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a phylogenetically conserved group of nuclear factor-y transcription factors interact to control nodulation in legumes.the endosymbiotic association between legumes and soil bacteria called rhizobia leads to the formation of a new root-derived organ called the nodule in which differentiated bacteria convert atmospheric nitrogen into a form that can be assimilated by the host plant. successful root infection by rhizobia and nodule organogenesis require the activation of symbiotic genes that are controlled by a set of transcription factors (tfs). we recently identified medicago truncatula nuclear factor-ya1 (mtnf- ...201526432878
the transcriptional repressor myb2 regulates both spatial and temporal patterns of proanthocyandin and anthocyanin pigmentation in medicago truncatula.accumulation of anthocyanins and proanthocyanidins (pas) is limited to specific cell types and developmental stages, but little is known about how antagonistically acting transcriptional regulators work together to determine temporal and spatial patterning of pigmentation at the cellular level, especially for pas. here, we characterize myb2, a transcriptional repressor regulating both anthocyanin and pa biosynthesis in the model legume medicago truncatula. myb2 was strongly upregulated by myb5, ...201526410301
loss of the nodule-specific cysteine rich peptide, ncr169, abolishes symbiotic nitrogen fixation in the medicago truncatula dnf7 mutant.host compatible rhizobia induce the formation of legume root nodules, symbiotic organs within which intracellular bacteria are present in plant-derived membrane compartments termed symbiosomes. in medicago truncatula nodules, the sinorhizobium microsymbionts undergo an irreversible differentiation process leading to the development of elongated polyploid noncultivable nitrogen fixing bacteroids that convert atmospheric dinitrogen into ammonia. this terminal differentiation is directed by the hos ...201526401023
knotted1-like homeobox 3: a new regulator of symbiotic nodule development.knox transcription factors (tfs) regulate different aspects of plant development essentially through their effects on phytohormone metabolism. in particular, knox tf shootmeristemless activates the cytokinin biosynthesis isopentenyl transferase (ipt) genes in the shoot apical meristem. however, the role of knox tfs in symbiotic nodule development and their possible effects on phytohormone metabolism during nodulation have not been studied to date. cytokinin is a well-known regulator of nodule de ...201526351356
flavonoids and auxin transport inhibitors rescue symbiotic nodulation in the medicago truncatula cytokinin perception mutant cre1.initiation of symbiotic nodules in legumes requires cytokinin signaling, but its mechanism of action is largely unknown. here, we tested whether the failure to initiate nodules in the medicago truncatula cytokinin perception mutant cre1 (cytokinin response1) is due to its altered ability to regulate auxin transport, auxin accumulation, and induction of flavonoids. we found that in the cre1 mutant, symbiotic rhizobia cannot locally alter acro- and basipetal auxin transport during nodule initiatio ...201526253705
a role for the mevalonate pathway in early plant symbiotic signaling.rhizobia and arbuscular mycorrhizal fungi produce signals that are perceived by host legume receptors at the plasma membrane and trigger sustained oscillations of the nuclear and perinuclear ca(2+) concentration (ca(2+) spiking), which in turn leads to gene expression and downstream symbiotic responses. the activation of ca(2+) spiking requires the plasma membrane-localized receptor-like kinase does not make infections 2 (dmi2) as well as the nuclear cation channel dmi1. a key enzyme regulating ...201526199419
deep sequencing of the medicago truncatula root transcriptome reveals a massive and early interaction between nodulation factor and ethylene signals.the legume-rhizobium symbiosis is initiated through the activation of the nodulation (nod) factor-signaling cascade, leading to a rapid reprogramming of host cell developmental pathways. in this work, we combine transcriptome sequencing with molecular genetics and network analysis to quantify and categorize the transcriptional changes occurring in roots of medicago truncatula from minutes to days after inoculation with sinorhizobium medicae. to identify the nature of the inductive and regulatory ...201526175514
suppression of arbuscule degeneration in medicago truncatula phosphate transporter4 mutants is dependent on the ammonium transporter 2 family protein amt2;3.during arbuscular mycorrhizal (am) symbiosis, the plant gains access to phosphate (pi) and nitrogen delivered by its fungal symbiont. transfer of mineral nutrients occurs at the interface between branched hyphae called arbuscules and root cortical cells. in medicago truncatula, a pi transporter, pt4, is required for symbiotic pi transport, and in pt4, symbiotic pi transport fails, arbuscules degenerate prematurely, and the symbiosis is not maintained. premature arbuscule degeneration (pad) is su ...201525841038
medicago truncatula natural resistance-associated macrophage protein1 is required for iron uptake by rhizobia-infected nodule cells.iron is critical for symbiotic nitrogen fixation (snf) as a key component of multiple ferroproteins involved in this biological process. in the model legume medicago truncatula, iron is delivered by the vasculature to the infection/maturation zone (zone ii) of the nodule, where it is released to the apoplast. from there, plasma membrane iron transporters move it into rhizobia-containing cells, where iron is used as the cofactor of multiple plant and rhizobial proteins (e.g. plant leghemoglobin a ...201525818701
the small gtpase rop10 of medicago truncatula is required for both tip growth of root hairs and nod factor-induced root hair deformation.rhizobia preferentially enter legume root hairs via infection threads, after which root hairs undergo tip swelling, branching, and curling. however, the mechanisms underlying such root hair deformation are poorly understood. here, we showed that a type ii small gtpase, rop10, of medicago truncatula is localized at the plasma membrane (pm) of root hair tips to regulate root hair tip growth. overexpression of rop10 and a constitutively active mutant (rop10ca) generated depolarized growth of root h ...201525794934
activation of symbiosis signaling by arbuscular mycorrhizal fungi in legumes and rice.establishment of arbuscular mycorrhizal interactions involves plant recognition of diffusible signals from the fungus, including lipochitooligosaccharides (lcos) and chitooligosaccharides (cos). nitrogen-fixing rhizobial bacteria that associate with leguminous plants also signal to their hosts via lcos, the so-called nod factors. here, we have assessed the induction of symbiotic signaling by the arbuscular mycorrhizal (myc) fungal-produced lcos and cos in legumes and rice (oryza sativa). we show ...201525724637
novel mtcep1 peptides produced in vivo differentially regulate root development in medicago truncatula.small, post-translationally modified and secreted peptides regulate diverse plant developmental processes. due to low natural abundance, it is difficult to isolate and identify these peptides. using an improved peptide isolation protocol and orbitrap mass spectrometry, nine 15-amino-acid cep peptides were identified that corresponded to the two domains encoded by medicago truncatula cep1 (mtcep1). novel arabinosylated and hydroxylated peptides were identified in root cultures overexpressing mtce ...201525711701
