| variation of clonal, mesquite-associated rhizobial and bradyrhizobial populations from surface and deep soils by symbiotic gene region restriction fragment length polymorphism and plasmid profile analysis. | genetic characteristics of 14 rhizobium and 9 bradyrhizobium mesquite (prosopis glandulosa)-nodulating strains isolated from surface (0- to 0.5-m) and deep (4- to 6-m) rooting zones were determined in order to examine the hypothesis that surface- and deep-soil symbiont populations were related but had become genetically distinct during adaptation to contrasting soil conditions. to examine genetic diversity, southern blots of psti-digested genomic dna were sequentially hybridized with the noddabc ... | 1994 | 16349226 |
| genetic structure of rhizobium leguminosarum biovar trifolii and viciae populations found in two oregon soils under different plant communities. | an investigation was carried out to determine the genetic structure in soil populations of rhizobium leguminosarum bv. trifolii and viciae at each of two oregon sites (a and c) that were 1 km apart. although the soils were similar, the plant communities were quite different because grazing by domestic animals had been allowed (site a) or prevented (site c). analysis of allelic variation at 13 enzyme-encoding loci by multilocus enzyme electrophoresis delineated 202 chromosomal types (ets) among a ... | 1994 | 16349348 |
| fingerprinting of cyanobacteria based on pcr with primers derived from short and long tandemly repeated repetitive sequences. | the presence of repeated dna (short tandemly repeated repetitive [strr] and long tandemly repeated repetitive [ltrr]) sequences in the genome of cyanobacteria was used to generate a fingerprint method for symbiotic and free-living isolates. primers corresponding to the strr and ltrr sequences were used in the pcr, resulting in a method which generate specific fingerprints for individual isolates. the method was useful both with purified dna and with intact cyanobacterial filaments or cells as te ... | 1998 | 16349487 |
| the vibrio fischeri-euprymna scolopes light organ association: current ecological paradigms. | | 1998 | 16349524 |
| lipopolysaccharide profiles from nodules as markers of bradyrhizobium strains nodulating wild legumes. | to develop the use of electrophoretic lipopolysaccharide profiles for bradyrhizobium strain identification, we studied the feasibility of using electrophoresis of whole legume nodule homogenates to obtain distinctive lipopolysaccharide profiles. the electrophoretic patterns were the same whether we used nodule extracts, bacteroids, or cultured bacteria as samples, and there was no evidence of changes in the ladder-like pattern during the nodulation process. to assess the reliability of using lip ... | 1998 | 16349529 |
| distribution of a population of rhizobium leguminosarum bv. trifolii among different size classes of soil aggregates. | a combination of the plant infection-soil dilution technique (most-probable-number [mpn] technique) and immunofluorescence direct count (ifdc) microscopy was used to examine the effects of three winter cover crop treatments on the distribution of a soil population of rhizobium leguminosarum bv. trifolii across different size classes of soil aggregates (<0.25, 0.25 to 0.5, 0.5 to 1.0, 1.0 to 2.0, and 2.0 to 5.0 mm). the aggregates were prepared from a willamette silt loam soil immediately after h ... | 1998 | 16349531 |
| effects of ionic and osmotic strength on the glucosyltransferase of rhizobium meliloti responsible for cyclic beta-(1,2)-glucan biosynthesis. | the cyclic beta-(1,2)-glucans of rhizobium meliloti and agrobacterium tumefaciens play an important role during hypoosmotic adaptation, and the synthesis of these compounds is osmoregulated. glucosyltransferase, the enzyme responsible for cyclic beta-(1,2)-glucan biosynthesis, is present constitutively, suggesting that osmotic regulation of the biosynthesis of these glucans occurs through modulation of enzyme activity. in this study, we examined regulation of cyclic glucan biosynthesis in vitro ... | 1998 | 16349538 |
| exopolysaccharide structure is not a determinant of host-plant specificity in nodulation of vicia sativa roots. | exopolysaccharide (eps)-deficient strains of the root nodule symbiote rhizobium leguminosarum induce formation of abortive infection threads in vicia sativa subsp. nigra roots. as a result, the nodule tissue remains uninfected. formation of an infection thread can be restored by coinoculation of the eps-deficient mutant with a nod factor-deficient strain, which produces a similar eps structure. this suggests that eps contributes to host-plant specificity of nodulation. here, a comparison was mad ... | 2005 | 16353547 |
| [hydrogen peroxide content and catalase activity at inoculation with root tubercle bacteria of pea seedlings with the various nodulation ability]. | hydrogen peroxide (h2o2) content and catalase activity were studied in pea (pisum sativum l.) seedlings with normal (cultivar marat) and disrupted (pea mutants) process of nodulation, which were inoculated with the nitrogen-fixing bacterium rhizobium leguminosarum strain ciam 1026. differences in hydrogen peroxide content and catalase activity in pea seedlings with different ability for nodulation, which were inoculated with rhizobia, were found. it was assumed that h2o2 and catalase are involve ... | 2005 | 16358750 |
| the brucella suis type iv secretion system assembles in the cell envelope of the heterologous host agrobacterium tumefaciens and increases incq plasmid pls1 recipient competence. | pathogenic brucella species replicate within mammalian cells, and their type iv secretion system is essential for intracellular survival and replication. the options for biochemical studies on the brucella secretion system are limited due to the rigidity of the cells and biosafety concerns, which preclude large-scale cell culture and fractionation. to overcome these problems, we heterologously expressed the brucella suis virb operon in the closely related alpha(2)-proteobacterium agrobacterium t ... | 2006 | 16368963 |
| bla(imp-9) and its association with large plasmids carried by pseudomonas aeruginosa isolates from the people's republic of china. | a novel plasmid-mediated metallo-beta-lactamase (imp-9) is described in seven isolates of pseudomonas aeruginosa from guangzhou, china, isolated in 2000. the gene was carried on a large (approximately 450-kb) incp-2 conjugative plasmid. this is the first report of carriage of bla(imp) genes on such large plasmids. | 2006 | 16377710 |
| regulation of the mycobacterium tuberculosis mce1 operon. | in the murine model of infection, a mycobacterium tuberculosis mce1 operon mutant elicits an aberrant granulomatous response, resulting in uncontrolled replication and failure to enter a persistent state. in this study, we demonstrate that the mce1 genes can be transcribed as a 13-gene polycistronic message encompassing rv0166 to rv0178. quantitative reverse transcriptase pcr and immunoblot analyses revealed that the mce1 genes and proteins are expressed during in vitro growth but are significan ... | 2006 | 16385033 |
