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t-dna as a gene tag.the characteristics of agrobacterium-mediated plant transformation are such that the t-dna can be used as an insertional mutagen and, by extension, a gene tag. an increasing number of mutants have been obtained as a result of t-dna insertion and the versatility of this experimental system can be exploited further to tag sequences of dna which control gene expression. while the isolation of specific mutations by t-dna tagging in the past has been fortuitous, t-dna-based vectors have the potential ...199121736647
reclassification of rhizobium tropici type a strains as rhizobium leucaenae sp. nov.rhizobium tropici is a well-studied legume symbiont characterized by high genetic stability of the symbiotic plasmid and tolerance to tropical environmental stresses such as high temperature and low soil ph. however, high phenetic and genetic variabilities among r. tropici strains have been largely reported, with two subgroups, designated type a and b, already defined within the species. a polyphasic study comprising multilocus sequence analysis, phenotypic and genotypic characterizations, inclu ...201121742822
modulation of rosr expression and exopolysaccharide production in rhizobium leguminosarum bv. trifolii by phosphate and clover root exudates.the acidic exopolysaccharide (eps) secreted in large amounts by the symbiotic nitrogen-fixing bacterium rhizobium leguminosarum bv. trifolii is required for the establishment of an effective symbiosis with the host plant trifolium spp. eps biosynthesis in rhizobia is a very complex process regulated at both transcriptional and post-transcriptional levels and influenced by various nutritional and environmental conditions. the r. leguminosarum bv. trifolii rosr gene encodes a transcriptional regul ...201121747729
agrobacterium-mediated transformation of leaf base derived callus tissues of popular indica rice (oryza sativa l. sub sp. indica cv. adt 43).a simple and efficient protocol for the agrobacterium-mediated transformation of an agronomically useful abiotic sensitive popular indica rice cv. adt 43 has been developed. initiation of calli were best achieved from the leaf bases of 4 days old rice seedlings on ls medium supplemented with 2.5mg/l 2,4-d and 1.0mg/l thiamine-hcl. rice calli immersed in agrobacterium suspension (strain eha 105, od(600)=0.8) were co-cultured on ls30-aspc medium for 2 days at 25±2°c in the dark. based on gus expre ...201121763536
an acpxl mutant in rhizobium leguminosarum bv. phaseolus lacks 27-hydroxyoctacosanoic acid in its lipid a and is developmentally delayed during symbiotic infection of the determinate nodulating host plant phaseolus vulgaris.rhizobium leguminosarum is a gram negative bacterium that forms nitrogen fixing symbioses with compatible leguminous plants via intracellular invasion and establishes a persistent infection within host membrane derived subcellular compartments. notably, an unusual very long chain fatty acid (vlcfa) is found in the lipid a of r. leguminosarum as well as in the lipid a of the medically relevant pathogens brucella abortus, brucella melitensis, bartonella henselae, and legionellae pneumophila which ...201121764936
sinorhizobium fredii usda257 and s. fredii usda191, cultivar-specific and non-specific symbionts of soybean, produce distinct cell surface appendages.sinorhizobium fredii usda257 and s. fredii usda191 are fast-growing rhizobia that form nitrogen-fixing nodules on soybean roots. in contrast to usda191, usda257 exhibits cultivar specificity and can form nodules only on primitive soybean cultivars. in response to flavonoids released from soybean roots these two rhizobia secrete nodulation outer proteins (nop) to the extracellular milieu through a type iii secretion system. in spite of the fact that nop proteins are known to regulate legume nodul ...201121764962
inducing salt tolerance in mung bean through coinoculation with rhizobia and plant-growth-promoting rhizobacteria containing 1-aminocyclopropane-1-carboxylate deaminase.twenty-five strains of plant-growth-promoting rhizobacteria (pgpr) containing 1-aminocyclopropane-1-carboxylate (acc) deaminase and 10 strains of rhizobia were isolated from rhizosphere soil samples and nodules of mung bean. they were screened in separate trials under salt-stressed axenic conditions. the three most effective strains of pgpr (mk1, pseudomonas syringae ; mk20, pseudomonas fluorescens ; and mk25, pseudomonas fluorescens biotype g) and rhizobium phaseoli strains m1, m6, and m9 were ...201121770816
transgenic sugar beet tolerant to imidazolinone obtained by agrobacterium-mediated transformation.sugar beet is highly sensitive to imidazolinone herbicides thus rotational restrictions exist. in order to develop imidazolinone tolerant sugar beets als gene from arabidopsis thaliana encoding acetolactate synthase with s653n mutation was used for genetic transformation. transgenic sugar beet plants were obtained by agrobacterium-mediated transformation of aseptic seedlings using vacuum-infiltration. the efficiency of genetic transformation was 5.8%. rt-pcr analysis of obtained plants revealed ...201121774399
expression and localization of a rhizobium-derived cambialistic superoxide dismutase in pea (pisum sativum) nodules subjected to oxidative stress.two phylogenetically unrelated superoxide dismutase (sod) families i.e. cuznsods and fe/mn/cambialistic sods, eliminate superoxide radicals in different locations within the plant cell. cuznsods are located within the cytosol and plastids, whilst the second family of sods, which are considered to be of bacterial origin, are usually located within organelles, such as mitochondria. we have used the ros-producer methylviologen (mv) to study sod isozymes in the indeterminate nodules on pea (pisum sa ...201121774575
functional analysis of the type 3 effector nopl from rhizobium sp. ngr234: symbiotic effects, phosphorylation and interference with mapk signaling.pathogenic bacteria use type 3 secretion systems to deliver virulence factors (type 3 effector proteins) directly into eukaryotic host cells. similarly, type 3 effectors of certain nitrogen-fixing rhizobial strains affect nodule formation in the symbiosis with host legumes. nodulation outer protein l (nopl) of rhizobium sp. strain ngr234 is a rhizobium-specific type 3 effector. nodulation tests and microscopic analysis showed that distinct necrotic areas were rapidly formed in ineffective nodule ...201121775427
transgenic grass skirts regulators. 201121776051
[bioengineering of symbiotic systems: creation of new associative symbiosis with the use of lectins on the example of tobacco and colza]."barbate roots" in tobacco and colza transgenic on lectin gene were obtained with the use of a wild strain of agrobacterium rhizogenes 15834 transformed with pcambia1305.1 plasmid containing the full-size lectin gene (psl) from the pisum sativum. influence of expression oflectin gene on colonization oftransgenic roots with symbiont of pea (rhizobium leguminosarum) was investigated. the number of adhered bacteria onto the roots transformed with lectin gene was 14-fold and 37-fold higher in compar ...201121790035
a rapid and simple pcr method for identifying isolates of the genus azospirillum within populations of rhizosphere bacteria.aims: to develop a rapid and simple genus-specific polymerase chain reaction (pcr) method for detecting and identifying isolates of the genus azospirillum which is well-recognized as plant growth-promoting rhizobacterium. methods and results: nine pairs of pcr primers were designed based on the azospirillum 16s rrna, ipdc, nifa, and nifh genes to assess their genus specificity by testing against 12 azospirillum (from seven species) and 15 non-azospirillum reference strains, as compared with th ...201121790914
