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biotechnological applications of plant cells in culture.for many workers, the most exciting recent advances in the realm of plant cell biotechnology, center on results obtained from experiments concerned with the genetic engineering of plant cells. various groups of workers have managed to introduce new genetic material into plant cells, using ti-plasmids (or modified ti-plasmids) from agrobacterium tumefaciens. this genetic material has been expressed (with varying degrees of efficiency), in each case. thus the way may possibly be coming clear to pr ...198514541777
electric field mediated stable transformation of carrot protoplasts with naked dna.we have developed an electroporation procedure for the transformation of carrot protoplasts with ti-plasmid dna from agrobacterium tumefaciens. the uptake of ptic58 into carrot protoplasts was mediated by high voltage electrical pulses at field strengths from 0.5 to 3.8 kv/cm. protoplast regeneration, somatic embryogenesis and plantlet regeneration were unaffected by the electroporation conditions selected for dna uptake. uptake of plasmid ptic58 resulted in hormone independent regeneration of c ...198524254082
brassica grown gall tumourigenesis and in vitro of transformed tissue.a number of brassica species and cultivars were tested and found to be highly susceptible to crown gall induction by both nopaline and octopine strains of agrobacterium tumefaciens. only b. napus did not form tumours when inoculated with octopine strains. seedlings of very young plants were poor hosts but efficient infection occurred after 8-10 weeks of growth. teratomas arising on tumours in planta were relatively frequent on induction with nopaline strains. axenically cultured tumour calli of ...198524254075
genetic manipulation in cultivars of oilseed rape (brassica napus) using agrobacterium.the response of oilseed rape cultivars to infection with agrobacterium tumefaciens and a. rhizogenes and the possibility of regenerating genetically transformed oilseed rape plants were examined. the frequency at which agrobacterium induced galls or hairy-roots on in vitro cultured plants ranged from 10% to 70%, depending on the cultivar. from galls induced by the tumorigenic strain t37, known to be strongly shoot inducing on tobacco, roots developed frequently. occasionally, shoots formed and s ...198524247402
the role of bacterial attachment in the transformation of cell-wall-regenerating tobacco protoplasts by agrobacterium tumefaciens.the presence of a newly formed primary cell wall was shown to be required for attachment and subsequent transformation of tobacco leaf protoplasts by agrobacterium tumefaciens in cocultivation experiments. in these experiments both protoplasts at different stages after their isolation and cell-wall inhibitors were used. the specificity of agrobacterium attachment was shown by using other kinds of bacteria that did not attach. by diminishing the concentration of divalent cations using ethylenedia ...198524241510
transformation of protoplast-derived cell colonies and suspension cultures by agrobacterium tumefaciens.in this paper we describe procedures for transforming micro colonies derived from mesophyll protoplasts of petunia hybrida with agrobacterium tumefaciens. the method is efficient, up to 70% of the colonies were transformed, and we used a similar method to transform cells from a suspension culture of haploid nicotiana plumbaginifolia.198524253882
structure and expression of dna transferred to tobacco via transformation of protoplasts with ti-plasmid dna: co-transfer of t-dna and non t-dna sequences.the t-dna structure and organization in tissues obtained via transformation of tobacco protoplasts with ti-plasmid dna was found to be completely different from the t-dna introduced via agrobacterium tumefaciens. it is often fragmented. overlapping copies of t-dna, having various sizes, as well as separated fragments of t-dna were detected. the border sequences of 23 basepairs (bp), flanking the t-region in the ti-plasmid as direct repeats are not used as preferred sequences for integration. sim ...198524306763
resistance to hygromycin b : a new marker for plant transformation studies.a bacterial gene encoding hygromycin phosphotransferase has been modified for expression in tobacco cells. the aphiv gene from escherichia coli was inserted between the 5' sequence of an octopine synthase gene and the 3' sequence from a nopaline synthase gene. the new gene was incorporated between t-dna border fragments in the broad-host-range vector pkt210 to form a micro-ti plasmid. agrobacterium tumefaciens containing this plasmid and a ti plasmid as helper was used to incite crown gall tumor ...198524306569
overdrive, a t-dna transmission enhancer on the a. tumefaciens tumour-inducing plasmid.during crown gall tumorigenesis a specific segment of the agrobacterium tumefaciens tumour-inducing (ti) plasmid, the t-dna, integrates into plant nuclear dna. similar 23-bp direct repeats at each end of the t region signal t-dna borders, and t-dna transmission (transfer and integration) requires the right-hand direct repeat. a chemically synthesized right border repeat in its wild-type orientation promotes t-dna transmission at a low frequency; ti plasmid sequences which normally flank the righ ...198615966101
stimulation of agrobacterium tumefaciens growth by azotobacter vinelandii ferrisiderophores.azotobacter vinelandii stimulated the growth of agrobacterium tumefaciens h2, h23, h24, h27, and atcc 15955 on media containing insoluble iron sources. the azotobacter vinelandii siderophores appeared to promote agrobacterium tumefaciens growth by solubilizing mineral iron, and the ferrisiderophores so formed then acted as iron sources for agrobacterium tumefaciens. agrobactin, the agrobacterium siderophore, appeared to be inefficient in solubilizing mineral iron directly.198616347002
adsorption of agrobacterium tumefaciens to susceptible potato tissues: a physisorption process.adsorption of agrobacterium tumefaciens cells to potato tuber disks reached equilibrium after coincubation for about 30 min. more than 10% of the number of bacteria bound at equilibrium were adsorbed within 30 s. adsorption isotherms obtained at three temperatures showed that the heat of adsorption was nearly zero.198616347060
agrocin-producing agrobacterium tumefaciens strain active against grapevine isolates.agrobacterium tumefaciens j73, a biotype 2 strain harboring a nopaline ti plasmid, was found to produce an agrocin active against a broad range of a. tumefaciens strains, including grapevine isolates. sensitivity to j73 is not encoded by a ti plasmid. optimal conditions for the production of the agrocin were determined.198616347112
susceptibility of agrobacterium tumefaciens strains to two agrocin-producing agrobacterium strains.sixty-five strains and isolates of agrobacterium tumefaciens representing each of the known biotypes, were tested for in vitro and in vivo susceptibility to the agrocin-producing strains agrobacterium radiobacter 84 and a. tumefaciens d286. no biotype 3 strain was susceptible to the effects of either of the agrocinogenic strains in vitro. on datura and tobacco, the best inhibition of tumor formation was obtained when the agrocinogenic strains were applied to wounds 24 h before the pathogens and ...198616347122
