| molecular genetics of the glutamine synthetases in rhizobium species. | soil bacteria of the genus rhizobium and bradyrhizobium establish symbiotic interactions with leguminous plants that result in the formation of specialized structures, the nodules, in which the bacteria differentiate into bacteroids and fix nitrogen. rhizobial glutamine synthetase (gs) activity is very low in the nodule. the ammonia produced by the bacteroids is exported to the plant cell, where it is assimilated by the gs from the plant, whereas in the free-living state, rhizobium and bradyrhiz ... | 1994 | 7915906 |
| structures of nodulation factors from the nitrogen-fixing soybean symbiont rhizobium fredii usda257. | we have isolated and characterized the extracellular nod factors of rhizobium fredii usda257, a nitrogen-fixing symbiont of soybean [glycine max (l.) merr.] and several other legume species. these signals are produced upon exposure to the isoflavone genistein and consist of a series of substituted, beta 1,4-linked tri-, tetra-, and pentamers of n-acetylglucosamine. n-vaccenic acid replaces acetate on the nonreducing residue, and the reducing residue contains alpha-linked 2-o-methylfucose on carb ... | 1994 | 7918395 |
| expression of a bacterial gene in transgenic plants confers resistance to the herbicide phenmedipham. | tobacco plants were genetically engineered to express a detoxifying pathway for the herbicide phenmedipham. a gene from arthrobacter oxidans strain p52 that encodes an enzyme catalysing the hydrolytic cleavage of the carbamate compound phenmedipham has recently been cloned and sequenced. the coding sequence was fused with a cauliflower mosaic virus 35s promoter and introduced into tobacco plants by agrobacterium-mediated gene transfer. transgenic plants expressing high levels of phenmedipham hyd ... | 1994 | 7919217 |
| the small, versatile ppzp family of agrobacterium binary vectors for plant transformation. | the new ppzp agrobacterium binary vectors are versatile, relatively small, stable and are fully sequenced. the vectors utilize the ptit37 t-dna border regions, the pbr322 bom site for mobilization from escherichia coli to agrobacterium, and the cole1 and pvs1 plasmid origins for replication in e. coli and in agrobacterium, respectively. bacterial marker genes in the vectors confer resistance to chloramphenicol (ppzp100 series) or spectinomycin (ppzp200 series), allowing their use in agrobacteriu ... | 1994 | 7919218 |
| production of agrobacterium-mediated transgenic fertile plants by direct somatic embryogenesis from immature zygotic embryos of datura innoxia. | this work describes a new method to obtain transgenic somatic embryos from agrobacterium-infected immature zygotic embryos of datura innoxia. it has several advantages over previous transformation methods such as the absence of a callus phase, an average transformation rate of 76% and a high regeneration frequency. critical steps for optimal transformation were the embryo stage and a short preculture treatment. the marker gene beta-glucuronidase and light microscopy were used to identify the com ... | 1994 | 7919219 |
| tomatoes ... a brave new world. | | 1994 | 7919683 |
| a new proline-rich early nodulin from medicago truncatula is highly expressed in nodule meristematic cells. | we cloned and characterized mtprp4, a new member of the repetitive proline-rich protein gene family in medicago truncatula. the sequence of mtprp4 predicts a 62-kd protein consisting of a 22-amino acid n-terminal signal peptide and a 527-amino acid repetitive proline-rich domain composed of three repetitive pentapeptide motifs arranged into two decapeptide repeats: ppvekppvhk and ppvekppvyk. mtprp4 is the largest prp described to date and contains repeated motifs that have not previously been fo ... | 1994 | 7919991 |
| rhizobium meliloti nod factors elicit cell-specific transcription of the enod12 gene in transgenic alfalfa. | extracellular lipo-oligosaccharides of rhizobium, known as nod factors, play a key role in the molecular signal exchange which leads to the specific nitrogen-fixing symbiotic association between the soil microbe and its host legume. the biological activity of nod factors and their perception by the host plant during the earliest stages of the rhizobium/legume interaction have been studied using transgenic alfalfa carrying a fusion between the promoter of the early nodulin gene mtenod12 and the b ... | 1994 | 7920714 |
| efficient transformation of rice (oryza sativa l.) mediated by agrobacterium and sequence analysis of the boundaries of the t-dna. | a large number of morphologically normal, fertile, transgenic rice plants were obtained by co-cultivation of rice tissues with agrobacterium tumefaciens. the efficiency of transformation was similar to that obtained by the methods used routinely for transformation of dicotyledons with the bacterium. stable integration, expression and inheritance of transgenes were demonstrated by molecular and genetic analysis of transformants in the r0, r1 and r2 generations. sequence analysis revealed that the ... | 1994 | 7920717 |
| isolation of a rhizobium galegae strain-specific dna probe. | we have isolated a strain-specific dna probe from the strain rhizobium galegae hambi 1174 by a subtraction hybridization procedure followed by pcr amplification and dna cloning. the specificity of the 342-bp dna probe (p3) was tested in dot blot or southern blot hybridizations against total genomic dna of 41 bacterial strains (21 of them belong to r. galegae, 15 to other rhizobium species and five to other bacterial species). only the samples from four r. galegae strains, which are different iso ... | 1994 | 7921351 |
| the glabra2 gene encodes a homeo domain protein required for normal trichome development in arabidopsis. | the glabra2 gene (gl2) is one of several genes known to have a role in trichome development in arabidopsis. mutations at this locus result in abnormal trichome expansion. we have identified several gl2 mutants from a t-dna-mutagenized population of plants. the t-dna insert in one of the mutant lines cosegregated with the recessive gl2 phenotype and thus served as a molecular tag to isolate genomic dna at the putative gl2 locus. rflp analysis of the segregating population and subsequent molecular ... | 1994 | 7926739 |
| rhizobium meliloti homologs of escherichia coli mur genes. | the pectate-lyase-encoding gene pelb of erwinia chrysanthemi ec16 was used as a probe for hybridization to rhizobium meliloti rm1021 chromosomal dna under low-stringency conditions. an rm1021 dna fragment that hybridized to this probe was cloned and sequenced. results of rna hybridization indicate that a portion of the cloned fragment is transcribed in r. meliloti. although the rm1021 fragment shares no significant nucleotide sequence identity with ec16 pelb, it includes an orf (open reading fra ... | 1994 | 7926844 |
| purification of rhizobium leguminosarum hypb, a nickel-binding protein required for hydrogenase synthesis. | the products of the rhizobium leguminosarum hyp gene cluster are necessary for synthesis of a functional uptake [nife] hydrogenase system in symbiosis with pea plants, and at least for hypb and hypf, a role in hydrogenase-specific nickel metabolism has been postulated (l. rey, j. murillo, y. hernando, e. hidalgo, e. cabrera, j. imperial, and t. ruiz-argüeso, mol. microbiol. 8:471-481, 1993). the r. leguminosarum hypb gene product has been overexpressed in escherichia coli and purified by immobil ... | 1994 | 7928968 |
