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1

Rhizavidin from Rhizobium etli: the first natural dimer in the avidin protein family  

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Abstract Rhizobium etli CFN42 is a symbiotic, nitrogen-fixing bacterium of the common bean, Phaseolus vulgaris. The symbiotic plasmid p42d of R. etli comprises a gene encoding a putative (strept)avidin-like protein, named rhizavidin. The amino acid sequence identity of rhizavidin in relation to other known avidin-like proteins is 20-30%. The amino acid residues involved in (strept)avidin-biotin interaction are well conserved in rhizavidin. The structural and functional properties o...

Helppolainen, Satu H.; Nurminen, Kirsi P.; Ma?a?tta?, Juha Ae; Halling, Katrin K.; Slotte, J. Peter; Huhtala, Tuulia; Liimatainen, Timo; Yla?-herttuala, Seppo; Airenne, Kari J.; Na?rva?nen, Ale; Ja?nis, Janne; Vainiotalo, Pirjo; Valjakka, Jarkko; Kulomaa, Markku S.; Nordlund, Henri R.

2007-01-01

2

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

OpenAIRE

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

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

2013-01-01

3

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

4

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

5

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

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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 su...

Mendoza-Hernández Guillermo; Encarnación Sergio; Meneses Niurka

2010-01-01

6

Requirement of a Plasmid-Encoded Catalase for Survival of Rhizobium etli CFN42 in a Polyphenol-Rich Environment?  

OpenAIRE

Nitrogen-fixing bacteria collectively called rhizobia are adapted to live in polyphenol-rich environments. The mechanisms that allow these bacteria to overcome toxic concentrations of plant polyphenols have not been clearly elucidated. We used a crude extract of polyphenols released from the seed coat of the black bean to simulate a polyphenol-rich environment and analyze the response of the bean-nodulating strain Rhizobium etli CFN42. Our results showed that the viability of the wild type as...

Garci?a-de Los Santos, Alejandro; Lo?pez, Erika; Cubillas, Ciro A.; Noel, K. Dale; Brom, Susana; Romero, David

2008-01-01

7

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

8

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

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

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

2013-01-01

9

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

10

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

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

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

2014-05-01

12

The extent of migration of the Holliday junction is a crucial factor for gene conversion in Rhizobium etli.  

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Gene conversion, defined as the nonreciprocal transfer of DNA, is one result of homologous recombination. Three steps in recombination could give rise to gene conversion: (i) DNA synthesis for repair of the degraded segment, (ii) Holliday junction migration, leading to heteroduplex formation, and (iii) repair of mismatches in the heteroduplex. There are at least three proteins (RuvAB, RecG, and RadA) that participate in the second step. Their roles have been studied for homologous recombination, but evidence of their relative role in gene conversion is lacking. In this work, we showed the effect on gene conversion of mutations in ruvB, recG, and radA in Rhizobium etli, either alone or in combination, using a cointegration strategy previously developed in our laboratory. The results indicate that the RuvAB system is highly efficient for gene conversion, since its absence provokes smaller gene conversion segments than those in the wild type as well as a shift in the preferred position of conversion tracts. The RecG system possesses a dual role for gene conversion. Inactivation of recG leads to longer gene conversion tracts than those in the wild type, indicating that its activity may hinder heteroduplex extension. However, under circumstances where it is the only migration activity present (as in the ruvB radA double mutant), conversion segments can still be seen, indicating that RecG can also promote gene conversion. RadA is the least efficient system in R. etli but is still needed for the production of detectable gene conversion tracts. PMID:19502410

Castellanos, Mildred; Romero, David

2009-08-01

13

The Rhizobium etli RpoH1 and RpoH2 sigma factors are involved in different stress responses.  

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The physiological role and transcriptional expression of Rhizobium etli sigma factors rpoH1 and rpoH2 are reported in this work. Both rpoH1 and rpoH2 were able to complement the temperature-sensitive phenotype of an Escherichia coli rpoH mutant. The R. etli rpoH1 mutant was sensitive to heat shock, sodium hypochlorite and hydrogen peroxide, whereas the rpoH2 mutant was sensitive to NaCl and sucrose. The rpoH2 rpoH1 double mutant had increased sensitivity to heat shock and oxidative stress when compared with the rpoH1 single mutant. This suggests that in R. etli, RpoH1 is the main heat-shock sigma factor, but a more complete protective response could be achieved with the participation of RpoH2. Conversely, RpoH2 is involved in osmotic tolerance. In symbiosis with bean plants, the R. etli rpoH1 and rpoH2 rpoH1 mutants still elicited nodule formation, but exhibited reduced nitrogenase activity and bacterial viability in early and late symbiosis compared with nodules produced by rpoH2 mutants and wild-type strains. In addition, nodules formed by R. etli rpoH1 and rpoH2 rpoH1 mutants showed premature senescence. It was also determined that fixNf and fixKf expression was affected in rpoH1 mutants. Both rpoH genes were induced under microaerobic conditions and in the stationary growth phase, but not in response to heat shock. Analysis of the upstream region of rpoH1 revealed a sigma70 and a probable sigmaE promoter, whereas in rpoH2, one probable sigmaE-dependent promoter was detected. In conclusion, the two RpoH proteins operate under different stress conditions, RpoH1 in heat-shock and oxidative responses, and RpoH2 in osmotic tolerance. PMID:19202087

Martínez-Salazar, Jaime M; Sandoval-Calderón, Mario; Guo, Xianwu; Castillo-Ramírez, Santiago; Reyes, Alma; Loza, Maria G; Rivera, Javier; Alvarado-Affantranger, Xochitl; Sánchez, Federico; González, Víctor; Dávila, Guillermo; Ramírez-Romero, Miguel A

2009-02-01

14

Transfer of the Symbiotic Plasmid of Rhizobium etli CFN42 Requires Cointegration with p42a, Which May Be Mediated by Site-Specific Recombination  

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Plasmid p42a from Rhizobium etli CFN42 is self-transmissible and indispensable for conjugative transfer of the symbiotic plasmid (pSym). Most pSym transconjugants also inherit p42a. pSym transconjugants that lack p42a always contain recombinant pSyms, which we designated RpSyms*. RpSyms* do not contain some pSym segments and instead have p42a sequences, including the replication and transfer regions. These novel recombinant plasmids are compatible with wild-type pSym, incompatible with p42a, ...

Brom, Susana; Girard, Lourdes; Tun-garrido, Cristina; Garci?a-de Los Santos, Alejandro; Bustos, Patricia; Gonza?lez, Vi?ctor; Romero, David

2004-01-01

15

Conjugative Transfer of p42a from Rhizobium etli CFN42, Which Is Required for Mobilization of the Symbiotic Plasmid, Is Regulated by Quorum Sensing  

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Rhizobium etli CFN42 contains six plasmids. Only one of them, p42a, is self-conjugative at high frequency. This plasmid is strictly required for mobilization of the symbiotic plasmid (pSym). To study the transfer mechanism of p42a, a self-transmissible cosmid clone containing its transfer region was isolated. Its sequence showed that most of the tra genes are highly similar to genes of Agrobacterium tumefaciens pTiC58 and other related plasmids. Four putative regulatory genes were identified;...

Tun-garrido, Cristina; Bustos, Patricia; Gonza?lez, Vi?ctor; Brom, Susana

2003-01-01

16

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

17

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

OpenAIRE

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 ...

los Santos Alejandro; Romero David; Lozano Luis; Dávalos Araceli; Brom Susana; Villaseñor Tomás

2011-01-01

18

Influence of plant species on the biological control activity of the antagonistic rhizobacterium Rhizobium etli strain G12 toward the root-knot nematode, Meloidogyne incognita.  

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The influence of plant species on the antagonistic activity of the rhizosphere bacterium Rhizobium etli G12 towards the root-knot nematode Meloidogyne incognita was studied. The crops tested were tomato, cucumber, cotton, soybean and pepper. The plants were evaluated for the following parameters: root gall-index, total number of galls and egg masses of M. incognita, as well as shoot and root fresh weight and root length. Results indicated a clear influence of plant species on the ability of R. etli G12 to reduce nematode infection. Based on the root gall index, nematode control by R. etli G12 was higher on vegetables (tomato, cucumber, pepper) than on field crops (soybean, cotton). Reduction in galling ranged from 17% for cotton to 50% for tomato. R. etli G12 also reduced the actual number of galls produced. The reduction in the number of galls produced between crops was not affected significantly as was seen when a galling index was used to measure activity. The reduction in the number of galls was similar in level for all the crops studied and ranged from 34% for cucumber to 47% for tomato. There was a significant reduction in the number of egg masses produced by the females ranging from 37% for soybean to 70% for pepper. This indicated a direct effect on female development in the root after penetration or delayed penetration on certain crops. The bacteria caused significant increases in shoot fresh weight from 11% for soybean to 31% for pepper and in root fresh weight from 3% for soybean to 39% for tomato and in root length from 11% for cucumber to 24% for pepper. R. etli G12 gave significant control of M. incognita on a broad range of host plants, but the level of control varied. The suitability of each plant species, therefore, must be examined before R. etli G12 can be recommend for control of this nematode. PMID:12425090

Mahdy, M; Hallmann, J; Sikora, R A

2001-01-01

19

Characterization of IntA, a Bidirectional Site-Specific Recombinase Required for Conjugative Transfer of the Symbiotic Plasmid of Rhizobium etli CFN42  

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Site-specific recombination occurs at short specific sequences, mediated by the cognate recombinases. IntA is a recombinase from Rhizobium etli CFN42 and belongs to the tyrosine recombinase family. It allows cointegration of plasmid p42a and the symbiotic plasmid via site-specific recombination between attachment regions (attA and attD) located in each replicon. Cointegration is needed for conjugative transfer of the symbiotic plasmid. To characterize this system, two plasmids harboring the corresponding attachment sites and intA were constructed. Introduction of these plasmids into R. etli revealed IntA-dependent recombination events occurring at high frequency. Interestingly, IntA promotes not only integration, but also excision events, albeit at a lower frequency. Thus, R. etli IntA appears to be a bidirectional recombinase. IntA was purified and used to set up electrophoretic mobility shift assays with linear fragments containing attA and attD. IntA-dependent retarded complexes were observed only with fragments containing either attA or attD. Specific retarded complexes, as well as normal in vivo recombination abilities, were seen even in derivatives harboring only a minimal attachment region (comprising the 5-bp central region flanked by 9- to 11-bp inverted repeats). DNase I-footprinting assays with IntA revealed specific protection of these zones. Mutations that disrupt the integrity of the 9- to 11-bp inverted repeats abolish both specific binding and recombination ability, while mutations in the 5-bp central region severely reduce both binding and recombination. These results show that IntA is a bidirectional recombinase that binds to att regions without requiring neighboring sequences as enhancers of recombination. PMID:23935046

Hernández-Tamayo, Rogelio; Sohlenkamp, Christian; Puente, José Luis; Brom, Susana

2013-01-01

20

Characterization of IntA, a bidirectional site-specific recombinase required for conjugative transfer of the symbiotic plasmid of Rhizobium etli CFN42.  

Science.gov (United States)

Site-specific recombination occurs at short specific sequences, mediated by the cognate recombinases. IntA is a recombinase from Rhizobium etli CFN42 and belongs to the tyrosine recombinase family. It allows cointegration of plasmid p42a and the symbiotic plasmid via site-specific recombination between attachment regions (attA and attD) located in each replicon. Cointegration is needed for conjugative transfer of the symbiotic plasmid. To characterize this system, two plasmids harboring the corresponding attachment sites and intA were constructed. Introduction of these plasmids into R. etli revealed IntA-dependent recombination events occurring at high frequency. Interestingly, IntA promotes not only integration, but also excision events, albeit at a lower frequency. Thus, R. etli IntA appears to be a bidirectional recombinase. IntA was purified and used to set up electrophoretic mobility shift assays with linear fragments containing attA and attD. IntA-dependent retarded complexes were observed only with fragments containing either attA or attD. Specific retarded complexes, as well as normal in vivo recombination abilities, were seen even in derivatives harboring only a minimal attachment region (comprising the 5-bp central region flanked by 9- to 11-bp inverted repeats). DNase I-footprinting assays with IntA revealed specific protection of these zones. Mutations that disrupt the integrity of the 9- to 11-bp inverted repeats abolish both specific binding and recombination ability, while mutations in the 5-bp central region severely reduce both binding and recombination. These results show that IntA is a bidirectional recombinase that binds to att regions without requiring neighboring sequences as enhancers of recombination. PMID:23935046

Hernández-Tamayo, Rogelio; Sohlenkamp, Christian; Puente, José Luis; Brom, Susana; Romero, David

2013-10-01

21

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

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

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

1999-05-01

22

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

23

Transfer of the symbiotic plasmid of Rhizobium etli CFN42 requires cointegration with p42a, which may be mediated by site-specific recombination.  

Science.gov (United States)

Plasmid p42a from Rhizobium etli CFN42 is self-transmissible and indispensable for conjugative transfer of the symbiotic plasmid (pSym). Most pSym transconjugants also inherit p42a. pSym transconjugants that lack p42a always contain recombinant pSyms, which we designated RpSyms*. RpSyms* do not contain some pSym segments and instead have p42a sequences, including the replication and transfer regions. These novel recombinant plasmids are compatible with wild-type pSym, incompatible with p42a, and self-transmissible. The symbiotic features of derivatives simultaneously containing a wild-type pSym and an RpSym* were analyzed. Structural analysis of 10 RpSyms* showed that 7 shared one of the two pSym-p42a junctions. Sequencing of this common junction revealed a 53-bp region that was 90% identical in pSym and p42a, including a 5-bp central region flanked by 9- to 11-bp inverted repeats reminiscent of bacterial and phage attachment sites. A gene encoding an integrase-like protein (intA) was localized downstream of the attachment site on p42a. Mutation or the absence of intA abolished pSym transfer from a recA mutant donor. Complementation with the wild-type intA gene restored transfer of pSym. We propose that pSym-p42a cointegration is required for pSym transfer; cointegration may be achieved either through homologous recombination among large reiterated sequences or through IntA-mediated site-specific recombination between the attachment sites. Cointegrates formed through the site-specific system but resolved through RecA-dependent recombination or vice versa generate RpSyms*. A site-specific recombination system for plasmid cointegration is a novel feature of these large plasmids and implies that there is unique regulation which affects the distribution of pSym in nature due to the role of the cointegrate in conjugative transfer. PMID:15516565

Brom, Susana; Girard, Lourdes; Tun-Garrido, Cristina; García-de los Santos, Alejandro; Bustos, Patricia; González, Víctor; Romero, David

2004-11-01

24

Phosphate solubilization by Rhizobium strains  

OpenAIRE

Forty-six Rhizobium isolates from legume root and stem nodules were examined for their phosphate-solubilizing ability on Pikovskaya’s agar medium. Rhizobium isolates from root nodules of Cassia absus, Vigna trilobata and three strains from Sesbania sesban showed zone of tricalcium phosphate (TCP) solubilization. The isolate from C. absus showed maximum solubilization (620 ?g/ml) after 12 d of incubation, while the Rhizobium sp. strain 26 (from S. sesban) showed the least amount (150 ?g/ml...

Sridevi, M.; Mallaiah, K. V.

2009-01-01

25

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

26

Phosphate solubilization by Rhizobium strains.  

Science.gov (United States)

Forty-six Rhizobium isolates from legume root and stem nodules were examined for their phosphate-solubilizing ability on Pikovskaya's agar medium. Rhizobium isolates from root nodules of Cassia absus, Vigna trilobata and three strains from Sesbania sesban showed zone of tricalcium phosphate (TCP) solubilization. The isolate from C. absus showed maximum solubilization (620 ?g/ml) after 12 d of incubation, while the Rhizobium sp. strain 26 (from S. sesban) showed the least amount (150 ?g/ml) of phosphate solubilization. Among the carbon sources tested for their ability to solubilize TCP, maximum solubilization (620 ?g/ml) was observed in glucose by Rhizobium isolate from C. absus. Phosphate solubilization increased with increase in glucose concentration steeply up to 2% and slowly above this concentration in four isolates. Among the nitrogen sources tested, maximum solubilization (620 ?g/ml) was observed in ammonium sulphate by Rhizobium isolate from C. absus. PMID:23100757

Sridevi, M; Mallaiah, K V

2009-03-01

27

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

28

Change in land use alters the diversity and composition of Bradyrhizobium communities and led to the introduction of Rhizobium etli into the tropical rain forest of Los Tuxtlas (Mexico).  

Science.gov (United States)

Nitrogen-fixing bacteria of the Bradyrhizobium genus are major symbionts of legume plants in American tropical forests, but little is known about the effects of deforestation and change in land use on their diversity and community structure. Forest clearing is followed by cropping of bean (Phaseolus vulgaris) and maize as intercropped plants in Los Tuxtlas tropical forest of Mexico. The identity of bean-nodulating rhizobia in this area is not known. Using promiscuous trap plants, bradyrhizobia were isolated from soil samples collected in Los Tuxtlas undisturbed forest, and in areas where forest was cleared and land was used as crop fields or as pastures, or where secondary forests were established. Rhizobia were also trapped by using bean plants. Bradyrhizobium strains were classified into genospecies by dnaK sequence analysis supported by recA, glnII and 16S-23S rDNA IGS loci analyses. A total of 29 genospecies were identified, 24 of which did not correspond to any described taxa. A reduction in Bradyrhizobium diversity was observed when forest was turned to crop fields or pastures. Diversity seemed to recover to primary forest levels in secondary forests that derived from abandoned crop fields or pastures. The shifts in diversity were not related to soil characteristics but seemingly to the density of nodulating legumes present at each land use system (LUS). Bradyrhizobium community composition in soils was dependent on land use; however, similarities were observed between crop fields and pastures but not among forest and secondary forest. Most Bradyrhizobium genospecies present in forest were not recovered or become rare in the other LUS. Rhizobium etli was found as the dominant bean-nodulating rhizobia present in crop fields and pastures, and evidence was found that this species was introduced in Los Tuxtlas forest. PMID:22109095

Ormeño-Orrillo, Ernesto; Rogel-Hernández, Marco A; Lloret, Lourdes; López-López, Aline; Martínez, Julio; Barois, Isabelle; Martínez-Romero, Esperanza

2012-05-01

29

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

Science.gov (United States)

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

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

2000-03-01

30

Polyol metabolism by Rhizobium trifolii.  

OpenAIRE

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

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

1980-01-01

31

Thiamine Is Synthesized by a Salvage Pathway in Rhizobium leguminosarum bv. viciae Strain 3841  

OpenAIRE

In the absence of added thiamine, Rhizobium leguminosarum bv. viciae strain 3841 does not grow in liquid medium and forms only “pin” colonies on agar plates, which contrasts with the good growth of Sinorhizobium meliloti 1021, Mesorhizobium loti 303099, and Rhizobium etli CFN42. These last three organisms have thiCOGE genes, which are essential for de novo thiamine synthesis. While R. leguminosarum bv. viciae 3841 lacks thiCOGE, it does have thiMED. Mutation of thiM prevented formation of...

Karunakaran, R.; Ebert, K.; Harvey, S.; Leonard, M. E.; Ramachandran, V.; Poole, P. S.

2006-01-01

32

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

33

Congo Red Absorption by Rhizobium leguminosarum  

OpenAIRE

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

34

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

35

Immunosuppression during Rhizobium-legume symbiosis.  

Science.gov (United States)

Rhizobium infects host legumes to elicit new plant organs, nodules where dinitrogen is fixed as ammonia that can be directly utilized by plants. The nodulation factor (NF) produced by Rhizobium is one of the determinant signals for rhizobial infection and nodule development. Recently, it was found to suppress the innate immunity on host and nonhost plants as well as its analogs, chitins. Therefore, NF can be recognized as a microbe/pathogen-associated molecular pattern (M/PAMP) like chitin to induce the M/PAMP triggered susceptibility (M/PTS) of host plants to rhizobia. Whether the NF signaling pathway is directly associated with the innate immunity is not clear till now. In fact, other MAMPs such as lipopolysaccharide (LPS), exopolysaccharide (EPS) and cyclic-?-glucan, together with type III secretion system (T3SS) effectors are also required for rhizobial infection or survival in leguminous nodule cells. Interestingly, most of them play similarly negative roles in the innate immunity of host plants, though their signaling is not completely elucidated. Taken together, we believe that the local immunosuppression on host plants induced by Rhizobium is essential for the establishment of their symbiosis. PMID:24556951

Luo, Li; Lu, Dawei

2014-01-01

36

Conservation between coding and regulatory elements of Rhizobium meliloti and Rhizobium leguminosarum dct genes.  

OpenAIRE

Complementation of Rhizobium leguminosarum dct mutants with a cosmid bank yielded Rhizobium meliloti homologs of the dctA, dctB, and dctD genes. The genes dctB and dctD are thought to form a two-component system which responds to the presence of C4-dicarboxylates to regulate expression of a transport protein encoded by dctA. DNA sequence analysis showed that dct coding and intergenic regions, including putative binding sites for the dctD protein and sigma 54-RNA polymerase, were highly conser...

Jiang, J.; Gu, B. H.; Albright, L. M.; Nixon, B. T.

1989-01-01

37

Rhizobium tibeticum sp. nov., a symbiotic bacterium isolated from Trigonella archiducis-nicolai (Sirj.) Vassilcz.  

Science.gov (United States)

Isolated from root nodules of Trigonella archiducis-nicolai (Sirj.) Vassilcz. grown in Tibet, China, cells of the bacterial strains CCBAU 85039(T) and CCBAU 85027 were Gram-negative, aerobic, motile, non-spore-forming rods that formed colonies that were semi-translucent and opalescent on yeast extract-mannitol agar. In numerical taxonomy, SDS-PAGE analysis of whole-cell proteins and DNA-DNA hybridization, the two strains were very similar and were different from reference strains of defined Rhizobium species. In the phylogeny based on 16S rRNA gene sequences, they were most similar to Rhizobium etli CFN 42(T) (98.2 % similarity) and R. leguminosarum USDA 2370(T) (97.6 %). Sequence analyses of the housekeeping genes recA, atpD and glnII and the 16S-23S rRNA intergenic spacer, phenotypic characteristics and cellular fatty acid profiles strongly suggested that these two strains represented a novel species within Rhizobium. Cross-nodulation tests and sequencing of nifH and nodA genes showed that these two strains were symbiotic bacteria that nodulated Trigonella archiducis-nicolai, Medicago lupulina, Medicago sativa, Melilotus officinalis, Phaseolus vulgaris and Trigonella foenum-graecum. Based on the results, the novel species Rhizobium tibeticum sp. nov. is described to accommodate the two strains. The type strain is CCBAU 85039(T) (=LMG 24453(T) =CGMCC 1.7071(T)). The DNA G+C content of this strain is 59.7 mol% (T(m)). PMID:19643889

Hou, Bao Chao; Wang, En Tao; Li, Ying; Jia, Rui Zong; Chen, Wen Feng; Gao, Yu; Dong, Ren Jie; Chen, Wen Xin

2009-12-01

38

Nodulation of Acacia Species by Fast- and Slow-Growing Tropical Strains of Rhizobium  

OpenAIRE

Thirteen Acacia species were classified into three groups according to effective nodulation response patterns with fast- and slow-growing tropical strains of Rhizobium. The first group nodulated effectively with slow-growing, cowpea-type Rhizobium strains; the second, with fast-growing Rhizobium strains; and the third, with both fast- and slow-growing Rhizobium strains. The Rhizobium requirements of the Acacia species of the second group were similar to those of Leucaena leucocephala.

Dreyfus, B. L.; Dommergues, Y. R.

1981-01-01

39

Rhizobium calliandrae sp. nov., Rhizobium mayense sp. nov. and Rhizobium jaguaris sp. nov., rhizobial species nodulating the medicinal legume Calliandra grandiflora.  

Science.gov (United States)

Calliandra grandiflora has been used as a medicinal plant for thousands of years in Mexico. Rhizobial strains were obtained from root nodules of C. grandiflora collected from different geographical regions in Chiapas and characterized by BOX-PCR, amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis. Most isolates corresponded to members of the genus Rhizobium and those not related to species with validly published names were further characterized by recA, atpD, rpoB and nifH gene phylogenies, phenotypic and DNA-DNA hybridization analyses. Three novel related species of the genus Rhizobium within the 'Rhizobium tropici group' share the same symbiovar that may be named sv. calliandrae. The names proposed for the three novel species are Rhizobium calliandrae sp. nov. (type strain, CCGE524(T)?=ATCC BAA-2435(T)?=CIP 110456(T)?=LBP2-1(T)), Rhizobium mayense sp. nov. (type strain, CCGE526(T)?=ATCC BAA-2446(T)?=?CIP 110454(T)?=NSJP1-1(T)) and Rhizobium jaguaris sp. nov. (type strain, CCGE525(T)?=ATCC BAA-2445(T)?=CIP 110453(T)?=SJP1-2(T)). PMID:23584283

Rincón-Rosales, Reiner; Villalobos-Escobedo, José M; Rogel, Marco A; Martinez, Julio; Ormeño-Orrillo, Ernesto; Martínez-Romero, Esperanza

2013-09-01

40

Regulation of Syrm and Nodd3 in Rhizobium Meliloti  

OpenAIRE

The early steps of symbiotic nodule formation by Rhizobium on plants require coordinate expression of several nod gene operons, which is accomplished by the activating protein NodD. Three different NodD proteins are encoded by Sym plasmid genes in Rhizobium meliloti, the alfalfa symbiont. NodD1 and NodD2 activate nod operons when Rhizobium is exposed to host plant inducers. The third, NodD3, is an inducer-independent activator of nod operons. We previously observed that nodD3 carried on a mul...

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

1993-01-01

41

Rhizobium sullae sp. nov. (formerly 'Rhizobium hedysari'), the root-nodule microsymbiont of Hedysarum coronarium L.  

Science.gov (United States)

This work is the completion of a series of reports describing the nitrogen-fixing bacterial symbionts of sulla (Hedysarum coronarium L., Leguminosae) and providing the grounds for their proposal as a new taxon. The introduction summarizes a large amount of previous evidence gathered on the physiology, genetics and ecology of such organisms, which have in the past been referred to provisionally as 'Rhizobium hedysari'. Upon adding 16S RNA sequencing, amplified rDNA restriction analysis of the rrn operon, DNA-DNA hybridization homology and analysis of low-molecular-mass RNA species, it is concluded that the group of strains that specifically nodulate sulla consists of a coherent set of isolates that differ from previously described rhizobia to an extent that warrants the constitution of the species boundary. The name Rhizobium sullae sp. nov. is proposed, with isolate 1S123T (=USDA 4950T = DSM 14623T) as the type strain. PMID:12148639

Squartini, Andrea; Struffi, Paolo; Döring, Heidi; Selenska-Pobell, Sonja; Tola, Elisabetta; Giacomini, Alessio; Vendramin, Elena; Velázquez, Encarna; Mateos, Pedro F; Martínez-Molina, Eustoquio; Dazzo, Frank B; Casella, Sergio; Nuti, Marco P

2002-07-01

42

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

Directory of Open Access Journals (Sweden)

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

Stéphane Legrand

2004-04-01

43

Variability among Rhizobium Strains Originating from Nodules of Vicia faba  

OpenAIRE

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 agains...

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

1995-01-01

44

A Rhizobium leguminosarum mutant defective in symbiotic iron acquisition.  

OpenAIRE

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: the accumulation of porphyrins (precursors of hemes) so that colonies emitted a characteristic pinkish-re...

Nadler, K. D.; Johnston, A. W.; Chen, J. W.; John, T. R.

1990-01-01

45

Bacterial and plant glycoconjugates at the Rhizobium-legume interface  

OpenAIRE

Many classes of bacterial and plant glycoconjugate have been shown to be involved in establishing the Rhizobium root nodule symbiosis with peas (Pisum sativum). It was demonstrated, using techniques of molecular genetics, that a group of Rhizobium nodulation genes (nod genes) co-operate to synthesize a lipo-oligosaccharide signal molecule that specifically initiates nodule development on legume hosts. An additional gene function, encoded by nodX, has been found to extend the host range of Rhi...

Brewin, N. J.; Rae, A. L.; Perotto, S.; Kannenberg, E. L.; Rathbun, E. A.; Lucas, M. Mercedes; Gunder, A.; Bolan?os, L.; Kardailsky, I. V.; Wilson, K. E.; Firmin, J. L.; Downie, J. A.

1994-01-01

46

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

Directory of Open Access Journals (Sweden)

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

Abdul Khalil Gardezi

2006-01-01

47

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

Directory of Open Access Journals (Sweden)

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

48

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

Science.gov (United States)

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

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

2013-06-01

49

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

OpenAIRE

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

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

2008-01-01

50

Gene transfer into Solanum tuberosum via Rhizobium spp.  

Science.gov (United States)

Agrobacterium tumefaciens-mediated transformation (ATMT) is the preferred technique for gene transfer into crops. A major disadvantage of the technology remains the complexity of the patent landscape that surrounds ATMT which restricts its use for commercial applications. An alternative system has been described (Broothaerts et al. in Nature 433:629-633, 2005) detailing the propensity of three rhizobia to transform the model crop Arabidopsis thaliana, the non-food crop Nicotiana tabacum and, at a very low frequency, the monocotyledonous crop Oryza sativa. In this report we describe for the first time the genetic transformation of Solanum tuberosum using the non-Agrobacterium species Sinorhizobium meliloti, Rhizobium sp. NGR234 and Mesorhizobium loti. This was achieved by combining an optimal bacterium and host co-cultivation period with a low antibiotic regime during the callus and shoot induction stages. Using this optimized protocol the transformation frequency (calculated as % of shoots equipped with root systems with the ability to grow in rooting media supplemented with 25 ?g/ml hygromycin) of the rhizobia strains was calculated at 4.72, 5.85 and 1.86% for S. meliloti, R. sp. NGR234 and M. loti respectively, compared to 47.6% for the A. tumefaciens control. Stable transgene integration and expression was confirmed via southern hybridisation, quantitative PCR analysis and histochemical screening of both leaf and/or tuber tissue. In light of the rapid advances in potato genomics, combined with the sequencing of the potato genome, the ability of alternative bacteria species to genetically transform this major food crop will provide a novel resource to the Solanaceae community as it continues to develop potato as both a food and non-food crop. PMID:20582626

Wendt, Toni; Doohan, Fiona; Winckelmann, Dominik; Mullins, Ewen

2011-04-01

51

Negotiation, sanctions, and context dependency in the legume-Rhizobium mutualism.  

Science.gov (United States)

Two important questions about mutualisms are how the fitness costs and benefits to the mutualist partners are determined and how these mechanisms affect the evolutionary dynamics of the mutualism. We tackle these questions with a model of the legume-rhizobium symbiosis that regards the mutualism outcome as a result of biochemical negotiations between the plant and its nodules. We explore the fitness consequences of this mechanism to the plant and rhizobia and obtain four main results. First, negotiations permit the plant to differentially reward more-cooperative rhizobia--a phenomenon termed "plant sanctions"--but only when more-cooperative rhizobia also provide the plant with good outside options during negotiations with other nodules. Second, negotiations may result in seemingly paradoxical cases where the plant is worse off when it has a "choice" between two strains of rhizobia than when infected by either strain alone. Third, even when sanctions are effective, they are by themselves not sufficient to maintain cooperative rhizobia in a population: less cooperative strains always have an advantage at the population level. Finally, partner fidelity feedback, together with genetic correlations between a rhizobium strain's cooperativeness and the outside options it provides, can maintain cooperative rhizobia. Our results show how joint control over the outcome of a mutualism through the proximate mechanism of negotiation can affect the evolutionary dynamics of interspecific cooperation. PMID:21670573

Akçay, Erol; Simms, Ellen L

2011-07-01

52

Conservation of nodulation genes between Rhizobium meliloti and a slow-growing Rhizobium strain that nodulates a nonlegume host  

OpenAIRE

Parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with a Rhizobium species. The bacterial strain RP501 is a slow-growing strain of Rhizobium isolated from Parasponia nodules. Strain RP501 also nodulates the legumes siratro (Macroptilium atropurpureum) and cowpea (Vigna unguiculata). Using a cosmid clone bank of RP501 DNA, we isolated a 13.4-kilobase (kb) EcoRI fragment that complemented insertion an...

Marvel, Deborah J.; Kuldau, Gretchen; Hirsch, Ann; Richards, Eric; Torrey, John G.; Ausubel, Frederick M.

1985-01-01

53

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

OpenAIRE

Problem statement: Rhizobial isolates belonging to genera (Rhizobium sp. and Mesorhizobium sp.) in our laboratory produced only catecholate type of siderophores. Although FhuA and FegA (ferrichrome receptors) homologs were found to be present in the sequenced genomes of few rhizobia (e.g., 1 in R. etli and 2 in Mesorhizobium sp. BNC1), laboratory isolates of the corresponding genera failed to utilize ferrichrome, a siderophore which is pres...

Archana, G.; Desai, Dhwani K.; Joshi, Falguni R.; Desai, Anjana J.

2009-01-01

54

75 FR 5120 - United States, et al. v. Stericycle, Inc., et al.; Proposed Final Judgment and Competitive Impact...  

Science.gov (United States)

...adjudication of any issue of fact or law; and without this Final Judgment...party regarding any issue of law or fact; And Whereas, defendants...adjudication of any issue of fact or law, and upon consent of the parties...facilities: a. MedServe's Newton, Kansas autoclave...

2010-02-01

55

Gluconate Catabolism in Rhizobium japonicum1  

Science.gov (United States)

Gluconate catabolism in Rhizobium japonicum ATCC 10324 was investigated by the radiorespirometric method and by assaying for key enzymes of the major energy-yielding pathways. Specifically labeled gluconate gave the following results for growing cells, with values expressed as per cent 14CO2 evolution: C-1 = 93%, C-2 = 57%, C-3 = 30%, C-4 = 70%, C-6 = 39%. The preferential release of 14CO2 from C-1 and C-4 indicate that gluconate is degraded primarily by the Entner-Doudoroff pathway but the inequalities between C-1 and C-4 and between C-3 and C-6 indicate that another pathway(s) also participates. The presence of gluconokinase and a system for converting 6-phosphogluconate to pyruvate also indicate a role for the Entner-Doudoroff pathway. The extraordinarily high yield of 14CO2 from C-1 labeled gluconate suggests that the other participating pathway is a C-1 decarboxylative pathway. The key enzyme of the pentose phosphate pathway, 6-phosphogluconate dehydrogenase, could not be demonstrated. Specifically labeled 2-ketogluconate and 2,5-diketogluconate were oxidized by gluconate grown cells and gave ratios of C-1 to C-6 of 2.73 and 2.61, respectively. These compare with a ratio of 2.39 obtained with specifically labeled gluconate. Gluconate dehydrogenase, the first enzyme in the ketogluconate pathway found in acetic acid bacteria, was found. Oxidation of specifically labeled pyruvate, acetate, succinate, and glutamate by gluconate-grown cells yielded the preferential rates of 14CO2 evolution expected from the operation of the tricarboxylic acid cycle. These data are consistent with the operation of the Entner-Doudoroff pathway and tricarboxylic acid cycle as the primary pathways of gluconate oxidation in R. japonicum. An ancillary pathway for the initial breakdown of gluconate would appear to be the ketogluconate pathway which enters the tricarboxylic acid cycle at ?-ketoglutarate. PMID:5438044

Keele, Bernard B.; Hamilton, Pat B.; Elkan, Gerald H.

1970-01-01

56

Infection and nodulation of clover by nonmotile Rhizobium trifolii.  

OpenAIRE

Nonmotile mutants of Rhizobium trifolii were isolated to determine whether bacterial motility is required for the infection and nodulation of clover. The nonmotile mutants were screened for their ability to infect and nodulate clover seedlings in Fahraeus glass slide assemblies, plastic growth pouches, and vermiculite-sand-filled clay pots. In each system, the nonmotile mutants were able to infect and nodulate clover.

Napoli, C.; Albersheim, P.

1980-01-01

57

Rhizobium alvei sp. nov., isolated from a freshwater river.  

Science.gov (United States)

A bacterial strain designated TNR-22T was isolated from freshwater river in Taiwan and characterized using the polyphasic taxonomy approach. Cells of strain TNR-22T were faculative anaerobic, Gram-stain-negative, rod-shaped, motile by a single polar flagellum and forming cream colored colonies. Growth occurred at 4-45 °C (optimum, 25-30 °C), with 0-1.0 % NaCl (optimum, 0.5 %) and at pH 7.0-8.0 (optimum, pH 7.0). Strain TNR-22T did not form nodules on a legume plant, Macroptilium atropurpureum. The nifH gene encoding denitrogenase reductase was not detected by PCR. The major fatty acids (?10 %) of strain TNR-22T were C18:1 ?7c and C16:0. The DNA G+C content was 60.3 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, diphosphatidylglycerol, an uncharacterized aminoglycolipid and an uncharacterized phospholipid. Comparative analysis of the 16S rRNA gene sequences showed that strain TNR-22T constituted a distinct branch within the genus Rhizobium, showing the highest level of sequence similarity with respect to Rhizobium rosettiformans W3T (96.3 %). Phenotypic characteristics of the novel strain also differed from those of the closest related species of the genus Rhizobium. On the basis of the genotypic, chemotaxonomic and phenotypic data, strain TNR-22T represents a novel species in the genus Rhizobium, for which the name Rhizobium alvei sp. nov. is proposed. The type strain is TNR-22T (=BCRC 80408T =LMG 26895T =KCTC 23919T). PMID:25385988

Sheu, Shih-Yi; Huang, Hsing-Wei; Young, Chiu-Chung; Chen, Wen-Ming

2014-11-10

58

Rhizobium Promotes Non-Legumes Growth and Quality in Several Production Steps: Towards a Biofertilization of Edible Raw Vegetables Healthy for Humans  

OpenAIRE

The biofertilization of crops with plant-growth-promoting microorganisms is currently considered as a healthy alternative to chemical fertilization. However, only microorganisms safe for humans can be used as biofertilizers, particularly in vegetables that are raw consumed, in order to avoid sanitary problems derived from the presence of pathogenic bacteria in the final products. In the present work we showed that Rhizobium strains colonize the roots of tomato and pepper plants promoting thei...

Garci?a-fraile, Paula; Carro, Lorena; Robledo, Marta; Rami?rez-bahena, M. H.; Flores-fe?lix, Jose?-david; Ferna?ndez, Mari?a Teresa; Mateos, P. F.; Rivas, R.; Igual, Jose? Mariano; Marti?nez-molina, E.; Peix, A.; Vela?zquez, E.

2012-01-01

59

Interaction of Azospirillum and Rhizobium Strains Leading to Inhibition of Nodulation  

OpenAIRE

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

Plazinski, Jacek; Rolfe, Barry G.

1985-01-01

60

The conjugative plasmid of a bean-nodulating Sinorhizobium fredii strain is assembled from sequences of two Rhizobium plasmids and the chromosome of a Sinorhizobium strain  

OpenAIRE

Abstract Background Bean-nodulating Rhizobium etli originated in Mesoamerica, while soybean-nodulating Sinorhizobium fredii evolved in East Asia. S. fredii strains, such as GR64, have been isolated from bean nodules in Spain, suggesting the occurrence of conjugative transfer events between introduced and native strains. In R. etli CFN42, transfer of the symbiotic plasmid (pRet42d) requires cointegration with the endogenous self-transmissibl...

Brom Susana; Romero David; Vinuesa Pablo; Dávila Guillermo; Santamaría Rosa; Girard Lourdes; Bustos Patricia; Cervantes Laura

2011-01-01

61

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

62

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

Science.gov (United States)

Bacterial strain L6-16(T) was isolated from Lemna aequinoctialis. Cells were Gram-stain-negative, rod-shaped and motile with monopolar flagella. The phylogenetic analysis of its nearly complete 16S rRNA gene sequence revealed that strain L6-16(T) was a member of the genus Rhizobium. Its closest relative was Rhizobium tarimense PL-41(T) with a 16S rRNA gene sequence similarity value of 98.3%. Sequence similarity analysis of the housekeeping recA and atpD genes showed low levels of sequence similarity (lemnae sp. nov. is proposed. The type strain is L6-16(T) (?= NBRC 109339(T)?= BCC 55143(T)). PMID:24786354

Kittiwongwattana, Chokchai; Thawai, Chitti

2014-07-01

63

Growth of Rhizobium japonicum Strains at Temperatures Above 27°C †  

OpenAIRE

A study was conducted to examine the growth responses of different Rhizobium japonicum strains to increasing temperatures, determine the degree of variability among strains in those responses, and identify temperature-related growth characteristics that could be used to select temperature-tolerant strains. Each of 42 strains was grown in liquid culture for 96 h at 19 incubation temperatures ranging from 27.4 to 54.1°C in a temperature gradient apparatus. Growth was estimated by measuring the...

Mune?var, Fernando; Wollum, Arthur G.

1981-01-01

64

An apparently useless conserved gene in Rhizobium sullae  

OpenAIRE

Rhizobium sullae, a nitrogen fixing symbiotic bacterium, induces nodules formation on Hedysarum coronarium L. Although the ability to denitrify may enhance bacterial survival and growth capability in anaerobic soils, denitrification among rhizobia is rare, and only B. japonicum and A. caulinodans have been shown to be true denitrifiers, reducing nitrate (NO3-) simultaneously to both NH4+(assimilation) and N2 (denitrification), when cultured microaerobically with nitrate as the only nitrog...

Bottegal, Mariangela

2009-01-01

65

Evaluation of Nitrate Reductase Activity in Rhizobium japonicum†  

OpenAIRE

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

Streeter, John G.; Devine, Paul J.

1983-01-01

66

A Positive Strain Identification Method for Rhizobium meliloti†  

OpenAIRE

About 80% of Rhizobium meliloti strains contain 1 to 11 copies of insertion sequence ISRm1 in their genomes (R. Wheatcroft and R. J. Watson, J. Gen. Microbiol. 134:113-121, 1988). Hybridization to separated genomic DNA fragments with an ISRm1-specific probe produces patterns of hybridization bands which are distinctive for each strain. These patterns can be compared between strains to prove or disprove common identity. In most cases relatedness can be inferred despite phenotypic differences o...

Wheatcroft, Roger; Watson, Robert J.

