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ftsz characterization and immunolocalization in the two phases of plastid reorganization in arbuscular mycorrhizal roots of medicago truncatula.we have analyzed plastid proliferation in root cortical cells of medicago truncatula colonized by arbuscular mycorrhizal (am) fungi by concomitantly labeling fungal structures, root plastids, a protein involved in plastid division (ftsz1) and a protein involved in the biosynthesis of am-specific apocarotenoids. antibodies directed against ftsz1 have been generated after heterologous expression of the respective gene from m. truncatula and characterization of the gene product. analysis of enzymat ...200616854943
gc-ms based metabolite profiling implies three interdependent ways of ammonium assimilation in medicago truncatula root nodules.in symbiotic interaction with legume plants, bacteria termed rhizobia can fix massive amounts of atmospheric nitrogen which is primarily provided in the form of ammonium to the host plants. therefore, legume root nodules that house the symbiotic bacteria are ideally suited to study the process of primary ammonium assimilation. here, we present a gc-ms based metabolite profiling analysis of medicago truncatula root nodules (induced by the bacterium sinorhizobium meliloti) before and after inhibit ...200616870293
nitric oxide is formed in medicago truncatula-sinorhizobium meliloti functional nodules.nitric oxide (no) has recently gained interest as a major signaling molecule during plant development and response to environmental cues. its role is particularly crucial for plant-pathogen interactions, during which it participates in the control of plant defense response and resistance. indication for the presence of no during symbiotic interactions has also been reported. here, we defined when and where no is produced during medicago truncatula-sinorhizobium meliloti symbiosis. using the no-s ...200616941901
isolation of mtpim proves tnt1 a useful reverse genetics tool in medicago truncatula and uncovers new aspects of ap1-like functions in legumes.comparative studies help shed light on how the huge diversity in plant forms found in nature has been produced. we use legume species to study developmental differences in inflorescence architecture and flower ontogeny with classical models such as arabidopsis thaliana or antirrhinum majus. whereas genetic control of these processes has been analyzed mostly in pea (pisum sativum), medicago truncatula is emerging as a promising alternative system for these studies due to the availability of a ran ...200616963524
ralstonia solanacearum requires f-box-like domain-containing type iii effectors to promote disease on several host plants.the phytopathogenic bacterium ralstonia solanacearum encodes a family of seven type iii secretion system (t3ss) effectors that contain both a leucine-rich repeat and an f-box domain. this structure is reminiscent of a class of typical eukaryotic proteins called f-box proteins. the latter, together with skp1 and cullin1 subunits, constitute the scf-type e3 ubiquitin ligase complex and control specific protein ubiquitinylation. in the eukaryotic cell, depending on the nature of the polyubiquitin c ...200616983093
medicago truncatula transformation using leaf explants.legumes have long been recalcitrant to efficient agrobacterium tumefaciens-mediated transformation. the choice and use of model legume plants (medicago truncatula and lotus japonicus) for molecular studies has triggered extensive studies devoted to the development of efficient agrobacterium-mediated transformation protocols for these two plants. in m. truncatula, transformation protocols rely on the use of highly regenerable lines obtained by recurrent in vitro culture selection. these protocols ...200616988338
medicago truncatula transformation using cotyledon explants.medicago truncatula has been developed into a model species for legumes. large numbers of ests have been sequenced, and sequencing of the complete gene-rich space of the genotype jemalong a17 is in progress. by using cotyledons as explants for agrobacterium infection and direct shoot formation, this protocol allows for rapid production of transgenic plants from a17 and other genotypes. transgenic plants can be regenerated and established in the greenhouse in only 3-4 mo after agrobacterium-media ...200616988339
medicago truncatula transformation using root explants.medicago truncatula is a forage crop that has been developed into a model legume. as a model plant, m. truncatula is particularly useful for the study of root endosymbiotic associations, including nodulation and mycorrhizal colonization. the development of different transformation methods is an important aspect for functional genomic studies in the species. this protocol describes an efficient system for generating transgenic plants from m. truncatula roots based on agrobacterium tumefaciens-med ...200616988340
salt-tolerant rhizobia isolated from a tunisian oasis that are highly effective for symbiotic n2-fixation with phaseolus vulgaris constitute a novel biovar (bv. mediterranense) of sinorhizobium meliloti.nodulation of common bean was explored in six oases in the south of tunisia. nineteen isolates were characterized by pcr-rflp of 16s rdna. three species of rhizobia were identified, rhizobium etli, rhizobium gallicum and sinorhizobium meliloti. the diversity of the symbiotic genes was then assessed by pcr-rflp of nodc and nifh genes. the majority of the symbiotic genotypes were conserved between oases and other soils of the north of the country. sinorhizobia isolated from bean were then compared ...200717019605
the medicago truncatula cre1 cytokinin receptor regulates lateral root development and early symbiotic interaction with sinorhizobium meliloti.legumes develop different types of lateral organs from their primary root, lateral roots and nodules, the latter depending on a symbiotic interaction with sinorhizobium meliloti. phytohormones have been shown to function in the control of these organogeneses. however, related signaling pathways have not been identified in legumes. we cloned and characterized the expression of medicago truncatula genes encoding members of cytokinin signaling pathways. rna interference of the cytokinin receptor ho ...200617028204
geminivirus infection up-regulates the expression of two arabidopsis protein kinases related to yeast snf1- and mammalian ampk-activating kinases.geminivirus rep-interacting kinase 1 (grik1) and grik2 constitute a small protein kinase family in arabidopsis (arabidopsis thaliana). an earlier study showed that a truncated version of grik1 binds to the geminivirus replication protein al1. we show here both full-length grik1 and grik2 interact with al1 in yeast two-hybrid studies. using specific antibodies, we showed that both arabidopsis kinases are elevated in infected leaves. immunoblot analysis of healthy plants revealed that grik1 and gr ...200617041027
