliloti population from different Medicago sativa varieties.  

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We investigated the genetic diversity of 96 Rhizobium meliloti strains isolated from nodules of four Medicago sativa varieties from distinct geographic areas and planted in two different northern Italian soils. The 96 isolates, which were phenotypically indistinguishable, were analyzed for DNA polymorphism with the following three methods: (i) a randomly amplified polymorphic DNA (RAPD) method, (ii) a restriction fragment length polymorphism (RFLP) analysis of the 16S-23S ribosomal operon spa...

Paffetti, D.; Scotti, C.; Gnocchi, S.; Fancelli, S.; Bazzicalupo, M.

1996-01-01

165

Influence of Glycine spp. on Competitiveness of Bradyrhizobium japonicum and Rhizobium fredii  

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The displacement of indigenous Bradyrhizobium japonicum in soybean nodules with more effective strains offers the possibility of enhanced N2 fixation in soybean (Glycine max (L.) Merr.). Our objective was to determine whether the wild soybean (G. soja Sieb. & Zucc.) genotype PI 468397 would cause reduced competitiveness of important indigenous B. japonicum strains USDA 31, 76, and 123 and thereby permit nodulation by Rhizobium fredii, the fast-growing microsymbiont of soybean. In an initial e...

Cregan, P. B.; Keyser, H. H.

1988-01-01

166

Bouvard et Pécuchet et le désir amoureux  

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Full Text Available L’article propose une étude de genèse du chapitre 7 de Bouvard et Pécuchet, consacré à l’amour, qui forme une étape encyclopédique a priori un peu surprenante. Flaubert s’amuse à écrire ces aventures de Bouvard et Pécuchet, dans un pays qui n’est pas si tendre. L’étude de genèse porte sur le travail de l’écriture de plusieurs temps forts du chapitre (dans l’incipit, et les scènes de duos, notamment la scène entre Mme Castillon et Gorgu. Elle permet de montrer l’effacement de détails érotiques, mais aussi du politique et de l’histoire, qui se trouvent condensés dans le texte final. Elle révèle aussi le rôle concerté de ce chapitre dans la construction du roman et l’itinéraire des personnages. Anodin en apparence, ce chapitre est emblématique d’une poétique fondée sur l’ellipse, et qui mêle le jeu et le sérieux.This article presents a textual genetics study of Bouvard et Pécuchet’s 7th chapter, about love, which appears to be a surprising encyclopedic stage of the novel. Flaubert has fun writing these adventures in a not so tender country. This genetics study focuses on the writing of several key moments of the chapter (in the beginning and the duo scenes, such as the one between Mme Castillon and Gorgu. It reveals the erasure of erotic details, as well as politics and history, which end up condensed in the final text. It also shows this chapter’s concerted role in the construction of the novel and the characters’ development. Apparently minor, this chapter is emblematic of a poetics founded on the ellipsis, mingling play and seriousness.

Anne Herschberg Pierrot

2010-09-01

167

Basis for the competitiveness of Rhizobium japonicum in nodulation of soybean. Final progress report  

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This study sought to identify molecular, genetic and environmental factors most crucial to the ability of an inoculated strain of rhizobia to nodulate soybean roots in the face of competition from indigenous microorganisms. Co-inoculation of a more efficient strain with a less-efficient strain resulted in the more efficient strain occupying a higher percentage of nodules. When culture conditions became less stringent the less efficient strain became more competitive. The number of infections formed was related in a direct manner to nodulation efficiency. The strain which was more nodulation efficient also was more infection efficient. That the number of infections per se, as determined in a single inoculum, can not be the only factor in determining the competency was indicated by experiments in which one strain formed more total infection yet nodule occupancy was equally distributed. 5 figs., 9 tabs.

Evans, W.R.; Bauer, W.D.

1986-07-30

168

Biochemical Analysis of Chickpea Protection Against Fusarium Wilt Afforded by Two Rhizobium Isolates  

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Full Text Available Germinated seeds of two chickpea cultivars ILC482 and INRAT87/1, respectively susceptible and moderately resistant to Fusarium oxysporum f. sp. ciceris (Foc, were preinoculated with a suspension of two Rhizobium isolates PchDMS and Pch43. Three days later, the seedlings were challenged by root dip with a conidial suspension of Foc race 0. The two Rhizobium isolates protected chickpea plants from F. oxysporum infection; the best protection has been obtained by PchDMS for the two cultivars. For the susceptible cultivar, mortality was 12.5 and 33.33% for treated plants, respectively with PchDMS and Pch43 as compared to the 79.16% in the inoculated control with Foc only. For the INRAT87/1 Cv. mortality was 8.33 and 12.5% for treated plants, respectively with PchDMS and Pch43 compared to the 54.16% in the control inoculated treatment. The two Rhizobium isolates stimulated the peroxidases and polyphenoloxidases activities and induced the accumulation of phenolic compounds. The maximum of peroxidases activities in plant roots were reached 24 h after challenging. However, the higher activity of polyphenoloxidases and the higher level of the phenolic compounds were recorded 72 h after Foc inoculation. Comparing the two strains, PchDMS was more effective in inducing enzymes and phenolic compounds and highest levels were recorded in INRAT87/1 cultivar.

A. Arfaoui

2005-01-01

169

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

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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.

Joši? Dragana

2008-01-01

170

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

Science.gov (United States)

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

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

2014-01-01

171

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

Science.gov (United States)

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

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

2014-11-01

172

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

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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.

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

2012-05-01

173

Effects of salt and pH stress on temperature-tolerant Rhizobium sp. NBRI330 nodulating Prosopis juliflora.  

Science.gov (United States)

A study was conducted to examine the growth response of a rhizobial strain Rhizobium sp. NBRI330 isolated from root nodules of Prosopis juliflora growing in alkaline soil. The strain had the ability to nodulate P. juliflora. Nursery grown plants inoculated with Rhizobium sp. NBRI330 had 60.6% higher plant dry weight, as compared with uninoculated plants. The individual stress survival limit of a rhizobial strain Rhizobium sp. NBRI330 isolated from alkaline soil in a medium containing 32% (wt/vol) salt was 8 h, and at 55 degrees C up to 3 h. The length of Rhizobium sp. NBRI330 in salt-stressed cells increased significantly to 3.04 microm from 1.75 microm of non-stressed control cells. On the contrary, the length of pH-stressed cells declined to 1.40 microm. Compared with non-stressed control rod-shaped cells, the shape of temperature-stressed cells changed to spherical, of 0.42 microm diameter. High temperature (45 degrees C) was tolerated efficiently by Rhizobium sp. NBRI330 in the presence of salt at pH 12, as compared with pH 7. PMID:10688689

Kulkarni, S; Nautiyal, C S

2000-04-01

174

Effect of Rhizobium japonicum Inoculum Doses (Liquid Culture on the Growth and Seed Yield of Soybean Crop  

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Full Text Available 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 Design. The adequate level of 25 ml with 300 grams sand maize as seed treatment inoculant was found more effective for maximum growth and seed yield as compared to higher and lower doses of Rhizobium japonicum. Thus, it was concluded that Rhizobium japonicum exhibited the positive change in terms of enhanced growth and seed yield. The satisfactory results would be achieved if, the soybean seed will be treated with 25 ml of Rhizobium japonicum inoculum.

F. C. Oad

2002-01-01

175

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

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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.

M. Yadegari

2008-01-01

176

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

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Full Text Available 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 Rhizobium genotype in expressing the association effect was more decisive than that of Azospirillum. The cell-free extract of Azospirillum produced the same enhancement effect as that of the organism itself, while the culture supernatant also showed the same in some instances. Since the response to combined inoculation in winged bean was obtained only with one strain of Rhizobium, the factors that could influence the nodulation enhancement were investigated in detail. An attempt was made in finding out the possible mechanism involved in the enhancement effect by Azospirillum.

Iruthayathas, EE.

1985-01-01

177

Colonization and Nitrogenase Activity of Triticum aestivum (cv. Baccross and Mahdavi to the Dual Inoculation with Azospirillum brasilense and Rhizobium meliloti plus 2,4-D  

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Full Text Available The potential enhancement of root colonization and nitrogenase activity of wheat cultivars (Baccross and Mahdavi was studied with application of two Azospirillum brasilense strains (native and Sp7 co-inoculated with two Rhizobium meliloti strains (native and DSMZ 30135. The results indicated that the colonization was different due to the strains and cultivars of wheat were used. Native A. brasilense colonized wheat root better than Sp7 strain. However, Baccross cv. reacted better with native Azospirillum compared to Mahdavi cv. which reacted better with Sp7. When plants inoculated with dual inoculants (SP7 with standard Rhizobium, the colonization of Azospirillum were increased significantly (from 1.67x105 to 22x105 cfu g-1 FW for Baccras cv. and 3.67x105 to 26x105 cfu g-1 FW for Mahdavi cultivar. When the standard Rhizobium as co-inoculants changed to the native Rhizobium, the colonization of Azospirillum was higher when compared to the single inoculants but was almost the same when compared to the standard Rhizobium. When the standard or native strains of Rhizobium used as single inoculation of wheat roots, the number of Rhizobium in the wheat roots were not changed significantly. However, when plants co-inoculated with Rhizobium and Azospirillum, the colonization of Rhizobium was increased. Co-inoculation of standard strain of R. melilot with A. brasilense Sp7 showed that the colonization of Rhizobium were increased from 0.67x105 to 21x105 cfu g-1 FW for Baccross cv. and 0.33x105 to 18x105 cfu g-1 FW for Mahdavi cv. This behavior was the same when inoculation of Rhizobium was happened with the native one. In dual inoculation, the highest nitrogenase activity was measured in combination of the local strains (native A. brasilense with the native R. meliloti and the lower one belongs to the combination of standard strains (Sp7 with standard R. meliloti. The difference in nirtogenase activity for different cultivars of wheat with Sp7 and standard Rhizobium is not significant but the difference for Sp7 strain plus native Rhizobium is significant (p>0.05. However, the differences were not significant (p<0.05 for nitrogenase activity in bacterial tubes, the difference for nitrogenase activity of co-inoculated plants with combination of Sp7 and Rhizobium either standard or native were significantly different

Askary Mehry

2008-01-01

178

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)

179

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  

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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.

Isnia Aparecida de Oliveira

2000-03-01

180

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)

 
 
 
 
181

Inoculation of the Nonlegume Capsicum annuum (L.) with Rhizobium Strains. 1. Effect on Bioactive Compounds, Antioxidant Activity, and Fruit Ripeness.  

Science.gov (United States)

Pepper (Capsicum annuum L.) is an economically important agricultural crop and an excellent dietary source of natural colors and antioxidant compounds. The levels of these compounds can vary according to agricultural practices, like inoculation with plant growth-promoting rhizobacteria. In this work we evaluated for the first time the effect of the inoculation of two Rhizobium strains on C. annuum metabolites and bioactivity. The results revealed a decrease of organic acids and no effect on phenolics and capsaicinoids of leaves from inoculated plants. In the fruits from inoculated plants organic acids and phenolic compounds decreased, showing that fruits from inoculated plants present a higher ripeness stage than those from uninoculated ones. In general, the inoculation with Rhizobium did not improve the antioxidant activity of pepper fruits and leaves. Considering the positive effect on fruit ripening, the inoculation of C. annuum with Rhizobium is a beneficious agricultural practice for this nonlegume. PMID:24404842

Silva, Luís R; Azevedo, Jessica; Pereira, Maria J; Carro, Lorena; Velazquez, Encarna; Peix, Alvaro; Valentão, Patrícia; Andrade, Paula B

2014-01-22

182

STUDY OF INTERACTIVE EFFECT OF RHIZOBIUM, AZOTOBACTER AND TRICHODERMA ALONE AND IN COMBINATION ON TRIGONELLA FOENUM-GRACEUM L  

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Full Text Available Trigonella foenum-graceum L. has unique ability to maintain a high protein level throughout the growing season therefore it is cultivated as a commercial crop. The use of biofertilizers on Trigonella plant showed the significant effect on growth and leaf, seed protein content. Compared to control shoot length and root length was more in the pot containing different biofertilizers. The total Chlorophyll content was maximum in the leaves of plants grown in the pot containing 50 gm of Rhizobium and 50 gm Azotobacter. The maximum leaf protein content was noticed in the plant grown in the pot containing 50 gm of Rhizobium and 50 gram of Azotobacter. The maximum seed protein was noticed in the plants grown in soil containing 50 gm of Rhizobium and 50 gm of Azotobacter.

PATIL VILAS ARJUN

2013-01-01

183

“STUDY OF INTERACTIVE EFFECT OF RHIZOBIUM, AZOTOBACTER AND TRICHODERMA ALONE AND IN COMBINATION ON TRIGONELLA FOENUM-GRACEUM L.”  

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Full Text Available Trigonella foenum-graceum L. has unique ability to maintain a high protein level throughout the growing season therefore it is cultivated as a commercial crop. The use of biofertilizers on Trigonella plant showed the significant effect on growth and leaf, seed protein content. Compared to control shoot length and root length was more in the pot containing different biofertilizers. The total Chlorophyll content was maximum in the leaves of plants grown in the pot containing 50 gm of Rhizobium and 50 gm Azotobacter. The maximum leaf protein content was noticed in the plant grown in the pot containing 50 gm of Rhizobium and 50 gram of Azotobacter. The maximum seed protein was noticed in the plants grown in soil containing 50 gm of Rhizobium and 50 gm of Azotobacter.

PATIL V. A.

2013-04-01

184

Comparative response of Pisum sativum nodulated with indigenous soil Rhizobium populations and/or co-inoculated with a Rhizobium leguminosarum strain. I. Acetylene-reducing, dihydrogen- and carbon dioxide-evolving activities.  

Science.gov (United States)

No significant differences in the acetylene-reducing activity and evolution of H2 and CO2 from nodulated roots of Pisum sativum inoculated with soil Rhizobium populations from two soils with different acidities (Ruzyn? soil 7.6; Lukavec soil 4.9) were observed. Rhizobium population from Lukavec soil formed nodules, exhibiting a higher H2 evolution. Co-inoculation with the Hup+ strain 128C30 (7 x 10(7) cells per seedling) eliminated, to some extent, the effect of soil populations on physiological activity. PMID:1841862

Skrdleta, V; N?mcová, M; Lisá, L; Novák, K; Kovárová, D

1991-01-01

185

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

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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...

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

1995-01-01

186

Caracterização química dos géis produzidos pelas bactérias diazotróficas Rhizobium tropici e Mesorhizobium sp. / Chemical characterization of the gels produced by the diazotrophic bacteria Rhizobium tropici and Mesorhizobium sp.  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english The exopolysaccharides with characteristics of gel produced by Rhizobium tropici (EPS RT) and Mesorhizobium sp (EPS MR) 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 p [...] resence of uronic acid, pyruvate and acetyl-substituents in the structures of both polymers. Experiments of gel permeation chromatography and polyacrylamide gel electrophoresis showed that EPS RT and EPS MR are homogeneous molecules with low grade of polydispersity. The EPS were characterized using spectroscopic techniques of FT-IR, ¹H and 13C-NMR.

Nilson Kobori, Monteiro; Gabriel, Aranda-Selverio; Diego Tadeu Degli, Exposti; Maria de Lourdes Corradi da, Silva; Eliana Gertrudes Macedo, Lemos; João Carlos, Campanharo; Joana Léa Meira, Silveira.

187

Genome sequence of the beta-rhizobium Cupriavidus taiwanensis and comparative genomics of rhizobia.  

Science.gov (United States)

We report the first complete genome sequence of a beta-proteobacterial nitrogen-fixing symbiont of legumes, Cupriavidus taiwanensis LMG19424. The genome consists of two chromosomes of size 3.42 Mb and 2.50 Mb, and a large symbiotic plasmid of 0.56 Mb. The C. taiwanensis genome displays an unexpected high similarity with the genome of the saprophytic bacterium C. eutrophus H16, despite being 0.94 Mb smaller. Both organisms harbor two chromosomes with large regions of synteny interspersed by specific regions. In contrast, the two species host highly divergent plasmids, with the consequence that C. taiwanensis is symbiotically proficient and less metabolically versatile. Altogether, specific regions in C. taiwanensis compared with C. eutrophus cover 1.02 Mb and are enriched in genes associated with symbiosis or virulence in other bacteria. C. taiwanensis reveals characteristics of a minimal rhizobium, including the most compact (35-kb) symbiotic island (nod and nif) identified so far in any rhizobium. The atypical phylogenetic position of C. taiwanensis allowed insightful comparative genomics of all available rhizobium genomes. We did not find any gene that was both common and specific to all rhizobia, thus suggesting that a unique shared genetic strategy does not support symbiosis of rhizobia with legumes. Instead, phylodistribution analysis of more than 200 Sinorhizobium meliloti known symbiotic genes indicated large and complex variations of their occurrence in rhizobia and non-rhizobia. This led us to devise an in silico method to extract genes preferentially associated with rhizobia. We discuss how the novel genes we have identified may contribute to symbiotic adaptation. PMID:18490699

Amadou, Claire; Pascal, Géraldine; Mangenot, Sophie; Glew, Michelle; Bontemps, Cyril; Capela, Delphine; Carrère, Sébastien; Cruveiller, Stéphane; Dossat, Carole; Lajus, Aurélie; Marchetti, Marta; Poinsot, Véréna; Rouy, Zoé; Servin, Bertrand; Saad, Maged; Schenowitz, Chantal; Barbe, Valérie; Batut, Jacques; Médigue, Claudine; Masson-Boivin, Catherine

2008-09-01

188

Host-specific regulation of symbiotic nitrogen fixation in Rhizobium leguminosarum biovar trifolii.  

Science.gov (United States)

Strains of Rhizobium leguminosarum bv. trifolii (Rlt) able to form effective nodules on Trifolium ambiguum (Caucasian clover, CC) form ineffective nodules on Trifolium repens (white clover, WC), whereas strains that form effective nodules on WC usually do not nodulate CC. Here, we investigate the genetic basis of the host-specific nitrogen-fixation phenotype of CC rhizobia. A cosmid library of the symbiotic plasmid from the WC rhizobium strain Rlt NZP514 was introduced into the CC rhizobium strain Rlt ICC105. An 18 kb Asp718 fragment containing the nifABHDKEN and fixABCX genes of NZP514 that imparted the Fix(+) phenotype was identified. Tn5 mutagenesis of this region revealed that the nifHDKEN, fixABC and nifB genes were required for the Fix(+) phenotype, but that the nifA gene was not. Introduction of several plasmids containing NZP514 nif/fix genes into an ICC105 nifA mutant strain demonstrated that the NifA protein of ICC105 was able to activate expression of the NZP514 nif/fix genes but not the ICC105 nif/fix genes in WC nodules. Reporter gene fusion studies showed that the host-specific regulation of the nif/fix genes depended on the DNA region between the promoters of the divergently transcribed nifH and fixA genes. We hypothesize that a protein acting either in response to a host-specific signal or in the absence of such a signal is able to bind upstream of the NifA-binding sites and interact with NifA to prevent it activating nif/fix gene expression. PMID:17768261

Miller, Simon H; Elliot, Rachel M; Sullivan, John T; Ronson, Clive W

2007-09-01

189

Kinetics study of pyridine biodegradation by a novel bacterial strain, Rhizobium sp. NJUST18.  