remodeling of the infection chamber before infection thread formation reveals a two-step mechanism for rhizobial entry into the host legume root hair.in many legumes, root entry of symbiotic nitrogen-fixing rhizobia occurs via host-constructed tubular tip-growing structures known as infection threads (its). here, we have used a confocal microscopy live-tissue imaging approach to investigate early stages of it formation in medicago truncatula root hairs (rhs) expressing fluorescent protein fusion reporters. this has revealed that its only initiate 10 to 20 h after the completion of rh curling, by which time major modifications have occurred wi ...201525659382
network of gras transcription factors involved in the control of arbuscule development in lotus japonicus.arbuscular mycorrhizal (am) fungi, in symbiosis with plants, facilitate acquisition of nutrients from the soil to their host. after penetration, intracellular hyphae form fine-branched structures in cortical cells termed arbuscules, representing the major site where bidirectional nutrient exchange takes place between the host plant and fungus. transcriptional mechanisms underlying this cellular reprogramming are still poorly understood. gras proteins are an important family of transcriptional re ...201525560877
chemical induction of hairpin rnai molecules to silence vital genes in plant roots.understanding the functions encoded by plant genes can be facilitated by reducing transcript levels by hairpin rna (hprna) mediated silencing. a bottleneck to this technology occurs when a gene encodes a phenotype that is necessary for cell viability and silencing the gene inhibits transformation. here we compared the use of two chemically inducible plant promoter systems to drive hprna mediated gene silencing in transgenic, hairy roots. we cloned the gene encoding the yellow fluorescence protei ...201627898105
della-mediated gibberellin signalling regulates nod factor signalling and rhizobial infection.legumes develop symbiotic interactions with rhizobial bacteria to form nitrogen-fixing nodules. bacterial nod factors (nfs) and plant regulatory pathways modulating nf signalling control rhizobial infections and nodulation efficiency. here we show that gibberellin (ga) signalling mediated by della proteins inhibits rhizobial infections and controls the nf induction of the infection marker enod11 in medicago truncatula. ectopic expression of a constitutively active della protein in the epidermis ...201627586842
della proteins are common components of symbiotic rhizobial and mycorrhizal signalling pathways.legumes form symbiotic associations with either nitrogen-fixing bacteria or arbuscular mycorrhizal fungi. formation of these two symbioses is regulated by a common set of signalling components that act downstream of recognition of rhizobia or mycorrhizae by host plants. central to these pathways is the calcium and calmodulin-dependent protein kinase (ccamk)-ipd3 complex which initiates nodule organogenesis following calcium oscillations in the host nucleus. however, downstream signalling events ...201627514472
a snapshot of functional genetic studies in medicago truncatula.in the current context of food security, increase of plant protein production in a sustainable manner represents one of the major challenges of agronomic research, which could be partially resolved by increased cultivation of legume crops. medicago truncatula is now a well-established model for legume genomic and genetic studies. with the establishment of genomics tools and mutant populations in m. truncatula, it has become an important resource to answer some of the basic biological questions r ...201627555857
different pathways act downstream of the cep peptide receptor cra2 to regulate lateral root and nodule development.c-terminally encoded peptides (ceps) control root system architecture in a non-cell-autonomous manner. in medicago truncatula, mtcep1 affects root development by increasing nodule formation and inhibiting lateral root emergence by unknown pathways. here, we show that the mtcep1 peptide-dependent increase in nodulation requires the symbiotic signaling pathway and ethylene insensitive2 (ein2)/sickle (skl), but acts independently of super numeric nodules. mtcep1-dependent inhibition of lateral root ...201627342310
a laser dissection-rnaseq analysis highlights the activation of cytokinin pathways by nod factors in the medicago truncatula root epidermis.nod factors (nfs) are lipochitooligosaccharidic signal molecules produced by rhizobia, which play a key role in the rhizobium-legume symbiotic interaction. in this study, we analyzed the gene expression reprogramming induced by purified nf (4 and 24 h of treatment) in the root epidermis of the model legume medicago truncatula tissue-specific transcriptome analysis was achieved by laser-capture microdissection coupled to high-depth rna sequencing. the expression of 17,191 genes was detected in th ...201627217496
the symbiosis-related ern transcription factors act in concert to coordinate rhizobial host root infection.legumes improve their mineral nutrition through nitrogen-fixing root nodule symbioses with soil rhizobia. rhizobial infection of legumes is regulated by a number of transcription factors, including erf required for nodulation1 (ern1). medicago truncatula plants defective in ern1 are unable to nodulate, but still exhibit early symbiotic responses including rhizobial infection. ern1 has a close homolog, ern2, which shows partially overlapping expression patterns. here we show that ern2 mutants exh ...201627208242
nadph oxidases in the arbuscular mycorrhizal symbiosis.plant nadph oxidases are the major source of reactive oxygen species (ros) that plays key roles as both signal and stressor in several plant processes, including defense responses against pathogens. ros accumulation in root cells during arbuscular mycorrhiza (am) development has raised the interest in understanding how ros-mediated defense programs are modulated during the establishment of this mutualistic interaction. we have recently analyzed the expression pattern of 5 nadph oxidase (also cal ...201627018627
mtsweet11, a nodule-specific sucrose transporter of medicago truncatula.optimization of nitrogen fixation by rhizobia in legumes is a key area of research for sustainable agriculture. symbiotic nitrogen fixation (snf) occurs in specialized organs called nodules and depends on a steady supply of carbon to both plant and bacterial cells. here we report the functional characterization of a nodule-specific suc transporter, mtsweet11 from medicago truncatula mtsweet11 belongs to a clade of plant sweet proteins that are capable of transporting suc and play critical roles ...201627021190
a medicago truncatula cystathionine-β-synthase-like domain-containing protein is required for rhizobial infection and symbiotic nitrogen fixation.the symbiosis between leguminous plants and soil rhizobia culminates in the formation of nitrogen-fixing organs called nodules that support plant growth. two medicago truncatula tnt1-insertion mutants were identified that produced small nodules, which were unable to fix nitrogen effectively due to ineffective rhizobial colonization. the gene underlying this phenotype was found to encode a protein containing a putative membrane-localized domain of unknown function (duf21) and a cystathionine-β-sy ...201626884486
medicago truncatula gaertn. as a model for understanding the mechanism of growth promotion by bacteria from rhizosphere and nodules of alfalfa.the present study showed all the 16 strains isolated and identified from the alfalfa rhizosphere and nodules, and registered in genbank, to be good candidates for targeted use in studies addressing the rather weak known mechanism of plant growth promotion, including that of medicago truncatula, a molecular crop model. based on physiological, biochemical and molecular analysis, the 16 isolates obtained were ascribed to the following five families: bacillaceae, rhizobiaceae, xantomonadaceae, enter ...201626861677
