Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| flavonoids released naturally from alfalfa seeds enhance growth rate of rhizobium meliloti. | alfalfa (medicago sativa l.) releases different flavonoids from seeds and roots. imbibing seeds discharge 3',4',5,7-substituted flavonoids; roots exude 5-deoxy molecules. many, but not all, of these flavonoids induce nodulation (nod) genes in rhizobium meliloti. the dominant flavonoid released from alfalfa seeds is identified here as quercetin-3-o-galactoside, a molecule that does not induce nod genes. low concentrations (1-10 micromolar) of this compound, as well as luteolin-7-o-glucoside, anot ... | 1991 | 16668056 |
| evidence for cytokinin involvement in rhizobium (ic3342)-induced leaf curl syndrome of pigeonpea (cajanus cajan millsp.). | a uniquely abnormal shoot development (shoot tip-bending, leaf curling, release from apical dominance, and stunted growth) in pigeonpea (cajanus cajan millsp) induced by a nodulating rhizobium strain, ic3342, is thought to be due to a hormonal imbalance. amaranthus betacyanin bioassay indicated that xylem exudate and leaf extracts from pigeonpea plants with rhizobium-induced leaf curl symptoms contained high concentrations of cytokinin relative to those in normal plants. radioimmunoassay (ria) o ... | 1991 | 16668086 |
| growth enhancement and developmental modifications of in vitro grown potato (solanum tuberosum spp. tuberosum) as affected by a nonfluorescent pseudomonas sp. | a plant growth-promoting rhizobacterium, designated ps jn and isolated from onion roots, was identified as a nonfluorescent pseudomonas sp. the percentage of similarity of ps jn to p. gladioli (ncppb 1891), p. cichorii (ncppb 943), and p. viridiflava (ncppb 635), as determined from 135 biochemical and physiological tests was 77, 70, and 66%, respectively. ps jn persisted through successive generations of in vitro cultured potato plantlets, both as endophytic and epiphytic populations. in vitro i ... | 1991 | 16668277 |
| anthocyanidins and flavonols, major nod gene inducers from seeds of a black-seeded common bean (phaseolus vulgaris l.). | eleven compounds released from germinating seeds of a black-seeded bean (phaseolus vulgaris l., cv pi165426cs) induce transcription of nod genes in rhizobium leguminosarum biovar phaseoli. aglycones from 10 of those compounds were identified by spectroscopic methods (ultraviolet/visible, proton nuclear magnetic resonance, and mass spectroscopy), and their biological activities were demonstrated by induction of beta-galactosidase activity in r. leguminosarum strains containing noda-lacz or nodc-l ... | 1991 | 16668462 |
| rhizobium nod gene inducers exuded naturally from roots of common bean (phaseolus vulgaris l.). | four compounds exuded from young roots of a black-seeded bean (phaseolus vulgaris l., cv pi165426cs) induce transcription of nod genes in rhizobium leguminosarum biovar phaseoli. the three most active nod gene inducers were identified by spectroscopic methods (ultraviolet/visible absorbance, proton nuclear magnetic resonance, and mass spectrometry) as being eriodictyol (5,7,3',4' -tetrahydroxyflavanone), naringenin (5,7,4' -trihydroxyflavanone), and a 7-o-glycoside of genistein (5,7,4' -trihydro ... | 1991 | 16668463 |
| alfalfa controls nodulation during the onset of rhizobium-induced cortical cell division. | the formation of first nodules inhibits subsequent nodulation in younger regions of alfalfa (medicago sativa l.) roots by a feedback regulatory mechanism that controls nodule number systemically (g caetano-anollés, wd bauer [1988] planta 175: 546-557). following inoculation with wild-type rhizobium meliloti, almost all infections associated with cortical cell division developed into mature nodules. while the distribution of rhizobium- induced cell divisions closely paralleled the distribution of ... | 1991 | 16667992 |
| release and modification of nod-gene-inducing flavonoids from alfalfa seeds. | traces of luteolin, an important rhizobial nod gene inducer in rhizobium meliloti, are released by alfalfa (medicago sativa l.) seeds, but most luteolin in the seed exudate is conjugated as luteolin-7-o-glucoside (l7g). processes affecting the production of luteolin from l7g in seed exudate are poorly understood. results from this study establish that (a) seed coats are the primary source of flavonoids, including l7g, in seed exudate; (b) these flavonoids exist in seeds before imbibition; and (c ... | 1991 | 16668057 |
| 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 ... | 1991 | 16348523 |
| 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 ... | 1991 | 16348600 |
| 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 ... | 1991 | 16348432 |
| 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 ... | 1991 | 16348502 |
| 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 ... | 1991 | 16348512 |
| 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 ... | 1991 | 16348589 |
| biotransformation of the pentahydroxy flavone quercetin by rhizobium loti and bradyrhizobium strains (lotus). | lotus rhizobia catabolized quercetin in an arabinose-based medium via a novel form of c-ring cleavage, yielding phloroglucinol and protocatechuic acid. conservation of the a and b rings of the flavone suggests that a chalcone could be formed as a transient intermediate. | 1991 | 16348495 |
| diglyceride kinase activity in cell extracts of rhizobium meliloti: evidence for a diglyceride cycle during cyclic beta-1,2-glucan biosynthesis. | in this article, we provide evidence for the presence of diglyceride kinase activity in cell extracts of rhizobium meliloti 1021. characterization of the rhizobial enzyme revealed that it shares many properties with the diglyceride kinase of escherichia coli. a possible role for this enzyme during cyclic beta-1,2-glucan biosynthesis is discussed. | 1991 | 16348611 |
| improvement of rhizobium inoculants by mutation, genetic engineering and formulation. | the use of mutation and genetic engineering techniques have resulted in rhizobium strains with improved characteristics. the latter approach can provide improvement and new traits not achievable previously. enhanced commercial rhizobium inoculants, however, still rely solely on traditional approaches including formulation improvement, mutation, and strain selection. the lack of contribution to the commercial product lines by genetic engineering is mostly due to the time delay and financial burde ... | 1991 | 14548735 |
