Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| transfer and expression of lithoautotrophy and denitrification in a host lacking these metabolic activities. | the conjugative 450-kilobase-pair megaplasmid phg1 from alcaligenes eutrophus h16 was transferred to the herbicide-degrading soil bacterium a. eutrophus jmp134. this transfer was achieved by means of rp4 mobilization and a tn5-mob insertion provided in trans on the megaplasmid replicon. although kanamycin-resistant transconjugants also occurred with other gram-negative species such as rhizobium, agrobacterium, and thiobacteria, a. eutrophus jmp134 was the only recipient which stably maintained t ... | 1988 | 16347808 |
| role of motility and chemotaxis in efficiency of nodulation by rhizobium meliloti. | spontaneous mutants of rhizobium meliloti l5-30 defective in motility or chemotaxis were isolated and compared against the parent with respect to symbiotic competence. each of the mutants was able to generate normal nodules on the host plant alfalfa (medicago sativa), but had slightly delayed nodule formation, diminished nodulation in the initially susceptible region of the host root, and relatively low representation in nodules following co-inoculation with equal numbers of the parent. when ino ... | 1988 | 16666059 |
| the glycine-glomus-rhizobium symbiosis : vii. photosynthetic nutrient-use efficiency in nodulated, mycorrhizal soybeans. | four consecutive trifoliate leaves of 56-day-old symbiotic or nonsymbiotic soybean plants were evaluated individually for co(2) exchange rates (cer), leaf area and dry weight, and leaf n, p, and starch concentrations. plants had been inoculated with the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae and rhizobium japonicum, with either of the endophytes alone, or with neither at time of planting. plants lacking one or both endophytes received n and/or p fertilizers to produce plant ... | 1988 | 16666069 |
| 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 |
| nodulin gene expression in effective alfalfa nodules and in nodules arrested at three different stages of development. | nodulin gene expression was analyzed in effective and ineffective root nodules of alfalfa (medicago sativa l. cv iroquois) elicited by three different rhizobium meliloti mutants: an exob mutant having defective acidic exopolysaccharide that does not fluoresce on plates containing the fluorescent brightener calcofluor; fix21, a spontaneous mutant that has defective lipopolysaccharide and is calcofluor bright; and a rhizobium mutant resulting from a tn5 insertion in the nifh gene of the nif operon ... | 1988 | 16666302 |
| alfalfa root exudates and compounds which promote or inhibit induction of rhizobium meliloti nodulation genes. | using a plate induction assay, we demonstrate that alfalfa exudes inducer of rhizobium meliloti nodulation genes. the inducer is exuded from the infectible zone of the root, accumulates to at least 1 micromolar, and is not affected by 10 millimolar nitrate. no zones of inhibition are observed. a nodulation minus mutant line of alfalfa, mn-1008, exudes normal levels of inducer. r. meliloti grown in rich medium requires ten-fold higher concentrations of luteolin to achieve half-maximal induction a ... | 1988 | 16666315 |
| expression and functional analysis of the rhizobium meliloti nifa gene. | the translational initiation point for rhizobium meliloti nifa, the specific activator for nitrogen fixation (nif) genes, was determined. when expressed in an escherichia coli linked transcriptional-translational system the dna coding for the r.meliloti nifa gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. there are three in-frame atg codons at the n-terminus of the gene; by replacing the poor ribosome binding sites of the native dna with a synthetic consensus r ... | 1988 | 16453824 |
| transmembrane orientation and receptor-like structure of the rhizobium meliloti common nodulation protein nodc. | the 46.8-kd nodc protein of rhizobium meliloti is a membrane protein, essential for nodule formation. gene fusions of nodc to a portion of the lambda ci repressor gene were used to define the membrane-anchor domain which is necessary for membrane insertion of the nodc protein into the membrane. the transmembrane orientation of nodc was confirmed by surface-specific radiolabeling and proteolysis experiments. a highly hydrophobic transmembrane-anchor domain was found near the carboxyl terminus, se ... | 1988 | 16453829 |
| single genes from agrobacterium rhizogenes influence plant development. | the combined expression of the rol a, b, and c loci of agrobacterium rhizogenes ri-plasmids establishes, in transgenic tobacco plants, a pathological state called hairy-root syndrome. however, when expressed separately they provoke distinct developmental abnormalities characteristic for each rol gene. moreover, changes in their mode of expression obtained by replacing the promoters of the rol b and c genes with the cauliflower mosaic virus 35s promoter elicit new and distinct developmental patte ... | 1988 | 15977331 |
| stress inducing factors of strains of rhizobium phaseoli as related to inoculant-carrier preparations. | 1988 | 14543439 | |
| positive and negative control of nod gene expression in rhizobium meliloti is required for optimal nodulation. | we show that expression of common nodulation genes in rhizobium meliloti is under positive as well as negative control. a repressor protein was found to be involved in the negative control of nod gene expression. whereas the activator nodd protein binds to the conserved cis-regulatory element (nod-box) required for coordinated regulation of nod genes, the repressor binds to the overlapping nodd1 and noda promoters, at the rna polymerase binding site. a model depicting the possible interaction of ... | 1989 | 16453883 |
| interference by phosphatases in the spectrophotometric assay for phosphoenolpyruvate carboxylase. | the aim of this work was to discover the extent of interference by phosphoenolpyruvate (pep) phosphatase in spectrophotometric assays of pep carboxylase (ec 4.1.1.31) in crude extracts of plant organs. the presence of pep phosphatase and lactate dehydrogenase (ec 1.1.1.27) in extracts leads to pep-dependent nadh oxidation that is independent of pep carboxylase activity, and hence to overestimation of pep carboxylase activity. in extracts of three organs of pea (pisum sativum l.: leaves, developi ... | 1989 | 16666652 |
| isoenzymes of superoxide dismutase in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp. | the activity and isozymic composition of superoxide dismutase (sod; ec 1.15.1.1) were determined in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp. formed by rhizobium phaseoll 3622, r. ieguminosarum 3855, and bradyrhizobium sp. br7301, respectively. a mn-sod was present in rhizobium and two in bradyrhizobium and bacteroids. nodule mitochondria from all three legume species had a single mn-sod with similar relative mobility, whereas the cytosol contained seve ... | 1989 | 16666924 |
| nodule formation is stimulated by the ethylene inhibitor aminoethoxyvinylglycine. | previous researchers found that formation and function of nitrogen-fixing nodules on legume roots were severely inhibited by addition of exogenous ethylene. nodule formation by rhizobium meliloti on medicago sativa was stimulated twofold when the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (avg) was added with the inoculum. stimulation of nodule formation by avg showed a similar concentration dependence as inhibition of ethylene biosynthesis, suggesting that the primary action of avg ... | 1989 | 16667088 |
