Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
the effect of heavy metals on dinitrogen fixation by rhizobium-white clover in a range of long-term sewage sludge amended and metal-contaminated soils.an investigation was conducted to determine whether effective strains of rhizobium leguminosarum biovar. trifolii capable of symbiotic n2 fixation with white clover (trifolium repens) were present in a range of metal-contaminated soils. a number of historically sewage-amended sites (including experimental, pasture grassland and arable sites) were selected and compared with highly contaminated samples from abandoned heavy metal mines. many sites had metal concentrations above the limits establish ...199315091894
nucleotide sequence analysis of four genes, hupc, hupd, hupf and hupg, downstream of the hydrogenase structural genes in bradyrhizobium japonicum.the nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in bradyrhizobium japonicum was determined. four genes encoding predicted polypeptides of 27.8 (hupc), 21.4 (hupd), 10.6 (hupf) and 15.8 (hupg) kda were identified, of which the first three probably belong to the same operon as the hup structural genes, hups and hupl. hupc is homologous to the hydrophobic polypeptides with four potential transmembrane regions that are encoded by open reading frames followin ...19938230232
proposal for rejection of agrobacterium tumefaciens and revised descriptions for the genus agrobacterium and for agrobacterium radiobacter and agrobacterium rhizogenes.the 16s rrna sequences of seven representative agrobacterium strains, eight representative rhizobium strains, and the type strains of azorhizobium caulinodans and bradyrhizobium japonicum were determined. these strains included the type strains of agrobacterium tumefaciens, agrobacterium rhizogenes, agrobacterium radiobacter, agrobacterium vitis, agrobacterium rubi, rhizobium fredii, rhizobium galegae, rhizobium huakuii, rhizobium leguminosarum, rhizobium loti, rhizobium meliloti, and rhizobium ...19938240952
genomic heterogeneity among french rhizobium strains isolated from phaseolus vulgaris l.levels of dna relatedness between strains isolated from root nodules of phaseolus vulgaris and reference strains of different rhizobium species were determined by performing dna-dna hybridization experiments (s1 nuclease method). the nine strains examined were members of three genomic groups previously delineated by a restriction fragment length polymorphism analysis among strains isolated from p. vulgaris at different sites in france. in agreement with the results of the restriction fragment le ...19938240956
identification of the sata gene encoding a streptogramin a acetyltransferase in enterococcus faecium bm4145.enterococcus faecium bm4145, a clinical isolate from urine, was resistant to streptogramin group a antibiotics by inactivation. the strain harbored a plasmid containing a gene, sata, responsible for this resistance; this gene was cloned and sequenced. it encoded sata, a protein deduced to be 23,634 da in mass and homologous with a new family of chloramphenicol acetyltransferases described in agrobacterium tumefaciens, escherichia coli, pseudomonas aeruginosa, and staphylococcus aureus. the simil ...19938257133
influence of growth conditions on production of capsular and extracellular polysaccharides by rhizobium leguminosarum.the influence of growth rate and medium composition on exopolymer production by rhizobium leguminosarum was studied. when grown in medium containing 10 g/l mannitol and 1 g/l glutamic acid, rhizobium leguminosarum biovar trifolii ta-1 synthesized up to 2.0 g/l of extracellular polysaccharide (eps), and up to 1.6 g/l of capsular polysaccharide (cps). under non-growing cell conditions in medium without glutamic acid, cps synthesis by strain ta-1 could proceed to 2.1 g/l, while eps-production remai ...19938273998
phospholipid and fatty acid compositions of rhizobium leguminosarum biovar trifolii anu843 in relation to flavone-activated psym nod gene expression.the phospholipid and associated fatty acid compositions of the bacterial symbiont of clover, rhizobium leguminosarum biovar trifolii wild-type anu843, was analyzed by two-dimensional silica thin-layer chromatography, fast atom bombardment-mass spectrometry, flame-ionization detection gas-liquid chromatography and combined gas-liquid chromatography/mass spectrometry. the phospholipid composition included phosphatidylethanolamine (15%), n-methylphosphatidylethanolamine (47%), n,n-dimethylphosphati ...19938277828
the survival of bacteria exposed to desiccation on surfaces associated with farm buildings.the survival of 11 species of gram-negative and gram-positive bacteria was examined on different surfaces exposed to desiccation. there were large variations between species; pseudomonas spp. and rhizobium leguminosarum biovars survived for less than 2 d, whilst enterococcus spp. survived for more than 11 weeks. the type of surface on to which the bacteria were deposited affected survival, but with different effects between species. in addition the survival of spontaneous nalidixic acid-resistan ...19938294304
the nodl and nodj proteins from rhizobium and bradyrhizobium strains are similar to capsular polysaccharide secretion proteins from gram-negative bacteria.the nodl and nodj nodulation proteins have been described in different rhizobium and bradyrhizobium species. the nodlj genes belong to the nod regulon. other genes from this regulon are involved in the biosynthesis and modification of lipo-oligosaccharide molecule(s) which are morphogenic signals when acting on legume roots. it has been proposed that the nodl and nodj proteins belong to a bacterial inner membrane transport system of small molecules. nucleotide sequencing of mudll pr13 insertions ...19938316086
molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in rhizobium leguminosarum biovar viciae.the nucleotide sequence (6138 bp) of a microaerobically inducible region (hupv/vi) from the rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. six genes, arranged as a single operon, were identified, and designated hypa, b, f, c, d and e based on the sequence similarities of all of them, except hypf, to genes from the hydrogenase pleiotropic operon (hyp) from escherichia coli. the gene products from hypbfcde were identified by in vivo expression analysis in e. coli, ...19938326860
methoxylated fatty acids reported in rhizobium isolates arise from chemical alterations of common fatty acids upon acid-catalyzed transesterification procedures.we obtained from a phospholipid extract of wild-type rhizobium leguminosarum bv. trifolii anu843 methoxylated fatty acids that had been previously reported as constitutive unusual rhizobium fatty acids. the use of deuterated reagents and subsequent gas-liquid chromatography-mass spectrometry analyses showed that these methoxylated fatty acid derivatives are the products of chemical alterations of common cyclopropane-containing and unsaturated fatty acids occurring during various acid-catalyzed t ...19938335647