host-symbiont specificity expressed during early adsorption of rhizobium meliloti to the root surface of alfalfa.early (4 h) adsorption of rhizobium meliloti l5-30 in low numbers to alfalfa roots in mineral solution was examined for competition with other bacterial strains. all tested competitor strains decreased the adsorption of l5-30 by extents which depended on the strain and its concentration. the decrease of adsorption by r. meliloti competitors (all of them infective in alfalfa) was nearly complete at saturation (97 to 99% decrease). all other heterologous rhizobia and agrobacterium tumefaciens at s ...198616347138
long-term storage of plant-pathogenic bacteria in sterile distilled water.this study was made to determine the effectiveness of the preservation of plant-pathogenic bacteria in sterile distilled water. after 20 or 24 years of storage in distilled water, a very high percentage (90 to 92%) of the isolates of agrobacterium tumefaciens and pseudomonas spp. were still alive. moreover, 12 of 13 viable (after 24 years) isolates of p. syringae subsp. syringae maintained their ability to produce syringomycin and were pathogenic to bean seedlings. the water-stored cells of two ...198616347141
recombination in a plant virus: template-switching in cauliflower mosaic virus.a hybrid plasmid, containing tandemly arranged pieces of two different but well-defined cauliflower mosaic virus (camv) genomes, was used to study the mechanism by which infectious viral dna can escape from transforming dna. systemic viral infection followed inoculation of brassica plants with a strain of agrobacterium tumefaciens containing the hybrid plasmid in its t-dna. restriction mapping of uncloned viral dna from these plants, and sequencing of relevant portions of cloned viral dna, showe ...198616453678
monocot and dicot pre-mrnas are processed with different efficiencies in transgenic tobacco.a gene encoding the small subunit of ribulose 1,5-bisphosphate carboxylase (rbcs) in wheat, a monocot plant, was transferred to tobacco, a dicot plant. the wheat gene is not expressed in transgenic tobacco under the control of its own promoter, but when transcription is driven by a viral promoter, several wheat transcripts accumulate. these include both spliced and unspliced transcripts, which are polyadenylated at multiple novel sites in the wheat 3' flanking region. another monocot intron, fro ...198616453710
a plant cell factor induces agrobacterium tumefaciens vir gene expression.the virulence genes of agrobacterium are required for this organism to genetically transform plant cells. we show that vir gene expression is specifically induced by a small (<1000 da) diffusible plant cell metabolite present in limiting quantities in the exudates of a variety of plant cell cultures. active plant cell metabolism is required for the synthesis of the vir-inducing factor, and the presence of bacteria does not stimulate this production. vir-inducing factor is (i) heat and cold stabl ...198616593648
developmental regulation of two genes encoding ribulose-bisphosphate carboxylase small subunit in pea and transgenic petunia plants: phytochrome response and blue-light induction.we describe the effects of light quality on the light-induced expression of two genes (rbcs-3a and rbcs-3c) encoding the ribulose-1,5-bisphosphate carboxylase small subunit of pea plants. these two genes exhibit distinctive photoresponses depending on the developmental stages of the leaves. in etiolated primary leaves, changes in the rbcs-3a and rbcs-3c transcript levels are regulated by phytochrome. in mature green leaves, on the other hand, the transcript levels are modulated by a putative blu ...198616593682
"agroinfection," an alternative route for viral infection of plants by using the ti plasmid.most plant viruses are transmitted by insect vectors. we present an alternative method for the introduction of infectious viral dna that uses the ability of agrobacterium to transfer dna from bacterial cells to plants. cauliflower mosaic virus was chosen to develop this method because it is the best characterized plant dna virus and can be introduced into plants via aphids, virus particles, viral dna, or suitably treated cloned dna. we show that systemic infection of turnips results from woundin ...198616593697
rhizobium meliloti genes required for nodule development are related to chromosomal virulence genes in agrobacterium tumefaciens.symbiotically essential genes have been identified in rhizobium meliloti that are structurally and functionally related to chromosomal virulence (chv) genes of agrobacterium tumefaciens. homologous sequences also exist in the genomes of other fast-growing rhizobia including rhizobium trifolii, rhizobium leguminosarum, and rhizobium phaseoli. in agrobacterium, the chva and chvb loci are known to be essential for oncogenic transformation of dicotyledonous plants and for attachment to plant cells [ ...198616593714
rapid assay of foreign gene expression in leaf discs transformed by agrobacterium tumefaciens: role of t-dna borders in the transfer process.we have developed a sensitive leaf disc transformation procedure for studying early and/or transient t-dna expression during agrobacterium tumefaciens-mediated transformation of plant cells. using this system, we have examined the function of t-dna border sequences on the early expression of t-dna genes and on the stable integration of those genes in infected cells. deletion of the right border from the t-dna appears to permit transfer of t-dna genes from the tumor-inducing (ti) plasmid but grea ...198616593716
complementation of agrobacterium tumefaciens tumor-inducing aux mutants by genes from the t(r)-region of the ri plasmid of agrobacterium rhizogenes.in this paper we provide information indicating that the agropine-type root-inducing (ri) plasmid pri1855 of agrobacterium rhizogenes contains functional genes for auxin production (aux) in the right transferred dna (t-dna) region (t(r)-region). these genes were cloned and introduced into the t-region of the tumor-inducing (ti) plasmids of mutants of agrobacterium tumefaciens carrying an aux mutation. depending on the ri aux gene present, the oncogenicity of the ti aux-1 and/or aux-2 mutations w ...198616593762
insertion sequence elements of pseudomonas savastanoi: nucleotide sequence and homology with agrobacterium tumefaciens transfer dna.two types of transposable elements, is51 and is52 (is, insertion sequence), were found in pseudomonas syringae subsp. savastanoi (p. savastanoi) that spontaneously insert into and inactivate iaam; the insertion results in the loss of indoleacetic acid production and attenuation of virulence. the nucleotide sequences of both is elements have sizes and structural features common to other prokaryotic is elements; is51 is 1311 base pairs (bp) long and has terminal inverted repeats of 26 bp; is52 is ...198616593778
the initiation of auxin autonomy in tissue from tobacco plants carrying the auxin biosynthesizing genes from the t-dna of agrobacterium tumefaciens.tobacco (nicotiana tabacum cv havana 425) plants containing the indole-3-acetic acid biosynthesizing genes (1 and 2) from the t-dna of agrobacterium tumefaciens strain t37-adh(2) (mutated at the cytokinin biosynthesis gene 4) were used to study the physiological basis of the suppression and reinitiation of the auxin autonomous phenotype. the plants, though normal in appearance and cross-fertile with nontransformed, wild type tobacco, are shown to contain multiple copies of genes 1 and 2. plants ...198616664572