| resistance to nodulation of cv. afghanistan peas is overcome by nodx, which mediates an o-acetylation of the rhizobium leguminosarum lipo-oligosaccharide nodulation factor. | only some strains of rhizobium leguminosarum biovar viciae can efficiently nodulate varieties of peas such as cv. afghanistan, which carry a recessive allele that blocks efficient nodulation by most western isolates of r.i. viciae. one strain (tom) which can nodulate cv. afghanistan peas has a gene (nodx) that is required to overcome the nodulation resistance. strain tom makes significantly lower amounts of lipo-oligosaccharide nodulation factors than other strains of r.i. viciae and this effect ... | 1993 | 7934826 |
| processes at the nick region link conjugation, t-dna transfer and rolling circle replication. | data from prokaryotic replicative and conjugative systems, which interrelate dna processing events initiated by a site-specific nick, are reviewed. while the replicative systems have been established in accordance with the rolling circle replication model, the mechanism of conjugative replication has not been elucidated experimentally. we summarize data involving random point mutagenesis of the rk2 transfer origin (orit), which yielded relaxation-deficient and transfer-deficient derivatives havi ... | 1993 | 7934927 |
| a rhizobium tropici dna region carrying the amino-terminal half of a nodd gene and a nod-box-like sequence confers host-range extension. | rhizobium tropici ciat899 is a broad-host-range strain that, in addition to phaseolus, nodulates other plant legumes such as leucaena and macroptilium. the narrow-host-range of rhizobium leguminosarum biovars phaseoli (strain ce3) and trifolii (strain rs1051) can be extended to leucaena esculenta and phaseolus vulgaris plants, respectively, by the introduction of a dna fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodd gene from r. tropici, as well as a pu ... | 1993 | 7934929 |
| the orf1 of the gentamicin-resistance operon (aac) of pseudomonas aeruginosa encodes adenosine 5'-phosphosulphate kinase. | the gentamicin-resistance operon of pseudomonas aeruginosa (aac) contains two cistrons for which only the second gene product has an identified function. the 813bp second cistron (orf2) encodes a protein that confers gentamicin resistance by catalysis of the transfer of an acetyl group from acetyl coenzyme a to gentamicin. the first open reading frame (orf1) encodes a 23.9 kda protein that we have found, by enzyme activity and immunological reactivity, to be adenosine-5'-phosphosulphate (aps) ki ... | 1993 | 7934935 |
| hupk, a hydrogenase-ancillary protein from rhizobium leguminosarum, shares structural motifs with the large subunit of nife hydrogenases and could be a scaffolding protein for hydrogenase metal cofactor assembly. | | 1993 | 7934943 |
| overexpression of the prosystemin gene in transgenic tomato plants generates a systemic signal that constitutively induces proteinase inhibitor synthesis. | tomato plants (lycopersicon esculentum, var. better boy) were stably transformed with a gene consisting of the open reading frame of a prosystemin cdna under the regulation of the cauliflower mosaic virus 35s promoter. the leaves of the transgenic plants constitutively produced proteinase inhibitor i and ii proteins, which accumulated over time to levels exceeding 1 mg/g of dry leaf weight. this phenotype contrasts with that of untransformed plants, which produce proteinase inhibitor proteins in ... | 1994 | 7937894 |
| differential gene expression in an actinorhizal symbiosis: evidence for a nodule-specific cysteine proteinase. | nodules formed on the roots of actinorhizal plants as a consequence of nitrogen-fixing symbioses with the actinomycete frankia appear to result from modification of the developmental pathway that leads to lateral root formation. presently no information exists about factors that control this developmental switch or, until now, about genes that are differentially expressed as a result of an altered developmental pathway. differential screening of an alnus glutinosa nodule cdna library revealed al ... | 1994 | 7937912 |
| posttranscriptional silencing of reporter transgenes in tobacco correlates with dna methylation. | endogenous plant genes or transgenes can be silenced on introduction of homologous gene sequences. here we document a reporter gene-silencing event in nicotiana tabacum that has a distinctive combination of features--i.e., (i) silencing occurs by a posttranscriptional process, (ii) silencing correlates with dna methylation, and (iii) this de novo methylation is not restricted to cytosines located in the symmetrical motifs cg and cxg. | 1994 | 7937983 |
| [the rhizobium-prosopis symbiosis in the argentinian chaco arido]. | low productivity soils can be improved by incorporation of adapted legumes species able to increase the nitrogen fixation when associated to rhizobium strains. two fast-growing rhizobium strains were isolated from nodules of prosopis alba. infectivity and effectivity of the strains were assessed under controlled conditions, measuring the following parameters: nodule number, dry weight, nitrogen percentage and fixed nitrogen. p. flexuosa strains showed high infective capacity (144 nodules/plant) ... | 1994 | 7938496 |
| developmental specific expression and organelle targeting of the escherichia coli fabd gene, encoding malonyl coenzyme a-acyl carrier protein transacylase in transgenic rape and tobacco seeds. | in both plants and bacteria, de novo fatty acid biosynthesis is catalysed by a type ii fatty acid synthetase (fas) system which consists of a group of eight discrete enzyme components. the introduction of heterologous, i.e. bacterial, fas genes in plants could provide an alternative way of modifying the plant lipid composition. in this study the escherichia coli fabd gene, encoding malonyl coa-acp transacylase (mcat), was used as a model gene to investigate the effects of over-producing a bacter ... | 1994 | 7948869 |
| tissue-specific expression of an oat 12s seed globulin gene in developing tobacco seeds: differential mrna and protein accumulation. | we studied the expression of the oat globulin gene asglo5 in developing transgenic tobacco seeds. the asglo5 gene promoter directed transcription in the endosperm as well as in the provascular tissue, the presumptive root tip and the shoot apical meristem of the embryo as revealed by gus reporter gene constructs and in situ hybridization. however, immunological tissue printing detected the oat protein exclusively in the tobacco endosperm, suggesting that extensive post-transcriptional regulatory ... | 1994 | 7948870 |
| repression of the l-asparaginase gene during nodule development in lupinus angustifolius. | upon the establishment of an effective nitrogen-fixing symbiosis in amide-transporting plants the enzymatic activity and transcript levels of l-asparaginase are dramatically decreased. this decrease in l-asparaginase activity is essential for the correct functioning of the rhizobium-legume symbiosis in lupin in which asparagine, synthesized from recently fixed nitrogen, is exported to aerial parts of the plant for use in growth and development. concomitant with this decrease in l-asparaginase tr ... | 1994 | 7948878 |
