| sinorhizobium medicae sp. nov., isolated from annual medicago spp. | the taxonomic position of isolates of a new genomic species (designated genomic species 2) obtained from several annual medicago species and originating from different geographical locations was established through the results of phenotypic tests (including the results of auxanographic and biochemical tests and symbiotic properties) and 16s rrna phylogenetic inferences. a comparison of the complete 16s rrna sequence of a representative of genomic species 2 (strain a 321t [t = type strain]) with ... | 1996 | 8863426 |
| rapid identification of medicago nodulating strains by using two oligonucleotide probes complementary to 16s rdna sequences. | symbiotic bacteria associated with the medicago genus are separated into two closely related species named sinorhizobium meliloti and sinorhizobium medicae. to discriminate rapidly between these two bacterial species, two 15-base dna probes, 16smfs and 16smed, were designed from the alignment of 16s rdna sequences to differentiate s. meliloti from s. medicae. their specificities were evaluated by dot-blot hybridization experiments on 25 reference strains representing 13 species of rhizobium and ... | 1997 | 9336948 |
| genetic diversity of sinorhizobium populations recovered from different medicago varieties cultivated in tunisian soils. | a collection of 468 rhizobial isolates was obtained from different ecological areas of tunisia by trapping them on medicago sativa cv. gabes, medicago scutelleta cv. kelson, medicago truncatula, and medicago ciliaris. a subsample of 134 rhizobia was chosen to determine their plasmid profile, and 89 isolates were subjected to multilocus enzyme electrophoresis (mlee) and pcr/rflp analysis using 16s, igs (inter genic spacer), and nifkd probes. twenty-five representatives from these isolates were ev ... | 2001 | 11261493 |
| genetic relationship of sinorhizobium meliloti and sinorhizobium medicae strains isolated from caucasian region. | sinorhizobium meliloti and sinorhizobium medicae are two closely related species of the genus sinorhizobium showing a similar host range, nodulating leguminous species of the genera medicago, melilotus and trigonella, but their phylogenic relationship has not been elucidated yet. in this paper we report the application of three different molecular markers, (i) rflp of nodd genes, (ii) 16s-23s rdna intergenic gene spacer fingerprinting and (iii) amplification fragment length polymorphism to s. me ... | 2003 | 12670682 |
| the genus name ensifer casida 1982 takes priority over sinorhizobium chen et al. 1988, and sinorhizobium morelense wang et al. 2002 is a later synonym of ensifer adhaerens casida 1982. is the combination "sinorhizobium adhaerens" (casida 1982) willems et al. 2003 legitimate? request for an opinion. | the synonymy of the genera ensifer and sinorhizobium was recently reported, but it was proposed that the later-named genus, sinorhizobium, take priority in nomenclature. there is no justification in the international code of nomenclature of bacteria (prokaryotes) for this step; ensifer is the correct name of the genus, with ensifer adhaerens as the type species. species previously allocated to sinorhizobium are here proposed as the new combinations ensifer arboris, ensifer fredii, ensifer kostie ... | 2003 | 14657154 |
| sinorhizobium medicae genes whose regulation involves the acts and/or actr signal transduction proteins. | acts-actr proteins belong to a highly conserved family of two-component signal transduction systems involved in global regulation in the alpha-proteobacteria; they were first identified in sinorhizobium medicae (previously sinorhizobium meliloti) as essential for acid-tolerance. this paper reports on the identification of genes regulated by acts and/or actr in s. medicae. to do this, random gusa fusions were created in s. medicae to follow gene transcription in an acts chromosomal knockout mutan ... | 2004 | 15212786 |
| probing for ph-regulated genes in sinorhizobium medicae using transcriptional analysis. | the low ph sensitivity of sinorhizobium species is one of the major causes of reduced productivity of medicago species (such as lucerne) sown in acidic soils. to investigate the ph response of an acid-tolerant sinorhizobium medicae strain, a pool of random promoter fusions to gusa was created using minitransposon insertional mutagenesis. acid-activated expression was identified in 11 mutants; rhizobial dna flanking insertions in 10 mutants could be cloned and the dna sequences obtained were used ... | 2004 | 15263817 |