systems biology of bacterial nitrogen fixation: high-throughput technology and its integrative description with constraint-based modeling.abstract: background: bacterial nitrogen fixation is the biological process by which atmospheric nitrogen is uptaken by bacteroids located in plant root nodules and converted into ammonium through the enzymatic activity of nitrogenase. in practice, this biological process serves as a natural form of fertilization and its optimization has significant implications in sustainable agricultural programs. currently, the advent of high-throughput technology supplies with valuable data that contribute t ...201121801415
molecular adaptation in flowering and symbiotic recognition pathways: insights from patterns of polymorphism in the legume medicago truncatula.abstract: background: we studied patterns of molecular adaptation in the wild mediterranean legume medicago truncatula. we focused on two phenotypic traits that are not functionally linked: flowering time and perception of symbiotic microbes. phenology is an important fitness component, especially for annual plants, and many instances of molecular adaptation have been reported for genes involved in flowering pathways. while perception of symbiotic microbes is also integral to adaptation in many ...201121806823
a comparative transcriptome analysis of rhizobium etli bacteroids: specific gene-expression during symbiotic non-growth.rhizobium etli occurs either in a nitrogen-fixing symbiosis with its host plant, phaseolus vulgaris, or free-living in the soil. during both conditions, the bacterium has been suggested to reside primarily in a non-growing state. using genome-wide transcriptome profiles, we here examine the molecular basis of the physiological adaptations of rhizobia to non-growth inside and outside of the host. compared to exponentially growing cells, we found an extensive overlap of downregulated growth-associ ...201121809980
pseudonodule formation by wild type and symbiotic mutant medicago truncatula in response to auxin transport inhibitors.rhizobium and allied bacteria form symbiotic nitrogen fixing nodules on legume roots. plant hormones play key roles in nodule formation. we treated medicago truncatula roots with auxin transport inhibitors (atis) n-(1-naphthyl)phthalamic acid (npa) and 2,3,5-triiodobenzoic acid (tiba), to induce the formation of pseudonodules. m. truncatula mutants defective for rhizobial nod factor signal transduction still formed pseudonodules in response to atis. however, a m. truncatula ethylene-insensitive ...201121809981
rhizobial nod factors are required for cortical cell division in the nodule morphogenetic programme of the aeschynomeneae legume arachis.nod factors are among the best-studied molecules implicated in the signal exchange that leads to legume-rhizobia symbiosis. the role of these molecules in symbiosis development has been primarily studied in legumes invaded through infection threads. in these plants, nod factors generate several responses required for nodulation, including the induction of cortical cell division to form the nodule primordium. arachis hypogaea l. (peanut) exhibits a specific mode of rhizobial infection and nodule ...201121815984
matrix-assisted laser desorption ionization (maldi)-time of flight mass spectrometry- and maldi biotyper-based identification of cultured biphenyl-metabolizing bacteria from contaminated horseradish rhizosphere soil.bacteria that are able to utilize biphenyl as a sole source of carbon were extracted and isolated from polychlorinated biphenyl (pcb)-contaminated soil vegetated by horseradish. isolates were identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (maldi-tof ms). the usage of maldi biotyper for the classification of isolates was evaluated and compared to 16s rrna gene sequence analysis. a wide spectrum of bacteria was isolated, with arthrobacter, serratia, r ...201121821747
synthesis of microbial signaling molecules and their stereochemistry-activity relationships.microbial signaling molecules such as autoinducers and microbial hormones play important roles in intercellular communication in microorganisms. information transfer between the individual cells of a microorganism is one of the most important biological events among them. researchers often suffer from extremely low levels of microbial signaling molecule contents, which prevent them from understanding chemistry and biology of intercellular communication in microorganisms. chemical synthesis is a ...201121821958
phylogenetic analysis reveals gene conversions in multigene families of rhizobia.gene families are an important and intrinsic trait of rhizobial species. these gene copies can participate in non-reciprocal recombination events, also called gene conversions. gene conversion has diverse roles, but it is usually implicated in the evolution of multigene families. here, we searched for gene conversions in multigene families of six representative rhizobial genomes. we identified 11 gene families with different numbers of copies, genome location and function in cfn42 and ciat652 st ...201121823087
high-level recombinant protein expression in transgenic plants by using a double-inducible viral vector.we describe here a unique ethanol-inducible process for expression of recombinant proteins in transgenic plants. the process is based on inducible release of viral rna replicons from stably integrated dna proreplicons. a simple treatment with ethanol releases the replicon leading to rna amplification and high-level protein production. to achieve tight control of replicon activation and spread in the uninduced state, the viral vector has been deconstructed, and its two components, the replicon an ...201121825158
legume-nodulating betaproteobacteria: diversity, host range and future prospects.rhizobia form specialized nodules on the roots of legumes (fabaceae) and fix nitrogen in exchange for carbon from the host plant. although the majority of legumes form symbioses with rhizobium and its relatives in the alphaproteobacteria, some legumes, such as those in the large genus mimosa, are nodulated predominantly by betaproteobacteria in the genera burkholderia and cupriavidus. the principal centers of diversity of these bacteria are in central brazil and south africa. molecular phylogene ...201121830951
plant growth-promotion (pgp) activities and molecular characterization of rhizobacterial strains isolated from soybean (glycine max l. merril) plants against charcoal rot pathogen, macrophomina phaseolina.charcoal rot disease, caused by the fungus macrophomina phaseolina, leads to significant yield losses of soybean crops. one strategy to control charcoal rot is the use of antagonistic, root-colonizing bacteria. rhizobacteria a(5)f and fpt(7)21 and pseudomonas sp. strain grp(3) were characterized for their plant growth-promotion activities against the pathogen. rhizobacterium fpt(7)21 exhibited higher antagonistic activity against the pathogen on dual plate assay compared to strain a(5)f and grp( ...201121833548
synthesis and evaluation of an n-acetylglucosamine biosynthesis inhibitor.the structural rationale, synthesis and evaluation of an inhibitor designed to block glucosamine synthesis by competitively inhibiting the action of glutamine: fructose-6-phosphate amidotransferase and subsequently reducing the transformation of any glucosamine-6-phosphate formed to udp-n-acetylglucosamine are described. the inhibitor 2-acetamido-2,6-dideoxy-6-sulfo-d-glucose (d-glucosamine-6-sulfonate) is an analog of glucosamine-6-phosphate in which the phosphate group in the latter is replace ...201121843880
