Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| lipopolysaccharide profiles from nodules as markers of bradyrhizobium strains nodulating wild legumes. | to develop the use of electrophoretic lipopolysaccharide profiles for bradyrhizobium strain identification, we studied the feasibility of using electrophoresis of whole legume nodule homogenates to obtain distinctive lipopolysaccharide profiles. the electrophoretic patterns were the same whether we used nodule extracts, bacteroids, or cultured bacteria as samples, and there was no evidence of changes in the ladder-like pattern during the nodulation process. to assess the reliability of using lip ... | 1998 | 16349529 |
| nod bj-v (c18:1, mefuc) production by bradyrhizobium japonicum (usda110, 532c) at suboptimal growth temperatures. | nod factors (lipo-chitooligosaccharides, or lcos) act as bacteria-to-plant signal molecules that modulate early events of the bradyrhizobium-soybean symbiosis. it is known that low root zone temperature inhibits the early stages of this symbiosis; however, the effect of low soil temperature on bacteria-to-plant signaling is largely uninvestigated. we evaluated the effect of low growth temperatures on the production kinetics of nod factor (lco) by b. japonicum. two strains of b. japonicum, 532c a ... | 2006 | 16360810 |
| effect of two amf life strategies on the tripartite symbiosis with bradyrhizobium japonicum and soybean. | this study is the first in assessing the effect of soil disturbance on the contribution of arbuscular mycorrhizal fungi (amf) with different life-history strategies to the tripartite symbiosis with soybeans and bradyrhizobium japonicum (kirchner) jordan. we hypothesized that gigaspora margarita becker and hall would be more affected by soil disturbance than glomus clarum nicol. and schenck, and consequently, the tripartite symbiosis would develop more rapidly and lead to greater n(2) fixation in ... | 2006 | 16362418 |
| the iron control element, acting in positive and negative control of iron-regulated bradyrhizobium japonicum genes, is a target for the irr protein. | bradyrhizobium japonicum, the nitrogen-fixing soybean symbiont, possesses a heme uptake system encoded by the gene cluster hmuvut-hmur-exbbd-tonb. transcription of the divergently oriented hmut and hmur genes was previously found to be induced by iron limitation and to depend on a 21-bp promoter-upstream iron control element (ice). here, we show by deletion analysis that the full-length ice is needed for this type of positive control. additional genes associated with ice-like motifs were identif ... | 2006 | 16385063 |
| functional characterization of the bradyrhizobium japonicum moda and modb genes involved in molybdenum transport. | a modabc gene cluster that encodes an abc-type, high-affinity molybdate transporter from bradyrhizobium japonicum has been isolated and characterized. b. japonicum moda and modb mutant strains were unable to grow aerobically or anaerobically with nitrate as nitrogen source or as respiratory substrate, respectively, and lacked nitrate reductase activity. the nitrogen-fixing ability of the mod mutants in symbiotic association with soybean plants grown in a mo-deficient mineral solution was severel ... | 2006 | 16385130 |
| tgge analysis of the diversity of ammonia-oxidizing and denitrifying bacteria in submerged filter biofilms for the treatment of urban wastewater. | the spatial and temporal diversity of the bacterial community-forming biofilms in a pilot-scale submerged biofilter used for the treatment of urban wastewater was analyzed by a temperature-gradient gel electrophoresis (tgge) approach. tgge profiles based on partial sequence of the 16s rrna gene showed that the community composition of the biofilms remained fairly stable along the column system and during the whole time of operation of the biofilter (more than 1 year). community-profiling based o ... | 2006 | 16391923 |
| rflp analysis of the rrna operon of a brazilian collection of bradyrhizobial strains from 33 legume species. | genetic diversity in tropical rhizobial species is still poorly known. with the aim of increasing this knowledge, three ribosomal regions of 119 strains belonging to the official brazilian culture collection of rhizobia and classified as bradyrhizobium based on morphological and physiological characteristics in vitro were analysed by rflp-pcr. the strains were isolated from 33 legume species, representing nine tribes and all three subfamilies; they all form very effective n2-fixing nodules and 4 ... | 2006 | 16403890 |
| characterization of rhizobia isolated from albizia spp. in comparison with microsymbionts of acacia spp. and leucaena leucocephala grown in china. | this is the first systematic study of rhizobia associated with albizia trees. the analyses of pcr-rflp and sequencing of 16s rrna genes, sds-page of whole-cell proteins and clustering of phenotypic characters grouped the 31 rhizobial strains isolated from albizia into eight putative species within the genera bradyrhizobium, mesorhizobium and rhizobium. among these eight rhizobial species, five were unique to albizia and the remaining three were shared with acacia and leucaena, two legume trees c ... | 2006 | 16406708 |
| the bradyrhizobium japonicum napedabc genes are controlled by the fixlj-fixk(2)-nnrr regulatory cascade. | nitrate respiration by the n(2)-fixing symbiotic bacteria bradyrhizobium japonicum usda110 is mediated by a nap (periplasmic nitrate reductase) encoded by the napedabc genes. expression of a transcriptional fusion of the nap promoter region to the reporter gene lacz, p(nape)-lacz, was very low in aerobically grown cells of usda110, but expression was induced approx. 3-fold when the cells were cultured under microaerobic conditions, and 12-fold when nitrate was added to the microaerobic incubatio ... | 2006 | 16417495 |
| a multitude of crp/fnr-like transcription proteins in bradyrhizobium japonicum. | in bradyrhizobium japonicum, the nitrogen-fixing soya bean endosymbiont and facultative denitrifier, three crp (camp receptor protein)/fnr (fumarate and nitrate reductase regulatory protein)-type transcription factors [fixk(1), fixk(2) and nnrr (nitrite and nitric oxide reductase regulator)] have been studied previously in the context of the regulation of nitrogen fixation and denitrification. the gene expression of both fixk(1) and nnrr depends on fixk(2), which acts as a key distributor of the ... | 2006 | 16417509 |
| the role of bradyrhizobium japonicum nitric oxide reductase in nitric oxide detoxification in soya bean root nodules. | the identification of nitric oxide-bound leghaemoglobin within soya bean nodules has led to the question of how bradyrhizobium japonicum bacteroids overcome the toxicity of this nitric oxide. it has previously been shown that one candidate for nitric oxide detoxification, the respiratory nitric oxide reductase, is expressed in soya bean nodules from plants supplied with nitrate. in this paper, the role of this enzyme in nitric oxide detoxification is assessed and discussion is provided on other ... | 2006 | 16417520 |
| effect of plant growth promoting rhizobacteria containing acc-deaminase on maize (zea mays l.) growth under axenic conditions and on nodulation in mung bean (vigna radiata l.). | this study was conducted to test the hypothesis that the bacterial strains possessing 1-aminocyclopropane-1-carboxylic acid (acc)-deaminase activity may also promote growth of inoculated plants and could increase nodulation in legumes upon co-inoculation with rhizobia. | 2006 | 16441381 |