metabolic engineering of proanthocyanidin production by repressing the isoflavone pathways and redirecting anthocyanidin precursor flux in legume.mtpar is a proanthocyanidin (pa) biosynthesis regulator; the mechanism underlying its promotion of pa biosynthesis is not fully understood. here, we showed that mtpar promotes pa production by a direct repression of biosynthesis of isoflavones, the major flavonoids in legume, and by redirecting immediate precursors, such as anthocyanidins, flux into pa pathway. ectopic expression of mtpar repressed isoflavonoid production by directly binding and suppressing isoflavone biosynthetic genes such as ...201626806316
a diffusible signal from arbuscular mycorrhizal fungi elicits a transient cytosolic calcium elevation in host plant cells.the implication of calcium as intracellular messenger in the arbuscular mycorrhizal (am) symbiosis has not yet been directly demonstrated, although often envisaged. we used soybean (glycine max) cell cultures stably expressing the bioluminescent ca(2+) indicator aequorin to detect intracellular ca(2+) changes in response to the culture medium of spores of gigaspora margarita germinating in the absence of the plant partner. rapid and transient elevations in cytosolic free ca(2+) were recorded, in ...200717142489
responses of the model legume medicago truncatula to the rhizobial exopolysaccharide succinoglycan.many species of rhizobial bacteria can invade their plant hosts and induce development of symbiotic nitrogen-fixing nodules only if they are able to produce an acidic exopolysaccharide (eps) with certain structural and molecular weight characteristics.1-3sinorhizobium meliloti that produces the functional form of the exopolysaccharide succinoglycan induces formation of invasion structures called infection threads in the root hair cells of its plant hosts alfalfa and medicago truncatula. however, ...200819704531
transcriptional analysis of highly syntenic regions between medicago truncatula and glycine max using tiling microarrays.legumes are the third largest family of flowering plants and are unique among crop species in their ability to fix atmospheric nitrogen. as a result of recent genome sequencing efforts, legumes are now one of a few plant families with extensive genomic and transcriptomic data available in multiple species. the unprecedented complexity and impending completeness of these data create opportunities for new approaches to discovery.200818348734
transcriptional profiling of medicago truncatula meristematic root cells.the root apical meristem of crop and model legume medicago truncatula is a significantly different stem cell system to that of the widely studied model plant species arabidopsis thaliana. in this study we used the affymetrix medicago genechip(r) to compare the transcriptomes of meristem and non-meristematic root to identify root meristem specific candidate genes.200818302802
genome-wide medicago truncatula small rna analysis revealed novel micrornas and isoforms differentially regulated in roots and nodules.posttranscriptional regulation of a variety of mrnas by small 21- to 24-nucleotide rnas, notably the micrornas (mirnas), is emerging as a novel developmental mechanism. in legumes like the model medicago truncatula, roots are able to develop a de novo meristem through the symbiotic interaction with nitrogen-fixing rhizobia. we used deep sequencing of small rnas from root apexes and nodules of m. truncatula to identify 100 novel candidate mirnas encoded by 265 hairpin precursors. new atypical pre ...200919767456
comparative evolution of photosynthetic genes in response to polyploid and nonpolyploid duplication.the likelihood of duplicate gene retention following polyploidy varies by functional properties (e.g. gene ontologies or protein family domains), but little is known about the effects of whole-genome duplication on gene networks related by a common physiological process. here, we examined the effects of both polyploid and nonpolyploid duplications on genes encoding the major functional groups of photosynthesis (photosystem i, photosystem ii, the light-harvesting complex, and the calvin cycle) in ...201121289102
promex - a mass spectral reference database for plant proteomics.the promex database is one of the main collection of annotated tryptic peptides in plant proteomics. the main objective of the promex database is to provide experimental ms/ms-based information for cell type-specific or sub-cellular proteomes in arabidopsis thaliana, medicago truncatula, chlamydomonas reinhardtii, lotus japonicus, lotus corniculatus, phaseolus vulgaris, lycopersicon esculentum, solanum tuberosum, nicotiana tabacum, glycine max, zea mays, bradyrhizobium japonicum, and sinorhizobi ...201222685450
iron: an essential micronutrient for the legume-rhizobium symbiosis.legumes, which develop a symbiosis with nitrogen-fixing bacteria, have an increased demand for iron. iron is required for the synthesis of iron-containing proteins in the host, including the highly abundant leghemoglobin, and in bacteroids for nitrogenase and cytochromes of the electron transport chain. deficiencies in iron can affect initiation and development of the nodule. within root cells, iron is chelated with organic acids such as citrate and nicotianamine and distributed to other parts o ...201324062758
comprehensive characterization and rna-seq profiling of the hd-zip transcription factor family in soybean (glycine max) during dehydration and salt stress.the homeodomain leucine zipper (hd-zip) transcription factor family is one of the largest plant specific superfamilies, and includes genes with roles in modulation of plant growth and response to environmental stresses. many hd-zip genes are characterized in arabidopsis (arabidopsis thaliana), and members of the family are being investigated for abiotic stress responses in rice (oryza sativa), maize (zea mays), poplar (populus trichocarpa) and cucumber (cucmis sativus). findings in these species ...201425362847
identification of a dominant gene in medicago truncatula that restricts nodulation by sinorhizobium meliloti strain rm41.leguminous plants are able to form a root nodule symbiosis with nitrogen-fixing soil bacteria called rhizobia. this symbiotic association shows a high level of specificity. beyond the specificity for the legume family, individual legume species/genotypes can only interact with certain restricted group of bacterial species or strains. specificity in this system is regulated by complex signal exchange between the two symbiotic partners and thus multiple genetic mechanisms could be involved in the ...201424934080
an alternative approach to "identification of unknowns": designing a protocol to verify the identities of nitrogen fixing bacteria.microbiology courses often include a laboratory activity on the identification of unknown microbes. this activity consists of providing students with microbial cultures and running biochemical assays to identify the organisms. this approach lacks molecular techniques such as sequencing of genes encoding 16s rrna, which is currently the method of choice for identification of unknown bacteria. a laboratory activity was developed to teach students how to identify microorganisms using 16s rrna polym ...201526753033
medicago truncatula and glycine max: different drought tolerance and similar local response of the root nodule proteome.legume crops present important agronomical and environmental advantages mainly due to their capacity to reduce atmospheric n2 to ammonium via symbiotic nitrogen fixation (snf). this process is very sensitive to abiotic stresses such as drought, but the mechanism underlying this response is not fully understood. the goal of the current work is to compare the drought response of two legumes with high economic impact and research importance, medicago truncatula and glycine max, by characterizing th ...201526503705
