the early nodulin gene mtn6 is a novel marker for events preceding infection of medicago truncatula roots by sinorhizobium meliloti.mtn6 belongs to a series of cdna clones representing medicago truncatula genes transcriptionally activated during nodulation by sinorhizobium meliloti (p. gamas, f. de carvalho niebel, n. lescure, and j. v. cullimore, mol. plant-microbe interact. 9:233-242, 1996). we show here by in situ hybridization that mtn6 transcripts specifically accumulate first at very localized regions in the outer root cell layers, corresponding to outer cortical cells containing preinfection threads. at later stages, ...199910356802
cloning and characterization of two phosphate transporters from medicago truncatula roots: regulation in response to phosphate and to colonization by arbuscular mycorrhizal (am) fungi.most vascular plants can acquire phosphate from the environment either directly, via the roots, or indirectly, via a fungal symbiont that invades the cortical cells of the root. here we have identified two cdna clones (mtpt1 and mtpt2) encoding phosphate transporters from a mycorrhizal root cdna library (medicago truncatula/glomus versiforme). the cdnas represent m. truncatula genes and the encoded proteins share identity with high-affinity phosphate transporters from arabidopsis, potato, yeast, ...19989425684
heteromeric assembly of the cytosolic glutamine synthetase polypeptides of medicago truncatula: complementation of a glna escherichia coli mutant with a plant domain-swapped enzyme.we have cloned and sequenced the cdnas corresponding to the two cytosolic glutamine synthetase (gs) polypeptides (a and b) of medicago truncatula. using these two cdnas we have prepared a construct encoding the n-terminal domain of b and the c-terminal domain of a in order to produce a domain-swapped polypeptide which should assemble to give an enzyme containing chimeric active sites. both the native and the domain-swapped enzymes were expressed in escherichia coli where they were catalytically ...19979349283
the alfalfa (medicago sativa) tdy1 gene encodes a mitogen-activated protein kinase homolog.development of root nodules, specifically induction of cortical cell division for nodule initiation, requires expression of specific genes in the host and microsymbiont. a full-length cdna clone and the corresponding genomic clone encoding a map (mitogen-activated protein) kinase homolog were isolated from alfalfa (medicago sativa). the genomic clone, tdy1, encodes a 68.9-kda protein with 47.7% identity to mmk4, a previously characterized map kinase homolog from alfalfa. tdy1 is unique among the ...199910517028
gene structure and differential regulation of the rhizobium-induced peroxidase gene rip1.primary expression of the rhizobium meliloti-induced peroxidase gene rip1 occurs prior to nodule morphogenesis, specifically at the site of impending rhizobial infection (d. cook, d. dreyer, d. bonnet, m. howell, e. nony, k. vandenbosch [1995] plant cell 7: 43-55). we examined the distribution and structure of rip1 transcript throughout nodule development. we determined that expression of rip1 in root tips is correlated with the competence of this zone for symbiotic association, whereas after rh ...19968972593
in rhizobium meliloti, the operon associated with the nod box n5 comprises nodl, noea and noeb, three host-range genes specifically required for the nodulation of particular medicago rhizobium meliloti, the genes required for nodulation of legume hosts are under the control of dna regulatory sequences called nod boxes. in this paper, we have characterized three host-specific nodulation genes, which form a flavonoid-inducible operon down-stream of the nod box n5. the first gene of this operon is identical to the nodl gene identified by baev and kondorosi (1992) in r. meliloti strain ak631. the product of the second gene, noea, presents some homology with a methyltransferas ...19958801423
a legume ethylene-insensitive mutant hyperinfected by its rhizobial symbiontdevelopment of the rhizobium-legume symbiosis is controlled by the host plant, although the underlying mechanisms have remained obscure. a mutant in the annual legume medicago truncatula exhibits an increase of more than an order of magnitude in the number of persistent rhizobial infections. physiological and genetic analyses indicate that this same mutation confers insensitivity to the plant hormone ethylene for multiple aspects of plant development, including nodulation. these data support the ...19978999796
enod40, a gene expressed during nodule organogenesis, codes for a non-translatable rna involved in plant growth.rhizobium meliloti can interact symbiotically with medicago plants, thereby inducing root nodules. however, certain medicago plants can form nodules spontaneously, in the absence of rhizobia. a differential screening was performed using spontaneous nodule versus root cdnas from medicago sativa ssp. varia. transcripts of a differentially expressed clone, msenod40, were detected in all differentiating cells of nodule primordia and spontaneous nodules, but were absent in fully differentiated cells. ...19947957074
a new proline-rich early nodulin from medicago truncatula is highly expressed in nodule meristematic cells.we cloned and characterized mtprp4, a new member of the repetitive proline-rich protein gene family in medicago truncatula. the sequence of mtprp4 predicts a 62-kd protein consisting of a 22-amino acid n-terminal signal peptide and a 527-amino acid repetitive proline-rich domain composed of three repetitive pentapeptide motifs arranged into two decapeptide repeats: ppvekppvhk and ppvekppvyk. mtprp4 is the largest prp described to date and contains repeated motifs that have not previously been fo ...19947919991
lectin genes from the legume medicago truncatula.we report the cloning and characterization of two lectin genes from medicago truncatula, designated mtlec1 and mtlec2. the two genes show a high degree of homology and apparently belong to a small multigene family. mtlec1 appears to encode a functional lectin with 277 amino acids, whereas mtlec2 is probably non-functional, since a frameshift mutation (insertion of two nucleotides) leads to premature translation termination after only 98 amino acids. the deduced amino acid sequence of the polypep ...19921511126