| molecular phylogeny based on the 16s rrna gene of elite rhizobial strains used in brazilian commercial inoculants. | nitrogen is often a limiting nutrient, therefore the sustainability of food crops, forages and green manure legumes is mainly associated with their ability to establish symbiotic associations with stem and root-nodulating n2-fixing rhizobia. the selection, identification and maintenance of elite strains for each host are critical. decades of research in brazil resulted in a list of strains officially recommended for several legumes, but their genetic diversity is poorly known. this study aimed a ... | 2006 | 16442259 |
| oxygen reactivity of puta from helicobacter species and proline-linked oxidative stress. | proline is converted to glutamate in two successive steps by the proline utilization a (puta) flavoenzyme in gram-negative bacteria. puta contains a proline dehydrogenase domain that catalyzes the flavin adenine dinucleotide (fad)-dependent oxidation of proline to delta1-pyrroline-5-carboxylate (p5c) and a p5c dehydrogenase domain that catalyzes the nad+-dependent oxidation of p5c to glutamate. here, we characterize puta from helicobacter hepaticus (puta(hh)) and helicobacter pylori (puta(hp)) t ... | 2006 | 16452403 |
| glutamine synthetase genes are regulated by ammonia provided externally or by symbiotic nitrogen fixation. | glutamine synthetase is the key enzyme in the assimilation by plants of reduced nitrogen provided from either the soil or fixed symbiotically in association with rhizobium. we have isolated a number of cdna clones for soybean glutamine synthetase (gs) from a nodule-cdna library, using rna from polysomes immunoprecipitated by gs antibodies. transcripts corresponding to two clones differing in their 3' non-translated sequences were present in both root and nodule tissue; however, the concentration ... | 1987 | 16453762 |
| expression and functional analysis of the rhizobium meliloti nifa gene. | the translational initiation point for rhizobium meliloti nifa, the specific activator for nitrogen fixation (nif) genes, was determined. when expressed in an escherichia coli linked transcriptional-translational system the dna coding for the r.meliloti nifa gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. there are three in-frame atg codons at the n-terminus of the gene; by replacing the poor ribosome binding sites of the native dna with a synthetic consensus r ... | 1988 | 16453824 |
| nitrous oxide reductase genes (nosz) of denitrifying microbial populations in soil and the earthworm gut are phylogenetically similar. | earthworms emit nitrous oxide (n2o) and dinitrogen (n2). it has been hypothesized that the in situ conditions of the earthworm gut activates ingested soil denitrifiers during gut passage and leads to these in vivo emissions (m. a. horn, a. schramm, and h. l. drake, appl. environ. microbiol. 69:1662-1669, 2003). this hypothesis implies that the denitrifiers in the earthworm gut are not endemic to the gut but rather are regular members of the soil denitrifier population. to test this hypothesis, t ... | 2006 | 16461644 |
| functional implications of the propionate 7-arginine 220 interaction in the fixlh oxygen sensor from bradyrhizobium japonicum. | bjfixl from bradyrhizobium japonicum is a heme-based oxygen sensor implicated in the signaling cascade that enables the bacterium to adapt to fluctuating oxygen levels. signal transduction is initiated by the binding of o(2) to the heme domain of bjfixl, resulting in protein conformational changes that are transmitted to a histidine kinase domain. we report structural changes of the heme and its binding pocket in the fe(ii) deoxy and fe(iii) met states of the wild-type bjfixlh oxygen sensor doma ... | 2006 | 16475796 |
| a novel bacteriocin, thuricin 17, produced by plant growth promoting rhizobacteria strain bacillus thuringiensis neb17: isolation and classification. | the aim of this study was to identify and characterize a compound produced by the plant growth promoting bacterium, bacillus thuringiensis non-bradyrhizobium endophytic bacterium 17. | 2006 | 16478494 |
| dissimilatory nitrate reductase from bradyrhizobium sp. (lupinus): subcellular location, catalytic properties, and characterization of the active enzyme forms. | subcellular location, chlorate specificity, and sensitivity to micromolar concentrations of azide suggest that most of the anaerobically induced nitrate reductase (nr) activity in bradyrhizobium sp. (lupinus) could be ascribed to the membrane type of bacterial dissimilatory nrs. two active complexes of the enzyme, nr(i) of 140 kda and nr(ii) of 190 kda, were detected in membranes of the nitrate-respiring usda strain 3045. both enzyme forms were purified to homogeneity. obtained specific antibodi ... | 2006 | 16479356 |
| rhizobial exopolysaccharides: genetic control and symbiotic functions. | specific complex interactions between soil bacteria belonging to rhizobium, sinorhizobium, mesorhizobium, phylorhizobium, bradyrhizobium and azorhizobium commonly known as rhizobia, and their host leguminous plants result in development of root nodules. nodules are new organs that consist mainly of plant cells infected with bacteroids that provide the host plant with fixed nitrogen. proper nodule development requires the synthesis and perception of signal molecules such as lipochitooligosacchari ... | 2006 | 16483356 |
| ameba-associated microorganisms and diagnosis of nosocomial pneumonia. | to elucidate the role of ameba-associated microorganisms (aams) as etiologic agents of pneumonia, we screened for legionella spp., parachlamydia acanthamoeba, afipia sp., bosea spp., bradyrhizobium spp., mesorhizobium amorphae, rasbo bacterium, azorhizobium caulinodans, acanthamoeba polyphaga mimivirus, and conventional microorganisms in 210 pneumonia patients in intensive-care units by using culture, polymerase chain reaction, and serologic testing. these resulted in 59 diagnoses in 40 patients ... | 2006 | 16494750 |
| rhizobitoxine modulates plant-microbe interactions by ethylene inhibition. | bradyrhizobium elkanii produces rhizobitoxine, an enol-ether amino acid, which has been regarded as a phytotoxin because it causes chlorosis in soybeans. however, recent studies have revealed that rhizobitoxine plays a positive role in establishing symbiosis between b. elkanii and host legumes: rhizobitoxine enhances the nodulation process by inhibiting acc (1-aminocyclopropane-1-carboxylate) synthase in the ethylene biosynthesis of host roots. b. elkanii rtxa and rtxc genes are required for rhi ... | 2006 | 16516430 |
| genome sequence of the chemolithoautotrophic nitrite-oxidizing bacterium nitrobacter winogradskyi nb-255. | the alphaproteobacterium nitrobacter winogradskyi (atcc 25391) is a gram-negative facultative chemolithoautotroph capable of extracting energy from the oxidation of nitrite to nitrate. sequencing and analysis of its genome revealed a single circular chromosome of 3,402,093 bp encoding 3,143 predicted proteins. there were extensive similarities to genes in two alphaproteobacteria, bradyrhizobium japonicum usda110 (1,300 genes) and rhodopseudomonas palustris cga009 cg (815 genes). genes encoding p ... | 2006 | 16517654 |
| transformation of rhizobia with broad-host-range plasmids by using a freeze-thaw method. | several species of rhizobia were successfully transformed with broad-host-range plasmids of different replicons by using a modified freeze-thaw method. a generic binary vector (ppzp211) was maintained in mesorhizobium loti without selection and stably inherited during nodulation. the method could extend the potential of rhizobia as a vehicle for plant transformation. | 2006 | 16517691 |