genomic signature of selective sweeps illuminates adaptation of medicago truncatula to root-associated microorganisms.medicago truncatula is a model legume species used to investigate plant-microorganism interactions, notably root symbioses. massive population genomic and transcriptomic data now available for this species open the way for a comprehensive investigation of genomic variations associated with adaptation of m. truncatula to its environment. here we performed a fine-scale genome scan of selective sweep signatures in m. truncatula using more than 15 million single nucleotide polymorphisms identified o ...201525901015
multiple steps control immunity during the intracellular accommodation of rhizobia.medicago truncatula belongs to the legume family and forms symbiotic associations with nitrogen fixing bacteria, the rhizobia. during these interactions, the plants develop root nodules in which bacteria invade the plant cells and fix nitrogen for the benefit of the plant. despite massive infection, legume nodules do not develop visible defence reactions, suggesting a special immune status of these organs. some factors influencing rhizobium maintenance within the plant cells have been previously ...201525682610
six medicago truncatula dicer-like protein genes are expressed in plant cells and upregulated in nodules.here we report the existence of six putative dicer-like genes in the medicago truncatula genome. they are ubiquitously expressed throughout the plant and significantly induced in root nodules. over the past decade, small noncoding rnas (sncrna) have emerged as widespread and important regulatory molecules influencing both the structure and expression of plant genomes. one of the key factors involved in sncrna biogenesis in plants is a group of rnase iii-type nucleases known as dicer-like (dcl) p ...201626825594
comprehensive comparative genomic and transcriptomic analyses of the legume genes controlling the nodulation process.nitrogen is one of the most essential plant nutrients and one of the major factors limiting crop productivity. having the goal to perform a more sustainable agriculture, there is a need to maximize biological nitrogen fixation, a feature of legumes. to enhance our understanding of the molecular mechanisms controlling the interaction between legumes and rhizobia, the symbiotic partner fixing and assimilating the atmospheric nitrogen for the plant, researchers took advantage of genetic and genomic ...201626858743
extracellular atp in plants. visualization, localization, and analysis of physiological significance in growth and signaling.extracellular atp (eatp) in animals is well documented and known to play an important role in cellular signaling (e.g. at the nerve synapse). the existence of eatp has been postulated in plants; however, there is no definitive experimental evidence for its presence or an explanation as to how such a polar molecule could exit the plant cell and what physiological role it may play in plant growth and development. the presence of eatp in plants (medicago truncatula) was detected by constructing a n ...200616963521
tracing nonlegume orthologs of legume genes required for nodulation and arbuscular mycorrhizal symbioses.most land plants can form a root symbiosis with arbuscular mycorrhizal (am) fungi for assimilation of inorganic phosphate from the soil. in contrast, the nitrogen-fixing root nodule symbiosis is almost completely restricted to the legumes. the finding that the two symbioses share common signaling components in legumes suggests that the evolutionarily younger nitrogen-fixing symbiosis has recruited functions from the more ancient am symbiosis. the recent advances in cloning of the genes required ...200616452143
small rna pathways and diversity in model legumes: lessons from genomics.small non-coding rnas (smrna) participate in the regulation of development, cell differentiation, adaptation to environmental constraints and defense responses in plants. they negatively regulate gene expression by degrading specific mrna targets, repressing their translation or modifying chromatin conformation through homologous interaction with target loci. micrornas (mirna) and short-interfering rnas (sirna) are generated from long double stranded rna (dsrna) that are cleaved into 20-24-nucle ...201323847640
hormonal control of lateral root and nodule development in legumes.many plants can establish symbioses with nitrogen-fixing bacteria, some of which lead to nodulation, including legumes. indeed, in the rhizobium/legume symbiosis, new root organs, called nodules, are formed by the plant in order to host the rhizobia in protective conditions, optimized for nitrogen fixation. in this way, these plants can benefit from the reduction of atmospheric dinitrogen into ammonia by the hosted bacteria, and in exchange the plant provides the rhizobia with a carbon source. s ...201527135340
cell surface expansion in polarly growing root hairs of medicago truncatula.fluorescent microspheres were used as material markers to investigate the relative rates of cell surface expansion at the growing tips of medicago truncatula root hairs. from the analysis of tip shape and microsphere movements, we propose three characteristic zones of expansion in growing root hairs. the center of the apical dome is an area of 1- to 2- microm diameter with relatively constant curvature and high growth rate. distal to the apex is a more rapidly expanding region 1 to 2 microm in w ...200011080274
production and characterization of diverse developmental mutants of medicago truncatula.the diploid annual legume medicago truncatula has been developed as a tractable genetic system for studying biological questions that are unique to, or well suited for study in legume species. an efficient mutagenesis protocol using ethyl-methyl sulfonate and a polymorphic ecotype with properties appropriate for use as a mapping parent are described. isolation and characterization of three developmental mutants are described. the mtapetala mutation results in homeotic conversions of floral organ ...200010938356
translational and structural requirements of the early nodulin gene enod40, a short-open reading frame-containing rna, for elicitation of a cell-specific growth response in the alfalfa root cortex.a diversity of mrnas containing only short open reading frames (sorf-rnas; encoding less than 30 amino acids) have been shown to be induced in growth and differentiation processes. the early nodulin gene enod40, coding for a 0.7-kb sorf-rna, is expressed in the nodule primordium developing in the root cortex of leguminous plants after infection by symbiotic bacteria. ballistic microtargeting of this gene into medicago roots induced division of cortical cells. translation of two sorfs (i and ii, ...200111113209
nodule initiation involves the creation of a new symplasmic field in specific root cells of medicago species.the organogenesis of nitrogen-fixing nodules in legume plants is initiated in specific root cortical cells and regulated by long-distance signaling and carbon allocation. here, we explore cell-to-cell communication processes that occur during nodule initiation in medicago species and their functional relevance using a combination of fluorescent tracers, electron microscopy, and transgenic plants. nodule initiation induced symplasmic continuity between the phloem and nodule initials. macromolecul ...200314615602