| the iron control element, acting in positive and negative control of iron-regulated bradyrhizobium japonicum genes, is a target for the irr protein. | bradyrhizobium japonicum, the nitrogen-fixing soybean symbiont, possesses a heme uptake system encoded by the gene cluster hmuvut-hmur-exbbd-tonb. transcription of the divergently oriented hmut and hmur genes was previously found to be induced by iron limitation and to depend on a 21-bp promoter-upstream iron control element (ice). here, we show by deletion analysis that the full-length ice is needed for this type of positive control. additional genes associated with ice-like motifs were identif ... | 2006 | 16385063 |
| putative abc transporter responsible for acetic acid resistance in acetobacter aceti. | two-dimensional gel electrophoretic analysis of the membrane fraction of acetobacter aceti revealed the presence of several proteins that were produced in response to acetic acid. a 60-kda protein, named aata, which was mostly induced by acetic acid, was prepared; aata was cloned on the basis of its nh2-terminal amino acid sequence. aata, consisting of 591 amino acids and containing atp-binding cassette (abc) sequences and abc signature sequences, belonged to the abc transporter superfamily. the ... | 2006 | 16391084 |
| identification of a ubiquinone-binding site that affects autophosphorylation of the sensor kinase regb. | rhodobacter capsulatus regulates many metabolic processes in response to the level of environmental oxygen and the energy state of the cell. one of the key global redox regulators of the cell's metabolic physiology is the sensor kinase regb that controls the synthesis of numerous energy generation and utilization processes. in this study, we have succeeded in purifying full-length regb containing six transmembrane-spanning elements. exogenous addition of excess oxidized coenzyme q1 is capable of ... | 2006 | 16407278 |
| atgat1, a high affinity transporter for gamma-aminobutyric acid in arabidopsis thaliana. | functional characterization of arabidopsis thaliana gat1 in heterologous expression systems, i.e. saccharomyces cerevisiae and xenopus laevis oocytes, revealed that atgat1 (at1g08230) codes for an h(+)-driven, high affinity gamma-aminobutyric acid (gaba) transporter. in addition to gaba, other omega-aminofatty acids and butylamine are recognized. in contrast to the most closely related proteins of the proline transporter family, proline and glycine betaine are not transported by atgat1. atgat1 d ... | 2006 | 16407306 |
| visualization of nodulation gene activity on the early stages of rhizobium leguminosarum bv. viciae symbiosis. | a technique was optimized for the in situ detection of nodulation (nod) gene activity in rhizobium leguminosarum bv. viciae symbiosis with compatible plant hosts vicia tetrasperma (l.) schreb. and pisum sativum l. the transcription of nodabc-lacz fusion was visualized as beta-galactosidase (beta-gal) activity after reaction with the chromogenic substrate x-gal and subsequent light microscopy, while the background of the indigenous beta-gal activity of rhizobia and the host plant was eliminated b ... | 2005 | 16408851 |
| the yjeb (nsrr) gene of escherichia coli encodes a nitric oxide-sensitive transcriptional regulator. | microarray studies of the escherichia coli response to nitric oxide and nitrosative stress have suggested that additional transcriptional regulators of this response remain to be characterized. we identify here the product of the yjeb gene as a negative regulator of the transcription of the ytfe, hmpa and ygba genes, all of which are known to be upregulated by nitrosative stress. transcriptional fusions to the promoters of these genes were expressed constitutively in a yjeb mutant, indicating th ... | 2006 | 16428390 |
| isolation and identification of natural endophytic rhizobia from rice (oryza sativa l.) through rdna pcr-rflp and sequence analysis. | three novel endophytic rhizobial strains (rre3, rre5, and rre6) were isolated from naturally growing surface sterilized rice roots. these isolates had the ability to nodulate common bean (phaseolus vulgaris). polymerase chain reaction-restriction fragment length polymorphism and sequencing of 16s rdna of these isolates revealed that rre3 and rre5 are phylogenetically very close to burkholderia cepacia complex, whereas rre6 has affinity with rhizobium leguminosarum bv. phaseoli. plant infection t ... | 2006 | 16450073 |
| genetic and transcriptional analysis of the siderophore malleobactin biosynthesis and transport genes in the human pathogen burkholderia pseudomallei k96243. | burkholderia pseudomallei is a gram-negative facultative intracellular pathogen that causes melioidosis, an invasive disease of humans and animals. to address the response of this bacterium to iron-limiting conditions, we first performed a global transcriptional analysis of rna extracted from bacteria grown under iron-limiting and iron-rich conditions by microarrays. we focused our study on those open reading frames (orfs) induced under iron limitation, which encoded predicted proteins that coul ... | 2006 | 16452439 |
| cloning of the symbiotic region of rhizobium leguminosarum: the nodulation genes are between the nitrogenase genes and a nifa-like gene. | the region of the rhizobium leguminosarum plasmid prl1ji involved in nodulation and nitrogen fixation has been cloned on a series of four overlapping cosmid clones. these clones represent 60 kb of prl1ji dna on which a series of tn5-induced fix and nod alleles have been identified, with the two most distant alleles being separated by 45 kb of dna. the mutant alleles fell into three groups, two clusters of fix alleles separated by one cluster of nod alleles. within one group of fix alleles, dna h ... | 1983 | 16453461 |
| the nodd gene of rhizobium leguminosarum is autoregulatory and in the presence of plant exudate induces the noda,b,c genes. | 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 beta-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 hy ... | 1985 | 16453650 |
| the rhizobium leguminosarum nodulation gene nodf encodes a polypeptide similar to acyl-carrier protein and is regulated by nodd plus a factor in pea root exudate. | the dna sequence of approximately 3.5 kb of the nodulation (nod) region of the rhizobium leguminosarum symbiotic plasmid prl1ji was determined. three open reading frames were identified; genes corresponding to these have been called nodd, node and nodf.nodd is adjacent to noda and is transcribed in the opposite direction. the nodf and node genes are downstream of, and transcribed in the same direction as, nodd with 667 nucleotides between nodd and nodf and three nucleotides separating nodf and n ... | 1986 | 16453679 |
| clovers secrete specific phenolic compounds which either stimulate or repress nod gene expression in rhizobium trifolii. | 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 umbell ... | 1987 | 16453763 |
| engineering plant-microbe symbiosis for rhizoremediation of heavy metals. | the use of plants for rehabilitation of heavy-metal-contaminated environments is an emerging area of interest because it provides an ecologically sound and safe method for restoration and remediation. although a number of plant species are capable of hyperaccumulation of heavy metals, the technology is not applicable for remediating sites with multiple contaminants. a clever solution is to combine the advantages of microbe-plant symbiosis within the plant rhizosphere into an effective cleanup te ... | 2006 | 16461658 |
