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characterization of four lectin-like receptor kinases expressed in roots of medicago truncatula. structure, location, regulation of expression, and potential role in the symbiosis with sinorhizobium meliloti.to study the role of lecrk (lectin-like receptor kinase) genes in the legumerhizobia symbiosis, we have characterized the four medicago truncatula gaernt. lecrk genes that are most highly expressed in roots. three of these genes, mtlecrk7;1, mtlecrk7;2, and mtlecrk7;3, encode proteins most closely related to the class a lecrks of arabidopsis, whereas the protein encoded by the fourth gene, mtlecrk1;1, is most similar to a class b arabidopsis lecrk. all four genes show a strongly enhanced root ex ...200314630957
lysm domain receptor kinases regulating rhizobial nod factor-induced infection.the rhizobial infection of legumes has the most stringent demand toward nod factor structure of all host responses, and therefore a specific nod factor entry receptor has been proposed. the sym2 gene identified in certain ecotypes of pea (pisum sativum) is a good candidate for such an entry receptor. we exploited the close phylogenetic relationship of pea and the model legume medicago truncatula to identify genes specifically involved in rhizobial infection. the sym2 orthologous region of m. tru ...200312947035
a member of the germin-like protein family is a highly conserved mycorrhiza-specific induced gene.a medicago truncatula cdna encoding a germin-like protein (glp) was isolated from a suppression subtractive hybridization cdna library enriched for arbuscular mycorrhiza (am)-induced genes. the mtglp1 amino acid sequence shows some striking differences to previously described plant glp sequences and might therefore represent a new subgroup of this multigene family. the mtglp1 mrna was strongly induced in roots and root cultures colonized by the am fungus glomus intraradices. whereas mtglp1 is st ...200314634158
extensive and specific responses of a eukaryote to bacterial quorum-sensing signals.many bacteria use n-acyl homoserine lactone (ahl) signals to coordinate the behavior of individual cells in a local population. the successful infection of eukaryotic hosts by bacteria seems to depend particularly on such ahl-mediated "quorum-sensing" regulation. we have used proteome analysis to show that a eukaryotic host, the model legume medicago truncatula, is able to detect nanomolar to micromolar concentrations of bacterial ahls from both symbiotic (sinorhizobium meliloti) and pathogenic ...200312511600
n-acylethanolamine signaling in tobacco is mediated by a membrane-associated, high-affinity binding protein.n-acylethanolamines (naes) are fatty acid derivatives found as minor constituents of animal and plant tissues, and their levels increase 10- to 50-fold in tobacco (nicotiana tabacum) leaves treated with fungal elicitors. infiltration of tobacco leaves with submicromolar to micromolar concentrations of n-myristoylethanolamine (nae 14:0) resulted in an increase in relative phenylalanine ammonia-lyase (pal) transcript abundance within 8 h after infiltration, and this pal activation was reduced afte ...200312692337
role of anthocyanidin reductase, encoded by banyuls in plant flavonoid biosynthesis.condensed tannins (cts) are flavonoid oligomers, many of which have beneficial effects on animal and human health. the flavanol (-)-epicatechin is a component of many cts and contributes to flavor and astringency in tea and wine. we show that the banyuls (ban) genes from arabidopsis thaliana and medicago truncatula encode anthocyanidin reductase, which converts anthocyanidins to their corresponding 2,3-cis-flavan-3-ols. ectopic expression of ban in tobacco flower petals and arabidopsis leaves re ...200312532018
sinorhizobium meliloti acpxl mutant lacks the c28 hydroxylated fatty acid moiety of lipid a and does not express a slow migrating form of lipopolysaccharide.lipid a is the hydrophobic anchor of lipopolysaccharide (lps) in the outer membrane of gram-negative bacteria. lipid a of all rhizobiaceae is acylated with a long fatty acid chain, 27-hydroxyoctacosanoic acid. biosynthesis of this long acyl substitution requires a special acyl carrier protein, acpxl, which serves as a donor of c28 (omega-1)-hydroxylated fatty acid for acylation of rhizobial lipid a (brozek, k.a., carlson, r.w., and raetz, c. r. (1996) j. biol. chem. 271, 32126-32136). to determi ...200312566460
kinetics and strain specificity of rhizosphere and endophytic colonization by enteric bacteria on seedlings of medicago sativa and medicago truncatula.the presence of human-pathogenic, enteric bacteria on the surface and in the interior of raw produce is a significant health concern. several aspects of the biology of the interaction between these bacteria and alfalfa (medicago sativa) seedlings are addressed here. a collection of enteric bacteria associated with alfalfa sprout contaminations, along with escherichia coli k-12, salmonella enterica serotype typhimurium strain atcc 14028, and an endophyte of maize, klebsiella pneumoniae 342, were ...200312620870
a diffusible factor from arbuscular mycorrhizal fungi induces symbiosis-specific mtenod11 expression in roots of medicago truncatula.using dual cultures of arbuscular mycorrhizal (am) fungi and medicago truncatula separated by a physical barrier, we demonstrate that hyphae from germinating spores produce a diffusible factor that is perceived by roots in the absence of direct physical contact. this am factor elicits expression of the nod factor-inducible gene mtenod11, visualized using a pmtenod11-gusa reporter. transgene induction occurs primarily in the root cortex, with expression stretching from the zone of root hair emerg ...200312644648
molecular cloning and characterization of triterpene synthases from medicago truncatula and lotus japonicus.cloning of oscs required for triterpene synthesis from legume species that are amenable to molecular genetics will provide tools to address the importance of triterpenes and their derivatives during normal plant growth and development and also in interactions with symbionts and pathogens. here we report the cloning and characterization of a total of three triterpene synthases from the legume species medicago truncatula and lotus japonicus. these include a beta-amyrin synthase from m. truncatula ...200312683345
a novel family in medicago truncatula consisting of more than 300 nodule-specific genes coding for small, secreted polypeptides with conserved cysteine motifs.transcriptome analysis of medicago truncatula nodules has led to the discovery of a gene family named ncr (nodule-specific cysteine rich) with more than 300 members. the encoded polypeptides were short (60-90 amino acids), carried a conserved signal peptide, and, except for a conserved cysteine motif, displayed otherwise extensive sequence divergence. family members were found in pea (pisum sativum), broad bean (vicia faba), white clover (trifolium repens), and galega orientalis but not in other ...200312746522
expression of the plastid-located glutamine synthetase of medicago truncatula. accumulation of the precursor in root nodules reveals an in vivo control at the level of protein import into plastids.in this paper, we report the cloning and characterization of the plastid-located glutamine synthetase (gs) of medicago truncatula gaertn (mtgs2). a cdna was isolated encoding a gs2 precursor polypeptide of 428 amino acids composing an n-terminal transit peptide of 49 amino acids. expression analysis, by westerns and by northern hybridization, revealed that mtgs2 is expressed in both photosynthetic and non-photosynthetic organs. both transcripts and proteins of mtgs2 were detected in substantial ...200312746544