| probing for ph-regulated proteins in sinorhizobium medicae using proteomic analysis. | to elucidate the mechanisms of ph response in an acid-tolerant sinorhizobium medicae strain we have identified acid-activated gene transcription and now complement this approach by using a proteomic analysis to identify the changes that occur following exposure to acidity. protein profiles of persistently or transiently acid-stressed s. medicae cells were compared to those grown in ph neutral, buffered media. fifty ph-regulated proteins were identified; n-terminal sequences for 15 of these were ... | 2004 | 15263818 |
| rhizobial strain involvement in plant growth, nodule protein composition and antioxidant enzyme activities of chickpea-rhizobia symbioses: modulation by salt stress. | mesorhizobium ciceri, mesorhizobium mediterraneum and sinorhizobium medicae strains showed different symbiotic performances when inoculated to chickpea (cicer arietinum l., cv. chetoui) at unstressed conditions and under salt stress. the analysis of nodular proteic composition and antioxidant enzyme activities revealed a polymorphism of patterns on sds and native page suggesting a potential dependence on the bacterial partner. salt effect was analysed on plant growth, nitrogen fixation and antio ... | 2004 | 15474377 |
| nitrogen-fixing sinorhizobia with medicago laciniata constitute a novel biovar (bv. medicaginis) of s. meliloti. | sixty-eight new rhizobial isolates were obtained from root-nodules of medicago laciniata and from mediterranean soils in tunisia and france. all of them were identified as sinorhizobium meliloti on the basis of pcr-rflp analyses of 16s rdna and the intergenic spacer sequence between 16s and 23s rdnas. dna/dna hybridization, phenotypic characterization and 16s rrna gene sequencing led to the conclusion that they belong the same taxon. all new isolates shared the ability to nodulate and fix nitrog ... | 2006 | 16413160 |
| development of a lab-made microarray for analyzing the genetic diversity of nitrogen fixing symbionts sinorhizobium meliloti and sinorhizobium medicae. | some bacterial species, like nitrogen-fixing sinorhizobium that interact with medicago plants, are prone to frequent horizontal gene transfers. investigation of their genetic structure requires to study polymorphism patterns at many loci. although dna microarrays represent a method of choice for high throughput analysis of polymorphisms, this technology yet remains an expensive and heavy approach, thus depriving most of research groups from this powerful tool. in an attempt to overcome this limi ... | 2006 | 16626823 |
| agrobacterium strains isolated from root nodules of common bean specifically reduce nodulation by rhizobium gallicum. | in a previous work, we showed that non-nodulating agrobacteria strains were able to colonize root nodules of common bean. both rhizobia and agrobacteria co-existed in the infected nodules. no impact on symbiosis was found in laboratory conditions when using sterile gravel as a support for growth. in this study, soil samples originating from different geographic and agronomic regions in tunisia were inoculated with a mixture of agrobacteria strains isolated previously from root nodules of common ... | 2006 | 16629759 |
| multilocus sequence typing as an approach for population analysis of medicago-nodulating rhizobia. | multilocus sequence typing (mlst), a sequence-based method to characterize bacterial genomes, was used to examine the genetic structure in a large collection of medicago-nodulating rhizobial strains. this is the first study where mlst has been applied in conjunction with eburst analysis to determine the population genetic structure of nonpathogenic bacteria recovered from the soil environment. sequence variation was determined in 10 chromosomal loci of 231 strains that predominantly originated f ... | 2006 | 16855247 |
| recombination and selection shape the molecular diversity pattern of nitrogen-fixing sinorhizobium sp. associated to medicago. | we investigate the genetic structure and molecular selection pattern of a sympatric population of sinorhizobium meliloti and sinorhizobium medicae. these bacteria fix nitrogen in association with plants of the genus medicago. a set of 116 isolates were obtained from a soil sample, from root nodules of three groups of plants representing among-species, within-species and intraline diversity in the medicago genus. bacteria were characterized by sequencing at seven loci evenly distributed along the ... | 2006 | 16911196 |
