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elicitor-induced transcription factors for metabolic reprogramming of secondary metabolism in medicago truncatula.exposure of medicago truncatula cell suspension cultures to pathogen or wound signals leads to accumulation of various classes of flavonoid and/or triterpene defense molecules, orchestrated via a complex signalling network in which transcription factors (tfs) are essential components.200819102779
a portal for rhizobial genomes: rhizogate integrates a sinorhizobium meliloti genome annotation update with postgenome data.sinorhizobium meliloti is a symbiotic soil bacterium of the alphaproteobacterial subdivision. like other rhizobia, s. meliloti induces nitrogen-fixing root nodules on leguminous plants. this is an ecologically and economically important interaction, because plants engaged in symbiosis with rhizobia can grow without exogenous nitrogen fertilizers. the s. meliloti-medicago truncatula (barrel medic) association is an important symbiosis model. the s. meliloti genome was published in 2001, and the m ...200919103235
stimulation of nodulation in medicago truncatula by low concentrations of ammonium: quantitative reverse transcription pcr analysis of selected genes.although mineral nitrogen generally has negative effects on nodulation in legume-rhizobia symbioses, low concentrations of ammonium stimulate nodulation in some legumes. in this study, the effects of ammonium and nitrate on growth, nodulation and expression of 2 nitrogen transport and 12 putative nodulation-related genes of the model symbiosis of medicago truncatula - sinorhizobium meliloti are investigated. after 3 weeks of hydroponic growth, whole-plant nodulation was enhanced in all the ammon ...200919140888
an ste12 gene identified in the mycorrhizal fungus glomus intraradices restores infectivity of a hemibiotrophic plant pathogen.mechanisms of root penetration by arbuscular mycorrhizal (am) fungi are unknown and investigations are hampered by the lack of transformation systems for these unculturable obligate biotrophs. early steps of host infection by hemibiotrophic fungal phytopathogens, sharing common features with those of am fungal colonization, depend on the transcription factor ste12. using degenerated primers and rapid amplification of cdna ends, we isolated the full-length cdna of an ste12-like gene, gintste, fro ...200919140944
aer1, a major gene conferring resistance to aphanomyces euteiches in medicago truncatula.aphanomyces euteiches is a major soilborne oomycete pathogen that infects various legume species, including pea and alfalfa. the model legume medicago truncatula has recently emerged as a valuable genetic system for understanding the genetic basis of resistance to a. euteiches in leguminous crops. the objective of this study was to identify genetic determinants of resistance to a broad host-range pea-infecting strain of a. euteiches in m. truncatula. two m. truncatula segregating populations of ...200919159312
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
gras proteins form a dna binding complex to induce gene expression during nodulation signaling in medicago truncatula.the symbiotic association of legumes with rhizobia involves bacterially derived nod factor, which is sufficient to activate the formation of nodules on the roots of the host plant. perception of nod factor by root hair cells induces calcium oscillations that are a component of the nod factor signal transduction pathway. perception of the calcium oscillations is a function of a calcium- and calmodulin-dependent protein kinase, and this activates nodulation gene expression via two gras domain tran ...200919252081
characterization of root-knot nematode resistance in medicago truncatula.root knot (meloidogyne spp.) and cyst (heterodera and globodera spp.) nematodes infect all important crop species, and the annual economic loss due to these pathogens exceeds $90 billion. we screened the worldwide accession collection with the root-knot nematodes meloidogyne incognita, m. arenaria and m. hapla, soybean cyst nematode (scn-heterodera glycines), sugar beet cyst nematode (sbcn-heterodera schachtii) and clover cyst nematode (clcn-heterodera trifolii), revealing resistant and suscepti ...200819259519
methylotrophic metabolism is advantageous for methylobacterium extorquens during colonization of medicago truncatula under competitive conditions.facultative methylotrophic bacteria of the genus methylobacterium are commonly found in association with plants. inoculation experiments were performed to study the importance of methylotrophic metabolism for colonization of the model legume medicago truncatula. competition experiments with methylobacterium extorquens wild-type strain am1 and methylotrophy mutants revealed that the ability to use methanol as a carbon and energy source provides a selective advantage during colonization of m. trun ...200516269765
gene expression analysis of molecular mechanisms of defense induced in medicago truncatula parasitized by orobanche crenata.the infection of medicago truncatula gaertn. roots with the obligate parasite orobanche crenata forsk. is a useful model for studying the molecular events involved in the legumes-parasite interaction. in order to gain insight into the identification of gene-regulatory elements involved in the resistance mechanism, the temporal expression pattern of ten defense-related genes was carried out using real-time quantitative reverse-transcription polymerase chain reaction assays. the induction of all o ...200919321356
effects of indole-3-acetic acid on sinorhizobium meliloti survival and on symbiotic nitrogen fixation and stem dry weight production.we evaluated the effects of the main auxin phytohormone, indole-3-acetic acid (iaa), on the central metabolism of sinorhizobium meliloti 1021. we either treated s. meliloti 1021 wild-type cells with 0.5 mm iaa, 1021+, or use a derivative, rd64, of the same strain harboring an additional pathway for iaa biosynthesis (converting tryptophan into iaa via indoleacetamide). we assayed the activity of tricarboxylic acid cycle (tca) key enzymes and found that activity of citrate synthase and alpha-ketog ...200919343341
sini- and expr-dependent quorum sensing in sinorhizobium meliloti.quorum sensing (qs) in sinorhizobium meliloti, the n-fixing bacterial symbiont of medicago host plants, involves at least half a dozen different n-acyl homoserine lactone (ahl) signals and perhaps an equal number of ahl receptors. the accumulation of 55 proteins was found to be dependent on sini, the ahl synthase, and/or on expr, one of the ahl receptors. gas chromatography-mass spectrometry and electrospray ionization tandem mass spectrometry identified 3-oxo-c(14)-homoserine lactone (3-oxo-c(1 ...200516291666
geminivirus infection up-regulates the expression of two arabidopsis protein kinases related to yeast snf1- and mammalian ampk-activating kinases.geminivirus rep-interacting kinase 1 (grik1) and grik2 constitute a small protein kinase family in arabidopsis (arabidopsis thaliana). an earlier study showed that a truncated version of grik1 binds to the geminivirus replication protein al1. we show here both full-length grik1 and grik2 interact with al1 in yeast two-hybrid studies. using specific antibodies, we showed that both arabidopsis kinases are elevated in infected leaves. immunoblot analysis of healthy plants revealed that grik1 and gr ...200617041027