lotus japonicus nodulation requires two gras domain regulators, one of which is functionally conserved in a non-legume.a new nodulation-defective mutant of lotus japonicus does not initiate nodule cortical cell division in response to mesorhizobium loti, but induces root hair deformation, nod factor-induced calcium spiking, and mycorrhization. this phenotype, together with mapping data, suggested that the mutation could be in the ortholog of the medicago truncatula nsp1 gene (mtnsp1). the sequence of the orthologous gene (ljnsp1) in the l. japonicus mutant (ljnsp1-1) revealed a mutation causing a premature stop ...200617071642
identification of ethylene-mediated protein changes during nodulation in medicago truncatula using proteome analysis.ethylene has been hypothesised to be a regulator of root nodule development in legumes, but its molecular mechanisms of action remain unclear. the skl mutant is an ethylene-insensitive legume mutant showing a hypernodulation phenotype when inoculated with its symbiont sinorhizobium meliloti. we used the skl mutant to study the ethylene-mediated protein changes during nodule development in medicago truncatula. we compared the root proteome of the skl mutant to its wild-type in response to the eth ...200617081060
development of bioinformatic tools to support est-sequencing, in silico- and microarray-based transcriptome profiling in mycorrhizal symbioses.the great majority of terrestrial plants enters a beneficial arbuscular mycorrhiza (am) or ectomycorrhiza (ecm) symbiosis with soil fungi. in the spp 1084 "molmyk: molecular basics of mycorrhizal symbioses", high-throughput est-sequencing was performed to obtain snapshots of the plant and fungal transcriptome in mycorrhizal roots and in extraradical hyphae. to focus activities, the interactions between medicago truncatula and glomus intraradices as well as populus tremula and amanita muscaria we ...200717081576
gene expression analysis of arbuscule development and functioning.the arbuscular mycorrhiza (am) is characterized by specific morphological structures of the fungus and the plant and by physiological adaptations which are mostly beneficial for both partners of the symbiosis. this review describes approaches to study the molecular basis of the interaction. rna accumulation patterns have been monitored in pisum sativum to analyse the plant response to arbuscule development. in a direct approach, the mtha1 gene from medicago truncatula was cloned which is express ...200717081578
a cdpk isoform participates in the regulation of nodule number in medicago truncatula.medicago spp. are able to develop root nodules via symbiotic interaction with sinorhizobium meliloti. calcium-dependent protein kinases (cdpks) are involved in various signalling pathways in plants, and we found that expression of mtcpk3, a cdpk isoform present in roots of the model legume medicago truncatula, is regulated during the nodulation process. early inductions were detected 15 min and 3-4 days post-inoculation (dpi). the very early induction of cpk3 messengers was also present in inocu ...200617132148
towards the elucidation of am-specific transcription in medicago truncatula.roots of most plants form a mutualistic interaction with arbuscular mycorrhiza (am) fungi. during the symbiosis, drastic morphological and physiological changes occur in the host plant root system. these changes are likely to be controlled by a specific genetic program of the plant. the legume medicago truncatula is a model system widely used to elucidate this program. a number of loci required for am-development have been identified by the analysis of m. truncatula mutants; however, the genes i ...200717141285
the symbiotic ion channel homolog dmi1 is localized in the nuclear membrane of medicago truncatula roots.legumes utilize a common signaling pathway to form symbiotic associations both with rhizobial bacteria and arbuscular mycorrhizal fungi. the perception of microbial signals is believed to take place at the plasma membrane, activating a cascade that converges on the nucleus where transcriptional reprogramming facilitates the symbioses. forward genetic strategies have identified genes in this signaling pathway including medicago truncatula dmi1 (doesn't make infections 1) that encodes a putative i ...200717173544
a transient decrease in reactive oxygen species in roots leads to root hair deformation in the legume-rhizobia symbiosis.* a possible role for reactive oxygen species (ros) in root hair deformation in response to nod factor (nf) was investigated using medicago truncatula nodulation mutants, and an inhibitor and precursors of ros. * in wild-type roots, ros efflux transiently decreased approximately 1 h after nf treatment. transcript accumulation of two nadph oxidase homologs, respiratory burst oxidase homolog 2 (mtrboh2) and mtrboh3, also transiently decreased at 1 h. however, in the nonnodulating mutant nod factor ...200717176392
microtubule dynamics in root hairs of medicago truncatula.the microtubular cytoskeleton plays an important role in the development of tip-growing plant cells, but knowledge about its dynamics is incomplete. in this study, root hairs of the legume medicago truncatula have been chosen for a detailed analysis of microtubular cytoskeleton dynamics using gfp-mbd and eb1-yfp as markers and 4d imaging. the microtubular cytoskeleton appears mainly to be composed of bundles which form tracks along which new microtubules polymerise. polymerisation rates of micro ...200717218039
the lipopolysaccharide of sinorhizobium meliloti suppresses defense-associated gene expression in cell cultures of the host plant medicago truncatula.in the establishment of symbiosis between medicago truncatula and the nitrogen-fixing bacterium sinorhizobium meliloti, the lipopolysaccharide (lps) of the microsymbiont plays an important role as a signal molecule. it has been shown in cell cultures that the lps is able to suppress an elicitor-induced oxidative burst. to investigate the effect of s. meliloti lps on defense-associated gene expression, a microarray experiment was performed. for evaluation of the m. truncatula microarray datasets, ...200717220366
analysis of calcium spiking using a cameleon calcium sensor reveals that nodulation gene expression is regulated by calcium spike number and the developmental status of the cell.rhizobium-made nod factors induce rapid changes in both ca(2+) and gene expression. mutations and inhibitors that abolish nod-factor-induced ca(2+) spiking block gene induction, indicating a specific role for ca(2+) spiking in signal transduction. we used transgenic medicago truncatula expressing a "cameleon" ca(2+) sensor to assess the relationship between nod-factor-induced ca(2+) spiking and the activation of downstream gene expression. in contrast to enod11 induction, ca(2+) spiking is activ ...200617227545