phylogenetic grouping and identification of rhizobium isolates on the basis of random amplified polymorphic dna profiles.through the use of a single, random 15mer as a primer, between 1 and 12 dna amplification products were obtained per strain from a selection of 84 rhizobium and bradyrhizobium isolates. a principal-coordinate analysis was used to analyse the resulting amplified dna profiles and it was possible to assign isolates to specific groupings. within the species rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped t ...19938364802
sequence of the rhizobium leguminosarum biovar phaseoli syrm gene. 19938367305
cloning and sequence of the rhizobium leguminosarum biovar phaseoli fixa gene.we report the identification and cloning of rhizobium leguminosarum biovar phaseoli fixabcx homologous genes and the complete nucleotide sequence of the fixa gene. the corresponding gene product is highly homologous to the rhizobium meliloti and azorhizobium caulinodans fixa proteins. putative ntra- and nifa-binding sites are identified in the fixa promoter region.19938369342
uridylylation of the pii protein in rhizobium leguminosarum.permeabilization with cetyl trimethyl ammonium bromide was used to study the post-translational modification of the pii protein in rhizobium leguminosarum. upon incubation with radioactive utp a single band was obtained after sds-page and autoradiography. rnase resistance and snake venom phosphodiesterase sensitivity showed that radioactivity was bound through a phosphodiester bond to a protein which was absorbed by an antiserum specific for the pii protein. uridylylation of the pii protein was ...19938370467
role of the rhizobium meliloti nodf and node genes in the biosynthesis of lipo-oligosaccharidic nodulation factors.rhizobia nodulation (nod) genes are involved in the synthesis of symbiotic signals, the nod factors, which are mono-n-acylated chito-oligosaccharides. nod factors elicit, in a specific manner, various plant responses on legume roots. in this report we address the question of the role of nodfeg genes in the synthesis of the acyl moiety of rhizobium meliloti nod factors. in a nod factor-overproducing strain with the wild-type nod region, in addition to the delta 2,9-c16:2 and delta 2, 4,9-c16:3 ac ...19938376372
the ntrbc genes of rhizobium leguminosarum are part of a complex operon subject to negative regulation.we report here that ntrb and ntrc genes of rhizobium leguminosarum biovar phaseoli are cotranscribed with an open reading frame (called orf1) of unknown function. the promoter region of the orf1-ntrb-ntrc operon was mapped immediately upstream of orf1 and two in vivo transcription initiation sites were identified, both preceded by -35/-10 promoter consensus sequences. some major aspects differentiate r. leguminosarum from the enteric nitrogen regulatory system: the ntrbc genes are cotranscribed ...19938412703
polysaccharide synthesis in relation to nodulation behavior of rhizobium leguminosarum.in this study, we characterized four tn5 mutants derived from rhizobium leguminosarum rbl5515 with respect to synthesis and secretion of cellulose fibrils, extracellular polysaccharides (eps), capsular polysaccharides, and cyclic beta-(1,2)-glucans. one mutant, strain rbl5515 exo-344::tn5, synthesizes residual amounts of eps, the repeating unit of which lacks the terminal galactose molecule and the substituents attached to it. on basis of the polysaccharide production pattern of strain rbl5515 e ...19938423148
psym nod gene influence on elicitation of peroxidase activity from white clover and pea roots by rhizobia and their cell-free supernatants.the activities of salt-elutable peroxidases from roots of white clover and pea were examined during the early interaction of these legume hosts with strains of rhizobium leguminosarum in homologous and heterologous combination. peroxidase-specific activity from clover root hairs began to increase 6 hr after inoculation with r. l. bv. viciae rl300 and was localized over the entire area of their deformations. in contrast, the onset of elicitation of peroxidase activity from root hairs was delayed ...19938439669
evaluation of a strategy for identifying nodulation competitiveness genes in rhizobium leguminosarum biovar phaseoli.rhizobium leguminosarum biovar phaseoli strain kim5s is consistently much more competitive than strain ce3 in nodulation of beans (phaseolus vulgaris l.) in the laboratory and in the field. to identify genes that contribute to the competitiveness of kim5s, we transferred a cosmid library containing kim5s dna into ce3 and applied the transconjugants to bean plants to allow the plants to enrich for those with enhanced nodulation competitiveness. the nodule isolates were then applied to plants for ...19938473861
versatile suicide vectors which allow direct selection for gene replacement in gram-negative bacteria.a set of vector plasmids which greatly facilitate gene replacement and reverse genetics in many gram-negative bacteria was constructed. these vectors are based on the p15a origin of replication (ori) and incorporate sacb from bacillus subtilis, which is inducible by sucrose and is lethal when expressed in gram-negative bacteria. the vectors also have a convenient antibiotic-resistance marker (gentamicin resistance) and the lacz alpha system which allows blue/white selection of cloned fragments. ...19938486283
characterization and symbiotic importance of acidic extracellular polysaccharides of rhizobium sp. strain grh2 isolated from acacia nodules.rhizobium sp. wild-type strain grh2 was originally isolated from root nodules of the leguminous tree acacia cyanophylla and has a broad host range which includes herbaceous legumes, e.g., trifolium spp. we examined the extracellular exopolysaccharides (epss) produced by strain grh2 and found three independent glycosidic structures: a high-molecular-weight acidic heteropolysaccharide which is very similar to the acidic eps produced by rhizobium leguminosarum biovar trifolii anu843, a low-molecula ...19938491702
reclassification of american rhizobium leguminosarum biovar phaseoli type i strains as rhizobium etli sp. nov.a new rhizobium species that nodulates phaseolus vulgaris l. is proposed on the basis of a sequence analysis of 16s ribosomal dna. this taxon, rhizobium etli sp. nov., was previously named rhizobium leguminosarum biovar phaseoli (type i strains) and is characterized by the capacity to establish an effective symbiosis with bean plants, the reiteration of the nitrogenase structural genes, the organization of the common nodulation genes into two separate transcriptional units bearing noda and nodbc ...19938494746
organization of the genes necessary for hydrogenase expression in rhodobacter capsulatus. sequence analysis and identification of two hyp regulatory mutants.a 25 kbp dna fragment from the chromosome of rhodobacter capsulatus b10 carrying hydrogenase (hup) determinants was completely sequenced. coding regions corresponding to 20 open reading frames were identified. the r. capsulatus hydrogenase-specific gene (hup and hyp) products bear significant structural identity to hydrogenase gene products from escherichia coli (13), from rhizobium leguminosarum (16), from azotobacter vinelandii (10) and from alcaligenes eutrophus (11). the sequential arrangeme ...19938497190