| coexistence of burkholderia, cupriavidus, and rhizobium sp. nodule bacteria on two mimosa spp. in costa rica. | rrna gene sequencing and pcr assays indicated that 215 isolates of root nodule bacteria from two mimosa species at three sites in costa rica belonged to the genera burkholderia, cupriavidus, and rhizobium. this is the first report of cupriavidus sp. nodule symbionts for mimosa populations within their native geographic range in the neotropics. burkholderia spp. predominated among samples from mimosa pigra (86% of isolates), while there was a more even distribution of cupriavidus, burkholderia, a ... | 2006 | 16461667 |
| catabolism of 1,5-anhydro-d-fructose in sinorhizobium morelense s-30.7.5: discovery, characterization, and overexpression of a new 1,5-anhydro-d-fructose reductase and its application in sugar analysis and rare sugar synthesis. | the bacterium sinorhizobium morelense s-30.7.5 was isolated by a microbial screening using the sugar 1,5-anhydro-d-fructose (af) as the sole carbon source. this strain metabolized af by a novel pathway involving its reduction to 1,5-anhydro-d-mannitol (am) and the further conversion of am to d-mannose by c-1 oxygenation. growth studies showed that the af metabolizing capability is not confined to s. morelense s-30.7.5 but is a more common feature among the rhizobiaceae. the af reducing enzyme wa ... | 2006 | 16461673 |
| several archaeal homologs of putative oligopeptide-binding proteins encoded by thermotoga maritima bind sugars. | the hyperthermophilic bacterium thermotoga maritima has shared many genes with archaea through horizontal gene transfer. several of these encode putative oligopeptide atp binding cassette (abc) transporters. we sought to test the hypothesis that these transporters actually transport sugars by measuring the substrate affinities of their encoded substrate-binding proteins (sbps). this information will increase our understanding of the selective pressures that allowed this organism to retain these ... | 2006 | 16461685 |
| expression cloning and periplasmic orientation of the francisella novicida lipid a 4'-phosphatase lpxf. | francisella tularensis and related intracellular pathogens synthesize lipid a molecules that differ from their escherichia coli counterparts. although a functional orthologue of lpxk, the gene encoding the lipid a 4'-kinase, is present in francisella, no 4'-phosphate moiety is attached to francisella lipid a. we now demonstrate that a membrane-bound phosphatase present in francisella novicida u112 selectively removes the 4'-phosphate residue from tetra- and pentaacylated lipid a molecules. a clo ... | 2006 | 16467300 |
| determination of the amino acid residues required for the activity of the anti-rhizobial peptide antibiotic trifolitoxin. | the first aim was to determine those amino acid residues required for the biological activity of the potent peptide antibiotic, trifolitoxin (tfx). the second aim was to determine the concentrations of tfx1 and tfx2 that cause 50% inhibition of bacterial growth (ki), the two predominant isomeric forms of tfx made by rhizobium. | 2006 | 16478489 |
| rhizobial exopolysaccharides: genetic control and symbiotic functions. | specific complex interactions between soil bacteria belonging to rhizobium, sinorhizobium, mesorhizobium, phylorhizobium, bradyrhizobium and azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosacchari ... | 2006 | 16483356 |
| a luxr/luxi-type quorum-sensing system in a plant bacterium, mesorhizobium tianshanense, controls symbiotic nodulation. | the ability of rhizobia to symbiotically fix nitrogen from the atmosphere when forming nodules on their plant hosts requires various signal transduction pathways. luxr-luxi-type quorum-sensing systems have been shown to be one of the players in a number of rhizobium species. in this study, we found that mesorhizobium tianshanense, a moderate-growth rhizobium that forms nodules on a number of licorice plants, produces multiple n-acyl homoserine lactone (ahl)-like molecules. a simple screen for ah ... | 2006 | 16484206 |
| health considerations regarding horizontal transfer of microbial transgenes present in genetically modified crops. | the potential effects of horizontal gene transfer on human health are an important item in the safety assessment of genetically modified organisms. horizontal gene transfer from genetically modified crops to gut microflora most likely occurs with transgenes of microbial origin. the characteristics of microbial transgenes other than antibiotic-resistance genes in market-approved genetically modified crops are reviewed. these characteristics include the microbial source, natural function, function ... | 2005 | 16489267 |
| in vitro characterization of a bacterial manganese uptake regulator of the fur superfamily. | fur proteins generally act as negative transcriptional regulators by binding to target regulatory sequences (fur boxes) in the promoter regions of iron-responsive genes. recently, rhizobium leguminosarum was reported to contain a protein (mur(rl)) of fur-like sequence, which, under manganese-replete conditions in its native background, repressed transcription of an abc-type mn(ii) transporter by binding to two nonpalindromic mur boxes in its promoter region. mur(rl) displays apparently unusual r ... | 2006 | 16489762 |
| dodecaprenyl phosphate-galacturonic acid as a donor substrate for lipopolysaccharide core glycosylation in rhizobium leguminosarum. | the lipid a and inner core regions of rhizobium leguminosarum lipopolysaccharide contain four galacturonic acid (gala) residues. two are attached to the outer unit of the 3-deoxy-d-manno-octulosonic acid (kdo) disaccharide, one to the mannose residue, and one to the 4'-position of lipid a. the enzymes rgta and rgtb, described in the accompanying article, catalyze gala transfer to the kdo residue, whereas rgtc is responsible for modification of the core mannose unit. heterologous expression of rg ... | 2006 | 16497671 |
| expression cloning of three rhizobium leguminosarum lipopolysaccharide core galacturonosyltransferases. | the lipid a and core regions of the lipopolysaccharide in rhizobium leguminosarum, a nitrogen-fixing plant endosymbiont, are strikingly different from those of escherichia coli. in r. leguminosarum lipopolysaccharide, the inner core is modified with three galacturonic acid (gala) moieties, two on the distal 3-deoxy-d-manno-octulosonic acid (kdo) unit and one on the mannose residue. here we describe the expression cloning of three novel gala transferases from a 22-kb r. leguminosarum genomic dna ... | 2006 | 16497674 |
| the pea nodule environment restores the ability of a rhizobium leguminosarum lipopolysaccharide acpxl mutant to add 27-hydroxyoctacosanoic acid to its lipid a. | members of the rhizobiaceae contain 27-hydroxyoctacosanoic acid (27ohc(28:0)) in their lipid a. a rhizobium leguminosarum 3841 acpxl mutant (named here rlv22) lacking a functional specialized acyl carrier lacked 27ohc(28:0) in its lipid a, had altered growth and physiological properties (e.g., it was unable to grow in the presence of an elevated salt concentration [0.5% nacl]), and formed irregularly shaped bacteroids, and the synchronous division of this mutant and the host plant-derived symbio ... | 2006 | 16513742 |