an ire-like agc kinase gene, mtire, has unique expression in the invasion zone of developing root nodules in medicago truncatula.the agc protein kinase family (camp-dependent protein kinases a, cgmp-dependent protein kinases g, and phospholipid-dependent protein kinases c) have important roles regulating growth and development in animals and fungi. they are activated via lipid second messengers by 3-phosphoinositide-dependent protein kinase coupling lipid signals to phosphorylation of the agc kinases. these phosphorylate downstream signal transduction protein targets. agc kinases are becoming better studied in plants, esp ...200717237187
silencing of pr-10-like proteins in medicago truncatula results in an antagonistic induction of other pr proteins and in an increased tolerance upon infection with the oomycete aphanomyces euteiches.recent studies on the root proteome of medicago truncatula (gaertn.) showed an induction of pathogenesis-related (pr) proteins of the class 10 after infection with the oomycete pathogen aphanomyces euteiches (drechs.). to get insights into the function of these proteins during the parasitic root-microbe association, a gene knockdown approach using rnai was carried out. agrobacterium rhizogenes-mediated transformation of m. truncatula roots led to a knockdown of the medicago pr10-1 gene in transg ...200717237953
abscisic acid rescues the root meristem defects of the medicago truncatula latd mutant.the latd gene of the model legume, medicago truncatula, is required for the normal function of three meristems, i.e. the primary root, lateral roots and nitrogen-fixing nodules. in latd mutants, primary root growth eventually arrests, resulting in a disorganized root tip lacking a presumptive meristem and root cap columella cells. lateral root organs are more severely affected; latd lateral roots and nodules arrest immediately after emerging from the primary root, and reveal a lack of organizati ...200717239844
roles of poly-3-hydroxybutyrate (phb) and glycogen in symbiosis of sinorhizobium meliloti with medicago sp.poly-3-hydroxybutyrate (phb) and glycogen are major carbon storage compounds in sinorhizobium meliloti. the roles of phb and glycogen in rhizobia-legume symbiosis are not fully understood. glycogen synthase mutations were constructed by in-frame deletion (glga1) or insertion (glga2). these mutations were combined with a phbc mutation to make all combinations of double and triple mutants. phb was not detectable in any of the mutants containing the phbc mutation; glycogen was not detectable in any ...200717259610
the mtmmpl1 early nodulin is a novel member of the matrix metalloendoproteinase family with a role in medicago truncatula infection by sinorhizobium meliloti.we show here that mtmmpl1, a medicago truncatula nodulin gene previously identified by transcriptomics, represents a novel and specific marker for root and nodule infection by sinorhizobium meliloti. this was established by determining the spatial pattern of mtmmpl1 expression and evaluating gene activation in the context of various plant and bacterial symbiotic mutant interactions. the mtmmpl1 protein is the first nodulin shown to belong to the large matrix metalloendoproteinase (mmp) family. w ...200717293436
characterization of the interaction between the bacterial wilt pathogen ralstonia solanacearum and the model legume plant medicago truncatula.the soilborne pathogen ralstonia solanacearum is the causal agent of bacterial wilt and attacks more than 200 plant species, including some legumes and the model legume plant medicago truncatula. we have demonstrated that m. truncatula accessions jemalong a17 and f83005.5 are susceptible to r. solanacearum and, by screening 28 r. solanacearum strains on the two m. truncatula lines, differential interactions were identified. r. solanacearum gmi1000 infected jemalong a17 line, and disease symptoms ...200717313167
mastoparan activates calcium spiking analogous to nod factor-induced responses in medicago truncatula root hair cells.the rhizobial-derived signaling molecule nod factor is essential for the establishment of the medicago truncatula/sinorhizobium meliloti symbiosis. nod factor perception and signal transduction in the plant involve calcium spiking and lead to the induction of nodulation gene expression. it has previously been shown that the heterotrimeric g-protein agonist mastoparan can activate nodulation gene expression in a manner analogous to nod factor activation of these genes and this requires doesn't ma ...200717322338
identification of qtl for reaction to three races of colletotrichum trifolii and further analysis of inheritance of resistance in autotetraploid lucerne.anthracnose, caused by colletotrichum trifolii, is one of the most serious diseases of lucerne worldwide. the disease is managed through deployment of resistant cultivars, but new pathotypes present a challenge to the successful implementation of this strategy. this paper reports the genetic map locations of quantitative trait loci (qtl) for reaction to races 1, 2 and 4 of c. trifolii in a single autotetraploid lucerne clone, designated w126 from the australian cv. trifecta. resistance was mappe ...200717356866
medicago truncatula nin is essential for rhizobial-independent nodule organogenesis induced by autoactive calcium/calmodulin-dependent protein kinase.the symbiotic association between legumes and nitrogen-fixing bacteria collectively known as rhizobia results in the formation of a unique plant root organ called the nodule. this process is initiated following the perception of rhizobial nodulation factors by the host plant. nod factor (nf)-stimulated plant responses, including nodulation-specific gene expression, is mediated by the nf signaling pathway. plant mutants in this pathway are unable to nodulate. we describe here the cloning and char ...200717369436
identification of new potential regulators of the medicago truncatula-sinorhizobium meliloti symbiosis using a large-scale suppression subtractive hybridization approach.we set up a large-scale suppression subtractive hybridization (ssh) approach to identify medicago truncatula genes differentially expressed at different stages of the symbiotic interaction with sinorhizobium meliloti, with a particular interest for regulatory genes. we constructed 7 ssh libraries covering successive stages from nod factor signal transduction to s. meliloti infection, nodule organogenesis, and functioning. over 26,000 clones were differentially screened by two rounds of macroarra ...200717378435