nod factor inhibition of reactive oxygen efflux in a host legume.hydrogen peroxide (h(2)o(2)) efflux was measured from medicago truncatula root segments exposed to purified nod factor and to poly-galua (pga) heptamers. nod factor, at concentrations > 100 pm, reduced h(2)o(2) efflux rates to 60% of baseline levels beginning 20 to 30 min after exposure, whereas the pga elicitor, at > 75 nm, caused a rapid increase in h(2)o(2) efflux to >200% of baseline rates. pretreatment of plants with nod factor alters the effect of pga by limiting the maximum h(2)o(2) efflu ...200312913174
mapping the proteome of barrel medic (medicago truncatula).a survey of six organ-/tissue-specific proteomes of the model legume barrel medic (medicago truncatula) was performed. two-dimensional polyacrylamide gel electrophoresis reference maps of protein extracts from leaves, stems, roots, flowers, seed pods, and cell suspension cultures were obtained. five hundred fifty-one proteins were excised and 304 proteins identified using peptide mass fingerprinting and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. nanoscale high- ...200312644662
dual genetic pathways controlling nodule number in medicago truncatula.we report the isolation and characterization of a new medicago truncatula hyper-nodulation mutant, designated sunn (super numeric nodules). similar to the previously described ethylene-insensitive mutant sickle, sunn exhibits a 10-fold increase in the number of nodules within the primary nodulation zone. despite this general similarity, these two mutants are readily distinguished based on anatomical, genetic, physiological, and molecular criteria. in contrast to sickle, where insensitivity to et ...200312644652
computational identification and characterization of novel genes from legumes.the fabaceae, the third largest family of plants and the source of many crops, has been the target of many genomic studies. currently, only the grasses surpass the legumes for the number of publicly available expressed sequence tags (ests). the quantity of sequences from diverse plants enables the use of computational approaches to identify novel genes in specific taxa. we used blast algorithms to compare unigene sets from medicago truncatula, lotus japonicus, and soybean (glycine max and glycin ...200415266052
a ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: gene identification by transcript-based cloning.in the establishment of the legume-rhizobial symbiosis, bacterial lipochitooligosaccharide signaling molecules termed nod factors activate the formation of a novel root organ, the nodule. nod factors elicit several responses in plant root hair cells, including oscillations in cytoplasmic calcium levels (termed calcium spiking) and alterations in root hair growth. a number of plant mutants with defects in the nod factor signaling pathway have been identified. one such medicago truncatula mutant, ...200415070781
functional analysis of members of the isoflavone and isoflavanone o-methyltransferase enzyme families from the model legume medicago truncatula.previous studies have identified two distinct o-methyltransferases (omts) implicated in isoflavonoid biosynthesis in medicago species, a 7-omt methylating the a-ring 7-hydroxyl of the isoflavone daidzein and a 4'-omt methylating the b-ring 4'-hydroxyl of 2,7,4'-trihydroxyisoflavanone. genes related to these omts from the model legume medicago truncatula cluster as separate branches of the type i plant small molecule omt family. to better understand the possible functions of these related omts in ...200617001495
aging in legume symbiosis. a molecular view on nodule senescence in medicago truncatula.rhizobia reside as symbiosomes in the infected cells of legume nodules to fix atmospheric nitrogen. the symbiotic relation is strictly controlled, lasts for some time, but eventually leads to nodule senescence. we present a comprehensive transcriptomics study to understand the onset of nodule senescence in the legume medicago truncatula. distinct developmental stages with characteristic gene expression were delineated during which the two symbiotic partners were degraded consecutively, marking t ...200616648219
the agc kinase mtire: a link to phospholipid signaling during nodulation?the development of nitrogen fixing root nodules is complex and involves an interplay of signaling processes. during maturation of plant host cells and their endocytosed rhizobia in symbiosomes, host cells and symbiosomes expand. this expansion is accompanied by a large quantity of membrane biogenesis. we recently characterized an agc kinase gene, mtire, that could play a role in this expansion. mtire's expression coincides with host cell and symbiosome expansion in the proximal side of the invas ...200719704633
identification of transcription factors involved in root apex responses to salt stress in medicago truncatula.the root apex contains meristematic cells that determine root growth and architecture in the soil. specific transcription factor (tf) genes in this region may integrate endogenous signals and external cues to achieve this. early changes in transcriptional responses involving tf genes after a salt stress in medicago truncatula (mt) roots were analysed using two complementary transcriptomic approaches. forty-six salt-regulated tf genes were identified using massive quantitative real-time rt-pcr tf ...200818987888
genome-wide transcriptional analysis of super-embryogenic medicago truncatula explant cultures.the medicago truncatula (m. truncatula) line 2ha has a 500-fold greater capacity to regenerate plants in culture by somatic embryogenesis than its wild type progenitor jemalong. to understand the molecular basis for the regeneration capacity of this super-embryogenic line 2ha, using affymetrix genechip(r), we have compared transcriptomes of explant leaf cultures of these two lines that were grown on media containing the auxin naa (1-naphthaleneacetic acid) and the cytokinin bap (6-benzylaminopur ...200818950541
a community resource for high-throughput quantitative rt-pcr analysis of transcription factor gene expression in medicago truncatula.medicago truncatula is a model legume species that is currently the focus of an international genome sequencing effort. although several different oligonucleotide and cdna arrays have been produced for genome-wide transcript analysis of this species, intrinsic limitations in the sensitivity of hybridization-based technologies mean that transcripts of genes expressed at low-levels cannot be measured accurately with these tools. amongst such genes are many encoding transcription factors (tfs), whi ...200818611268
trans-regulation of the expression of the transcription factor mthap2-1 by a uorf controls root nodule development.mthap2-1 is a ccaat-binding transcription factor from the model legume medicago truncatula. we previously showed that mthap2-1 expression is regulated both spatially and temporally by microrna169. here we present a novel regulatory mechanism controlling mthap2-1 expression. alternative splicing of an intron in the mthap2-1 5'leader sequence (ls) becomes predominant during the development of root nodules, leading to the production of a small peptide, uorf1p. our results indicate that binding of u ...200818519645
genomic inventory and transcriptional analysis of medicago truncatula transporters.transporters move hydrophilic substrates across hydrophobic biological membranes and play key roles in plant nutrition, metabolism, and signaling and, consequently, in plant growth, development, and responses to the environment. to initiate and support systematic characterization of transporters in the model legume medicago truncatula, we identified 3,830 transporters and classified 2,673 of these into 113 families and 146 subfamilies. analysis of gene expression data for 2,611 of these transpor ...200920023147