| metabolic changes of rhizobia in legume nodules. | bacteria have evolved a wide variety of metabolic strategies to cope with varied environments. some are specialists and only able to survive in restricted environments; others are generalists and able to cope with diverse environmental conditions. rhizobia (e.g. rhizobium, sinorhizobium, bradyrhizobium, mesorhizobium and azorhizobium species) can survive and compete for nutrients in soil and the plant rhizosphere but can also form a beneficial symbiosis with legumes in a highly specialized plant ... | 2006 | 16520035 |
| restriction of nodulation by bradyrhizobium japonicum is mediated by factors present in the roots of glycine max. | reciprocal grafting experiments done using soybean plant introduction genotypes indicated that restriction of nodulation by bradyrhizobium japonicum is determined by the genotype of the root and is dependent on plant growth temperature. microscopic analyses indicated that the soybean plant introduction genotypes restrict nodulation of b. japonicum at symbiotic stages which occur both before and after the formation of nodule primordia. | 1995 | 16534946 |
| diversity among field populations of bradyrhizobium japonicum in poland. | genetic structure in field populations of bradyrhizobium japonicum isolated in poland was determined by using several complementary techniques. of the 10 field sites examined, only 4 contained populations of indigenous b. japonicum strains. the polish bradyrhizobia were divided into at least two major groups on the basis of protein profiles on polyacrylamide gels, serological reaction with polyclonal antisera, repetitive extragenic palindromic pcr fingerprints of genomic dna, and southern hybrid ... | 1995 | 16534985 |
| host-controlled restriction of nodulation by bradyrhizobium japonicum strains in serogroup 110. | we previously reported the identification of a soybean plant introduction (pi) genotype, pi 417566, which restricts nodulation by bradyrhizobium japonicum mn1-1c (usda 430), strains in serogroup 129, and usda 110 (p. b. cregan, h. h. keyser, and m. j. sadowsky, appl. environ. microbiol. 55:2532-2536, 1989, and crop sci. 29:307-312, 1989). in this study, we further characterized nodulation restriction by pi 417566. twenty-four serogroup 110 isolates were tested for restricted nodulation on pi 417 ... | 1995 | 16535054 |
| protein synthesis by bradyrhizobium japonicum bacteroids declines as a function of nodule age. | isolated bacteroids of bradyrhizobium japonicum accumulated exogenously supplied [(sup35)s]methionine or [(sup3)h]leucine and incorporated them into cytosolic proteins. the accumulation of these labeled amino acids was inhibited by azide. only 3 to 6% of these accumulated amino acids were incorporated into protein. protein synthesis was not stimulated by incubation of bacteroids in the presence of potassium salts, malate, or amino acids, but azide, chloramphenicol, and acridine did inhibit the p ... | 1996 | 16535424 |
| enzymes of poly-(beta)-hydroxybutyrate metabolism in soybean and chickpea bacteroids. | the enzymatic capacity for metabolism of poly-(beta)-hydroxybutyrate (phb) has been examined in nitrogen-fixing symbioses of soybean (glycine max l.) plants, which may accumulate substantial amounts of phb, and chickpea (cicer arietinum l.) plants, which contain little or no phb. in the free-living state, both bradyrhizobium japonicum cb 1809 and rhizobium sp. (cicer) cc 1192, which form nodules on soybean and chickpea plants, respectively, produced substantial amounts of phb. to obtain informat ... | 1996 | 16535445 |
| identification of the carotenoid pigment canthaxanthin from photosynthetic bradyrhizobium strains. | canthaxanthin (4,4(prm1)-diketo-(beta)-carotene) is produced as the major carotenoid pigment by orange- and dark-pink-pigmented bacteriochlorophyll-containing bradyrhizobium strains isolated from stem nodules of aeschynomene species. these two new pigmentation groups differ from the well-studied strain btai1, which accumulates spirilloxanthin as the sole carotenoid. | 1997 | 16535544 |
| variation in the nod gene rflps, nucleotide sequences of 16s rrna genes, nod factors, and nodulation abilities of bradyrhizobium strains isolated from thai vigna plants. | the analysis of nod genes and 16s rrna gene regions, nod factors, and nodulation abilities of brady rhizobium strains isolated from tropical thai vigna species is reported. a total of 55 bradyrhizobium strains isolated from two cultivated and six wild vigna species growing in central and northern thailand were evaluated. thai vigna spp. bradyrhizobium strains showed higher levels of nod gene rflp diversity compared with thai soybean brady rhizobium strains or temperate strains of bradyrhizobium ... | 2006 | 16541157 |
| nitrate-dependent anaerobic carbon monoxide oxidation by aerobic co-oxidizing bacteria. | two dissimilatory nitrate-reducing (burkholderia xenovorans lb400 and xanthobacter sp. str. cox) and two denitrifying isolates (stappia aggregata iam 12614 and bradyrhizobium sp. str. cpp), previously characterized as aerobic co oxidizers, consumed co at ecologically relevant levels (<100 ppm) under anaerobic conditions in the presence, but not absence, of nitrate. none of the isolates were able to grow anaerobically with co as a carbon or energy source, however, and nitrate-dependent anaerobic ... | 2006 | 16542399 |
| oxidative stress promotes degradation of the irr protein to regulate haem biosynthesis in bradyrhizobium japonicum. | the haem proteins catalase and peroxidase are stress response proteins that detoxify reactive oxygen species. in the bacterium bradyrhizobium japonicum, expression of the gene encoding the haem biosynthesis enzyme delta-aminolevulinic acid dehydratase (alad) is normally repressed by the irr protein in iron-limited cells. irr degrades in the presence of iron, which requires haem binding to the protein. here, we found that alad levels were elevated in iron-limited cells of a catalase-deficient mut ... | 2006 | 16556232 |
| proposal for combining bradyrhizobium spp. (aeschynomene indica) with blastobacter denitrificans and to transfer blastobacter denitrificans (hirsch and muller, 1985) to the genus bradyrhizobium as bradyrhizobium denitrificans (comb. nov.). | the symbiotic bradyrhizobia of aeschynomene indica and the aquatic budding bacterium blastobacter denitrificans have much in common and this study broadens the characters that are shared between the two. the 23s rrna gene sequences of the bradyrhizobial isolates were most similar to each other and to the sequence of bl. denitrificans. evidence for the presence of photosynthetic genes in the genome of bl. denitrificans was obtained by pcr using primers to the conserved m subunit (pufm) of the pho ... | 2006 | 16564957 |
| molecular diversity of native bradyrhizobia isolated from lima bean (phaseolus lunatus l.) in peru. | the diversity of a collection of 21 bradyrhizobial isolates from lima bean (phaseolus lunatus l.) was assayed by molecular methods. moderately high to high genetic diversity was revealed by multilocus enzyme electrophoresis (mlee) analysis of seven enzyme loci and genomic fingerprints with eric and box primers. two groups with differences in growth rate were found among the isolates and their differentiation as two divergent bradyrhizobial lineages was supported by pcr-rflp of the rpob gene and ... | 2006 | 16564961 |
| bradyrhizobium japonicum senses iron through the status of haem to regulate iron homeostasis and metabolism. | the irr protein from the bacterium bradyrhizobium japonicum is expressed under iron limitation to mediate iron control of haem biosynthesis. the regulatory input to irr is the status of haem and its precursors iron and protoporphyrin at the site of haem synthesis. here, we show that irr controls the expression of iron transport genes and many other iron-regulated genes not directly involved in haem synthesis. irr is both a positive and negative effector of gene expression, and in at least some c ... | 2006 | 16573691 |