regulation of arbuscular mycorrhization by carbon. the symbiotic interaction cannot be improved by increased carbon availability accomplished by root-specifically enhanced invertase activity.the mutualistic interaction in arbuscular mycorrhiza (am) is characterized by an exchange of mineral nutrients and carbon. the major benefit of am, which is the supply of phosphate to the plant, and the stimulation of mycorrhization by low phosphate fertilization has been well studied. however, less is known about the regulatory function of carbon availability on am formation. here the effect of enhanced levels of hexoses in the root, the main form of carbohydrate used by the fungus, on am forma ...200717416641
arbuscular mycorrhizal symbiosis is accompanied by local and systemic alterations in gene expression and an increase in disease resistance in the shoots.in natural ecosystems, the roots of many plants exist in association with arbuscular mycorrhizal (am) fungi, and the resulting symbiosis has profound effects on the plant. the most frequently documented response is an increase in phosphorus nutrition; however, other effects have been noted, including increased resistance to abiotic and biotic stresses. here we used a 16,000-feature oligonucleotide array and real-time quantitative rt-pcr to explore transcriptional changes triggered in medicago tr ...200717419842
root hair curling and rhizobium infection in medicago truncatula are mediated by phosphatidylinositide-regulated endocytosis and reactive oxygen species.the symbiotic relationships between legumes and rhizobacteria involve extensive signalling between the two organisms. studies using genetic, biochemical, and pharmacological approaches have demonstrated the involvement of calcium and reactive oxygen species in the establishment of symbiotic interactions. in the early stage of the interactions rhizobia grow as infection thread within host root hairs and are internalized into the plant cells via endocytosis. it is shown here that inoculation of me ...200717420174
flavone synthases from medicago truncatula are flavanone-2-hydroxylases and are important for nodulation.flavones are important copigments found in the flowers of many higher plants and play a variety of roles in plant adaptation to stress. in medicago species, flavones also act as signal molecules during symbiotic interaction with the diazotropic bacterium sinorhizobium meliloti. they are the most potent nod gene inducers found in root exudates. however, flavone synthase ii (fns ii), the key enzyme responsible for flavone biosynthesis, has not been characterized in medicago species. we cloned two ...200717434990
overlap of proteome changes in medicago truncatula in response to auxin and sinorhizobium meliloti.we used proteome analysis to identify proteins induced during nodule initiation and in response to auxin in medicago truncatula. from previous experiments, which found a positive correlation between auxin levels and nodule numbers in the m. truncatula supernodulation mutant sunn (supernumerary nodules), we hypothesized (1) that auxin mediates protein changes during nodulation and (2) that auxin responses might differ between the wild type and the supernodulating sunn mutant during nodule initiat ...200717468210
tracembler--software for in-silico chromosome walking in unassembled genomes.whole genome shotgun sequencing produces increasingly higher coverage of a genome with random sequence reads. progressive whole genome assembly and eventual finishing sequencing is a process that typically takes several years for large eukaryotic genomes. in the interim, all sequence reads of public sequencing projects are made available in repositories such as the ncbi trace archive. for a particular locus, sequencing coverage may be high enough early on to produce a reliable local genome assem ...200717490482
horizontal gene transfer and homologous recombination drive the evolution of the nitrogen-fixing symbionts of medicago species.using nitrogen-fixing sinorhizobium species that interact with medicago plants as a model system, we aimed at clarifying how sex has shaped the diversity of bacteria associated with the genus medicago on the interspecific and intraspecific scales. to gain insights into the diversification of these symbionts, we inferred a topology that includes the different specificity groups which interact with medicago species, based on sequences of the nodulation gene cluster. furthermore, 126 bacterial isol ...200717496100
comparison of rhizobia that nodulate medicago laciniata and medicago truncatula present in a single tunisian arid soil.the rhizobia present in a single arid region tunisian soil that nodulate medicago laciniata and medicago truncatula were compared. all isolates, 40 from each host, were sinorhizobium meliloti based on 16s rrna polymerase chain reaction restriction fragment length polymorphism (pcr-rflp) patterns and subsequent confirmation by sequence analysis of the 16s rrna genes in four representatives from each host species. there was no apparent relationship between medicago host species of isolation and th ...200717496977
increased calcium bioavailability in mice fed genetically engineered plants lacking calcium oxalate.bioavailable calcium affects bone formation and calcification. here we investigate how a single gene mutation altering calcium partitioning in the model forage crop medicago truncatula affects calcium bioavailability. previously, the cod5 m. truncatula mutant was identified which contains identical calcium concentrations to wild-type, but contains no oxalate crystals. in this study, equal number of male and female mice were randomly grouped and then fed one of four 45ca-containing diets: m. trun ...200717514431
context dependence in the coevolution of plant and rhizobial mutualists.several mechanisms are expected to rapidly rid mutualisms of genetic variation in partner quality. variation for mutualist quality, however, appears to be widespread. we used a model legume-rhizobium mutualism to test for evidence that context-dependent selection may maintain variation in partner quality. in a greenhouse experiment using 10 natural populations of medicago truncatula and two strains of sinorhizobium medicae, we detected significant genotype x genotype (g x g) interactions for pla ...200717535796
medicago truncatula root nodule proteome analysis reveals differential plant and bacteroid responses to drought stress.drought is one of the environmental factors most affecting crop production. under drought, symbiotic nitrogen fixation is one of the physiological processes to first show stress responses in nodulated legumes. this inhibition process involves a number of factors whose interactions are not yet understood. this work aims to further understand changes occurring in nodules under drought stress from a proteomic perspective. drought was imposed on medicago truncatula 'jemalong a17' plants grown in sym ...200717545507
