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opposing control by transcription factors myb61 and myb3 increases freezing tolerance by relieving c-repeat binding factor suppression.cold acclimation is an important process by which plants respond to low temperature and enhance their winter hardiness. c-repeat binding factor1 (cbf1), cbf2, and cbf3 genes were shown previously to participate in cold acclimation in medicago truncatula in addition, mtcbf4 is transcriptionally induced by salt, drought, and cold stresses. we show here that mtcbf4, shown previously to enhance drought and salt tolerance, also positively regulates cold acclimation and freezing tolerance. to identify ...201627578551
function of succinoglycan polysaccharide in sinorhizobium meliloti host plant invasion depends on succinylation, not molecular weight.the acidic polysaccharide succinoglycan produced by the rhizobial symbiont sinorhizobium meliloti 1021 is required for this bacterium to invade the host plant medicago truncatula and establish a nitrogen-fixing symbiosis. s. meliloti mutants that cannot make succinoglycan cannot initiate invasion structures called infection threads in plant root hairs. s. meliloti exoh mutants that cannot succinylate succinoglycan are also unable to form infection threads, despite the fact that they make large q ...201627329751
nod factor effects on root hair-specific transcriptome of medicago truncatula: focus on plasma membrane transport systems and reactive oxygen species networks.root hairs are involved in water and nutrient uptake, and thereby in plant autotrophy. in legumes, they also play a crucial role in establishment of rhizobial symbiosis. to obtain a holistic view of medicago truncatula genes expressed in root hairs and of their regulation during the first hours of the engagement in rhizobial symbiotic interaction, a high throughput rna sequencing on isolated root hairs from roots challenged or not with lipochitooligosaccharides nod factors (nf) for 4 or 20 h was ...201627375649
cross-regulation between n metabolism and nitric oxide (no) signaling during plant immunity.plants are sessile organisms that have evolved a complex immune system which helps them cope with pathogen attacks. however, the capacity of a plant to mobilize different defense responses is strongly affected by its physiological status. nitrogen (n) is a major nutrient that can play an important role in plant immunity by increasing or decreasing plant resistance to pathogens. although no general rule can be drawn about the effect of n availability and quality on the fate of plant/pathogen inte ...201627092169
biotic and abiotic stimulation of root epidermal cells reveals common and specific responses to arbuscular mycorrhizal fungi.during arbuscular mycorrhizal (am) colonization, a focal accumulation of organelles occurs in root epidermal cells, prior to fungal penetration, beneath adhering hyphopodia. this is followed by the appearance of the prepenetration apparatus (ppa), a transcellular column of cytoplasm connected to the nucleus and rich in cytoskeleton and secretory endomembranes. this apparatus appears to be responsible for the construction of an apoplastic compartment that confines the fungus within the cell lumen ...200919151131
genome-wide identification of nodule-specific transcripts in the model legume medicago truncatula.the medicago truncatula expressed sequence tag (est) database (gene index) contains over 140,000 sequences from 30 cdna libraries. this resource offers the possibility of identifying previously uncharacterized genes and assessing the frequency and tissue specificity of their expression in silico. because m. truncatula forms symbiotic root nodules, unlike arabidopsis, this is a particularly important approach in investigating genes specific to nodule development and function in legumes. our analy ...200212376622
the molecular genetic linkage map of the model legume medicago truncatula: an essential tool for comparative legume genomics and the isolation of agronomically important genes.the legume medicago truncatula has emerged as a model plant for the molecular and genetic dissection of various plant processes involved in rhizobial, mycorrhizal and pathogenic plant-microbe interactions. aiming to develop essential tools for such genetic approaches, we have established the first genetic map of this species. two parental homozygous lines were selected from the cultivar jemalong and from the algerian natural population (dza315) on the basis of their molecular and phenotypic poly ...200211825338
nodule-specific modulation of glutamine synthetase in transgenic medicago truncatula leads to inverse alterations in asparagine synthetase expression.transgenic medicago truncatula plants were produced harboring chimeric gene constructs of the glutamine synthetase (gs) cdna clones (mtgs1a or mtgs1b) fused in sense or antisense orientation to the nodule-specific leghemoglobin promoter mtlb1. a series of transgenic plants were obtained showing a 2- to 4-fold alteration in nodule gs activity when compared with control plants. western and northern analyses revealed that the increased or decreased levels of gs activity correlate with the amount of ...200312970490
recruitment of novel calcium-binding proteins for root nodule symbiosis in medicago truncatula.legume rhizobia symbiotic nitrogen (n2) fixation plays a critical role in sustainable nitrogen management in agriculture and in the earth's nitrogen cycle. signaling between rhizobia and legumes initiates development of a unique plant organ, the root nodule, where bacteria undergo endocytosis and become surrounded by a plant membrane to form a symbiosome. between this membrane and the encased bacteria exists a matrix-filled space (the symbiosome space) that is thought to contain a mixture of pla ...200616543412
antisense repression of the medicago truncatula nodule-enhanced sucrose synthase leads to a handicapped nitrogen fixation mirrored by specific alterations in the symbiotic transcriptome and metabolome.we analyzed the role of the sucrose (suc) synthase mtsucs1 during nodulation of the model legume medicago truncatula, integrating data for the developmental, transcriptional, and metabolic processes affected downstream of an impaired suc cleavage in root nodules. to reduce carbohydrate supply to nodule tissues, transgenic plants expressing a p35s-driven mtsucs1-antisense fusion were constructed. these plants displayed an up to 90% reduction of mtsucs1 proteins in roots and nodules. phenotypic st ...200717951459
fungal symbiosis in rice requires an ortholog of a legume common symbiosis gene encoding a ca2+/calmodulin-dependent protein kinase.in natural ecosystems, many plants are able to establish mutually beneficial symbioses with microorganisms. of critical importance to sustainable agriculture are the symbioses formed between more than 80% of terrestrial plants and arbuscular mycorrhizal (am) fungi and between legumes and nitrogen-fixing rhizobial bacteria. interestingly, the two symbioses share overlapping signaling pathways in legumes, suggesting that the evolutionarily recent root nodule symbiosis may have acquired functions f ...200717965173
a medicago truncatula phosphate transporter indispensable for the arbuscular mycorrhizal symbiosis.the arbuscular mycorrhizal (am) symbiosis is a mutualistic endosymbiosis formed by plant roots and am fungi. most vascular flowering plants have the ability to form these associations, which have a significant impact on plant health and consequently on ecosystem function. nutrient exchange is a central feature of the am symbiosis, and am fungi obtain carbon from their plant host while assisting the plant with the acquisition of phosphorus (as phosphate) from the soil. in the am symbiosis, the fu ...200717242358