characterization of a binding site for chemically synthesized lipo-oligosaccharidic nodrm factors in particulate fractions prepared from roots.this paper describes the characteristics of a binding site for the major, lipo-oligosaccharide nod factor of rhizobium meliloti in roots of the symbiotic host plant, medicago truncatula. chemically synthesized nodrm-iv(ac, s, c16:2) was labelled by tritiation to a specific activity of 56 ci mmol-1 and this ligand was shown to be biologically active in the root hair deformation assay at 10(-11) m. binding of the ligand to a particulate fraction from roots of m. truncatula was found to be saturabl ...19957704048
transient induction of a peroxidase gene in medicago truncatula precedes infection by rhizobium meliloti.although key determinative events of the rhizobium-legume symbiosis are likely to precede bacterial infection, no plant genes have been identified that are expressed strongly prior to infection and nodule morphogenesis. a subtractive hybridization-polymerase chain reaction technique was used to enrich for genes induced during the early phases of the r. meliloti-medicago truncatula symbiosis. one gene so identified encodes a putative plant peroxidase protein, which we have named rip1 for rhizobiu ...19957696879
evidence that two genomic species of rhizobium are associated with medicago truncatula.seventy-three isolates of rhizobia sampled from root nodules of medicago truncatula were analyzed by restriction fragment length polymorphism (rflp) of dna regions amplified by the polymerase chain reaction (pcr) targeting the symbiotic plasmid (nifd-k, nodd1, and nodd2 genes) and the chromosome (16s rdna plus intergenic spacer). two genotypic groups were found, regardless of the dna region targeted. these two groups were given the status of genomic species based on results of dna/dna hybridizat ...19968639029
a sugar transporter from medicago truncatula: altered expression pattern in roots during vesicular-arbuscular (va) mycorrhizal associations.a cdna clone encoding a hexose transporter has been isolated from a library prepared from medicago truncatula roots colonized by the mycorrhizal fungus glomus versiforme. the clone (mtst1) represents a m. truncatula gene and expression studies in yeast indicate that the encoded protein transports glucose and fructose but not sucrose. transcripts corresponding to mtst1 are expressed in leaves, stems and roots of m. truncatula, with the highest levels of expression in roots. in the roots, mtst1 tr ...19968624512
expressed sequence tags from a root-hair-enriched medicago truncatula cdna librarythe root hair is a specialized cell type involved in water and nutrient uptake in plants. in legumes the root hair is also the primary site of recognition and infection by symbiotic nitrogen-fixing rhizobium bacteria. we have studied the root hairs of medicago truncatula, which is emerging as an increasingly important model legume for studies of symbiotic nodulation. however, only 27 genes from m. truncatula were represented in genbank/embl as of october, 1997. we report here the construction of ...19989701588
characterization of the mt4 gene from medicago truncatula.previously we identified mt4, a phosphate starvation inducible cdna from medicago truncatula which is down-regulated in roots in response to phosphate fertilization as well as colonization by arbuscular mycorrhizal (am) fungi (am). here we present further studies of mt4. expression was highly sensitive to exogenous applications of phosphate fertilizer; transcripts were abundant in roots fertilized with nutrient solution lacking phosphate, reduced when fertilized with 0.02 or 0.1 mm phosphate and ...19989714729
enzymatic radiolabelling to a high specific activity of legume lipo-oligosaccharidic nodulation factors from rhizobium this paper we describe the two-step coupled 35s-radiolabelling of the lipo-oligosaccharidic nodulation (nod) factors of the bacterium rhizobium meliloti to a specific radioactivity of 800 ci/mmol. these radiolabelled nod factors bind to a particulate fraction from roots of the bacterium's symbiotic host, medicago truncatula, with an equilibrium dissociation constant (kd) of 117 nm, similar to that observed with a synthetic tritiated ligand. the first step of the 35s-labelling involves the syn ...19957864819
use of a subtractive hybridization approach to identify new medicago truncatula genes induced during root nodule development.we report the identification of new molecular markers associated with different stages of rhizobium-induced nodule development in the legume medicago truncatula. a cdna library was constructed from pre-nitrogen-fixing m. truncatula nodules, and differentially screened with a polymerase chain reaction-amplified subtracted probe. twenty-nine new families of nodulin cdna clones, designated mtn1 to mtn29, were thus identified in addition to clones for several known nodulins. all mtn genes were shown ...19968634476
the medicago truncatula mtann1 gene encoding an annexin is induced by nod factors and during the symbiotic interaction with rhizobium we report the characterization of a new nod factor-induced gene from medicago truncatula identified by mrna differential display. this gene, designated mtann1, encodes a protein homologous to the annexin family of calcium- and phospholipid-binding proteins. we further show that the mtann1 gene is also induced during symbiotic associations with rhizobium meliloti, both at early stages in bacterial-inoculated roots and in nodule structures. by in situ hybridization, we demonstrate that mtann1 ...19989612949
symbiosis-specific expression of two medicago truncatula nodulin genes, mtn1 and mtn13, encoding products homologous to plant defense proteins.two medicago truncatula nodulin genes putatively encoding proteins structurally related to two classes of proteins commonly associated with plant defense reactions have been characterized. mtn1 is homologous to two small, cysteine-rich, pathogen-inducible proteins from pea (pi39 and pi230), whereas mtn13 is closely related to the pr10 family of pathogenesis-related proteins. we show that neither mtn1 nor mtn13 is induced in leaves in response to pathogenic bacteria, and that both are exclusively ...19989574507
the effect of zeranol and testosterone on merino wethers exposed to highly oestrogenic subterranean clover pasture.groups of merino wethers treated with 2 doses of zeranol (6 mg and 12 mg), or testosterone cyclopentyl propionate (150 mg) and untreated controls were grazed at 2 sites, one an oestrogenic subterranean clover (trifolium subterraneum) pasture and the other a low oestrogen medic (medicago truncatula) pasture. the influence of oestrogenic subterranean clover on these treatments was assessed by measuring changes in teat length, bulbourethral gland weight and pathology, bodyweight, carcase weight, dr ...19863767798