| 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 |
| interactions among flavonoid nod gene inducers released from alfalfa seeds and roots. | alfalfa (medicago sativa l.) seeds and roots can create complex rhizosphere effects by releasing flavonoids that induce nodulation (nod) genes in rhizobium meliloti. previous reports identified luteolin and 4,4'-dihydroxy-2'-methoxychalcone as strong inducers that are released from seeds and roots, respectively, and 4',7-dihydroxyflavone and 4',7-dihydroxyflavanone as weaker inducers which are exuded by roots. as a first step toward identifying flavonoid interactions that may occur in the rhizos ... | 1989 | 16667124 |
| a chalcone and two related flavonoids released from alfalfa roots induce nod genes of rhizobium meliloti. | flavonoid signals from alfalfa (medicago sativa l.) induce transcription of nodulation (nod) genes in rhizobium meliloti. previous investigations identified the flavone luteolin as an active inducer in alfalfa seed extracts, but the nature of nod inducers released from roots has not been reported. root exudate from 3-day-old alfalfa seedlings was purified and then assayed for biological activity with a nodabc-lacz fusion in r. meliloti. indentities of major nod inducers were established by spect ... | 1989 | 16667146 |
| diversity within serogroups of rhizobium leguminosarum biovar viceae in the palouse region of eastern washington as indicated by plasmid profiles, intrinsic antibiotic resistance, and topography. | serology, plasmid profiles, and intrinsic antibiotic resistance (iar) were determined for 192 isolates of rhizobium leguminosarum biovar viceae from nodules of peas (pisum sativum l.) grown on the south slope and bottomland topographic positions in eastern washington state. a total of 3 serogroups and 18 plasmid profile groups were identified. nearly all isolates within each plasmid profile group were specific for one of the three serogroups. cluster analysis of iar data showed that individual c ... | 1989 | 16347814 |
| rhizobium strain identification and quantification in commercial inoculants by immunoblot analysis. | an immunoblot procedure for the strain-specific quantitative analysis of commercial rhizobium inoculants was developed. the technique greatly reduced the time required for inoculant analysis. correlation between immunoblot analysis and traditional plant nodule grow-out most-probable-number techniques was r = 0.90 for 16 commercial alfalfa inoculants tested. | 1989 | 16347860 |
| use of the chrome azurol s agar plate technique to differentiate strains and field isolates of rhizobium leguminosarum biovar trifolii. | identification of rhizobium and bradyrhizobium strains and especially of indigenous isolates continues to be one of the major difficulties associated with competition studies. because there is no universally accepted method, the method of choice depends on preference, experience, and equipment. here, an agar plate technique was used to distinguish strains and field isolates of rhizobium leguminosarum biovar trifolii to provide a basis for identifying nodule occupants in further competition studi ... | 1989 | 16347877 |
| relationship of the presence and copy number of plasmids to exopolysaccharide production and symbiotic effectiveness in rhizobium fredii usda 206. | rhizobium fredii usda 206 harbors four large plasmids, one of which carries nodulation and nitrogen fixation genes. previously isolated groups of plasmid-cured derivatives of strain usda 206 were compared with each other to determine possible plasmid functions. mutant strain 206cans was isolated as a nonmucoid (muc) derivative of strain 206ca, a mutant that was cured of two plasmids. the muc phenotype of 206cans was only expressed when the strain was grown on certain media, particularly those wi ... | 1989 | 16347890 |
| improvement of rhizobium inoculants. | a practical approach was used to develop a rhizobium (bradyrhizobium) japonicum inoculant that increases soybean (glycine max (l.) merr.) yield in fields with indigenous rhizobium populations, which typically outcompete strains present in existing commercial inoculants and therefore decrease the value of inoculant use. field tests managed by several universities in the mississippi delta region averaged a 169-kg/ha (p < 0.01) grain yield increase. the inoculant contains a mixture of mutants selec ... | 1989 | 16347891 |
| population size and distribution of rhizobium leguminosarum bv. trifolii in relation to total soil bacteria and soil depth. | bacterial cells small enough to pass through 0.4-mum-pore-size filters made up 5 to 9% of the indigenous bacterial population in 0- to 20-cm-depth samples of abiqua silty clay loam. within the same soil samples, cells of a similar dimension were stained with fluorescent antibodies specific to each of four antigenically distinct indigenous serogroups of rhizobium leguminosarum bv. trifolii and made up 22 to 34% of the soil population of the four serogroups. despite the extensive contribution of s ... | 1989 | 16347896 |
| expression by soil bacteria of nodulation genes from rhizobium leguminosarum biovar trifolii. | gram-negative, rod-shaped bacteria from the soil of white clover-ryegrass pastures were screened for their ability to nodulate white clover (trifolium repens) cultivar grasslands huia and for dna homology with genomic dna from rhizobium leguminosarum biovar trifolii icmp2668 (nzp582). of these strains, 3.2% were able to hybridize with strain icmp2668 and nodulate white clover and approximately 19% hybridized but were unable to nodulate. strains which nodulated but did not hybridize with strain i ... | 1989 | 16347936 |
| competition among strains of rhizobium leguminosarum biovar trifolii and use of a diallel analysis in assessing competition. | competition between indigenous rhizobium leguminosarum biovar trifolii strains and inoculant strains or between mixtures of inoculant strains was assessed in field and growth-room studies. strain effectiveness under competition was compared with strain performance in the absence of competition. field inoculation trials were conducted at elora, ontario, canada, with soil containing indigenous r. leguminosarum biovar trifolii. the indirect fluorescent-antibody technique was used for the identifica ... | 1989 | 16347952 |
| exopolysaccharide-deficient mutants of rhizobium fredii hh303 which are symbiotically effective. | nineteen tn5-induced mutants of rhizobium fredii hh303 defective in acidic exopolysaccharide synthesis were isolated by screening for lack of calcofluor fluorescence. they were grouped by complementation analysis by using rhizobium meliloti cosmids carrying exo genes. all of the 19 mutants were symbiotically effective or partially effective, indicating that the major bacterial acidic exopolysaccharide of this strain of r. fredii may not be required for symbiotic development in the soybean. | 1989 | 16347980 |
| improvement of rhizobium inoculants. | [this corrects the article on p. 865 in vol. 55.]. | 1989 | 16347981 |