| a simple method for measuring acetylene reduction of intact, nodulated black locust seedlings. | a simple method is described for measuring acetylene (c(2)h(2)) reduction of nodulated black locust (robinia pseudoacacia l.) seedlings. the c(2)h(2) reduction chamber consists of a standard plant pot sealed at one end with a stopper having holes for the seedling and a gas inlet port, and sealed at the other end with a stoppered collar with a gas port. the chamber temperature is regulated by circulating water at a controlled temperature through a copper coil surrounding the plant pot. a pump rec ... | 1991 | 14972842 |
| expression of rhizobium galegae common nod clones in various backgrounds. | the cosmid clone prg30, carrying common nodulation genes of rhizobium galegae hambi 1174, and prg33, a subclone of prg30 that contains a 5.7-kb clai insert carrying noddabc were conjugated into various rhizobium nod- mutant strains and into a ti plasmid-cured agrobacterium tumefaciens. complementation and expression of the nodabc genes of r. galegae were studied by following microscopically the infection process and the nodulation on different test plants. the nodabc genes of r. galegae compleme ... | 1991 | 1804401 |
| betaine use by rhizosphere bacteria: genes essential for trigonelline, stachydrine, and carnitine catabolism in rhizobium meliloti are located on psym in the symbiotic region. | rhizobium meliloti is known to use betaines synthesized by its host, medicago sativa, as osmoprotectants and sources of energy. it is shown in the present report that the symbiotic megaplasmid (psym) of r. meliloti rcr2011 encodes functions essential to the catabolism of three betaines, trigonelline (nicotinic acid n-methylbetaine), stachydrine (proline betaine or dimethylproline), and carnitine (gamma-trimethyl-beta-hydroxybutyrobetaine). preliminary evidence is presented showing that functions ... | 1991 | 1804402 |
| 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. ... | 1991 | 1804765 |
| antigenic changes in lipopolysaccharide i of rhizobium leguminosarum bv. viciae in root nodules of vicia sativa subsp. nigra occur during release from infection threads. | three different monoclonal antibodies raised against the o antigen-containing lipopolysaccharide (lps i) of free-living cells were used in an immunocytochemical study to follow the fate of lps i on the outer membrane of rhizobium leguminosarum bv. viciae 248 during the nodulation of vicia sativa subsp. nigra. after immunogold labeling, the lps i epitopes were detected on the outer membrane of bacteria present in infection threads throughout the nodule. epitopes were not detectable on bacteria re ... | 1991 | 1708764 |
| application of a metabolic balancing technique to the analysis of microbial fermentation data. | a general method for the development of fermentation models, based on elemental and metabolic balances, is illustrated with three examples from the literature. physiological parameters such as the (maximal) yield on atp, the energetic maintenance coefficient, the p/o ratio and others are estimated by fitting model equations to experimental data. further, phenomenological relations concerning kinetics of product formation and limiting enzyme activities are assessed. the results are compared with ... | 1991 | 1807198 |
| rhizobium meliloti exopolysaccharides. structures, genetic analyses, and symbiotic roles. | 1991 | 1809206 | |
| development of the legume root nodule. | 1991 | 1809347 | |
| involvement of the syrm and nodd3 genes of rhizobium meliloti in nod gene activation and in optimal nodulation of the plant host. | we identified and sequenced the regulatory syrm and nodd3 genes of rhizobium meliloti 41. both genes were shown to contribute to optimal nodulation of alfalfa. in r. meliloti strains carrying syrm and nodd3 on plasmid, the nod genes are expressed constitutively, resulting in host-range extension to siratro. this is due to the presence of multiple syrm copies, suggesting that syrm participates directly in nod gene activation. nodd3 activates nod genes in conjunction with flavonoids and enhances s ... | 1991 | 1809842 |
| site-directed mutagenesis and dna sequence of pcka of rhizobium ngr234, encoding phosphoenolpyruvate carboxykinase: gluconeogenesis and host-dependent symbiotic phenotype. | we have cloned and sequenced the pcka gene of rhizobium sp. ngr234, a broad host-range strain. the gene encodes phosphoenolpyruvate carboxykinase (pepck), a key enzyme of gluconeogenesis. the locus was isolated and subcloned from a genomic library of ngr234 employing hybridization with an r. meliloti pck gene probe and complementation of a tn5 mutant in this species. the dna sequence of pcka (ngr234) was determined and encoded a pepck protein of 535 amino acids with a molecular weight of 58.4 kd ... | 1991 | 1720862 |
| [pea (pisum sativum) genes participating in symbiosis with nitrogen-fixing bacteria. ii. nucleotide sequence of cdna and parts of the late nodulin-6 (psnod6) gene]. | certain characteristics of late noduline gene from pea-nod6 were investigated as part of works of characterization of higher plant genes taking part in symbiotic nitrogen fixation. the complete 450 b.p. long cdna was sequenced, it's coding sequence includes the open reading frame. the part of dna containing the corresponding gene from the genomic clone was also sequenced. the predicted nod6 amino acid sequence has been analyzed and do not reveal the significant homology with any known protein. | 1991 | 1813810 |
| studies of the bradyrhizobium japonicum nodd1 promoter: a repeated structure for the nod box. | induction of nod genes in rhizobium and bradyrhizobium species is dependent on the presence of plant-produced flavonoids, the nodd protein, and the cis-acting nod box promoter sequence. although the nodd (nodd1) gene in rhizobium species is constitutively expressed, nodd1 expression in bradyrhizobium japonicum is inducible by isoflavones in a manner similar to that of the nodyabc operon. a consensus nod box sequence is found 5' of the nodyabc operon, whereas a presumptive, nod box-like sequence ... | 1991 | 1675210 |
| a pyruvate-stimulated adenylate cyclase has a sequence related to the fes/fps oncogenes and to eukaryotic cyclases. | the pyruvate-stimulated adenylate cyclase from brevibacterium liquefaciens produces up to 450 microm cyclic amp in the culture medium when the bacterium is grown on glucose and alanine. in this paper we report the cloning, expression and sequencing of the gene for this enzyme. residues were identified, within the c-terminal domain, which are conserved in adenylate and guanylate cyclase sequences from eukaryotes and in the adenylate cyclase of the prokaryote rhizobium meliloti. we have also ident ... | 1991 | 1683468 |