1988-01-01

67

Pengaruh Inokulasi Rhizobium Terhadap Produksi Legum Stylo (Stylosanthes guyanensis)  

OpenAIRE

Penelitian ini dilaksanakan dirumah kaca di Fakultas Pertanian Universitas Sumatera Utara pada bulan Juli sampai September 1999. Adapun tujuan dari penelitian ini adalah untuk mengetahui pengaruh perlakuan inokulasi rhizobium terhadap pertumbuhan dan produksi hijauan legum stylo. Pelaksanaan penelitian ini menggunakan Rancangan Acak Lengkap (RAL) non faktorial. Terdiri dari 3 pedakuan dengan 6 ulangan yang ma~ing-masing perlakuan sebagai berikut : PI = Media tanam tanpa r...

Junaidi

2012-01-01

68

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

Science.gov (United States)

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

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

2013-01-01

69

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

Science.gov (United States)

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

70

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

Science.gov (United States)

In contrast to Klebsiella pneumoniae or fast-growing Rhizobium species, such as R. meliloti, where the nitrogenase structural genes are clustered in one operon (nifHDK), in slow-growing Rhizobium japonicum 110, nifH and nifDK are on separate operons. Images PMID:6307985

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

1983-01-01

71

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

OpenAIRE

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

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

1983-01-01

72

Nodules are induced on alfalfa roots by Agrobacterium tumefaciens and Rhizobium trifolii containing small segments of the Rhizobium meliloti nodulation region.  

OpenAIRE

Regions of the Rhizobium meliloti nodulation genes from the symbiotic plasmid were transferred to Agrobacterium tumefaciens and Rhizobium trifolii by conjugation. The A. tumefaciens and R. trifolii transconjugants were unable to elicit curling of alfalfa root hairs, but were able to induce nodule development at a low frequency. These were judged to be genuine nodules on the basis of cytological and developmental criteria. Like genuine alfalfa nodules, the nodules were initiated from divisions...

Hirsch, A. M.; Drake, D.; Jacobs, T. W.; Long, S. R.

1985-01-01

73

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

OpenAIRE

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 n...

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

1985-01-01

74

Mechanism of regulation of glucose transport in Rhizobium leguminosarum.  

OpenAIRE

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

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

1982-01-01

75

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

Science.gov (United States)

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

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

2015-01-01

76

Role of Rhizobium Inoculation in Chickpea (Cicer arietinum L. Under Water Stress Conditions  

Directory of Open Access Journals (Sweden)

Full Text Available Two chickpea varieties viz., 90122 and 93081 were subjected to Rhizobium inoculation with BioPower under water stress conditions, imposed by withholding water. Stress reduced all the parameters including yield components and this effect was more pronounced by stress at reproductive stage as compared with vegetative stage. Rhizobium inoculation enhanced yield under both normal and stressed conditions, but its performance was better under normal than under stress. Rhizobium inoculation proved ineffective to recover loss caused by water stress. The two varieties exhibited statistically non-significant differences.

Rahat Parveen

1999-01-01

77

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

78

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

79

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

OpenAIRE

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

80

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

81

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

82

An Experimental Test of the Rhizopine Concept in Rhizobium meliloti.  

Science.gov (United States)

In some Rhizobium-legume symbioses, compounds known as rhizopines are synthesized by bacteroids and subsequently catabolized by free-living cells of the producing strain. It has been suggested than rhizopines act as proprietary growth substrates and enhance the competitive ability of the producing strain in its interactions with the diverse microbial community found within the rhizosphere. Wild-type, rhizopine-producing Rhizobium meliloti L5-30 and mutant L5-30 strains deficient for either rhizopine synthesis or catabolism were inoculated onto lucerne host plants in competition experiments. These experiments demonstrated that no apparent advantage resulted from the ability to synthesize a rhizopine, whereas the ability to catabolize rhizopine provided a clear advantage when an organism was in competition with a strain without this ability. The results suggest that when an organism is in competition with a catabolism-deficient mutant, the ability to catabolize rhizopine results in enhanced rates of nodulation. The results of the experiments were not consistent with the hypothesis that the sole role of rhizopines is to act as proprietary growth substrates for the free-living population of the producing strain. PMID:16535438

Gordon, D M; Ryder, M H; Heinrich, K; Murphy, P J

1996-11-01

83

[Studies on transference of hydrogenase genes of Rhizobium arachis].  

Science.gov (United States)

The hydrogen-uptake genes were transferred into wild Rhizobium arachis Ra strains (Hup-, Nif+, Apr) by triparental mating using pRK2013 as help plasmid. A transconjugant R. arachis Rz34-2(Hup+, Nif+, Apr, Tcr) which expressed high activities of hydrogenase and nitrogenase under free-living and symbiotic state was screened. Peanut inoculation test with recipient R. arachis Ra34, transcojugant Rz34-2 and control strain R. arachis L8-3 (Hup+, Nif+) was carried out respectively. The results showed that, compare to treatment without inoculation, inoculation with R. arachis Ra34 and R. arachis L8-3, the dry weight of leaf inoculated with transconjuant Rz34-2 increased 6.2%, 7.6% and 6.3% respectively; the N-content of seed increased 8.8%, 10.0% and 6.0%; the output increased 18.8%, 10.5% and 10.7%. This suggested that legume plants inoculated with Rhizobium strains (Hup+) were more efficient to accumulate N and to increase its output. PMID:12552906

Wang, Z; Long, M; Liu, Y; Zhang, F; Xu, L; Zhu, T; Jiang, S

2001-08-01

84

Dynamics of genome architecture in Rhizobium sp. strain NGR234.  

Science.gov (United States)

Bacterial genomes are usually partitioned in several replicons, which are dynamic structures prone to mutation and genomic rearrangements, thus contributing to genome evolution. Nevertheless, much remains to be learned about the origins and dynamics of the formation of bacterial alternative genomic states and their possible biological consequences. To address these issues, we have studied the dynamics of the genome architecture in Rhizobium sp. strain NGR234 and analyzed its biological significance. NGR234 genome consists of three replicons: the symbiotic plasmid pNGR234a (536,165 bp), the megaplasmid pNGR234b (>2,000 kb), and the chromosome (>3,700 kb). Here we report that genome analyses of cell siblings showed the occurrence of large-scale DNA rearrangements consisting of cointegrations and excisions between the three replicons. As a result, four new genomic architectures have emerged. Three consisted of the cointegrates between two replicons: chromosome-pNGR234a, chromosome-pNGR234b, and pNGR234a-pNGR234b. The other consisted of a cointegrate of the three replicons (chromosome-pNGR234a-pNGR234b). Cointegration and excision of pNGR234a with either the chromosome or pNGR234b were studied and found to proceed via a Campbell-type mechanism, mediated by insertion sequence elements. We provide evidence showing that changes in the genome architecture did not alter the growth and symbiotic proficiency of Rhizobium derivatives. PMID:11741857

Mavingui, Patrick; Flores, Margarita; Guo, Xianwu; Dávila, Guillermo; Perret, Xavier; Broughton, William J; Palacios, Rafael

2002-01-01

85

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

86

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

87

Rhizobium alamii sp. nov., an exopolysaccharide-producing species isolated from legume and non-legume rhizospheres.  

Science.gov (United States)

A group of exopolysaccharide-producing bacteria was isolated from the root environment of Arabidopsis thaliana. The genetic diversity revealed by REP-PCR fingerprinting indicated that the isolates correspond to different strains. 16S rRNA gene sequence analysis showed that the isolates are closely related to the strains Rhizobium sp. YAS34 and USDA 1920, respectively isolated from sunflower roots and Medicago ruthenica nodules. These bacteria belong to the Rhizobium lineage of the Alphaproteobacteria, and the closest known species was Rhizobium sullae. DNA-DNA hybridization experiments and biochemical analysis demonstrated that the nine strains isolated from A. thaliana and Rhizobium strains YAS34 and USDA 1920 constitute a novel species within the genus Rhizobium, for which the name Rhizobium alamii sp. nov. is proposed. The type strain is GBV016(T) (=CFBP 7146(T) =LMG 24466(T)). PMID:19196780

Berge, Odile; Lodhi, Asma; Brandelet, Géraldine; Santaella, Catherine; Roncato, Marie-Anne; Christen, Richard; Heulin, Thierry; Achouak, Wafa

2009-02-01

88

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

OpenAIRE

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

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

1992-01-01

89

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

90

Density Centrifugation Method for Recovering Rhizobium spp. from Soil for Fluorescent-Antibody Studies †  

OpenAIRE

A density centrifugation procedure has been developed as a replacement for soil flocculation and clarification steps employed in quantitative fluorescent-antibody studies on Rhizobium in soils. Near-quantitative recovery of added cells of two strains of Rhizobium japonicum and two strains of R. phaseoli was achieved from six soils with various properties. It is proposed that this technique may prove useful in separating other soil microorganisms from soil particles in ecological studies emplo...

Wollum, A. G.; Miller, R. H.

1980-01-01

91

LysM-Type Mycorrhizal Receptor Recruited for Rhizobium Symbiosis in Nonlegume Parasponia  

OpenAIRE

Rhizobium root nodule symbiosis is generally considered to be unique for legumes. However, there is one exception and that is Parasponia. In this nonlegume, the rhizobial nodule symbiosis evolved independently and is, like in legumes, induced by rhizobium Nod factors. We used Parasponia to identify genetic constrains underlying evolution of Nod factor signalling. Part of the signalling cascade, downstream of Nod factor perception, has been recruited from the more ancient arbuscular endomycorr...

Camp, R. H. M.; Streng, A. J.; Mita, S.; Cao, Q.; Polone, E.; Liu, W.; Ammiraju, J. S. S.; Kudrna, D.; Wing, R.; Untergasser, A.; Bisseling, T.; Geurts, R.

2011-01-01

92

Nod factor signaling genes and their function in the early stages of Rhizobium infection  

OpenAIRE

A lipochitosaccharide-based signal molecule that is secreted by Rhizobium, named Nod factor (NF), induces root nodule formation in legumes. This molecule is also essential for the establishment of bacterial infection. Genetic analyses in the legume species Lotus japonicus and Medicago truncatula have led to the identification of many components of the NF signaling cascade. At least three of these genes do not function exclusively in the Rhizobium symbiosis but are also essential for the forma...

Geurts, R.; Fedorova, E.; Bisseling, T.

2005-01-01

93

Novel organization of the common nodulation genes in Rhizobium leguminosarum bv. phaseoli strains.  

OpenAIRE

Nodulation by Rhizobium, Bradyrhizobium, and Azorhizobium species in the roots of legumes and nonlegumes requires the proper expression of plant genes and of both common and specific bacterial nodulation genes. The common nodABC genes form an operon or are physically mapped together in all species studied thus far. Rhizobium leguminosarum bv. phaseoli strains are classified in two groups. The type I group has reiterated nifHDK genes and a narrow host range of nodulation. The type II group has...

Va?zquez, M.; Da?valos, A.; Las Pen?as, A.; Sa?nchez, F.; Quinto, C.

1991-01-01

94

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

OpenAIRE

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

Iruthayathas, Ee; Vlassak, K.

1985-01-01

95

Role of Rhizobium Inoculation in Chickpea (Cicer arietinum L.) Under Water Stress Conditions  

OpenAIRE

Two chickpea varieties viz., 90122 and 93081 were subjected to Rhizobium inoculation with BioPower under water stress conditions, imposed by withholding water. Stress reduced all the parameters including yield components and this effect was more pronounced by stress at reproductive stage as compared with vegetative stage. Rhizobium inoculation enhanced yield under both normal and stressed conditions, but its performance was better under normal than under stress. Rhizobium inoculation proved i...

Rahat Parveen; Sadiq, M.; Muzammil Saleem

1999-01-01

96

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

Directory of Open Access Journals (Sweden)

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.

Araújo Ademir Sérgio Ferreira de

2006-01-01

97

Signal transduction in the Rhizobium meliloti dicarboxylic acid transport system.  

Science.gov (United States)

The gene products of the Rhizobium meliloti dctB and dctD genes, which control the expression of the C4-dicarboxylic acid transporter DctA, were overproduced in Escherichia coli and purified. The purified sensor protein, DctB, was shown to have autophosphorylation activity in vitro and could subsequently phosphorylate the transcriptional activator, DctD. The presence of C4-dicarboxylic acids did not affect either reaction. In vitro experiments aimed at investigating 'crosstalk' between cognate components demonstrated that the phospho-transfer activity was specific between DctB and DctD. Studies on truncated versions of the DctB protein in vitro revealed that the cytoplasmic domain of DctB had strong autophosphorylation activity. Data from gel retardation experiments demonstrated that once the activator protein, DctD, was phosphorylated it had increased affinity for binding to the dctA promoter DNA. PMID:7896073

Giblin, L; Boesten, B; Turk, S; Hooykaas, P; O'Gara, F

1995-02-01

98

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; Nielsen, G.

1985-01-01

99

Rhizobium meliloti and Rhizobium leguminosarum dctD gene products bind to tandem sites in an activation sequence located upstream of sigma 54-dependent dctA promoters.  

OpenAIRE

Free-living rhizobia transport external C4-dicarboxylates to use as sole carbon sources, and uptake of these compounds is essential for nitrogen fixation by rhizobial bacteroids. In both Rhizobium leguminosarum and Rhizobium meliloti, the genes dctB and dctD are believed to form an ntrB/ntrC-like two-component system which regulates the synthesis of a C4-dicarboxylate transport protein encoded by dctA. Here we confirm the identity of sigma 54-dependent promoters previously hypothesized for th...

Ledebur, H.; Gu, B.; Sojda, J.; Nixon, B. T.

1990-01-01

100

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

101

Rhizobium tarimense sp. nov., isolated from soil in the ancient Khiyik River.  

Science.gov (United States)

A Gram-negative, non-motile, pale-yellow, rod-shaped bacterial strain, PL-41(T), was isolated from Populus euphratica forest soil at the ancient Khiyik River valley in Xinjiang Uyghur Autonomous Region, People's Republic of China. Strain PL-41(T) grew optimally at 30 °C and pH 7.0-8.0. The major quinone was Q-10. The predominant cellular fatty acids of strain PL-41(T) were summed feature 8 (comprising C18 : 1?7c and C18 : 1?6c), C16 : 0 and C19 : 0 cyclo ?8c. Polar lipids of strain PL-41(T) include two unidentified aminophospholipids (APL1, 2), two unidentified phospholipids (PL1, 2), phosphatidylcholine and three unidentified lipids (L1-3). Strain PL-41(T) showed 16S rRNA gene sequence similarity of 97.0-97.5 % to the type strains of recognized species of the genus Rhizobium. Phylogenetic analysis of strain PL-41(T) based on the sequences of housekeeping genes recA and atpD confirmed (similarities are less than 90 %) its position as a distinct species of the genus Rhizobium. The DNA G+C content was 57.8 mol%. DNA-DNA relatedness between strain PL-41(T) and the type strains of Rhizobium huautlense S02(T), Rhizobium alkalisoli CCBAU 01393(T), Rhizobium vignae CCBAU 05176(T) and Rhizobium loessense CCBAU 7190B(T) were 33.4, 22.6, 25.5 and 45.1 %, respectively, indicating that strain PL-41(T) was distinct from them genetically. Strain PL-41(T) also can be differentiated from these four phylogenetically related species of the genus Rhizobium by various phenotypic properties. On the basis of phenotypic properties, phylogenetic distinctiveness and genetic data, strain PL-41(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium tarimense sp. nov. is proposed. The type strain is PL-41(T) ( = CCTCC AB 2011011(T) =?NRRL B-59556(T)). PMID:23203621

Turdahon, Maripat; Osman, Ghenijan; Hamdun, Maryam; Yusuf, Khayir; Abdurehim, Zumret; Abaydulla, Gulsumay; Abdukerim, Muhtar; Fang, Chengxiang; Rahman, Erkin

2013-07-01

102

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

International Nuclear Information System (INIS)

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

103

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

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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

104

Effect of Rhizobium Inoculants on Cowpea under Rainfed Condition  

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

Sarker P. C.

2001-01-01

105

Rhizobium azibense sp. nov., a nitrogen fixing bacterium isolated from root-nodules of Phaseolus vulgaris.  

Science.gov (United States)

Three microbial strains isolated from common beans, 23C2T (Tunisia), Gr42 (Spain) and IE4868 (Mexico), which have been identified previously as representing a genomic group closely related to Rhizobium gallicum, are further studied here. Their 16S rRNA genes showed 98.5-99% similarity with Rhizobium loessense CCBAU 7190BT, R. gallicum R602spT, Rhizobium mongolense USDA 1844T and Rhizobium yanglingense CCBAU 71623T. Phylogenetic analysis based on recA, atpD, dnaK and thrC sequences showed that the novel strains were closely related and could be distinguished from the four type strains of the closely related species. Strains 23C2T, Gr42 and IE4868 could be also differentiated from their closest phylogenetic neighbours by their phenotypic and physiological properties and their fatty acid contents. All three strains harboured symbiotic genes specific to biovar gallicum. Levels of DNA-DNA relatedness between strain 23C2T and the type strains of R. loessense, R. mongolense, R. gallicum and R. yanglingense ranged from 58.1 to 61.5%. The DNA G+C content of the genomic DNA of strain 23C2T was 59.52%. On the basis of these data, strains 23C2T, Gr42 and IE4868 were considered to represent a novel species of the genus Rhizobium for which the name Rhizobium azibense is proposed. Strain 23C2T (=CCBAU 101087T=HAMBI3541T) was designated as the type strain. PMID:24478208

Mnasri, Bacem; Liu, Tian Yan; Saidi, Sabrine; Chen, Wen Feng; Chen, Wen Xin; Zhang, Xiao Xia; Mhamdi, Ridha

2014-05-01

106

Influence of carbofuran on certain metabolic and symbiotic activities of a cowpea Rhizobium  

International Nuclear Information System (INIS)

Using carbon 14 radioisotope an in-vitro study of the effect of insecticides, carbofuran, on the metabolic and symbiotic activities of Rhizobium sp. cowpea group, was carried out. The study indicated that at 10 ppm carbofuran inhibited the in-vitro growth of the bacterium, suppressed the oxidation of all the Trichloroacetic acid (TCA) cycle intermediates, significantly reduced glucose oxidation and translocation and affected the growth and symbiotic activities of the cowpea as reflected by a reduction in the dry matter production and total nitrogen content. The insecticide was itself degraded by the Rhizobium sp. within 30 days of incubation

107

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

108

Les structures et le mobilier du site d’habitat Hallstatt final-La Tène ancienne d'Allaines Mervilliers (Eure-et-Loir) Buildings and effects from the hallstatt D-Early La Tène site of Allaines Mervilliers (Eure-et-Loir)  

OpenAIRE

Découverte de structures d’habitat sur poteaux et d’une fosse Hallstatt final-La Tène ancienne dans le cadre d’une opération d’archéologie préventive en 1998, à Allaines Mervilliers (Eure-et-Loir). Il s’agit de deux bâtiments rectangulaires à six trous de poteau, d’un bâtiment rectangulaire à trois nefs et d’un bâtiment circulaire. Ces deux derniers sont inédits pour cette époque en région Centre. Le bâtiment rectangulaire à trois nefs est composé de deux rangé...

Diane Casadei; Richard Cottiaux; Hervé Sellès

2006-01-01

109

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

Science.gov (United States)

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

Stuckey, James M.

1996-01-01

110

Rhizobium selenireducens sp. nov. Validation and inclusion onto the list of organisms with standing in nomenclature.  

Science.gov (United States)

This is a submission to the list of microorganisms with standing in nomenclature. The list of valid microbial names is maintained by the International Journal of Systematic and Evolutionary Microbiology and we are proposing that Rhizobium selenireducens sp. nov. be added to the list as a valid spec...

111

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

Science.gov (United States)

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

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

2009-10-01

112

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

113

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

114

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

Science.gov (United States)

...Restricted Percentages for the 2010-2011 Crop Year for Tart Cherries AGENCY: Agricultural...marketing order for the 2010-2011 crop year. The percentages are 58 percent free and...cherries handled by handlers during the crop year. This rule establishes final free...

2011-02-25

115

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

OpenAIRE

Groundnut variety BARD-699 produced significantly the most promising yield than that of variety BARI-89 at Attock, Fatehjang and NARC, Islamabad. Rhizobium strains, NC-92 was found to be less efficient as compared to TAL-1000; TAL-1371. Nodule dry mass and number of pods per plant were much higher than that of control treatment. Although a significant difference in growth and yield of both the varieties due to Rhizobium inoculation was observed but on average basis TAL-1000 and ...

Aslam, M.; Ahmad, S.; Mahmood, I. A.; Sultan, T.

1999-01-01

116

Complete Genome Sequence of the Sesbania Symbiont and Rice Growth-Promoting Endophyte Rhizobium sp. Strain IRBG74.  

Science.gov (United States)

Rhizobium sp. strain IRBG74 is the first known nitrogen-fixing symbiont in the Agrobacterium/Rhizobium clade that nodulates the aquatic legume Sesbania sp. and is also a growth-promoting endophyte of wetland rice. Here, we present the sequence of the IRBG74 genome, which is composed of a circular chromosome, a linear chromosome, and a symbiotic plasmid, pIRBG74a. PMID:24265489

Crook, Matthew B; Mitra, Shubhajit; Ané, Jean-Michel; Sadowsky, Michael J; Gyaneshwar, Prasad

2013-01-01

117

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

118

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

119

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-01

120

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

Science.gov (United States)

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

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

2014-02-01

121

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

Directory of Open Access Journals (Sweden)

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

M. Aslam

1999-01-01

122

Relationships between C4 dicarboxylic acid transport and chemotaxis in Rhizobium meliloti.  

OpenAIRE

The relationship between chemotaxis and transport of C4 dicarboxylic acids was analyzed with Rhizobium meliloti dct mutants defective in one or all of the genes required for dicarboxylic acid transport. Succinate, malate, and fumarate were moderately potent chemoattractants for wild-type R. meliloti and appeared to share a common chemoreceptor. While dicarboxylate transport is inducible, taxis to succinate was shown to be constitutive. Mutations in the dctA and dctB genes both resulted in the...

Robinson, J. B.; Bauer, W. D.

1993-01-01

123

Clovers secrete specific phenolic compounds which either stimulate or repress nod gene expression in Rhizobium trifolii  

OpenAIRE

Rhizobium trifolii mutants containing Escherichia coli lac gene fusions to specific nodulation (nod) genes were used to characterise phenolic compounds secreted from the roots of white clover (Trifolium repens) plants. These compounds either had stimulatory or inhibitory effects upon the induction of the nod genes. The stimulatory compounds were hydroxylated flavones and the most active compound was 7,4'-dihydroxyflavone. The inhibitory compounds present in white clover root exudates were umb...

Djordjevic, Michael A.; Redmond, John W.; Batley, Michael; Rolfe, Barry G.

1987-01-01

124

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

OpenAIRE

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

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

1985-01-01

125

Diversity and specificity of Rhizobium leguminosarum biovar viciae on wild and cultivated legumes  

OpenAIRE

The symbiotic partnerships between legumes and their root-nodule bacteria (rhizobia) vary widely in their degree of specificity, but the underlying reasons are not understood. To assess the potential for host-range evolution, we have investigated microheterogeneity among the shared symbionts of a group of related legume species. Host specificity and genetic diversity were characterized for a soil population of Rhizobium leguminosarum biovar viciae (Rlv) sampled using six wild Vicia and Lathyr...

Mutch, L. A.; Young, J. P. W.

2004-01-01

126

Perception and action of nod factors in Rhizobium-legume symbiosis.  

OpenAIRE

Rhizobium bacteria are able to invade the roots of their leguminous hosts and trigger the formation of a new organ, the root nodule. In these nodules the bacteria are hosted in the proper environment for fixing atmospheric nitrogen into ammonia, making plant growth independent of nitrogen compounds from the soil. The interaction between the bacterium and the host plant starts with a signal exchange, when flavonoids excreted by the plant induce the transcription of bacterial nodulation (nod) g...

Heidstra, R.

1997-01-01

127

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

OpenAIRE

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

Plazinski, Jacek; Rolfe, Barry G.

1985-01-01

128

Lectin-enhanced accumulation of manganese-limited Rhizobium leguminosarum cells on pea root hair tips.  

OpenAIRE

The ability of Rhizobium leguminosarum 248 to attach to developing Pisum sativum root hairs was investigated during various phases of bacterial growth in yeast extract-mannitol medium. Direct cell counting revealed that growth of the rhizobia transiently stopped three successive times during batch culture in yeast extract-mannitol medium. These interruptions of growth, as well as the simultaneous autoagglutination of the bacteria, appeared to be caused by manganese limitation. Rhizobia harves...

Kijne, J. W.; Smit, G.; Di?az, C. L.; Lugtenberg, B. J.

1988-01-01

129

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

OpenAIRE

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

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

1988-01-01

130

Effect of Leguminous Lectins on the Growth of Rhizobium tropici CIAT899  

OpenAIRE

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 vari...

Mayron Alves de Vasconcelos; Cláudio Oliveira Cunha; Francisco Vassiliepe Sousa Arruda; Victor Alves Carneiro; Rafaela Mesquita Bastos; Fábio Martins Mercante; Kyria Santiago do Nascimento; Benildo de Sousa Cavada; Ricardo Pires dos Santos; Edson Holanda Teixeira

2013-01-01

131

Genetic and Metabolic Divergence within a Rhizobium leguminosarum bv. trifolii Population Recovered from Clover Nodules? †  

OpenAIRE

Rhizobia are able to establish symbiosis with leguminous plants and usually occupy highly complex soil habitats. The large size and complexity of their genomes are considered advantageous, possibly enhancing their metabolic and adaptive potential and, in consequence, their competitiveness. A population of Rhizobium leguminosarum bv. trifolii organisms recovered from nodules of several clover plants growing in each other's vicinity in the soil was examined regarding possible relationships betw...

Wielbo, Jerzy; Marek-kozaczuk, Monika; Mazur, Andrzej; Kubik-komar, Agnieszka; Skorupska, Anna

2010-01-01

132

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

OpenAIRE

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

Sanchez Can?izares, Carmen

2013-01-01

133

Cryptic plasmid and rifampin resistance in Rhizobium meliloti influencing nodulation competitiveness.  

OpenAIRE

An assessment was made of the relative contributions of a spontaneous mutation to rifampin resistance and a cryptic plasmid, pTA2, to competitive nodulation of Medicago sativa by a strain of Rhizobium meliloti. This was facilitated by use of rifampin-resistant derivatives of this strain in which pTA2 was originally present, cured, or reintroduced. Both curing of pTA2 and spontaneous mutation to rifampin resistance significantly influenced nodulating competitiveness, but the effect of rifampin...

Bromfield, E. S.; Lewis, D. M.; Barran, L. R.

1985-01-01

134

Interrelations between Meloidogyne javanica, Rotylenchulus reniformis, and Rhizobium Sp. on Vigna sinensis  

OpenAIRE

The interactions of Meloidogyne javanica, Rotylenchulus reniformis, and Rhizobium sp. on cowpea seedlings were investigated. Upon simultaneous inoculation with the two nematode species, M. javanica invaded first but did not affect root invasion by R. reniformis. M. javanica populations increased less in competition with R. reniformis than when present alone. Preinvasion by R. renilormis significantly suppressed the number of M. javanica in the roots. Inoculation of M. javanica and/or R. renif...

Taha, A. H. Y.; Kassab, A. S.

1980-01-01

135

The symbiosis between Rhizobium leguminosarum and Pisum savitum: regulation of the nitrogenase activity.  

OpenAIRE

Bacteria of the genus Rhizobium can form a symbiosis with plants of the family Leguminosae. Both bacteria and plant show considerable biochemical and morphological changes in order to develop and carry out the symbiosis. The Rhizobia induce special structures on the legumes, which are called root nodules. In these root nodules, the differentiated bacteria - so-called bacteroids - are localized. Within the root nodule the bacteroids are able to reduce atmospheric N 2

Appels, M. A.

1989-01-01

136

Biosynthesis and degradation of nodule-specific Rhizobium loti compounds in Lotus nodules.  

Science.gov (United States)

Two nodule-specific Rhizobium loti compounds were identified in Lotus tenuis and Lotus pedunculatus nodules induced by strain NZP2037. One, a silver nitrate-positive cation called rhizolotine, has been characterized as the riboside of a novel alpha-hydroxyimino acid containing a 1,4,5,6-tetrahydropyrimidine ring (G. J. Shaw, R. D. Wilson, G. A. Lane, L. D. Kennedy, D. B. Scott, and G. J. Gainsford, J. Chem. Soc. Chem. Commun., p. 180-181, 1986), and the other, yellow-1, stains yellow with ninhydrin. Both compounds were degraded by R. loti NZP2037 but not by strains of Rhizobium meliloti, Rhizobium trifolii, or Agrobacterium tumefaciens. Under the conditions tested neither compound was able to serve as a sole source of C or N for growth of R. loti NZP2037. Rhizolotine and yellow-1 were found in nodules from a range of different legumes inoculated with NZP2037, suggesting that the Rhizobium and not the host plant determines their synthesis. Neither compound was found in nodulelike structures of L. pedunculatus induced by transposon Tn5-induced noninfectious (Inf-) mutants of NZP2037 or in similar structures induced by a transconjugant of NZP2037 containing the symbiotic (Sym) cointegrate plasmid pPN1 of R. trifolii. Both compounds were also absent in the ineffective nodules induced by the bacterial-release-negative (Bar-) mutant, strain PN239. However, both compounds were present in nodules induced by the fixation-negative (Fix-) mutant PN235 and in Fix+ nodules formed by a plasmid-cured derivative of NZP2037. These results would suggest that infection and bacterial release from the infection thread are necessary for nodule (symbiotic) synthesis of these compounds. PMID:3025173

Scott, D B; Wilson, R; Shaw, G J; Petit, A; Tempe, J

1987-01-01

137

Role of Microniches in Protecting Introduced Rhizobium leguminosarum biovar trifolii against Competition and Predation in Soil  

OpenAIRE

The importance of microniches for the survival of introduced Rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate Bodo saltans, precultured on rhizobial cells. The introduced organisms were enumerated in different soil fractions by washing the soil, using a standar...

Postma, J.; Hok-a-hin, C. H.; Veen, J. A.

1990-01-01

138

Rhizobium symbiotic genes required for nodulation of legume and nonlegume hosts  

OpenAIRE

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

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

1987-01-01

139

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

OpenAIRE

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

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

1990-01-01

140

Effect of Rhizobium inoculation and phosphorus application on native Texas legumes grown in local soil  

OpenAIRE

Greenhouse experiments were conducted to determine the effects of Rhizobium inoculation and addition of phosphorus to soil on the productivity and quality of the Texas range legumes Desmanthus illinoiensis (Michx.) MacMill. ex B.L. Rob. & Fernald, Desmanthus velutinus Scheele, Desmanthus virgatus (L.) Willd., and Neptunia lutea (Leavenw.) Benth. Phosphorus (P) fertilization was applied at 0, 40, 80, and 120 kg P ha-1 in Experiment 1 with half the pots also receiving D522-1/2 (a Desmanthus iso...

Osman, E.; Muir, J. P.; Elgersma, A.

2002-01-01

141

ABC Transport Is Inactivated by the PTSNtr under Potassium Limitation in Rhizobium leguminosarum 3841  

OpenAIRE

PTSNtr is a regulatory phosphotransferase system in many bacteria. Mutation of the PTSNtr enzymes causes pleiotropic growth phenotypes, dry colony morphology and a posttranslational inactivation of ABC transporters in Rhizobium leguminosarum 3841. The PTSNtr proteins EINtr and 2 copies of EIIANtr have been described previously. Here we identify the intermediate phosphocarrier protein NPr and show its phosphorylation by EINtr in vitro. Furthermore we demonstrate that phosphorylation of EINt...

Untiet, Verena; Karunakaran, Ramakrishnan; Kra?mer, Maria; Poole, Philip; Priefer, Ursula; Prell, Ju?rgen

2013-01-01

142

Growth and Nodulation Responses of Rhizobium meliloti to Water Stress Induced by Permeating and Nonpermeating Solutes †  

OpenAIRE

Isolates of Rhizobium meliloti, representing antigenically distinct indigenous serogroups 31 and 17, were grown in yeast extract-mannitol broth (YEM) containing NaCl or polyethylene glycol (PEG) to provide external water potentials ranging from ?0.15 to ?1.5 MPa. Several differences were found between representatives of the two groups in their abilities to adapt to water stress induced by the nonpermeating solute PEG. At potentials below ?0.5 MPa, strain 31 had a lower specific growth r...

Busse, Matt D.; Bottomley, Peter J.

1989-01-01

143

Expression by Soil Bacteria of Nodulation Genes from Rhizobium leguminosarum biovar trifolii  

OpenAIRE

Gram-negative, rod-shaped bacteria from the soil of white clover-ryegrass pastures were screened for their ability to nodulate white clover (Trifolium repens) cultivar Grasslands Huia and for DNA homology with genomic DNA from Rhizobium leguminosarum biovar trifolii ICMP2668 (NZP582). Of these strains, 3.2% were able to hybridize with strain ICMP2668 and nodulate white clover and approximately 19% hybridized but were unable to nodulate. Strains which nodulated but did not hybridize with strai...

Jarvis, B. D. W.; Ward, L. J. H.; Slade, E. A.

1989-01-01

144

Glucose-6-phosphate dehydrogenase deficiency in pleiotropic carbohydrate-negative mutant strains of Rhizobium meliloti.  

OpenAIRE

Several mutant strains of Rhizobium meliloti isolated after nitrosoguanidine mutagenesis were selected as unable to grow on mannose. Some of them also failed to grow on glucose, fructose, ribose, and xylose but grew on L-arabinose, galactose, and many other carbon sources. Biochemical analysis demonstrated that the mutants lacked NAD- and NADP-linked glucose-6-phosphate dehydrogenase activities that reside on a single enzyme species. One such mutant was found to accumulate glucose-6-phosphate...

Cerven?ansky?, C.; Arias, A.

1984-01-01

145

Role of divalent cations in the subunit associations of complex flagella from Rhizobium meliloti.  

OpenAIRE

Rhizobium meliloti, a symbiotic, nitrogen-fixing soil bacterium with complex flagella, as well as other members of the family Rhizobiaceae, rapidly lost motility when suspended in buffers lacking divalent cations but retained good motility in buffers containing calcium, magnesium, barium, or strontium. Loss of motility was associated with loss of flagella from the cells. Analysis of flagella by sedimentation, gel electrophoresis, and electron microscopy revealed that removal of divalent catio...

Robinson, J. B.; Tuovinen, O. H.; Bauer, W. D.

1992-01-01

146

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

OpenAIRE

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

147

Siderophore biosynthesis genes of Rhizobium sp. isolated from Cicer arietinum L.  

OpenAIRE

Rhizobium BICC 651, a fast-growing strain isolated from root nodule of chickpea (Cicer arietinum L.), produced a catechol siderophore to acquire iron under iron poor condition. A Tn5-induced mutant (B153) of the strain, BICC 651 impaired in siderophore biosynthesis was isolated and characterized. The mutant failed to grow on medium supplemented with iron chelator and grew less efficiently in deferrated broth indicating its higher iron requirement. The mutant produced less number of nodules th...

Datta, Bejoysekhar; Chakrabartty, Pran K.

2013-01-01

148

Isolation of Rhizobium meliloti nod Gene Inducers from Alfalfa Rhizosphere Soil  

OpenAIRE

Methanolic extracts of alfalfa rhizosphere soil induce more nod gene transcription in Rhizobium meliloti than extracts of nonrhizosphere soil. Six peaks of nod-inducing activity were separated by high-performance liquid chromatography from rhizosphere soil extract, and one compound was identified by 1H nuclear magnetic resonance, mass spectrometry, and UV-visible spectra as a formononetin-7-O-glycoside that activates both NodD1 and NodD2 proteins. The unanticipated presence of a glycoside in ...

Leo?n-barrios, Milagros; Dakora, Felix D.; Joseph, Cecillia M.; Phillips, Donald A.

1993-01-01

149

Rhizobium-mediated induction of phenolics and plant growth promotion in rice (Oryza sativa L.).  

Science.gov (United States)

Qualitative and quantitative estimation of phenolic compounds was done through reverse phase-high performance liquid chromatography (RP-HPLC) from different parts (leaf, stem, and root) of rice plants after inoculation with two rhizobial strains, RRE6 (Rhizobium leguminosarum bv. phaseoli) and ANU 843 (R. leguminosarum bv. trifolii) and infection by Rhizoctonia solani. On the basis of their retention time, the major phenolic acids detected in HPLC analysis were gallic, tannic, ferulic, and cinnamic acids. Furthermore, in all Rhizobium-inoculated rice plants, synthesis of phenolic compounds was more consistently enhanced than in control (uninoculated plants), where the maximum accumulation of phenolic compounds was observed in plants inoculated with RRE6 and infection with R. solani. Under pathogenic stress, RRE6 performed better because a relatively higher amount of phenolics was induced as compared with plants treated with ANU 843. Phenolic acids mediate induced systemic resistance and provide bioprotection to plants during pathogenic stresses. In addition, both rhizobial strains promote growth and productivity of rice plants in greenhouse conditions. This report on Rhizobium-mediated defense responses and growth promotion of nonlegume (such as rice) provides a novel paradigm of symbiotic plant-microbe interaction. PMID:16586021

Mishra, Ravi P N; Singh, Ramesh K; Jaiswal, Hemant K; Kumar, Vinod; Maurya, Sudarshan

2006-05-01

150

Isolation and characterization of the constitutive acyl carrier protein from Rhizobium meliloti.  

Science.gov (United States)

Rhizobium species produce an inducible acyl carrier protein (ACP), encoded by the nodF gene, that somehow functions in an exchange of cell signals between bacteria and specific plant hosts, leading to nodulation of plant roots and symbiotic nitrogen fixation, as well as a constitutive ACP needed for the synthesis of essential cell lipids. The periplasmic cyclic glucans of Rhizobium spp. are also involved in specific rhizobium-plant interaction. These glucans are strongly similar to the periplasmic membrane-derived oligosaccharides (MDO) of Escherichia coli. E. coli ACP is an essential component of a membrane-bound transglucosylase needed for the biosynthesis of MDO, raising the possibility that either or both of the rhizobial ACPs might have a similar function. We have now isolated the constitutive ACP of R. meliloti and determined its primary structure. We have also examined its function, together with those of ACPs from E. coli, Rhodobacter sphaeroides, and spinach, in the MDO transglucosylase system and as substrate for the E. coli ACP acylase enzyme. All four ACPs act as acceptors of acyl residues, but only the E. coli ACP functions in the transglucosylase system. PMID:2144277

Platt, M W; Miller, K J; Lane, W S; Kennedy, E P

1990-09-01

151

In vitro sensitivity of Rhizobium and phosphate solubilising bacteria to herbicides.  

Science.gov (United States)

Nitrogen fixing bacteria, rhizobia and phosphate solubilizing bacteria (PSB) are the commonly applied microbial inoculants in grain legumes (Pulses). It is important to apply herbicides to control weeds in order to augment yield of the crop. The herbicides may however, be incompatible with the microbial inoculants. This study compared the effect of the recommended pre-plant incorporated herbicide, fluchloralin (20.25 × 10(4) ppm) and pre-emergence herbicide, pendimethalin in two doses (9 × 10(4) and 15 × 10(4) ppm) on the growth and survival of mungbean Rhizobium and PSB, under laboratory conditions. These herbicides were also used under field conditions in conjunction with biofertilizers (R, PSB) to improve grain yield of mungbean. It was found that fluchloralin (20.25 × 10(4) ppm) and the lower dose of pendimethalin (9 × 10(4) ppm) had no adverse effect on growth of Rhizobium and PSB. The higher dose of pendimethalin (15 × 10(4) ppm) was safe on PSB but it imposed a retarding effect on the growth of Rhizobium. PMID:22654170

Jeenie; Sharma, Poonam; Khanna, Veena

2011-06-01

152

Oxamate is an alternative substrate for pyruvate carboxylase from Rhizobium etli.  

Science.gov (United States)

Oxamate, an isosteric and isoelectronic inhibitory analogue of pyruvate, enhances the rate of enzymatic decarboxylation of oxaloacetate in the carboxyl transferase domain of pyruvate carboxylase (PC). It is unclear, though, how oxamate exerts a stimulatory effect on the enzymatic reaction. Herein, we report direct (13)C nuclear magnetic resonance (NMR) evidence that oxamate acts as a carboxyl acceptor, forming a carbamylated oxamate product and thereby accelerating the enzymatic decarboxylation reaction. (13)C NMR was used to monitor the PC-catalyzed formation of [4-(13)C]oxaloacetate and subsequent transfer of (13)CO(2) from oxaloacetate to oxamate. In the presence of oxamate, the apparent K(m) for oxaloacetate is artificially suppressed (from 15 to 4-5 ?M). Interestingly, the steady-state kinetic analysis of the initial rates determined at varying concentrations of oxaloacetate and fixed concentrations of oxamate revealed initial velocity patterns inconsistent with a simple ping-pong-type mechanism. Rather, the patterns suggest the existence of an alternate decarboxylation pathway in which an unstable intermediate is formed. The steady-state kinetic analysis coupled with the normal (13)(V/K) kinetic isotope effect observed on C-4 of oxaloacetate [(13)(V/K) = 1.0117 ± 0.0005] indicates that the transfer of CO(2) from carboxybiotin to oxamate is the partially rate-limiting step of the enzymatic reaction. The catalytic mechanism proposed for the carboxylation of oxamate is similar to that proposed for the carboxylation of pyruvate, which occurs via the formation of an enol intermediate. PMID:23560609

Marlier, John F; Cleland, W W; Zeczycki, Tonya N

2013-04-30

153

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

Directory of Open Access Journals (Sweden)

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

154

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

Directory of Open Access Journals (Sweden)

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

155

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

Directory of Open Access Journals (Sweden)

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

156

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  

Directory of Open Access Journals (Sweden)

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

157

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.  

Science.gov (United States)

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 1.67 x 10(5) to 22 x 10(5) cfu g(-1) FW for Baccras cv. and 3.67 x 10(5) to 26 x 10(5) 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 0.67 x 10(5) to 21 x 10(5) cfu g(-1) FW for Baccross cv. and 0.33 x 10(5) to 18 x 10(5) 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. PMID:18819640

Mehry, Askary; Akbar, Mostajeran; Giti, Emtiazi

2008-06-15

158

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)

159

Fixation biologique de l'azote et possibilité de nodulation croisée chez les deux espèces d'acacias producteurs de gomme dure : Acacia senegal L. Willd. et Acacia laeta R. Br. ex. Benth.  

