Publications

sequence and analysis of the rpon sigma factor gene of rhizobium sp. strain ngr234, a primary coregulator of symbiosis.	we report the nucleotide sequence of the rpon gene from broad-host-range rhizobium sp. strain ngr234 and analyze the encoded rpon protein, a sigma factor. comparative analysis of the deduced amino acid sequence of rpon from ngr234 with sequences from other gram-negative bacteria identified a perfectly conserved rpon box unique to rpon sigma factors. symbiotic regulatory phenotypes were defined for a site-directed internal deletion within the coding sequence of the rpon gene of rhizobium strain n ...	1990	2211497
genetic map of rhizobium meliloti megaplasmid prmesu47b.	a circular linkage map of the rhizobium meliloti megaplasmid prmesu47b was constructed. the map consists of transposon insertions carrying alternating antibiotic resistance markers linked by phi m12 transduction. data from conjugation experiments utilizing donor strains carrying tn5-orit insertions in the megaplasmid supported the proposed genetic map. in addition, the positions of previously identified fix, exopolysaccharide synthetic, thiamine synthetic, and c4-dicarboxylate transport loci on ...	1990	2158971
inhibition by agrobacterium tumefaciens and pseudomonas savastanoi of development of the hypersensitive response elicited by pseudomonas syringae pv. phaseolicola.	injection into tobacco leaves of biotype 1 agrobacterium tumefaciens or of pseudomonas savastanoi inhibited the development of a visible hypersensitive response to the subsequent injection at the same site of pseudomonas syringae pv. phaseolicola. this interference with the hypersensitive response was not seen with injection of bacterial growth medium or escherichia coli cells. live a. tumefaciens cells were required for the inhibitory effect. various mutants and strains of a. tumefaciens were e ...	1990	2211508
systemic movement and symptom production following agroinoculation with a single dna of tomato yellow leaf curl geminivirus (thailand).	two different dna species were cloned from purified tomato yellow leaf curl geminivirus particles after annealing a specific primer to virus dna and generating a second strand; both were approximately 2.8 kbp in length. one clone contains sequences which hybridize to the coat protein gene of tomato golden mosaic virus and most likely represents the a dna of tomato yellow leaf curl virus (thailand). the other clone may represent the b dna of this geminivirus. both clones contain short sequences w ...	1990	2219706
involvement of azospirillum brasilense plasmid dna in the production of indole acetic acid.	indole acetic acid (iaa) production in azospirillum brasilense strain sp245 is controlled by a 85 mda plasmid naturally present in this bacterium. in the presence of l-tryptophan, anthranilic acid production and almost no iaa production occurs in a derivative strain harbouring a tn5-mob insertion in the 85 mda plasmid. agrobacterium tumefaciens strain gm19023, upon transfer of tn5-mob labelled 85 mda plasmid of a. brasilense sp245, gains the ability to produce anthranilic acid.	1990	2283026
mutational analysis of the virg protein, a transcriptional activator of agrobacterium tumefaciens virulence genes.	the virg protein of agrobacterium tumefaciens is required in conjunction with the vira protein for transcriptional activation of the virulence (vir) genes in response to plant phenolic compounds. these proteins are members of a family of two component regulatory systems. vir genes are activated via a cascade of phosphorylation reactions involving a specific aspartic acid residue of the virg protein. we have conducted a mutational analysis of the virg protein. by mutating conserved and nonconserv ...	1990	2211523
cell-associated oligosaccharides of bradyrhizobium spp.	we report the initial characterization of the cell-associated oligosaccharides produced by four bradyrhizobium strains: bradyrhizobium japonicum usda 110, usda 94, and atcc 10324 and bradyrhizobium sp. strain 32h1. the cell-associated oligosaccharides of these strains were found to be composed solely of glucose and were predominantly smaller than the cyclic beta-1,2-glucans produced by agrobacterium and rhizobium species. linkage studies and nuclear magnetic resonance analyses demonstrated that ...	1990	2294083
isolation of the replication dna region from a rhizobium plasmid and examination of its potential as a replicon for rhizobiaceae cloning vectors.	the dna region essential for replication and stability of a native plasmid (ptm5) from rhizobium sp. (hedysarum) has been identified and isolated within a 5.4-kb psti restriction fragment. the isolation of this region was accomplished by cloning endonuclease-restricted ptm5 dna into a cole1-type replicon and selecting the recombinant plasmids containing the ptm5 replicator (ptm5 derivative plasmids) by their ability to replicate in rhizobium. dna homology studies revealed that ptm5-like replicon ...	1990	2217572
identification of a caulobacter basal body structural gene and a cis-acting site required for activation of transcription.	the genes that encode the components and regulatory proteins of the caulobacter crescentus flagellum are transcribed at specific times in the cell cycle. one of these genes, flbn, is required early in the flagellar assembly process. the flbn gene was cloned and sequenced, and the time of transcription activation was determined. the derived amino acid sequence indicates that fibn encodes a 25-kilodalton protein with a cleavable leader peptide. the flbn-encoded protein has 30.8% identity with the ...	1990	2211524
revised 2.3 a structure of porcine pepsin: evidence for a flexible subdomain.	a revised three-dimensional crystal structure of ethanol-inhibited porcine pepsin refined to an r-factor of 0.171 at 2.3 a resolution is presented and compared to the refined structures of the fungal aspartic proteinases: penicillopepsin, rhizopuspepsin, and endothiapepsin. pepsin is composed of two nearly equal n and c domains related by an intra dyad. the overall polypeptide fold and active site structures are homologous for pepsin and the fungal enzymes. the weak inhibition of pepsin by ethan ...	1990	2217165
rhizobium meliloti nodd genes mediate host-specific activation of nodabc.	to differentiate among the roles of the three nodd genes of rhizobium meliloti 1021, we studied the activation of a nodc-lacz fusion by each of the three nodd genes in response to root exudates from several r. meliloti host plants and in response to the flavone luteolin. we found (i) that the nodd1 and nodd2 products (nodd1 and nodd2) responded differently to root exudates from a variety of hosts, (ii) that nodd1 but not nodd2 responded to luteolin, (iii) that nodd2 functioned synergistically wi ...	1990	2298703