early signaling in actinorhizal symbioses.nitrogen-fixing root nodulation, confined to four plant orders, encompasses more than 14,000 leguminosae species, and approximately 200 actinorhizal species forming symbioses with rhizobia (rhizobium, bradyrhizobium, etc) and frankia bacterial species, respectively. while several genetic components of the host-symbiont interaction have been identified in legumes, little is known about the genetic bases of actinorhizal symbiosis. however, we recently demonstrated the existence of common symbiotic ...201121847030
atomic force microscopy of a ctpa mutant in rhizobium leguminosarum reveals surface defects linking ctpa function to biofilm formation.atomic force microscopy was used to investigate the surface ultrastructure, adhesive properties and biofilm formation of rhizobium leguminosarum and a ctpa mutant strain. the surface ultrastructure of wild-type r. leguminosarum consists of tightly packed surface subunits, whereas the ctpa mutant has much larger subunits with loose lateral packing. the ctpa mutant strain is not capable of developing fully mature biofilms, consistent with its altered surface ultrastructure, greater roughness and s ...201121852352
the superoxide dismutase soda is targeted to the periplasm in a seca-dependent manner by a novel mechanism.the manganese/iron-type superoxide dismutase (soda) of rhizobium leguminosarum bv. viciae 3841 is exported to the periplasm of r. l. bv. viciae and escherichia coli. however, it does not possess a hydrophobic cleaved n-terminal signal peptide typically present in soluble proteins exported by the sec-dependent (sec) pathway or the twin-arginine translocation (tat) pathway. a tatc mutant of r. l. bv. viciae exported soda to the periplasm, ruling out export of soda as a complex with a tat substrate ...201121854464
variations in exopolysaccharide production by rhizobium tropici.rhizobium tropici, a legume-symbiont soil bacterium, is known for its copious production of exopolysaccharide (eps). many aspects of this organism's growth and eps production, however, remain uncharacterized, including the influence of environment and culturing conditions upon eps. here, we demonstrate that r. tropici eps chemical composition and yield differ when grown with different substrates in a defined minimal medium in batch culture. exopolysaccharide was quantified from r. tropici grown ...201121858649
environmental microbiota represents a natural reservoir for dissemination of clinically relevant metallo-beta-lactamases.a total of 10 metallo-β-lactamase-producing isolates of six different species, including brevundimonas diminuta (n = 3), rhizobium radiobacter (n = 2), pseudomonas monteilii (n = 1), pseudomonas aeruginosa (n = 2), ochrobactrum anthropi (n = 1), and enterobacter ludwigii (n = 1), were detected in the sewage water of a hospital. the presence of bla(vim-13) associated with a tn1721-class 1 integron structure was detected in all but one of the isolates (e. ludwigii, which produced vim-2), and in tw ...201121859934
how good is the turbid medium-based approach for accounting for light partitioning in contrasted grass--legume intercropping systems?most studies dealing with light partitioning in intercropping systems have used statistical models based on the turbid medium approach, thus assuming homogeneous canopies. however, these models could not be directly validated although spatial heterogeneities could arise in such canopies. the aim of the present study was to assess the ability of the turbid medium approach to accurately estimate light partitioning within grass-legume mixed canopies.201121865218
Agrobacterium-mediated virus-induced gene silencing assay in cotton.Cotton (Gossypium hirsutum) is one of the most important crops worldwide. Considerable efforts have been made on molecular breeding of new varieties. The large-scale gene functional analysis in cotton has been lagged behind most of the modern plant species, likely due to its large size of genome, gene duplication and polyploidy, long growth cycle and recalcitrance to genetic transformation(1). To facilitate high throughput functional genetic/genomic study in cotton, we attempt to develop rapid a ...201121876527
Symbiotic effectiveness of rhizobial mutualists varies in interactions with native Australian legume genera.Interactions between plants and beneficial soil organisms (e.g. rhizobial bacteria, mycorrhizal fungi) are models for investigating the ecological impacts of such associations in plant communities, and the evolution and maintenance of variation in mutualisms (e.g. host specificity and the level of benefits provided). With relatively few exceptions, variation in symbiotic effectiveness across wild host species is largely unexplored.201121887270
Role of bioinoculants and organic fertilizers in fodder production and quality of leguminous tree species.The comparative effect of dual inoculation of native N fixer (Rhizobium) and AM fungi consortia with different organic fertilizers (vermicompost and farm yard manure) on fodder production and quality of two leguminous tree species (Leucaena leucocephala (Lam) de. Wit. and Sesbania sesban (L.) Merr.) in silvopastoral system and their impact on the fodder production of un-inoculated Panicum maximum Jacq. under cut and carry system. After three years of plantation maximum tree survival was in L. le ...201121888233
nitric oxide in legume-rhizobium symbiosis.nitric oxide (no) is a gaseous signaling molecule with a broad spectrum of regulatory functions in plant growth and development. no has been found to be involved in various pathogenic or symbiotic plant-microbe interactions. during the last decade, increasing evidence of the occurrence of no during legume-rhizobium symbioses has been reported, from early steps of plant-bacteria interaction, to the nitrogen-fixing step in mature nodules. this review focuses on recent advances on no production and ...201121893254
effect of applying an arsenic-resistant and plant growth-promoting rhizobacterium to enhance soil arsenic phytoremediation by populus deltoides lh05-17.bioremediation of highly arsenic (as)-contaminated soil is difficult because as is very toxic for plants and micro-organisms. the aim of this study was to investigate soil arsenic removal effects using poplar in combination with the inoculation of a plant growth-promoting rhizobacterium (pgpr).201121895895
A New Family of Biuret Hydrolases Involved in S-Triazine Ring Metabolism.Biuret is an intermediate in the bacterial metabolism of s-triazine ring compounds and is occasionally used as a ruminant feed supplement. We used bioinformatics to identify a biuret hydrolase, an enzyme that has previously resisted efforts to stabilize, purify and characterize. This newly discovered enzyme is a member of the cysteine hydrolase superfamily, a family of enzymes previously not found to be involved in s-triazine metabolism. The gene from Rhizobium leguminosarum bv. viciae strain 38 ...201121897878
systemically induced resistance and microbial competitive exclusion: implications on biological control.the root-knot nematode, meloidogyne incognita, is among the most damaging agricultural pests, particularly to tomato. the mutualistic endophytes fusarium oxysporum strain fo162 (fo162) and rhizobium etli strain g12 (g12) have been shown to systemically induce resistance towards m. incognita. by using triple-split-root tomato plants, spatially-separated but simultaneous inoculation of both endophytes did not lead to additive reductions in m. incognita infection. more importantly, spatially-separa ...201121899390