crystal structure of medicago truncatula ugt85h2--insights into the structural basis of a multifunctional (iso)flavonoid glycosyltransferase.(iso)flavonoids are a diverse group of plant secondary metabolites with important effects on plant, animal and human health. they exist in various glycosidic forms. glycosylation, which may determine their bioactivities and functions, is controlled by specific plant uridine diphosphate glycosyltransferases (ugts). we describe a new multifunctional (iso)flavonoid glycosyltransferase, ugt85h2, from the model legume medicago truncatula with activity towards a number of phenylpropanoid-derived natur ...200717553523
a udp-glucose:isoflavone 7-o-glucosyltransferase from the roots of soybean (glycine max) seedlings. purification, gene cloning, phylogenetics, and an implication for an alternative strategy of enzyme catalysis.isoflavones, a class of flavonoids, play very important roles in plant-microbe interactions in certain legumes such as soybeans (glycine max l. merr.). g. max udp-glucose:isoflavone 7-o-glucosyltransferase (gmif7gt) is a key enzyme in the synthesis of isoflavone conjugates, which accumulate in large amounts in vacuoles and serve as an isoflavonoid pool that allows for interaction with microorganisms. in this study, the 14,000-fold purification of gmif7gt from the roots of g. max seedlings was ac ...200717565994
medicago lyk3, an entry receptor in rhizobial nodulation factor signaling.rhizobia secrete nodulation (nod) factors, which set in motion the formation of nitrogen-fixing root nodules on legume host plants. nod factors induce several cellular responses in root hair cells within minutes, but also are essential for the formation of infection threads by which rhizobia enter the root. based on studies using bacterial mutants, a two-receptor model was proposed, a signaling receptor that induces early responses with low requirements toward nod factor structure and an entry r ...200717586690
promex: a mass spectral reference database for proteins and protein phosphorylation sites.in the last decade, techniques were established for the large scale genome-wide analysis of proteins, rna, and metabolites, and database solutions have been developed to manage the generated data sets. the golm metabolome database for metabolite data (gmd) represents one such effort to make these data broadly available and to interconnect the different molecular levels of a biological system 1. as data interpretation in the light of already existing data becomes increasingly important, these ini ...200717587460
distinct, crucial roles of flavonoids during legume nodulation.rna interference-mediated silencing of the key flavonoid and isoflavone biosynthesis enzyme, respectively, by two different research groups has provided direct genetic evidence for the essential roles that these compounds play in nodulation. anton wasson et al. have shown that flavonoids are essential for localized auxin transport inhibition during nodulation in the indeterminate legume medicago truncatula. by contrast, senthil subramanian et al. have shown that isoflavones are essential for end ...200717591456
effects of aiia-mediated quorum quenching in sinorhizobium meliloti on quorum-sensing signals, proteome patterns, and symbiotic interactions.many behaviors in bacteria, including behaviors important to pathogenic and symbiotic interactions with eukaryotic hosts, are regulated by a mechanism called quorum sensing (qs). a "quorum-quenching" approach was used here to identify qs-regulated behaviors in the n-fixing bacterial symbiont sinorhizobium meliloti. the aiia lactonase from bacillus produced in s. meliloti was shown to enzymatically inactivate s. meliloti's n-acyl homoserine lactone (ahl) qs signals, thereby disrupting normal qs r ...200717601171
the medicago truncatula dmi1 protein modulates cytosolic calcium signaling.in addition to establishing symbiotic relationships with arbuscular mycorrhizal fungi, legumes also enter into a nitrogen-fixing symbiosis with rhizobial bacteria that results in the formation of root nodules. several genes involved in the development of both arbuscular mycorrhiza and legume nodulation have been cloned in model legumes. among them, medicago truncatula dmi1 (doesn't make infections1) is required for the generation of nucleus-associated calcium spikes in response to the rhizobial ...200717631529
how rhizobial symbionts invade plants: the sinorhizobium-medicago model.nitrogen-fixing rhizobial bacteria and leguminous plants have evolved complex signal exchange mechanisms that allow a specific bacterial species to induce its host plant to form invasion structures through which the bacteria can enter the plant root. once the bacteria have been endocytosed within a host-membrane-bound compartment by root cells, the bacteria differentiate into a new form that can convert atmospheric nitrogen into ammonia. bacterial differentiation and nitrogen fixation are depend ...200717632573
structure of two melon regions reveals high microsynteny with sequenced plant species.in this study, two melon bacterial artificial chromosome (bac) clones have been sequenced and annotated. bac 1-21-10 spans 92 kb and contains the nsv locus conferring resistance to the melon necrotic spot virus (mnsv) in melon linkage group 11. bac 13j4 spans 98 kb and belongs to a bac contig containing resistance gene homologues, extending a previous sequenced region of 117 kb in linkage group 4. both regions have microsyntenic relationships to the model plant species arabidopsis thaliana, and ...200717665215
lysm domains mediate lipochitin-oligosaccharide recognition and nfr genes extend the symbiotic host range.legume-rhizobium symbiosis is an example of selective cell recognition controlled by host/non-host determinants. individual bacterial strains have a distinct host range enabling nodulation of a limited set of legume species and vice versa. we show here that expression of lotus japonicus nfr1 and nfr5 nod-factor receptor genes in medicago truncatula and l. filicaulis, extends their host range to include bacterial strains, mesorhizobium loti or dzl, normally infecting l. japonicus. as a result, th ...200717690687
medicago truncatula as a model for nonhost resistance in legume-parasitic plant interactions.crenate broomrape (orobanche crenata) is a root parasitic weed that represents a major constraint for grain legume production in mediterranean and west asian countries. medicago truncatula has emerged as an important model plant species for structural and functional genomics. the close phylogenic relationship of m. truncatula with crop legumes increases its value as a resource for understanding resistance against orobanche spp. different cytological methods were used to study the mechanisms of r ...200717693539
a novel nuclear protein interacts with the symbiotic dmi3 calcium- and calmodulin-dependent protein kinase of medicago truncatula.many higher plants establish symbiotic relationships with arbuscular mycorrhizal (am) fungi that improve their ability to acquire nutrients from the soil. in addition to establishing am symbiosis, legumes also enter into a nitrogen-fixing symbiosis with bacteria known as rhizobia that results in the formation of root nodules. several genes involved in the perception and transduction of bacterial symbiotic signals named "nod factors" have been cloned recently in model legumes through forward gene ...200717722695