| the sinorhizobium medicae wsm419 lpia gene is transcriptionally activated by fsrr and required to enhance survival in lethal acid conditions. | sinorhizobium medicae wr101 was identified as a mutant of wsm419 that contained a minitransposon-induced transcriptional gusa fusion activated at least 20-fold at ph 5.7. the expression of this fusion in moderately acid conditions was dependent on the calcium concentration; increasing the calcium concentration to enhance cell growth and survival in acid conditions decreased the expression of the fusion. a gene region containing the gusa fusion was sequenced, revealing five s. medicae genes: tcsa ... | 2006 | 17005985 |
| population genetic structure of sinorhizobium meliloti and s. medicae isolated from nodules of medicago spp. in mexico. | we studied the genetic structure of 176 bacterial isolates from nodules of medicago sativa, m. lupulina and m. polymorpha in fifteen sites distributed in three localities in mexico. the strains were characterized by multilocus enzyme electrophoresis, plasmid profiles, pcr restriction fragment length polymorphism of 16s rrna genes and of the intergenic spacer between 16s and 23s rrna genes, and partial sequences of glnii, reca and nodb. most of the strains were classified as sinorhizobium melilot ... | 2007 | 17386032 |
| sequence analysis of the 181-kb accessory plasmid psmesm11b, isolated from a dominant sinorhizobium meliloti strain identified during a long-term field release experiment. | the 181 251 bp accessory plasmid psmesm11b of sinorhizobium meliloti strain sm11, belonging to a dominant indigenous s. meliloti subpopulation identified during a long-term field release experiment, was sequenced. this plasmid has 166 coding sequences (cdss), 42% of which encode proteins with homology to proteins of known function. plasmid psmesm11b is a member of the repabc replicon family and contains a large gene region coding for a conjugation system similar to that of other self-transmissib ... | 2007 | 17466030 |
| horizontal gene transfer and homologous recombination drive the evolution of the nitrogen-fixing symbionts of medicago species. | using nitrogen-fixing sinorhizobium species that interact with medicago plants as a model system, we aimed at clarifying how sex has shaped the diversity of bacteria associated with the genus medicago on the interspecific and intraspecific scales. to gain insights into the diversification of these symbionts, we inferred a topology that includes the different specificity groups which interact with medicago species, based on sequences of the nodulation gene cluster. furthermore, 126 bacterial isol ... | 2007 | 17496100 |
| context dependence in the coevolution of plant and rhizobial mutualists. | several mechanisms are expected to rapidly rid mutualisms of genetic variation in partner quality. variation for mutualist quality, however, appears to be widespread. we used a model legume-rhizobium mutualism to test for evidence that context-dependent selection may maintain variation in partner quality. in a greenhouse experiment using 10 natural populations of medicago truncatula and two strains of sinorhizobium medicae, we detected significant genotype x genotype (g x g) interactions for pla ... | 2007 | 17535796 |
| the lipid lysyl-phosphatidylglycerol is present in membranes of rhizobium tropici ciat899 and confers increased resistance to polymyxin b under acidic growth conditions. | lysyl-phosphatidylglycerol (lpg) is a well-known membrane lipid in several gram-positive bacteria but is almost unheard of in gram-negative bacteria. in staphylococcus aureus, the gene product of mprf is responsible for lpg formation. low ph-inducible genes, termed ipia, have been identified in the gram-negative alpha-proteobacteria rhizobium tropici and sinorhizobium medicae in screens for acid-sensitive mutants and they encode homologs of mprf. an analysis of the sequenced bacterial genomes re ... | 2007 | 17977153 |
| genetic characterization of fast-growing rhizobia able to nodulate prosopis alba in north spain. | prosopis is a mimosaceae legume tree indigenous to south america and not naturalized in europe. in this work 18 rhizobial strains nodulating prosopis alba roots were isolated from a soil in north spain that belong to eight different randomly amplified polymorphic dna groups phylogenetically related to sinorhizobium medicae, sinorhizobium meliloti and rhizobium giardinii according to their intergenic spacer and 16s rrna gene sequences. the nodc genes of isolates close to s. medicae and s. melilot ... | 2007 | 18031342 |
