| construction and use of agrobacterium tumefaciens binary vectors with a. tumefaciens c58 t-dna genes. | five plant morphoregulatory genes were isolated from the agrobacterium tumefaciens ti plasmid and binary plasmid vectors for plant transformation with these genes were constructed. all vectors have a similar structure with t-dna borders, rk2 origin of replication and chimeric kanamycin resistance gene for the selection of transformed plant tissues. over twenty vectors with single and combined morphoregulatory genes were constructed and their effects after tobacco tissue transformation studied. | 1992 | 1505884 |
| transcription and autoregulation of the stabilizing functions of broad-host-range plasmid rk2 in escherichia coli, agrobacterium tumefaciens and pseudomonas aeruginosa. | the broad-host-range plasmid rk2 has been shown to encode several proteins important for its maintenance within bacterial populations of a number of gram-negative bacteria. their genes are organized into two operons: parcba and pard. these operons have been proposed to be transcribed from two divergent promoters, p-parcba and p-pard, located within a sequence of approximately 150 bases. in this report we identify and characterize the sequences required for regulated transcription from these prom ... | 1992 | 1508045 |
| factors affecting the rate of t-dna transfer from agrobacterium tumefaciens to nicotiana glauca plant cells. | different factors involved in the early steps of the t-dna transfer process were studied by using a beta-glucuronidase gene (gusa) as a reporter in nicotiana glauca leaf disc transformation experiments. the levels of transient expression of the gusa gene in leaf discs infected with several strains or vir mutants correlated well with their virulence phenotype, except for virc mutants. the rate of t-dna transfer was shown to be stimulated in the case of non-oncogenic strains by the co-transfer of ... | 1992 | 1511127 |
| growth inhibition and loss of virulence in cultures of agrobacterium tumefaciens treated with acetosyringone. | acetosyringone, a phenolic inducer of the virulence (vir) genes of agrobacterium tumefaciens, inhibited the growth of the nopaline-type strains t37 and c58 incubated under acidic conditions. in the course of a 6-day incubation with acetosyringone, avirulent clones were produced in different proportions by strains t37 and c58 and also by a spontaneous variant of strain c58, denominated c58f. the proportion of avirulent clones in acetosyringone-treated cultures often exceeded 50% for strains t37 a ... | 1992 | 1512200 |
| construction of a cassette enabling regulated gene expression in the presence of aromatic hydrocarbons. | a high-level expression cassette has been constructed from a tol plasmid derived from pseudomonas putida carrying all cis- and trans-acting regulatory elements necessary for transcriptional gene activation in the presence of aromatic hydrocarbons such as toluene. foreign dna can be inserted at unique kpni, saci, and ecori sites 7, 13, and 15 nucleotides downstream of a ribosome binding site. the cassette, flanked by bamhi and ecori restriction sites, was inserted into a broad-host-range vector a ... | 1992 | 1513877 |
| [multifactorial analysis of combined use of an antibiotic and peptidoglycan of microbial origin in experimental plague]. | the combined effect of doxycycline and microbial peptidoglycan was studied with multifactorial analysis. the drugs were used preventively and therapeutically. the preventive use of doxycycline in the subtherapeutic doses in combination with the immunomodulator resulted in a significant increase in the survival rate rather than the average life-span (als) of the experimental animals. the therapeutic use of the drugs was more efficient than the preventive one and resulted in higher survival and al ... | 1992 | 1514851 |
| a t-dna transfer stimulator sequence in the vicinity of the right border of pri8196. | an 8 bp sequence repeated 6 times is present to the right of the mannopine type pri8196 t-dna right-border sequence. experiments were designed to test whether these repeats have a role in t-dna transfer. several constructs in which different lengths of pri8196 right-border region were linked to the cucumopine synthesis gene on an agrobacterium-escherichia coli shuttle vector were made. the recombinant plasmids were tested for their efficiency to act as a source of t-dna in a binary system in whi ... | 1992 | 1515600 |
| evolution of agrobacteria and their ti plasmids--a review. | | 1992 | 1515664 |
| hierarchical analysis of linkage disequilibrium in rhizobium populations: evidence for sex? | many bacterial species exhibit strong linkage disequilibrium of their chromosomal genes, which apparently indicates restricted recombination between alleles at different loci. the extent to which restricted recombination reflects limited migration between geographically isolated populations versus infrequent mixis of genotypes within populations is more difficult to determine. we examined the genetic structure of rhizobium leguminosarum biovar phaseoli populations associated with wild and cultiv ... | 1992 | 1518873 |
| characterization of an aromatic amino acid aminotransferase from rhizobium leguminosarum biovar trifolii. | the most abundant aromatic amino acid aminotransferase of rhizobium leguminosarum biovar trifolii was partially purified. the molecular mass of the enzyme was estimated to be 53 kda by gel filtration. the enzyme transaminated aromatic amino acids and histidine. it used aromatic keto acids and alpha-ketoglutaric and oxalacetic acids as amino-group acceptors. the optimum temperature was 35 degrees c. using phenylalanine and alpha-ketoglutaric acid as substrates the activation energy was 46.2 kj.mo ... | 1992 | 1520732 |
| competition among rhizobium leguminosarum bv. phaseoli strains for nodulation of common bean. | six effective rhizobium leguminosarum bv. phaseoli strains were examined for nodulation competitiveness on common bean (phaseolus vulgaris l.), using all possible two-strain combinations of inoculum. nodule occupancy was determined with strain-specific fluorescent antibodies. the strains were divided into three groups according to their overall competitive abilities on pole bean cv. kentucky wonder and bush bean cv. bountiful. strains tal 182 and tal 1472 were highly competitive (greater than 70 ... | 1992 | 1521190 |
| isolation and characterization of a lectin from peanut roots. | a glucose-specific lectin has been purified to apparent homogeneity from 7-day-old peanut (arachis hypogaea) roots by affinity chromatography on a sephadex g-50. the lectin has a 66 kda native molecular mass and a 33 kda subunit molecular mass as revealed by native and denaturing sodium dodecyl sulphate-polyacrylamide gel electrophoresis, respectively. the purified lectin, gives a single precipitin line with the antiserum produced against 7-day-old root extract and shows 5 bands in the ph range ... | 1992 | 1525173 |