| rol genes of agrobacterium rhizogenes cucumopine strain: sequence, effects and pattern of expression. | by sequencing the central region of the cucumopine-type t-dna of agrobacterium rhizogenes strain 2659, we identified three open reading frames homologous, to different extents, to orfs 10, 11 and 12 (rola, b and c) of the agropine-type (1855) t-dna. recombinant agrobacterium strains encompassing the orfs of 2659 t-dna--which we refer to as rol alpha, beta and gamma--were utilized to infect carrot discs and to obtain transgenic tobacco plants, in order to compare the morphogenetic capabilities to ... | 1994 | 7948887 |
| dissecting molecular mechanisms of nodulation: taking a leaf from arabidopsis. | | 1994 | 7948910 |
| vascular expression of the grp1.8 promoter is controlled by three specific regulatory elements and one unspecific activating sequence. | the bean grp1.8 full-length promoter is specifically active in vascular tissue during normal development of tobacco. deletion of a negative regulatory element resulted in ectopic activity of the promoter in cortical cells of hypocotyls, roots and stems. a 169 bp fragment (-205 to -36) of the grp1.8 promoter conferred vascular-specific expression to camv 35s minimal promoters whereas a 141 bp fragment (-205 to -64) strongly activated these minimal promoters both in vascular and cortical cells. th ... | 1994 | 7948928 |
| dna sequence of the common nodulation genes of bradyrhizobium elkanii and their phylogenetic relationship to those of other nodulating bacteria. | a 6.6-kb bamhi fragment containing the common nodulation genes of bradyrhizobium elkanii usda94 was identified by southern hybridization using the common nod genes of b. japonicum as a probe. this fragment was cloned and sequenced. analysis of the sequence showed open reading frames highly homologous to nola, nodd2, nodd1, and nodkabc from other bradyrhizobial sources. the sequence showed higher homology to the common nod genes of bradyrhizobium sp. (parasponia) than to those from b. japonicum. ... | 1994 | 7949325 |
| t-dna-insert-independent mutations induced in transformed plant cells during agrobacterium co-cultivation. | transformation frequencies were determined for 1n, 2n, and 4n nicotiana plumbaginifolia protoplast cultures in agrobacterium-mediated gene transfer experiments. an unexpected large drop (50%) in plating efficiencies was observed in the non-selected (control) 1n populations after transformation treatment with virulent strains. this effect was not observed in the 2n or 4n cultures or in the 1n cultures when treated with avirulent bacteria. the mortality was disproportionally high and could not be ... | 1994 | 7951334 |
| [the endotoxins of gram-negative bacteria: their structure and biological role]. | main attention in the paper is paid to the study of lipid a, a component possessing endotoxic activity. lipids a containing glucosamine disaccharide (representatives of enterobacteriaceae family), and variants of lipid a differing from the toxic one either in the structure of carbohydrate core or in the spectrum of fatty acids are considered. they are either phototrophic, nodulating (bradyrhyzobium species) or soil species (nitrobacter and thiobacillus) bacteria. lipid a from lipopolysaccharides ... | 1994 | 7952230 |
| molecular architecture of a galactoglucan from rhizobium meliloti. | rhizobium meliloti mutants produce a linear, acidic exopolysaccharide with alternating galactopyranosyl and glucopyranosyl units having (1-->3) linkages. it has a 4,6-o-pyruvic cyclic acetal group on the alpha-galactosyl and 6-o-acetyl ester group on the beta-glucosyl units. x-ray diffraction patterns from polycrystalline and well oriented specimens of its potassium salt indicate that the polymer forms a 2-fold helix of pitch 15.89 a. the three-dimensional structure has been determined and refin ... | 1994 | 7954516 |
| enod40, a gene expressed during nodule organogenesis, codes for a non-translatable rna involved in plant growth. | rhizobium meliloti can interact symbiotically with medicago plants, thereby inducing root nodules. however, certain medicago plants can form nodules spontaneously, in the absence of rhizobia. a differential screening was performed using spontaneous nodule versus root cdnas from medicago sativa ssp. varia. transcripts of a differentially expressed clone, msenod40, were detected in all differentiating cells of nodule primordia and spontaneous nodules, but were absent in fully differentiated cells. ... | 1994 | 7957074 |
| cell wall degradation during infection thread formation by the root nodule bacterium rhizobium leguminosarum is a two-step process. | in the nitrogen-fixing root-nodule symbiosis of rhizobium leguminosarum biovar viciae and its host plants pea and vetch, the bacteria enter one root cortical cell after another via a tip-growing structure, the infection thread. rhizobial nod (nodulation) factors induce the formation of preinfection thread structures (van brussel, a.a.n., r. bakhuizen, p.c. van spronsen, h.p. spaink, t. tak, b.j.j. lugtenberg, j.w. kijne, science 257, 70-72 (1992)), but formation of infection threads requires the ... | 1994 | 7957317 |
| dna binding activity of ntrc from rhizobium grown on different nitrogen sources. | the dna-binding activity of the ntrc protein can be demonstrated in gel retardation assays with concentrated protein extracts of rhizobium etli. using extracts from either the wild type or a ntrc mutant strain and an antiserum raised against the ntrc protein, we demonstrate specific binding of ntrc to the upstream regulatory region of the glnii gene, where two putative ntrc-binding sites are present. kno3-grown bacteria contain less ntrc protein and more ntrc-binding activity than nh4cl-grown ba ... | 1994 | 7957908 |
| differential effects of elicitors on secondary metabolism in hairy root cultures of tobacco (nicotiana tabacum). | | 1994 | 7958330 |
| construction of a bidirectional promoter probe vector and its use in analysing nod gene expression in rhizobium loti. | a broad-host-range bidirectional promoter reporter vector, pspv4, has been constructed to analyse the activity of cloned divergent regulatory regions. plasmid pspv4 contains a pair of divergent promoterless reporter genes (lacz and gusa) that are bisected by an extensive multiple cloning site. [corrected] the transcriptional fusion vector pspv4 has a distinct advantage over unidirectional promoter probe vectors in that it can determine the activity of a cloned bidirectional regulatory region sim ... | 1994 | 7959034 |
| the pss4 gene from rhizobium leguminosarum by viciae vf39: cloning, sequence and the possible role in polysaccharide production and nodule formation. | the tn5 insertion into the genome of rhizobium leguminosarum bv viciae vf39, resulting in non-mucoid growth and formation of non-n2-fixing nodule-like structures on vicia faba plants, was mapped within a 1.4-kb ecorv-saci fragment. nucleotide sequence analysis revealed an orf (pss4) of 263 amino acids (aa). three transcription start points (tsp) were determined. two of them were localized upstream from the first gtg codon; the third tsp was mapped in front of the second putative start codon (gtg ... | 1994 | 7959035 |
| a chromosomal cluster of genes encoding adp-glucose synthetase, glycogen synthase and phosphoglucomutase in agrobacterium tumefaciens. | a chromosomal region from agrobacterium tumefaciens that complements exoc (pgm) mutations was cloned and sequenced. a cluster of three open reading frames (orf1, orf2 and orf3) was identified. these genes are oriented in the same direction and are involved in the synthesis of glycogen and other polysaccharides. orf1 encodes a 420-amino-acid (aa) protein with 55.9% homology to escherichia coli glgc (adp-glucose synthetase, ec 2.7.7.27). orf2 encodes a 480-aa protein with 42.2% homology to e. coli ... | 1994 | 7959036 |