| an alternative approach for gene transfer in trees using wild-type agrobacterium strains. | micropropagated shoots of three forest tree species, poplar (populus tremula x p. alba), wild cherry (prunus avium l.) and walnut (juglans nigra x j. regia), were inoculated each with six different wild-type agrobacterium strains. poplar and wild cherry developed tumors that grew hormone-independently, whereas on walnut, gall formation was weak. on poplar and wild cherry, tumors induced by nopaline strains developed spontaneously shoots that had a normal phenotype and did not carry oncogenic t-d ... | 1991 | 1653060 |
| [the role of phytoalexins in natural plant resistance]. | 1991 | 1819793 | |
| production of tsr factor by rhizobium meliloti. | the root exudates of alfalfa (medicago sativa) and mungbean (vigna radiata) induced the tsr (thick and short roots) factor production in rhizobium meliloti. the factor caused a 30-40% reduction of root length in alfalfa seedlings. pea root exudate had no tsr induction activity. the flavonoid naringenin could replace the roots in inducing tsr production. naringenin-induced tsr factor caused 70% shortening of main roots. the tsr inducing property of naringenin was specific since quercetin and syri ... | 1991 | 1823653 |
| [establishing the substrate specificity of site-specific deoxyribonuclease rtri]. | 1991 | 1830740 | |
| molecular cloning and nucleotide sequence of the rhizobium phaseoli reca gene. | a recombinant lambda phage carrying the reca gene of rhizobium phaseoli was isolated from a r. phaseoli genomic library by complementation of the fec- phenotype of the recombinant phage in escherichia coli. when expressed in e. coli, the cloned reca gene was shown to restore resistance to both uv irradiation and the dna alkylating agent methyl methanesulphonate (mms). the r. phaseoli reca gene also promoted homologous recombination in e. coli. the cloned reca gene was only weakly inducible in e. ... | 1991 | 1832737 |
| agrobacterium mediated genetic transformation of chickpea, cicer arietinum l. | in leaf and stem explants of chickpea, wild type strains of agrobacteria were able to induce tumors. these tumors were capable of phytohormone independent growth. a supervirulent strain a281 was found to be most effective. thus, using an agrobacterium r1601, which carries genes conferring supervirulent phenotype along with a plant selectable marker gene (npt ii), transformed calli of chickpea were selected in the presence of 100 micrograms/ml level of kanamycin. molecular analyses of genomic dna ... | 1991 | 1769719 |
| identification of nolr, a negative transacting factor controlling the nod regulon in rhizobium meliloti. | in rhizobium meliloti, expression of the nodulation genes (nod and nol genes) is under both positive and negative controls. these genes are activated by the products of the three related nodd genes, in conjunction with signal molecules from the host plants. we showed that negative regulation is mediated by a repressor protein, binding to the overlapping nodd1 and noda as well as to the nodd2 promoters. the encoding gene, termed nolr, was identified and cloned from strain 41. by subcloning, delet ... | 1991 | 1840615 |
| swimming against the tide: chemotaxis in agrobacterium. | chemotaxis in bacteria is an excellent model for signal transduction processes. in agrobacterium tumefaciens, the causative agent of crown gall tumour on wounded plants, it is a vital part of the organism's biology. a chromosomally-determined chemotaxis system causes the bacterium to be attracted into the rhizosphere by chemoattractants in plant exudates. by interfacing with this system, the multifunctional products of two ti-plasmid encoded genes, vira and virg, allow the sensing of specific wo ... | 1991 | 1772407 |
| transduction of plant signal molecules by the rhizobium nodd proteins. | the regulatory nodd proteins of rhizobium bacteria mediate the activation of a gene set responsible for symbiotic nodule formation by plant signal molecules. here we discuss the signal recognition and gene activation properties of nodd and present a model summarizing the current knowledge on nodd action. | 1991 | 1772413 |
| comparative response of pisum sativum nodulated with indigenous soil rhizobium populations and/or co-inoculated with a rhizobium leguminosarum strain. i. acetylene-reducing, dihydrogen- and carbon dioxide-evolving activities. | no significant differences in the acetylene-reducing activity and evolution of h2 and co2 from nodulated roots of pisum sativum inoculated with soil rhizobium populations from two soils with different acidities (ruzynĕ soil 7.6; lukavec soil 4.9) were observed. rhizobium population from lukavec soil formed nodules, exhibiting a higher h2 evolution. co-inoculation with the hup+ strain 128c30 (7 x 10(7) cells per seedling) eliminated, to some extent, the effect of soil populations on physiological ... | 1991 | 1841862 |
| organ-dependent regulation of a plant promoter isolated from rice by 'promoter-trapping' in tobacco. | a vector containing a transcriptionally inactive neomycin phosphotransferase ii gene was used to select promoter sequences from a pool of random genomic dna fragments. this paper describes how one such sequence (p4.7) isolated from oryza sativa acts as a hormonally regulated promoter in nicotiana tabacum. relative expression ratios in leaf, root, midrib, callus, and stem tissue of tobacco plants are 1:5:4:10:17. histochemical assays show that p4.7 activates the uida reporter gene throughout the ... | 1991 | 1844878 |
| aerobic inactivation of rhizobium meliloti nifa in escherichia coli is mediated by lon and two newly identified genes, snob and snoc. | the rhizobium meliloti nifa protein is an oxygen-sensitive transcriptional regulator of nitrogen fixation genes. regulation of nifa activity by oxygen occurs at the transcriptional level through fixlj and at the posttranslational level through the sensitivity of nifa to oxygen. we have previously reported that the nifa protein is sensitive to oxygen in escherichia coli as well as in r. meliloti. to investigate whether the posttranslational regulation of nifa is dependent on host factors conserve ... | 1991 | 1846139 |