Science.gov (United States)

Biodegradation of pyridine by a novel bacterial strain, Rhizobium sp. NJUST18, was studied in batch experiments over a wide concentration range (from 100 to 1,000 mg l(-1)). Pyridine inhibited both growth of Rhizobium sp. NJUST18 and biodegradation of pyridine. The Haldane model could be fitted to the growth kinetics data well with the kinetic constants ?* = 0.1473 h(-1), K s = 793.97 mg l(-1), K i = 268.60 mg l(-1) and S m = 461.80 mg l(-1). The true ? max, calculated from ?*, was found to be 0.0332 h(-1). Yield coefficient Y X/S depended on S i and reached a maximum of 0.51 g g(-1) at S i of 600 mg l(-1). V max was calculated by fitting the pyridine consumption data with the Gompertz model. V max increased with initial pyridine concentration up to 14.809 mg l(-1) h(-1). The q S values, calculated from [Formula: see text], were fitted with the Haldane equation, yielding q Smax = 0.1212 g g(-1) h(-1) and q* = 0.3874 g g(-1) h(-1) at S m' = 507.83 mg l(-1), K s' = 558.03 mg l(-1), and K i' = 462.15 mg l(-1). Inhibition constants for growth and degradation rate value were in the same range. Compared with other pyridine degraders, ? max and S m obtained for Rhizobium sp. NJUST18 were relatively high. High K i and K i' values and extremely high K s and K s' values indicated that NJUST18 was able to grow on pyridine within a wide concentration range, especially at relatively high concentrations. PMID:24425539

Shen, Jinyou; Zhang, Xin; Chen, Dan; Liu, Xiaodong; Zhang, Libin; Sun, Xiuyun; Li, Jiansheng; Bi, Huiping; Wang, Lianjun

2014-06-01

190

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)

191

Genetic analysis of the attenuator of the Rhizobium meliloti trpE(G) gene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It was previously reported that transcription of the Rhizobium meliloti trpE(G) gene starts at the adenine residue of the AUG codon of the leader peptide coding sequence (trpL), suggesting that translation of the trpL sequence starts without the Shine-Dalgarno sequence. We constructed mutations replacing the AUG codon of the trpL sequence with AAG or ACG. These mutations reduced the expression of a trpL'-'lacZ fusion gene to 0.1 and 0.2% of the wild-type level, respectively, indicating that t...

Bae, Y. M.; Stauffer, G. V.

1991-01-01

192

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

193

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

DEFF Research Database (Denmark)

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.

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

1990-01-01

194

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

Science.gov (United States)

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.

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

1995-07-01

195

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

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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.

Akimova G. P.

2012-11-01

196

The PTS(Ntr) system globally regulates ATP-dependent transporters in Rhizobium leguminosarum.  

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Mutation of ptsP encoding EI(Ntr) of the PTS(Ntr) system in Rhizobium leguminosarum strain Rlv3841 caused a pleiotropic phenotype as observed with many bacteria. The mutant formed dry colonies and grew poorly on organic nitrogen or dicarboxylates. Most strikingly the ptsP mutant had low activity of a broad range of ATP-dependent ABC transporters. This lack of activation, which occurred post-translationally, may explain many of the pleiotropic effects. In contrast proton-coupled transport sy...

Prell, J.; Mulley, G.; Haufe, F.; White, Jp; Williams, A.; Karunakaran, R.; Downie, Ja; Poole, Ps

2012-01-01

197

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

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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 ...

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

1986-01-01

198

Electron transport components involved in hydrogen oxidation in free-living Rhizobium japonicum.  

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Membranes from free-living Rhizobium japonicum were isolated to study electron transport components involved in H2 oxidation. The H2/O2 uptake rate ratio in membranes was approximately 2. The electron transport inhibitors antimycin A, cyanide, azide, hydroxylamine, and 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited H2 uptake and H2-dependent O2 uptake significantly. H2-reduced minus O2-oxidized absorption difference spectra revealed peaks at 551.5, 560, and 603 nm, indicating the invo...

O Brian, M. R.; Maier, R. J.

1982-01-01

199

Involvement of cytochromes and a flavoprotein in hydrogen oxidation in Rhizobium japonicum bacteroids.  

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Electron transport components involved in H2 oxidation were studied in membranes from Rhizobium japonicum bacteroids. Hydrogen oxidation in membranes was inhibited by antimycin A and 2-n-heptyl-4-hydroxyquinoline-N-oxide with Ki values of 39.4 and 5.6 microM, respectively. The inhibition of H2 uptake by cyanide was triphasic with Ki values of 0.8, 9.9, and 93.6 microM. This result suggested that three cyanide-reactive components were involved in H2 oxidation. H2-reduced minus O2-oxidized abso...

O Brian, M. R.; Maier, R. J.

1983-01-01

200

CONFIRMING LOCATION OF NITROGEN FIXING GENES ON PLASMIDS IN RHIZOBIUM ISOLATED FROM PISUM SATIVUM  

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Full Text Available To confirm the location of the nitrogen fixing genes whether on the plasmids or on the genomic DNA the Rhizobial isolates isolated from pea (Pisum sativum were treated with acridine orange with various concentrations and fixed nitrogen was estimated from the media in which these rhizobia were grown. There was no significant difference in between the cured and non cured strains of the Rhizobium which proved that the nitrogen fixing genes are not plasmid borne but these are located on the genomic DNA.

Balaji Hajare and Avinash Ade1

2012-06-01

 
 
 
 
201

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

CERN Document Server

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.

Kartashov, A

2013-01-01

202

Draft Genome Sequence of Rhizobium sp. H41, a Rock-Weathering Bacterium from a Weathered Rock Surface.  

Science.gov (United States)

Rhizobium sp. H41 isolated from weathered tuff can weather tuff and release Fe, Si, and Al from the rock under nutrient-poor conditions. Here, we report the draft genome sequence of strain H41, which may facilitate a better understanding of the molecular mechanism involved in rock weathering by the bacterium. PMID:25377707

Xi, Jun; Sheng, Xiafang; He, Linyan

2014-01-01

203

Draft Genome Sequence of Rhizobium sp. H41, a Rock-Weathering Bacterium from a Weathered Rock Surface  

Science.gov (United States)

Rhizobium sp. H41 isolated from weathered tuff can weather tuff and release Fe, Si, and Al from the rock under nutrient-poor conditions. Here, we report the draft genome sequence of strain H41, which may facilitate a better understanding of the molecular mechanism involved in rock weathering by the bacterium. PMID:25377707

Xi, Jun; He, Linyan

2014-01-01

204

Caracterización de la resistencia a metales pesados de cepas de Rhizobium aisladas de suelos ultramáficos y contaminados  

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- Caracterización de la resistencia a altas concentraciones de metales, y en especial a níquel y cobalto en las cepas objeto de estudio. - Determinar si existe una posible correlación entre la presencia del sistema hidrogenasa y la resistencia a altas concentraciones de níquel. - Determinar los mecanismos moleculares implicados en la resistencia a níquel en la cepa de Rhizobium leguminosarum más resistente identificada en este estudio.

Rubio Sanz, Laura

2009-01-01

205

The structure and molecular mechanics calculations of the cyclic (1 ? 2)-?- D-glucan secreted by Rhizobium tropici CIAT 899  

Science.gov (United States)

The structure of the extracellular cyclic (1 ? 2)-?- D-glucan secreted by Rhizobium tropici CIAT 899 has been studied by methylation analysis, 1D and 2D NMR experiments, HPLC and FAB-MS. Molecular mechanics (MM2) and theoretical 3JHH coupling constants calculations were performed.

Gil Serrano, Antonio M.; Franco-Rodríguez, Guillermo; González-Jiménez, Isabel; Tejero-Mateo, Pilar; Molina, José Molina; Dobado, J. A.; Megías, Manuel; Romero, Maria Jesús

1993-12-01

206

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

Science.gov (United States)

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

Corticeiro, Sofia; Freitas, Rosa; Figueira, Etelvina

2013-12-01

207

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

Science.gov (United States)

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

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

2014-01-01

208

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

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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.

Raposeiras Rui

2002-01-01

209

Effects of high temperature on survival, symbiotic performance and genomic modifications of bean nodulating Rhizobium strains  

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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.

Pinto Patrícia P.

1998-01-01

210

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)

211

Revegetating fly ash landfills with Prosopis juliflora L.: impact of different amendments and Rhizobium inoculation.  

Science.gov (United States)

A revegetation trial was conducted to evaluate the feasibility of growing a legume species, Prosopis juliflora L., on fly ash ameliorated with combination of various organic amendments, blue-green algal biofertilizer and Rhizobium inoculation. Significant enhancements in plant biomass, photosynthetic pigments, protein content and in vivo nitrate reductase activity were found in the plants grown on ameliorated fly ash in comparison to the plants growing in unamended fly ash or garden soil. Higher growth was obtained in fly ash amended with blue-green algae (BGA) than farmyard manure or press mud (PM), a waste from sugar-processing industry, due to the greater contribution of plant nutrients, supply of fixed nitrogen and increased availability of phosphorus. Nodulation was suppressed in different amendments of fly ash with soil in a concentration-duration-dependent manner, but not with other amendments. Plants accumulated higher amounts of Fe, Mn, Cu, Zn and Cr in various fly ash amendments than in garden soil. Further, inoculation of the plant with a fly ash tolerant Rhizobium strain conferred tolerance for the plant to grow under fly ash stress conditions with more translocation of metals to the above ground parts. The results showed the potential of P. juliflora to grow in plantations on fly ash landfills and to reduce the metal contents of fly ash by bioaccumulation in its tissues. PMID:14987858

Rai, U N; Pandey, K; Sinha, S; Singh, A; Saxena, R; Gupta, D K

2004-05-01

212

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

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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.

Kumari, B. S.

2010-01-01

213

Carotenoids of rhizobia. II. The effect of nicotine on the carotenoid pattern of Rhizobium lupini.  

Science.gov (United States)

With increasing concentrations in the growth medium of the cyclization inhibitors nicotine or 2-(4-chlorophenylthio)-triethylamine hydrochloride (CPTA) the previously identified bicyclic carotenoids of Rhizobium lupini (2,3,2',3'-tetrahydroxy-beta,beta-caroten-4-one and 2,3,2',3'-tetrahydroxy-beta,beta-carotene) were successively replaced by hitherto unknown monocyclic carotenoids. By application of mass and nuclear magnetic resonance spectroscopy 3 carotenoids were identified as 2,3-trans-dihydroxy-beta,psi-caroten-4-one, 2,3-trans-dihydroxy-beta,psi-carotene, and 3-hydroxy-beta,psi-caroten-4-one. A further compound was tentatively established as (2- or 3-)monohydroxy-beta,psi-carotene. It was found that other inhibitors such as diphenylamine or 4-chloro-5-(dimethylamino)-2-alpha,alpha,alpha(trifluoro-m-tolyl)-3-(2H)-pyridazinone (San 6706) did not affect the pigment pattern. The results are discussed in relation to carotenoid biosynthesis in Rhizobium lupini. PMID:718371

Kleinig, H; Meister, W; Englert, G

1978-10-01

214

Growth of a leguminous tree (Centrolobium tomentosum Guill. ex Benth.) inoculated with Rhizobium and mycorrhizal fungi.  

Science.gov (United States)

Leguminous trees are being suggested for revegetation programs due to their ability to develop associations with rhizobia and mycorrhizal fungi. The growth of a native species of the Tropical Atlantic Forest, Centrolobium tomentosum, was evaluated in a native forest soil and in a Eucalyptus forest soil under different treatments of inoculation. C. tomentosum produced more biomass under nursery conditions after inoculation with Rhizobium BHICB-Ab1 associated with arbuscular mycorrhizal (AM). This treatment improved shoot and root growth and nodule weight under forest soil condition, while in eucalyptus soil only shoot biomass and nodule weight were significantly modified. In another experiment, using forest soil, height and stem diameter were also increased by dual inoculation procedures. The height and diameter growth promoting effect was observed when BHICB-Ab1 was used as inoculant associated with AM, but not with BHICB-Ab1 alone. In contrast, plants inoculated with BHICB-Ab3 alone were similar in height and diameter growth, to those which were inoculated with BHICB-Ab3 associated with AM. These results suggest that benefits of dual inoculation depend on triparty symbiosis and especially on the choice of Rhizobium strain. PMID:9269713

Marques, M S; Gonçalves, L M; Lemos-Filho, J P; Rocha, D; Vale, M T; Scotti, M R

1997-01-01

215

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

216

Specific oligosaccharide form of the Rhizobium meliloti exopolysaccharide promotes nodule invasion in alfalfa.  

Science.gov (United States)

Rhizobium meliloti strain SU47 produces both high molecular weight (HMW) and low molecular weight (LMW) forms of an acidic exopolysaccharide, succinoglycan. Genetic studies have shown that succinoglycan is required for alfalfa root nodule invasion. We found that LMW succinoglycan, when applied exogenously to alfalfa roots, restored nodule invasion to exoA, exoB, exoF, and exoH mutants. Nodule initiation signals were not involved, since LMW succinoglycan from R. meliloti nodD1D2D3 and nodA mutants and from luteolin-induced wild-type cultures elicited effects similar to LMW succinoglycan from the uninduced wild-type strain. In contrast, LMW fractions from an exoA mutant, nonsuccinylated LMW succinoglycan, and HMW succinoglycan did not promote invasion, nor did LMW exopolysaccharides from R. leguminosarum bv. trifolii and Rhizobium sp. strain NGR234. LMW succinoglycan could be separated by anion-exchange chromatography into several distinct subfractions differing in repeating subunit multiplicities (monomer, trimer, and tetramer) and charge. When tested singly, only the most charged, tetrameric form was active. These results show that a specific oligosaccharide form of succinoglycan promotes nodule invasion in alfalfa. The implications for the mode of action of succinoglycan are discussed. PMID:1608972

Battisti, L; Lara, J C; Leigh, J A

1992-06-15

217

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

Science.gov (United States)

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

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

218

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)

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

Ole?ska, Ewa; Ma?ek, Wanda

2013-05-01

219

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)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 bo

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

2011-08-01

220

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

Directory of Open Access Journals (Sweden)

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.

Robledo M

2012-09-01

 
 
 
 
221

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)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish 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.

Mónica G, Ontivero Urquiza; Héctor Abel, Altube; Leonardo, Baghin.

222

Role of Some Chemical Compounds on the Detoxification of Rhizobium leguminsarum biovar vicia by Some Heavy Metals  

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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 g...

Sanaa Mostafa El-Deeb; Fawziah Saleh Al-Sheri

2005-01-01

223

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

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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.

Helena Furga?-W?grzycka

1987-06-01

224

Mission related to regulation and development of the photovoltaic sector in France. Final report; Mission relative a la regulation et au developpement de la filiere photovoltaique en France. Rapport final  

Energy Technology Data Exchange (ETDEWEB)

This report first gives an overview of the development of the photovoltaic stock in France (high potential with a middle term development constrained by high costs, consequences of a very strong increase of demands at the end of 2009, perspective of development at a rather high rate). Then, it outlines and discusses the financial consequences of such a high rate development, and the inadequacy between industrial objectives and development rate. It presents a development plan for this sector, stresses the need to implement new purchase obligation measures before the summer 2010, and to define a global action plan to be implemented at the beginning of 2011 for the development of photovoltaic electricity. Elements of international comparison are finally proposed

Charpin, J.M; Sine, A.; Helleisen, Ph.; Tlili, C. [Inspection Generale des Finances - IGF, 75 - Paris (France); Trink, C.; Stoffaes, Ch. [Conseil General de l' Industrie de l' Energie et des Technologies - CGIET, 75 - Paris (France)

2010-07-01

225

Implementation and validation of the linear collider final focus prototype: ATF2 at KEK (Japan); Implementation et validation de la focalisation finale du collisionneur lineaire: ATF2 at KEK (Japan)  

Energy Technology Data Exchange (ETDEWEB)

The two linear collider projects (ILC and CLIC) require beam delivery systems with the same local chromaticity correction scheme in the final focus. ATF2 at KEK (Japan), an implementation of this scheme scaled down in energy, uses the beam extracted from ATF, which is one of the most successful damping rings in the world. The ATF2 goals are to prove the feasibility and the stability of the linear collider final focus system and to define and test the experimental correction procedures. The nominal beam sizes at the interaction point are 3 {mu}m horizontally and 37 nm vertically. The work in this thesis was started before the commissioning and covered its first year at KEK. At the beginning, we observed that the stripline BPMs were not working properly so we investigated their behavior in detail. The problem was characterized and later solved in 2010 by upgrading the electronics. We then developed an efficient procedure to check the modeling of the beam line, comparing measurements of transfer matrices to model predictions calculated on line. After obtaining a good agreement, we were able to successfully test the trajectory correction algorithm which had been developed, reducing the difference between BPM measurements and the target values down to 0.5 mm horizontally and 0.2 mm vertically. We also successfully developed an algorithm to reconstruct pulse to pulse beam trajectory fluctuations with sub-micron precision. This reconstruction also gave a precise determination of the energy fluctuation, allowing a global fit of the dispersion function along the beam line with a precision of a few mm. A simple and robust IP beam size tuning method using sextupoles displacements was also studied in simulation, whose performance indicates that, given some assumptions on the error level of the beam, convergence within 20% of the nominal beam size should be possible in 8 hours with a 80% probability. (author)

Renier, Y.

2010-06-15

226

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)

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.

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

1341-13-01

227

Énumération et structuration discursive  

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Full Text Available Dans cet article, la structure énumérative est envisagée, dans une perspective discursive, en tant que procédé d'organisation du texte constituant un tout fonctionnel. Une fois précisée notre approche et explicité son ancrage, un premier objectif est d’illustrer la diversité des réalisations des structures énumératives, tout en dégageant clairement ce qui en fait l’unité : la mise en parallèle des items, l’expression (ou l’inférabilité du critère interprétatif qui sous-tend cette mise en parallèle. Nous montrons que quelle que soit la réalisation de la structure – indices variés, potentiellement distribués sur les différents composants – elle se doit d’être perceptible, puisque c’est cette perception qui conditionne chez le lecteur la compréhension de l’intention sous-jacente. Nous décrivons les indices et la manière dont ils se combinent pour rendre la structure visible. Nous nous intéressons également à la diversité des contextes où elle s’insère, et des rôles discursifs auxquels elle se prête, ainsi que les premiers résultats concernant les corrélations entre types de réalisation et fonction. Pour cela, nous nous focalisons sur ses « marges » – l’amorce, qui la lie au texte amont et annonce l’énumération, et la clôture, segment final qui fait le lien avec le texte aval – pour mieux mettre en lumière la nécessité de la considérer dans son ensemble comme un tout fonctionnel.