regulation of soybean nodulation independent of ethylene signalingleguminous plants regulate the number of bradyrhizobium- or rhizobium-infected sites that develop into nitrogen-fixing root nodules. ethylene has been implicated in the regulation of nodule formation in some species, but this role has remained in question for soybean (glycine max). the present study used soybean mutants with decreased responsiveness to ethylene, soybean mutants with defective regulation of nodule number, and ag+ inhibition of ethylene perception to examine the role of ethylene i ...199910069833
novel genes induced during an arbuscular mycorrhizal (am) symbiosis formed between medicago truncatula and glomus versiforme.many terrestrial plant species are able to form symbiotic associations with arbuscular mycorrhizal fungi. here we have identified three cdna clones representing genes whose expression is induced during the arbuscular mycorrhizal symbiosis formed between medicago truncatula and an arbuscular mycorrhizal fungus, glomus versiforme. the three clones represent m. truncatula genes and encode novel proteins: a xyloglucan endotransglycosylase-related protein, a putative arabinogalactan protein (agp), an ...199910065555
rhizobium meliloti elicits transient expression of the early nodulin gene enod12 in the differentiating root epidermis of transgenic study the molecular responses of the host legume during early stages of the symbiotic interaction with rhizobium, we have cloned and characterized the infection-related early nodulin gene mtenod12 from medicago truncatula. in situ hybridization experiments have shown that, within the indeterminate medicago nodule, transcription of the mtenod12 gene begins in cell layers of meristematic origin that lie ahead of the infection zone, suggesting that these cells are undergoing preparation for bact ...19921446169
alteration of enod40 expression modifies medicago truncatula root nodule development induced by sinorhizobium melilotimolecular mechanisms involved in the control of root nodule organogenesis in the plant host are poorly understood. one of the nodulin genes associated with the earliest phases of this developmental program is enod40. we show here that transgenic medicago truncatula plants overexpressing enod40 exhibit accelerated nodulation induced by sinorhizobium meliloti. this resulted from increased initiation of primordia, which was accompanied by a proliferation response of the region close to the root tip ...199910521525
a novel gene whose expression in medicago truncatula roots is suppressed in response to colonization by vesicular-arbuscular mycorrhizal (vam) fungi and to phosphate nutrition.a cdna clone (mt4) was isolated as a result of a differential screen to identify genes showing altered expression during the interaction between medicago truncatula and the vesicular-arbuscular mycorrhizal (vam) fungus glomus versiforme. mt4 represents a m. truncatula mrna that contains numerous short open reading frames, the two longest of which are predicted to encode polypeptides of 51 amino acids each. one of these open reading frames shares a short region of identity with a phosphate starva ...19979207836
synchronous expression of leghaemoglobin genes in medicago truncatula during nitrogen-fixing root nodule development and response to exogenously supplied nitrate.two leghaemoglobin genes from the diploid, autogamous medicago truncatula (mtlb1 and mtlb2) have been cloned and their nucleotide sequences determined. the deduced amino acid sequences encoded by these two genes differ significantly (18%), confirming that they belong to different sub-groups of medicago leghaemoglobin genes. rnase protection experiments have been used to show that both genes are transcriptionally active, and are expressed specifically in the nitrogen-fixing root nodule of m. trun ...19911883994
two branches of the lupeol synthase gene in the molecular evolution of plant oxidosqualene cyclases.two new triterpene synthase cdnas, named as oew and trw, were cloned from olive leaves (olea europaea) and from dandelion roots (taraxacum officinale), respectively, by the pcr method with primers designed from the conserved sequences found in the known oxidosqualene cyclases. their orfs consisted of 2274 bp nucleotides and coded for 758 amino acid long polypeptides. they shared high sequence identity (78%) to each other, while they showed only about 60% identities to the known triterpene syntha ...199910542078
differential expression of eight chitinase genes in medicago truncatula roots during mycorrhiza formation, nodulation, and pathogen infection.expression of eight different chitinase genes, representing members of five chitinase classes, was studied in medicago truncatula roots during formation of arbuscular mycorrhiza with glomus intraradices, nodulation with rhizobium meliloti, and pathogen attack by phytophthora megasperma f. sp. medicaginis, fusarium solani f. sp. phaseoli (compatible interactions with root rot symptoms), ascochyta pisi (compatible, symptomless), and f. solani f. sp. pisi (incompatible, nonhost interaction). in the ...200010875337
transformation of medicago truncatula via infiltration of seedlings or flowering plants with agrobacterium.two rapid and simple in planta transformation methods have been developed for the model legume medicago truncatula. the first approach is based on a method developed for transformation of arabidopsis thaliana and involves infiltration of flowering plants with a suspension of agrobacterium. the second method involves infiltration of young seedlings with agrobacterium. in both cases a proportion of the progeny of the infiltrated plants is transformed. the transformation frequency ranges from 4.7 t ...200010886773
mtsym6, a gene conditioning sinorhizobium strain-specific nitrogen fixation in medicago truncatula.the availability of a wide range of independent lines for the annual medic medicago truncatula led us to search for natural variants in the symbiotic association with sinorhizobium meliloti. two homozygous lines, jemalong 6 and dza315.16, originating from an australian cultivar and a natural algerian population, respectively, were inoculated with two wild-type strains of s. meliloti, rcr2011 and a145. both plant lines formed nitrogen-fixing (effective) nodules with the rcr2011 strain. however, t ...200010889234
