Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| in vivo packaging of cosmids in transposon-mediated mutagenesis. | a technique was developed that permits the analysis of large regions of dna by transposition mutagenesis. large fragments of the ptia6nc plasmid were cloned into the broad host range cosmid phk17 and subjected to transposition mutagenesis by tn3. cosmids containing tn3 insertions were selected by in vivo packaging by lambda ci857 and transduction to a new host. the insertions were localized by dna restriction endonuclease analysis and transferred to the ti-plasmid by marker exchange. | 1983 | 6296041 |
| localization of symbiotic mutations in rhizobium meliloti. | a total of 5 nod- and 57 fix- symbiotic mutants of rhizobium meliloti strain 41 have been isolated after either nitrosoguanidine or tn5 transposition mutagenesis. chromosomal locations of mutations in 1 nod- and 11 fix- derivatives were ascertained by transferring the chromosome (mobilized by plasmid r68.45), in eight fragments, into symbiotically effective recipients and testing the recombinants for symbiotic phenotype. alternatively, the kanamycin resistance marker of tn5 was mapped. in five m ... | 1983 | 6296048 |
| mutational analysis of the virulence region of an agrobacterium tumefaciens ti plasmid. | forty-nine tn3 and tn5 transposition insertion mutations were introduced into the virulence region of the ptia6nc plasmid of agrobacterium tumefaciens. five tn5 transposition mutations from an earlier study (d. garfinkel and e. nester, j. bacteriol. 144:732-743, 1980) were also mapped more accurately. these mutations defined five separate loci within the virulence region. two tn3 insertions into one of these loci, vira, result in a strain which is only weakly virulent; however, a tn5 insertion i ... | 1983 | 6296058 |
| physical and genetic characterization of rhizobium meliloti symbiotic mutants. | a set of 19 symbiotic mutants of rhizobium meliloti obtained by a tn5 "suicide plasmid" mutagenesis procedure was characterized genetically and physically. as part of this characterization, we showed that r. meliloti strain 1021, like other r. meliloti strains, contains a very large indigenous plasmid (greater than 300 md) that carries the structural genes for nitrogenase (nifhdk genes). among the 19 symbiotic mutations studied, at least six were shown to reside on the megaplasmid. by a "walking ... | 1983 | 6363587 |
| klebsiella pneumoniae nifa product activates the rhizobium meliloti nitrogenase promoter. | bacteria in the genus rhizobium normally fix nitrogen only when they interact with leguminous plants to produce on the roots a highly differentiated structure, the nodule, within which the bacteria differentiate into nitrogen-fixing bacteroids. by contrast, the enteric bacterium klebsiella pneumoniae reduces nitrogen in a free-living state in conditions of low oxygen tension and deficiency of fixed nitrogen. in k. pneumoniae, the overall circuitry by which nitrogen-fixation (nif) genes are regul ... | 1983 | 6338395 |
| rhizobium infection and nodulation: a beneficial plant disease? | 1983 | 6357057 | |
| detoxification of pesticides by microbial enzymes. | 1983 | 6357841 | |
| parasitic origins of nitrogen-mixing rhizobium-legume symbioses. a review of the evidence. | this paper is divided into two sections. the first part (i) reviews the literature on the legume-rhizobium association with emphasis on the processes leading to the establishment of the association. in the second part (ii) it is proposed that the legume-rhizobium association was originally necrotrophic , beginning when the free-living, nitrogen-fixing, saprotrophic rhizobium developed the ability to infect the plant. the pre-infection events, infection processes and nodulation in the colonizatio ... | 1983 | 6370330 |
| [genetic manipulation of plant cells]. | 1983 | 6324283 | |
| liposomes as carriers for intracellular delivery of nucleic acids. | 1983 | 6193396 | |
| localization of nodulation gene on the chromosome of rhizobium meliloti. | using n-methyl-n'-nitro-n-nitrosoguanidine mutant rm54 of rhizobium meliloti l5-30 defective in the nodulation process (nod-) and in the biosynthesis of adenine was obtained. nod- phenotype of this mutant was not caused by the auxotrophic mutation. the nod gene is located on the chromosome. the wild type strain of r. meliloti and nod- mutant rm54 harbour two indigenous plasmids having a molecular weight of 90 mdal and about 300 mdal. | 1983 | 6194660 |
| symbiotic properties of adenine requiring mutants of rhizobium meliloti strain l5-30. | from the effective and prototrophic rhizobium meliloti strain l5-30 two auxotrophic mutants were isolated: rm4 and rm221. these two mutants required adenine and adenine with thiamine for their growth, respectively. both mutants nodulated lucerne plants ineffectively. electron microscopic observations of the nodule tissue showed that its cells were not occupied by bacteria. prototrophic revertants and transductants of these mutants showed high symbiotic effectiveness. it is assumed that adenine o ... | 1983 | 6194661 |
| characterization of the lipopolysaccharide from the nod mutant of rhizobium trifolii. | lipopolysaccharides (lps) from the non-nodulating rhizobium trifolii 24sm 15 and from the nodulating r. trifolii 24sm 13 were isolated and examined by means of gas-liquid chromatography and mass spectrometry. analysis of lps showed these preparations from both strains examined contained lipid a, 2-keto-3-deoxyoctonate, neutral sugars, amino sugars, and trace amounts of amino acids. in 24sm 13 lps prevailed glucose and rhamnose whereas lps from the non-nodulating strain sm 15 contained mainly man ... | 1983 | 6194662 |
| isolation and characterization of mutants of cowpea rhizobium defective in nitrate uptake system. | in this communication, two mutants of cowpea rhizobium cb756 (nr-18 and nr-23), defective in nitrate uptake system, were described. they failed to grow in a medium where nitrate was the sole source of nitrogen and unable to show nitrate reductase activity in cell suspensions. however, they showed nitrate reductase activity (to the level of wild type) in cell-free extract preparations. thus it appears that in these mutants, the transport genes of nitrate uptake were affected and the synthesis of ... | 1983 | 6194663 |
| chromosomal gene controlling symbiotic nitrogen fixation in rhizobium meliloti l5-30. | auxotrophic rhizobium meliloti strain rm 246 carries two independent mutations: in the biosynthesis of cysteine (cys) and symbiotic nitrogen fixation process (fix). these two mutations were mapped by transduction between his-240 and ade-4 markers. cotransduction frequencies show the following order of genes: his-240 fix-1 cys-246 ade-4. | 1983 | 6194666 |
| molecular characterization of tn5-induced symbiotic (fix-) mutants of rhizobium meliloti. | to investigate the expression of specific symbiotic genes during the development of nitrogen-fixing root nodules, we conducted a systematic analysis of nodule-specific proteins and rnas produced after the inoculation of alfalfa roots with a series of rhizobium meliloti mutants generated by site-directed transposon tn5 mutagenesis. the mutagenized region of the rhizobium genome covered approximately 10 kilobases and included the region encoding the nitrogenase polypeptides. all mutant strains tha ... | 1983 | 6196347 |