| maintenance of intracellular ph and acid tolerance in rhizobium meliloti. | the development and function of the rhizobium meliloti-medicago sp. symbiosis are sensitive to soil acidity. physiological criteria that can be measured in culture which serve to predict acid tolerance in soil would be valuable. the intracellular ph of r. meliloti was measured using either radioactively labeled weak acids (5,5-dimethyloxazolidine-2,4-dione and butyric acid) or ph-sensitive fluorescent compounds; both methods gave similar values. six acid-tolerant strains (wsm419, wsm533, wsm539, ... | 1989 | 16347984 |
| localization of bacteria and hemoglobin in root nodules of parasponia andersonii containing both bradyrhizobium strains and rhizobium leguminosarum biovar trifolii. | dual occupancy of parasponia andersonii nodules with different bradyrhizobium strains and rhizobium leguminosarum biovar trifolii was frequently obtained when two strains were inoculated into plants grown aseptically in tubes. since reisolates of bradyrhizobium strains from dually occupied nodules acquired the ability to nodulate trifolium repens, the spatial relationship of the two species of bacteria during nodule initiation and development was investigated and their proximity was demonstrated ... | 1989 | 16347995 |
| cadmium resistance screening in nitrilotriacetate-buffered minimal media. | media used to determine the mics of heavy metals for bacteria are unreliable because organic components in the media bind or chelate most of the metal being studied. to define specific metal activity in media and to maintain metal activity at a constant level, hepes-mes [n-2-hydroxyethylpiperazine-n' -2-ethanesulfonic acid-2-(n-morpholine)ethanesulfonic acid] salts medium with arabinose medium was modified, and the modified medium was used to examine the mic of cadmium for rhizobium fredii usda ... | 1989 | 16348000 |
| growth and nodulation responses of rhizobium meliloti to water stress induced by permeating and nonpermeating solutes. | isolates of rhizobium meliloti, representing antigenically distinct indigenous serogroups 31 and 17, were grown in yeast extract-mannitol broth (yem) containing nacl or polyethylene glycol (peg) to provide external water potentials ranging from -0.15 to -1.5 mpa. several differences were found between representatives of the two groups in their abilities to adapt to water stress induced by the nonpermeating solute peg. at potentials below -0.5 mpa, strain 31 had a lower specific growth rate than ... | 1989 | 16348021 |
| host restriction and transduction in rhizobium meliloti. | a host restriction difference exists between rhizobium meliloti rm41 and su47 exists as indicated by the reduce plating efficiency of transducing phage phim12h1. restriction can be attenuated by incubating cells at 42 degrees c for 3 h; this procedure overcomes a block to transduction from su47 to rm41. | 1989 | 16348079 |
| molecular genetics of rhizobium meliloti symbiotic nitrogen fixation. | the application of recombinant dna techniques to the study of symbiotic nitrogen fixation has yielded a growing list of rhizobium meliloti genes involved in the processes of nodulation, infection thread formation and nitrogenase activity in nodules on the roots of the host plant, medicago sativa (alfalfa). interaction with the plant is initiated by genes encoding sensing and motility systems by which the bacteria recognizes and approaches the root. signal molecules, such as flavonoids, mediate a ... | 1989 | 14542173 |
| early nodulin genes are induced in alfalfa root outgrowths elicited by auxin transport inhibitors. | rhizobium nod genes are essential for root hair deformation and cortical cell division, early stages in the development of nitrogen-fixing root nodules. nod(-) mutants are unable to initiate nodules on legume roots. we observed that n-(1-naphthyl)phthalamic acid and 2,3,5-triiodobenzoic acid, compounds known to function as auxin transport inhibitors, induced nodule-like structures on alfalfa roots. the nodule-like structures (pseudonodules) were white, devoid of bacteria, and resembled nodules e ... | 1989 | 16594017 |
| the evolution of specificity in the legume-rhizobium symbiosis. | we know more about the partnership between legumes and their root-nodule bacteria than about any other symbiosis or any other plant-microbe interaction. in the light of recent research we are beginning to see details of an elaborate tapestry. the rhizobia are not a self-contained branch on the bacterial tree; their ancestry is intertwined with that of photosynthetic and pathogenic bacteria. their host ranges, which vary enormously in breadth, overlap to form a tangled web of interconnections bet ... | 1989 | 21227376 |
| host-range related structural features of the acidic extracellular polysaccharides of rhizobium trifolii and rhizobium leguminosarum. | proton nuclear magnetic resonance (1h nmr) and fast atom bombardment mass spectrometric analyses were performed on enzymatically derived oligosaccharides from the acidic excreted polysaccharides (eps) from representative bacterial strains of the pea-nodulating symbiont, rhizobium leguminosarum (128c53, 128c63, and 300) and the clover-nodulating symbiont, rhizobium trifolii (na-30, anu843, 0403, ta-1, lpr5035, usda20.102, and 4s). the results revealed structural similarities and differences betwe ... | 1989 | 2912966 |
| characterization of three choline transport activities in rhizobium meliloti: modulation by choline and osmotic stress. | choline has both a nutritional and osmoregulatory role in rhizobium meliloti (t. bernard, j. a. pocard, b. perroud, and d. le rudulier, arch. microbiol. 143:359-364, 1986). in view of this fact, choline transport was studied in r. meliloti 102f34 to determine how the rate of choline uptake is modulated. the effects of the cultural conditions on the kinetics of transport are presented. a high-affinity activity and a low-affinity activity were found in cells grown in minimal medium. the addition o ... | 1989 | 2914855 |
| roles of flagella, lipopolysaccharide, and a ca2+-dependent cell surface protein in attachment of rhizobium leguminosarum biovar viciae to pea root hair tips. | the relationship between ca2+-dependent cell surface components of rhizobium leguminosarum biovar viciae, motility, and ability to attach to pea root hair tips was investigated. in contrast to flagella and lipopolysaccharide, a small protein located on the cell surface was identified as the ca2+-dependent adhesin. | 1989 | 2914856 |
| protoporphyrinogen oxidation, a step in heme synthesis in soybean root nodules and free-living rhizobia. | extracts of the crude bacteroid fraction of symbiotically grown bradyrhizobium japonicum were much more active in oxidizing protoporphyrinogen to protoporphyrin than were extracts of cells grown under free-living conditions, especially when assayed in atmospheres containing only traces of oxygen. this correlates with the higher heme content of the microaerophilic nodules. furthermore, the high level of oxidative activity in the crude bacteroid fraction was associated with an uncharacterized memb ... | 1989 | 2914857 |