experimental evidence for splicing of intron-containing transcripts of plant ltr retrotransposon ogre.ogre elements are a distinct group of plant ty3/gypsy-like retrotransposons characterized by several specific features, one of which is a separation of the gag-pol region into two non-overlapping open reading frames: orf2 coding for gag-pro, and orf3 coding for rt/rh-int proteins. previous characterization of ogre elements from several plant species revealed that part of their transcripts lacks the region between orf2 and orf3, carrying one uninterrupted orf instead. in this work, we investigate ...200818762986
seven in absentia proteins affect plant growth and nodulation in medicago truncatula.protein ubiquitination is a posttranslational regulatory process essential for plant growth and interaction with the environment. e3 ligases, to which the seven in absentia (sina) proteins belong, determine the specificity by selecting the target proteins for ubiquitination. sina proteins are found in animals as well as in plants, and a small gene family with highly related members has been identified in the genome of rice (oryza sativa), arabidopsis (arabidopsis thaliana), medicago truncatula, ...200818599652
control of compound leaf development by floricaula/leafy ortholog single leaflet1 in medicago truncatula.molecular genetic studies suggest that floricaula (flo)/leafy (lfy) orthologs function to control compound leaf development in some legume species. however, loss-of-function mutations in the flo/lfy orthologs result in reduction of leaf complexity to different degrees in pisum sativum and lotus japonicus. to further understand the role of flo/lfy orthologs in compound leaf development in legumes, we studied compound leaf developmental processes and characterized a leaf development mutant, single ...200818287485
the transcription factor mtserf1 of the erf subfamily identified by transcriptional profiling is required for somatic embryogenesis induced by auxin plus cytokinin in medicago truncatula.transcriptional profiling of embryogenic callus produced from medicago truncatula mesophyll protoplasts indicated up-regulation of ethylene biosynthesis and ethylene response genes. using inhibitors of ethylene biosynthesis and perception, it was shown that ethylene was necessary for somatic embryogenesis (se) in this model legume. we chose several genes involved in ethylene biosynthesis and response for subsequent molecular analyses. one of these genes is a gene encoding a transcription factor ...200818235037
comparative genomic sequence and expression analyses of medicago truncatula and alfalfa subspecies falcata cold-acclimation-specific genes.in arabidopsis (arabidopsis thaliana) the low-temperature induction of genes encoding the c-repeat binding factor (cbf) transcriptional activators is a key step in cold acclimation. cbfs in turn activate a battery of downstream genes known as the cbf regulon, which collectively act to increase tolerance to low temperatures. fundamental questions are: what determines the size and scope of the cbf regulon, and is this is a major determinant of the low-temperature tolerance capacity of individual p ...200818218976
bioinformatic analysis of the cle signaling peptide family.plants encode a large number of leucine-rich repeat receptor-like kinases. legumes encode several lrr-rlk linked to the process of root nodule formation, the ligands of which are unknown. to identify ligands for these receptors, we used a combination of profile hidden markov models and position-specific iterative blast, allowing us to detect new members of the clv3/esr (cle) protein family from publicly available sequence databases.200818171480
mere1, a low-copy-number copia-type retroelement in medicago truncatula active during tissue culture.we have identified an active medicago truncatula copia-like retroelement called medicago retroelement1-1 (mere1-1) as an insertion in the symbiotic nsp2 gene. mere1-1 belongs to a low-copy-number family in the sequenced medicago genome. these copies are highly related, but only three of them have a complete coding region and polymorphism exists between the long terminal repeats of these different copies. this retroelement family is present in all m. truncatula ecotypes tested but also in other l ...200919656907
a wd40 repeat protein from medicago truncatula is necessary for tissue-specific anthocyanin and proanthocyanidin biosynthesis but not for trichome development.wd40 repeat proteins regulate biosynthesis of anthocyanins, proanthocyanidins (pas), and mucilage in the seed and the development of trichomes and root hairs. we have cloned and characterized a wd40 repeat protein gene from medicago truncatula (mtwd40-1) via a retrotransposon-tagging approach. deficiency of mtwd40-1 expression blocks accumulation of mucilage and a range of phenolic compounds, including pas, epicatechin, other flavonoids, and benzoic acids, in the seed, reduces epicatechin levels ...200919710231
the association of homeobox gene expression with stem cell formation and morphogenesis in cultured medicago truncatula.somatic embryogenesis (se) is induced in vitro in medicago truncatula 2ha by auxin and cytokinin but rarely in wild type jemalong. the putative wuschel (mtwus), clavata3 (mtclv3) and the wuschel-related homeobox gene wox5 (mtwox5) were investigated in m. truncatula (mt) and identified by the similarity to arabidopsis wus, clv3 and wox5 in amino acid sequence, phylogeny and in planta and in vitro expression patterns. mtwus was induced throughout embryogenic cultures by cytokinin after 24-48 h and ...200919639337
expression of the somatic embryogenesis receptor-like kinase1 (serk1) gene is associated with developmental change in the life cycle of the model legume medicago truncatula.somatic embryogenesis receptor-like kinase (serk) genes have been demonstrated to play a role in somatic embryogenesis in several plant species. as more is learnt about these genes, the view of their role in plant development has broadened. the medicago truncatula mtserk1 gene has been associated with somatic embryogenesis and in vitro root formation. in order to study the role of mtserk1 in development further, the mtserk1 promoter sequence has been isolated and cloned into a promoter-gus analy ...200919305022
medicago truncatula and glomus intraradices gene expression in cortical cells harboring arbuscules in the arbuscular mycorrhizal symbiosis.most vascular flowering plants have the capacity to form symbiotic associations with arbuscular mycorrhizal (am) fungi. the symbiosis develops in the roots where am fungi colonize the root cortex and form arbuscules within the cortical cells. arbuscules are enveloped in a novel plant membrane and their establishment requires the coordinated cellular activities of both symbiotic partners. the arbuscule-cortical cell interface is the primary functional interface of the symbiosis and is of central ...200919161626
antiquity and function of castor and pollux, the twin ion channel-encoding genes key to the evolution of root symbioses in plants.root symbioses with arbuscular mycorrhizal fungi and rhizobial bacteria share a common signaling pathway in legumes. among the common symbiosis genes are castor and pollux, the twin homologous genes in lotus japonicus that encode putative ion channel proteins. here, we show that the orthologs of castor and pollux are ubiquitously present and highly conserved in both legumes and nonlegumes. using rice (oryza sativa) as a study system, we employ reverse genetic tools (knockout mutants and rna inte ...200918978069
endoplasmic microtubules configure the subapical cytoplasm and are required for fast growth of medicago truncatula root hairs.to investigate the configuration and function of microtubules (mts) in tip-growing medicago truncatula root hairs, we used immunocytochemistry or in vivo decoration by a gfp linked to a mt-binding domain. the two approaches gave similar results and allowed the study of mts during hair development. cortical mts (cmts) are present in all developmental stages. during the transition from bulge to a tip-growing root hair, endoplasmic mts (emts) appear at the tip of the young hair and remain there unt ...200212376661