truncatulix--a data warehouse for the legume community.databases for either sequence, annotation, or microarray experiments data are extremely beneficial to the research community, as they centrally gather information from experiments performed by different scientists. however, data from different sources develop their full capacities only when combined. the idea of a data warehouse directly adresses this problem and solves it by integrating all required data into one single database - hence there are already many data warehouses available to geneti ...200919210766
mediplex - a tool to combine in silico & experimental gene expression profiles of the model legume medicago truncatula.expressed sequence tags (ests) are in general used to gain a first insight into gene activities from a species of interest. subsequently, and typically based on a combination of est and genome sequences, microarray-based expression analyses are performed for a variety of conditions. in some cases, a multitude of est and microarray experiments are conducted for one species, covering different tissues, cell states, and cell types. under these circumstances, the challenge arises to combine results ...201020958970
medicago truncatula contains a second gene encoding a plastid located glutamine synthetase exclusively expressed in developing seeds.nitrogen is a crucial nutrient that is both essential and rate limiting for plant growth and seed production. glutamine synthetase (gs), occupies a central position in nitrogen assimilation and recycling, justifying the extensive number of studies that have been dedicated to this enzyme from several plant sources. all plants species studied to date have been reported as containing a single, nuclear gene encoding a plastid located gs isoenzyme per haploid genome. this study reports the existence ...201020723225
transcript profiling of two alfalfa genotypes with contrasting cell wall composition in stems using a cross-species platform: optimizing analysis by masking biased probes.the genechip(r) medicago genome array, developed for medicago truncatula, is a suitable platform for transcript profiling in tetraploid alfalfa [medicago sativa (l.) subsp. sativa]. however, previous research involving cross-species hybridization (csh) has shown that sequence variation between two species can bias transcript profiling by decreasing sensitivity (number of expressed genes detected) and the accuracy of measuring fold-differences in gene expression.201020497574
the medicago genome provides insight into the evolution of rhizobial symbioses.legumes (fabaceae or leguminosae) are unique among cultivated plants for their ability to carry out endosymbiotic nitrogen fixation with rhizobial bacteria, a process that takes place in a specialized structure known as the nodule. legumes belong to one of the two main groups of eurosids, the fabidae, which includes most species capable of endosymbiotic nitrogen fixation. legumes comprise several evolutionary lineages derived from a common ancestor 60 million years ago (myr ago). papilionoids ar ...201122089132
morphological and genetic changes induced by excess zn in roots of medicago truncatula a17 and a zn accumulating mutant.nutrient fluxes associated with legume-rhizobia symbioses are poorly understood and little is known regarding the influence of abiotic stresses on development and maintenance of n-fixing nodules and root system architecture (rsa). we examined effects of zn on nodule development and structure, root architecture, and expression of nodulation-related mirnas in medicago truncatula and the mutant, raz (requires additional zn).201223191938
is n-feedback involved in the inhibition of nitrogen fixation in drought-stressed medicago truncatula?drought stress is a major factor limiting nitrogen fixation (nf) in crop production. however, the regulatory mechanism involved and the origin of the inhibition, whether local or systemic, is still controversial and so far scarcely studied in temperate forage legumes. medicago truncatula plants were symbiotically grown with a split-root system and exposed to gradual water deprivation. physiological parameters, nf activity, and amino acid content were measured. the partial drought treatment inhib ...201223175536
expression dynamics of the medicago truncatula transcriptome during the symbiotic interaction with sinorhizobium meliloti: which role for nitric oxide?medicago truncatula is one of the most studied model plants. nevertheless, the genome of this legume remains incompletely determined. we used rna-seq to characterize the transcriptome during the early organogenesis of the nodule and during its functioning. we detected 37,333 expressed transcription units; to our knowledge, 1,670 had never been described before and were functionally annotated. we identified 7,595 new transcribed regions, mostly corresponding to 5' and 3' untranslated region exten ...201223136381
mapping the genetic basis of symbiotic variation in legume-rhizobium interactions in medicago truncatula.mutualisms are known to be genetically variable, where the genotypes differ in the fitness benefits they gain from the interaction. to date, little is known about the loci that underlie such genetic variation in fitness or whether the loci influencing fitness are partner specific, and depend on the genotype of the interaction partner. in the legume-rhizobium mutualism, one set of potential candidate genes that may influence the fitness benefits of the symbiosis are the plant genes involved in th ...201223173081
increased production of the exopolysaccharide succinoglycan enhances sinorhizobium meliloti 1021 symbiosis with the host plant medicago truncatula.the nitrogen-fixing rhizobial symbiont sinorhizobium meliloti 1021 produces acidic symbiotic exopolysaccharides that enable it to initiate and maintain infection thread formation on host legume plants. the exopolysaccharide that is most efficient in mediating this process is succinoglycan (exopolysaccharide i [epsi]), a polysaccharide composed of octasaccharide repeating units of 1 galactose and 7 glucose residues, modified with succinyl, acetyl, and pyruvyl substituents. previous studies had sh ...201222685282
a proteogenomic survey of the medicago truncatula genome.peptide sequencing by computational assignment of tandem mass spectra to a database of putative protein sequences provides an independent approach to confirming or refuting protein predictions based on large-scale dna and rna sequencing efforts. this use of mass spectrometrically-derived sequence data for testing and refining predicted gene models has been termed proteogenomics. we report herein the application of proteogenomic methodology to a database of 10.9 million tandem mass spectra collec ...201222774004
"ménage à trois": the presence/absence of thyme shapes the mutualistic interaction between the host plant medicago truncatula (fabaceae) and its symbiotic bacterium sinorhizobium meliloti.the long-term maintenance of specialized mutualisms remains an evolutionary puzzle. recent focus has been on factors governing the stability of these mutualisms, including sanctions by the host, partner choice, and coevolutionary constraint, that is, the genetic correlation (r(g)) between fitness of both partners. so far these studies have been typically carried out in a single environment. here, we ask if the genetic correlation between fitness of the host plant medicago truncatula (fabaceae) a ...201222957171
a medicago truncatula tobacco retrotransposon insertion mutant collection with defects in nodule development and symbiotic nitrogen fixation.a tnt1-insertion mutant population of medicago truncatula ecotype r108 was screened for defects in nodulation and symbiotic nitrogen fixation. primary screening of 9,300 mutant lines yielded 317 lines with putative defects in nodule development and/or nitrogen fixation. of these, 230 lines were rescreened, and 156 lines were confirmed with defective symbiotic nitrogen fixation. mutants were sorted into six distinct phenotypic categories: 72 nonnodulating mutants (nod-), 51 mutants with totally i ...201222679222