Effects of salt stress on some nitrogen fixation parameters in faba bean.The adverse effects of sea water salinity on number of nodules, nitrogen content, nitroginase activity, Chlorophyll a and b content, proline accumulation and protein pattern of faba bean plants (Vicia faba commercial cultivar Nubaria 1) were investigated. Faba bean plants were irrigated with sea water at 20, 25, 30, 40 and 50% concentrations and inoculated with rhizobial isolate ARC307 or with gamma rays treated isolates namely; ARC1, ARC2, ARC3, ARC4, ARC5, ARC6 and ARC7. Nodules number, nitrog ...201121902062
evolutionary origin of rhizobium nod factor signaling.for over two decades now, it is known that the nodule symbiosis between legume plants and nitrogen fixing rhizobium bacteria is set in motion by the bacterial signal molecule named nodulation (nod) factor. ( 1) upon nod factor perception a signaling cascade is activated that is also essential for endomycorrhizal symbiosis (fig. 1). this suggests that rhizobium co-opted the evolutionary far more ancient mycorrhizal signaling pathway in order to establish an endosymbiotic interaction with legumes ...201121904113
effects of glyphosate-resistant crop cultivation on soil and water quality.transgenic glyphosate-resistant crops (grcs) have been commercialized and grown extensively in the western hemisphere and, to a lesser extent, elsewhere. grcs have generally become dominant in those countries where they have been approved for growing. potential effects of glyphosate on soil and water are minimal, compared the effects of the herbicides that are replaced when grcs are adopted. perhaps the most important indirect effect is that grcs crops promote the adoption of reduced- or no-till ...201021912208
glutamine synthetase is a molecular target of nitric oxide in root nodules of medicago truncatula and is regulated by tyrosine nitration.nitric oxide (no) is emerging as an important regulatory player in the rhizobium-legume symbiosis, but its biological role in nodule functioning is still far from being understood. to unravel the signal transduction cascade and ultimately no function, it is necessary to identify its molecular targets. this study provides evidence that glutamine synthetase (gs), a key enzyme for root nodule metabolism, is a molecular target of no in root nodules of medicago truncatula, being regulated by tyrosine ...201121914816
novel root nodule bacteria belonging to the genus caulobacter.aim of this study is to determine the genetic variation of rhizobia associated with horse gram [macrotyloma uniflorum (lam.) verdc.] plants grown in different regions of andhra pradesh, india.201121919926
strigolactones promote nodulation in pea.strigolactones are recently defined plant hormones with roles in mycorrhizal symbiosis and shoot and root architecture. their potential role in controlling nodulation, the related symbiosis between legumes and rhizobium bacteria, was explored using the strigolactone-deficient rms1 mutant in pea (pisum sativum l.). this work indicates that endogenous strigolactones are positive regulators of nodulation in pea, required for optimal nodule number but not for nodule formation per se. rms1 mutant roo ...201121927948
Lotus japonicus nodulation is photomorphogenetically controlled by sensing the red/far red (R/FR) ratio through jasmonic acid (JA) signaling.Light is critical for supplying carbon to the energetically expensive, nitrogen-fixing symbiosis between legumes and rhizobia. Here, we show that phytochrome B (phyB) is part of the monitoring system to detect suboptimal light conditions, which normally suppress Lotus japonicus nodule development after Mesorhizobium loti inoculation. We found that the number of nodules produced by L. japonicus phyB mutants is significantly reduced compared with the number produced of WT Miyakojima MG20. To explo ...201121930895
Interplay of flg22-induced defence responses and nodulation in Lotus japonicus.In this study the interplay between the symbiotic and defence signalling pathways in Lotus japonicus was investigated by comparing the responses to Mesorhizobium loti, the symbiotic partner of L. japonicus, and the elicitor flg22, a conserved peptide motif present in flagellar protein of a wide range of bacteria. It was found that defence and symbiotic pathways overlap in the interaction between L. japonicus and M. loti since similar responses were induced by the mutualistic bacteria and flg22. ...201221934117
[polymorphism of lectin genes in lathyrus plants].the carbohydrate-binding sequences of the lectin genes from spring vetchling lathyrus vernus (l.) bernh., marsh vetchling l. palustris (l.), and gmelin's vetchling l. gmelinii (fitsch) (fabaceae) were determined. computer-aided analysis revealed substantial differences between nucleotide and predicted amino acid sequences of the lectin gene regions examined in each of the three vetchling species tested. in the phylogenetic trees based on sequence similarity of carbohydrate-biding regions of legu ...201121938955
Burkholderia phytofirmans strain PsJN primes Vitis vinifera L. and confers a better tolerance to low non-freezing temperatures.Several endophytic bacteria reportedly induce resistance to biotic stress and abiotic stress tolerance in several plant species. Burkholderia phytofirmans strain PsJN (PsJN) is a plant growth-promoting rhizobacterium (PGPR) that is able to colonize grapevine tissues and induce resistance to gray mold. Further, PsJN induces physiological changes that increase grapevine tolerance to low non-freezing temperatures. To better understand how bacteria induced the observed phenomena, stress-related gene ...201121942451
[Features of the expression of a meristem-specific WOX5 gene during nodule organogenesis in legumes].In recent years, the role of WOX genes encoding homeodomain transcription factors in the development of the apical meristem of shoots and roots has been actively investigated. However, the role of WOX genes in the control of the cell proliferation in other meristem types is poorly studied. In our work, we have studied the role of the WOX5 gene in the development of the meristem in nitrogen-fixing nodules developing on the roots of legumes in a symbiosis with rhizobia. We have shown that the WOX5 ...201121950052
The genome of the plant growth-promoting rhizobacterium Paenibacillus polymyxa M-1 contains nine sites dedicated to nonribosomal synthesis of lipopeptides and polyketides.The genome of Paenibacillus polymyxa M-1 consisted of a 5.8-Mb chromosome and a 360-kb plasmid. Nine sites were dedicated to nonribosomal synthesis of lipopeptides and polyketides. Eight of them were located at the chromosome, while one gene cluster predicted to encode an unknown secondary metabolite was present on the plasmid.201121952539
characterization of rhizobia from legumes of agronomic interest grown in semi-arid areas of central spain relates genetic differences to soil properties.a study of symbiotic bacteria from traditional agricultural legumes from central spain was performed to create a collection of rhizobia from soils differing in physicochemical, analytical and/or agroecological properties which could be well-adapted to the environmental conditions of this region, and be used for sustainable agricultural practices. thirty-six isolates were obtained from root-nodules of fifteen legume species (including cicer arietinum, lathyrus sativus, lens culinaris, lupinus spp ...201121953333