| regulation of rhizobium meliloti exo genes in free-living cells and in planta examined by using tnphoa fusions. | the exo loci of rhizobium meliloti are necessary for the production of an acidic exopolysaccharide, eps i, that is needed for alfalfa nodule invasion by strain rm1021. we have isolated and characterized alkaline phosphatase fusions made with tnphoa in several exo loci of r. meliloti and used these fusions to examine the subcellular localization of exo gene products and the regulation of exo genes in free-living cells and in planta. in the course of this work, we isolated a new exo locus, exot. w ... | 1991 | 1846141 |
| microbial metabolism of quinoline and related compounds. xi. degradation of quinoline-4-carboxylic acid by microbacterium sp. h2, agrobacterium sp. 1b and pimelobacter simplex 4b and 5b. | from soil enrichment cultures four strains, using quinoline-4-carboxylic acid as sole source of energy and carbon, have been isolated. according to their physiological properties these bacteria have been identified as microbacterium sp. designated h2, as agrobacterium sp. designated 1b and pimelobacter simplex designated 4b and 5b. metabolites of the degradation pathway of quinoline-4-carboxylic acid have been isolated and identified. with pimelobacter simplex 4b and 5b 2-oxo-1,2-dihydroquinolin ... | 1991 | 1793516 |
| characterization of three agrobacterium tumefaciens avirulent mutants with chromosomal mutations that affect induction of vir genes. | three agrobacterium tumefaciens mutants with chromosomal mutations that affect bacterial virulence were isolated by transposon mutagenesis. two of the mutants were avirulent on all hosts tested. the third mutant, ivr-211, was a host range mutant which was avirulent on bryophyllum diagremontiana, nicotiana tabacum, n. debneyi, n. glauca, and daucus carota but was virulent on zinnia elegans and lycopersicon esculentum (tomato). that the mutant phenotype was due to the transposon insertion was dete ... | 1991 | 1846853 |
| positive regulators of opine-inducible promoters in the nopaline and octopine catabolism regions of ti plasmids. | the noc and occ regions of nopaline and octopine ti plasmids in agrobacterium tumefaciens contain genes for the catabolism of nopaline and octopine, respectively. we investigated the transcriptional organization and regulation of both regions. the noc region of ptic58 contains two nopaline-inducible promoters, and one octopine-inducible promoter was identified in the occ region of ptiach5. all three promoters are positively regulated in trans by constitutively expressed genes localized at the ri ... | 1991 | 1799698 |
| isolation and characterization of insertion sequence elements from gram-negative bacteria by using new broad-host-range, positive selection vectors. | on the basis of an rsf1010-derived broad-host-range vector, three different systems which enable positive detection and isolation of insertion sequence (is) elements from gram-negative bacteria were constructed. vectors psup104-phes, psup104-rpsl, and psup104-sac were used successfully in a number of rhizobium strains and in xanthomonas campestris. more than 20 different is elements were isolated and characterized. the 16 is elements from rhizobium meliloti were further used to characterize vari ... | 1991 | 1847366 |
| transcription of the octopine catabolism operon of the agrobacterium tumor-inducing plasmid ptia6 is activated by a lysr-type regulatory protein. | agrobacterium tumefaciens incites crown gall tumors on plant hosts by conjugally transferring a discrete fragment of oncogenic dna. in addition to oncogenes, the transferred dna contains genes that direct the synthesis and exudation of opines, which are used as nutrients by the bacteria. the bacterium contains one or more operons of ti plasmid-encoded genes that are required for the internalization and utilization of opines, and transcription of these catabolic genes is induced by cognate opines ... | 1991 | 1799699 |
| mutants of the agrobacterium tumefaciens vira gene exhibiting acetosyringone-independent expression of the vir regulon. | hydroxylamine-induced mutations in the vira gene of agrobacterium tumefaciens that do not require the plant phenolic-inducing compound acetosyringone for vir regulon induction were isolated. the isolation was based on the activation of both virb::lacz and vire::cat fusions by mutant vira loci in the absence of acetosyringone. three of these vira(ais) (acetosyringone-independent signaling) mutants were characterized. all three mutants expressed a virb::lacz fusion at high levels in the absence of ... | 1991 | 1799700 |
| repetitive sequences with homology to bradyrhizobium japonicum dna and the t-dna of agrobacterium rhizogenes are closely linked to nodabc of rhizobium fredii usda257. | we have detected strong homology between a 9.2-kb ecori restriction fragment from rhizobium fredii usda257 that contains nodabc and eight additional ecori fragments in dna digests from this organism. a series of repetitive sequences responsible for this hybridization lies within a 0.95-kb hindiii/sali subfragment about 1-kb upstream of noda. this subfragment also hybridizes to multiple restriction fragments from nine other strains of r. fredii, but only one is common to all strains. the 0.95-kb ... | 1991 | 1799702 |
| the hexose transporters at the plasma membrane and the tonoplast of transformed plant cells: kinetic characterization of two distinct carriers. | the plasma membrane hexose transporter and the tonoplast hexose transporter from heterotrophically grown transformed nicotiana tabacum cells have been studied in vitro using membrane vesicles for trans-zero transport studies. in highly purified phase-partitioned outside-out plasma membrane vesicles (pmv) the hexose transporter showed an apparent km value of 230 microm (substrate: 3-o-methyl-d-glucose (3-omg); phi 7.2/pho 7.2), which was reduced to 120 microm when a ph gradient was imposed (pho 5 ... | 1991 | 1849009 |
| polymorphism of nopaline-type t-dnas from agrobacterium tumefaciens. | the structure of several t-dnas of agrobacterium tumefaciens was determined by molecular cloning and southern hybridization. the t-dnas cloned in escherichia coli vectors from four different nopaline type strains (pyte1, po31, po22, and ake10) showed various sizes of restriction enzyme fragments. comparative analysis of the restriction maps revealed that the t-dnas were composed of three distinct structural domains: (1) the region proximal to the right border (domain i) containing the portion es ... | 1991 | 1674610 |
| 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 ... | 1991 | 1779763 |