| nucleotide sequence of the rhizobium etli nods gene. | the complete nucleotide sequence of the nods gene from the bean-nodulating rhizobium etli, presumably encoding a methyltransferase, was determined. a phylogenetic analysis of five different nods proteins from three genera of gram- soil bacteria, azorhizobium, bradyrhizobium and rhizobium, was performed. | 1994 | 7959055 |
| mutational analysis of the transcriptional activator virg of agrobacterium tumefaciens. | to find virg proteins with altered properties, the virg gene was mutagenized. random chemical mutagenesis of single-stranded dna containing the agrobacterium tumefaciens virg gene led with high frequency to the inactivation of the gene. sequence analysis showed that 29% of the mutants contained a virg gene with one single-base-pair substitution somewhere in the open reading frame. thirty-nine different mutations that rendered the virg protein inactive were mapped. besides these inactive mutants, ... | 1994 | 7961391 |
| rhizobium meliloti nodp and nodq form a multifunctional sulfate-activating complex requiring gtp for activity. | the nodulation genes nodp and nodq are required for production of rhizobium meliloti nodulation (nod) factors. these sulfated oligosaccharides act as morphogenic signals to alfalfa, the symbiotic host of r. meliloti. in previous work, we have shown that nodp and nodq encode atp sulfurylase, which catalyzes the formation of aps (adenosine 5'-phosphosulfate) and ppi. in the subsequent metabolic reaction, aps is converted to paps (3'-phosphoadenosine 5'-phosphosulfate) by aps kinase. in escherichia ... | 1994 | 7961471 |
| sequences, organization and analysis of the hupzmnoqrtv genes from the azotobacter chroococcum hydrogenase gene cluster. | hydrogen-uptake (hup) activity in azotobacter chroococcum depends upon a cluster of genes spread over 13,687 bp of the chromosome. six accessory genes of the cluster, hupabycde, begin 4.8 kb downstream of the structural genes, hupsl, and are required for the formation of a functional [nife] hydrogenase. the sequencing of the intervening 4.8 kb of hup-specific dna has now been completed. this revealed eight additional closely linked orfs, which we designated hupz, hupm, hupn, hupo, hupq, hupr, hu ... | 1994 | 7966281 |
| restoration of attachment, virulence and nodulation of agrobacterium tumefaciens chvb mutants by rhicadhesin. | in contrast to wild-type agrobacterium tumefaciens strains, beta-1,2-glucan-deficient chvb mutants were found to be unable to attach to pea root hair tips. the mutants appeared to produce rhicadhesin, the protein that mediates the first step in attachment of rhizobiaceae cells to plant root hairs, but the protein was inactive. both attachment to root hairs and virulence of the chvb mutants could be restored by treatment of the plants with active rhicadhesin, whereas treatment of plants with beta ... | 1993 | 7968537 |
| genetic regulation of nitrogen fixation in rhizobia. | this review presents a comparison between the complex genetic regulatory networks that control nitrogen fixation in three representative rhizobial species, rhizobium meliloti, bradyrhizobium japonicum, and azorhizobium caulinodans. transcription of nitrogen fixation genes (nif and fix genes) in these bacteria is induced primarily by low-oxygen conditions. low-oxygen sensing and transmission of this signal to the level of nif and fix gene expression involve at least five regulatory proteins, fixl ... | 1994 | 7968919 |
| the n-terminal domain of virg of agrobacterium tumefaciens: modelling and analysis of mutant phenotypes. | fourteen mutants in the n-terminal domain of virulence factor g (virg) were obtained by random mutagenesis. two mutants showed an altered phenotype, all others were non-functional. all mutants can still be phosphorylated and bind to dna. a 3-d model was built based on the coordinates of chemotaxis protein y (chey). many of the observed phenotypic changes of virg are explained qualitatively. combination of model building and biochemical information leads to the conclusion that the active sites of ... | 1994 | 7971952 |
| alterations of auxin perception in rolb-transformed tobacco protoplasts. time course of rolb mrna expression and increase in auxin sensitivity reveal multiple control by auxin. | expression and physiological effects of the root-inducing rolb gene of agrobacterium rhizogenes t-dna were studied simultaneously in tobacco (nicotiana tabacum) mesophyll protoplasts. the kinetic study of the expression of rolb mrna following exogenous auxin application showed that auxin transiently stimulated rolb expression, with mrna levels starting to accumulate 6 to 9 h after auxin was supplied and increasing 300-fold after 12 to 18 h. the parallel study of the auxin sensitivity of rolb-tra ... | 1994 | 7972494 |
| an attempt at application of trna genes as promoters of protein-coding genes in transgenic plants. | | 1994 | 7976020 |
| nonspecific transmission of the nptii gene from e. coli helper plasmid to a plasmid of agrobacterium tumefaciens. | | 1994 | 7976022 |
| biological control of fungal pathogens. | biological control of soil-borne plant pathogens is a potential alternative to the use of chemical pesticides, which have already been proved to be harmful to the environment. several strains of the fungus trichoderma have been isolated and found to be effective biocontrol agents of various soil-borne plant pathogenic fungi under greenhouse and field conditions. different application approaches have been used including integration of trichoderma with reduced doses of chemical agents. biochemical ... | 1994 | 7979350 |
| host-plant invasion by rhizobium: the role of cell-surface components. | rhizobia are soil bacteria that can become endosymbionts, reducing atmospheric nitrogen within nodules formed on the roots of legume plants. during tissue and cell invasion, bacterial cell-surface components adapt the bacterium to survive as an endophyte without eliciting host-defence responses. the structures of many of these components have been established recently, allowing their possible roles in invasion to be defined more clearly. | 1994 | 7981970 |
| nod factors of rhizobium are a key to the legume door. | symbiotic interactions between rhizobia and legumes are largely controlled by reciprocal signal exchange. legume roots excrete flavonoids which induce rhizobial nodulation genes to synthesize and excrete lipo-oligosaccharide nod factors. in turn, nod factors provoke deformation of the root hairs and nodule primordium formation. normally, rhizobia enter roots through infection threads in markedly curled root hairs. if nod factors are responsible for symbiosis-specific root hair deformation, they ... | 1994 | 7984092 |
| rhizobium meliloti dctd, a sigma 54-dependent transcriptional activator, may be negatively controlled by a subdomain in the c-terminal end of its two-component receiver module. | rhizobium meliloti dctd is believed to have three functional domains: an n-terminal, two-component receiver domain; and like other sigma 54-dependent activators, c-terminal and central domains for dna binding and transcription activation. we have characterized a progressive series of n-terminal deletions of r. meliloti dctd. the n-terminal domain was not needed for binding the dcta upstream activation sequence. only 25% of the c-terminal end of the receive domain was needed to significantly inhi ... | 1994 | 7984094 |