differing requirements for flavonoids during the formation of lateral roots, nodules and root knot nematode galls in medicago truncatula.* in this study, we tested whether the organogenesis of symbiotic root nodules, lateral roots and root galls induced by parasitic root knot nematodes (meloidogyne javanica) was regulated by the presence of flavonoids in the roots of medicago truncatula. flavonoids accumulate in all three types of root organ, and have been hypothesized previously to be required for secondary root organogenesis because of their potential role as auxin transport regulators. * using rna interference to silence the f ...200919402878
the symbiotic ion channel homolog dmi1 is localized in the nuclear membrane of medicago truncatula roots.legumes utilize a common signaling pathway to form symbiotic associations both with rhizobial bacteria and arbuscular mycorrhizal fungi. the perception of microbial signals is believed to take place at the plasma membrane, activating a cascade that converges on the nucleus where transcriptional reprogramming facilitates the symbioses. forward genetic strategies have identified genes in this signaling pathway including medicago truncatula dmi1 (doesn't make infections 1) that encodes a putative i ...200717173544
medicago truncatula improves salt tolerance when nodulated by an indole-3-acetic acid-overproducing sinorhizobium meliloti strain.the abiotic stress resistance of wild-type sinorhizobium meliloti 1021 was compared with that of rd64, a derivative of the 1021 strain harbouring an additional pathway for the synthesis of indole-3-acetic acid (iaa), expressed in both free-living bacteria and bacteroids. it is shown here that the iaa-overproducing rd64 strain accumulated a higher level of trehalose as its endogenous osmolyte and showed an increased tolerance to several stress conditions (55 degrees c, 4 degrees c, uv-irradiation ...200919436044
medicago truncatula root nodule proteome analysis reveals differential plant and bacteroid responses to drought stress.drought is one of the environmental factors most affecting crop production. under drought, symbiotic nitrogen fixation is one of the physiological processes to first show stress responses in nodulated legumes. this inhibition process involves a number of factors whose interactions are not yet understood. this work aims to further understand changes occurring in nodules under drought stress from a proteomic perspective. drought was imposed on medicago truncatula 'jemalong a17' plants grown in sym ...200717545507
dissection of bacterial wilt on medicago truncatula revealed two type iii secretion system effectors acting on root infection process and disease development.ralstonia solanacearum is the causal agent of the devastating bacterial wilt disease, which colonizes susceptible medicago truncatula via the intact root tip. infection involves four steps: appearance of root tip symptoms, root tip cortical cell invasion, vessel colonization, and foliar wilting. we examined this pathosystem by in vitro inoculation of intact roots of susceptible or resistant m. truncatula with the pathogenic strain gmi1000. the infection process was type iii secretion system depe ...200919493968
medicago lyk3, an entry receptor in rhizobial nodulation factor signaling.rhizobia secrete nodulation (nod) factors, which set in motion the formation of nitrogen-fixing root nodules on legume host plants. nod factors induce several cellular responses in root hair cells within minutes, but also are essential for the formation of infection threads by which rhizobia enter the root. based on studies using bacterial mutants, a two-receptor model was proposed, a signaling receptor that induces early responses with low requirements toward nod factor structure and an entry r ...200717586690
changes in the profile of flavonoid accumulation in medicago truncatula leaves during infection with fungal pathogen phoma medicaginis.medicago truncatula is a model species for the study of the unique secondary metabolism in legumes. lc/ms/ms analysis was used to identify and profile flavonoid glycoconjugates and free aglycones in leaves of m. truncatula (ecotype r108-1) infected with the fungal pathogen phoma medicaginis. use of a high resolution analyzer with a collision induced dissociation tandem mass spectrometer (cid ms/ms) permitted structural elucidation of target secondary metabolites and four new acylated flavone gly ...200919541494
metabolic capacity of sinorhizobium (ensifer) meliloti strains as determined by phenotype microarray analysis.sinorhizobium meliloti is a soil bacterium that fixes atmospheric nitrogen in plant roots. the high genetic diversity of its natural populations has been the subject of extensive analysis. recent genomic studies of several isolates revealed a high content of variable genes, suggesting a correspondingly large phenotypic differentiation among strains of s. meliloti. here, using the phenotype microarray (pm) system, hundreds of different growth conditions were tested in order to compare the metabol ...200919561177
integrated metabolite and transcript profiling identify a biosynthetic mechanism for hispidol in medicago truncatula cell cultures.metabolic profiling of elicited barrel medic (medicago truncatula) cell cultures using high-performance liquid chromatography coupled to photodiode and mass spectrometry detection revealed the accumulation of the aurone hispidol (6-hydroxy-2-[(4-hydroxyphenyl)methylidene]-1-benzofuran-3-one) as a major response to yeast elicitor. parallel, large-scale transcriptome profiling indicated that three peroxidases, mtprx1, mtprx2, and mtprx3, were coordinately induced with the accumulation of hispidol. ...200919571306
composite medicago truncatula plants harbouring agrobacterium rhizogenes-transformed roots reveal normal mycorrhization by glomus intraradices.composite plants consisting of a wild-type shoot and a transgenic root are frequently used for functional genomics in legume research. although transformation of roots using agrobacterium rhizogenes leads to morphologically normal roots, the question arises as to whether such roots interact with arbuscular mycorrhizal (am) fungi in the same way as wild-type roots. to address this question, roots transformed with a vector containing the fluorescence marker dsred were used to analyse am in terms o ...200919574251
lysm domains mediate lipochitin-oligosaccharide recognition and nfr genes extend the symbiotic host range.legume-rhizobium symbiosis is an example of selective cell recognition controlled by host/non-host determinants. individual bacterial strains have a distinct host range enabling nodulation of a limited set of legume species and vice versa. we show here that expression of lotus japonicus nfr1 and nfr5 nod-factor receptor genes in medicago truncatula and l. filicaulis, extends their host range to include bacterial strains, mesorhizobium loti or dzl, normally infecting l. japonicus. as a result, th ...200717690687
(homo)glutathione depletion modulates host gene expression during the symbiotic interaction between medicago truncatula and sinorhizobium meliloti.under nitrogen-limiting conditions, legumes interact with symbiotic rhizobia to produce nitrogen-fixing root nodules. we have previously shown that glutathione and homoglutathione [(h)gsh] deficiencies impaired medicago truncatula symbiosis efficiency, showing the importance of the low m(r) thiols during the nodulation process in the model legume m. truncatula. in this study, the plant transcriptomic response to sinorhizobium meliloti infection under (h)gsh depletion was investigated using cdna- ...200919587096
partial resistance of medicago truncatula to aphanomyces euteiches is associated with protection of the root stele and is controlled by a major qtl rich in proteasome-related genes.a pathosystem between aphanomyces euteiches, the causal agent of pea root rot disease, and the model legume medicago truncatula was developed to gain insights into mechanisms involved in resistance to this oomycete. the f83005.5 french accession and the a17-jemalong reference line, susceptible and partially resistant, respectively, to a. euteiches, were selected for further cytological and genetic analyses. microscopy analyses of thin root sections revealed that a major difference between the tw ...200919656040