| regulation of long-chain n-acyl-homoserine lactones in agrobacterium vitis. | homologs of quorum-sensing luxr and luxi regulatory genes, avsr and avsi, were identified in agrobacterium vitis strain f2/5. compared to other luxi proteins from related species, the deduced avsi shows the greatest identity to sini (71%) from sinorhizobium meliloti rm1021. avsr possesses characteristic autoinducer binding and helix-turn-helix dna binding domains and shares a high level of identity with sinr (38%) from rm1021. site-directed mutagenesis of avsr and avsi was performed, and both ge ... | 2006 | 16513747 |
| global control of cysteine metabolism by cymr in bacillus subtilis. | yrzc has previously been identified as a repressor controlling ytmi expression via its regulation of ytli activator synthesis in bacillus subtilis. we identified yrzc as a master regulator of sulfur metabolism. gene expression profiles of b. subtilis delta yrzc mutant and wild-type strains grown in minimal medium with sulfate as the sole sulfur source were compared. in the mutant, increased expression was observed for 24 genes previously identified as repressed in the presence of sulfate. since ... | 2006 | 16513748 |
| an empirical test of partner choice mechanisms in a wild legume-rhizobium interaction. | mutualisms can be viewed as biological markets in which partners of different species exchange goods and services to their mutual benefit. trade between partners with conflicting interests requires mechanisms to prevent exploitation. partner choice theory proposes that individuals might foil exploiters by preferentially directing benefits to cooperative partners. here, we test this theory in a wild legumerhizobium symbiosis. rhizobial bacteria inhabit legume root nodules and convert atmospheric ... | 2006 | 16519238 |
| an empirical test of partner choice mechanisms in a wild legume-rhizobium interaction. | mutualisms can be viewed as biological markets in which partners of different species exchange goods and services to their mutual benefit. trade between partners with conflicting interests requires mechanisms to prevent exploitation. partner choice theory proposes that individuals might foil exploiters by preferentially directing benefits to cooperative partners. here, we test this theory in a wild legumerhizobium symbiosis. rhizobial bacteria inhabit legume root nodules and convert atmospheric ... | 2006 | 16519238 |
| proteomic analysis of quorum sensing in rhizobium leguminosarum biovar viciae upm791. | production of quorum-sensing signal molecules of the acyl-homoserine lactone (ahl) type by rhizobium leguminosarum bv. viciae upm791 is dependent on its plasmid content. curing of two of its four native plasmids, pupm791d and psym, resulted in loss of production of the largest (c(14)) and the three smaller (c(6)-c(8)) ahls, respectively. introduction of a lactonase-containing plasmid resulted in ahl signal degradation and quorum quenching. the quorum-dependent proteome was studied in these strai ... | 2006 | 16521149 |
| the rhizobium etli sigma70 (siga) factor recognizes a lax consensus promoter. | a collection of rhizobium etli promoters was isolated from a genomic dna library constructed in the promoter-trap vector pbbmcs53, by their ability to drive the expression of a gusa reporter gene. thirty-seven clones were selected, and their transcriptional start-sites were determined. the upstream sequence of these 37 start-sites, and the sequences of seven previously identified promoters were compared. on the basis of sequence conservation and mutational analysis, a consensus sequence cttgacn1 ... | 2006 | 16528104 |
| early interactions of rhizobium leguminosarum bv. phaseoli and bean roots: specificity in the process of adsorption and its requirement of ca(sup2+) and mg(sup2+) ions. | roots of phaseolus vulgaris l. were incubated with dilute suspensions (1 x 10(sup3) to 3 x 10(sup3) bacteria ml(sup-1)) of an antibiotic-resistant indicator strain of rhizobium leguminosarum bv. phaseoli in mineral medium and washed four times by a standardized procedure prior to quantitation of adsorption (g. caetano-anolles and g. favelukes, appl. environ. microbiol. 52:371-376, 1986). the population of rhizobia remaining adsorbed on roots after washing was homogeneous, as indicated by the fir ... | 1995 | 16535005 |
| influence of bovine slurry deposition on the structure of nodulating rhizobium leguminosarum bv. viciae soil populations in a natural habitat. | the population of nodulating r. leguminosarum bv. viciae in soil from a grass-covered valley area which had been used for bovine slurry deposition over a period of 5 years was analyzed. for these studies, a rapid and reproducible method based on enterobacterial repetitive intergenic consensus (eric)-pcr was applied to identify rhizobium strains which had infected pea nodules. soil samples were taken from different areas and further analyzed in plant tests to determine the impact of the applicati ... | 1996 | 16535318 |
| distribution of symbiotic genotypes in rhizobium leguminosarum biovar viciae populations isolated directly from soils. | the distribution of symbiotic (sym) plasmid types across background genotypes was investigated in two field populations of rhizobium leguminosarum biovar viciae isolated directly from soils. pcr-based methods were used to characterize the background genotypes and the sym gene types. identical sym gene types were associated with a variable range of background genotypes, while the same background genotype could harbor distinct sym gene types. random distributions of sym gene types in the backgroun ... | 1996 | 16535447 |
| eukaryotic control on bacterial cell cycle and differentiation in the rhizobium-legume symbiosis. | symbiosis between legumes and rhizobium bacteria leads to the formation of root nodules where bacteria in the infected plant cells are converted into nitrogen-fixing bacteroids. nodules with a persistent meristem are indeterminate, whereas nodules without meristem are determinate. the symbiotic plant cells in both nodule types are polyploid because of several cycles of endoreduplication (genome replication without mitosis and cytokinesis) and grow consequently to extreme sizes. here we demonstra ... | 2006 | 16547129 |
| a novel polar surface polysaccharide from rhizobium leguminosarum binds host plant lectin. | rhizobium bacteria produce different surface polysaccharides which are either secreted in the growth medium or contribute to a capsule surrounding the cell. here, we describe isolation and partial characterization of a novel high molecular weight surface polysaccharide from a strain of rhizobium leguminosarum that nodulates pisum sativum (pea) and vicia sativa (vetch) roots. carbohydrate analysis showed that the polysaccharide consists for 95% of mannose and glucose, with minor amounts of galact ... | 2006 | 16553877 |
| respiratory enzyme systems in symbiotic nitrogen fixation: iii. the dehydrogenase systems of rhizobium trifolii and rhizobium leguminosarum. | | 1941 | 16560421 |
| a medium adapted to the bacteriophage of rhizobium leguminosarum. | | 1943 | 16560646 |
| studies on lyophiled cultures: lyophile storage of cultures of rhizobium leguminosarum. | | 1946 | 16561164 |
| the production of species-specific highly unsaturated fatty acyl-containing lcos from rhizobium leguminosarum bv. trifolii is stringently regulated by nodd and involves the nodrl genes. | a proportion of the nod factors of some rhizobium leguminosarum bv. trifolii strains is characterized by the presence of highly unsaturated fatty acyl chains containing trans double bonds in conjugation with the carbonyl group of the glycan oligosaccharide backbone. these fatty acyl chains are c18:3, c20:3, c18:4, or c20:4 and have uv-absorption maxima at 303 and 330 nm. these nod factors are presumed to be important for host-specific nodulation on clover species. however, in wild-type r. legumi ... | 2006 | 16570652 |