nod factor elicits two separable calcium responses in medicago truncatula root hair cells.modulation of intracellular calcium levels plays a key role in the transduction of many biological signals. here, we characterize early calcium responses of wild-type and mutant medicago truncatula plants to nodulation factors produced by the bacterial symbiont sinorhizobium meliloti using a dual-dye ratiometric imaging technique. when presented with 1 nm nod factor, root hair cells exhibited only the previously described calcium spiking response initiating 10 min after application. nod factor ( ...200312644650
identification and characterization of nodulation-signaling pathway 2, a gene of medicago truncatula involved in nod actor signaling.bacterially derived nod factor is critical in the establishment of the legume/rhizobia symbiosis. understanding the mechanisms of nod factor perception and signal transduction in the plant will greatly advance our understanding of this complex interaction. here, we describe the identification of a new locus, nodulation-signaling pathway 2 (nsp2), of medicago truncatula that is involved in nod factor signaling. mutants at this locus are blocked for nod factor-induced gene expression and show a re ...200312644655
efficient transposition of the tnt1 tobacco retrotransposon in the model legume medicago truncatula.the tobacco element, tnt1, is one of the few active retrotransposons in plants. its transposition is activated during protoplast culture in tobacco and tissue culture in the heterologous host arabidopsis thaliana. here, we report its transposition in the r108 line of medicago truncatula during the early steps of the in vitro transformation-regeneration process. two hundred and twenty-five primary transformants containing tnt1 were obtained. among them, 11.2% contained only transposed copies of t ...200312662312
estimates of conserved microsynteny among the genomes of glycine max, medicago truncatula and arabidopsis thaliana.a growing body of research indicates that microsynteny is common among dicot genomes. however, most studies focus on just one or a few genomic regions, so the extent of microsynteny across entire genomes remains poorly characterized. to estimate the level of microsynteny between medicago truncatula (mt) and glycine max (soybean), and also among homoeologous segments of soybean, we used a hybridization strategy involving bacterial artificial chromosome (bac) contigs. a mt bac library consisting o ...200312748777
a plasma membrane zinc transporter from medicago truncatula is up-regulated in roots by zn fertilization, yet down-regulated by arbuscular mycorrhizal colonization.here we present a zn transporter cdna named mtzip2 from the model legume medicago truncatula. mtzip2 encodes a putative 37 kda protein with 8-membrane spanning domains and has moderate amino acid identity with the arabidopsis thaliana zn transporter atzip2p. mtzip2 complemented a zn-uptake mutant of yeast implying that the protein encoded by this gene can transport zn across the yeast's plasma membrane. the product of a mtzip2-gfp fusion construct introduced into onion cells by particle bombardm ...200314558666
evolution and microsynteny of the apyrase gene family in three legume genomes.apyrases have been suggested to play important roles in plant nutrition, photomorphogenesis, and nodulation. to help trace the evolution of these genes in the legumes--and possibly, the acquisition of new functions for nodulation--apyrase-containing bacs were sequenced from three legume genomes. genomic sequences from medicago truncatula, glycine max and lotus japonicus were compared to one another and to corresponding regions in arabidopsis thaliana. a phylogenetic analysis of apyrase homologs ...200314598165
auxin up-regulates mtserk1 expression in both medicago truncatula root-forming and embryogenic cultures.we have cloned a somatic embryogenesis receptor kinase (serk) gene from medicago truncatula (mtserk1) and examined its expression in culture using real time pcr. in the presence of the auxin 1-naphthaleneacetic acid (naa) alone, root differentiation occurs from the proliferating calli in both the cultured highly embryogenic seed line (2ha) and a low to nonembryogenic seed line (m. truncatula cv jemalong). auxin stimulated mtserk1 expression in both 2ha and m. truncatula cv jemalong. embryo induc ...200312970488
mapping the proteome of barrel medic (medicago truncatula).a survey of six organ-/tissue-specific proteomes of the model legume barrel medic (medicago truncatula) was performed. two-dimensional polyacrylamide gel electrophoresis reference maps of protein extracts from leaves, stems, roots, flowers, seed pods, and cell suspension cultures were obtained. five hundred fifty-one proteins were excised and 304 proteins identified using peptide mass fingerprinting and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. nanoscale high- ...200312644662
a ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: gene identification by transcript-based cloning.in the establishment of the legume-rhizobial symbiosis, bacterial lipochitooligosaccharide signaling molecules termed nod factors activate the formation of a novel root organ, the nodule. nod factors elicit several responses in plant root hair cells, including oscillations in cytoplasmic calcium levels (termed calcium spiking) and alterations in root hair growth. a number of plant mutants with defects in the nod factor signaling pathway have been identified. one such medicago truncatula mutant, ...200415070781
two classes of the cdh1-type activators of the anaphase-promoting complex in plants: novel functional domains and distinct regulation.the cdc20 and cdh1/fzr proteins are the substrate-specific activators of the anaphase-promoting complex (apc). in medicago truncatula, the mtccs52a and mtccs52b proteins represent two subgroups of the cdh1-type activators, which display differences in their cell cycle regulation, structure, and function. the ccs52a transcripts are present in all phases of the cell cycle. by contrast, expression of ccs52b is restricted to late g2-phase and m-phase, and its induced overexpression in by2 cells inhi ...200414742878
mining est databases to resolve evolutionary events in major crop species.using plant est collections, we obtained 1392 potential gene duplicates across 8 plant species: zea mays, oryza sativa, sorghum bicolor, hordeum vulgare, solanum tuberosum, lycopersicon esculentum, medicago truncatula, and glycine max. we estimated the synonymous and nonsynonymous distances between each gene pair and identified two to three mixtures of normal distributions corresponding to one to three rounds of genome duplication in each species. within the poaceae, we found a conserved duplica ...200415499401
widespread paleopolyploidy in model plant species inferred from age distributions of duplicate genes.it is often anticipated that many of today's diploid plant species are in fact paleopolyploids. given that an ancient large-scale duplication will result in an excess of relatively old duplicated genes with similar ages, we analyzed the timing of duplication of pairs of paralogous genes in 14 model plant species. using est contigs (unigenes), we identified pairs of paralogous genes in each species and used the level of synonymous nucleotide substitution to estimate the relative ages of gene dupl ...200415208399
comparative physical mapping reveals features of microsynteny between glycine max, medicago truncatula, and arabidopsis thaliana.to gain insight into genomic relationships between soybean (glycine max) and medicago truncatula, eight groups of bacterial artificial chromosome (bac) contigs, together spanning 2.60 million base pairs (mb) in g. max and 1.56 mb in m. truncatula, were compared through high-resolution physical mapping combined with sequence and hybridization analysis of low-copy bac ends. cross-hybridization among g. max and m. truncatula contigs uncovered microsynteny in six of the contig groups and extensive m ...200415060611