| purification and some properties of l-fucose dehydrogenase from agrobacterium radiobacter and its application to the assay of bound-fucose in glycoconjugates. | l-fucose dehydrogenase was found in the cell extract of agrobacterium radiobacter and purified to homogeneity about 480-fold with 16% recovery. the molecular weight of the enzyme was approx. 64,000. the enzyme was active in the neutral ph range, unlike other l-fucose or d-arabinose dehydrogenases which are active only in the alkaline ph range. using this enzyme and alpha-l-fucosidase f-i of bacillus circulans (tsuji, y., yamamoto, k., tochikura, t., seno, t., ohkubo, y. and yamaguchi, h. (1990) ... | 1992 | 1525177 |
| characterization of two genes (hupd and hupe) required for hydrogenase activity in azotobacter chroococcum. | in azotobacter chroococcum the hydrogenase structural genes (hupsl) cover about 2.8 kb of a 15-kb region associated with hydrogen-uptake (hup) activity. two other genes in this region, hupd and hupe, were located 8.9 kb downstream of hupl and were shown to be essential for hydrogenase activity by insertion mutagenesis. a fragment of dna beginning 3.4 kb downstream of hupl was able to complement the hupe mutant, supporting earlier evidence for a promoter downstream of hupsl. hybridization experim ... | 1992 | 1526470 |
| mechanism of activation of agrobacterium virulence genes: identification of phenol-binding proteins. | agrobacterium tumefaciens initiates the expression of pathogenic genes (vir genes) in response to host-derived phenolic signals through a two-component regulatory system consisting of vira and virg. alpha-bromoacetosyringone (asbr) was developed as an inhibitor of this induction process and found to be a specific and irreversible inhibitor of vir gene induction in this pathogen. formal replacement of one of the methoxy groups of asbr with iodine gave an equally effective inhibitor that could car ... | 1992 | 1528878 |
| a 2-o-methylfucose moiety is present in the lipo-oligosaccharide nodulation signal of bradyrhizobium japonicum. | bradyrhizobium japonicum is a soil bacterium that forms nitrogen-fixing nodules on the roots of the agronomically important legume soybean. microscopic observation of plant roots showed that butanol extract of b. japonicum strain usda110 cultures induced for nod gene expression elicited root hair deformation, an early event in the nodulation process. the metabolite produced by b. japonicum responsible for root hair deformation activity was purified. chemical analysis of the compound revealed it ... | 1992 | 1528893 |
| rol a modulates the sensitivity to auxin of the proton translocation catalyzed by the plasma membrane h(+)-atpase in transformed tobacco. | in order to investigate the effect of the rol a gene product on the plasma membrane response to auxin, a clone of rol a-transformed tobacco was prepared. auxin sensitivity was measured by the auxin concentration which induced the highest stimulation of h(+)-atpase-mediated proton translocation on isolated plasma membrane vesicles. both transformed and control plants exhibited identical auxin-sensitivity changes during vegetative and induction to flowering periods. however the sensitivity of flow ... | 1992 | 1531964 |
| csd2, csd3, and csd4, genes required for chitin synthesis in saccharomyces cerevisiae: the csd2 gene product is related to chitin synthases and to developmentally regulated proteins in rhizobium species and xenopus laevis. | in saccharomyces cerevisiae, chitin forms the primary division septum and the bud scar in the walls of vegetative cells. three chitin synthetic activities have been detected. two of them, chitin synthase i and chitin synthase ii, are not required for synthesis of most of the chitin present in vivo. using a novel screen, i have identified three mutations, designated csd2, csd3, and csd4, that reduce levels of chitin in vivo by as much as 10-fold without causing any obvious perturbation of cell di ... | 1992 | 1532231 |
| major flavonoids in uninoculated and inoculated roots of vicia sativa subsp. nigra are four conjugates of the nodulation gene-inhibitor kaempferol. | inoculation of vicia sativa subsp. nigra (v. sativa) roots with rhizobium leguminosarum biovar. viciae (r.l. viciae) bacteria substantially increases the ability of v. sativa to induce rhizobial nodulation (nod) genes. this increase is caused by the additional release of flavanones and chalcones which all induce the nod genes of r.l. viciae (k. recourt et al., plant mol biol 16: 841-852). in this paper, we describe the analyses of the flavonoids present in roots of v. sativa. independent of inoc ... | 1992 | 1536926 |
| characterization of salt-tolerant and salt-sensitive mutants of rhizobium leguminosarum biovar viciae strain c1204b. | spontaneous mutants of rhizobium leguminosarum biovar viciae strain c1204b were selected for their ability to tolerate 0.2 m nacl, a growth-inhibiting level of salt for the parental strain. transposon-mediated salt-sensitive mutants of strain c1204b were screened for their inability to grow in 0.08 m nacl. quantitation of the free-amino acid pools in the mutants grown in nacl revealed a dramatic increase in glutamine, serine, glutamate and proline, and to a lesser extent alanine and glycine in t ... | 1992 | 1537541 |
| cloning and sequencing of an agrobacterium tumefaciens beta-glucosidase gene involved in modifying a vir-inducing plant signal molecule. | induction of agrobacterium tumefaciens virulence genes by plant phenolic compounds is essential for successful t-dna transfer to a host plant. in douglas fir needles, the major virulence region inducer is the glycoside coniferin (j. w. morris and r. o. morris, proc. natl. acad. sci. usa 87:3612-3618, 1990). agrobacterium strains with high beta-glucosidase activity respond to coniferin and infect douglas fir seedlings, whereas most strains with low beta-glucosidase activity fail to respond to con ... | 1992 | 1537792 |
| characterization of an azospirillum brasilense sp7 gene homologous to alcaligenes eutrophus phbb and to rhizobium meliloti nodg. | a 4 kb sali fragment from azospirillum brasilense sp7 that shares homology with a 6.8 kb ecori fragment carrying nodgefh and part of nodp of rhizobium meliloti 41 was cloned in puc18 to yield pab503. the nucleotide sequence of a 2 kb sali-smai fragment of the pab503 insert revealed an open reading frame, named orf3, encoding a polypeptide sharing 40% identity with r. meliloti nodg. the deduced polypeptide also shared 60% identity with the alcaligenes eutrophus nadph-dependent acetoacetyl-coa (aa ... | 1992 | 1538694 |