symbiotic diversity of ensifer meliloti strains recovered from various legume species in tunisia.ensifer meliloti (formerly sinorhizobium meliloti) was first considered as a specific microsymbiont of medicago, melilotus and trigonella. however, strains of e. meliloti were recovered from root nodules of various legume species and their symbiotic status still remains unclear. here, we further investigate the specificity of these strains. a collection of 47 e. meliloti strains isolated in tunisia from root nodules of medicago truncatula, medicago sativa, medicago ciliaris, medicago laciniata, ...200919665858
early steps in proanthocyanidin biosynthesis in the model legume medicago truncatula.oligomeric proanthocyanidins (pas) composed primarily of epicatechin units accumulate in the seed coats of the model legume medicago truncatula, reaching maximal levels at around 20 d after pollination. genes encoding the single medicago anthocyanidin synthase (ans; ec 1.14.11.19) and leucoanthocyanidin reductase (lar; ec 1.17.1.3) were cloned and the corresponding enzymes functionally identified. recombinant mtans converted leucocyanidin to cyanidin, and, more efficiently, dihydroquercetin to t ...200717885080
induction of a small heat shock protein and its functional roles in nicotiana plants in the defense response against ralstonia solanacearum.in tobacco (nicotiana tabacum), ralstonia solanacearum oe1-1 (rsoe1-1) is pathogenic, whereas r. solanacearum 8107 (rs8107) is nonpathogenic and induces the hypersensitive response (hr). to elucidate the molecular mechanisms of plant-r. solanacearum interactions, we used differential display to isolate a cdna fragment, a6, regulated in tobacco by inoculation with rsoe1-1. the deduced amino acid sequence predicted from full-length a6-cdna showed similarity to small heat shock proteins from arabid ...200717965181
a nuclear-targeted cameleon demonstrates intranuclear ca2+ spiking in medicago truncatula root hairs in response to rhizobial nodulation factors.lipochitooligosaccharide nodulation factors (nfs) secreted by endosymbiotic nitrogen-fixing rhizobia trigger ca(2+) spiking in the cytoplasmic perinuclear region of host legume root hairs. to determine whether nfs also elicit ca(2+) responses within the plant cell nucleus we have made use of a nucleoplasmin-tagged cameleon (nupyc2.1). confocal microscopy using this nuclear-specific calcium reporter has revealed sustained and regular ca(2+) spiking within the nuclear compartment of medicago trunc ...200919700563
can differences of nitrogen nutrition level among medicago truncatula genotypes be assessed non-destructively?: probing with a recombinant inbred lines population.the international consensus on medicago truncatula as a model system has lead to the development of powerful approaches for dissecting the genetic and molecular bases of legume nitrogen nutrition. however, such approaches now come up against a poor knowledge of the phenotypic traits that should be used for the large-scale screening of the genotypic variability associated with nitrogen nutrition. this issue was unravelled in a previous report, in which an ecophysiological approach allowed a bette ...200919704700
medicago n2-fixing symbiosomes acquire the endocytic identity marker rab7 but delay the acquisition of vacuolar identity.rhizobium bacteria form n(2)-fixing organelles, called symbiosomes, inside the cells of legume root nodules. the bacteria are generally thought to enter the cells via an endocytosis-like process. to examine this, we studied the identity of symbiosomes in relation to the endocytic pathway. we show that in medicago truncatula, the small gtpases rab5 and rab7 are endosomal membrane identity markers, marking different (partly overlapping) endosome populations. although symbiosome formation is consid ...200919734435
legume small gtpases and their role in the establishment of symbiotic associations with rhizobium spp.small gtp-binding genes act as molecular switches regulating myriad of cellular processes including vesicle-mediated intracellular trafficking, signal transduction, cytoskeletal reorganization and cell division in plants and animals. even though these genes are well conserved both functionally and sequentially across whole eukaryotae, occasional lineage-specific diversification in some plant species in terms of both functional and expressional characteristics have been reported. hence, comparati ...200919794839
identification and characterization of mtmtp1, a zn transporter of cdf family, in the medicago truncatula.zn is an essential micronutrient in plants, and the mechanisms of zn homeostasis are under intensive study. in this report, we have identified mtmtp1, a zn transporter of the cdf family in the legume model plant medicago truncatula. the orf of the mtmtp1 cdna encodes a protein consisting of 407 amino acid residues with a predicted molecular mass of 45 kda. like other metal tolerance proteins (mtps) in plants, heterologous expression of mtmtp1 can complement the zn-susceptible zrc1 cot1 yeast dou ...200919800247
cloning and characterization of a functional flavanone-3ß-hydroxylase gene from medicago truncatula.as a key enzyme in the biosynthesis of flavonols, anthocyanidins and proanthocyanidins, flavanone-3ß-hydroxylase (f3h) plays very important roles in plant stress response. a putative flavanone-3ß-hydroxylase gene from medicago truncatula (mtf3h), a model legume species, was identified from a bio-data analysis platform. it was speculated to be induced by salt stress based on the outcomes of the analysis platform. the complementary dna (cdna) consists of 1499 bp with an open reading frame (orf) of ...201019888675
the medicago truncatula n5 gene encoding a root-specific lipid transfer protein is required for the symbiotic interaction with sinorhizobium meliloti.the medicago truncatula n5 gene is induced in roots after sinorhizobium meliloti infection and it codes for a putative lipid transfer protein (ltp), a family of plant small proteins capable of binding and transferring lipids between membranes in vitro. various biological roles for plant ltp in vivo have been proposed, including defense against pathogens and modulation of plant development. the aim of this study was to shed light on the role of mtn5 in the symbiotic interaction between m. truncat ...200919888823
the rap1 gene confers effective, race-specific resistance to the pea aphid in medicago truncatula independent of the hypersensitive reaction.plant resistance to pathogens is commonly associated with a hypersensitive response (hr), but the degree to which the hr is responsible for incompatibility is subject to debate. resistance to aphids is likely to share features with resistance to pathogens but is less well understood. here, we report effective resistance to the pea aphid acyrthosiphon pisum in medicago truncatula. aphids lost weight and died rapidly (within two days) on the resistant genotype jemalong, which developed necrotic le ...200919888829
differential gel electrophoresis (dige) to quantitatively monitor early symbiosis- and pathogenesis-induced changes of the medicago truncatula root proteome.symbiosis- and pathogenesis-related early protein induction patterns in the model legume medicago truncatula were analysed with two-dimensional differential gel electrophoresis. two symbiotic soil microorganisms (glomus intraradices, sinorhizobium meliloti) were used in single infections and in combination with a secondary pathogenic infection by the oomycete aphanomyces euteiches. proteomic analyses performed 6 and 24h after inoculations led to identification of 87 differentially induced protei ...201019895911