| rhizobium meliloti exopolysaccharides: genetic analyses and symbiotic importance. | genetic experiments have indicated that succinoglycan (eps i), the acidic calcofluor-binding exopolysaccharide, of the nitrogen-fixing bacterium rhizobium meliloti strain rm1021 is required for nodule invasion and possibly for later events in nodule development on alfalfa and other hosts. fourteen exo loci on the second megaplasmid have been identified that are required for, or affect, the synthesis of eps i. mutations in certain of these loci completely abolish the production of eps i and resul ... | 1991 | 1783190 |
| plant cell culture in the production of flavour compounds. | 1991 | 1783202 | |
| 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 ... | 1991 | 1787800 |
| an agrobacterium two-component regulatory system for the detection of chemicals released from plant wounds. | crown gall tumorigenesis by agrobacterium tumefaciens requires the co-ordinate transcriptional induction of a set of pathogenesis genes. at least three classes of environmental stimuli act synergistically to induce these genes: (i) monocyclic aromatic hydrocarbons such as acetosyringone, coniferyl alcohol, and vanillin, (ii) neutral or acidic monosaccharides such as glucose and glucuronic acid, and (iii) acidic ph. three proteins are required to sense and respond to these stimuli: (i) vira, a tr ... | 1991 | 1791750 |
| acidic conditions permit effective nodulation of alfalfa by invasion-deficient rhizobium meliloti exod mutants. | rhizobium meliloti exod mutants are deficient in invasion of alfalfa nodules and, as a consequence, the nodules that exod strains induce fail to fix nitrogen. these nodules appear to be arrested at the same stage as nodules induced by other exo mutants, which do not make an acidic exopolysaccharide called eps i, or by ndv mutants, which do not produce a periplasmic cyclic beta(1,2) glucan. however previous genetic and biochemical evidence suggested that the nodule invasion defect of exod mutants ... | 1991 | 1748284 |
| expression of the gene encoding the coat protein of cucumber mosaic virus (cmv) strain wl appears to provide protection to tobacco plants against infection by several different cmv strains. | the gene (cp) encoding the coat protein (cp) of cucumber mosaic virus (cmv) strain wl (cmv-wl, which belongs to cmv subgroup ii) was custom polymerase chain reaction (cpcr)-engineered for expression as described by slightom [gene 100 (1991) 251-255]. cpcr amplification was used to add 5'- and 3'-flanking ncoi sites to the cmv-wl cp gene, and cp was cloned into the expression vector, puc18cpexp. this cmv-wl cp expression cassette was transferred into the genome of tobacco (nicotiana tabacum cv. h ... | 1991 | 1748291 |
| t-dna gene 5 of agrobacterium modulates auxin response by autoregulated synthesis of a growth hormone antagonist in plants. | oncogenes carried by the transferred dna (t-dna) of agrobacterium ti plasmids encode the synthesis of plant growth factors, auxin and cytokinin, and induce tumour development in plants. other t-dna genes regulate the tumorous growth in ways that are not yet understood. to determine the function of t-dna gene 5, its coding region was expressed in escherichia coli. synthesis of the gene 5 encoded protein (26 kda) correlated with a 28-fold increase in conversion of tryptophan to indole-3-lactate (i ... | 1991 | 1756712 |
| transcriptional interference in transgenic plants. | when a promoterless marker gene is transformed into the plant genome using the agrobacterium vector system, on average 30% of the t-dna inserts produce gene fusions. this suggests that the t-dna is preferentially integrated into transcribed regions. here, we proposed that this transcriptional activity is responsible for some of the variation in expression frequently observed among independent transformants. using hybrid gene constructions, we show that transcriptional readthrough into a downstre ... | 1991 | 1662656 |
| the products of rhizobium genes, psi and pss, which affect exopolysaccharide production, are associated with the bacterial cell surface. | translational fusions between a mutant phoa (lacking its promoter, ribosomal binding site and signal peptide sequence) and rhizobium 'symbiotic' genes were isolated. since these fusions expressed alkaline phosphatase (ap), the product of phoa, the genes into which phoa was inserted apparently specify proteins located in the bacterial periplasm or cell membrane, the compartment in which ap has activity. these genes were psia and genes upstream of psia (psia is required for normal nodule developme ... | 1991 | 1662758 |
| nodules elicited by rhizobium meliloti heme mutants are arrested at an early stage of development. | heme-deficient mutants of rhizobium and bradyrhizobium have been found to exhibit diverse phenotypes with respect to symbiotic interactions with plant hosts. we observed that r. meliloti hema mutants elicit nodules that do not contain intracellular bacteria; the nodules contain either no infection threads ("empty" nodule phenotype) or aberrant infection threads that failed to release bacteria (bar- phenotype). these mutant nodules expressed nodulin genes associated with nodules arrested at an ea ... | 1991 | 1766439 |
| 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 ... | 1991 | 1768143 |
| do rhizobia produce cytokinins? | two rhizobium strains were cultured on a defined medium; one was a normal strain of the cowpea group (anu240) while the other (ic3342) was an unusual but related strain of the same group which induced abnormal shoot development, including proliferation of lateral buds, in nodulated plants. culture supernatants were examined for the presence of cytokinins by mass spectrometry using deuterium-labelled internal standards and by radioimmunoassay. in culture supernatants of both strains a range of cy ... | 1991 | 1768251 |
| characterization of three soluble c-type cytochromes isolated from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705. | three soluble, low molecular mass cytochromes c (mr 8000-15,000) were isolated and purified from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705. on the basis of their alpha: absorbance peaks in the reduced forms, they were named cytochromes c550, c552 and c555. cytochrome c552 reacted very fast, c555 very slowly and c550 not at all with carbon monoxide. the complete amino acid sequence (73 residues) of cytochrome c552 was established which identifies it as a monoheme, cl ... | 1991 | 1663887 |
| plant genetic control of nodulation. | 1991 | 1741618 | |