binding of the regulatory protein virg to the phased signal sequences upstream from virulence genes on the hairy-root-inducing plasmid.	the virg protein is a positive regulator for the virulence genes of which expression is induced by a plant factor, and is essential for agrobacterium pathogenicity on dicotyledonous plants. the virg protein of the hairy-root-inducing plasmid a4 was overproduced in escherichia coli cells, and purified to homogeneity. dnase i footprinting experiments revealed that the purified virg protein was bound to the upstream region of virulence genes including the phased vir box sequences, which had been pr ...	1990	2231718
functional and evolutionary relatedness of genes for exopolysaccharide synthesis in rhizobium meliloti and rhizobium sp. strain ngr234.	rhizobium meliloti su47 and rhizobium sp. strain ngr234 produce distinct exopolysaccharides that have some similarities in structure. r. meliloti has a narrow host range, whereas rhizobium strain ngr234 has a very broad host range. in cross-species complementation and hybridization experiments, we found that several of the genes required for the production of the two polysaccharides were functionally interchangeable and similar in evolutionary origin. ngr234 exoc and exoy corresponded to r. meli ...	1990	2203745
symbiotic pseudorevertants of rhizobium meliloti ndv mutants.	nodule development (ndv) mutants of rhizobium meliloti cannot invade alfalfa to establish a nitrogen-fixing symbiosis and instead induce the formation of small, white, unoccupied nodules on alfalfa roots. such mutants also fail to produce the unusual cyclic oligosaccharide beta-(1----2)-glucan and show defects in several aspects of vegetative growth and function. here we show that ndv mutants are severely reduced, although not totally deficient, in the ability to attach to and initiate infection ...	1990	2307652
either of two nod gene loci can complement the nodulation defect of a nod deletion mutant of rhizobium leguminosarum bv viciae.	a deletion mutant of rhizobium leguminosarum biovar viciae lacking the host-specific nodulation (nod) gene region (nodfel nodmnt and nodo) but retaining the other nod genes (nodd nodabcij) was unable to nodulate peas or vicia hirsuta, although it did induce root hair deformation. the mutant appeared to be blocked in its ability to induce infection threads and could be rescued for nodulation of v. hirsuta in mixed inoculation experiments with an exopolysaccharide deficient mutant (which is also n ...	1990	2233683
3-oxoacyl-(acyl-carrier protein) reductase from avocado (persea americana) fruit mesocarp.	the nadph-linked 3-oxoacyl-(acyl-carrier protein) (acp) reductase (ec 1.1.1.100), also known as 'beta-ketoacyl-acp reductase', has been purified from the mesocarp of mature avocado pears (persea americana). the enzyme is inactivated by low ionic strength and low temperature. on sds/page under reducing conditions, purified 3-oxoacyl-acp reductase migrated as a single polypeptide giving a molecular mass of 28 kda. gel-filtration chromatography gave an apparent native molecular mass of 130 kda, sug ...	1990	2244875
correction: characterization of the virb operon from agrobacterium tumefaciens ti plasmid.		1990	2307685
binding-protein-dependent lactose transport in agrobacterium radiobacter.	agrobacterium radiobacter ncib 11883 was grown in lactose-limited continuous culture at a dilution rate of 0.045/h. washed cells transported [14c]lactose and [methyl-14c]beta-d-thiogalactoside, a nonmetabolisable analog of lactose, at similar rates and with similar affinities (km for transport, less than 1 microm). transport was inhibited to various extents by the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, by unlabeled beta-galactosides and d-galactose, and by osmotic s ...	1990	2318800
osmosensitivity phenotypes of agrobacterium tumefaciens mutants that lack periplasmic beta-1,2-glucan.	the periplasmic cyclic beta-1,2-glucan of agrobacterium tumefaciens is believed to maintain high osmolarity in the periplasm during growth of the bacteria on low-osmotic-strength media. strains with mutations in the chva or chvb gene do not accumulate beta-1,2-glucan in their periplasm and exhibit pleiotropic phenotypes, including inability to form crown gall tumors on plants. we examined the effects of medium osmolarity to determine whether some or all of these phenotypes result from suboptimal ...	1990	2318812
virulence genes promote conjugative transfer of the ti plasmid between agrobacterium strains.	certain virulence region operons of the agrobacterium tumefaciens ti plasmid promoted conjugative ti plasmid transfer. mutations in the vir region of ptic58 inhibited conjugative plasmid transfer between a. tumefaciens strains. mutations in vira, virg, 5' virb, and vire had the greatest effect on plasmid transfer, and mutations in virc had no effect. transfer inhibition in vir mutants occurred in the presence or absence of acetosyringone.	1990	2318813
re-examination of cellular cyclic beta-1,2-glucans of rhizobiaceae: distribution of ring sizes and degrees of glycerol-1-phosphate substitution.	gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of agrobacterium radiobacter, isolate ii, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans t ...	1990	2321938
fnr and its role in oxygen-regulated gene expression in escherichia coli.	bacteria which can grow in different environments have developed regulatory systems which allow them to exploit specific habitats to their best advantage. in the facultative anaerobe escherichia coli two transcriptional regulators controlling independent networks of oxygen-regulated gene expression have been identified. one is a two-component sensor-regulator system (arcb-a), which represses a wide variety of aerobic enzymes under anaerobic conditions. the other is fnr, the transcriptional regul ...	1990	2248796
virg, an agrobacterium tumefaciens transcriptional activator, initiates translation at a uug codon and is a sequence-specific dna-binding protein.	the agrobacterium tumefaciens ti plasmid virg locus, in conjunction with vira and acetosyringone, activates transcription of the virulence (vir) genes. insertional and deoxyoligonucleotide-directed mutagenesis studies showed that both octopine and nopaline ti plasmid virg genes initiate translation at a uug codon. virg protein initiated at this uug codon was found to be 241 amino acid residues in length and had an apparent molecular mass of 27.1 kilodaltons. a salmonella typhimurium trp-virg tra ...	1990	2307647
rhizobium leguminosarum exob mutants are deficient in the synthesis of udp-glucose 4'-epimerase.	rhizobium leguminosarum bv. viciae exo- mutant strains rbl5523,exo7::tn5,rbl5523,exo8::tn5 and rbl5523,exo52::tn5 are affected in nodulation and in the syntheses of lipopolysaccharide, capsular polysaccharide, and exocellular polysaccharide. these mutants were complemented for nodulation and for the syntheses of these polysaccharides by plasmid pmp2603. the gene in which these mutants are defective is functionally homologous to the exob gene of rhizobium meliloti. the repeating unit of the resid ...	1990	2250016