| [chemotaxis and growth of bradyrhizobium japonicum in the presence of fine-dispersed silica]. | the chemotactic properties of the soybean nodule bacterium bradyrhizobium japonicum were studied in the presence of synthetic fine-dispersed materials. it was shown that fine-dispersed silica (fds) and its variety modified with aluminum oxide (mfds) reduce bacterial chemotaxis to glucose. in addition, fds increases the irregular motility of b. japonicum, and mfds decreases it. this is in agreement with the effect of the materials on the rate of nodule bacterium growth. | 2006 | 16579445 |
| [genetic diversity and phylogeny of soybean bradyrhizobia isolated from south and north region of china]. | studies on genetic diversity and phylogeny of soybean bradyrhizobia isolated from south and north region of china were investigated through 16s rrna gene pcr rflp, 16s rrna gene sequencing and 16s-23s rrna igs pcr rflp assays. results of 16s rrna gene pcr rflp and 16s rrna gene sequencing analysis reveal that strains tested are ascribed into bradyrhizobium japonicum and b. elkanii species. b. japonicum is the dominant species and accounts for 91% of strains tested, but b. elkanii just up to 9%, ... | 2006 | 16579479 |
| isolation and characterization of nodulation genes from bradyrhizobium sp. (vigna) strain irc 78. | an 11.76-kilobase-pair (kb) segment of dna from bradyrhizobium sp. (vigna) strain irc 78 that hybridizes to nodulation genes of rhizobium meliloti strain 41 was isolated. hybridization of the 11.76-kb dna fragment to dna from other bradyrhizobium species revealed a high degree of sequence conservation in this region. transfer of the 11.76-kb segment to nodulation-defective (nod(-)) mutants of r. meliloti restored their ability to induce nodules on medicago sativa (alfalfa). mutants of strain irc ... | 1985 | 16593624 |
| bacterial delta-aminolevulinic acid synthase activity is not essential for leghemoglobin formation in the soybean/bradyrhizobium japonicum symbiosis. | previous studies of legume nodules have indicated that formation of the heme moiety of leghemoglobin is a function of the bacterial symbiont. we now show that a hema mutant of bradyrhizobium japonicum that cannot carry out the first step in heme biosynthesis forms fully effective nodules on soybeans. the bacterial mutant strain was constructed by first isolating the wild-type hema gene encoding delta-aminolevulinic acid synthase (ec 2.3.1.37) from a cosmid library, using a fragment of the rhizob ... | 1986 | 16593670 |
| bioluminescence in soybean root nodules: demonstration of a general approach to assay gene expression in vivo by using bacterial luciferase. | two plasmid vectors pfit001 and ppale001, containing luxab genes encoding bacterial luciferase [alkanal, reduced-fmn:oxygen oxidoreductase (1-hydroxylating, luminescing), ec 1.14.14.3] from vibrio harveyi, have been constructed. escherichia coli carrying derivatives of pfit001 with dna inserts in the unique ecori site located in luxb form "dark" colonies that can be readily distinguished from the bioluminescent or "bright" colonies. in contrast, promoterless ppale001 is used as a promoter-search ... | 1986 | 16593783 |
| rhizobium symbiotic genes required for nodulation of legume and nonlegume hosts. | parasponia, a woody member of the elm family, is the only nonlegume genus whose members are known to form an effective nitrogen-fixing symbiosis with bradyrhizobium or rhizobium species. the bradyrhizobium strain rp501, isolated from parasponia nodules, also nodulates the legumes siratro (macroptilium atropurpureum) and cowpea (vigna unguiculata). to test whether some of the same genes are involved in the early stages of legume and nonlegume nodulation, we generated transposon tn5 insertions in ... | 1987 | 16593814 |
| isolation of a cytochrome aa(3) gene from bradyrhizobium japonicum. | bradyhizobium japonicum strain lo501 is a tn5-induced mutant that does not express the terminal oxidase cytochrome aa(3) (cytochrome-c oxidase, ec 1.9.3.1). two and one-half kilobase pairs of lo501 genomic dna that flanks the transposon was isolated and used as a hybridization probe to obtain the wild-type gene from a cosmid library. two subcloned fragments from two of the isolated cosmids were ligated into broad host range vectors, and restriction maps of these fragments were generated. the res ... | 1987 | 16593835 |
| k regulates bacteroid-associated functions of bradyrhizobium. | cowpea bradyrhizobium 32h1 cells, when grown under 0.2% o(2), synthesize nitrogenase, as well as a methylammonium (ammonium) transport system and an electrogenic k(+)/h(+) antiporter. this effect was seen in growth medium containing 8-12 mm k(+) but not with 50 mum k(+). addition of k(+) to cells growing under low o(2) tensions in low-k(+) medium led to various phenotypic properties associated with bacteroids, including the ability to reduce acetylene, induction of an ammonium transport carrier ... | 1987 | 16593858 |
| induction of bradyrhizobium japonicum common nod genes by isoflavones isolated from glycine max. | the early events in legume nodulation by rhizobium spp. involve a conserved gene cluster known as the common nod region. a broad-host-range plasmid (pea2-21) containing a bradyrhizobium japonicum noddabc-lacz translational fusion was constructed and used to monitor nod gene expression in response to soybean root extract. two inducing compounds were isolated and identified. analysis using ultraviolet absorption spectra, proton nuclear magnetic resonance, and mass spectrometry showed that the two ... | 1987 | 16593884 |
| isolation of genes involved in nodulation competitiveness from rhizobium leguminosarum bv. trifolii t24. | rhizobium leguminosarum bv. trifolii t24 produces a potent anti-rhizobial compound, trifolitoxin, and exclusively nodulates clover roots when in mixed inoculum with trifolitoxin-sensitive strains of r. leguminosarum bv. trifolii [schwinghamer, e. a. & belkengren r. p. (1968) arch. mikrobiol. 64, 130-145]. in the present study, the isolation of trifolitoxin production and resistance genes is described. a cosmid genomic library of t24 was prepared in plafr3. no trifolitoxin expression was observed ... | 1988 | 16593933 |
| biodiversity of amoebae and amoeba-resisting bacteria in a hospital water network. | free-living amoebae (fla) are ubiquitous organisms that have been isolated from various domestic water systems, such as cooling towers and hospital water networks. in addition to their own pathogenicity, fla can also act as trojan horses and be naturally infected with amoeba-resisting bacteria (arb) that may be involved in human infections, such as pneumonia. we investigated the biodiversity of bacteria and their amoebal hosts in a hospital water network. using amoebal enrichment on nonnutrient ... | 2006 | 16597941 |
| symbiotic bradyrhizobium japonicum reduces n2o surrounding the soybean root system via nitrous oxide reductase. | n(2)o reductase activity in soybean nodules formed with bradyrhizobium japonicum was evaluated from n(2)o uptake and conversion of (15)n-n(2)o into (15)n-n(2). free-living cells of usda110 showed n(2)o reductase activity, whereas a nosz mutant did not. complementation of the nosz mutant with two cosmids containing the nosrzdfylx genes of b. japonicum usda110 restored the n(2)o reductase activity. when detached soybean nodules formed with usda110 were fed with (15)n-n(2)o, they rapidly emitted (1 ... | 2006 | 16597953 |