| structure of the rigid-layer of rhizobium cell wall. iii. electron microscopic evidence for the cellulose microfibrils association with peptidoglycan sacculi. | the morphology of peptidoglycan layer of rhizobium cell wall was examined by transmission electron microscopy. peptidoglycans were isolated from intact cells after treatment with sodium dodecyl sulfate, extraction with aqueous 45% phenol and then with a mixture of chloroform-methanol. finally rigid layers were digested with trypsin and chymotrypsin. the results indicate the presence of lump or bar-like structures on the surface of the cell shaped peptidoglycan sacculi. evidence is provided sugge ... | 1983 | 6196947 |
| the role of cytosine methylation in the control of nopaline synthase gene expression in a plant tumor. | the ft37/1 tumor line induced by agrobacterium tumefaciens on flax epicotyls contains 22-24 copies of the t-dna encoded nopaline synthase gene per cell. all the gene copies are methylated to some extent but the methylation is not uniform, nor does it reflect the methylation level of the flanking plant dna. this extensive methylation correlates with an extremely low level of expression of the nopaline synthase gene. treatment of the tumor line with the in vivo demethylating drug 5-azacytidine at ... | 1983 | 6198416 |
| promoters regulated by the glng (ntrc) and nifa gene products share a heptameric consensus sequence in the -15 region. | we have determined the nucleotide sequences of the klebsiella pneumoniae nifl (regulation of n2 fixation genes) and the escherichia coli glna (glutamine synthetase) promoters. we compared these sequences with the published sequences of three other promoters that, like the nifl and glna promoters, are activated by the general nitrogen regulators glnf (ntra) and glng (ntrc). the three promoters are the argtr (arginine transport) and dhua (histidine transport) promoters of salmonella typhimurium an ... | 1983 | 6133280 |
| cloning of the glutamine synthetase i gene from rhizobium meliloti. | glutamine synthetase is a major enzyme in the assimilation of ammonia by members of the genus rhizobium. two forms of glutamine synthetase are found in members of the genus rhizobium, a heat-stable glutamine synthetase i (gsi) and a heat-labile gsii. as a step toward clarifying the role of these enzymes in symbiotic nitrogen fixation, we have cloned the structural gene for gsi from rhizobium meliloti 104a14. a gene bank of r. meliloti was constructed by using the bacteriophage p4 cosmid pmk318. ... | 1983 | 6137474 |
| cloning of the symbiotic region of rhizobium leguminosarum: the nodulation genes are between the nitrogenase genes and a nifa-like gene. | the region of the rhizobium leguminosarum plasmid prl1ji involved in nodulation and nitrogen fixation has been cloned on a series of four overlapping cosmid clones. these clones represent 60 kb of prl1ji dna on which a series of tn5-induced fix and nod alleles have been identified, with the two most distant alleles being separated by 45 kb of dna. the mutant alleles fell into three groups, two clusters of fix alleles separated by one cluster of nod alleles. within one group of fix alleles, dna h ... | 1983 | 16453461 |
| nodule-specific host proteins in effective and ineffective root nodules of pisum sativum. | nodule-specific root proteins - so called nodulins - were identified in root nodules of pea plants by an immunological assay. nodulin patterns were examined at different stages of nodule development. about 30 nodulins were detectable during development. some were preferentially synthesized before nitrogen fixation started, whereas the majority were synthesized concomitantly with leghaemoglobin. some of the nodulins were located within the peribacteroid membrane. ineffective rhizobium strains (a ... | 1983 | 16453462 |
| nickel: a micronutrient element for hydrogen-dependent growth of rhizobium japonicum and for expression of urease activity in soybean leaves. | soybean plants and rhizobium japonicum 122 des, a hydrogen uptake-positive strain, were cultured in media purified to remove ni. supplemental ni had no significant effect on the dry matter or total n content of plants. however, the addition of ni to both nitrate-grown and symbiotically grown plants resulted in a 7- to 10-fold increase in urease activity (urea amidohydrolase, ec 3.5.1.5) in leaves and significantly increased the hydrogenase activity (ec 1.18.3.1) in isolated nodule bacteroids. wh ... | 1983 | 16578770 |
| congo red absorption by rhizobium leguminosarum. | congo red absorption is generally considered a contraindication of rhizobium. however, r. leguminosarum takes up the dye on yeast extract-mannitol agar. the uptake of congo red varies among strains of r. leguminosarum, as shown elsewhere with strains of r. trifolii and r. meliloti. congo red absorption does not distinguish rhizobia from other bacteria, but may be useful as a strain marker. | 1983 | 16346177 |
| production of antimicrobial and bacteriocin-like substances by rhizobium trifolii. | rhizobium trifolii strains iari and rel-1 produced substances with broad and narrow activity spectra, respectively. reproducible inhibitory zones of various sizes produced by r. trifolii iari (2 to 14 mm) and r. trifolii rel-1 (2 to 6 mm) were detected, depending upon the indicator organism used. the maximum production of these substances by both strains of r. trifolii was observed on l-arabinose agar. a preliminary characterization of the antimicrobial substance produced by strain iari showed r ... | 1983 | 16346202 |
| population changes and persistence of rhizobium phaseoli in soil and rhizospheres. | the impact of legume cultivation on the establishment and persistence of an inoculant strain of rhizobium phaseoli and its ability to compete with a resident population of r. phaseoli for nodule occupancy was examined utilizing strain-specific fluorescent antibodies. the soil (hubbard loamy sand) was inoculated homogeneously with 5 x 10 cells per g of soil and confined in plastic cylinders kept in field plots. inoculated and uninoculated cylinders were either left fallow or planted to two seeds ... | 1983 | 16346203 |
| survival of rhizobium phaseoli in coal-based legume inoculants applied to seeds. | eight coals used as carriers in legume inoculants promoted the survival of rhizobium phaseoli on pinto bean seeds. although peat was more protective, most coal-based inoculants provided >10 viable rhizobia per seed after 4 weeks. | 1983 | 16346218 |
| free-living rhizobium strain able to grow on n(2) as the sole nitrogen source. | a rhizobium strain isolated from stem nodules of the legume sesbania rostrata was shown to grow on atmospheric nitrogen (n(2)) as the sole nitrogen source. non-n(2)-fixing mutants isolated directly on agar plates formed nodules that did not fix n(2) when inoculated into the host plant. | 1983 | 16346220 |