Rebeyrolle Josette

2014-07-01

228

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

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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.

Eli Sidney Lopes

1986-01-01

229

ets 10  

ETS 10 Application for the Transfer of a Permit Version 3, 30 August 2008 The Greenhouse Gas Emissions Trading Scheme Regulations 2005 Confidentiality Statement The information submitted in respect of this application ...

230

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

Science.gov (United States)

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

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

2009-09-01

231

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

Science.gov (United States)

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

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

232

Functional Characterization of aroA from Rhizobium leguminosarum with Significant Glyphosate Tolerance in Transgenic Arabidopsis.  

Science.gov (United States)

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

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

2014-09-28

233

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

Science.gov (United States)

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

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

234

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

Science.gov (United States)

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

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

235

The morphogenesis of lupine root nodules during infection by Rhizobium lupini  

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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.

W?adys?aw Golinowski

1987-12-01

236

Rhizobium NodB protein involved in nodulation signal synthesis is a chitooligosaccharide deacetylase.  

Science.gov (United States)

The common nodulation genes nodABC are conserved in all rhizobia and are involved in synthesis of a lipooligosaccharide signal molecule. This bacterial signal consists of a chitooligosaccharide backbone, which carries at the nonreducing end a fatty acyl chain. The modified chitooligosaccharide molecule triggers development of nodules on the roots of the leguminous host plant. To elucidate the specific role of the NodB protein in nodulation factor synthesis, we have purified recombinant NodB and determined its biochemical role by direct assays. Our data show that the NodB protein of Rhizobium meliloti deacetylates the nonreducing N-acetylglucosamine residue of chitooligosaccharides. The monosaccharide N-acetylglucosamine is not deacetylated by NodB. In the pathway of Nod factor synthesis, deacetylation at the nonreducing end of the oligosaccharide backbone may be a necessary requirement for attachment of the fatty acyl chain. Images PMID:8421697

John, M; Rohrig, H; Schmidt, J; Wieneke, U; Schell, J

1993-01-01

237

Evaluation of the biotechnological potential of Rhizobium tropici strains for exopolysaccharide production.  

Science.gov (United States)

Rhizobium tropici, a member of the Rhizobiaceae family, has the ability to synthesize and secrete extracellular polysaccharides (EPS). Rhizobial EPS have attracted much attention from the scientific and industrial communities. Rhizobial isolates and R. tropici mutants that produced higher levels of EPS than the wild-type strain SEMIA4080 were used in the present study. The results suggested a heteropolymer structure for these EPS composed by glucose and galactose as prevailing monomer unit. All EPS samples exhibited a typical non-Newtonian and pseudoplastic fluid flow, and the aqueous solutions apparent viscosities increased in a concentration-dependent manner. These results serve as a foundation for further studies aimed at enhancing interest in the application of the MUTZC3, JAB1 and JAB6 strains with high EPS production and viscosity can be exploited for the large-scale commercial production of Rhizobial polysaccharides. PMID:25037342

Castellane, Tereza Cristina Luque; Lemos, Manoel Victor Franco; Lemos, Eliana Gertrudes de Macedo

2014-10-13

238

Biological behavior of plasmid in Rhizobium sp. strain S25 from Tephrosia candida.  

Science.gov (United States)

Rhizobium sp. strain S25 was isolated from the nodule on Tephrosia candida in Hainan Province, China. The strain showed high stress tolerance. The plasmid profile of strain S25, examined by the Eckhardt procedure, indicated that the strain harbors only one plasmid with an estimated size of 150 kb. The plasmid was shown to carry nod and nif genes by hybridization with probes of nodABC and nifHDK genes. Plasmid curing was carried out using the Bacillus subtilis sacB to generate derivatives of strain S25. In comparison with the parent strain S25, the cured derivative lost its ability to nodulate the host plant. Loss of the plasmid reduced significantly the strain's tolerance to acid, nitrous, and multiple antibiotics. The properties of the cured strain also indicated that the plasmid was involved in carbon and nitrogen metabolism. Reintroduction of the plasmid from S25 in the cured derivative restored its original biological phenotypes. PMID:9735317

Zou, X; Feng, X L; Chen, W X; Li, F D

1998-09-01

239

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

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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..

2008-01-01

240

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

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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.

A.K. Glyanko

2004-01-01

 
 
 
 
241

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

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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.

Tadeusz Zaj?c

2013-07-01

242

Rhizobium leguminosarum hupE encodes a nickel transporter required for hydrogenase activity.  

Science.gov (United States)

Synthesis of the hydrogen uptake (Hup) system in Rhizobium leguminosarum bv. viciae requires the function of an 18-gene cluster (hupSLCDEFGHIJK-hypABFCDEX). Among them, the hupE gene encodes a protein showing six transmembrane domains for which a potential role as a nickel permease has been proposed. In this paper, we further characterize the nickel transport capacity of HupE and that of the translated product of hupE2, a hydrogenase-unlinked gene identified in the R. leguminosarum genome. HupE2 is a potential membrane protein that shows 48% amino acid sequence identity with HupE. Expression of both genes in the Escherichia coli nikABCDE mutant strain HYD723 restored hydrogenase activity and nickel transport. However, nickel transport assays revealed that HupE and HupE2 displayed different levels of nickel uptake. Site-directed mutagenesis of histidine residues in HupE revealed two motifs (HX(5)DH and FHGX[AV]HGXE) that are required for HupE functionality. An R. leguminosarum double mutant, SPF22A (hupE hupE2), exhibited reduced levels of hydrogenase activity in free-living cells, and this phenotype was complemented by nickel supplementation. Low levels of symbiotic hydrogenase activity were also observed in SPF22A bacteroid cells from lentil (Lens culinaris L.) root nodules but not in pea (Pisum sativum L.) bacteroids. Moreover, heterologous expression of the R. leguminosarum hup system in bacteroid cells of Rhizobium tropici and Mesorhizobium loti displayed reduced levels of hydrogen uptake in the absence of hupE. These data support the role of R. leguminosarum HupE as a nickel permease required for hydrogen uptake under both free-living and symbiotic conditions. PMID:20023036

Brito, Belén; Prieto, Rosa-Isabel; Cabrera, Ezequiel; Mandrand-Berthelot, Marie-Andrée; Imperial, Juan; Ruiz-Argüeso, Tomás; Palacios, José-Manuel

2010-02-01

243

FORAGE PRODUCTIVITY OF ARBILA (Phaseolus lunatus AT VARIOUS LEVELS OF RHIZOBIUM INOCULANTS AND HARVESTING TIMES  

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Full Text Available The study was conducted to evaluate forage productivity of arbila (Phaseolus lunatus as the ruminant feed at various levels of rhizobium inoculants and harvesting times, was designed following completely randomized design of factorial pattern with two factors. The first factor was the level of inoculums (I i.e. I1 (without inoculum, I2 (5 g/kg seed, I3 (10 g/kg seed, and I4 (15 g/kg seed. The second factor was harvesting time (U i.e. U1 (60 days, U2 (80 days, U3 (100 days with 4 replications. The variables were N uptake, production of dry matter (DM and organic matter (OM, and percentage of OM, crude protein (CP, crude fiber (CF, nitrogen free extract (NFE, extract ether (EE and ash of arbila forage (based on DM. The results showed that inoculant treatment at the rate of 15 g/kg seed produced the highest percentage of effective nodules (98.72%, and in combination with harvesting age at 100 days each polybag of plant was able to absorb the higest amount of N (688. 10 g with production of DM 273.81 g, OM production 263.96 g and nutrients content based on DM of about 91.14% OM, 33.52% CF, 34.76%, 5.75% EE, 09.37% ash, and 16.16% CP. From the study, it can be concluded that arbila plants inoculated specific rhizobium Phaseolus vulgaris at the rate of 15 g/kg seed and harvested at 100 days yielded the best forage as feed.

B. B. Koten

2012-12-01

244

Common bean cultivars performance under Rhizobium inoculation and the relation between yield components traits
Desempenho de cultivares de feijoeiro sob inoculação com Rhizobium e relação entre os caracteres componentes do rendimento de grãos
 

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The objectives of this study was to evaluate the Rhizobium inoculation effect on the grain yield characters in common bean cultivars, to quantify the possible relationship between these characters, and verify the genetic similarity among cultivars to suggest possible combinations to be adopted in crosses by breeding programs. It was evaluated six commercial common bean cultivars (IAPAR 81, Carioca, SCS-202 Guará, BRS Valente, FTS Soberano e IPR Uirapuru), with and without inoculation of Rhiz...

Julio Cesar Pires Santos; Maraisa Crestani; Fernando José Hawerroth

2011-01-01

245

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)

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.

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

2000-03-01

246

Presença e eficiência de Rhizobium Japonicum em solos cultivados ou não com soja, no estado deSão Paulo Presence and efficiency of Rhizobium Japonicum in soils previously cultivated and never cultivated with soybeans  

Directory of Open Access Journals (Sweden)

Full Text Available Foi conduzido um ensaio em solução nutritiva sem nitrogênio, com condições assépticas, usando-se como inoculantes para as plantas amostras de solos LR e LB coletadas em locais já cultivados e não com soja, com o objetivo de verificar a presença de Rhizobium capaz de nodular o cultivar santa-rosa. Verificou-se que solos ainda não cultivados com a leguminosa são desprovidos de Rhizobium japonicum, e também que essa bactéria é encontrada em solos previamente cultivados, fixando nitrogênio em quantidades equivalentes à de uma estirpe selecionada.An experiment was carried out in Leonard jars using Latosolic B Terra Roxa and Dark Red Latosol soil samples as inoculum to detect the presence and efficiency of rhizobia able to nodulate cultivar Santa-Rosa of soybean (Glycine max. (L Merrill. Results have shown that no rhizobia were present in those soils. Rhizobium japonicum with efficiency comparable to a selected strain survived in the same soils, when they were previously cropped with inoculated soybeans.

Eli Sidney Lopes

1976-07-01

247

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)

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.

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

2013-01-01

248

Two gene clusters of Rhizobium meliloti code for early essential nodulation functions and a third influences nodulation efficiency.  

Science.gov (United States)

A pLAFR1 cosmid clone (pPP346) carrying the nodulation region of the symbiotic plasmid pRme41b was isolated from a gene library of Rhizobium meliloti 41 by direct complementation of a Nod- deletion mutant of R. meliloti. Agrobacterium tumefaciens and Rhizobium species containing pPP346 were able to form ineffective nodules on alfalfa. The 24-kilobase insert in pPP346 carries both the common nodulation genes and genes involved in host specificity of nodulation. It was shown that these two regions are essential and sufficient to determine the early events in nodulation. A new DNA region influencing the kinetics and efficiency of nodulation was also localized on the symbiotic megaplasmid at the right side of the nif genes. PMID:3745124

Putnoky, P; Kondorosi, A

1986-01-01

249

Inoculation of the nonlegume Capsicum annuum L. with Rhizobium strains. 2. Changes in sterols, triterpenes, fatty acids, and volatile compounds.  

Science.gov (United States)

Peppers (Capsicum spp.) are consumed worldwide, imparting flavor, aroma, and color to foods, additionally containing high concentrations of biofunctional compounds. This is the first report about the effect of the inoculation of two Rhizobium strains on sterols, triterpenes, fatty acids, and volatile compounds of leaves and fruits of pepper (Capsicum annuum L.) plants. Generally, inoculation with strain TVP08 led to the major changes, being observed a decrease of sterols and triterpenes and an increase of fatty acids, which are related to higher biomass, growth, and ripening of pepper fruits. The increase of volatile compounds may reflect the elicitation of plant defense after inoculation, since the content on methyl salicylate was significantly increased in inoculated material. The findings suggest that inoculation with Rhizobium strains may be employed to manipulate the content of interesting metabolites in pepper leaves and fruits, increasing potential health benefits and defense abilities of inoculated plants. PMID:24405510

Silva, Luís R; Azevedo, Jessica; Pereira, Maria J; Carro, Lorena; Velazquez, Encarna; Peix, Alvaro; Valentão, Patrícia; Andrade, Paula B

2014-01-22

250

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

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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.

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

2009-07-01

251

Use of the Chrome Azurol S Agar Plate Technique To Differentiate Strains and Field Isolates of Rhizobium leguminosarum biovar trifolii.  

Science.gov (United States)

Identification of Rhizobium and Bradyrhizobium strains and especially of indigenous isolates continues to be one of the major difficulties associated with competition studies. Because there is no universally accepted method, the method of choice depends on preference, experience, and equipment. Here, an agar plate technique was used to distinguish strains and field isolates of Rhizobium leguminosarum biovar trifolii to provide a basis for identifying nodule occupants in further competition studies. A rapid plate technique, based on differential growth characteristics, complements other techniques such as serological reactions, particularly when antisera cross-react with nonhomologous strains. The technique involves culturing strains and isolates on chrome azurol S agar. Although similar responses were observed among some strains, the response was highly reproducible and was considered an ideal complementary technique used in conjunction with serological procedures. Strains with similar responses could often be differentiated by varying media components, such as the source of carbon. PMID:16347877

Ames-Gottfred, N P; Christie, B R; Jordan, D C

1989-03-01

252

Tolerance Of Several Rhizobium Strain/Isolate To A1 and Their Interaction With Several Soybean Mutants  

International Nuclear Information System (INIS)

Research activities to study the interaction of several soybean mutant and rhizobium strain/isalates were carried out. The first experiment to be involved screening of nine strain/isolates for tolerance to A1 acid stress. Five strains/isolates were considered tolerance. Further experiment with three strains/isolates with difference A1 concentrations, showed that the isolate no. 06 had the highest growth rate followed by isolate 09 and TAL 102. Experiment on interaction of five soybean mutant/varieties with those strains/isolates were carried out in nutrient culture. Mutant no. 21 and 43 showed better growth in solution containing 50 uM A1. Good nodulation occured in mutant no. 23 inoculated with Rhizobium isolate no. 06. This good symbiotic association should be studied further at higher A1 concentration. (authors). 14 refs, 6 tabs

253

Biosynthesis of lipooligosaccharide nodulation factors: Rhizobium NodA protein is involved in N-acylation of the chitooligosaccharide backbone.  

Science.gov (United States)

Rhizobium meliloti interacts symbiotically with alfalfa by forming root nodules in which the bacteria fix nitrogen. The Rhizobium nodulation genes nodABC are involved in the synthesis of lipooligosaccharide symbiotic signal molecules, which are mono-N-acylated chitooligosaccharides. These bacterial signals elicit nodule organogenesis in roots of legumes. To elucidate the role of the NodA protein in lipooligosaccharide biosynthesis, we prepared a radiolabeled tetrasaccharide precursor carrying an amino group as a potential attachment site for N-acylation at the nonreducing glucosamine residue. Various criteria demonstrate that NodA is involved in the attachment of a fatty acyl chain to this tetrasaccharide precursor, yielding a biologically active nodulation factor. Images PMID:8159714

Rohrig, H; Schmidt, J; Wieneke, U; Kondorosi, E; Barlier, I; Schell, J; John, M

1994-01-01

254

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  

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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)

Ferrer Ribas, E

2000-05-09

255

Growth and yield of groundnut (Arachis hypogaea L.) as influenced by weed management practices and Rhizobium inoculation.  

Science.gov (United States)

Groundnut (Arachis hypogaea L.) productivity in India is low, because of many problems beset in its cultivation. One of the serious problems are weeds. Groundnut yield losses due to weeds have been estimated as high as 24 to 70 percent. This has created a scope for using herbicides in groundnut crop. A field investigation was carried out during kharif (rainy) season of 2001-2002 on a sandy loam soil at College Agronomy Farm, B.A. College of Agriculture, Gujarat Agricultural University, Anand, India to study the effect of weed management practices and Rhizobium inoculation on growth and yield of groundnut (Arachis hypogaea L.). Ten weed control treatments, comprising four treatments of sole application of fluchloralin, pendimethalin, butachlor and metolachlor, respectively each applied at 1.0 kg ha(-1); four treatments comprising of an application of the same herbicides at the same levels coupled with one hand weeding at 30 DAS; one weed-free treatment (hand weedings at 15, 30, 45 DAS); and one unweeded control. All 10 treatmets were combined with and without Rhizobium inoculation (i.e. a total of 20 treatment combinations) under a factorial randomized complete block design (FRBD) with four replications. Minimum weed dry matter accumulation (70 kg/ha) with higher weed control efficiency (90.70%) was recorded under an integrated method i.e. pendimethalin at 1.0 kg ha(-1) + hand weeding at 30 DAS, which also resulted in maximum pod yield (1773.50 kg ha(-1)). This treatment was comparable to fluchloralin applied at 1.0 kg ha(-1) combined with hand- weeding at 30 DAS. Weedy conditions in the unweeded control treatment reduced pod yield by 29.90-35.95% as compared to integrated method. Significantly higher pod yield was obtained with Rhizobium inoculation than the mean value of all treatments without inoculation. For most agronomical parameters examined, Rhizobium inoculation and weed control treatments were independent in their effect. PMID:16637221

Jhala, A; Rathod, P H; Patel, K C; Van Damme, P

2005-01-01

256

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

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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 ...

Lin, Xg; Hao, Wy; Wu, Th

1993-01-01

257

Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress  

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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...

Gomes Douglas; Batista Jesiane Stefânia da Silva; Schiavon Aline; Andrade Diva; Hungria Mariangela

2012-01-01

258

Quantitative 1 H NMR spectroscopy analysis of the poly(3-hydroxy alkanoate) extracted from Rhizobium meliloti cells  

International Nuclear Information System (INIS)

1H NMR analysis was carried out to determine the nature and the concentration of the poly(3-hydroxyalkanoate) (PHA) accumulated by Rhizobium meliloti M5N1. The PHA was identified as being poly(3-hydroxybutyrate) (PHB). Benzene was shown to meet all the requirements of an internal reference for PHB quantification. NMR data were in good agreement with corresponding data obtained by Gas Chromatography (GC) analysis. (authors). 4 refs., 2 figs

259

The effect of legume inoculation with Rhizobium strains and starter nitrogen on symbiotic nitrogen fixation and soil agrochemical properties  

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The present paper provides summarised data from pot and field trials designed to estimate the effects of the combination of different strains of Rhizobium and starter nitrogen ( N30) on different symbiotic systems (red clover, alfalfa, goat's rue and field beans) in a dystri-endohypogleyic albeluvisol (pHKCl 4.7-5.3) and Eutri-endohypogleyic Albeluvisol (pHKCl5.5-6.3), and Albi-endohypogleyic Luvisol (pHKCl 6.5-7.2).