| effect of organic n source on bacterial growth, lipo-chitooligosaccharide production, and early soybean nodulation by bradyrhizobium japonicum. | production of bradyrhizobium japonicum inoculants is problematic because high inoculation rates are necessary but expensive, while production of rhizobial nod factors (lipo-chitooligosaccharides (lcos)), key signal molecules in the establishment of legume-rhizobia symbioses, may be inhibited at high culture cell densities. we conducted experiments to determine the effects of growth medium n source on b. japonicum growth, lco production, and early nodulation of soybean. we found that 1.57 mmol am ... | 2006 | 16604119 |
| the rhizobium leguminosarum regulator irra affects the transcription of a wide range of genes in response to fe availability. | we show that an unusual transcriptional regulator, called irra, regulates many genes in the symbiotic n2-fixing bacterium rhizobium leguminosarum in response to iron availability. several operons in r. leguminosarum are expressed at lower levels in cells grown in fe-depleted compared to fe-replete medium. these include hema1, which encodes the haem biosynthesis enzyme amino-levulinic acid synthase; sufs2bcds1xa, which specify enzymes for fes cluster synthesis; rira, a global, fe-responsive trans ... | 2006 | 16625355 |
| bradyrhizobia isolated from root nodules of parasponia (ulmaceae) do not constitute a separate coherent lineage. | rhizobial bacteria almost exclusively nodulate members of the families fabaceae, mimosaceae and caesalpiniaceae, but are found on a single non-legume taxon, parasponia (ulmaceae). based on their host-range, their nitrogen-fixing ability and strain competition experiments, bacterial strains isolated from parasponia were thought to constitute a separate lineage that would account for their exceptional host affinity. this hypothesis was investigated by focusing on four isolates that are representat ... | 2006 | 16627647 |
| labeling of carbon pools in bradyrhizobium japonicum and rhizobium leguminosarum bv viciae bacteroids following incubation of intact nodules with co(2). | the aim of the work reported here was to ascertain that the patterns of labeling seen in isolated bacteroids also occurred in bacteroids in intact nodules and to observe early metabolic events following exposure of intact nodules to (14)co(2). intact nodules of soybean (glycine max l. merr. cv ripley) inoculated with bradyrhizobium japonicum usda 110 and pea (pisum sativum l. cv progress 9) inoculated with rhizobium leguminosarum bv viciae isolate 128c53 were detached and immediately fed (14)co( ... | 1992 | 16653034 |
| p relaxation responses associated with n(2)/o(2) diffusion in soybean nodule cortical cells and excised cortical tissue. | n(2)-fixing bradyrhizobium japonicum nodules and cortical tissue derived from these nodules were examined in vivo by (31)p nuclear magnetic resonance (nmr) spectroscopy. perfusion of the viable nodules and excised cortical tissue with o(2) followed by n(2) or ar caused a loss of orthophosphate (pi) resonance magnetization associated with the major portion of acidic pi (delta 0.9 ppm, ph 5.5) residing in the cortical cells. resumption of o(2) perfusion restored approximately 80% of the intensity ... | 1992 | 16653184 |
| gibberellins and the legume-rhizobium symbiosis : iii. quantification of gibberellins from stems and nodules of lima bean and cowpea. | lima bean (phaseolus lunatus l.) plants inoculated with bradyrhizobium sp. strain 127e14 displayed a period of marked internode elongation that was not observed in plants inoculated with other compatible bradyrhizobia, including strain 127e15. when strain 127e14 nodulated an alternate host, cowpea (vigna unguiculata l. walp), a similar, although less dramatic growth response induced by the bacteria was observed. it has been speculated that the elongative growth promotion brought about by inocula ... | 1992 | 16653229 |
| relationship between ureide n and n(2) fixation, aboveground n accumulation, acetylene reduction, and nodule mass in greenhouse and field studies with glycine max l. (merr). | the relationship between ureide n and n(2) fixation was evaluated in greenhouse-grown soybean (glycine max l. merr.) and lima bean (phaseolus lunatus l.) and in field studies with soybean. in the greenhouse, plant n accumulation from n(2) fixation in soybean and lima bean correlated with ureide n. in soybean, n(2) fixation, ureide n, acetylene reduction, and nodule mass were correlated when n(2) fixation was inhibited by applying kno(3) solutions to the plants. the ureide-n concentrations of dif ... | 1985 | 16664027 |
| decreased exopolysaccharide synthesis by anaerobic and symbiotic cells of bradyrhizobium japonicum. | experiments were conducted to determine whether symbiotic bacteroids of bradyrhizobium japonicum produce exopolysaccharide within soybean (glycine max [l.] merr. cv ;lee 74') nodules. b. japonicum strains rt2, a derivative of usda 110 with resistance to streptomycin and rifampicin, and rt176-1, a mutant deficient in exopolysaccharide synthesis, were used. although aerobically cultured rt2 produced 1550 micrograms of exopolysaccharide per 10(10) cells, root nodules formed by rt2 contained only 55 ... | 1985 | 16664430 |
| enzymes of alpha,alpha-trehalose metabolism in soybean nodules. | metabolism of trehalose, alpha,d-glucopyranosyl-alpha,d-glucopyranoside, was studied in nodules of bradyrhizobium japonicum-glycine max [l.] merr. cv beeson 80 symbiosis. the nodule extract was divided into three fractions: bacteroid soluble protein, bacteroid fragments, and cytosol. the bacteroid soluble protein and cytosol fractions were gel-filtered. the key biosynthetic enzyme, trehalose-6-phosphate synthetase, was consistently found only in the bacteroids. trehalose-6-phosphate phosphatase ... | 1986 | 16664852 |
| two indirect methods for detecting ureide synthesis by nodulated legumes. | two methods were developed for the detection of altered ureide metabolism in legume nodules. both techniques are based on the positive correlation between the presence of high xanthine dehydrogenase (ec 1.2.1.37) specific activity in nodules and the ability of those nodules to produce the ureides, allantoin and allantoic acid. in the first method, nodulated legumes are treated for 2 weeks with a soil drench of allopurinol. after allopurinol treatment, leaves of n(2)-fed, ureide-producing legumes ... | 1986 | 16664857 |
| regulation of the soybean-rhizobium nodule symbiosis by shoot and root factors. | the availability of soybean mutants with altered symbiotic properties allowed an investigation of the shoot or root control of the relevant phenotype. by means of grafts between these mutants and wild-type plants (cultivar bragg and williams), we demonstrated that supernodulation as well as hypernodulation (nitrate tolerance in nodulation and lack of autoregulation) is shoot controlled in two mutants (nts382 and nts1116) belonging most likely to two separate complementation groups. the supernodu ... | 1986 | 16665072 |
| the occurrence of phytoferritin and its relationship to effectiveness of soybean nodules. | polyacrylamide gel electrophoresis and electron microscopy revealed that accumulation of iron-protein in soybean nodules is influenced by nodule age, mutation in bradyrhizobia, and rhizobial/bradyrhizobial strain-soybean cultivar interactions. iron-protein concentrations (micrograms per milligram protein) were inversely related to heme concentrations (nanomoles per milligram protein), with correlation coefficients (r values) ranging from -0.98 in young nodules to -0.83 in mature ones. bradyrhizo ... | 1987 | 16665240 |
| uptake and metabolism of carbohydrates by bradyrhizobium japonicum bacteroids. | bradyrhizobium japonicum bacteroids were isolated anaerobically and were supplied with (14)c-labeled trehalose, sucrose, udp-glucose, glucose, or fructose under low o(2) (2% in the gas phase). uptake and conversion of (14)c to co(2) were measured at intervals up to 90 minutes. of the five compounds studied, udp-glucose was most rapidly absorbed but it was very slowly metabolized. trehalose was the sugar most rapidly converted to co(2), and fructose was respired at a rate at least double that of ... | 1987 | 16665284 |