OpenAIRE

Neuf souches de #Rhizobium$ à croissance rapide, isolées de nodosités soit d'#A. laeta$ soit d'#A. senegal$ provoquent indifféremment, en trois semaines, au laboratoire, la nodulation de l'une et de l'autre de ces deux espèces : la nodulation croisée est donc possible entre elles malgré leurs différences. L'effectivité de ces souches est démontrée : les symbioses obtenues amènent, en 5 semaines de fonctionnement et par rapport aux témoins, une augmentation moyenne de l'azote des ...

Badji, S.; Ducousso, M.; Gueye, M.; Colonna, Jean-paul

1988-01-01

160

“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

161

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

Directory of Open Access Journals (Sweden)

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

162

Effect of Rhizobium inoculation on some characters of a high protein mutant and its parent field bean Vicia faba L  

International Nuclear Information System (INIS)

M1011 is a high protein mutant originally selected from the Egyptian bean (Vicia faba L.) variety Giza2 (G2) after seven generations of treating seeds with 4kR of 60Co gamma rays. Both the mutant line M1011 and its parent variety G2 were planted in soil inoculated with Rhizobium phaseoli after being sterilized. The plant and yield characters of both were then investigated. Results showed that the mean values of plant height, total and fertile number of branches per plant, number of pods per plant, seed yield and seed protein content increased significantly in both M1011 and G2 due to pre-sowing Rhizobium inoculation. Significant earliness in flowering and an increase in the number of seeds per pod were also noticed in M1011 after Rhizobium treatment. Therefore, the mutant line showed higher efficiency in utilizing bacterially fixed nitrogen than its parent mother variety Giza2. (author)

163

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

International Nuclear Information System (INIS)

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

164

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

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

Amalia Baraibar

1999-06-01

165

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

Scientific Electronic Library Online (English)

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

Amalia, Baraibar; Llillian, Frioni; Maria Elena, Guedes; Hans, Ljunggren.

1010-10-01

166

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)

167

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

International Nuclear Information System (INIS)

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

168

Pengaruh Penambahan Inokulum Rhizobium Terhadap Efektivitas Nodulasi dan Produksi Beberapa Varietas Kedelai (Glycine max L.) pada Tanah Ultisol  

OpenAIRE

Ultisol soil has been acid pH and low fertility of soil which is poor of nitrogen element, that’s why it needed an effort to increase of soybean productivity on the Ultisol soil through by repairing technology of fertility of soil with addition of Legin or Rhizobium inoculants which content of bacterial Rhizobium for the inoculation to make symbioses of legume, forming nodule and to fix nitrogen from the air so that can sufficient of demand requirement of crop nitrogen. The objective of the...

Tampubolon, Rosdyna M.

2011-01-01

169

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.

170

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

171

Generación de una mutateca en Rhizobium leguminosarum para el análisis de proteínas Tat-dependientes  

OpenAIRE

1) Se ha desarrollado una metodología de obtención, ordenación y conservación de mutantes obtenidos por transposición aleatoria de Rhizobium leguminosarum bv viciae generándose una mutateca con 2.304 mutantes. 2) Se ha determinado un método de extracción de ADN total de lotes 576 colonias de mutantes que permite amplificar un mutante control. 3) Se ha podido localizar un mutante en R. leguminosarum (mutRL3370) en el gen RL3370, a partir de la mutateca. 4) La proteína RL3370 es homól...

Abad Arranz, Juan

2008-01-01

172

Enzymatic Tailoring of Ornithine in the Biosynthesis of the Rhizobium Cyclic Trihydroxamate Siderophore Vicibactin  

OpenAIRE

To acquire iron, the N2-fixing, symbiotic bacterium Rhizobium sp. produce the cyclic tri-hydroxamate siderophore vicibactin, containing a 30-membered tri-lactone scaffold. Herein we report the overproduction and purification of the six proteins VbsACGOLS in the bacterial host Escherichia coli and the reconstitution of the biosynthesis of vicibactin from primary metabolites. The flavoprotein VbsO acts as a pathway-initiating L-ornithine N5-hydroxylase, followed by VbsA which transfers (R)-3-hy...

Heemstra, John R.; Walsh, Christopher T.; Sattely, Elizabeth S.

2009-01-01

173

Plant gene expression in early stages of Rhizobium-legume symbiosis.  

OpenAIRE

Upon infection of the root of a leguminous plant with bacteria of the genus Rhizobium or Bradyrhizobium root nodules are formed in which symbiotic dinitrogen fixation occurs. In the host plant a set of genes is only expressed during the formation of a root nodule. These plant genes are termed nodulin genes (Van Kammen, 1984). Based upon the stage of development of the root nodule in which nodulin genes become expressed a distinction is made between early and late nodulin genes (Nap and Bissel...

Gloudemans, T.; Bisseling, T.

1989-01-01

174

Correlation between extracellular fibrils and attachment of Rhizobium leguminosarum to pea root hair tips.  

OpenAIRE

As part of a project meant to characterize molecules involved in nodulation, a semiquantitative microscopic assay was developed for measuring attachment of Rhizobium leguminosarum cells to pea root hair tips, i.e., the site at which R. leguminosarum initiates nodulation. This form of attachment, designated as cap formation, was dependent on the incubation pH and growth phase, with optimal attachment at pH 7.5 and with bacteria in the early stationary phase of growth. Addition of glucose to th...

Smit, G.; Kijne, J. W.; Lugtenberg, B. J.

1986-01-01

175

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)

176

Modulating DNA bending affects NodD-mediated transcriptional control in Rhizobium leguminosarum  

OpenAIRE

Rhizobium leguminosarum NodD binds to the nod box of the inducible nod gene nodA as a V-shaped tetramer and bends the nod box. In this work, we show that the nod gene inducer naringenin decreased gel mobility of nod box DNA–NodD complexes by sharpening the NodD-induced DNA bend, which correlated with nodA transcription activation. NodD can induce different DNA bends when the distance between the two half-sites of the nod box was modified, which severely affected NodD-mediated transcriptiona...

Chen, Xiao-chun; Feng, Jie; Hou, Bi-he; Li, Feng-qing; Li, Qiang; Hong, Guo-fan

2005-01-01

177

Indoleacetic acid production by Rhizobium sp. from a leguminous tree, Erythrina indica.  

Science.gov (United States)

Rhizobium sp. isolated from the root nodules of Erythrina indica Lamk., a leguminous tree, produced large amounts of indoleacetic acid (IAA) from tryptophan. L-Tryptophan (2 mg/ mL) was preferred to DL-tryptophan for IAA synthesis. Attempts were made to optimize the cultural requirements for an accelerated IAA production. An enrichment of the carbon-free incubation medium with maltose (1 %), MnSO4 x H2O (5 microg/mL), and Triton X-100 (100 ppm) promoted the synthesized IAA content of the medium by 480 %. PMID:18425685

Bhowmick, P K; Basu, P S

1987-01-01

178

Proton motive force in washed cells of Rhizobium japonicum and bacteroids from Glycine max.  

OpenAIRE

The components of the proton motive force (delta p), namely the membrane potential and the transmembrane pH gradient, were measured in washed cells of Rhizobium japonicum CC705 grown in cultures (5% O2-95% N2) in the presence of 10 mM KNO3 and in bacteroids from Glycine max. The delta p and its components remained reasonably constant in cells as well as in bacteroids at various stages of growth. The effects of uncouplers and ATPase inhibitors on the delta p and its components were determined ...

Bhandari, B.; Nicholas, D. J.

1985-01-01

179

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

OpenAIRE

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

Berthelot, Karine; Delmotte, Francis M.

1999-01-01

180

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

Directory of Open Access Journals (Sweden)

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

181

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

OpenAIRE

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

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

1993-01-01

182

Genetic organization of the hydrogen uptake (hup) cluster from Rhizobium leguminosarum.  

OpenAIRE

In symbiosis with peas, Rhizobium leguminosarum UPM791 induces the synthesis of a hydrogen uptake (Hup) system that recycles hydrogen generated in nodules by nitrogenase. A cosmid (pAL618) containing hup genes from this strain on a 20-kilobase-pair (kb) DNA insert has previously been isolated in our laboratory (A. Leyva, J. M. Palacios, T. Mozo, and T.Ruiz-Argüeso, J. Bacteriol. 169:4929-4934, 1987). Here we show that cosmid pAL618 contains all of the genetic information required to confer h...

Leyva, A.; Palacios, J. M.; Murillo, J.; Ruiz-argu?eso, T.

1990-01-01

183

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

OpenAIRE

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

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

1990-01-01

184

[Effect of 2-ketogluconic acid synthesis on the exopolysaccharide production in a Rhizobium meliloti strain].  

Science.gov (United States)

Two categories of carbon substrates are defined for Rhizobium meliloti: the first favours the synthesis of exopolysaccharides (fructose belongs to this category) while the other is not suitable (glucose belongs to this category). With fructose, resting cells synthesize polysaccharides during more than 100 h and this synthesis is at its best in aerobic conditions at 30 degrees C. With glucose, 2-ketogluconic acid accumulates and rapidly stops the synthesis. The method used to stop this acidification allows with glucose a synthesis which can be compared to the one obtained with fructose. PMID:43767

Courtois, B; Hornez, J P; Derieux, J C

1979-10-01

185

Expression of Rhizobium trifolii early nodulation genes on maize and rice plants.  

OpenAIRE

An IncQ multicopy vector (pKT230) and an IncP1 low-copy-number vector (pRK290), both carrying Rhizobium trifolii root hair curling (Hac) genes, were transferred to a Sym plasmid-cured derivative of R. trifolii ANU843. The resulting transconjugants were used to inoculate the monocotyledonous plants sorghum, maize, rice, and wheat. Transconjugants carrying the Hac genes on the multicopy vector caused a root hair curling response on maize and rice plants 14 days after inoculation.

Plazinski, J.; Innes, R. W.; Rolfe, B. G.

1985-01-01

186

Identification and mobilization by cointegrate formation of a nodulation plasmid in Rhizobium trifolii.  

OpenAIRE

A nodulation plasmid, pRtr-514a, of molecular size 180 megadaltons (Mdal) was identified in Rhizobium trifolii strain NZP514. This plasmid was absent in both spontaneous and heat-cured Nod- derivatives of NZP514, and these strains were unable to induce root hair curling. The ability to nodulate clover was transferred from the wild-type strain to a Nod- derivatives, PN104, with the broad-host-range plasmid R68.45 (39 megadaltons) at a cotransfer frequency of about 4 X 10(-3). Most of the Nod+ ...

Scott, D. B.; Ronson, C. W.

1982-01-01

187

Nodulating strains of Rhizobium loti arise through chromosomal symbiotic gene transfer in the environment.  

OpenAIRE

Rhizobia were isolated from nodules off a stand of Lotus corniculatus established with a single inoculant strain, ICMP3153, 7 years earlier in an area devoid of naturalized Rhizobium loti. The isolates showed diversity in growth rate, Spe I fingerprint of genomic DNA, and hybridization pattern to genomic DNA probes. The 19% of isolates that grew at the same rate as strain ICMP3153 were the only isolates that had the same fingerprint as strain ICMP3153. Sequencing of part of the 16S rRNA gene ...

Sullivan, J. T.; Patrick, H. N.; Lowther, W. L.; Scott, D. B.; Ronson, C. W.

1995-01-01

188

Molecular cloning and genetic organization of C4-dicarboxylate transport genes from Rhizobium leguminosarum.  

OpenAIRE

Cosmids containing C4-dicarboxylate transport (dct) genes were identified from a gene bank of Rhizobium leguminosarum DNA made in the broad-host-range vector pLAFR1 by their ability to complement R. trifolii dct mutants. The dct genes were further characterized by subcloning, restriction site mapping, and transposon Tn5 and Tn7 mutageneses. Three dct loci were identified within a 5.5-kilobase region of DNA, in the order dctA-dctB-dctC. The results suggested that dctA encoded a structural comp...

Ronson, C. W.; Astwood, P. M.; Downie, J. A.

1984-01-01

189

Repeated sequences similar to insertion elements clustered around the nif region of the Rhizobium japonicum genome.  

OpenAIRE

Two different repeated sequences (RSs) were discovered in the Rhizobium japonicum genome: RSRj alpha is 1126 base pairs long and is repeated 12 times; RSRj beta is approximately 950 base pairs long and is repeated at least 6 times. Their arrangement in root nodule bacteroid DNA is the same as in DNA from bacteria grown in culture. Deletion analysis showed that many copies of alpha and beta are clustered around the nitrogenase genes nifDK and nifH, or, in general, they are found within a genom...

Kaluza, K.; Hahn, M.; Hennecke, H.

1985-01-01

190

Phylogenetic analysis of the genera Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium on the basis of 16S rRNA gene and internally transcribed spacer region sequences.  

Science.gov (United States)

A total of 128 strains was isolated from more than 23 legume hosts in Korea. Phylogenetic relationships between these Korean isolates and reference strains of the genera Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium were analysed using their 16S rRNA gene and internally transcribed spacer (ITS) region sequences. Among the Bradyrhizobium strains, dendrograms based on both the 16S rRNA gene and ITS region sequences produced two main groups. The ITS tree yielded at least two new clusters that were discernable from the seven previously delineated genospecies. Large discrepancies were revealed between phylogenetic dendrograms based on 16S rRNA gene and ITS region sequences for members of the genus Rhizobium, reflecting their taxonomic heterogeneity. The amalgamation of Rhizobium and former members of Agrobacterium was confirmed using the 16S rRNA tree. Phylogenetic analysis of ITS region sequences showed that the Rhizobium giardinii clade (group II) and the Rhizobium radiobacter/Rhizobium rubi clade (group III) could be tentatively recognized as groups that are separable from the core group (group I), which includes Rhizobium leguminosarum. Dendrograms based on the 16S rRNA gene and ITS region sequences of Mesorhizobium strains were highly conflicting due to the poor taxonomic resolution of the 16S rRNA gene sequences and the low confidence in the ITS dendrogram. Several Korean isolates within the genus Mesorhizobium are thought to represent novel taxa when considering their relatively low ITS region sequence similarities (<80 %) to the reference strains. PMID:15653885

Kwon, Soon-Wo; Park, Jin-Young; Kim, Jong-Shik; Kang, Jun-Won; Cho, Yang-Hee; Lim, Chun-Keun; Parker, Matthew A; Lee, Gil-Bok

2005-01-01

191

The conjugative plasmid of a bean-nodulating Sinorhizobium fredii strain is assembled from sequences of two Rhizobium plasmids and the chromosome of a Sinorhizobium strain  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Bean-nodulating Rhizobium etli originated in Mesoamerica, while soybean-nodulating Sinorhizobium fredii evolved in East Asia. S. fredii strains, such as GR64, have been isolated from bean nodules in Spain, suggesting the occurrence of conjugative transfer events between introduced and native strains. In R. etli CFN42, transfer of the symbiotic plasmid (pRet42d requires cointegration with the endogenous self-transmissible plasmid pRet42a. Aiming at further understanding the generation of diversity among bean nodulating strains, we analyzed the plasmids of S. fredii GR64: pSfr64a and pSfr64b (symbiotic plasmid. Results The conjugative transfer of the plasmids of strain GR64 was analyzed. Plasmid pSfr64a was self-transmissible, and required for transfer of the symbiotic plasmid. We sequenced pSfr64a, finding 166 ORFs. pSfr64a showed three large segments of different evolutionary origins; the first one presented 38 ORFs that were highly similar to genes located on the chromosome of Sinorhizobium strain NGR234; the second one harbored 51 ORFs with highest similarity to genes from pRet42d, including the replication, but not the symbiosis genes. Accordingly, pSfr64a was incompatible with the R. etli CFN42 symbiotic plasmid, but did not contribute to symbiosis. The third segment contained 36 ORFs with highest similarity to genes localized on pRet42a, 20 of them involved in conjugative transfer. Plasmid pRet42a was unable to substitute pSfr64a for induction of pSym transfer, and its own transfer was significantly diminished in GR64 background. The symbiotic plasmid pSfr64b was found to differ from typical R. etli symbiotic plasmids. Conclusions S. fredii GR64 contains a chimeric transmissible plasmid, with segments from two R. etli plasmids and a S. fredii chromosome, and a symbiotic plasmid different from the one usually found in R. etli bv phaseoli. We infer that these plasmids originated through the transfer of a symbiotic-conjugative-plasmid cointegrate from R. etli to a S. fredii strain, and at least two recombination events among the R. etli plasmids and the S. fredii genome. As in R. etli CFN42, the S. fredii GR64 transmissible plasmid is required for the conjugative transfer of the symbiotic plasmid. In spite of the similarity in the conjugation related genes, the transfer process of these plasmids shows a host-specific behaviour.

Brom Susana

2011-06-01

192

Mutational Analysis of the Phosphate-Binding Loop of Rhizobium meliloti DctD, a ?54-Dependent Activator  

OpenAIRE

The phosphate-binding loop of ?54-dependent activators is thought to participate in ATP binding and/or hydrolysis. Alanine substitutions at positions 3, 4, 6, 7, and 8 of this motif in Rhizobium meliloti DctD disrupted transcriptional activation and ATP hydrolysis. Interestingly, substitution of alanine at position 7 also affected DNA binding.

Gao, Yan; Wang, Ying-kai; Hoover, Timothy R.

1998-01-01

193

Mutational analysis of the phosphate-binding loop of Rhizobium meliloti DctD, a sigma54-dependent activator.  

Science.gov (United States)

The phosphate-binding loop of sigma54-dependent activators is thought to participate in ATP binding and/or hydrolysis. Alanine substitutions at positions 3, 4, 6, 7, and 8 of this motif in Rhizobium meliloti DctD disrupted transcriptional activation and ATP hydrolysis. Interestingly, substitution of alanine at position 7 also affected DNA binding. PMID:9573172

Gao, Y; Wang, Y K; Hoover, T R

1998-05-01

194

Serine residue 45 of nodulation protein NodF from Rhizobium leguminosarum bv. viciae is essential for its biological function.  

Science.gov (United States)

A system for testing the role of the Rhizobium nodF gene in the production of host-specific lipochitin oligosaccharides and in nodulation was developed. We show that a mutant nodF gene, in which the codon for serine residue 45 was changed to that for threonine, still expresses NodF, which, however, is no longer functional. PMID:8002602

Ritsema, T; Geiger, O; van Dillewijn, P; Lugtenberg, B J; Spaink, H P

1994-12-01

195

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

196

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

197

Identification of the diacylglycerol kinase structural gene of Rhizobium meliloti 1021.  

Science.gov (United States)

The cyclic beta-1,2-glucans of Rhizobium may function during legume nodulation. These molecules may become highly substituted with phosphoglycerol moieties from the head group of phosphatidylglycerol; diglyceride is a by-product of this reaction (K. J. Miller, R. S. Gore, and A. J. Benesi, J. Bacteriol. 170:4569-4575, 1988). We recently reported that R. meliloti 1021 produces a diacylglycerol kinase (EC 2.7.1.107) activity that shares several properties with the diacylglycerol kinase enzyme of Escherichia coli (W. P. Hunt, R. S. Gore, K. J. Miller, Appl. Environ. Microbiol. 57:3645-3647, 1991). A primary function of this rhizobial enzyme is to recycle diglyceride generated during cyclic beta-1,2-glucan biosynthesis. In the present study, we report the cloning and initial characterization of a single-copy gene from R. meliloti 1021 that encodes a diacylglycerol kinase homolog; this homolog can complement a diacylglycerol kinase deficient strain of E. coli. The sequence of the rhizobial diacylglycerol kinase gene was predicted to encode a protein of 137 amino acids; this protein shares 32% identity with the E. coli enzyme. Analysis of hydropathy and the potential to form specific secondary structures indicated a common overall structure for the two enzymes. Because diglyceride metabolism and cyclic beta-1,2-glucan biosynthesis are metabolically linked, future studies with diacylglycerol kinase mutants of R. meliloti 1021 should further elucidate the roles of the cyclic beta-1,2-glucans in the Rhizobium-legume symbiosis. PMID:1335301

Miller, K J; McKinstry, M W; Hunt, W P; Nixon, B T

1992-01-01

198

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

199

Effects of simulated, acidified rain on nodulation of leguminous plants by Rhizobium spp  

Energy Technology Data Exchange (ETDEWEB)

Simulated rain acidified with sulfuric acid to pH 3.2 inhibited Rhizobium nodulation of greenhouse- and field-grown kidney beans (Phaseolus vulgarius ''Red Kidney'') and greenhouse-grown soybeans (Glycine max ''Lee''). Plants were inoculated with Rhizobium and exposed at regular intervals to simulated rain of pH 3.2 +/- 0.1 or pH 6.0 +/- 0.2 at a rate of 1.9-5.7 cm/week for 1-9 weeks. Nodulation of kidney beans and soybeans exposed to acid ''rain'' (pH 3.2) was inhibited by 73%. Neither nitrogenase activity per plant nor nitrogenase activity per nodule formed was consistently inhibited, however. Nodulation of kidney beans was inhibited when ''rain'' of pH 3.2 was applied only to the foliage as well as when applied only to the soil or to the soil and foliage together. Inhibition of nodulation was partially or completely reversed in three or four soil types tested by addition of dolomitic lime (0.75 g/kg soil approx. = 1500 kg/ha). These results suggest that acidic precipitation is a potentially important environmental stress factor under marginal site conditions where bacterial symbiosis may be critical to the fitness of temperate leguminous plants.

Shriner, D.S.; Johnston, J.W.

1981-01-01

200

Production of proteasome inhibitor syringolin A by the endophyte Rhizobium sp. strain AP16.  

Science.gov (United States)

Syringolin A, the product of a mixed nonribosomal peptide synthetase/polyketide synthase encoded by the syl gene cluster, is a virulence factor secreted by certain Pseudomonas syringae strains. Together with the glidobactins produced by a number of beta- and gammaproteobacterial human and animal pathogens, it belongs to the syrbactins, a structurally novel class of proteasome inhibitors. In plants, proteasome inhibition by syringolin A-producing P. syringae strains leads to the suppression of host defense pathways requiring proteasome activity, such as the ones mediated by salicylic acid and jasmonic acid. Here we report the discovery of a syl-like gene cluster with some unusual features in the alphaproteobacterial endophyte Rhizobium sp. strain AP16 that encodes a putative syringolin A-like synthetase whose components share 55% to 65% sequence identity (72% to 79% similarity) at the amino acid level. As revealed by average nucleotide identity (ANI) calculations, this strain likely belongs to the same species as biocontrol strain R. rhizogenes K84 (formely known as Agrobacterium radiobacter K84), which, however, carries a nonfunctional deletion remnant of the syl-like gene cluster. Here we present a functional analysis of the syl-like gene cluster of Rhizobium sp. strain AP16 and demonstrate that this endophyte synthesizes syringolin A and some related minor variants, suggesting that proteasome inhibition by syrbactin production can be important not only for pathogens but also for endophytic bacteria in the interaction with their hosts. PMID:24727275

Dudnik, Alexey; Bigler, Laurent; Dudler, Robert

2014-06-01

201

Expression of Bradyrhizobium japonicum nodulation gene in Rhizobium fredii nod mutants.  

Science.gov (United States)

The B. japonicum USDA 110 pLAFR1 gene library was transferred to Tn5-induced Rhizobium fredii USDA 191-4 Nod- mutants with helper plasmid pRK2013. SmR TcR transconjugants occurred with a frequency of 5 x 10(-4). The transconjugants were purified and used to inoculate germinated soybean seeds. Seven nodules were obtained in the nodulation experiment. The fast-growing Nod+ SmR TcR Rhizobium fredii strain was isolated from all nodules. Each isolate had acquired a new plasmid with a molecular mass of approximately 51 kb. This recombinant plasmid was transferred to E. coli HB101 by helper pRK2013 at a frequency of 1 x 10(-4). In addition to the vector fragment, all the recombinant plasmids gave 23 kb and 6.5 kb fragments on EcoRI digestion. A DNA-DNA hybridization test with a 32P-labelled nod gene probe (prepared from pRmSL26) confirmed that the 20 kb EcoRI-BamHI DNA fragment of the plasmids exhibited sequence homology with an R. meliloti nod gene probe. PMID:2491321

Zhou, L M; Huang, T W; Gong, H Y; Ning, L F; Cen, Y H

1989-01-01

202

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

203

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

204

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

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

G. Archana

2009-01-01

205

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

OpenAIRE

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 contain...

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

2014-01-01

206

Cytochrome aa3 gene regulation in members of the family Rhizobiaceae: comparison of copper and oxygen effects in Bradyrhizobium japonicum and Rhizobium tropici.  

OpenAIRE

Dithionite-reduced minus ferricyanide-oxidized difference spectra on membranes from Rhizobium tropici (formerly Rhizobium leguminosarum bv. phaseoli) incubated at progressively lower O2 concentrations showed only a slight concomitant decrease in A603, the alpha-peak of cytochrome aa3. In contrast to previous results on Bradyrhizobium japonicum, R. tropici showed no significant O2-mediated reduction in the level of either coxA transcription or cytochrome aa3 activity (as measured by ascorbate-...

Gabel, C.; Bittinger, M. A.; Maier, R. J.

1994-01-01

207

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

Science.gov (United States)

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

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

2013-12-01

208

Les structures et le mobilier du site d’habitat Hallstatt final-La Tène ancienne d'Allaines Mervilliers (Eure-et-Loir Buildings and effects from the hallstatt D-Early La Tène site of Allaines Mervilliers (Eure-et-Loir  

Directory of Open Access Journals (Sweden)

Full Text Available Découverte de structures d’habitat sur poteaux et d’une fosse Hallstatt final-La Tène ancienne dans le cadre d’une opération d’archéologie préventive en 1998, à Allaines Mervilliers (Eure-et-Loir. Il s’agit de deux bâtiments rectangulaires à six trous de poteau, d’un bâtiment rectangulaire à trois nefs et d’un bâtiment circulaire. Ces deux derniers sont inédits pour cette époque en région Centre. Le bâtiment rectangulaire à trois nefs est composé de deux rangées centrales de trois trous de poteau et de deux rangées latérales de quatre trous de poteau. Les trous de poteau centraux présentent un remplissage stratifié dont la couche supérieure a livré l’essentiel de l’abondant mobilier découvert. On décompte par exemple dans les vestiges en céramique 56 individus-vases différents. Le bâtiment circulaire est composé d’une couronne de neuf trous de poteau présentant également un remplissage stratifié. On a découvert moins de mobilier dans cette structure que dans le bâtiment précédent, mais il se singularise aussi par la présence d’ossements humains.The discovery of settlement structureson posts and of a pit Hallstatt D-early La Tène during a rescue archaeology operation in 1998, in Allaines Mervilliers (Eure-et-Loir. It concerned two rectangular buildings of six post holes, a rectangular building in three naves and a circular building. The latter two are new for this period in the Centre region.The rectangular building in three naves consisted of two central rows of three post holes and two lateral rows of four post holes. The central holes of post introduce a stratified fill, the upper layer of which produced the majority of the abundant finds. From the ceramic remains it was estimated that there were fifty-six individuals in different vases. The circular building consisted of a ring of nine post holes also producing a stratified fill. Fewer articles were discovered in this structure than in the previous building, but it too was notable for the presence of human ossuaries.

Diane Casadei

2006-12-01

209

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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. Abstract in english 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 an [...] d 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; Sonia Cristina, Perón; Edilberto Princi, Portugal; Antonio Roberto, Giardini.

210

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  

OpenAIRE

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

211

Regulation of dct genes in the Rhizobium meliloti-alfalfa interaction.  

Science.gov (United States)

In order to support symbiotic N2 fixation, Rhizobium meliloti must be able to utilize the C4-dicarboxylic acids provided by its legume host, alfalfa. These compounds are taken up via a single transport protein, DctA. Transcription from the dctA promoter is positively regulated by the DctB/DctD two-component system. In response to dicarboxylic acids, the transmembrane sensor DctB, activates the transcriptional activator DctD, which together with ?(54) holoenzyme initiates transcription of dctA. In bacteroids an alternative mode of activation has also been implicated in dctA expression and the exact nature of this system remains to be elucidated. Evidence also suggests that expression of the dctA promoter can be influenced negatively by other DNA regulatory proteins. PMID:24415162

Giblin, L; Archdeacon, J; O'Gara, F

1996-03-01

212

NtrBC-dependent expression from the Rhizobium meliloti dctA promoter in Escherichia coli.  

Science.gov (United States)

Effects of the two-component sensor-regulator pairs DctBD and NtrBC upon the expression of a dctA::phoA fusion from Rhizobium meliloti were determined under excess and limiting nitrogen concentrations in Escherichia coli. Results indicated that NtrBC affected transcription from the dctA promoter on a number of regulatory levels and under different physiological conditions in the heterologous host. However, NtrBC-dependent cross-talk was not observed in free-living R. meliloti under the conditions tested. Comparisons of the predicted amino acid sequences of DctD and NtrC from various sources indicated a specific region of the NtrC from rhizobia, which may have diverged from a consensus NtrC/DctD sequence to minimise interference between the two component systems, NtrBC and DctBD. PMID:7781970

Allaway, D; Boesten, B; O'Gara, F

1995-05-15

213

Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea (ureaformaldehyde) as nitrogen source.  

Science.gov (United States)

Methylene ureas (MU) are slow-release nitrogen fertilizers degraded in soil by microbial enzymatic activity. Improved utilization of MU in agricultural production requires more knowledge about the organisms and enzymes responsible for its degradation. A Gram-negative, MU-degrading organism was isolated from a soil in Sacramento Valley, California. The bacterium was identified as Agrobacterium tumefaciens (recently also known as Rhizobium radiobacter) using both genotypic and phenotypic characterization. The pathogenic nature of the organism was confirmed by a bioassay on carrot disks. The MU-hydrolyzing enzyme (MUase) was intracellular and was induced by using MU as a sole source of nitrogen. The bacterial growth was optimized in NH4Cl, urea, or peptone, whereas the production and specific activity of MUase were maximized with either NH4Cl or urea as a nitrogen source. The result has a practical significance, demonstrating a potential to select for this plant pathogen in soils fertilized with MU. PMID:15105883

Koivunen, Marja E; Morisseau, Christophe; Horwath, William R; Hammock, Bruce D

2004-03-01

214

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

2014-09-01

215

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

216

Mutations inducing an active-site aperture in Rhizobium sp. sucrose isomerase confer hydrolytic activity.  

Science.gov (United States)

Sucrose isomerase is an enzyme that catalyzes the production of sucrose isomers of high biotechnological and pharmaceutical interest. Owing to the complexity of the chemical synthesis of these isomers, isomaltulose and trehalulose, enzymatic conversion remains the preferred method for obtaining these products. Depending on the microbial source, the ratio of the sucrose-isomer products varies significantly. In studies aimed at understanding and explaining the underlying molecular mechanisms of these reactions, mutations obtained using a random-mutagenesis approach displayed a major hydrolytic activity. Two of these variants, R284C and F164L, of sucrose isomerase from Rhizobium sp. were therefore crystallized and their crystal structures were determined. The three-dimensional structures of these mutants allowed the identification of the molecular determinants that favour hydrolytic activity compared with transferase activity. Substantial conformational changes resulting in an active-site opening were observed, as were changes in the pattern of water molecules bordering the active-site region. PMID:23385465

Lipski, Alexandra; Watzlawick, Hildegard; Ravaud, Stéphanie; Robert, Xavier; Rhimi, Moez; Haser, Richard; Mattes, Ralf; Aghajari, Nushin

2013-02-01

217

Effect of process parameters on production of a biopolymer by Rhizobium sp.  

Science.gov (United States)

The production of biopolymers by a Rhizobium strain was studied under batch and bioreactor conditions. The best viscosity levels were obtained under low mannitol concentrations as well as low agitation and aeration conditions. Infrared spectra indicated the presence of chemical groups characteristic of microbially produced biopolymers, including C = O and O-acetyl groups. Thermogravimetric analysis showed the characteristic degradation profiles of the exopolysaccharide produced (T(onset) = 290degreesC). The experimental design showed that a low substrate concentration (10.0 g/L), and low aeration (0.2 vvm) and agitation (200 rpm) levels should be used. The maximum yield of the process was a Yp/s (g/g) of 0.19 +/- 0.1, obtained under optimized conditions. PMID:15054283

Duta, Flávia Pereira; De França, Francisca Pessôa; Sérvulo, Eliana Flávia Camporese; De Almeida Lopes, Léa Maria; Da Costa, Antonio Carlos Augusto; Barros, Ana

2004-01-01

218

[luxAB genes as marker for detecting Rhizobium fredii HN01 nodulation functions].  

Science.gov (United States)

A suicide plasmid pHNC3 which contains Tn5-luxAB was transferred into Rhizobium fredii HN01 by the help of pRK2013. Then Tn5-luxAB inserted on the genome of HN01 and gave luminescence activity. The luminescence colonies were picked up and the Eckhardt gel was performed for plasmids profile detection. The location of Tn5-luxAB on the genome was determined using the luxAB as probe. The colonies which were marked by Tn5-luxAB on the chromosome and different plasmids of HN01 were chosen for pot experiment, and a chromosome labelled strain HN01LC02 was detected by soil pot experiment. The detections included the nodulation occupancy and the luminescent nodules distribution on the root system formed by the luxAB-marked rhizobia. PMID:12549335

Mo, C; Qin, Y; Zhou, J; Li, F

1998-06-01

219

Novel high- and low-copy stable cosmids for use in Agrobacterium and Rhizobium.  

Science.gov (United States)

Presented are a set of cosmids based on the unit copy Agrobacterium plasmid, pTAR, and the high-copy-number mutant plasmid, pUCD500, of pTiC58. The addition of a par function derived from pTAR to the vectors allowed them to be stably maintained throughout the cell population in the absence of selective pressure. These vectors, designed for Agrobacterium and Rhizobium, also work in Escherichia coli. The vectors can be cotransferred to Rhizobiaceae from E. coli with the helper plasmid, pRK2013. The pTiC58 origin containing vectors, pUCD1000 and pUCD1001 were found to be incompatible with a 250-kb plasmid harbored by R. meliloti RM102Z1. RM102Z1(pUCD1000) was still capable of nodulating roots in alfalfa. PMID:3906714

Gallie, D R; Novak, S; Kado, C I

1985-09-01

220

Accidentologie, usage et représentations des deux-roues motorisés: Rapport de synthèse final du projet "2RM". 2ème partie : Présentation des travaux  

OpenAIRE

Ce rapport fait état des travaux réalisés dans les différentes tâches qui composaient cette étude : Les défaillances d'interaction dans les accidents impliquant un Deux-roues motorisé. La dynamique des accidents : comportement du couple conducteur-deux-roues motorisé en situation d'urgence. Analyse comparative de procédures d'accidents mortels et non mortels. Etudes détaillées d'accident et prospectives. Observation des situations de trafic. Etude sociologique des représentations

Elslande, P.; Perrin, Christophe; Hermitte, T.; Page, Y.; Engel, R.

2008-01-01

221

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

222

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

223

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  

OpenAIRE

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 fija...

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

2010-01-01

224

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

225

Stimulation of indoleacetic acid production in a Rhizobium isolate of Vigna mungo by root nodule phenolic acids.  

Science.gov (United States)

The influence of endogenous root nodules phenolic acids on indoleacetic acid (IAA) production by its symbiont (Rhizobium) was examined. The root nodules contain higher amount of IAA and phenolic acids than non-nodulated roots. Presence of IAA metabolizing enzymes, IAA oxidase, peroxidase, and polyphenol oxidase indicate the metabolism of IAA in the nodules and roots. Three most abundant endogenous root nodule phenolic acids (protocatechuic acid, 4-hydroxybenzaldehyde and p-coumaric acid) have been identified and their effects on IAA production by the symbiont have been studied in L-tryptophan supplemented yeast extract basal medium. Protocatechuic acid (1.5 microg ml(-1)) showed maximum stimulation (2.15-fold over control) of IAA production in rhizobial culture. These results indicate that the phenolic acids present in the nodule might serve as a stimulator for IAA production by the symbiont (Rhizobium). PMID:19151966

Mandal, Santi M; Mandal, Santi; Mandal, Mahitosh; Das, Amit K; Das, Amit; Pati, Bikas R; Pati, Bikas; Ghosh, Ananta K; Ghosh, Ananta

2009-04-01

226

Accumulation of Soybean Lectin-Binding Polysaccharide During Growth of Rhizobium japonicum as Determined by Hemagglutination Inhibition Assay  

OpenAIRE

A hemagglutination inhibition assay was used to estimate the presence of soybean lectin-binding polysaccharide in whole culture, culture supernatant, and isolated exopolysaccharide of Rhizobium japonicum USDA 138. The occurrence of 0.1 to 0.2 ?g of lectin-binding polysaccharide could be detected within 2 h with a 0.5-ml total sample. Lectin-binding polysaccharide was detected in all preparations during both exponential and stationary growth phases. The formation of lectin-binding polysacchar...

Tsien, H. C.; Schmidt, E. L.

1980-01-01

227

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

Science.gov (United States)

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

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

2012-01-01

228

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

OpenAIRE

Populations of Rhizobium leguminosarum biovar viciae were sampled from two bulk soils, rhizosphere, and nodules of host legumes, fava bean (Vicia faba) and pea (Pisum sativum) grown in the same soils. Additional populations nodulating peas, fava beans, and vetches (Vicia sativa) grown in other soils and fava bean-nodulating strains from various geographic sites were also analyzed. The rhizobia were characterized by repetitive extragenomic palindromic-PCR fingerprinting and/or PCR-restriction ...

Laguerre, Gise?le; Louvrier, Philippe; Allard, Marie-reine; Amarger, Noe?lle

2003-01-01

229

Effect of Rhizobium Inoculants and Reproductive Growth Stages on Shoot Biomass and Yield of Soybean (Glycine max (L. Merril  

Directory of Open Access Journals (Sweden)

Full Text Available The experiment was conducted during the 2012 farming season in the agricultural experimental field of the University for Development Studies, Nyankpala in the Northern Region of Ghana. The objective of the study was to determine the influence of Rhizobium inoculants and growth stages on shoot dry matter and grain yield of soybean. Two levels of inoculation regimes (inoculation (+In and uninoculation (-In were combined with four sampling developmental stages (vegetative stage, flowering stage, pod stage and physiological maturity stage. The experimental design was a 2 x 4 factorial laid out in a Randomized Complete Block Design with eight treatments at four replications. Plants inoculated with Rhizobium and harvested at flowering stage recorded significantly higher fresh and dry shoot matter of 74.2 g and 23.57 g per plant, respectively as compared to plants that were not inoculated and harvested at the physiological maturity stage. The latter recorded the lowest fresh and dry shoot weights of 45.2 g and 15.5 g per plant, respectively. Rhizobium inoculation significantly increased grain yield (1262 kg/ha compared to the yield obtained in the uninoculated treatments (1044 kg/ha. Grain yield positively correlated with plant height, plant stand, canopy spread, number and weight of nodules, number and weight of pods. From the results, it is recommended that soybean seeds should be inoculated with Rhizobium before planting in order to obtain higher grain yields. It is also recommended that for higher nodule numbers, which can be a good indication of higher N2 fixation if the nodules are effective, and higher shoot biomass which is required for effective green manuring, soybean should be harvested at full pod stage.

S. lamptey

2014-04-01

230

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

OpenAIRE

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

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

2010-01-01

231

Mimosine, a Toxin Present in Leguminous Trees (Leucaena spp.), Induces a Mimosine-Degrading Enzyme Activity in Some Rhizobium Strains  

OpenAIRE

Thirty-seven Rhizobium isolates obtained from the nodules of leguminous trees (Leucaena spp.) were selected on the basis of their ability to catabolize mimosine, a toxin found in large quantities in the seeds, foliage, and roots of plants of the genera Leucaena and Mimosa. A new medium containing mimosine as the sole source of carbon and nitrogen was used for selection. The enzymes of the mimosine catabolic pathway were inducible and were present in the soluble fraction of the cell extract of...

Soedarjo, Muchdar; Hemscheidt, Thomas K.; Borthakur, Dulal

1994-01-01

232

Legume-bacterium (Rhizobium) Association-Symbiosis, A Marriage of Convenience, Necessary Evil or Bacterium Taken Hostage by the Legume  

OpenAIRE

Nitrogen (N) is the key nutrient element, limiting crop production under most situations. A major reason for insufficient N supplies being its presence in soil in organic forms which must be mineralized before being used by the plants. However, leguminous plants are equipped with the facility to acquire a major portion of N directly from atmospheric N2 through bacterial fixation (reduction). The bacteria (Rhizobium spp) reside inside the special structures on plant roots i.e...

Azam, F.

2001-01-01

233

Extracellular Glycanases of Rhizobium leguminosarum Are Activated on the Cell Surface by an Exopolysaccharide-Related Component  

OpenAIRE

Rhizobium leguminosarum secretes two extracellular glycanases, PlyA and PlyB, that can degrade exopolysaccharide (EPS) and carboxymethyl cellulose (CMC), which is used as a model substrate of plant cell wall cellulose polymers. When grown on agar medium, CMC degradation occurred only directly below colonies of R. leguminosarum, suggesting that the enzymes remain attached to the bacteria. Unexpectedly, when a PlyA-PlyB-secreting colony was grown in close proximity to mutants unable to produce ...

Zorreguieta, Angeles; Finnie, Christine; Downie, J. Allan

2000-01-01

234

Attenuation of Symbiotic Effectiveness by Rhizobium meliloti SAF22 Related to the Presence of a Cryptic Plasmid  

OpenAIRE

Several wild-type strains of Rhizobium meliloti isolated from alfalfa nodules exhibited different plasmid profiles, yet did not differ in growth rate in yeast-mannitol medium, utilization of 43 different carbon sources, intrinsic resistance to 14 antibiotics, or detection of 16 enzyme activities. In contrast, three measures of effectiveness in symbiotic nitrogen fixation with alfalfa (shoot length, dry weight, and nitrogen content) indicated that R. meliloti SAF22, whose plasmid profile diffe...