| immunological characterization of rhizobium leguminosarum outer membrane antigens by use of polyclonal and monoclonal antibodies. | surface antigens of rhizobium leguminosarum biovar viciae strain 248 were characterized by using polyclonal and monoclonal antibodies. with western immunoblotting as the criterion, an antiserum raised against living whole cells recognized mainly flagellar antigens and the o-antigen-containing part of the lipopolysaccharide (lps). immunization of mice with a peptidoglycan-outer membrane complex yielded eight monoclonal antibodies, of which three reacted with lps and five reacted with various sets ... | 1989 | 2914865 |
| cooperative interaction of agrobacterium vire2 protein with single-stranded dna: implications for the t-dna transfer process. | induction of agrobacterium tumefaciens vir gene expression by wounded plant cells results in production of a free transferable single-stranded (ss) copy of t-dna, the t-strand. one of the vir proteins, the vire2 polypeptide, is a ssdna-binding protein. in the present work, interaction of nopaline-specific vire2 protein (mr 69,000) with ssdna was studied by using nitrocellulose filter binding, gel retardation, and electron microscopy techniques. the vire2 protein was found to bind to ssdna molecu ... | 1989 | 2919168 |
| identification and sequence analysis of two related flagellin genes in rhizobium meliloti. | the genomic region that codes for the flagellin subunits of the complex flagellar filaments of rhizobium meliloti was cloned and sequenced. two structural genes, flaa and flab, that encode 395- and 396-amino-acid polypeptides, respectively, were identified. these exhibit 87% sequence identity. the amino acid sequences of tryptic peptides suggest that both of these subunit proteins are represented in the flagellar filaments. the n-terminal methionine was absent from the mature flagellin subunits. ... | 1989 | 2921241 |
| role for [corrected] agrobacterium tumefaciens chva protein in export of beta-1,2-glucan. | functional chva and chvb genes are required for attachment of agrobacterium tumefaciens to plant cells, an early step in crown gall tumor formation. strains defective in these loci do not secrete normal amounts of cyclic beta-1,2-glucan. whereas chvb is required for beta-1,2-glucan synthesis, the role of chva in glucan synthesis or export has not been clearly defined. we found that cultures of chva mutants contained as much neutral beta-1,2-glucan in the cell pellets as did the wild type, with n ... | 1989 | 2921245 |
| a protein required for transcriptional regulation of agrobacterium virulence genes spans the cytoplasmic membrane. | the vira protein is one of two proteins required for transcriptional activation of agrobacterium tumefaciens virulence genes in response to phenolic compounds released by plants during infection. we describe two experimental approaches which indicate that this protein has a transmembrane topology. first, spheroplasts of escherichia coli or wild-type a. tumefaciens expressing the vira protein were treated with proteinase k to digest periplasmic proteins, and the remaining proteins were immunologi ... | 1989 | 2921246 |
| two chromosomal loci involved in production of exopolysaccharide in agrobacterium tumefaciens. | the chromosomal locus psca (exoc) of agrobacterium tumefaciens lba4301 has been cloned by complementation of the avirulent and exopolysaccharide (eps)-deficient mutant lba4301 psca. we have also identified a new locus, termed psda (polysaccharide depression) and located 16 kilobases from psca in the a. tumefaciens chromosome, that negatively affects eps production when it is present in more than one copy in a. tumefaciens lba4301. subcloning, transposon mutagenesis, and transcriptional analysis ... | 1989 | 2921249 |
| the effect of interspecies transfer of rhizobium host-specific nodulation genes on acidic polysaccharide structure and in situ binding by host lectin. | host specificity in the rhizobium-legume symbiosis is controlled in the bacterium by host specific nodulation (hsn) genes residing on its symbiotic plasmid. we have examined the structure of the major acidic heteropolysaccharide produced by recombinant hybrid strains of rhizobium leguminosarum carrying cloned r. trifolii hsn genes with those produced by the parent donor and recipient strains. alteration of the nod gene composition of r. leguminosarum strain 300 by introduction of an 8-kilobase s ... | 1989 | 2925631 |
| high levels of double-stranded transferred dna (t-dna) processing from an intact nopaline ti plasmid. | to obtain bacterial-mediated oncogenic transformation of plants, the transferred dna (t-dna) of the tumor-inducing (ti) plasmid of agrobacterium tumefaciens is transferred to its plant host cells during infection. the initial phases of transformation involve the processing of the t-dna in the bacterial cell after induction of the vir genes located on the ti plasmid. the kinetics and conditions of this processing were examined and upon induction with acetosyringone up to 40% of the left and right ... | 1989 | 2928322 |
| ntr-like promoters and upstream regulatory sequence ftr are required for transcription of a developmentally regulated caulobacter crescentus flagellar gene. | the flbg (hook operon or transcription unit ii) and flan (transcription unit i) operons of caulobacter crescentus have a -12, -24 nucleotide sequence motif that is very similar to those of the nif and ntr promoters of enteric bacteria and rhizobium spp. and a conserved ftr (flagellar gene transcription regulation) sequence, previously designated ii-1 (d. a. mullin, s. a. minnich, l.-s. chen, and a. newton, j. mol. biol. 195:939-943, 1987) at approximately -100. we have used site-directed mutagen ... | 1989 | 2470725 |
| transient transfection of mammalian cells with dna of the plant-pathogenic ti-plasmid and expression of marker and resident sequences. | the large ti-plasmid from agrobacterium tumefaciens strain c58 has been used for transfection experiments with mammalian cells. in dna from tupaia baby fibroblasts ti-plasmid sequences could be identified by filter hybridization as long as four weeks after transfection including two cell passages. the hybridization signals decreased rapidly after addition of the ti-plasmid dna-coprecipitate to the cells. the signals were often not detected any more after the first day, but were visible one week ... | 1989 | 2471056 |
| oxyr, a positive regulator of hydrogen peroxide-inducible genes in escherichia coli and salmonella typhimurium, is homologous to a family of bacterial regulatory proteins. | the oxyr gene is required for the induction of a regulon of hydrogen peroxide-inducible genes in escherichia coli and salmonella typhimurium. the e. coli oxyr gene has been cloned and sequenced, revealing an open reading frame (305 amino acids) that encodes a 34.4-kda protein, which is produced in maxicells carrying the oxyr clone. the oxyr protein shows homology to a family of positive regulatory proteins including lysr in e. coli and nodd in rhizobium. like them, oxyr appears to be negatively ... | 1989 | 2471187 |
| the maize en-1/spm element transposes in potato. | the maize transposable element en-1 has been introduced into a diploid potato line via transformation with agrobacterium tumefaciens. the element is transcriptionally active in potato. numerous en specific rnas are observed, including a 6 kb transcript characteristic of an active en-1 element in maize. in contrast to maize, where the 6.0 kb transcript is hardly detectable, this transcript is very abundant in the transgenic potato. transposition of en-1 in the potato clone was analysed by souther ... | 1989 | 2475754 |