novel insights into the biotin carboxylase domain reactions of pyruvate carboxylase from rhizobium etli.the catalytic mechanism of the mgatp-dependent carboxylation of biotin in the biotin carboxylase domain of pyruvate carboxylase from r. etli (repc) is common to the biotin-dependent carboxylases. the current site-directed mutagenesis study has clarified the catalytic functions of several residues proposed to be pivotal in mgatp-binding and cleavage (glu218 and lys245), hco(3)(-) deprotonation (glu305 and arg301), and biotin enolization (arg353). the e218a mutant was inactive for any reaction inv ...201121957995
interaction between the biotin carboxyl carrier domain and the biotin carboxylase domain in pyruvate carboxylase from rhizobium etli.pyruvate carboxylase (pc) catalyzes the atp-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. to effect catalysis, the tethered biotin of pc must gain access to active sites in both the biotin carboxylase domain and the carboxyl transferase domain. previous studies have demonstrated that a mutation of threonine 882 to alanine in pc from rhizobium etli renders the carboxyl transferase domain inactive and favors the positioning of biotin i ...201121958016
Activation and inhibition of pyruvate carboxylase from Rhizobium etli.While crystallographic structures of the R. etli pyruvate carboxylase (PC) holoenzyme revealed the location and probable positioning of the essential activator, Mg(2+), and nonessential activator, acetyl-CoA, an understanding of how they affect catalysis remains unclear. The current steady-state kinetic investigation indicates that both acetyl-CoA and Mg(2+) assist in coupling the MgATP-dependent carboxylation of biotin in the biotin carboxylase (BC) domain with pyruvate carboxylation in the car ...201121958066
galega orientalis is more diverse than galega officinalis in caucasus--whole-genome aflp analysis and phylogenetics of symbiosis-related genes.legume plants can obtain combined nitrogen for their growth in an efficient way through symbiosis with specific bacteria. the symbiosis between rhizobium galegae and its host plant galega is an interesting case where the plant species g. orientalis and g. officinalis form effective, nitrogen-fixing, symbioses only with the appropriate rhizobial counterpart, r. galegae bv. orientalis and r. galegae bv. officinalis, respectively. the symbiotic properties of nitrogen-fixing rhizobia are well studie ...201121980996
Toxicological assessment of selective pesticides towards plant growth promoting activities of phosphate solubilizing Pseudomonas aeruginosa.The study was designed to assess the effect of selected pesticides (metribuzin, glyphosate, imidacloprid, thiamethoxam, hexaconazole, metalaxyl and kitazin) at the recommended and higher rates on plant growth promoting activities of Pseudomonas aeruginosa strain PS1 isolated from mustard (Brassica compestris) rhizosphere. The strain PS1 was specifically chosen owing to its substantial tolerance against pesticides, phosphate solubilization and considerable production of indole acetic acid, sidero ...201121983319
Stimulation of methanotrophic growth in cocultures by cobalamin excreted by rhizobia.Methanotrophs play a key role in the global carbon cycle, in which they affect methane emissions and help to sustain diverse microbial communities through the conversion of methane to organic compounds. To investigate the microbial interactions that cause positive effects on methanotrophs, cocultures were constructed using Methylovulum miyakonense HT12 and each of nine nonmethanotrophic bacteria, which were isolated from a methane-utilizing microbial consortium culture established from forest so ...201121984248
genotypic characterization of phage-typed indigenous soybean bradyrhizobia and their host range symbiotic effectiveness.analysis of genetic diversity among indigenous rhizobia and its symbiotic effectiveness with soybean cultivar is important for development of knowledge about rhizobial ecology. in india, little is known about the genetic resources and diversity of rhizobia nodulating soybean. indigenous bradyrhizobia isolated from root nodules of soybean plants, collected from traditional cultivating regions of two states (madhya pradesh and uttar pradesh) of india, were screened for bacteriophage sensitivity to ...201121984348
rhizobium petrolearium sp. nov., isolated from oil-contaminated soil.two gram-staining-negative, aerobic, rod-shaped bacteria, designated strains sl-1(t) and f11 which had the ability to decompose polycyclic aromatic hydrocarbons (pahs) were isolated from soil samples contaminated by oil. the cells were motile by polar or lateral flagella. according to comparison of 16s rrna gene sequences, strains sl-1(t) and f11 were identical and showed the greatest degree of similarity (96.8 %) to both r. oryzae alt505(t) and r. mesosinicum ccbau 25010(t); however, only r. or ...201121984664
nodulin 41, a novel late nodulin of common bean with peptidase activity.the legume-rhizobium symbiosis requires the formation of root nodules, specialized organs where the nitrogen fixation process takes place. nodule development is accompanied by the induction of specific plant genes, referred to as nodulin genes. important roles in processes such as morphogenesis and metabolism have been assigned to nodulins during the legume-rhizobium symbiosis.201121985276
modulation of host immunity by beneficial microbes.in nature, plants abundantly form beneficial associations with soilborne microbes that are important for plant survival and, as such, affect plant biodiversity and ecosystem functioning. classical examples of symbiotic microbes are mycorrhizal fungi that aid in the uptake of water and minerals, and rhizobium bacteria that fix atmospheric nitrogen for the plant. several other types of beneficial soilborne microbes, such as plant-growth-promoting rhizobacteria and fungi with biological control act ...201121995763
A plant arabinogalactan-like glycoprotein promotes a novel type of polar surface attachment by Rhizobium leguminosarum.Rhizobium leguminosarum biovar viciae can attach to the roots of legume and non-legume plants. We wanted to determine if root exudates could affect in vitro surface attachment in a confocal microscopy assay. Root exudate from peas, other legumes, wheat and Arabidopsis, induced R.l. viciae to attach end-on (in a polar manner) to glass in hexagonal close packed arrays, rather than attaching along their long axis. This did not involve a reorientation, but was probably due to altered growth. The pol ...201121995765
natural variation in host-specific nodulation of pea is associated with a haplotype of the sym37 lysm-type receptor-like kinase.rhizobium leguminosarum bv. viciae, which nodulates pea and vetch, makes a mixture of secreted nodulation signals (nod factors) carrying either a c18:4 or a c18:1 n-linked acyl chain. mutation of node blocks the formation of the c18:4 acyl chain, and node mutants, which produce only c18:1-containing nod factors, are less efficient at nodulating pea. however, there is significant natural variation in the levels of nodulation of different pea cultivars by a node mutant of r. leguminosarum bv. vici ...201121995800