| [screening for autoinducer synthase gene in sinorhizobium meliloti and analysis of the autoinducer produced by recombinant expression in escherichia coli]. | the plasmid pjz290 containing mariner transposon was used to mutagenize sinorhizobium meliloti and 3000 transposon insertion mutants were subsequently screened for autoinducer-deficient (ai-deficient) mutants. one ai-deficient mutant yw1 was obtained by quantitative activity assay and qualitative tlc detection. in an effort to characterize the transposon insertions of autoinducer-deficient mutant yw1, we performed an arbitrary pcr and sequencing techniques to identify insertion sites. the sequen ... | 2007 | 18062259 |
| stable low molecular weight rna profiling showed variations within sinorhizobium meliloti and sinorhizobium medicae nodulating different legumes from the alfalfa cross-inoculation group. | four different low molecular weight (lmw) rna profiles, designated i-iv, among 179 isolates from medicago, melilotus and trigonella species growing in a field site in northern spain were identified. from sequence analysis of the 16s rrna, atpd and reca genes as well as dna-dna hybridization analysis with representatives of each lmw rna profile it was evident that isolates with lmw rna profiles i and ii belonged to sinorhizobium meliloti and those displaying profiles iii and iv to sinorhizobium m ... | 2008 | 18399993 |
| the model legume medicago truncatula a17 is poorly matched for n2 fixation with the sequenced microsymbiont sinorhizobium meliloti 1021. | medicago truncatula (barrel medic) a17 is currently being sequenced as a model legume, complementing the sequenced root nodule bacterial strain sinorhizobium meliloti 1021 (sm1021). in this study, the effectiveness of the sm1021-m. truncatula symbiosis at fixing n(2) was evaluated. n(2) fixation effectiveness was examined with eight medicago species and three accessions of m. truncatula with sm1021 and two other sinorhizobium strains. plant shoot dry weights, plant nitrogen content and nodule di ... | 2008 | 18422896 |
| effects of medicago truncatula genetic diversity, rhizobial competition, and strain effectiveness on the diversity of a natural sinorhizobium species community. | we investigated the genetic diversity and symbiotic efficiency of 223 sinorhizobium sp. isolates sampled from a single mediterranean soil and trapped with four medicago truncatula lines. dna molecular polymorphism was estimated by capillary electrophoresis-single-stranded conformation polymorphism and restriction fragment length polymorphism on five loci (igs(nod), typa, virb11, avhb11, and the 16s rrna gene). more than 90% of the rhizobia isolated belonged to the sinorhizobium medicae species ( ... | 2008 | 18658290 |
| diversity of sinorhizobium strains nodulating medicago sativa from different iranian regions. | alfalfa is believed to have originated in north-western iran and has a long history of coexistence with its bacterial symbiont sinorhizobium in soils of iran. however, little is known about the diversity of sinorhizobium strains nodulating iranian alfalfa genotypes. in this study, sinorhizobium populations were sampled from eight different iranian sites using three cultivars of medicago sativa as trap host plants. a total of 982 rhizobial strains were isolated and species were identified showing ... | 2008 | 18783438 |
| lack of trehalose catabolism in sinorhizobium species increases their nodulation competitiveness on certain host genotypes. | the role of host and bacterial genotypes in determining the competitiveness of trehalose utilization mutants of sinorhizobium meliloti and sinorhizobium medicae was investigated here. trehalose utilization mutants of s. meliloti and s. medicae were obtained by mutagenesis of their trehalose utilization gene thub. the mutant strains and the wild type were coinoculated on three cultivars of alfalfa (medicago sativa) and two cultivars of medicago truncatula and assessed for competitiveness in root ... | 2008 | 19086182 |
| [recombinant expression of an autoinducer synthase of sinorhizobium sp.1128 in escherichia coli]. | to explore the roles of quorum sensing system in establishing symbiosis between bacterium sinorhizobium sp.1128 and its plant host melilotus suaveolens ledeb. | 2008 | 19160810 |