analysis of the periplasmic [nife] hydrogenase transcription unit from desulfovibrio fructosovorans.two genes, hyna and hynb, encode the two subunits of the periplasmic [nife] hydrogenase in desulfovibrio fructosovorans. sequencing downstream from hynb revealed a third open reading frame (hync) that has the potential for encoding a polypeptide showing 21% identity with the hyad, hoxm, and hupd proteins, belonging to putative operons encoding escherichia coli hydrogenase 1, alcaligenes eutrophus h16 membrane-bound hydrogenase, and rhizobium leguminosarum uptake hydrogenase, respectively. northe ...19938501043
positive regulation of phenolic catabolism in agrobacterium tumefaciens by the pcaq gene in response to beta-carboxy-cis,cis-muconate.an escherichia coli system for generating a commercially unavailable catabolite in vivo was developed and was used to facilitate molecular genetic studies of phenolic catabolism. introduction of the plasmid-borne acinetobacter pcahg genes, encoding the 3,4-dioxygenase which acts on protocatechuate, into e. coli resulted in bioconversion of exogenously supplied protocatechuate into beta-carboxy-cis,cis-muconate. this compound has been shown to be an inducer of the protocatechuate (pca) genes requ ...19938501056
gene amplification in rhizobium: identification and in vivo cloning of discrete amplifiable dna regions (amplicons) from rhizobium leguminosarum biovar phaseoli.a genetic element that allows the positive selection of different genomic rearrangements was used to analyze dna amplification in rhizobium leguminosarum biovar phaseoli. discrete amplifiable dna regions (amplicons) were detected in different regions of the genome of the model strain cfn42, including the chromosome and several large plasmids. amplicons were mobilized into escherichia coli using a genetic approach that involves the introduction of an origin of replication active in e. coli and an ...19938506337
dna sequence and mutational analysis of genes involved in the production and resistance of the antibiotic peptide trifolitoxin.the 7.1-kb fragment of rhizobium leguminosarum bv. trifolii t24 dna which confers trifolitoxin production and resistance to nonproducing, sensitive rhizobium strains (e. w. triplett, m. j. schink, and k. l. noeldner, mol. plant-microbe interact. 2:202-208, 1989) was subcloned, sequenced, and mutagenized with a transcriptional fusion cassette. the sequence of this fragment revealed seven complete open reading frames, tfxabcdefg, all transcribed in the same direction. tfxa has an 11-amino-acid car ...19938509324
biological activity of rhizobium sp. ngr234 nod-factors on macroptilium atropurpureum.the broad host range of rhizobium sp. ngr234 is based mainly on its ability to secrete a family of lipooligosaccharide nod factors. to monitor nod-factor purification, we used the small seeded legume macroptilium atropurpureum, which responds evenly and consistently to nod factors. at concentrations between approximately equal to 10(-11) m and 10(-9) m, this response takes the form of deformation of the root hairs. higher concentrations (approximately equal to 10(-9) to 10(-7) m), provoked profo ...19938118058
resistance to nodulation of cv. afghanistan peas is overcome by nodx, which mediates an o-acetylation of the rhizobium leguminosarum lipo-oligosaccharide nodulation factor.only some strains of rhizobium leguminosarum biovar viciae can efficiently nodulate varieties of peas such as cv. afghanistan, which carry a recessive allele that blocks efficient nodulation by most western isolates of r.i. viciae. one strain (tom) which can nodulate cv. afghanistan peas has a gene (nodx) that is required to overcome the nodulation resistance. strain tom makes significantly lower amounts of lipo-oligosaccharide nodulation factors than other strains of r.i. viciae and this effect ...19937934826
a rhizobium tropici dna region carrying the amino-terminal half of a nodd gene and a nod-box-like sequence confers host-range extension.rhizobium tropici ciat899 is a broad-host-range strain that, in addition to phaseolus, nodulates other plant legumes such as leucaena and macroptilium. the narrow-host-range of rhizobium leguminosarum biovars phaseoli (strain ce3) and trifolii (strain rs1051) can be extended to leucaena esculenta and phaseolus vulgaris plants, respectively, by the introduction of a dna fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodd gene from r. tropici, as well as a pu ...19937934929
hupk, a hydrogenase-ancillary protein from rhizobium leguminosarum, shares structural motifs with the large subunit of nife hydrogenases and could be a scaffolding protein for hydrogenase metal cofactor assembly. 19937934943
homology of genes for exopolysaccharide synthesis in rhizobium leguminosarum and effect of cloned exo genes on nodule formation.a 5.4 kb bamhi fragment of r. leguminosarum bv. trifolii ta1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). this fragment was strongly hybridized to the total dna from r. l. bv. viciae and bv. phaseoli digested with ecori. no homology was found with total dna of r. meliloti and rhizobium sp. ngr 234. the exo genes from r. l. bv. trifolii ta1 conjugally introduced into r. l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abort ...19938140821
effect of nitrogen supply on frost resistance, nitrogen metabolism and carbohydrate content in white clover (trifolium repens).effects of mineral nitrogen (2, 4, 6 and 8 mm nh4 no3 ) and nodulation with rhizobium on frost hardiness in seedlings of white clover (trifolium repens) have been studied. seedlings of a population from bodø (67°n lat.) were grown in leonard jars under controlled conditions in a phytotron. for induction of frost hardening, plants were first exposed to 12 h photoperiod conditions for 2 weeks at 18°c, then for 2 weeks at 6°c and finally for 2 weeks at 0.5°c. frost hardiness after treatments at 6 a ...199328741772
phylogenetic estimation of plasmid exchange in bacteria.the existence of differential horizontal gene transfer may be assessed by comparing the phylogenetic trees derived from two different genes. we use this concept to estimate quantitatively the amount of plasmid exchange that has occurred in a bacterial population. by means of computer simulations we studied the effect of gene transfer on the topological distortion between two phylogenetic trees: one obtained from an euchromosomal gene and another from a plasmid-borne sequence, which may be subjec ...199228568654
performance of chickpea, lentil and lupin nodulated with indigenous or inoculated rhizobia micropartners under nitrogen, boron, cobalt and molybdenum fertilization schedules.chickpea (cicer arietinum), lentil (lens esculenta) and lupin (lupinus albus) responded to inoculation with their respective symbiotants:rhizobium loti, rhizobium leguminosarum biovarviceae andbradyrhizobium sp. (lupinus) alone or with (nh4)2so4 at 30 ppm n. soil application of na2moo4.2h2o at 3 ppm mo, cocl2.6h2o at 2 ppm co(2+) or na2b4o7.10h2o at 1 ppm b with 0 and 30 ppm n increased nodule weight and plant dry weight and n-content 60 days after sowing and seed yield, seed size and the n and ...199224425609
a new subfamily of bacterial abc-type transport systems catalyzing export of drugs and carbohydrates.sequence comparison studies revealed that the drug resistance transporter of streptomyces peucetius (drrab) and two nodulation gene products (nodij) of rhizobium leguminosarum are homologous to proteins encoded by three sets of genes that comprise capsular polysaccharide export systems in gram-negative bacteria: kpstm of escherichia coli, bexabc of haemophilus influenzae, and ctrdcb of neisseria meningitidis. these five systems comprise a new subfamily within the family of atp binding cassette ( ...19921303751