analysis of medicago truncatula nodule expressed sequence tags.systematic sequencing of expressed sequence tags (ests) can give a global picture of the assembly of genes involved in the development and function of organs. indeterminate nodules representing different stages of the developmental program are especially suited to the study of organogenesis. with the vector lambdahybrizap, a cdna library was constructed from emerging nodules of medicago truncatula induced by sinorhizobium meliloti. the 5' ends of 389 cdna clones were sequenced, then these ests w ...200010656586
four genes of medicago truncatula controlling components of a nod factor transduction pathway.rhizobium nodulation (nod) factors are lipo-chitooligosaccharides that act as symbiotic signals, eliciting several key developmental responses in the roots of legume hosts. using nodulation-defective mutants of medicago truncatula, we have started to dissect the genetic control of nod factor transduction. mutants in four genes (dmi1, dmi2, dmi3, and nsp) were pleiotropically affected in nod factor responses, indicating that these genes are required for a nod factor-activated signal transduction ...200011006338
the presence of gsi-like genes in higher plants: support for the paralogous evolution of gsi and gsii genes.glutamine synthetase type i (gsi) genes have previously been described only in prokaryotes except that the fungus emericella nidulans contains a gene (flug) which encodes a protein with a large n-terminal domain linked to a c-terminal gsi-like domain. eukaryotes generally contain the type ii (gsii) genes which have been shown to occur also in some prokaryotes. the question of whether gsi and gsii genes are orthologues or paralogues remains a point of controversy. in this article we show that gsi ...200010684345
characterisation of a cdna encoding gamma-glutamylcysteine synthetase in medicago truncatula.a gamma-ecs cdna from medicago truncatula was isolated using an arabidopsis thaliana cdna as probe. the analysis of the amino acid sequence deduced from this cdna revealed 80% identity with the gamma-ecs from a. thaliana and brassica juncea and suggested a plastidial localisation for the enzyme. gamma-ecs activity and high level of gsh were detected in the gamma-ecs-deficient e. coli strain expressing a fusion protein containing the m. truncatula gamma-ecs protein. southern blot analysis suggest ...199910694062
enod40 induces dedifferentiation and division of root cortical cells in legumes.under nitrogen-limiting conditions rhizobium meliloti can establish symbiosis with medicago plants to form nitrogen-fixing root nodules. nodule organogenesis starts with the dedifferentiation and division of root cortical cells. in these cells the early nodulin gene enod40, which encodes an unusually small peptide (12 or 13 amino acids), is induced from the beginning of this process. herein we show that enod40 expression evokes root nodule initiation. (i) nitrogen-deprived transgenic medicago tr ...199711038563
genetic analysis of calcium spiking responses in nodulation mutants of medicago truncatula.the symbiotic interaction between medicago truncatula and sinorhizobium meliloti results in the formation of nitrogen-fixing nodules on the roots of the host plant. the early stages of nodule formation are induced by bacteria via lipochitooligosaccharide signals known as nod factors (nfs). these nfs are structurally specific for bacterium-host pairs and are sufficient to cause a range of early responses involved in the host developmental program. early events in the signal transduction of nfs ar ...200011078514
the hcl gene of medicago truncatula controls rhizobium-induced root hair curling.the symbiotic infection of the model legume medicago truncatula by sinorhizobium meliloti involves marked root hair curling, a stage where entrapment of the microsymbiont occurs in a chamber from which infection thread formation is initiated within the root hair. we have genetically dissected these early symbiotic interactions using both plant and rhizobial mutants and have identified a m. truncatula gene, hcl, which controls root hair curling. s. meliloti nod factors, which are required for the ...200111290290
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 ...200111261493
expression studies on aux1-like genes in medicago truncatula suggest that auxin is required at two steps in early nodule development.medicago truncatula contains a family of at least five genes related to aux1 of arabidopsis thaliana (termed mtlax genes for medicago truncatula-like aux1 genes). the high sequence similarity between the encoded proteins and aux1 implies that the mtlax genes encode auxin import carriers. the mtlax genes are expressed in roots and other organs, suggesting that they play pleiotropic roles related to auxin uptake. in primary roots, the mtlax genes are expressed preferentially in the root tips, part ...200111277424
medicago truncatula enod11: a novel rprp-encoding early nodulin gene expressed during mycorrhization in arbuscule-containing cells.leguminous plants establish endosymbiotic associations with both rhizobia (nitrogen fixation) and arbuscular mycorrhizal fungi (phosphate uptake). these associations involve controlled entry of the soil microsymbiont into the root and the coordinated differentiation of the respective partners to generate the appropriate exchange interfaces. as part of a study to evaluate analogies at the molecular level between these two plant-microbe interactions, we focused on genes from medicago truncatula en ...200111386369
differential regulation of a family of apyrase genes from medicago truncatula.four putative apyrase genes were identified from the model legume medicago truncatula. two of the genes identified from m. truncatula (mtapy1 and mtapy4) are expressed in roots and are inducible within 3 h after inoculation with sinorhizobium meliloti. the level of mrna expression of the other two putative apyrases, mtapy2 and mtapy3, was unaffected by rhizobial inoculation. screening of a bacterial artificial chromosome library of m. truncatula genomic dna showed that mtapy1, mtapy3, and mtapy4 ...200111299390
agrobacterium rhizogenes-transformed roots of medicago truncatula for the study of nitrogen-fixing and endomycorrhizal symbiotic associations.medicago truncatula, a diploid autogamous legume, is currently being developed as a model plant for the study of root endosymbiotic associations, including nodulation and mycorrhizal colonization. an important requirement for such a plant is the possibility of rapidly introducing and analyzing chimeric gene constructs in root tissues. for this reason, we developed and optimized a convenient protocol for agrobacterium rhizogenes-mediated transformation of m. truncatula. this unusual protocol, whi ...200111386364