transcriptional responses toward diffusible signals from symbiotic microbes reveal mtnfp- and mtdmi3-dependent reprogramming of host gene expression by arbuscular mycorrhizal fungal lipochitooligosaccharides.the formation of root nodules and arbuscular mycorrhizal (am) roots is controlled by a common signaling pathway including the calcium/calmodulin-dependent kinase doesn't make infection3 (dmi3). while nodule initiation by lipochitooligosaccharide (lco) nod factors is well characterized, diffusible am fungal signals were only recently identified as sulfated and nonsulfated lcos. irrespective of different outcomes, the perception of symbiotic lcos in medicago truncatula is mediated by the lysm rece ...201222652128
identification of distinct quantitative trait loci associated with defence against the closely related aphids acyrthosiphon pisum and a. kondoi in medicago truncatula.aphids are a major family of plant insect pests. medicago truncatula and acyrthosiphon pisum (pea aphid, pa) are model species with a suite of resources available to help dissect the mechanism underlying plant-aphid interactions. a previous study focused on monogenic and relatively strong resistance in m. truncatula to pa and other aphid species. in this study a moderate resistance to pa was characterized in detail in the m. truncatula line a17 and compared with the highly susceptible line a20 a ...201222442407
the autoregulation gene sunn mediates changes in root organ formation in response to nitrogen through alteration of shoot-to-root auxin transport.we tested whether a gene regulating nodule number in medicago truncatula, super numeric nodules (sunn ), is involved in root architecture responses to carbon (c) and nitrogen (n) and whether this is mediated by changes in shoot-to-root auxin transport. nodules and lateral roots are root organs that are under the control of nutrient supply, but how their architecture is regulated in response to nutrients is unclear. we treated wild-type and sunn-1 seedlings with four combinations of low or increa ...201222399647
how to hierarchize the main physiological processes responsible for phenotypic differences in large-scale screening studies?one difficulty when analyzing the determinants at the origin of plant phenotypic differences is that measured plant traits are frequently integrative: they result from the integration of a large number of physiological processes under the control of genetic and environmental factors. in a previous report, we demonstrated that dissecting integrative traits into simpler components using a simple crop physiology model was a valuable method for detecting quantitative trait loci (qtl) related to the ...201222499204
role of cysteine residues and disulfide bonds in the activity of a legume root nodule-specific, cysteine-rich peptide.the root nodules of certain legumes including medicago truncatula produce >300 different nodule-specific cysteine-rich (ncr) peptides. medicago ncr antimicrobial peptides (amps) mediate the differentiation of the bacterium, sinorhizobium meliloti into a nitrogen-fixing bacteroid within the legume root nodules. in vitro, ncr amps such as ncr247 induced bacteroid features and exhibited antimicrobial activity against s. meliloti. the bacterial baca protein is critical to prevent s. meliloti from be ...201222351783
(homo)glutathione deficiency impairs root-knot nematode development in medicago truncatula.root-knot nematodes (rkn) are obligatory plant parasitic worms that establish and maintain an intimate relationship with their host plants. during a compatible interaction, rkn induce the redifferentiation of root cells into multinucleate and hypertrophied giant cells essential for nematode growth and reproduction. these metabolically active feeding cells constitute the exclusive source of nutrients for the nematode. detailed analysis of glutathione (gsh) and homoglutathione (hgsh) metabolism de ...201222241996
genome sequence of ensifer meliloti strain wsm1022; a highly effective microsymbiont of the model legume medicago truncatula a17.ensifer meliloti wsm1022 is an aerobic, motile, gram-negative, non-spore-forming rod that can exist as a soil saprophyte or as a legume microsymbiont of medicago. wsm1022 was isolated in 1987 from a nodule recovered from the roots of the annual medicago orbicularis growing on the cyclades island of naxos in greece. wsm1022 is highly effective at fixing nitrogen with m. truncatula and other annual species such as m. tornata and m. littoralis and is also highly effective with the perennial m. sati ...201324976888
elevated co(2) modifies n acquisition of medicago truncatula by enhancing n fixation and reducing nitrate uptake from soil.the effects of elevated co2 (750 ppm vs. 390 ppm) were evaluated on nitrogen (n) acquisition and assimilation by three medicago truncatula genotypes, including two n-fixing-deficient mutants (dnf1-1 and dnf1-2) and their wild-type (jemalong). the proportion of n acquisition from atmosphere and soil were quantified by (15)n stable isotope, and n transportation and assimilation-related genes and enzymes were determined by qpcr and biochemical analysis. elevated co2 decreased nitrate uptake from so ...201324339920
an rna sequencing transcriptome analysis reveals novel insights into molecular aspects of the nitrate impact on the nodule activity of medicago truncatula.the mechanism through which nitrate reduces the activity of legume nodules is controversial. the objective of the study was to follow medicago truncatula nodule activity after nitrate provision continuously and to identify molecular mechanisms, which down-regulate the activity of the nodules. nodule h2 evolution started to decline after about 4 h of nitrate application. at that point in time, a strong shift in nodule gene expression (rna sequencing) had occurred (1,120 differentially expressed g ...201324285852
inhibition of nitrogen fixation in symbiotic medicago truncatula upon cd exposure is a local process involving leghaemoglobin.leguminous biological nitrogen fixation (bnf) is very sensitive to environmental fluctuations. it is still contentious how bnf is regulated under stress conditions. the local or systemic control of bnf and the role played by reactive oxygen species (ros) in such regulation have still not been elucidated completely. cadmium, which belongs to the so-called heavy metals, is one of the most toxic substances released into the environment. the mechanisms involved in cd toxicity are still not completel ...201324151304
the identification of novel loci required for appropriate nodule development in medicago truncatula.the formation of functional symbiotic nodules is the result of a coordinated developmental program between legumes and rhizobial bacteria. genetic analyses in legumes have been used to dissect the signaling processes required for establishing the legume-rhizobial endosymbiotic association. compared to the early events of the symbiotic interaction, less attention has been paid to plant loci required for rhizobial colonization and the functioning of the nodule. here we describe the identification ...201324119289
single-plant, sterile microcosms for nodulation and growth of the legume plant medicago truncatula with the rhizobial symbiont sinorhizobium meliloti.rhizobial bacteria form symbiotic, nitrogen-fixing nodules on the roots of compatible host legume plants. one of the most well-developed model systems for studying these interactions is the plant medicago truncatula cv. jemalong a17 and the rhizobial bacterium sinorhizobium meliloti 1021. repeated imaging of plant roots and scoring of symbiotic phenotypes requires methods that are non-destructive to either plants or bacteria. the symbiotic phenotypes of some plant and bacterial mutants become ap ...201324121837