| identification of rhizobium phaseoli strains that are tolerant or sensitive to soil acidity. | a study was conducted to determine whether the survival of rhizobium phaseoli in acid soils could be predicted on the basis of the tolerance of the organism to acidity in culture. of 16 strains tested, all grew in culture at ph 4.6, but only those that grew at ph 3.8 survived in soils having ph values of 4.1 to 4.6. strains that tolerated the lowest ph values in culture were tolerant of the highest aluminum concentrations. in one acid soil, an acid-tolerant strain was unable to survive in number ... | 1983 | 16346239 |
| hydrogen recycling by rhizobium leguminosarum isolates and growth and nitrogen contents of pea plants (pisum sativum l.). | the ability to recycle h(2) evolved by nitrogenase is thought to be of importance in increasing the efficiency of n(2) fixation and to be a factor in increasing plant yield in symbiotic systems. to determine whether this ability is a significant factor in the rhizobium leguminosarum-pisum sativum l. system, plants were inoculated with r. leguminosarum isolates which differed in their ability to oxidize h(2) and in their relative efficiency of n(2) fixation. these plants were grown at three level ... | 1983 | 16346248 |
| rapid colony screening method for identifying hydrogenase activity in rhizobium japonicum. | a method has been developed for the rapid screening of rhizobium japonicum colonies for hydrogenase activity based on their ability to reduce methylene blue in the presence of respiratory inhibitors and hydrogen. hydrogen uptake-positive (hup) colonies derepressed for hydrogenase activity were visualized by their localized decolorization of filter paper disks impregnated with the dye. appropriate responses were seen with a number of hup and hup wild-type strains of r. japonicum as well as hup mu ... | 1983 | 16346252 |
| competition among rhizobium leguminosarum strains for nodulation of lentils (lens esculenta). | thirty-one cultures of rhizobium leguminosarum were screened for effectiveness (c(2)h(2) reduction) on lentils (lens esculenta). fluorescent antibodies prepared against three of the most effective strains (hawaii 5-0, nitragin 92a3, and nitragin 128a12) exhibited a high degree of strain specificity; the antibodies reacted strongly with their homologous rhizobia in culture and with bacteroids in nodules. they did not cross-react with one another, and only weakly with 5 of the 47 other r. legumino ... | 1983 | 16346257 |
| physiology of ex planta nitrogenase activity in rhizobium japonicum. | thirty-nine wild-type strains of rhizobium japonicum have been studied for their ability to synthesize nitrogenase ex planta in defined liquid media under microaerobic conditions. twenty-one produced more than trace amounts of acetylene reduction activity, but only a few of these yielded high activity. the oxygen response curves were similar for most of the nitrogenase-positive strains. the strains derepressible for activity had several phenotypic characteristics different from non-derepressible ... | 1983 | 16346295 |
| effects of carrier and temperature on survival of rhizobium spp. in legume inocula: development of an improved type of inoculant. | the effects of inoculant carrier, temperature, and storage period on the survival of rhizobium strains were determined by plate count and most-probable-number analyses. preliminary experiments showed that survival of rhizobia was affected by each of these factors and their interactions. results of further studies indicated that six strains of rhizobia survived better at high temperatures when lyophilized and suspended in an oil carrier as compared to finely ground peat. the oil base inocula cont ... | 1983 | 16346313 |
| evaluation of nitrate reductase activity in rhizobium japonicum. | nitrate reductase activity was evaluated by four approaches, using four strains of rhizobium japonicum and 11 chlorate-resistant mutants of the four strains. it was concluded that in vitro assays with bacteria or bacteroids provide the most simple and reliable assessment of the presence or absence of nitrate reductase. nitrite reductase activity with methyl viologen and dithionite was found, but the enzyme activity does not confound the assay of nitrate reductase. | 1983 | 16346376 |
| competition of rhizobium japonicum strains in early stages of soybean nodulation. | the effects of preexposure of soybean (glycine max l. merrill) roots to rhizobium japonicum strains and subsequent establishment of other strains in the nodules were investigated by using combinations of effective strains (usda 110 and usda 138) and effective-ineffective strains (usda 110 and sm-5). strain usda 110 was a better competitor than either usda 138 or sm-5 on cultivars lee and peking. however, when either of the two less-competitive strains was inoculated into 2-day-old seedlings befo ... | 1983 | 16346400 |
| interaction of agromyces ramosus with other bacteria in soil. | agromyces ramosus occurs in very high numbers in most soils and, based on studies of laboratory isolates, does not require host cells for growth. nevertheless, it attacked and destroyed most of the gram-positive and gram-negative bacterial species tested as possible host organisms. a. ramosus also attacked and destroyed saccharomyces cerevisiae. the possibility of attack on fungi was unclear. among the bacteria serving as hosts were the important soil species azotobacter vinelandii, rhizobium le ... | 1983 | 16346402 |
| possible involvement of a megaplasmid in nodulation of soybeans by fast-growing rhizobia from china. | several isolates from a newly described group of fast-growing acid-producing soybean rhizobia, rhizobium japonicum, were analyzed for plasmid content. all contained from one to four plasmids with molecular weights of 100 x 10 or larger. although most of the isolates shared plasmids of similar size, the restriction endonuclease (bamhi, ecori, and hindiii) patterns of the plasmids from three of the isolates were vastly different. growth in the presence of acridine orange was effective in producing ... | 1983 | 16346403 |
| effect of acidity on the composition of an indigenous soil population of rhizobium trifolii found in nodules of trifolium subterraneum l. | acidity affected which members of an indigenous soil population of rhizobium trifolii nodulated trifolium subterraneum l. cv. mt. barker. in three experiments involving plants grown either in mineral salts agar adjusted to ph 4.8 or 6.8 and inoculated with a soil suspension or grown directly in samples of unamended soil (ph 4.8) or soil amended with caco(3) (ph 6.4), 121 of 151 isolates of r. trifolii were placed into four serogroups. seventy-nine of these isolates were placed into two serogroup ... | 1983 | 16346425 |
| free-living rhizobium strain able to grow on n(2) as the sole nitrogen source. | [this corrects the article on p. 711 in vol. 45.]. | 1983 | 16346430 |
| motility and chemotaxis of rhizobium meliloti in soil. | the spreading of rhizobium meliloti strains in various autoclaved soils was measured by using simple modifications of established techniques. behavioral mutants were used to demonstrate that efficient spreading requires active motility and chemotaxis. the rate of spreading was affected by physical or chemical differences among soils and by changes in water content. | 1983 | 16346435 |