growth and nitrogen fixation in lotus japonicus and medicago truncatula under nacl stress: nodule carbon metabolism.lotus japonicus and medicago truncatula model legumes, which form determined and indeterminate nodules, respectively, provide a convenient system to study plant-rhizobium interaction and to establish differences between the two types of nodules under salt stress conditions. we examined the effects of 25 and 50mm nacl doses on growth and nitrogen fixation parameters, as well as carbohydrate content and carbon metabolism of m. truncatula and l. japonicus nodules. the leghemoglobin (lb) content and ...200817728011
identification of a multigene family encoding putative beta-glucan-binding proteins in medicago truncatula.branched 1,6-1,3-beta-glucans from phytophthora sojae cell walls represent pathogen-associated molecular patterns (pamps) that have been shown to mediate the activation of plant defence reactions in many legumes. in soybean, a receptor protein complex containing a high affinity beta-glucan-binding protein (gbp) was identified and investigated in detail. in the model legume medicago truncatula, used for functional genomic studies of various plant-microbe interactions, a high-affinity beta-glucan- ...200817728012
recovery of nicotiana benthamiana plants from a necrotic response induced by a nepovirus is associated with rna silencing but not with reduced virus titer.recovery of plants from virus-induced symptoms is often described as a consequence of rna silencing, an antiviral defense mechanism. for example, recovery of nicotiana clevelandii from a nepovirus (tomato black ring virus) is associated with a decreased viral rna concentration and sequence-specific resistance to further virus infection. in this study, we have characterized the interaction of another nepovirus, tomato ringspot virus (torsv), with host defense responses during symptom induction an ...200717728227
strain-ecotype specificity in sinorhizobium meliloti-medicago truncatula symbiosis is correlated to succinoglycan oligosaccharide structure.molecular signals, including nod factors and succinoglycan, are necessary for the establishment of nitrogen-fixing nodules (fix+) in medicago truncatula-sinorhizobium meliloti symbiosis. this report shows that m. truncatula-s. meliloti interactions involve ecotype-strain specificity, as s. meliloti rm41 and nrg247 are fix+ (compatible) on m. truncatula a20 and fix- (incompatible) on m. truncatula a17, the fix phenotypes are reversed with s. meliloti nrg185 and nrg34, and there is a correlation b ...200717766412
ap2-erf transcription factors mediate nod factor dependent mt enod11 activation in root hairs via a novel cis-regulatory motif.rhizobium nod factors (nfs) are specific lipochitooligosaccharides that activate host legume signaling pathways essential for initiating the nitrogen-fixing symbiotic association. this study describes the characterization of cis-regulatory elements and trans-interacting factors that regulate nf-dependent and epidermis-specific gene transcription in medicago truncatula. detailed analysis of the mt enod11 promoter using deletion, mutation, and gain-of-function constructs has led to the identificat ...200717827349
early steps in proanthocyanidin biosynthesis in the model legume medicago truncatula.oligomeric proanthocyanidins (pas) composed primarily of epicatechin units accumulate in the seed coats of the model legume medicago truncatula, reaching maximal levels at around 20 d after pollination. genes encoding the single medicago anthocyanidin synthase (ans; ec 1.14.11.19) and leucoanthocyanidin reductase (lar; ec 1.17.1.3) were cloned and the corresponding enzymes functionally identified. recombinant mtans converted leucocyanidin to cyanidin, and, more efficiently, dihydroquercetin to t ...200717885080
genetic and physical localization of an anthracnose resistance gene in medicago truncatula.anthracnose of alfalfa, caused by the fungal pathogen colletotrichum trifolii, is one of the most destructive diseases of alfalfa worldwide. an improved understanding of the genetic and molecular mechanisms underlying host resistance will facilitate the development of resistant alfalfa cultivars, thus providing the most efficient and environmentally sound strategy to control alfalfa diseases. unfortunately, cultivated alfalfa has an intractable genetic system because of its tetrasomic inheritanc ...200717891371
chromosomal and symbiotic relationships of rhizobia nodulating medicago truncatula and m. laciniata.multilocus sequence typing (mlst) is a sequence-based method used to characterize bacterial genomes. this method was used to examine the genetic structure of medicago-nodulating rhizobia at the amra site, which is located in an arid region of tunisia. here the annual medics medicago laciniata and m. truncatula are part of the natural flora. the goal of this study was to identify whether distinct chromosomal groups of rhizobia nodulate m. laciniata because of its restricted requirement for specif ...200717921275
influence of the poly-3-hydroxybutyrate (phb) granule-associated proteins (phap1 and phap2) on phb accumulation and symbiotic nitrogen fixation in sinorhizobium meliloti rm1021.sinorhizobium meliloti cells store excess carbon as intracellular poly-3-hydroxybutyrate (phb) granules that assist survival under fluctuating nutritional conditions. phb granule-associated proteins (phasins) are proposed to regulate phb synthesis and granule formation. although the enzymology and genetics of phb metabolism in s. meliloti have been well characterized, phasins have not yet been described for this organism. comparison of the protein profiles of the wild type and a phb synthesis mu ...200717921298
differential expression of the tfiiia regulatory pathway in response to salt stress between medicago truncatula genotypes.soil salinity is one of the most significant abiotic stresses for crop plants, including legumes. these plants can establish root symbioses with nitrogen-fixing soil bacteria and are able to grow in nitrogen-poor soils. medicago truncatula varieties show diverse adaptive responses to environmental conditions, such as saline soils. we have compared the differential root growth of two genotypes of m. truncatula (108-r and jemalong a17) in response to salt stress. jemalong a17 is more tolerant to s ...200717951460
induction of a small heat shock protein and its functional roles in nicotiana plants in the defense response against ralstonia solanacearum.in tobacco (nicotiana tabacum), ralstonia solanacearum oe1-1 (rsoe1-1) is pathogenic, whereas r. solanacearum 8107 (rs8107) is nonpathogenic and induces the hypersensitive response (hr). to elucidate the molecular mechanisms of plant-r. solanacearum interactions, we used differential display to isolate a cdna fragment, a6, regulated in tobacco by inoculation with rsoe1-1. the deduced amino acid sequence predicted from full-length a6-cdna showed similarity to small heat shock proteins from arabid ...200717965181