| nitrate induced regulation of nodule formation in soybean. | nodule formation was inhibited by exposing soybean plants to nitrate in plastic growth pouches. exposure to 15 millimolar nitrate resulted in a 2.5-fold decrease in the number of nodules formed in the region of the primary root above the mark made at the time of inoculation to indicate the position of the root tip. serial section analysis of bradyrhizobium infections in this region revealed that infection initiation was inhibited approximately 3-fold by exposure to nitrate. both initial cortical ... | 1987 | 16665428 |
| responses of rj(1) and rj(1) soybean isolines to inoculation with bradyrhizobium japonicum. | we evaluated the symbiotic phenotypes of nodulation-restrictive and normal soybean isolines by inoculating clark (genotypically rj(1)rj(1)) and mutant clark-rj(1) (genotypically rj(1)rj(1)) seedlings in plastic growth pouches. nodules first appeared on clark seedlings inoculated with bradyrhizobium japonicum usda 94 after 6 days. the mean number of nodules per plant was 13.9 +/- 0.8 after 24 days. in contrast, clark-rj(1) seedlings first nodulated at 12 days, and the mean number of nodules per p ... | 1987 | 16665600 |
| regulation of nodulation in the soybean-rhizobium symbiosis : strain and cultivar variability. | double inoculation (15 h apart) of the soybean cultivar williams with bradyrhizobium japonicum i-110ars reveals a rapid regulatory plant response that inhibits nodulation of distal portions of the primary root (m pierce, wd bauer 1984 plant physiol 73: 286-290). only living, homologous rhizobia elicit the response. we conducted similar double inoculation experiments to test the hypothesis that this is a universal phenomenon in soybean symbioses. we investigated interactions of the cultivar mccal ... | 1987 | 16665616 |
| glycine-glomus-rhizobium symbiosis: v. effects of mycorrhiza on nodule activity and transpiration in soybeans under drought stress. | soybean (glycine max [l.] merr.) plants were nodulated (bradyrhizobium japonicum) and either inoculated with the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae (nicol. & gerd.) gerd. and trappe or left uncolonized. all plants were grown unstressed for 21 days initially. after this period, some vam and non-vam plants were exposed to four 8-day drought cycles while others were kept well watered. drought cycles were terminated by rewatering when soil moisture potentials reached -1.2 m ... | 1987 | 16665641 |
| carbohydrate, organic acid, and amino acid composition of bacteroids and cytosol from soybean nodules. | metabolites in bradyrhizobium japonicum bacteroids and in glycine max (l.) merr. cytosol from root nodules were analyzed using an isolation technique which makes it possible to estimate and correct for changes in concentration which may occur during bacteroid isolation. bacteroid and cytosol extracts were fractionated on ion-exchange columns and were analyzed for carbohydrate composition using gas-liquid chromatography and for organic acid and amino acid composition using high performance liquid ... | 1987 | 16665774 |
| effect of nitrate on the organic acid and amino acid composition of legume nodules. | nitrate supplied to legume plants inhibits the activity of nitrogenase in rhizobium bacteroids in root nodules. the accumulation of amino n which is known to occur in glycine max (l.) merr. nodules as nitrogenase activity declines was studied in more detail by analysis of changes in free amino acid composition in response to high nitrate supply. a 6-fold increase in asparagine concentration in bradyrhizobium japonicum bacteroids was found about the time of maximum nitrogenase inhibition. however ... | 1987 | 16665775 |
| uniformity of the microsymbiont population from soybean nodules with respect to buoyant density. | the microsymbiont population in soybean root nodules (glycine max l. cv williams 82 inoculated with bradyrhizobium japonicum 2143) was characterized during symbiotic development to determine the extent of heterogeneity in this population. the microsymbiont population was isolated by centrifugation through a continuous sucrose gradient (44 to 57% weight to weight ratio) and appeared homogeneous at each age examined up to 26 days after planting based on the symmetrical distribution of the populati ... | 1988 | 16665972 |
| efficiency of nodule initiation in cowpea and soybean. | when serial dilutions of a suspension of bradyrhizobium japonicum strain 138 were inoculated onto both soybean and cowpea roots, the formation of nodules in the initially susceptible region of the roots of both hosts was found to be linearly dependent on the log of the inoculum dosage until an optimum dosage was reached. approximately 30- to 100-fold higher dosages were required to elicit half-maximal nodulation on cowpea than on soybean in the initially susceptible zone of the root. however, at ... | 1988 | 16666056 |
| regulation of o(2) concentration in soybean nodules observed by in situ spectroscopic measurement of leghemoglobin oxygenation. | a fiber optic spectrophotometric system was used to monitor the in vivo oxygenation of leghemoglobin in intact, attached soybean root nodules (glycine max l. merr. x usda 16 bradyrhizobium japonicum) which were flattened during development by growth in narrow, glass-walled cuvettes. when equilibrated at an external po(2) of 20 kilopascals, leghemoglobin was 36.6 +/- 5.4% oxygenated, a value estimated to represent an infected cell o(2) concentration of 21.5 nanomolar. increasing the external po(2 ... | 1988 | 16666136 |
| when does the self-regulatory response elicited in soybean root after inoculation occur? | the inoculation of soybean (glycine max l.) roots with bradyrhizobium japonicum produces a regulatory response that inhibits nodulation in the younger regions of the roots. by exposing the soybean roots to live homologous bacteria for only a short period of time, the question of whether or not early interactions of rhizobia with root cells, prior to infection, elicit this regulatory response has been explored. b. japonicum cells mixed with infective bacteriophages were applied to the roots and t ... | 1988 | 16666343 |
| selection and initial characterization of partially nitrate tolerant nodulation mutants of soybean. | since no(3) (-) availability in the rooting medium seriously limits symbiotic n(2) fixation by soybean (glycine max [l.] merr.), studies were initiated to select nodulation mutants which were more tolerant to no(3) (-) and were adapted to the midwest area of the united states. three independent mutants were selected in the m(2) generation from ethyl methanesulfonate or n-nitroso-n-methylurea mutagenized williams seed. all three mutants (designated nod1-3, nod2-4, and nod3-7) were more extensivel ... | 1989 | 16666510 |
| occurrence of h(2)-uptake hydrogenases in bradyrhizobium sp. (lupinus) and their expression in nodules of lupinus spp. and ornithopus compressus. | fifty-four strains of bradyrhizobium sp. (lupinus) from worldwide collections were screened by a colony hybridization method for the presence of dna sequences homologous to the structural genes of the bradyrhizobium japonicum hydrogenase. twelve strains exhibited strong colony hybridization signals, and subsequent southern blot hybridization experiments showed that they fell into two different groups on the basis of the pattern of ecori fragments containing the homology to the hup probe. all str ... | 1989 | 16666550 |