| analysis of poly-beta-hydroxybutyrate in rhizobium japonicum bacteroids by ion-exclusion high-pressure liquid chromatography and uv detection. | ion-exclusion high-pressure liquid chromatography (hplc) was used to measure poly-beta-hydroxybutyrate (phb) in rhizobium japonicum bacteroids. the products in the acid digest of phb-containing material were fractionated by hplc on aminex hpx-87h ion-exclusion resin for organic acid analysis. crotonic acid formed from phb during acid digestion was detected by its intense absorbance at 210 nm. the aminex-hplc method provides a rapid and simple chromatographic technique for routine analysis of org ... | 1983 | 16346443 |
| the conserved part of the t-region in ti-plasmids expresses four proteins in bacteria. | the t-region of ti-plasmids expresses four proteins (mol. wts. 74,000, 49,000, 28,000 and 27,000) in escherichia coli minicells. promoter activities are determined by sequences within the t-region, and the protein-coding regions map in that part of the t-region which is highly conserved in octopine and nopaline plasmids and which is responsible for shoot and root inhibition when expressed in plant cells. three of the regions expressed in bacteria correlate with three regions which are transcribe ... | 1983 | 11894956 |
| intergeneric transfer and exchange recombination of restriction fragments cloned in pbr322: a novel strategy for the reversed genetics of the ti plasmids of agrobacterium tumefaciens. | transmission of cole1/pmb1-derived plasmids, such as pbr322, from escherichia coli donor strains was shown to be an efficient way to introduce these plasmids into agrobacterium. this was accomplished by using e. coli carrying the helper plasmids pgj28 and r64drd11 which provide the cole1 mob functions and tra functions, respectively. for example, the broad host-range replication plasmid, pgv1150, a co-integrate plasmid between pbr322 and the w-type mini-sa plasmid, pgv1106, was transmitted from ... | 1983 | 11894957 |
| identification of sequences involved in the polyadenylation of higher plant nuclear transcripts using agrobacterium t-dna genes as models. | sequences in the 3'-untranslated region of two different octopine t-dna genes were analyzed with regard to their significance in polyadenylation. poly(a) addition sites were localized precisely by s1 nuclease mapping with t-dna-derived mrnas isolated from tobacco. the gene encoding transcript 7' contains two aataaa hexanucleotides, respectively 119 bp and 170 bp downstream of the taa stop codon. a single poly(a) site was mapped 24-25 bp downstream of the first aataaa. further, we show that a mut ... | 1983 | 11894958 |
| significance of hydrogen evolution in the carbon and nitrogen economy of nodulated cowpea. | the carbon and nitrogen economies of a single cultivar of cowpea (vigna unguiculata (l.) walp.cv caloona) nodulated with either a high h(2)-evolving strain (176a27) or a low h(2)-evolving strain (cb756) of rhizobium were compared. the two symbioses did not differ in total dry matter production, seed yield, nitrogen fixed, the spectrum of nitrogenous solutes produced by nodules for export, or the partitioning of net photosynthate within the plant throughout the growth cycle. detailed examination ... | 1983 | 16662769 |
| cytochromes of rhizobium japonicum 61a76 bacteroids from soybean nodules. | bacteroids of rhizobium japonicum 61a76 were isolated from nodules of field-grown soybean plants by sucrose density gradient fractionation. the major cytochromes, aa(3), b, c, and possibly o were present in the bacteroids throughout the active nitrogen-fixing life of the nodule. this is in contrast with previous reports using other r. japonicum strains in which cyotchromes aa(3) and o were not found. | 1983 | 16662786 |
| a comparison of the surface polysaccharides from rhizobium leguminosarum 128c53 smrif with the surface polysaccharides from its exo mutant. | the surface polysaccharides of rhizobium leguminosarum 128c53 sm(r)rif(r) (parent) and its exo(-1) mutant were isolated and characterized. the parent carries out normal symbiosis with its host, pea, while the exo(-1) mutant does not nodulate the pea. the following observations were made. (a) the parent produces lipopolysaccharide (lps), typical acidic extracellular polysaccharide (eps), and three additional polysaccharides, ps1, ps2, and ps3. the ps1 and ps2 fractions are likely to be the capsul ... | 1983 | 16662808 |
| nitrate and nitrite reduction in relation to nitrogenase activity in soybean nodules and rhizobium japonicum bacteroids. | soybean (glycine max l. cv williams) seeds were sown in pots containing a 1:1 perlite-vermiculite mixture and grown under greenhouse conditions. nodules were initiated with a nitrate reductase expressing strain of rhizobium japonicum, usda 110, or with nitrate reductase nonexpressing mutants (nr(-) 108, nr(-) 303) derived from usda 110. nodules initiated with either type of strain were normal in appearance and demonstrated nitrogenase activity (acetylene reduction). the in vivo nitrate reductase ... | 1983 | 16662897 |
| effect of the host legume on acetylene reduction and hydrogen evolution by rhizobium nitrogenase. | the relative efficiency (re) of n(2) fixation (re = 1 - [h(2) evolved in air]/[acetylene reduced]) was investigated in a rhizobium strain lacking uptake hydrogenase activity (hup(-)). variation in re of such strains presumably reflects changes in the electron allocation coefficient of nitrogenase. by artificially extending the normal dark period of 24-day-old pisum sativum l. cv ;alaska' inoculated with the hup(-)r. leguminosarum strain 3740, reproducible changes in re were obtained. the re show ... | 1983 | 16662950 |
| enzymes of ureide synthesis in pea and soybean. | soybean (glycine max) and pea (pisum sativum) differ in the transport of fixed nitrogen from nodules to shoots. the dominant nitrogen transport compounds for soybean are ureides, while amides dominate in pea. a possible enzymic basis for this difference was examined.the level of enzymes involved in the formation of the ureides allantoin and allantoic acid from inosine 5'-monophosphate (imp) was compared in different tissues of pea and soybean. two enzymes, 5'-nucleotidase and uricase, from soybe ... | 1983 | 16662981 |
| metabolism of c-labeled photosynthate and distribution of enzymes of glucose metabolism in soybean nodules. | the metabolism of translocated photosynthate by soybean (glycine max l. merr.) nodules was investigated by (14)co(2)-labeling studies and analysis of nodule enzymes. plants were exposed to (14)co(2) for 30 minutes, followed by (12)co(2) for up to 5 hours. the largest amount of radioactivity in nodules was recovered in neutral sugars at all sampling times. the organic acid fraction of the cytosol was labeled rapidly. although cyclitols and malonate were found in high concentrations in the nodules ... | 1983 | 16663058 |