bound auxin metabolism in cultured crown-gall tissues of tobacco.bound auxin metabolism in cultured crown-gall tumor cells and pith callus of tobacco was examined by feeding radiolabeled auxins and auxin conjugates. in all tissues fed [(14)c]indoleacetic acid (iaa), at least one-third of the iaa was decarboxylated, and most of the remaining radiolabel occurred in a compound(s) which did not release iaa with alkaline hydrolysis. in cells transformed by the a6 strain of agrobacterium tumefaciens, the only detectable iaa conjugate was indole-3-acetylaspartic aci ...198616664620
transformation of tobacco, tomato, potato, and arabidopsis thaliana using a binary ti vector system.using a binary tumor-inducing (ti) plasmid vector system, several plant species were transformed with a kanamycin resistance marker (neomycin phosphotransferase gene). four nicotiana species, seven tomato cultivars, two potato cultivars, and arabidopsis thaliana were transformed by the binary vector transformation method. in this method, various plant organ pieces were co-cultivated with agrobacterium tumefaciens cells carrying the binary vector, pga472, and a helper ti plasmid. we have also dem ...198616664795
development of plant promoter expression vectors and their use for analysis of differential activity of nopaline synthase promoter in transformed tobacco cells.i have developed promoter expression binary vectors based on the tumor-inducing plasmid of agrobacterium tumefaciens to facilitate elucidation of plant gene regulation. promoter activity can be determined by inserting dna fragments into the multiple cloning sites of the vectors forming transcriptional and/or translational fusions between the cat structural gene and an inserted promoter region. the activity of the nopaline synthase (nos) promoter was demonstrated with the vector. however, three a ...198616664813
opine synthesis in wild-type plant tissue.opine production is associated with crown gall tissue, a neoplastic growth caused by infection of dicotyledonous plants with agrobacterium tumefaciens. recent publications have claimed that tissues of certain monocotyledonous plants can also be infected by agrobacterium. following infection, a part of the agrobacterium ti plasmid, t-dna, is integrated into the chromosome of the infected plant. t-dna, which codes for opine-synthesizing enzymes, is now used to add foreign genes to plants. a number ...198616664995
response of various cucurbits to infection by plasmid-harboring strains of agrobacterium.tumor formation in cucurbit cultivars resulting from infection by various strains of agrobacterium tumefaciens and agrobacterium rhizogenes is environmentally affected. in all instances, tumors could be induced on excised cotyledons while inoculating attached cotyledons or stems resulted in no tumor formation. in addition, buttercup squash (cucurbita maxima duch. buttercup) was most susceptible to tumor formation, while butterbush squash (cucurbita maxima duch. butterbush) failed to form tumors ...198616665082
secretion of zeatin, ribosylzeatin, and ribosyl-1'' -methylzeatin by pseudomonas savastanoi: plasmid-coded cytokinin biosynthesis.cytokinin production by strains of the phytopathogenic bacterium pseudomonas syringae pv savastanoi was measured by immunoaffinity chromatography of the culture medium on immobilized anti-cytokinin antibodies, followed by high performance liquid chromatography, radioimmunoassay and mass spectrometry. p. savastanoi strain pb213-2 secretes zeatin (80 nanograms per milliliter) and ribosylzeatin (80 nanograms per milliliter). even higher levels of zeatin (400 nanograms per milliliter) are produced b ...198616665104
agrobacterium-mediated gene transfer results mainly in transgenic plants transmitting t-dna as a single mendelian factor.forty-four independent transformed tobacco plants were obtained from a cocultivation experiment with agrobacterium tumefaciens strains carrying modified ti-plasmids. the transformed plants were either self-fertilized or crossed with nontransformed plants or with other transformed plants. the segregation of a phenotypic marker (kanamycin resistance) in the progenies of these plants was determined. in 40 cases out of 44, the segregation of the kanamycin resistance marker is consistent with mendeli ...198617246346
molecular basis for the auxin-independent phenotype of crown gall tumor tissues.the transfer of specific ti (tumor-inducing) plasmid sequences, the t-dna, from agrobacterium tumefaciens to a wide range of plants results in the formation of crown gall tumors. these tissues differ from most plant cells in that they can be grown in vitro in the absence of added phytohormones. here, data are presented that offer an explanation for the auxin-independent phenotype of crown gall tissues. it is shown that crude cell-free extracts prepared from three bacterial species harboring ptia ...19863511528
promoters of agrobacterium tumefaciens ti-plasmid virulence genes.the dna sequences of the promoter and 5' upstream regions of six agrobacterium tumefaciens ti-plasmid encoded virulence (vir) genes were determined. the transcription initiation sites were mapped by the s1 nuclease protection assay. in the -10 region, the vir promoters share a consensus sequence that is homologous to a dna sequence found in the same region of e. coli promoters. in contrast, the -35 region sequences are variable. several vir genes contain two common hexanucleotide sequences, 5'cg ...19863513123
nucleotide sequence and expression of a pseudomonas savastanoi cytokinin biosynthetic gene: homology with agrobacterium tumefaciens tmr and tzs loci.the nucleotide sequence of a pseudomonas trans-zeatin producing gene (ptz) from the pck1 plasmid of pseudomonas syringae pv. savastanoi strain 1006 has been determined. this gene confers upon e. coli the ability to synthesize and secrete several cytokinins including trans-zeatin, iso-pentenyladenine and their respective n9-ribosyl derivatives. sequence analysis indicates an open reading frame encoding a protein of 234 amino acids with a molecular weight of 26,816. significant sequence homology i ...19863515320
fate of selectable marker dna integrated into the genome of nicotiana tabacum.to compare the effects of different transformation methods on the integration behavior and structural stability of integrated foreign genes in plant cells, tobacco protoplasts were transformed with escherichia coli plasmid plgv2103neo dna using the ca phosphate dna coprecipitation technique. parallel transformations were done by cocultivation with agrobacterium tumefaciens harboring the ti plasmid derivatives pgv3850::2103neo or pgv3850::1103neo. a comparison of the fine structure of the integra ...19863519133
modification of t-dna of nopaline ti plasmid by intermediary vector and utilization of agrocin 84 sensitivity as simple criterion of conjugation transfer of modified ti plasmid.the chloramphenicol resistance gene from psa was introduced into t-dna of pti t37 of agrobacterium tumefaciens by cointegration with intermediary plasmid based on pbr322. the resulting intermediary vector was mobilized to a. tumefaciens t37 by conjugative plasmid prk2. the rk2 plasmid also forms contegrates with pti due to the tn3 transposon which was used for the mobilization of modified pti into plasmid-less a. tumefaciens strain. transconjugants were selected on the basis of their antibiotic ...19863519390
identification of legionella pneumophila with commercially available immunofluorescence test. 19863522642