| conserved motifs in a divergent nod box of azorhizobium caulinodans ors571 reveal a common structure in promoters regulated by lysr-type proteins. | nodulation of leguminous plants by rhizobium, bradyrhizobium, and azorhizobium spp. is dependent on the induction by the plant host of different bacterial nodulation (nod) loci. the transcription of these nod loci is activated in the presence of plant-produced flavonoids upon binding of the nodd protein--a lysr-type activator--to specific sequences present in the nod promoters. originally, a 47-base-pair (bp) region called the nod box was shown to be the target sequence for binding of nodd. from ... | 1992 | 1542656 |
| secretion of the rhizobium leguminosarum nodulation protein nodo by haemolysin-type systems. | the rhizobium leguminosarum biovar viciae nodulation protein nodo is partially homologous to haemolysin of escherichia coli and, like haemolysin, is secreted into the growth medium. the nodo protein can be secreted by a strain of e. coli carrying the cloned nodo gene plus the haemolysin secretion genes hlybd, in a process that also requires the outer membrane protein encoded by tolc. the related protease secretion genes, prtdef, from erwinia chrysanthemi also enable e. coli to secrete nodo. the ... | 1992 | 1545707 |
| characterization of a fixlj-regulated bradyrhizobium japonicum gene sharing similarity with the escherichia coli fnr and rhizobium meliloti fixk genes. | we describe the cloning, sequencing, regulation, and mutational analysis of a bradyrhizobium japonicum fixk-like gene whose product belongs to the family of fnr-crp-related regulatory proteins. the predicted 237-amino-acid fixk protein was found to share between 28 and 38% sequence identity with the escherichia coli fnr protein, other bacterial fnr-like proteins (fnrn, anr, and hlyx), and two rhizobial fixk proteins. the b. japonicum fixk-like gene, when expressed from a lac promoter, could func ... | 1992 | 1551834 |
| diauxic growth of agrobacterium tumefaciens 15955 on succinate and mannopine. | diauxic growth was observed upon incubation of agrobacterium tumefaciens 15955 on a mixture of succinate and mannopine as the carbon source. diauxic growth was also observed when either fumarate or l-malate was mixed with mannopine. no diauxie was detectable when a. tumefaciens 15955 was grown on a mixture of mannopine and glucose, fructose, sucrose, or l-arabinose. preferential utilization of succinate was observed in the initial growth phase of diauxie, whereas the final growth phase occurred ... | 1992 | 1551843 |
| agrobacterium tumefaciens transfers extremely long t-dnas by a unidirectional mechanism. | during crown gall tumorigenesis, part of the agrobacterium tumefaciens tumor-inducing (ti) plasmid, the t-dna, integrates into plant dna. direct repeats define the left and right ends of the t-dna, but tumorigenesis requires only the right-hand repeat. virulence (vir) genes act in trans to mobilize the t-dna into plant cells. transfer of t-dna begins when the vird endonuclease cleaves within the right-hand border repeat. although the t-dna right-border repeat promotes t-dna transmission best in ... | 1992 | 1551847 |
| new functional assignment of the carotenogenic genes crtb and crte with constructs of these genes from erwinia species. | the role of carotenoid genes crtb and crte has been functionally assigned. these genes were cloned from erwinia into escherichia coli or agrobacterium tumefaciens. their functions were elucidated by assaying early isoprenoid enzymes involved in phytoene formation. in vitro reactions from extracts of e. coli carrying the crte gene or a complete carotenogenic gene cluster in which crtb was deleted showed an elevated conversion of farnesyl pyrophosphate (fpp) into geranylgeranyl pyrophosphate (ggpp ... | 1992 | 1555761 |
| spontaneous mutation conferring the ability to catabolize mannopine in agrobacterium tumefaciens. | two nopaline-type strains of agrobacterium tumefaciens, c58 and t37, as well as strain a136, which is a ti plasmid-cured derivative of strain c58, gave rise to spontaneous mutants that were able to grow on mannopine. the observation of mutagenesis with strain a136 demonstrated that the ability to acquire this new catabolic potential was independent of the presence of a ti plasmid. the mutants were isolated after 4 weeks of incubation on minimal medium containing mannopine as the sole carbon sour ... | 1992 | 1556082 |
| the ntra gene of agrobacterium tumefaciens: identification, cloning, and phenotype of a site-directed mutant. | a 3.6-kb ecori fragment containing the ntra gene of agrobacterium tumefaciens was cloned by using the homologous ntra gene of rhizobium meliloti as a probe. construction of an ntra mutant of a. tumefaciens by site-directed insertional mutagenesis demonstrated the requirement of the ntra gene for nitrate utilization and c4-dicarboxylate transport but not for vir gene expression or tumorigenesis. | 1992 | 1556090 |
| biolistic transformation of prokaryotes: factors that affect biolistic transformation of very small cells. | five bacterial species were transformed using particle gun-technology. no pretreatment of cells was necessary. physical conditions (helium pressure, target cell distance and gap distance) and biological conditions (cell growth phase, osmoticum concentration, and cell density) were optimized for biolistic transformation of escherichia coli and these conditions were then used to successfully transform agrobacterium tumefaciens, erwinia amylovora, erwinia stewartii and pseudomonas syringae pv. syri ... | 1992 | 1556553 |
| transcription of the azospirillum brasilense nifh gene is positively regulated by nifa and ntra and is negatively controlled by the cellular nitrogen status. | the expression of a translational azospirillum brasilense nifh-uida fusion was studied in a. brasilense and in rhizobium meliloti strains with mutations in nifa, ntra and ntrc. induction of the fusion was observed in the r. meliloti wild-type and ntrc- strains on incubation under microaerobic conditions but not in the nifa- and ntra- strains, showing the absolute requirement of both sigma 54 and nifa for activation of the nifh promoter. histochemical analysis of the root nodules elicited by r. m ... | 1992 | 1557035 |
| spatial and temporal expression patterns directed by the agrobacterium tumefaciens t-dna gene 5 promoter during somatic embryogenesis in carrot. | we have analysed the patterns of expression of a gene encoding beta-glucuronidase (gus) fused to the promoter of the agrobacterium tumefaciens t-dna gene 5 during embryogenesis in carrot, daucus carota l. gene expression was monitored by a histochemical assay of beta-glucuronidase activity. the gene 5 promoter, although of bacterial origin, conferred expression upon the marker gene in all stages of embryo development. the patterns of expression however, differed between embryos in different stag ... | 1992 | 1558941 |