| effect of rhizobial strain and host plant on nitrogen isotopic fractionation in legumes. | lotus pedunculatus l., medicago sativa l., macroptilium atropurpureum, glycine max, and trifolium repens l. were grown in a n-free medium and inoculated with one of ten rhizobium strains. dry matter, n content, and delta(15)n values were determined for various plant parts.nodules, with the exception of those from lucerne, were enriched in (15)n relative to atmospheric n. considerable variation was found in delta(15)n values of plant herbage (-4.5 to +0.8). the extent of isotopic discrimination w ... | 1983 | 16663110 |
| host plant cultivar effects on hydrogen evolution by rhizobium leguminosarum. | the effect of host plant cultivar on h(2) evolution by root nodules was examined in symbioses between pisum sativum l. and selected strains of rhizobium leguminosarum. hydrogen evolution from root nodules containing rhizobium represents the sum of h(2) produced by the nitrogenase enzyme complex and h(2) oxidized by any uptake hydrogenase present in those bacterial cells. relative efficiency (re) calculated as re = 1 - (h(2) evolved in air/c(2) h(2) reduced) did not vary significantly among ;felt ... | 1983 | 16663112 |
| role of inosine monophosphate oxidoreductase in the formation of ureides in nitrogen-fixing nodules of cowpea (vigna unguiculata l. walp.). | cell-free extracts from nodules of cowpea (vigna unguiculata l. (walp.) cv caloona:rhizobium strain cb756) prepared in the presence of 15% (v/v) glycerol showed high rates (30 to 60 nanomoles nad reduced per minute per gram fresh weight nodule) of inosine monophosphate oxidoreductase (ec 1.2.1.14) activity. the enzyme was labile (half-life of activity less than 3 hours) but could be stabilized for up to 18 hours by inclusion of the substrates nad and inosine monophosphate in the breaking media. ... | 1983 | 16663115 |
| a rapid regulatory response governing nodulation in soybean. | the number of nodules which develop on the primary root of soybean seedlings (glycine max l. merr) after inoculation with rhizobium japonicum is substantially diminished in the region of the root developmentally 10 to 15 hours younger than the region maximally susceptible to nodulation at the time of inoculation. this rapid inhibition of nodulation has been investigated by inoculating soybean seedlings with rhizobia at two different times, 15 hours apart. living r. japonicum cells, but not heter ... | 1983 | 16663209 |
| phytohormones, rhizobium mutants, and nodulation in legumes : iii. auxin metabolism in effective and ineffective pea root nodules. | high specific activity [(3)h]indole-3-acetic acid (iaa) was applied to the apical bud of intact pea (pisum sativum l. cv greenfeast) plants. radioactivity was detected in all tissues after 24 hours. more radioactivity accumulated in the nodules than in the parent root on a fresh weight basis and more in effective (nitrogen-fixing) nodules than in ineffective nodules (which do not fix nitrogen).for most samples, thin layer chromatography revealed major peaks of radioactivity at the r(f) values of ... | 1983 | 16663219 |
| effect of temperature on nitrogenase functioning in cowpea nodules. | nitrogenase (ec 1.7.99.2) activity of a cowpea (vigna unguiculata (l.) walp cv caloona) symbiosis formed with a rhizobium strain (176a27) lacking uptake hydrogenase and maintained under conditions of a 12-hour day at an air temperature of 30 degrees c (800-1000 microeinsteins per square meter per second) and a 12-hour night at an air temperature of 20 degrees c showed a marked diurnal variation in ratio of nitrogen fixed to hydrogen evolved. as little as 0.3 micromole nitrogen was fixed per micr ... | 1983 | 16663226 |
| construction of a rhizobium japonicum gene bank and use in isolation of a hydrogen uptake gene. | a gene bank of rhizobium japonicum dna was constructed by using the broad host range conjugative cosmid plafr1. eighty-three percent of the clones in the bank contained cosmids with insert dna averaging 22.6 kilobase pairs in length. a series of cosmids containing a hydrogen uptake (hup) gene was identified by transferring the gene bank into a h(2) uptake-negative (hup(-)) r. japonicum point mutant (pj17nal) and screening tetracycline-resistant colonies for the ability to grow chemolithotrophica ... | 1983 | 16593268 |
| organization and expression of rhizobium meliloti nitrogen fixation genes. | the boundaries of a nif gene cluster in rhizobium meliloti were determined by tn5 mutagenesis. these genes are clustered within a 14- to 15-kilobase (kb) region that includes the nitrogenase structural genes. sequences within 10 kb on either side of this region are devoid of symbiotically essential gene function. rna blot analysis identified a 5- to 6-kb transcript that corresponds to the nitrogenase structural gene operon. the 5' end of this transcript and its polarity were determined by nuclea ... | 1983 | 16593313 |
| mutants of rhizobium japonicum with increased hydrogenase activity. | some strains of rhizobium japonicum can use hydrogen as an energy source for growth under microaerophilic conditions. mutant strains have been selected that use hydrogen in the presence of high partial pressures of oxygen. the mutants contain more hydrogenase than the parent strain, both as free-living cells and as bacteroids in nitrogen-fixing soybean root nodules. | 1983 | 17754553 |
| hemoglobin in a nonleguminous plant, parasponia: possible genetic origin and function in nitrogen fixation. | a dimeric hemoglobin was purified from nitrogen-fixing root nodules formed by association of rhizobium with a nonleguminous plant, parasponia. the oxygen dissociation rate constant is probably sufficiently high to allow parasponia hemoglobin to function in a fashion similar to that of leghemoglobin, by oxygen buffering and transport during symbiotic nitrogen fixation. the identification of hemoglobin in a nonlegume raises important questions about the evolution of plant hemoglobin genes. | 1983 | 17816020 |
| parasitism of rotylenchulus reniformis on soybean root rhizobium nodules in venezuela. | 1983 | 19295793 | |
| the phylogeny of purple bacteria: the alpha subdivision. | the technique of oligonucleotide cataloging shows the purple photosynthetic eubacteria to comprise three major subdivisions, temporarily called alpha, beta, and gamma--previously designated groups i-iii by gibson et al. (1979). each subdivision contains a number of non-photosynthetic genera in addition to the photosynthetic ones. the alpha subdivision, the subject of the present report, contains most but not all of the species that fall into the classically defined genera rhodospirillum, rhodo ... | 1984 | 11541974 |
| mineral soils as carriers for rhizobium inoculants. | mineral soil-based inoculants of rhizobium meliloti and rhizobium phaseoli survived better at 4 degrees c than at higher temperatures, but ca. 15% of the cells were viable at 37 degrees c after 27 days. soil-based inoculants of r. meliloti, r. phaseoli, rhizobium japonicum, and a cowpea rhizobium sp. applied to seeds of their host legumes also survived better at low temperatures, but the percent survival of such inoculants was higher than peat-based inoculants at 35 degrees c. survival of r. pha ... | 1984 | 16346460 |