| differential regulation of soybean chalcone synthase genes in plant defence, symbiosis and upon environmental stimuli. | four independent recombinant lambda clones hybridizing to parsley chalcone synthase (chs) cdna were isolated from a soybean (glycine max) genomic library. restriction fragment length polymorphism (rflp) analysis indicated that the chs gene family comprises six members. the chs genes were found to be clustered with three genes on a 10 kb segment and pairs on others. dna sequences of the 5'-, the coding-, and the 3' untranslated regions were determined for three different genes. a consensus alignm ... | 1989 | 2476656 |
| protection against tobacco mosaic virus in transgenic plants that express tobacco mosaic virus antisense rna. | transgenic tobacco plants that express rna sequences complementary to the tobacco mosaic virus (tmv) coat protein (cp) coding sequence with or without the trna-like structure at the 3' end of the tmv rna were produced. progeny of self-pollinated plants were challenged with tmv to determine their resistance to infection. plants that expressed rna sequences complementary to the cp coding region and the 3' untranslated region, including the trna-like sequences, were protected from infection by tmv ... | 1989 | 2476807 |
| altered imino diacid synthesis and transcription in crown gall tumors with transposon tn5 insertions in the 3' end of the octopine synthase gene. | octopine synthase encoded by the t-dna (transferred dna) locus ocs synthesizes n2-(d-1-carboxyethyl)-l-amino acids in octopine-type crown gall tumors. so far, derivatives of only basic amino acids have been isolated. we have detected a glutamine derivative and called it heliopine. tumors induced by several ti plasmids with transposon tn5 insertions in the 3' end of ocs still synthesized small quantities of n2-(1-carboxyethyl)-arginine and n2-(1-carboxyethyl)-glutamine. in addition, n2-(1,3-dicar ... | 1989 | 2478521 |
| extensive changes in dna methylation patterns accompany activation of a silent t-dna ipt gene in agrobacterium tumefaciens-transformed plant cells. | we crossed a male-sterile, agrobacterium-transformed nicotiana tabacum plant that contains a silent, hypermethylated t-dna ipt oncogene with a normal tobacco plant and found that the methylated state of the ipt gene was stably inherited through meiosis in the offspring. however, when tissues of these plants were placed in cell culture, the ipt gene was spontaneously reactivated in a very small fraction of the cells; if 5-azacytidine was added to the culture medium, ipt gene reactivation occurred ... | 1989 | 2479825 |
| signal structure for transcriptional activation in the upstream regions of virulence genes on the hairy-root-inducing plasmid a4. | the inducibility of the vir genes (vira, -b, -c, -d, -e, and -g) on pria4 was examined at the transcriptional level, and the rna-starting sites were determined by s1-nuclease mapping and primer-extension experiments. all of these genes were inducible, while vira, -e, and -g were transcribed even under noninducing conditions. each transcription of virb, -c, -d, and -e was initiated at one particular site, but that of vira and -g occurred at two and three sites, respectively, depending on the cond ... | 1989 | 2479910 |
| [ribosomal rna sequencing with reverse transcriptase: its application to the phylogenetic study of cells]. | 1989 | 2480986 | |
| phleomycin resistance as a dominant selectable marker for plant cell transformation. | tobacco cells are sensitive to bleomycin and phleomycin. the tn5 and the streptoalloteichus hindustanus (sh) bleomycin resistance ('ble') genes conferring resistance to these antibiotics have each been inserted into two plant expression vectors. they are flanked by the nopaline synthase (nos) or the cauliflower mosaic virus (camv) 35s promoters on one side, and by the nos polyadenylation signal on the other. these four chimaeric genes were introduced into the binary transformation vector pga 492 ... | 1989 | 2485087 |
| anaerobic processes in yellow lupin (lupinus luteus l.) root nodules. | the lupin root nodule homogenate was separated by centrifugation in the percoll density gradient into the rhizobium bacteroid fraction and plant subcellular components. high activities of alcohol dehydrogenase and lactate dehydrogenase in the soluble fraction of host plant, and high capability of the isolated bacteroids to oxidize ethanol, malate, lactate and acetaldehyde evidence functional interrelationship between the plant and bacteroids. | 1989 | 2486002 |
| nodule-specific repression of yellow lupin protein r18. | it was found, using immunochemical techniques, that protein r18 presumably specifically repressed during development of lupin root nodules (sikorski et al., 1989, acta biochim. polon., 36, 63-72) is present in various tissues of this plant. protein r18 was also detected in roots of four other legumes but was absent from the bacteroid-containing cells of root nodules. the data support our earlier view (sikorski et al., op. cit.) that expression of protein r18 is regulated by the coupled mechanism ... | 1989 | 2486003 |
| the nucleotide sequence of ribosomal 5s rna from rhizobium meliloti: comparison with 5s rrna of agrobacterium. | the complete nucleotide sequence of r. meliloti 5s ribosomal rna has been determined and compared with the already known sequence of a. tumefaciens 5s rrna (vandenberghe et al., 1985, eur. j. biochem., 149, 537-542) and of other 5s rrnas from rodobacteria alpha-2 (wolters et al., 1988, nucleic acids res., 16, rl-r70). the differences found at eight positions (23, 73, 83, 72 in helical fragments; 16, 40, 88 in loops; 54 in bulge), which might affect secondary structures of 5s rrna, are small. mor ... | 1989 | 2486005 |
| expression of bradyrhizobium japonicum nodulation gene in rhizobium fredii nod mutants. | the b. japonicum usda 110 plafr1 gene library was transferred to tn5-induced rhizobium fredii usda 191-4 nod- mutants with helper plasmid prk2013. smr tcr transconjugants occurred with a frequency of 5 x 10(-4). the transconjugants were purified and used to inoculate germinated soybean seeds. seven nodules were obtained in the nodulation experiment. the fast-growing nod+ smr tcr rhizobium fredii strain was isolated from all nodules. each isolate had acquired a new plasmid with a molecular mass o ... | 1989 | 2491321 |
| direct dna transfer to plant cells. | a range of somatic cell and molecular techniques are now available to supplement conventional plant breeding. the introduction and expression of foreign dna has been used to modify basic aspects of physiology and development, to introduce commercially important characteristics such as herbicide and insect resistance into plants and to insert genes suitable as dominant selectable markers for somatic hybridisation. several techniques for direct dna delivery are available, ranging from uptake of dn ... | 1989 | 2491654 |
| use of roots transformed by agrobacterium rhizogenes in rhizosphere research: applications in studies of cadmium assimilation from sewage sludges. | the use of roots transformed by agrobacterium rhizogenes in models for the rhizosphere is discussed. a list of species for which transformed root cultures have been obtained is provided and the example of studies of cadmium assimilation from sewage sludges is given to illustrate how transformed root cultures can be used in physiological tests under non-sterile conditions. | 1989 | 2491656 |