rhizobium leguminosarum cfn42 lipopolysaccharide antigenic changes induced by environmental conditions.four monoclonal antibodies were raised against the lipopolysaccharide of rhizobium leguminosarum bv. phaseoli cfn42 grown in tryptone and yeast extract. two of these antibodies reacted relatively weakly with the lipopolysaccharide of bacteroids of this strain isolated from bean nodules. growth ex planta of strain cfn42 at low ph, high temperature, low phosphate, or low oxygen concentration also eliminated binding of one or both of these antibodies. lipopolysaccharide mobility on gel electrophore ...19921312998
the chloramphenicol acetyltransferase gene of tn2424: a new breed of cat.we have sequenced the gene coding for the chloramphenicol acetyltransferase of tn2424 of plasmid nr79. this gene codes for a protein of 23,500 da, and the derived protein sequence is similar to those of the chromosomal chloramphenicol acetyltransferases of agrobacterium tumefaciens and pseudomonas aeruginosa and of unidentified open reading frames, which may encode chloramphenicol acetyltransferases, adjacent to the ermg macrolide-lincosamide-streptogramin resistance gene of bacillus sphaericus ...19921314803
characterization of structural defects in the lipopolysaccharides of symbiotically impaired rhizobium leguminosarum biovar viciae vf-39 mutants.the lipopolysaccharides (lps) of a wild type strain of rhizobium leguminosarum biovar viciae (strain vf-39) and two symbiotically defective tn5 mutants (vf-39-32 and vf-39-86) have been studied. the lps of the mutants reflected impaired synthesis of the o-antigen. in the lps of one mutant, the core tetrasaccharide was lacking and in that of the other it was truncated to a disaccharide containing mannose and 3-deoxy-d-manno-oct-2-ulosonic acid (kdo). the latter mutant also synthesized an unusual ...19921327527
protein iiia of rhizobium leguminosarum is probably a porin.the cloning, sequencing and expression of the gene encoding the 36-kilodalton (kda) outer membrane protein of rhizobium leguminosarum has been recently described in the literature (de maagd ra et al (1992) j bacteriol 174, 214-221). we present evidence that this protein is a porin from a sub-type covalently bound to the peptidoglycan.19921337982
dissociation by nh4cl treatment of the enzymic activities of glutamine synthetase ii from rhizobium leguminosarum biovar viceae.glutamine synthetase ii (gsii) was purified to homogeneity from rhizobium leguminosarum biovar viceae and characterized. the sequence of 26 amino acid residues from the amino-terminal end of the protein showed high similarity with the sequence of gsii from bradyrhizobium japonicum or from rhizobium meliloti. non-denaturing page showed that gsii, either in crude extracts or in the pure state, was a mixture of an octamer and a tetramer and that under specific conditions the octamer/tetramer ratio ...19921355107
the rhizobium leguminosarum biovar phaseoli glnt gene, encoding glutamine synthetase iii.plasmid pge203 contains the rhizobium leguminosarum biovar phaseoli glnt locus. glutamine synthetase iii (gsiii) was purified from a glutamine auxotrophic strain of klebsiella pneumoniae carrying this plasmid. sequencing of a 2.4-kb fragment containing the glnt locus reveals an open reading frame of 435 amino acids (aa), whose first eight aa are identical to those determined from pure gsiii by direct aa sequencing, thus confirming that glnt indeed codes for gsiii activity. the comparison of the ...19921356885
activation of the rhizobium leguminosarum glnii gene by ntrc is dependent on upstream dna sequences.the cloning and sequence determination is reported of the dna region of rhizobium leguminosarum coding for glutamine synthetase ii (gsii). an open reading frame (orf) encoding 326 amino acids was defined as the glnii gene on the basis of its similarity to other glnii genes and the ability of a dna fragment carrying this orf to complement the glutamine auxotrophy of a klebsiella pneumoniae glna mutant. we find that the glnii gene in r. leguminosarum is transcribed as a monocistronic unit from a s ...19921357539
phenotype of a rhizobium leguminosarum ntrc mutant.a tn5 insertion mutant, strain cfn2012, of rhizobium leguminosarum biovar phaseoli devoid of glutamine synthetase ii (gsii) activity was analysed. it was shown to contain tn5 within an 11-kb bamhi dna fragment, which was isolated (psm261) from the wild-type strain and, when introduced into strain cfn2012, was shown to complement the absence of gsii activity. the dna sequence of the corresponding region from the wild-type allele revealed the presence of an ntrc regulatory gene, and restriction an ...19921357726
cloning, nucleotide sequencing, and expression in escherichia coli of a rhizobium leguminosarum gene encoding a symbiotically repressed outer membrane protein.we describe the cloning of a gene from rhizobium leguminosarum biovar viciae strain 248 encoding protein iiia, the 36-kda outer membrane protein forming a part of the outer membrane protein antigen group iii. the expression of this antigen group is repressed in the bacteroid form during symbiosis (r. a. de maagd, r. de rijk, i. h. m. mulders, and b. j. j. lugtenberg, j. bacteriol. 171:1136-1142, 1989). a cosmid clone expressing the strain 248-specific mab38 epitope of this antigen group in a non ...19921370281
phylogeny of fast-growing soybean-nodulating rhizobia support synonymy of sinorhizobium and rhizobium and assignment to rhizobium fredii.we determined the sequences for a 260-base segment amplified by the polymerase chain reaction (corresponding to positions 44 to 337 in the escherichia coli 16s rrna sequence) from seven strains of fast-growing soybean-nodulating rhizobia (including the type strains of rhizobium fredii chemovar fredii, rhizobium fredii chemovar siensis, sinorhizobium fredii, and sinorhizobium xinjiangensis) and broad-host-range rhizobium sp. strain ngr 234. these sequences were compared with the corresponding pre ...19921371066
chemical characterization of ph-dependent structural epitopes of lipopolysaccharides from rhizobium leguminosarum biovar phaseoli.lipopolysaccharide (lps) was isolated from free-living rhizobium leguminosarum bv. phaseoli ce3 cells grown at ph 4.8 (antigenically similar to bacteroid lps) and compared with that from cells grown at ph 7.2 (free-living bacteria). composition analysis revealed that ph 7.2 lps differs from ph 4.8 lps in that 2,3,4-tri-o-methylfucose is replaced by 2,3-di-o-methylfucose. the amount of 2-o-methylrhamnose is greater in the ph 4.8 lps than in the ph 7.2 lps. analysis of the structural components of ...19921372601
phylogenetic position of rhizobium sp. strain or 191, a symbiont of both medicago sativa and phaseolus vulgaris, based on partial sequences of the 16s rrna and nifh genes.phenotypic and dna sequence comparisons are presented for eight rhizobium isolates that were cultured from field-grown alfalfa (medicago sativa l.) in oregon. these isolates were previously shown to nodulate both alfalfa and common bean (phaseolus vulgaris (l.) savi.). the objective of the present study was to determine their phylogenetic relationships to the normal symbionts of these plants, rhizobium meliloti and rhizobium leguminosarum biovar phaseoli, respectively. phenotypically, the oregon ...19921377901