anthocyanidin reductases from medicago truncatula and arabidopsis thaliana.anthocyanidin reductase (anr), encoded by the banyuls gene, is a newly discovered enzyme of the flavonoid pathway involved in the biosynthesis of condensed tannins. anr functions immediately downstream of anthocyanidin synthase to convert anthocyanidins into the corresponding 2,3-cis-flavan-3-ols. we report the biochemical properties of anrs from the model legume medicago truncatula (mtanr) and the model crucifer arabidopsis thaliana (atanr). both enzymes have high temperature optima. mtanr uses ...200414725861
characterization of soybean genomic features by analysis of its expressed sequence tags.we analyzed 314,254 soybean expressed sequence tags (ests), including 29,540 from our laboratory and 284,714 from genbank. these ests were assembled into 56,147 unigenes. about 76.92% of the unigenes were homologous to genes from arabidopsis thaliana ( arabidopsis). the putative products of these unigenes were annotated according to their homology with the categorized proteins of arabidopsis. genes corresponding to cell growth and/or maintenance, enzymes and cell communication belonged to the sl ...200414624337
estimating genome conservation between crop and model legume species.legumes are simultaneously one of the largest families of crop plants and a cornerstone in the biological nitrogen cycle. we combined molecular and phylogenetic analyses to evaluate genome conservation both within and between the two major clades of crop legumes. genetic mapping of orthologous genes identifies broad conservation of genome macrostructure, especially within the galegoid legumes, while also highlighting inferred chromosomal rearrangements that may underlie the variation in chromoso ...200415489274
rna interference in agrobacterium rhizogenes-transformed roots of arabidopsis and medicago truncatula.rna interference (rnai) is a powerful reverse genetic tool to study gene function. the data presented here show that agrobacterium rhizogenes-mediated rnai is a fast and effective tool to study genes involved in root biology. the arabidopsis gene kojak, involved in root hair development, was efficiently knocked down. a. rhizogenes-mediated root transformation is a fast method to generate adventitious, genetically transformed roots. in order to select for co-transformed roots a binary vector was ...200415073217
molecular and cell biology of a family of voltage-dependent anion channel porins in lotus japonicus.voltage-dependent anion channels (vdacs) are generally considered as the main pathway for metabolite transport across the mitochondrial outer membrane. recent proteomic studies on isolated symbiosome membranes from legume nodules indicated that vdacs might also be involved in transport of nutrients between plants and rhizobia. in an attempt to substantiate this, we carried out a detailed molecular and cellular characterization of vdacs in lotus japonicus and soybean (glycine max). database searc ...200414657408
plant and bacterial symbiotic mutants define three transcriptionally distinct stages in the development of the medicago truncatula/sinorhizobium meliloti symbiosis.in the medicago truncatula/sinorhizobium meliloti symbiosis, the plant undergoes a series of developmental changes simultaneously, creating a root nodule and allowing bacterial entry and differentiation. our studies of plant genes reveal novel transcriptional regulation during the establishment of the symbiosis and identify molecular markers that distinguish classes of plant and bacterial symbiotic mutants. we have identified three symbiotically regulated plant genes encoding a beta,1-3 endogluc ...200414739349
biochemical characterization of symbiosome membrane proteins from medicago truncatula root nodules.the symbiosome membrane represents a specialized plant membrane that forms both a structural and a functional interface between the legume plant and its bacterial counterpart. in this study, the symbiosome membrane protein profile from the model system medicago truncatula and the corresponding bacterium sinorhizobium meliloti was examined using two-dimensional electrophoresis and microcapillary high-performance liquid chromatography (hplc) tandem mass spectrometry. the identities of 51 proteins ...200414760646
a putative ca2+ and calmodulin-dependent protein kinase required for bacterial and fungal symbioses.legumes can enter into symbiotic relationships with both nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. nodulation by rhizobia results from a signal transduction pathway induced in legume roots by rhizobial nod factors. dmi3, a medicago truncatula gene that acts immediately downstream of calcium spiking in this signaling pathway and is required for both nodulation and mycorrhizal infection, has high sequence similarity to genes encoding calcium and calmodulin-dependent protein kinase ...200414963335
molecular and biochemical analysis of two cdna clones encoding dihydroflavonol-4-reductase from medicago truncatula.dihydroflavonol-4-reductase (dfr; ec1.1.1.219) catalyzes a key step late in the biosynthesis of anthocyanins, condensed tannins (proanthocyanidins), and other flavonoids important to plant survival and human nutrition. two dfr cdna clones (mtdfr1 and mtdfr2) were isolated from the model legume medicago truncatula cv jemalong. both clones were functionally expressed in escherichia coli, confirming that both encode active dfr proteins that readily reduce taxifolin (dihydroquercetin) to leucocyanid ...200414976232
nip, a symbiotic medicago truncatula mutant that forms root nodules with aberrant infection threads and plant defense-like response.to investigate the legume-rhizobium symbiosis, we isolated and studied a novel symbiotic mutant of the model legume medicago truncatula, designated nip (numerous infections and polyphenolics). when grown on nitrogen-free media in the presence of the compatible bacterium sinorhizobium meliloti, the nip mutant showed nitrogen deficiency symptoms. the mutant failed to form pink nitrogen-fixing nodules that occur in the wild-type symbiosis, but instead developed small bump-like nodules on its roots ...200415516506
the promoter of the vicia faba l. leghemoglobin gene vflb29 is specifically activated in the infected cells of root nodules and in the arbuscule-containing cells of mycorrhizal roots from different legume and nonlegume plants.the vflb29 leghemoglobin gene promoter was polymerase chain reaction-amplified from a vicia faba genomic library and was fused to the gusaint coding region. expression of the chimeric gene was analyzed in transgenic hairy roots of the legumes v. faba, v. hirsuta, and medicago truncatula as well as in transgenic nicotiana tabacum plants. the vflb29 promoter was found to be specifically active not only in the infected cells of the nitrogen-fixing zone of root nodules but also in arbuscule-containi ...200414714869
an auxin-inducible gene from loblolly pine (pinus taeda l.) is differentially expressed in mature and juvenile-phase shoots and encodes a putative transmembrane protein.we have isolated a gene from loblolly pine, 5ng4, that is highly and specifically induced by auxin in juvenile loblolly pine shoots prior to adventitious root formation, but substantially down-regulated in physiologically mature shoots that are adventitious rooting incompetent. 5ng4 was highly auxin-induced in roots, stems and hypocotyls, organs that can form either lateral or adventitious roots following an auxin treatment, but was not induced to the same level in needles and cotyledons, organs ...200414722770
isolation and characterization of the early nodule-specific protein homologue (hev b 13), an allergenic lipolytic esterase from hevea brasiliensis latex.recurring reports of a highly allergenic 42-46-kda protein in hevea brasiliensis latex appeared to have been resolved with the discovery of a 43-kda allergenic latex protein that was a homologue to patatin. however, the low to moderate prevalence of sensitization to the protein, designated hev b 7, among latex-allergic patients could not adequately explain the frequent observations of the 42-46-kda allergen. this led to the hypothesis that another, more allergenic protein of a similar molecular ...200415024009