| different species and symbiotic genotypes of field rhizobia can nodulate phaseolus vulgaris in tunisian soils. | abstract a collection of 160 isolates of rhizobia nodulating phaseolus vulgaris in three geographical regions in tunisia was characterized by restriction fragment length polymorphism analysis of polymerase chain reaction (pcr)-amplified 16s rdna, nifh and nodc genes. nine groups of rhizobia were delineated: rhizobium gallicum biovar (bv.) gallicum, rhizobium leguminosarum bv. phaseoli and bv. viciae, rhizobium etli bv. phaseoli, rhizobium giardinii bv. giardinii, and four groups related to speci ... | 2002 | 19709241 |
| cultural conditions required for the induction of an adaptive acid-tolerance response (atr) in sinorhizobium meliloti and the question as to whether or not the atr helps rhizobia improve their symbiosis with alfalfa at low ph. | sinorhizobium meliloti associates with medicago and melilotus species to develop nitrogen-fixing symbioses. the agricultural relevance of these associations, the worldwide distribution of acid soils, and the remarkable acid sensitivity of the microsymbiont have all stimulated research on the responses of the symbionts to acid environments. we show here that an adaptive acid-tolerance response (atr) can be induced in s. meliloti, as shown previously for sinorhizobium medicae, when the bacteria ar ... | 2010 | 19958387 |
| identification of sinorhizobium (ensifer) medicae based on a specific genomic sequence unveiled by m13-pcr fingerprinting. | a collection of nodule isolates from medicago polymorpha obtained from southern and central portugal was evaluated by m13-pcr fingerprinting and hierarchical cluster analysis. several genomic clusters were obtained which, by 16s rrna gene sequencing of selected representatives, were shown to be associated with particular taxonomic groups of rhizobia and other soil bacteria. the method provided a clear separation between rhizobia and co-isolated non-symbiotic soil contaminants. ten m13-pcr groups ... | 2009 | 20112226 |
| phrr-like gene prar of azorhizobium caulinodans ors571 is essential for symbiosis with sesbania rostrata and is involved in expression of reb genes. | this study focuses on the function of the gene prar that encodes a putative transcription factor in azorhizobium caulinodans ors571, a microsymbiont of sesbania rostrata. the prar gene is a homolog of the phrr gene of sinorhizobium medicae wsm419, and the prar and phrr homologs are distributed throughout the class alphaproteobacteria. the growth and nitrogen fixation activity of an a. caulinodans prar deletion mutant in the free-living state were not significantly different from those of the wil ... | 2010 | 20382809 |
| application of multilocus sequence typing to study the genetic structure of megaplasmids in medicago-nodulating rhizobia. | a multilocus sequence typing (mlst) analysis was used to examine the genetic structure and diversity within the two large extrachromosomal replicons in medicago-nodulating rhizobia (sinorhizobium meliloti and sinorhizobium medicae). the allelic diversity within these replicons was high compared to the reported diversity within the corresponding chromosomes of the same strains (p. van berkum et al., j. bacteriol. 188:5570-5577, 2006). also, there was strong localized linkage disequilibrium (ld) b ... | 2010 | 20418433 |
| the nodulation of alfalfa by the acid-tolerant rhizobium sp. strain lpu83 does not require sulfated forms of lipochitooligosaccharide nodulation signals. | the induction of root nodules by the majority of rhizobia has a strict requirement for the secretion of symbiosis-specific lipochitooligosaccharides (nodulation factors [nfs]). the nature of the chemical substitution on the nfs depends on the particular rhizobium and contributes to the host specificity imparted by the nfs. we present here a description of the genetic organization of the nod gene cluster and the characterization of the chemical structure of the nfs associated with the broad-host- ... | 2010 | 20971905 |