| transformation of plant cells via agrobacterium. | 1989 | 2491660 | |
| expression of a c3 plant rubisco ssu gene in regenerated c4 flaveria plants. | we report the successful transformation, via agrobacterium tumefaciens infection, and regeneration of two species of the genus flaveria: f. brownii and f. palmeri. we document the expression of a c3 plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these c4 plants. the organ-specific expression of this petunia gene in flaveria brownii is qualitatively identical to its endogenous pattern of expression. | 1989 | 2491665 |
| mutational analysis of the conserved domains of a t-region border repeat of agrobacterium tumefaciens. | left- and right-border repeats, which surround the t-region, contain two conserved regions separated by 5 bp that are not conserved. at the onset of t-dna processing vird-encoded proteins introduce a nick in the largest of these conserved regions (12 bp) at a specific position in the bottom strand between a guanine and thymine nucleotide [2, 33]. in this paper we describe the effect of several site-directed mutations in the right-border repeat on tumorigenicity of agrobacterium in plants. our da ... | 1989 | 2491670 |
| single-stranded dna used as an efficient new vehicle for transformation of plant protoplasts. | in relation to the question which dna form (single- or double-stranded) is transferred by agrobacterium tumefaciens to plant cells, we studied the behaviour of single-stranded dna, as compared to double-stranded dna, when it is introduced into plant protoplasts by electroporation. to this end, we cloned a construct with a plant nptii gene as well as a cat gene in the m13 vectors tg130 and tg131. we found that both complementary single-stranded molecules gave rise to substantial cat activity in p ... | 1989 | 2491686 |
| sequence of the pseudomonas aeruginosa trpi activator gene and relatedness of trpi to other procaryotic regulatory genes. | in pseudomonas aeruginosa, the trpi gene product regulates the expression of the trpba gene pair encoding tryptophan synthase. trpi and trpba are transcribed divergently. the trpi dna sequence and deduced amino acid sequence were determined. the trpi start codon was found to be 103 base pairs from that of trpb. trpi encodes a 293-residue protein and the size of the trpi gene product, measured on sodium dodecyl sulfatepolyacrylamide gels, was close to that calculated from the amino acid sequence. ... | 1989 | 2492495 |
| product of the lactococcus lactis gene required for malolactic fermentation is homologous to a family of positive regulators. | malolactic fermentation is a secondary fermentation that many lactic acid bacteria can carry out when l-malate is present in the medium. the activation of the malolactic system in lactococcus lactis is mediated by a locus we call mler. induction of the genes necessary to perform malolactic fermentation occurs only in bacteria with a functional copy of mler. the mler gene consists of one open reading frame capable of coding for a protein with a calculated molecular mass of 33,813 daltons. the ami ... | 1989 | 2498286 |
| evidence for divalent cation (ca2+)-stabilized oligomeric proteins and covalently bound protein-peptidoglycan complexes in the outer membrane of rhizobium leguminosarum. | two unusual characteristics of some outer membrane proteins of rhizobium leguminosarum are described. first, most of the major outer membrane proteins could only be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after lysozyme treatment of the isolated cell envelopes, suggesting a very strong, possibly covalent, interaction of these proteins with the peptidoglycan. these peptidoglycan-associated outer membrane proteins belonged to two distinct groups of immunologically r ... | 1989 | 2500420 |
| effect of carbofuran, carbaryl, and their metabolites on the growth of rhizobium sp. and azotobacter chroococcum. | 1989 | 2500994 | |
| identification and characterization of the nifh and nifj promoter regions located on the nif-plasmid pea3 of enterobacter agglomerans 333. | small restriction fragments of the plasmid-borne enterobacter agglomerans 333 nif region were cloned into a promoter probe plasmid as transcriptional fusions with the lacz gene. identification of nifa-dependent promoters was accomplished by using a compatible plasmid which constitutively expresses the klebsiella pneumoniae nifa gene. beta-galactosidase assays showed strong activation of the cloned e. agglomerans promoters in escherichia coli by the heterologous k. pneumoniae nifa gene product. t ... | 1989 | 2504647 |
| construction of a lacz-kanamycin-resistance cassette, useful for site-directed mutagenesis and as a promoter probe. | a lacz gene without a promoter, but containing its ribosome-binding site, was cloned next to the kanamycin-resistance (kmr) gene of plasmid puc4k, yielding a lacz-kmr cassette. from the resulting plasmid, pkok5, the lacz-kmr cassette was recloned by means of bamhi into plasmid pkok4, a mobilizable derivative of pbr322 which mediates ampicillin, chloramphenicol and tetracycline resistance. the lacz-kmr cassette can be excised from pkok5 or pkok6 by digestion with bamhi, sali or psti. it can be us ... | 1989 | 2515118 |
| the -24/-12 promoter comes of age. | a new bacterial promoter type has been identified in the last few years. originally designated as nif (= nitrogen fixation) or ntr (= nitrogen regulation) consensus promoter, it is now evident that this promoter occurs in many different bacterial species and is used not only for genes involved in nitrogen assimilation but also for genes determining many other unrelated metabolic functions. the general features of this type of promoter are (i) the conserved -24(gg)/-12(gc) consensus sequence, (ii ... | 1989 | 2517036 |
| analysis of the major inducers of the rhizobium noda promoter from vicia sativa root exudate and their activity with different nodd genes. | root exudate of vicia sativa contains 7 inducers for the noda promoter of rhizobium leguminosarum biovar viciae. six of these inducers are flavanones. one inducer was identified as 3,5,7,3'-tetrahydroxy-4'-methoxyflavanone, and a second inducer most likely is 7,3'-dihydroxy-4'-methoxyflavanone. the inducing activity of these compounds and the other inducers depends on the nodd gene present in the test strains, which originated either from r. leguminosarum biovars viciae or trifolii, or from r. m ... | 1989 | 2519112 |
| chva locus may be involved in export of neutral cyclic beta-1,2-linked d-glucan from agrobacterium tumefaciens. | extracellular and intracellular neutral beta-1,2-linked d-glucan content was determined in a virulent, attachment-deficient mutants of agrobacterium tumefaciens that map in the chva locus. chva mutants contained approximately the same amount of intracellular glucan as cells of the virulent control strain a759, but released into the culture medium only 2% of the glucan released by strain a759. introduction of a cosmid carrying the wild-type chv region restored attachment and virulence and restore ... | 1989 | 2520158 |