| phosphate nutrition of rhizobium spp. | this study was conducted to determine the behavior of 40 strains from six species of rhizobium in liquid defined media containing orthophosphate at levels likely to be encountered naturally, ranging from the high concentrations expected in nodules and artificial media to the low concentrations of soil solutions. storage capacity in strains with high levels (2 mm) of p and ability to utilize this stored p for growth after transfer to low levels (0.06 mum) of p varied with each strain. storage var ... | 1984 | 16346468 |
| rhizosphere response as a factor in competition among three serogroups of indigenous rhizobium japonicum for nodulation of field-grown soybeans. | rhizosphere response was studied as a factor in competition among indigenous rhizobium japonicum serogroups for the nodulation of soybeans under field conditions. r. japonicum serogroups 110, 123, and 138 were found to coexist in a waukegan field soil where they were determined to be the major nodulating rhizobia in soybean nodules. competitive relationships among the three serogroups in that soil and in rhizospheres were examined during two growing seasons with several host cultivars with and w ... | 1984 | 16346501 |
| rhizobium japonicum serogroup and hydrogenase phenotype distribution in 12 states. | a survey was conducted in 1980 on 972 isolates of rhizobium japonicum obtained from 65 soybean field locations in 12 states. isolates were examined for the hydrogenase (hup) phenotype and somatic serogroup identity. only 20% of the isolates were hup, with a majority of hup isolates occurring in 10 of the 12 states. the most predominant serogroup was 31 (21.5%), followed by 123 (13.6%). although most serogroups contained a majority of hup isolates, marked differences occurred. none of the isolate ... | 1984 | 16346502 |
| complementary methods for the differentiation of rhizobium meliloti isolates. | because of the scarcity of literature on the successful use of serological methods for differentiation of rhizobium meliloti isolates, the objectives of this study were to provide a rationale for selecting isolates to which antisera could be raised and to appraise the suitability of published methods of preparing r. meliloti antigens for the serological identification of field isolates. we used one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis to develop protein profiles ... | 1984 | 16346506 |
| effect of plasmid pij1008 from rhizobium leguminosarum on symbiotic function of rhizobium meliloti. | plasmid pij1008, which carries determinants for uptake hydrogenase (hup) activity, was transferred from rhizobium leguminosarum to rhizobium meliloti without impairing the capacity of the latter species to form root nodules on alfalfa. the plasmid was still present in rhizobia reisolated from the root nodules of 12 different alfalfa cultivars, but only low levels of hup activity were detected in alfalfa. | 1984 | 16346527 |
| interaction of rhizobium sp. with toxin-producing fungus in culture medium and in a tropical soil. | experiments were conducted to determine the influence of a toxin-producing fungus on a rhizobial population in yeast-mannitol medium and in a tropical soil. the fungus, which was isolated from a highly weathered soil (tropeptic eutrustox), was identified as a metarhizum sp. the density of rhizobial populations established in yeast-mannitol medium in the absence of the fungus was 10 times higher than that established in its presence. however, the fungus did not exert similar antagonistic influenc ... | 1984 | 16346537 |
| fine structure of succinate-swollen rhizobium trifolii 0403. | transmission electron micrographs of glutaraldehyde- oso(4)-fixed rhizobium trifolii 0403 before and after cells were treated with 16.6 mm succinate showed that treated cells increased in mass by increasing cytoplasmic volume. the morphology of succinate-treated cells was identical to that of bacteroids, and the appearances of the envelope and periplasmic space were similar. the primary difference was in inclusion number and type. | 1984 | 16346547 |
| invalidity of the concept of slow growth and alkali production in cowpea rhizobia. | a total of 103 rhizobial strains representing the cowpea miscellany and rhizobium japonicum were studied with regard to growth rate, glucose metabolic pathways, and ph change in culture medium. doubling times ranged from 1.4 +/- 0.04 to 44.1 +/- 5.2 h; although two populations of "fast-growing" and "slow-growing" rhizobia were noted, they overlapped and were not distinctly separated. twenty-four strains which had doubling times of less than 8 h all showed nadp-linked 6-phosphogluconate dehydroge ... | 1984 | 16346589 |
| fast-growing rhizobium japonicum that effectively nodulates several commercial glycine max l. merrill cultivars. | several isolates of fast-growing rhizobium japonicum that nodulate the wild soybean glycine soja have been recently described (keyser et al., science 215:1631-1632, 1982). we demonstrate that one of these isolates, designated prc 440 or usda 191, has a wider host range than that previously reported and is able to nodulate several commercial glycine max cultivars as effectively as does slow-growing r. japonicum 61a76. electron microscopic examination revealed no obvious differences between strain ... | 1984 | 16346594 |
| competition among rhizobium spp. for nodulation of leucaena leucocephala in two tropical soils. | the successful nodulation of legumes by a rhizobium strain is determined by the competitive ability of that strain against the mixture of other native and inoculant rhizobia. competition among six leucaena rhizobial strains in single and multistrain inoculants were studied. field inoculation trials were conducted in an oxisol and a mollisol soil, both of which contained indigenous leucaena-nodulating rhizobia. strain-specific fluorescent antibodies were used for the identification of the strains ... | 1984 | 16346600 |
| nitrogen fixation and carbon dioxide assimilation in rhizobium japonicum. | in free-living rhizobium japonicum cultures, the stimulatory effect of co(2) on nitrogenase (acetylene reduction) activity was mediated through ribulose bisphosphate carboxylase activity. two mutant strains (cj5 and cj6) of r. japonicum defective in co(2) fixation were isolated by mitomycin c treatment. no ribulose bisphosphate carboxylase activity could be detected in strain cj6, but a low level of enzyme activity was present in strain cj5. mutant strain cj5 also exhibited pleiotropic effects o ... | 1984 | 16346608 |
| enhancing soybean rhizosphere colonization by rhizobium japonicum. | a study was conducted to seek means to increase the colonization of the rhizosphere of soybeans (glycine max l. merrill) by rhizobium japonicum. for this purpose, a strain of r. japonicum that was resistant to benomyl, streptomycin, and erythromycin was used. the numbers of r. japonicum rose quickly in the first 2 days after soybean seeds were planted in soil and then rapidly fell. the decline was slower if the seeds were coated with benomyl. this fungicide reduced the numbers of bacteria and pr ... | 1984 | 16346616 |