use of the fluorescent timer dsred-e5 as reporter to monitor dynamics of gene activity in plants.fluorescent proteins, such as green fluorescent protein and red fluorescent protein (dsred), have become frequently used reporters in plant biology. however, their potential to monitor dynamic gene regulation is limited by their high stability. the recently made dsred-e5 variant overcame this problem. dsred-e5 changes its emission spectrum over time from green to red in a concentration independent manner. therefore, the green to red fluorescence ratio indicates the age of the protein and can be ...200415326279
rna interference identifies a calcium-dependent protein kinase involved in medicago truncatula root development.changes in cellular or subcellular ca2+ concentrations play essential roles in plant development and in the responses of plants to their environment. however, the mechanisms through which ca2+ acts, the downstream signaling components, as well as the relationships among the various ca2+-dependent processes remain largely unknown. using an rna interference-based screen for gene function in medicago truncatula, we identified a gene that is involved in root development. silencing ca2+-dependent pro ...200516199614
overlaps in the transcriptional profiles of medicago truncatula roots inoculated with two different glomus fungi provide insights into the genetic program activated during arbuscular mycorrhiza.arbuscular mycorrhiza (am) is a widespread symbiotic association between plants and fungal microsymbionts that supports plant development under nutrient-limiting and various stress conditions. in this study, we focused on the overlapping genetic program activated by two commonly studied microsymbionts in addition to identifying am-related genes. we thus applied 16,086 probe microarrays to profile the transcriptome of the model legume medicago truncatula during interactions with glomus mosseae an ...200515778460
mthap2-1 is a key transcriptional regulator of symbiotic nodule development regulated by microrna169 in medicago truncatula.in the model legume medicago truncatula, we identified a new transcription factor of the ccaat-binding family, mthap2-1, for which rna interference (rnai) and in situ hybridization experiments indicate a key role during nodule development, possibly by controlling nodule meristem function. we could also show that mthap2-1 is regulated by microrna169, whose overexpression leads to the same nodule developmental block as mthap2-1 rnai constructs. the complementary expression pattern of mir169 and mt ...200617114582
rnai phenotypes and the localization of a protein::gus fusion imply a role for medicago truncatula pin genes in nodulation.the symbiosis between legumes and rhizobia results in the development of a new plant organ, the nodule. a role for polar auxin transport in nodule development in medicago truncatula has been demonstrated using molecular genetic tools. the expression of a dr5::gus auxin-responsive promoter in uninoculated m. truncatula roots mirrored that reported in arabidopsis, and expression of the construct in nodulating roots confirmed results reported in white clover. the localization of a root-specific pin ...200619444321
transcriptome analysis of arbuscular mycorrhizal roots during development of the prepenetration apparatus.information on changes in the plant transcriptome during early interaction with arbuscular mycorrhizal (am) fungi is still limited since infections are usually not synchronized and plant markers for early stages of colonization are not yet available. a prepenetration apparatus (ppa), organized in epidermal cells during appressorium development, has been reported to be responsible for assembling a trans-cellular tunnel to accommodate the invading fungus. here, we used ppas as markers for cell res ...200717468219
an erf transcription factor in medicago truncatula that is essential for nod factor signal transduction.rhizobial bacteria activate the formation of nodules on the appropriate host legume plant, and this requires the bacterial signaling molecule nod factor. perception of nod factor in the plant leads to the activation of a number of rhizobial-induced genes. putative transcriptional regulators in the gras family are known to function in nod factor signaling, but these proteins have not been shown to be capable of direct dna binding. here, we identify an erf transcription factor, erf required for no ...200717449807
rna interference-mediated repression of mtccd1 in mycorrhizal roots of medicago truncatula causes accumulation of c27 apocarotenoids, shedding light on the functional role of ccd1.tailoring carotenoids by plant carotenoid cleavage dioxygenases (ccds) generates various bioactive apocarotenoids. recombinant ccd1 has been shown to catalyze symmetrical cleavage of c(40) carotenoid substrates at 9,10 and 9',10' positions. the actual substrate(s) of the enzyme in planta, however, is still unknown. in this study, we have carried out rna interference (rnai)-mediated repression of a medicago truncatula ccd1 gene in hairy roots colonized by the arbuscular mycorrhizal (am) fungus gl ...200818790999
a transcript profiling approach reveals an epicatechin-specific glucosyltransferase expressed in the seed coat of medicago truncatula.expression of the arabidopsis transparent testa 2 (tt2) myb family transcription factor leads to massive accumulation of proanthocyanidins (pas) in hairy roots of medicago truncatula. microarray analysis showed that tt2 induces genes for flavonoid/pa biosynthesis, transcription factors, and a large number of genes of unknown function. a second microarray dataset identified genes that were preferentially expressed in the m. truncatula seed coat. comparison of the two datasets defines target genes ...200818772380
prepenetration apparatus assembly precedes and predicts the colonization patterns of arbuscular mycorrhizal fungi within the root cortex of both medicago truncatula and daucus carota.arbuscular mycorrhizas (am) are widespread, ancient endosymbiotic associations that contribute significantly to soil nutrient uptake in plants. we have previously shown that initial fungal penetration of the host root is mediated via a specialized cytoplasmic assembly called the prepenetration apparatus (ppa), which directs am hyphae through the epidermis (genre et al., 2005). in vivo confocal microscopy studies performed on medicago truncatula and daucus carota, host plants with different patte ...200818515499
knockdown of cell division cycle16 reveals an inverse relationship between lateral root and nodule numbers and a link to auxin in medicago truncatula.the postembryonic development of lateral roots and nodules is a highly regulated process. recent studies suggest the existence of cross talk and interdependency in the growth of these two organs. although plant hormones, including auxin and cytokinin, appear to be key players in coordinating this cross talk, very few genes that cross-regulate root and nodule development have been uncovered so far. this study reports that a homolog of cell division cycle16 (cdc16), a core component of the anaphas ...200919789288
lin, a novel type of u-box/wd40 protein, controls early infection by rhizobia in legumes.the formation of a nitrogen-fixing nodule requires the coordinated development of rhizobial colonization and nodule organogenesis. based on its mutant phenotype, lumpy infections (lin), lin functions at an early stage of the rhizobial symbiotic process, required for both infection thread growth in root hair cells and the further development of nodule primordia. we show that spontaneous nodulation activated by the calcium- and calmodulin-dependent protein kinase is independent of lin; thus, lin i ...200919776163