analysis and modeling of the integrative response of medicago truncatula to nitrogen constraints.an integrative biology approach was conducted in medicago truncatula for: (i) unraveling the coordinated regulation of no3-, nh4+ and n(2) acquisition by legumes to fulfill the plant n demand; and (ii) modeling the emerging properties occurring at the whole plant level. upon localized addition of a high level of mineral n, the three n acquisition pathways displayed similar systemic feedback repression to adjust n acquisition capacities to the plant n status. genes associated to these responses w ...200919909924
red clover coumarate 3'-hydroxylase (cyp98a44) is capable of hydroxylating p-coumaroyl-shikimate but not p-coumaroyl-malate: implications for the biosynthesis of phaselic acid.red clover (trifolium pratense) leaves accumulate several mumol of phaselic acid [2-o-caffeoyl-l-malate] per gram fresh weight. post-harvest oxidation of such o-diphenols to o-quinones by endogenous polyphenol oxidases (ppo) prevents breakdown of forage protein during storage. forages like alfalfa (medicago sativa) lack both foliar ppo activity and o-diphenols. consequently, breakdown of their protein upon harvest and storage results in economic losses and release of excess nitrogen into the env ...201019921248
identification of flavone phytoalexins and a pathogen-inducible flavone synthase ii gene (sbfnsii) in sorghum.following inoculation with the anthracnose pathogen colletotrichum sublineolum, seedlings of the sorghum resistant cultivar sc748-5 showed more rapid and elevated accumulation of luteolin than the susceptible cultivar btx623. on the other hand, apigenin was the major flavone detected in infected btx623 seedlings. luteolin was demonstrated to show stronger inhibition of spore germination of c. sublineolum than apigenin. because of their pathogen-inducible and antifungal nature, both flavone aglyc ...201020007684
a complex genetic network involving a broad-spectrum locus and strain-specific loci controls resistance to different pathotypes of aphanomyces euteiches in medicago truncatula.a higher understanding of genetic and genomic bases of partial resistance in plants and their diversity regarding pathogen variability is required for a more durable management of resistance genetic factors in sustainable cropping systems. in this study, we investigated the diversity of genetic factors involved in partial resistance to aphanomyces euteiches, a very damaging pathogen on pea and alfalfa, in medicago truncatula. a mapping population of 178 recombinant inbred lines, from the cross f ...201020012740
the mtsnf4b subunit of the sucrose non-fermenting-related kinase complex connects after-ripening and constitutive defense responses in seeds of medicago truncatula.dormant seeds are capable of remaining alive in the hydrated state for extended periods of time without losing vigor, until environmental cues or after-ripening result in the release of dormancy. here, we investigated the possible role of the regulatory subunit of the sucrose non-fermenting-related kinase complex, mtsnf4b, in dormancy of medicago truncatula seeds. expression of mtsnf4b and its involvement in a high-molecular-weight complex are found in dormant seeds, whereas imbibition of fully ...201020015062
different mechanisms for phytoalexin induction by pathogen and wound signals in medicago truncatula.cell suspensions of the model legume medicago truncatula accumulated the isoflavonoid phytoalexin medicarpin in response to yeast elicitor or methyl jasmonate (mj), accompanied by decreased levels of isoflavone glycosides in mj-treated cells. dna microarray analysis revealed rapid, massive induction of early (iso)flavonoid pathway gene transcripts in response to yeast elicitor, but not mj, and differential induction by the two elicitors of sets of genes encoding transcription factors, abc transp ...200717971436
metabolomics reveals novel pathways and differential mechanistic and elicitor-specific responses in phenylpropanoid and isoflavonoid biosynthesis in medicago truncatula cell cultures.high-performance liquid chromatography coupled to ultraviolet photodiode array detection and ion-trap mass spectrometry was used to analyze the intra- and extracellular secondary product metabolome of medicago truncatula cell suspension cultures responding to yeast elicitor (ye) or methyl jasmonate (meja). data analysis revealed three phases of intracellular response to ye: a transient response in mainly (iso)flavonoid metabolites such as formononetin and biochanin-a that peaked at 12 to 18 h fo ...200818055588
a novel rna-binding peptide regulates the establishment of the medicago truncatula-sinorhizobium meliloti nitrogen-fixing symbiosis.plants use a variety of small peptides for cell to cell communication during growth and development. leguminous plants are characterized by their ability to develop nitrogen-fixing nodules via an interaction with symbiotic bacteria. during nodule organogenesis, several so-called nodulin genes are induced, including large families that encode small peptides. using a three-hybrid approach in yeast cells, we identified two new small nodulins, mtsnarp1 and mtsnarp2 (for small nodulin acidic rna-bind ...201020042020
presence of three mycorrhizal genes in the common ancestor of land plants suggests a key role of mycorrhizas in the colonization of land by plants.*the colonization of land by plants fundamentally altered environmental conditions on earth. plant-mycorrhizal fungus symbiosis likely played a key role in this process by assisting plants to absorb water and nutrients from soil. *here, in a diverse set of land plants, we investigated the evolutionary histories and functional conservation of three genes required for mycorrhiza formation in legumes and rice (oryza sativa), dmi1, dmi3 and ipd3. *the genes were isolated from nearly all major plant ...201020059702
large-scale insertional mutagenesis using the tnt1 retrotransposon in the model legume medicago truncatula.medicago truncatula is a fast-emerging model for the study of legume functional biology. we used the tobacco retrotransposon tnt1 to tag the medicago genome and generated over 7600 independent lines representing an estimated 190,000 insertion events. tnt1 inserted on average at 25 different locations per genome during tissue culture, and insertions were stable during subsequent generations in soil. analysis of 2461 tnt1 flanking sequence tags (fsts) revealed that tnt1 appears to prefer gene-rich ...200818208518
suppression of hypernodulation in soybean by a leaf-extracted, nark- and nod factor-dependent, low molecular mass fraction.*legumes regulate the number of nodules they form via a process called autoregulation of nodulation (aon). this involves a shoot-derived inhibitor (sdi) molecule that is synthesized in the shoots and is transported down to the roots where it inhibits further nodule development. *to characterize sdi, we developed a novel feeding bioassay. this involved feeding aqueous leaf extracts directly into the petiole of hypernodulating and supernodulating nark mutant plants of glycine max (soybean). these ...201020100211
systemic signaling of the plant nitrogen status triggers specific transcriptome responses depending on the nitrogen source in medicago truncatula.legumes can acquire nitrogen (n) from no(3)(-), nh(4)(+), and n(2) (through symbiosis with rhizobium bacteria); however, the mechanisms by which uptake and assimilation of these n forms are coordinately regulated to match the n demand of the plant are currently unknown. here, we find by use of the split-root approach in medicago truncatula plants that no(3)(-) uptake, nh(4)(+) uptake, and n(2) fixation are under general control by systemic signaling of plant n status. indeed, irrespective of the ...200818287487