activation of flavonoid biosynthesis in roots of vicia sativa subsp. nigra plants by inoculation with rhizobium leguminosarum biovar viciae.infective (nodulating) rhizobium leguminosarum biovar viciae (r.l. viciae) bacteria release nod factors which stimulate the release of nodulation gene-inducing flavanones and chalcones from roots of the host plant vicia sativa subsp. nigra (k. recourt et al., plant mol biol 16: 841-852; h.p. spaink et al., nature 354: 125-130). the hypothesis that this release results from increased synthesis of flavonoids was tested by studying the effect of inoculation of v. sativa with infective and uninfecti ...19921377964
molecular dissection of structure and function in the lipopolysaccharide of rhizobium leguminosarum strain 3841 using monoclonal antibodies and genetic analysis.following treatment with nitrosoguanidine, mutant derivatives of rhizobium leguminosarum strain 3841 were isolated which failed to react with afrc mac 203. this monoclonal antibody normally recognizes a strain-specific lipopolysaccharide epitope which is developmentally regulated during legume nodule differentiation. structural modification of lipopolysaccharide (lps) was analysed by examining reactivity with a range of monoclonal antibodies with different epitope specificities, and also by anal ...19921383672
siderophore and organic acid production in root nodule bacteria.nineteen strains of root nodule bacteria were grown under various iron regimes (0.1, 1.0 and 20 microm added iron) and tested for catechol and hydroxamate siderophore production and the excretion of malate and citrate. the growth response of the strains to iron differed markedly. for 12 strains (bradyrhizobium strains nc92b and 32h1, b. japonicum usda110 and cb1809, b. lupini wu8, cowpea rhizobium ngr234, rhizobium meliloti strains u45 and cc169, rhizobium leguminosarum bv viciae wu235 and rhizo ...19921387306
the nodd protein does not bind to the promoters of inducible nodulation genes in extracts of bacteroids of rhizobium leguminosarum biovar viciae.in a previous study, we showed that in bacteroids, transcription of the inducible nod genes does not occur and expression of nodd is decreased by 65% (h. r. m. schlaman, b. horvath, e. vijgenboom, r.j.h. okker, and b. j. j. lugtenberg, j. bacteriol. 173:4277-4287, 1991). in the present study, we show, using gel retardation, that in crude extracts of bacteroids of rhizobium leguminosarum biovar (bv.) viciae, nodd protein does not bind to the nodf, nodm, and nodo box and that it binds only weakly ...19921400160
synthesis of cyclic beta-(1,2)-glucans by rhizobium leguminosarum biovar trifolii ta-1: factors influencing excretion.the synthesis of cyclic beta-(1,2)-glucans from udp-[14c]glucose by a crude membrane preparation and whole cells of rhizobium leguminosarum bv. trifolii ta-1 was investigated. the crude membrane system needed mn2+, atp, and nad+ for optimal activity. hardly any difference in biosynthetic activity between membrane fractions of ta-1 cells grown in the presence (200 mm) or absence of nacl was observed. whole ta-1 cells grown in the presence of nacl excreted labeled, neutral cyclic beta-(1,2)-glucan ...19921400186
effects of flavonoids released naturally from bean (phaseolus vulgaris) on nodd-regulated gene transcription in rhizobium leguminosarum bv. phaseoli.nine flavonoid aglycones released from black bean (phaseolus vulgaris 'pi165426cs') seeds and roots induced nodc::lacz transcription in rhizobium leguminosarum bv. phaseoli strains containing extra cloned copies of the regulatory genes nodd1, nodd2, or nodd3 from that biovar. individual flavonoids generally induced highest levels of nodc::lacz transcription (imax) with extra copies of nodd2, and the concentration required for half-maximum induction (i50) was lowest with extra copies of nodd1 gen ...19921421508
exopolysaccharides of rhizobium leguminosarum biovar trifolii harbouring cloned exo region.rhizobium leguminosarum bv. trifolii produces an acidic exopolysaccharide (eps) which plays an important role in the development of nitrogen-fixing nodules. tn5 mutant of r. trifolii 93 defective in eps production (exo-) forms ineffective (fix-) nodules on red clover. this exo- mutation is complemented by the parf1368 and parf25 cosmids isolated from gene bank of rhizobium trifolii ta1, but the complementation is not correlated with restoration of fix+ phenotype. furthermore, these cosmids intro ...19921441845
rhizobium nodm and nodn genes are common nod genes: nodm encodes functions for efficiency of nod signal production and bacteroid maturation.earlier, we showed that rhizobium meliloti nodm codes for glucosamine synthase and that nodm and nodn mutants produce strongly reduced root hair deformation activity and display delayed nodulation of medicago sativa (baev et al., mol. gen. genet. 228:113-124, 1991). here, we demonstrate that nodm and nodn genes from rhizobium leguminosarum biovar viciae restore the root hair deformation activity of exudates of the corresponding r. meliloti mutant strains. partial restoration of the nodulation ph ...19921447128
mutational analysis of pea lectin. substitution of asn125 for asp in the monosaccharide-binding site eliminates mannose/glucose-binding activity.as part of a strategy to determine the precise role of pea (pisum sativum) lectin, psl, in nodulation of pea by rhizobium leguminosarum, mutations were introduced into the genetic determinant for pea lectin by site-directed mutagenesis using pcr. introduction of a specific mutation, n125d, into a central area of the sugar-binding site resulted in complete loss of binding of psl to dextran as well as of mannose/glucose-sensitive haemagglutination activity. as a control, substitution of an adjacen ...19921463840
nucleotide sequence and organization of an h2-uptake gene cluster from rhizobium leguminosarum bv. viciae containing a rubredoxin-like gene and four additional open reading frames.the nucleotide sequence of a 3.2 kb region following the hydrogenase structural operon (hupslcdef) in the h2-uptake gene cluster from rhizobium leguminosarum by viciae strain 128c53 has been determined. five closely linked genes encoding products of 16.3 (hupg), 30.5 (huph), 8.0 (hupi), 18.4 (hupj) and 38.7 (hupk) kda were identified 166 bp downstream from hupf. transposon insertions into hupg, huph, hupj and hupk suppress the h2-oxidizing capability of the wild-type strain. the amino acid seque ...19921469733
evaluation of acidic heteropolysaccharide structures in rhizobium leguminosarum biovars altered in nodulation genes and host range.1h-nmr spectroscopy showed that the extracellular heterpolysaccharides (eps) from derivatives of rhizobium leguminosarum bv. trifolii anu843 altered in psym nod composition or function (transposon insertions, deletion of psym, induction by flavone, and introduction of cloned psym nod regions from anu843 and r. l. bv. viciae 248 on recombinant plasmids into the psym-cured background of anu843) differed only in 3-hydroxybutyrate stoichiometry per octaglycosyl unit. this change in eps was likely to ...19921477403