live-cell imaging reveals periarbuscular membrane domains and organelle location in medicago truncatula roots during arbuscular mycorrhizal symbiosis.in the arbuscular mycorrhizal symbiosis, the fungal symbiont colonizes root cortical cells, where it establishes differentiated hyphae called arbuscules. as each arbuscule develops, the cortical cell undergoes a transient reorganization and envelops the arbuscule in a novel symbiosis-specific membrane, called the periarbuscular membrane. the periarbuscular membrane, which is continuous with the plant plasma membrane of the cortical cell, is a key interface in the symbiosis; however, relatively l ...200919692536
a novel plant leucine-rich repeat receptor kinase regulates the response of medicago truncatula roots to salt stress.in plants, a diverse group of cell surface receptor-like protein kinases (rlks) plays a fundamental role in sensing external signals to regulate gene expression. roots explore the soil environment to optimize their growth via complex signaling cascades, mainly analyzed in arabidopsis thaliana. however, legume roots have significant physiological differences, notably their capacity to establish symbiotic interactions. these major agricultural crops are affected by environmental stresses such as s ...200919244136
environmental regulation of lateral root emergence in medicago truncatula requires the hd-zip i transcription factor hb1.the adaptation of root architecture to environmental constraints is a major agricultural trait, notably in legumes, the third main crop worldwide. this root developmental plasticity depends on the formation of lateral roots (lrs) emerging from primary roots. in the model legume medicago truncatula, the hd-zip i transcription factor hb1 is expressed in primary and lateral root meristems and induced by salt stress. constitutive expression of hb1 in m. truncatula roots alters their architecture, wh ...201020675575
the compact root architecture1 gene regulates lignification, flavonoid production, and polar auxin transport in medicago truncatula.the root system architecture is crucial to adapt plant growth to changing soil environmental conditions and consequently to maintain crop yield. in addition to root branching through lateral roots, legumes can develop another organ, the nitrogen-fixing nodule, upon a symbiotic bacterial interaction. a mutant, cra1, showing compact root architecture was identified in the model legume medicago truncatula. cra1 roots were short and thick due to defects in cell elongation, whereas densities of later ...201020522723
two medicago truncatula half-abc transporters are essential for arbuscule development in arbuscular mycorrhizal symbiosis.in the symbiotic association of plants and arbuscular mycorrhizal (am) fungi, the fungal symbiont resides in the root cortical cells where it delivers mineral nutrients to its plant host through branched hyphae called arbuscules. here, we report a medicago truncatula mutant, stunted arbuscule (str), in which arbuscule development is impaired and am symbiosis fails. in contrast with legume symbiosis mutants reported previously, str shows a wild-type nodulation phenotype. str was identified by pos ...201020453115
cle peptides control medicago truncatula nodulation locally and systemically.the clavata3/embryo-surrounding region (cle) peptides control the fine balance between proliferation and differentiation in plant development. we studied the role of cle peptides during indeterminate nodule development and identified 25 mtcle peptide genes in the medicago truncatula genome, of which two genes, mtcle12 and mtcle13, had nodulation-related expression patterns that were linked to proliferation and differentiation. mtcle13 expression was up-regulated early in nodule development. a hi ...201020348212
comparison of developmental and stress-induced nodule senescence in medicago truncatula.mature indeterminate medicago truncatula nodules are zonated with an apical meristem, an infection zone, a fixation zone with nitrogen-fixing bacteroids, and a "developmental" senescence zone that follows nodule growth with a conical front originating in the center of the fixation zone. in nitrogen-fixing cells, senescence is initiated coincidently with the expression of a family of conserved cysteine proteases that might be involved in the degradation of symbiotic structures. environmental stre ...201020081044
laser microdissection unravels cell-type-specific transcription in arbuscular mycorrhizal roots, including caat-box transcription factor gene expression correlating with fungal contact and spread.arbuscular mycorrhizae (am) are the most widespread symbioses on earth, promoting nutrient supply of most terrestrial plant species. to unravel gene expression in defined stages of medicago truncatula root colonization by am fungi, we here combined genome-wide transcriptome profiling based on whole mycorrhizal roots with real-time reverse transcription-pcr experiments that relied on characteristic cell types obtained via laser microdissection. our genome-wide approach delivered a core set of 512 ...201122034628
the root determined nodulation1 gene regulates nodule number in roots of medicago truncatula and defines a highly conserved, uncharacterized plant gene family.the formation of nitrogen-fixing nodules in legumes is tightly controlled by a long-distance signaling system in which nodulating roots signal to shoot tissues to suppress further nodulation. a screen for supernodulating medicago truncatula mutants defective in this regulatory behavior yielded loss-of-function alleles of a gene designated root determined nodulation1 (rdn1). grafting experiments demonstrated that rdn1 regulatory function occurs in the roots, not the shoots, and is essential for n ...201121742814
mtbhlh1, a bhlh transcription factor involved in medicago truncatula nodule vascular patterning and nodule to plant metabolic exchanges.this study aimed at defining the role of a basic helix-loop-helix (bhlh) transcription factor gene from medicago truncatula, mtbhlh1, whose expression is upregulated during the development of root nodules produced upon infection by rhizobia bacteria. we used mtbhlh1 promoter::gus fusions and quantitative reverse-transcription polymerase chain reaction analyses to finely characterize the mtbhlh1 expression pattern. we altered mtbhlh1 function by expressing a dominantly repressed construct (cres-t ...201121679315
transcriptional profiling of medicago truncatula under salt stress identified a novel cbf transcription factor mtcbf4 that plays an important role in abiotic stress responses.salt stress hinders the growth of plants and reduces crop production worldwide. however, different plant species might possess different adaptive mechanisms to mitigate salt stress. we conducted a detailed pathway analysis of transcriptional dynamics in the roots of medicago truncatula seedlings under salt stress and selected a transcription factor gene, mtcbf4, for experimental validation.201121718548
lc/ms profiling of flavonoid glycoconjugates isolated from hairy roots, suspension root cell cultures and seedling roots of medicago truncatula.hairy roots and suspension cell cultures are commonly used in deciphering different problems related to the biochemistry and physiology of plant secondary metabolites. here, we address about the issue of possible differences in the profiles of flavonoid compounds and their glycoconjugates derived from various plant materials grown in a standard culture media. we compared profiles of flavonoids isolated from seedling roots, hairy roots, and suspension root cell cultures of a model legume plant, m ...201122039365