initial interactions of agrobacterium tumefaciens with plant host cells.infections of wounded dicotyledonous plants by agrobacterium tumefaciens result in the formation of crown gall tumors. the initial step in tumor formation is the site-specific attachment of the bacteria to the host cells. the mechanism of recognition and attachment in this interaction has been studied in detail. current information on the nature of the bacterial binding sites, the nature of the host receptors, the role of bacterial cellulose fibrils, and the genetics of bacterial attachment will ...19863533427
plant phenolic compounds induce expression of the agrobacterium tumefaciens loci needed for virulence.the virulence loci of agrobacterium tumefaciens are a set of linked transcriptional units that play an essential role in the early stages of plant tumorigenesis. these loci are induced upon cocultivation of the bacteria with plant cells. seven phenolic compounds that are widely distributed among the angiosperm plants--catechol, gallic acid, pyrogallic acid, p-hydroxybenzoic acid, protocatechuic acid, beta-resorcylic acid, and vanillin--are able to induce the expression of the virulence loci. the ...19863085219
enzymes of the beta-ketoadipate pathway are inducible in rhizobium and agrobacterium spp. and constitutive in bradyrhizobium spp.protocatechuate is a universal growth substrate for members of the family rhizobiaceae, and these bacteria utilize the aromatic compound via the beta-ketoadipate pathway. this report describes transcriptional controls exercised by different subgroups of the rhizobiaceae over five enzymes that catalyze consecutive reactions in the pathway: protocatechuate oxygenase (ec 1.13.11.3), beta-carboxy-cis,cis-muconate lactonizing enzyme (ec 5.5.1.2), gamma-carboxymuconolactone decarboxylase (ec 4.1.1.44) ...19863941043
osmotic adaptation by gram-negative bacteria: possible role for periplasmic oligosaccharides.the cyclic (1----2)-beta-d-glucans produced by species of agrobacterium and rhizobium resemble the membrane-derived oligosaccharides of escherichia coli in their periplasmic localization, intermediate size, and (1----2)-beta-d-glucan backbones. the regulation of the biosynthesis of cyclic (1----2)-beta-d-glucan by agrobacterium tumefaciens is now shown to parallel the osmotic regulation of membrane-derived oligosaccharide biosynthesis in escherichia coli. this result suggests a general role for ...19863941890
arginine catabolism in agrobacterium strains: role of the ti plasmid.we present a study of the enzymatic activities involved in the pathway for arginine catabolism by agrobacterium tumefaciens. nitrogen from arginine is recovered through the arginase-urease pathway; the genes for these two activities are probably chromosomally born. arginase was found to be inducible during growth in the presence of arginine or ornithine. urease was constitutively expressed. ornithine, resulting from the action of arginase on arginine, could be used as a nitrogen source via trans ...19863957872
physical and functional map of supervirulent agrobacterium tumefaciens tumor-inducing plasmid ptibo542.agrobacterium tumefaciens strains carrying ptibo542 induce large, fast-appearing tumors and have an unusually wide host range. a clone bank was made from this 250-kilobase plasmid in a wide-host-range vector, and restriction maps were determined for bamhi and sali. the virulence genes, transferred dna genes, plasmid incompatibility region, and a region that inhibits growth of certain a. tumefaciens strains were localized. the six virulence genes and two tms genes were highly homologous to the ge ...19863957875
identification of rhizobium plasmid sequences involved in recognition of psophocarpus, vigna, and other legumes.symbiotic dna sequences involved in nodulation by rhizobium must include genes responsible for recognizing homologous hosts. we sought these genes by mobilizing the symbiotic plasmid of a broad host-range rhizobium mpik3030 (= ngr234) that can nodulate glycine max, psophocarpus tetragonolobus, vigna unguiculata, etc., into two nod- rhizobium mutants as well as into agrobacterium tumefaciens. subsequently, cosmid clones of pmpik3030a were mobilized into nod+ rhizobium that cannot nodulate the cho ...19863958042
enhanced instrumental sensitivity and selectivity for aminopeptidase profiling.laser-excited fluorimetry has been applied to the identification of bacteria and fungus. the instrumental sensitivity and selectivity of the aminopeptidase profiling method has been enhanced by the use of laser excitation in conjunction with improved spectral and temporal background rejection. the linear dynamic range for the aminopeptidase technique has been increased by achieving a reduced lower limit of detection of the fluorescent tag, beta-naphthylamine. standard aminopeptidase methodology ...19863706731
tomato golden mosaic virus a component dna replicates autonomously in transgenic plants.phenotypically normal petunia plants carrying chromosomal inserts of either the tomato golden mosaic virus (tgmv) a or the b component dna, as single or tandem inserts, were obtained using an agrobacterium tumefaciens ti plasmid-based transformation system. southern hybridization analysis revealed that the tandem, direct-repeat a plants contained free single and double stranded a component dnas. no free b component dna was detected in plants carrying tandem repeats of the b component. progeny of ...19863708687
transformed cell clones as a tool to study t-dna integration mediated by agrobacterium tumefaciens.a large number of tobacco sr1 cell clones transformed by the wild-type agrobacterium c58 have been analysed for the presence of screenable markers such as tumour morphology, opine synthesis and hormone dependence. distinct phenotypic classes were observed depending upon whether the cell clones were isolated from primary tumours or were obtained via cocultivation of protoplasts. these classes of tobacco sr1-c58 transformants appear to arise from errors in the ti plasmid (t-dna) transfer and integ ...19863723593
vira and virg control the plant-induced activation of the t-dna transfer process of a. tumefaciens.the ti plasmid vir loci of agrobacterium tumefaciens are transcriptionally activated in response to signal molecules produced by plant cells to initiate the t-dna transfer process. we show that the ptia6 vir loci are organized as a single regulon whose induction by plants is controlled by vira and virg. mutations in vira result in attenuated induction. this locus is constitutively transcribed and noninducible. mutations in virg eliminate vir induction. this locus is constitutively transcribed, p ...19863731272
proline biosynthesis encoded by the noc and occ loci of agrobacterium ti plasmids.octopine or nopaline ti plasmids, or clones encoding their occ or noc loci, allowed proline auxotrophs of agrobacterium tumefaciens to utilize the appropriate arginyl opine as a proline substitute. arginine and ornithine substituted for proline only if the occ or noc loci were induced or made constitutive by mutation. these results support a report demonstrating a ti plasmid-encoded activity in a. tumefaciens which cyclizes ornithine to proline.19863733675