spatial effects and rare outcrossing events in medicago truncatula (fabaceae).in order to elucidate the mechanisms underlying the large amount of rapd polymorphism found in 1990 in a population of the selfing annual medicago truncatula gaertn. (fabaceae), we have analysed most of the individuals (n = 363) from the same population 6 years later using microsatellite loci. we confirm the result of the earlier study, namely that this population is very polymorphic and highly subdivided, with approximately 37% of the variance distributed among subpopulations, only 50 m apart o ...200111412361
ethylene inhibits the nod factor signal transduction pathway of medicago truncatula.legumes form a mutualistic symbiosis with bacteria collectively referred to as rhizobia. the bacteria induce the formation of nodules on the roots of the appropriate host plant, and this process requires the bacterial signaling molecule nod factor. although the interaction is beneficial to the plant, the number of nodules is tightly regulated. the gaseous plant hormone ethylene has been shown to be involved in the regulation of nodule number. the mechanism of the ethylene inhibition on nodulatio ...200111487696
increased abundance of mtd1 and mtd2 mrnas in nodules of decapitated medicago gain insight into the molecular processes occurring in root nodule metabolism after stress, we used a mrna differential display (ddrt-pcr) approach to identify cdnas corresponding to genes whose expression is enhanced in nodules of decapitated medicago truncatula plants. two full-length cdnas of plant origin were isolated (mtd1 and mtd2). sequence analysis revealed that mtd1 is identical to an est clone (accession number aw559774) expressed in roots of m. truncatula upon infection with phytop ...200011197323
the spatial expression patterns of a phosphate transporter (mtpt1) from medicago truncatula indicate a role in phosphate transport at the root/soil interface.the movement of phosphate from the soil into plant root cells is the first of many crucial transport events required to supply phosphorous (p) to cells throughout the plant. in addition to the ability to acquire phosphate from the soil, the majority of the vascular plants are able to form arbuscular mycorrhizal associations in which phosphate may be delivered to the cortex via a fungus. previously, we cloned two phosphate transporter genes, mtpt1 and mtpt2 from medicago truncatula roots. complem ...200111208020
microtubule organization in root cells of medicago truncatula during development of an arbuscular mycorrhizal symbiosis with glomus versiforme.the colonization of plants by arbuscular mycorrhizal fungi has been shown to induce changes in cytoplasmic organization and morphology of root cells. because of their role in a variety of cellular functions in plants, it is likely that microtubules are involved either in the signaling events leading to the establishment of the symbiosis or in changes in host cell morphology and cytoplasmic architecture. recent studies of the arbuscular mycorrhizal symbiosis have shown that root cortical cells re ...200111732307
evidence for structurally specific negative feedback in the nod factor signal transduction pathway.nod factor is a critical signalling molecule in the establishment of the legume/rhizobial symbiosis. the nod factor of sinorhizobium meliloti carries o-sulphate, o-acetate and c16:2 n-acyl attachments that define its activity and host specificity. here we assess the relative importance of these modifications for the induction of calcium spiking in medicago truncatula. we find that nod factor structures lacking the o-sulphate, structures lacking the o-acetate and n-acyl groups, and structures lac ...200111722762
chemical syntheses of caffeoyl and 5-oh coniferyl aldehydes and alcohols and determination of lignin o-methyltransferase activities in dicot and monocot investigate the substrate preferences of o-methyltransferases in the monolignol biosynthetic pathways, caffeoyl and 5-hydroxy coniferyl aldehydes were synthesized by a new procedure involving a wittig reaction with the corresponding hydroxybenzaldehydes. the same procedure can also be used to synthesize caffeoyl and 5-hydroxyconiferyl alcohols. relative o-methyltransferase activities against these substrates were determined using crude extracts and recombinant caffeic acid o-methyltransferase ...200111730866
identification of a family of extensin-like glycoproteins in the lumen of rhizobium-induced infection threads in pea root nodules.rhizobium leguminosarum bv. viciae normally gains access to pea host cells through tubular cell wall ingrowths termed infection threads. matrix glycoprotein (mgp), a major component of the infection thread lumen, is also secreted from the tips of uninoculated roots and can be released into solution under reducing conditions. monoclonal antibody mac265, which recognizes mgp through a carbohydrate epitope, was used for immunoaffinity purification of the glycoprotein from pea roots. following treat ...200212026173
[differential accumulation of the new high-affinity phosphate transporter candidated gene fragment in rice roots in response to phosphorus deficiency stress].phosphate is a major constraint to crop production, and phosphate uptake in plant is mainly by high-affinity phosphate transporter under phosphate deficiency condition. using rt-pcr, a 1,178 bp phosphate transporter gene fragment ojpt1 was cloned from roots of jingxi17 (oryza sativa l. ssp. japanica) supplied with no phosphate. the comparison of this sequence with ones in genbank indicated that it shared about 70% similarity at amino acid level with other phosphate transporters in higher plants, ...200111233258
[calcium oscillations and nod signal transduction in rhizobium-legume symbiosis].rhizobium nodulation (nod) factors are lipo-chitooligosaccharides that act as symbiotic signals, eliciting a number of key developmental responses in the roots of legume hosts. one of the earliest responses of root hairs to nod factors is the induction of sharp oscillations of cytoplasmic calcium ion concentration ("calcium spiking"). this response was first characterised in medicago sativa and nod factors were found to be unable to induce calcium spiking in a nodulation-defective mutant of m. s ...200111833467