Lapinskas, Edmundas

2006-01-01

260

Genetic Diversity among Rhizobium leguminosarum bv. Trifolii Strains Revealed by Allozyme and Restriction Fragment Length Polymorphism Analyses  

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Allozyme electrophoresis and restriction fragment length polymorphism (RFLP) analyses were used to examine the genetic diversity of a collection of 18 Rhizobium leguminosarum bv. trifolii, 1 R. leguminosarum bv. viciae, and 2 R. meliloti strains. Allozyme analysis at 28 loci revealed 16 electrophoretic types. The mean genetic distance between electrophoretic types of R. leguminosarum and R. meliloti was 0.83. Within R. leguminosarum, the single strain of bv. viciae differed at an average of 0...

Demezas, David H.; Reardon, Terry B.; Watson, John M.; Gibson, Alan H.

1991-01-01

 
 
 
 
261

Quantitative analysis of the naringenin-inducible proteome in Rhizobium leguminosarum by isobaric tagging and mass spectrometry.  

Science.gov (United States)

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

Tolin, Serena; Arrigoni, Giorgio; Moscatiello, Roberto; Masi, Antonio; Navazio, Lorella; Sablok, Gaurav; Squartini, Andrea

2013-06-01

262

Symbiont effect of Rhizobium bacteria and vesicular arbuscular mycorrhizal fungi on Pisum sativum in recultivated mine spoils  

Energy Technology Data Exchange (ETDEWEB)

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.

Biro, B.; Voros, I.; Kovespechy, K.; Szegi, J. (Hungarian Academy of Sciences, Budapest (Hungary). Soil Science and Agricultural Chemistry Research Institute)

263

Calcium-dependent regulation of genes for plant nodulation in Rhizobium leguminosarum detected by iTRAQ quantitative proteomic analysis.  

Science.gov (United States)

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

Arrigoni, Giorgio; Tolin, Serena; Moscatiello, Roberto; Masi, Antonio; Navazio, Lorella; Squartini, Andrea

2013-11-01

264

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  

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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.

Claudia G Castillo R

2008-01-01

265

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Spanish Abstract in spanish 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 cr [...] ecido 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. Abstract in english 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 d [...] ifferent 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.

Claudia G, Castillo R; Rosa, Rubio H; Horacio, Urzúa S; Fernando, Borie B.

266

Common bean cultivars performance under Rhizobium inoculation and the relation between yield components traitsDesempenho de cultivares de feijoeiro sob inoculação com Rhizobium e relação entre os caracteres componentes do rendimento de grãos  

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Full Text Available The objectives of this study was to evaluate the Rhizobium inoculation effect on the grain yield characters in common bean cultivars, to quantify the possible relationship between these characters, and verify the genetic similarity among cultivars to suggest possible combinations to be adopted in crosses by breeding programs. It was evaluated six commercial common bean cultivars (IAPAR 81, Carioca, SCS-202 Guará, BRS Valente, FTS Soberano e IPR Uirapuru, with and without inoculation of Rhizobium bacteria. The experimental design was randomized block design with four replications, in factorial arrangement (6x2, with six cultivars and two inoculation levels. Each plot had six rows with three meters in length and 0.50 meters between rows, with 4 m2 plot. The yield components traits in common bean, under the conditions of this study, do not show to be influenced by Rhizobium’s inoculation. The number of grains per pod has a relation with the definition of yield per area in commercial common bean cultivars, while the numbers of pods and grains per plant showed strong positive correlation with grain yield per plant. The SCS-202 Guará, FTS Soberano e IPR Uirapuru cultivars show high grain yield, characterizing potential parents to be adopted in bean breeding programs.Os objetivos deste trabalho foram avaliar o efeito da inoculação com Rhizobium sobre os caracteres de rendimento de grãos em cultivares comerciais de feijoeiro, quantificar as possíveis relações entre estes caracteres, e verificar a similaridade genética entre as cultivares avaliadas a fim de sugerir possíveis genitores para compor combinações promissoras a serem adotadas em cruzamentos artificiais pelos programas de melhoramento. Foram avaliadas seis cultivares comerciais de feijoeiro (IAPAR 81, Carioca, SCS-202 Guará, BRS Valente, FTS Soberano e IPR Uirapuru, com e sem a inoculação de bactérias do gênero Rhizobium. O delineamento experimental utilizado foi blocos ao acaso, com quatro repetições, onde os tratamentos foram combinados em esquema fatorial (6 x 2, sendo seis cultivares e dois níveis de inoculação. Cada parcela foi constituída por seis linhas de três metros de comprimento espaçadas em 0,50 m, com área útil de 4m2. Os componentes do rendimento de grãos em feijoeiro, nas condições de realização deste estudo, não mostram ser influenciadas pela inoculação com Rhizobium. O caráter número de grãos por legume apresenta relação positiva com a definição da produtividade de grãos por área em cultivares comerciais de feijoeiro, enquanto que os números de legumes e de grãos por planta evidenciam forte correlação positivas com a produção de grãos por planta. A cultivar BRS Valente apresenta maior dissimilaridade genética no grupo de genótipos avaliados. As cultivares SCS-202 Guará, FTS Soberano e IPR Uirapuru evidenciam elevado rendimento de grãos, caracterizando genitores potenciais a serem adotados em programas de melhoramento do feijoeiro.

Julio Cesar Pires Santos

2011-08-01

267

Selection of Rhizobium strain from Wonogiri, Central Java on the growth of soybean (Glycine max L. on the sand sterile medium in greenhouse  

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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.

SRI PURWANINGSIH

2005-07-01

268

Mathématiques, Mind et Geist.  

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Full Text Available L’article est une exploration systématique de la dualité des figures du Mind et du Geist, le premier étant entendu comme l’esprit en tant que partie de la nature scientifiquement objectivable, le second comme l’esprit en tant qu’acteur immatériel insaisissable de la pensée. De plus, cette dualité est étudiée du point de vue de l’interférence de la mathématique avec elle, dans plusieurs contextes. Sont ainsi successivement analysés : le conflit entre les deux « modèles » du Mind, le computationnaliste et le dynamiciste; la définition philosophique et la définition épistémologique du Geist ; le jeu entre Mind et Geist dans les recherches cognitives contemporaines ; l’ambivalence de la logique et des mathématiques vis-à-vis de l’opposition Mind/Geist. Dans la partie finale, on propose une définition personnelle du Geist–en termes d’adresse et de sujet–dont dérive une détermination du Mind. Revenant sur ces nouvelles bases à l’interférence avec la mathématique, on conclut sur la question essentielle et délicate de la paramétrisation de la conscience.This paper systematically investigates the conflicting figures of Mind and Geist : Mind has to be understood as some part of nature likely to become the object of science, while Geist names the unmaterial unseizable protagonist of thought. Further, the opposition of the two figures is studied in the light of the way mathematics interfere with it, in several contexts. This leads to following analyses : how computational and dynamicist models of Mind compete within cognitive science; how Geist may be defined philosophically and epistemologically ; how Mind and Geist differently come to be considered or to be aimed at within contemporary cognitive research ; how mathematics and logic play an ambivalent part with respect to the Mind/Geist opposition. In the final section of the paper, a personal definition of the Geist–in terms of address and subject–is proposed, which also leads to some conceptual determination of the Mind. Coming back to the interference with mathematics on this new basis, the paper concludes by an examination of the difficult question of the parametrization of consciousness.

Jean-Michel Salanskis

2004-04-01

269

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

270

Gérer et alerter  

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Full Text Available Sur la base de deux événements d’inondation ayant touché récemment, dans des contextes politiques, organisationnels et hydrologiques bien différents, de nouveaux quartiers d’habitation, cet article rend compte des pratiques des acteurs impliqués dans des situations d’alerte et de crise en Suisse. Le recensement des acteurs – à travers leur rôle et leur place dans les mécanismes de préparation, d’alerte et de gestion –, ainsi que l’inventaire des documents mobilisés par ceux-ci, ont été réalisés dans les deux cas. Cette analyse a permis d’évaluer la gestion des événements, de déceler les changements organisationnels qui ont suivi les crises et de connaître la conception et le degré de formalisation du risque dont étaient dotés les différents acteurs avant et après les inondations. Plus encore, l’analyse a documenté les nouveaux processus d’alerte et de prévision qui ont été mis en place suite aux événements. Il s’avère ainsi que les épisodes d’inondation agissent de façon décisive sur la production de connaissances, à un degré variable selon les acteurs. Ces épisodes révèlent aussi parfois l’existence de connaissances « en attente » qui ne sont pas encore intégrées dans les procédures institutionnelles. Tant du point de vue de la prévision que de la gestion de la crise, ils permettent aussi de tester les canaux de l’information et de combler les déficits d’organisation, de collaboration et de sécurisation des dispositifs de communication. En outre, les risques et les crises liés aux inondations modifient les dynamiques et les politiques territoriales, conséquences du réajustement des réseaux d’acteurs. La mise en place de dispositifs d’intervention et de gestion de crise se montre cependant plus efficace que la refonte des dispositifs d’aménagement, généralement longue. Toutefois, la mémoire des événements se dégradant avec le temps, une inscription territoriale du risque s’avère nécessaire.Based on two flood events that recently affected new housing areas in very different political, organisational and hydrological contexts, this article examines the practices of actors involved in emergency and crisis situations in Switzerland. In both cases, the actors are identified – through their role and their position in the various procedures related to crisis management – and an inventory is made of the documents used. The study examines how the flood events were managed, identifies the organisational changes that followed the crises, and determines how the risk was conceived and to what extent it was formalised by the different actors both before and after the floods. Finally new forecasting and warning procedures that were set up following the events are described. The study shows that floods have a decisive impact on the production of knowledge, but that this phenomenon varies according to the actors. Events such as floods also sometimes reveal the existence of "latent" knowledge, or knowledge that is available but has not yet been integrated into institutional procedures. In terms of both forecasting and crisis management, these events also provide the opportunity to test information channels and to identify and correct any problems relating to organisation, cooperation or the reliability of means of communication. Among other things, the risks and crises related to flooding modify the dynamics and policies of the local area as a result of readjustments in the networks of actors. The introduction of emergency and crisis management measures appears more effective, however, than the reorganisation of planning and development procedures, a process which generally takes a lot longer. Nevertheless, since the recollection of events tends to fade with time, it is important that risks find a more concrete form of spatial expression on the landscape.

Valérie November

2009-03-01

271

Procedure for Obtaining Efficient Root Nodulation of a Pea Cultivar by a Desired Rhizobium Strain and Preempting Nodulation by Other Strains.  

Science.gov (United States)

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 resulting Rhizobium strain with the pea cultivar carrying sym-2. To accomplish this, we first constructed a transposon Tn5 derivative called Tn5nodX and an efficient delivery vehicle that is suicidal in R. leguminosarum. We tested the potential utility of the system in greenhouse experiments. The results are encouraging enough to warrant extensive experiments under field conditions. PMID:16348502

Fobert, P R; Roy, N; Nash, J H E; Iyer, V N

1991-06-01

272

Ecotoxicological assessment of pesticides towards the plant growth promoting activities of Lentil (Lens esculentus)-specific Rhizobium sp. strain MRL3.  

Science.gov (United States)

This study was designed to evaluate the effect of the selected pesticides [herbicides (metribuzin and glyphosate), insecticides (imidacloprid and thiamethoxam) and fungicides (hexaconazole, metalaxyl and kitazin)] at the recommended and the higher dose rates on plant growth promoting traits of Rhizobium sp. strain MRL3 isolated from lentil-nodules. Strain MRL3 was explicitly selected owing to its high pesticide-tolerance ability and substantial production of indole acetic acid, siderophores (salicylic acid and 2, 3 dihydroxy benzoic acid), exo-polysaccharides, HCN and ammonia. A trend of pesticide-concentration dependent progressive-decline for plant growth promoting properties of Rhizobium sp. strain MRL3 was observed excluding exo-polysaccharides which was regularly augmented on exceeding the concentration of each tested pesticide from the recommended dose. Commonly, the maximum toxicity to plant growth promoting traits of Rhizobium was shown by glyphosate, imidacloprid and hexaconazole at three times the recommended rate among herbicides, insecticides and fungicides, respectively. PMID:21318390

Ahemad, Munees; Khan, Mohammad Saghir

2011-06-01

273

Bouvard et Pécuchet et le savoir médical  

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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.

Norioki Sugaya

2009-01-01

274

Increased effectiveness of competitive rhizobium strains upon inoculation of Cajanus cajan  

International Nuclear Information System (INIS)

A field study was conducted in lysimeters containing 15N-enriched soil to determine the effects of four competitive rhizobium strains upon yield parameters of pigeon peas (Cajanus cajan). The greatest differences observed were in seed yields; strain P132 effected the highest seed yield (121 +/- 20 g per plant), and the control strain (indigenous rhizobia) effected the lowest yield (43.9 +/- 8 g per plant). With the exception of seeds and pods, the dry matter weights were not different. Although there appeared to be no effect by inoculum strains on the fractional content of N derived from biological nitrogen fixation when the total plant biomass was considered, strains P132 and 401 partitioned more of the N derived from fixation into seeds and leaves than did the other strains. Because the seeds comprised the major portion of plant N, more total N and more N derived from biological nitrogen fixation (about half of total N) were found in plants inoculated with P132, whereas the smallest amount was found in the uninoculated controls. P132 was also the best competitor with respect to indigenous rhizobia and accounted for all of the nodules found on the plants in which it was inoculated

275

Rhizobium Strain Effects on Yield and Bleeding Sap Amino Compounds in Pisum sativum.  

DEFF Research Database (Denmark)

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.

Rosendahl, Lis

1984-01-01

276

ABC transport is inactivated by the PTS(Ntr) under potassium limitation in Rhizobium leguminosarum 3841.  

Science.gov (United States)

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

Untiet, Verena; Karunakaran, Ramakrishnan; Krämer, Maria; Poole, Philip; Priefer, Ursula; Prell, Jürgen

2013-01-01

277

Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI565.  

Science.gov (United States)

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

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

278

The PTS(Ntr) system globally regulates ATP-dependent transporters in Rhizobium leguminosarum.  

Science.gov (United States)

Mutation of ptsP encoding EI(Ntr) of the PTS(Ntr) system in Rhizobium leguminosarum strain Rlv3841 caused a pleiotropic phenotype as observed with many bacteria. The mutant formed dry colonies and grew poorly on organic nitrogen or dicarboxylates. Most strikingly the ptsP mutant had low activity of a broad range of ATP-dependent ABC transporters. This lack of activation, which occurred post-translationally, may explain many of the pleiotropic effects. In contrast proton-coupled transport systems were not inhibited in a ptsP mutant. Regulation by PtsP also involves two copies of ptsN that code for EIIA(Ntr) , resulting in a phosphorylation cascade. As in Escherichia coli, the Rlv3841 PTS(Ntr) system also regulates K(+) homeostasis by transcriptional activation of the high-affinity ATP-dependent K(+) transporter KdpABC. This involves direct interaction of a two-component sensor regulator pair KdpDE with unphosphorylated EIIA(Ntr) . Critically, ptsP mutants, which cannot phosphorylate PtsN1 or PtsN2, had a fully activated KdpABC transporter. This is the opposite pattern from that observed with ABC transporters which apparently require phosphorylation of PtsN. These results suggest that ATP-dependent transport might be regulated via PTS(Ntr) responding to the cellular energy charge. ABC transport may be inactivated at low energy charge, conserving ATP for essential processes including K(+) homeostasis. PMID:22340847

Prell, J; Mulley, G; Haufe, F; White, J P; Williams, A; Karunakaran, R; Downie, J A; Poole, P S

2012-04-01

279

Evaluación de diferentes sistemas de fermentación para la producción de ácido indolacético por Rhizobium sp  

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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.

Beatriz Altuna

2006-01-01

280

Rhizobium alters inducible defenses in broad bean, Vicia faba  

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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.

Edward Brian Mondor

2011-11-01

 
 
 
 
281

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

282

Rhizobium sp. effects, irradiated with ultraviolet and gamma rays, on nodulation of P. vulgaris (L.) bean  

International Nuclear Information System (INIS)

Indigenous isolates of Rhizobium sp. from the root nodules of bean were selected. There of these isolates and a R. leguminosarum biovar phaseoli (SEMIA 4064) strain, used as a reference, were irradiated with ultraviolet (UV) light and gamma-Rays (?-R). The relations between survival and fluence of UV, and survival and absorbed dose of ?-R were linear for the strain of reference. The D37 values, for this rhizobial strain were 43 j.m-2 for the UV-treatment, and 32 Gy for the ?-rays treatment. Through a greenhouse experiment the irradiated isolates were inoculated on bean seedlings (P. vulgaris L, Variety IPA-8), in an attempt to evaluate sensitivity of the host-plants and possible effects on their nodulation. Significant differences were observed only for root dry matter yield. For all the other evaluated parameters variance was of such magnitude that it was not possible to detect significance of the effects. The isolates tested showed difference in responses to nodulation, due to the effects of irradiations. The host plant (IPA-8) seemed to be sensitive to the possible modifications in the irradiated isolates. (author). 10 refs, 6 figs, 1 tab

283

Role of nickel in membrane-bound hydrogenase and nickel metabolism in Rhizobium japonicum  

International Nuclear Information System (INIS)

The membrane-bound hydrogenase of Rhizobium japonicum requires nickel for activity. Radioactive 63Ni co-migrates with hydrogenase activity in native gel systems and co-elutes with purified hydrogenase form an affinity matrix column. A simplified scheme for the purification of hydrogenase has been developed and constitutes the first report of the aerobic purification of this enzyme from R. japonicum. The aerobic purification utilizes the general affinity matrix. Reactive Red 120-agarose and results in higher specific activity and yield of enzyme than previously reported. The stability of aerobically purified hydrogenase to oxygen is substantially greater than that reported for anaerobically isolated enzyme. Reduction of the aerobically purified enzyme in the presence of oxygen, however, results in the rapid loss of activity. R. japonicum cells accumulate nickel during heterotrophic growth and as non-growing cells. The hydrogenase constitutive mutant SR470 accumulates substantially greater amounts of nickel under both conditions. Kinetic studies indicate that the nickel uptake system in the hydrogenase constitutive mutant SR470 is upregulated relative to SRwt cells. The uptake system is specific for nickel, although a 10-fold excess (relative to nickel) of copper or zinc inhibits nickel uptake. The nickel uptake system appears to require energy. Under nickel-free conditions hydrogenase protein is not synthesized as determined by cross-reactivity with antibodies directed against hydrogenase, indicating that nickel regulates the formation of the enzyme as well as being a constituent of the active protein

284

Suppression of the ndv mutant phenotype of Rhizobium meliloti by cloned exo genes.  