| nucleotide sequence of the rhizobium meliloti nodl gene located in locus n5 of the nod regulon. | | 1992 | 1558960 |
| suppression of the ndv mutant phenotype of rhizobium meliloti by cloned exo genes. | the ndva and ndvb genes of rhizobium meliloti are involved in the export and synthesis, respectively, of the small cyclic polysaccharide beta(1,2)glucan. we have previously shown that spontaneous symbiotic pseudorevertants of ndv mutants do not produce periplasmic beta(1,2)glucan. here we show that the pseudorevertants also do not produce extracellular beta(1,2)glucan, but do show alterations in the amount of the major acidic exopolysaccharide produced. this exopolysaccharide is not detectably d ... | 1992 | 1560776 |
| evolution of regulation of steroid-mediated intercellular communication in vertebrates: insights from flavonoids, signals that mediate plant-rhizobia symbiosis. | various flavonoids, such as genistein, luteolin, and coumestrol, have actions in mammals that are mediated by binding either to classical estrogen receptors or to type ii receptors, which also bind estrogen. these actions are of intense interest because they may be the basis for the protective actions of plants against certain cancers, such as breast cancer. the biological activity of flavonoids in mammals raises some questions. is the hormonal action of flavonoids "an accident" derived from the ... | 1992 | 1562508 |
| 3-oxoacyl-[acp] reductase from oilseed rape (brassica napus). | 3-oxoacyl-[acp] reductase (e.c. 1.1.1.100, alternatively known as beta-ketoacyl-[acp] reductase), a component of fatty acid synthetase has been purified from seeds of rape by ammonium sulphate fractionation, procion red h-e3b chromatography, fplc gel filtration and high performance hydroxyapatite chromatography. the purified enzyme appears on sds-page as a number of 20-30 kda components and has a strong tendency to exist in a dimeric form, particularly when dithiothreitol is not present to reduc ... | 1992 | 1562581 |
| molecular cloning of higher-plant 3-oxoacyl-(acyl carrier protein) reductase. sequence identities with the nodg-gene product of the nitrogen-fixing soil bacterium rhizobium meliloti. | cdna clones encoding the fatty-acid- biosynthetic enzyme nadph-linked 3-oxoacyl-(acyl carrier protein) (acp) reductase were isolated from a brassica napus (rape) developing seed library and from an arabidopsis thaliana (thale cress) leaf library. the n-terminal end of the coding region shows features typical of a stromal-targeting plastid-transit peptide. the deduced amino acid sequences have 41% and 55% identity respectively with the nodg-gene product of rhizobium meliloti, one of the host-spec ... | 1992 | 1575676 |
| exogenous suppression of the symbiotic deficiencies of rhizobium meliloti exo mutants. | the acidic exopolysaccharide (eps i) produced by rhizobium meliloti during symbiosis with medicago sativa has been shown to be required for the proper development of nitrogen-fixing nodules. cloned dna from the exo region of r. meliloti is shown to stimulate production of the low-molecular-weight form of this exopolysaccharide, and in this report we show that the symbiotic deficiencies of two exo mutants of r. meliloti, the exoa and exoh mutants, can be rescued by the addition of this low-molecu ... | 1992 | 1577707 |
| two-way chemical signaling in agrobacterium-plant interactions. | the discovery in 1977 that agrobacterium species can transfer a discrete segment of oncogenic dna (t-dna) to the genome of host plant cells has stimulated an intense interest in the molecular biology underlying these plant-microbe associations. this attention in turn has resulted in a series of insights about the biology of these organisms that continue to accumulate at an ever-increasing rate. this excitement was due in part to the notion that this unprecedented interkingdom dna transfer could ... | 1992 | 1579105 |
| self-splicing introns in trna genes of widely divergent bacteria. | the organization of eukaryotic genes into exons separated by introns has been considered as a primordial arrangement but because it does not exist in eubacterial genomes it may be that introns are relatively recent acquisitions. a self-splicing group i intron has been found in cyanobacteria at the same position of the same gene (that encoding leucyl transfer rna, uaa anticodon) as a similar group i intron of chloroplasts, which indicates that this intron predates the invasion of eukaryotic cells ... | 1992 | 1579169 |
| expression of a chimaeric heat-shock-inducible agrobacterium 6b oncogene in nicotiana rustica. | the t-6b gene of agrobacterium tumefaciens strain tm4 induces tumours on nicotiana rustica by an as yet unknown mechanism. these tumours cannot be regenerated into normal plants. to study the effect of the t-6b gene product on normal plant cells, the t-6b gene was placed under control of the drosophila melanogaster hsp70 heat-shock promoter and introduced into n. rustica. progeny of an hsp70-t-6b transformant developed into normal plants. the inducibility of the hsp70-t-6b construct was shown by ... | 1992 | 1581569 |
| the fixl protein of rhizobium meliloti can be separated into a heme-binding oxygen-sensing domain and a functional c-terminal kinase domain. | transcription of nitrogen fixation (nif and fix) genes in rhizobium meliloti is induced by a decrease in oxygen concentration. the products of two genes, fixl and fixj, are responsible for sensing and transmitting the low-oxygen signal. the proteins encoded by fixl and fixj (fixl and fixj, respectively) are homologous to a family of bacterial proteins that transduce environmental signals through a common phosphotransfer mechanism [david, m., daveran, m., batut, j., dedieu, a., domergue, o., ghai ... | 1992 | 1584762 |
| the a. tumefaciens transcriptional activator occr causes a bend at a target promoter, which is partially relaxed by a plant tumor metabolite. | octopine is released from crown gall tumors as a nutrient source and a signal molecule for the plant pathogen agrobacterium tumefaciens. some or all octopine-inducible genes are regulated by a protein called occr. primer extension analysis showed that occr protein represses the occr gene and both represses and activates the occq operon, which is divergently transcribed from occr. these promoters initiate transcription 46 bp apart. this regulatory system was reconstituted in vitro using purified ... | 1992 | 1586946 |
| region-directed mutagenesis of residues surrounding the active site nucleophile in beta-glucosidase from agrobacterium faecalis. | the active site nucleophile of the beta-glucosidase of agrobacterium faecalis has recently been identified by the use of inhibitors. a combination of site-directed and in vitro enzymatic mutagenesis was carried out on the beta-glucosidase to probe the structure of the active site region. forty-three point mutations were generated at 22 different residues in the region surrounding the active site nucleophile, glu358. only five positions were identified which affected enzyme activity indicating th ... | 1992 | 1587814 |