| complete genome sequence of the medicago microsymbiont ensifer (sinorhizobium) medicae strain wsm419. | ensifer (sinorhizobium) medicae is an effective nitrogen fixing microsymbiont of a diverse range of annual medicago (medic) species. strain wsm419 is an aerobic, motile, non-spore forming, gram-negative rod isolated from a m. murex root nodule collected in sardinia, italy in 1981. wsm419 was manufactured commercially in australia as an inoculant for annual medics during 1985 to 1993 due to its nitrogen fixation, saprophytic competence and acid tolerance properties. here we describe the basic fea ... | 2010 | 21304680 |
| first genomic analysis of the broad-host-range rhizobium sp. lpu83 strain, a member of the low-genetic diversity oregon-like rhizobium sp. group. | alfalfa (medicago sativa) is the most cultivated forage legume for cattle and animal feeding, occupying about 32 million hectares over the world. management of the n(2)-fixing symbiosis of this plant to maximize crop production is therefore an important objective. a fundamental constraint to this aim emerges when a moderately low soil ph hampers the establishment of an effective symbiosis with indigenous and/or inoculated rhizobia. besides the association of alfalfa with ensifer (sinorhizobium) ... | 2011 | 21329739 |
| the complete genome sequence of the dominant sinorhizobium meliloti field isolate sm11 extends the s. meliloti pan-genome. | isolates of the symbiotic nitrogen-fixing species sinorhizobium meliloti usually contain a chromosome and two large megaplasmids encoding functions that are absolutely required for the specific interaction of the microsymbiont with corresponding host plants leading to an effective symbiosis. the complete genome sequence, including the megaplasmids psmesm11c (related to psyma) and psmesm11d (related to psymb), was established for the dominant, indigenous s. meliloti strain sm11 that had been isol ... | 2011 | 21396969 |
| stress tolerance and symbiotic and phylogenic features of root nodule bacteria associated with medicago species in different bioclimatic regions of tunisia. | thirty two rhizobial isolates were obtained from different bioclimatic regions of tunisia using as trap plants, medicago sativa, medicago ciliaris, medicago polymorpha and medicago minima. to study their diversity and characterize them in relation to mediterranean conditions, abiotic stress resistance, symbiotic properties and genetic diversity in terms of 16s rrna and noda sequences were assessed. five isolates from m. sativa, three from m. ciliaris and three from m. minima could grow at 45°c. ... | 2011 | 21487201 |
| population genomics of sinorhizobium medicae based on low-coverage sequencing of sympatric isolates. | we investigated the genomic diversity of a local population of the symbiotic bacterium sinorhizobium medicae, isolated from the roots of wild medicago lupulina plants, in order to assess genomic diversity, to identify genomic regions influenced by duplication, deletion or strong selection, and to explore the composition of the pan-genome. partial genome sequences of 12 isolates were obtained by roche 454 shotgun sequencing (average 5.3 mb per isolate) and compared with the published sequence of ... | 2011 | 21562597 |
| mutualism and adaptive divergence: co-invasion of a heterogeneous grassland by an exotic legume-rhizobium symbiosis. | species interactions play a critical role in biological invasions. for example, exotic plant and microbe mutualists can facilitate each other's spread as they co-invade novel ranges. environmental context may influence the effect of mutualisms on invasions in heterogeneous environments, however these effects are poorly understood. we examined the mutualism between the legume, medicago polymorpha, and the rhizobium, ensifer medicae, which have both invaded california grasslands. many of these inv ... | 2011 | 22174755 |
| genetic and functional characterization of a yet-unclassified rhizobial dtr (dna-transfer-and-replication) region from a ubiquitous plasmid conjugal system present in sinorhizobium meliloti, in sinorhizobium medicae, and in other nonrhizobial gram-negative bacteria. | rhizobia are gram-negative bacteria that live in soils and associate with leguminous plants to establish nitrogen-fixing symbioses. the ability of these bacteria to undergo horizontal gene transfer (hgt) is thought to be one of the main features to explain both the origin of their symbiotic life-style and the plasticity and dynamics of their genomes. in our laboratory we have previously characterized at the species level the non-psym plasmid mobilome in sinorhizobium meliloti, the symbiont of me ... | 2012 | 22233546 |