Science.gov (United States)

The ndvA and ndvB genes of Rhizobium meliloti are involved in the export and synthesis, respectively, of the small cyclic polysaccharide beta(1,2)glucan. We have previously shown that spontaneous symbiotic pseudorevertants of ndv mutants do not produce periplasmic beta(1,2)glucan. Here we show that the pseudorevertants also do not produce extracellular beta(1,2)glucan, but do show alterations in the amount of the major acidic exopolysaccharide produced. This exopolysaccharide is not detectably different from that produced by the wild type or by the ndv mutants. A cosmid which suppresses the symbiotic defect of both ndvA and ndvB mutants was isolated from a gene bank prepared from DNA of an ndvA pseudorevertant. This cosmid contains a number of exo genes, including exoH and exoF. Subcloning and Tn5 mutagenesis were used to show that the widely separated exoH and exoF genes are both involved in suppression of the ndv mutant phenotype and that the 3.5 kb DNA fragment which contains the exoH gene does not carry the mutation responsible for second site suppression. PMID:1560776

Nagpal, P; Khanuja, S P; Stanfield, S W

1992-02-01

285

Characterization of polysaccharides of Rhizobium meliloti exo mutants that form ineffective nodules.  

Science.gov (United States)

Mutants of Rhizobium meliloti SU47 with defects in the production of the Calcofluor-binding expolysaccharide succinoglycan failed to gain entry into alfalfa root nodules. In order to define better the polysaccharide phenotypes of these exo mutants, we analyzed the periplasmic oligosaccharide cyclic (1-2)-beta-D-glucan and lipopolysaccharide (LPS) in representative mutants. The exoC mutant lacked the glucan and had abnormal LPS which appeared to lack a substantial portion of the O side chain. The exoB mutant had a spectrum of LPS species which differed from those of both the wild-type parental strain and the exoC mutant. The presence of the glucan and normal LPS in the exoA, exoD, exoF, and exoH mutants eliminated defects in these carbohydrates as explanations for the nodule entry defects of these mutants. We also assayed for high- and low-molecular-weight succinoglycans. All of the exo mutants except exoD and exoH completely lacked both forms. For the Calcofluor-dim exoD mutant, the distribution of high- and low-molecular-weight forms depended on the growth medium. The haloless exoH mutant produced high-molecular-weight and only a trace of low-molecular-weight succinoglycan; the succinyl modification was missing, as was expected from the results of previous studies. The implications of these observations with regard to nodule entry are discussed. PMID:3403505

Leigh, J A; Lee, C C

1988-08-01

286

A second exopolysaccharide of Rhizobium meliloti strain SU47 that can function in root nodule invasion  

Energy Technology Data Exchange (ETDEWEB)

Rhizobium meliloti strain SU47 produces the calcofluor-binding exopolysaccharide, succinoglycan, that is required for alfalfa root nodule invasion. Strains derived from R. meliloti SU47 secreted an acidic exopolysaccharide, EPSb, that replaced succinoglycan in nodule invasion. EPSb, which has not formerly been identified among the Rhizobiaceae, consisted of the repeating unit 4,6-O-(1-carboxyethylidene)-{alpha}-D-Galp1{yields}3(X-O-Ac)-{beta}-D-Glcp1{yields}3. EPSb synthesis occurred either in strains containing a mutation in a locus designated mucR or in strains with a recombinant cosmid pMuc. mucR mapped slightly counterclockwise from pyr49 on the chromosome, while pMuc contained genes mapping to the megaplasmid pRmeSU47b. In exoA, -F, and -H mutants, which are deficient in normal succinoglycan secretion and nodule invasion, a transposon Tn5 insertion in mucR or the presence of pMuc resulted in EPSb secretion and a restoration of nodule invasion on Medicago sativa and Melilotus alba. Mutants in exoB and exoC were incapable of succinoglycan and EPSb secretion as well as nodule invasion. A mutant that secreted succinoglycan but was incapable of EPSb secretion invaded nodules normally.

Zhan, Hangjun; Levery, S.B.; Lee, C.C.; Leigh, J.A. (Univ. of Washington, Seattle (USA))

1989-05-01

287

Studies on the Inoculation and Competitiveness of a Rhizobium leguminosarum Strain in Soils Containing Indigenous Rhizobia.  

Science.gov (United States)

The competitiveness of a Rhizobium leguminosarum strain was investigated at two separate locations in field inoculation studies on commercially grown peas. The soil at each location (sites I and II) contained an indigenous R. leguminosarum population of ca. 3 x 10 rhizobia per g of soil. At site I it was necessary to use an inoculum concentration as large as 4 x 10 CFU ml (2 x 10 bacteria seed) to establish the inoculum strain in the majority of nodules (73%). However, at site II the inoculum strain formed only 33% of nodules when applied at this (10 CFU ml) level. Establishment could not be further improved by increasing the inoculum concentration even as high as 10 CFU ml (9.6 x 10 bacteria seed). The inoculum strain could be detected at both sites 19 months after inoculation. Analysis by intrinsic antibiotic resistance patterns and plasmid DNA profiles indicated that a dominant strain(s) and plasmid pool existed among the indigenous population at site II. Competition experiments were carried out under laboratory conditions between a dominant indigenous isolate and the inoculum strain. Both strains were shown to be equally competitive. PMID:16346769

Meade, J; Higgins, P; O'gara, F

1985-04-01

288

Quantitative comparison of the laboratory and field competitiveness of Rhizobium leguminosarum biovar phaseoli.  

Science.gov (United States)

Rhizobium leguminosarum bv. phaseoli KIM5s outcompeted strain CE3 in bean (Phaseolus vulgaris L.) root nodulation when plants were grown at any of three field sites, each with a different soil type and indigenous population, or in the laboratory in a sterilized sand, a sterilized peat-vermiculite mixture, or a nonsterile field soil. A mathematical model describing nodulation competitiveness was empirically derived to evaluate the relative competitiveness of the two strains under these conditions. This model relates the proportional representation of the two strains in the inoculum to the proportional representation of nodules occupied by each strain or both strains and provides a measure of competitiveness, which is referred to as the competitiveness index. Statistical comparisons of competitiveness indices showed that the relative competitiveness of KIM5s and CE3 remained constant when the two strains were applied in a constant ratio over a range of inoculum concentrations, from 10(3) to 10(7) cells per seed, and when they were applied in various ratios to six P. vulgaris cultivars. Furthermore, the relative competitiveness of KIM5s and CE3 in the laboratory did not differ significantly from their relative competitiveness at the three field sites studied. Thus, a study of the basis for nodulation competitiveness of KIM5s and CE3 in the laboratory has the potential to provide an understanding of competitiveness both in the laboratory and in the field. PMID:2624457

Beattie, G A; Clayton, M K; Handelsman, J

1989-11-01

289

Transfer of an indigenous plasmid of Rhizobium loti to other rhizobia and Agrobacterium tumefaciens.  

Science.gov (United States)

Rhizobium loti strains NZP2037 and NZP2213 were each found to contain a single large plasmid: pRlo2037a (240 MDal) and pRlo2213a (120 MDal), respectively. Plasmid DNA present in crude cell lysates of each strain and purified pRlo2037a DNA did not hybridize with pID1, a recombinant plasmid containing part of the nitrogen fixation (nif) region of R. meliloti, indicating that nif genes were not present on these plasmids. The transposon Tn5 was inserted into pRlo2037a and this plasmid was then transferred into R. leguminosarum, R. meliloti and Agrobacterium tumefaciens. All transconjugants failed to nodulate Lotus pedunculatus, suggesting that the ability to nodulate this legume was also not carried on pRlo2037a. Transfer of pRlo2037a to R. loti strain NZP2213 did not alter the Nod+ Fix- phenotype of this strain for L. pedunculatus. Determinants for flavolan resistance, believed to be necessary for effective nodulation of L. pedunculatus, were not carried on pRlo2037a. These data suggest that nodulation, nitrogen fixation and flavolan resistance genes are not present on the large plasmid in R. loti strain NZP2037. PMID:6313860

Pankhurst, C E; Broughton, W J; Wieneke, U

1983-08-01

290

Isolation of Rhizobium Spp. Bacteria which as Used Microbial Fertilizer from Wild Leguminosarum Plants  

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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.

Hatice Ö?ütcü

2014-04-01

291

Effect of Leguminous Lectins on the Growth of Rhizobium tropici CIAT899  

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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.

Mayron Alves de Vasconcelos

2013-05-01

292

Evaluation of the Galega-Rhizobium galegae system for the bioremediation of oil-contaminated soil  

Energy Technology Data Exchange (ETDEWEB)

The bioremediation potential of a nitrogen-fixing leguminous plant, Galega orientalis, and its microsymbiont Rhizobium galegae was evaluated in BTX (benzene, toluene, xylene)-contaminated soils in microcosm and mesocosm scale. To measure the intrinsic tolerance of the organisms to m-toluate, a model compound representing BTX, G. orientalis and R. galegae were cultivated under increasing concentrations of m-toluate alone and in association with Pseudomonas putida pWWO, a bacterial strain able to degrade toluene-derived compounds. The test plants and rhizobia remained viable in m-toluate concentrations as high as 3000 ppm. Plant growth was inhibited in concentrations higher than 500 ppm, but restituted when plants were transferred into m-toluate-free medium. Nodulation was blocked under the influence of m-toluate, but was restored after the plants were transferred into the non-contaminated media. In the mesocosm assay the Galega plants showed good growth, modulation and nitrogen fixation, and developed a strong rhizosphere in soils contaminated with oil or spiked with 2000 ppm m-toluate. Thus, this legume system has good potential for use on oil-contaminated sites. (author)

Suominen, L.; Jussila, M.M.; Makelainen, K.; Lindstrom, K. [University of Helsinki (Finland). Dept. of Applied Chemistry and Microbiology; Romantschuk, M. [University of Helsinki (Finland). Dept. of Biosciences

2000-07-01

293

Increased effectiveness of competitive rhizobium strains upon inoculation of Cajanus cajan  

Energy Technology Data Exchange (ETDEWEB)

A field study was conducted in lysimeters containing /sup 15/N-enriched soil to determine the effects of four competitive rhizobium strains upon yield parameters of pigeon peas (Cajanus cajan). The greatest differences observed were in seed yields; strain P132 effected the highest seed yield (121 +/- 20 g per plant), and the control strain (indigenous rhizobia) effected the lowest yield (43.9 +/- 8 g per plant). With the exception of seeds and pods, the dry matter weights were not different. Although there appeared to be no effect by inoculum strains on the fractional content of N derived from biological nitrogen fixation when the total plant biomass was considered, strains P132 and 401 partitioned more of the N derived from fixation into seeds and leaves than did the other strains. Because the seeds comprised the major portion of plant N, more total N and more N derived from biological nitrogen fixation (about half of total N) were found in plants inoculated with P132, whereas the smallest amount was found in the uninoculated controls. P132 was also the best competitor with respect to indigenous rhizobia and accounted for all of the nodules found on the plants in which it was inoculated.

Hernandez, B.S.; Poth, M.; Focht, D.D.

1987-09-01

294

Study of the basis for the competitiveness of Rhizobium japonicum in the nodulation of soybean  

Energy Technology Data Exchange (ETDEWEB)

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.

Bauer, W.

1990-06-01

295

Genome sequence of the clover-nodulating Rhizobium leguminosarum bv. trifolii strain SRDI943.  

Science.gov (United States)

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

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

296

Paramétrage Dynamique et Optimisation Automatique des Réseaux Mobiles 3G et 3G+  

Digital Repository Infrastructure Vision for European Research (DRIVER)

La télécommunication radio mobile connait actuellement une évolution importante en termes de diversité de technologies et de services fournis à l'utilisateur final. Il apparait que cette diversité complexifie les réseaux cellulaires et les opérations d'optimisation manuelle du paramétrage deviennent de plus en plus compliquées et couteuses. Par conséquent, les couts d'exploitation du réseau augmentent corrélativement pour les operateurs. Il est donc essentiel de simplifier et d'a...

Nasri, Ridha

2009-01-01

297

Characterization of the gene encoding nitrite reductase and the physiological consequences of its expression in the nondenitrifying Rhizobium "hedysari" strain HCNT1.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rhizobium "hedysari" HCNT1 is an unclassified rhizobium which contains a nitric oxide-producing nitrite reductase but is apparently incapable of coupling the reduction of nitrite to energy conservation. The gene encoding the nitrite reductase, nirK, has been cloned and sequenced and was found to encode a protein closely related to the copper-containing family of nitrite reductases. Unlike other members of this family, nirK expression in HCNT1 is not dependent on the presence of nitrogen oxide...

Toffanin, A.; Wu, Q.; Maskus, M.; Caselia, S.; Abrun?a, H. D.; Shapleigh, J. P.

1996-01-01

298

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)

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.

Patrícia P., Pinto; Ruy, Raposeiras; Andrea M., Macedo; Lucy, Seldin; Edilson, Paiva; Nadja M.H., Sá.

299

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)

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.

Patrícia P., Pinto; Ruy, Raposeiras; Andrea M., Macedo; Lucy, Seldin; Edilson, Paiva; Nadja M.H., Sá.

1998-10-01

300

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.  

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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.

Ormeño-Orrillo Ernesto

2012-12-01

 
 
 
 
301

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  

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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.

Eulene Francisco da Silva

2009-01-01

302

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)

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

Juan Guillermo, Cubillos-Hinojosa; Pablo Ernesto, Milian-Mindiola; Jorge Luis, Hernández-Mulford.

303

Is 'Final' Really Final?  

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Recently, the Appeal Committee of the Hong Kong Court of Final Appeal raised the question of whether that court had the power to hear an appeal against a decision of the Court of Appeal. The decision in question concerned a judgment of professional misconduct against an accountant by a disciplinary committee under the Professional Accountants Ordinance. The ordinance clearly states that the decision of the Court of Appeal is final. This article examines whether the Court of Final Appeal has t...

Tai, B.

2002-01-01

304

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)

305

Transfer of R1drd19 plasmid from Escherichia coli J53 to Rhizobium trifolii by conjugation.  

Science.gov (United States)

Rldrd19 plasmid was transferred by conjugation from Escherichia coli J53 to Rhizobium trifolii T24, T26 and 24XSM strains with frequency 10(-3) to 10(-5). The R. trifolii exconjugants carrying Rldrd19 were in turn able to transfer the R factor by conjugation to other R. trifolii strains. Rldrd19 was maintained stably in R. trifolii. R. trifolii 24XSM, T26 and 14M were also found to harbor an endogenous plasmid (molecular weight 5.5 megadaltons) with undetermined as yet properties. Ridrd19 could be stably maintained in the same cell together with the endogenous plasmid. PMID:67758

Kowalczuk, E; Lorkiewicz, Z

1977-01-01

306

Involvement of Genes on a Megaplasmid in the Acid-Tolerant Phenotype of Rhizobium leguminosarum Biovar Trifolii  

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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 <4.7. The intracellular pH of strain AN...

Chen, Hancai; Gartner, Elena; Rolfe, Barry G.

1993-01-01

307

Influence of Lime and Phosphate on Nodulation of Soil-Grown Trifolium subterraneum L. by Indigenous Rhizobium trifolii†  

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Previous research had identified four serogroups of Rhizobium trifolii indigenous to the acidic Abiqua soil (fine, mixed, mesic Cumulic Ultic Haploxeroll). Nodulation of subterranean clover (Trifolium subterraneum L.) by two of the serogroups, 6 and 36, was differentially influenced by an application of CaCO3 which raised the pH of the soil from 5.0 to 6.5. These studies were designed to characterize this phenomenon more comprehensively. Liming the soil with either CaCO3, Ca(OH)2, MgO, or K2C...

Almendras, Angela S.; Bottomley, Peter J.

1987-01-01

308

Expression of a cell surface antigen from Rhizobium leguminosarum 3841 is regulated by oxygen and pH.  

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Rhizobium leguminosarum bv. viciae 3841 was grown in liquid suspension culture to investigate how culture conditions could affect the expression of a developmentally regulated cell surface antigen associated with lipopolysaccharide. The antigen, which is recognized by monoclonal antibody AFRC MAC 203, was expressed when cultures were grown at neutral pH under low-oxygen conditions (less than 7.5% [vol/vol] O2 in the gas phase). Antigen was also expressed in aerobically grown cultures at pH va...

Kannenberg, E. L.; Brewin, N. J.

1989-01-01

309

A family of activator genes regulates expression of Rhizobium meliloti nodulation genes.  

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Nodulation (nod) gene expression in Rhizobium meliloti requires plant inducers and the activating protein product of the nodD gene. We have examined three genes in R. meliloti which have nodD activity and sequence homology. These three nodD genes are designated nodD1, nodD2 and nodD3, and have distinctive properties. The nodD1 gene product activates expression of the nodABC operon, as measured by a nodC-lacZ fusion or by transcript analysis, in the presence of crude seed or plant wash or the inducer, luteolin. The nodD3 gene product can cause a high basal (uninduced) level of nodC-lacZ expression and nodABC transcripts which is relatively unaffected by inducers. The effect of nodD3 is dependent on the presence of another gene, syrM (symbiotic regulator). By primer extension analysis we determined that the transcription start site is the same for nodD1 plus luteolin or nodD3-syrM mediated expression of nodA and nodH mRNAs. syrM also enhances the expression of another symbiotically important trait, production of extracellular polysaccharide. This regulatory effect of syrM requires locus syrA, which is linked to nodD3 and syrM. The syrM-syrA mediated increase in polysaccharide production requires at least some of the previously identified exo genes and may be a parallel regulatory event to the syrM-nodD3 control of nod promoters. PMID:2731734

Mulligan, J T; Long, S R

1989-05-01

310

Identification of protein secretion systems and novel secreted proteins in Rhizobium leguminosarum bv. viciae  

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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.