| root hair deformation, bacterial attachment, and plant growth in wheat-azospirillum associations. | seven azospirillum strains induced more deformation of root hairs of wheat than did strains of rhizobium leguminosarum, azotobacter chroococcum, or escherichia coli. azospirillum sp. strain sp245 caused the most deformation. strain sp245 (isolated from surface sterile roots of wheat) and strain sp7 (isolated from the rhizosphere of a forage grass) were compared with regard to their effects on root hair deformation, their attachment to roots, and their effects on the growth of four wheat cultivar ... | 1984 | 16346680 |
| variation in preference for rhizobium meliloti within and between medicago sativa cultivars grown in soil. | variation in nodulation preferences for rhizobium strains within and between medicago sativa cultivars was assessed in the greenhouse with plants grown in leonard jars and two soils of diverse origin (lanark and ottawa), using inocula consisting of effective individual or paired strains of r. meliloti which could be recognized by high-concentration antibiotic resistance. the results indicated considerable variability in host preferences for r. meliloti among plants within cultivars but not betwe ... | 1984 | 16346682 |
| underexpression of ap from r-plasmids in fast-growing rhizobium species. | the presence of the plasmid rp1 in the cells of rhizobium leguminosarum strains rld1, 300, and 248, r. phaseoli 1233, r. trifolii strains t1 and 6661, and r. meliloti 4013 was found to appreciably increase bacterial resistance toward kanamycin and tetracycline but not toward ampicillin. the presence of 16 other r-plasmids in r. leguminosarum was also found to either not increase or only marginally increase bacterial resistance toward ampicillin. it appears now that underexpression of the plasmid ... | 1984 | 16346686 |
| structural genes of dinitrogenase and dinitrogenase reductase are transcribed from two separate promoters in the broad host range cowpea rhizobium strain irc78. | the nucleotide sequence of the structural gene (nifd) coding for the alpha-subunit of dinitrogenase along with its flanking sequences has been determined in cowpea rhizobium irc78. the coding sequence consists of 1500 nucleotides, which corresponds to a predicted amino acid sequence of 500 residues and a molecular weight of 56,025. nucleotide homology to nifd from the blue-green alga, anabaena, and parasponia rhizobium, are 63% and 90%, respectively. cowpea rhizobium irc78 nifd and nifk (encodes ... | 1984 | 16578778 |
| mapping of the protein-coding regions of rhizobium meliloti common nodulation genes. | an 8.5-kb ecori fragment containing the common nod region of the megaplasmid prme41b of rhizobium meliloti was recloned in plasmids of escherichia coli, and a detailed restriction map was established. the region can express at least eight proteins in e. coli minicells and in an in vitro transcription/translation system, prepared from e. coli. protein coding regions were determined by subcloning of restriction fragments, deletion mutations and by transposon mutagenesis. the coding regions for at ... | 1984 | 16453541 |
| rhizobium sp. strain ors571 ammonium assimilation and nitrogen fixation. | among rhizobia studied, rhizobium sp. strain ors571 alone grew unambiguously on n2 as sole n source. in ors571 , only the glutamine synthetase (gs)-glutamate synthase ( gogat ) pathway assimilated ammonium. however, ors571 exhibited two unique physiological aspects of this pathway: ors571 had only gs i, whereas all other rhizobiaceae studied had both gs i and gs ii, and both nadph- and nadh-dependent gogat activities were present. ors571 gs-affected and nadph- gogat -affected mutant strains were ... | 1984 | 6144666 |
| mg2+ adenosine triphosphatase from cell envelopes of free-living and bacteroid forms of rhizobium lupini strain nzp2257. | a procedure for the purification of mg2+ adenosine triphosphatase (ec 3.6.1.3) from free-living and bacteroid forms of rhizobium lupini nzp2257 is described. the enzyme was released from cell envelopes using triton x-100 and purified by gel filtration on ultrogel aca 22, followed by preparative gel electrophoresis on agarose. the purified atpase had a molecular weight of about 355,000, as determined from sedimentation coefficients on sucrose gradients. kinetic analysis of activity of the enzyme ... | 1984 | 6146293 |
| glutamine synthetase of phaseolus vulgaris l.: organ-specific expression of a multigene family. | a recombinant plasmid (pcpvngs-01) containing sequences related to glutamine synthetase (gs) has been identified from a cdna library constructed from poly (a)+ rna isolated from root nodules of phaseolus vulgaris l. the identification of this recombinant relied on the observations that: (a) the clone hybridized strongly to purified gs mrna; (b) in hybrid-select translation experiments, the clone selected mrna that produced a polypeptide identical in molecular weight to purified gs subunits which ... | 1984 | 6152282 |
| map locations of five transcripts homologous to tr-dna in tobacco and sunflower crown gall tumors. | polyadenylated rna from two octopine type tumor lines (e1, pscg-15955) was analyzed by rna blot hybridization and shown to contain five major transcripts homologous to tr dna. in tobacco e1 tissue, the molecular weights of the tr homologous rnas are 1.65 kb, 1.55 kb, 1.45 kb, 1.05 kb, and 0.78 kb. the 5' - and 3'-termini of each of the five e1 tumor transcripts were determined by s1 nuclease hybrid protection mapping. the polarity of transcription for the 0.78, 1.05 and 1.65 kb rnas is from left ... | 1984 | 6200831 |
| evaluation of active versus passive uptake of metabolites by rhizobium japonicum bacteroids. | rhizobium japonicum bacteroids were isolated anaerobically from soybean [glycine max (l.) merr] nodules. the bacteroids, which were capable of acetylene reduction and respiration, were used to study the uptake of metabolites by a method which permits correction for nonspecific adsorption of metabolites and estimation of total cell volume. these determinations permit active uptake to be assessed from metabolite accumulation against a concentration gradient. succinate, malate, alpha-ketoglutarate, ... | 1984 | 6203891 |
| changes in t-dna methylation and expression are associated with phenotypic variation and plant regeneration in a crown gall tumor line. | phenotypic variation of an octopine-type crown gall tumor line resulting from changes in the pattern of t-dna methylation and expression is described. variants that grow as unorganized callus always express t-dna transcripts 1 and 2. in shoot-forming variants (teratomas) only t-dna transcript 4 is expressed. this line also regenerates normal-appearing, rooted plants in which all t-dna expression is suppressed. tissues from these plants require phytohormones for growth in vitro. these plants are ... | 1984 | 6084805 |
| reverse transcription and kinetic complexity analysis of mrna from lupin root nodules. | complementary dna (cdna) synthesis was performed using mrna from lupin root nodules and from lupin uninfected roots as templates. optimal conditions for the synthesis of 700 nucleotides long cdna were established. hybridization kinetics of mrna-cdna were performed in a homologous system from root nodules as well as in a heterologous system. hybridization analysis revealed the presence of four frequency abundance classes within the root nodule mrna population. in order to enrich the cdna populati ... | 1984 | 6085442 |