Velazquez, E.; Mateos, P. F.; Pedrero, P.; Dazzo, F. B.; Martinez-molina, E.

1995-01-01

235

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

OpenAIRE

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

236

Rhizobium leguminosarum bv. viciae populations in soils with increasing heavy metal contamination: abundance, plasmid profiles, diversity and metal tolerance  

OpenAIRE

Populations of Rhizobium leguminosarum bv. viciae were investigated from plots of a long-term sewage sludge experiment in Braunschweig, Germany, which represented a gradient of increasing metal contamination. The number of R. leguminosarum bv. viciae decreased from 105 cells g¿1 soil in uncontaminated plots to between 7 and 102 cells g¿1 soil with increasing Zn concentration (from 50 to 400 mg kg¿1). Rhizobia were isolated from nodules of Vicia hirsuta inoculated with dilutions of soil fro...

Lakzian, A.; Murphy, P.; Turner, A.; Beynon, J. L.; Giller, K. E.

2002-01-01

237

Exploitation de la vague 3 de l'enquête Marc. Volume 1 : croyances vis à vis de la vitesse et risque routier. Rapport final -version courte  

OpenAIRE

Un des objectifs de l'enquête prospective MARC est d'expliquer, en se référant principalement au Modèle du Comportement Planifié, l'intention des jeunes automobilistes de conduire à plus de 110 km/h sur route limitée à 90 km/h. L'enquête a été menée à trois reprises entre 2003 et 2005. Nous observons au fur et à mesure des vagues d'interrogation que les jeunes automobilistes ont l'intention de conduire moins vite. Cette diminution de la vitesse s'explique essentiellement par un ...

Delhomme, P.; Fernandez, V.; Paran, F.

2008-01-01

238

Production of gibberellins and indole-3-acetic acid by Rhizobium phaseoli in relation to nodulation of Phaseolus vulgaris roots.  

Science.gov (United States)

Similar ranges of gibberellins (GAs) were detected by high-performance liquid chromatography (HPLC)-immunoassay procedures in ten cultures of wild-type and mutant strains of Rhizobium phaseoli. The major GAs excreted into the culture medium were GA1 and GA4. These identifications were confirmed by combined gas chromatographymass spectrometry. The HPLC-immunoassays also detected smaller amounts of GA9- as well as GA20-like compounds, the latter being present in some but not all cultures. In addition to GAs, all strains excreted indole-3-acetic acid (IAA) but there was no obvious relationship between the amounts of GA and IAA that accumulated. The Rhizobium strains studied included nod (-) and fix (-) mutants, making it unlikely that the IAA- and GA-biosynthesis genes are closely linked to the genes for nodulation and nitrogen fixation.The HPLC-immunoassay analyses showed also that nodules and non-nodulated roots of Phaseolus vulgaris L. contained similar spectra of GAs to R. phaseoli culture media. The GA pools in roots and nodules were of similar size, indicating that Rhizobium does not make a major contribution to the GA content of the infected tissue. PMID:24221937

Atzorn, R; Crozier, A; Wheeler, C T; Sandberg, G

1988-10-01

239

Two rhizobacterial strains, individually and in interactions with Rhizobium sp., enhance fusarial wilt control, growth, and yield in pigeon pea.  

Science.gov (United States)

A Pseudomonas aeruginosa strain, RRLJ 04, and a Bacillus cereus strain, BS 03, were tested both individually and in combination with a Rhizobium strain, RH 2, for their ability to enhance plant growth and nodulation in pigeon pea (Cajanus cajan L.) under gnotobiotic, greenhouse and field conditions. Both of the rhizobacterial strains exhibited a positive effect on growth in terms of shoot height, root length, fresh and dry weight, nodulation and yield over the non-treated control. Co-inoculation of seeds with these strains and Rhizobium RH 2 also reduced the number of wilted plants, when grown in soil infested with Fusarium udum. Gnotobiotic studies confirmed that the suppression of wilt disease was due to the presence of the respective PGPR strains. Seed bacterization with drug-marked mutants of RRLJ 04 and BS 03 confirmed their ability to colonize and multiply along the roots. The results suggest that co-inoculation of these strains with Rhizobium strain RH 2 can be further exploited for enhanced growth, nodulation and yield in addition to control of fusarial wilt in pigeon pea. PMID:25224506

Dutta, Swarnalee; Morang, Pranjal; Kumar S, Nishanth; Dileep Kumar, B S

2014-09-01

240

Une fosse du Bronze final IIb dans le Val d’Orléans à Sandillon (Loiret : données archéologiques et contexte environnemental A Late Bronze Age pit IIb in the Val d’Orléans at Sandillon (Loiret: archaeological data and environmental context  

Directory of Open Access Journals (Sweden)

Full Text Available Un diagnostic archéologique réalisé en 2004 à Sandillon (Loiret a permis la découverte d’une occupation du Bronze final IIb dans la plaine alluviale de la Loire. Les structures sont peu nombreuses, mais une fosse se distingue par un ensemble céramique exceptionnel par sa richesse, sa conservation et la présence de formes encore inconnues en région Centre. Ce corpus céramique, corrélé par une datation par radiocarbone, offre désormais un jalon fiable pour la région. Par ailleurs, ces vestiges ont pu être replacés dans leur environnement immédiat grâce à une étude géomorphologique et à l’analyse des restes carpologiques contenus dans la fosse. Ainsi, le croisement des données permet de tenter une approche paléo environnementale sur une occupation en contexte fluviatile et de préciser les relations entre l’homme et son milieu durant cette période chronologique.An archaeological diagnostic carried out in 2004 at Sandillon (Loiret enabled the discovery of a final Bronze Age IIb occupation in the alluvial Loire valley. There are few structures but one pit is noteworthy for a ceramic collection, exceptional in its abundance, its preservation and the presence of previously unknown forms in the Centre region. This ceramic corpus, dated by radiocarbon, henceforth provides a reliable standard for the region. Moreover, these relics could be set in their immediate environment thanks to a geomorphological study and to the analysis of carpological remains contained in the pit. So, the crossing of data allows us to attempt an environmental paleolithic approach to an occupation in a freshwater context and to clarify the relationship between man and his environment in this chronological period.

Hélène Froquet

2008-06-01

241

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

Energy Technology Data Exchange (ETDEWEB)

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

Lamy, C.

2005-07-01

242

Relationships between C4 dicarboxylic acid transport and chemotaxis in Rhizobium meliloti.  

Science.gov (United States)

The relationship between chemotaxis and transport of C4 dicarboxylic acids was analyzed with Rhizobium meliloti dct mutants defective in one or all of the genes required for dicarboxylic acid transport. Succinate, malate, and fumarate were moderately potent chemoattractants for wild-type R. meliloti and appeared to share a common chemoreceptor. While dicarboxylate transport is inducible, taxis to succinate was shown to be constitutive. Mutations in the dctA and dctB genes both resulted in the reduction, but not elimination, of chemotactic responses to succinate, indicating that transport via DctA or chemosensing via DctB is not essential for C4 dicarboxylate taxis, although they appear to contribute to it. Mutations in dctD and rpoN genes did not affect taxis to succinate. Aspartate, which is also transported by the dicarboxylate transport system, elicited strong chemotactic responses via a chemoreceptor distinct from the succinate-malate-fumarate receptor. Taxis to aspartate was unaltered in dctA and dctB mutants but was considerably reduced in both dctD and rpoN mutants, indicating that aspartate taxis is strongly dependent on elements responsible for transcriptional activation of dctA. Methylation and methanol release experiments failed to show a significant increase in methyl esterification of R. meliloti proteins in response to any of the attractants tested. PMID:8468289

Robinson, J B; Bauer, W D

1993-04-01

243

Nitrogenase activity in Trifolium subterraneum L. in relation to the uptake of nitrate ions. [Rhizobium trifolii  

Energy Technology Data Exchange (ETDEWEB)

An experiment was conducted to test the hypothesis that, when nitrogenase and nitrate reductase both contribute to the nitrogen nutrition of a nodulated legume, nitrogenase activity is inversely proportional to the rate of accumulation of organic nitrogen derived from the reduction of nitrate. Trifolium subterraneum L. plants, inoculated with Rhizobium trifolii and sown as small swards, were allowed to establish a closed canopy and steady rates of growth, dinitrogen fixation, and nitrogen accumulation. Swards were then supplied with nutrient solutions of 0, 0.5, 1.0, or 2.5 mM NO/sub 3//sup -/ with a 29.69% enrichment of /sup 15/N and allowed to grow for a further 33 days. Harvests were made to measure dry weight, nitrogen accumulation, /sup 15/N accumulation, NO/sub 3//sup -/ content and nitrogenase activity by acetylene reduction assay. Since the /sup 15/N of the plant organic matter could have been derived only from the NO/sub 3//sup -/ of the nutrient solution, its rate of accumulation provided a measure of the rate of NO/sub 3//sup -/ reduction. It was found that as this rate increased in response to external NO/sub 3//sup -/ concentration the rate of nitrogenase activity decreased proportionately. It is concluded that the reduction of nitrate and the reduction of dinitrogen act in a complementary manner to supply a plant with organic nitrogen for growth.

Silsbury, J.H.

1987-07-01

244

Escherichia coli BdcA controls biofilm dispersal in Pseudomonas aeruginosa and Rhizobium meliloti  

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Full Text Available Abstract Background Previously we showed that BdcA controls Escherichia coli biofilm dispersal by binding the ubiquitous bacterial signal cyclic diguanylate (c-di-GMP; upon reducing the concentration of c-di-GMP, the cell shifts to the planktonic state by increasing motility, decreasing aggregation, and decreasing production of biofilm adhesins. Findings Here we report that BdcA also increases biofilm dispersal in other Gram-negative bacteria including Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhizobium meliloti. BdcA binds c-di-GMP in these strains and thereby reduces the effective c-di-GMP concentrations as demonstrated by increases in swimming motility and swarming motility as well as by a reduction in extracellular polysaccharide production. We also develop a method to displace existing biofilms by adding BdcA via conjugation from E. coli in mixed-species biofilms. Conclusion Since BdcA shows the ability to control biofilm dispersal in diverse bacteria, BdcA has the potential to be used as a tool to disperse biofilms for engineering and medical applications.

Wood Thomas K

2011-10-01

245

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

246

Enzymatic tailoring of ornithine in the biosynthesis of the Rhizobium cyclic trihydroxamate siderophore vicibactin.  

Science.gov (United States)

To acquire iron, the N(2)-fixing, symbiotic bacterium Rhizobium sp. produce the cyclic trihydroxamate siderophore vicibactin, containing a 30-membered trilactone scaffold. Herein we report the overproduction and purification of the six proteins VbsACGOLS in the bacterial host Escherichia coli and the reconstitution of the biosynthesis of vicibactin from primary metabolites. The flavoprotein VbsO acts as a pathway-initiating l-ornithine N(5)-hydroxylase, followed by VbsA, which transfers (R)-3-hydroxybutyryl- from the CoA thioester to N(5)-hydroxyornithine to yield N(5)-((R)-3-hydroxybutyryl)-N(5)-hydroxy-l-ornithine. VbsL is a PLP-dependent epimerase acting at C(2) of the 10 atom monomer unit. VbsS, a nonribosomal peptide synthetase free-standing module, then activates N(5)-((R)-3-hydroxybutyryl)-N(5)-hydroxy-d-ornithine as the AMP anhydride on the way to cyclotrimerization to the vicibactin scaffold. The last step, tris-acetylation of the C(2) amino group of desacetyl-d-vicibactin to the mature siderophore vicibactin, is catalyzed distributively by VbsC, using three molecules of acetyl-CoA. PMID:19778043

Heemstra, John R; Walsh, Christopher T; Sattely, Elizabeth S

2009-10-28

247

Rhizobium cellulase CelC2 is essential for primary symbiotic infection of legume host roots.  

Science.gov (United States)

The rhizobia-legume, root-nodule symbiosis provides the most efficient source of biologically fixed ammonia fertilizer for agricultural crops. Its development involves pathways of specificity, infectivity, and effectivity resulting from expressed traits of the bacterium and host plant. A key event of the infection process required for development of this root-nodule symbiosis is a highly localized, complete erosion of the plant cell wall through which the bacterial symbiont penetrates to establish a nitrogen-fixing, intracellular endosymbiotic state within the host. This process of wall degradation must be delicately balanced to avoid lysis and destruction of the host cell. Here, we describe the purification, biochemical characterization, molecular genetic analysis, biological activity, and symbiotic function of a cell-bound bacterial cellulase (CelC2) enzyme from Rhizobium leguminosarum bv. trifolii, the clover-nodulating endosymbiont. The purified enzyme can erode the noncrystalline tip of the white clover host root hair wall, making a localized hole of sufficient size to allow wild-type microsymbiont penetration. This CelC2 enzyme is not active on root hairs of the nonhost legume alfalfa. Microscopy analysis of the symbiotic phenotypes of the ANU843 wild type and CelC2 knockout mutant derivative revealed that this enzyme fulfils an essential role in the primary infection process required for development of the canonical nitrogen-fixing R. leguminosarum bv. trifolii-white clover symbiosis. PMID:18458328

Robledo, M; Jiménez-Zurdo, J I; Velázquez, E; Trujillo, M E; Zurdo-Piñeiro, J L; Ramírez-Bahena, M H; Ramos, B; Díaz-Mínguez, J M; Dazzo, F; Martínez-Molina, E; Mateos, P F

2008-05-13

248

Effect of leguminous lectins on the growth of Rhizobium tropici CIAT899.  

Science.gov (United States)

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. PMID:23685936

de Vasconcelos, Mayron Alves; Cunha, Cláudio Oliveira; Arruda, Francisco Vassiliepe Sousa; Carneiro, Victor Alves; Bastos, Rafaela Mesquita; Mercante, Fábio Martins; do Nascimento, Kyria Santiago; Cavada, Benildo Sousa; dos Santos, Ricardo Pires; Teixeira, Edson Holanda

2013-01-01

249

Effect of Leguminous Lectins on the Growth of Rhizobium tropici CIAT899  

Directory of Open Access Journals (Sweden)

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

250

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

Directory of Open Access Journals (Sweden)

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

251

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

252

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

Science.gov (United States)

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, nodulation 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 PMID:15093001

Suominen, L; Jussila, M M; Mäkeläinen, K; Romantschuk, M; Lindström, K

2000-02-01

253

Survival of several Rhizobium/Bradyrhizobium strains on different inoculant formulations and inoculated seeds.  

Science.gov (United States)

The effect of a variety factors on the survival of several rhizobia strains on inoculants and inoculated seeds has been evaluated. Since the rhizobia strains showed different cell-density-evolution patterns on peat-based inoculants and on inoculated seeds, several inoculant formulations with highly effective Rhizobium/Bradyrhizobium strains (for Lupinus, Hedysarum, Phaseolus and Glycine max.) were monitored under the following storage conditions: (a) the inoculants were kept refrigerated (at 4 degrees C), or (b) at room temperature (25 degrees C). The effect of water content (30-50%, w/w) in the inoculants as well as that of several seed-coating adhesives were also investigated. Alternative carriers including perlite and vermiculite were tested. For all of the strains, survival on sterile peat-based inoculants was higher than on the corresponding unsterile peat formulation; for the latter, refrigerated storage conditions are recommended to ensure high bacterial densities. The water content of the inoculants had a differential effect on strain survival depending on the sterility of the peat, such that a high water content was more detrimental when unsterilized peat was employed. The best adherent for rhizobia survival was a gum arabic/water solution. Perlite was as effective as peat in maintaining a high population of rhizobia, at least for 6 months of storage. PMID:12180784

Temprano, F J; Albareda, M; Camacho, M; Daza, A; Santamaría, C; Rodríguez-Navarro, D Nombre

2002-06-01

254

The replicator region of the Rhizobium leguminosarum cryptic plasmid pRL8JI.  

Science.gov (United States)

The replicator region of the cryptic plasmid pRL8JI from Rhizobium leguminosarum strain 3841 was cloned and sequenced. The recombinant plasmid (pYK3) was selected by function from a partial EcoRI library of total DNA cloned in pSUP202 and shows incompatibility with plasmid pRL8JI when conjugated into R. leguminosarum strains 3841 and its derivative 1062. The cloned insert (approximately 10.5 kb) comprises five EcoRI fragments none of which confers replicative stability when cloned individually. A single 5.0-kb BamHI fragment, that spans all five EcoRI fragments and confers replicative stability on pSUP202 in R. leguminosarum, has been sequenced. This replicator region shows organisational and sequence similarity to the replicator regions of the Agrobacterium plasmids pTiB6S3 and pRiA4b. It has three open reading frames (repA, repB, repC) and a conserved intergenic sequence. PMID:8566712

Turner, S L; Young, J P

1995-11-01

255

Role of Microniches in Protecting Introduced Rhizobium leguminosarum biovar trifolii against Competition and Predation in Soil.  

Science.gov (United States)

The importance of microniches for the survival of introduced Rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate Bodo saltans, precultured on rhizobial cells. The introduced organisms were enumerated in different soil fractions by washing the soil, using a standardized washing procedure. With this method, free organisms and organisms associated with soil particles or aggregates >50 mum were separated. The total number of rhizobia was influenced slightly (silt loam) or not at all (loamy sand) by the recolonization with microorganisms or by the addition of flagellates alone. However, when both flagellates and microorganisms were present, numbers of rhizobia decreased drastically. This decrease was more than the sum of both effects separately. Nevertheless, populations of rhizobia were still higher than in natural soil. In the presence of flagellates, higher percentages of rhizobia and other microorganisms were associated with soil particles or aggregates >50 mum than in the absence of flagellates. In recolonized soils, however, the percentages of particle-associated rhizobia were lower than in soils not recolonized previous to inoculation. Thus, the presence of other microorganisms hindered rhizobial colonization of sites where they are normally associated with soil particles or aggregates. PMID:16348125

Postma, J; Hok-A-Hin, C H; van Veen, J A

1990-02-01

256

Bacterial genospecies that are not ecologically coherent: population genomics of Rhizobium leguminosarum  

Science.gov (United States)

Biological species may remain distinct because of genetic isolation or ecological adaptation, but these two aspects do not always coincide. To establish the nature of the species boundary within a local bacterial population, we characterized a sympatric population of the bacterium Rhizobium leguminosarum by genomic sequencing of 72 isolates. Although all strains have 16S rRNA typical of R. leguminosarum, they fall into five genospecies by the criterion of average nucleotide identity (ANI). Many genes, on plasmids as well as the chromosome, support this division: recombination of core genes has been largely within genospecies. Nevertheless, variation in ecological properties, including symbiotic host range and carbon-source utilization, cuts across these genospecies, so that none of these phenotypes is diagnostic of genospecies. This phenotypic variation is conferred by mobile genes. The genospecies meet the Mayr criteria for biological species in respect of their core genes, but do not correspond to coherent ecological groups, so periodic selection may not be effective in purging variation within them. The population structure is incompatible with traditional ‘polyphasic taxonomy? that requires bacterial species to have both phylogenetic coherence and distinctive phenotypes. More generally, genomics has revealed that many bacterial species share adaptive modules by horizontal gene transfer, and we envisage a more consistent taxonomic framework that explicitly recognizes this. Significant phenotypes should be recognized as ‘biovars' within species that are defined by core gene phylogeny. PMID:25589577

Kumar, Nitin; Lad, Ganesh; Giuntini, Elisa; Kaye, Maria E.; Udomwong, Piyachat; Shamsani, N. Jannah; Young, J. Peter W.; Bailly, Xavier

2015-01-01

257

Production of extracellular biopolymers and identification of intracellular proteins and Rhizobium tropici.  

Science.gov (United States)

The objective of this study was to identify species of rhizobia (from the IPA 403 and IPA 49 isolates), to assess the physico-chemical characteristics of the biopolymers produced by these rhizobia and to determine the soluble intracellular proteins that are present in these rhizobia. The polysaccharides containing acetyl and pyruvic acid groups that were produced by different strains that had been cultivated in yeast extract mannitol (YEM) medium for 132, 144, and 168 h were evaluated for yield, viscosity, and concentration. Based on the analysis of their partial 16S rDNA sequences, both isolates were identified as Rhizobium tropici. The polymers produced in liquid YEM medium were recovered, dried and weighed to determine culture yield. Soluble intracellular proteins were identified through the techniques of 2D-PAGE and mass spectrometry for cultures that were cultivated for 168 h. The largest biopolymer yield and the highest viscosity and concentration of acetyl and pyruvic acids were obtained from the IPA 403 isolate after 168 h of culture. The proteins that were identified for the CIAT 899 isolate included elongation factor TU, a chaperone; GroE/GroEs and a putative glycosyltransferase, all of which catalyze the production of polysaccharides. For the IPA 403 strain, dinitrogenase and nitrogenase iron proteins were found. In the IPA 49 strain, glyceraldehyde-3-phosphate dehydrogenase was found along with two other proteins, the beta subunit of an electron-transferring flavoprotein and a dehydrogenase. PMID:22941435

Oliveira, José; Figueiredo, Marcia; Silva, Marcia; Malta, Marília; Vendruscolo, Claire; Almeida, Hélio

2012-12-01

258

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

259

Repeated sequences similar to insertion elements clustered around the nif region of the Rhizobium japonicum genome.  

Science.gov (United States)

Two different repeated sequences (RSs) were discovered in the Rhizobium japonicum genome: RSRj alpha is 1126 base pairs long and is repeated 12 times; RSRj beta is approximately 950 base pairs long and is repeated at least 6 times. Their arrangement in root nodule bacteroid DNA is the same as in DNA from bacteria grown in culture. Deletion analysis showed that many copies of alpha and beta are clustered around the nitrogenase genes nifDK and nifH, or, in general, they are found within a genomic region harboring genes that are nonessential for growth. One copy each of alpha and beta are located upstream of nifDK and are adjacent to each other. Neither of them, however, is involved in the expression of nifDK. Nucleotide sequence analysis of three copies of RS alpha revealed many characteristics of procaryotic insertion sequence elements: potential inverted repeats at their ends, potential target site duplication, and large open reading frames. Despite this, their genomic positions appear to be stable. One possible function of these RSs is in deletion formation probably via recombination between them. Images PMID:2985537

Kaluza, K; Hahn, M; Hennecke, H

1985-01-01

260

The central domain of Rhizobium meliloti NifA is sufficient to activate transcription from the R. meliloti nifH promoter.  

OpenAIRE

The Rhizobium meliloti nifA product (NifA) shares extensive homology in its central region and at its C-terminal end with Rhizobium leguminosarum DctD and with NtrC from several species. All three proteins are transcriptional activators of NtrA (RpoN)-RNA polymerase-dependent promoters. Several large deletions of R. meliloti NifA were constructed to investigate the role of the conserved and divergent domains of NifA in transcriptional activity and posttranscriptional regulation by oxygen. The...

Huala, E.; Ausubel, F. M.

1989-01-01

261

Involvement of both cellulose fibrils and a Ca2+-dependent adhesin in the attachment of Rhizobium leguminosarum to pea root hair tips.  

OpenAIRE

We have previously described an assay for the attachment of Rhizobium bacteria to pea root hair tips (cap formation) which was used as a model to study the attachment step in the nodulation process. Under all conditions tested, a positive correlation was observed between the percentage of fibrillated cells and the ability of these bacteria to form caps and to adhere to glass, suggesting that fibrils play a role in the attachment of Rhizobium leguminosarum to pea root hair tips and to glass (G...

Smit, G.; Kijne, J. W.; Lugtenberg, B. J.

1987-01-01

262

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

OpenAIRE

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

263

Binary conjugational transfer system of vectors pRK290 and pLAFRI is proficient both ways between Escherichia coli and Rhizobium.  

Science.gov (United States)

Wide host range vector plasmids pRK290 and pLAFRI carrying genomic fragments of Rhizobium are transferable both ways between R. meliloti and R. leguminosarum cells on the one hand and to E. coli cells on the other, in triparental matings involving E. coli cells carrying pRK2013, the helper for Tra functions to the vector plasmids. The vector plasmids pRK290 and pLAFRI can be employed for recovering clones harbored by R. leguminosarum and R. meliloti by transfer to Rhizobium cells by direct matings of the library with them. PMID:2279773

Singh, R K; Singh, A; Misra, A K; Khanuja, S P; Narula, R; Kumar, S

1990-10-01

264

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.

2011-12-01

265

Interação entre cultivares, estirpes comerciais de Rhizobium meliloti e fungicidas no incremento da produção de alfafa / Interactions of cultivars, commercial strains of Rhizobium meliloti and fungicides on the production of alfalfa  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A cultura da alfafa (Medicago sativa) é importante para a produção animal, por sua alta qualidade nutritiva, alto potencial de produção e sucesso na fixação de nitrogênio, através da simbiose com o Rhizobium meliloti, dispensando o uso de adubação nitrogenada. Neste trabalho objetivou-se selecionar [...] estirpes comerciais de R. meliloti (SEMIA-116, SEMIA-134 e SEMIA-135) em relação às cultivares de alfafa Flórida 77, Pioneer 5929, CUF 101 e Crioula, e avaliar os fungicidas Iprodione e Thiram em tratamento de semente e solo na cultivar Crioula. Não houve interação entre as estirpes de R. meliloti e as cultivares de alfafa quanto à produção de matéria seca, e as plantas infestadas com a SEMIA-116 apresentaram maior número de nódulos. Houve interações entre os diferentes tipos e doses de fungicidas e as estirpes de R. meliloti testadas. A estirpe SEMIA-116 apresentou superioridade, representada pela maior produção de biomassa e número de nódulos. Pelos resultados obtidos, não se recomenda a inoculação da estirpe SEMIA-135, quando em associação com o fungicida Iprodione, em solo ou semente. Abstract in english The cultivation of alfalfa (Medicago sativa) is not only important because of its nutrient, content, but also for its high productivity and its ability to fix nitrogen through its association with Rhizobium meliloti. To better understand this symbiotic association, the interaction between R. melilot [...] i strains SEMIA-116, SEMIA-134 and SEMIA-135 with different cultivars of alfalfa Florida 77, Pioneer 5929, CUF 101 and Crioula was evaluated. In addition to the above treatments, the fungicides Iprodione and Thiram were used with the cultivar Crioula to study their effects on the alfalfa/Rhizobium interaction. Plants inoculated with SEMIA-116 had a greater number of nodules. However, no significant difference in the production of plant dry matter was observed between the various Rhizobium strains and the alfalfa cultivars tested. In the presence of the tested fungicides, the Crioula/SEMIA-116 association showed superior biomass production and number of nodules. Results obtained in this study suggest that SEMIA-135 should not be used as an inoculum for alfalfa when Iprodione is used either as a soil or seed treatment.

Patrícia Perondi Anchão, Oliveira; Siu Mui, Tsai; Moacyr, Corsi; María Del Pilar, Díaz.

1999-03-01

266

Genomic basis of broad host range and environmental adaptability of Rhizobium tropici CIAT 899 and Rhizobium sp. PRF 81 which are used in inoculants for common bean (Phaseolus vulgaris L.  

Directory of Open Access Journals (Sweden)

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

267

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

268

Crystallization and preliminary X-ray studies of the Rhizobium meliloti DctD two-component receiver domain.  

Science.gov (United States)

The Rhizobium meliloti DctD two-component receiver domain was expressed in Escherichia coli and purified to homogeneity. Crystals were obtained using the hanging-drop vapor-diffusion geometry with ammonium phosphate as the precipitant. The crystals diffract to 2.3 A and exhibit the symmetry of space group I222 or I212121. The unit-cell dimensions are a = 59.0, b = 58.6 and c = 169.8 A. The asymmetric unit contains a dimer and the crystals have a Vm of 2.16 A3 Da-1. PMID:10089524

Staley, M; Zeringue, L C; Kidd, R D; Nixon, B T; Farber, G K

1998-11-01

269

Deduced products of C4-dicarboxylate transport regulatory genes of Rhizobium leguminosarum are homologous to nitrogen regulatory gene products.  

OpenAIRE

We have sequenced two genes dctB and dctD required for the activation of the C4-dicarboxylate transport structural gene dctA in free-living Rhizobium leguminosarum. The hydropathic profile of the dctB gene product (DctB) suggested that its N-terminal region may be located in the periplasm and its C-terminal region in the cytoplasm. The C-terminal region of DctB was strongly conserved with similar regions of the products of several regulatory genes that may act as environmental sensors, includ...

Ronson, C. W.; Astwood, P. M.; Nixon, B. T.; Ausubel, F. M.

1987-01-01

270

Succinoglycan Production by Rhizobium meliloti Is Regulated through the ExoS-ChvI Two-Component Regulatory System  

OpenAIRE

The Rhizobium meliloti exoS gene is involved in regulating the production of succinoglycan, which plays a crucial role in the establishment of the symbiosis between R. meliloti Rm1021 and its host plant, alfalfa. The exoS96::Tn5 mutation causes the upregulation of the succinoglycan biosynthetic genes, thereby resulting in the overproduction of succinoglycan. Through cloning and sequencing, we found that the exoS gene is a close homolog of the Agrobacterium tumefaciens chvG gene, which has bee...

Cheng, Hai-ping; Walker, Graham C.

1998-01-01

271

Identification of Site-Specific Recombination Genes int and xis of the Rhizobium Temperate Phage 16-3  

OpenAIRE

Phage 16-3 is a temperate phage of Rhizobium meliloti 41 which integrates its genome with high efficiency into the host chromosome by site-specific recombination through DNA sequences of attB and attP. Here we report the identification of two phage-encoded genes required for recombinations at these sites: int (phage integration) and xis (prophage excision). We concluded that Int protein of phage 16-3 belongs to the integrase family of tyrosine recombinases. Despite similarities to the cognate...

Semsey, Szabolcs; Papp, Istvan; Buzas, Zsuzsanna; Patthy, Andras; Orosz, Laszlo; Papp, Peter P.

1999-01-01

272

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

OpenAIRE

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...

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

2011-01-01

273

In Rhizobium leguminosarum, NodD represses its own transcription by competing with RNA polymerase for binding sites  

OpenAIRE

We isolated RNA polymerase (RNAP) from Rhizobium leguminosarum, the nitrogen-fixing symbiont of peas and Vicia. Its 91 kDa subunit, which is homologous to ?70 of Escherichia coli RNAP, is necessary for transcription of the regulatory nodD gene, which in the presence of certain flavonoids induces transcription of other nod genes that are needed for the early steps of infection. We also show that negative autoregulation of nodD was achieved through competition between RNAP and NodD for their r...

Hu, Hailiang; Liu, Songtao; Yang, Yang; Chang, Weizhong; Hong, Guofan

2000-01-01

274

Legume-bacterium (Rhizobium Association-Symbiosis, A Marriage of Convenience, Necessary Evil or Bacterium Taken Hostage by the Legume  

Directory of Open Access Journals (Sweden)

Full Text Available Nitrogen (N is the key nutrient element, limiting crop production under most situations. A major reason for insufficient N supplies being its presence in soil in organic forms which must be mineralized before being used by the plants. However, leguminous plants are equipped with the facility to acquire a major portion of N directly from atmospheric N2 through bacterial fixation (reduction. The bacteria (Rhizobium spp reside inside the special structures on plant roots i.e., nodules and reduce atmospheric N at the expense of C supplied by the plant. This paper presents an analysis of the nature of association between the legume and bacterium.

F. Azam

2001-01-01

275

Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor  

OpenAIRE

Rhizobium leguminosarum is a soil bacterium that infects root hairs and induces the formation of nitrogen-fixing nodules on leguminous plants. Light, oxygen, and voltage (LOV)-domain proteins are blue-light receptors found in higher plants and many algae, fungi, and bacteria. The genome of R. leguminosarum bv. viciae 3841, a pea-nodulating endosymbiont, encodes a sensor histidine kinase containing a LOV domain at the N-terminal end (R-LOV-HK). R-LOV-HK has a typical LOV domain absorption spec...

Bonomi, Herna?n R.; Posadas, Diana M.; Paris, Gasto?n; Carrica, Mariela Del Carmen; Frederickson, Marcus; Pietrasanta, Li?a Isabel; Bogomolni, Roberto A.; Zorreguieta, Angeles; Goldbaum, Fernando A.

2012-01-01

276

Rhizobium meliloti suhR suppresses the phenotype of an Escherichia coli RNA polymerase sigma 32 mutant.  

OpenAIRE

sigma 32, the product of the Escherichia coli rpoH locus, is an alternative RNA polymerase sigma factor utilized to express heat shock genes upon a sudden rise in temperature. E. coli K165 [rpoH165(Am) supC(Ts)] is temperature sensitive for growth and does not induce heat shock protein synthesis. We have isolated a locus from Rhizobium meliloti called suhR that allows E. coli K165 to grow at high temperature and induce heat shock protein synthesis. R. meliloti suhR mutants were viable and sym...

Bent, A. F.; Signer, E. R.

1990-01-01

277

Effect of Cobalt, Rhizobium and Phosphobacterium Inoculations on Growth, Yield, Quality and Nutrient Uptake of Summer Groundnut (Arachis hypogaea)  

OpenAIRE

A field experiment was carried out on the neutral soil of Student’s Instructional Farm, Barajaguli, B. C. K. V., Nadia, West Bengal with groundnut during pre-kharif season (Feb-June) of 2001, 2002 and 2003. It revealed that in increasing plant height (cm), no. of branches per plant, leaf area index (LAI), dry matter accumulation (gm per m2) and no. and dry weight (gm) of nodules per plant at different dates of observation, Rhizobium was more effective than phosphobacterium. Again it ...

Basu, T. K.

2010-01-01

278

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

Directory of Open Access Journals (Sweden)

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

279

Rhizobium sp. strain NGR234 and R. fredii USDA257 share exceptionally broad, nested host ranges.  

Science.gov (United States)

Genetically, Rhizobium sp. strain NGR234 and R. fredii USDA257 are closely related. Small differences in their nodulation genes result in NGR234 secreting larger amounts of more diverse lipo-oligosaccharidic Nod factors than USDA257. What effects these differences have on nodulation were analyzed by inoculating 452 species of legumes, representing all three subfamilies of the Leguminosae, as well as the nonlegume Parasponia andersonii, with both strains. The two bacteria nodulated P. andersonii, induced ineffective outgrowths on Delonix regia, and nodulated Chamaecrista fasciculata, a member of the only nodulating genus of the Caesalpinieae tested. Both strains nodulated a range of mimosoid legumes, especially the Australian species of Acacia, and the tribe Ingeae. Highest compatibilities were found with the papilionoid tribes Phaseoleae and Desmodieae. On Vigna spp. (Phaseoleae), both bacteria formed more effective symbioses than rhizobia of the "cowpea" (V. unguiculata) miscellany. USDA257 nodulated an exact subset (79 genera) of the NGR234 hosts (112 genera). If only one of the bacteria formed effective, nitrogen-fixing nodules it was usually NGR234. The only exceptions were with Apios americana, Glycine max, and G. soja. Few correlations can be drawn between Nod-factor substituents and the ability to nodulate specific legumes. Relationships between the ability to nodulate and the origin of the host were not apparent. As both P. andersonii and NGR234 originate from Indonesia/Malaysia/Papua New Guinea, and NGR234's preferred hosts (Desmodiinae/Phaseoleae) are largely Asian, we suggest that broad host range originated in Southeast Asia and spread outward. PMID:10188270

Pueppke, S G; Broughton, W J

1999-04-01

280

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 mutantR95::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

281

Final Environmental Statement related to the operation of Wolf Creek Generating Station, Unit No. 1. Docket No. STN 50-482, Kansas Gas and Electric Company, et al  

International Nuclear Information System (INIS)

This final environmental statement contains the second assessment of the environmental impact associated with operation of Wolf Creek Generating Station Unit 1 pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR Part 51, as amended, of the NRC's regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial- and aquatic-ecological impacts will be small. Air-quality impacts will also be small. However, steam fog from the station's cooling lake has the potential for reducing visibility over nearby roads and bridges. A fog-monitoring program for roads and bridges near the lake has been recommended. Impacts to historic and prehistoric sites will be negligible. Chemical discharges to the Neosho River are expected to have no appreciable impacts on water quality under normal conditions and will be required to meet conditions of the station's NPDES permit. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission line facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial. The action called for is the issuance of an operating license for the Wolf Creek Generating Station Unit 1

282

Diglyceride Kinase Activity in Cell Extracts of Rhizobium meliloti: Evidence for a Diglyceride Cycle during Cyclic ?-1,2-Glucan Biosynthesis  

OpenAIRE

In this article, we provide evidence for the presence of diglyceride kinase activity in cell extracts of Rhizobium meliloti 1021. Characterization of the rhizobial enzyme revealed that it shares many properties with the diglyceride kinase of Escherichia coli. A possible role for this enzyme during cyclic ?-1,2-glucan biosynthesis is discussed.

Hunt, William P.; Gore, Richard S.; Miller, Karen J.

1991-01-01

283

Diglyceride Kinase Activity in Cell Extracts of Rhizobium meliloti: Evidence for a Diglyceride Cycle during Cyclic beta-1,2-Glucan Biosynthesis.  

Science.gov (United States)

In this article, we provide evidence for the presence of diglyceride kinase activity in cell extracts of Rhizobium meliloti 1021. Characterization of the rhizobial enzyme revealed that it shares many properties with the diglyceride kinase of Escherichia coli. A possible role for this enzyme during cyclic beta-1,2-glucan biosynthesis is discussed. PMID:16348611

Hunt, W P; Gore, R S; Miller, K J

1991-12-01

284

Population structure of root nodulating Rhizobium leguminosarum in Vicia cracca populations at local to regional geographic scales.  

Science.gov (United States)

The genetic diversity and population structure of about 350 Rhizobium leguminosarum biovar viciae isolates from Vicia cracca were analysed. A hierarchical sampling design was used covering three regions, one region in Belgium and two in France, in which multiple local V. cracca populations were sampled. Rhizobium isolates were genotyped using RAPD and by sequencing two chromosomal housekeeping genes (glnII and recA) and one plasmid-borne gene (nodC). Twenty-six nodC types and sixty-seven chromosomal types were identified, many of which appeared to be regional or local endemics. We found strong genetic differentiation both among V. cracca populations that are separated by only a few kilometres, and among regions that are 50 to 350km apart. Despite significant plasmid exchange, chromosomal and nod types were similarly structured among host populations and regions. We found two lineages of which one prevailed in the Belgian region while the other dominated the French regions. Although a significant correlation between genetic differentiation and geographic distance was found, it is deemed more likely that the observed biogeographic patterns are rather due to coevolutionary interactions and environmental pressures. Furthermore, the impact of recombination on the chromosomal differentiation was found to be considerable. PMID:25199986

Van Cauwenberghe, Jannick; Verstraete, Brecht; Lemaire, Benny; Lievens, Bart; Michiels, Jan; Honnay, Olivier

2014-12-01

285

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

286

Evidence for Cytokinin Involvement in Rhizobium (IC3342)-Induced Leaf Curl Syndrome of Pigeonpea (Cajanus cajan Millsp.).  

Science.gov (United States)

A uniquely abnormal shoot development (shoot tip-bending, leaf curling, release from apical dominance, and stunted growth) in pigeonpea (Cajanus cajan Millsp) induced by a nodulating Rhizobium strain, IC3342, is thought to be due to a hormonal imbalance. Amaranthus betacyanin bioassay indicated that xylem exudate and leaf extracts from pigeonpea plants with Rhizobium-induced leaf curl symptoms contained high concentrations of cytokinin relative to those in normal plants. Radioimmunoassay (RIA) of samples purified with high performance liquid chromatography revealed that zeatin riboside (ZR) and dihydrozeatin riboside (DZR) concentrations in xylem sap from plants with leaf curl symptoms were 7 to 9 times higher than those in the sap from symptomless, nodulated plants. The sap from symptomless plants nodulated by a Curl(-) mutant had ZR and DZR concentrations comparable to those in the normal plant sap. RIA indicated that the respective concentrations of zeatin and N(6)-isopenteny-ladenine in culture filtrates of the curl-inducing strain IC3342 were 26 and 8 times higher than those in filtrates of a related normal nodulating strain (ANU240). Gas chromatographic-mass spectrometric analyses revealed similar differences. Gene-specific hybridization and sequence comparisons failed to detect any homology of IC3342 DNA to Agrobacterium tumefaciens or Pseudomonas savastanoi genetic loci encoding enzymes involved in cytokinin biosynthesis. PMID:16668086

Upadhyaya, N M; Parker, C W; Letham, D S; Scott, K F; Dart, P J

1991-04-01

287

“Item perrexil, mostarda, lechugas et rauanos”. Notas sobre la alimentación de mineros alemanes en Pamplona a finales del siglo XIV (1392  

Directory of Open Access Journals (Sweden)

Full Text Available The present article represents an approximation to the food of some German miners settled in Pamplona at the end of the 14th century, to carry out a series of assays intended to determine the kind of metals present in the ore and their actual proportion, with the purpose to verify the profitability of some seams found at Five Villages. Their food accounting for approximately one and a half months, give us first hand information of their habits and of those sharing the table with them. To a certain extent, it is possible to extrapolate these practices to the ones of part of Navarra's salary earners. In them, we could sense certain customs or preferences characteristic of North Europe.

El presente artículo es una aproximación a la alimentación de unos mineros alemanes que, a finales del siglo XIV, se asientan en Pamplona con el fin de realizar una serie de ensayos (averiguación de los metales que contiene la mena —el mineral metalífero—, y la proporción en que cada uno está con el peso de ella en los que determinar la rentabilidad de algunos filones mineros encontrados en la zona de las Cinco Villas. Las cuentas de los gastos que realizan en alimentación, en aprox. mes y medio, nos acercan de primera mano a los hábitos de estos hombres y de quienes les acompañan en la mesa. Unas prácticas que es posible extrapolar, en cierta medida, a parte de la menestralía navarra, y en las que podemos intuir ciertas costumbres (o gustos propios de la Europa del Norte.

Serrano Larráyoz, Fernando

2008-06-01

288

Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium / Rheological properties and effect of the salt addition on the exopolysaccharides viscosity produced by bacteria of Rhizobium genus  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese [...] Abstract in english Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4) produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of t [...] hese molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.