Krehenbrink Martin

2008-01-01

311

Acetoacetyl coenzyme A reductase and polyhydroxybutyrate synthesis in rhizobium (Cicer) sp. Strain CC 1192  

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Biochemical controls that regulate the biosynthesis of poly-3-hydroxybutyrate (PHB) were investigated in Rhizobium (Cicer) sp. strain CC 1192. This species is of interest for studying PHB synthesis because the polymer accumulates to a large extent in free-living cells but not in bacteroids during nitrogen-fixing symbiosis with chickpea (Cicer arietinum L.) plants. Evidence is presented that indicates that CC 1192 cells retain the enzymic capacity to synthesize PHB when they differentiate from the free-living state to the bacteroid state. This evidence includes the incorporation by CC 1192 bacteroids of radiolabel from [14C]malate into 3-hydroxybutyrate which was derived by chemically degrading insoluble material from bacteroid pellets. Furthermore, the presence of an NADPH-dependent acetoacetyl coenzyme A (CoA) reductase, which was specific for R-(-)-3-hydroxybutyryl-CoA and NADP+ in the oxidative direction, was demonstrated in extracts from free-living and bacteroid cells of CC 1192. Activity of this enzyme in the reductive direction appeared to be regulated at the biochemical level mainly by the availability of substrates. The CC 1192 cells also contained an NADH-specific acetoacetyl-CoA reductase which oxidized S-(+)-3-hydroxybutyryl-CoA. A membrane preparation from CC 1192 bacteroids readily oxidized NADH but not NADPH, which is suggested to be a major source of reductant for nitrogenase. Thus, a high ratio of NADPH to NADP+, which could enhance delivery of reductant to nitrogenase, could also favor the reduction of acetoacetyl-CoA for PHB synthesis. This would mean that fine controls that regulate the partitioning of acetyl-CoA between citrate synthase and 3-ketothiolase are important in determining whether PHB accumulates. PMID:9687441

Chohan; Copeland

1998-08-01

312

Proteomic profiling of Rhizobium tropici PRF 81: identification of conserved and specific responses to heat stress  

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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.

Gomes Douglas

2012-05-01

313

Rhizobium meliloti mutants that overproduce the R. meliloti acidic Calcofluor-binding exopolysaccharide  

International Nuclear Information System (INIS)

The acidic Calcofluor-binding exopolysaccharide of Rhizobium meliloti Rm1021 plays one or more critical roles in nodule invasion and possible in nodule development. Two loci, exoR and exoS, that effect the regulation of synthesis of this exopolysaccharide were identified by screening for derivatives of strain Rm1021 that formed mucoid colonies that fluoresced extremely brightly under UV light when grown on medium containing Calcofluor. The exopolysaccharide produced in large quantities by the exoR95::Tn5 and exoS96::Tn5 strains was indistinguishable from that produced by the parental strain Rm1021, and its synthesis required the function of at least the exoA, exoB, and exoF genes. Both the exoR and exoS loci were located on the chromosome, and the exo96::Tn5 mutation was 84% linked to the trp-33 mutation by ?M12 transduction. Synthesis of the Calcofluor-binding exopolysaccharide by strain Rm1021 was greatly stimulated by starvation for ammonia. In contrast, the exoR95::Tn5 mutant produced high levels of exopolysaccharide regardless of the presence or absence of ammonia in the medium. The exoS96::Tn5 mutant produced elevated amounts of exopolysaccharide in the presence of ammonia, but higher amounts were observed after starvation for ammonia. The presence of either mutation increased the level of expression of exoF::TnphoA and exoP::TnphoA fusions. Analyses of results obtained when alfalfa seedlings were inoculated with the exoR95::Tn5 strain indicated that the mutant strain could not invade nodules. However, pseudorevertants that retained the original exoR95::Tn5 mutant but acquired unlinked suppressors so that they produced an approximately normal amount of exopolysaccharide were able to invade nodules and fix nitrogen

314

Rhizobium meliloti mutants that overproduce the R. meliloti acidic Calcofluor-binding exopolysaccharide  

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The acidic Calcofluor-binding exopolysaccharide of Rhizobium meliloti Rm1021 plays one or more critical roles in nodule invasion and possible in nodule development. Two loci, exoR and exoS, that effect the regulation of synthesis of this exopolysaccharide were identified by screening for derivatives of strain Rm1021 that formed mucoid colonies that fluoresced extremely brightly under UV light when grown on medium containing Calcofluor. The exopolysaccharide produced in large quantities by the exoR95::Tn5 and exoS96::Tn5 strains was indistinguishable from that produced by the parental strain Rm1021, and its synthesis required the function of at least the exoA, exoB, and exoF genes. Both the exoR and exoS loci were located on the chromosome, and the exo96::Tn5 mutation was 84% linked to the trp-33 mutation by {Phi}M12 transduction. Synthesis of the Calcofluor-binding exopolysaccharide by strain Rm1021 was greatly stimulated by starvation for ammonia. In contrast, the exoR95::Tn5 mutant produced high levels of exopolysaccharide regardless of the presence or absence of ammonia in the medium. The exoS96::Tn5 mutant produced elevated amounts of exopolysaccharide in the presence of ammonia, but higher amounts were observed after starvation for ammonia. The presence of either mutation increased the level of expression of exoF::TnphoA and exoP::TnphoA fusions. Analyses of results obtained when alfalfa seedlings were inoculated with the exoR95::Tn5 strain indicated that the mutant strain could not invade nodules. However, pseudorevertants that retained the original exoR95::Tn5 mutant but acquired unlinked suppressors so that they produced an approximately normal amount of exopolysaccharide were able to invade nodules and fix nitrogen.

Doherty, D.; Glazebrook, J.; Walker, G.C. (Massachusetts Institute of Technology, Cambridge (USA)); Leigh, J.A. (Univ. of Washington, Seattle (USA))

1988-09-01

315

Long-term effects of crop management on Rhizobium leguminosarum biovar viciae populations.  

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Little is known about factors that affect the indigenous populations of rhizobia in soils. We compared the abundance, diversity and genetic structure of Rhizobium leguminosarum biovar viciae populations in soils under different crop managements, i.e., wheat and maize monocultures, crop rotation, and permanent grassland. Rhizobial populations were sampled from nodules of pea- or vetch plants grown in soils collected at three geographically distant sites in France, each site comprising a plot under long-term maize monoculture. Molecular characterization of isolates was performed by PCR-restriction fragment length polymorphism of 16S-23S rDNA intergenic spacer as a neutral marker of the genomic background, and PCR-restriction fragment length 0polymorphism of a nodulation gene region, nodD, as a marker of the symbiotic function. The diversity, estimated by richness in types and Simpson's index, was consistently and remarkably lower in soils under maize monoculture than under the other soil managements at the three sites, except for the permanent grassland. The highest level of diversity was found under wheat monoculture. Nucleotide sequences of the main rDNA intergenic spacer types were determined and sequence analysis showed that the prevalent genotypes in the three maize fields were closely related. These results suggest that long-term maize monoculturing decreased the diversity of R. leguminosarum biovar viciae populations and favored a specific subgroup of genotypes, but the size of these populations was generally preserved. We also observed a shift in the distribution of the symbiotic genotypes within the populations under maize monoculture, but the diversity of the symbiotic genotypes was less affected than that of IGS types. The possible effect of such changes on biological nitrogen fixation remains unknown and this requires further investigation. PMID:16329858

Depret, Géraldine; Houot, Sabine; Allard, Marie-Reine; Breuil, Marie-Christine; Nouaïm, Rachida; Laguerre, Gisèle

2004-12-27

316

Visualization of nodulation gene activity on the early stages of Rhizobium leguminosarum bv. viciae symbiosis.  

Science.gov (United States)

A technique was optimized for the in situ detection of nodulation (nod) gene activity in Rhizobium leguminosarum bv. viciae symbiosis with compatible plant hosts Vicia tetrasperma (L.) SCHREB. and Pisum sativum L. The transcription of nodABC-lacZ fusion was visualized as beta-galactosidase (beta-Gal) activity after reaction with the chromogenic substrate X-Gal and subsequent light microscopy, while the background of the indigenous beta-Gal activity of rhizobia and the host plant was eliminated by glutaraldehyde treatment. V. tetrasperma was suggested as a suitable model plant for pea cross-inoculation group due to its advantages over the common model of V. hirsuta (L.) S.F. GRAY: compactness of the plant, extremely small seeds, fast development and stable nodulation under laboratory conditions. In the roots of both plants, a certain extent of nod gene activity was detectable in all rhizobia colonizing the rhizoplane. In pea 1 d after inoculation (d.a.i.), the maximum was localized in the region of emerging root hairs (RH) later (3 and 6 d.a.i.) shifting upwards from the root tip. Nodulation genes sustained full expression even in the infection threads inside the RH and the root cortex, independently of their association with nodule primordia. Comparison of two pea symbiotic mutant lines, Risnod25 and Risnod27, with the wild type did not reveal any differences in the RH formation, RH curling response and rhizoplane colonization. Both mutants appeared to be blocked at the infection thread initiation stage and in nodule initiation, consistent with the phenotype caused by other mutant alleles in the pea sym8 locus. Judging from the nod gene expression level and pattern in the rhizoplane, flavonoid response upon inoculation is preserved in both pea mutants, being independent of infection thread and nodule initiation. PMID:16408851

Chovanec, P; Novák, K

2005-01-01

317

Draft Genome Sequence of Rhizobium mesoamericanum STM3625, a Nitrogen-Fixing Symbiont of Mimosa pudica Isolated in French Guiana (South America)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Moulin, Lionel; Mornico, Damien; Melkonian, Re?my; Klonowska, Agnieszka

2013-01-01

318

Growth, nodulation and yield of mash bean (Vigna mungo L. as affected by Rhizobium inoculation and soil applied L-tryptophan  

Directory of Open Access Journals (Sweden)

Full Text Available Most of the grain legumes in Pakistan are poorly nodulated either because of low indigenous rhizobialpopulation or due to inefficient strains of native rhizobia. However, improvement in nodulation could be achievedthrough inoculation with effective rhizobial strains. A pot trial was conducted to evaluate the effect of Rhizobiuminoculation along with L-tryptophan (L-TRP, a precursor of indole acetic acid (IAA on growth, yield andnodulation of mash been. The results indicated that Rhizobium inoculation along with L-tryptophan application (6mg kg-1 soil significantly improved plant height (44.6% as compared to control. Different improvements in rootlength (72.4%, oven dry root weight (Five fold, no. of pods plant-1 (86.4%, no. of grains per pod (42.8%, 100-grain weight (18.9% and nitrogen concentration in grains (two fold, was noted as compared with the controlwhere L-TRP was applied @ 2 mg kg-1 soil. There was a significant increase in number of nodules plant-1 (one fold,nodule fresh weight plant-1 (two fold and nodule dry weight plant-1 (four fold with Rhizobium inoculation alongwith L-TRP application @ 2 mg kg-1 soil as compared to Rhizobium inoculation alone. The study showed thatRhizobium inoculation along with L-TRP application could be a better approach for sustainable legume production.

Muhammad Iqbal Hussain*, Muhammad Javed Akhtar, Hafiz Naeem Asghar and Maqshoof Ahmad

2011-04-01

319

Draft Genome Sequence of Rhizobium mesoamericanum STM3625, a Nitrogen-Fixing Symbiont of Mimosa pudica Isolated in French Guiana (South America).  

Science.gov (United States)

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

Moulin, Lionel; Mornico, Damien; Melkonian, Rémy; Klonowska, Agnieszka

2013-01-01

320

Détermination expérimentale des isothermes de sorption et de la chaleur isostérique des feuilles d'absinthe et de menthe pouliot  

Digital Repository Infrastructure Vision for European Research (DRIVER)

La détermination des isothermes de sorption est une étape indispensable et un moyen privilégié pour connaitre la répartition et l'intensité des liaisons de l'eau dans les produits agro-alimentaires. Ces isothermes permettent de déterminer la teneur en eau finale à atteindre pour optimiser les conditions de stockage et de séchage de ces produits et donnent des informations précieuses sur l'équilibre hygroscopique du produit à sécher et à conserver. Cette étude vise d'une part à...

Lamharrar, Abdelkader; Kane, Cheikh Sidi Ethmane; Idlimam, Ali; Akkad, Siham; Kouhila, Mohammed; Mimet, Abdelaziz; Ahachad, Mohamed

2007-01-01

 
 
 
 
321

Genetic Factors in Rhizobium Affecting the Symbiotic Carbon Costs of N2 Fixation and Host Plant Biomass Production  

DEFF Research Database (Denmark)

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.

SkØt, L.

1986-01-01

322

Lipid A biosynthesis in Rhizobium leguminosarum: Role of a 2-keto-3-deoxyoctulosonate-activated 4{prime} phosphatase  

Energy Technology Data Exchange (ETDEWEB)

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.

Price, N.P.J.; Jeyaretnam, B.; Carlson, R.W. [Univ. of Georgia, Athens, GA (United States)] [and others

1995-08-01

323

Rhizobium leguminosarum is the symbiont of lentils in the Middle East and Europe but not in Bangladesh.  

Science.gov (United States)

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

Harun-or Rashid, M; Gonzalez, Javier; Young, J Peter W; Wink, Michael

2014-01-01

324

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

325

Homo- and heterotypic interactions between Pss proteins involved in the exopolysaccharide transport system in Rhizobium leguminosarum bv. trifolii.  

Science.gov (United States)

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

Marczak, Ma?gorzata; D?wierzy?ska, Monika; Skorupska, Anna

2013-04-01

326

Homology of genes for exopolysaccharide synthesis in Rhizobium leguminosarum and effect of cloned exo genes on nodule formation  

Energy Technology Data Exchange (ETDEWEB)

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.

Skorupska, A.; Derylo, M. [Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland)

1993-12-31

327

Expression of Rhizobium leguminosarum CFN42 genes for lipopolysaccharide in strains derived from different R. leguminosarum soil isolates  

Energy Technology Data Exchange (ETDEWEB)

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.

Brink, B.A.; Noel, K.D. (Marquette Univ., Milwaukee, WI (USA)); Miller, J.; Carlson, R.W. (Eastern Illinois Univ., Charlston (USA))

1990-02-01

328

Validación técnica de inoculantes en frijol con cepas de rhizobium eficientes en fijación de nitrógeno en Centroamérica  

Directory of Open Access Journals (Sweden)

Full Text Available Se realizó un ensayo de validación técnica de inoculantes en frijol elaborado con cepas de Rhizobium eficientes en fijación biológica de nitrógeno, con el objetivo de recabar mayor información sobre la bondad de esta tecnología en la producción comercial de frijol. El ensayo regional se sembró en 45 sitios, distribuidos en Costa Rica (20, Panamá (10, Nicaragua (10 y El Salvador (5, durante 1998 y 1999. Se incluyeron cuatro tratamientos: 1. Testigo absoluto; 2. Inoculado; 3. Fertilización intermedia e inoculación; 4. Fertilización recomendada (Fer Rec. El inoculante fue preparado y distribuido por la Universidad de Costa Rica; la variedad y la fertilización utilizada en los tratamientos tres y cuatro, fueron las recomendadas localmente. La parcela experimental varió de 50 a 100 m2 y se utilizó un diseño de bloques al azar, con tres repeticiones. Se cosecharon 39 ensayos y se registraron rendimientos de grano y costos de producción. El análisis de varianza por áreas de producción y países, utilizó el promedio por sitio; el análisis económico fue de presupuesto parcial. Los resultados mostraron lo siguiente: a la respuesta del frijol a la inoculación con Rhizobium y/o fertilizantes, varió de un sitio a otro; b el análisis regional mostró respuesta del rendimiento al uso de inoculante y en el 80% de los casos el análisis económico, seleccionó a la inoculación como redituable; c a excepción de Panamá, el uso de la mitad del fertilizante recomendado más inoculación, fue superior al tratamiento con sólo inoculante

Oscar Acu\\u00F1a

2001-01-01

329

Biosynthesis of Rhizobium meliloti lipooligosaccharide Nod factors: NodA is required for an N-acyltransferase activity  

Energy Technology Data Exchange (ETDEWEB)

Rhizobium bacteria synthesize N-acylated [beta]-1,4-N-acetylglucosamine lipooligosaccharides, called Nod factors, which act as morphogenic signal molecules to legume roots during development of nitrogen-fixing nodules. The biosynthesis of Nod factors is genetically dependent upon the nodulation (nod) genes, including the common nod genes nodABC. We used the Rhizobium meliloti NodH sulfotransferase to prepare [sup 35]S-labeled oligosaccharides which served as metabolic tracers for Nod enzyme activities. This approach provides a general method for following chitooligosaccharide modifications. We found nodAB-dependent conversion of N-acetylchitotetraose (chitotetraose) monosulfate into hydrophobic compounds which by chromatographic and chemical tests were equivalent to acylated Nod factors. Sequential incubation of labeled intermediates with Escherichia coli containing either NodA or NodB showed that NodB was required before NodA during Nod factor biosynthesis. The acylation activity was sensitive to oligosaccharide chain length, with chitotetraose serving as a better substrate than chitobiose or chitotriose. We constructed a putative Nod factor intermediate, GlcN-[beta]1,4-(GlcNac)[sub 3], by enzymatic synthesis and labeled it by NodH-mediated sulfation to create a specific metabolic probe. Acylation of this oligosaccharide required only NodA. These results confirm previous reports that NodB is an N-deacetylase and suggest that NodA is an N-acyltransferase. 31 refs., 6 figs.

Atkinson, E.M.; Long, S.R. (Stanford Univ., CA (United States)); Palcic, M.M.; Hindsgaul, O. (Univ. of Alberta, Edmonton (Canada))

1994-08-30

330

Role of Some Chemical Compounds on the Detoxification of Rhizobium leguminsarum biovar vicia by Some Heavy Metals  

Directory of Open Access Journals (Sweden)

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.

Sanaa Mostafa El-Deeb

2005-01-01

331

Biological nitrogen fixation by Rhizobium sp. native gliricidia (Gliricidia sepium [Jacq.] Kunth ex Walp. under greenhouse conditions  

Directory of Open Access Journals (Sweden)

Full Text Available

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 (Rhizobiolc. Suspensions of 106 and 108 cells/mL for each of the strains studied 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.

Milian Mindiola Pablo Ernesto

2011-12-01

332

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)

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.

Raúl Carlos, López Sánchez; Roeland, Samson; Patrick, Vandamme; Bettina, Eichler-Löbermann; Ernesto, Gómez Padilla.

2011-06-01

333

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)

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.

Raúl Carlos, López Sánchez; Roeland, Samson; Patrick, Vandamme; Bettina, Eichler-Löbermann; Ernesto, Gómez Padilla.

334

Rhizobium meliloti mutants that overproduce the R. meliloti acidic calcofluor-binding exopolysaccharide.  