| the nodd proteins of rhizobium sp. strain br816 differ in their interactions with coinducers and in their activities for nodulation of different host plants. | the early steps of symbiotic nodule formation by rhizobium spp. on plants require coordinate expression of several nod gene operons, which is accomplished by the activating protein nodd. rhizobium sp. strain br816, isolated from leucaena leucocephala, contains four nodd genes which differ in their interaction with flavonoids. two of the four nodd proteins, namely, nodd1 and nodd2, obey the lysr rule regarding the need of a coinducer. nodd3 shows hardly any inducing activity, and nodd4 contains a ... | 1994 | 7986038 |
| alfalfa yield response to inoculation with recombinant strains of rhizobium meliloti with an extra copy of dctabd and/or modified nifa expression. | the construction of rhizobial strains which increase plant biomass under controlled conditions has been previously reported. however, there is no evidence that these newly constructed strains increase legume yield under agricultural conditions. this work tested the hypothesis that carefully manipulating expression of additional copies of nifa and dctabd in strains of rhizobium meliloti would increase alfalfa yield in the field. the rationale for this hypothesis is based on the positive regulator ... | 1994 | 7986051 |
| a new open reading frame, encoding a putative regulatory protein, in agrobacterium rhizogenes t-dna. | we report the presence of an open reading frame, named orf13a, encoding a putative regulatory protein on the t-dna of agrobacterium rhizogenes 8196 ri plasmid. homologous orfs are present at the same location in two other types of ri plasmids. we present evidence that orf13a is transcriptionally active. expression of orf13a was investigated by analysis of glucuronidase (gus) activity in transgenic tobacco containing an orf13agus fusion. the gene fusion was expressed at higher level in roots than ... | 1994 | 7987690 |
| occurrence of sulfoquinovosyl diacylglycerol in some members of the family rhizobiaceae. | a radiolabeled component of a membrane extract of rhizobium meliloti 2011 cells grown in the presence of 35s-labeled sulfate was isolated by silica flash chromatography and purified by high performance liquid chromatography (hplc). based on 1- and 2-dimensional nuclear magnetic resonance (nmr) spectroscopic and mass spectrometric analyses, the structure of the compound was determined to be sulfoquinovosyl diacylglycerol (sqdg). nmr analyses indicated substantial heterogeneity in the fatty acid c ... | 1994 | 7989869 |
| [expression of a partially modified delta-endotoxin gene from bacillus thuringiensis var. tenebrionis in transgenic potato plants]. | a modified gene (bt77) of delta-endotoxin from bacillus thuringiensis var. tenebrionis was constructed and cloned into pmon505. this binary transformation vector was introduced into agrobacterium tumefaciens strains containing different helper disarmed ti-plasmids, lba4404, a281, and cbe21. these agrobacterium strains were used to transform potato stem segments (s. tuberosum, cv desiree, resy, temp, granat). regenerants were selected on kanamycin-containing media. the presence of the bt77 sequen ... | 1994 | 7990839 |
| is1032 from acetobacter xylinum, a new mobile insertion sequence. | is1031 elements constitute a family of related insertion sequences (is) in acetobacter xylinum strains. a new is1031-related element, is1032, was isolated from a. xylinum atcc 23770. southern hybridization analysis showed that one or more sequences similar to is1032 are present in most of the a. xylinum strains examined. in addition, one copy was detected in acetobacter aceti atcc 15973. the transposition of is1032 was evident from the appearance of an extra insertion in a spontaneous exopolysac ... | 1994 | 7991672 |
| the large nonsymbiotic plasmid prmegr4a of rhizobium meliloti gr4 encodes a protein involved in replication that has homology with the repc protein of agrobacterium plasmids. | the large plasmid, prmegr4a, of rhizobium meliloti gr4 is a nonsymbiotic, self-transmissible replicon that shows a high degree of stability. plasmid replication and stabilization functions are located on a 4.8-kb psti fragment. analysis of the nucleotide sequence of this dna region revealed the presence of six open reading frames (orfs) with coding capabilities; all are transcribed in the same direction. only one of the orfs (orf3) seems to be essential for replication. its predicted protein seq ... | 1994 | 7991675 |
| construction of agrobacterium strains by electroporation of genomic dna and its utility in analysis of chromosomal virulence mutations. | we have extended the technique of electroporation as a genetic tool for manipulating the agrobacterium tumefaciens chromosome. we used this technique to introduce chromosomal dna into recipient a. tumefaciens strains by electroporation and constructed isogenic chve mutants that share the same chromosomal background but differ in their types of pti (octopine or nopaline). both nopaline and octopine pti-carrying chve mutants were deficient in vir regulon induction and exhibited similar reductions ... | 1994 | 7993100 |
| rhizobium meliloti lipooligosaccharide nodulation factors: different structural requirements for bacterial entry into target root hair cells and induction of plant symbiotic developmental responses. | rhizobium meliloti produces lipochitooligosaccharide nodulation nodrm factors that are required for nodulation of legume hosts. nodrm factors are o-acetylated and n-acylated by specific c16-unsaturated fatty acids. nodl mutants produce non-o-acetylated factors, and nodfe mutants produce factors with modified acyl substituents. both mutants exhibited a significantly reduced capacity to elicit infection thread (it) formation in alfalfa. however, once initiated, its developed and allowed the format ... | 1994 | 7994171 |
| rhizobium nod factors reactivate the cell cycle during infection and nodule primordium formation, but the cycle is only completed in primordium formation. | rhizobia induce the formation of root nodules on the roots of leguminous plants. in temperate legumes, nodule organogenesis starts with the induction of cell divisions in regions of the root inner cortex opposite protoxylem poles, resulting in the formation of nodule primordia. it has been postulated that the susceptibility of these inner cortical cells to rhizobium nodulation (nod) factors is conferred by an arrest at a specific stage of the cell cycle. concomitantly with the formation of nodul ... | 1994 | 7994175 |
| reduced ethylene synthesis by transgenic tomatoes expressing s-adenosylmethionine hydrolase. | we have utilized a gene from bacteriophage t3 that encodes the enzyme s-adenosylmethionine hydrolase (samase) to generate transgenic tomato plants that produce fruit with a reduced capacity to synthesize ethylene. s-adenosylmethionine (sam) is the metabolic precursor of 1-aminocyclopropane-1-carboxylic acid, the proximal precursor to ethylene. samase catalyzes the conversion of sam to methylthioadenosine and homoserine. to restrict the presence of samase to ripening fruit, the promoter from the ... | 1994 | 7999994 |