Gabriel, Aranda-Selverio; Ana Lúcia Barretto, Penna; Luciana Frizarin, Campos-Sás; Osvaldo dos, Santos Junior; Ana Flora Dalberto, Vasconcelos; Maria de Lourdes Corradi da, Silva; Eliana Gertrudes Macedo, Lemos; João Carlos, Campanharo; Joana Léa Meira, Silveira.

289

Propriedades reológicas e efeito da adição de sal na viscosidade de exopolissacarídeos produzidos por bactérias do gênero Rhizobium Rheological properties and effect of the salt addition on the exopolysaccharides viscosity produced by bacteria of Rhizobium genus  

Directory of Open Access Journals (Sweden)

Full Text Available Viscosity of some polysaccharide solutions supports that these molecules can be applied in food sectors. Four exopolysaccharides (R1, R2, R3, R4 produced by different Rhizobium strains were selected. Sugar composition and differences in the uronic acid contents suggests that chemical structure of these molecules can vary when different culture conditions and strains are analyzed. The Power Law was the rheological model used to represent the experimental data of shear stress versus shear rate. All exopolysaccharides showed non-Newtonian behavior, with pseudoplastic characteristics. R1, R2 and R4 showed a slight increase in viscosity in the presence of 0,2 M NaCl.

Gabriel Aranda-Selverio

2010-01-01

290

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

Directory of Open Access Journals (Sweden)

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

291

Response of lupine plants irrigated with saline water to rhizobium inoculation using 15N-isotope dilution  

International Nuclear Information System (INIS)

The lupine Rhizobium symbiosis and contribution of N2 fixation under different levels of irrigation water salinity were examined. Lysimeter experiment was established under greenhouse conditions during the year 2002-2003. In this experiment, inoculated plants were imposed to different salinity levels of irrigation water and N-fertilizer treatment. Plant height was decreased under different salinity levels, nitrogen treatments and bacterial inoculation. Similar trend was noticed with leaf area. The highest leaf area was recorded with salt tolerant bacterial inoculation (SBI) and splitting N-treatment. Highest values of N-uptake occurred after 100 day intervals under the tested factors. Relative decrease in N-uptake did not exceed 40% of those recorded with the fresh water treatment as affected by experimental factors. Nitrogen uptake by the whole plant reflected an increase at 3 dS/m salinity level of irrigation water. Relative increases were 5% and 15% for normal bacteria inoculation under single dose (NI) and splitting

292

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)

293

Phenotypic variation and molecular signaling in the interaction of the rhizosphere bacteria Acidovorax sp. N35 and Rhizobium radiobacter F4 with roots  

OpenAIRE

The aim of this doctoral thesis was to investigate the factors relevant in plant interaction of two plant growth promoting rhizobacteria (PGPR). For this, the strain Acidovorax sp. N35 isolated from surface sterilized wheat roots and the two strains F4 and F7 of Rhizobium radiobacter, a bacterium associated with the plant growth promoting fungus Piriformospora indica, were chosen. First of all, the isolate N35 was characterized using phylogenetic and taxonomic methods. The 16S rRNA gene seque...

Li, Dan

2011-01-01

294

Flavone-enhanced accumulation and symbiosis-related biological activity of a diglycosyl diacylglycerol membrane glycolipid from Rhizobium leguminosarum biovar trifolii.  

OpenAIRE

Rhizobium leguminosarum bv. trifolii is the bacterial symbiont which induces nitrogen-fixing root nodules on the leguminous host, white clover (Trifolium repens L.). In this plant-microbe interaction, the host plant excretes a flavone, 4',7-dihydroxyflavone (DHF), which activates expression of modulation genes, enabling the bacterial symbiont to elicit various symbiosis-related morphological changes in its roots. We have investigated the accumulation of a diglycosyl diacylglycerol (BF-7) in w...

Orgambide, G. G.; Philip-hollingsworth, S.; Hollingsworth, R. I.; Dazzo, F. B.

1994-01-01

295

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

OpenAIRE

El objetivo de esta investigación fue evaluar (a) la capacidad de absorción de Cu por Leucaena leucocephala y (b) el efecto en sus características agronómicas al inocularse con hongos endomicorrízicos arbusculares y Rhizobium como alternativa para la fitorremediación de suelos agrícolas contaminados. El trabajo se realizó en condiciones de invernadero en suelo contaminado por Cu procedente de la parte alta de la cuenca del río Lerma, estado de México. Las plantas de Leucaena crecier...

Abdul Khalil Gardezi; Barcelo-quintal, Icela D.; V\\u00EDctor Manuel Cetina-Alcal\\u00E1; Anne Laure Bussy; Rez-nieto, Joel P. U. E.; Borja-salin, Manuel A.

2006-01-01

296

A Mannosyl Transferase Required for Lipopolysaccharide Inner Core Assembly in Rhizobium leguminosarum: Purification, substrate specificity, and expression in Salmonella waaC mutants*  

OpenAIRE

The lipopolysaccharide (LPS) core domain of Gram-negative bacteria plays an important role in outer membrane stability and host interactions. Little is known about the biochemical properties of the glycosyltransferases that assemble the LPS core. We now report the purification and characterization of the Rhizobium leguminosarum mannosyl transferase LpcC, which adds a mannose unit to the inner 3-deoxy-D-manno-octulosonic acid (Kdo) moiety of the LPS precursor, Kdo2-lipid IVA. LpcC containing a...

Kanipes, Margaret I.; Ribeiro, Anthony A.; Lin, Shanhua; Cotter, Robert J.; Raetz, Christian R. H.

2003-01-01

297

Flavonoids induce Rhizobium leguminosarum to produce nodDABC gene-related factors that cause thick, short roots and root hair responses on common vetch.  

OpenAIRE

Rhizobium leguminosarum produced a factor(s) that caused thick, short roots (Tsr phenotype) as well as root hair induction (Hai phenotype) and deformation (Had phenotype) in Vicia sativa plants upon incubation with root exudate or with one of the nod gene inducers naringenin or apigenin; this was a nodDABC gene-dependent process. Detection of the Hai and Had phenotypes was much more sensitive than that of the Tsr phenotype.

Zaat, S. A.; Brussel, A. A.; Tak, T.; Pees, E.; Lugtenberg, B. J.

1987-01-01

298

Root colonization of different plants by plant-growth-promoting Rhizobium leguminosarum bv. trifolii R39 studied with monospecific polyclonal antisera.  

OpenAIRE

Monospecific polyclonal antisera raised against Rhizobium leguminosarum bv. trifolii R39, a bacterium which was isolated originally from red clover nodules, were used to study the colonization of roots of leguminous and nonleguminous plants (Pisum sativum, Lupinus albus, Triticúm aestivum, and Zea mays) after inoculation. Eight weeks after inoculation of soil-grown plants, between 0.1 and 1% of the total bacterial population in the rhizospheres of all inoculated plants were identified as R. ...

Schloter, M.; Wiehe, W.; Assmus, B.; Steindl, H.; Becke, H.; Ho?flich, G.; Hartmann, A.

1997-01-01

299

Diversity of Plasmid Profiles and Conservation of Symbiotic Nitrogen Fixation Genes in Newly Isolated Rhizobium Strains Nodulating Sulla (Hedysarum coronarium L.)  

OpenAIRE

Forty-five Rhizobium strains nodulating sulla (Hedysarum coronarium L.), isolated from plants grown in different sites in Menorca Island and southern Spain, were examined for plasmid content and the location and organization of nif (nitrogen fixation) and nod (nodulation) sequences. A great diversity in both number and size of the plasmids was observed in this native population of strains, which could be distributed among 19 different groups according to their plasmid profiles. No correlation...

Mozo, Teresa; Cabrera, Ezequiel; Ruiz-argu?eso, Toma?s

1988-01-01

300

Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis Protein Banding Patterns among Rhizobium leguminosarum biovar phaseoli Strains Isolated from the Mexican Bean Phaseolus coccineus  

OpenAIRE

Several rhizobial strains were isolated from Phaseolus coccineus root nodules and were determined to be Rhizobium leguminosarum biovar phaseoli strains after reinfection of the same host plant. These strains were characterized by cultural procedures (growth on different carbon sources and intrinsic antibiotic resistance) and electrophoretic procedures (sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total proteins). Our results showed that these rhizobia are very similar to each ...

Arredondo-peter, R.; Escamilla, E.

1993-01-01

301

Second Site Mutations Specifically Suppress the Fix(-) Phenotype of Rhizobium Meliloti Ndvf Mutations on Alfalfa: Identification of a Conditional Ndvf-Dependent Mucoid Colony Phenotype  

OpenAIRE

Rhizobium meliloti mutants carrying ndvF insertion or deletion mutations induce nodules on alfalfa which contain very few infected cells and fail to fix N(2) (Fix(-)). We have characterized five independent second site mutations (designated sfx) which completely suppress the Fix(-) phenotype of ndvF mutants on Medicago sativa but not on another R. meliloti host Melilotus alba. Genetic mapping and phenotypic analysis revealed that the suppressor mutations sfx-1, sfx-4 and sfx-5 mapped to a sin...

Oresnik, I. J.; Charles, T. C.; Finan, T. M.

1994-01-01

302

Formation in Rhizobium and Agrobacterium spp. of a 235-kilodalton protein intermediate in beta-D(1-2) glucan synthesis.  

OpenAIRE

beta-D(1-2) Glucan was synthesized by Agrobacterium and Rhizobium spp. in vitro with enzymes from the internal membranes upon the addition of UDF glucose and Mg2+ or Mn2+. An intermediate containing protein and beta-D(1-2) glucan was formed during the reaction. It could be precipitated with trichloroacetic acid or separated by polyacrylamide gel electrophoresis under denaturing conditions. After detection with Coomassie blue or a radioactive substrate, the intermediate appeared as a 235-kilod...

Zorreguieta, A.; Ugalde, R. A.

1986-01-01

303

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

OpenAIRE

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 e...

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

2008-01-01

304

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

OpenAIRE

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 i...

Muhammad Iqbal Hussain, Muhammad Javed Akhtar

2011-01-01

305

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

OpenAIRE

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

306

Functional Analysis of NopM, a Novel E3 Ubiquitin Ligase (NEL) Domain Effector of Rhizobium sp. Strain NGR234  

OpenAIRE

Type 3 effector proteins secreted via the bacterial type 3 secretion system (T3SS) are not only virulence factors of pathogenic bacteria, but also influence symbiotic interactions between nitrogen-fixing nodule bacteria (rhizobia) and leguminous host plants. In this study, we characterized NopM (nodulation outer protein M) of Rhizobium sp. strain NGR234, which shows sequence similarities with novel E3 ubiquitin ligase (NEL) domain effectors from the human pathogens Shigella flexneri and Salom...

Xin, Da-wei; Liao, Sha; Xie, Zhi-ping; Hann, Dagmar R.; Steinle, Lea; Boller, Thomas; Staehelin, Christian

2012-01-01

307

Rhizobium paranaense sp. nov., an effective N2-fixing symbiont of common bean (Phaseolus vulgaris L.) with broad geographical distribution in Brazil.  

Science.gov (United States)

Nitrogen (N), the nutrient most required for plant growth, is key for good yield of agriculturally important crops. Common bean (Phaseolus vulgaris L.) can benefit from bacteria collectively called rhizobia, which are capable of fixing atmospheric nitrogen (N2) in root nodules and supplying it to the plant. Common bean is amongst the most promiscuous legume hosts; several described species, in addition to putative novel ones have been reported as able to nodulate this legume, although not always effectively in terms of fixing N2. In this study, we present data indicating that Brazilian strains PRF 35(T), PRF 54, CPAO 1135 and H 52, currently classified as Rhizobium tropici, represent a novel species symbiont of common bean. Morphological, physiological and biochemical properties differentiate these strains from other species of the genus Rhizobium, as do BOX-PCR profiles (less than 60?% similarity), multilocus sequence analysis with recA, gyrB and rpoA (less than 96.4?% sequence similarity), DNA-DNA hybridization (less than 50?% DNA-DNA relatedness), and average nucleotide identity of whole genomes (less than 92.8.%). The novel species is effective in nodulating and fixing N2 with P. vulgaris, Leucaena leucocephala and Leucaena esculenta. We propose the name Rhizobium paranaense sp. nov. for this novel taxon, with strain PRF 35(T) (?=?CNPSo 120(T)?=?LMG 27577(T)?=?IPR-Pv 1249(T)) as the type strain. PMID:24972614

Dall'Agnol, Rebeca Fuzinatto; Ribeiro, Renan Augusto; Delamuta, Jakeline Renata Marçon; Ormeño-Orrillo, Ernesto; Rogel, Marco Antonio; Andrade, Diva Souza; Martínez-Romero, Esperanza; Hungria, Mariangela

2014-09-01

308

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

309

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  

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Full Text Available Los terrenos decapitados constituyen un caso extremo de degradación de suelos aptos para agricultura, con graves consecuencias ambientales. El propósito de este trabajo fue ensayar los efectos de la inoculación de acacia blanca (Robinia pseudoacacia L. con una cepa efectiva de Rhizobium y un hongo de micorrizas arbusculares (Glomus deserticola en la supervivencia y crecimiento temprano de plantas trasplantadas a un terreno decapitado de Balcarce, comparando con fresno como árbol no fijador de nitrógeno. La supervivencia inicial fue muy buena (mayor del 77%, especialmente para los fresnos y las acacias inoculadas, las cuales mostraron significativamente mayor supervivencia al estrés por sequía que las acacias control. Todas las plantas se mostraron igualmente tolerantes al ataque de liebres y al estrés por heladas tardías. Durante el primer año las acacias inoculadas crecieron más rápido que las no inoculadas. En el segundo año las alturas se equipararon en parte, probablemente por la colonización de las acacias control con rizobios o micorrizas naturales del suelo. De todos modos, las acacias inoculadas siempre mostraron valores mayores de los distintos parámetros de desarrollo (altura total, diámetro de la copa y cantidad de ramificaciones que las plantas control, tanto en los sectores poco decapitados como en los más severamente degradados. En conclusión, la doble inoculación previa de acacia blanca mejoró la supervivencia inicial, aumentó tolerancia a la sequía y el crecimiento en 2 años y medio desde la plantación. Esta práctica de manejo sería entonces muy recomendable para reducir el período de vivero en la producción de árboles, así como lograr ejemplares más resistentes y mejor adaptados para proyectos de recuperación de suelos degradados.Many agricultural lands in Buenos Aires Province (Argentina have traditionally been desurfaced for the manufacture of bricks and other building materials. The desurfaced soils represent an extreme situation of degradation, having severe consequences for the environment. The purpose of this work was to assay the effects of inoculation of black locust (Robinia pseudoacacia L. with Rhizobium and with a mycorrhizal strain on the survival and early growth of plants in a desurfaced field at the location of Balcarce (37º 45´ S, 58º 18´ O, in Buenos Aires Province (Argentina. The development of inoculated black locust was compared with non-inoculated (control black locust and with the non-fixing green ash (Fraxinus pennsylvanica Marsh.. Survival after two months was very good (>77%, especially for Fraxinus and for inoculated plants. Furthermore, inoculated plants also showed a significantly higher survival rate under drought stress than the control plants. The three kinds of plants showed high tolerance to hare attack and to late frost stress. During the first year, inoculated plants grew more rapidly than non-inoculated controls. During the second year the height of the two treatments was quite similar, probably because of the nodulation of control plants with soil-borne rhizobial or mycorrhizal strains. However, inoculated plants always showed higher development than the control plants according to three growth parameters (total height, canopy diameter and amount of side branches, both in the intact parts of the field and in the most severely extracted sectors. In conclusion, prior inoculation of black locust with effective strains of Rhizobium and mycorrhizal fungi was able to improve initial survival, tolerance to drought and early growth. This management practice is highly recommended to reduce the greenhouse period in the production of trees, and to produce plants more resistant and better adapted to use in reclamation projects of degraded areas.

Alejandro E Ferrari

2010-07-01

310

Synergistic interaction of Rhizobium leguminosarum bv. viciae and arbuscular mycorrhizal fungi as a plant growth promoting biofertilizers for faba bean (Vicia faba L.) in alkaline soil.  

Science.gov (United States)

Egyptian soils are generally characterized by slightly alkaline to alkaline pH values (7.5-8.7) which are mainly due to its dry environment. In arid and semi-arid regions, salts are less concentrated and sodium dominates in carbonate and bicarbonate forms, which enhance the formation of alkaline soils. Alkaline soils have fertility problems due to poor physical properties which adversely affect the growth and the yield of crops. Therefore, this study was devoted to investigating the synergistic interaction of Rhizobium and arbuscular mycorrhizal fungi for improving growth of faba bean grown in alkaline soil. A total of 20 rhizobial isolates and 4 species of arbuscular mycorrhizal fungi (AMF) were isolated. The rhizobial isolates were investigated for their ability to grow under alkaline stress. Out of 20 isolates 3 isolates were selected as tolerant isolates. These 3 rhizobial isolates were identified on the bases of the sequences of the gene encoding 16S rRNA and designated as Rhizobium sp. Egypt 16 (HM622137), Rhizobium sp. Egypt 27 (HM622138) and Rhizobium leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The best alkaline tolerant was R. leguminosarum bv. viciae STDF-Egypt 19 (HM587713). The effect of R. leguminosarum bv. viciae STDF-Egypt 19 and mixture of AMF (Acaulospora laevis, Glomus geosporum, Glomus mosseae and Scutellospora armeniaca) both individually and in combination on nodulation, nitrogen fixation and growth of Vicia faba under alkalinity stress were assessed. A significant increase over control in number and mass of nodules, nitrogenase activity, leghaemoglobin content of nodule, mycorrhizal colonization, dry mass of root and shoot was recorded in dual inoculated plants than plants with individual inoculation. The enhancement of nitrogen fixation of faba bean could be attributed to AMF facilitating the mobilization of certain elements such as P, Fe, K and other minerals that involve in synthesis of nitrogenase and leghaemoglobin. Thus it is clear that the dual inoculation with Rhizobium and AMF biofertilizer is more effective for promoting growth of faba bean grown in alkaline soils than the individual treatment, reflecting the existence of synergistic relationships among the inoculants. PMID:23920230

Abd-Alla, Mohamed Hemida; El-Enany, Abdel-Wahab Elsadek; Nafady, Nivien Allam; Khalaf, David Mamdouh; Morsy, Fatthy Mohamed

2014-01-20

311

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  

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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

312

Rapport final de la Collaboration CERN-CNRS pour la construction du LHC Accord Technique d'Exécution No 2 Cryostats et assemblage des sections droites courtes (SSS) du LHC  

CERN Document Server

Depuis 1995 et suite à la signature du protocole de Collaboration, le CERN, le CEA et le CNRS ont étroitement collaboré dans le cadre de la contribution exceptionnelle de la France à la construction du LHC. Pour le CNRS, l'Institut de Physique Nucléaire d'Orsay a pris en charge deux Accords Techniques d'Exécution. Le premier concerne la conception et l'assemblage des Sections Droites Courtes de la machine, et le deuxième, l'étalonnage des thermomètres cryogéniques du LHC. Dans le cadre de l'Accord Technique d'Exécution N°2, le Bureau d'Etudes de la Division Accélérateur de l'IPNO et le groupe AT-CRI du CERN ont travaillé de concert pour mener à bien la conception des SSS (Short Straight Section) et de tous les équipements nécessaires à l'assemblage. Ce rapport a donc pour objectif de dresser, en termes d'historique, d'organisation, de résultats quantitatifs et qualitatifs et de moyens mis en ?uvre, un tableau aussi complet que possible du déroulement de cette Collaboration entre le CERN e...

Bergot, JB; Poncet, A; Rohmig, P; Roy, E; Vincent, D

2006-01-01

313

[Comparison of the adaptive potential for Rhizobium leguminosarum bv. viceae nodule bacterial populations isolated in natural ecosystems and agrocenoses].  

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Polymorphism analysis was performed in Rhizobium leguminosarum bv. viceae populations isolated from geographically distant regions of Ukraine and Middle Asia. Examination of cultural, biochemical, and symbiotic traits revealed interpopulation differences, which were attributed to the difference in conditions between natural ecosystems and agrocenoses. Vetch has high species diversity and is not cultivated in Middle Asia, and the corresponding rhizobial population displayed higher genetic diversity and higher polymorphism of adaptive traits ensuring saprophytic development in soil and the rhizosphere, including melanin synthesis (35%) and active exopolysaccharide production (90%). Strains of the Ukrainian population had a lower exopolysaccharide production (10%), did not produce melanin, had higher herbicide resistance, and utilized glucose and succinate (main components of plant root exudation) as carbon sources. Strains capable of efficient symbiosis with Vicia villosa Roth. had a higher frequency in the Middle Asian than in the Ukrainian population, especially among strains isolated from soil (80 and 35%, respectively). In addition, strains of the Middle Asian population better competed for nodulation. It was assumed that the formation of rhizobial populations in vetch cultivation regions (Ukraine) is aimed at adaptation to ectosymbiotic (rhizospheric) interactions with plants and anthropogenic stress factors, while strains of the vetch original center (Middle Asia) are mostly adapted to the endosymbiotic interaction and to natural edaphic stress factors. PMID:21675237

Kurchak, O N; Provorov, N A; Simarov, B V

2011-04-01

314

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

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Sequence inspection identified several potential IHF binding sites adjacent to the Rhizobium leguminosarum dctA promoter. IHF protected the -30 to -76 region from DNase I digestion, but systematic error in quantitative assays suggested that this protein DNA interaction is complex. IHF stimulated DctD-mediated transcriptional activation from the R. leguminosarum dctA promoter both in vivo and in vitro. In contrast to R. leguminosarum dctA, the Sinorhizobium meliloti dctA promoter region was found to have a much weaker match to the consensus IHF binding site and a low affinity for IHF. Moreover, IHF had no effect on transcriptional activation from the S. meliloti dctA promoter in vitro. A base substitution was introduced into the IHF binding site of R. leguminosarum dtA that reduced the affinity of the promoter regulatory region for IHF by approximately 30-fold and resulted in an eight-fold decrease in transcriptional activation in both R. leguminosarum and S. meliloti. These data suggest that both rhizobial species have an IHF homolog that stimulates DctD-mediated transcriptional activation from the R. leguminosarum dctA promoter. Consistent with this hypothesis, a 12.5 kDa protein was identified from R. leguminosarum as a putative homolog of IHF subunit beta by immunoblotting and N-terminal sequence analysis. PMID:10570977

Sojda, J; Gu, B; Lee, J; Hoover, T R; Nixon, B T

1999-10-01

315

Structural determination of the lipo-chitin oligosaccharide nodulation signals produced by Rhizobium giardinii bv. giardinii H152.  

Science.gov (United States)

Rhizobium giardinii bv. giardinii is a microsymbiont of plants of the genus Phaseolus and produces extracellular signal molecules that are able to induce deformation of root hairs and nodule organogenesis. We report here the structures of seven lipochitooligosaccharide (LCO) signal molecules secreted by R. giardinii bv. giardinii H152. Six of them are pentamers of GlcNAc carrying C 16:0, C 18:0, C 20:0 and C 18:1 fatty acyl chains on the non-reducing terminal residue. Four are sulfated at C-6 of the reducing terminal residue and one is acetylated in the same position. Six of them are N-methylated on the non-reducing GlcN residue and all the nodulation factors are carbamoylated on C-6 of the non-reducing terminal residue. The structures were determined using monosaccharide composition and methylation analyses, 1D- and 2D-NMR experiments and a range of mass spectrometric techniques. The position of the carbamoyl substituent on the non-reducing glucosamine residue was determined using a CID-MSMS experiment and an HMBC experiment. PMID:12543556

Soria-Díaz, M Eugenia; Tejero-Mateo, Pilar; Espartero, José L; Rodríguez-Carvajal, Miguel A; Morón, Belén; Sousa, Carolina; Megías, Manuel; Amarger, Noelle; Thomas-Oates, Jane; Gil-Serrano, Antonio M

2003-01-31

316

Optimization of surface sterilization for legume seed. [Medicago sativa L. , Trifolium repens L. ; Glycine max (L. ) Merr; Rhizobium meliloti  

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Roots of alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), and soybean (Glycine max (L.) Merr.) seedlings are frequently contaminated with bacteria even after surface sterilization of the seeds and germination under aspetic conditions. Several seed-sterilization procedures were compared for their ability to minimize or eliminate such contamination without damaging the plant. Mercuric chloride proved the best seed disinfectant for alfalfa and white clover. Calcium hypochlorite was the best for soybean. For alfalfa seeds, treatment with 95% ethanol (v/v) for 60 min followed by 0.2% HgCl{sub 2} (v/v) for 15 min prior to rinsing and imbibition resulted in a low frequency (< 5%) of seed and root contamination. This treatment resulted in no measurable damage to alfalfa seedlings with respect to root growth, nodulation efficiency, or rate of nodule emergence following inoculation with Rhizobium meliloti. Longer exposures to HgCl{sub 2} further reduced bacterial contamination, but also caused modest reductions in seed germination. None of the surface-sterilization techniques tested completely eliminated bacterial contaminants. It appears that these sterilization-resistant contaminants are borne within the seed and proliferate on plant surfaces after germination, with possible effects on plant health.

Caetano-Anolles, G. (Univ. of Tennessee, Knoxville (USA)); Favelukes, G. (Universidad Nacional de La Plata (Argentina)); Bauer, W.D. (Ohio State Univ., Columbus (USA))

317

Effect of N-rate and P sources on BNF in soybean as affected by rhizobium and VAM fungi lnoculants  

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Greenhouse experiment was made to investigate the influence of phosphate fertilizers on nitrogen fixation in soybean. The N-15 isotope dilution method was used to quantify N 2-fixed. In this concern, seed of nodulated and on-nodulated soybean plant bacterized with Bradyrhizobium japonicum and noculated without or with mycorrhizas in the presence of super or rock phosphate. Ammonium sulphate labelled fertilizer (5% N-15 a.e) was applied o 15 kg sandy soil of egypt at the rate of 20 and 100 kg N/acre. At re-flowering stage, the highest amount of N derived from air (Ndfa) was 66.3 and 470.2 (mg/pot) equivalent 47.6 and 47.1 of total N assimilated for noculated soybean with Rhizobium and fertilized with super or rock phosphate, respectively. While the contributions from 15 N labelled fertilizer (Ndff) accounted for 11 and 10.8, respectively. Use of mycorrhizas could increase the amount of N 2-fixed in the presence of rhizobia. There appears to be a strong case for improving N 2-fixation in the presence of mycorrhizas especially in sandy soil. 4 tabs

318

Biologic fixation of nitrogen in irradiated rhizobium strips; Fixacao biologica do nitrogenio em estirpes de rizobianas irradiadas  

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Native Rhizobium sp. and Bradyrhizobium sp. isolates from the root nodules of bean and cowpea were selected. Six isolates, and the SEMIA 4077 (R. leguminosarum bv. phaseolus) and SEMIA 6145 (Bradyrhizobium sp) strains used as references, were irradiated with ultraviolet light (R-uv) and gamma rays (R-{gamma}). The D{sub 37} values for the rhizobial strain SEMIA 4077 were 43 J.m{sup -2} (UV) and 32 Gy (R-{gamma}) and for the SEMIA 6145 were 45 J.m{sup -2} (UV) and 35 Gy (R-gamma). Through a greenhouse experiment the irradiated isolates were inoculated on bean (P. vulgaris L., cv. Princesa) and on cowpea [Vigna unguiculata, (L.) Walp, cv. IPA-206] seedlings, in an attempt to evaluate the sensitivity of the host plants, and possible effects on their nodulation. Differences in responses to nodulation due to the effect of irradiation were observed for the isolates tested. Significantly differences were observed only for nodules dry matter yield of the IPA-206 cultivar. Gamma irradiated treatment were statistically superior to treatments with ultraviolet light in relation. (author)

Caribe, Rebeka Alves; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear

2002-07-01

319

Enhanced Synthesis of Antioxidant Enzymes, Defense Proteins and Leghemoglobin in Rhizobium-Free Cowpea Roots after Challenging with Meloydogine incognita  

Directory of Open Access Journals (Sweden)

Full Text Available The root knot nematodes (RKN, Meloydogine spp., particularly Meloidogyne incognita and Meloidogyne javanica species, parasitize several plant species and are responsible for large annual yield losses all over the world. Only a few available chemical nematicides are still authorized for RKN control owing to environmental and health reasons. Thus, plant resistance is currently considered the method of choice for controlling RKN, and research performed on the molecular interactions between plants and nematodes to identify genes of interest is of paramount importance. The present work aimed to identify the differential accumulation of root proteins of a resistant cowpea genotype (CE-31 inoculated with M. incognita (Race 3 in comparison with mock-inoculated control, using 2D electrophoresis assay, mass spectrometry identification and gene expression analyses by RT-PCR. The results showed that at least 22 proteins were differentially represented in response to RKN challenge of cowpea roots mainly within 4–6 days after inoculation. Amongst the up-represented proteins were SOD, APX, PR-1, ?-1,3-glucanase, chitinases, cysteine protease, secondary metabolism enzymes, key enzymes involved in ethylene biosynthesis, proteins involved in MAPK pathway signaling and, surprisingly, leghemoglobin in non-rhizobium-bacterized cowpea. These findings show that an important rearrangement in the resistant cowpea root proteome occurred following challenge with M. incognita.

Jose T. A. Oliveira

2014-11-01

320

High NaCl concentrations induce the nod genes of Rhizobium tropici CIAT899 in the absence of flavonoid inducers.  

Science.gov (United States)

The nodulation (nod) genes of Rhizobium tropici CIAT899 can be induced by very low concentrations (micromolar to nanomolar range) of several flavonoid molecules secreted by the roots of leguminous plants under a number of different conditions. Some of these conditions have been investigated and appear to have a great influence on the concentration and the number of different Nod factors, which can induce root nodule primordia and pseudonodules in several leguminous plant roots. In one such condition, we added up to 300 mM NaCl to the induction medium of R. tropici CIAT899 containing the nod gene inducer apigenin. At the higher concentrations of NaCl, larger amounts and more different Nod factors were produced than in the absence of extra NaCl. To our surprise, under control conditions (300 mM NaCl without apigenin), some Nod-factor-like spots were also observed on the thin-layer plates used to detect incorporation of radiolabeled glucosamine into newly synthesized Nod factors. This phenomenon was further investigated with thin-layer plates, fusions of nod genes to the lacZ gene, high-performance liquid chromatography, mass spectrometry, and the formation of pseudonodules on bean roots. Here, we report that, in the absence of flavonoid inducers, high concentrations of NaCl induced nod genes and the production of Nod factors. PMID:23216086

Guasch-Vidal, B; Estévez, J; Dardanelli, M S; Soria-Díaz, M E; de Córdoba, F Fernández; Balog, C I A; Manyani, H; Gil-Serrano, A; Thomas-Oates, J; Hensbergen, P J; Deelder, A M; Megías, M; van Brussel, A A N

2013-04-01

321

Light regulates attachment, exopolysaccharide production, and nodulation in Rhizobium leguminosarum through a LOV-histidine kinase photoreceptor.  

Science.gov (United States)

Rhizobium leguminosarum is a soil bacterium that infects root hairs and induces the formation of nitrogen-fixing nodules on leguminous plants. Light, oxygen, and voltage (LOV)-domain proteins are blue-light receptors found in higher plants and many algae, fungi, and bacteria. The genome of R. leguminosarum bv. viciae 3841, a pea-nodulating endosymbiont, encodes a sensor histidine kinase containing a LOV domain at the N-terminal end (R-LOV-HK). R-LOV-HK has a typical LOV domain absorption spectrum with broad bands in the blue and UV-A regions and shows a truncated photocycle. Here we show that the R-LOV-HK protein regulates attachment to an abiotic surface and production of flagellar proteins and exopolysaccharide in response to light. Also, illumination of bacterial cultures before inoculation of pea roots increases the number of nodules per plant and the number of intranodular bacteroids. The effects of light on nodulation are dependent on a functional lov gene. The results presented in this work suggest that light, sensed by R-LOV-HK, is an important environmental factor that controls adaptive responses and the symbiotic efficiency of R. leguminosarum. PMID:22773814

Bonomi, Hernán R; Posadas, Diana M; Paris, Gastón; Carrica, Mariela del Carmen; Frederickson, Marcus; Pietrasanta, Lía Isabel; Bogomolni, Roberto A; Zorreguieta, Angeles; Goldbaum, Fernando A

2012-07-24

322

A previously uncharacterized tetratricopeptide-repeat-containing protein is involved in cell envelope function in Rhizobium leguminosarum.  

Science.gov (United States)

Rhizobium leguminosarum is a soil bacterium that is an intracellular symbiont of leguminous plants through the formation of nitrogen-fixing root nodules. Due to the changing environments that rhizobia encounter, the cell is often faced with a variety of cell altering stressors that can compromise the cell envelope integrity. A previously uncharacterized operon (RL3499-RL3502) has been linked to proper cell envelope function, and mutants display pleiotropic phenotypes including an inability to grow on peptide-rich media. In order to identify functional partners to the operon, suppressor mutants capable of growth on complex, peptide-rich media were isolated. A suppressor mutant of a non-polar mutation to RL3500 was chosen for further characterization. Transposon mutagenesis, screening for loss of the suppressor phenotype, led to the identification of a Tn5 insertion in an uncharacterized tetratricopeptide-repeat-containing protein RL0936. Furthermore, RL0936 had a 3.5-fold increase in gene expression in the suppressor strain when compared with the WT and a 1.5-fold increase in the original RL3500 mutant. Mutation of RL0936 decreased desiccation tolerance and lowered the ability to form biofilms when compared with the WT strain. This work has identified a potential interaction between RL0936 and the RL3499-RL3502 operon that is involved in cell envelope development in R. leguminosarum, and has described phenotypic activities to a previously uncharacterized conserved hypothetical gene. PMID:25370751

Neudorf, Kara D; Vanderlinde, Elizabeth M; Tambalo, Dinah D; Yost, Christopher K

2015-01-01

323

Relevance of fucose-rich extracellular polysaccharides produced by Rhizobium sullae strains nodulating Hedysarum coronarium l. legumes.  

Science.gov (United States)

Specific and complex interactions between soil bacteria, known as rhizobia, and their leguminous host plants result in the development of root nodules. This process implies a complex dialogue between the partners. Rhizobia synthesize different classes of polysaccharides: exopolysaccharides (EPS), Kdo-rich capsular polysaccharides, lipopolysaccharides, and cyclic ?-(1,2)-glucans. These polymers are actors of a successful symbiosis with legumes. We focus here on studying the EPS produced by Rhizobium sullae bacteria that nodulate Hedysarum coronarium L., largely distributed in Algeria. We describe the influence of the carbon source on the production and on the composition of EPS produced by R. sullae A6 and RHF strains. High-molecular-weight EPS preserve the bacteria from desiccation. The structural characterization of the EPS produced by R. sullae strains has been performed through sugar analysis by gas chromatography-mass spectrometry. The low-molecular-weight EPS of one strain (RHF) has been totally elucidated using nuclear magnetic resonance and quantitative time-of-flight tandem mass spectrometry analyses. An unusual fucose-rich EPS has been characterized. The presence of this deoxy sugar seems to be related to nodulation capacity. PMID:23183977

Gharzouli, Razika; Carpéné, Marie-Anne; Couderc, François; Benguedouar, Ammar; Poinsot, Véréna

2013-03-01

324

A guaB mutant strain of Rhizobium tropici CIAT899 pleiotropically defective in thermal tolerance and symbiosis.  

Science.gov (United States)

Rhizobium tropici strain CIAT899 displays a high intrinsic thermal tolerance, and had been used in this work to study the molecular basis of bacterial responses to high temperature. We generated a collection of R. tropici CIAT899 mutants affected in thermal tolerance using TnS-luxAB mutagenesis and described the characterization of a mutant strain, CIAT899-10T, that fails to grow under conditions of high temperature. Strain CIAT899-10T carries a single transposon insertion in a gene showing a high degree of similarity with the guaB gene of Escherichia coli and other organisms, encoding the enzyme inosine monophosphate dehydrogenase. The guaB strain CIAT899-10T does not require guanine for growth due to an alternative pathway via xanthine dehydrogenase and, phenotypically, in addition to the thermal sensitivity, the mutant is also defective in symbiosis with beans, forming nodules that lack rhizobial content. Guanine and its precursors restore wild-type tolerance to grow at high temperature. Our data show that, in R. tropici, the production of guanine via inosine monophosphate dehydrogenase is essential for growth at extreme temperatures and for effective nodulation. PMID:11059489

Riccillo, P M; Collavino, M M; Grasso, D H; England, R; de Bruijn, F J; Aguilar, O M

2000-11-01

325

Concurrent synthesis and release of nod-gene-inducing flavonoids from alfalfa roots. [Medicago sativa L. ; Rhizobium meliloti  

Energy Technology Data Exchange (ETDEWEB)

Flavonoid signals from alfalfa (Medicago sativa L.) induce transcription of nodulation (nod) genes in Rhizobium meliloti. Alfalfa roots release three major nod-gene inducers: 4{prime},7-dihydroxyflavanone, 4{prime},7-dihydroxyflavone, and 4,4{prime}-dihydroxy-2{prime}-methoxychalcone. The objective of the present study was to define temporal relationships between synthesis and exudation for those flavonoids. Requirements for concurrent flavonoid biosynthesis were assessed by treating roots of intact alfalfa seedlings with (U-{sup 14}C)-L-phenylalanine in the presence or absence of the phenylalanine ammonia-lyase inhibitor L-2-aminoxy-3-phenylpropionic acid (AOPP). In the absence of AOPP, each of the three flavonoids in exudates contained {sup 14}C. In the presence of AOPP, {sup 14}C labeling and release of all the exuded nod-gene inducers were reduced significantly. AOPP inhibited labeling and release of the strongest nod-gene inducer, methoxychalcone, by more than 90%. The release process responsible for exudation of nod-gene inducers appears to be specific rather than a general phenomenon such as a sloughing off of cells during root growth.

Maxwell, C.A.; Phillips, D.A. (Univ. of California, Davis (USA))

1990-08-01

326

Predominant nifH transcript phylotypes related to Rhizobium rosettiformans in field-grown sugarcane plants and in Norway spruce.  

Science.gov (United States)

Although some sugarcane cultivars may benefit substantially from biological nitrogen fixation (BNF), the responsible bacteria have been not identified yet. Here, we examined the active diazotrophic bacterial community in sugarcane roots from Africa and America by reverse transcription (RT)-PCR using broad-range nifH-specific primers. Denaturing gradient gel electrophoresis (DGGE) profiles obtained from sugarcane showed a low diversity at all sample locations with one phylotype amounting up to 100% of the nifH transcripts. This major phylotype has 93.9-99.6% DNA identity to the partial nifH sequence from a strain affiliated with Rhizobium rosettiformans. In addition, nifH transcripts of this phylotype were also detected in spruce roots sampled in Germany, where they made up 91% of nifH transcripts detected. In contrast, in control soil or shoot samples two distinct nifH transcript sequences distantly related to nifH from Sulfurospirillum multivorans or Bradyrhizobium elkanii, respectively, were predominant. These results suggest that R. rosettiformans is involved in root-associated nitrogen fixation with sugarcane and spruce, plants that do not form root-nodule symbioses. PMID:23761284

Burbano, Claudia Sofía; Liu, Yuan; Rösner, Kim Leonie; Reis, Veronica Massena; Caballero-Mellado, Jesus; Reinhold-Hurek, Barbara; Hurek, Thomas

2011-06-01

327

Biotin production under limiting growth conditions by Agrobacterium/Rhizobium HK4 transformed with a modified Escherichia coli bio operon.  

Science.gov (United States)

The E. coli biotin (bio) operon was modified to improve biotin production by host cells: (a) the divergently transcribed wild-type bio operon was re-organized into one transcriptional unit; (b) the wild-type bio promoter was replaced with a strong artificial (tac) promoter; (c) a potential stem loop structure between bioD and bioA was removed; and (d) the wild-type bioB ribosomal binding site (RBS) was replaced with an artificial RBS that resulted in improved bioB expression. The effects of the modifications on the bio operon were studied in E. coli by measuring biotin and dethiobiotin production, and bio gene expression with mini-cells and two-dimensional polyacrylamide gel electrophoresis. The modified E. coli bio operon was introduced into a broad host-range plasmid and used to transform Agrobacterium/Rhizobium HK4, which then produced 110 mg L-1 of biotin in a 2-L fermenter, growing on a defined medium with diaminononanoic acid as the starting material. Biotin production was not growth-phase dependent in this strain, and the rate of production remained high under limiting (maintenance) and zero growth conditions. PMID:10455485

Shaw; Lehner; Fuhrmann; Kulla; Brass; Birch; Tinschert; Venetz; Venetz; Sanchez; Tonella; Hochstrasser

1999-06-01

328

Transgenic Leucaena leucocephala expressing the Rhizobium gene pydA encoding a meta-cleavage dioxygenase shows reduced mimosine content.  

Science.gov (United States)

The use of the tree-legume Leucaena leucocephala (leucaena), which contains high levels of proteins in its foliage, is limited due to the presence of the toxic free amino acid mimosine. The goal of this research was to develop transgenic leucaena with reduced mimosine content. Two genes, pydA and pydB, encoding a meta-cleavage dioxygenase (EC 1.13.11.2) and a pyruvate hydrolase (EC 3.7.1.6), respectively, from the mimosine-degrading leucaena symbiont Rhizobium sp. strain TAL1145, were used to transform leucaena. These bacterial genes were sequence-optimized for expression in leucaena and cloned into the plant binary vector pCAMBIA3201 for Agrobacterium tumefaciens-mediated transformation. Using immature zygotic embryos as the start explant material, six pydA and three pydB transgenic lines were developed. The presence and expression of the bacterial genes in the transgenic lines were verified by PCR, reverse transcriptase PCR, and Southern analyses. HPLC analyses of the transgenic plants determined that the mimosine contents of the pydA-expressing lines were reduced up to 22.5% in comparison to the wild-type. No significant reduction in mimosine content was observed in the pydB-expressing lines. This is the first example of using a gene from a bacterial symbiont to reduce the toxicity of a tree-legume. PMID:20138776

Jube, Sandro L R; Borthakur, Dulal

2010-04-01

329

Accumulation of a nod gene inducer, the flavonoid naringenin, in the cytoplasmic membrane of Rhizobium leguminosarum biovar viciae is caused by the pH-dependent hydrophobicity of naringenin.  