| bradyrhizobium japonicum senses iron through the status of haem to regulate iron homeostasis and metabolism. | the irr protein from the bacterium bradyrhizobium japonicum is expressed under iron limitation to mediate iron control of haem biosynthesis. the regulatory input to irr is the status of haem and its precursors iron and protoporphyrin at the site of haem synthesis. here, we show that irr controls the expression of iron transport genes and many other iron-regulated genes not directly involved in haem synthesis. irr is both a positive and negative effector of gene expression, and in at least some c ... | 2006 | 16573691 |
| intra- and interspecies transfer and expression of rhizobium japonicum hydrogen uptake genes and autotrophic growth capability. | cosmids containing hydrogen uptake genes have previously been isolated in this laboratory. four new cosmids that contain additional hup gene(s) have now been identified by conjugal transfer of a rhizobium japonicum 122des gene bank into a tn5-generated hup(-) mutant and screening for the acquisition of hup activity. the newly isolated cosmids, phu50-phu53, contain part of the previously isolated phu1 but extend as far as 20 kilobases beyond its border. phu52 complements five of six hup(-) mutant ... | 1985 | 16578786 |
| baca-mediated bleomycin sensitivity in sinorhizobium meliloti is independent of the unusual lipid a modification. | sinorhizobium meliloti baca mutants are symbiotically defective, deoxycholate sensitive, and bleomycin resistant. we show that the bleomycin resistance phenotype is independent of the lipid a alteration and that the changes giving rise to both phenotypes are likely to be involved in the inability of baca mutants to persist within their hosts. | 2006 | 16585777 |
| rhizobium-mediated induction of phenolics and plant growth promotion in rice (oryza sativa l.). | 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 cinna ... | 2006 | 16586021 |
| isolation and identification of natural endophytic rhizobia from rice (oryza sativa l.) through rdna pcr-rflp and sequence analysis. | three novel endophytic rhizobial strains (rre3, rre5, and rre6) were isolated from naturally growing surface-sterilized rice roots. these isolates had the ability to nodulate common bean (phaseolus vulgaris). polymerase chain reaction-restriction fragment length polymorphism (pcr-rflp) and sequencing of 16s rdna of these isolates revealed that rre3 and rre5 are phylogenetically very close to burkholderia cepacia complex, whereas rre6 has affinity with rhizobium leguminosarum bv. phaseoli. plant ... | 2006 | 16586025 |
| c(4)-dicarboxylate transport mutants of rhizobium trifolii form ineffective nodules on trifolium repens. | mutants of rhizobium trifolii strain 7012 defective in c(4)-dicarboxylate transport were isolated by using a selective procedure based on ph indicator media. the mutant strains cr7098 and cr7099 failed to grow on or transport succinate, fumarate, or malate, but grew at wild-type rates on several other carbon sources. the c(4)-dicarboxylate transport system was inducible in strain 7012, but was expressed constitutively in four out of five succinate-positive revertants of strain cr7098. in the fif ... | 1981 | 16593058 |
| rhizobium meliloti genes required for nodule development are related to chromosomal virulence genes in agrobacterium tumefaciens. | symbiotically essential genes have been identified in rhizobium meliloti that are structurally and functionally related to chromosomal virulence (chv) genes of agrobacterium tumefaciens. homologous sequences also exist in the genomes of other fast-growing rhizobia including rhizobium trifolii, rhizobium leguminosarum, and rhizobium phaseoli. in agrobacterium, the chva and chvb loci are known to be essential for oncogenic transformation of dicotyledonous plants and for attachment to plant cells [ ... | 1986 | 16593714 |
| induction of bradyrhizobium japonicum common nod genes by isoflavones isolated from glycine max. | the early events in legume nodulation by rhizobium spp. involve a conserved gene cluster known as the common nod region. a broad-host-range plasmid (pea2-21) containing a bradyrhizobium japonicum noddabc-lacz translational fusion was constructed and used to monitor nod gene expression in response to soybean root extract. two inducing compounds were isolated and identified. analysis using ultraviolet absorption spectra, proton nuclear magnetic resonance, and mass spectrometry showed that the two ... | 1987 | 16593884 |
| isolation of genes involved in nodulation competitiveness from rhizobium leguminosarum bv. trifolii t24. | rhizobium leguminosarum bv. trifolii t24 produces a potent anti-rhizobial compound, trifolitoxin, and exclusively nodulates clover roots when in mixed inoculum with trifolitoxin-sensitive strains of r. leguminosarum bv. trifolii [schwinghamer, e. a. & belkengren r. p. (1968) arch. mikrobiol. 64, 130-145]. in the present study, the isolation of trifolitoxin production and resistance genes is described. a cosmid genomic library of t24 was prepared in plafr3. no trifolitoxin expression was observed ... | 1988 | 16593933 |
| identification and functional characterization of the lactococcus lactis cody-regulated branched-chain amino acid permease bcap (ctra). | transcriptome analyses have previously revealed that a gene encoding the putative amino acid transporter ctra (yhdg) is one of the major targets of the pleiotropic regulator cody in lactococcus lactis and bacillus subtilis. the role of ctra in l. lactis was further investigated with respect to both transport activity as well as cody-mediated regulation. ctra is required for optimal growth in media containing free amino acids as the only amino acid source. amino acid transport studies showed that ... | 2006 | 16621821 |
| the rhizobium leguminosarum regulator irra affects the transcription of a wide range of genes in response to fe availability. | we show that an unusual transcriptional regulator, called irra, regulates many genes in the symbiotic n2-fixing bacterium rhizobium leguminosarum in response to iron availability. several operons in r. leguminosarum are expressed at lower levels in cells grown in fe-depleted compared to fe-replete medium. these include hema1, which encodes the haem biosynthesis enzyme amino-levulinic acid synthase; sufs2bcds1xa, which specify enzymes for fes cluster synthesis; rira, a global, fe-responsive trans ... | 2006 | 16625355 |
| investigations of rhizobium biofilm formation. | the development of nitrogen-fixing nodules of the rhizobium-legume symbiosis, especially the early stages of root hair deformation and curling, infection thread formation, and nodule initiation, has been well studied from a genetic standpoint. in contrast, the factors important for the colonization of surfaces by rhizobia, including roots-an important prerequisite for nodule formation-have not been as thoroughly investigated. we developed conditions for analyzing the ability of two fast-growing ... | 2006 | 16629750 |