a remorin protein interacts with symbiotic receptors and regulates bacterial infection.remorin proteins have been hypothesized to play important roles during cellular signal transduction processes. induction of some members of this multigene family has been reported during biotic interactions. however, no roles during host-bacteria interactions have been assigned to remorin proteins until now. we used root nodule symbiosis between medicago truncatula and sinorhizobium meliloti to study the roles of a remorin that is specifically induced during nodulation. here we show that this ol ...201020133878
site and plant species are important determinants of the methylobacterium community composition in the plant phyllosphere.the plant phyllosphere constitutes a habitat for numerous microorganisms; among them are members of the genus methylobacterium. owing to the ubiquitous occurrence of methylobacteria on plant leaves, they represent a suitable target for studying plant colonization patterns. the influence of the factor site, host plant species, time and the presence of other phyllosphere bacteria on methylobacterium community composition and population size were evaluated in this study. leaf samples were collected ...201020164863
plant peptides govern terminal differentiation of bacteria in symbiosis.legume plants host nitrogen-fixing endosymbiotic rhizobium bacteria in root nodules. in medicago truncatula, the bacteria undergo an irreversible (terminal) differentiation mediated by hitherto unidentified plant factors. we demonstrated that these factors are nodule-specific cysteine-rich (ncr) peptides that are targeted to the bacteria and enter the bacterial membrane and cytosol. obstruction of ncr transport in the dnf1-1 signal peptidase mutant correlated with the absence of terminal bacteri ...201020185722
a nodule-specific protein secretory pathway required for nitrogen-fixing symbiosis.the nitrogen-fixing symbiosis between sinorhizobium meliloti and its leguminous host plant medicago truncatula occurs in a specialized root organ called the nodule. bacteria that are released into plant cells are surrounded by a unique plant membrane compartment termed a symbiosome. we found that in the symbiosis-defective dnf1 mutant of m. truncatula, bacteroid and symbiosome development are blocked. we identified the dnf1 gene as encoding a subunit of a signal peptidase complex that is highly ...201020185723
role of the sinorhizobium meliloti global regulator hfq in gene regulation and symbiosis.the rna-binding protein hfq is a global regulator which controls diverse cellular processes in bacteria. to begin understanding the role of hfq in the sinorhizobium meliloti-medicago truncatula nitrogen-fixing symbiosis, we defined free-living and symbiotic phenotypes of an hfq mutant. over 500 transcripts were differentially accumulated in the hfq mutant of s. meliloti rm1021 when grown in a shaking culture. consistent with transcriptome-wide changes, the hfq mutant displayed dramatic alteratio ...201020192823
transcription of enod8 in medicago truncatula nodules directs enod8 esterase to developing and mature symbiosomes.in medicago truncatula nodules, the soil bacterium sinorhizobium meliloti reduces atmospheric dinitrogen into nitrogenous compounds that the legume uses for its own growth. in nitrogen-fixing nodules, each infected cell contains symbiosomes, which include the rhizobial cell, the symbiosome membrane surrounding it, and the matrix between the bacterium and the symbiosome membrane, termed the symbiosome space. here, we describe the localization of enod8, a nodule-specific esterase. the onset of eno ...200818321186
regioselective synthesis of plant (iso)flavone glycosides in escherichia coli.the flavonoids genistein, biochanin a, luteolin, quercetin, and kaempferol are plant natural products with potentially useful pharmacological and nutraceutical activities. these natural products usually exist in plants as glycosides, and their glycosylation has a remarkable influence on their pharmacokinetic properties. the glycosyltransferases ugt71g1 and ugt73c8 from medicago truncatula are excellent reagents for the regioselective glycosylation of (iso)flavonoids in escherichia coli grown in ...200818568307
isolation and characterization of a harvest-inducible gene hi11 and its promoter from alfalfa.the harvesting and storing of alfalfa is a routine practice in the agricultural industry worldwide. to investigate gene expression in harvested alfalfa, cdna from non-harvested and harvested plants in the field was subjected to subtractive hybridization to identify, in particular, those genes that are induced by the harvesting treatment. one cdna clone, named hi11, was isolated and analysed. the full length cdna of the hi11 gene was cloned by race amplification. the hi11 gene, which has high hom ...201120238171
proteomic analysis of medicago truncatula root plastids.despite the recognized importance of non-photosynthetic plastids in a wide array of plant processes, the root plastid proteome of soil-grown plants still remains to be explored. in this study, we used a protocol allowing the isolation of medicago truncatula root plastids with sufficient protein recovery and purity for their subsequent in-depth analysis by nanoscale capillary lc-ms/ms. besides providing the first picture of a root plastid proteome, the results obtained highlighted the identificat ...201020336678
effects of medicago truncatula genetic diversity, rhizobial competition, and strain effectiveness on the diversity of a natural sinorhizobium species community.we investigated the genetic diversity and symbiotic efficiency of 223 sinorhizobium sp. isolates sampled from a single mediterranean soil and trapped with four medicago truncatula lines. dna molecular polymorphism was estimated by capillary electrophoresis-single-stranded conformation polymorphism and restriction fragment length polymorphism on five loci (igs(nod), typa, virb11, avhb11, and the 16s rrna gene). more than 90% of the rhizobia isolated belonged to the sinorhizobium medicae species ( ...200818658290
alfalfa benefits from medicago truncatula: the rct1 gene from m. truncatula confers broad-spectrum resistance to anthracnose in alfalfa.alfalfa is economically the most important forage legume worldwide. a recurrent challenge to alfalfa production is the significant yield loss caused by disease. although knowledge of molecular mechanisms underlying host resistance should facilitate the genetic improvement of alfalfa, the acquisition of such knowledge is hampered by alfalfa's tetrasomic inheritance and outcrossing nature. however, alfalfa is congeneric with the reference legume medicago truncatula, providing an opportunity to use ...200818719113
nitrogen fixation persists under conditions of salt stress in transgenic medicago truncatula plants expressing a cyanobacterial flavodoxin.several recent studies have demonstrated that the expression of a cyanobacterial flavodoxin in plants can provide tolerance to a wide range of environmental stresses. indeed, this strategy has been proposed as a potentially powerful biotechnological tool to generate multiple-tolerant crops. to determine whether flavodoxin expression specifically increased tolerance to salt stress and whether it might also preserve legume nitrogen fixation under saline conditions, the flavodoxin gene was introduc ...201020353403