| expression of agrobacterium nopaline-specific vird1, vird2, and virc1 proteins and their requirement for t-strand production in e. coli. | induction of ti plasmid virulence (vir) genes during early stages of the genetic transformation of plant cells by agrobacterium tumefaciens results in several molecular events that are involved in generating a transferable t-dna copy. these events include site-specific nicking at the t-dna borders and synthesis of free, unipolar, linear, single-stranded copies of the t-dna (t-strands). here e. coli was used as a heterologous cell to assay the requirements for t-strand synthesis. cells of e. coli ... | 1989 | 2520160 |
| the relationship between nodulin gene expression and the rhizobium nod genes in vicia sativa root nodule development. | the role of the rhizobium nod genes in the induction of nodulin gene expression was examined by analyzing nodules formed on vetch roots by bacterial strains containing only the nod region. introduction of an 11-kb cloned nod region of the r. leguminosarum sym plasmid prl1ji into sym plasmid-cured rhizobia conferred on the recipient strains the ability to induce nodules in which all nodulin genes were expressed. this proves that from the sym plasmid only the nod region is involved in the inductio ... | 1989 | 2520161 |
| nucleotide sequence and protein products of two new nodulation genes of rhizobium meliloti, nodp and nodq. | previous studies had suggested the existence of nodulation (nod) genes downstream of nodg in rhizobium meliloti strain 1021. we have established the dna sequence and analyzed the translation products of the genes located in this position. computer analysis of the dna sequence revealed a number of overlapping putative open-reading frames (orfs), so we constructed several clones that contained either full-length or truncated orfs. the protein products of these clones were expressed in both r. meli ... | 1989 | 2520820 |
| extension of host range of rhizobium leguminosarum bv. trifolii caused by point mutations in nodd that result in alterations in regulatory function and recognition of inducer molecules. | the positive activation of several nodulation genes in strain anu843 of rhizobium leguminosarum biovar trifolii is mediated by the product of the nodd gene and by the interaction of nodd with plant-secreted inducer and anti-inducer compounds. we have mutagenized the nodd gene of strain anu843 with nitrosoguanidine and have found that the ability of the mutated nodd products to interact with inducer and anti-inducer compounds is affected by the amino acid sequence in at least two key regions, inc ... | 1989 | 2520822 |
| isolation and characterization of a rhizobium loti gene required for effective nodulation of lotus pedunculatus. | a rhizobium loti gene required for effective invasion of the host lotus pedunculatus has been identified by transposon tn5 mutagenesis. cosmids that complemented a previously isolated mutation (239) at this invasion (inv) locus were identified by in planta complementation and used to construct a physical map of the gene region. the insertion site of tn5 in pn239 was mapped to a 7.5-kb ecori fragment, which complemented the mutation when subcloned into plafr1. further tn5 mutagenesis of the 7.5-k ... | 1989 | 2520823 |
| identification, cloning, and sequence analysis of the nitrogen regulation gene ntrc of agrobacterium tumefaciens c58. | we describe the cloning of an ntrc gene of agrobacterium tumefaciens c58 by interspecific complementation of an escherichia coli ntrc mutant. restriction mapping and southern blot analysis of the complementing clone identified a 1.7-kb ecori-pvuii dna fragment whose sequence was determined. analysis of this sequence revealed coding regions corresponding to a complete ntrc gene and the c-terminal region of an ntrb gene. amino acid sequence comparisons of a. tumefaciens ntrc protein with ntrc sequ ... | 1989 | 2520824 |
| a gene required for transfer of t-dna to plants encodes an atpase with autophosphorylating activity. | the virb operon of the agrobacterium tume-faciens ptia6nc plasmid likely plays a role in directing t-dna transfer events at the bacterial membrane, as determined previously by mutagenesis and cellular fractionation studies and by dna sequence analysis of the approximately 12-kilobase-pair operon. the dna sequence analysis also revealed consensus mononucleotide binding domains in the deduced virb5 and virb11 gene products, suggesting that one or both of these proteins couple energy, by means of n ... | 1989 | 2532360 |
| a non-nodulating alfalfa mutant displays neither root hair curling nor early cell division in response to rhizobium meliloti. | the early events in the alfalfa-rhizobium meliloti symbiosis include deformation of epidermal root hairs and the approximately concurrent stimulation of cell dedifferentiation and cell division in the root inner cortex. these early steps have been studied previously by analysis of r. meliloti mutants. bacterial strains mutated in nodabc, for example, fail to stimulate either root hair curling or cell division events in the plant host, whereas exopolysaccharide (exo) mutants of r. meliloti stimul ... | 1989 | 2535468 |
| promoters of the rola, b, and c genes of agrobacterium rhizogenesare differentially regulated in transgenic plants. | chimeric genes containing the beta-glucuronidase reporter gene under the control of the rola, b, and c promoters of agrobacterium rhizogenes are expressed in a regulated manner in transgenic plants. the intergenic region separating the rolb and c genes represents a bidirectional promoter. this bidirectional promoter regulates transcription for both genes in a similar fashion in aerial organs of the plants, but in a distinct way in roots. moreover, both rolb and c promoter activities differ from ... | 1989 | 2535517 |
| multiple domains exist within the upstream activator sequence of the octopine synthase gene. | it is known that a 16-base pair palindrome (acgtaagcgcttacgt) located upstream of the ocs gene can activate a maize adh1 promoter in a transient expression system [ellis et al. (1987). embo j. 6, 11-16; ellis et al. (1987). embo j. 6, 3203-3208]. we have determined that this palindrome is also essential for ocs promoter activity in tobacco calli. in addition, sequences immediately adjacent to this palindrome, both 5' and 3', modulate its activity. the palindrome is sensitive to the differentiate ... | 1989 | 2535532 |
| level of expression of the tomato rbcs-3a gene is modulated by a far upstream promoter element in a developmentally regulated manner. | by agrobacterium-mediated transformation we have demonstrated that a 1.10-kilobase promoter sequence from the tomato rbcs-3a gene confers light-inducible and organ-specific expression upon fusion to the bacterial chloramphenicol acetyltransferase gene. a biphasic expression profile was obtained by 5' deletion analysis of this promoter, indicating the presence of both positive and negative regulatory elements. a severe reduction in the level of expression was observed when the 5'-terminal 90 base ... | 1989 | 2535544 |
| cloning and analysis of genes involved in coenzyme b12 biosynthesis in pseudomonas denitrificans. | cobalamin synthesis probably requires 20 to 30 different enzymatic steps. pseudomonas putida and agrobacterium tumefaciens mutants deficient in cobalamin synthesis (cob have been isolated. in p. putida, cob mutants were identified as being unable to use ethanolamine as a source of nitrogen in the absence of added cobalamin (deamination of ethanolamine requires coenzyme b12 as a cofactor). in a. tumefaciens, cob mutants were simply screened for their reduced cobalamin synthesis. a genomic library ... | 1989 | 2536665 |