atp sulphurylase activity of the nodp and nodq gene products of rhizobium meliloti.	the symbiotic bacterium rhizobium meliloti stimulates alfalfa (medicago sativa l.) roots to undergo morphogenesis and form nitrogen-fixing nodules. it has been proposed that the bacterial genes nodabc, common to all rhizobium, are required for synthesis of an oligosaccharide factor, which is converted to a sulphated form (nodrm-1) by the products of the r. meliloti-specific genes nodh and nodq1-5; nodrm-1 elicits host-specific plant responses. previously we have shown that the nodp gene is homol ...	1990	2250719
molecular characterization of the nodulation gene, nodt, from two biovars of rhizobium leguminosarum.	dna sequencing of the nodij region from rhizobium leguminosarum biovar trifolii revealed the nodt gene immediately downstream of nodj. dna hybridizations using a nodt-specific probe showed that nodt is present in several r. leguminosarum strains. interestingly, a flavonoid-inducible nodt gene homologue in r. leguminosarum bv. viciae is not in the nodabcij operon but is located downstream of nodmn. the sequence of the nodt gene from bv. viciae was determined and a comparison of the predicted amin ...	1990	2338917
plant nuclear factor asf-1 binds to an essential region of the nopaline synthase promoter.	we have characterized a tobacco nuclear factor that binds to the -118 region of the nopaline synthase (nos) promoter from the ti plasmid of agrobacterium tumefaciens. the binding site for this factor, identified by dnase i footprinting, encompasses the region from -138 to -103 of the nos promoter. this region, which contains a potential z-dna-forming sequence, was previously shown to be essential for nos promoter activity in transgenic tobacco. a synthetic 21-base pair sequence from the protecte ...	1990	2351681
nodule formation in soybeans by exopolysaccharide mutants of rhizobium fredii usda 191.	production of exopolysaccharides by rhizobium has been linked with efficient invasion and nodulation of leguminous plant roots by the bacteria. exopolysaccharide-deficient (exo) mutants of rhizobium fredii usda 191 were isolated following tn5-insertion mutagenesis. five phenotypically unique exo mutants were investigated for exopolysaccharide synthesis and their ability to nodulate soybeans. the exopolysaccharides produced by these mutants were analysed for polysaccharide composition by column c ...	1990	2351951
uptake of glycine betaine and its analogues by bacteroids of rhizobium meliloti.	bacteroids isolated from alfalfa nodules induced by rhizobium meliloti 102f34 transported glycine betaine at a constant rate for up to 30 min. addition of sodium salts greatly increased the uptake activity, whereas other salts or non-electrolytes had less effect. the apparent km for glycine betaine uptake was 8.3 microm and v was about 0.84 nmol min-1 (mg protein)-1 in the presence of 200 mm-nacl which gave maximum stimulation of the transport. supplementing bacteroid suspensions with various en ...	1990	2351954
nucleotide sequence of rhizobium loti nodc.		1990	2251130
dna sequence and translational product of a new nodulation-regulatory locus: syrm has sequence similarity to nodd proteins.	rhizobium meliloti nodulation (nod) genes are expressed when activated by trans-acting proteins in the nodd family. the nodd1 and nodd2 gene products activate nod promoters when cells are exposed to plant-synthesized signal molecules. alternatively, the same nod promoters are activated by the nodd3 gene when nodd3 is carried in trans along with a closely linked global regulatory locus, syrm (symbiotic regulator) (j. t. mulligan and s. r. long, genetics 122:7-18, 1989). in this article we report ...	1990	2361944
nucleotide sequence of rhizobium loti nodi.		1990	2251131
osmoregulation in agrobacterium tumefaciens: accumulation of a novel disaccharide is controlled by osmotic strength and glycine betaine.	we have investigated the mechanism of osmotic stress adaptation (osmoregulation) in agrobacterium tumefaciens biotype i (salt-tolerant) and biotype ii (salt-sensitive) strains. using natural-abundance 13c nuclear magnetic resonance spectroscopy, we identified all organic solutes that accumulated to significant levels in osmotically stressed cultures. when stressed, biotype i strains (c58, nt1, and a348) accumulated glutamate and a novel disaccharide, beta-fructofuranosyl-alpha-mannopyranoside, c ...	1990	2254260
agrobacterium tumefaciens t-dna gene 6b stimulates rol-induced root formation, permits growth at high auxin concentrations and increases root size.	all agrobacterium tumefaciens strains studied up to now transfer an active 6b gene to plant cells. however, the role of this gene in natural tumour induction is unknown. various effects of 6b on plant cell growth have been described, but the precise mechanism by which 6b causes these effects has not been elucidated. earlier experiments indicated that the 6b gene might increase auxin sensitivity as do the a. rhizogenes rol genes. the 6b gene from tm4 (t-6b) was therefore compared with the rolb an ...	1990	2259331
structural studies of a novel exopolysaccharide produced by a mutant of rhizobium meliloti strain rm1021.	the structure of a novel expolysaccharide obtained from a mutant of rhizobium meliloti strain rm1021 was elucidated by a combination of enzymic, chemical, and spectroscopic methods. the polysaccharide is composed of a disaccharide repeating-unit, beta-d-glcp-(1----3)-alpha-d-galp-(1----3), having a 6-o-acetyl group attached to most d-glucose residues and a 4,6-o-(1-carboxyethylidene) group attached to every d-galactose residue.	1990	2379191
dicarboxylic acid transport and regulation of nitrogen fixation in rhizobium meliloti.		1990	2379758
characterization of the virg binding site of agrobacterium tumefaciens.	expression of agrobacterium tumefaciens virulence (vir) genes is dependent on the presence of a conserved 'vir box' sequence in their 5' nontranscribed regions. the location and number of these sequences vary considerably in different vir genes. site-directed mutagenesis was used to identify the functional vir box(es) of virb, virc and vird. for virb expression both vir box b1 and b2 are required but only the vir box b1 is absolutely essential. of the five vir boxes of virc and vird two are requ ...	1990	2263453
defective viral dna ameliorates symptoms of geminivirus infection in transgenic plants.	nicotiana benthamiana was transformed with a single copy of a tandem repeat of subgenomic dna b isolated from plants infected with a kenyan isolate of the bipartite geminivirus african cassava mosaic virus. symptoms in transformed plants were less severe than in nontransformed controls when challenged with virus or cloned dna of kenyan or nigerian isolates. symptom amelioration was associated with the mobilization and amplification of the subgenomic dna, producing a comparable reduction in the a ...	1990	2385593
phosphorylation of the virg protein of agrobacterium tumefaciens by the autophosphorylated vira protein: essential role in biological activity of virg.	agrobacterium tumefaciens virulence genes are induced by plant signals through the vira-virg two-component regulatory system. the vira protein is a membrane-spanning sensor molecule that possesses an autophosphorylating activity, and the virg protein is a sequence-specific dna-binding protein. in this report, we demonstrate that the virg protein is phosphorylated by the vira protein and that the phosphate is directly transferred from the phosphorylated vira molecule (phosphohistidine) to the vir ...	1990	2394678