OpenAIRE

Most Sym plasmid-localized nodulation genes of Rhizobium leguminosarum bv. viciae are only expressed upon activation of the NodD protein by plant flavonoids, e.g., naringenin (S. A. J. Zaat, C. A. Wijffelman, H. P. Spaink, A. A. N. van Brussel, and B. J. J. Lugtenberg, J. Bacteriol, 169:198-204, 1987). As part of a study on the mechanism of NodD protein activation, the mechanism of uptake and the intracellular fate of [3H]naringenin were studied. Naringenin was accumulated by Rhizobium cells ...

Recourt, K.; Brussel, A. A.; Driessen, A. J.; Lugtenberg, B. J.

1989-01-01

330

Final Report  

Energy Technology Data Exchange (ETDEWEB)

This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

Gurney, Kevin R

2015-01-12

331

Efficacy of Rhizobium and Pseudomonas strains to improve physiology, ionic balance and quality of mung bean under salt-affected conditions on farmer's fields.  

Science.gov (United States)

High ethylene concentration under different environmental stresses such as salinity is one of the contributing factors for premature senescence of different plant parts. Plants under salinity stress produce increased levels of ethylene which inhibit the plant growth and physiology thus deteriorating the quality of the produce. Some plant growth promoting rhizobacteria (PGPR) have the ability to improve quality of crops through reduction in detrimental effects of salinity on plant growth and physiology by lowering endogenous level of ethylene along with other mechanisms. Two field trials were conducted to evaluate the Rhizobium and Pseudomonas containing ACC-deaminase for their efficacy to reduce the effect of salinity on physiology, ionic and nutrient balance of mung bean. Results showed that salinity stress adversely affected the physiological parameters of mung bean. It decreased the CO(2) assimilation, stomatal conductance of water, relative water content, photosynthetic rate, transpiration rate and chlorophyll contents in mung bean but inoculation of either Rhizobium or Pseudomonas alone reduced adverse effect of salinity significantly. However, co-inoculation with Rhizobium and Pseudomonas was the most effective treatment and it diluted the adverse effects of salinity on relative water contents and CO(2) assimilation rate thus improving the photosynthetic rate, water use efficiency and chlorophyll content over the un-inoculated control. Co-inoculation improved the ionic balance and also increased the phosphorus and protein concentration in grain of mung bean. The results suggested that these strains could be effectively used to improve the growth, physiology and quality of mung bean under salt-affected conditions. PMID:23262185

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

2013-02-01

332

Effects of fly ash, Pseudomonas striata and Rhizobium on the reproduction of nematode Meloidogyne incognita and on the growth and transpiration of pea.  

Science.gov (United States)

Glasshouse experiments were conducted twice to assess the ash amendments (0, 20, and 40% with soil), a phosphate solubilizing microorganism Pseudomonas striata and a root-nodule bacterium Rhizobium sp on the reproduction of root-knot nematode Meloidogyne incognita and on the growth and transpiration of pea. Amendments of fly ash with soil had no effect on transpiration. However, M. incognita reduced the rate of transpiration from 1st week onward after inoculation while inoculation of Rhizobium sp and P. striata increased transpiration from 1st week onward after their inoculation both in nematode inoculated and uninoculated plants. Increase in transpiration was greater when both organisms were inoculated together. Addition of 20 and 40% fly ash with soil was beneficial for plant growth both in nematode inoculated and uninoculated plants. Inoculation of above organisms also increases plant growth of nematode inoculated and uninoculated plants in different fly ash soil mixture but increase in growth was greater when both organisms were inoculated together. Use of 20% fly ash increased galling and nematode multiplication over plants grown in without fly ash while 40% fly ash had adverse effect on galling and nematode multiplication. Rhizobium sp had greater adverse effect on galling and nematode multiplication than P. striata. Use of both organisms together had greater adverse effect on galling and nematode multiplication than caused by either of them alone. Highest reduction in galling and nematode multiplication was observed when both organisms were used in 40% fly ash amended soil. However, highest transpiration was observed in plants without nematodes and inoculated with both organisms together both in with or without fly ash amended soil. PMID:16114471

Siddiqui, Zaki A; Singh, Lamabam Peter

2005-01-01

333

Symbiotic nitrogen fixation by a nifA deletion mutant of Rhizobium meliloti: the role of an unusual ntrC allele.  

OpenAIRE

In the N2-fixing alfalfa symbiont Rhizobium meliloti, the three sigma 54 (NTRA)-dependent positively acting regulatory proteins NIFA, NTRC, and DCTD are required for activation of promoters involved in N2 fixation (pnifHDKE and pfixABCX), nitrogen assimilation (pglnII), and C4-dicarboxylate transport (pdctA), respectively. Here, we describe an allele of ntrC which results in the constitutive activation of the above NTRC-, NIFA-, and DCTD-regulated promoters. The expression and activation of w...

Labes, M.; Rastogi, V.; Watson, R.; Finan, T. M.

1993-01-01

334

FixL of Rhizobium meliloti enhances the transcriptional activity of a mutant FixJD54N protein by phosphorylation of an alternate residue.  

OpenAIRE

In Rhizobium meliloti, transcription of nitrogen fixation genes is induced in oxygen-depleted conditions under the control of the two-component regulatory system FixLJ. FixJ is a transcriptional activator whose activity is dramatically enhanced by phosphorylation, whereas FixL is a hemoprotein kinase that controls the level of phosphorylated FixJ in response to oxygen availability. We have found that a mutant FixJ protein, FixJD54N, in which the presumed site of phosphorylation (aspartate 54)...

Reyrat, J. M.; David, M.; Batut, J.; Boistard, P.

1994-01-01

335

Induction of the nodA promoter of Rhizobium leguminosarum Sym plasmid pRL1JI by plant flavanones and flavones.  

OpenAIRE

An expression vector containing the Rhizobium leguminosarum nodA promoter cloned in front of the Escherichia coli lacZ gene was used to characterize the properties of the R. leguminosarum nodA gene-inducing compound(s) present in sterile root exudate of the host plant Vicia sativa L. subsp. nigra (L.). The major inducing compound was flavonoid in nature, most likely a flavanone. The commercially available flavonoids naringenin (5,7,4'-trihydroxyflavanone), eriodictyol (5,7,3'4'-tetrahydroxyfl...

Zaat, S. A.; Wijffelman, C. A.; Spaink, H. P.; Brussel, A. A.; Okker, R. J.; Lugtenberg, B. J.

1987-01-01

336

The nodD gene of Rhizobium leguminosarum is autoregulatory and in the presence of plant exudate induces the nodA,B,C genes  

OpenAIRE

To analyse nod gene expression in Rhizobium leguminosarum, a broad host-range lacZ protein fusion vector was constructed. Two protein fusions, nodC-lacZ and nodD-lacZ, were used to measure the regulation of expression of the promoters of the nodA,B,C and the nodD transcripts by measuring the induced levels of ?-galactosidase activity in R. leguminosarum. In the absence of plant root exudate the nodD-lacZ hybrid was expressed but the nodC-lacZ hybrid was not. The expression of the nodD-lacZ h...

Rossen, L.; Shearman, C. A.; Johnston, A. W. B.; Downie, J. A.

1985-01-01

337

A Rhizobium meliloti mutant that forms ineffective pseudonodules in alfalfa produces exopolysaccharide but fails to form beta-(1----2) glucan.  

OpenAIRE

A mutant of Rhizobium meliloti that elicited the formation of inactive nodules in alfalfa was found not to form beta-(1----2) glucan in vivo or in vitro. It was nonmotile because it lacks flagella. The 235-kilodalton protein which acts as an intermediate in beta-(1----2) glucan synthesis was undetectable in the mutant. These properties of the mutant are common to those of chvB mutants of Agrobacterium tumefaciens. Exopolysaccharide formation by the R. meliloti mutant was about double that by ...

Geremia, R. A.; Cavaignac, S.; Zorreguieta, A.; Toro, N.; Olivares, J.; Ugalde, R. A.

1987-01-01

338

A Lotus japonicus nodulation system based on heterologous expression of the fucosyl transferase NodZ and the acetyl transferase NoIL in Rhizobium leguminosarum.  

Science.gov (United States)

Heterologous expression of NodZ and NolL proteins in Rhizobium leguminosarum bv. viciae led to the production of acetyl fucosylated lipo-chitin oligosaccharides (LCOs), indicating that the NolL protein obtained from Mesorhizobium loti functions as an acetyl transferase. We show that the NolL-dependent acetylation is specific for the fucosyl penta-N-acetylglucosamine species. In addition, the NolL protein caused elevated production of LCOs. Efficient nodulation of Lotus japonicus by the NodZ/NolL-producing strain was demonstrated. Nodulation efficiency was further improved by the addition of the ethylene inhibitor L-alpha-(2-aminoethoxyvinyl) glycine (AVG). PMID:10755312

Pacios Bras, C; Jordá, M A; Wijfjes, A H; Harteveld, M; Stuurman, N; Thomas-Oates, J E; Spaink, H P

2000-04-01

339

Nickel availability to pea (Pisum sativum L.) plants limits hydrogenase activity of Rhizobium leguminosarum bv. viciae bacteroids by affecting the processing of the hydrogenase structural subunits.  

OpenAIRE

Rhizobium leguminosarum bv. viciae UPM791 induces the synthesis of an [NiFe] hydrogenase in pea (Pisum sativum L.) bacteroids which oxidizes the H2 generated by the nitrogenase complex inside the root nodules. The synthesis of this hydrogenase requires the genes for the small and large hydrogenase subunits (hupS and hupL, respectively) and 15 accessory genes clustered in a complex locus in the symbiotic plasmid. We show here that the bacteroid hydrogenase activity is limited by the availabili...

Brito, B.; Palacios, J. M.; Hidalgo, E.; Imperial, J.; Ruiz-argu?eso, T.

1994-01-01

340

Molecular and culture dependent characterization of endolithic bacteria in two beach sand samples and description of Rhizobium endolithicum sp. nov.  

Science.gov (United States)

Endolithic metagenome analysis of two beach samples collected form Chilika, Odisha, India indicated rich bacterial diversity. While the metagenome analysis of sample one yielded 16S rRNA gene sequences which represent six phyla and 16 genera, sample two yielded very rich diversity representing 17 phyla and 286 genera. Six species of bacteria were isolated from the endolithic enrichments and most of them have 16S rRNA gene sequence similarity of >99 % with known taxa, except for strain JC140(T) having fatty acid is summed feature 8 (C18:1?7c/C18:1?6c) with minor amounts of C19:0 cyclo?8c, C16:0, C18:0, C17:0cyclo, summed feature 2 (C14:03OH/C16:1 isoI), summed feature 3 (C16:1?7c/C16:1?6c) and 2-hydroxyacid of C15:0. Diphosphatidylglycerol, phosphatidylethanol-amine, phosphatidylcholine, phosphatidylglycerol, unidentified lipids (L1, 2), unidentified phospholipid (PL1-4) constitute the polar lipids of strain JC140(T). The strain has bacteriohopane derivative (BHD2), diplopterol and two unidentified hopanes (UH1, 2) as major hopanoids. Q-10 is the major quinone of strain JC140(T). Based on polyphasic taxonomic analysis, strain JC140(T) represents a species in the genus Rhizobium for which, the name R. endolithicum sp. nov. is proposed. The type strain is JC140(T) (= KCTC32077(T) = CCUG64352(T) = MTCC11723(T) = HAMBI 2447(T)). PMID:24104485

Parag, B; Sasikala, Ch; Ramana, Ch V

2013-12-01

341

Succinoglycan production by Rhizobium meliloti is regulated through the ExoS-ChvI two-component regulatory system.  

Science.gov (United States)

The Rhizobium meliloti exoS gene is involved in regulating the production of succinoglycan, which plays a crucial role in the establishment of the symbiosis between R. meliloti Rm1021 and its host plant, alfalfa. The exoS96::Tn5 mutation causes the upregulation of the succinoglycan biosynthetic genes, thereby resulting in the overproduction of succinoglycan. Through cloning and sequencing, we found that the exoS gene is a close homolog of the Agrobacterium tumefaciens chvG gene, which has been proposed to encode the sensor protein of the ChvG-ChvI two-component regulatory system, a member of the EnvZ-OmpR family. Further analyses revealed the existence of a newly discovered A. tumefaciens chvI homolog located just upstream of the R. meliloti exoS gene. R. meliloti ChvI may serve as the response regulator of ExoS in a two-component regulatory system. By using ExoS-specific antibodies, it was found that the ExoS protein cofractionated with membrane proteins, suggesting that it is located in the cytoplasmic membrane. By using the same antibodies, it was shown that the exoS96::Tn5 allele encodes an N-terminal truncated derivative of ExoS. The cytoplasmic histidine kinase domain of ExoS was expressed in Escherichia coli and purified, as was the R. meliloti ChvI protein. The ChvI protein autophosphorylated in the presence of acetylphosphate, and the ExoS cytoplasmic domain fragment autophosphorylated at a histidine residue in the presence of ATP. The ChvI protein was phosphorylated in the presence of ATP only when the histidine kinase domain of ExoS was also present. We propose a model for regulation of succinoglycan production by R. meliloti through the ExoS-ChvI two-component regulatory system. PMID:9422587

Cheng, H P; Walker, G C

1998-01-01

342

Mutation of praR in Rhizobium leguminosarum enhances root biofilms, improving nodulation competitiveness by increased expression of attachment proteins.  

Science.gov (United States)

In Rhizobium leguminosarum bv. viciae, quorum-sensing is regulated by CinR, which induces the cinIS operon. CinI synthesizes an AHL, whereas CinS inactivates PraR, a repressor. Mutation of praR enhanced biofilms in vitro. We developed a light (lux)-dependent assay of rhizobial attachment to roots and demonstrated that mutation of praR increased biofilms on pea roots. The praR mutant out-competed wild-type for infection of pea nodules in mixed inoculations. Analysis of gene expression by microarrays and promoter fusions revealed that PraR represses its own transcription and mutation of praR increased expression of several genes including those encoding secreted proteins (the adhesins RapA2, RapB and RapC, two cadherins and the glycanase PlyB), the polysaccharide regulator RosR, and another protein similar to PraR. PraR bound to the promoters of several of these genes indicating direct repression. Mutations in rapA2, rapB, rapC, plyB, the cadherins or rosR did not affect the enhanced root attachment or nodule competitiveness of the praR mutant. However combinations of mutations in rapA, rapB and rapC abolished the enhanced attachment and nodule competitiveness. We conclude that relief of PraR-mediated repression determines a lifestyle switch allowing the expression of genes that are important for biofilm formation on roots and the subsequent initiation of infection of legume roots. PMID:24942546

Frederix, Marijke; Edwards, Anne; Swiderska, Anna; Stanger, Andrew; Karunakaran, Ramakrishnan; Williams, Alan; Abbruscato, Pamela; Sanchez-Contreras, Maria; Poole, Philip S; Downie, J Allan

2014-08-01

343

Regulation of exopolysaccharide synthesis in Rhizobium sp. strain TAL1145 involves an alternative sigma factor gene, rpoH2.  

Science.gov (United States)

Exopolysaccharide (EPS) produced by Rhizobium sp. strain TAL1145 has been shown to be essential for effective nodulation on Leucaena leucocephala (leucaena). This paper reports the isolation and characterization of an alternative sigma factor gene, rpoH2, involved in the regulation of EPS synthesis in TAL1145. Disruption of this gene in TAL1145 resulted in a Calcofluor-dim mutant RUH102 that produced approximately 18 % of the amount of EPS made by TAL1145. This mutation did not affect the normal growth of RUH102 in free-living state. RUH102 induced few nitrogen-fixing nodules, resulting in a significant reduction in total nitrogen content in leucaena. It was complemented for EPS production and nodulation by a 2.0 kb HindIII fragment of TAL1145. Sequence analysis of this fragment revealed the rpoH2 ORF of 870 bp that encoded a protein of 32 kDa. Expression of the rpoH2 ORF in Escherichia coli also revealed a 32 kDa protein. A PCR-constructed clone of 1263 bp, containing the rpoH2 ORF and its upstream putative regulatory region, complemented RUH102 for EPS defects. Comparison of the RpoH2 sequence to proteins in the databases showed significant similarity to RpoH-like sigma factors of other Gram-negative bacteria. By constructing several exo : : Tn3Hogus fusions and transferring them to the backgrounds of TAL1145 and RUH102, it was demonstrated that RpoH2 positively regulates the transcription of some exo genes. PMID:15470124

Kaufusi, Pakieli H; Forsberg, L Scott; Tittabutr, Panlada; Borthakur, Dulal

2004-10-01

344

Occurrence of polyamines in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici in response to salt stress.  

Science.gov (United States)

Polyamines (PAs) are low molecular weight aliphatic compounds that have been shown to be an important part of plant responses to salt stress. For that reason in this work we have investigated the involvement of PAs in the response to salt stress in root nodules of Phaseolus vulgaris in symbiosis with Rhizobium tropici. The level and variety of PAs was higher in nodules, compared to leaves and roots, and in addition to the common PAs (putrescine, spermidine and spermine) we found homospermidine (Homspd) as the most abundant polyamine in nodules. UPLC-mass spectrometry analysis revealed the presence of 4-aminobutylcadaverine (4-ABcad), only described in nodules of Vigna angularis before. Indeed, the analysis of different nodular fractions revealed higher level of 4-ABcad, as well as Homspd, in bacteroids which indicate the production of these PAs by the bacteria in symbiosis. The genes involved in PAs biosynthesis in nodules displayed an induction under salt stress conditions which was not consistent with the decline of free PAs levels, probably due to the nitrogen limitations provoked by the nitrogenase activity depletion and/or the conversion of free PAs to theirs soluble conjugated forms, that seems to be one of the mechanisms involved in the regulation of PAs levels. On the contrary, cadaverine (Cad) and 4-ABcad concentrations augmented by the salinity, which might be due to their involvement in the response of bacteroids to hyper-osmotic conditions. In conclusion, the results shown in this work suggest the alteration of the bacteroidal metabolism towards the production of uncommon PAs such as 4-ABcad in the response to salt stress in legume root nodules. PMID:25220497

López-Gómez, Miguel; Cobos-Porras, Libertad; Hidalgo-Castellanos, Javier; Lluch, Carmen

2014-11-01

345

Biodegradation of Selected Nigerian Fruit Peels by the use of a Non-pathogenic Rhizobium species CWP G34B.  

Science.gov (United States)

This study was carried out to determine the ability of Rhizobium species CWP G34B to degrade the peels of selected Nigerian fruits. The potential of the bacterium to digest some carbon sources (lactose, maltose, sucrose and mannitol) and peels of some Nigerian fruits (pineapple, orange, plantain, banana, pawpaw and mango fruits) was investigated by growing the organism on the substances separately after which DNSA reagent method was used to quantify glucose released into the medium. The results showed that the bacterium was able to degrade all the carbohydrates with the highest and the lowest glucose concentrations of 5.52 mg/ml for lactose and 0.50 mg/ml for mannitol. The carbohydrate-catabolic-enzyme (CCE) activity ranged from 0.169 mg/ml to 1.346 mg/ml glucose per mg/ml protein. Mannitol exhibited the highest CCE activity while the lowest activity was observed in the presence of sucrose. The amount of extracellular protein synthesized was highest (9.803 mg/ml) in the presence of maltose and lowest (0.925 mg/ml) in mannitol. The mean polygalacturonase activity was 0.54 unit/ml when the bacterium was grown in pectin in contrast to 0.28 unit/ml when it was grown in mannitol. The bacterium showed ability to breakdown the peels of the Nigerian fruits with the highest capability in banana and pineapple (0.42 and 0.41 mg/ml glucose per mg/ml protein respectively). The fruit-peel-degrading enzyme activity was lowest in orange peel (0.75 unit/ml). PMID:23166567

Esther Boboye, Bolatito; Ajayi, George Olarewaju

2012-01-01

346

Nodulation protein NodL of Rhizobium leguminosarum O-acetylates lipo-oligosaccharides, chitin fragments and N-acetylglucosamine in vitro.  

Science.gov (United States)

Upon induction of their nodulation genes, the root nodule-inducing Rhizobium bacteria produce lipo-oligosaccharide signal molecules. All lipo-oligosaccharides identified from Rhizobium leguminosarum bv. viciae carry an O-acetyl group at the C-6 position of the non-reducing terminal sugar, the presence of which is important for biological activity and host specificity. Previously we showed that a functional nodL gene product is required for the presence of this O-acetyl moiety. The production of polyclonal antibodies against isolated NodL protein, using a NodL-overproducing Escherichia coli strain is described. These antibodies were used (i) to elucidate the subcellular localization of the NodL protein, which appeared to be present in the cytosol, and (ii) for the purification of native NodL protein from E. coli. Here we provide biochemical proof that purified NodL protein has transacetylating activity in vitro with acetyl-CoA as the acetyl donor. NodL protein appeared to be able to acetylate various substrates, such as lipo-oligosaccharides, chitin fragments and N-acetylglucosamine. For chitinpentaose as the substrate we have shown, using mass spectrometry and NMR spectroscopy, that NodL protein substitutes one O-acetyl group at the C-6 position of the non-reducing terminal sugar. PMID:8196551

Bloemberg, G V; Thomas-Oates, J E; Lugtenberg, B J; Spaink, H P

1994-02-01

347

Polymorphic infection and organogenesis patterns induced by a Rhizobium leguminosarum isolate from Lotus root nodules are determined by the host genotype.  

Science.gov (United States)

To sample the natural variation in genes controlling compatibility in the legume-rhizobium symbiosis, we isolated rhizobia from nodules of endemic Lotus species from 21 sites across Europe. The majority of isolates were identified as Mesorhizobium- or Bradyrhizobium-related and formed nitrogen-fixing root nodules on Lotus corniculatus and L. pendunculatus, respectively, thus confirming previously defined cross-inoculation groups. Rhizobium leguminosarum (Rl) strain Norway, isolated from L. corniculatus nodules, displayed an exceptional phenotypic variation on different Lotus genotypes. On L. burttii, Rl Norway formed infected nodules, whereas tumors and elongated infected swellings were induced on L. glaber and L. japonicus ecotype Nepal, respectively. A symbiosis- and Nod-factor-responsive promoter:uidA fusion was strongly and rapidly induced in L. japonicus Gifu, but infection threads or signs of nodule organogenesis were absent. This complex phenotypic pattern was not mimicked by either of three engineered R. leguminosarum bv viciae strains producing different Nod-factor variants. Intriguingly, Rl Norway formed infection threads on Pisum sativum cv Sparkle, but failed to induce organogenesis. Rl Norway thus uncovered variation in symbiotic capabilities among diploid Lotus species and ecotypes that are obscured by optimally adapted M. loti strains. These contrasting infection and organogenesis phenotypes reveal recent diversification of recognition determinants in Lotus. PMID:22950721

Gossmann, Jasmin A; Markmann, Katharina; Brachmann, Andreas; Rose, Laura E; Parniske, Martin

2012-10-01

348

Rhizobium nodulation protein NodA is a host-specific determinant of the transfer of fatty acids in Nod factor biosynthesis.  

Science.gov (United States)

In the biosynthesis of lipochitin oligosaccharides (LCOs) the Rhizobium nodulation protein NodA plays an essential role in the transfer of an acyl chain to the chitin oligosaccharide acceptor molecule. The presence of nodA in the nodABCIJ operon makes genetic studies difficult to interpret. In order to be able to investigate the biological and biochemical functions of NodA, we have constructed a test system in which the nodA, nodB and nodC genes are separately present on different plasmids. Efficient nodulation was only obtained if nodC was present on a low-copy-number vector. Our results confirm the notion that nodA of Rhizobium leguminosarum biovar viciae is essential for nodulation on Vicia. Surprisingly, replacement of R. l. by viciae nodA by that of Bradyrhizobium sp. ANU289 results in a nodulation-minus phenotype on Vicia. Further analysis revealed that the Bradyrhizobium sp. ANU289 NodA is active in the biosynthesis of LCOs, but is unable to direct the transfer of the R. l. by, viciae nodFE-dependent multi-unsaturated fatty acid to the chitin oligosaccharide acceptor. These results lead to the conclusion that the original notion that nodA is a common nod gene should be revised. PMID:8628246

Ritsema, T; Wijfjes, A H; Lugtenberg, B J; Spaink, H P

1996-04-24

349

Micorriza arbuscular e rizóbios no enraizamento e nutrição de mudas de angico-vermelho Arbuscular mycorrhizae and rhizobium in rooting and nutrition of angico-vermelho seedlings  

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Full Text Available O objetivo deste estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs e rizóbio no enraizamento, crescimento e nutrição de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth Brenan propagadas via miniestaquia. Foram utilizadas seis progênies, das quais foram confeccionadas miniestacas com um par de folhas inteiras, bem como tubetes de 55 cm³ contendo substrato comercial Bioplant®. Foram testados quatro tratamentos: 8 kg m-3 de superfosfato simples (SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato e adição de suspensão contendo rizóbios; e 4 kg m-3 de SS e adição de suspensão contendo rizóbios e 5 g de solo contendo esporos de FMAs. Não houve interação entre os tratamentos para percentagem de sobrevivência das miniestacas e percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, na saída da casa de vegetação (30 dias e da casa de sombra (40 dias, provavelmente em função do sistema radicular ainda estar em formação. Houve diferenças entre as progênies para percentagem de sobrevivência das miniestacas, percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, altura, diâmetro de colo e massa seca da parte aérea. As avaliações das características de crescimento das miniestacas enraizadas, principalmente com relação à sobrevivência a pleno sol (140 dias, evidenciam a eficiência dos rizóbios e FMAs na produção de mudas desta espécie. Conclui-se que a associação simbiótica com rizóbio e/ou FMA favorece a produção de mudas de A. macrocarpa via miniestaquia.The objective of this study was to evaluate the effect of inoculation of arbuscular mycorrhizae fungi (AMF and rhizobium on rooting, growth and nutrition of seedlings of angico-red (Anadenanthera macrocarpa (Benth Brenan propagated by minicutting. Six progenies were used, of which were prepared cuttings with a pair of complete leaves. It was used a 55 cm³container filled with commercial substrate Bioplant®. Four treatments were tested: 8 kg m-3 of superphosphate (SS added to substrate; 4 kg m-3 SS added to substrate; 4 kg m-3 SS added to substrate and adition of a suspension solution containing rhizobium; 4 kg m-3 SS and suspension solution containing rhizobium plus 5 g of soil contaminated by AMF spores. There was no interaction among treatments for survival rate of cuttings and roots observed at bottom of the container, evaluated in the greenhouse exit (30 days and the shade house exit (40 days, probably because the root system was still in formation. There were differences among the progeny for survival rate of the shoots, the percentage of cuttings with roots observed at bottom of the container, height, stem diameter and shoot dry weight. The evaluations of the growth characteristics of the cuttings in, particularly with respect to survival at full sun (140 days, demonstrate the efficiency of rhizobium and AMF on seedling production of this species. We conclude that the symbiotic association with rhizobium and / or FMA favors the production of seedlings of A. macrocarpa by minicutting.

Poliana Coqueiro Dias

2012-12-01

350

Micorriza arbuscular e rizóbios no enraizamento e nutrição de mudas de angico-vermelho / Arbuscular mycorrhizae and rhizobium in rooting and nutrition of angico-vermelho seedlings  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo deste estudo foi avaliar o efeito da inoculação dos fungos micorrízicos arbusculares (FMAs) e rizóbio no enraizamento, crescimento e nutrição de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth) Brenan) propagadas via miniestaquia. Foram utilizadas seis progênies, das quais foram [...] confeccionadas miniestacas com um par de folhas inteiras, bem como tubetes de 55 cm³ contendo substrato comercial Bioplant®. Foram testados quatro tratamentos: 8 kg m-3 de superfosfato simples (SS) misturados ao substrato; 4 kg m-3 de SS misturados ao substrato; 4 kg m-3 de SS misturados ao substrato e adição de suspensão contendo rizóbios; e 4 kg m-3 de SS e adição de suspensão contendo rizóbios e 5 g de solo contendo esporos de FMAs. Não houve interação entre os tratamentos para percentagem de sobrevivência das miniestacas e percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, na saída da casa de vegetação (30 dias) e da casa de sombra (40 dias), provavelmente em função do sistema radicular ainda estar em formação. Houve diferenças entre as progênies para percentagem de sobrevivência das miniestacas, percentagem de miniestacas com raízes observadas na extremidade inferior do tubete, altura, diâmetro de colo e massa seca da parte aérea. As avaliações das características de crescimento das miniestacas enraizadas, principalmente com relação à sobrevivência a pleno sol (140 dias), evidenciam a eficiência dos rizóbios e FMAs na produção de mudas desta espécie. Conclui-se que a associação simbiótica com rizóbio e/ou FMA favorece a produção de mudas de A. macrocarpa via miniestaquia. Abstract in english The objective of this study was to evaluate the effect of inoculation of arbuscular mycorrhizae fungi (AMF) and rhizobium on rooting, growth and nutrition of seedlings of angico-red (Anadenanthera macrocarpa (Benth) Brenan) propagated by minicutting. Six progenies were used, of which were prepared c [...] uttings with a pair of complete leaves. It was used a 55 cm³container filled with commercial substrate Bioplant®. Four treatments were tested: 8 kg m-3 of superphosphate (SS) added to substrate; 4 kg m-3 SS added to substrate; 4 kg m-3 SS added to substrate and adition of a suspension solution containing rhizobium; 4 kg m-3 SS and suspension solution containing rhizobium plus 5 g of soil contaminated by AMF spores. There was no interaction among treatments for survival rate of cuttings and roots observed at bottom of the container, evaluated in the greenhouse exit (30 days) and the shade house exit (40 days), probably because the root system was still in formation. There were differences among the progeny for survival rate of the shoots, the percentage of cuttings with roots observed at bottom of the container, height, stem diameter and shoot dry weight. The evaluations of the growth characteristics of the cuttings in, particularly with respect to survival at full sun (140 days), demonstrate the efficiency of rhizobium and AMF on seedling production of this species. We conclude that the symbiotic association with rhizobium and / or FMA favors the production of seedlings of A. macrocarpa by minicutting.

Poliana Coqueiro, Dias; Muriel da Silva Folli, Pereira; Maria Catarina, MegumiKasuya; Haroldo Nogueira de, Paiva; Leandro Silva de, Oliveira; Aloisio, Xavier.

1027-10-01

351

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

352

Un nouvel habitat du Bronze final IIIb dans le Val d’Orléans et ses traces de métallurgie du fer : Bonnée, Les Terres à l’Est du Bourg (Centre, Loiret A new settlement from late Bronze IIIb in the val d’Orléans: Bonnée, Les Terres à l’Est du Bourg (lands to the east of the town (Centre, Loiret  

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Full Text Available La multiplication récente des diagnostics archéologiques autour du petit bourg actuel de Bonnée a permis la détection d’une occupation du Bronze final IIIb (circa 900-750 av. n.-e. sur environ un hectare aux Terres à l’Est du Bourg. Les limites inhérentes à ce type d’intervention réduisent l’interprétation des structures et toute approche spatiale de ce probable habitat repéré. L’étude conjointe des différents mobiliers en particulier céramique et métallurgique, mais aussi le torchis et la faune, atteste de sa culture matérielle et de son intérêt. Ces scories pourraient être parmi les plus anciennes traces en région Centre d’activité métallurgique du fer. Des activités de post-réduction sont avérées et certaines opérations de forgeage sont supposées.La découverte de cet habitat dans ce secteur du lit majeur de la Loire, apporte de nouvelles données concernant l’occupation du sol et ses problématiques évolutives dans le Val d’Orléans sur ces périodes de transition avec le Hallstatt ancien.The recent increase in the archaeological evaluations around the village of Bonnée has enabled the discovery of a final Bronze Age IIIb settlement (circa 900-750 BP on about a hectare of the Terres à l’Est du Bourg. The limits inherent in this type of work restrict the interpretation of structures and all spatial approaches to this likely dwelling. The joint study of the different furnishings, in particular ceramics and metal, but also the cob and fauna, attests to its material culture and its interest. The slag could be amongst the oldest iron metallurgy remains from the Centre region. Some activities of post-forging are proven and certain operations are guessed at. The discovery of this settlement in this sector of the major bed of the Loire, has produced new data concerning the occupation of the land and its evolutionary problems in the valley of Orleans over these periods of transition in the early Hallstatt.

Stéphane Joly

2011-12-01

353

FINAL REPORT  

Energy Technology Data Exchange (ETDEWEB)

We proposed to extend Maurer’s data sets through at least 2005 (to include extreme drought years in the Colorado basin). We updated and verified the forcings for tmin, tmax, and precipitation over the Colorado River basin at 1/8-deg spatial resolution through November 2008, with the potential to alter the resolution as needed (we subsequently extended the Maurer et al data set over the entire continental U.S. at 1/16 degree spatial resolution; see Livneh et al., 2013). We proposed to use either MODIS-based land cover data for recent years, or modification of the existing fixed seasonal cycle used in VIC (based on University of Maryland land cover data) to represent interannual variations in vegetation characteristics such as leaf area index (LAI) particularly in drought years. We assessed model performance with respect to evapotranspiration estimation through comparison of the model predictions with ground observations and in experiments that use time-varying and fixed seasonal LAI cycles (based on University of Maryland land cover data) in a test region of northwestern Mexico where the ground ET observations from eddy covariance tower sites are available for the period from 2001 to 2008 (Tang et al., 2011). We also proposed to implement statistical downscaling with an adjustment to constrain precipitation changes at the GCM level. These simulations were performed, using 20 IPCC AR4 GCMs over the Colorado River basin with two global emissions scenarios, and are reported in Vano et al., 2014. Task 2: Coupled model implementation We proposed to implement the “standard” climate version of WRF, as used by collaborator Ruby Leung in NARCCAP simulations (see Section 5.4), and perform tests to assure that model output for runs equivalent to NARCCAP Phase 1 (reanalysis boundary conditions) are consistent. We proposed do test sensitivity to higher spatial resolution. We made a run of 11 years’ length with the “standard” version of WRF, forced by NCEP/DOE with the same spatial resolution as WRF in NARCCAP, with a slightly different domain designed to cover the Colorado River basin. We also compared the sensitivity of standard WRF simulations to different spatial resolutions (50 km, 25 km and 16 km). We proposed to implement the WRF-VIC version, and to evaluate differences between the “standard” WRF version (with CLM as the land scheme) and WRF-VIC. As part of a companion project (Regional Arctic Climate Model; RACM), we have linked the macroscale hydrologic model VIC (Variable Infiltration Capacity) with WRF through the CCSM coupling architecture CPL7. We decided to defer making new model runs with VIC over the Colorado basin and rather to focus on analysis of NARCCAP results. Our preliminary results from analysis of NARCCAP current and future climate results (reported in Gao et al., 2011) indicate that CRCM has a cold bias; HRM3 has a warm bias; and ECPC and CRCM have a wet bias over the Colorado River basin. Task 3: Retrospective coupled model simulations We proposed to compare the climatology of key land surface and atmospheric variables from the retrospective RCM and GCM runs, as well as 1/8-degree as the historical North American Land Data Assimilation System dataset (Maurer et al., 2002) to evaluate the ability of each of the RCMs and GCMs to reproduce characteristics of observed climate. In addition to the NARCCAP runs analyzed under Task 2, we also evaluated an ECHAM5/WRF run performed by Eric Salathe and HadCM3/WRF run performed by Francina Dominguez (University of Arizona). Results of the retrospective RCM runs indicate that they capture the primary features of the observed land–surface water budget and surface temperature better than their host GCMs. Although the RCMs do not have significantly improved simulations of precipitation relative to the GCMs, their ability to better represent surface temperature in mountainous regions has important effects on simulations of evapotranspiration, snowpack, and runoff. This improved skill in simulating temperature is important for detecting climate change signals

Lettenmaier, Dennis [University of Washsington

2012-05-26

354

Regulation of flagellar, motility and chemotaxis genes in Rhizobium leguminosarum by the VisN/R-Rem cascade.  

Science.gov (United States)

In this paper, we describe the regulatory roles of VisN, VisR and Rem in the expression of flagellar, motility and chemotaxis genes in Rhizobium leguminosarum biovar viciae strains VF39SM and 3841. Individual mutations in the genes encoding these proteins resulted in a loss of motility and an absence of flagella, indicating that these regulatory genes are essential for flagellar synthesis and function. Transcriptional experiments involving gusA-gene fusions in wild-type and mutant backgrounds were performed to identify the genes under VisN/R and Rem regulation. Results showed that the chemotaxis and motility genes of R. leguminosarum could be separated into two groups: one group under VisN/R-Rem regulation and another group that is independent of this regulation. VisN and VisR regulate the expression of rem, while Rem positively regulates the expression of flaA, flaB, flaC, flaD, motA, motB, che1 and mcpD. All of these genes except mcpD are located within the main motility and chemotaxis gene cluster of R. leguminosarum. Other chemotaxis and motility genes, which are found outside of the main motility gene cluster (che2 operon, flaH for VF39SM, and flaG) or are plasmid-borne (flaE and mcpC), are not part of the VisN/R-Rem regulatory cascade. In addition, all genes exhibited the same regulation pattern in 3841 and in VF39SM, except flaE and flaH. flaE is not regulated by VisN/R-Rem in 3841 but it is repressed by Rem in VF39SM. flaH is under VisN/R-Rem regulation in 3841, but not in VF39SM. A kinetics experiment demonstrated that a subset of the flagellar genes is continuously expressed in all growth phases, indicating the importance of continuous motility for R. leguminosarum under free-living conditions. On the other hand, motility is repressed under symbiotic conditions. Nodulation experiments showed that the transcriptional activators VisN and Rem are dramatically downregulated in the nodules, suggesting that the symbiotic downregulation of motility-related genes could be mediated by repressing the expression of VisN/R and Rem. PMID:20203055

Tambalo, Dinah D; Del Bel, Kate L; Bustard, Denise E; Greenwood, Paige R; Steedman, Audrey E; Hynes, Michael F

2010-06-01

355

Rhizobium leguminosarum contains a group of genes that appear to code for methyl-accepting chemotaxis proteins.  

Science.gov (United States)

Methyl-accepting chemotaxis proteins (MCPs) play important roles in the chemotactic response of many bacteria. Oligonucleotide primers designed to amplify the conserved signalling domain of MCPs by PCR were used to identify potential MCP-encoding genes in Rhizobium leguminosarum. Using a PCR-derived probe created from these primers a genomic library of R. leguminosarum VF39SM was screened; at least five putative MCP-encoding genes (termed mcpB to mcpF) were identified and isolated from the library. One of these putative genes (mcpC) is located on one of the indigenous plasmids of VF39SM. Fifteen different cosmids showing homology to an mcpD probe were also isolated from a genomic library. The complete DNA sequences of mcpB, mcpC and mcpD were obtained. All three genes code for proteins with characteristics typical of MCPs. However, the protein encoded by mcpB has a relatively large periplasmic domain compared to that in other MCPs. Partial DNA sequences of mcpE and mcpF had strong similarity to sequences from the methylation domains of known MCPs. Mutants defective in mcpB, mcpC, mcpD or mcpE were created using insertional mutagenesis strategies. Mutation of mcpB resulted in impairment of chemotaxis to a wide range of carbon sources on swarm plates; phenotypes for the other three mutants have yet to be elucidated. The mcpB, mcpC and mcpD mutants were tested for loss of nodulation competitiveness. When co-inoculated with the wild-type, the mcpB and mcpC mutants formed fewer nodules than the wild-type, whereas the mcpD mutant was just as competitive as the wild-type. The results overall suggest that R. leguminosarum possesses mcp-like genes, and that at least some of these play a role in early steps in the plant-microbe interaction. PMID:9695927

Yost, C K; Rochepeau, P; Hynes, M F

1998-07-01

356

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

357

Final Report  

Energy Technology Data Exchange (ETDEWEB)

We participated in a FASTER SCM intercomparison for which we ran our SCM for 3 years at the SGP to analyze statistics of the precipitation field (Song et al., 2013). An important feature of these simulations was the use of relaxation forcing to observed T, q, which decouples the model convection from the forcing and allows precipitation errors to emerge. Because the GISS cumulus parameterization includes a trigger that prevents convection until sufficient lifting is present, and because convection at the SGP is usually triggered by mesoscale motions that are not represented in the forcing when relaxation is applied, the duration of SCM precipitation is shorter than observed (Del Genio and Wolf, 2012) and thus its mean precipitation less than observed. However, its diurnal cycle phase is correct, and it is the only operational cumulus parameterization in the intercomparison that does not produce excessive warm season precipitation under weak large-scale forcing conditions.

Bauer, Susanne

2015-02-09

358

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

359

Molecular basis of a microbe-mediated enhancement of symbiotic N/sub 2/-fixation. [Rhizobium meliloti; Pseudomonas syringae pv. tabaci  

Energy Technology Data Exchange (ETDEWEB)

Improvement of biological nitrogen fixation represents a potential source of both increased food production and decreased dependence on costly chemical fertilizer. They report the results of an investigation of the molecular basis of a unique, microbial-mediated mechanism for increased growth and nitrogen fixation rates in alfalfa. Inoculation of alfalfa plants with both Rhizobium meliloti and Pseudomonas syringae pv tabaci provides increased growth and N/sub 2/-fixation rates of alfalfa. Tabaci produces tabtoxinine-..beta..-lactam (T..beta..L), an exocellular product and glutamine synthetase (GS) inhibitor. The association of this pathogen with nodulating alfalfa plants appears to alter the normal regulation of nitrogen fixation such that nitrogenase activity is stimulated and GS activity is inhibited. Studies of the soluble amino acids in these nodules and the activities of the ammonia assimilatory enzymes indicate alternative pathways of ammonia assimilation are being employed.

Unkefer, P.J.; Knight, T.J.

1987-04-01

360

Occurrence of enzymes involved in biosynthesis of indole-3-acetic acid from indole-3-acetonitrile in plant-associated bacteria, Agrobacterium and Rhizobium.  