| the genome of rhizobium leguminosarum has recognizable core and accessory components. | rhizobium leguminosarum is an alpha-proteobacterial n2-fixing symbiont of legumes that has been the subject of more than a thousand publications. genes for the symbiotic interaction with plants are well studied, but the adaptations that allow survival and growth in the soil environment are poorly understood. we have sequenced the genome of r. leguminosarum biovar viciae strain 3841. | 2006 | 16640791 |
| gaba controls the level of quorum-sensing signal in agrobacterium tumefaciens. | the concentration of gaba increases rapidly in wounded plant tissues, but the implication of this gaba pulse for plant-bacteria interactions is not known. here we reveal that gaba stimulated the inactivation of the n-(3-oxooctanoyl)homoserine lactone (oc8-hsl) quorum-sensing signal (or "quormone") by the agrobacterium lactonase attm. gaba induced the expression of the attklm operon, which was correlated to a decrease in oc8-hsl concentration in agrobacterium tumefaciens cultures. the agrobacteri ... | 2006 | 16645034 |
| labeling of carbon pools in bradyrhizobium japonicum and rhizobium leguminosarum bv viciae bacteroids following incubation of intact nodules with co(2). | the aim of the work reported here was to ascertain that the patterns of labeling seen in isolated bacteroids also occurred in bacteroids in intact nodules and to observe early metabolic events following exposure of intact nodules to (14)co(2). intact nodules of soybean (glycine max l. merr. cv ripley) inoculated with bradyrhizobium japonicum usda 110 and pea (pisum sativum l. cv progress 9) inoculated with rhizobium leguminosarum bv viciae isolate 128c53 were detached and immediately fed (14)co( ... | 1992 | 16653034 |
| the flavin content of clovers relative to symbiosis with a riboflavin-requiring mutant of rhizobium trifoli. | a riboflavin-requiring auxotroph of rhizobium trifolii (t1/d-his(r)-15) formed ineffective root nodules on red clover and on two cultivars of subterranean clover, but produced almost fully effective nodules on several other cultivars of subterranean clover. fluorescence and bioassay measurements of the flavin content of the roots and shoots of these cultivars revealed no differences between cultivars which could be correlated with the differences in symbiotic response. the concentration of flavi ... | 1974 | 16658676 |
| interdependence of nitrogen nutrition and photosynthesis in pisum sativum l: i. effect of combined nitrogen on symbiotic nitrogen fixation and photosynthesis. | photosynthesis, primary productivity, n content, and n(2) fixation were determined as a function of applied nh(4) (+) in peas (pisum sativum l. cv. alaska) which were inoculated or not inoculated with rhizobium leguminosarum. cabon dioxide exchange rate (cer) increased 10-fold, total n content 7-fold, and total dry weight 3-fold in 26-day-old uninoculated plants as applied nh(4) (+) was increased from 0 to 16 millimolar. in inoculated plants of the same age cer and dry weight were maximal at 2 m ... | 1978 | 16660450 |
| interdependence of nitrogen nutrition and photosynthesis in pisum sativum l: ii. host plant response to nitrogen fixation by rhizobium strains. | physiological responses to infection by strains of rhizobium leguminosarum which differed in their capacity to reduce n(2) were determined in 26-day-old pea plants (pisum sativum l. cv. alaska) grown under uniform environmental conditions in the absence of combined n. the highest n(2) reduction rates, calculated from h(2) evolution and c(2)h(2)-dependent c(2)h(4) production measurements, were approximately 6-fold greater than the lowest. higher n(2) fixation rates were associated with greater co ... | 1978 | 16660451 |
| host-symbiont interactions: iii. purification and partial characterization of rhizobium lipopolysaccharides. | the lipopolysaccharides of three strains each of rhizobium leguminosarum, r. phaseoli, and trifolii have been purified and partially characterized. the last step in the purification procedure is gel filtration column chromatography using sepharose 4b with an elution buffer consisting of ethylenediaminetetraacetic acid and triethylamine. each of the lipopolysaccharides reported in this paper elutes as a symmetrical peak in the partially included volume of this sepharose 4b column. the ratio of 2- ... | 1978 | 16660637 |
| variation in nitrogenase and hydrogenase activity of alaska pea root nodules. | hydrogenase activity of root nodules in the symbiotic association between pisum sativum l. and rhizobium leguminosarum was determined by incubating unexcised nodules with tritiated h(2) and measuring tissue hto. hydrogenase activity saturated at 0.50 millimolar h(2) and was not inhibited by the presence of 0.10 atmosphere c(2)h(2), which prevented h(2) evolution from nitrogenase. total h(2) production from nitogenase was estimated as net h(2) evolution in air plus h(2) exchange in 0.10 atmospher ... | 1979 | 16660819 |
| environmental and genotypic effects on the respiration associated with symbiotic nitrogen fixation in peas. | estimated values for the respiration associated with symbiotic nitrogen fixation in pisum sativum l. were independent of irradiance, temperature, plant age, and co(2) concentration, despite large variation in the total rates of c(2)h(2) reduction and root + nodule respiration. similar values were also found in phaseolus vulgaris l., vicia faba l. and glycine max (l.) merr. among all combinations of four pisum cultivars with four rhizobium leguminosarum inoculants only the plant genotype signific ... | 1979 | 16660833 |
| interactions between rhizobia and lectins of lentil, pea, broad bean, and jackbean. | a quantitative method was developed to measure the binding of fluorescent-labeled lentil (lens esculenta moench), pea (pisum sativum l.), broad bean (vicia faba l.), and jackbean (canavalia ensiformis l., dc.) lectins to various rhizobium strains. lentil lectin bound to three of the five rhizobium leguminosarum strains tested. the number of lentil lectin molecules bound per r. leguminosarum 128c53 cell was 2.1 x 10(4). lentil lectin also bound to r. japonicum 61a133. pea and broad bean lectins b ... | 1980 | 16661328 |
| host-symbiont interactions : v. the structure of acidic extracellular polysaccharides secreted by rhizobium leguminosarum and rhizobium trifolii. | the sequence of the glycosyl residues and the anomeric configurations of the glycosyl linkages of the acidic polysaccharides secreted by rhizobium leguminosarum 128c53, rhizobium leguminosarum 128c63, rhizobium trifolii na30, and rhizobium trifolii 0403 have been determined. all four polysaccharides were found to have the following glycosyl repeating-unit structure, where galactosyl is gal, glucosyl is glc, glucuronosyl is glca, and pyruvyl is pyr: [formula: see text] each of the glycosyl residu ... | 1981 | 16661681 |
| nitrogen stress and apparent photosynthesis in symbiotically grown pisum sativum l. | pea plants (pisum sativum l. cv. alaska) were inoculated individually with one of 15 rhizobium leguminosarum strains and grown under uniform environmental conditions in the absence of combined n. differences in effectiveness of the rhizobium strains produced plants with differing rates of whole plant apparent n(2) fixation and total n content at the same morphological stage of development. plants were analyzed to determine interactions between n(2) fixation, n allocation, apparent photosynthesis ... | 1981 | 16661907 |