the non-specific lipid transfer protein n5 of medicago truncatula is implicated in epidermal stages of rhizobium-host interaction.the symbiotic interaction between leguminous plants and rhizobia involves two processes: bacterial infection, resulting in the penetration of bacteria in epidermal and cortical cells, and root nodule organogenesis. root nodule symbiosis is activated by rhizobial signalling molecules, called nodulation factors (nfs). nf perception induces the expression of several genes called early nodulins. the early nodulin n5 of medicago truncatula is a lipid transfer protein that has been shown to positively ...201223217154
cell autonomous and non-cell autonomous control of rhizobial and mycorrhizal infection in medicago truncatula.legumes can form a nitrogen fixing symbiosis with soil bacteria called rhizobia (the rl symbiosis). they can also, like most plants, form symbiotic associations with arbuscular mycorrhizal (am) fungi, which facilitate plants' phosphate nutrition. in both interactions, the symbionts are hosted inside the plant root. nitrogen-fixing rhizobia are housed in intracellular symbiotic structures within nodules, while am fungi form intracellular symbiotic structures, called arbuscules, within cortical ro ...201223221781
allelic differences in medicago truncatula nip/latd mutants correlate with their encoded proteins' transport activities in planta.medicago truncatula nip/latd gene, required for symbiotic nitrogen fixing nodule and root architecture development, encodes a member of the nrt1(ptr) family that demonstrates high-affinity nitrate transport in xenopus laevis oocytes. of three mtnip/latd mutant proteins, one retains high-affinity nitrate transport in oocytes, while the other two are nitrate-transport defective. to further examine the mutant proteins' transport properties, the missense mtnip/latd alleles were expressed in arabidop ...201223154505
nodule root and cochleata maintain nodule development and are legume orthologs of arabidopsis blade-on-petiole genes.during their symbiotic interaction with rhizobia, legume plants develop symbiosis-specific organs on their roots, called nodules, that house nitrogen-fixing bacteria. the molecular mechanisms governing the identity and maintenance of these organs are unknown. using medicago truncatula nodule root (noot) mutants and pea (pisum sativum) cochleata (coch) mutants, which are characterized by the abnormal development of roots from the nodule, we identified the noot and coch genes as being necessary fo ...201223136374
one-step agrobacterium mediated transformation of eight genes essential for rhizobium symbiotic signaling using the novel binary vector system phuge.advancement in plant research is becoming impaired by the fact that the transfer of multiple genes is difficult to achieve. here we present a new binary vector for agrobacterium tumefaciens mediated transformation, phuge-red, in concert with a cloning strategy suited for the transfer of up to nine genes at once. this vector enables modular cloning of large dna fragments by employing gateway technology and contains dsred1 as visual selection marker. furthermore, an r/rs inducible recombination sy ...201223112864
medicago truncatula ern transcription factors: regulatory interplay with nsp1/nsp2 gras factors and expression dynamics throughout rhizobial infection.rhizobial nodulation factors (nfs) activate a specific signaling pathway in medicago truncatula root hairs that involves the complex interplay of nodulation signaling pathway1 (nsp1)/nsp2 gras and ethylene response factor required for nodulation1 (ern1) transcription factors (tfs) to achieve full enod11 transcription. ern1 acts as a direct transcriptional regulator of enod11 through the activation of the nf-responsive "nf box." here, we show that nsp1, when combined with nsp2, can act as a stron ...201223077241
two direct targets of cytokinin signaling regulate symbiotic nodulation in medicago truncatula.cytokinin regulates many aspects of plant development, and in legume crops, this phytohormone is necessary and sufficient for symbiotic nodule organogenesis, allowing them to fix atmospheric nitrogen. to identify direct links between cytokinins and nodule organogenesis, we determined a consensus sequence bound in vitro by a transcription factor (tf) acting in cytokinin signaling, the nodule-enhanced medicago truncatula mt rr1 response regulator (rr). among genes rapidly regulated by cytokinins a ...201223023168
functional assessment of the medicago truncatula nip/latd protein demonstrates that it is a high-affinity nitrate transporter.the medicago truncatula nip/latd (for numerous infections and polyphenolics/lateral root-organ defective) gene encodes a protein found in a clade of nitrate transporters within the large nrt1(ptr) family that also encodes transporters of dipeptides and tripeptides, dicarboxylates, auxin, and abscisic acid. of the nrt1(ptr) members known to transport nitrate, most are low-affinity transporters. here, we show that m. truncatula nip/latd mutants are more defective in their lateral root responses to ...201222858636
the recent evolution of a symbiotic ion channel in the legume family altered ion conductance and improved functionality in calcium signaling.arbuscular mycorrhiza and the rhizobia-legume symbiosis are two major root endosymbioses that facilitate plant nutrition. in lotus japonicus, two symbiotic cation channels, castor and pollux, are indispensable for the induction of nuclear calcium spiking, one of the earliest plant responses to symbiotic partner recognition. during recent evolution, a single amino acid substitution in does not make infections1 (dmi1), the pollux putative ortholog in the closely related medicago truncatula, render ...201222706284
rapid phosphoproteomic and transcriptomic changes in the rhizobia-legume symbiosis.symbiotic associations between legumes and rhizobia usually commence with the perception of bacterial lipochitooligosaccharides, known as nod factors (nf), which triggers rapid cellular and molecular responses in host plants. we report here deep untargeted tandem mass spectrometry-based measurements of rapid nf-induced changes in the phosphorylation status of 13,506 phosphosites in 7739 proteins from the model legume medicago truncatula. to place these phosphorylation changes within a biological ...201222683509
the small gtpase rop6 interacts with nfr5 and is involved in nodule formation in lotus japonicus.nod factor receptor5 (nfr5) is an atypical receptor-like kinase, having no activation loop in the protein kinase domain. it forms a heterodimer with nfr1 and is required for the early plant responses to rhizobium infection. a rho-like small gtpase from lotus japonicus was identified as an nfr5-interacting protein. the amino acid sequence of this rho-like gtpase is closest to the arabidopsis (arabidopsis thaliana) rop6 and medicago truncatula rop6 and was designated as ljrop6. the interaction bet ...201222434040
characterization of an isoflavonoid-specific prenyltransferase from lupinus albus.prenylated flavonoids and isoflavonoids possess antimicrobial activity against fungal pathogens of plants. however, only a few plant flavonoid and isoflavonoid prenyltransferase genes have been identified to date. in this study, an isoflavonoid prenyltransferase gene, designated as lapt1, was identified from white lupin (lupinus albus). the deduced protein sequence of lapt1 shared high homologies with known flavonoid and isoflavonoid prenyltransferases. the lapt1 gene was mainly expressed in roo ...201222430842
multiple domains in mtenod8 protein including the signal peptide target it to the symbiosome.symbiotic nitrogen fixation occurs in nodules, specialized organs on the roots of legumes. within nodules, host plant cells are infected with rhizobia that are encapsulated by a plant-derived membrane forming a novel organelle, the symbiosome. in medicago truncatula, the symbiosome consists of the symbiosome membrane, a single rhizobium, and the soluble space between them, called the symbiosome space. the symbiosome space is enriched with plant-derived proteins, including the m. truncatula early ...201222415512