two gene clusters of rhizobium meliloti code for early essential nodulation functions and a third influences nodulation efficiency.a plafr1 cosmid clone (ppp346) carrying the nodulation region of the symbiotic plasmid prme41b was isolated from a gene library of rhizobium meliloti 41 by direct complementation of a nod- deletion mutant of r. meliloti. agrobacterium tumefaciens and rhizobium species containing ppp346 were able to form ineffective nodules on alfalfa. the 24-kilobase insert in ppp346 carries both the common nodulation genes and genes involved in host specificity of nodulation. it was shown that these two regions ...19863745124
control of a futile urea cycle by arginine feedback inhibition of ornithine carbamoyltransferase in agrobacterium tumefaciens and rhizobia.in agrobacterium tumefaciens and rhizobia arginine can be used as the sole nitrogenous nutrient via degradation by an inducible arginase. these microorganisms were found to exhibit arginine inhibition of ornithine carbamoyltransferase activity. this inhibition is competitive with respect to ornithine (km for ornithine = 0.8 mm; ki for arginine = 0.05 mm). this type of urea cycle regulation has not been observed among other microorganisms which degrade arginine via an arginase. the competitive pa ...19863758074
molecular characterization of a host-range-determining locus from agrobacterium tumefaciens.the virulence loci play an essential role in tumor formation by agrobacterium tumefaciens. this study focused on the virc locus, which affects the host range agrobacterium species. virc mutants display an attenuated or avirulent phenotype on certain host plants, but remain fully virulent on other plant hosts. the nucleotide sequence revealed that the virc locus of ptia6nc is an operon consisting of two open reading frames. these two open reading frames, designated virc1 and virc2, encode protein ...19863759904
time required for tumor induction by agrobacterium tumefaciens.cellulose-minus mutants of agrobacterium tumefaciens retain virulence but can be removed from wound sites by washing with water. washing of bryophyllum diagremontiana leaves inoculated with a cellulose-minus mutant was used to determine the minimum time the bacteria must be present for tumor induction. this time was 4 to 8 h.19863767365
agrobacterium tumefaciens and the susceptible plant cell: a novel adaptation of extracellular recognition and dna conjugation. 19863768954
molecular cloning and expression of rhizobium fredii usda 193 nodulation genes: extension of host range for nodulation.dna hybridization with the cloned nodulation region of rhizobium meliloti as a probe revealed dna homology with four hindiii fragments, 12.5, 6.8, 5.2, and 0.3 kilobases (kb) in size, of the symbiotic plasmid prjausda193. both hybridization and complementation studies suggest that the common nodulation genes nodabc and nodd of r. fredii usda 193 are present on the 5.2-kb hindiii and 2.8-kb ecori fragments, respectively, of the sym plasmid. both fragments together could confer nodulation ability ...19863782034
the hypervirulence of agrobacterium tumefaciens a281 is encoded in a region of ptibo542 outside of t-dna.we used a binary-vector strategy to study the hypervirulence of agrobacterium tumefaciens a281, an l,l-succinamopine strain. strain a281 is hypervirulent on several solanaceous plants. we constructed plasmids (pcs65 and pcs277) carrying either the transferred dna (t-dna) or the remainder of the tumor-inducing (ti) plasmid (peha101) from this strain and tested each of these constructs in trans with complementary regions from heterologous ti plasmids. hypervirulence on tobacco could be reconstruct ...19863782037
delay of disease development in transgenic plants that express the tobacco mosaic virus coat protein gene.a chimeric gene containing a cloned cdna of the coat protein (cp) gene of tobacco mosaic virus (tmv) was introduced into tobacco cells on a ti plasmid of agrobacterium tumefaciens from which tumor inducing genes had been removed. plants regenerated from transformed cells expressed tmv mrna and cp as a nuclear trait. seedlings from self-fertilized transgenic plants were inoculated with tmv and observed for development of disease symptoms. the seedlings that expressed the cp gene were delayed in s ...19863457472
analysis of agrobacterium tumefaciens virulence mutants in leaf discs.the leaf disc transformation system provides a simple means to score expression of various t-dna markers within days of infection by agrobacterium tumefaciens as well as long-term selection for growth of transformed callus and shoots. in this report, we describe the application of this system to evaluation of marker transfer and integration in a comprehensive set of defined avirulent mutants of a. tumefaciens. we conclude that virc is not essential when the t-dna is present on a binary vector. t ...19863458219
the right border region of ptit37 t-dna is intrinsically more active than the left border region in promoting t-dna transformation.deletions of border regions of t-dna on agrobacterium ti plasmid or mini-t plasmid have shown the right border region of ptit37 t-dna to be more active than the left border region in promoting t-dna transformation. in this study we examine the possibility that the apparent difference in activity of left and right border regions may be due to position or orientation differences between the left and right borders with respect to the transferred onc genes. we have constructed eight similar single-b ...19863459162
nucleotide sequence analysis of tl-dna of agrobacterium rhizogenes agropine type plasmid. identification of open reading frames.we have determined the nucleotide sequence of the ri tl-dna region from an agrobacterium rhizogenes agropine-type plasmid using subcloned regions from the essentially identical ri tl-dnas from strains a4 and hri. this sequenced region of 21,126 base pairs (bp) contains the complete tl-dna region of the ri plasmid as determined by analysis of tl-dna borders in the genome of infected, clonal, convolvulus arvensis plants. the left and right borders of the tl-dna are flanked by 25-bp sequences which ...19863001043
stable transformation of maize after gene transfer by electroporation.the graminaceous monocots, including the economically important cereals, seem to be refractory to infection by agrobacterium tumefaciens, a natural gene transfer system that has been successfully exploited for transferring foreign genes into higher plants. therefore, direct transfer techniques that are potentially applicable to all plant species have been developed using a few dicot and monocot species as model systems. one of these techniques, electroporation, uses electrical pulses of high fie ...19863005872
expression of a bean storage protein 'phaseolin minigene' in foreign plant tissues.using the phaseolin gene and its cdna counterpart we constructed a mutant phaseolin gene lacking the five introns but retaining its natural 5' and 3' plant-regulatory sequences. this mutant phaseolin gene (minigene) was inserted into the ti-plasmid of agrobacterium tumefaciens strain 15955 which allowed its transfer and integration into the tobacco genome. full-length and correctly initiated phaseolin mrna was found among the poly(a)+rna isolated from plant callus transformed with the minigene c ...19863009275
activity of t-dna borders in plant cell transformation by mini-t plasmids.by using a binary vector system, we examined the requirements for border sequences in t-dna transformation of plant genomes. mini-t plasmids consisting of small replicons with different extents of ptit37 t-dna were tested for plant tumor-inducing ability in agrobacterium tumefaciens strain lba4404 containing helper plasmid pal4404 (which encodes virulence genes needed for t-dna transfer). assays of these bacteria on carrot disks, kalanchoë leaves, and sr1 nicotiana tabacum plantlets showed that ...19863009403