| mercury-resistant rhizobial bacteria isolated from nodules of leguminous plants growing in high hg-contaminated soils. | a survey of symbiotic bacteria from legumes grown in high mercury-contaminated soils (almadén, spain) was performed to produce a collection of rhizobia which could be well adapted to the environmental conditions of this region and be used for restoration practices. nineteen hg-tolerant rhizobia were isolated from nodules of 11 legume species (of the genera medicago, trifolium, vicia, lupinus, phaseolus, and retama) and characterized. based on their growth on hg-supplemented media, the isolates w ... | 2012 | 22246528 |
| the trnaarg gene and enga are essential genes on the 1.7-mb psymb megaplasmid of sinorhizobium meliloti and were translocated together from the chromosome in an ancestral strain. | bacterial genomes with two (or more) chromosome-like replicons are known, and these appear to be particularly frequent in alphaproteobacteria. the genome of the n(2)-fixing alfalfa symbiont sinorhizobium meliloti 1021 contains a 3.7-mb chromosome and 1.4-mb (psyma) and 1.7-mb (psymb) megaplasmids. in this study, the trna(arg) and enga genes, located on the psymb megaplasmid, are shown to be essential for growth. these genes could be deleted from psymb when copies were previously integrated into ... | 2013 | 23123907 |
| deep sequencing of the medicago truncatula root transcriptome reveals a massive and early interaction between nodulation factor and ethylene signals. | the legume-rhizobium symbiosis is initiated through the activation of the nodulation (nod) factor-signaling cascade, leading to a rapid reprogramming of host cell developmental pathways. in this work, we combine transcriptome sequencing with molecular genetics and network analysis to quantify and categorize the transcriptional changes occurring in roots of medicago truncatula from minutes to days after inoculation with sinorhizobium medicae. to identify the nature of the inductive and regulatory ... | 2015 | 26175514 |
| population genomics of the facultatively mutualistic bacteria sinorhizobium meliloti and s. medicae. | the symbiosis between rhizobial bacteria and legume plants has served as a model for investigating the genetics of nitrogen fixation and the evolution of facultative mutualism. we used deep sequence coverage (>100×) to characterize genomic diversity at the nucleotide level among 12 sinorhizobium medicae and 32 s. meliloti strains. although these species are closely related and share host plants, based on the ratio of shared polymorphisms to fixed differences we found that horizontal gene transfe ... | 2012 | 22876202 |
| insights into the strategies used by related group ii introns to adapt successfully for the colonisation of a bacterial genome. | group ii introns are self-splicing rnas and site-specific mobile retroelements found in bacterial and organellar genomes. the group ii intron rmint1 is present at high copy number in sinorhizobium meliloti species, and has a multifunctional intron-encoded protein (iep) with reverse transcriptase/maturase activities, but lacking the dna-binding and endonuclease domains. we characterized two rmint1-related group ii introns rmint2 from s. meliloti strain gr4 and sr.md.i1 from s. medicae strain wsm4 ... | 2014 | 25482895 |
| nodule carbohydrate catabolism is enhanced in the medicago truncatula a17-sinorhizobium medicae wsm419 symbiosis. | the symbiotic association between medicago truncatula and sinorhizobium meliloti is a well-established model system in the legume-rhizobium community. despite its wide use, the symbiotic efficiency of this model has been recently questioned and an alternative microsymbiont, s. medicae, has been proposed. however, little is known about the physiological mechanisms behind the higher symbiotic efficiency of s. medicae wsm419. in the present study, we inoculated m. truncatula jemalong a17 with eithe ... | 2014 | 25221545 |
| insights into the history of a bacterial group ii intron remnant from the genomes of the nitrogen-fixing symbionts sinorhizobium meliloti and sinorhizobium medicae. | group ii introns are self-splicing catalytic rnas that act as mobile retroelements. in bacteria, they are thought to be tolerated to some extent because they self-splice and home preferentially to sites outside of functional genes, generally within intergenic regions or in other mobile genetic elements, by mechanisms including the divergence of dna target specificity to prevent target site saturation. rmint1 is a mobile group ii intron that is widespread in natural populations of sinorhizobium m ... | 2014 | 24736785 |