proteome analysis and identification of symbiosis-related proteins from medicago truncatula gaertn. by two-dimensional electrophoresis and mass spectrometry.time-course analysis of root protein profiles was studied by two-dimensional gel electrophoresis and silver staining in the model plant medicago truncatula, inoculated either with the arbuscular mycorrhizal fungus glomus mosseae or with the nitrogen fixing bacterium sinorhizobium meliloti. protein modifications in relation to the development of both symbioses included down- and upregulations, as well as newly induced polypeptides. matrix assisted laser desorption/ionization-time of flight-mass s ...200211824612
a medicago truncatula homoglutathione synthetase is derived from glutathione synthetase by gene duplication.glutathione (gsh) and homo-gsh (hgsh) are the major low-molecular weight thiols synthesized in medicago truncatula. two m. truncatula cdnas (gshs1 and gshs2) corresponding to a putative gsh synthetase (gshs) and a putative hgsh synthetase (hgshs) were characterized. heterologous expression of gshs1 and gshs2 cdnas in an escherichia coli strain deficient in gshs activity showed that gshs1 and gshs2 are a gshs and an hgshs, respectively. leucine-534 and proline-535 present in hgshs were substitute ...200111500568
structure-function analysis of nod factor-induced root hair calcium spiking in rhizobium-legume the rhizobium-legume symbiosis, compatible bacteria and host plants interact through an exchange of signals: host compounds promote the expression of bacterial biosynthetic nod (nodulation) genes leading to the production of a lipochito-oligosaccharide signal, the nod factor (nf). the particular array of nod genes carried by a given species of rhizobium determines the nf structure synthesized and defines the range of legume hosts by which the bacterium is recognized. purified nf can induce ea ...200212011352
a receptor kinase gene regulating symbiotic nodule development.leguminous plants are able to establish a nitrogen-fixing symbiosis with soil bacteria generally known as rhizobia. metabolites exuded by the plant root activate the production of a rhizobial signal molecule, the nod factor, which is essential for symbiotic nodule development. this lipo-chitooligosaccharide signal is active at femtomolar concentrations, and its structure is correlated with host specificity of symbiosis, suggesting the involvement of a cognate perception system in the plant host. ...200212087406
on the species of origin: diagnosing the source of symbiotic transcripts.most organisms have developed ways to recognize and interact with other species. symbiotic interactions range from pathogenic to mutualistic. some molecular mechanisms of interspecific interaction are well understood, but many remain to be discovered. expressed sequence tags (ests) from cultures of interacting symbionts can help identify transcripts that regulate symbiosis, but present a unique challenge for functional analysis. given a sequence expressed in an interaction between two symbionts, ...200111574056
kap-2, a protein that binds to the h-box in a bean chalcone synthase promoter, is a novel plant transcription factor with sequence identity to the large subunit of human ku autoantigen.the kap-2 protein that binds to the h-box (cctacc) element in the bean chs15 chalcone synthase promoter was purified, and internal peptide sequence used to design primers leading to the cloning of kap-2 from bean (phaseolus vulgaris) and barrel medic (medicago truncatula). kap-2 shares sequence similarity to the large subunit of mammalian ku autoantigen, a protein proposed to be involved in control of dna recombination and transcription. kap-2 sequences were present in genomic dna from a range o ...200212090626
overlapping plant signal transduction pathways induced by a parasitic nematode and a rhizobial endosymbiont.root-knot nematodes and rhizobia establish interactions with roots characterized by the de novo induction of host structures, termed giant cells and nodules, respectively. two transcription regulators, phan and knox, required for the establishment of meristems were previously shown to be expressed in tomato giant cells. we isolated the orthologues of phan and knox (mt-phan and mt-knox-1) from the model legume medicago truncatula, and established the spatial distribution of their expression in si ...200111605956
a mass spectrometry method for measuring 15n incorporation into pheophytin.the 15n content of pheophytin, the magnesium-free derivative of chlorophyll, can be measured with great accuracy and precision using positive-ion atmospheric pressure ionization electrospray mass spectroscopy following a simple solvent extraction of small amounts of plant tissue. the molecular weight of pheophytin prepared from chlamydomonas reinhardtii grown in different ratios of 14n/15n showed linear regression with the isotopic input, with a precision of 0.5-1%. using an isotope dilution str ...200212202237
te7, an inefficient symbiotic mutant of medicago truncatula gaertn. cv jemalong.a mutagenesis program using ethylmethane sulfonate on medicago truncatula gaertn cv jemalong, an annual, autogamous and diploid lucerne, permitted the isolation of a mutant (te7) unable to establish an effective nitrogen-fixing symbiosis, [nod+fix-], with rhizobium meliloti wild-type strains. the mutant phenotype is characterized by an altered infection process that leads to the formation of two kinds of inefficient nodules on the same root system. a certain proportion of the nodules are small, ...199512228341
glycine-rich proteins encoded by a nodule-specific gene family are implicated in different stages of symbiotic nodule development in medicago spp.four genes encoding small proteins with significantly high glycine content have been identified from root nodules of medicago sativa. all of these proteins as well as their medicago truncatula homologues carried an amino terminal signal peptide and a glycine-rich carboxy terminal domain. all except nodgrp3 lacked the characteristic repeat structure described for cell wall and stress response-related glycine-rich proteins (grp). expression of these grp genes was undetectable in flower, leaf, stem ...200212236598