vird2 gene product from the nopaline plasmid ptic58 has at least two activities required for virulence.	virulence genes vird1 and vird2 are required for t-dna processing in agrobacterium tumefaciens. the regions within vird2 contributing to t-dna processing and virulence were investigated. some insertional mutations in vird2 prevented t-dna border endonucleolytic cleavage and produced an avirulent phenotype. however, a non-polar insertion immediately after bp 684 of the 1344 bp open reading frame of vird2 did not inhibit endonucleolytic cleavage but still caused a loss of virulence. this suggested ...	1990	2263456
agrobacterium in plant disease, biological disease control and plant genetic engineering.	plant pathogenic strains of agrobacterium cause crown gall and hairy-root diseases. the abnormal cell proliferation of diseased tissues results from elevated plant hormonal levels within them. these levels are consequent upon the transfer of dna portions (t-dna) from agrobacterium plasmids to host nuclei where they are integrated and where genes for hormone synthesis, borne on the t-dna, are expressed in transformed host cells. this process has been exploited in plant genetic engineering by prod ...	1990	2267572
dna sequence encoding the two structural genes for the uptake hydrogenase of rhizobium leguminosarum bv. viciae b10.		1990	2402452
[construction of frankia genomic libraries and isolation of clones homologous to nodulation genes from rhizobium leguminosarum].	high molecular genomic dnas were isolated by using the lysozyme plus achromopeptidase system from frankia strains at4, ccol and hr16, the root nodule endophytes of alnus, casuarina and hippophae respectively, and used to construct genomic libraries in plafr1, a broad host range cosmid vector within many gram-negative hosts. the genomic libraries were screened by in situ colony hybridization to identify clones homologous to common nodulation genes of rhizobium leguminosarum, based on the sequence ...	1990	2268450
biochemical characterization of avirulent exoc mutants of agrobacterium tumefaciens.	the synthesis of periplasmic beta(1-2)glucan is required for crown gall tumor formation by agrobacterium tumefaciens and for effective nodulation of alfalfa by rhizobium meliloti. the exoc (psca) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. we tested the possibility that the pleiotropic exoc phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic p ...	1990	2307661
agrobacterium plasmids encode structurally and functionally different loci for catabolism of agrocinopine-type opines.	agrobacterium tumefaciens strains c58, t37, k827 and j73, a. rhizogenes strains a4 and 15834, and a. radiobacter strain k299 were all susceptible to agrocin 84 and this sensitivity was enhanced in each case by addition of agrocinopines a and b. analysis of transconjugants showed that sensitivity of strain a4 to agrocin 84 was encoded by para4a and not by the rhizogenic plasmid, pria4. the acc region of the a. tumefaciens nopaline-type ti plasmid ptic58, contained on the recombinant plasmid pthh2 ...	1990	2270086
identification of bacterial periplasmic glycine betaine-binding protein after electrophoresis and affinity labeling.	antibodies were elicited in rabbits against periplasmic proteins obtained by cold osmotic shock from the gram-negative eubacterium rhizobium meliloti. when analyzed by crossed immunoelectrophoresis (cie), the periplasmic proteins gave rise to 20 distinct immunoprecipitates corresponding to the same number of bands in polyacrylamide gel electrophoresis (page) under non-denaturing conditions and in sds-page. the periplasmic glycine betaine-binding protein (gb-bp) was identified by autoradiography ...	1990	2273200
structure of the extracellular polysaccharide secreted by rhizobium leguminosarum var. phaseoli ciat 899.	the structure of the extracellular polysaccharide secreted by rhizobium leguminosarum var. phaseoli ciat 899 has been studied by methylation analysis. 1h-n.m.r. spectroscopy, and partial acid hydrolysis. the repeating unit is an octasaccharide made up of d-glucose, d-galactose, pyruvic acid, and acetic acid in the molar ratios 6:2:1.5:1.5. half of the terminal gal groups are 4,6-substituted by pyruvic acid acetal groups and the other half by o-acetyl groups at position 3. also, one of the 3-link ...	1990	2279241
chimeric genes and transgenic plants are used to study the regulation of genes involved in symbiotic plant-microbe interactions (nodulin genes).	nodulin genes are plant genes specifically activated during the formation of nitrogen-fixing nodules on leguminous plants. these genes are interesting to study since they are not only induced in a specific developmental fashion by signals coming directly or indirectly from the rhizobial symbiont, but are also expressed in a tissue-specific manner. by examining the expression of chimeric nodulin-reporter genes in transgenic legume plants it has been shown that nodule specific expression is mediat ...	1990	2279354
binary conjugational transfer system of vectors prk290 and plafri is proficient both ways between escherichia coli and rhizobium.	wide host range vector plasmids prk290 and plafri carrying genomic fragments of rhizobium are transferable both ways between r. meliloti and r. leguminosarum cells on the one hand and to e. coli cells on the other, in triparental matings involving e. coli cells carrying prk2013, the helper for tra functions to the vector plasmids. the vector plasmids prk290 and plafri can be employed for recovering clones harbored by r. leguminosarum and r. meliloti by transfer to rhizobium cells by direct matin ...	1990	2279773
oxygen-dependent desulphation of monomethyl sulphate by agrobacterium sp. m3c.	agrobacterium sp. m3c, previously isolated from canal-water for its ability to grow on monomethyl sulphate, degraded this ester with stoichiometric liberation of inorganic sulphate. in contrast with the biodegradation of monomethyl sulphate in hyphomicrobium sp., and of other longer-chain alkyl sulphates in pseudomonas spp., the pathway in agrobacterium appeared not to involve a sulphatase enzyme capable of catalysing ester-bond hydrolysis. no such sulphatase was detectable under a range of cond ...	1990	1368469
signal transduction pathway controlling synthesis of a class of degradative enzymes in bacillus subtilis: expression of the regulatory genes and analysis of mutations in degs and degu.	the rates of synthesis of a class of both secreted and intracellular degradative enzymes in bacillus subtilis are controlled by a signal transduction pathway defined by at least four regulatory genes: degs, degu, degq (formerly sacq), and degr (formerly prtr). the degs-degu proteins show amino acid similarities with two-component procaryotic modulator-effector pairs such as ntrb-ntrc, chea-chey, and envz-ompr. by analogy with these systems, it is possible that degs is a protein kinase which coul ...	1990	1688843