pharmacological evidence that multiple phospholipid signaling pathways link rhizobium nodulation factor perception in medicago truncatula root hairs to intracellular responses, including ca2+ spiking and specific enod gene expression.rhizobium nodulation (nod) factors are specific lipochito-oligosaccharide signals essential for initiating in root hairs of the host legume developmental responses that are required for controlled entry of the microsymbiont. in this article, we focus on the nod factor signal transduction pathway leading to specific and cell autonomous gene activation in medicago truncatula cv jemalong in a study making use of the nod factor-inducible mtenod11 gene. first, we show that pharmacological antagonists ...200415489277
the typa gene is required for stress adaptation as well as for symbiosis of sinorhizobium meliloti 1021 with certain medicago truncatula lines.in this article, we describe the typa gene of sinorhizobium meliloti, the orthologue of typa/bipa genes found in a wide range of bacteria. we found that typa was required for survival of s. meliloti under certain stress conditions, such as growth at low temperature or low ph and in the presence of sodium dodecyl sulfate (sds). the cold-sensitive phenotype of both escherichia coli bipa and s. meliloti typa mutants were cross-complemented, indicating that the two genes are functionally equivalent. ...200415000390
enod40, a short open reading frame-containing mrna, induces cytoplasmic localization of a nuclear rna binding protein in medicago truncatula.in eukaryotes, diverse mrnas containing only short open reading frames (sorf-mrnas) are induced at specific stages of development. their mechanisms of action may involve the rna itself and/or sorf-encoded oligopeptides. enod40 genes code for highly structured plant sorf-mrnas involved in root nodule organogenesis. a novel rna binding protein interacting with the enod40 rna, mtrbp1 (for medicago truncatula rna binding protein 1), was identified using a yeast three-hybrid screening. immunolocaliza ...200415037734
a natural variant of a host rna-dependent rna polymerase is associated with increased susceptibility to viruses by nicotiana benthamiana.nicotiana benthamiana often displays more intense symptoms after infection by rna viruses than do other nicotiana species. here, we examined the role of rna-dependent rna polymerases (rdrps) in n. benthamiana antiviral defense. cdnas representing only two genes encoding rdrps were identified in n. benthamiana. one rdrp was similar in sequence to sde1/sgs2 required for maintenance of transgene silencing, whereas the second, named nbrdrp1m, was >90% identical in sequence to the salicylic acid (sa) ...200415079073
sinorhizobium meliloti-induced chitinase gene expression in medicago truncatula ecotype r108-1: a comparison between symbiosis-specific class v and defence-related class iv chitinases.the medicago truncatula (gaertn.) ecotypes jemalong a17 and r108-1 differ in sinorhizobium meliloti-induced chitinase gene expression. the pathogen-inducible class iv chitinase gene, mtchit 4, was strongly induced during nodule formation of the ecotype jemalong a17 with the s. meliloti wild-type strain 1021. in the ecotype r108-1, the s. meliloti wild types sm1021 and sm41 did not induce mtchit 4 expression. on the other hand, expression of the putative class v chitinase gene, mtchit 5, was foun ...200415107993
construction and validation of cdna-based mt6k-rit macro- and microarrays to explore root endosymbioses in the model legume medicago truncatula.to construct macro- and microarray tools suitable for expression profiling in root endosymbioses of the model legume medicago truncatula, we pcr-amplified a total of 6048 cdna probes representing genes expressed in uninfected roots, mycorrhizal roots and young root nodules [nucleic acids res. 30 (2002) 5579]. including additional probes for either tissue-specific or constitutively expressed control genes, 5651 successfully amplified gene-specific probes were used to grid macro- and to spot micro ...200415129719
six nonnodulating plant mutants defective for nod factor-induced transcriptional changes associated with the legume-rhizobia symbiosis.as the legume-rhizobia symbiosis is established, the plant recognizes bacterial-signaling molecules, nod factors (nfs), and initiates transcriptional and developmental changes within the root to allow bacterial invasion and the construction of a novel organ, the nodule. plant mutants defective in nodule initiation (nod(-)) are thought to have defects in nf-signal transduction. however, it is unknown whether wt plants respond to nf-independent bacterial-derived signals or whether nod(-) plant mut ...200415220482
cytological, genetic, and molecular analysis to characterize compatible and incompatible interactions between medicago truncatula and colletotrichum trifolii.in this study, a new pathosystem was established using the model plant medicago truncatula and colletotrichum trifolii, the causal agent of anthracnose on medicago sativa. screening of a few m. truncatula lines identified jemalong and f83005.5 as resistant and susceptible to colletotrichum trifolii race 1, respectively. symptom analysis and cytological studies indicated that resistance of jemalong was associated with a hypersensitive response of the plant. the two selected lines were crossed, an ...200415305612
comprehensive metabolite profiling of sinorhizobium meliloti using gas chromatography-mass spectrometry.a metabolite analysis of the soil bacterium sinorhizobium meliloti was established as a first step towards a better understanding of the symbiosis with its host plant medicago truncatula. a crucial step was the development of fast harvesting and extraction methods for the bacterial metabolites because of rapid changes in their composition. s. meliloti 1021 cell cultures grown in minimal medium were harvested by centrifugation, filtration or immediate freezing in liquid nitrogen followed by a lyo ...200415372312
infection-related activation of the cg12 promoter is conserved between actinorhizal and legume-rhizobia root nodule symbiosis.two nitrogen-fixing root nodule symbioses between soil bacteria and higher plants have been described: the symbiosis between legume and rhizobia and actinorhizal symbioses between plants belonging to eight angiosperm families and the actinomycete frankia. we have recently shown that the subtilisin-like ser protease gene cg12 (isolated from the actinorhizal plant casuarina glauca) is specifically expressed during plant cell infection by frankia. here we report on the study of c. glauca cg12 promo ...200415466224
expression profiling in medicago truncatula identifies more than 750 genes differentially expressed during nodulation, including many potential regulators of the symbiotic program.in this study, we describe a large-scale expression-profiling approach to identify genes differentially regulated during the symbiotic interaction between the model legume medicago truncatula and the nitrogen-fixing bacterium sinorhizobium meliloti. macro- and microarrays containing about 6,000 probes were generated on the basis of three cdna libraries dedicated to the study of root symbiotic interactions. the experiments performed on wild-type and symbiotic mutant material led us to identify a ...200415466239
a nonsymbiotic root hair tip growth phenotype in nork-mutated legumes: implications for nodulation factor-induced signaling and formation of a multifaceted root hair pocket for bacteria.the medicago truncatula does not make infections (dmi2) mutant is mutated in the nodulation receptor-like kinase, nork. here, we report that nork-mutated legumes of three species show an enhanced touch response to experimental handling, which results in a nonsymbiotic root hair phenotype. when care is taken not to induce this response, dmi2 root hairs respond morphologically like the wild type to nodulation factor (nf). global nf application results in root hair deformation, and nf spot applicat ...200415031407