Science.gov (United States)

The acidic Calcofluor-binding exopolysaccharide of Rhizobium meliloti Rm1021 plays one or more critical roles in nodule invasion and possibly in nodule development. Two loci, exoR and exoS, that affect the regulation of synthesis of this exopolysaccharide were identified by screening for derivatives of strain Rm1021 that formed mucoid colonies that fluoresced extremely brightly under UV light when grown on medium containing Calcofluor. The exopolysaccharide produced in large quantities by the exoR95::Tn5 and exoS96::Tn5 strains was indistinguishable from that produced by the parental strain Rm1021, and its synthesis required the function of at least the exoA, exoB, and exoF genes. Both the exoR and exoS loci were located on the chromosome, and the exo96::Tn5 mutation was 84% linked to the trp-33 mutation by phi M12 transduction. Synthesis of the Calcofluor-binding exopolysaccharide by strain Rm1021 was greatly stimulated by starvation for ammonia. In contrast, the exoR95::Tn5 mutant produced high levels of exopolysaccharide regardless of the presence or absence of ammonia in the medium. The exoS96::Tn5 mutant produced elevated amounts of exopolysaccharide in the presence of ammonia, but higher amounts were observed after starvation for ammonia. The presence of either mutation increased the level of expression of exoF::TnphoA and exoP::TnphoA fusions (TnphoA is Tn5 IS50L::phoA). Analyses of results obtained when alfalfa seedlings were inoculated with the exoR95::Tn5 strain indicated that the mutant strain could not invade nodules. However, pseudorevertants that retained the original exoR95::Tn5 mutation but acquired unlinked suppressors so that they produced an approximately normal amount of exopolysaccharide were able to invade nodules and fix nitrogens. The exoS95::Tn5 strain formed Fix+ nodules, although some minor variability was observed. PMID:2842307

Doherty, D; Leigh, J A; Glazebrook, J; Walker, G C

1988-09-01

335

Exo-oligosaccharides of Rhizobium sp. strain NGR234 are required for symbiosis with various legumes.  

Science.gov (United States)

Rhizobia are nitrogen-fixing bacteria that establish endosymbiotic associations with legumes. Nodule formation depends on various bacterial carbohydrates, including lipopolysaccharides, K-antigens, and exopolysaccharides (EPS). An acidic EPS from Rhizobium sp. strain NGR234 consists of glucosyl (Glc), galactosyl (Gal), glucuronosyl (GlcA), and 4,6-pyruvylated galactosyl (PvGal) residues with beta-1,3, beta-1,4, beta-1,6, alpha-1,3, and alpha-1,4 glycoside linkages. Here we examined the role of NGR234 genes in the synthesis of EPS. Deletions within the exoF, exoL, exoP, exoQ, and exoY genes suppressed accumulation of EPS in bacterial supernatants, a finding that was confirmed by chemical analyses. The data suggest that the repeating subunits of EPS are assembled by an ExoQ/ExoP/ExoF-dependent mechanism, which is related to the Wzy polymerization system of group 1 capsular polysaccharides in Escherichia coli. Mutation of exoK (NGROmegaexoK), which encodes a putative glycanase, resulted in the absence of low-molecular-weight forms of EPS. Analysis of the extracellular carbohydrates revealed that NGROmegaexoK is unable to accumulate exo-oligosaccharides (EOSs), which are O-acetylated nonasaccharide subunits of EPS having the formula Gal(Glc)5(GlcA)2PvGal. When used as inoculants, both the exo-deficient mutants and NGROmegaexoK were unable to form nitrogen-fixing nodules on some hosts (e.g., Albizia lebbeck and Leucaena leucocephala), but they were able to form nitrogen-fixing nodules on other hosts (e.g., Vigna unguiculata). EOSs of the parent strain were biologically active at very low levels (yield in culture supernatants, approximately 50 microg per liter). Thus, NGR234 produces symbiotically active EOSs by enzymatic degradation of EPS, using the extracellular endo-beta-1,4-glycanase encoded by exoK (glycoside hydrolase family 16). We propose that the derived EOSs (and not EPS) are bacterial components that play a crucial role in nodule formation in various legumes. PMID:16923883

Staehelin, Christian; Forsberg, Lennart S; D'Haeze, Wim; Gao, Mu-Yun; Carlson, Russell W; Xie, Zhi-Ping; Pellock, Brett J; Jones, Kathryn M; Walker, Graham C; Streit, Wolfgang R; Broughton, William J

2006-09-01

336

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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, c [...] om 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. Abstract in english 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.

Eulene Francisco da, Silva; Marlene Estevão, Marchetti; Luiz Carlos Ferreira de, Souza; Fábio Martins, Mercante; Edson Talarico, Rodrigues; Antonio Carlos Tadeu, Vitorino.

337

Social bookmarking et tags structurés  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nous présentons dans cet article les enjeux du rapprochement entre les techniques du web participatif (Web 2.0) et du web sémantique. Nous expliquons ensuite les limites des outils actuels explorant cette piste mais qui, malgré l'emploi de tags, conservent une part de rigidité liée aux ontologies sous-jacentes employées. Nous décrivons finalement l'ajout à un outil de social bookmarking de trois fonctionnalités permettant la structuration progressive de tags par une communauté tout ...

Huynh-kim-bang, Benjamin; Dane?, Eric

2008-01-01

338

AVALIAÇÃO DA FIXAÇÃO BIOLÓGICA DO NITROGÊNIO EM GENÓTIPOS DE FEIJOEIROS TOLERANTES A SECA / EVALUATION OF BIOLOGICAL FIXATION OF NITROGEN IN RHIZOBIUM UNDER WATER DEFICIT  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: Portuguese Abstract in portuguese Vários fatores como a temperatura, acidez do solo, teor de nutrientes e cultivar, interferem na eficiência simbiótica das estirpes de Rhizobium em condições de campo. Com objetivo de avaliar a capacidade de fixação biológica de nitrogênio de estirpes nativas de Rhizobium sp. foi realizado um experim [...] ento em vasos montado no delineamento inteiramente casualizado no esquema fatorial 10x7 (10 linhagens de feijoeiro consideradas tolerantes ao déficit hídrico, sendo estas: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano e Preto Meia Lua e 7 inoculantes isolados dos solos dos municipios de Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares e Alegre, no estado do Espírito Santo, com quatro repetições. Os dados demonstraram que a fixação biológica de N2 utilizando a inoculação de estirpes eficientes de Rhizobium em cultivar nodulante de feijoeiro ou seu cultivo em solos com população nativa eficiente, pode possibilitar a suplementação ou até mesmo á não utilização de nitrogênio em cobertura na cultura do feijoeiro, sem perdas no rendimento da produtividade. Abstract in english Several factors as the temperature, soil acidity, content of nutrients and cultivate interfere in the symbiotic efficiency of the ancestries of Rhizobium infield conditions. With the objective of evaluating the capacity of biological fixation of nitrogen of native ancestries of Rhizobium sp. an expe [...] riment was accomplished in vases set up in the delineate entirely casualty in the factorial outline 10x7 (10 bean plant lineages considered tolerant to the water deficit, being these: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano and Preto Meia Lua and 7 isolated inoculate of the soils of the municipal districts of Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares and Alegre in Espírito Saint state, with four repetitions. The data demonstrated that the biological fixation of N2 using the inoculation of efficient ancestries of Rhizobium in cultivating bean plant nodule cultivation in soils with efficient native population, it can make possible the supplement or even to the not use of nitrogen in covering in the culture bean plant, without losses in the income of the productivity.

Willian, Bucker Moraes; Sebastião, Martins Filho; Giovanni de Oliveira, Garcia; Simone de Paiva, Caetano; Wanderson, Bucker Moraes; Fernando, Carrara Cosmi.

339

AVALIAÇÃO DA FIXAÇÃO BIOLÓGICA DO NITROGÊNIO EM GENÓTIPOS DE FEIJOEIROS TOLERANTES A SECA EVALUATION OF BIOLOGICAL FIXATION OF NITROGEN IN RHIZOBIUM UNDER WATER DEFICIT  

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Full Text Available Vários fatores como a temperatura, acidez do solo, teor de nutrientes e cultivar, interferem na eficiência simbiótica das estirpes de Rhizobium em condições de campo. Com objetivo de avaliar a capacidade de fixação biológica de nitrogênio de estirpes nativas de Rhizobium sp. foi realizado um experimento em vasos montado no delineamento inteiramente casualizado no esquema fatorial 10x7 (10 linhagens de feijoeiro consideradas tolerantes ao déficit hídrico, sendo estas: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano e Preto Meia Lua e 7 inoculantes isolados dos solos dos municipios de Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares e Alegre, no estado do Espírito Santo, com quatro repetições. Os dados demonstraram que a fixação biológica de N2 utilizando a inoculação de estirpes eficientes de Rhizobium em cultivar nodulante de feijoeiro ou seu cultivo em solos com população nativa eficiente, pode possibilitar a suplementação ou até mesmo á não utilização de nitrogênio em cobertura na cultura do feijoeiro, sem perdas no rendimento da produtividade.Several factors as the temperature, soil acidity, content of nutrients and cultivate interfere in the symbiotic efficiency of the ancestries of Rhizobium infield conditions. With the objective of evaluating the capacity of biological fixation of nitrogen of native ancestries of Rhizobium sp. an experiment was accomplished in vases set up in the delineate entirely casualty in the factorial outline 10x7 (10 bean plant lineages considered tolerant to the water deficit, being these: Amarelinho, Macuquinho, Imperial, EL 22, BATT 477, Uirapuru, IAPAR-81, Bate Estrada, Serrano and Preto Meia Lua and 7 isolated inoculate of the soils of the municipal districts of Colatina, Vila Pavão, Nova Venécia, Pinheiros, Sooretama, Linhares and Alegre in Espírito Saint state, with four repetitions. The data demonstrated that the biological fixation of N2 using the inoculation of efficient ancestries of Rhizobium in cultivating bean plant nodule cultivation in soils with efficient native population, it can make possible the supplement or even to the not use of nitrogen in covering in the culture bean plant, without losses in the income of the productivity.

Willian Bucker Moraes

2010-04-01

340

In vitro Survival and Nematicidal Activity of Rhizobium, Bradyrhizobium and Sinorhizobium. I. The Influence of Various NaCl Concentrations  

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Full Text Available During the survey of the cultivated fields in Karachi and neighborhood (Southern Sindh, 3 strains of Rhizobium phaseoli, 1 strain of R. leguminosarum and R. trifolii each, 5 strains of Sinorhizobium meliloti, 2 strains of Bradyrhizobium japonicum and 3 strains of Bradyrhizobium sp. were isolated and identified. The 15 strains of rhizobia tested for their growth under saline media exhibited varying degree of effects to salt concentrations. Most resistant strain was that of S. meliloti MAT1(R9 while least resistant was that of Bradyrhizobium sp. VRM1(R13. All the rhizobial strains caused significant mortality of Meloidogyne incognita, the root-knot nematode juveniles in vitro, though the strains differed markedly in their toxic activity. The rhizobial strains showed significant interaction with NaCl salinity towards M. incognita

S. Shahid Shaukat

2002-01-01

 
 
 
 
341

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

Science.gov (United States)

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

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

2013-04-01

342

Identification of a NodD repressible gene adjacent to nodM in Rhizobium leguminosarum biovar viciae.  

Science.gov (United States)

The nodFEL and nodMNT operons in Rhizobium leguminosarum biovar viciae are transcribed in the same orientation and induced by NodD in response to flavonoids secreted by legumes. In the narrow intergenic region between nodFEL and nodMNT, we identified a small gene divergently transcribed from nodM to the 3' end of nodL. Unlike the promoters upstream of nodF and nodM, the promoter of this gene is constitutively expressed. It appeared that its promoter might partially overlap with that of nodM and its expression was repressed by nodD. A deletion mutation was made and proteins produced by the mutant were compared with those by wild-type using 2D gel electrophoresis. Several protein differences were identified suggesting that this small gene influences the expression or stability of these proteins. However, the mutant nodulated its host plant (pea) normally. PMID:22337919

Yang, Xiao'er; Hou, Bihe; Zong, Chenzhi; Hong, Guofan

2012-04-01

343

Morphogenesis of root nodules in white clover. I. Effective root nodules induced by the wild type Rhizobium leguminosarium biovar. trifolii  

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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.

Barbara ?otocka

1997-12-01

344

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

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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.

S Perotto

2009-12-01

345

Mechanisms of protection of pea plants by polysaccharides extracted from a strain of Rhizobium against Orobanche crenata  

International Nuclear Information System (INIS)

The Broomrape causes notable damage on the leguminous crops and became major factor limiting production of pea in the Mediterranean region. The effect of the polysaccharides extracted from P.SOM Rhizobium strain on the development of Orobanche crenata on pea was studied. The results showed that the lipopolysaccharides significantly reduce the infestation of pea by O. crenata. This limitation of infestation results from the reduction of seeds germination rates of the parasite resulting in reduction of the tubercles number on pea roots. Moreover, necrosis of orobanche before or after attachment on pea roots treated by LPS can explain this reduction of parasitism. A correlation was observed between the reduction of pea infection by the broomrape and the activation phenolic compounds pathway. This activation resulted to increase of two enzymes (peroxidase and polyphenoloxidase) activities these enzymes are implicated in plant defense. The results of our study showed that the LPS seem implied in the induction of pea resistance against the broomrape.

346

Fluorescence studies with malate dehydrogenase from rhizobium japonicum 3I1B-143 bacteroids: a two-tryptophan containing protein  

Science.gov (United States)

A number of fluorescence studies, both of trp residues and bound NADH, have been reported for porcine MDH. The large number of trp residues (6) complicates the interpretation of some studies. To circumvent this we have performed studies with a two tryptophan (per subunit) MDH from Rhizobium japonicum 311B-143 bacteroids. We have performed phase/modulation fluorescence lifetime measurements, as a function of temperature and added quencher KI, in order to resolved the 1.3 ns (blue) and 6.6 ns (red) contributions from the two classes of trp residues. Anisotropy decay studies have also been performed. The binding of NADH dynamically quenches the fluorescence of both tip residues, but, unlike mammalian cytoplasmic and mitochondrial MDH, there is not a large enhancement in fluorescence of bound NADH upon forming a ternary complex with either tartronic acid or D-malonate.

Ghiron, Camillo A.; Eftink, Maurice R.; Waters, James K.; Emerich, David W.

1990-05-01

347

Comparison of the nitrogen-15 and conventional methods to determine N2 fixing capacity of chickpea by rhizobium strains  

International Nuclear Information System (INIS)

The N2 fixing capacity of 8 strains of rhizobium ciceri (45, 68, 51,620, 29,18,23 and 31) in association with two cicer cultivars (Akcin-91 and Izmir-92) was evaluated under growth room conditions as a preliminary screening prior to field experimentation. The ''1''5N isotope method (A-value) was used to quantify the % Ndfa and actual amounts of N2 fixed. In addition to this, other conventional methods (dry matter, N content, total N uptake, difference method and symbiotic effectiveness) were also investigated in the comparison. The results obtained show that 18 and 31 number of strains could be successfully used as inoculant both cultivar

348

Growth behaviour and indole acetic acid (IAA) production by a Rhizobium isolated from root nodules of Alysicarpus vaginalis DC.  

Science.gov (United States)

From the root nodules of Alysicarpus vaginalis DC, the symbiont was isolated and identified as a Rhizobium sp. The bacteria produced a high amount (107 microg/ml) of indole acetic acid (IAA) in culture from tryptophan supplemented yeast extract mannitol medium. The isolate preferred L-isomer of tryptophan for maximum IAA production. The production was maximum when the bacteria reached its stationary phase of growth. The production of IAA could be increased up to 70% over yeast extract glucose medium by supplementing ZnSO4, 7H2O (0.5 microg/ml). L-asparagine (0.2%) and sodium dodecyl sulfate (1.0 microg/ml). The possible relationship between the rhizobial IAA production and legume-rhizobia symbiosis is discussed. PMID:10735189

Bhattacharyya, R N; Pati, B R

2000-01-01

349

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)

350

Screening of isolates and strains of Rhizobium leguminosarum biovar trifolii for heavy metal resistance using buffered media  

Energy Technology Data Exchange (ETDEWEB)

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.

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

351

Mutation of the sensor kinase chvG in Rhizobium leguminosarum negatively impacts cellular metabolism, outer membrane stability, and symbiosis.  

Science.gov (United States)

Two-component signal transduction systems (TCS) are a main strategy used by bacteria to sense and adapt to changes in their environment. In the legume symbiont Rhizobium leguminosarum biovar viciae VF39, mutation of chvG, a histidine kinase, caused a number of pleiotropic phenotypes. ChvG mutants are unable to grow on proline, glutamate, histidine, or arginine as the sole carbon source. The chvG mutant secreted smaller amounts of acidic and neutral surface polysaccharides and accumulated abnormally large amounts of poly-ß-hydroxybutyrate. Mutation of chvG caused symbiotic defects on peas, lentils, and vetch; nodules formed by the chvG mutant were small and white and contained only a few cells that had failed to differentiate into bacteroids. Mutation of chvG also destabilized the outer membrane of R. leguminosarum, resulting in increased sensitivity to membrane stressors. Constitutive expression of ropB, the outer membrane protein-encoding gene, restored membrane stability and rescued the sensitivity phenotypes described above. Similar phenotypes have been described for mutations in other ChvG-regulated genes encoding a conserved operon of unknown function and in the fabXL genes required for synthesis of the lipid A very-long-chain fatty acid, suggesting that ChvG is a key component of the envelope stress response in Rhizobium leguminosarum. Collectively, the results of this study demonstrate the important and unique role the ChvG/ChvI TCS plays in the physiology, metabolism, and symbiotic competency of R. leguminosarum. PMID:22155778

Vanderlinde, Elizabeth M; Yost, Christopher K

2012-02-01

352

ESTABLECIMIENTO Y RESPUESTAS FISIOLÓGICAS DE LA SIMBIOSIS Rhizobium tropici-Leucaena leucocephala EN PRESENCIA DE FENANTRENO Y NAFTALENO  

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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 (CloroT 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.

Carlos L\\u00D3PEZ-ORTIZ

2012-01-01

353

Nodulation inhibition by Rhizobium leguminosarum multicopy nodABC genes and analysis of early stages of plant infection.  

Science.gov (United States)

During analysis of early events in the infection and nodulation of Vicia hirsuta roots inoculated with normal and mutant strains of Rhizobium leguminosarum and strains containing cloned nodulation (nod) genes, a number of novel observations were made. (i) Alternating zones of curled and straight root hairs were seen on roots of V. hirsuta inoculated with the wild-type strain of R. leguminosarum. This phasing of root hair curling was not seen if plants were grown under continuous light or continuous dark conditions. (ii) Reduced nodulation and delayed nodule initiation was observed with a strain carrying a Tn5 mutation in the nodE gene. In addition the phased root hair curling was absent, and root hair curling was observed along the length of the root. (iii) The nodABC genes cloned on a multicopy plasmid in a wild-type strain inhibited nodulation but induced a continuous root hair curling response. Those few nodules that eventually formed were found to contain bacteria which had lost the plasmid carrying the nodABC genes. (iv) With a strain of Rhizobium cured of its indigenous symbiotic plasmid, but containing the cloned nodABCDEF genes, continuous root hair curling on V. hirsuta was observed. However, no infection threads were observed, and surprisingly, it did appear that initial stages of nodule development occurred. Observations of thin sections of these early developing nodules indicated that early nodule meristematic divisions may have occurred but that no bacteria were found within the nodules and no infection threads were observed either within the nodule bumps or within any of the root hairs. It was concluded that for normal infections to occur, precise regulation of the nod genes is required and that overexpression of the root hair curling genes inhibits the normal infection process. PMID:3009408

Knight, C D; Rossen, L; Robertson, J G; Wells, B; Downie, J A

1986-05-01

354

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.