signaling ltps: a new plant ltps sub-family?numerous plant non specific lipid transfer protein (nsltps) have been characterized for their antimicrobial activity, suggesting for these proteins a direct role in the protection against pathogenic microorganisms. another group of ltps seems to be involved in structural events in the extracellular matrix through binding and transport of hydrophobic molecules. more recently, some ltps putatively involved in the symbiotic interaction between legumes and rhizobia have been identified. we investiga ...201020404561
phymatotrichum (cotton) root rot caused by phymatotrichopsis omnivora: retrospects and prospects.phymatotrichum (cotton or texas) root rot is caused by the soil-borne fungus phymatotrichopsis omnivora (duggar) hennebert. the broad host range of the fungus includes numerous crop plants, such as alfalfa and cotton. together with an overview of existing knowledge, this review is aimed at discussing the recent molecular and genomic approaches that have been undertaken to better understand the disease development at the molecular level with the ultimate goal of developing resistant germplasm. ta ...201020447281
infection-specific activation of the medicago truncatula enod11 early nodulin gene promoter during actinorhizal root nodulation.the mtenod11 gene from medicago truncatula is widely used as an early infection-related molecular marker for endosymbiotic associations involving both rhizobia and arbuscular mycorrhizal fungi. in this article, heterologous expression of the mtenod11 promoter has been studied in two actinorhizal trees, casuarina glauca and allocasuarina verticillata. transgenic c. glauca and a. verticillata expressing a promtenod11::beta-glucuronidase (gus) fusion were generated and the activation of the transge ...201020459313
the response to nitric oxide of the nitrogen-fixing symbiont sinorhizobium meliloti.nitric oxide (no) is crucial in animal- and plant-pathogen interactions, during which it participates in host defense response and resistance. indications for the presence of no during the symbiotic interaction between the model legume medicago truncatula and its symbiont sinorhizobium meliloti have been reported but the role of no in symbiosis is far from being elucidated. our objective was to understand the role or roles played by no in symbiosis. as a first step toward this goal, we analyzed ...201020459314
molecular and cytological responses of medicago truncatula to erysiphe pisi.summary powdery mildew is an economically important disease in a number of crop legumes; however, little is known about resistance to the disease in these species. to gain a better understanding of the genetics of resistance and plant responses to powdery mildew in legumes, we developed a pathosystem with medicago truncatula and erysiphe pisi. screening accessions of m. truncatula identified genotypes that are highly susceptible, moderately resistant and highly resistant to the fungus. in the hi ...200720507501
root rot disease of legumes caused by aphanomyces euteiches.the oomycete genus aphanomyces houses plant and animal pathogens found in both terrestrial and aquatic habitats. aphanomyces euteiches drechs. causes seedling damping off and root rot diseases on many legumes. it is the most devastating pea (pisum sativum) disease in several countries, causing up to 80% losses each year. this strictly soil-borne pathogen may survive many years in soil and no efficient chemical control is currently available. the only way to control the disease is to avoid cultiv ...200720507520
improvement of phosphate solubilization and medicago plant yield by an indole-3-acetic acid-overproducing strain of sinorhizobium meliloti.nitrogen (n) and phosphorus (p) are the most limiting factors for plant growth. some microorganisms improve the uptake and availability of n and p, minimizing chemical fertilizer dependence. it has been published that the rd64 strain, a sinorhizobium meliloti 1021 strain engineered to overproduce indole-3-acetic acid (iaa), showed improved nitrogen fixation ability compared to the wild-type 1021 strain. here, we present data showing that rd64 is also highly effective in mobilizing p from insolub ...201020511434
expression pattern suggests a role of mir399 in the regulation of the cellular response to local pi increase during arbuscular mycorrhizal symbiosis.many plants improve their phosphate (pi) availability by forming mutualistic associations with arbuscular mycorrhizal (am) fungi. pi-repleted plants are much less colonized by am fungi than pi-depleted plants. this indicates a link between plant pi signaling and am development. micrornas (mir) of the 399 family are systemic pi-starvation signals important for maintenance of pi homeostasis in arabidopsis thaliana and might also qualify as signals regulating am development in response to pi availa ...201020521954
lack of trehalose catabolism in sinorhizobium species increases their nodulation competitiveness on certain host genotypes.the role of host and bacterial genotypes in determining the competitiveness of trehalose utilization mutants of sinorhizobium meliloti and sinorhizobium medicae was investigated here. trehalose utilization mutants of s. meliloti and s. medicae were obtained by mutagenesis of their trehalose utilization gene thub. the mutant strains and the wild type were coinoculated on three cultivars of alfalfa (medicago sativa) and two cultivars of medicago truncatula and assessed for competitiveness in root ...200819086182
medicago truncatula (e)-beta-ocimene synthase is induced by insect herbivory with corresponding increases in emission of volatile ocimene.virtually all plants are able to recognize attack by herbivorous insects and release volatile organic compounds (voc) in response. terpenes are the most abundant and varied class of insect-induced voc from plants. four genes encoding putative terpene synthases (mttps1, mttps2, mttps3 and mttps4) were shown to accumulate in medicago truncatula gaertn. in response to spodoptera exigua (hübner) feeding and methyl jasmonate treatment in a previous study [s.k. gomez, m.m. cox, j.c. bede, k.k. inoue, ...200919249223
characterization and expression analysis of medicago truncatula rop gtpase family during the early stage of symbiosis.rops (rho-related gtpases of plants) are small gtpases that are plant-specific signaling proteins. they act as molecular switches in a variety of developmental processes. in this study, seven cdna clones coding for rop gtpases have been isolated in medicago truncatula, and conserved and divergent domains are identified in these predicted mtrop proteins. phylogenetic analysis has indicated that mtrops are distributed into groups ii, iii, iv but group i. mtrop genes are expressed in various tissue ...201020590994
non-protein-coding rnas and their interacting rna-binding proteins in the plant cell nucleus.the complex responses of eukaryotic cells to external factors are governed by several transcriptional and post-transcriptional processes. several of them occur in the nucleus and have been linked to the action of non-protein-coding rnas (or npcrnas), both long and small npcrnas, that recently emerged as major regulators of gene expression. regulatory npcrnas acting in the nucleus include silencing-related rnas, intergenic npcrnas, natural antisense rnas, and other aberrant rnas resulting from th ...201020603381
medicago truncatula proteomics.legumes (fabaceae) are unique in their ability to enter into an elaborate symbiosis with nitrogen-fixing rhizobial bacteria. rhizobia-legume (rl) symbiosis represents one of the most productive nitrogen-fixing systems and effectively renders the host plants to be more or less independent of other nitrogen sources. due to high protein content, legumes are among the most economically important crop families. beyond that, legumes consist of over 16,000 species assigned to 650 genera. in most cases, ...201020621211