| [the importance of antibiotic resistant mutants of rhizobium and their uses in ecology]. | almost all aspects of research into the ecology of rhizobia rests on the recognition of the strains. marker techniques can be conveniently grouped into the three categories (a) those based on serological differences, (b) genetic markers, and (c) other natural markers. in this article, the genetically marked strains of rhizobia and their use in the ecology will be discussed. | 1992 | 1588855 |
| delta-aminolevulinate uptake by rhizobium bacteroids and its limitation by the peribacteroid membrane in legume nodules. | heme is overproduced during rhizobium-legume symbiosis and delta-aminolevulinate (ala) is a common precursor in both bacterial and plant synthesis pathways of this molecule. ala uptake by bacteroids from french bean and soybean nodules was characterized. the action of several metabolic inhibitors and the competition effect of malate on this uptake were studied. ala transport appeared to be mediated by the dicarboxylate carrier system. purified symbiosomes--bacteroids surrounded by the peribacter ... | 1992 | 1590795 |
| yeast flavohemoglobin is an ancient protein related to globins and a reductase family. | the hemoglobin of yeast is a two-domain protein with both heme and flavin prosthetic groups. the nucleotide sequences of the cdna and genomic dna encoding the protein from saccharomyces cerevisiae show that introns are absent and that both domains are homologous with a flavoheme protein from escherichia coli. the heme domains are also homologous with those of o2-binding heme proteins from several other distantly related bacteria, plants, and animals; all appear to be members of the same globin s ... | 1992 | 1594608 |
| exopolysaccharides from rhizobium meliloti ye-2 grown under different osmolarity conditions: viscoelastic properties. | the exopolysaccharides fro rhizobium meliloti ye-2 extracted 10 days after the inoculum from culture broths and having different osmolarity values (0, 0.2, 0.4, and 0.6 m) have been investigated by means of oscillatory and steady-shear measurements on 1% solutions in 0.1m nacl. the micro-organism produces a mixture of a galactoglucan and a succinoglycan. at low osmolarity (0 and 0.2m), the main fraction consists of galactoglucan and the viscoelastic properties of the mixture are typical of an en ... | 1992 | 1596921 |
| role of divalent cations in the subunit associations of complex flagella from rhizobium meliloti. | rhizobium meliloti, a symbiotic, nitrogen-fixing soil bacterium with complex flagella, as well as other members of the family rhizobiaceae, rapidly lost motility when suspended in buffers lacking divalent cations but retained good motility in buffers containing calcium, magnesium, barium, or strontium. loss of motility was associated with loss of flagella from the cells. analysis of flagella by sedimentation, gel electrophoresis, and electron microscopy revealed that removal of divalent cations ... | 1992 | 1597412 |
| molecular characterization and regulation of the rhizosphere-expressed genes rhiabcr that can influence nodulation by rhizobium leguminosarum biovar viciae. | a group of four rhi (rhizosphere-expressed) genes from the symbiotic plasmid of rhizobium leguminosarum biovar viciae has been characterized. although mutation of the rhi genes does not normally affect nodulation, in the absence of the closely linked nodulation genes nodfel, mutations in the rhi genes can influence the nodulation of the vetch vicia hirsuta. the dna sequence of the rhi gene region reveals four large open reading frames, three of them constituting an operon (rhiabc) transcribed co ... | 1992 | 1597418 |
| analysis of mutations in trfa, the replication initiation gene of the broad-host-range plasmid rk2. | plasmids with mutations in trfa, the gene encoding the replication initiation protein of the broad-host-range plasmid rk2, were isolated and characterized. mutants identified from a nitrosoguanidine bank were defective in supporting the replication of a wild-type rk2 origin in escherichia coli. most of the mutations were clustered in a region of trfa corresponding to the carboxy-terminal quarter of the trfa protein. 5' and 3' deletion mutants of trfa were also constructed. a c-terminal deletion ... | 1992 | 1597426 |
| mutational analysis of the rhizobium meliloti nifa promoter. | the nifa gene of rhizobium meliloti, the bacterial endosymbiont of alfalfa, is a regulatory nitrogen fixation gene required for the induction of several key nif and fix genes. transcription of nifa is strongly induced in planta and under microaerobic conditions ex planta. induction of nifa, in turn, is positively controlled by the fixl and fixj genes of r. meliloti, the sensor and regulator, respectively, of a two-component system responsible for oxygen sensing by this bacterium. this system is ... | 1992 | 1597427 |
| nucleotide sequence and characterization of four additional genes of the hydrogenase structural operon from rhizobium leguminosarum bv. viciae. | the nucleotide sequence of a 2.5-kbp region following the hydrogenase structural genes (hupsl) in the h2 uptake gene cluster from rhizobium leguminosarum bv. viciae upm791 was determined. four closely linked genes encoding peptides of 27.9 (hupc), 22.1 (hupd), 19.0 (hupe), and 10.4 (hupf) kda were identified immediately downstream of hupl. proteins with comparable apparent molecular weights were detected by heterologous expression of these genes in escherichia coli. the six genes, hups to hupf, ... | 1992 | 1597428 |
| constitutive mutations of agrobacterium tumefaciens transcriptional activator virg. | the virulence (vir) genes of agrobacterium tumefaciens ti plasmids are positively regulated by virg in conjunction with vira and plant-derived inducing molecules. a procedure that utilizes both genetic selection and a genetic screen was developed to isolate mutations in virg that led to elevated levels of vir gene expression in the absence of vira and plant phenolic inducers. mutants were isolated at a frequency of 1 in 10(7) to 10(8). substitution mutations at two positions in the virg coding r ... | 1992 | 1597431 |
| agrobacterium and plant genetic engineering. | | 1992 | 1600167 |
| developmental aspects of the rhizobium-legume symbiosis. | | 1992 | 1600171 |