355

Synthesis and adsorption properties of titanosilicates ETS-4 and ETS-10 from fly ash  

Energy Technology Data Exchange (ETDEWEB)

Highlights: {yields} Titanosilicates (ETS-4 and ETS-10) have been synthesized from waste fly ash. {yields} These materials showed similar properties to those prepared from traditional starting materials. {yields} The supernatant liquid after product formation (ETS-4) can be recycled and the final by-product is NaCl. {yields} These materials can be used for CO{sub 2}/CH{sub 4} and N{sub 2} 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.

Liu, Liying [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China); Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Department of Chemical Engineering, Monash University, Clayton, Victoria 3800 (Australia); Singh, Ranjeet, E-mail: Ranjeet.Singh@monash.edu [Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Department of Chemical Engineering, Monash University, Clayton, Victoria 3800 (Australia); Li, Gang; Xiao, Penny; Webley, Paul [Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Department of Chemical Engineering, Monash University, Clayton, Victoria 3800 (Australia); Zhai, Yuchun [School of Material and Metallurgy, Northeastern University, Shenyang, Liaoning 110004 (China)

2011-11-15

356

Survival and nodulating ability of indigenous and inoculated Rhizobium leguminosarum biovar trifolii in sterilized and unsterilized soil treated with sewage sludge.  

Science.gov (United States)

Rhizobium leguminosarum biovar trifolii was detected in soil from 41 of 47 plots, within nine sewage sludge-treated sites with different soil characteristics and heavy metal contents. However, although population size varied widely, there was no consistent correlation with soil heavy metal concentration. Indigenous populations in 20 plots within four selected sites retained their ability to induce effective nodule formation after incubation of soil in the dark for 165 days. In sterilized (gamma-irradiated) soil, Rhizobium survival varied from 0.01% to 95% depending on the soil sample and strain used. Metal-resistant strains with non-mucoid colonies survived less well than mucoid metal-sensitive strains. PMID:11116399

Purchase, D; Miles, R J

2001-01-01

357

Bouvard et Pécuchet et le désir amoureux  

Digital Repository Infrastructure Vision for European Research (DRIVER)

L’article propose une étude de genèse du chapitre 7 de Bouvard et Pécuchet, consacré à l’amour, qui forme une étape encyclopédique a priori un peu surprenante. Flaubert s’amuse à écrire ces aventures de Bouvard et Pécuchet, dans un pays qui n’est pas si tendre. L’étude de genèse porte sur le travail de l’écriture de plusieurs temps forts du chapitre (dans l’incipit, et les scènes de duos, notamment la scène entre Mme Castillon et Gorgu). Elle permet de montrer l?...

Anne Herschberg Pierrot

2010-01-01

358

Characterization of RFRS9, a second member of the Rhizobium fredii repetitive sequence family from the nitrogen-fixing symbiont R. fredii USDA257.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The genome of the nitrogen-fixing symbiont, Rhizobium fredii USDA257, contains nine copies of repetitive sequences known as the R. fredii repetitive sequence (RFRS) family. We previously sequenced RFRS3, which is linked to symbiosis plasmid-borne nodulation genes of this organism and has substantial homology to the T-DNA of Agrobacterium rhizogenes and lesser homology to reiterated sequences of Bradyrhizobium japonicum. Here we characterize a second family member, RFRS9. The EcoRI fragment co...

Krishnan, H. B.; Pueppke, S. G.

1993-01-01

359

Analysis of Poly-?-Hydroxybutyrate in Rhizobium japonicum Bacteroids by Ion-Exclusion High-Pressure Liquid Chromatography and UV Detection †  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ion-exclusion high-pressure liquid chromatography (HPLC) was used to measure poly-?-hydroxybutyrate (PHB) in Rhizobium japonicum bacteroids. The products in the acid digest of PHB-containing material were fractionated by HPLC on Aminex HPX-87H ion-exclusion resin for organic acid analysis. Crotonic acid formed from PHB during acid digestion was detected by its intense absorbance at 210 nm. The Aminex-HPLC method provides a rapid and simple chromatographic technique for routine analysis of or...

Karr, Dale B.; Waters, James K.; Emerich, David W.

1983-01-01

360

In vitro sulfotransferase activity of Rhizobium meliloti NodH protein: lipochitooligosaccharide nodulation signals are sulfated after synthesis of the core structure.  

Science.gov (United States)

The Rhizobium common nod gene products NodABC are involved in the synthesis of the core lipochitooligosaccharide (Nod factor) structure, whereas the products of the host-specific nod genes are necessary for diverse structural modifications, which vary in different Rhizobium species. The sulfate group attached to the Rhizobium meliloti Nod signal is necessary for activity on the host plant alfalfa, while its absence renders the Nod factor active on the non-host plant vetch. This substituent is therefore a major determinant of host specificity. The exact biosynthetic pathway of Nod factors has not been fully elucidated. In particular, it is not known why some chemical modifications are introduced with high fidelity whereas others are inaccurate, giving rise to a family of different Nod factor structures produced by a single Rhizobium strain. Using protein extracts and partially purified recombinant NodH protein obtained from Escherichia coli expressing the R. meliloti nodH gene, we demonstrate here NodH-dependent in vitro sulfotransferase activity. Kinetic analyses with Nod factors, chitooligosaccharides, and their deacetylated derivatives revealed that Nod factors are the preferred substrate for the sulfate transfer. Moreover, the tetrameric Nod factor, NodRm-IV, was a better substrate than the trimer, NodRm-III, or the pentamer, NodRm-V. These data suggest that the core lipochitooligosaccharide structure must be synthesized prior to its host-specific modification with a sulfate group. Since in R. meliloti tetrameric Nod factors are the most abundant and the most active ones, high affinity of NodH for the appropriate tetrameric substrate guarantees its modification and thus contributes to the fidelity of host-specific behavior. Images Fig. 5 PMID:7708710

Schultze, M; Staehelin, C; Rohrig, H; John, M; Schmidt, J; Kondorosi, E; Schell, J; Kondorosi, A

1995-01-01

 
 
 
 
361

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)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish 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.

Alejandro E, Ferrari; Carlos A, Esparrach; Mario A, Galetti; Luis G, Wall.

2010-07-01

362

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)

Full Text Available SciELO Argentina | Language: Spanish Abstract in spanish 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.

Alejandro E, Ferrari; Carlos A, Esparrach; Mario A, Galetti; Luis G, Wall.

363

Isolation of Insertion Sequence ISRLdTAL1145-1 from a Rhizobium sp. (Leucaena diversifolia) and Distribution of Homologous Sequences Identifying Cross-Inoculation Group Relationships.  

Science.gov (United States)

Insertion sequence (IS) element ISRLdTAL1145-1 from Rhizobium sp. (Leucaena diversifolia) strain TAL 1145 was entrapped in the sacB gene of the positive selection vector pUCD800 by insertional inactivation. A hybridization probe prepared from the whole 2.5-kb element was used to determine the distribution of homologous sequences in a diverse collection of 135 Rhizobium and Bradyrhizobium strains. The IS probe hybridized strongly to Southern blots of genomic DNAs from 10 rhizobial strains that nodulate both Phaseolus vulgaris (beans) and Leucaena leucocephala (leguminous trees), 1 Rhizobium sp. that nodulates Leucaena spp., 9 R. meliloti (alfalfa) strains, 4 Rhizobium spp. that nodulate Sophora chrysophylla (leguminous trees), and 1 nonnodulating bacterium associated with the nodules of Pithecellobium dulce from the Leucaena cross-inoculation group, producing distinguishing IS patterns for each strain. Hybridization analysis revealed that ISRLdTAL1145-1 was strongly homologous with and closely related to a previously isolated element, ISRm USDA1024-1 from R. meliloti, while restriction enzyme analysis found structural similarities and differences between the two IS homologs. Two internal segments of these IS elements were used to construct hybridization probes of 1.2 kb and 380 bp that delineate a structural similarity and a difference, respectively, of the two IS homologs. The internal segment probes were used to analyze the structures of homologous IS elements in other strains. Five types of structural variation in homolog IS elements were found. The predominate IS structural type naturally occurring in a strain can reasonably identify the strain's cross-inoculation group relationships. Three IS structural types were found in Rhizobium species that nodulate beans and Leucaena species, one of which included the designated type IIB strain of R. tropici (CIAT 899). Weak homology to the whole IS probe, but not with the internal segments, was found with two Bradyrhizobium japonicum strains. The taxonomic and ecological implications of the distribution of ISRLdTAL1145-1 are discussed. PMID:16349459

Rice, D J; Somasegaran, P; Macglashan, K; Bohlool, B B

1994-12-01

364

Isolation of Insertion Sequence ISRLdTAL1145-1 from a Rhizobium sp. (Leucaena diversifolia) and Distribution of Homologous Sequences Identifying Cross-Inoculation Group Relationships †  

Science.gov (United States)

Insertion sequence (IS) element ISRLdTAL1145-1 from Rhizobium sp. (Leucaena diversifolia) strain TAL 1145 was entrapped in the sacB gene of the positive selection vector pUCD800 by insertional inactivation. A hybridization probe prepared from the whole 2.5-kb element was used to determine the distribution of homologous sequences in a diverse collection of 135 Rhizobium and Bradyrhizobium strains. The IS probe hybridized strongly to Southern blots of genomic DNAs from 10 rhizobial strains that nodulate both Phaseolus vulgaris (beans) and Leucaena leucocephala (leguminous trees), 1 Rhizobium sp. that nodulates Leucaena spp., 9 R. meliloti (alfalfa) strains, 4 Rhizobium spp. that nodulate Sophora chrysophylla (leguminous trees), and 1 nonnodulating bacterium associated with the nodules of Pithecellobium dulce from the Leucaena cross-inoculation group, producing distinguishing IS patterns for each strain. Hybridization analysis revealed that ISRLdTAL1145-1 was strongly homologous with and closely related to a previously isolated element, ISRm USDA1024-1 from R. meliloti, while restriction enzyme analysis found structural similarities and differences between the two IS homologs. Two internal segments of these IS elements were used to construct hybridization probes of 1.2 kb and 380 bp that delineate a structural similarity and a difference, respectively, of the two IS homologs. The internal segment probes were used to analyze the structures of homologous IS elements in other strains. Five types of structural variation in homolog IS elements were found. The predominate IS structural type naturally occurring in a strain can reasonably identify the strain's cross-inoculation group relationships. Three IS structural types were found in Rhizobium species that nodulate beans and Leucaena species, one of which included the designated type IIB strain of R. tropici (CIAT 899). Weak homology to the whole IS probe, but not with the internal segments, was found with two Bradyrhizobium japonicum strains. The taxonomic and ecological implications of the distribution of ISRLdTAL1145-1 are discussed. Images PMID:16349459

Rice, Douglas J.; Somasegaran, Padma; MacGlashan, Kathryn; Bohlool, B. Ben

1994-01-01

365

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)

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.

Jolimar Antonio Schiavo

2003-02-01

366

Séminaires et colloques  

Directory of Open Access Journals (Sweden)

Full Text Available La liste des séminaires et colloques organisés par l’UMR Savoirs et textes durant l’année 2004/2005 est disponible sur le site de cette équipe (http://stl.recherche.univ-lille3.fr.

2006-05-01

367

Modélisation dynamique et SIG  

Directory of Open Access Journals (Sweden)

Full Text Available Méthodes de modélisation dynamique et SIG sont ici couplés. Cette intégration SIG-modélisation dynamique aide à l’élaboration des modèles et constitue un véritable outil de recherche en géographie.

Hélène MATHIAN

1993-12-01

368

Energie et développement  

Directory of Open Access Journals (Sweden)

Full Text Available Cet article introduit le dossier thématique consacré à la relation intime entre énergie et développement. Les auteurs retracent l’importance des énergies fossiles dans la croissance économique du monde occidental dès le XIXe siècle et le rôle central du pétrole au XXe siècle pour s’interroger sur les limites de ce modèle de développement face aux contraintes géologiques et climatiques. Ils examinent le fossé et les malentendus qui séparent les sciences de l’homme  et les sciences de la nature, ainsi que les récentes initiatives de dialogue interdisciplinaire autour de l’économie écologique et de l’écologie industrielle. Ils analysent ensuite les enjeux spécifiques aux pays en développement ainsi que l’inadéquation du système de gouvernance internationale pour faire face aux tensions croissantes liées à la déplétion du pétrole, aux asymétries d’accès et d’exploitation des ressources minérales et aux conséquences environnementales d’une consommation croissante de ressources non renouvelables.

Jacques Grinevald

2011-05-01

369

Morphèmes grammaticaux et cohérence  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Cet article défend l'hypothèse selon laquelle les morphèmes grammaticaux tels que les articles, les temps et les modes verbaux, participent au marquage de l'organisation hiérarchique des contenus et par là même à la cohérence discursive.

Lebas-fraczak, Lidia

2011-01-01

370

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)

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)

Bolzon, B

2007-11-15

371

Migrations et circulations thérapeutiques : Odyssées et espaces  

Directory of Open Access Journals (Sweden)

Full Text Available Après avoir abordé, dans le numéro 3 de la revue Anthropologie & Santé, les questions relatives à la circulation des médecines, mais aussi des outils, usages, savoirs et pratiques arrimés à ces médecines dans la globalisation, le dossier de ce numéro 5 est dédié plus spécifiquement aux circulations contemporaines des pourvoyeurs et des bénéficiaires de soins. Les articles regroupés ici n’épuisent pas l’ensemble des questions et des thématiques soulevées par la mise en lien de la santé, des mo...

Sandrine Musso

2012-11-01

372

Être, essence et substance chez Platon et Aristote Être, essence et substance chez Platon et Aristote  

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Full Text Available Book Review of Paul Ricœur, Être, essence et substance chez Platon et Aristote. Cours professé à l’université de Strasbourg en 1953-1954. Texte vérifié et annoté par Jean-Louis Schlegel, (Paris: Éditions du Seuil, 2011, 348 pp.

Thomas De Koninck

2011-07-01

373

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)

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.

Campos Segura Ricardo

1995-12-01

374

Recommendations for the management of old uranium mining sites in France. From Limousin sites to other sites, from short- to medium- and long-terms. Final report of the pluralist expertise group on Limousin uranium mines (GEP). Synthesis and final report; Recommandations pour la gestion des anciens sites miniers d'uranium en France. Des sites du Limousin aux autres sites, du court aux moyen et long termes. Rapport final du Groupe d'expertise pluraliste sur les mines d'uranium du Limousin (GEP). Synthese et Rapport final  

Energy Technology Data Exchange (ETDEWEB)

The final report of the Pluralistic Experts Group for the Uranium mines of Limousin (GEP) brings together the main conclusions and recommendations arising from three and half years of work having mobilized, at the request and with the financial support of French authorities, more than forty experts from a varying range of disciplines and backgrounds. The mission given to GEP by the Ministers of Ecology, Industry and Health, as well as the President of the Nuclear safety Authority, was ambitious. It was not simply a matter of conducting an exhaustive and vigorous investigation of actual impacts, but also to analyse the present situation from a technical point of view starting with actual cases to clarify the options for management and monitoring, and to make recommendations on their development in order to reduce the current impacts and to foresee those in the long term according to the preparation of a long term plan. This final report attempts to develop a coherent framework of recommendations that are as operationally feasible as possible. Thus, the proposals of the GEP underline the need for an comprehensive approach, on the basis of work on the institutional perspectives, of a programme for improvement of knowledge and including a reinforcement of information and dialogue, to frame and guide the characterization of the risks and impacts, the evolution of the surveillance devices and the consolidation of the existing protection systems. These final proposals take account of a whole range of activities undertaken by Areva NC as well as the relevant local and national government organizations; and which integrate certain recommendations already produced by the GEP within the framework of its three interim reports. The GEP sets out six main areas of improvements, within which the GEP makes 15 major recommendations addressed to the public authorities, the owner and all of the stakeholders concerned. These recommendations, largely detailed in the report, aim to: - 1 - renovate and clarify the institutional and legal framework for the management of the former mining - 2 - promote efforts directed at the improvement of knowledge on the sites; to continue the studies and research and to broaden their scope; - 3 - reinforce the relevance of impact evaluations, in particular extending them to the ecosystems; to replace public exposure in the public health risks; - 4 - develop surveillance systems at the sites and the zones potentially located under their influence; - 5 - extend the effort of refitting in order to put in place, as of today, systems that are as robust as possible for the long term, where the risks justify it; - 6 - continue the implementation of the principles of information and participation to make them the drivers of a truly sustainable management system for the sites

NONE

2010-07-01

375

Vin et Mondialisation : préface  

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Full Text Available L’actualité cinématographique de ces derniers mois avec la sortie de Mondovino et Sideways illustre un certain nombre de tensions qui s’attachent à la mondialisation du produit “vin” et au soi-disant clivage entre le Nouveau Monde et la Vieille Europe, la marque et le terroir, la modernité et la tradition, autant de concepts masquant la complexité de ce processus. Le terme de ‘mondialisation’, d’usage fort répandu dans les médias, mérite sans doute quelques précautions. L’usage courant renvoi...

Chantal Crenn

2004-12-01

376

Entrepreneuriat Social et Participation Citoyenne  

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Full Text Available L'entrepreneuriat social est un concept émergeant, notamment dans les sciences de l'administration. Pourtant, en dehors d'une pratique directoriale spécifique, il est aussi une forme de participation citoyenne trop méconnue. L'objectif de cet article, basé sur une revue de la littérature et une approche théorique, est de présenter le concept d'entrepreneuriat social afin de mieux saisir son positionnement par rapport à la participation citoyenne. L'entrepreneuriat social constitue une forme particulière de participation à l'espace public par l'action, les entreprises sociales agissant au quotidien pour transformer le paysage social. En particulier, cet article souligne le contexte de développement de l'entrepreneuriat social, définit le concept et les notions connexes d'entreprise sociale et d'entrepreneur social, et, enfin, présente une réflexion sur la contribution de l'entrepreneuriat social à la participation citoyenne. L'article montre que l'entrepreneuriat social est une façon pour les citoyens d'agir directement et avec maîtrise sur la société. / Social entrepreneurship is an emerging concept, notably in administrative sciences. However, not only is it a specific managerial practice but it is also a type of citizen participation that is not well-known. The objective of this article, based on a literature review and a theoretical approach, is to present the concept of social entrepreneurship in order to better understand its relation to citizen participation. Social entrepreneurship represents a specific type of citizen participation involving actions. Social enterprises act daily to transform the social landscape. More specifically, this artic