sinorhizobium meliloti metabolism in the root nodule: a proteomic perspective.the proteome of the model symbiotic bacterium, sinorhizobium meliloti was examined to determine the enzymatic reactions and cell processes that occur when s. meliloti occupies the root nodules of medicago truncatula and melilotus alba. the proteomes of the nodule bacteria were compared to that of s. meliloti grown under laboratory cultured conditions as an additional control. all the detectable protein spots on the two-dimensional (2-d) gels between ph 4-7 were analyzed. in total, the identity o ...200415221743
impact of sewage sludges on medicago truncatula symbiotic proteome.the effects of sewage sludges were investigated on the symbiotic interactions between the model plant medicago truncatula and the arbuscular mycorrhizal fungus glomus mosseae or the rhizobial bacteria sinorhizobium meliloti. by comparison to a control sludge showing positive effects on plant growth and root symbioses, sludges enriched with polycylic aromatic hydrocarbons or heavy metals were deleterious. symbiosis-related proteins were detected and identified by two-dimensional electrophoresis a ...200415276460
resistance of glycine species and various cultivated legumes to the soybean aphid (homoptera: aphididae).the soybean aphid, aphis glycines matsumura, is a new pest of soybean, glycine max (l.) merr., in north america. it has become widespread on soybean in north america since it was first identified in the midwest in 2000. species of rhamnus l. (buckthorn) are the primary hosts of a. glycines, and soybean is known as a secondary host. there is limited information about the secondary host range of a. glycines. aphid colonization on various legume hosts was compared in choice experiments. aphid colon ...200415279293
identification and characterization of several new members of the zip family of metal ion transporters in medicago truncatula.to broaden our understanding of micronutrient metal transport in plants, we have identified cdnas for six new metal transporters in the model legume medicago truncatula. all of the predicted proteins have high similarity to the zip protein family, and have been designated mtzip1, mtzip3, mtzip4, mtzip5, mtzip6, and mtzip7. the six predicted proteins ranged from 350 to 372 amino acids in length; sequence analysis revealed that all proteins contained eight transmembrane domains and the highly cons ...200415316291
microbial products trigger amino acid exudation from plant roots.plants naturally cycle amino acids across root cell plasma membranes, and any net efflux is termed exudation. the dominant ecological view is that microorganisms and roots passively compete for amino acids in the soil solution, yet the innate capacity of roots to recover amino acids present in ecologically relevant concentrations is unknown. we find that, in the absence of culturable microorganisms, the influx rates of 16 amino acids (each supplied at 2.5 microm) exceed efflux rates by 5% to 545 ...200415347793
nod factor-treated medicago truncatula roots and seeds show an increased number of nodules when inoculated with a limiting population of sinorhizobium meliloti.medicago truncatula is a model legume plant that interacts symbiotically with sinorhizobium meliloti, the alfalfa symbiont. this process involves a molecular dialogue between the bacterium and the plant. legume roots exude flavonoids that induce the expression of a set of rhizobial genes, the nod genes, which are essential for nodulation and determination of the host range. in turn, nod genes control the synthesis of lipo-chito-oligosaccharides (lcos), nod factors, which are bacteria-to-plant si ...200415361530
differential antifungal and calcium channel-blocking activity among structurally related plant defensins.plant defensins are a family of small cys-rich antifungal proteins that play important roles in plant defense against invading fungi. structures of several plant defensins share a cys-stabilized alpha/beta-motif. structural determinants in plant defensins that govern their antifungal activity and the mechanisms by which they inhibit fungal growth remain unclear. alfalfa (medicago sativa) seed defensin, msdef1, strongly inhibits the growth of fusarium graminearum in vitro, and its antifungal acti ...200415299136
phytohormonal responses in enod40-overexpressing plants of medicago truncatula and rice.phytohormones are well-known regulators of the symbiotic rhizobium-legume association in the plant host. the enod40 nodulin gene is associated with the earliest phases of the nodule organogenesis programme in the legume host and modifying its expression resulted in perturbations of nodule development in medicago truncatula. therefore in our pursuit to mimic the initial signal transduction steps of legume nodulation in the alien physiological set-up of a rice plant, we have expressed the mtenod40 ...200415032885
lin, a medicago truncatula gene required for nodule differentiation and persistence of rhizobial infections.ethyl methanesulfonate mutagenesis of the model legume medicago truncatula has previously identified several genes required for early steps in nodulation. here, we describe a new mutant that is defective in intermediate steps of nodule differentiation. the lin (lumpy infections) mutant is characterized by a 4-fold reduction in the number of infections, all of which arrest in the root epidermis, and by nodule primordia that initiate normally but fail to mature. genetic analyses indicate that the ...200415516512
a dual-genome symbiosis chip for coordinate study of signal exchange and development in a prokaryote-host interaction.the soil-dwelling alpha-proteobacterium sinorhizobium meliloti engages in a symbiosis with legumes: s. meliloti elicits the formation of plant root nodules where it converts dinitrogen to ammonia for use by the plant in exchange for plant photosynthate. to study the coordinate differentiation of s. meliloti and its legume partner during nodule development, we designed a custom affymetrix genechip with the complete s. meliloti genome and approximately 10,000 probe sets for the plant host, medicag ...200415542588
the symbiotic defect in a sinorhizobium meliloti lipopolysaccharide mutant can be overcome by expression of other surface polysaccharides.in this work we have examined the extent of functional complementation in symbiosis among different sinorhizobium meliloti surface polysaccharides including lipopolysaccharide (lps). we show that a symbiotic deficiency associated with an lps defect can be reversed by appropriate expression of other surface polysaccharides such as galactoglucan (epsii) and a particular form of capsular polysaccharide (kdops). it is noteworthy that, while succinoglycan epsi and lps cannot functionally substitute f ...200415567281
effect of salinity on root-nodule conductance to the oxygen diffusion in the medicago truncatula-sinorhizobium meliloti symbiosis.in order to determine the effect of salinity on the nodule conductance, oxygen uptake by the nodulated roots was measured by registering the concentration of o(2) as a function of time in a tight incubator of known volume containing the nodulated roots of medicago truncatula. four lines, namely tn8.20 and tn6.18, originated from local populations, f83005.5 originated from var (france) and jemalong 6, a cultivar from australia, were hydroponically grown in 250 ml glass bottles under semi-controll ...200415596103