| the product of the rhizobium meliloti ilvc gene is required for isoleucine and valine synthesis and nodulation of alfalfa. | tn5-induced mutants of rhizobium meliloti that require the amino acids isoleucine and valine for growth on minimal medium were studied. in one mutant, 1028, the defect is associated with an inability to induce nodules on alfalfa. the tn5 mutation in 1028 is located in a chromosomal 5.5-kb ecori fragment. complementation analysis with cloned dna indicated that 2.0 kb of dna from the 5.5-kb ecori fragment restored the wild-type phenotype in the ilv- nod- mutant. this region was further characteriz ... | 1991 | 1744032 |
| characterization of the supervirulent virg gene of the agrobacterium tumefaciens plasmid ptibo542. | the virg gene of the agrobacterium tumefaciens ti plasmid ptibo542 has previously been reported to elicit stronger vir gene expression than its counterpart in the ptia6 plasmid, a property we call the "superactivator" phenotype. the dna sequence of the ptibo542 virg gene was determined and compared to that of the ptia6 gene. the dna sequences of these genes differ at 16 positions: two differences are in the promoter regions, 12 are in the coding regions, and two are in the 3' untranslated region ... | 1991 | 1745238 |
| polygalacturonase is a virulence factor in agrobacterium tumefaciens biovar 3. | agrobacterium tumefaciens biovar 3 causes both crown gall and root decay of grapes. all biovar 3 strains, regardless of their tumorigenicity, produce in culture a single polygalacturonase with a pi around 4.5. a. tumefaciens biovar 3 strain cg49 was mutagenized with tn5 by using psup2021 as a suicide vector. a mutant strain, cg50, lacking polygalacturonase activity was isolated. the mutation was due to a single tn5 insertion in an 8.5-kb ecori fragment that also contained the polygalacturonase s ... | 1991 | 1655716 |
| limited host range ti plasmids: recent origin from wide host range ti plasmids and involvement of a novel is element, is868. | agrobacterium tumefaciens biotype iii octopine strains have been isolated from grapevine tumors worldwide. they comprise limited and wide host range (lhr and whr) strains that carry related tumor-inducing (ti) plasmids with two t-regions, ta and tb. the whr ta-region resembles the biotype i octopine region, whereas the lhr ta-region is a recent deletion derivative of the whr ta-region, which lacks the iaa genes and part of the ipt gene. sequencing of the ta-region of the ubiquitous lhr strain ab ... | 1991 | 1657255 |
| the exor gene of rhizobium meliloti affects rna levels of other exo genes but lacks homology to known transcriptional regulators. | rhizobium meliloti strains mutant in the exor gene overproduce an exopolysaccharide called succinoglycan or eps i. protein fusions to several different exo genes required for eps i biosynthesis are expressed at a higher level in an exor strain than in a wild-type strain, showing that the overproduction of eps i in exor strains results at least in part from increased gene expression. this regulation is important to nodulation, since exor mutants fail to invade alfalfa nodules unless secondary sup ... | 1991 | 1711027 |
| phylogenetic analysis and evolution of rnase p rna in proteobacteria. | the secondary structures of the eubacterial rnase p rnas are being elucidated by a phylogenetic comparative approach. sequences of genes encoding rnase p rna from each of the recognized subgroups (alpha, beta, gamma, and delta) of the proteobacteria have now been determined. these sequences allow the refinement, to nearly the base pair level, of the phylogenetic model for rnase p rna secondary structure. evolutionary change among the rnase p rnas was found to occur primarily in four discrete str ... | 1991 | 1711030 |
| suppression of nodulation gene expression in bacteroids of rhizobium leguminosarum biovar viciae. | the expression of nod genes of rhizobium leguminosarum bv. viciae in nodules of pisum sativum was investigated at both the translational and transcriptional levels. by using immunoblots, it was found that the levels of noda, nodi, node, and nodo proteins were reduced at least 14-fold in bacteriods compared with cultured cells, whereas nodd protein was reduced only 3-fold. northern (rna) blot hybridization, rnase protection assays, and in situ rna hybridization together showed that, except for th ... | 1991 | 1712355 |
| transgenic rice cell lines and plants: expression of transferred chimeric genes. | cell suspension-derived rice (oryza sativa l.) protoplasts were transformed by direct gene uptake. peg-mediated transformation was more efficient than electroporation. plasmid dna containing a hygromycin phosphotransferase (hpt) gene (which confers hygromycin resistance) driven by the camv 35s promoter and a beta-d-glucuronidase (gus) gene under control of the 1', 2' double promoter of the mannopine synthase (mas) locus of agrobacterium tumefaciens was introduced into rice protoplasts. southern ... | 1991 | 1713479 |
| characterization of a soluble catalase-peroxidase hemoprotein b-590, previously identified as 'cytochrome alpha 1' from bradyrhizobium japonicum bacteroids. | the cytochrome "a1" or p-428, previously proposed to be a high affinity terminal oxidase in nitrogen-fixing bacteroids of bradyrhizobium japonicum has been purified. the water-soluble native hemoprotein has an mr of 136,000, lacks heme a and is a high-spin ferric protohemoprotein: it is slowly reduced with dithionite to give a species with an optical spectrum like that of hemoprotein b-590 (escherichia coli; peak at 555 nm, shoulder at 590 nm), and which reacts slowly with co. it has catalase an ... | 1991 | 1645695 |
| direct regeneration of transformed shoots in brassica napus from hypocotyl infections with agrobacterium rhizogenes. | genetically transformed root clones of rapeseed (brassica napus) were obtained after in vitro infection of excised hypocotyl segments with a wild type strain of agrobacterium rhizogenes and two strains of a. rhizogenes harbouring kanamycin resistance. the ability of hairy root formation was affected by light and was highly dependent on the location of the infection site at the hypocotyl. inoculation of decapitated hypocotyls with an intact root system gave rise to direct shoot formation from the ... | 1991 | 1651126 |
| characterization of a putative periplasmic transport system for octopine accumulation encoded by agrobacterium tumefaciens ti plasmid ptia6. | neoplastic crown gall tumors incited by agrobacterium tumefaciens release novel amino acid or sugar derivatives known as opines, whose synthesis is directed by genes transferred to plant cells. agrobacterium cells can transport and catabolize these compounds as sources of carbon and nitrogen. this article describes a region of the ptia6 plasmid which is required for catabolism of the opine octopine and whose transcription is induced by octopine. this region of the plasmid contains four open read ... | 1991 | 1655707 |