Biological activity of (lipo)polysaccharides of the exopolysaccharide-deficient mutant Rt120 derived from Rhizobium leguminosarum bv. trifolii strain TA1.Lipopolysaccharides (LPS) from Rhizobium leguminosarum biovar trifolii TA1 (RtTA1) and its mutant Rt120 in the pssB?pssA intergenic region as well as degraded polysaccharides (DPS) derived from the LPS were elucidated in terms of their chemical composition and biological activities. The polysaccharide portions were examined by methylation analysis, MALDI-TOF mass spectrometry, and (1)H NMR spectroscopy. A high molecular mass carbohydrate fraction obtained from Rt120 DPS by Sephadex G-50 gel chro ...201121999546
Genomic lineages of Rhizobium etli revealed by the extent of nucleotide polymorphisms and low recombination.Most of the DNA variations found in bacterial species are in the form of single nucleotide polymorphisms (SNPs), but there is some debate regarding how much of this variation comes from mutation versus recombination. The nitrogen-fixing symbiotic bacteria Rhizobium etli is highly variable in both genomic structure and gene content. However, no previous report has provided a detailed genomic analysis of this variation at nucleotide level or the role of recombination in generating diversity in thi ...201122004448
glutathione is required by rhizobium etli for glutamine utilization and symbiotic effectiveness.here we provide genetic and biochemical evidence indicating that the ability of rhizobium etli bacteria to efficiently catabolize glutamine depends on its ability to produce reduced glutathione (l-γ-glutamyl-l-cysteinylglycine, gsh). we find that gsh-deficient strains, namely a gshb (gsh synthetase) and a gor (gsh reductase) mutant, can use different amino acids including histidine, alanine and asparagine, but not glutamine, as sole source of carbon/energy and nitrogen. moreover, l-buthionine(s, ...201122007600
studies on the biodegradation of fosfomycin: synthesis of 13c-labeled intermediates, feeding experiments with rhizobium huakuii pmy1, and isolation of labeled amino acids from cell mass by hplc.racemic (1r*,2r*)-1,2-dihydroxy-[1-(13)c(1)]propylphosphonic acid and 1-hydroxy-[1-(13)c(1)]acetone were synthesized and fed to r. huakuii pmy1. alanine and a mixture of valine and methionine were isolated as their n-acetyl derivatives from the cell hydrolysate by reversed-phase hplc and analyzed by nmr spectroscopy. it was found that the carbon atoms of the respective carboxyl groups were highly (13)c-labeled (up to 65 %). hydroxyacetone is therefore considered an obligatory intermediate of the ...201122012897
[phenotypic and genotypic characterization of twelve rhizobial isolates from different regions of venezuela].rhizobial taxonomy and systematics have progressed substantially, nevertheless, few studies have been developed on venezuelan species. this study evaluated the phenotypic and genetic variation between 12 venezuelan indigenous rhizobial isolates and 10 international referential strains, by phenotypical traits and dna molecular markers. in this regard, a pcr-rflp of the 16s rdna gene, the presence of large plasmids, metabolic assays in solid media, salinity resistance, ph and temperature growth co ...201122017109
Field monitoring of plant-growth-promoting rhizobacteria by colony immunoblotting.Inoculant plant-growth-promoting bacteria are emerging as an important component of sustainable agriculture. There is a need to develop inexpensive methods for enumerating these organisms after their application in the field, to better understand their survival and impacts on yields. Immunoblotting is one potential method to measure viable cells, but the high cost of the conventionally used nylon membranes makes this method prohibitive. In this study, less expensive alternative materials such as ...201122017658
adaptation of rhizobium leguminosarum to pea, alfalfa and sugar beet rhizospheres investigated by comparative transcriptomics.abstract: background: the rhizosphere is the microbe-rich zone around plant roots and is a key determinant of the biosphere's productivity. comparative transcriptomics was used to investigate general and plant-specific adaptations during rhizosphere colonization. rhizobium leguminosarum biovar viciae was grown in the rhizospheres of pea (its legume nodulation host), alfalfa (a non-host legume) and sugar beet (non-legume). gene expression data were compared to metabolic and transportome maps to ...201122018401
Identification and Characterization of the Rhizobium sp. Strain GIN611 Glycoside Oxidoreductase Resulting in the Deglycosylation of Ginsenosides.Using enrichment culture, Rhizobium sp. strain GIN611 was isolated as having activity for deglycosylation of a ginsenoside, compound K (CK). The purified heterodimeric protein complex from Rhizobium sp. GIN611 consisted of two subunits with molecular masses of 63.5 kDa and 17.5 kDa. In the genome, the coding sequence for the small subunit was located right after the sequence for the large subunit, with one nucleotide overlapping. The large subunit showed CK oxidation activity, and the deglycosyl ...201222020506
rhizobium halophytocola sp. nov., a novel bacterium isolated from the root of a coastal dune plant.during a study of endophytic bacteria from coastal dune plants, a bacterial strain, designated yc6881t, was isolated from the root of rosa rugosa collected from the coastal dune areas of namhae island. the bacterium was found to be gram-negative, motile, halophilic and heterotrophic with a polar single flagellum. strain yc6881t exhibited growth at temperature 4-37 °c (optimum at 28-32 °c), ph 6.0-9.0 (optimum at ph 7.0-8.0) and was able to grow at nacl concentrations in the range of 0-7.5 % (w/v ...201122021574
escherichia coli bdca controls biofilm dispersal in pseudomonas aeruginosa and rhizobium meliloti.abstract:201122029875
A phylogenetic strategy based on a legume-specific whole genome duplication yields symbiotic cytokinin type-a response regulators.Legumes host their Rhizobium spp. symbiont in novel root organs called nodules. Nodules originate from differentiated root cortical cells that dedifferentiate and subsequently form nodule primordia, a process controlled by cytokinin. A whole-genome duplication has occurred at the root of the legume Papilionoideae subfamily. We hypothesize that gene pairs originating from this duplication event and are conserved in distinct Papilionoideae lineages have evolved symbiotic functions. A phylogenetic ...201122034625
rhizobium radiobacter bacteremia in a neonate.rhizobium radiobacter bacteremia is an infrequent cause of human infection. we report a rare manifestation of r. radiobacter infection in which bacteremia occurred in a newborn infant without other risk factors.201122038113
Genome sequence of the diazotrophic Gram-positive rhizobacterium Paenibacillus riograndensis SBR5(T).Paenibacillus riograndensis SBR5(T), a nitrogen-fixing Gram-positive rhizobacterium isolated from a wheat field in the south of Brazil, has a great potential for agricultural applications due to its plant growth promotion effects. Here we present the draft genome sequence of P. riograndensis SBR5(T). Its 7.37-Mb genome encodes determinants of the diazotrophic lifestyle and plant growth promotion, such as nitrogen fixation, antibiotic resistance, nitrate utilization, and iron uptake.201122038959
strigolactone biosynthesis in medicago truncatula and rice requires the symbiotic gras-type transcription factors nsp1 and nsp2.legume gras (gai, rga, scr)-type transcription factors nodulation signaling pathway1 (nsp1) and nsp2 are essential for rhizobium nod factor-induced nodulation. both proteins are considered to be nod factor response factors regulating gene expression after symbiotic signaling. however, legume nsp1 and nsp2 can be functionally replaced by nonlegume orthologs, including rice (oryza sativa) nsp1 and nsp2, indicating that both proteins are functionally conserved in higher plants. here, we show that n ...201122039214