| in vivop nmr spectroscopic studies of soybean bradyrhizobium symbiosis: i. optimization of parameters. | (31)p nmr spectroscopy was used to study in vivo the symbiotic state established between soybean (glycine max [l.] merr. cv williams) and bradyrhizobium japonicum (usda 110 and 138). different experimental conditions were used to maintain perfused, respiring detached or attached nodules in an nmr magnet. the ph of the perfusion medium affected the cytoplasmic ph and the resolution of the spectra. the internal pi content and distribution were assessed as a function of nodule age and green-house g ... | 1989 | 16666690 |
| cytokinin production by bradyrhizobium japonicum. | although there is considerable circumstantial evidence for the involvement of cytokinins in legume nodulation, the cytokinins produced by rhizobia have not been well characterized. bradyrhizobium japonicum 61a68, a bacterium which nodulates soybean (glycine max [l.] merr.), was grown in defined medium. cytokinins were purified from the culture medium by amberlite xad-2 chromatography and fractionated by column chromatography on sephadex lh-20 in 35% ethanol. pooled fractions from the sephadex co ... | 1989 | 16666691 |
| leghemoglobin in lupin plants (lupinus albus cv multolupa). | leghemoglobin was localized by immunogold techniques in nodules of lupinus albus cv multolupa inoculated with bradyrhizobium sp. (lupinus) strain islu 16. the protein localization was performed in nodules embedded in spurr's and araldite epoxy resins and lowycryl k4m. a very good preservation of both the ultrastructure and antigenicity was obtained with the tissues embedded in araldite following glutaraldehyde fixation and unpostfixed in osmium tetroxide. lupin leghemoglobin is a stable and abun ... | 1989 | 16666792 |
| cytochrome mutants of bradyrhizobium induced by transposon tn5. | transposon tn5 was used to mutate bradyrhizobium japonicum usda 61n. from over 5000 clones containing tn5, 12 were selected and purified using a chemical reaction to identify oxidase-deficient clones. four classes of mutants were identified based on the alterations in cytochromes. most of the mutants had alterations in more than one cytochrome. southern hybridization analysis of restricted genomic dna of a representative strain of each class demonstrated that each mutant had a single tn5 insert. ... | 1989 | 16666807 |
| isoenzymes of superoxide dismutase in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp. | the activity and isozymic composition of superoxide dismutase (sod; ec 1.15.1.1) were determined in nodules of phaseolus vulgaris l., pisum sativum l., and vigna unguiculata (l.) walp. formed by rhizobium phaseoll 3622, r. ieguminosarum 3855, and bradyrhizobium sp. br7301, respectively. a mn-sod was present in rhizobium and two in bradyrhizobium and bacteroids. nodule mitochondria from all three legume species had a single mn-sod with similar relative mobility, whereas the cytosol contained seve ... | 1989 | 16666924 |
| lack of systemic suppression of nodulation in split root systems of supernodulating soybean (glycine max [l.] merr.) mutants. | wild-type soybean (glycine max [l] merr. cv bragg) and a nitrate-tolerant supernodulating mutant (nts382) were grown in split root systems to investigate the involvement of the autoregulation response and the effect of timing of inoculation on nodule suppression. in bragg, nodulation of the root portion receiving the delayed inoculation was suppressed nearly 100% by a 7-day prior inoculation of the other root portion with bradyrhizobium japonicum strain usda 110. significant suppression was also ... | 1989 | 16666934 |
| hydrogen inhibition of nitrogen reduction by nitrogenase in isolated soybean nodule bacteroids. | dihydrogen, a by-product of biological nitrogen fixation, is a competitive inhibitor of n(2) reduction by nitrogenase. to evaluate the significance of h(2) inhibition in vivo, we have measured the apparent inhibition constant for h(2) inhibition of n(2) reduction in bradyrhizobium japonicum bacteroids isolated from soybean nodules. the rate of n(2) reduction was measured as ammonia production by bacteroids incubated in a buffer containing 200 micromolar leghemoglobin and 10 millimolar succinate ... | 1989 | 16667084 |
| developmental regulation of enzymes of sucrose and hexose metabolism in effective and ineffective soybean nodules. | soybean (glycine max) nodules formed by inoculation with either an effective strain or an ineffective (noninvasive, nodule-forming) strain of bradyrhizobium japonicum were assayed for changes in developmental patterns of carbon metabolic enzymes of the plant nodule cells. of the enzyme activities measured, only sucrose synthase, glutamine synthetase, and alcohol dehydrogenase were altered in the ineffective nodules relative to the effective nodules. sucrose synthase and glutamine synthetase acti ... | 1990 | 16667280 |
| ureide assay for measuring nitrogen fixation by nodulated soybean calibrated by n methods. | we report experiments to quantify the relationships between the relative abundance of ureide-n in root-bleeding sap, vacuum-extracted sap, and hot water extracts of stems and petioles of nodulated soybean (glycine max [l.] merrill cv bragg) and the proportion of plant n derived from nitrogen fixation. additional experiments examined the effects of plant genotype and strain of rhizobia on these relationships. in each of the five experiments reported, plants of cv bragg (experiment 1), cv lincoln ... | 1990 | 16667494 |
| measurement of nitrogen fixation by soybean in the field using the ureide and natural n abundance methods. | nitrogen fixation by field-grown soybean (glycine max [l.] merrill) was assessed by the natural (15)n abundance and ureide methods. the field sites (five) and genotypes (six, plus two levels of inoculation on bragg) were chosen to provide a range of proportions of plant n derived from nitrogen fixation (p). genotypes k466, k468, nts1007, and nts1116 and davis were included on the basis of their reported tolerance of the suppressive effects of nitrate on nodulation and nitrogen fixation. bragg wa ... | 1990 | 16667527 |
| effect of po(2) on growth and nodule functioning of symbiotic cowpea (vigna unguiculata l. walp.). | nodulated cowpea (vigna unguiculata l. walp. cv vita 3:bradyrhizobium cb 756) plants were cultured with their whole root system or crown root nodulation zone maintained for periods from 5 to 69 days after planting in atmospheres containing a range of po(2) (1-80%, v/v) while the rest of the plant grew in normal air. growth (dry matter yield) and n(2) fixation were largely unaffected by po(2) from 10 to 40%. decrease in fixation at po(2) below 5% was due to lower nodulation and nodule mass and, a ... | 1990 | 16667605 |
| effect of po(2) during growth on the gaseous diffusional properties of nodules of cowpea (vigna unguiculata l. walp.). | adaptations of nodules of cowpea (vigna unguiculata l. walp. cv vita 3: bradyrhizobium cb 756) to growth in po(2) ranging from 1 to 80% o(2) (volume/volume) involved both readily reversible mechanisms of adjustment and more stable alterations which together resulted in nodules with widely ranging resistance to diffusion of gases. those grown in subambient po(2) (1-5% o(2) were altered such that rapid diffusional adjustment was unable to prevent irreversible loss of nitrogenase on their transfer ... | 1990 | 16667606 |
| photosynthesis and photosynthate partitioning in n(2)-fixing soybeans. | leaf area, chlorophyll content, net co(2) photoassimilation, and the partitioning of fixed carbon between leaf sucrose and starch and soluble protein were examined in glycine max (l) merr. cv williams grown under three different nitrogen regimes. one group (nod+/+) was inoculated with bradyrhizobium and watered daily with a nutrient solution containing 6 millimolar nh(4)no(3). a second set (nod+/-) was inoculated and had n(2) fixation as its sole source of nitrogen. a third group (nod(-)) was no ... | 1990 | 16667695 |