| analysis of rhizobium meliloti nodulation mutant wl131: novel insertion sequence isrm3 in nodg and altered nodh protein product. | nodulation (nod) genes are required for invasion of legumes by rhizobium bacteria. mutant wl131 is a derivative of 102f51 that has a severe nod- phenotype on alfalfa. upon examination of the extended dna region containing host-specific nodulation genes nodfeg and nodh, we found that the nodg gene of wl131 bears a novel insertion sequence, isrm3. complementation studies implied, however, that the phenotype on alfalfa correlated with the nodh locus. we found that nodh in wl131 encodes an altered g ... | 1991 | 1850728 |
| homology of the ligand-binding regions of rhizobium symbiotic regulatory protein nodd and vertebrate nuclear receptors. | the signal specificity and structure of sensor-activator proteins from different species (nodd of rhizobium bacteria and vertebrate nuclear receptors) were compared. several compounds (including flavonoids, coumestrol and estradiol) that bind to mammalian receptors also interact with nodd proteins. nodd-dependent synergism of the signal compounds luteolin and catechin was observed suggesting that these compounds bind directly to nodd. two regions comprising 63 and 37 amino acids in nodd showed 4 ... | 1991 | 1851955 |
| molecular basis of symbiotic host specificity in rhizobium meliloti: nodh and nodpq genes encode the sulfation of lipo-oligosaccharide signals. | the symbiosis between rhizobium and legumes is highly specific. for example, r. meliloti elicits the formation of root nodules on alfalfa and not on vetch. we recently reported that r. meliloti nodulation (nod) genes determine the production of acylated and sulfated glucosamine oligosaccharide signals. we now show that the biochemical function of the major host-range genes, nodh and nodpq, is to specify the 6-o-sulfation of the reducing terminal glucosamine. purified nod factors (sulfated or not ... | 1991 | 1760841 |
| formation of rhizobium phaseoli symbiotic plasmids by genetic recombination. | we report here the formation of symbiotic plasmids (psyms), by genetic recombination between rearranged psyms, which lack symbiotic information, and resistance plasmids carrying parts of different symbiotic plasmids (r's). this recombination was found to occur both between plasmids derived from different rhizobium phaseoli isolates, and between plasmids derived from strains obtained from the same original isolate. we also present evidence on the formation of a functional symbiotic plasmid by rec ... | 1991 | 1857210 |
| modular structure of fixj: homology of the transcriptional activator domain with the -35 binding domain of sigma factors. | the fixl/fixj two-component system is a global regulator of nitrogen-fixation genes in rhizobium meliloti. the transcriptional activator fixj contains two modules: its n-terminal module is homologous with other two-component regulators; its c-terminal module shows homology with various transcriptional activators, and with the c-terminal region of sigma factors, which is involved in the discrimination of the -35 region of bacterial promoters. we show that the c-terminal module of fixj contains th ... | 1991 | 1857213 |
| inoculation of vicia sativa subsp. nigra roots with rhizobium leguminosarum biovar viciae results in release of nod gene activating flavanones and chalcones. | flavonoids released by roots of vicia sativa subsp. nigra (v. sativa) activate nodulation genes of the homologous bacterium rhizobium leguminosarum biovar viciae (r. l. viciae). inoculation of v. sativa roots with infective r. l. viciae bacteria largely increases the nod gene-inducing ability of v. sativa root exudate (a.a.n. van brussel et al., j bact 172: 5394-5401). the present study showed that, in contrast to sterile roots and roots inoculated with r. l. viciae cured of its sym plasmid, roo ... | 1991 | 1859867 |
| 35s-beta-glucuronidase gene blocks biological effects of cotransferred iaa genes. | the iaam and iaah genes of agrobacterium tumefaciens and agrobacterium rhizogenes play an important role in crown gall and hairy root disease. the iaam gene codes for tryptophan monooxygenase which converts tryptophan into indole-3-acetamide (iam). iam is converted into the auxin indole-3-acetic acid (iaa) by indoleacetamide hydrolase, encoded by the iaah gene. in functional studies on the activity of the iaa genes of the tb region of the a. tumefaciens biotype iii strain tm4, the frequently use ... | 1991 | 1859868 |
| electroporation of megaplasmids into agrobacterium. | 1991 | 1859872 | |
| genetic and molecular analyses of pica, a plant-inducible locus on the agrobacterium tumefaciens chromosome. | pica is an agrobacterium tumefaciens chromosomal locus, identified by mu d11681 mutagenesis, that is inducible by certain acidic polysaccharides found in carrot root extract. cloning and genetic analysis of a pica::lacz fusion defined a region of the pica promoter that is responsible for the induction of this locus. furthermore, we identified a possible negative regulator of pica expression upstream of the pica locus. this sequence, denoted pgl, has extensive homology to polygalacturonase genes ... | 1991 | 1860822 |
| a novel strategy for production of a highly expressed recombinant protein in an active form. | under standard growth conditions, e. coli transformed with the high-level expression vector pmon5525 produces recombinant dmapp/amp transferase in inactive, insoluble complexes. we have produced large amounts of active, soluble protein by growing and inducing the cells under osmotic stress in the presence of sorbitol and glycyl betaine. this caused an increase of up to 427-fold in the active yield, and the disappearance of the protein from the pelletable fraction of cell extracts. this treatment ... | 1991 | 1765138 |
| environmental conditions differentially affect vir gene induction in different agrobacterium strains. role of the vira sensor protein. | the induction of vir gene expression in different types of agrobacterium strains shows different ph sensitivity profiles. the ph sensitivity pattern demonstrated by octopine ti strains was similar to that of a supervirulent leucinopine ti strain, whereas this was different from that shown by nopaline ti strains and agropine ri strains. data are given which indicate that these differences are due to different properties of the vira genes of these wild types. an exceptional case was formed by stra ... | 1991 | 1863759 |