Diversity of 16S rRNA genes from bacteria of sugarcane rhizosphere soil.Sugarcane is an important agricultural product of Brazil, with a total production of more than 500 million tons. Knowledge of the bacterial community associated with agricultural crops and the soil status is a decisive step towards understanding how microorganisms influence crop productivity. However, most studies aim to isolate endophytic or rhizosphere bacteria associated with the plant by culture-dependent approaches. Culture-independent approaches allow a more comprehensive view of entire ba ...201122042267
preference in the nodulation of phaseolus vulgaris cv. rab39. ii. effect of delayed inoculation or low cell representation in the inoculant on nodule occupancy by rhizobium tropici umr1899.common bean (phaseolus vulgaris l.) is a traditional crop in much of latin america, where it is often planted into soils containing numerous, sometimes ineffective, indigenous rhizobia. the presence of these indigenous organisms can limit response to inoculation. because of this, we have sought bean cultivars that will nodulate preferentially with the inoculant strain, and have previously reported on the preference between the bean cultivar rab39 and strains of rhizobium tropici. we have detaile ...199622049998
Rhizobium helanshanense sp. nov., a bacterium that nodulates Sphaerophysa salsula (Pall.) DC. in China.Studying rhizobia in the root nodules of Sphaerophysa salsula (Pall.) DC in the northwest of China, we obtained five strains classified as genus Rhizobium on the basis of their 16S rRNA gene sequences. The sequence similarity of strain CCNWQTX14(T) with the most related species was 99.0%. Further phylogenetic analysis of housekeeping genes (recA and atpD) suggested the five strains comprised a novel lineage within Rhizobium. The nifH and nodD gene sequences of CCNWQTX14(T) were phylogenetically ...201122065311
Synthesis of the Flavonoid-Induced Lipopolysaccharide of Rhizobium Sp. Strain NGR234 Requires Rhamnosyl Transferases Encoded by Genes rgpF and wbgA.In the presence of flavonoids, Rhizobium sp. strain NGR234 synthesizes a new lipopolysaccharide (LPS), characterized by a rhamnan O-antigen. The presence of this rhamnose-rich LPS is important for the establishment of competent symbiotic interactions between NGR234 and many species of leguminous plants. Two putative rhamnosyl transferases are encoded in a cluster of genes previously shown to be necessary for the synthesis of the rhamnose-rich LPS. These two genes, wbgA and rgpF, were mutated. Th ...201122066901
Biogeography of symbiotic and other endophytic bacteria isolated from medicinal Glycyrrhiza species in China.A total of 159 endophytic bacteria were isolated from surface-sterilized root nodules of wild perennial Glycyrrhiza legumes growing on 40 sites in central and northwestern China. Amplified fragment length polymorphism (AFLP) genomic fingerprinting and sequencing of partial 16S rRNA genes revealed that the collection mainly consisted of Mesorhizobium, Rhizobium, Sinorhizobium, Agrobacterium and Paenibacillus species. Based on symbiotic properties with the legume hosts Glycyrrhiza uralensis and Gl ...201122066910
draft genome sequence of the biocontrol bacterium pseudomonas putida b001, an oligotrophic bacterium that induces systemic resistance to plant diseases.pseudomonas putida b001 is a rhizobacterium that was isolated on the basis of its abilities to grow under low-nutrient conditions and induce systemic resistance against bacterial, fungal, and viral diseases of plants. here we report the draft genome sequence and automatic annotation of strain b001. comparison of this sequence to the sequenced genome of p. putida kt2440 points to a subset of gene functions that may be related to the defense-inducing functions of b001.201122072649
growth and cesium uptake responses of phytolacca americana linn. and amaranthus cruentus l. grown on cesium contaminated soil to elevated co2 or inoculation with a plant growth promoting rhizobacterium burkholderia sp. d54, or in combination.growth and cesium uptake responses of plants to elevated co(2) and microbial inoculation, alone or in combination, can be explored for clean-up of contaminated soils, and this induced phytoextraction may be better than the natural process. the present study used open-top chambers to investigate combined effects of burkholderia sp. d54 inoculation and elevated co(2) (860 μl l(-1)) on growth and cs uptake by phytolacca americana and amaranthus cruentus grown on soil spiked with various levels of c ...201122074893
rhizobium grahamii sp. nov. from dalea leporina, leucaena leucocephala, clitoria ternatea nodules, and rhizobium mesoamericanum sp. nov. from phaseolus vulgaris, siratro, cowpea and mimosa pudica nodules.two novel related rhizobium species, rhizobium grahamii and rhizobium mesoamericanum were identified by a polyphasic approach using dna-dna hybridization, whole genome sequencing, phylogenetic and phenotypic characterization including nodulation of leucaena leucocephala and phaseolus vulgaris (bean). as similar bacteria were found in los tuxtlas rain forest and in central america we suggest the existence of a mesoamerican microbiological corridor. the type strain of rhizobium grahamii sp. nov. i ...201122081714
contribution of nfp lysm domains to the recognition of nod factors during the medicago truncatula/sinorhizobium meliloti symbiosis.the root nodule nitrogen fixing symbiosis between legume plants and soil bacteria called rhizobia is of great agronomical and ecological interest since it provides the plant with fixed atmospheric nitrogen. the establishment of this symbiosis is mediated by the recognition by the host plant of lipo-chitooligosaccharides called nod factors (nfs), produced by the rhizobia. this recognition is highly specific, as precise nf structures are required depending on the host plant. here, we study the imp ...201122087221
nitrogen fixation and nitrogen fertilization of soybeans.abstract in pot experiments with (15)n labelled soil and mineral (15)n, the influence of bradyrhizobium (rhizobium japonicum) inoculation and n fertilization on the symbiotic n(2) fixation and yield of soybeans [glycine max (l.) merill., cv. 'fiskeby v'] was investigated. symbiotic n(2) fixation only occured after inoculation with bradyrhizobium. considerable differences in efficiency of the bacterial preparations were observed. shortly after flowering, the symbiotic nitrogen fixation was fini ...199622088108
A genetic discontinuity in root-nodulating bacteria of cultivated pea in the Indian trans-Himalayas.Evolutionary relationships of 120 root-nodulating bacteria isolated from the nodules of Pisum sativum cultivated at 22 different locations of the trans-Himalayan valleys of Lahaul and Spiti in the state of Himachal Pradesh of India were studied using 16S rRNA gene PCR-RFLP, ERIC-PCR, sequencing of 16S rRNA, atpD, recA, nodC and nifH genes, carbon-source utilization pattern (BIOLOG™), and whole-cell fatty acid profiling. The results demonstrated that all isolates belonged to Rhizobium leguminosar ...201222092487