activation of an alfalfa cyclin-dependent kinase inhibitor by calmodulin-like domain protein kinase.kip-related proteins (krps) play a central role in the regulation of the cell cycle and differentiation through modulation of cyclin-dependent kinase (cdk) functions. we have identified a cdk inhibitor gene from medicago truncatula (mt) by a yeast two-hybrid screen. the krpmt gene was expressed in all plant organs and cultured cells, and its transcripts accumulated after abscisic acid and nacl treatment. the krpmt protein exhibits seven conserved sequence domains and a pest motif that is also de ...200616553899
recombinant artificial forisomes provide ample quantities of smart biomaterials for use in technical devices.forisomes are mechanoproteins that undergo atp-independent contraction-expansion cycles triggered by divalent cations, ph changes, and electrical stimuli. although native forisomes from medicago truncatula comprise a number of subunits encoded by separate genes, here we show that at least two of those subunits (mtseo1 and mtseo4) can assemble into homomeric forisome bodies that are functionally similar to their native, multimeric counterparts. we expressed these subunits in plants and yeast, res ...201020665019
host and nonhost resistance in medicago-colletotrichum interactions.medicago truncatula lines resistant (a17) or susceptible (f83005.5) to the alfalfa pathogen colletotrichum trifolii were used to compare defense reactions induced upon inoculation with c. trifolii or with the nonadapted pathogens c. lindemuthianum and c. higginsianum. nonadapted colletotrichum spp. induced a hypersensitive response (hr)-like reaction similar to the one induced during the host-incompatible interaction. molecular analyses indicated an induction of pr10 and chalcone synthase genes ...201020687801
multiple distinct small rnas originate from the same microrna precursors.micrornas (mirnas), which originate from precursor transcripts with stem-loop structures, are essential gene expression regulators in eukaryotes.201020696037
a comparison of two class 10 pathogenesis-related genes from alfalfa and their activation by multiple stresses and stress-related signaling molecules.a collection of 29 pathogenesis-related 10 (pr10) genes of medicago sativa and medicago truncatula showed that they were almost all obtained from cdna libraries of tissues undergoing abiotic or biotic stresses. the predicted proteins could be divided into two subclasses, pr10.1 and pr10.2, but in silico predicted models of their three-dimensional structures revealed that they could be further divided based on size of the hydrophobic internal cavity and number of β-bulges. a comparison of the exp ...201020703880
the b-3 ethylene response factor mterf1-1 mediates resistance to a subset of root pathogens in medicago truncatula without adversely affecting symbiosis with rhizobia.the fungal necrotrophic pathogen rhizoctonia solani is a significant constraint to a range of crops as diverse as cereals, canola, and legumes. despite wide-ranging germplasm screens in many of these crops, no strong genetic resistance has been identified, suggesting that alternative strategies to improve resistance are required. in this study, we characterize moderate resistance to r. solani anastomosis group 8 identified in medicago truncatula. the activity of the ethylene- and jasmonate-respo ...201020713618
palmate-like pentafoliata1 encodes a novel cys(2)his(2) zinc finger transcription factor essential for compound leaf morphogenesis in medicago truncatula.as the primary site for photosynthetic carbon fixation and the interface between plants and the environment, plant leaves play a key role in plant growth, biomass production and survival, and global carbon and oxygen cycles. leaves can be simple with a single blade or compound with multiple units of blades known as leaflets. in a palmate-type compound leaf, leaflets are clustered at the tip of the leaf. in a pinnate-type compound leaf, on the other hand, leaflets are placed on a rachis in distan ...201020724826
the ethylene-insensitive sickle mutant of medicago truncatula shows altered auxin transport regulation during nodulation.we studied the ethylene-insensitive, hypernodulating mutant, sickle (skl), to investigate the interaction of ethylene with auxin transport during root nodulation in medicago truncatula. grafting experiments demonstrated that hypernodulation in skl is root controlled. long distance transport of auxin from shoot to root was reduced by rhizobia after 24 h in wild type but not in skl. similarly, the ethylene precursor 1-amino cyclopropane-1-carboxylic acid inhibited auxin transport in wild type but ...200616844840
characterization of the medicago truncatula cell wall proteome in cell suspension culture upon elicitation and suppression of plant defense.in addition to establishing methods for proteome analysis of cell wall proteins (cwps) for the model plant medicago truncatula, this work highlights the presence of several protein classes in cell culture. using a combination of two-dimensional gel electrophoresis (2d-page) and/or liquid chromatography-tandem mass spectrometry (lc-ms/ms), we established the proteome reference map of m. truncatula cell wall proteins. cwps extracted from purified cell wall fragments resulted in the identification ...201020801546
biosynthesis of udp-xylose and udp-arabinose in sinorhizobium meliloti 1021: first characterization of a bacterial udp-xylose synthase, and udp-xylose 4-epimerase.sinorhizobium meliloti is a soil bacterium that fixes nitrogen after being established inside nodules that can form on the roots of several legumes, including medicago truncatula. a mutation in an s. meliloti gene (lpsb) required for lipopolysaccharide synthesis has been reported to result in defective nodulation and an increase in the synthesis of a xylose-containing glycan. glycans containing xylose as well as arabinose are also formed by other rhizobial species, but little is known about thei ...201120847005
comparative proteomics of yeast-elicited medicago truncatula cell suspensions reveals induction of isoflavonoid biosynthesis and cell wall modifications.the temporal proteome response of medicago truncatula suspension cell cultures to yeast elicitation (which mimics fungal infection) was investigated using two-dimensional polyacrylamide gel electrophoresis (2-de) and nanoliquid chromatography coupled to tandem mass spectrometry (nano lc-ms/ms). reproducibility of 2-de was assessed using the number of the visualized protein spots and spot volume. average coefficient of variation was determined to be less than 6% for the number of spots and around ...201020853911
stimulation of defense reactions in medicago truncatula by antagonistic lipopeptides from paenibacillus sp. strain b2.with the aim of obtaining new strategies to control plant diseases, we investigated the ability of antagonistic lipopolypeptides (paenimyxin) from paenibacillus sp. strain b2 to elicit hydrogen peroxide (h₂o₂) production and several defense-related genes in the model legume medicago truncatula. for this purpose, m. truncatula cell suspensions were used and a pathosystem between m. truncatula and fusarium acuminatum was established. in m. truncatula cell cultures, the induction of h₂o₂ reached a ...201020870792
medicago truncatula transformation using leaf explants.legumes have long been recalcitrant to efficient agrobacterium tumefaciens-mediated transformation. the choice and use of model legume plants (medicago truncatula and lotus japonicus) for molecular studies has triggered extensive studies devoted to the development of efficient agrobacterium-mediated transformation protocols for these two plants. in m. truncatula, transformation protocols rely on the use of highly regenerable lines obtained by recurrent in vitro culture selection. these protocols ...200616988338