| isolation and characterization of mutants of rhizobium leguminosarum bv. viciae 248 with altered lipopolysaccharides: possible role of surface charge or hydrophobicity in bacterial release from the infection thread. | effects of alterations in lipopolysaccharide (lps) structure of rhizobium leguminosarum bv. viciae on effective symbiosis and on a number of cell surface characteristics were studied. tn5 mutants with altered lpss were screened for their inability to bind monoclonal antibody 3, one of three monoclonal antibodies to the tentative o-antigenic part of the wild-type lps of strain 248. ten class i lps mutants completely lacked the o-antigen-containing lps species. the class ii lps mutant had a severe ... | 1989 | 2536673 |
| rhizobium meliloti fixghi sequence predicts involvement of a specific cation pump in symbiotic nitrogen fixation. | we present genetic and structural analyses of a fix operon conserved among rhizobia, fixghi from rhizobium meliloti. the nucleotide sequence of the operon suggests it may contain a fourth gene, fixs. adjacent open reading frames of this operon showed an overlap between tga stop codons and atg start codons in the form of an atga motif suggestive of translational coupling. all four predicted gene products contained probable transmembrane sequences. fixg contained two cysteine clusters typical of i ... | 1989 | 2536685 |
| a novel exopolysaccharide can function in place of the calcofluor-binding exopolysaccharide in nodulation of alfalfa by rhizobium meliloti. | we have found that r. meliloti strain rm1021, which is known to synthesize a calcofluor-binding exopolysaccharide (eps i), also has a cryptic capacity to synthesize a second exopolysaccharide (eps ii). structural analysis of eps ii has shown that it differs in many respects from eps i. genetic analysis indicates that eps ii synthesis requires the products of at least seven loci on the second symbiotic megaplasmid of r. meliloti, and is induced by a mutation, expr101, which causes increased trans ... | 1989 | 2537152 |
| coordinate regulation and sensory transduction in the control of bacterial virulence. | genes and operons that encode bacterial virulence factors are often subject to coordinate regulation. these regulatory systems are capable of responding to various environmental signals that may be encountered during the infectious cycle. for some pathogens, proteins that mediate sensory transduction and virulence control are similar to components of other bacterial information processing systems. understanding the molecular mechanisms governing global regulation of pathogenicity is essential fo ... | 1989 | 2537530 |
| sequence determination and characterization of the replicator region in the tumor-inducing plasmid ptib6s3. | the replicator region of the 195-kilobase-pair (kb) tumor-inducing plasmid ptib6s3 was previously identified by isolation of a 6.8-kb miniplasmid (b.p. koekman, p.j.j. hooykaas, and r.a. schilperoort, plasmid 7:119-132, 1982). this miniplasmid was joined to cole1-based vectors and subjected to mutagenesis. the resulting mutant plasmids were examined for their ability to replicate autonomously in agrobacterium tumefaciens. it was found that a 4.2-kb region was sufficient for displaying replicatio ... | 1989 | 2537824 |
| the vird operon of agrobacterium tumefaciens ti plasmid encodes a dna-relaxing enzyme. | the vird locus of agrobacterium tumefaciens ti plasmid encodes functions necessary for endonucleolytic cleavage of transferred dna (t-dna) prior to its transfer to plant cells. for the overproduction of the vird proteins in escherichia coli a tac-vird operon fusion was constructed. a significant increase in the accumulation of vird proteins was observed in a lon protease-deficient e. coli host. the presence of an overlapping open reading frame (orf) upstream of the vird1 coding sequence had a ne ... | 1989 | 2541431 |
| identification of bradyrhizobium nod genes involved in host-specific nodulation. | three loci important for soybean nodulation by bradyrhizobium japonicum were delimited by tn5 mutagenesis on a 5.3-kilobase ecori fragment adjacent to the nodabc genes. results of hybridization studies suggested that this region is conserved in bradyrhizobium species but absent in all rhizobium species. lacz translational fusions of two of the loci contained in this region were found to be inducible by host-produced flavonoid chemicals via a mechanism requiring a functional nodd gene product. a ... | 1989 | 2542223 |
| symbiotic properties of rhizobia containing a flavonoid-independent hybrid nodd product. | a hybrid nodd gene consisting of 75% of the nodd1 gene of rhizobium meliloti at the 5' end and 27% of the nodd gene of rhizobium trifolii at the 3' end activates the six tested inducible nod promoters of rhizobium leguminosarum, r. trifolii, or r. meliloti to maximal levels, even in the absence of flavonoids. in strains containing such a constitutive activating nodd gene, transcription of nod genes started at the same site as in flavonoid-induced strains containing a wild-type nodd gene. in cont ... | 1989 | 2544568 |
| isr1, a transposable dna sequence resident in rhizobium class iv strains, shows structural characteristics of classical insertion elements. | isr1 is a small transposable element, identified in rhizobium class iv strains by its high frequent mutagenic insertion into plasmid rp4. hybridization studies showed that isr1 is present in, multiple copies in rhizobium class iv strains. nucleotide sequence analysis revealed that isr1 has a length of 1260 bp and is characterized by perfect inverted repeats of 13 nucleotides followed by a stretch of 28/29 nucleotides with imperfect homology. the insertion under study generated a target site dupl ... | 1989 | 2544911 |
| identification of insertion sequence element is427 in ptit37 plasmid dna of an agrobacterium tumefaciens t37 isolate. | the isolation and characterization of an insertion sequence (is) element, is427, from agrobacterium tumefaciens t37 is described. is427 is present in three nonidentical copies on the ptit37 plasmid. the copy that was isolated through transposition on the entrapment vector pucd800 contains at its ends a 16-bp imperfect inverted repeat and generates a 2-bp duplication of the target dna. is427 does not show homology with previously characterized is elements of a. tumefaciens, based on hybridization ... | 1989 | 2544912 |
| plasmid localization and mapping of two azospirillum brasilense loci that affect exopolysaccharide synthesis. | two azospirillum brasilense loci that correct rhizobium meliloti exob and exoc mutants for exopolysaccharide (eps) synthesis have been identified previously (k. w. michiels, j. vanderleyden, a. p. van gool, e. r. signer, j. bacteriol., 1988b). a. brasilense exo mutants produce eps of lower molecular weight than the wild type strain. here, we show by hybridization that these exo loci are located on a 90-mda plasmid in a. brasilense sp7. in four other azospirillum strains but not in a. lipoferum s ... | 1989 | 2544914 |