metabolic profiling of medicago truncatula cell cultures reveals the effects of biotic and abiotic elicitors on metabolism.gc-ms-based metabolite profiling was used to analyse the response of medicago truncatula cell cultures to elicitation with methyl jasmonate (meja), yeast elicitor (ye), or ultraviolet light (uv). marked changes in the levels of primary metabolites, including several amino acids, organic acids, and carbohydrates, were observed following elicitation with meja. a similar, but attenuated response was observed following ye elicitation, whereas little response was observed following uv elicitation. me ...200415596476
fungal elicitation of signal transduction-related plant genes precedes mycorrhiza establishment and requires the dmi3 gene in medicago truncatula.suppressive subtractive hybridization and expressed sequence tag sequencing identified 29 plant genes which are upregulated during the appressorium stage of mycorrhiza establishment between medicago truncatula j5 (myc+) and glomus mosseae. eleven genes coding plant proteins with predicted functions in signal transduction, transcription, and translation were investigated in more detail for their relation to early events of symbiotic interactions. expression profiling showed that the genes are act ...200415597744
proteomic approach: identification of medicago truncatula proteins induced in roots after infection with the pathogenic oomycete aphanomyces euteiches.the legume root rot disease caused by the oomycete pathogen aphanomyces euteiches is one major yield reducing factor in legume crop production. a comparative proteomic approach was carried out in order to identify proteins of the model legume medicago truncatula which are regulated after an infection with a. euteiches . several proteins were identified by two dimensional gel electrophoresis to be differentially expressed after pathogen challenge. densitometric evaluation of expression values sho ...200415604668
methyl jasmonate and yeast elicitor induce differential transcriptional and metabolic re-programming in cell suspension cultures of the model legume medicago truncatula.exposure of cell suspension cultures of medicago truncatula gaerth. to methyl jasmonate (meja) resulted in up to 50-fold induction of transcripts encoding the key triterpene biosynthetic enzyme beta-amyrin synthase (betaas; ec 5.4.99.-). transcripts reached maximum levels at 24 h post-elicitation with 0.5 mm meja. the entry point enzymes into the phenylpropanoid and flavonoid pathways, l: -phenylalanine ammonia-lyase (pal; ec 4.3.1.5) and chalcone synthase (chs; ec 2.3.1.74), respectively, were ...200415605242
computational identification and characterization of novel genes from legumes.the fabaceae, the third largest family of plants and the source of many crops, has been the target of many genomic studies. currently, only the grasses surpass the legumes for the number of publicly available expressed sequence tags (ests). the quantity of sequences from diverse plants enables the use of computational approaches to identify novel genes in specific taxa. we used blast algorithms to compare unigene sets from medicago truncatula, lotus japonicus, and soybean (glycine max and glycin ...200415266052
use of the fluorescent timer dsred-e5 as reporter to monitor dynamics of gene activity in plants.fluorescent proteins, such as green fluorescent protein and red fluorescent protein (dsred), have become frequently used reporters in plant biology. however, their potential to monitor dynamic gene regulation is limited by their high stability. the recently made dsred-e5 variant overcame this problem. dsred-e5 changes its emission spectrum over time from green to red in a concentration independent manner. therefore, the green to red fluorescence ratio indicates the age of the protein and can be ...200415326279
rna interference identifies a calcium-dependent protein kinase involved in medicago truncatula root development.changes in cellular or subcellular ca2+ concentrations play essential roles in plant development and in the responses of plants to their environment. however, the mechanisms through which ca2+ acts, the downstream signaling components, as well as the relationships among the various ca2+-dependent processes remain largely unknown. using an rna interference-based screen for gene function in medicago truncatula, we identified a gene that is involved in root development. silencing ca2+-dependent pro ...200516199614
overlaps in the transcriptional profiles of medicago truncatula roots inoculated with two different glomus fungi provide insights into the genetic program activated during arbuscular mycorrhiza.arbuscular mycorrhiza (am) is a widespread symbiotic association between plants and fungal microsymbionts that supports plant development under nutrient-limiting and various stress conditions. in this study, we focused on the overlapping genetic program activated by two commonly studied microsymbionts in addition to identifying am-related genes. we thus applied 16,086 probe microarrays to profile the transcriptome of the model legume medicago truncatula during interactions with glomus mosseae an ...200515778460
lotus japonicus metabolic profiling. development of gas chromatography-mass spectrometry resources for the study of plant-microbe interactions.symbiotic nitrogen fixation (snf) in legume root nodules requires differentiation and integration of both plant and bacterial metabolism. classical approaches of biochemistry, molecular biology, and genetics have revealed many aspects of primary metabolism in legume nodules that underpin snf. functional genomics approaches, especially transcriptomics and proteomics, are beginning to provide a more holistic picture of the metabolic potential of nodules in model legumes like medicago truncatula an ...200515749991
expression of the medicago truncatula dm12 gene suggests roles of the symbiotic nodulation receptor kinase in nodules and during early nodule development.the medicago truncatula dmi2 gene encodes a receptorlike kinase required for establishing root endosymbioses. the dmi2 gene was shown to be expressed much more highly in roots and nodules than in leaves and stems. in roots, its expression was not altered by nitrogen starvation or treatment with lipochitooligosaccharidic nod factors. moreover, the dmi2 mrna abundance in roots of the nfp, dmil, dmi3, nsp1, nsp2, and hcl symbiotic mutants was similar to the wild type, whereas lower levels in some d ...200516134899
the mycorrhizal fungus gigaspora margarita possesses a cuzn superoxide dismutase that is up-regulated during symbiosis with legume hosts.a full-length cdna showing high similarity to previously described cuzn superoxide dismutases (sods) was identified in an expressed sequence tag collection from germinated spores of the arbuscular mycorrhizal fungus gigaspora margarita (beg 34). the corresponding gene sequence, named gmarcuznsod, is composed of four exons. as revealed by heterologous complementation assays in a yeast mutant, gmarcuznsod encodes a functional polypeptide able to confer increased tolerance to oxidative stress. the ...200515749992
pseudomonas fluorescens and glomus mosseae trigger dmi3-dependent activation of genes related to a signal transduction pathway in roots of medicago truncatula.plant genes induced during early root colonization of medicago truncatula gaertn. j5 by a growth-promoting strain of pseudomonas fluorescens (c7r12) have been identified by suppressive subtractive hybridization. ten m. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between m. truncatula and p. fluorescens, up to 8 d after root inoculation. gene expression was not significantly enhanced ...200516183836
invasion of lotus japonicus root hairless 1 by mesorhizobium loti involves the nodulation factor-dependent induction of root hairs.in many legumes, including lotus japonicus and medicago truncatula, susceptible root hairs are the primary sites for the initial signal perception and physical contact between the host plant and the compatible nitrogen-fixing bacteria that leads to the initiation of root invasion and nodule organogenesis. however, diverse mechanisms of nodulation have been described in a variety of legume species that do not rely on root hairs. to clarify the significance of root hairs during the l. japonicus-me ...200515778455