| ammonia (c-methylamine) transport across the bacteroid and peribacteroid membranes of soybean root nodules. | [(14)c]methylamine (ma; an analog of ammonia) was used to investigate ammonia transport across the bacteroid and peribacteroid membranes (pbm) from soybean (glycine max) root nodules. free-living bradyrhizobium japonicum usda110 grown under nitrogen-limited conditions showed rapid ma uptake with saturation kinetics at neutral ph, indicative of a carrier. exchange of accumulated ma for added ammonia occurred, showing that the carrier recognized both nh(4) (+) and ch(3)nh(3) (+). ma uptake by isol ... | 1990 | 16667721 |
| glycine-glomus-bradyrhizobium symbiosis : x. relationships between leaf gas exchange and plant and soil water status in nodulated, mycorrhizal soybean under drought stress. | soybean (glycine max [l.] merr.) plants were colonized by the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae (nicol. and gerd.) gerd. and trappe (vam plants) or fertilized with kh(2)po(4) (nonvam plants) and grown for 50 days under controlled conditions. plants were harvested over a 4-day period during which the soil was permitted to dry slowly. the harvest was terminated when leaf gas exchange was no longer measurable due to drought stress. significantly different effects in shoot ... | 1990 | 16667771 |
| early autoregulation of symbiotic root nodulation in soybeans. | autoregulation of symbiotic root nodulation in soybean seedlings (glycine max l. merrill cv pride 216) was studied following double inoculation of primary roots with bradyrhizobium japonicum 110. when the second inoculation was given 10 or 17 hours after the first, the nodulation in the first-inoculated region of the root was suppressed. the effect was eliminated if b. japonicum 110 containing tn5 insertions in the ;common' nod abc genes was used for the second inoculation, indicating the requir ... | 1990 | 16667864 |
| effect of inoculation and nitrogen on isoflavonoid concentration in wild-type and nodulation-mutant soybean roots. | the isoflavones, daidzein and genistein, have been isolated and identified as the major inducers of nod genes of bradyrhizobium japonicum. the common nod genes of rhizobia are in turn responsible for stimulating root hair curling and cortical root cell division, the earliest steps in the host response. this study evaluated whether there was a relationship between root isoflavonoid production and the hypernodulation phenotype of selected soybean (glycine max [l.] merr.) mutants. three independent ... | 1991 | 16668002 |
| effect of po(2) on the formation and status of leghemoglobin in nodules of cowpea and soybean. | nodulated cowpea (vigna unguiculata [l.] walp. cv vita 3: bradyrhizobium strain cb756) and soybean (glycine max [l.] merr. cv white eye: bradyrhizobium strain cb1809) were grown with their root systems maintained in a flowing gas stream containing a range of po(2) (1-80%, v/v) in n(2) for up to 28 days after planting. at the extremes of sub- and supra-ambient po(2), the levels of leghemoglobin (lb) in nodules were reduced. however, neither the proportional composition of lb component proteins (e ... | 1991 | 16668046 |
| effect of localized nitrate application on isoflavonoid concentration and nodulation in split-root systems of wild-type and nodulation-mutant soybean plants. | although isoflavonoids are known to be inducers of nod genes in bradyrhizobium japonicum, it was recently proposed that internal root levels of isoflavonoids may be important in nodule development on soybean (glycine max [l.] merr.). the hypernodulating soybean mutants were shown to accumulate higher root concentrations of isoflavonoid compounds (daidzein, genistein, and coumestrol) and to be more extensively nodulated than was the williams parent when inoculated with b. japonicum. the hypernodu ... | 1991 | 16668097 |
| effect of increases in oxygen concentration during the argon-induced decline in nitrogenase activity in root nodules of soybean. | when intact nodulated roots of soybean (glycine max l. merr. nodulated with bradyrhizobium japonicum strain usda 16) were exposed to an atmosphere lacking n(2) gas (ar:o(2) 80:20), total nitrogenase activity (measured as h(2) evolution) and respiration (co(2) evolution) declined with time of exposure. in ar-inhibited nodules, when the o(2) concentration in the rhizosphere was increased in a linear ;ramp' of 2.7% per minute, 93% of the original h(2) evolution and 99% of the co(2) evolution could ... | 1991 | 16668196 |
| adaptation of nodulated soybean (glycine max l. merr.) to growth in rhizospheres containing nonambient po(2). | nodulated soybean (glycine max l. merr. cv white eye inoculated with bradyrhizobium japonicum strain cb 1809) plants were cultured in the absence of combined n from 8 to 28 days with their root systems maintained continuously in 1, 2.5, 5, 10, 20, 40, 60, or 80% o(2) (volume/volume) in n(2). plant dry matter yield was unaffected by partial pressure of oxygen (po(2)) and n(2) fixation showed a broad plateau of maximum activity from 2.5 to 40 or 60% o(2). slight inhibition of nitrogenase activity ... | 1991 | 16668248 |
| root isoflavonoid response to grafting between wild-type and nodulation-mutant soybean plants. | it was previously reported that the hypernodulating soybean (glycine max [l.] merr.) mutants, derived from the cultivar williams, had higher root concentration of isoflavonoid compounds (daidzein, genistein, and coumestrol) than did williams at 9 to 12 days after inoculation with bradyrhizobium japonicum. these compounds are known inducers of nod genes in b. japonicum and may be involved in subsequent nodule development. the current study involving reciprocal grafts between nod1-3 (hypernodulati ... | 1991 | 16668330 |
| gibberellins and the legume-rhizobium symbiosis : i. endogenous gibberellins of lima bean (phaseolus lunatus l.) stems and nodules. | the content of gibberellin-like substances in nodules formed by bradyrhizobium species strain 127e14 on roots of lima bean (phaseolus lunatus l.) has been previously found to be relatively high. the objectives of the present study were to purify and identify the endogenous gibberellins from the stems and nodules of lima bean. by sequential silica gel partition column chromatography, c(18) reverse-phase high performance liquid chromatography, and combined gas chromatography-mass spectrometry, the ... | 1992 | 16668617 |
| characterization of delta-aminolevulinic acid formation in soybean root nodules. | formation of the heme precursor delta-aminolevulinic acid (ala) was studied in soybean root nodules elicited by bradyrhizobium japonicum. glutamate-dependent ala formation activity by soybean (glycine max) in nodules was maximal at ph 6.5 to 7.0 and at 55 to 60 degrees c. a low level of the plant activity was detected in uninfected roots and was 50-fold greater in nodules from 17-day-old plants; this apparent stimulation correlated with increases in both plant and bacterial hemes in nodules comp ... | 1992 | 16668729 |
| pyrroline-5-carboxylate reductase in soybean nodules : comparison of the enzymes in host cytosol, bradyrhizobium japonicum bacteroids, and cultures. | characteristics of pyrroline-5-carboxylate reductase (p5cr) from bradyrhizobium japonicum bacteroids and cultured rhizobia were compared with those of the enzyme in soybean nodule host cytosol. reductase from host cytosol differed from that in bacteroids in: (a) the effect of ph on enzymic activity, (b) the capacity to catalyze both reduction of pyrroline-5-carboxylic acid and nad(+)-dependent proline oxidation, (c) apparent affinities for pyrroline-5-carboxylic acid, and (d) sensitivities to in ... | 1992 | 16668837 |