hypoosmotic adaptation in rhizobium meliloti requires beta-(1----2)-glucan.	beta-(1----2)-glucan, an unusual cyclic oligosaccharide, can be isolated from the periplasm of bacteria belonging to the family rhizobiaceae. data presented here suggest that the periplasmic beta-(1----2)-glucan of rhizobium meliloti plays a major role in osmotic adaptation. first, growth of r. meliloti in a low-osmolarity medium causes a large accumulation of periplasmic beta-(1----2)-glucan. second, mutations in the ndv genes, which prevent this accumulation of beta-(1----2)-glucan, reduce cel ...	1990	1689716
choline derivatives increase two different acid phosphatases in rhizobium meliloti and pseudomonas aeruginosa.	in pseudomonas aeruginosa and rhizobium meliloti several choline derivatives, utilized as the sole carbon and nitrogen source, increase acid phosphatase activity. the enzyme activity of both bacteria could be released into the surrounding medium by edta-lysozyme treatment. the r. meliloti acid phosphatase activity of crude periplasmic extracts measured with p-nitrophenylphosphate was not inhibited by the presence of 5 mm choline, betaine, trimethylammonium or phosphorylcholine. the activity coul ...	1990	1695086
production and epitope analysis of monoclonal antibodies against a rhizobium leguminosarum biovar trifolii strain.	heat-treated cells of rhizobium leguminosarum biovar trifolii strain 162x95 were used to produce monoclonal antibodies (mabs). the fusion produced three cross-reactive mabs and eight mabs specific for the immunizing strain and a group of five other r. trifolii strains from the same geographic region where 162x95 was isolated (california). seven mabs were analyzed by competitive enzyme-linked immunosorbent assay to determine the number of different epitopes detectable on strain 162x95. the result ...	1990	1697150
cloning and sequence analysis of truncated t-dna inserts from nicotiana tabacum.	transgenic plants produced by agrobacterium-mediated transformation usually have one or a few stable and intact t-dna insertions. however, in a significant number of the transformants southern blot analysis has revealed the occurrence of aberrant t-dna insertions missing one or both ends. during the study of this phenomenon, we obtained kmr nicotiana tabacum clones after cocultivation with an agrobacterium strain containing a promoterless nptii gene located internally in the t-dna. expression of ...	1990	1701747
the early nodulin transcript enod2 is located in the nodule parenchyma (inner cortex) of pea and soybean root nodules.	a pea cdna clone homologous to the soybean early nodulin clone pgmenod2 that most probably encodes a cell wall protein was isolated. the derived amino acid sequence of the pea enod2 protein shows that it contains the same repeating pentapeptides, proprohisglulys and proproglutyrgln, as the soybean enod2 protein. by in situ hybridization the expression of the enod2 gene was shown to occur only in the inner cortex of the indeterminate pea nodule. the transcription of the pea enod2 gene starts when ...	1990	1688528
an altered constitutive peptide in sym 5 mutants of pisum sativum l.	mutational analysis of pisum sativum l. was used to search for constitutive proteins that might function in nodule formation. the sym 5 locus is a mutational hot spot, represented by seven independently derived mutant lines with decreased nodulation. comparison of two-dimensional polyacrylamide gels of in vitro-translated root rna showed a consistent difference in the migrational pattern of one peptide. in the nodulating parental cultivar 'sparkle', a 66 kda peptide had a pi of 5.9. in four of t ...	1990	1714314
[system of transgenic plants and its application].		1990	1702547
anti-sense rna efficiently inhibits formation of the 10 kd polypeptide of photosystem ii in transgenic potato plants: analysis of the role of the 10 kd protein.	a chimeric gene encoding an anti-sense rna of the 10 kd protein of the water-splitting apparatus of photosystem ii of higher plants under the control of the camv 35s promoter was introduced into potato using agrobacterium based vectors. the expression of the anti-sense rna led to a significant reduction of the amounts of the 10 kd protein and rna in a number of transgenic plants. in three out of 36 plants tested, the level of the 10 kd protein was only up to 1-3% compared with the wild-type cont ...	1990	1697267
aminoglycoside-3''-adenyltransferase confers resistance to spectinomycin and streptomycin in nicotiana tabacum.	the bacterial gene aada encodes the enzyme aminoglycoside-3"-adenyltransferase that confers resistance to spectinomycin and streptomycin in escherichia coli. chimeric genes have been constructed for expression in plants, and were introduced into nicotiana tabacum by agrobacterium binary transformation vectors. spectinomycin or streptomycin in selective concentrations prevent greening of n. tabacum calli. transgenic clones, however, formed green calli on selective media containing spectinomycin, ...	1990	1966273
improved binary vectors for agrobacterium-mediated plant transformation.	improved plant transformation vectors were constructed which utilize the prihri origin of replication for highly stable maintenance in agrobacterium tumefaciens, the cole1 origin of replication for high copy maintenance in escherichia coli, and a gentamycin resistance gene as a strong selectable marker for bacteria. concise t-dna elements were engineered with border sequences from the tl-dna of ptia6, the tn5 neomycin phosphotransferase gene (npt ii) expressed from either camv 35s or mannopine s ...	1990	1966276
frequent spontaneous deletions of ri t-dna in agrobacterium rhizogenes transformed potato roots and regenerated plants.	the presence of t-dna was examined by southern blot analysis in 16 regenerated shoot lines derived from 6 agrobacterium rhizogenes-transformed root clones of solanum tuberosum l. cv. bintje. tr-dna, present in regenerated shoot lines from 3 out of 6 root clones was correlated with the presence of opines. one root clone produced opines up to 2.5 years of subculture. however, plant regeneration from and prolonged subculturing of this root clone resulted in loss of opine synthesis, caused by deleti ...	1990	1966386
a sensitive and simple paper chromatographic procedure for detecting neomycin phosphotransferase ii (nptii) gene expression.		1990	1966388
a previously unrecognized glutamine synthetase expressed in klebsiella pneumoniae from the glnt locus of rhizobium leguminosarum.	using glnt dna of rhizobium meliloti as a hybridization probe we identified a r. leguminosarum biovar phaseoli (r. l. phaseoli) locus (glnt) expressing a glutamine synthetase activity in klebsiella pneumoniae. a 2.2 kb dna fragment from r. l. phaseoli was cloned to give plasmid pmw5a, which shows interspecific complementation of a k. pneumoniae glna mutant. the cloned sequence did not show cross-hybridization to glna or glnii, the genes coding for two glutamine synthetase isozymes of rhizobium s ...	1990	1980142