grafting between model legumes demonstrates roles for roots and shoots in determining nodule type and host/rhizobia specificity.previous grafting experiments have demonstrated that legume shoots play a critical role in symbiotic development of nitrogen-fixing root nodules by regulating nodule number. here, reciprocal grafting experiments between the model legumes lotus japonicus and medicago truncatula were carried out to investigate the role of the shoot in the host-specificity of legume-rhizobia symbiosis and nodule type. lotus japonicus is nodulated by mesorhizobium loti and makes determinate nodules, whereas m. trunc ...200515824071
the lipid a substructure of the sinorhizobium meliloti lipopolysaccharides is sufficient to suppress the oxidative burst in host plants.medicago sativa (alfalfa), medicago truncatula and nicotiana tabacum cell suspension cultures, responding to elicitation with the production of reactive oxygen species (ros), were used to analyse the suppressor (and elicitor) activity of lipopolysaccharides (lps) of the symbiotic soil bacterium sinorhizobium meliloti. in order to identify the epitopes of the lps molecule recognized by the plant, s. meliloti mutants defective in lps biosynthesis and hydrolytically obtained lipid a were analysed f ...200515720666
glutathione and homoglutathione play a critical role in the nodulation process of medicago truncatula.legumes form a symbiotic interaction with bacteria of the rhizobiaceae family to produce nitrogen-fixing root nodules under nitrogen-limiting conditions. this process involves the recognition of the bacterial nod factors by the plant which mediates the entry of the bacteria into the root and nodule organogenesis. we have examined the importance of the low molecular weight thiols, glutathione (gsh) and homoglutathione (hgsh), during the nodulation process in the model legume medicago truncatula. ...200515782639
a kunitz trypsin inhibitor from chickpea (cicer arietinum l.) that exerts anti-metabolic effect on podborer (helicoverpa armigera) larvae.chickpea (cicer arietinum l.) seeds contain bowman-birk proteinase inhibitors, which are ineffective against the digestive proteinases of larvae of the insect pest helicoverpa armigera. we have identified and purified a low expressing proteinase inhibitor (pi), distinct from the bowman-birk inhibitors and active against h. armigera gut proteinases (hgp), from chickpea seeds. n-terminal sequencing of this hgp inhibitor revealed a sequence similar to reported pea (pisum sativum) and chickpea alpha ...200515830127
arbuscular mycorrhizal fungi elicit a novel intracellular apparatus in medicago truncatula root epidermal cells before infection.the penetration of arbuscular mycorrhizal (am) fungi through the outermost root tissues of the host plant is a critical step in root colonization, ultimately leading to the establishment of this ecologically important endosymbiotic association. to evaluate the role played by the host plant during am infection, we have studied in vivo cellular dynamics within medicago truncatula root epidermal cells using green fluorescent protein labeling of both the plant cytoskeleton and the endoplasmic reticu ...200516284314
molecular cloning and characterisation of a rab-binding gdp-dissociation inhibitor from medicago truncatula.we have isolated and sequenced the full-length cdna of a gdp-dissociation inhibitor (gdi) from the model legume medicago truncatula l. the cdna (mtgdi) contains an open reading frame of 1335 bp, coding for a protein of 444 amino acids with a calculated molecular mass of 49,785 kda. the deduced amino acid sequence shows significant homology to other plant gdis, the highest homology being found to gdi from the legume cicer arietinum (96% identity). the mtgdi was expressed as a n-terminal flag-fusi ...200515854828
accumulation of reactive oxygen species in arbuscular mycorrhizal roots.we investigated the accumulation of reactive oxygen species (ros) in arbuscular mycorrhizal (am) roots from medicago truncatula, zea mays and nicotiana tabacum using three independent staining techniques. colonized root cortical cells and the symbiotic fungal partner were observed to be involved in the production of ros. extraradical hyphae and spores from glomus intraradices accumulated small levels of ros within their cell wall and produced ros within the cytoplasm in response to stress. withi ...200515875223
insertional mutagenesis: a swiss army knife for functional genomics of medicago truncatula.legumes are second only to grasses in worldwide economic importance, and understanding their molecular genetics is vital to the breeding of important grain and forage legumes. over the past decade, medicago truncatula has been selected as a model plant in which to study biological processes that are unique and pertinent to legumes, and that cannot easily be studied in arabidopsis. here, we discuss the most common tools for introducing and analyzing genetic mutations in m. truncatula. because tra ...200515882655
munich information center for protein sequences plant genome resources: a framework for integrative and comparative analyses 1(w).with several plant genomes sequenced, the power of comparative genome analysis can now be applied. however, genome-scale cross-species analyses are limited by the effort for data integration. to develop an integrated cross-species plant genome resource, we maintain comprehensive databases for model plant genomes, including arabidopsis (arabidopsis thaliana), maize (zea mays), medicago truncatula, and rice (oryza sativa). integration of data and resources is emphasized, both in house as well as w ...200516010004
characterisation of new symbiotic medicago truncatula (gaertn.) mutants, and phenotypic or genotypic complementary information on previously described mutants.from a pool of medicago truncatula mutants--obtained by gamma-irradiation or ethyl methanesulfonate mutagenesis--impaired in symbiosis with the n-fixing bacterium sinorhizobium meliloti, new mutants are described and genetically analysed, and for already reported mutants, complementary data are given on their phenotypic and genetic analysis. phenotypic data relate to nodulation and mycorrhizal phenotypes. among the five new mutants, three were classified as [nod+ fix- myc+] and the mutations wer ...200515558330
defensin gene family in medicago truncatula: structure, expression and induction by signal molecules.a large gene family encoding the putative cysteine-rich defensins was discovered in medicago truncatula. sixteen members of the family were identified by screening a cloned seed defensin from m. sativa (gao et al. 2000) against the institute for genomic research's (tigr) m. truncatula gene index (mtgi version 7). based on the comparison of their amino acid sequences, m. truncatula defensins fell arbitrarily into three classes displaying extensive sequence divergence outside of the eight canonica ...200516021402
nod factor signaling genes and their function in the early stages of rhizobium infection.a lipochitosaccharide-based signal molecule that is secreted by rhizobium, named nod factor (nf), induces root nodule formation in legumes. this molecule is also essential for the establishment of bacterial infection. genetic analyses in the legume species lotus japonicus and medicago truncatula have led to the identification of many components of the nf signaling cascade. at least three of these genes do not function exclusively in the rhizobium symbiosis but are also essential for the formatio ...200515955723