second symbiotic megaplasmid in rhizobium meliloti carrying exopolysaccharide and thiamine synthesis genes.using physical and genetic data, we have demonstrated that rhizobium meliloti su47 has a symbiotic megaplasmid, prmesu47b, in addition to the previously described nod-nif megaplasmid prmesu47a. this plasmid includes four loci involved in exopolysaccharide (exo) synthesis as well as two loci involved in thiamine biosynthesis. mutations at the exo loci have previously been shown to result in the formation of nodules which lack infection threads (inf-) and fail to fix nitrogen (fix-). thus, both me ...19863013840
the genetic and transcriptional organization of the vir region of the a6 ti plasmid of agrobacterium tumefaciens.the genetic transformation of plant cells by agrobacterium tumefaciens is mediated by the genes of the ti plasmid vir region. to determine the genetic and transcriptional organization of the vir region of ptia6, vir plasmid clones were saturated with insertion mutations of a tn3-lacz transposon. this element is both an insertion mutagen and a reporter for the expression of the sequences into which it has inserted. one hundred and twenty-four vir::tn3-lac insertions were analyzed for their mutage ...19863017694
nucleotide sequence of an insertion sequence (is) element identified in the t-dna region of a spontaneous variant of the ti-plasmid ptit37.we have identified and determined the nucleotide sequence of an is element (is136) of agrobacterium tumefaciens. this is the first is element isolated and sequenced from a nopaline type ti-plasmid. our is element has 32/30 bp inverted repeats with 6 mismatches, is 1,313 bp long and generates 9 bp direct repeats upon integration. is136 has 3 main open reading frames (orf's). only orf1 (159 codons) is preceded by sequences that are proposed to serve functional roles in transcriptional and translat ...19863018677
location of the right boundary of the virulence region on agrobacterium tumefaciens plasmid ptic58 and a host-specifying gene next to the boundary.the right boundary of the virulence (vir) region of the nopaline plasmid ptic58 of agrobacterium tumefaciens was determined by transposon insertion, cartridge emplacement, and deletion mutagenesis. genetic complementation with mutant and wild-type alleles led to the identification of the vire locus at the right boundary, which was located about 6 kilobases from the left border of the segment of dna that is transferred into the plant genome. vire is 2.0 kilobases long and encodes at least one pro ...19863019998
two-component regulatory systems responsive to environmental stimuli share strongly conserved domains with the nitrogen assimilation regulatory genes ntrb and ntrc.we report that the ntrb and ntrc proteins of bradyrhizobium sp. [parasponia] strain rp501 share homology with other regulatory proteins. there is extensive conservation of c-terminal regions between products of rp501 ntrb; klebsiella pneumoniae ntrb; escherichia coli envz, cpxa, and phor; agrobacterium tumefaciens vira; and, to a lesser extent, e. coli chea. there is also extensive conservation of n-terminal regions between products of rp501 ntrc; k. pneumoniae ntrc; e. coli ompr, sfra, phob, ch ...19863020561
the vird operon of agrobacterium tumefaciens encodes a site-specific endonuclease.tumor formation by agrobacterium tumefaciens involves the transfer and integration of a defined segment (t-dna) of tumor-inducing (ti) plasmid dna into the plant nuclear genome. a set of plasmid genes outside the t-dna, the vir genes, are thought to mediate the transfer process. we report here that the vird operon encodes a site-specific endonuclease that cleaves at a unique site within each of the 24 bp direct repeats that flank the t-dna. the endonuclease function was further localized to the ...19863021341
a gene essential for agrobacterium virulence is homologous to a family of positive regulatory loci.the vir region of agrobacterium tumefaciens spans at least six transcriptional loci required for crown gall tumorigenesis. the transcriptional induction of two of these vir loci in response to cocultivation with tobacco suspension cells was measured by using bacteria containing mutations in each of the six vir loci located on the ti plasmid. induction of these vir genes occurred only in bacteria that had functional copies of vira and virg. the nucleic acid sequence of a 1.25-kilobase clone encom ...19863022288
cloning and regulation of erwinia herbicola pigment genes.the genes coding for yellow pigment production in erwinia herbicola eho10 (atcc 39368) were cloned and localized to a 12.4-kilobase (kb) chromosomal fragment. a 2.3-kb avai deletion in the cloned fragment resulted in the production of a pink-yellow pigment, a possible precursor of the yellow pigment. production of yellow pigment in both e. herbicola eho10 and pigmented escherichia coli clones was inhibited by glucose. when the pigment genes were transformed into a cya (adenylate cyclase) e. coli ...19863023282
t-dna and opine synthetic loci in tumors incited by agrobacterium tumefaciens a281 on soybean and alfalfa plants.we report here the molecular characterization of transferred dna (t-dna) in leguminous tumors incited by agrobacterium tumefaciens a281 harboring the tumor-inducing plasmid ptibo542. the t-dna is composed of two regions named tl (left portion)-dna and tr (right portion)-dna, in accordance with the nomenclature for the octopine strains. tl-dna is defined by several internal hindiii restriction fragments totaling 10.8 kilobase pairs (kbp) in uncloned soybean and alfalfa tumors. alfalfa tumor dna m ...19863023301
[characteristics of derivatives of the plasmid rp4 in a broad range of hosts with altered properties of maintenance and inheritance].hydroxylamine-induced mutants of the plasmid ppd6 (8.4 kb) were isolated which are resistant to high doses of tetracycline. one of the plasmids studied--ppd21 is a multicopy mutant, another one, ppd12 is a dimeric form of the ppd6 plasmid. the ppd12 plasmid is very unstable, its derivative, ppd13 spontaneous mutant acquiring stability but not the ability to resolve dna multimeric forms into monomeric forms. multicopy bireplicon ppd619 plasmid was constructed by joining in vitro ppd6 and puc19 pl ...19863026896
integration of the delta-endotoxin gene of bacillus thuringiensis into the chromosome of root-colonizing strains of pseudomonads using tn5.the delta-endotoxin gene (tox) from bacillus thuringiensis subsp. kurstaki hd-1 was cloned into tn5 and the resulting tn5-tox element transposed from a vector plasmid into the chromosome of six corn-root-colonizing strains of pseudomonas fluorescens and agrobacterium radiobacter. chromosomal integration of the tox gene maximized stability and minimized the potential for horizontal transfer of the tox gene to other bacterial species. expression of the tox gene was demonstrated by western blot ana ...19863026918
nucleotide sequence of the virulence gene virg of the agrobacterium tumefaciens octopine ti plasmid: significant homology between virg and the regulatory genes ompr, phob and dye of e. coli.the entire nucleotide sequence of the virg locus, from the octopine ti plasmid of agrobacterium tumefaciens strain 15955, has been determined. the virg gene is 801 nucleotides in length and has one open reading frame which encodes a protein of mr 29,995. the virg gene is involved in the transcriptional activation of the ti plasmid vir-loci, which occurs after induction by specific compounds present in plant exudate. sequence analysis of the agrobacterium virg protein showed significant homology ...19863027669