human infections with strains of agrobacterium.		1990	1980510
production of a foreign protein product with genetically modified plant cells.	plant cells (nicotiana tabacum) were genetically engineered to produce a foreign protein, chloramphenicol acetyltransferase (cat), and the cat production from suspension cultures was investigated. suspension cultures were grown in a shake flask, a stirred fermenter, and a bubble-column fermenter. the cat production was growth related and the maximum activity was reached during the early stationary phase. a 41-day, semicontinuous stirred fermenter run, consisting of five sequential batch runs, de ...	1990	1366635
purification, properties and determinations of recognition sequence and cleavage site of restriction endonuclease from "agrobacterium gelatinovorum" iam 12617, a marine bacterium (agei).	a new restriction endonuclease, designated as agei, was purified from cell-free extracts of a marine bacterium, "agrobacterium gelatinovorum" iam 12617 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on heparin-sepharose cl-6b and deae-sepharose cl-6b and fplc on mono q (hr 5/5) and superose 12 (hr 10/30). the purified enzyme was homogeneous on sds-polyacrylamide gel disc electrophoresis and free from other phosphatase and exonuclease activities on lig ...	1990	1369292
specificity of octopine uptake by rhizobium and pseudomonas strains.	the octopine-utilizing strain agrobacterium tumefaciens b6s3 and three nonagrobacteria which had the capacity to utilize this opine were compared for octopine uptake. the characteristics of uptake by rhizobium meliloti a3 and strain b6s3 were similar. in both bacteria, uptake activity was inducible by octopine and by the related opine octopinic acid, and competition assays showed that these two opine substrates were accepted by the same uptake system with an equivalent affinity. cells of pseudom ...	1990	16348194
purification and properties of catechol 1,2-dioxygenase from rhizobium leguminosarum biovar viceae usda 2370.	the catechol 1,2-dioxygenase of rhizobium leguminosarum biovar viceae usda 2370 was purified 296-fold, yielding a homogeneous preparation with a specific activity of 51.1 u mg of protein. the molecular weight of the native protein was 70,000, with two identical subunits of 34,500 and 1 g-atom of iron per mol. the optimum ph for catalytic activity was 9.0 to 9.5.	1990	16348234
role of microniches in protecting introduced rhizobium leguminosarum biovar trifolii against competition and predation in soil.	the importance of microniches for the survival of introduced rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. the recolonized soils contained several species of soil microorganisms but were free of protozoa. part of these soil samples was inoculated with the flagellate bodo saltans, precultured on rhizobial cells. the introduced organisms were enumerated in different soil fractions by washing the soil, using a standardiz ...	1990	16348125
new field isolates of rhizobium leguminosarum biovar viciae that nodulate the primitive pea cultivar afghanistan in addition to modern cultivars.	a collection of 13 field isolates of rhizobium leguminosarum bv. viciae that have the ability to nodulate the roots of current north american cultivars of peas as well as a "primitive" cultivar, afghanistan, was examined. these isolates originated in diverse geographical regions of the world, which indicates that this phenotype is not restricted to isolates from any one region. when subclones of the nodulation region from one plasmid were used to examine ecori-fragment-length polymorphisms in th ...	1990	16348240
increased accumulation of trehalose in rhizobia cultured under 1% oxygen.	the growth of rhizobia under 1% o(2) induced the accumulation of alpha,alpha-trehalose, and the effect of low o(2) was independent of medium composition and rhizobium species. trehalose concentration in cells declined rapidly when microaerobic cultures were supplied with 21% o(2). trehalose formation in nodules may be induced by the microaerobic environment.	1990	16348326
bacteriochlorophyll and photosynthetic reaction centers in rhizobium strain btai 1.	rhizobium strain btai 1, which nodulates both stems and roots of aeschynomene indica l., formed bacteriochlorophyll and photosynthetic reaction centers resembling those of purple photosynthetic bacteria when grown aerobically ex planta under a light-dark cycle. bacteriochlorophyll formation was not observed under continuous dark or light growth conditions. the amount of pigment formed was similar to that previously found in aerobic photosynthetic bacteria. stem nodules appear to fix nitrogen pho ...	1990	16348349
osmoregulation in rhizobium meliloti: production of glutamic acid in response to osmotic stress.	rhizobium meliloti, like many other bacteria, accumulates high levels of glutamic acid when osmotically stressed. the effect was found to be proportional to the osmolarity of the growth medium. nacl, kci, sucrose, and polyethylene glycol elicited this response. the intracellular levels of glutamate and k began to increase immediately when cells were shifted to high-osmolarity medium. antibiotics that inhibit protein synthesis did not affect this increase in glutamate production. cells growing in ...	1990	16348124
carbon metabolism enzymes of rhizobium meliloti cultures and bacteroids and their distribution within alfalfa nodules.	several carbon metabolism enzymes were measured in cultured cells and bacteroids of rhizobium meliloti 102f51 and in alfalfa root nodule cytosol. the enzyme activity levels of the pentose phosphate pathway were much higher than those of the embden-meyerhof-parnas or entner-doudoroff pathways in extracts of cultured cells. the pattern of enzyme activities in the bacteroids was different from that of cultured cells.	1990	16348268
single-strain versus multistrain inoculation: effect of soil mineral n availability on rhizobial strain effectiveness and competition for nodulation on chick-pea, soybean, and dry bean.	the nitrogen-fixing effectiveness of multistrain inoculants was found to be determined by both the effectiveness of the component strains and the percentage of the nodules occupied by them. multistrain formulations were always either as good as the most effective single-strain inoculant or intermediate between the most and the least effective. the percentage of nodules occupied and the amount of nitrogen fixed by the component strains of a multistrain inoculant showed highly significant linear c ...	1990	16348337
conjugal transfer of megaplasmid 2 between rhizobium meliloti strains in alfalfa nodules.	a dna fragment containing the rp4 mob function, as well as the gentamicin and spectinomycin resistance genes, was inserted by gene replacement onto the megaplasmid 2 (pm2) of rhizobium meliloti 0540 (inf eps), resulting in pg101 (inf eps). the self-transfer of pm2 and the mobilization of pm2 by plasmid rp4-4 were investigated during conjugation between pg101 and r. meliloti 2526 (nod). in filter conjugations, pm2 was readily mobilized by rp4-4. in addition to this, the self-transfer of one megap ...	1990	16348248