| transient susceptibility of root cells in four common legumes to nodulation by rhizobia. | root cells of four common legumes were found to remain susceptible to nodulation by rhizobia for only a short period of time. delayed inoculation experiments conducted with these legume hosts indicated that the initially susceptible region of the root became progressively less susceptible if inoculations were delayed by a few hours. profiles of the frequency of nodule formation relative to marks indicating the regions of root and root hair development at the time of inoculation indicated that no ... | 1981 | 16662065 |
| a comparison of the surface polysaccharides from rhizobium leguminosarum 128c53 smrif with the surface polysaccharides from its exo mutant. | the surface polysaccharides of rhizobium leguminosarum 128c53 sm(r)rif(r) (parent) and its exo(-1) mutant were isolated and characterized. the parent carries out normal symbiosis with its host, pea, while the exo(-1) mutant does not nodulate the pea. the following observations were made. (a) the parent produces lipopolysaccharide (lps), typical acidic extracellular polysaccharide (eps), and three additional polysaccharides, ps1, ps2, and ps3. the ps1 and ps2 fractions are likely to be the capsul ... | 1983 | 16662808 |
| host plant cultivar effects on hydrogen evolution by rhizobium leguminosarum. | the effect of host plant cultivar on h(2) evolution by root nodules was examined in symbioses between pisum sativum l. and selected strains of rhizobium leguminosarum. hydrogen evolution from root nodules containing rhizobium represents the sum of h(2) produced by the nitrogenase enzyme complex and h(2) oxidized by any uptake hydrogenase present in those bacterial cells. relative efficiency (re) calculated as re = 1 - (h(2) evolved in air/c(2) h(2) reduced) did not vary significantly among ;felt ... | 1983 | 16663112 |
| role of lectins in the specific recognition of rhizobium by lotononis bainesii. | fluorescein isothiocyanate (fitc)-labeled lectin purified from the root of lotononis bainesii baker was bound by cells of five out of seven l. bainesii-nodulating strains of rhizobium under culture conditions. with the exception of a strain of rhizobium leguminosarum, strains of noninfective rhizobia failed to bind the root lectin under these conditions. the two nonlectin binding l. bainesii-specific strains did not bind root lectin on the l. bainesii rhizoplane although this was observed with t ... | 1984 | 16663509 |
| effect of temperature on h(2) evolution and acetylene reduction in pea nodules and in isolated bacteroids. | nitrogenase (ec 1.7.99.2) activity in pea (pisum savitum) nodules formed after infection with rhizobium leguminosarum (lacking uptake hydrogenase) was measured as acetylene reduction, h(2) evolution in air and h(2) evolution in ar:o(2). with detached roots the relative efficiency, calculated from acetylene reduction, showed a decrease (from 55 to below 0%) with increasing temperature. with excised nodules and isolated bacteroids similar results were obtained. however, the relative efficiency cal ... | 1985 | 16664054 |
| a structural comparison of the acidic extracellular polysaccharides from rhizobium trifolii mutants affected in root hair infection. | the structures of the acidic extracellular polysaccharides (epss) from several r. trifolii mutants were compared by examining their compositions and their sugar linkages as determined by methylation analysis. these mutant strains were derived from the wild-type r. trifolii anu843 and were unable to induce normal root hair curling (hac- phenotype) or nodulation response (nod- phenotype) in clover plants. these strains included several transposon tn5-induced nod-mutants, strain anu871, which posse ... | 1986 | 16664568 |
| stimulation of nodulation in the clover-rhizobium trifolii 0403 system by penicillin and mecillinam. | the number of nodules produced per clover seedling inoculated with rhizobium trifolii 0403 can be increased almost 2-fold by the addition of penicillin or mecillinam. two-day-old dutch white clover seedlings grown in 250 milliliter boston round jars containing agar-solidified plant growth medium were inoculated with exponentially growing rhizobium trifolii 0403 cells. penicillin or mecillinam (100 micrograms per milliliter) were added immediately or after 24 hours. following 42 days growth, 10 r ... | 1986 | 16664802 |
| the relationship between h(2) evolution and acetylene reduction in pisum sativum-rhizobium leguminosarum symbioses differing in uptake hydrogenase activity. | peas (pisum sativum l.) were inoculated with strains of rhizobium leguminosarum having different levels of uptake hydrogenase (hup) activity and were grown in sterile leonard jars under controlled conditions. rates of h(2) evolution and acetylene reduction were determined for intact nodulated roots at intervals after the onset of darkness or after removal of the shoots. hup activity was estimated using treatment plants or equivalent plants from the growth chamber, by measuring the uptake of h(2) ... | 1986 | 16664984 |
| sodium stimulation of uptake hydrogenase activity in symbiotic rhizobium. | initial observations showed a 100% increase in h(2)-uptake (hup) activity of rhizobium leguminosarum strain 3855 in pea root nodules (pisum sativum l. cv alaska) on plants growing in a baked clay substrate relative to those growing in vermiculite, and an investigation of nutrient factors responsible for the phenomenon was initiated. significantly greater hup activity was first measured in the clay-grown plants 24 days after germination, and higher activity was maintained relative to the vermicul ... | 1986 | 16665057 |
| the isolation and partial characterization of the lipopolysaccharides from several rhizobium trifolii mutants affected in root hair infection. | the lipopolysaccharides (lpss) from rhizobium trifolii anu843 and several transposon (tn5) symbiotic mutants derived from anu843 were isolated and partially characterized. the mutant strains are unable to induce normal root hair curling (hac- phenotype) or nodulation (nod-phenotype) in clover plants. the lpss from the parent and mutants are very similar in composition. analysis by page shows that the lpss consist of higher and lower molecular weight forms. the higher molecular weight form of the ... | 1987 | 16665455 |
| nitrogenase activity in trifolium subterraneum l. in relation to the uptake of nitrate ions. | 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 accumu ... | 1987 | 16665549 |
| trifolitoxin production and nodulation are necessary for the expression of superior nodulation competitiveness by rhizobium leguminosarum bv. trifolii strain t24 on clover. | rhizobium leguminosarum bv. trifolii t24 is ineffective in symbiotic nitrogen fixation, produces a potent antibiotic (referred to here as trifolitoxin) that is bacteriostatic to certain rhizobium strains, and is very competitive for clover root nodulation (ea schwinghamer, rp belkengren 1968 arch mikrobiol 64: 130-145). the primary objective of this work was to demonstrate the roles of nodulation and trifolitoxin production in the expression of nodulation competitiveness by t24. unlike wildtype ... | 1987 | 16665698 |