evaluation of proteome reference maps for cross-species identification of proteins by peptide mass fingerprinting.we tested whether proteome reference maps established for one species can be used for cross-species protein identification by comparing two-dimensional protein gel patterns and protein identification data of two closely related bacterial strains and four plant species. first, proteome profiles of two strains of the fully sequenced bacterium sinorhizobium meliloti were compared as an example of close relatedness, high reproducibility and sequence availability. secondly, the proteome profiles of t ...200212362347
two distantly related genes encoding 1-deoxy-d-xylulose 5-phosphate synthases: differential regulation in shoots and apocarotenoid-accumulating mycorrhizal roots.isopentenyl diphosphate, the universal precursor of isoprenoids, is synthesized by two separate routes, one in the cytosol and the other in plastids. the initial step of the plastidial pathway is catalysed by 1-deoxy-d-xylulose 5-phosphate synthase (dxs), which was previously thought to be encoded by a single-copy gene. we have identified two distinct classes of dxs-like cdnas from the model legume medicago truncatula. the deduced mature mtdxs1 and mtdxs2 proteins, excluding the predicted plasti ...200212164805
a phosphate transporter from medicago truncatula involved in the acquisition of phosphate released by arbuscular mycorrhizal fungi.many plants have the capacity to obtain phosphate via a symbiotic association with arbuscular mycorrhizal (am) fungi. in am associations, the fungi release phosphate from differentiated hyphae called arbuscules, that develop within the cortical cells, and the plant transports the phosphate across a symbiotic membrane, called the periarbuscular membrane, into the cortical cell. in medicago truncatula, a model legume used widely for studies of root symbioses, it is apparent that the phosphate tran ...200212368495
nod factor induction of reactive oxygen species production is correlated with expression of the early nodulin gene rip1 in medicago truncatula.plant genes that are specifically activated by the rhizobial lipochitooligosaccharide signal molecule (nod factor) in legume hosts are collectively referred to as nodulins. although nodulin gene expression is both spatially and temporally correlated with symbiosis, the function of these genes and the molecular events underlying their expression remain unknown. sequence analysis of rip1, an early nodulin gene encoding a putative peroxidase protein, revealed the existence of sequence motifs with h ...200212059100
pharmacological analysis of nod factor-induced calcium spiking in medicago truncatula. evidence for the requirement of type iia calcium pumps and phosphoinositide signaling.bacterial nod factors trigger a number of cellular responses in root hairs of compatible legume hosts, which include periodic, transient increases in cytosolic calcium levels, termed calcium spiking. we screened 13 pharmaceutical modulators of eukaryotic signal transduction for effects on nod factor-induced calcium spiking. the purpose of this screening was 2-fold: to implicate enzymes required for nod factor-induced calcium spiking in medicago sp., and to identify inhibitors of calcium spiking ...200211950987
the soybean gmn6l gene encodes a late nodulin expressed in the infected zone of nitrogen-fixing nodules.previously, we determined the n-terminal amino acid sequences of a number of putative peribacteroid membrane proteins from soybean. here, we report the cloning of a gene, gmn6l, that encodes one of these proteins. the protein encoded by gmn6l is similar in sequence to mtn6, an early nodulin expressed in medicago truncatula roots in response to infection by sinorhizobium meliloti. the gmn6l gene was strongly expressed in mature nodules but not in other plant organs. gmn6l protein was first detect ...200212118878
genetic and cytogenetic mapping of dmi1, dmi2, and dmi3 genes of medicago truncatula involved in nod factor transduction, nodulation, and mycorrhization.the dmi1, dmi2, and dmi3 genes of medicago truncatula, which are required for both nodulation and mycorrhization, control early steps of nod factor signal transduction. here, we have used diverse approaches to pave the way for the map-based cloning of these genes. molecular amplification fragment length polymorphism markers linked to the three genes were identified by bulked segregant analysis. integration of these markers into the general genetic map of m. truncatula revealed that dmi1, dmi2, a ...200212423016
the nod factor-elicited annexin mtann1 is preferentially localised at the nuclear periphery in symbiotically activated root tissues of medicago truncatula.the medicago truncatula mtann1 gene, encoding a putative annexin, is transcriptionally activated in root tissues in response to rhizobial nod factors. to gain further insight into mtann1 function during the early stages of nodulation, we have examined in detail both spatio-temporal gene expression patterns and mtann1 activity and localisation in root tissues. analysis of transgenic medicago plants expressing a pmtann1-gus fusion has revealed a novel pattern of transcription in both outer and inn ...200212410812
a genomics approach to the early stages of triterpene saponin biosynthesis in medicago truncatula.the saponins of the model legume medicago truncatula are glycosides of at least five different triterpene aglycones: soyasapogenol b, soyasapogenol e, medicagenic acid, hederagenin and bayogenin. these aglycones are most likely derived from beta-amyrin, a product of the cyclization of 2,3-oxidosqualene. mining m. truncatula est data sets led to the identification of sequences putatively encoding three early enzymes of triterpene aglycone formation: squalene synthase (ss), squalene epoxidase (se) ...200212492844
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
exploring root symbiotic programs in the model legume medicago truncatula using est analysis.we report on a large-scale expressed sequence tag (est) sequencing and analysis program aimed at characterizing the sets of genes expressed in roots of the model legume medicago truncatula during interactions with either of two microsymbionts, the nitrogen-fixing bacterium sinorhizobium meliloti or the arbuscular mycorrhizal fungus glomus intraradices. we have designed specific tools for in silico analysis of est data, in relation to chimeric cdna detection, est clustering, encoded protein predi ...200212490726
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
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 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
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
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
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