mtenod11 gene activation during rhizobial infection and mycorrhizal arbuscule development requires a common at-rich-containing regulatory sequence.the mtenod11 gene from the model legume medicago truncatula is transcriptionally activated both in response to sinorhizobium meliloti nod factors and throughout infection of root tissues by the nitrogen-fixing microsymbiont. to identify the regulatory sequences involved in symbiosis-related mtenod11 expression, a series of promoter deletions driving the beta-glucuronidase reporter gene were analyzed in transgenic m. truncatula roots. these studies have revealed that distinct regulatory regions a ...200516478046
nodulation signaling in legumes requires nsp2, a member of the gras family of transcriptional regulators.rhizobial bacteria enter a symbiotic interaction with legumes, activating diverse responses in roots through the lipochito oligosaccharide signaling molecule nod factor. here, we show that nsp2 from medicago truncatula encodes a gras protein essential for nod-factor signaling. nsp2 functions downstream of nod-factor-induced calcium spiking and a calcium/calmodulin-dependent protein kinase. we show that nsp2-gfp expressed from a constitutive promoter is localized to the endoplasmic reticulum/nucl ...200515961668
soil nematodes mediate positive interactions between legume plants and rhizobium bacteria.symbiosis between legume species and rhizobia results in the sequestration of atmospheric nitrogen into ammonium, and the early mechanisms involved in this symbiosis have become a model for plant-microbe interactions and thus highly amenable for agricultural applications. the working model for this interaction states that the symbiosis is the outcome of a chemical/molecular dialogue initiated by flavonoids produced by the roots of legumes and released into the soil as exudates, which specificall ...200516025342
ectopic expression of the mycorrhiza-specific chitinase gene mtchit 3-3 in medicago truncatula root-organ cultures stimulates spore germination of glomalean fungi.expression of mtchit 3-3, a class iii chitinase gene, is specifically induced by arbuscular mycorrhizal (am) fungi in roots of the model legume medicago truncatula and its transcripts accumulate in cells containing arbuscules. agrobacterium rhizogenes-transformed roots and root-organ cultures of m. truncatula were used to study effects of mtchit 3-3 on am fungi. * this work provides evidence for enzymatic activity of the mtchit 3-3 gene product and shows with promoter:gus fusions that a 2 kb fra ...200515998406
formation of organelle-like n2-fixing symbiosomes in legume root nodules is controlled by dmi2.in most legume nodules, the n2-fixing rhizobia are present as organelle-like structures inside their host cells. these structures, named symbiosomes, contain one or a few rhizobia surrounded by a plant membrane. symbiosome formation requires the release of bacteria from cell-wall-bound infection threads. in primitive legumes, rhizobia are hosted in intracellular infection threads that, in contrast to symbiosomes, are bound by a cell wall. the formation of symbiosomes is presumed to represent a m ...200516006515
metabolic engineering of isoflavonoid biosynthesis in alfalfa.the potential health benefits of dietary isoflavones have generated considerable interest in engineering the synthesis of these phytoestrogens into plants. genistein glucoside production (up to 50 nmol g(-1) fresh weight) was engineered in alfalfa (medicago sativa) leaves by constitutive expression of isoflavone synthase from medicago truncatula (mtifs1). glucosides of biochanin a (4'-o-methylgenistein) and pratensein (3'-hydroxybiochanin a) also accumulated. although mtifs1 was highly expressed ...200516006598
expression of a xyloglucan endotransglucosylase/hydrolase gene, mt-xth1, from medicago truncatula is induced systemically in mycorrhizal roots.xyloglucan endotransglucosylase/hydrolases (xth) are enzymes that catalyze the hydrolysis and transglycosylation of xyloglucan polymers in plant cell walls. previously, we isolated a cdna from mycorrhizal roots of medicago truncatula that is predicted to encode an xth [van buuren, m.l., maldonado-mendoza, i.e., trieu, a.t., blaylock, l.a., harrison, m.j., 1999. novel genes induced during an arbuscular mycorrhizal (am) symbiosis between m. truncatula and g. versiforme. mol. plant-microb. interact ...200515716119
the latd gene of medicago truncatula is required for both nodule and root development.the evolutionary origins of legume root nodules are largely unknown. we have identified a gene, latd, of the model legume medicago truncatula, that is required for both nodule and root development, suggesting that these two developmental processes may share a common evolutionary origin. the latd mutant plants initiate nodule formation but do not complete it, resulting in immature, non-nitrogen-fixing nodules. similarly, lateral roots initiate, but remain short stumps. the primary root, which ini ...200515986921
plants as bioreactors: a comparative study suggests that medicago truncatula is a promising production system.plants are emerging as a promising alternative to conventional platforms for the large-scale production of recombinant proteins. this field of research, known as molecular farming, is developing rapidly and several plant-derived recombinant proteins are already in advanced clinical trials. however, the full potential of molecular farming can only be realized if we gain a fundamental understanding of biological processes regulating the production and accumulation of functional recombinant protein ...200516026877
guab activity is required in rhizobium tropici during the early stages of nodulation of determinate nodules but is dispensable for the sinorhizobium meliloti-alfalfa symbiotic interaction.the guab mutant strain rhizobium tropici ciat8999-10t is defective in symbiosis with common bean, forming nodules that lack rhizobial content. in order to investigate the timing of the guab requirement during the nodule formation on the host common bean by the strain ciat899-10.t, we constructed gene fusions in which the guab gene is expressed under the control of the symbiotic promoters noda, baca, and nifh. our data indicated that the guab is required from the early stages of nodulation becaus ...200516042020
transcript enrichment of nod factor-elicited early nodulin genes in purified root hair fractions of the model legume medicago truncatula.this article describes an efficient procedure to study nod factor-induced gene expression in root hairs of the model legume medicago truncatula. by developing an improved method of fracturing frozen root hairs, it has been possible to obtain a highly purified root hair fraction from m. truncatula seedlings yielding sufficient rna for real-time quantitative rt-pcr expression analysis. after nod factor treatment it was possible to detect up to 100-fold increases of mtenod11 and pmtenod11-gus trans ...200516043451
identification of a large cluster of coiled coil-nucleotide binding site--leucine rich repeat-type genes from the rps1 region containing phytophthora resistance genes in soybean.fifteen rps genes confer resistance against the oomycete pathogen phytophthora sojae, which causes root and stem rot disease in soybean. we have isolated a disease resistance gene-like sequence from the genomic region containing rps1-k. four classes of cdna of the sequence were isolated from etiolated hypocotyl tissues that express the rps1-k-encoded phytophthora resistance. sequence analyses of a cdna clone showed that the sequence is a member of the coiled coil-nucleotide binding site-leucine ...200515841357
production of transgenic crops by the floral-dip method.the application of floral dipping toward the production of transformed plants has been rather limited. however, this procedure has enabled the successful production of transformed medicago truncatula plants (a model plant for legume genetics) at efficiencies higher than those obtained by tissue culture methods. indeed, this simple system, without requiring any knowledge of plant tissue culture, has been a breakthrough in the production of the first transgenic radish plants. this root crop is of ...200515310916
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