| detection and separation of rhizobium and bradyrhizobium nod metabolites using thin-layer chromatography. | using radioactive acetate as a precursor, it was shown that the common nodabc genes of rhizobium and bradyrhizobium strains are involved in the production of one or more metabolites that are excreted into the growth medium. a rapid thin-layer chromatography (tlc) system has been developed to separate these so-called nod metabolites that can then be visualized by autoradiography. different patterns of nod metabolites were observed in the tested strains of the cross-inoculation groups of r. legumi ... | 1992 | 1600238 |
| rhizobium leguminosarum has two glucosamine synthases, glms and nodm, required for nodulation and development of nitrogen-fixing nodules. | the rhizobium leguminosarum nodm gene product shows strong homology to the escherichia coli glms gene product that catalyses the formation of glucosamine 6-p from fructose 6-p and glutamine. dna hybridization with nodm indicated that, in addition to nodm on the symbiotic plasmid, another homologous gene was present elsewhere in the r. leguminosarum genome. a glucosamine-requiring mutant was isolated and its auxotrophy could be corrected by two different genetic loci. it could grow without glucos ... | 1992 | 1602964 |
| identification of a nodd-like gene in frankia by direct complementation of a rhizobium nodd-mutant. | clones from a frankia at4 gene bank were pooled into groups and mass conjugated into a nodd mutant of rhizobium leguminosarum bv. viciae by triparental matings. when peas were inoculated with the pooled transconjugants, nodulation was observed. a plasmid, pat2gx containing frankia dna, was isolated from bacteria recovered from these nodules. this plasmid was shown to complement a nodd mutant of r. leguminosarum bv. viciae. thus pat2gx contains a frankia gene that is functionally equivalent to no ... | 1992 | 1603071 |
| functional analysis of the cysteine motifs in the ferredoxin-like protein fdxn of rhizobium meliloti involved in symbiotic nitrogen fixation. | the rhizobium meliloti fdxn gene, which is part of the nifa-nifb-fdxn operon, is absolutely required for symbiotic nitrogen fixation. the deduced sequence of the fdxn protein is characterized by two cysteine motifs typical of bacterial-type ferredoxins. the fix-phenotype of an r. meliloti fdxn::[tc] mutant could be rescued by the r. leguminosarum fdxn gene, whereas no complementation was observed with nif-associated genes encoding ferredoxins from bradyrhizobium japonicum, azotobacter vinelandii ... | 1992 | 1603075 |
| [mechanism of t-dna integration into plant genomes and trial of plant gene targeting]. | | 1992 | 1603947 |
| specific oligosaccharide form of the rhizobium meliloti exopolysaccharide promotes nodule invasion in alfalfa. | rhizobium meliloti strain su47 produces both high molecular weight (hmw) and low molecular weight (lmw) forms of an acidic exopolysaccharide, succinoglycan. genetic studies have shown that succinoglycan is required for alfalfa root nodule invasion. we found that lmw succinoglycan, when applied exogenously to alfalfa roots, restored nodule invasion to exoa, exob, exof, and exoh mutants. nodule initiation signals were not involved, since lmw succinoglycan from r. meliloti nodd1d2d3 and noda mutant ... | 1992 | 1608972 |
| influence of metribuzin on the rhizobium leguminosarum--lentil (lens culinaris) symbiosis. | the effects of the triazine herbicide metribuzin (sencor) on the lentil (lens culinaris medic.) - rhizobium leguminosarum biovar viciae symbiosis were studied in leonard jars and growth pouches. lentils inoculated with rhizobium leguminosarum strain 128c54 or 128c84, and noninoculated lentils grown in plant nutrient solution supplemented with 5 mm kno3, had metribuzin applied to the plants at either 8 or 13 days after planting. when sprayed at 8 days, metribuzin had a significant (p less than or ... | 1992 | 1611561 |
| rhizobium--plant signal exchange. | initial stages in the rhizobium-legume symbiosis can be thought of as a reciprocal molecular conversation: transmission of a gene inducer from legume host to bacterium, with ensuing bacterial synthesis of a morphogen that is transmitted to the plant, switching the developmental fate of the legume root. these signal molecules have a key role in determining bacterium-host specificity and the purified nod factor compounds provide useful new tools to probe plant cell function. | 1992 | 1614514 |
| nuclear localization of agrobacterium vire2 protein in plant cells. | the agrobacterium single-stranded dna (ssdna) intermediate t-strand is likely transferred to the plant cell nucleus as a complex with a single vird2 molecule at its 5' end and multiple vire2 molecules along its length. vird2 contains a nuclear localization signal (nls); however, because the t-strand is principally coated with vire2 molecules, vire2 also might assist in nuclear uptake. indeed, vire2 fused to a reporter protein localizes to plant cell nuclei, a process mediated by two amino acid s ... | 1992 | 1615325 |
| two c4-dicarboxylate transport systems in rhizobium sp. ngr234: rhizobial dicarboxylate transport is essential for nitrogen fixation in tropical legume symbioses. | to investigate the role of dicarboxylate transport in nitrogen-fixing symbioses between rhizobium and tropical legumes, we made a molecular genetic analysis of the bacterial transport system in rhizobium sp. ngr234. this braod host range strain fixes nitrogen in association with evolutionarily divergent legumes. two dicarboxylate transport systems were cloned from rhizobium ngr234. one locus was chromosomally located, whereas the other was carried on the symbiotic plasmid (psym) and contained a ... | 1992 | 1617199 |
| cell-associated pectinolytic and cellulolytic enzymes in rhizobium leguminosarum biovar trifolii. | the involvement of rhizobium enzymes that degrade plant cell wall polymers has long been an unresolved question about the infection process in root nodule symbiosis. here we report the production of enzymes from rhizobium leguminosarum bv. trifolii that degrade carboxymethyl cellulose and polypectate model substrates with sensitive methods that reliably detect the enzyme activities: a double-layer plate assay, quantitation of reducing sugars with a bicinchoninate reagent, and activity gel electr ... | 1992 | 1622257 |
| hyperreiterated dna regions are conserved among bradyrhizobium japonicum serocluster 123 strains. | we have identified and cloned two dna regions which are highly reiterated in bradyrhizobium japonicum serocluster 123 strains. while one of the reiterated dna regions, pfr2503, is closely linked to the b. japonicum common and genotype-specific nodulation genes in strain usda 424, the other, pmap9, is located next to a tn5 insertion site in a host-range extension mutant of b. japonicum usda 438. the dna cloned in pfr2503 and pmap9 are reiterated 18 to 21 times, respectively, in the genomes of b. ... | 1992 | 1622264 |