| termini and telomeres in t-dna transformation. | a t-dna vector for plant transformation has been constructed in which the cloning site is located 9 bp from the right-border (rb) end and 27 bp from the left-border (lb) end. in this vector cloned dna homologous to plant chromosomal sequences is located at the t-dna termini, and will thus be exposed by even limited exonucleolysis in planta. the arabidopsis adh (alcohol dehydrogenase) locus was mobilized from agrobacterium, and integration into the recipient genome was studied. despite the termin ... | 1994 | 8000005 |
| cloning and sequencing show that 4-hydroxybenzoate hydroxylase (poba) is required for uptake of 4-hydroxybenzoate in rhizobium leguminosarum. | mutants of rhizobium leguminosarum bv. viciae mnf300 and r. leguminosarum bv. trifolii wu95 unable to accumulate 4-hydroxybenzoate lack 4-hydroxybenzoate hydroxylase. the capacity of these mutants to take up and grow on 4-hydroxybenzoate was restored by a 2.0 kb ecori-psti dna fragment. this contained only one orf which had over 60% dna sequence similarity with the structural gene for 4-hydroxybenzoate hydroxylase (poba) from pseudomonas spp. and acinetobacter. reported effects of metabolic inhi ... | 1994 | 8000543 |
| identification of chromosomal genes located downstream of dctd that affect the requirement for calcium and the lipopolysaccharide layer of rhizobium leguminosarum. | in rhizobium leguminosarum both the c4-dicarboxylate transport system and wild-type lipopolysaccharide layer (lps) are essential for nitrogen fixation. a tn5 mutant (ru301) of r. leguminosarum bv. viciae 3841, was isolated that is only able to synthesize lps ii, which lacks the o-antigen. strain ru301 exhibits a rough colony morphology, flocculates in culture and is unable to swarm in ty agar. it also fails to grow on organic acids, sugars or ty unless the concentration of calcium or magnesium i ... | 1994 | 8000544 |
| expression of the symbiotic plasmid from rhizobium leguminosarum biovar trifolii in sphingobacterium multivorum. | an inoculant strain of rhizobium leguminosarum biovar trifolii containing a tn5 marked symbiotic plasmid transferred this plasmid by conjugation to sphingobacterium multivorum, an organism that can be found in soil. the transconjugant bacteria nodulated the roots of white clover (trifolium repens) seedlings but did not fix atmospheric nitrogen. microscopic examination revealed abnormal nodule structures. bacteria isolated from the nodules were shown to be closely related to the recipient s. mult ... | 1994 | 8000966 |
| serine residue 45 of nodulation protein nodf from rhizobium leguminosarum bv. viciae is essential for its biological function. | a system for testing the role of the rhizobium nodf gene in the production of host-specific lipochitin oligosaccharides and in nodulation was developed. we show that a mutant nodf gene, in which the codon for serine residue 45 was changed to that for threonine, still expresses nodf, which, however, is no longer functional. | 1994 | 8002602 |
| the adaptive acid tolerance response in root nodule bacteria and escherichia coli. | root nodule bacteria and escherichia coli show an adaptive acid tolerance response when grown under mildly acidic conditions. this is defined in terms of the rate of cell death upon exposure to acid shock at ph 3.0 and expressed in terms of a decimal reduction time, d. the d values varied with the strain and the ph of the culture medium. early exponential phase cells of three strains of rhizobium leguminosarum (wu95, 3001 and wsm710) had d values of 1, 6 and 5 min respectively when grown at ph 7 ... | 1994 | 8002711 |
| oncogene arrangement in a shooty strain of agrobacterium tumefaciens. | the agrobacterium tumefaciens nopaline strain 82.139 induces non-teratogenic shooty tumours on several plant species. we have determined the position of the t-region oncogenes in a 11.4 kb xba i fragment which shows a general organization similar to its ptic58 counterpart. sequence analysis of the 4.7 kb right part of this fragment allowed us to identify the pti82.139 ipt, 6b and nos coding sequences. pti82.139 lacks the 6a gene, which lies between the ipt and 6b genes in ptic58. the intervening ... | 1994 | 8003699 |
| bryonolic acid production in hairy roots of trichosanthes kirilowii max. var japonica kitam. transformed with agrobacterium rhizogenes and its cytotoxic activity. | the hairy roots of trichosanthes kirilowii max, var. japonica kitam. were induced by agrobacterium rhizogenes (tcc 15834) on sterile shoots. the axenic culture of hairy roots proliferated 30 to 60-fold based on the initial fresh weight after three weeks of culture in murashige & skoog liquid media. bryonolic acid as the main triterpenoid was isolated in a high yield, together with chondrillasterol from the hairy roots of this plant. bryonolic acid showed strong inhibition of the growth of b-16 m ... | 1994 | 8004724 |
| an overview of a feasibility study for the production of industrial enzymes in transgenic alfalfa. | the overall aims of the research are to develop genetically engineered alfalfa producing high levels of industrially important enzymes and to develop rapid methods for extracting and purifying these enzymes from alfalfa juice. using a reporter gene beta-glucuronidase (gus) as a model system, we were able to demonstrate production of a foreign protein in alfalfa and gain valuable insight into the molecular approaches required for the expression and accumulation of foreign proteins in leaf tissue. ... | 1994 | 8010673 |
| the effect of media composition on edta degradation by agrobacterium sp. | edta degradation by an agrobacterium sp. has been examined by quantifying 14c-labeled co2 produced from iron-[2-14c] edta and by measured loss of nonlabeled edta by hplc. fe-edta degradation resulted in a rise in ph, nitrate concentration, and ammonia concentration. addition of glycerol resulted in suppression of fe-edta degradation and in a decrease in ph and nh4+ concentration in the media. addition of peptone or yeast extract did not affect degradation. some of the components (e.g., biotin) o ... | 1994 | 8010772 |
| natural instability of agrobacterium vitis ti plasmid due to unusual duplication of a 2.3-kb dna fragment. | the octopine/cucumopine (o/c) ti plasmids of agrobacterium vitis carry two t regions, ta and tb. the ta region resembles the octopine tl region. the tb region contains the auxin synthesis genes tb-iaam and tb-iaah and the cucumopine synthesis gene cus. within the group of o/c isolates, strains 2608 and 2641 are closely related. however, 2641 lacks the tb region. the restriction maps of pti2608 and pti2641 were established and showed that the tb deletion resulted from intramolecular recombination ... | 1994 | 8012038 |
| production of cell-associated polysaccharides of rhizobium fredii usda205 is modulated by apigenin and host root extract. | rhizobium fredii usda205 cells were cultured in the presence of 4',5,7-trihydroxyflavone (apigenin), a compound that has been shown to induce the nod genes and other symbiosis-related genes in r. fredii. the cell-associated polysaccharides were then extracted with hot phenol/water, separated by repetitive gel filtration chromatography, and analyzed by polyacrylamide gel electrophoresis, nuclear magnetic resonance spectrometry, high-performance anion-exchange chromatography, and gas chromatograph ... | 1994 | 8012042 |