| a comparison of virulence determinants in an octopine ti plasmid, a nopaline ti plasmid, and an ri plasmid by complementation analysis of agrobacterium tumefaciens mutants. | transposon-insertion mutants with vir- ti plasmids were characterized and then used in complementation experiments. one of the mutants (lba 1517) had a mutation in a newly discovered vir locus called virf. the virf mutation led to a strongly diminished virulence on tomato and tobacco, but not on certain other plant species. also a mutant (lba 1505) was isolated with a mutation somewhere in the bacterial genome but outside the octopine ti plasmid that caused a restriction in host range for tumor ... | 1984 | 6087390 |
| genetic and molecular characterization of the pseudomonas plasmid pvs1. | a restriction map of the 30-kb nonconjugative pseudomonas plasmid pvs1 was constructed. derivatives of pvs1 obtained in vitro by successive deletions were used to localize on the physical map the determinant for resistance to mercuric ions (carried by transposon tn501), the gene(s) encoding sulfonamide resistance, a 1.6-kb region affecting plasmid stability and establishment in p. fluorescens atcc 13525, and a segment required for mobilization of pvs1 by plasmid rp1. the sulfonamide resistance d ... | 1984 | 6087391 |
| [taxonomic position of agrobacterium strains of hospital origin]. | a collection of 31 strains received as agrobacterium tumefaciens and a. radiobacter was subjected to detailed phenotypic and genomic studies. these strains were recovered from plants, soil, water and clinical specimens. type strains of a. tumefaciens, a. radiobacter, a. rhizogenes and a. rubi were also included. the strains were tested for their ability to use 169 organic compounds as sources of carbon and energy. in addition, 11 conventional characters were studied for each strain. relatedness ... | 1984 | 6087709 |
| crown gall oncogenesis: evidence that a t-dna gene from the agrobacterium ti plasmid ptia6 encodes an enzyme that catalyzes synthesis of indoleacetic acid. | stable incorporation of tumor-inducing (ti) plasmid sequences, the t-dna, into the genomes of dicotyledonous plants results in the formation of crown gall tumors. previous genetic studies have suggested that the products of the genes encoding transcripts 1 and 2, which are encoded by the tl-dna region of ptia6, are responsible for inducing the auxin-independent phenotype of crown gall tissues. here we report the construction of a plasmid, pmtlact2, which directs the synthesis of the mr 49,800 po ... | 1984 | 6089175 |
| characterization of rhizobium japonicum hydrogen uptake genes. | recombinant cosmids from a gene library of the dna from hup+ rhizobium japonicum 122des previously have been shown to restore hydrogenase activity when transferred by conjugation into certain hup- mutants of r. japonicum. we generated a restriction map covering 32.2 kilobases of this cosmid dna. at least 25.3 kilobases of the cosmid phu1 were shown to have the same arrangement as those in the genome of strain 122des. analysis of tn5 insertions into the 122des genome indicates that hup-specific s ... | 1984 | 6090382 |
| physical organization of the bradyrhizobium japonicum nitrogenase gene region. | in bradyrhizobium japonicum usda 110 the three genes that encode the nitrogenase enzyme complex are separated into two transcription units, nifh and nifdk. we have physically mapped a 33-kilobase-pair region of the b. japonicum genome that contains both nifh and nifdk. the nifdk operon is located transcriptionally upstream from nifh, and all three genes are transcribed in the same direction. within the 20-kilobase-pair region that separates the promoters for these two transcription units, we hav ... | 1984 | 6090394 |
| comparison of t-dna oncogene complements of agrobacterium tumefaciens tumor-inducing plasmids with limited and wide host ranges. | the t-dna oncogene complements of the limited-host-range tumor-inducing plasmid ptiag63 and the wide-host-range plasmid ptia6 were compared. the resulting data indicate that ptiag63 has dna sequences related to most of the genes encoded by the oncogene region, the tl-dna, of ptia6 and that these sequences are divided between two t-dna regions, the ta-dna, which encoded sequences related to ptia6 genes 4 (the cytokinin independence gene) and 6a, as well as to a ptia6 tl-dna fragment that encoded ... | 1984 | 6090421 |
| host range encoded by the agrobacterium tumefaciens tumor-inducing plasmid ptiag63 can be expanded by modification of its t-dna oncogene complement. | agrobacterium tumefaciens harboring ptia6 incite unorganized tumors on nicotiana rustica, sunflowers, carrots, and tomatoes, whereas isogenic strains of agrobacteria harboring ptiag63 form "rooty" tumors on n. rustica and are essentially avirulent on sunflowers, carrots, and tomatoes. in this report we show that the different host range characteristics of these two plasmids were due, in part, to differences in the t-dna oncogene complements of the plasmids. specifically, we constructed derivativ ... | 1984 | 6090422 |
| conjugal transfer of bacterial chromosomes mediated by the rk2 plasmid transfer origin cloned into transposon tn5. | we report here a novel system for the conjugal transfer of bacterial chromosomes which utilizes the transfer origin (orit) of plasmid rk2 cloned into transposon tn5. tn5 with orit was inserted by transposition into the chromosomes of escherichia coli and rhizobium meliloti. the orit sequence then served as the origin of high-frequency chromosome transfer when a helper rk2 plasmid was present in the same cell. the broad host range features of rk2 make this system of oriented chromosome mobilizati ... | 1984 | 6090433 |
| the t-dna of agrobacterium rhizogenes is transmitted through meiosis to the progeny of hairy root plants. | plants regenerated from tobacco hairy root callus cultures were fertilized by self-pollination, and healthy, morphologically normal r1 offspring were obtained. three of these r1 seedlings were analyzed for the presence of t-dna and synthesis of the t-dna-specific compound agropine. all three r1 plants analyzed contained the same full-length t-dna as the parental regenerant, while only two showed agropine synthesis. | 1984 | 6090564 |
| identification and dna sequence of fixz, a nifb-like gene from rhizobium leguminosarum. | previously, several mutants which nodulated peas but which failed to fix nitrogen were isolated following tn5 mutagenesis of prl 1ji, a symbiotic plasmid of rhizobium leguminosarum. two of these alleles, fix52::tn5 and fix137::tn5 were in a region of prl 1ji which hybridized to a probe that contained the nifa gene and the amino-terminal region of the nifb gene of klebsiella pneumoniae. the nitrogen fixation defect of the fix52::tn5 mutant strain was corrected by a 2.0kb fragment of the correspon ... | 1984 | 6091056 |