| molecular basis for novel root phenotypes induced by agrobacterium rhizogenes a4 on cucumber. | we have used the wild-type agrobacterium rhizogenes strain a4 to induce roots on cucumber stem explants. cultures of transformed roots obtained that were capable of hormone-autonomous growth could be grouped in three phenotypic classes. of particular interest were extremely thick roots of a type not previously described. characterization of the transferred dna and of the expression of the corresponding genes allowed us to determine that the genes rolabc of the tl region of the ri plasmid are suf ... | 1992 | 1623191 |
| molecular cloning of a cdna encoding aspartate aminotransferase-p2 from lupin root nodules. | two isoenzymic forms of aspartate aminotransferase are present in the plant fraction of developing lupin root nodules. one of these forms, aspartate aminotransferase-p2 (aat-p2), increases dramatically with the onset of biological nitrogen fixation and is associated with the assimilation of ammonia by the plant in the rhizobium-legume symbiosis. a day 18 lupin nodule cdna library in the lambda zapii vector was immunoscreened with a monoclonal antibody specific for aat-p2 and yielded two near-ful ... | 1992 | 1623192 |
| transgenic medicinal plants: agrobacterium-mediated foreign gene transfer and production of secondary metabolites. | agrobacterium-ti/ri plasmids are natural gene vectors, by which a number of attempts have been made in genetic engineering of secondary metabolism in pharmaceutically important plants in the last few years. opines are biosynthesized by transformed crown galls and hairy roots integrated with t-dnas of ti/ri plasmids. these opines are classified into five families according to their structures and biogenesis. the production of opines is a natural example of genetic engineering of the biosynthetic ... | 1992 | 1624938 |
| molecular genetic analysis of the rhizobium meliloti fixk promoter: identification of sequences involved in positive and negative regulation. | transcription of the rhizobium meliloti fixk gene is induced in symbiotic and microaerobic growth conditions by the fixl/fixj modulator/effector pair. transcription of fixk is also negatively autoregulated. by 5' deletion analysis, the involvement in negative regulation of a dna region between -514 and -450 with respect to the transcription start was demonstrated. site-directed mutagenesis allowed us to show that a sequence homologous to the binding site of the escherichia coli fnr protein, cent ... | 1992 | 1625575 |
| mutational analysis of the 'conserved region' of maize streak virus suggests its involvement in replication. | maize streak virus as well as other geminiviruses contain a potential hairpin structure with the conserved sequence taatattac in the loop. we assessed the possible involvement of this structure in replication and symptom induction of the virus. a series of insertion and deletion mutants were analyzed by agroinfection. deletion of the hairpin or insertions in the conserved sequence abolished symptom development. viral dna could not be detected in the infected tissue. however, a mutant with a poin ... | 1992 | 1627773 |
| the agrobacterium tumefaciens vird3 gene is not essential for tumorigenicity on plants. | genetic studies indicate that three of the four polypeptides encoded within the vird operon of the agrobacterium tumefaciens ti plasmid are essential for virulence. in order to determine whether the fourth polypeptide, vird3, has any role in virulence, complementation analysis was used. an a. tumefaciens strain, a348 delta d, which lacked the entire vird operon in the ti plasmid ptia6, was constructed. plasmids containing defined regions of the vird operon were introduced into this strain, and v ... | 1992 | 1629176 |
| molecular analysis of the lac operon encoding the binding-protein-dependent lactose transport system and beta-galactosidase in agrobacterium radiobacter. | the genes coding for the binding-protein-dependent lactose transport system and beta-galactosidase in agrobacterium radiobacter strain ar50 were cloned and partially sequenced. a novel lac operon was identified which contains genes coding for a lactose-binding protein (lace), two integral membrane proteins (lacf and lacg), an atp-binding protein (lack) and beta-galactosidase (lacz). the operon is transcribed in the order lacefgzk. the operon is controlled by an upstream regulatory region contain ... | 1992 | 1630315 |
| structure of the acidic exopolysaccharide secreted by rhizobium leguminosarum biovar. phaseoli cfn42. | | 1992 | 1633602 |
| use of repetitive (repetitive extragenic palindromic and enterobacterial repetitive intergeneric consensus) sequences and the polymerase chain reaction to fingerprint the genomes of rhizobium meliloti isolates and other soil bacteria. | the distribution of dispersed repetitive dna (repetitive extragenic palindromic [rep] and enterobacterial repetitive intergenic consensus [eric]) sequences in the genomes of a number of gram-negative soil bacteria was examined by using conserved primers corresponding to rep and eric sequences and the polymerase chain reaction (pcr). the patterns of the resulting pcr products were analyzed on agarose gels and found to be highly specific for each strain. the rep and eric pcr patterns of a series o ... | 1992 | 1637156 |
| combined subtraction hybridization and polymerase chain reaction amplification procedure for isolation of strain-specific rhizobium dna sequences. | a novel subtraction hybridization procedure, incorporating a combination of four separation strategies, was developed to isolate unique dna sequences from a strain of rhizobium leguminosarum bv. trifolii. sau3a-digested dna from this strain, i.e., the probe strain, was ligated to a linker and hybridized in solution with an excess of pooled subtracter dna from seven other strains of the same biovar which had been restricted, ligated to a different, biotinylated, subtracter-specific linker, and am ... | 1992 | 1637166 |
| vectors for plant transformation and cosmid libraries. | a series of vectors has been constructed for the purpose of introducing cloned dnas into plant genomes, using agrobacterium tumefaciens-mediated transformation methods. one of these vectors, pcit20, is a plasmid that contains a multiple cloning site (mcs), and a marker (hph) that confers hygromycin resistance to plant cells. the others are all cosmid vectors which allow insertion of up to 46 kb of plant genomic dna, and which also contain all of the necessary sequences for a. tumefaciens-mediate ... | 1992 | 1639265 |
| regulation of lysine synthesis in transgenic potato plants expressing a bacterial dihydrodipicolinate synthase in their chloroplasts. | the essential amino acid lysine is synthesized in higher plants by a complex pathway that is predominantly regulated by feedback inhibition of two enzymes, namely aspartate kinase (ak) and dihydrodipicolinate synthase (dhps). although dhps is thought to play a major role in this regulation, the relative importance of ak is not known. in order to study this regulation, we have expressed in the chloroplasts of transgenic potato plants a dhps derived from escherichia coli at a level 50-fold above t ... | 1992 | 1643284 |