| the early events underlying genome evolution in a localized sinorhizobium meliloti population. | population genetic analyses based on genome-wide sequencing data have been carried out for sinorhizobium medicae and s. meliloti, two closely related bacterial species forming nitrogen-fixing symbioses with plants of the genus medicago. however, genome coverage was low or the isolates had a broad geographic distribution, making it difficult to interpret the estimated diversity and to unravel the early events underlying population genetic variations and ecological differentiation. | 2016 | 27495742 |
| in silico identification for α-amino-ε-caprolactam racemases by using information on the structure and function relationship. | in silico identification for enzymes having desired functions is attractive because there is a possibility that numerous desirable enzymes have been deposited in databases. in this study, α-amino-ε-caprolactam (acl) racemases were searched from the ncbi protein database. four hundred thirteen fold-type i pyridoxal 5'-phosphate-dependent enzymes which are considered to contain sequences of acl racemase were firstly obtained by submitting the sequence of acl racemase from achromobacter obae to the ... | 2015 | 26206345 |
| evidence for a rhizobia-induced drought stress response strategy in medicago truncatula. | drought stress hampers plant energy and biomass production; however it is still unknown how internal c:n balance and rhizobial symbiosis impact on plant response to water limitation. here, the effect of differential optimal nitrogen nutrition and root nodule symbiosis on drought stress and rehydration responses of medicago truncatula was assessed. two groups of plants were nodulated with sinorhizobium medicae or sinorhizobium meliloti--differing in the performance of n fixation; the third group ... | 2016 | 26812498 |
| identification of nodule-specific cysteine-rich plant peptides in endosymbiotic bacteria. | the symbiosis of medicago truncatula with sinorhizobium meliloti or sinorhizobium medicae soil bacteria results in the formation of root nodules where bacteria inside the plant cells are irreversibly converted to polyploid, nondividing nitrogen-fixing bacteroids. bacteroid differentiation is host-controlled and the plant effectors are symbiosis-specific secreted plant peptides. in the m. truncatula genome there are more than 600 symbiotic peptide genes including 500 small genes coding for nodule ... | 2015 | 25690539 |
| a rhizobium selenitireducens protein showing selenite reductase activity. | biobarriers remove, via precipitation, the metalloid selenite (seo₃⁻²) from groundwater; a process that involves the biological reduction of soluble seo₃⁻² to insoluble elemental red selenium (se⁰). the enzymes associated with this reduction process are poorly understood. in rhizobium selenitireducens at least two enzymes are potentially involved; one, a nitrite reductase reduces seo₃⁻² to se⁰ but another protein may also be involved which is investigated in this study. proteins from r. seleniti ... | 2014 | 24474405 |
| enhanced nodulation and nodule development by nolr mutants of sinorhizobium medicae on specific medicago host genotypes. | the nolr gene encodes a negatively acting, transcriptional regulatory protein of core nod-factor biosynthetic genes in the sinorhizobia. although previous reports showed that nolr modulates nod-factor production and enhances nodulation speed of sinorhizobium meliloti on alfalfa, there have been no reports for the symbiotic function of this gene in the s. medicae-medicago truncatula symbiosis. here, we constructed an nolr mutant of s. medicae wsm419 and evaluated mutant and wild-type strains for ... | 2014 | 24283939 |
| involvement of source-sink relationship and hormonal control in the response of medicago ciliaris - sinorhizobium medicae symbiosis to salt stress. | in order to explore the relationship between leaf hormonal status and source-sink relations in the response of symbiotic nitrogen fixation (snf) to salt stress, three major phytohormones (cytokinins, abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid), sucrose phosphate synthase activity in source leaves and sucrolytic activities in sink organs were analysed in two lines of medicago ciliaris (salt-tolerant tnc 1.8 and salt-sensitive tnc 11.9). snf (measured as nitroge ... | 2012 | 22453803 |