Key physiological properties contributing to rhizosphere adaptation and plant growth promotion abilities of Azospirillum brasilense.Azospirillum brasilense is a plant growth promoting rhizobacterium (PGPR) that is being increasingly used in agriculture in a commercial scale. Recent research has elucidated key properties of A. brasilense that contribute to its ability to adapt to the rhizosphere habitat and to promote plant growth. They include synthesis of the auxin indole-3-acetic acid, nitric oxide, carotenoids, and a range of cell surface components as well as the ability to undergo phenotypic variation. Storage and utili ...201222092983
genetic diversity of mimosa pudica rhizobial symbionts in soils of french guiana: investigating the origin and diversity of burkholderia phymatum and other beta-rhizobia.the genetic diversity of 221 mimosa pudica bacterial symbionts trapped from eight soils from diverse environments in french guiana was assessed by 16s rrna pcr-rflp, rep-pcr fingerprints, as well as by phylogenies of their 16s rrna and reca housekeeping genes, and by their nifh, noda and nodc symbiotic genes. interestingly, we found a large diversity of beta-rhizobia, with burkholderia phymatum and burkholderia tuberum being the most frequent and diverse symbiotic species. other species were als ...201122093060
modulation of metabolism and switching to biofilm prevail over exopolysaccharide production in the response of rhizobium alamii to cadmium.heavy metals such as cadmium (cd(2+)) affect microbial metabolic processes. consequently, bacteria adapt by adjusting their cellular machinery. we have investigated the dose-dependent growth effects of cd(2+) on rhizobium alamii, an exopolysaccharide (eps)-producing bacterium that forms a biofilm on plant roots. adsorption isotherms show that the eps of r. alamii binds cadmium in competition with calcium. a metabonomics approach based on ion cyclotron resonance fourier transform mass spectrometr ...201122096497
Casuarina Root Exudates Alter the Physiology, Surface Properties, and Plant Infectivity of Frankia sp. Strain CcI3.The actinomycete genus Frankia forms nitrogen-fixing symbioses with 8 different families of actinorhizal plants, representing more than 200 different species. Very little is known about the initial molecular interactions between Frankia and host plants in the rhizosphere. Root exudates are important in Rhizobium-legume symbiosis, especially for initiating Nod factor synthesis. We measured differences in Frankia physiology after exposure to host aqueous root exudates to assess their effects on ac ...201222101047
the nitric oxide response in plant-associated endosymbiotic bacteria.nitric oxide (no) is a gaseous signalling molecule which becomes very toxic due to its ability to react with multiple cellular targets in biological systems. bacterial cells protect against no through the expression of enzymes that detoxify this molecule by oxidizing it to nitrate or reducing it to nitrous oxide or ammonia. these enzymes are haemoglobins, c-type nitric oxide reductase, flavorubredoxins and the cytochrome c respiratory nitrite reductase. expression of the genes encoding these enz ...201122103544
change in land use alters the diversity and composition of bradyrhizobium communities and led to the introduction of rhizobium etli into the tropical rain forest of los tuxtlas (mexico).nitrogen-fixing bacteria of the bradyrhizobium genus are major symbionts of legume plants in american tropical forests, but little is known about the effects of deforestation and change in land use on their diversity and community structure. forest clearing is followed by cropping of bean (phaseolus vulgaris) and maize as intercropped plants in los tuxtlas tropical forest of mexico. the identity of bean-nodulating rhizobia in this area is not known. using promiscuous trap plants, bradyrhizobia w ...201122109095
Characterization of the galacturonosyl transferase genes rgtA, B, C, D, and E responsible for lipopolysaccharide synthesis in the nitrogen-fixing endosymbiont Rhizobium leguminosarum: Lipopolysaccharide core and lipid A galacturonosyl residues confer membrane stability.Rhizobium lipopolysaccharide (LPS) contains four terminally linked galacturonic acid (GalA) residues: one attached to the lipid A and three attached to the core oligosaccharide moiety. Attachment of the GalA residues requires the lipid donor dodecaprenyl-phosphate GalA (Dod-P-GalA) which is synthesized by the GalA transferase (GalAT) RgtE reported here. The galacturonosyl transferases (GalATs) RgtA, B, and C utilize Dod-P-GalA to attach GalAs on the LPS core region and RgtD attaches GalA to the ...201122110131
Functional characterization of the quorum sensing regulator RsaL in the plant-beneficial strain Pseudomonas putida WCS358.In many bacteria quorum sensing systems rely on a signal receptor and a synthase producing N-acyl-homoserine lactone(s) as signal molecule(s). In some species, the rsaL gene, located between the signal receptor and synthase genes, encodes for a repressor limiting signal synthase expression and hence signal molecule production.Here we investigate the molecular mechanism of action of the RsaL protein (RsaL(WCS)) in the plant growth-promoting rhizobacterium Pseudomonas putida WCS358.In P. putida WC ...201122113916
regulation of the structure and activity of pyruvate carboxylase by acetyl coa.in this review we examine the effects of the allosteric activator, acetyl coa on both the structure and catalytic activities of pyruvate carboxylase. we describe how the binding of acetyl coa produces gross changes to the quaternary and tertiary structures of the enzyme that are visible in the electron microscope. these changes serve to stabilize the tetrameric structure of the enzyme. the main locus of activation of the enzyme by acetyl coa is the biotin carboxylation domain of the enzyme where ...201122120519
Evaluation of the coal-degrading ability of Rhizobium and chelatococcus strains isolated from the formation water of an Indian coal bed.The rise in global energy demand has prompted researches on developing strategies for transforming coal into a cleaner fuel. This requires isolation of microbes with the capability to degrade complex coal into simpler substrates to support methanogenesis in the coal beds. In this study, aerobic bacteria were isolated from an Indian coal bed that can solubilize and utilize coal as the sole source of carbon. The six bacterial isolates capable of growing on coal agar medium were identified on the b ...201122127119
locoweed dose responses to nitrogen: positive for biomass and primary physiology, but inconsistent for an alkaloid.• premise of the study: plant communities may be influenced by toxic secondary metabolites or enhanced plant growth from plant-symbiont interactions. the c:n hypothesis predicts that carbon or nitrogen constrains plant secondary metabolite production, but it does not consider compounds produced by plant symbionts. locoweeds are legumes that can have fungal endophyte alkaloid (swainsonine [swa]) production, which causes livestock poisoning. we studied four locoweed taxa to test whether average sw ...201122130270
effect of genomic rearrangement on heavy metal tolerance in the plant-growth-promoting rhizobacterium azospirillum brasilense sp245.a derivative of azospirillum brasilense sp245, sp245.5, which spontaneously lost 85 and 120 mda replicons upon the formation of a new megaplasmid, has been shown to produce a novel lipopolysaccharide and to lose calcofluor-binding polysaccharides. as compared to sp245, the derivative displays notably increased heavy metal tolerance. the phenotypes of sp245 and sp245.5 are characterized by the following minimal inhibitory concentrations (mics) of heavy metals: 0.5 and 0.9 μmol l(-1) of ag(+), 0.4 ...201122130692
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