different mechanisms for phytoalexin induction by pathogen and wound signals in medicago truncatula.cell suspensions of the model legume medicago truncatula accumulated the isoflavonoid phytoalexin medicarpin in response to yeast elicitor or methyl jasmonate (mj), accompanied by decreased levels of isoflavone glycosides in mj-treated cells. dna microarray analysis revealed rapid, massive induction of early (iso)flavonoid pathway gene transcripts in response to yeast elicitor, but not mj, and differential induction by the two elicitors of sets of genes encoding transcription factors, abc transp ...200717971436
subcellular localisation of medicago truncatula 9/13-hydroperoxide lyase reveals a new localisation pattern and activation mechanism for cyp74c enzymes.hydroperoxide lyase (hpl) is a key enzyme in plant oxylipin metabolism that catalyses the cleavage of polyunsaturated fatty acid hydroperoxides produced by the action of lipoxygenase (lox) to volatile aldehydes and oxo acids. the synthesis of these volatile aldehydes is rapidly induced in plant tissues upon mechanical wounding and insect or pathogen attack. together with their direct defence role towards different pathogens, these compounds are believed to play an important role in signalling wi ...200717983471
genetic dissection of resistance to anthracnose and powdery mildew in medicago truncatula.medicago truncatula was used to characterize resistance to anthracnose and powdery mildew caused by colletotrichum trifolii and erysiphe pisi, respectively. two isolates of e. pisi (ep-p from pea and ep-a from alfalfa) and two races of c. trifolii (races 1 and 2) were used in this study. the a17 genotype was resistant and displayed a hypersensitive response after inoculation with either pathogen, while lines f83005.5 and dza315.16 were susceptible to anthracnose and powdery mildew, respectively. ...200818052883
metabolomics reveals novel pathways and differential mechanistic and elicitor-specific responses in phenylpropanoid and isoflavonoid biosynthesis in medicago truncatula cell cultures.high-performance liquid chromatography coupled to ultraviolet photodiode array detection and ion-trap mass spectrometry was used to analyze the intra- and extracellular secondary product metabolome of medicago truncatula cell suspension cultures responding to yeast elicitor (ye) or methyl jasmonate (meja). data analysis revealed three phases of intracellular response to ye: a transient response in mainly (iso)flavonoid metabolites such as formononetin and biochanin-a that peaked at 12 to 18 h fo ...200818055588
the model plant medicago truncatula exhibits biparental plastid inheritance.the plastid, which originated from the endosymbiosis of a cyanobacterium, contains its own plastid dna (ptdna) that exhibits a unique mode of inheritance. approximately 80% of angiosperms show maternal inheritance, whereas the remainder exhibit biparental inheritance of ptdna. here we studied ptdna inheritance in the model legume, medicago truncatula. cytological analysis of mature pollen with dna-specific fluorescent dyes suggested that m. truncatula is one of the few model plants potentially s ...200818065422
3-hydroxy-3-methylglutaryl coenzyme a reductase 1 interacts with nork and is crucial for nodulation in medicago truncatula.nork in legumes encodes a receptor-like kinase that is required for nod factor signaling and root nodule development. using medicago truncatula nork as bait in a yeast two-hybrid assay, we identified 3-hydroxy-3-methylglutaryl coa reductase 1 (mt hmgr1) as a nork interacting partner. hmgr1 belongs to a multigene family in m. truncatula, and different hmgr isoforms are key enzymes in the mevalonate biosynthetic pathway leading to the production of a diverse array of isoprenoid compounds. testing ...200718156218
differential response of the plant medicago truncatula to its symbiont sinorhizobium meliloti or an exopolysaccharide-deficient mutant.sinorhizobium meliloti forms symbiotic, nitrogen-fixing nodules on the roots of medicago truncatula. the bacteria invade and colonize the roots through structures called infection threads. s. meliloti unable to produce the exopolysaccharide succinoglycan are unable to establish a symbiosis because they are defective in initiating the production of infection threads and in invading the plant. here, we use microarrays representing 16,000 m. truncatula genes to compare the differential transcriptio ...200818184805
large-scale insertional mutagenesis using the tnt1 retrotransposon in the model legume medicago truncatula.medicago truncatula is a fast-emerging model for the study of legume functional biology. we used the tobacco retrotransposon tnt1 to tag the medicago genome and generated over 7600 independent lines representing an estimated 190,000 insertion events. tnt1 inserted on average at 25 different locations per genome during tissue culture, and insertions were stable during subsequent generations in soil. analysis of 2461 tnt1 flanking sequence tags (fsts) revealed that tnt1 appears to prefer gene-rich ...200818208518
peanut gene expression profiling in developing seeds at different reproduction stages during aspergillus parasiticus infection.peanut (arachis hypogaea l.) is an important crop economically and nutritionally, and is one of the most susceptible host crops to colonization of aspergillus parasiticus and subsequent aflatoxin contamination. knowledge from molecular genetic studies could help to devise strategies in alleviating this problem; however, few peanut dna sequences are available in the public database. in order to understand the molecular basis of host resistance to aflatoxin contamination, a large-scale project was ...200818248674
systemic signaling of the plant nitrogen status triggers specific transcriptome responses depending on the nitrogen source in medicago truncatula.legumes can acquire nitrogen (n) from no(3)(-), nh(4)(+), and n(2) (through symbiosis with rhizobium bacteria); however, the mechanisms by which uptake and assimilation of these n forms are coordinately regulated to match the n demand of the plant are currently unknown. here, we find by use of the split-root approach in medicago truncatula plants that no(3)(-) uptake, nh(4)(+) uptake, and n(2) fixation are under general control by systemic signaling of plant n status. indeed, irrespective of the ...200818287487