characterisation of rhizobium isolates by amplification of dna polymorphisms using random primers.the use of single random primers, selected in the absence of target sequence information, has been shown to be effective in producing dna amplifications that provide fingerprints which are unique to individual organisms. dna amplification by random priming was applied to the dna from isolates of rhizobium leguminosarum biovar trifolii. amplification products were produced using a number of primers, and the resulting fingerprints allowed strain differentiation. however, the effectiveness of prime ...19921477784
the rhizobium leguminosarum fnrn protein is functionally similar to escherichia coli fnr and promotes heterologous oxygen-dependent activation of transcription.an open reading frame from rhizobium leguminosarum bv. viciae strain vf39, previously identified and found to be similar to escherichia coli fnr and rhizobium meliloti fixk (orf240, thereafter called fnrn), was further analysed. analysis of the expression of an fnrn-lacz transcriptional fusion revealed that fnrn is preferentially expressed under oxygen limitation. using r. meliloti fixn-lacz fusions it was shown that the fnrn gene product only mediates transcriptional activation under microaerob ...19921484491
slow rehydration improves the recovery of dried bacterial populations.slow rehydration of bacteria from dried inoculant formulations provided higher viable counts than did rapid rehydration. estimates were higher when clay and peat powder formulations of rhizobium meliloti, rhizobium leguminosarum biovar trifolii, and pseudomonas putida, with water activities between 0.280 and 0.650, were slowly rehydrated to water activities of approximately 0.992 before continuing the dilution plating sequence. rhizobium meliloti populations averaged 6.8 x 10(8) cfu/g and 1328 c ...19921504917
construction of a cassette enabling regulated gene expression in the presence of aromatic hydrocarbons.a high-level expression cassette has been constructed from a tol plasmid derived from pseudomonas putida carrying all cis- and trans-acting regulatory elements necessary for transcriptional gene activation in the presence of aromatic hydrocarbons such as toluene. foreign dna can be inserted at unique kpni, saci, and ecori sites 7, 13, and 15 nucleotides downstream of a ribosome binding site. the cassette, flanked by bamhi and ecori restriction sites, was inserted into a broad-host-range vector a ...19921513877
hierarchical analysis of linkage disequilibrium in rhizobium populations: evidence for sex?many bacterial species exhibit strong linkage disequilibrium of their chromosomal genes, which apparently indicates restricted recombination between alleles at different loci. the extent to which restricted recombination reflects limited migration between geographically isolated populations versus infrequent mixis of genotypes within populations is more difficult to determine. we examined the genetic structure of rhizobium leguminosarum biovar phaseoli populations associated with wild and cultiv ...19921518873
characterization of an aromatic amino acid aminotransferase from rhizobium leguminosarum biovar trifolii.the most abundant aromatic amino acid aminotransferase of rhizobium leguminosarum biovar trifolii was partially purified. the molecular mass of the enzyme was estimated to be 53 kda by gel filtration. the enzyme transaminated aromatic amino acids and histidine. it used aromatic keto acids and alpha-ketoglutaric and oxalacetic acids as amino-group acceptors. the optimum temperature was 35 degrees c. using phenylalanine and alpha-ketoglutaric acid as substrates the activation energy was 46.2 kj.mo ...19921520732
competition among rhizobium leguminosarum bv. phaseoli strains for nodulation of common bean.six effective rhizobium leguminosarum bv. phaseoli strains were examined for nodulation competitiveness on common bean (phaseolus vulgaris l.), using all possible two-strain combinations of inoculum. nodule occupancy was determined with strain-specific fluorescent antibodies. the strains were divided into three groups according to their overall competitive abilities on pole bean cv. kentucky wonder and bush bean cv. bountiful. strains tal 182 and tal 1472 were highly competitive (greater than 70 ...19921521190
major flavonoids in uninoculated and inoculated roots of vicia sativa subsp. nigra are four conjugates of the nodulation gene-inhibitor kaempferol.inoculation of vicia sativa subsp. nigra (v. sativa) roots with rhizobium leguminosarum biovar. viciae (r.l. viciae) bacteria substantially increases the ability of v. sativa to induce rhizobial nodulation (nod) genes. this increase is caused by the additional release of flavanones and chalcones which all induce the nod genes of r.l. viciae (k. recourt et al., plant mol biol 16: 841-852). in this paper, we describe the analyses of the flavonoids present in roots of v. sativa. independent of inoc ...19921536926
characterization of salt-tolerant and salt-sensitive mutants of rhizobium leguminosarum biovar viciae strain c1204b.spontaneous mutants of rhizobium leguminosarum biovar viciae strain c1204b were selected for their ability to tolerate 0.2 m nacl, a growth-inhibiting level of salt for the parental strain. transposon-mediated salt-sensitive mutants of strain c1204b were screened for their inability to grow in 0.08 m nacl. quantitation of the free-amino acid pools in the mutants grown in nacl revealed a dramatic increase in glutamine, serine, glutamate and proline, and to a lesser extent alanine and glycine in t ...19921537541
secretion of the rhizobium leguminosarum nodulation protein nodo by haemolysin-type systems.the rhizobium leguminosarum biovar viciae nodulation protein nodo is partially homologous to haemolysin of escherichia coli and, like haemolysin, is secreted into the growth medium. the nodo protein can be secreted by a strain of e. coli carrying the cloned nodo gene plus the haemolysin secretion genes hlybd, in a process that also requires the outer membrane protein encoded by tolc. the related protease secretion genes, prtdef, from erwinia chrysanthemi also enable e. coli to secrete nodo. the ...19921545707
molecular characterization and regulation of the rhizosphere-expressed genes rhiabcr that can influence nodulation by rhizobium leguminosarum biovar viciae.a group of four rhi (rhizosphere-expressed) genes from the symbiotic plasmid of rhizobium leguminosarum biovar viciae has been characterized. although mutation of the rhi genes does not normally affect nodulation, in the absence of the closely linked nodulation genes nodfel, mutations in the rhi genes can influence the nodulation of the vetch vicia hirsuta. the dna sequence of the rhi gene region reveals four large open reading frames, three of them constituting an operon (rhiabc) transcribed co ...19921597418
nucleotide sequence and characterization of four additional genes of the hydrogenase structural operon from rhizobium leguminosarum bv. viciae.the nucleotide sequence of a 2.5-kbp region following the hydrogenase structural genes (hupsl) in the h2 uptake gene cluster from rhizobium leguminosarum bv. viciae upm791 was determined. four closely linked genes encoding peptides of 27.9 (hupc), 22.1 (hupd), 19.0 (hupe), and 10.4 (hupf) kda were identified immediately downstream of hupl. proteins with comparable apparent molecular weights were detected by heterologous expression of these genes in escherichia coli. the six genes, hups to hupf, ...19921597428