silencing of the rac1 gtpase mtrop9 in medicago truncatula stimulates early mycorrhizal and oomycete root colonizations but negatively affects rhizobial infection.rac/rop proteins (ρ-related gtpases of plants) are plant-specific small g proteins that function as molecular switches within elementary signal transduction pathways, including the regulation of reactive oxygen species (ros) generation during early microbial infection via the activation of nadph oxidase homologs of plants termed rboh (for respiratory burst oxidase homolog). we investigated the role of medicago truncatula jemalong a17 small gtpase mtrop9, orthologous to medicago sativa rac1, via ...201222399646
polar localization of a symbiosis-specific phosphate transporter is mediated by a transient reorientation of secretion.the arbuscular mycorrhizal (am) symbiosis, formed by land plants and am fungi, evolved an estimated 400 million years ago and has been maintained in angiosperms, gymnosperms, pteridophytes, and some bryophytes as a strategy for enhancing phosphate acquisition. during am symbiosis, the am fungus colonizes the root cortical cells where it forms branched hyphae called arbuscules that function in nutrient exchange with the plant. each arbuscule is enveloped in a plant membrane, the periarbuscular me ...201222355114
role of n-glycosylation sites and cxc motifs in trafficking of medicago truncatula nod factor perception protein to plasma membrane.the lysin motif receptor-like kinase, nfp (nod factor perception), is a key protein in the legume medicago truncatula for the perception of lipochitooligosaccharidic nod factors, which are secreted bacterial signals essential for establishing the nitrogen-fixing legume-rhizobia symbiosis. predicted structural and genetic analyses strongly suggest that nfp is at least part of a nod factor receptor, but few data are available about this protein. characterization of a variant encoded by the mutant ...201222334694
functional domain analysis of the remorin protein ljsymrem1 in lotus japonicus.in legumes rhizobial infection during root nodule symbiosis (rns) is controlled by a conserved set of receptor proteins and downstream components. mtsymrem1, a protein of the remorin family in medicago truncatula, was shown to interact with at least three receptor-like kinases (rlks) that are essential for rns. remorins are comprised of a conserved c-terminal domain and a variable n-terminal region that defines the six different remorin groups. while both n- and c-terminal regions of remorins be ...201222292047
mtpar myb transcription factor acts as an on switch for proanthocyanidin biosynthesis in medicago truncatula.mtpar (medicago truncatula proanthocyanidin regulator) is an myb family transcription factor that functions as a key regulator of proanthocyanidin (pa) biosynthesis in the model legume medicago truncatula. mtpar expression is confined to the seed coat, the site of pa accumulation. loss-of-function par mutants contained substantially less pa in the seed coat than the wild type, whereas levels of anthocyanin and other specialized metabolites were normal in the mutants. in contrast, massive accumul ...201222307644
wuschel-related homeobox5 gene expression and interaction of cle peptides with components of the systemic control add two pieces to the puzzle of autoregulation of nodulation.in legumes, the symbiotic nodules are formed as a result of dedifferentiation and reactivation of cortical root cells. a shoot-acting receptor complex, similar to the arabidopsis (arabidopsis thaliana) clavata1 (clv1)/clv2 receptor, regulating development of the shoot apical meristem, is involved in autoregulation of nodulation (aon), a mechanism that systemically controls nodule number. the targets of clv1/clv2 in the shoot apical meristem, the wuschel (wus)-related homeobox (wox) family transc ...201222232385
automated analysis of calcium spiking profiles with casa software: two case studies from root-microbe symbioses.repeated oscillations in intracellular calcium (ca2+) concentration, known as ca2+ spiking signals, have been described in plants for a limited number of cellular responses to biotic or abiotic stimuli and most notably the common symbiotic signaling pathway (cssp) which mediates the recognition by their plant hosts of two endosymbiotic microbes, arbuscular mycorrhizal (am) fungi and nitrogen fixing rhizobia. the detailed analysis of the complexity and variability of the ca2+ spiking patterns whi ...201324369773
the ccaat box-binding transcription factor nf-ya1 controls rhizobial infection.symbiosis between legume plants and soil rhizobia culminates in the formation of a novel root organ, the 'nodule', containing bacteria differentiated as facultative nitrogen-fixing organelles. mtnf-ya1 is a medicago truncatula ccaat box-binding transcription factor (tf), formerly called hap2-1, highly expressed in mature nodules and required for nodule meristem function and persistence. here a role for mtnf-ya1 during early nodule development is demonstrated. detailed expression analysis based o ...201324319255
della proteins regulate arbuscule formation in arbuscular mycorrhizal symbiosis.most flowering plants are able to form endosymbioses with arbuscular mycorrhizal fungi. in this mutualistic association, the fungus colonizes the root cortex and establishes elaborately branched hyphae, called arbuscules, within the cortical cells. arbuscule development requires the cellular reorganization of both symbionts, and the resulting symbiotic interface functions in nutrient exchange. a plant symbiosis signaling pathway controls the development of the symbiosis. several components of th ...201324297892
high phosphate reduces host ability to develop arbuscular mycorrhizal symbiosis without affecting root calcium spiking responses to the fungus.the arbuscular mycorrhizal symbiosis associates soil fungi with the roots of the majority of plants species and represents a major source of soil phosphorus acquisition. mycorrhizal interactions begin with an exchange of molecular signals between the two partners. a root signaling pathway is recruited, for which the perception of fungal signals triggers oscillations of intracellular calcium concentration. high phosphate availability is known to inhibit the establishment and/or persistence of thi ...201324194742
the c2h2 transcription factor regulator of symbiosome differentiation represses transcription of the secretory pathway gene vamp721a and promotes symbiosome development in medicago truncatula.transcription factors (tfs) are thought to regulate many aspects of nodule and symbiosis development in legumes, although few tfs have been characterized functionally. here, we describe regulator of symbiosome differentiation (rsd) of medicago truncatula, a member of the cysteine-2/histidine-2 (c2h2) family of plant tfs that is required for normal symbiosome differentiation during nodule development. rsd is expressed in a nodule-specific manner, with maximal transcript levels in the bacterial in ...201324082011
a regulatory network-based approach dissects late maturation processes related to the acquisition of desiccation tolerance and longevity of medicago truncatula seeds.in seeds, desiccation tolerance (dt) and the ability to survive the dry state for prolonged periods of time (longevity) are two essential traits for seed quality that are consecutively acquired during maturation. using transcriptomic and metabolomic profiling together with a conditional-dependent network of global transcription interactions, we dissected the maturation events from the end of seed filling to final maturation drying during the last 3 weeks of seed development in medicago truncatul ...201323929721