| isolation and characterization of rhizobium meliloti mutants affected in exopolysaccharide production. | rhizobium meliloti mutants affected in the production of exopolysaccharide (eps) were isolated after n-methyl-n'-nitro-n-nitrosoguanidine mutagenesis. the mutants were classified into three phenotypic classes: (i) exo-, rough mutants lacking exopolysaccharide; (ii) exos (for "small") which form tiny, compact colonies and synthesize reduced amounts of eps; and (iii) exoc (for "constitutive"), hypermucoid mutants which overproduce eps. hypermucoid strains showed increased resistance to desiccation ... | 1991 | 1867774 |
| sequence and analysis of the nodabc region of rhizobium fredii usda257, a nitrogen-fixing symbiont of soybean and other legumes. | we cloned and analyzed nodabc from rhizobium fredii usda257. these genes are thought to have common functions in initiation of nitrogen-fixing nodules by all rhizobia. in usda257, they were located in a 9.2-kb ecori fragment that was not closely linked to either of two copies of the regulatory gene, nodd. nodabc was present in a 3,094-base pair (bp) sequenced region, which also included a consensus nod-box promoter. the three open reading frames contained 654, 642, and 1,239 bp, respectively, an ... | 1991 | 1799701 |
| sequence of the iaa and ipt region of different agrobacterium tumefaciens biotype iii octopine strains: reconstruction of octopine ti plasmid evolution. | the ta regions of biotype iii octopine/cucumopine (oc) ti plasmids are closely related to the tl region of the biotype i octopine ti plasmids ptiach5 and pti15955. sequence analysis shows that the limited and wide host range biotype iii oc ta regions are derived from a common ancestor structure which lacked the 6a gene found in the biotype i octopine tl region. the ta region of the wide host range oc ti plasmids has conserved most of the original tl-like structure. in most wide host range oc iso ... | 1991 | 1868199 |
| sequence of agrobacterium tumefaciens biotype iii auxin genes. | 1991 | 1868204 | |
| a quick method to estimate the t-dna copy number in transgenic plants at an early stage after transformation, using inverse pcr. | agrobacterium-mediated transformation of plants is known to result in transgenic plants with a variable number of integrated t-dna copies. our aim was to obtain transgenic tobacco plants containing one integrated t-dna copy per genome. therefore, a quick method was developed to estimate the t-dna copy number of young transgenic plantlets within 10 weeks after transformation. inverse polymerase chain reaction (ipcr) was used to amplify junction fragments, i.e. plant genomic dna sequences flanking ... | 1991 | 1868218 |
| isolation of the spinach nitrite reductase gene promoter which confers nitrate inducibility on gus gene expression in transgenic tobacco. | nitrite reductase is the second enzyme in the nitrate assimilatory pathway. the transcription of this gene is regulated by nitrate as well as a variety of other environmental and developmental factors. genomic clones containing the entire nitrite reductase gene have been isolated from a spinach genomic library and sequenced. the sequence is identical in the transcribed region to a previously isolated spinach nir cdna clone (back et al., 1988) except for the presence of three introns. the analysi ... | 1991 | 1868226 |
| production of beta-carotene in zymomonas mobilis and agrobacterium tumefaciens by introduction of the biosynthesis genes from erwinia uredovora. | the erwinia uredovora crtb, crte, crti, and crty genes required for beta-carotene biosynthesis were introduced by conjugal transfer into an ethanol-producing bacterium, zymomonas mobilis, and a phytopathogenic bacterium, agrobacterium tumefaciens, in which no carotenoid is synthesized. the transconjugants of z. mobilis and a. tumefaciens carrying these genes appeared as yellow colonies and produced 220 and 350 micrograms of beta-carotene per g of dry weight, respectively, in the stationary phase ... | 1991 | 1872613 |
| isolation of agrobacterium radiobacter from a central venous catheter. | a case of septicemia caused by agrobacterium radiobacter is reported in a patient undergoing chemotherapy treatment who had recently been neutropenic. agrobacterium radiobacter was isolated from the hickman line blood culture. the patient responded favorably to removal of the hickman catheter and treatment with amikacin and piperacillin. the molecular and biochemical characteristics of the isolate are presented. | 1991 | 1874251 |
| structural analysis of a second acidic exopolysaccharide of rhizobium meliloti that can function in alfalfa root nodule invasion. | 1991 | 1878885 | |
| expression and quantification of firefly luciferase under control of rhizobium meliloti symbiotic promoters. | we have tested the use of firefly luciferase for monitoring regulated symbiotic nitrogen fixation gene expression. broad-host-range plasmids carrying translational fusions of rhizobium meliloti nifh, fixa and nifa promoters were constructed. despite low levels of promoter activity the absence of escherichia coli endogenous luminescence and the high sensitivity of the bioluminescent assay for firefly luciferase allowed rapid screening for functional luciferase expression. plasmids containing symb ... | 1991 | 1746317 |
| synchronous expression of leghaemoglobin genes in medicago truncatula during nitrogen-fixing root nodule development and response to exogenously supplied nitrate. | two leghaemoglobin genes from the diploid, autogamous medicago truncatula (mtlb1 and mtlb2) have been cloned and their nucleotide sequences determined. the deduced amino acid sequences encoded by these two genes differ significantly (18%), confirming that they belong to different sub-groups of medicago leghaemoglobin genes. rnase protection experiments have been used to show that both genes are transcriptionally active, and are expressed specifically in the nitrogen-fixing root nodule of m. trun ... | 1991 | 1883994 |
| cytosolic localization in transgenic plants of the rolc peptide from agrobacterium rhizogenes. | the rolc gene of agrobacterium rhizogenes codes for a peptide with an apparent molecular weight of approximately 20 kda. immunolocalization of the rolc peptide, in leaves of transgenic plants which are genetic mosaics for the expression of the rolc gene, is restricted to the phenotypically altered sectors. subcellular fractionation of homogenates from 35s-rolc transgenic leaves shows the cytosolic localization of the rolc peptide. | 1991 | 1884008 |