rhizobium leguminosarum has two glucosamine synthases, glms and nodm, required for nodulation and development of nitrogen-fixing nodules.the rhizobium leguminosarum nodm gene product shows strong homology to the escherichia coli glms gene product that catalyses the formation of glucosamine 6-p from fructose 6-p and glutamine. dna hybridization with nodm indicated that, in addition to nodm on the symbiotic plasmid, another homologous gene was present elsewhere in the r. leguminosarum genome. a glucosamine-requiring mutant was isolated and its auxotrophy could be corrected by two different genetic loci. it could grow without glucos ...19921602964
identification of a nodd-like gene in frankia by direct complementation of a rhizobium nodd-mutant.clones from a frankia at4 gene bank were pooled into groups and mass conjugated into a nodd mutant of rhizobium leguminosarum bv. viciae by triparental matings. when peas were inoculated with the pooled transconjugants, nodulation was observed. a plasmid, pat2gx containing frankia dna, was isolated from bacteria recovered from these nodules. this plasmid was shown to complement a nodd mutant of r. leguminosarum bv. viciae. thus pat2gx contains a frankia gene that is functionally equivalent to no ...19921603071
influence of metribuzin on the rhizobium leguminosarum--lentil (lens culinaris) symbiosis.the effects of the triazine herbicide metribuzin (sencor) on the lentil (lens culinaris medic.) - rhizobium leguminosarum biovar viciae symbiosis were studied in leonard jars and growth pouches. lentils inoculated with rhizobium leguminosarum strain 128c54 or 128c84, and noninoculated lentils grown in plant nutrient solution supplemented with 5 mm kno3, had metribuzin applied to the plants at either 8 or 13 days after planting. when sprayed at 8 days, metribuzin had a significant (p less than or ...19921611561
cell-associated pectinolytic and cellulolytic enzymes in rhizobium leguminosarum biovar trifolii.the involvement of rhizobium enzymes that degrade plant cell wall polymers has long been an unresolved question about the infection process in root nodule symbiosis. here we report the production of enzymes from rhizobium leguminosarum bv. trifolii that degrade carboxymethyl cellulose and polypectate model substrates with sensitive methods that reliably detect the enzyme activities: a double-layer plate assay, quantitation of reducing sugars with a bicinchoninate reagent, and activity gel electr ...19921622257
hyperreiterated dna regions are conserved among bradyrhizobium japonicum serocluster 123 strains.we have identified and cloned two dna regions which are highly reiterated in bradyrhizobium japonicum serocluster 123 strains. while one of the reiterated dna regions, pfr2503, is closely linked to the b. japonicum common and genotype-specific nodulation genes in strain usda 424, the other, pmap9, is located next to a tn5 insertion site in a host-range extension mutant of b. japonicum usda 438. the dna cloned in pfr2503 and pmap9 are reiterated 18 to 21 times, respectively, in the genomes of b. ...19921622264
structure of the acidic exopolysaccharide secreted by rhizobium leguminosarum biovar. phaseoli cfn42. 19921633602
combined subtraction hybridization and polymerase chain reaction amplification procedure for isolation of strain-specific rhizobium dna sequences.a novel subtraction hybridization procedure, incorporating a combination of four separation strategies, was developed to isolate unique dna sequences from a strain of rhizobium leguminosarum bv. trifolii. sau3a-digested dna from this strain, i.e., the probe strain, was ligated to a linker and hybridized in solution with an excess of pooled subtracter dna from seven other strains of the same biovar which had been restricted, ligated to a different, biotinylated, subtracter-specific linker, and am ...19921637166
different plasmids of rhizobium leguminosarum bv. phaseoli are required for optimal symbiotic performance.rhizobium leguminosarum bv. phaseoli cfn42 contains six plasmids (pa to pf), and pd has been shown to be the symbiotic plasmid. to determine the participation of the other plasmids in cellular functions, we used a positive selection scheme to isolate derivatives cured of each plasmid. these were obtained for all except one (pe), of which only deleted derivatives were recovered. in regard to symbiosis, we found that in addition to pd, pb is also indispensable for nodulation, partly owing to the p ...19921644746
the central domain of rhizobium leguminosarum dctd functions independently to activate transcription.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.19921735730
genetic analysis of rhizobium leguminosarum bv. phaseoli mutants defective in nodulation and nodulation suppression.nodulation-defective rhizobia and their nodule-forming derivatives containing cloned dna from the wild type were used to study nodulation suppression in phaseolus vulgaris l. non-nitrogen-fixing derivatives which formed rhizobia-containing white nodules induced partial suppression. comparison of this with the complete suppression by fix derivatives and a fix mutant which formed rhizobia-containing pink nodules suggests that the extent of suppression may be related to successive stages of nodule ...199216348664
extracellular polysaccharide is not responsible for aluminum tolerance of rhizobium leguminosarum bv. phaseoli ciat899.strain uhm-5, a psym exo derivative of the aluminum-tolerant rhizobium leguminosarum bv. phaseoli strain ciat899, was equally tolerant of aluminum (al) as the parental culture. dialyzed culture supernatants of the wild-type cells grown in yem broth (10 cells ml) contained 185 mug of glucose equivalents ml whereas uhm-5 culture supernatants yielded 2 mug of glucose ml. the exo derivative and the parental strain gave essentially similar growth in medium containing from 0 to 300 mum al, indicating ...199216348680
utilization of carbon substrates, electrophoretic enzyme patterns, and symbiotic performance of plasmid-cured clover rhizobia.plasmids in rhizobium spp. are relatively large, numerous, and difficult to cure. except for the symbiotic plasmid, little is known about their functions. the primary objective of our investigation was to obtain plasmid-cured derivatives of rhizobium leguminosarum bv. trifolii by using a direct selection system and to determine changes in the phenotype of the cured strains. three strains of rhizobia were utilized that contained three, four, and five plasmids. phenotypic effects observed after cu ...199216348739
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( ...199216653034
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 ...199216668898
induction of pre-infection thread structures in the leguminous host plant by mitogenic lipo-oligosaccharides of rhizobium.root nodules of leguminous plants are symbiotic organs in which rhizobium bacteria fix nitrogen. their formation requires the induction of a nodule meristem and the formation of a tubular structure, the infection thread, through which the rhizobia reach the nodule primordium. in the rhizobium host plants pea and vetch, pre-infection thread structures always preceded the formation of infection threads. these structures consisted of cytoplasmic bridges traversing the central vacuole of outer corti ...199217800714