a spontaneous insertion in the agrocin sensitivity region of the ti-plasmid of agrobacterium tumefaciens c58.a spontaneous agrocin-resistant mutant of agrobacterium tumefaciens strain c58 was shown to have an insertion of 1.2 kb in the agrocin-sensitivity region of ptic58. the insertion was cloned from the ti-plasmid, and a subclone containing only dna internal to the insertion was used to probe the ti-plasmid and chromosomal dna of the wild-type strain c58. the probe showed homology to chromosomal sequences but showed no homology to wild-type ptic58. homology was also detected with chromosomal sequenc ...19863027729
studies of the structure and functional organization of foreign dna integrated into the genome of nicotiana tabacum.in transgenic plants obtained either by agrobacterium tumefaciens-mediated transformation or by direct dna transfer, the structure of integrated chimeric donor dna remains stable during vegetative proliferation, during sexual transmission, and under various selection conditions. we correlate the level of expression of the introduced gene in independent transformants and their offspring with the particular arrangement and modification of their integrated dnas. genetic analysis of transgenic plant ...19863028737
expression of agrobacterium tumefaciens t-dna gene 7 in xenopus laevis oocytes.the expression of agrobacterium tumefaciens t-dna gene 7 was investigated in xenopus laevis oocytes. cloned dna injected into oocytes consisted of t-dna sequences derived from octopine type ti plasmid b6-806 and t-dna attached to plant dna sequences at the left junction in crown gall tumors. transcription initiation sites observed in oocytes were similar to those for transcript 7 in crown gall tumors. quantitative differences in transcription occurred depending on the flanking sequences of the i ...19863814121
transient and stable expression of the firefly luciferase gene in plant cells and transgenic plants.the luciferase gene from the firefly, photinus pyralis, was used as a reporter of gene expression by light production in transfected plant cells and transgenic plants. a complementary dna clone of the firefly luciferase gene under the control of a plant virus promoter (cauliflower mosaic virus 35s rna promoter) was introduced into plant protoplast cells (daucus carota) by electroporation and into plants (nicotiana tabacum) by use of the agrobacterium tumefaciens tumor-inducing plasmid. extracts ...198617758108
transformation of arabidopsis thaliana with agrobacterium tumefaciens.transformed arabidopsis thaliana plants have been produced by a modified leaf disk transformation-regeneration method. leaf pieces from sterilely grown plants were precultured for 2 days and inoculated with an agrobacterium tumefaciens strain containing an avirulent ti (tumor-inducing) plasmid with a chimeric gene encoding hygromycin resistance. after cocultivation for 2 days, the leaf pieces were placed on a medium that selects for hygromycin resistance. shoots regenerated within 3 months and w ...198617792019
transfer of agrobacterium dna to plants requires a t-dna border but not the vire locus.agrobacterium tumefaciens induces tumors in plants by transferring and integrating oncogenes (t-dna) into the chromosomes of host plant cells. agrobacterium strains were used to transfer complementary dna copies of a potato spindle tuber viroid (pstv) to plant cells at a wound site on tomato plant stems. subsequently, infectious viroid rna was found in the leaves of these plants, indicating systemic pstv infection. this process utilized the t-dna transfer mechanisms of agrobacterium since pstv i ...198617800798
neoplastic progression in crown gall in tobacco without elevated auxin levels.we have isolated two stable variants from a crown-gall teratoma tissue of tobacco (nicotiana tabacum l.) transformed by agrobacterium tumefaciens strain a66, a mutant of the virulent a6 strain containing an insertion sequence in the tumor-inducing (ti) plasmid at the locus coding for auxin biosynthesis. normally tobacco cells transformed by strain a66 spontaneously form shoots in culture and will not grow on hormone-free medium unless shoots develop. the variant tissue lines, isolated from the t ...198624232660
potato spindle tuber viroid infections mediated by the ti plasmid of agrobacterium tumefaciens.full length copies of potato spindle tuber viroid (pstv) were introduced into plant cells using an agrobacterium tumefaciens vector. crown galls containing the pstv dna were induced on tomato plants, and the plants analysed for systemic replication of the viroid. two separately derived multimeric pstv insertions in the t-dna were infectious on every plant inoculated. however, monomeric pstv gave rise to significant levels of infection only when an adjacent plant promoter could direct transcripti ...198624307321
changes in translatable poly(a) rna from differentiated potato tissues transformed with shoot-inducing ti tl-dna of agrobacterium tumefaciens.two dimensional gel electrophoresis was used to examine differences in steady state total poly(a) rna from untransformed potato (solanum tuberosum cv. maris bard) and potato transformed with shoot-inducing tl-dna from a. tumefaciens. rna was compared from phenotypically very distinct in vitro cultured shoots, more similar grafted plants and tubers. in each case between 200-400 translation products were identified representing the more abundant poly(a) mrna's. in general, poly(a) rna from the tra ...198624307320
isozyme gene expression in potato tumors incited by agrobacterium.two plant tumors (crown galls and hairy roots) were experimentally provoked on potato cv. 'désirée' by oncogenic strains of agrobacterium tumefaciens and a. rhizogenes. a marked shift in the expression of some organ-specific genes occurred in crown galls derived from the central zone of tubers: two novel isozyme genes (est-b and pox-e) were expressed, two others (est-c and pox-f) were suppressed and the remaining ones were maintained in the original state. when the starting tissue was the stem s ...198624247945
site-specific mutagenesis of potato spindle tuber viroid cdna: : alterations within premelting region 2 that abolish infectivity.the infectivity of cloned viroid cdnas permits investigation of structure/function relationships in these unusual pathogenic rnas by systematic site-specific mutagenesis of the cdnas and subsequent bioassay. we have used three different strategies to create nucleotide substitutions within premelting region 2, a region of potato spindle tuber viroid (pstv) believed to be important in viroid replication: sodium bisulfitecatalyzed deamination of deoxycytosine residues, oligonucleotide-directed muta ...198624307277
conservation of is66 homologue of octopine ti plasmid dna in rhizobium fredii plasmid dna.dna sequences homologous to the t-dna region of the octopine ti plasmid from agrobacterium tumefaciens are found in various fast-growing rhizobium fredii strains. the largest fragment (bamhi fragment 2) at the right-boundary region of the 'core' t-dna hybridizes to more than one plasmid present in r. fredii. however, one smaller fragment (ecori fragment 19a) adjacent to the 'core' t-dna shows homology only with the plasmid carrying the symbiotic nitrogen-fixation genes (psym). hybridization data ...198624302303