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
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
stimulation of carotenoid metabolism in arbuscular mycorrhizal roots.development of arbuscular mycorrhizal roots is correlated with accumulation of various isoprenoids, i.e. acyclic c(14) polyene 'mycorradicin' and c(13) cyclohexenone derivatives. we present data indicating a strong stimulation of carotenoid metabolism in such roots. carotenoid profiling revealed mycorrhiza-specific accumulation of zeta-carotene in zea mays and medicago truncatula. precursor accumulation after inhibition of phytoene desaturase (pds) activity by norflurazon indicated an increased ...200212430024
expression of the apyrase-like apy1 genes in roots of medicago truncatula is induced rapidly and transiently by stress and not by sinorhizobium meliloti or nod factors.the model legume medicago truncatula contains at least six apyrase-like genes, five of which (mtapy1;1, mtapy1;2, mtapy1;3, mtapy1;4, and mtapy1;5) are members of a legume-specific family, whereas a single gene (mtapy2) has closer homologs in arabidopsis. phylogenetic analysis has revealed that the proteins encoded by these two plant gene families are more similar to yeast (saccharomyces cerevisiae) gda1 and to two proteins encoded by newly described mammalian genes (enp5 and 6) than they are to ...200312644663
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
the endosymbiosis-induced genes enod40 and ccs52a are involved in endoparasitic-nematode interactions in medicago truncatula.plants associate with a wide range of mutualistic and parasitic biotrophic organisms. here, we investigated whether beneficial plant symbionts and biotrophic pathogens induce distinct or overlapping regulatory pathways in medicago truncatula. the symbiosis between sinorhizobium meliloti and this plant results in the formation of nitrogen-fixing root nodules requiring the activation of specific genes in the host plant. we studied expression patterns of nodule-expressed genes after infection with ...200212437298
the nfp locus of medicago truncatula controls an early step of nod factor signal transduction upstream of a rapid calcium flux and root hair deformation.establishment of the rhizobium-legume symbiosis depends on a molecular dialogue, in which rhizobial nodulation (nod) factors act as symbiotic signals, playing a key role in the control of specificity of infection and nodule formation. using nodulation-defective (nod-) mutants of medicago truncatula to study the mechanisms controlling nod factor perception and signalling, we have previously identified five genes that control components of a nod factor-activated signal transduction pathway. charac ...200312753588
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
efficient transformation of medicago truncatula cv. jemalong using the hypervirulent agrobacterium tumefaciens strain agl1.the efficiency of agrobacterium tumefaciens transformation of the model legume medicago truncatula cv. jemalong (genotype 2ha) was evaluated for strains lba 4404, c58pmp90, c58pgv2260 and agl1. binary vectors carrying promoter- gus/ gfp reporter gene fusions and the nptii gene as selectable marker were used for plant in vitro transformation/regeneration. the highest transformation efficiency was obtained with the disarmed hypervirulent strain agl1 (ti plasmid tibo542), for which the percentage o ...200312827434
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
an integrated physical, genetic and cytogenetic map around the sunn locus of medicago truncatula.the sunn mutation of medicago truncatula is a single-gene mutation that confers a novel supernodulation phenotype in response to inoculation with sinorhizobium meliloti. we took advantage of the publicly available codominant pcr markers, the high-density genetic map, and a linked cytogenetic map to define the physical and genetic region containing sunn. we determined that sunn is located at the bottom of linkage group 4, where a fine-structure genetic map was used to place the locus within a app ...200312897874
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
identical accumulation and immobilization of sulfated and nonsulfated nod factors in host and nonhost root hair cell walls.nod factors are signaling molecules secreted by rhizobium bacteria. these lipo-chitooligosaccharides (lcos) are required for symbiosis with legumes and can elicit specific responses at subnanomolar concentrations on a compatible host. how plants perceive lcos is unclear. in this study, using fluorescent nod factor analogs, we investigated whether sulfated and nonsulfated nod factors were bound and perceived differently by medicago truncatula and vicia sativa root hairs. the bioactivity of three ...200314558690
a plasma membrane zinc transporter from medicago truncatula is up-regulated in roots by zn fertilization, yet down-regulated by arbuscular mycorrhizal 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
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 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
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
regiospecific hydroxylation of isoflavones by cytochrome p450 81e enzymes from medicago truncatula.mining of medicago truncatula est databases and screening of a root cdna library led to the identification of three cytochrome p450 81e subfamily members. two were functionally characterized by expression in yeast. the recombinant enzymes in yeast microsomes utilized the same isoflavone substrates, but produced different products hydroxylated at the 2' and/or 3' positions of the b-ring. when transiently expressed in alfalfa leaves, green fluorescent protein (gfp) fusions of the isoflavone 2'- an ...200314617078
nod factor-induced root hair curling: continuous polar growth towards the point of nod factor application.a critical step in establishing a successful nitrogen-fixing symbiosis between rhizobia and legume plants is the entrapment of the bacteria between root hair cell walls, usually in characteristic 180 degrees to 360 degrees curls, shepherd's crooks, which are formed by the host's root hairs. purified bacterial signal molecules, the nodulation factors (nfs), which are lipochitooligosaccharides, induce root hair deformation in the appropriate host legume and have been proposed to be a key player in ...200312913154
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
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
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