increased bean (phaseolus vulgaris l.) nodulation competitiveness of genetically modified rhizobium strains.	rhizobium leguminosarum bv. phaseoli strain collections harbor heterogeneous groups of bacteria in which two main types of strains may be distinguished, differing both in the symbiotic plasmid and in the chromosome. we have analyzed under laboratory conditions the competitive abilities of the different types of rhizobium strains capable of nodulating phaseolus vulgaris l. bean. r. leguminosarum bv. phaseoli type i strains (characterized by nif gene reiterations and a narrow host range) are more ...	1990	16348252
growth, respiration, and polypeptide patterns of bradyrhizobium sp. (arachis) strain 3g4b20 from succinate- or oxygen-limited continuous cultures.	succinate- or oxygen-limited continuous cultures were used to study the influences of different concentrations of dissolved oxygen and ammonia on the growth, respiration, and polypeptide patterns of bradyrhizobium sp. (arachis) strain 3g4b20. during succinate-limited growth, molar growth yields on succinate (y(succ)) ranged from 38.9 to 44.4 g (dry weight) of cells mol of succinate and were not greatly influenced by changes in dilution rates or changes in the oxygen concentrations that we tested ...	1990	16348154
isolation of rhizobium leguminosarum (biovar trifolii) strains from ethiopian soils and symbiotic effectiveness on african annual clover species.	strains of rhizobium leguminosarum (biovar trifolii) isolated from two ethiopian soils or obtained from a commercial source were evaluated for symbiotic effectiveness on five african annual clover species. numerous rhizobium trifolii strains that exhibited varying levels of symbiotic effectiveness were isolated from both soils (a nitosol and a vertisol), and it was possible to identify strains that were highly effective for each clover species. the soil isolates were, as a group, superior to the ...	1990	16348157
identification and plant interaction of a phyllobacterium sp., a predominant rhizobacterium of young sugar beet plants.	the second most abundant bacterium on the root surface of young sugar beet plants was identified as a phyllobacterium sp. (rhizobiaceae) based on a comparison of the results of 39 conventional identification tests, 167 api tests, 30 antibiotic susceptibility tests, and sodium dodecyl sulfate-polyacrylamide gel electrophoretic fingerprints of total cellular proteins with type strains of phyllobacterium myrsinacearum and phyllobacterium rubiacearum. it was found on 198 of 1,100 investigated plants ...	1990	16348158
construction of a symbiotically effective strain of rhizobium leguminosarum bv. trifolii with increased nodulation competitiveness.	genes involved in nodulation competitiveness (tfx) were inserted by marker exchange into the genome of the effective strain rhizobium leguminosarum bv. trifolii ta1. isogenic strains of ta1 were constructed which differed only in their ability to produce trifolitoxin, an antirhizobial peptide. trifolitoxin production by the ineffective strain r. leguminosarum bv. trifolii t24 limited nodulation of clover roots by trifolitoxin-sensitive strains of r. leguminosarum bv. trifolii. the trifolitoxin-p ...	1990	16348109
stability of markers used for identification of two rhizobium galegae inoculant strains after five years in the field.	the stability of identification markers was examined for two rhizobium galegae inoculant strains after 5 years in the field. the two strains are genetically closely related, but differ in their lipopolysaccharides. strain hambi 540 has lipopolysaccharide of the rough type, whereas that of strain hambi 1461 is of the smooth type. the properties that were examined for 10 field isolates of each inoculant type were symbiotic phenotype, phage type, intrinsic antibiotic resistance, maximum growth temp ...	1990	16348119
dna, a possible site of action of aluminum in rhizobium spp.	al was found to penetrate the cell envelopes of both sensitive and tolerant rhizobium strains and bind to dna in vivo. despite causing a reduction in viability, al stimulated dna synthesis in the sensitive strain, which suggested that an excision repair mechanism was operating. the al-stimulated dna synthesis was reduced by the simultaneous addition of chloramphenicol. in contrast to the sensitive strain, dna synthesis was unaffected by al binding to dna in the tolerant strain. it is proposed th ...	1990	16348368
binding of isolated plant lectin by rhizobia during episodes of reduced gravity obtained by parabolic flight.	development of a legume root nodule is a complex process culminating in a plant/bacterial symbiosis possessing the capacity for biological dinitrogen fixation. formation of root nodules is initiated by the binding and stabilization of rhizobia to plant root hairs, mediated in part by a receptor/ligand recognition system composed of lectins on the plant root surface and lectin-binding sites on the rhizobial cell surface. the dinitrogen fixation activity of these root nodules may be an important ...	1990	11537996
nodulin gene expression and enod2 localization in effective, nitrogen-fixing and ineffective, bacteria-free nodules of alfalfa.	alfalfa plants form bacteria-free nodules in response to a number of agents, including rhizobium meliloti exo mutants, agrobacterium tumefaciens transconjugants carrying cloned r. meliloti nodulation genes, and compounds that function as auxin transport inhibitors, n-( 1-naphthyl)phthalamic acid or 2,3,5-triiodobenzoic acid. these bacteria-free nodules contain transcripts for the nodulins nms30 and msenod2; transcripts for late nodulins like leghemoglobin are not detected. in situ hybridization ...	1990	12354949
rhizobium meliloti genes encoding catabolism of trigonelline are induced under symbiotic conditions.	rhizobium meliloti trc genes controlling the catabolism of trigonelline, a plant secondary metabolite often abundant in legumes, are closely linked to nif-nod genes on the symbiotic megaplasmid psym [boivin, c., malpica, c., rosenberg, c., denarie, j., goldman, a., fleury, v., maille, m., message, b., and tepfer, d. (1989). in molecular signals in the microbe-plant symbiotic and pathogenic systems. (berlin: springer-verlag), pp. 401-407]. to investigate the role of trigonelline catabolism in the ...	1990	12354952
cooperative action of rhizobium meliloti nodulation and infection mutants during the process of forming mixed infected alfalfa nodules.	alfalfa plants co-inoculated with rhizobium meliloti nodulation (nod-) and infection mutants deficient in exopolysaccharide production (inf-eps-) formed mixed infected nodules that were capable of fixing atmospheric nitrogen. the formation of infected nodules was dependent on close contact between the inoculation partners. when the partners were separated by a filter, empty fix- nodules were formed, suggesting that infection thread formation in alfalfa is dependent on signals from the nodulation ...	1990	12354955