the arabidopsis hp6 gene is expressed in medicago truncatula lateral roots and root nodule primordia.expression patterns of orthologous genes can be similar between distantly related species, suggesting that developmental programs can be conserved between organisms. here, we show that the promoter of ahp6, a gene which is involved in arabidopsis lateral root development, also drives the expression of the reporter gus gene in lateral roots of medicago truncatula suggesting that similar regulatory elements are involved in lateral root organogenesis in these species. interestingly, the ahp6 promot ...201323759550
cell- and tissue-specific transcriptome analyses of medicago truncatula root nodules.legumes have the unique ability to host nitrogen-fixing rhizobium bacteria as symbiosomes inside root nodule cells. to get insight into this key process, which forms the heart of the endosymbiosis, we isolated specific cells/tissues at different stages of symbiosome formation from nodules of the model legume medicago truncatula using laser-capture microdissection. next, we determined their associated expression profiles using affymetrix medicago genechips. cells were collected from the nodule in ...201323734198
genotype delimitation in the nod-independent model legume aeschynomene evenia.research on the nitrogen-fixing symbiosis has been so far focused on two model legumes, medicago truncatula and lotus japonicus, which use a sophisticated infection process involving infection thread formation. however, in 25% of the legumes, the bacterial entry occurs more simply in an intercellular fashion. among them, some semi-aquatic aeschynomene species present the distinctive feature to form nitrogen-fixing nodules on both roots and stems following elicitation by photosynthetic bradyrhizo ...201323717496
an endogenous artificial microrna system for unraveling the function of root endosymbioses related genes in medicago truncatula.legumes have the unique capacity to undergo two important root endosymbioses: the root nodule symbiosis and the arbuscular mycorrhizal symbiosis. medicago truncatula is widely used to unravel the functions of genes during these root symbioses. here we describe the development of an artificial microrna (amir)-mediated gene silencing system for m. truncatula roots.201323679580
regulatory patterns of a large family of defensin-like genes expressed in nodules of medicago truncatula.root nodules are the symbiotic organ of legumes that house nitrogen-fixing bacteria. many genes are specifically induced in nodules during the interactions between the host plant and symbiotic rhizobia. information regarding the regulation of expression for most of these genes is lacking. one of the largest gene families expressed in the nodules of the model legume medicago truncatula is the nodule cysteine-rich (ncr) group of defensin-like (defl) genes. we used a custom affymetrix microarray to ...201323573247
rhizobial infection is associated with the development of peripheral vasculature in nodules of medicago truncatula.nodulation in legumes involves the coordination of epidermal infection by rhizobia with cell divisions in the underlying cortex. during nodulation, rhizobia are entrapped within curled root hairs to form an infection pocket. transcellular tubes called infection threads then develop from the pocket and become colonized by rhizobia. the infection thread grows toward the developing nodule primordia and rhizobia are taken up into the nodule cells, where they eventually fix nitrogen. the epidermal an ...201323535942
the root hair "infectome" of medicago truncatula uncovers changes in cell cycle genes and reveals a requirement for auxin signaling in rhizobial infection.nitrogen-fixing rhizobia colonize legume roots via plant-made intracellular infection threads. genetics has identified some genes involved but has not provided sufficient detail to understand requirements for infection thread development. therefore, we transcriptionally profiled medicago truncatula root hairs prior to and during the initial stages of infection. this revealed changes in the responses to plant hormones, most notably auxin, strigolactone, gibberellic acid, and brassinosteroids. sev ...201425527707
local and systemic regulation of plant root system architecture and symbiotic nodulation by a receptor-like kinase.in plants, root system architecture is determined by the activity of root apical meristems, which control the root growth rate, and by the formation of lateral roots. in legumes, an additional root lateral organ can develop: the symbiotic nitrogen-fixing nodule. we identified in medicago truncatula ten allelic mutants showing a compact root architecture phenotype (cra2) independent of any major shoot phenotype, and that consisted of shorter roots, an increased number of lateral roots, and a redu ...201425521478
the nitrate transporter mtnpf6.8 (mtnrt1.3) transports abscisic acid and mediates nitrate regulation of primary root growth in medicago truncatula.elongation of the primary root during postgermination of medicago truncatula seedlings is a multigenic trait that is responsive to exogenous nitrate. a quantitative genetic approach suggested the involvement of the nitrate transporter mtnpf6.8 (for medicago truncatula nitrate transporter1/peptide transporter family6.8) in the inhibition of primary root elongation by high exogenous nitrate. in this study, the inhibitory effect of nitrate on primary root elongation, via inhibition of elongation of ...201425367858
nod factor receptors form heteromeric complexes and are essential for intracellular infection in medicago nodules.rhizobial nod factors are the key signaling molecules in the legume-rhizobium nodule symbiosis. in this study, the role of the nod factor receptors nod factor perception (nfp) and lysin motif receptor-like kinase3 (lyk3) in establishing the symbiotic interface in root nodules was investigated. it was found that inside medicago truncatula nodules, nfp and lyk3 localize at the cell periphery in a narrow zone of about two cell layers at the nodule apex. this restricted accumulation is narrower than ...201425351493
intracellular catalytic domain of symbiosis receptor kinase hyperactivates spontaneous nodulation in absence of rhizobia.symbiosis receptor kinase (symrk), a member of the nod factor signaling pathway, is indispensible for both nodule organogenesis and intracellular colonization of symbionts in rhizobia-legume symbiosis. here, we show that the intracellular kinase domain of a symrk (symrk-kd) but not its inactive or full-length version leads to hyperactivation of the nodule organogenic program in medicago truncatula tr25 (symrk knockout mutant) in the absence of rhizobia. spontaneous nodulation in tr25/symrk-kd wa ...201425304318
abscisic acid promotion of arbuscular mycorrhizal colonization requires a component of the protein phosphatase 2a complex.legumes can establish intracellular interactions with symbiotic microbes to enhance their fitness, including the interaction with arbuscular mycorrhizal (am) fungi. am fungi colonize root epidermal cells to gain access to the root cortex, and this requires the recognition by the host plant of fungus-made mycorrhizal factors. genetic dissection has revealed the symbiosis signaling pathway that allows the recognition of am fungi, but the downstream processes that are required to promote fungal inf ...201425293963
adjustment of host cells for accommodation of symbiotic bacteria: vacuole defunctionalization, hops suppression, and tip1g retargeting in medicago.in legume-rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. symbiosomes remain as individual units and avoid fusion with lytic vacuoles of host cells. we observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. to examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbios ...201425217511