medicago truncatula transformation using cotyledon explants.medicago truncatula has been developed into a model species for legumes. large numbers of ests have been sequenced, and sequencing of the complete gene-rich space of the genotype jemalong a17 is in progress. by using cotyledons as explants for agrobacterium infection and direct shoot formation, this protocol allows for rapid production of transgenic plants from a17 and other genotypes. transgenic plants can be regenerated and established in the greenhouse in only 3-4 mo after agrobacterium-media ...200616988339
the medicago truncatula cre1 cytokinin receptor regulates lateral root development and early symbiotic interaction with sinorhizobium meliloti.legumes develop different types of lateral organs from their primary root, lateral roots and nodules, the latter depending on a symbiotic interaction with sinorhizobium meliloti. phytohormones have been shown to function in the control of these organogeneses. however, related signaling pathways have not been identified in legumes. we cloned and characterized the expression of medicago truncatula genes encoding members of cytokinin signaling pathways. rna interference of the cytokinin receptor ho ...200617028204
induction of distinct defense-associated protein patterns in aphanomyces euteiches (oomycota)-elicited and -inoculated medicago truncatula cell-suspension cultures: a proteome and phosphoproteome approach.a comprehensive proteomic approach was applied to investigate molecular events occurring upon inoculation of medicago truncatula cell-suspension cultures with the oomycete root pathogen aphanomyces euteiches. establishment of an inoculation assay in the cell cultures allowed a direct comparison between proteins induced by elicitation with a crude culture extract of the oomycete and by inoculation with a. euteiches zoospores representing the natural infection carrier. oxidative burst assays revea ...200919271957
the lap1 myb transcription factor orchestrates anthocyanidin biosynthesis and glycosylation in medicago.myb transcription factors help to control anthocyanin biosynthesis in plants, and ectopic expression of the arabidopsis production of anthocyanin pigment 1 (pap1) transcription factor activates the anthocyanin pathway in tobacco, suggesting the general utility of such factors for metabolic engineering of anthocyanins and anthocyanin-derived compounds such as proanthocyanidins (condensed tannins). however, pap1 does not activate anthocyanin biosynthesis in the model legume medicago truncatula or ...200919368693
identification of qtl affecting seed mineral concentrations and content in the model legume medicago truncatula.increasing the amount of bioavailable micronutrients such as iron and zinc in plant foods for human consumption is an international goal, intended especially for developing countries where micronutrient deficiencies are an ongoing health risk. legume seeds have the potential to provide the essential nutrients required by humans, but concentrations of several minerals are low when compared to other foods. in order to increase seed mineral concentrations, it is important to understand the genes an ...200919396421
annexins - calcium- and membrane-binding proteins in the plant kingdom: potential role in nodulation and mycorrhization in medicago truncatula.annexins belong to a family of multi-functional membrane- and ca(2+)-binding proteins. the characteristic feature of these proteins is that they can bind membrane phospholipids in a reversible, ca(2+)-dependent manner. while animal annexins have been known for a long time and are fairly well characterized, their plant counterparts were discovered only in 1989, in tomato, and have not been thoroughly studied yet. in the present review, we discuss the available information about plant annexins wit ...200919421430
transcriptome analysis of a bacterially induced basal and hypersensitive response of medicago truncatula.research using the well-studied model legume medicago truncatula has largely focused on rhizobium symbiosis, while little information is currently available for this species on pathogen-induced transcriptome changes. we have performed a transcriptome analysis of this species with the objective of studying the basal (br, no visible symptoms) and hypersensitive response (hr, plant cell death) in its leaves at 6 and at 24 h after infection by hr-negative (hrcc mutant) and hr-inducing pseudomonas sy ...200919466566
enod40 gene expression and cytokinin responses in the nonnodulating, nonmycorrhizal (nodmyc) mutant, masym3, of melilotus alba desr.several nonnodulating, nonmycorrhizal (nod(-)myc(-)) mutants of melilotus alba desr. (white sweetclover) have been described. however, the details of their responses to sinorhizobium meliloti have not been fully elucidated. we investigated rhizobial entry and colonization using confocal scanning laser microscopy on the masym1-5 mutants and isolated an early nodulin (enod40) gene from wild-type m. alba. we focused on masym3, the least responsive of the mutants to s. meliloti and va-fungi, to dete ...200719516966
differential expression proteomics to investigate responses and resistance to orobanche crenata in medicago truncatula.parasitic angiosperm orobanche crenata infection represents a major constraint for the cultivation of legumes worldwide. the level of protection achieved to date is either incomplete or ephemeral. hence, an efficient control of the parasite requires a better understanding of its interaction and associated resistance mechanisms at molecular levels.200919575787
mate transporters facilitate vacuolar uptake of epicatechin 3'-o-glucoside for proanthocyanidin biosynthesis in medicago truncatula and arabidopsis.expression of the arabidopsis thaliana myb transcription factor transparent testa 2 (tt2) in medicago trunculata hairy roots induces both proanthocyanidin accumulation and the atp-dependent vacuolar/vesicular uptake of epicatechin 3'-o-glucoside; neither process is active in control roots that do, however, possess anthocyanidin 3-o-glucoside vacuolar uptake activity. a vacuolar membrane-localized multidrug and toxic compound extrusion (mate) transporter, medicago mate1, was identified at the mol ...200919684242
osmotic shock improves tnt1 transposition frequency in medicago truncatula cv jemalong during in vitro regeneration.insertion mutant collections are powerful tools for genetic studies in plants. although large-scale insertional mutagenesis using t-dna is not feasible in legumes, the tnt1 tobacco retrotransposon can be used as a very efficient mutagen in the medicago truncatula r108 genotype. in this article, we show that tnt1 can also be exploited to create insertional mutants via transformation and/or regeneration in the reference cultivar jemalong. tnt1 insertional mutagenesis in jemalong following agrobact ...200919688215
plant flotillins are required for infection by nitrogen-fixing bacteria.to establish compatible rhizobial-legume symbioses, plant roots support bacterial infection via host-derived infection threads (its). here, we report the requirement of plant flotillin-like genes (flots) in sinorhizobium meliloti infection of its host legume medicago truncatula. flotillins in other organisms have roles in viral pathogenesis, endocytosis, and membrane shaping. we identified seven flot genes in the m. truncatula genome and show that two, flot2 and flot4, are strongly up-regulated ...201020018678
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