Science.gov (United States)

The occurrence of a hitherto unknown pathway involving the action of two enzymes, a nitrile hydratase and an amidase for the biosynthesis of indole-3-acetic acid was discovered in phytopathogenic bacteria Agrobacterium tumefaciens and in leguminous bacteria Rhizobium. The nitrile hydratase acting on indole-3-acetonitrile was purified to homogeneity through only two steps from the cell-free extract of A. tumefaciens. The molecular mass of the purified enzyme estimated by HPLC was about 102 kDa, and the enzyme consisted of four subunits identical in molecular mass. The enzyme exhibited a broad absorption spectrum in the visible range with absorption maxima at 408 nm and 705 nm, and it contained cobalt and iron. The enzyme stoichiometrically catalyzed the hydration of indole-3-acetonitrile into indole-3-acetamide with a specific activity of 13.7 mol per min per mg and a Km of 7.9 microM. PMID:11607511

Kobayashi, M; Suzuki, T; Fujita, T; Masuda, M; Shimizu, S

1995-01-31

361

Compatibilidade entre a inoculação de rizóbios e fungicidas aplicados em sementes de feijoeiro-comum / Compatibility between rhizobium inoculation and fungicide application in seeds of common beans  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O objetivo do presente estudo foi avaliar os efeitos do tratamento de sementes de feijoeiro com diferentes fungicidas na sobrevivência de estirpe de Rhizobium tropici (SEMIA 4077) e Rhizobium freirei (SEMIA 4080), na nodulação das plantas e na produtividade da cultura. Foram conduzidos dois ensaios [...] em substrato esterilizado, sob condições de casa de vegetação e um ensaio no campo experimental da Embrapa Agropecuária Oeste, em Dourados, MS, num Latossolo Vermelho distroférrico típico. Os fungicidas (princípios ativos) utilizados nos ensaios foram: (1) carbendazim + tiram (Produto A); (2) carbendazim + tiram (Produto B); (3) carboxin + tiram; (4) fludioxonil + metalaxil-M; (5) fludioxonil + metalaxil-M + tiabendazol; (6) fluazinam + tiofanato metílico; (7) fipronil + tiofanato metílico + piraclostrobina; (8) clorotalonil + tiofanato metílico. A sobrevivência das estirpes de R. tropici inoculadas nas sementes de feijoeiro foi afetada pela aplicação dos fungicidas, principalmente por aqueles com modo de ação de contato. Observou-se ainda, com a aplicação dos fungicidas, redução na nodulação das plantas de feijoeiro, especialmente da massa nodular, tanto nos ensaios conduzidos em substrato esterilizado, em casa de vegetação, quanto no experimento a campo, onde também observou-se redução na produtividade do feijoeiro pela aplicação da maioria dos fungicidas avaliados. Os fungicidas que mais afetaram o rendimento de grãos foram carbendazim + tiram (Produto B) e carboxin + tiram. Os produtos fipronil + tiofanato metílico + piraclostrobina, fludioxonil + metalaxil-M + tiabendazol e fludioxonil + metalaxil-M não afetaram a produtividade da cultura, embora a massa seca de nódulos tenha sido reduzida em todos os ensaios. Abstract in english The aim of this study was to evaluate the effects of treatment of common bean seeds with different fungicides on the survival of strains of Rhizobium tropici (SEMIA 4077) and Rhizobium freirei (SEMIA 4080), as well as on plant nodulation and on crop yield. Two experiments were carried out in sterili [...] zed substrate, under greenhouse conditions and in the experimental field of Embrapa Western Agriculture, in Dourados, Mato Grosso do Sul State, in a typical Oxisol. The fungicides (active ingredients) used in the experiments were: (1) carbendazim + thiram (Product A), (2) carbendazim + thiram (Product B), (3) carboxin + thiram, (4) fludioxonil + metalaxyl-M, (5) fludioxonil + metalaxyl-M + thiabendazole, (6) fluazinam + methyl thiophanate, (7) fipronil + methyl thiophanate + pyraclostrobin, (8) chlorothalonil + methyl thiophanate. The survival of R. tropici strains inoculated in bean seeds was affected by the application of fungicides, especially contact fungicides. In addition, fungicide application led to a reduction in the nodulation of bean plants, especially for nodular mass, either in assays carried out on sterilized substrate, in a greenhouse, or in the field experiment, where grain yield reduction was also noted with the use of most evaluated fungicides. The fungicides that mostly affected grain yield were carbendazim + thiram (Product B) and carboxin + thiram. The products fipronil + thiophanate methyl + pyraclostrobin, fludioxonil + metalaxyl-M + thiabendazole and fludioxonil + metalaxyl-M did not affect the crop yield, although the dry weight of nodules was reduced in all trials.

Maurício Rocha, Kintschev; Augusto César Pereira, Goulart; Fábio Martins, Mercante.

2014-12-01

362

Resposta da cultura do feijoeiro à adubação nitrogenada e à inoculação com rizóbio / Response of common bean crop to nitrogen fertilization and rhizobium inoculation  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O manejo adequado da adubação nitrogenada representa uma das principais dificuldades da cultura do feijoeiro (Phaseolus vulgaris L.). No entanto, a fixação biológica de nitrogênio é uma fonte alternativa de suprimento deste nutriente à cultura. O presente estudo teve como objetivo avaliar a resposta [...] do feijoeiro à inoculação com rizóbio e ao parcelamento de fertilizante nitrogenado em termos de nodulação das plantas e produtividade de grãos da cultura, bem como a viabilidade econômica da aplicação de fertilizante nitrogenado e, ou, inoculação com rizóbio em feijoeiro. O experimento foi conduzido num Latossolo Vermelho distroférrico, em Dourados, MS. O delineamento experimental utilizado foi o de blocos casualizados, com seis repetições. Os sete tratamentos consistiram da aplicação parcelada de fertilizante nitrogenado em diferentes doses (0, 20, 40, 80 e 160 kg ha-1 de N como ureia) na cultura do feijoeiro, cv. Pérola, além de controles com inoculação de Rhizobium tropici combinada ou não com aplicação de 20 kg ha-1 de N. A análise econômica foi efetuada considerando os custos da ureia e sua aplicação a lanço, além do custo do inoculante; os demais custos não foram considerados, por não haver diferença entre os diferentes tratamentos. Foram obtidos o acréscimo de produtividade, o custo de produção, o acréscimo da receita bruta e o acréscimo da receita líquida dos tratamentos, em relação à testemunha sem inoculação e sem adubação nitrogenada. Embora a nodulação das plantas não tenha sido alterada pelos tratamentos, verificou-se tendência de redução conforme o aumento da dose de N aplicada. A inoculação com rizóbio selecionado promoveu rendimentos de grãos de feijoeiros equivalentes à aplicação de 80 kg ha-1 de N. Quando acrescida da adubação com 20 kg ha-1 de N no plantio, a inoculação com rizóbio propiciou acréscimo de receita líquida semelhante à aplicação de 160 kg ha-1 de N e superior ao tratamento com a adubação de 20 kg ha-1 de N sem inoculação, evidenciando a sua importância para obtenção de maior rentabilidade na cultura do feijoeiro. Abstract in english Adequate management of nitrogen fertilizer is one of the main difficulties on common bean (Phaseolus vulgaris L.) crop. However, the biological N2 fixation is an alternative source of N supply to this crop. This study had the purpose to evaluate the response of common bean to rhizobium inoculation a [...] nd split application of N fertilizer in terms of plant nodulation and grain yield. Besides, this study aimed to evaluate the economic viability of using N fertilizer application and/or rhizobium inoculation on the plants. The experiment was carried out on a typic Haplustox in Dourados, Mato Grosso do Sul State. The experimental design was a completely randomized block with six replications. The seven treatments consisted of different levels of N fertilizer (0, 20, 40, 80, and 160 kg ha-1 N as urea) applied to common bean, cultivar Pérola, and control treatments with R. tropici inoculation with or without application of 20 kg ha-1 N. In the economic analysis, the cost of urea, broadcast application, and cost of inoculant were taken into account. No other costs were considered since the treatments did not differ. Increases in grain yield, production cost, net and gross income, in relation to the control without inoculation and without nitrogen were obtained. The effect of inoculation of selected rhizobia on bean grain yield was similar to the application of 80 kg ha-1 N. When supplied with 20 kg ha-1 N at sowing, rhizobium inoculation increased grain yield and net income similarly to the application of 160 kg ha-1 N and more than the treatment of 20 kg ha-1 N without inoculant, which demonstrates the importance of the inoculant for an enhanced crop profitability.

Rodrigo de, Pelegrin; Fábio Martins, Mercante; Ilda Miyuki Nakase, Otsubo; Auro Akio, Otsubo.

2009-02-01

363

Uso de micorrizas e rizóbio em cultivo consorciado de eucalipto e sesbânia: II - Absorção e eficiência de utilização de fósforo e frações fosfatadas Use of mycorrhizas and rhizobium in intercropping system of eucalyptus and sesbania: II - Phosphorus uptake and efficiency of use and phosphate phosphate -fractions  

Directory of Open Access Journals (Sweden)

Full Text Available Realizou-se um experimento em casa de vegetação com o objetivo de avaliar os efeitos de fungos micorrízicos arbusculares (FMAs e rizóbio na absorção e eficiência de utilização de P e nas frações fosfatadas em mudas de Eucalyptus grandis, cultivadas em consorciação com Sesbania virgata. Os tratamentos foram: inoculação ou não com FMAs em ambas as espécies de plantas e inoculação ou não com rizóbio na S. virgata, com quatro repetições. Ambas as plantas foram cultivadas em vasos de 6 L de capacidade, durante 100 dias, quando foram colhidas. A inoculação com FMAs ou FMAs + rizóbio aumentou o conteúdo de P no eucalipto, enquanto a inoculação com rizóbio, FMAs ou FMAs + rizóbio aumentou a eficiência de utilização de P. Nas frações de P, avaliadas nas folhas de eucalipto, observou-se aumento do fósforo total solúvel em ácido (PST nos tratamentos com inoculação de rizóbio ou FMAs + rizobio. Nos tratamentos com inoculação com rizóbio, FMAs, FMAs+rizóbio ou sem inoculação, observou-se que 81, 32, 91 e 68%, respectivamente, do PST foram encontrados como fósforo orgânico (Po. Em uma avaliação conjunta das frações fosfatadas e do conteúdo de P na parte aérea do eucalipto, o que aparentemente influenciou o aumento do PST e do Po não foi o conteúdo interno de P na planta, mas, sim, a inoculação do rizóbio na sesbânia.The effects of arbuscular mycorrhizal fungi (AMF and Rhizobium on P uptake and efficiency of use, as well as on the P fractions of Eucalyptus grandis grown in an intercropping system with Sesbania virgata were evaluated under greenhouse conditions. The treatments were: with or without inoculation with AMF of both plant species and with or without inoculation with Rhizobium of S. virgata plants only, in four replications. The two plant species were grown together in pots with a volume of 6 L for 100 days. Inoculations with AMF or with AMF + Rhizobium increased the P content in Eucalyptus plants, while inoculations with Rhizobium, AMF, or with AMF + Rhizobium increased the P utilization efficiency. An increase of total acid-soluble P (PTS in the treatments inoculated with Rhizobium or AMF + Rhizobium was observed in the P fractions of the analyzed Eucalyptus plant leaves. In the inoculation treatments with Rhizobium, AMF, and AMF + Rhizobium, and the control (uninoculated 81, 32, 91, and 68%, respectively, of the PST in the leaves of Eucalyptus plants were found in organic-P (Po form. An evaluation of both the P fractions and P contents of Eucalyptus shoots suggests that the increase of PST and organic-P was caused by the inoculation of Rhizobium in sesbania plants, and not by the internal P plant content.

L. A. Rodrigues

2003-08-01

364

Final Report  

Energy Technology Data Exchange (ETDEWEB)

Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

Webb, Robert C. [Texas A& M University; Kamon, Teruki [Texas A& M University; Toback, David [Texas A& M University; Safonov, Alexei [Texas A& M University; Dutta, Bhaskar [Texas A& M University; Dimitri, Nanopoulos [Texas A& M University; Pope, Christopher [Texas A& M University; White, James [Texas A& M University

2013-11-18

365

Characterization and functional analysis of seven flagellin genes in Rhizobium leguminosarum bv. viciae. Characterization of R. leguminosarum flagellins  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Rhizobium leguminosarum bv. viciae establishes symbiotic nitrogen fixing partnerships with plant species belonging to the Tribe Vicieae, which includes the genera Vicia, Lathyrus, Pisum and Lens. Motility and chemotaxis are important in the ecology of R. leguminosarum to provide a competitive advantage during the early steps of nodulation, but the mechanisms of motility and flagellar assembly remain poorly studied. This paper addresses the role of the seven flagellin genes in producing a functional flagellum. Results R. leguminosarum strains 3841 and VF39SM have seven flagellin genes (flaA, flaB, flaC, flaD, flaE, flaH, and flaG, which are transcribed separately. The predicted flagellins of 3841 are highly similar or identical to the corresponding flagellins in VF39SM. flaA, flaB, flaC, and flaD are in tandem array and are located in the main flagellar gene cluster. flaH and flaG are located outside of the flagellar/motility region while flaE is plasmid-borne. Five flagellin subunits (FlaA, FlaB, FlaC, FlaE, and FlaG are highly similar to each other, whereas FlaD and FlaH are more distantly related. All flagellins exhibit conserved amino acid residues at the N- and C-terminal ends and are variable in the central regions. Strain 3841 has 1-3 plain subpolar flagella while strain VF39SM exhibits 4-7 plain peritrichous flagella. Three flagellins (FlaA/B/C and five flagellins (FlaA/B/C/E/G were detected by mass spectrometry in the flagellar filaments of strains 3841 and VF39SM, respectively. Mutation of flaA resulted in non-motile VF39SM and extremely reduced motility in 3841. Individual mutations of flaB and flaC resulted in shorter flagellar filaments and consequently reduced swimming and swarming motility for both strains. Mutant VF39SM strains carrying individual mutations in flaD, flaE, flaH, and flaG were not significantly affected in motility and filament morphology. The flagellar filament and the motility of 3841 strains with mutations in flaD and flaG were not significantly affected while flaE and flaH mutants exhibited shortened filaments and reduced swimming motility. Conclusion The results obtained from this study demonstrate that FlaA, FlaB, and FlaC are major components of the flagellar filament while FlaD and FlaG are minor components for R. leguminosarum strains 3841 and VF39SM. We also observed differences between the two strains, wherein FlaE and FlaH appear to be minor components of the flagellar filaments in VF39SM but these flagellin subunits may play more important roles in 3841. This paper also demonstrates that the flagellins of 3841 and VF39SM are possibly glycosylated.

Tambalo Dinah D

2010-08-01

366

C. Petrone et al.: "Magnetic measurement of the model magnet QD0 designed for the CLIC final focus beam transport line." CERN TE-MSC Internal Note, EDMS Nr: 1184196  

CERN Document Server

This note presents the results of the magnetic measurements performed on QD0, model magnet for the final focus transport line for CLIC (Fig. 1). This high-gradient, hybrid quadrupole has a yoke length of 0.1 m and an aperture of 8.3 mm. ND2Fe14B Permanent magnet blocks provide a gradient of 150 T/m, which can be further increased to 530 T/m when the four coils are excited to 18.3 A. The request was to measure the strength of the field and the multipole coefficients at different currents. The measurement of the field strength, by means of the single stretched wire system, was done in December 2011 in the I8 laboratory. The measurement of the multipole was done by means of the oscillating wire system [1][2].

Arpaia, Pasquale; Petrone, Carlo; Russenschuck, Stephan; Walckiers, Louis

2012-01-01

367

Final environmental statement related to the operation of Catawba Nuclear Station, Units 1 and 2. Docket Nos. 50-413 and 50-414, Duke Power Company, et al  

International Nuclear Information System (INIS)

This Final Environmental Statement contains the second assessment of the environmental impact associated with the operation of the Catawba Nuclear Station, Units 1 and 2, pursuant to the National Environmental Policy Act of 1969 (NEPA) and 10 CFR 51, as amended, of the NRC regulations. This statement examines: the affected environment, environmental consequences and mitigating actions, and environmental and economic benefits and costs. Land use and terrestrial and aquatic-ecological impacts will be small. Operational impacts to historic and archeological sites will be negligible. The effects of routine operations, energy transmission, and periodic maintenance of rights-of-way and transmission facilities should not jeopardize any populations of endangered or threatened species. No significant impacts are anticipated from normal operational releases of radioactivity. The risk associated with accidental radiation exposure is very low. The net socioeconomic effects of the project will be beneficial

368

Protein crosslinking studies suggest that Rhizobium meliloti C4-dicarboxylic acid transport protein D, a sigma 54-dependent transcriptional activator, interacts with sigma 54 and the beta subunit of RNA polymerase.  

OpenAIRE

Rhizobium meliloti C4-dicarboxylic acid transport protein D (DCTD) activates transcription by a form of RNA polymerase holoenzyme that has sigma 54 as its sigma factor (referred to as E sigma 54). DCTD catalyzes the ATP-dependent isomerization of closed complexes between E sigma 54 and the dctA promoter to transcriptionally productive open complexes. Transcriptional activation probably involves specific protein-protein interactions between DCTD and E sigma 54. Interactions between sigma 54-de...

Lee, J. H.; Hoover, T. R.

1995-01-01

369

Associative Effect of Phosphate Dissolving Fungi, Rhizobium and Phosphate Fertilizer on Some Soil Properties, Yield Components and the Phosphorus and Nitrogen Concentration and Uptake by Vicia faba L. Under Field Conditions  

OpenAIRE

The effect of interactions between three phosphate-dissolving fungi (PDF) (Aspergillus niger, A. fumigatus and Penicillium pinophilum) and Rhizobium leguminosarum biovar viciae (RH) was studied on some soil chemical properties, phosphorus and nitrogen uptake and yield of faba beans (Vicia faba L.). Analysis of the soil after crop harvest indicated that the inoculation with PDF and RH significantly increased the levels of soil available P, mineral N (NH4...

Mehana, T. A.; Abdul Wahid, O. A.

2002-01-01

370

Using Arbuscular Mycorrhizal Fungi and Rhizobium leguminosarum Biovar phaseoli Against Sclerotinia sclerotiorum (Lib.) de Bary in the Common Bean (Phaseolus vulgaris L.)  

OpenAIRE

In this study, the effects of Arbuscular Mycorrhizal Fungi (AMF) Glomus mosseae (Gm), Glomus fasciculatum (Gf) and Rhizobium leguminosarum biovar phaseoli (Rlp), which are the important members of rhizosphere and biological control agents, were examined on the patho-system of Sclerotinia sclerotiorum (Lib.) de Bary (Ss) and common bean. The colonization and nodulation of two biological control agents exhibited differences as a result of reciprocal interactio...

Aysan, E.; Demir, S.

2009-01-01

371

The application of isotopic ({sup 32}P and {sup 15}N) dilution techniques to evaluate the interactive effect of phosphate-solubilizing rhizobacteria, mycorrhizal fungi and Rhizobium to improve the agronomic efficiency of rock phosphate for legume crops  

Energy Technology Data Exchange (ETDEWEB)

A pot experiment was designed to evaluate the interactive effects of multifunctional microbial inoculation treatments and rock phosphate (RP) application on N and P uptake by alfalfa through the use of {sup 15}N and {sup 32}P isotopic dilution approaches. The microbial inocula consisted of a wild type (WT) Rhizobium meliloti strain, the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, and a phosphate solubilizing rhizobacterium (Enterobacter sp.). Inoculated microorganisms were established in the root tissues and/or in the rhizosphere soil of alfalfa plants (Medicago sativa L.). Improvements in N and P accumulation in alfalfa corroborate beneficial effects of Rhizobium and AM interactions. Inoculation with selected rhizobacteria improved the AM effect on N or P accumulation in both the RP-added soil and in the non RP-amended controls. Measurements of the {sup 15}N/{sup 14}N ratio in plant shoots indicate an enhancement of the N{sub 2} fixation rates in Rhizobium-inoculated AM-plants, over that achieved by Rhizobium in non-mycorrhizal plants. Whether or not RP was added, AM-inoculated plants showed a lower specific activity ({sup 32}P/{sup 31}P) than did their comparable non-mycorrhizal controls, suggesting that the plant was using otherwise unavailable P sources. The phosphate-solubilizing, AM-associated, microbiota could in fact release phosphate ions, either from the added RP or from the indigenous 'less-available' soil phosphate. A low Ca concentrations in the test soil may have benefited P solubilization. Under field conditions, the inoculation with AM fungi significantly increased plant biomass and N and P accumulation in plant tissues. Phosphate-solubilizing rhizobacteria improved mycorrhizal responses in soil dually receiving RP and organic matter amendments. Organic matter addition favoured RP solubilization. This, together with a tailored microbial inoculation, increased the agronomic efficiency of RP in the test soil that was Ca deficient at neutral pH. (author)

Barea, J.M. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain)]. E-mail: jmbarea@eez.csic.es; Toro, M.; Azcon, R. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain); Orozco, M.O. [Instituto de Sistematica y Ecologia, Academia Cubana de Ciencias, Habana (Cuba); Campos, E. [Departamento de Ciencias de la Tierra y Quimica Ambiental Estacion Experimental del Zaidin (CSIC), Granada (Spain); Azcon, R. [Departamento de Microbiologia del Suelo y Sistemas Simbioticos (Spain)

2002-05-15

372

The application of isotopic (32P and 15N) dilution techniques to evaluate the interactive effect of phosphate-solubilizing rhizobacteria, mycorrhizal fungi and Rhizobium to improve the agronomic efficiency of rock phosphate for legume crops  

International Nuclear Information System (INIS)

A pot experiment was designed to evaluate the interactive effects of multifunctional microbial inoculation treatments and rock phosphate (RP) application on N and P uptake by alfalfa through the use of 15N and 32P isotopic dilution approaches. The microbial inocula consisted of a wild type (WT) Rhizobium meliloti strain, the arbuscular mycorrhizal (AM) fungus Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe, and a phosphate solubilizing rhizobacterium (Enterobacter sp.). Inoculated microorganisms were established in the root tissues and/or in the rhizosphere soil of alfalfa plants (Medicago sativa L.). Improvements in N and P accumulation in alfalfa corroborate beneficial effects of Rhizobium and AM interactions. Inoculation with selected rhizobacteria improved the AM effect on N or P accumulation in both the RP-added soil and in the non RP-amended controls. Measurements of the 15N/14N ratio in plant shoots indicate an enhancement of the N2 fixation rates in Rhizobium-inoculated AM-plants, over that achieved by Rhizobium in non-mycorrhizal plants. Whether or not RP was added, AM-inoculated plants showed a lower specific activity (32P/31P) than did their comparable non-mycorrhizal controls, suggesting that the plant was using otherwise unavailable P sources. The phosphate-solubilizing, AM-associated, microbiota could in fact release phosphate ions, either from the added RP or from the indigeither from the added RP or from the indigenous 'less-available' soil phosphate. A low Ca concentrations in the test soil may have benefited P solubilization. Under field conditions, the inoculation with AM fungi significantly increased plant biomass and N and P accumulation in plant tissues. Phosphate-solubilizing rhizobacteria improved mycorrhizal responses in soil dually receiving RP and organic matter amendments. Organic matter addition favoured RP solubilization. This, together with a tailored microbial inoculation, increased the agronomic efficiency of RP in the test soil that was Ca deficient at neutral pH. (author)

373

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

OpenAIRE

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 resist...

Shahid Shaukat, S.; Siddiqui, Imran A.; Maria Hamid; Ghazala Habib Khan; Syed Azhar Ali

2002-01-01

374

Final Report  

Energy Technology Data Exchange (ETDEWEB)

Final report for program on the study of structure and properties of epitaxial oxide films. The defect structure of epitaxial oxide thin films was investigated. Both binary and complex oxides were studied. Epitaxial oxides were synthesized by organometallic chemical vapor deposition (OMCVD). This technique has been found to be highly versatile for the synthesis of a wide range of epitaxial oxide including dielectrics, ferroelectrics and high T{sub c} superconductors. Systems investigated include the binary oxides ZnO and TiO{sub 2} and ferroelectric oxides BaTiO{sub 3}, BaSrTiO{sub 3} and KNbO{sub 3}. Techniques used to evaluate the defect structure included deep level transient spectroscopy (DLTS), photocapacitance spectroscopy, and photoluminescence (PL) spectroscopy. High purity, stoichiometric oxide films were deposited and their defect structure evaluated. Epitaxial ZnO was deposited at temperatures as low as 250 C. PL indicated only near band edge ultraviolet emission showing that both extrinsic and intrinsic point defects could be significantly lowered in OMCVD derived thin films compared to that of the bulk. This presumably was a result of low deposition temperatures and high purity starting materials. Ferroelectric oxides epitaxial thin films of BaTiO{sub 3} and the solid solution BaSrTiO{sub 3} were synthesized and the defect structure determined. Photocapacitance spectroscopy was developed to quantify electrically active defects in the oxides. Defects with concentrations as low as 10{sup 14} cm{sup -3} were observed and their properties determined. A new model was developed for the electronic transport properties of intrinsic and extrinsic BaTiO{sub 3}. A transport model was proposed whereby conduction in La doped films occurs via hopping in localized states within a pseudogap formed between a lower Hubbard band and the conduction band edge. The influence of the size effect on the ferroelectric phase transition in the thin films was investigated. The Curie temperature shifted more than 100 C as a result of strain stabilization of the low symmetry phase. The dielectric properties of BaTiO{sub 3} showed a strong thickness dependence for films ranging from 15 to 320 nm. The dynamic dielectric and non-linear optical relaxation response of the ferroelectric thin films was studied over nine orders of magnitude in time from 1 nsec to 1 sec. A power law dependence of the relaxation response on time was observed and a model developed. The dynamic response was analyzed in terms of relaxation of ferroelectric domains with a continuous size distribution. Domain size ranged from nanometers to microns. This continuous size distribution also leads to a diffuse phase transition as observed for the thin films.

Wessels, B. W.

2002-08-02

375

Final report  

Energy Technology Data Exchange (ETDEWEB)

In July of 2000, we performed another field bacterial injection experiment at the DOE study site in South Oyster, Virginia. This year the injection was performed at the site named SOFA. In parallel fashion to the previous year's experiment at the NC site, we collected samples to quantify protists before and after injection of bacteria. Two bacterial strains, DA001 and iron-reducing bacterium OY107, were co-injected with a bromide tracer (100 mg per liter) into the suboxic site flow cell during a 12-hour pulse. The bacteria were marked with two different viable fluorescent stains (50% green OY107 and 50% red DA001), and the concentration of each strain in the injectate was approximately 5.0 x 10{sup 7} cells per ml. Prior to the injection, a forced gradient had been established. As the concentration of DA001 decreased following breakthrough, the predator populations increased in number (maximum concentration of 3 x 10{sup 3} protists per ml). The response of the protists was qualitatively similar to the response we observed in the previous year's experiment at the NC site. Unfortunately, post-injection coring at the SOFA site forced relocation of sampling wells and the resultant data set is less complete than for the NC site. Calculations of bacteria lost to predation are ongoing. Application of molecular tools to detect microorganisms has become increasingly important and widely adopted because of its sensitivity and specificity, both of which can be much greater than that resolved by conventional microscopy. To this end, we have endeavored to incorporate these methods into our research. First, we designed polymerase chain reaction (PCR) primers specific for flagellates by examining small subunit ribosomal DNA (SSrDNA) of more than 20 strains of flagellates. Conservative regions of base sequences were selected and primers were synthesized at Gibbco Inc. In addition, we have had additional primer sets synthesized, ones conservative for eukaryotes. Second, two species of flagellates, Spumella sp. and Bodo sp. (identifications are tentative) were isolated from South Oyster sediments by repetitive serial dilution/extinction method. Protistan cells were cultured with Cereal leaf Prescott medium and pelleted by centrifugation. Protistan DNAs were extracted with a DNA extraction kit (Sigma Co.) and the sequencing of their SSrDNA is underway. Finally, to follow up on our collaboration of Dr. Bill Johnson (Univ. of Utah), one of the co-PIs under the same NABIR umbrella, we are pleased to report we have successfully tested antibody-ferrographic capture of protists (See previous year's report for more background). Polyclonal FITC-conjugated antibody specific for a flagellate, Spumella sp., was produced by Rockland Inc., and we now are able to enumerate that species using ferrographic capture. There are, however, some issues of non-specific staining that remain to be resolved.

Dobbs, Fred C.

2003-01-15

376

Greenhouse effect gases sources and sinks (CO{sub 2}, CH{sub 4}, N{sub 2}O) in grasslands and reduction strategies. Greenhouse effect gases prairies. Final report of the second part of the project. April 2004; Sources et puits de gaz a effet de serre (CO{sub 2}, CH{sub 4}, N{sub 2}O) en prairie paturee et strategies de reduction. GES-Prairies. Rapport final de la seconde tranche du projet. Avril 2004  

Energy Technology Data Exchange (ETDEWEB)

The project 'GES-Prairies' (Greenhouse Gases - Grasslands) had two main objectives: 1. To measure more accurately the fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O of French grasslands and determine the greenhouse gas (GHG) balance of these areas. 2. To calculate the net GHG emissions of cattle production farms and finally to propose and evaluate some management scenarios leading to a reduction of GHG emissions. This project deals with three different spatial scales: the field scale, the farm scale and finally, the regional scale. At the field scale, during two years, fluxes of CO{sub 2}, CH{sub 4} and N{sub 2}O were measured in a mid-mountain permanent grassland, previously managed intensively by cutting and grazing (Laqueuille, Auvergne, France). Results from the first complete year of measurements show that the extensification process (reduction of the stocking rate and stopping N fertilization) allows to stock more carbon in the ecosystem. At the farm scale, We developed a model (FARMSIM, coupled to PASIM) able to simulate the GHG balance of a livestock farm. FARMSIM has been tested with data obtained from a mixed livestock farm in Lorraine (dairy and meat production, annual average stocking rate = 1.3 LU ha{sup -1}) of 100 ha (including 76 ha of grasslands and 21 of annual crops). The results indicate a net emission of 175 t equivalent C-CO{sub 2} for this farm. If expressed per unit of product, it represents 1.34 t equivalent C-CO{sub 2} per LU and per year or 0.54 kg CO{sub 2} per kg of milk and per year. At the regional scale/. The PASIM model has been used to simulate the European grasslands with a spatial resolution of 1' (about 200 * 200 km). For each grid cell, a sensibility analysis allowed to determine the N application which correspond to 30% of the N application that would maximize the annual yield of the pasture. Simulation runs on mixed systems (combining grazing and cutting) show that almost one half of the grassland area is, on average, used for cutting. These simulations predict N{sub 2}O emission factors that are relatively stable for the different grid cells across Europe wit values ranging between 1 and 2% in cut systems and between 3 and 4% under grazing (with organic N application through faeces and urine deposition). Under cutting, the simulations predict a important annual C storage (varying between 0.5 to 6 t C ha-1 y-1). However one must consider that an important part of this storage occurs in the harvested forage. C storage in grazed grasslands (0.3 to 2 t C ha-1 y-1) is lower than in cut grasslands. The simulations indicates therefore that cut grassland could represent an important net GHG sink. In France, the amplitude of this sink could vary between 0.5 and 2 t C CO{sub 2} equivalent ha-1 y-1. The simulations combining cut and grazed grassland, in proportion to the dietary needs, show that,in France, these systems would be a net GHG sink of 2 to 3 t C CO{sub 2} equivalent ha-1 y-1. More realistic results would be obtained if the differences between farming systems were taken into account more specifically. (author)

Soussana, J.F

2004-04-15

377

Integrated use of Rhizobium leguminosarum, Plant Growth Promoting Rhizobacteria and Enriched Compost for Improving Growth, Nodulation and Yield of Lentil (Lens culinaris Medik.) / Uso Integrado de Rhizobium leguminosarum, Rizobacterias Promotoras de Crecimiento Vegetal y Compost Enriquecido para Mejorar el Crecimiento, Nodulación y Rendimiento de Lenteja (Lens culinaris Medik.)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish La mantención de una alta población bacteriana en la rizósfera mejora la eficiencia de estos organismos. Esta población bacteriana puede ser mantenida por la aplicación de compost enriquecido que mantiene su crecimiento y actividades. Por lo tanto, el uso integrado de Rhizobium, rhizobacterias promo [...] toras de crecimiento vegetal (PGPR) conteniendo 1-aminociclopropano-1-carboxilato desaminasa (ACC-desaminasa) y compost enriquecido con P (PEC) podría ser altamente efectivo en la promoción de crecimiento, nodulación, y producción de lenteja (Lens culinaris Medik.). Un estudio de campo se condujo para evaluar el potencial de Rhizobium, PGPR conteniendo ACC-desaminasa y PEC para promover el crecimiento de lenteja. Para este estudio, el tipo de suelo fue franco-arcillo arenoso con pH 7,6; conductividad eléctrica 2,8 dS m-1; materia orgánica 0,59%; N total 0,032%; P disponible 7,9 mg kg-1, y K extraíble 129 mg kg-1. Los tratamientos se repitieron tres veces, usando diseno de bloques completos al azar. Los resultados mostraron que el uso integrado de R. leguminosarum con Pseudomonas spp. conteniendo ACC-desaminasa junto con PEC fue altamente efectivo y causaron hasta 73.5, 73.9, 74.4, 67.5, 73.3, 65.8, 40.5, y 52.5% de aumento en biomasa fresca, producción de grano, producción de paja, vainas planta-1, peso seco de nódulo por planta, peso de 1000 granos, y contenido de N en grano de lenteja, respectivamente, comparado con el respectivo control. Se concluyó que el uso integrado de R. leguminosarum con Pseudomonas spp. portando el rasgo de ACC-desaminasa más PEC podría ser un apronte efectivo para mejor nodulación que consecuentemente mejoró producción de lenteja bajo condiciones naturales. Abstract in english Maintenance of high bacterial population in the rhizosphere improves the efficiency of these organisms. This high bacterial population can be maintained by the application of enriched compost which supports their growth and activities. Thus integrated use of Rhizobium, plant growth promoting rhizoba [...] cteria (PGPR) containing 1-aminocyclopropane-1-carboxylate deaminase (ACC-deaminase) and P-enriched compost (PEC) could be highly effective for promoting growth, nodulation, and yield of lentil (Lens culinaris Medik.). A field study was conducted to evaluate the potential of Rhizobium, PGPR containing ACC-deaminase and PEC for promoting growth of lentil. For this study, the soil type was sandy clay loam soil having pH 7.6; EC (electrical conductivity) 2.8 dS m-1; organic matter (OM) 0.59%; total N 0.032%; available P 7.9 mg kg-1, and extractable K 129 mg kg-1. Treatments were replicated thrice, using randomized complete block (RCB) design. Results showed that the integrated use of R. leguminosarum with Pseudomonas spp. containing ACC-deaminase along with PEC was highly effective and caused up to 73.5, 73.9, 74.4, 67.5, 73.3, 65.8, 40.5, and 52.5% increase in fresh biomass, grain yield, straw yield, pods plant-1, nodule plant-1, nodule dry weight plant-1, 1000-grain weight, and N content in grain of lentil, respectively, as compared to respective control. It is concluded that integrated use of R. leguminosarum with Pseudomonas spp. having trait ACC-deaminase plus PEC would be an effective approach for better nodulation which consequently improved yield of lentil under natural conditions.

Muhammad Asif, Iqbal; Muhammad, Khalid; Sher Muhammad, Shahzad; Maqshoof, Ahmad; Nawaf, Soleman; Naeem, Akhtar.

2012-03-01

378

Final report of the project. Emission of nitrogen oxides by the soils. Measures, modelization, land registry and inventory. Impact on the air quality, the climatic change and the evaluation of possibilities of these emissions reduction; Rapport final du projet. Emissions d'oxydes d'azote par les sols. Mesures, modelisation, cadastre et inventaire. Impact sur la qualite de l'air, le changement climatique, et evaluation des gisements de reduction de ces emissions  

Energy Technology Data Exchange (ETDEWEB)

This project deals with NOx biosphere-atmosphere exchanges, NOx being considered as an indirect greenhouse gases (tropospheric O{sub 3} precursor). It relies on four laboratory specialized both on the soil-plant-atmosphere interface, and on the atmospheric chemistry. Methodology used bear on a set of in situ and laboratory measurements aiming at improving existing emission parameterization, or building new ones for the agro-ecosystems encountered in France or Europe. In situ measurements allowed to study the emission phenology in relation with relevant environmental parameters (meteorological, soil characteristics, and agricultural). Laboratory measurements allowed to establish an emission algorithm related to the three main parameters, that is, soil temperature, water and ammonia content. This algorithm has been adapted and simplified to spatialize the emissions at the France level. This spatialization was performed using environmental parameters accessible through data base (ECMWF) or agricultural statistics (such as nitrogen inputs, land use, crops). Spatial and temporal extrapolation allowed reaching the main objective, that is, to build a national inventory for a reference year (2002). This inventory allowed determining the contribution of NOx emitted by soil as compared to total emitted NOx, and the proportion of NOx emitted by soil due to fertilizer use. Our study, based on 57% of the French used agricultural area, and extrapolated to the whole arable surface, shows that soils would be responsible of about 5% of the total NOx emissions. On these 5%, 20%, which finally is a rather low percentage, would be linked to fertilizer use. The impact of these emissions on the atmospheric chemistry has been evaluated using the CHIMERE chemistry-transport model. We found that NOx emissions from soil would be of minor importance when compared to the industrial emissions, being a factor of ten lower in France. As a matter of consequence, the impact of the emissions on the maximum ozone concentration during summer months is relatively limited over Europe, but can reach 2 to 3 ppb for some of the rural French regions. (author)

Serca, D.; Cortinovis, J. [LA Laboratoire d' Aerologie UMR 5560, 31 - Toulouse (France); Laville, P.; Gabrielle, B. [Institut National de Recherches Agronomiques (INRA), Environnement et Grandes Cultures, 78 - Thiverval-Grignon (France); Beekmann, M.; Ravetta, F. [Universite Pierre et Marie Curie, SA Service d' Aeronomie, 75 - Paris (France); Henault, C. [Institut National de Recherches Agronomiques (INRA-LMS) UMR Microbiologie des Sols-Geosol, 21 - Dijon (France)

2007-07-01

379

Conclusion : Jeunes et sociétés, évolutions et ambivalences  

OpenAIRE

Les parcours de vie et leurs encadrements sociauxévoluent ; nous avons voulu suivre et comprendre un peu mieux leur diversité et les modalités de leurs interactions. la pluralité des perspectives développées ici nous engageant à revenir sur les senssociaux pluriels que prend aujourd'hui le fait de «devenir adulte».

Bidart, Claire

2006-01-01

380

Mythe et logique  

OpenAIRE

- Homo faber - La prohibition de l'inceste - Muthos et logos - Le mythe selon la modernité - " Le mythe date et ne date pas car il est contemporain de l'humanité " - Mythes et affects - Acheminement vers l'origine

Rey, Olivier

2011-01-01

381

Symbiotic nitrogen fixation by a nifA deletion mutant of Rhizobium meliloti: the role of an unusual ntrC allele.  

Science.gov (United States)

In the N2-fixing alfalfa symbiont Rhizobium meliloti, the three sigma 54 (NTRA)-dependent positively acting regulatory proteins NIFA, NTRC, and DCTD are required for activation of promoters involved in N2 fixation (pnifHDKE and pfixABCX), nitrogen assimilation (pglnII), and C4-dicarboxylate transport (pdctA), respectively. Here, we describe an allele of ntrC which results in the constitutive activation of the above NTRC-, NIFA-, and DCTD-regulated promoters. The expression and activation of wild-type NTRC occur in response to nitrogen availability, whereas in cells carrying the ntrC283 allele, the NTRC283 protein appears constitutively active and is constitutively expressed. The ntrC283 allele was shown to carry a single mutation resulting in the replacement of an Asp by a Tyr residue in the helix-turn-helix motif of ntrC283. Introduction of the ntrC283 allele into a nifA deletion mutant restores the N2-fixation ability to 70 to 80% of the wild-type level. Thus, the nifA gene is dispensable for symbiotic N2 fixation. PMID:8478331

Labes, M; Rastogi, V; Watson, R; Finan, T M

1993-05-01

382

The Escherichia coli cAMP receptor protein (CRP) represses the Rhizobium meliloti dctA promoter in a cAMP-dependent fashion.  

Science.gov (United States)

The expression of the Rhizobium meliloti C4-dicarboxylic acid permease gene (dctA) is controlled by the sensor DctB and the transcriptional regulator, DctD. The R. meliloti Dct system has been reconstituted in Escherichia coli. Expression of the dctA promoter is DctBD dependent and is induced in the presence of C4-dicarboxylic acids (dCA). Other carbon sources also influence dctA expression. We demonstrate that the cAMP receptor protein (CRP) has a repressive effect on the dctA promoter. A mutated CRP molecule (CRP-H159L), unable to activate catabolic promoters (but still proficient in DNA binding), gives similar results. This suggests that the CRP-cAMP complex represses the dctA promoter activity by direct interaction with the DNA. Direct binding of the CRP-cAMP complex to the dctA promoter was confirmed in vitro by gel mobility-shift assays. Sequence analysis of the dctA promoter indicates that the most likely binding sites for CRP are the two confirmed DctD-binding sites. It is proposed that the CRP-cAMP complex competes with DctD for occupancy of these sites. Since in the presence of CRP-cAMP complex the uninduced levels of dctA expression are reduced, whereas induced levels are largely unaffected, such competition appears to be an essential regulatory feature of dctA expression. PMID:8391103

Wang, Y P; Giblin, L; Boesten, B; O'Gara, F

1993-04-01

383

Constitutive ATP hydrolysis and transcription activation by a stable, truncated form of Rhizobium meliloti DCTD, a sigma 54-dependent transcriptional activator.  