abscisic acid and lateral root organ defective/numerous infections and polyphenolics modulate root elongation via reactive oxygen species in medicago truncatula.abscisic acid (aba) modulates root growth in plants grown under normal and stress conditions and can rescue the root growth defects of the medicago truncatula lateral root-organ defective (latd) mutant. here, we demonstrate that reactive oxygen species (ros) function downstream of aba in the regulation of root growth by controlling cell elongation. we also show that the mtlatd/numerous infections and polyphenolics (nip) nitrate transporter is required for ros homeostasis and cell elongation in r ...201425192698
auxin perception is required for arbuscule development in arbuscular mycorrhizal symbiosis.most land plant species live in symbiosis with arbuscular mycorrhizal fungi. these fungi differentiate essential functional structures called arbuscules in root cortical cells from which mineral nutrients are released to the plant. we investigated the role of microrna393 (mir393), an mirna that targets several auxin receptors, in arbuscular mycorrhizal root colonization. expression of the precursors of the mir393 was down-regulated during mycorrhization in three different plant species: solanum ...201425096975
mir171h restricts root symbioses and shows like its target nsp2 a complex transcriptional regulation in medicago truncatula.legumes have the unique capability to undergo root nodule and arbuscular mycorrhizal symbiosis. both types of root endosymbiosis are regulated by nsp2, which is a target of microrna171h (mir171h). although, recent data implies that mir171h specifically restricts arbuscular mycorrhizal symbiosis in the root elongation zone of medicago truncatula roots, there is limited knowledge available about the spatio-temporal regulation of mir171h expression at different physiological and symbiotic condition ...201425928247
myb5 and myb14 play pivotal roles in seed coat polymer biosynthesis in medicago truncatula.in arabidopsis (arabidopsis thaliana), the major myb protein regulating proanthocyanidin (pa) biosynthesis is tt2, named for the transparent testa phenotype of tt2 mutant seeds that lack pas in their coats. in contrast, the myb5 transcription factor mainly regulates seed mucilage biosynthesis and trichome branching, with only a minor role in pa biosynthesis. we here characterize myb5 and myb14 (a tt2 homolog) in the model legume medicago truncatula. overexpression of mtmyb5 or mtmyb14 strongly i ...201424948832
a h+-atpase that energizes nutrient uptake during mycorrhizal symbioses in rice and medicago truncatula.most plant species form symbioses with arbuscular mycorrhizal (am) fungi, which facilitate the uptake of mineral nutrients such as phosphate from the soil. several transporters, particularly proton-coupled phosphate transporters, have been identified on both the plant and fungal membranes and contribute to delivering phosphate from fungi to plants. the mechanism of nutrient exchange has been studied in plants during mycorrhizal colonization, but the source of the electrochemical proton gradient ...201424781115
the h+-atpase ha1 of medicago truncatula is essential for phosphate transport and plant growth during arbuscular mycorrhizal symbiosis.a key feature of arbuscular mycorrhizal symbiosis is improved phosphorus nutrition of the host plant via the mycorrhizal pathway, i.e., the fungal uptake of pi from the soil and its release from arbuscules within root cells. efficient transport of pi from the fungus to plant cells is thought to require a proton gradient across the periarbuscular membrane (pam) that separates fungal arbuscules from the host cell cytoplasm. previous studies showed that the h(+)-atpase gene ha1 is expressed specifi ...201424781114
molecular and ultrastructural analysis of forisome subunits reveals the principles of forisome assembly.forisomes are specialized structural phloem proteins that mediate sieve element occlusion after wounding exclusively in papilionoid legumes, but most studies of forisome structure and function have focused on the old world clade rather than the early lineages. a comprehensive phylogenetic, molecular, structural and functional analysis of forisomes from species covering a broad spectrum of the papilionoid legumes was therefore carried out, including the first analysis of dipteryx panamensis foris ...201424694827
medicago truncatula symbiotic peptide ncr247 contributes to bacteroid differentiation through multiple mechanisms.symbiosis between rhizobia soil bacteria and legume plants results in the formation of root nodules where plant cells are fully packed with nitrogen fixing bacteria. in the host cells, the bacteria adapt to the intracellular environment and gain the ability for nitrogen fixation. depending on the host plants, the symbiotic fate of bacteria can be either reversible or irreversible. in medicago and related legume species, the bacteria undergo a host-directed multistep differentiation process culmi ...201424706863
the nin transcription factor coordinates diverse nodulation programs in different tissues of the medicago truncatula root.biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. we show that while early nod factor signaling associated with calcium oscillations is limited to the root surface, the resultant activation of nodule inception (nin) in the root epidermis is sufficient to promote cytokinin signaling and nodule organogenesis ...201526672071
the bhlh transcription factors tsar1 and tsar2 regulate triterpene saponin biosynthesis in medicago truncatula.plants respond to stresses by producing a broad spectrum of bioactive specialized metabolites. hormonal elicitors, such as jasmonates, trigger a complex signaling circuit leading to the concerted activation of specific metabolic pathways. however, for many specialized metabolic pathways, the transcription factors involved remain unknown. here, we report on two homologous jasmonate-inducible transcription factors of the basic helix-loop-helix family, triterpene saponin biosynthesis activating reg ...201526589673
an antimicrobial peptide essential for bacterial survival in the nitrogen-fixing symbiosis.in the nitrogen-fixing symbiosis between legume hosts and rhizobia, the bacteria are engulfed by a plant cell membrane to become intracellular organelles. in the model legume medicago truncatula, internalization and differentiation of sinorhizobium (also known as ensifer) meliloti is a prerequisite for nitrogen fixation. the host mechanisms that ensure the long-term survival of differentiating intracellular bacteria (bacteroids) in this unusual association are unclear. the m. truncatula defectiv ...201526598690
hyphal branching during arbuscule development requires reduced arbuscular mycorrhiza1.during arbuscular mycorrhizal symbiosis, arbuscule development in the root cortical cell and simultaneous deposition of the plant periarbuscular membrane generate the interface for symbiotic nutrient exchange. the transcriptional changes that accompany arbuscule development are extensive and well documented. by contrast, the transcriptional regulators that control these programs are largely unknown. here, we provide a detailed characterization of an insertion allele of medicago truncatula reduce ...201526511916
crispr/cas mutagenesis of soybean and medicago truncatula using a new web-tool and a modified cas9 enzyme.the crispr/cas9 system is rapidly becoming the reagent of choice for targeted mutagenesis and gene editing in crop species. there are currently intense research efforts in the crop sciences to identify efficient crispr/cas9 platforms to carry out targeted mutagenesis and gene editing projects. these efforts typically result in the incremental tweaking of various platform components including the identification of crop-specific promoters and terminators for optimal expression of the cas9 enzyme a ...201526479970
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