| accumulation of transcripts encoding a lipid transfer-like protein during deformation of nodulation-competent vigna unguiculata root hairs. | a cdna library was constructed from rna of vigna unguiculata root hairs harvested 1 day and 4 days after inoculation with rhizobium sp. ngr234. a heterologous probe was used to identify a cdna clone, the predicted 99-amino-acid sequence of which shares homology with a nonspecific lipid transfer protein (ltp) of hordeum vulgare. other characteristics, including an estimated molecular weight of 10.4 kd, an isoelectric point of 8.6, and a signal peptide with a hydrophobic region at the amino-termin ... | 1994 | 8012050 |
| analysis of the expression from rhizobium meliloti fix-promoters in other rhizobium backgrounds. | using translational fusions to lacz, we have measured expression from the promoters of rhizobium meliloti regulatory genes, nifa and fixk, and structural genes, nifh and fixa, in other fast-growing rhizobia whose nitrogen fixation regulation is less known. neither nifa nor fixk promoters were activated under both free-living microaerobic and symbiotic conditions, except in r. tropici, where clear symbiotic activation of either nifa or fixk expression could be observed. both nifh and fixa promote ... | 1994 | 8012569 |
| sequence and regulation of psra, a gene on the sym plasmid of rhizobium leguminosarum biover phaseoli which inhibits transcription of the psi genes. | the psr region of rhizobium leguminosarum biovar phaseoli had originally been recognized on the basis of its ability to repress the transcription of the psi genes, one of which, psia, inhibits exopolysaccharide synthesis when cloned in multi-copy plasmids. both psr and psi are located on the symbiotic plasmid prp2ji. the psra gene was localized and sequenced. the deduced amino acid sequence of psra was shown to have similarity to the dna-binding region of a family of other transcriptional regula ... | 1994 | 8012570 |
| genetic characterization of rhizobium sp. strain tal1145 that nodulates tree legumes. | rhizobium sp. strain tal1145 nodulates leucaena leucocephala and phaseolus vulgaris, in addition to a wide range of tropical tree legumes. six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. the common nod and nifa genes were situated approximately 17 kb apart, with the nodij genes in between. these clones enabled a derivative of tal1145 carrying a partially deleted psym to form ineffecti ... | 1994 | 8012908 |
| second site mutations specifically suppress the fix- phenotype of rhizobium meliloti ndvf mutations on alfalfa: identification of a conditional ndvf-dependent mucoid colony phenotype. | rhizobium meliloti mutants carrying ndvf insertion or deletion mutations induce nodules on alfalfa which contain very few infected cells and fail to fix n2 (fix-). we have characterized five independent second site mutations (designated sfx) which completely suppress the fix- phenotype of ndvf mutants on medicago sativa but not on another r. meliloti host melilotus alba. genetic mapping and phenotypic analysis revealed that the suppressor mutations sfx-1, sfx-4 and sfx-5 mapped to a single locus ... | 1994 | 8013901 |
| chromosomal location of lectin genes indicates they are not the basis of rhizobium strain specificity mutations identified in pea (pisum sativum l.). | a lectin gene family is located on linkage group 7 in pea. the lectin genes are arranged as a cluster, with no recombination observed within the multigene family. a lectin-like cdna clone, pea207, and eight dna fragments generated by random priming also were mapped in the region of the lectin genes. none of the known pea mutants altering rhizobium leguminosarum strain specificity map to this region of the genome, and therefore their altered specificities appear not to be directly produced by mut ... | 1994 | 8014459 |
| temporal and tissue-specific regulation of a brassica napus stearoyl-acyl carrier protein desaturase gene. | the nucleotide sequence of a brassica napus stearoyl-acyl carrier protein desaturase gene (bn10) is presented. this gene is one member of a family of four closely related genes expressed in oilseed rape. the expression of the promoter of this gene in transgenic tobacco was found to be temporally regulated in the developing seed tissues. however, the promoter was also particularly active in other oleogenic tissues such as the tapetum and pollen grains. this raises the interesting question of whet ... | 1994 | 8016261 |
| identification of a gene encoding a thioredoxin-like product necessary for cytochrome c biosynthesis and symbiotic nitrogen fixation in rhizobium leguminosarum. | a tn5-induced mutant of rhizobium leguminosarum bv. viciae could not form nitrogen-fixing nodules on pea or vetch because of a lesion in electron transport to oxygen. the mutant lacked spectroscopically detectable cytochromes c and aa3. no proteins containing c-type cytochrome could be identified in the mutant by heme staining of proteins fractionated on polyacrylamide gels, indicating that the mutant was defective in maturation of all c-type cytochromes. the tn5 mutation was determined to be lo ... | 1994 | 8021193 |
| flavone-enhanced accumulation and symbiosis-related biological activity of a diglycosyl diacylglycerol membrane glycolipid from rhizobium leguminosarum biovar trifolii. | rhizobium leguminosarum bv. trifolii is the bacterial symbiont which induces nitrogen-fixing root nodules on the leguminous host, white clover (trifolium repens l.). in this plant-microbe interaction, the host plant excretes a flavone, 4',7-dihydroxyflavone (dhf), which activates expression of modulation genes, enabling the bacterial symbiont to elicit various symbiosis-related morphological changes in its roots. we have investigated the accumulation of a diglycosyl diacylglycerol (bf-7) in wild ... | 1994 | 8021221 |
| eudistomin u and isoeudistomin u, new alkaloids from the caribbean ascidian lissoclinum fragile. | chemical investigations of the caribbean ascidian lissoclinum fragile (didemnidae) have resulted in the isolation of new alkaloids which we have designated eudistomin u [1] and isoeudistomin u [2]. their structures were determined by spectrometric and chemical means. | 1994 | 8021654 |
| two novel families of bacterial membrane proteins concerned with nodulation, cell division and transport. | homology has been established for members of two families of functionally related bacterial membrane proteins. the first family (the resistance/nodulation/cell division (rnd) family) includes (i) two metal-resistance efflux pumps in alcaligenes eutrophus (czca and cnra), (ii) three proteins which function together in nodulation of alfalfa roots by rhizobium meliloti (noighi), and (iii) a cell division protein in escherichia coli (envd). the second family (the putative membrane fusion protein (mf ... | 1994 | 8022262 |
| enhanced recovery of transformants of agrobacterium tumefaciens after freeze-thaw transformation and drug selection. | freeze-thaw transformation provides a simple and rapid method to transform agrobacterium tumefaciens directly with plasmid dna. competent a. tumefaciens cells of strains lba4404, gv3850 and eha101 were transformed with four to nine plasmids differing in size, size of insert and in some cases sensitivity to antibiotics. a threefold to fourfold increase in transformed colonies per microgram of dna was obtained by freezing cells with liquid nitrogen vs. dry ice/ethanol. freezing cells in liquid nit ... | 1994 | 8024787 |