Science.gov (United States)

The dctD gene product (DCTD) activates transcription from dctA by the sigma 54-holoenzyme form of RNA polymerase in Rhizobium meliloti. We have purified a constitutively active form of R. meliloti DCTD that lacks 142 amino acid residues from the N terminus (designated DCTDL143). Purified DCTDL143 recognized the DCTD-binding sites at the dctA promoter region and catalyzed the isomerization of closed complexes between sigma 54-holoenzyme and the dctA promoter to open complexes. Like the related sigma 54-dependent activators NTRC and NIFA, a purine nucleoside triphosphate with a hydrolyzable beta-gamma bond was required prior to transcription initiation for this isomerization. DCTDL143 hydrolyzed purine nucleoside triphosphates but not pyrimidine nucleoside triphosphates. As observed with NTRC-phosphate, the specific activity for the ATPase of DCTDL143 was strongly dependent on the enzyme concentration and was stimulated by DNA fragments bearing the binding sites for the protein. These DNA fragments increased the Vmax for MgATP hydrolysis but did not significantly lower the apparent Km for MgATP. These data are consistent with the idea proposed for related activators that DCTDL143 must assemble into an active, oligomeric form before it can hydrolyze MgATP and presumably activate transcription. PMID:8051135

Lee, J H; Scholl, D; Nixon, B T; Hoover, T R

1994-08-12

384

Influences of soil acidity and variety of plant on the populations of Rhizobium trifolii found in nodules of Trifolium subterraneum L  

Energy Technology Data Exchange (ETDEWEB)

Complementary methods of strain identification were sought to delineate the composition of the populations of Rhizobium trifoli found in nodules of sub-clover when exposed to soil containing a resident population of R. trifolii. Polyacrylamide gel electrophoresis (PAGE) was used in a microslab system to elucidate the protein profile patterns of the isolates. Antisera were raised to four isolates which showed distinctly different protein profile patterns. Serological tests showed that the majority of nodule isolates could be placed into four serogroups, isolates within two of the groups (16 and 36), were antigenically identical whereas isolates in the other two groups (6 and 27) were antigenically heterogeneous. PAGE revealed that antigenically identical isolates could be subdivided further. Soil acidity affected which members of the indigenous population nodulated T. subterraneum L. Representatives of serogroup 6 occupied the greatest percentage of the nodules formed on plants grown at low pH and were a minor nodule occupant at the higher pH. In contrast sergroup 36 was virtually absent in nodules formed at low pH and was a dominant serogroup at the higher pH. Despite the isolates within serogroups 6 and 36 being antigenically identical separation of cellular proteins by PAGE revealed that serogroups 6 and 36 were composed minimally of eight and twelve different strains.

Dughri, M.H.

1984-01-01

385

Complete genome sequence of Rhizobium leguminosarum bv trifolii strain WSM2304, an effective microsymbiont of the South American clover Trifolium polymorphum  

Energy Technology Data Exchange (ETDEWEB)

Rhizobium leguminosarum bv trifolii is the effective nitrogen fixing microsymbiont of a diverse range of annual and perennial Trifolium (clover) species. Strain WSM2304 is an aerobic, motile, non-spore forming, Gram-negative rod, isolated from Trifolium polymorphum in Uruguay in 1998. This microsymbiont predominated in the perennial grasslands of Glencoe Research Station, in Uruguay, to competitively nodulate its host, and fix atmospheric nitrogen. Here we describe the basic features of WSM2304, together with the complete genome sequence, and annotation. This is the first completed genome sequence for a nitrogen fixing microsymbiont of a clover species from the American center of origin. We reveal that its genome size is 6,872,702 bp encoding 6,643 protein-coding genes and 62 RNA only encoding genes. This multipartite genome was found to contain 5 distinct replicons; a chromosome of size 4,537,948 bp and four circular plasmids of size 1,266,105 bp, 501,946 bp, 308,747 bp and 257,956 bp.

Reeve, Wayne [Murdoch University, Perth, Australia; O' Hara, Graham [Murdoch University, Perth, Australia; Chain, Patrick S. G. [Lawrence Livermore National Laboratory (LLNL); Ardley, Julie [Murdoch University, Perth, Australia; Brau, Lambert [Murdoch University, Perth, Australia; Nandesena, Kemanthi [Murdoch University, Perth, Australia; Tiwari, Ravi [Murdoch University, Perth, Australia; Malfatti, Stephanie [Lawrence Livermore National Laboratory (LLNL); Kiss, Hajnalka [Los Alamos National Laboratory (LANL); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Copeland, A [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute; Melino, Vanessa [Murdoch University, Perth, Australia; Denton, Matthew [Department of Primary Industries, Victoria, Australia; Yates, Ron [Murdoch University, Perth, Australia; Howieson, John [Murdoch University, Perth, Australia

2010-01-01

386

Using Arbuscular Mycorrhizal Fungi and Rhizobium leguminosarum Biovar phaseoli Against Sclerotinia sclerotiorum (Lib. de Bary in the Common Bean (Phaseolus vulgaris L.  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, the effects of Arbuscular Mycorrhizal Fungi (AMF Glomus mosseae (Gm, Glomus fasciculatum (Gf and Rhizobium leguminosarum biovar phaseoli (Rlp, which are the important members of rhizosphere and biological control agents, were examined on the patho-system of Sclerotinia sclerotiorum (Lib. de Bary (Ss and common bean. The colonization and nodulation of two biological control agents exhibited differences as a result of reciprocal interactions of these items as well as the effect of the Ss. Nodulation of Rlp particularly decreased in triple inoculation. In addition, colonization of AMF significantly decreased in treatment of Ss+AMF than control AMF. Treatments of single inoculations of AMF and Rlp isolates reduced disease severity by 10.3-24.1%. It was determined that single biological control agents inoculations were more effective than dual inoculations (AMF+Rlp. When the morphological parameters of common bean were considered, all of the morphological parameters values were decreased in treatments which present pathogen isolate. Besides this, all biological control agents increased total contents of P and N in treated plants compared to the controls.

E. Aysan

2009-01-01

387

Bacillus simplex—A Little Known PGPB with Anti-Fungal Activity—Alters Pea Legume Root Architecture and Nodule Morphology When Coinoculated with Rhizobium leguminosarum bv. viciae  

Directory of Open Access Journals (Sweden)

Full Text Available Two strains, 30N-5 and 30VD-1, identified as Bacillus simplex and B. subtilis, were isolated from the rhizospheres of two different plants, a Podocarpus and a palm, respectively, growing in the University of California, Los Angeles (UCLA Mildred E. Mathias Botanical Garden. B. subtilis is a well-known plant-growth promoting bacterial species, but B. simplex is not. B. simplex 30N-5 was initially isolated on a nitrogen-free medium, but no evidence for nitrogen fixation was found. Nevertheless, pea plants inoculated with B. simplex showed a change in root architecture due to the emergence of more lateral roots. When Pisum sativum carrying a DR5::GUSA construct, an indicator for auxin response, was inoculated with either B. simplex 30N-5 or its symbiont Rhizobium leguminosarum bv. viciae 128C53, GUS expression in the roots was increased over the uninoculated controls. Moreover, when pea roots were coinoculated with either B. simplex 30N-5 or B. subtilis 30VD-1 and R. leguminosarum bv. viciae 128C53, the nodules were larger, clustered, and developed more highly branched vascular bundles. Besides producing siderophores and solubilizing phosphate, the two Bacillus spp., especially strain 30VD-1, exhibited anti-fungal activity towards Fusarium. Our data show that combining nodulating, nitrogen-fixing rhizobia with growth-promoting bacteria enhances plant development and strongly supports a coinoculation strategy to improve nitrogen fixation, increase biomass, and establish greater resistance to fungal disease.

Ann M. Hirsch

2013-09-01

388

Lipopolysaccharide O-Chain Core Region Required for Cellular Cohesion and Compaction of In Vitro and Root Biofilms Developed by Rhizobium leguminosarum.  

Science.gov (United States)

The formation of biofilms is an important survival strategy allowing rhizobia to live on soil particles and plant roots. Within the microcolonies of the biofilm developed by Rhizobium leguminosarum, rhizobial cells interact tightly through lateral and polar connections, forming organized and compact cell aggregates. These microcolonies are embedded in a biofilm matrix, whose main component is the acidic exopolysaccharide (EPS). Our work shows that the O-chain core region of the R. leguminosarum lipopolysaccharide (LPS) (which stretches out of the cell surface) strongly influences bacterial adhesive properties and cell-cell cohesion. Mutants defective in the O chain or O-chain core moiety developed premature microcolonies in which lateral bacterial contacts were greatly reduced. Furthermore, cell-cell interactions within the microcolonies of the LPS mutants were mediated mostly through their poles, resulting in a biofilm with an altered three-dimensional structure and increased thickness. In addition, on the root epidermis and on root hairs, O-antigen core-defective strains showed altered biofilm patterns with the typical microcolony compaction impaired. Taken together, these results indicate that the surface-exposed moiety of the LPS is crucial for proper cell-to-cell interactions and for the formation of robust biofilms on different surfaces. PMID:25416773

Russo, Daniela M; Abdian, Patricia L; Posadas, Diana M; Williams, Alan; Vozza, Nicolás; Giordano, Walter; Kannenberg, Elmar; Downie, J Allan; Zorreguieta, Angeles

2015-02-01

389

Formulation of microbes inoculum: AMF, PSB and Rhizobium isolated of ex-coal mining site for Acacia crassicarpa Cunn. Ex-benth seedlings  

Directory of Open Access Journals (Sweden)

Full Text Available The shoddier succeed land revegetation particularly caused by least adaptability of the seedlings planted on this site. To encourage their growth and survival rate it can be achieved by means do inoculation with the compatible functional microbes such as rhizobium, Psolubilizing bacteria (PSB and/or arbuscular-mycorrhiza fungy (AMF. This reserach is aimed to formulate the most compatible inoculant to support the growth of A. crassicarpa seedlings. Compatibility study is carried out in RCB design with 3 replications, each contain 5 seedlings. Height and biomass are accessed to measure the growth responses of the seedlings. The result showed that the best reponse is given by consortia that consist of the three kinds of these microbes. This increase the shoot biomass (137% compare to the control. The consortia also improved N 164%, P 335% and K 167% in the plant tissues. While pure AMF improved absorption of N plants 80%, P 383% and K 51% compare to the control. It is suggested that to prepare the A. crassicarpa seedlings is better inoculated by consortium of microbes or AMF as a sole inoculant.

ENNY WIDYATI

2007-07-01

390

In vitro Studies on the Effects of Biofertilizers (Azotobacter and Rhizobium on Seed Germination and Development of Trigonella foenum-graecum L. using a Novel Glass Marble containing Liquid Medium  

Directory of Open Access Journals (Sweden)

Full Text Available Biofertilizers are the formulations of living microorganisms, which are capable of fixing atmospheric nitrogen in the soil and thereby, increasing the crop yield. Trigonella foenum-graecum L. is a medicinally important plant possessing anti-diabetic, anti-cancerous, anti-microbial and hypocholesterolaemic properties. The present study was conducted to develop an in vitro method for studying the effects of biofertilizers (Azotobacter and Rhizobium on the seed germination and development of Trigonella foenum graecum L. using a simple and cost-effective liquid culture medium containing glass marbles as reusable and biologically inert support matrix. Sucrose optimization studies revealed maximum development for the plantlets grown on 1X Murashige and Skoog liquid medium containing 4% sucrose and glass marbles. Azotobacter and Rhizobium were isolated from rhizosphere soil and root nodules of Trigonella plants, respectively and identified following the standard procedures. Mass cultivation of the bacteria carried out for 5 days reported counts of 2.3x104 cells mL-1. The harvested bacterial cells were used to coat the seeds in the presence and absence of charcoal. After 15 days of growth under in vitro conditions, the root length, shoot length, fresh weight, protein, carbohydrate and chlorophyll contents of the plantlets were determined. Maximum growth was observed for the plantlets grown on 1X MS medium with 4% sucrose and glass marbles, inoculated with 40% concentration of Azotobacter, Rhizobium and their co-inoculum mixed with charcoal. Field trials, conducted under green house conditions, revealed that 10% biofertilizer co-inoculum supported maximum growth of the plants when the seeds were coated with charcoal.

Sourav Bhattacharya

2010-01-01

391

A homolog of the Rhizobium meliloti nitrogen fixation gene fixN is involved in the production of a microaerobically induced oxidase activity in the phytopathogenic bacterium Agrobacterium tumefaciens.  

Science.gov (United States)

Hybridization analysis using the Rhizobium meliloti nitrogen fixation gene fixN as a probe revealed the presence of a homologous DNA region in the phytopathogenic bacterium Agrobacterium tumefaciens. Hybridization signals were also detected with total DNAs of Rhizobium leguminosarum bv. phaseoli, Rhodobacter capsulatus and Escherichia coli, but not those of Xanthomonas campestris pv. campestris and Pseudomonas putida. The hybridizing fragment from A. tumefaciens was cloned and sequenced. The predicted gene product of one of the two open reading frames identified on the sequenced fragment shows homology to FixN of different Rhizobiaceae as well as a low but significant similarity to subunit I of heme copper oxidases from various bacteria. The presence of five strictly conserved histidine residues previously implicated in forming ligands to heme and CuB in oxidases and the predicted membrane topology provide evidence that the A. tumefaciens fixN-like gene product is a component of the heme copper oxidase superfamily. The incomplete open reading frame starting only 8 nucleotides downstream of the fixN-like gene exhibits homology to Rhizobium fixO. Using an uidA (GUS) gene fusion it could be shown that the A. tumefaciens fixN-like gene is preferentially expressed under microaerobic conditions. Expression of the uidA fusion is abolished in R. meliloti fixJ and fixK mutants, indicating that an Fnr-like protein is involved in transcriptional regulation of the fixN-like gene in A. tumefaciens. The presence of an upstream DNA sequence motif identical to the Fnr-consensus binding site (anaerobox) further supports this hypothesis. A. tumefaciens mutated in the fixN-like gene shows decreased TMPD-specific oxidase activity under microaerobic conditions, indicating that the fixN-like gene or operon codes for proteins involved in respiration under reduced oxygen availability. PMID:7753030

Schlüter, A; Rüberg, S; Krämer, M; Weidner, S; Priefer, U B

1995-04-20

392

INFINITIF ET GERONDIF  

OpenAIRE

Nous traitons ici des cas spécifiques du gérondif et de l'infinitif en français, lesquels ne correspondent à notre sens que très peu aux caractéristiques de ce qui renvoie aux modes verbaux, dont ils sont marginalisés sur les plans des spécifications personnelles et temporelles, mais aussi prédicationnelles. En tant que formes à proprement parler, mais aussi dans leurs caractéristiques valentielles, l'infinitif et le gérondif relèvent à la fois du verbe et du nom, du verbe et de...

Torterat, Fre?de?ric

2006-01-01

393

Lectin from Canavalia brasiliensis Seeds (ConBr) Is a Valuable Biotechnological Tool to Stimulate the Growth of Rhizobium tropici in Vitro  

OpenAIRE

To study the interactions between a Rhizobium tropici strain and lectins isolated from the seeds of Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr), a lectin fluorescence assay was performed. In addition, an experiment was designed to evaluate the effect of the two lectins on bacterial growth. Both lectins were found to bind to R. tropici cells, but the interactions were inhibited by D-mannose. ...

Ricardo Pires dos Santos; Benildo Sousa Cavada; Bruno Anderson Matias Rocha; Edson Holanda Teixeira; Victor Alves Carneiro; Giselly Soares de Sousa; Francisco Vassiliepe Sousa Arruda; Mayron Alves Vasconcelos; Luiz Gonzaga do Nascimento Neto; Fabio Martins Mercante; Claudio Oliveira Cunha

2012-01-01

394

The ndvA gene product of Rhizobium meliloti is required for beta-(1----2)glucan production and has homology to the ATP-binding export protein HlyB.  

OpenAIRE

The ndvA locus of Rhizobium meliloti is homologous to and can substitute for the chvA locus of Agrobacterium tumefaciens. We have previously shown that an ndvA mutant exhibited reduced motility and formed small, white, empty nodules on alfalfa roots. Here we show that this ndvA mutant is defective in the production of the cyclic extracellular polysaccharide beta-(1----2)glucan, even though a 235,000-dalton protein intermediate, known to be involved in the synthesis of this molecule, is presen...

Stanfield, S. W.; Ielpi, L.; O Brochta, D.; Helinski, D. R.; Ditta, G. S.

1988-01-01

395

L’excellence : impossible sans un personnel stable et expérimenté  

CERN Multimedia

Le monde entier avait les yeux fixés sur le CERN ce 4 juillet 2012, quand ATLAS et CMS ont annoncé leur découverte d’une particule « compatible avec le Higgs ». Début 2013 il n’a fallu que quelques jours pour régler le LHC et faire tourner des protons et des ions lourds. Toutes ces découvertes et prouesses techniques n’ont été possibles que grâce à l’expérience et la poursuite de l’excellence d’équipes soudées de techniciens et ingénieurs qui ont conçu, construit, mis en marche, et finalement font fonctionner ce complexe d’accélérateurs unique au monde. Un service d’excellence avec un encadrement adéquat Entre 2002 et 2012 (voir Fig. 1), le nombre d’utilisateurs est passé de 5912 à...

Association du personnel

2013-01-01

396

Probabilités et mécanique statistique hors équilibre  

OpenAIRE

Nous passons en revue certains résultats obtenus dans quatre thèmes: les équations de Navier-Stokes stochastiques en deux dimensions, la loi de Fourier dans les chaines d'oscillateurs anharmoniques, les grandes déviations de ces systèmes et finalement, les dynamiques de collision locales.

Lefevere, Raphael

2009-01-01

397

La balle et la plume  

Directory of Open Access Journals (Sweden)

Full Text Available Fin octobre 2008, la nouvelle fit l’effet d’une bombe : Barack Obama, alors candidat à la présidence américaine, demanda à la chaîne câblée Fox News de retarder le début du sixième match de la World Series de base-ball afin de diffuser un spot de campagne. Son adversaire, John McCain, soutenu par le camp républicain et une partie de la population, monta aussitôt au créneau pour dénoncer l’hérésie : s’arroger le droit de perturber cette grande finale du championnat au déroulement immuable reve...

Peter Marquis

2012-06-01

398

Biological activity of (lipo)polysaccharides of the exopolysaccharide-deficient mutant Rt120 derived from Rhizobium leguminosarum bv. trifolii strain TA1.  

Science.gov (United States)

Lipopolysaccharides (LPS) from Rhizobium leguminosarum biovar trifolii TA1 (RtTA1) and its mutant Rt120 in the pssB?pssA intergenic region as well as degraded polysaccharides (DPS) derived from the LPS were elucidated in terms of their chemical composition and biological activities. The polysaccharide portions were examined by methylation analysis, MALDI-TOF mass spectrometry, and (1)H NMR spectroscopy. A high molecular mass carbohydrate fraction obtained from Rt120 DPS by Sephadex G-50 gel chromatography was composed mainly of L-rhamnose, 6-deoxy-L-talose, D-galactose, and D-galacturonic acid, whereas that from RtTA1 DPS contained L-fucose, 2-acetamido-2,6-dideoxy-D-glucose, D-galacturonic acid, 3-deoxy-3-methylaminofucose, D-glucose, D-glucuronic acid, and heptose. Relative intensities of the major (1)H NMR signals for O-acetyl and N-acetyl groups were 1 : 0.8 and 1 : 1.24 in DPS of Rt120 and RtTA1, respectively. The intact mutant LPS exhibited a twice higher lethal toxicity than the wild type LPS. A higher in vivo production of TNF? and IL-6 after induction of mice with Rt120 LPS correlated with the toxicity, although the mutant LPS induced the secretion of IL-1? and IFN? more weakly than RtTA1 LPS. A polysaccharide obtained by gel chromatography on Bio-Gel P-4 of the high molecular mass material from Rt120 had a toxic effect on tumor HeLa cells but was inactive against the normal human skin fibroblast cell line. The polysaccharide from RtTA1 was inactive against either cell line. The potent inhibitory effect of the mutant DPS on tumor HeLa cells seems to be related with the differences in sugar composition. PMID:21999546

Kutkowska, J; Turska-Szewczuk, A; Janczarek, M; Paduch, R; Kami?ska, T; Urbanik-Sypniewska, T

2011-07-01

399

Physiological and biochemical defense reactions of Vicia faba L.-Rhizobium symbiosis face to chronic exposure to cyanobacterial bloom extract containing microcystins.  

Science.gov (United States)

The presence of cyanotoxins, mainly microcystins (MCs), in surface freshwater represents a serious health risk to aquatic organisms living in the water body, as well as terrestrial animals and plants that are in contact with contaminated water. Consequently, the use of MCs contaminated water for irrigation represents a hazard for cultivated plants and could induce severe economical losses due to crops' yield reduction. The experimental approach undertaken in this work was exposing Vicia faba seedlings (inoculated with a Rhizobium strain resistant to MCs), to water supplemented with cyanobacterial crude extract containing total microcystins at a concentration of 50 and 100 ?g/L (environmental relevant concentrations of MCs dissolved in the raw irrigation water from Lalla Takerkoust Lake-Marrakesh region). After chronic MCs exposure (2 months), biological and physiological parameters (plant growth, nitrogen uptake, mineral assimilation, and oxidative defense mechanisms) were evaluated. The results obtained showed evidence that chronic exposure to cyanobacterial bloom extract containing MCs strongly affected the physiological and biological plants activities; reduction of dry matter, photosynthetic activity, nodule number, and nitrogen assimilation. At the same time, an increase of oxidative stress was observed, as deduced from a significant increase of the activities of peroxidase, catalase, polyphenoloxidase, and phenylalanine ammonia lyase in leaves, roots, and nodules of faba bean plants exposed to cyanotoxins, especially at 100 ?g/L of MCs. This experimentation constitutes a simulation of the situation related to cyanotoxins chronic exposure of seedlings-plants via the contaminated irrigation water. For this reason, once should take into consideration the possibility of contamination of agricultural crops and the quality of irrigation water should be by the way monitored for cyanotoxins biohazard. PMID:23417437

Lahrouni, Majida; Oufdou, Khalid; El Khalloufi, Fatima; Baz, Mohamed; Lafuente, Alejandro; Dary, Mohammed; Pajuelo, Eloisa; Oudra, Brahim

2013-08-01

400

Synthesis of the flavonoid-induced lipopolysaccharide of Rhizobium Sp. strain NGR234 requires rhamnosyl transferases encoded by genes rgpF and wbgA.  

Science.gov (United States)

In the presence of flavonoids, Rhizobium sp. strain NGR234 synthesizes a new lipopolysaccharide (LPS), characterized by a rhamnan O-antigen. The presence of this rhamnose-rich LPS is important for the establishment of competent symbiotic interactions between NGR234 and many species of leguminous plants. Two putative rhamnosyl transferases are encoded in a cluster of genes previously shown to be necessary for the synthesis of the rhamnose-rich LPS. These two genes, wbgA and rgpF, were mutated. The resulting mutant strains synthesized truncated rough LPS species rather than the wild-type rhamnose-rich LPS when grown with flavonoids. Based on the compositions of these purified mutant LPS species, we inferred that RgpF is responsible for adding the first one to three rhamnose residues to the flavonoid-induced LPS, whereas WbgA is necessary for the synthesis of the rest of the rhamnan O-antigen. The NGR234 homologue of lpsB, which, in other bacteria, encodes a glycosyl transferase acting early in synthesis of the core portion of LPS, was identified and also mutated. LpsB was required for all the LPS species produced by NGR234, in the presence or absence of flavonoids. Mutants (i.e., of lpsB and rgpF) that lacked any portion of the rhamnan O-antigen of the induced LPS were severely affected in their symbiotic interaction with Vigna unguiculata, whereas the NGR?wbgA mutant, although having very few rhamnose residues in its LPS, was able to elicit functional nodules. PMID:22066901

Ardissone, Silvia; Noel, K Dale; Klement, Mitchell; Broughton, William J; Deakin, William J

2011-12-01

401

Functional Analysis of NopM, a Novel E3 Ubiquitin Ligase (NEL) Domain Effector of Rhizobium sp. Strain NGR234  

Science.gov (United States)

Type 3 effector proteins secreted via the bacterial type 3 secretion system (T3SS) are not only virulence factors of pathogenic bacteria, but also influence symbiotic interactions between nitrogen-fixing nodule bacteria (rhizobia) and leguminous host plants. In this study, we characterized NopM (nodulation outer protein M) of Rhizobium sp. strain NGR234, which shows sequence similarities with novel E3 ubiquitin ligase (NEL) domain effectors from the human pathogens Shigella flexneri and Salomonella enterica. NopM expressed in Escherichia coli, but not the non-functional mutant protein NopM-C338A, showed E3 ubiquitin ligase activity in vitro. In vivo, NopM, but not inactive NopM-C338A, promoted nodulation of the host plant Lablab purpureus by NGR234. When NopM was expressed in yeast, it inhibited mating pheromone signaling, a mitogen-activated protein (MAP) kinase pathway. When expressed in the plant Nicotiana benthamiana, NopM inhibited one part of the plant's defense response, as shown by a reduced production of reactive oxygen species (ROS) in response to the flagellin peptide flg22, whereas it stimulated another part, namely the induction of defense genes. In summary, our data indicate the potential for NopM as a functional NEL domain E3 ubiquitin ligase. Our findings that NopM dampened the flg22-induced ROS burst in N. benthamiana but promoted defense gene induction are consistent with the concept that pattern-triggered immunity is split in two separate signaling branches, one leading to ROS production and the other to defense gene induction. PMID:22615567

Xin, Da-Wei; Liao, Sha; Xie, Zhi-Ping; Hann, Dagmar R.; Steinle, Lea; Boller, Thomas; Staehelin, Christian

2012-01-01

402

Mutants of the two-component regulatory protein FixJ of Rhizobium meliloti that have increased activity at the nifA promoter.  

Science.gov (United States)

FixL and FixJ belong to a two-component regulatory system in Rhizobium meliloti that induces the expression of numerous nitrogen-fixation genes during symbiosis with alfalfa. FixJ is a positive activator required for transcription of the regulatory genes nifA and fixK, while FixL is an oxygen-binding hemoprotein capable of regulating the phosphorylation status of both itself and FixJ, in response to oxygen availability. In this study, we isolated four FixJ mutants that display increased activity at the nifA promoter (PnifA) in Escherichia coli. All four mutants possess amino acid changes in a domain of FixJ that is conserved in other response regulator proteins, and all exhibit increased activity at PnifA in R. meliloti that is dependent on the presence of FixL. One of the mutant proteins, while less efficient at accepting phosphate from a truncated derivative of FixL (FixL*), nevertheless has a phosphorylated form that is more stable than the phosphorylated form of wild-type (wt) FixJ and is more resistant to the phosphatase activity of FixL*. The wt FixJ-phosphate was found to have a half-life of approximately 4 h, which makes it an unusually long-lived response regulator protein. The exceptional stability of wt FixJ-phosphate and the altered phosphorylation properties observed for the mutant are discussed in relation to signal transduction in the FixLJ system. PMID:8262372

Weinstein, M; Lois, A F; Ditta, G S; Helinski, D R

1993-12-01

403

Screening a wide host-range, waste-water metagenomic library in tryptophan auxotrophs of Rhizobium leguminosarum and of Escherichia coli reveals different classes of cloned trp genes.  

Science.gov (United States)

A metagenomic cosmid library was constructed, in which the insert DNA was derived from bacteria in a waste-water treatment plant and the vector was the wide host-range cosmid pLAFR3. The library was screened for clones that could correct defined tryptophan auxotrophs of the alpha-proteobacterium Rhizobium leguminosarum and of Escherichia coli. A total of 26 different cosmids that corrected at least one trp mutant in one or both of these species were obtained. Several cosmids corrected the auxotrophy of one or more R. leguminosarum trp mutants, but not the corresponding mutants in E. coli. Conversely, one cosmid corrected trpA, B, C, D and E mutants of E. coli but none of the trp mutants of R. leguminosarum. Two of the Trp+ cosmids were examined in more detail. One contained a trp operon that resembled that of the pathogen Chlamydophila caviae, containing the unusual kynU gene, which specifies kynureninase. The other, whose trp genes functioned in R. leguminosarum but not in E. coli, contained trpDCFBA in an operon that is likely co-transcribed with five other genes, most of which had no known link with tryptophan synthesis. The sequences of these TRP proteins, and the products of nine other genes encoded by this cosmid, failed to affiliate them with any known bacterial lineage. For one metagenomic cosmid, lac reporter fusions confirmed that its cloned trp genes were transcribed in R. leguminosarum, but not in E. coli. Thus, rhizobia, with their many sigma-factors, may be well-suited hosts for metagenomic libraries, cloned in wide host-range vectors. PMID:16309391

Li, Youguo; Wexler, Margaret; Richardson, David J; Bond, Philip L; Johnston, Andrew W B

2005-12-01

404

Caracterización de cepas de Rhizobium y Bradyrhizobium (con habilidad de nodulación) seleccionados de los cultivos de fríjol caupi (Vigna unguiculata) como potenciales bioinóculos / Characterization of Rhizobium and Bradyrhizobiu´s strains (with ability of nodulation) selected from bean (Vigna unguiculata) cultures as a potentials bioinoculants  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Los suelos de Latinoamérica son ácidos y deficientes en nitrógeno; por esta razón es necesario explorar nuevas alternativas con el fin de modular el desarrollo de plantas, especialmente las leguminosas. El uso del potencial de las bacterias para inducir nodulación y fijar el nitrógeno en las plantas [...] leguminosas se ha estudiado como una opción con potencial impacto. En este estudio se analizó la diversidad de cepas de rhizobios aislados del fríjol Vigna unguiculata (fríjol caupí) cultivado en el norte del departamento de Bolívar (Colombia). Se identificaron aislados capaces de crecer mejor en ambientes hostiles (los cuales tienen un uso potencial como bioinoculantes). Se describe además un acercamiento a la taxonomía de estas bioespecies. Se caracterizaron 52 cepas de rizobios (basados en sus características morfológicas, requerimientos de cultivo, metabólicas, resistencia a metales y antibióticos y de autenticación). De acuerdo con sus propiedades de crecimiento, el 63,5% fueron de cepas de lento, mientras que el 36,5%, de rápido crecimiento. Prevalecieron las de lento crecimiento con un 63,5% del total sobre un 36,5% de rápido crecimiento. Los aislados fueron caracterizados de acuerdo con sus patrones de asimilación de carbohidratos, y se encontraron microorganismos de los géneros Rhizobium, Bradyrhizobium y Mesorhizobium (12 cepas identificadas como potenciales bioinoculantes). Abstract in english Latin America´s soils are acidic and nitrogen-deficient, for this reason is necessary to explore new alternatives in order to modulate in the development of plants, specially the leguminous plants. The use of bacteria´s potential to induce nodulation and to fix nitrogen in leguminous plants has been [...] studied as an option with potential impact. In our study, we analyzed the diversity of rhizobial isolated of the bean Vigna unguiculata (beans cowpea) cultured in the north of Bolivar department (Colombia). We identified strains able of growing in hostile environment (which have a potential use like bioinoculants). Additionally, we described an approach to taxonomy of these biospecies. We reached the characterization of 52 rhizobial strains (based on their morphologic, requires of culture, metabolic, resistance to metals and antibiotics and authentication characteristics). According with their growing properties, 63.5 % were slow growth strains while the 36.5 % were of rapid growth. The isolates were characterized according to their assimilation carbohydrate´s pattern, finding microorganism as Rhizobium, Bradyrhizobium and Mesorhizobium (12 of which were identified as potential bioinoculants).

Bernarda, Cuadrado; Guillermo, Rubio; Winston, Santos.

2009-01-01

405

Ethical aspects of final disposal. Final report  

International Nuclear Information System (INIS)

In fulfilment of this task the Federal Environmental Ministry has commissioned GRS to summarise the current national and international status of ethical aspects of the final disposal of radioactive wastes as part of the project titled ''Final disposal of radioactive wastes as seen from the viewpoint of ethical objectives''. The questions arising from the opinions, positions and publications presented in the report by GRS were to serve as a basis for an expert discussion or an interdisciplinary discussion forum for all concerned with the ethical aspects of an answerable approach to the final disposal of radioactive wastes. In April 2001 GRS held a one-day seminar at which leading ethicists and philosophers offered statements on the questions referred to above and joined in a discussion with experts on issues of final disposal. This report documents the questions that arose ahead of the workshop, the specialist lectures held there and a summary of the discussion results

406

Tessin. Paysage et patrimoine  

OpenAIRE

Le numéro est centré sur les liens entre paysage et le patrimoine au Tessin et met l'accent sur des aspects tels l'agriculture, le paysage, un éco-musée et des témoignages artistiques. Le numéro contient en outre un mémoire sur la géopoétique de Primo Levi

Le?vy, Bertrand; Ferrata, Claudio

2007-01-01

407

Final Focus Test Stand final report  

CERN Document Server

Future Linear colliders will need particle beam sizes in the nanometre range. The beam also needs to be stable all along the beam line and especially at the Final Focus section. A dedicated Final Focus test stand has been used for this study and is comprised of several sub-parts. First there is the Stabilisation/Isolation system with sensors and actuators stabilizing down to sub-nanometre level. Then the Magnet itself needs to comply with very specific design constraints. In addition to the mechanical items, the beam can be stabilized acting on the trajectory directly and Beam-based controls have been developed and tested on different accelerator facilities.

Jeremie, A; Burrows, P

2013-01-01

408

Rhizobium leguminosarum nodulation gene (nod) expression is lowered by an allele-specific mutation in the dicarboxylate transport gene dctB.  

Science.gov (United States)

To identify host genes that might influence nod (nodulation) gene expression in Rhizobium leguminosarum, a nodC-phoA reporter plasmid (carrying nodD) was introduced into a chemically mutagenized population of a R. leguminosarum strain lacking a symbiotic plasmid. The transconjugants were screened for expression of alkaline phosphatase (PhoA) on plates containing hesperetin, an inducer of nod genes, and a mutant with reduced expression was identified. When the nodC-phoA plasmid was cured from the mutant and the symbiotic plasmid pRL1Jl introduced, the mutant formed nodules, but symbiotic nitrogen fixation was less than 20% of normal. When the nodC-phoA allele was introduced on pRL1Jl a low level of nod gene induction was found. The reduced nodC expression appeared to be caused by a decrease in expression of the regulatory gene nodD, since expression of a nodD-lacZ fusion was also lower in the mutant than in the control. These mutant phenotypes and the low nitrogen fixation were complemented with a plasmid (plJ1848) from a R. leguminosarum cosmid library. DNA hybridization confirmed that plJ1848 was not from the symbiotic plasmid and showed that a DNA insertion was present in the mutant. The complementing region of plJ1848 was defined by transposon mutagenesis; DNA sequencing revealed that it carried the dicarboxylic acid transport (dct) genes. However, the mutant grew well with succinate as sole C-source. Genetic analysis revealed that the mutant appeared to contain IS50 in the regulatory gene dctB and that this mutation caused the reduction in nod gene expression. The effect was allele-specific since other mutations in dctB did not influence nod gene expression. Surprisingly, the mutant had a constitutive high level of succinate transport, indicating that the mutation caused unregulated expression of dctA the structural gene for dicarboxylic acid transport. This in some way appears to have lowered the expression of nodD, indicating that the nodD promoter may be influenced by the metabolic status of the cells or by expression of dctD in the absence of dctB. PMID:7894701

Mavridou, A; Barny, M A; Poole, P; Plaskitt, K; Davies, A E; Johnston, A W; Downie, J A

1995-01-01

409

Jachère et systèmes agraires  

OpenAIRE

Le Sahel subit des risques de sécheresse et ne dispose que de sols pauvres. Pour lutter contre la diminution de la fertilité des champs, les paysans ont recours à deux techniques : la mise en jachère et la fumure organique (essentiellement sous forme de restitution par le parcage). Dans la zone d'étude, coexistent des systèmes de cultures sur jachères, peu ou assez dégradées, et des systèmes de culture avec fumure organique. Du fait des dépôts de poussières pendant la période de...

Rouw, Anneke

1998-01-01

410

Femmes et politiques alimentaires  

OpenAIRE

Le Rondonia est actuellement au Brésil le principal lieu d'acceuil de petits agriculteurs à la recherche de terres : entre 1970 et 1980 la population rurale a été multipliée par cinq. L'histoire et la colonisation officielle en a fait une région originale où coexistent les économies traditionnelles (extraction du caoutchouc, recherche de l'or, de la cassitérite, cueillette de la noix du Brésil), les cultures de rente encouragées par l'Etat (café, cacao, hévéa) et la production v...

Aubertin, Catherine

1985-01-01

411

Diæten - et andet perspektiv  

DEFF Research Database (Denmark)

Temaet for den seneste udgave af vores studenterblad ”Næringsstoffet” er ”Et andet perspektiv”. Ifølge redaktionens oplæg kunne det eksempelvis dreje sig om »artikler om nye kropsidealer, at sundhed ikke kun handler om, hvad man propper i munden, forskellige perspektiver på de nye kostråd, alternative kostformer (5:2 kuren) osv.«. Det gav mig anledning til et indlæg, hvor jeg har forsøgt at strejfe flere punkter fra listen med et andet perspektiv på diæten. I bloggen gengives det indlæg i en lettere tilrettet version.

Agerholm, Frank Juul

412

Innovation et fondation  

OpenAIRE

Dans Sur la révolution, Hannah Arendt expose, dès le début du texte, l'authentique souci machiavélien de la fondation d'un corps politique permanent et durable. Selon elle, les révolutions ne sont pas des simples changements, parce qu'elles nous confrontent directement avec le problème du rapport entre commencement et constitution, liberté et permanence de l'espace politique. Dans cet article, je propose que cette analyse qu'Arendt fait des révolutions rectifie une aporie inscrite au ...

Paredes Goicochea, Diego

2012-01-01

413

Cultures et organisations  

OpenAIRE

La coopération interculturelle, une question de survie Véritable atlas des valeurs culturelles, paru en 18 langues, Cultures et organisations est le fruit de plus de 40 ans de recherches menées dans plus de 100 pays. Il est aujourd'hui le livre de référence des chercheurs, universitaires et professionnels en management interculturel, sociologie des organisations, psychosociologie... Dans un monde divisé malgré la globalisation et l'avènement des nouvelles technologies, cet ouvrage es...

Hofstede, G.; Hofstede, G. J.; Minkov, M.

2010-01-01

414

Fiction et forme encyclopédique : Wookieepedia, Dragon Ball Wiki et Cie.  

Directory of Open Access Journals (Sweden)

Full Text Available Wookieepedia, Final Fantasy Wiki, Dragon Ball Wiki, Memory Alpha, WoWWiki… Autant d’encyclopédies en ligne abordant de célèbres fictions pour la jeunesse à travers un nombre parfois considérable d’articles abordant toutes sortes de sujets (récits, technologies, personnages, lieux, auteurs, fans…. Que nous apprennent ces dispositifs entendant prendre des fictions au sérieux, c’est-à-dire aborder un domaine relevant de l’imaginaire avec des outils relevant du domaine de la connaissance ? Deux pratiques se dégagent : la référence à des produits culturels prenant des formes fort diverses (romans, bandes dessinées, films, jeux vidéo… et le lien entre les divers articles. Ces deux pratiques montrent comment se développe une expertise quant à une fiction, une capacité à se situer dans une construction imaginaire.

Benoît Berthou

2011-06-01

415

Rhizobium meliloti DctD, a sigma 54-dependent transcriptional activator, may be negatively controlled by a subdomain in the C-terminal end of its two-component receiver module.  

Science.gov (United States)

Rhizobium meliloti DctD is believed to have three functional domains: an N-terminal, two-component receiver domain; and like other sigma 54-dependent activators, C-terminal and central domains for DNA binding and transcription activation. We have characterized a progressive series of N-terminal deletions of R. meliloti DctD. The N-terminal domain was not needed for binding the dctA upstream activation sequence. Only 25% of the C-terminal end of the receive domain was needed to significantly inhibit the central domain, and proteins lacking up to 60% of the N-terminal end of the receiver domain were 'inducible' in R. meliloti cells. We hypothesize that the N-terminal two-thirds of the DctD receiver domain augments and controls an adjacent subdomain for inhibiting the central domain. PMID:7984094

Gu, B; Lee, J H; Hoover, T R; Scholl, D; Nixon, B T

1994-07-01

416

Le beau et le vrai  

Directory of Open Access Journals (Sweden)

Full Text Available La vie des abeilles de Maeterlinck est un ouvrage à la fois scientifique et littéraire, non pas parce qu’il appartiendrait à la science par son exactitude et à la littérature par son style, mais en ce qu’il invite à penser l’unité des deux domaines. Les aspects littéraires de l’ouvrage (beauté de l’écriture, usage des images, de l’analogie, etc. ne sont pas des accessoires, mais des outils indispensables à l’élaboration d’un authentique savoir sur les abeilles, c’est-à-dire un savoir qui reconnaît la part d’inconnu et le mystère qui subsistent en dépit de toutes les explications physiques et mécaniques que l’on peut par ailleurs donner des phénomènes observés. Etre scientifique, dans cette perspective, c’est-à-dire donner à connaître, c’est donc être littéraire. Cette conception de la science repose en dernière instance sur une conception philosophique de l’univers comme un tout où toutes choses sont reliées, unies, par des relations d’analogies, ce qui fonde et justifie l’emploi d’un style symboliste.The life of bees, one of Maeterlinck’s works, is together a scientific and literary book, not because of it scientific exactness and its literary style, but for the reason it suggests the unity of both these domains. Literay’s aspects of this work (writing’s beauty, use of images, analogy, etc. are not secondary but necessary to elaborate an authentic knowledge about bees, that means a knowledge which admit the unknown part and the mistery that subsist despite all the physical and mechanical explanations we can give moreover about the observed phenomenons. Be a scientist, in this sense, that is give something to know, therefore means be literary. Finally, this conception of science consist in a philosophiacl conception of Universe as a whole where everything links together, and is united by analogical relations, that base and justify the use of a symbolist style.

Létitia Mouze

2006-05-01

417

Tassements référentiels sur la décharge réhabilitée d’Agadir et suivi des biogaz  

OpenAIRE

La recirculation et réinjection des lixiviats dans le corps des anciens déchets, après leurs couverture finale, est mise en œuvre à titre d’essai sur une partie de la décharge réhabilité pour accélérer la biodégradation de la matière organique, augmenter la production des biogaz et par conséquent favoriser d’avantage la stabilité du massif des déchets. Afin d’assurer une valorisation et une exploitation rationnelle, au niveau environnemental et économique, les biogaz pro...

Ahmed Elkadi; Mostapha Maatouk; Mohammed Raissouni; Tahiri Zakariyae Djebary; Abderrahim Mouhssine

2014-01-01

418

Ville et environnement  

OpenAIRE

Le texte aborde différentes facettes des relations entre ville et environnement : l'approche classique par les sites urbains, la transformation des milieux naturels par l'u