| root exudates of various host plants of rhizobium leguminosarum contain different sets of inducers of rhizobium nodulation genes. | rhizobium promoters involved in the formation of root nodules on leguminous plants are activated by flavonoids in plant root exudate. a series of rhizobium strains which all contain the inducible rhizobium leguminosarum noda promoter fused to the escherichia coli lacz gene, and which differ only in the source of the regulatory nodd gene, were recently used to show that the regulatory nodd gene determines which flavonoids are able to activate the noda promoter (hp spaink, ca wijffelman, e pees, r ... | 1988 | 16666070 |
| developmentally regulated expression of the gene family for cytosolic glutamine synthetase in pisum sativum. | in pisum sativum, two classes of genes encode distinct isoforms of cytosolic glutamine synthetase (gs). the first class comprises two nearly identical or "twin" gs genes (gs341 and gs132), while the second comprises a single gs gene (gs299) distinct in both coding and noncoding regions from the "twin" gs genes. gene-specific analyses were used to monitor the individual contribution of each gene for cytosolic gs during root nodule development and in cotyledons during germination, two contexts whe ... | 1989 | 16667090 |
| development and partial characterization of nearly isogenic pea lines (pisum sativum l.) that alter uptake hydrogenase activity in symbiotic rhizobium. | some rhizobium bacteria have h(2)-uptake (hup) systems that oxidize h(2) evolved from nitrogenase in leguminous root nodules. pea (pisum sativum l.) cultivars ;ji1205' and ;alaska' produce high hup (hup(++)) and moderate hup (hup(+)) phenotypes, respectively, in rhizobium leguminosarum 128c53. the physiological significance and biochemical basis of this host plant genetic effect are unknown. the purpose of this investigation was to advance basic hup studies by developing nearly isogenic lines of ... | 1990 | 16667415 |
| products of dark co(2) fixation in pea root nodules support bacteroid metabolism. | products of the nodule cytosol in vivo dark [(14)c]co(2) fixation were detected in the plant cytosol as well as in the bacteroids of pea (pisum sativum l. cv "bodil") nodules. the distribution of the metabolites of the dark co(2) fixation products was compared in effective (fix(+)) nodules infected by a wild-type rhizobium leguminosarum (mnf 300), and ineffective (fix(-)) nodules of the r. leguminosarum mutant mnf 3080. the latter has a defect in the dicarboxylic acid transport system of the bac ... | 1990 | 16667422 |
| sym 13-a gene conditioning ineffective nodulation in pisum sativum. | treatment of pisum sativum (l.) cv. ;sparkle' with ethyl methanesulfonic acid (ems) produced a stable mutant, e135f, which forms small, white, ineffective nodules. these nodules exhibit histological zonation typical of an indeterminant nodule, e.g. meristematic, early symbiotic, late symbiotic, and senescent zones. compared with the nitrogen fixing nodules of the parent, the zones are smaller and the nodules senesce prematurely. bacteroids in e135f are less elongated and less differentiated than ... | 1990 | 16667870 |
| anthocyanidins and flavonols, major nod gene inducers from seeds of a black-seeded common bean (phaseolus vulgaris l.). | eleven compounds released from germinating seeds of a black-seeded bean (phaseolus vulgaris l., cv pi165426cs) induce transcription of nod genes in rhizobium leguminosarum biovar phaseoli. aglycones from 10 of those compounds were identified by spectroscopic methods (ultraviolet/visible, proton nuclear magnetic resonance, and mass spectroscopy), and their biological activities were demonstrated by induction of beta-galactosidase activity in r. leguminosarum strains containing noda-lacz or nodc-l ... | 1991 | 16668462 |
| rhizobium nod gene inducers exuded naturally from roots of common bean (phaseolus vulgaris l.). | four compounds exuded from young roots of a black-seeded bean (phaseolus vulgaris l., cv pi165426cs) induce transcription of nod genes in rhizobium leguminosarum biovar phaseoli. the three most active nod gene inducers were identified by spectroscopic methods (ultraviolet/visible absorbance, proton nuclear magnetic resonance, and mass spectrometry) as being eriodictyol (5,7,3',4' -tetrahydroxyflavanone), naringenin (5,7,4' -trihydroxyflavanone), and a 7-o-glycoside of genistein (5,7,4' -trihydro ... | 1991 | 16668463 |
| dissection of nodule development by supplementation of rhizobium leguminosarum biovar phaseoli purine auxotrophs with 4-aminoimidazole-5-carboxamide riboside. | purine auxotrophs of rhizobium leguminosarum biovar phaseoli cfn42 elicit uninfected pseudonodules on bean (phaseolus vulgaris l.). addition of 4-aminoimidazole-5-carboxamide (aica) riboside to the root medium during incubation of the plant with these mutants leads to enhanced nodule development, although nitrogenase activity is not detected. nodules elicited in this manner had infection threads and anatomical features characteristic of normal nodules, such as peripheral vasculature rather than ... | 1992 | 16668898 |
| sequence analysis of the 144-kilobase accessory plasmid psmesm11a, isolated from a dominant sinorhizobium meliloti strain identified during a long-term field release experiment. | the genome of sinorhizobium meliloti type strain rm1021 consists of three replicons: the chromosome and two megaplasmids, psyma and psymb. additionally, many indigenous s. meliloti strains possess one or more smaller plasmids, which represent the accessory genome of this species. here we describe the complete nucleotide sequence of an accessory plasmid, designated psmesm11a, that was isolated from a dominant indigenous s. meliloti subpopulation in the context of a long-term field release experim ... | 2006 | 16672515 |
| multiple groesl operons are not key targets of rpoh1 and rpoh2 in sinorhizobium meliloti. | among the rhizobia that establish nitrogen-fixing nodules on the roots of host plants, many contain multiple copies of genes encoding the sigma factor rpoh and the chaperone groel/groes. in sinorhizobium meliloti there are two rpoh genes, four groesl operons, and one groel gene. rpoh1 mutants are defective for growth at high temperature and form ineffective nodules, rpoh1 rpoh2 double mutants are unable to form nodules, and groesl1 mutants form ineffective nodules. to explore the roles of rpoh1 ... | 2006 | 16672605 |
| chemotaxis is required for virulence and competitive fitness of the bacterial wilt pathogen ralstonia solanacearum. | ralstonia solanacearum, a soilborne plant pathogen of considerable economic importance, invades host plant roots from the soil. qualitative and quantitative chemotaxis assays revealed that this bacterium is specifically attracted to diverse amino acids and organic acids, and especially to root exudates from the host plant tomato. exudates from rice, a nonhost plant, were less attractive. eight different strains from this heterogeneous species complex varied significantly in their attraction to a ... | 2006 | 16672623 |
| the rhizobium leguminosarum biovar trifolii anu794 induces novel developmental responses on the subterranean clover cultivar woogenellup. | the clover-nodulating rhizobium leguminosarum bv. trifolii anu794 initiates normal root-nodule development with abnormally low efficiency on the trifolium subterraneum cv. woogenellup. the cellular and developmental responses of woogenellup roots to the site- and dose-defined inoculation of green fluorescent protein (gfp)-labeled cells of anu843 (nodulation proficient) and anu794 was investigated using light, fluorescence, and confocal microscopy. strain anu794-gfp induced three primordia types ... | 2006 | 16673934 |