| regulation of nodulation gene expression by nodd in rhizobia. | | 1992 | 1644745 |
| different plasmids of rhizobium leguminosarum bv. phaseoli are required for optimal symbiotic performance. | rhizobium leguminosarum bv. phaseoli cfn42 contains six plasmids (pa to pf), and pd has been shown to be the symbiotic plasmid. to determine the participation of the other plasmids in cellular functions, we used a positive selection scheme to isolate derivatives cured of each plasmid. these were obtained for all except one (pe), of which only deleted derivatives were recovered. in regard to symbiosis, we found that in addition to pd, pb is also indispensable for nodulation, partly owing to the p ... | 1992 | 1644746 |
| 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 |
| nolc, a rhizobium fredii gene involved in cultivar-specific nodulation of soybean, shares homology with a heat-shock gene. | rhizobium fredii strain usda257 does not nodulate soybean (glycine max (l.) merr.) cultivar mccall. mutant 257dh5, which contains a tn5 insert in the bacterial chromosome, forms nodules on this cultivar, but acetylene-reduction activity is absent. we have sequenced the region corresponding to the site of tn5 insertion in this mutant and find that it lies within a 1176bp open reading frame that we designate nolc. nolc encodes a protein of deduced molecular weight 43564. nucleotide sequences homol ... | 1991 | 1646377 |
| polypeptide composition of bacterial cyclic diguanylic acid-dependent cellulose synthase and the occurrence of immunologically crossreacting proteins in higher plants. | to comprehend the catalytic and regulatory mechanism of the cyclic diguanylic acid (c-di-gmp)-dependent cellulose synthase of acetobacter xylinum and its relatedness to similar enzymes in other organisms, the structure of this enzyme was analyzed at the polypeptide level. the enzyme, purified 350-fold by enzyme-product entrapment, contains three major peptides (90, 67, and 54 kda), which, based on direct photoaffinity and immunochemical labeling and amino acid sequence analysis, are constituents ... | 1991 | 1647035 |
| ndvf, a novel locus located on megaplasmid prmesu47b (pexo) of rhizobium meliloti, is required for normal nodule development. | rhizobium meliloti strains carrying either of two overlapping deletions (delta 5408 and delta f114) of the megaplasmid prmesu47b form nodules on alfalfa which fail to fix n2 (fix-). strains carrying these deletions also fail to fluoresce on media containing calcofluor, indicating a defect in synthesis of the acidic exopolysaccharide (exo-) of r. meliloti. we have isolated cosmid clones (pth21 and pth22) which complement the fix- but not the exo- phenotype of the strains carrying the delta 5408 a ... | 1991 | 1648074 |
| [site-specific restriction endonuclease rme211 from rhizobium meliloti]. | a new site-specific restriction endonuclease rme211 from rhizobium meliloti has been shown to recognize the following nucleotide sequence 5'-atcgat-3' in the double-stranded dna. thus, the enzyme is a true isoschizomer for restriction endonucleases bsu151 and clai. | 1991 | 1649968 |
| 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 |
| 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 |
| cloning and characterization of a rhizobium meliloti homolog of the escherichia coli cell division gene ftsz. | the ftsz gene is essential for initiation of cell division in escherichia coli and bacillus subtilis. to begin our studies of division arrest during differentiation of rhizobium meliloti bacteroids, we isolated a r. meliloti ftsz homolog, ftszrm. degenerate primers directed towards a conserved region of ftsz were used to amplify a segment of r. meliloti dna by polymerase chain reaction, and the product of this reaction was then used to isolate positive clones from a bacteriophage library. the dn ... | 1991 | 1653222 |
| strong negative and positive regulatory elements contribute to the high-level fruit-specific expression of the tomato 2a11 gene. | fruit-specific expression of beta-glucuronidase (gus) activity was produced in transgenic tomato plants when the gus-coding region was flanked by 5' and 3' regions of the tomato 2a11 gene. deletion studies on the 5' region revealed a number of strong regulatory elements involved in the proper expression of the 2a11 gene. a 4.0 kb and a 1.3 kb 5' region can confer high-level fruit-specific gus expression, while a 1.8 kb 5' region produces no gus activity in leaf or fruit tissue. thus, a strong ne ... | 1991 | 1655112 |
| detection of gene regulatory signals in plants revealed by t-dna-mediated fusions. | a binary vector, pprf120, was designed to detect t-dna insertions within transcriptionally active areas of the plant genome. linked to the right-border repeat, the vector contains a promoterless beta-glucuronidase (gus) gene which can, upon integration into chromosomes, be activated by cis-acting regulatory elements. the vector also incorporates a chimeric marker gene conferring resistance to kanamycin to ensure recovery of gene fusions regardless of the extent of their tissue-specific or develo ... | 1991 | 1655114 |
| 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 |
| 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 |
| novel dna structures resulting from dtam3 excision in tobacco. | a tam3 two-element system has been designed by combining an immobilized tam3 element with a non-autonomous dtam3 element inserted into the hpt gene. the phenotypic assay employed, restored hygromycin resistance, indicated that trans-activation of the non-autonomous dtam3 element occurred. molecular analyses of the excision sites revealed that the ends of the dtam3 element remain in the empty donor sites. the predominant consequence of this type of excision appears to be that excised fragments fa ... | 1991 | 1657245 |
| 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 |
| genetic analysis of agrobacterium. | | 1991 | 1658565 |
| genetic techniques in rhizobium meliloti. | | 1991 | 1658566 |
| gene transfer with subsequent removal of the selection gene from the host genome. | a general method of gene transfer that does not leave behind a selectable marker in the host genome is described. a luciferase gene was introduced into the tobacco genome by using the hygromycin phosphotransferase gene (hpt) as a linked selectable marker. flanked by recombination sites from the bacteriophage p1 cre/lox recombination system, the hpt gene was subsequently excised from the plant genome by the cre recombinase. the cre-catalyzed excision event in the plant genome was precise and cons ... | 1991 | 1660141 |