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 ...199116668462
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 ...199116668463
population dynamics of rhizobium leguminosarum tn5 mutants with altered cell surface properties introduced into sterile and nonsterile soils.the influence of cell surface properties on attachment to soil particles and on population dynamics of introduced bacteria was studied in sterilized and nonsterilized loamy sand and silt loam. rhizobium leguminosarum rbl5523 and three tn5 mutants (rbl5762, rbl5810, and rbl5811) with altered cell surface properties were used. cellulose fibrils were not produced by rbl5762. both rbl5810 and rbl5811 produced 80 to 90% less soluble exopolysaccharides and rbl5811 had, in addition, an altered lipopoly ...199116348432
procedure for obtaining efficient root nodulation of a pea cultivar by a desired rhizobium strain and preempting nodulation by other strains.the specificity between the sym-2 gene bred into certain cultivars of pea (pisum sativum l.) and the nodx gene, present only rarely in isolates of rhizobium leguminosarum, can be exploited to preempt competition or nodulation blocking by a rhizobium strain indigenous to a soil environment. the principle is to isolate an r. leguminosarum strain prevalent in a locale, convert it into a strain that will nodulate a desirable pea cultivar carrying sym-2 by establishing nodx in it, and then use the re ...199116348502
degradation of the herbicide glyphosate by members of the family rhizobiaceae.several strains of the family rhizobiaceae were tested for their ability to degrade the phosphonate herbicide glyphosate (isopropylamine salt of n-phosphonomethylglycine). all organisms tested (seven rhizobium meliloti strains, rhizobium leguminosarum, rhizobium galega, rhizobium trifolii, agrobacterium rhizogenes, and agrobacterium tumefaciens) were able to grow on glyphosate as the sole source of phosphorus in the presence of the aromatic amino acids, although growth on glyphosate was not as f ...199116348512
construction of an acid-tolerant rhizobium leguminosarum biovar trifolii strain with enhanced capacity for nitrogen fixation.strain anu1173 is an acid-tolerant rhizobium leguminosarum biovar trifolii strain that is able to nodulate subterranean clover plants growing in agar culture at ph 4.4 at ph 6.5, its symbiotic effectiveness in association with trifolium subterraneum cv. mt. barker was 80% relative to that of strain anu794, a sm derivative of the commercial inoculant r. leguminosarum bv. trifolii ta1. strain anu1173 contained four indigenous megaplasmids, the smallest of these being the symbiotic (sym) plasmid. t ...199116348523
transfer of the pea symbiotic plasmid pjb5ji in nonsterile soil.transfer of the pea (pisum sativum l.) symbiotic plasmid pjb5ji between strains of rhizobia was examined in sterile and nonsterile silt loam soil. sinorhizobium fredii usda 201 and hh003 were used as plasmid donors, and symbiotic plasmid-cured rhizobium leguminosarum 6015 was used as the recipient. the plasmid was carried but not expressed in s. fredii strains, whereas transfer of the plasmid to r. leguminosarum 6015 rendered the recipient capable of nodulating pea plants. confirmation of plasmi ...199116348589
genetic diversity among rhizobium leguminosarum bv. trifolii strains revealed by allozyme and restriction fragment length polymorphism analyses.allozyme electrophoresis and restriction fragment length polymorphism (rflp) analyses were used to examine the genetic diversity of a collection of 18 rhizobium leguminosarum bv. trifolii, 1 r. leguminosarum bv. viciae, and 2 r. meliloti strains. allozyme analysis at 28 loci revealed 16 electrophoretic types. the mean genetic distance between electrophoretic types of r. leguminosarum and r. meliloti was 0.83. within r. leguminosarum, the single strain of bv. viciae differed at an average of 0.65 ...199116348600
autoregulatory response of phaseolus vulgaris l. to symbiotic mutants of rhizobium leguminosarum bv. phaseoli.in rhizobium-legume symbiosis, the plant host controls and optimizes the nodulation process by autoregulation. tn5 mutants of rhizobium leguminosarum bv. phaseoli tal 182 which are impaired at various stages of symbiotic development, were used to examine autoregulation in the common bean (phaseolus vulgaris l.). class i mutants were nonnodulating, class ii mutants induced small, distinct swellings on the roots, and a class iii mutant formed pink, bacterium-containing, but ineffective nodules. a ...19911768143
identification of a nifa-like regulatory gene of azospirillum brasilense sp7 expressed under conditions of nitrogen fixation and in the presence of air and ammonia.a gene bank of azospirillum lipoferum br17 constructed in the vector lambda gem11 was screened with a bradyrhizobium japonicum nifa gene probe. a 7.3 kb ecori fragment carrying a nifa-like gene was thereby isolated and subsequently used to screen a gene bank of azospirillum brasilense sp7 constructed in puc18. two ecori fragments of 5.6 kb and 3.6 kb covering the nifa-homology region were found. mutants with nif- phenotype were obtained by site-directed tn5 mutagenesis of the 5.6 kb fragment and ...19911779763
the rhizobium meliloti exozl exob fragment of megaplasmid 2: exob functions as a udp-glucose 4-epimerase and exoz shows homology to nodx of rhizobium leguminosarum biovar viciae strain tom.a 2.6 kb clai-bamhi dna fragment of megaplasmid 2 of rhizobium meliloti 2011 was found to carry genes involved in exopolysaccharide synthesis and infection of alfalfa nodules. the analysis of the nucleotide sequence of this dna fragment revealed the existence of two open reading frames (orfs) running in opposite directions. plasmid integration mutagenesis showed that these orfs are organized as two monocistronic transcription units. one of the orfs represents a new exo gene designated exoz, whic ...19911787800
unusual structure of the exopolysaccharide of rhizobium leguminosarum bv. viciae strain 248.the exopolysaccharide from r. leguminosarum bv. viciae strain 248 differs from those of other rhizobium strains with similar symbiotic behavior. 13c-n.m.r. spectroscopy of fragments generated by partial hydrolysis, together with methylation analysis and 13c-n.m.r. spectroscopy of the enzymically depolymerised exopolysaccharide, indicated the following nonasaccharide repeating-unit: [formula: see text] the locations of the acetyl and 3-hydroxybutanoyl substituents in the exopolysaccharide are ass ...19911802384
identification of 3-deoxy-lyxo-2-heptulosaric acid in the core region of lipopolysaccharides from rhizobiaceae.a 3-deoxy-2-heptulosaric acid (dha), very probably with the lyxo-configuration, was identified in the r-core region of lipopolysaccharides from nodulating strains of rhizobium leguminosarum, rhizobium meliloti and from all three biovars of the phytopathogenic agrobacterium tumefaciens. its structure could be deduced from the fragmentation pattern of the corresponding alditol acetates obtained after reduction of the 2-keto and the 1.7-carboxy groups by sodium borohydride or sodium borodeuteride. ...19911804765
Refresh
firstprev
...21222324252627282930
nextlast
Displaying items 2501 - 2600 of 2995