modulation of host gene expression during initiation and early growth of nodules in cowpea, vigna unguiculata (l.) walp.	inoculation of 2-day-old cowpea (vigna unguiculata [l.] walp.) seedlings with rhizobium fredii usda257 results in proficient nodulation of the tap root. the most abundant nodulation occurs in a region roughly corresponding to the position of the root tip at the time of inoculation. we have examined plant gene expression in this region, after inoculation with either usda257 or a nonnodulating mutant, 257b3. after isolation of mrna and in vitro translation, the protein products were separated by t ...	1990	16667410
chrysoeriol and luteolin released from alfalfa seeds induce nod genes in rhizobium meliloti.	flavonoid signals from alfalfa (medicago sativa l.) seed and root exudates induce transcription of nodulation (nod) genes in rhizobium meliloti. the flavone luteolin previously was isolated from alfalfa seeds by other workers and identified as the first nod gene inducer for r. meliloti. our recent study of ;moapa 69' alfalfa root exudates found no luteolin but did identify three other nod gene inducers: 4,4'-dihydroxy-2'-methoxychalcone, 4',7-dihydroxyflavone, and 4',7-dihydroxyflavanone. the go ...	1990	16667231
development and partial characterization of nearly isogenic pea lines (pisum sativum l.) that alter uptake hydrogenase activity in symbiotic rhizobium.	some rhizobium bacteria have h(2)-uptake (hup) systems that oxidize h(2) evolved from nitrogenase in leguminous root nodules. pea (pisum sativum l.) cultivars ;ji1205' and ;alaska' produce high hup (hup(++)) and moderate hup (hup(+)) phenotypes, respectively, in rhizobium leguminosarum 128c53. the physiological significance and biochemical basis of this host plant genetic effect are unknown. the purpose of this investigation was to advance basic hup studies by developing nearly isogenic lines of ...	1990	16667415
concurrent synthesis and release of nod-gene-inducing flavonoids from alfalfa roots.	flavonoid signals from alfalfa (medicago sativa l.) induce transcription of nodulation (nod) genes in rhizobium meliloti. alfalfa roots release three major nod-gene inducers: 4',7-dihydroxyflavanone, 4',7-dihydroxyflavone, and 4,4'-dihydroxy-2'-methoxychalcone. the objective of the present study was to define temporal relationships between synthesis and exudation for those flavonoids. requirements for concurrent flavonoid biosynthesis were assessed by treating roots of intact alfalfa seedlings w ...	1990	16667655
products of dark co(2) fixation in pea root nodules support bacteroid metabolism.	products of the nodule cytosol in vivo dark [(14)c]co(2) fixation were detected in the plant cytosol as well as in the bacteroids of pea (pisum sativum l. cv "bodil") nodules. the distribution of the metabolites of the dark co(2) fixation products was compared in effective (fix(+)) nodules infected by a wild-type rhizobium leguminosarum (mnf 300), and ineffective (fix(-)) nodules of the r. leguminosarum mutant mnf 3080. the latter has a defect in the dicarboxylic acid transport system of the bac ...	1990	16667422
nodulation of soybean by a transposon-mutant of rhizobium fredii usda257 is subject to competitive nodulation blocking by other rhizobia.	rhizobium fredii usda257 fails to nodulate the improved soybean [glycine max (l.)merr.] cultivar mccall in plastic growth pouches. mutant 257dh4, which was derived from usda257 by transposon mutagenesis, forms nitrogen fixing nodules under these conditions. if usda257 is present in inocula containing the mutant, most infections are arrested prior to organization of the nodule meristem, and nodule number is reduced by 95%. the improved cultivars essex, harosoy, hodgson 78, and viçoja, as well as ...	1990	16667829
production and characterization of monoclonal antibodies against aspartate aminotransferase-p(2) from lupin root nodules.	twenty-one monoclonal antibodies were raised against the aspartate aminotransferase-p(2) isoenzyme from root nodules of lupinus angustifolius [l.] cv uniharvest. induction of this isoenzyme is positively correlated with the onset of n(2) fixation in effective root nodules and is associated with the assimilation of ammonia by the plant in the rhizobium-legume symbiosis. the monoclonal antibodies produced were all of the igg class, recognized five different epitopes on the protein, and represented ...	1990	16667841
sym 13-a gene conditioning ineffective nodulation in pisum sativum.	treatment of pisum sativum (l.) cv. ;sparkle' with ethyl methanesulfonic acid (ems) produced a stable mutant, e135f, which forms small, white, ineffective nodules. these nodules exhibit histological zonation typical of an indeterminant nodule, e.g. meristematic, early symbiotic, late symbiotic, and senescent zones. compared with the nitrogen fixing nodules of the parent, the zones are smaller and the nodules senesce prematurely. bacteroids in e135f are less elongated and less differentiated than ...	1990	16667870
cultivar-specific interactions of soybean with rhizobium fredii are regulated by the genotype of the root.	rhizobium fredii usda257 forms nitrogen-fixing nodules on soybean cultivar peking, but not on cultivar mccall. this pattern of nodulation persists when mccall and peking seedlings are cultivated together in plastic growth pouches. reciprocal grafting experiments confirm that the root genotype, and not that of the shoot, regulates such cultivar specificity. when peking roots are grafted onto mccall seedlings, the nodulation responses of roots similarly remain unaffected. transposon-mutant 257dh4, ...	1990	16667934
metabolism of tryptophan and tryptophan analogs by rhizobium meliloti.	the alfalfa symbiont rhizobium meliloti rm1021 produces indole-3-acetic acid in a regulated manner when supplied with exogenous tryptophan. mutants with altered response to tryptophan analogs still produce indole-3-acetic acid, but are fix(-) because bacteria do not fully differentiate into the nitrogen-fixing bacteriod form. these mutations are in apparently essential genes tightly linked to a dominant streptomycin resistance locus.	1990	16667364
rhizobium meliloti exopolysaccharide mutants elicit feedback regulation of nodule formation in alfalfa.	nodule formation by wild-type rhizobium meliloti is strongly suppressed in younger parts of alfalfa (medicago sativum l.) root systems as a feedback response to development of the first nodules (g caetano-anollés, wd bauer [1988] planta 175: 546-557). mutants of r. meliloti deficient in exopolysaccharide synthesis can induce the formation of organized nodular structures (pseudonodules) on alfalfa roots but are defective in their ability to invade and multiply within host tissues. the formation o ...	1990	16667284
developmental biology of a plant-prokaryote symbiosis: the legume root nodule.	the development of nitrogen fixing root nodules on the roots of leguminous plants is induced by soil bacteria (for example, from the genus rhizobium). the formation of this plant organ involves specific activation of genes in both plant and bacterium. analysis of these genes gives insight into the way in which plant and bacterium succeed in coordinating plant development.	1990	17746918