| heme-based sensors, exemplified by the kinase fixl, are a new class of heme protein with distinctive ligand binding and autoxidation. | fixl's are chimeric heme protein kinases from symbiotic nitrogen-fixing rhizobia. we have overexpressed three fixl variants in escherichia coli. bradyrhizobium japonicum fixl, a soluble dimeric protein, is the first full-length fixl to be purified. the other two proteins are soluble truncations of rhizobium meliloti fixl, which is a membrane protein. one contains both heme and kinase domains and is dimeric; the other has only the heme domain and is monomeric. we find that all the fixl's bind oxy ... | 1994 | 8025112 |
| effects of organic acids and low ph on rhizobium meliloti 104a14. | in the symbiotic relationship between rhizobium meliloti and alfalfa (medicago sativa), the bacteria are enclosed within the plant cell by a membrane that may function like a plant vacuolar membrane and maintain a ph between 5.5 and 6.0. free-living rhizobium meliloti 104a14 is sensitive to ph in this range and its sensitivity was influenced by the presence of acetate and other monocarboxylic acids. r. meliloti can grow at ph 6.0 in 3 mm succinate but does not grow at ph 6.2 if 10 mm acetate is ... | 1994 | 8025689 |
| construction of multipurpose gene cartridges based on a novel synthetic promoter for high-level gene expression in gram-negative bacteria. | a series of gene cartridges containing a novel synthetic promoter (psyn) was constructed. the psyn sequence is based on the consensus of a number of naturally occurring promoters and displays strong activity in escherichia coli and rhizobium leguminosarum. in a direct comparison, psyn proved to be about twice as strong as the tac promoter in e. coli, while the difference in rhizobium was about tenfold. a small psyn cartridge was constructed by adding a shine-dalgarno sequence, an atg codon, and ... | 1994 | 8026755 |
| identification of a rhizobium leguminosarum gene homologous to nodt but located outside the symbiotic plasmid. | an open reading frame (orf471), homologous to nodt from rhizobium leguminosarum, has been found outside the symbiotic plasmid. the deduced amino-acid sequence indicates that the gene product is an outer membrane lipoprotein similar to the nodt proteins. this orf seems to be widespread among r. leguminosarum bv. viciae strains and its presence in the genetic background of different strains may explain the lack of a nodulation-deficient phenotype found in such strains carrying a nod mutation. | 1994 | 8026763 |
| specific, high affinity binding of chitin fragments to tomato cells and membranes. competitive inhibition of binding by derivatives of chitooligosaccharides and a nod factor of rhizobium. | suspension-cultured tomato cells have a sensitive perception system for chitin fragments with a degree of polymerization (dp) > or = 4 and react to these compounds with a transient alkalinization of their culture medium (felix, g., regenass, m., and boller, t. (1993) plant. j. 4, 307-316). a chitin fragment with dp 5 was aminated at the reducing end and coupled to t-butoxycarbonyl-l-[35s]methionine via an amidoglycine spacer. the radiolabeled chitin fragment (approximately 1000 ci/mmol) exhibite ... | 1994 | 8027050 |
| transgenic tomato lines containing ds elements at defined genomic positions as tools for targeted transposon tagging. | we have introduced a genetically marked dissociation transposable element (dshpt) into tomato (lycopersicon esculentum) by agrobacterium tumefaciens-mediated transformation. probes for the flanking regions of the t-dna and transposed dshpt elements were obtained with the inverse polymerase chain reaction (ipcr) technique and used in rflp linkage analyses. the rflp map location of 11 t-dnas carrying dshpt was determined. the t-dnas are distributed on 7 of the 12 tomato chromosomes. to explore the ... | 1994 | 8028583 |
| sequence of the cellular t-dna in the untransformed genome of nicotiana glauca that is homologous to orfs 13 and 14 of the ri plasmid and analysis of its expression in genetic tumours of n. glauca x n. langsdorffii. | a region homologous to the tl-dna of agrobacterium rhizogenes was previously detected in the genome of untransformed nicotiana glauca and designated cellular t-dna (ct-dna). subsequently, part of this region was sequenced and two genes, which corresponded to rolb and rolc and were named ngrolb and ngrolc, were found. we have now sequenced a region of the ct-dna other than the region that includes ngrolb and c and we have found two other open reading frames (orfs), ngorf13 and ngorf14. these orfs ... | 1994 | 8028588 |
| analysis of the involvement of ocs-like bzip-binding elements in the differential strength of the bidirectional mas1'2' promoter. | the ocs-like elements of the bidirectional mas1'2' promoter of agrobacterium tumefaciens, mas1' and mas2', were analyzed to elucidate their role in the expression conferred by this promoter. tetramers of the elements were cloned upstream of the beta-glucuronidase-coding region linked to the 35s promoter deleted at -54. transient expression assays with tobacco (nicotiana tabacum) and potato (solanum tuberosum) protoplasts showed that tetramers of the mas1' element had 3- to 8-fold enhancing activ ... | 1994 | 8029353 |
| siderophore activity in rhizobium species isolated from different legumes. | rhizobium strains isolated from nodules of the different legumes including wild-growing plants were examined for their siderophore activity. fifteen of the 84 screened rhizobial strains were able to grow under conditions of limited iron supply. nine of them gave orange halos in the assay with chrom azurol s. among these strains were rhizobium sp. (ononis) and rhizobium (genista), producing hydroxamates and phenolates. these compounds could promote the growth of siderophore-negative bacteria on i ... | 1994 | 8030377 |
| soybean gh3 promoter contains multiple auxin-inducible elements. | the soybean gh3 gene is transcriptionally induced in a wide variety of tissues and organs within minutes after auxin application. to determine the sequence elements that confer auxin inducibility to the gh3 promoter, we used gel mobility shift assays, methylation interference, deletion analysis, linker scanning, site-directed mutagenesis, and gain-of-function analysis with a minimal cauliflower mosaic virus 35s promoter. we identified at least three sequence elements within the gh3 promoter that ... | 1994 | 8038604 |
| a protein binding at-rich sequence in the soybean leghemoglobin c3 promoter is a general cis element that requires proximal dna elements to stimulate transcription. | a nodule nuclear factor, nat2, interacts with two at-rich binding sites (nat2 bs1 and nat2 bs2) in the soybean leghemoglobin (lb) c3 promoter. in transgenic lotus corniculatus nodules, an oligonucleotide containing nat2 bs1 activated an inactive -159 lbc3 promoter when placed immediately upstream of the promoter. the activation was independent of the orientation of nat2 bs1 but was dependent on its position in the promoter. the abilities of different mutated binding sites to activate expression ... | 1994 | 8038605 |
| the rolc promoter of agrobacterium rhizogenes ri plasmid is activated by sucrose in transgenic tobacco plants. | the 5'-upstream region of the rolc gene of the ri plasmid is expressed specifically in phloem cells of transgenic higher plants. in this study, we demonstrated that the rolc promoter is activated by sucrose in phloem cells of transgenic tobacco seedlings bearing rolc promoter-uida chimeric fusion gene. since the rolc promoter is not activated by sorbitol, sucrose metabolism rather than osmotic pressure exerted by the disaccharide may be responsible for induction. thus, experiments using 5'-upstr ... | 1994 | 8041357 |