bleomycin resistance: a new dominant selectable marker for plant cell transformation.plant cells are sensitive to the antibiotic bleomycin, a dna damaging glycopeptide. a bleomycin resistance determinant, located on transposon tn5 and functional in bacteria, has been cloned in a plant expression vector and introduced into nicotiana plumbaginifolia using agrobacterium tumefaciens. the expression of this determinant in plant cells confers resistance to bleomycin and allows selection of transformed plant cells.198624302302
transformation of medicago by agrobacterium mediated gene transfer.shoot segments of medicago varia genotype a2 were co-cultivated with agrobacterium tumefaciens strain bo42 carrying pga471, a plasmid coding for the kanamycin resistant determinant as transferable positive selection marker in plant cells (an et al., 1985). resistant plants were regenerated at high frequency from green calli developed on inoculated stem cuttings under kanamycin selection. dna-dna hybridization analysis showed the presence of the structural gene of the kanamycin resistant determin ...198624248043
leaf disc transformation of cultivated tomato (l. esculentum) using agrobacterium tumefaciens.the leaf disc transformation/regeneration system was modified for tomato (l. esculentum). both leaf explants and cotyledon/hypocotyl sections can be used to regenerate transformed plants. we have obtained over 300 transgenic plants from eight tomato cultivars. we have evidence for both single and multi-copy insertions of the t-dna, and have demonstrated inheritance of the t-dna insert in the expected mendelian ratios. several heterologous promoters function in tomato. a reduced efficiency of tra ...198624248039
shoot regeneration of mesophyll protoplasts transformed by agrobacterium tumefaciens, not achievable with untransformed protoplasts.alternative methods for shoot regeneration in protoplast derived cultures were developed in nicotiana paniculata and physalis minima. in both species protoplast derived callus is not regeneratable to shoots by conventional methods, e.g. hormone treatment. leaf discs and stem segments of n. paniculata and p. minima were incubated with agrobacterium tumefaciens "shooter" strains harbouring pgv 2215 or pgv 2298 or wildtype strain b6s3. after 36 h of co-incubation protoplasts were prepared. (leaf di ...198624247786
transformation of forage legumes using agrobacterium tumefaciens.galls were induced in six species of forage legumes following inoculation with wild-type strains of a. tumefaciens. the plant species was more influential than the bacterial strain in determining the type of tumour produced. inoculation of medicago sativa resulted in small, disorganised tumours. the three trifolium species, t. repens, t. hybridum and t. pratense, formed galls which tended to produce roots and both onobrychis viciifolia and lotus corniculatus produced teratomatous galls. the shoo ...198624247771
independent integration and seed-transmission of the tr-dna of the octopine ti plasmid pti ach5 in nicotiana plumbaginifolia.after co-cultivation of diploid nicotiana plumbaginifolia protoplasts with an octopine-type agrobacterium tumefaciens strain (lba 4013) putative transformants were selected for hormone-independent growth, and were tested for t-dna markers. the number of transformants expressing only tl-dna markers, i.e. phytohormone autotrophy and octopine synthase, was an order of magnitude higher than that of the cell lines which were simultaneously positive for both tl- and tr-dna markers (the latter being ma ...198624307226
the transformation of zea mays seedlings with agrobacterium tumefaciens.virulent strains of the soil bacterium agrobacterium tumefaciens infect dicotyledonous plants and elicit a profound neoplastic response which results in crown gall formation (18). the inciting agent has been shown to be a high molecular weight plasmid (ti) a section of which, the t-dna, integrates into the host plant's genome (4, 28, 30). although transformation of this kind was presumed to be limited to dicots, the detection of enzyme activities linked to the expression of t-dna has been demons ...198624302156
a disarmed binary vector from agrobacterium tumefaciens functions in agrobacterium rhizogenes : frequent co-transformation of two distinct t-dnas.binary ti plasmid vector systems consist of two plasmids in agrobacterium, where one plasmid contains the dna that can be transferred to plant cells and the other contains the virulence (vir) genes which are necessary for the dna transfer but are not themselves stably transferred. we have constructed two nononcogenic vectors (parc4 and parc8) based on the binary ti plasmid system of agrobacterium tumefaciens for plant transformation. each vector contains the left and right termini sequences from ...198624307418
transformation of cultivated tomato by a binary vector in agrobacterium rhizogenes: transgenic plants with normal phenotypes harbor binary vector t-dna, but no ri-plasmid t-dna.cultivated tomato was genetically transformed using two procedures. in the first procedure, punctured cotyledons were infected with "disarmed" agrobacterium tumefaciens strain lba4404 or with a. rhizogenes strain a4, each containing the binary vector parc8. the chimeric neomycin phosphotransferase (npt ii) gene on parc8 conferred on transformed plant cells the ability to grow on medium containing kanamycin. transformation reproducible yielded kanamycin-resistant transformants in different tomato ...198624248198
transgenic plants as tools to study the molecular organization of plant genes.transgenic plants are generated in nature by agrobacterium tumefaciens, a pathogen that produces disease through the transfer of some of its own dna into susceptible plants. the genes are carried on a plasmid. much has been learned about how the plasmid is transferred, how the plasmid-borne genes are organized, regulated, and expressed, and how the bacteria's pathogenic effects are produced. the a. tumefaciens plasmid has been manipulated for use as a general vector for the transfer of specific ...198717801640
the 30-kilodalton gene product of tobacco mosaic virus potentiates virus movement.the proposed role of the 30-kilodalton(kd) protein of tobacco mosaic virus is to facilitate cell-to-cell spread of the virus-during infection. to directly define the function of the protein, a chimeric gene containing a cloned complementary dna of the 30-kd protein gene was introduced into tobacco cells via a ti plasmid-mediated transformation system of agrobacterium tumefaciens. transgenic plants regenerated from transformed tobacco cells expressed the 30-kd protein messenger rna and accumulate ...198717794341
site-specific nick in the t-dna border sequence as a result of agrobacterium vir gene expression.the t-dna transfer process of agrobacterium tumefaciens is activated by the induction of the expression of the ti plasmid virulence (vir) loci by plant signal molecules such as acetosyringone. the vir gene products act in trans to mobilize the t-dna element from the bacterial ti plasmid. the t-dna is bounded by 25-base pair direct repeat sequences, which are the only sequences on the element essential for transfer. thus, specific reactions must occur at the border sites to generate a transferabl ...198717758248
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