novel aspects of glutamine synthetase (gs) regulation revealed by a detailed expression analysis of the entire gs gene family of medicago truncatula under different physiological conditions.glutamine synthetase (gs, ec 6.3.1.2) is a central enzyme in nitrogen metabolism, and a key component of nitrogen use efficiency (nue) and plant yield and thus it is extremely important to understand how it is regulated in plants. medicago truncatula provides an excellent model system to study gs, as it contain a very simple gs gene family comprising only four expressed genes, mtgs1a and mtgs1b encoding cytosolic polypeptides, and mtgs2a and mtgs2b encoding plastid-located enzymes. to identify n ...201324053168
possible role of glutamine synthetase in the no signaling response in root nodules by contributing to the antioxidant defenses.nitric oxide (no) is emerging as an important regulatory player in the rhizobium-legume symbiosis. the occurrence of no during several steps of the symbiotic interaction suggests an important, but yet unknown, signaling role of this molecule for root nodule formation and functioning. the identification of the molecular targets of no is key for the assembly of the signal transduction cascade that will ultimately help to unravel no function. we have recently shown that the key nitrogen assimilator ...201324065976
host-specific nod-factors associated with medicago truncatula nodule infection differentially induce calcium influx and calcium spiking in root hairs.rhizobial nodulation (nod) factors activate both nodule morphogenesis and infection thread development during legume nodulation. nod factors induce two different calcium responses: intra-nuclear calcium oscillations and a calcium influx at the root hair tip. calcium oscillations activate nodule development; we wanted to test if the calcium influx is associated with infection. sinorhizobium meliloti nodl and nodf mutations additively reduce infection of medicago truncatula. nod-factors made by th ...201324015832
control of no level in rhizobium-legume root nodules: not only a plant globin story.nitric oxide (no ) is a gaseous signaling molecule which plays both regulatory and defense roles in animals and plants. in the symbiosis between legumes and rhizobia, no has been shown to be involved in bacterial infection and nodule development steps as well as in mature nodule functioning. we recently showed that an increase in no level inside medicago truncatula root nodules also could trigger premature nodule senescence. here we discuss the importance of the bacterial sinorhizobium meliloti ...201323962798
the independent acquisition of plant root nitrogen-fixing symbiosis in fabids recruited the same genetic pathway for nodule organogenesis.only species belonging to the fabid clade, limited to four classes and ten families of angiosperms, are able to form nitrogen-fixing root nodule symbioses (rns) with soil bacteria. this concerns plants of the legume family (fabaceae) and parasponia (cannabaceae) associated with the gram-negative proteobacteria collectively called rhizobia and actinorhizal plants associated with the gram-positive actinomycetes of the genus frankia. calcium and calmodulin-dependent protein kinase (ccamk) is a key ...201323741336
candidate genes and genetic architecture of symbiotic and agronomic traits revealed by whole-genome, sequence-based association genetics in medicago truncatula.genome-wide association study (gwas) has revolutionized the search for the genetic basis of complex traits. to date, gwas have generally relied on relatively sparse sampling of nucleotide diversity, which is likely to bias results by preferentially sampling high-frequency snps not in complete linkage disequilibrium (ld) with causative snps. to avoid these limitations we conducted gwas with >6 million snps identified by sequencing the genomes of 226 accessions of the model legume medicago truncat ...201323741505
growth and nodulation of symbiotic medicago truncatula at different levels of phosphorus availability.medicago truncatula is an important model plant for characterization of p deficiency on leguminous plants at the physiological and molecular levels. growth optimization of this plant with regard to p supply is the first essential step for elucidation of the role of p in regulation of nodulation. hence, a study was carried out to address the growth pattern of m. truncatula hydroponically grown at different gradual increases in p levels. the findings revealed that m. truncatula had a narrow p regi ...201323682114
the involvement of medicago truncatula non-specific lipid transfer protein n5 in the control of rhizobial infection.cysteine-rich proteins seem to play important regulatory roles in medicago truncatula/sinorhizobium meliloti symbiosis. in particular, a large family of nodule-specific cysteine-rich (ncr) peptides is crucial for the differentiation of nitrogen-fixing bacteroids. the medicago truncatula n5 protein (mtn5) is currently the only reported non-specific lipid transfer protein necessary for successful rhizobial symbiosis; in addition, mtn5 shares several characteristics with ncr peptides: a small size, ...201323656864
structural analysis of succinoglycan oligosaccharides from sinorhizobium meliloti strains with different host compatibility phenotypes.sinorhizobium meliloti nrg247 has a fix(+) phenotype on medicago truncatula a20 and is fix(-) on m. truncatula a17, and the phenotype is reversed with s. meliloti nrg185. as the succinoglycan was shown to impact host specificity, an analysis of the succinoglycan oligosaccharides produced by each strain was conducted. the symbiotically active succinoglycan trimeric oligosaccharides (stos) from the two s. meliloti strains were compared by chromatography and mass spectrometry, and the analysis of t ...201323457246
sub-cellular proteomics of medicago truncatula.medicago truncatula is a leading model species and substantial molecular, genetic, genomics, proteomics, and metabolomics resources have been developed for this species to facilitate the study of legume biology. currently, over 60 proteomics studies of m. truncatula have been published. many of these have focused upon the unique symbiosis formed between legumes and nitrogen fixing rhizobia bacteria, while others have focused on seed development and the specialized proteomes of distinct tissues/o ...201323641248
comparative analysis of the symbiotic efficiency of medicago truncatula and medicago sativa under phosphorus deficiency.phosphorus (p)-deficiency is a major abiotic stress that limits legume growth in many types of soils. the relationship between medicago and sinorhizobium, is known to be affected by different environmental conditions. recent reports have shown that, in combination with s. meliloti 2011, medicago truncatula had a lower symbiotic efficiency than medicago sativa. however, little is known about how medicago-sinorhizobium is affected by p-deficiency at the whole-plant level. the objective of the pres ...201323459233
multifaceted investigation of metabolites during nitrogen fixation in medicago via high resolution maldi-ms imaging and esi-ms.legumes have developed the unique ability to establish a symbiotic relationship with soil bacteria known as rhizobia. this interaction results in the formation of root nodules in which rhizobia thrive and reduce atmospheric dinitrogen into plant-usable ammonium through biological nitrogen fixation (bnf). owing to the availability of genetic information for both of the symbiotic partners, the medicago truncatula-sinorhizobium meliloti association is an excellent model for examining the bnf proces ...201425323862
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