recent advances in medicago truncatula genomics.legume rotation has allowed a consistent increase in crop yield and consequently in human population since the antiquity. legumes will also be instrumental in our ability to maintain the sustainability of our agriculture while facing the challenges of increasing food and biofuel demand. medicago truncatula and lotus japonicus have emerged during the last decade as two major model systems for legume biology. initially developed to dissect plant-microbe symbiotic interactions and especially legume ...200818288239
transcription of enod8 in medicago truncatula nodules directs enod8 esterase to developing and mature symbiosomes.in medicago truncatula nodules, the soil bacterium sinorhizobium meliloti reduces atmospheric dinitrogen into nitrogenous compounds that the legume uses for its own growth. in nitrogen-fixing nodules, each infected cell contains symbiosomes, which include the rhizobial cell, the symbiosome membrane surrounding it, and the matrix between the bacterium and the symbiosome membrane, termed the symbiosome space. here, we describe the localization of enod8, a nodule-specific esterase. the onset of eno ...200818321186
the possible role of an [fefe]-hydrogenase-like protein in the plant responses to changing atmospheric oxygen levels.the knockdown of a [fefe]-hydrogenase-like gene in the model plants medicago truncatula and arabidopsis thaliana resulted in a mutant with a dwarf phenotype. surprisingly, the phenotype is undistinguishable from wild type under hypoxic conditions. the heterologous expression of the plant gene in escherichia coli indicates that the resulting protein probably coordinates two [fe-s] clusters with different magnetic properties. sequence alignment analysis indicates that these two clusters would be t ...200818329103
evidence for communality in the primary determinants of cyp74 catalysis and of structural similarities between cyp74 and classical mammalian p450 enzymes.in silico structural analysis of cyp74c3, a membrane-associated p450 enzyme from the plant medicago truncatula (barrel medic) with hydroperoxide lyase (hpl) specificity, showed that it had strong similarities to the structural folds of the classical microsomal p450 enzyme from rabbits (cyp2c5). it was not only the secondary structure predictions that supported the analysis but site directed mutagenesis of the substrate interacting residues was also consistent with it. this led us to develop a su ...200818338380
two alternative recessive quantitative trait loci influence resistance to spring black stem and leaf spot in medicago truncatula.knowledge of the genetic basis of plant resistance to necrotrophic pathogens is incomplete and has been characterised in relatively few pathosystems. in this study, the cytology and genetics of resistance to spring black stem and leaf spot caused by phoma medicaginis, an economically important necrotrophic pathogen of medicago spp., was examined in the model legume m. truncatula.200818366746
api, a novel medicago truncatula symbiotic mutant impaired in nodule primordium invasion.genetic approaches have proved to be extremely useful in dissecting the complex nitrogen-fixing rhizobium-legume endosymbiotic association. here we describe a novel medicago truncatula mutant called api, whose primary phenotype is the blockage of rhizobial infection just prior to nodule primordium invasion, leading to the formation of large infection pockets within the cortex of noninvaded root outgrowths. the mutant api originally was identified as a double symbiotic mutant associated with a ne ...200818393613
a gene expression atlas of the model legume medicago truncatula.legumes played central roles in the development of agriculture and civilization, and today account for approximately one-third of the world's primary crop production. unfortunately, most cultivated legumes are poor model systems for genomic research. therefore, medicago truncatula, which has a relatively small diploid genome, has been adopted as a model species for legume genomics. to enhance its value as a model, we have generated a gene expression atlas that provides a global view of gene expr ...200818410479
nucleocytoplasmic-localized acyltransferases catalyze the malonylation of 7-o-glycosidic (iso)flavones in medicago truncatula.(iso)flavonoids are commonly accumulated as malonylated or acetylated glycoconjugates in legumes. sequence analysis on est database of the model legume medicago truncatula enabled us to identify nine cdna sequences encoding bahd super-family enzymes that are distinct from the most of the characterized anthocyanin/flavonol acyltransferase genes in other species. functional characterization revealed that three of these corresponding enzymes, mtmat1, 2 and 3, specifically recognize malonyl coa as a ...200818419782
the model legume medicago truncatula a17 is poorly matched for n2 fixation with the sequenced microsymbiont sinorhizobium meliloti 1021.medicago truncatula (barrel medic) a17 is currently being sequenced as a model legume, complementing the sequenced root nodule bacterial strain sinorhizobium meliloti 1021 (sm1021). in this study, the effectiveness of the sm1021-m. truncatula symbiosis at fixing n(2) was evaluated. n(2) fixation effectiveness was examined with eight medicago species and three accessions of m. truncatula with sm1021 and two other sinorhizobium strains. plant shoot dry weights, plant nitrogen content and nodule di ...200818422896
the medicago truncatula ortholog of arabidopsis ein2, sickle, is a negative regulator of symbiotic and pathogenic microbial associations.summary: the plant hormone ethylene negatively regulates bacterial infection and nodule formation in legumes in response to symbiotic rhizobia, but the molecular mechanism(s) of ethylene action in symbiosis remain obscure. we have identified and characterized multiple mutant alleles of the mtskl1 gene, which controls both ethylene sensitivity and nodule numbers. we show that this locus encodes the medicago truncatula ortholog of the arabidopsis ethylene signaling protein ein2. in addition to the ...200818435823
high levels of stable phytase accumulate in the culture medium of transgenic medicago truncatula cell suspension cultures.the use of plants for production of recombinant proteins is becoming widely accepted. more recently, plant cell cultures have been proposed as valuable systems for producing a wide range of biologically active proteins. such systems provide certain advantages over whole plants, but yields are still considered a limitation. in this study we established a medicago truncatula cell suspension line expressing phytase from aspergillus niger. phytase is an n-glycosylated enzyme that breaks down indiges ...200818446871
virus-induced gene silencing in medicago truncatula and lathyrus odorata.virus-induced gene silencing (vigs) has become an important reverse genetics tool for functional genomics. vigs vectors based on pea early browning virus (pebv, genus tobravirus) and bean pod mottle virus (genus comovirus) are available for the legume species pisum sativum and glycine max, respectively. with the aim of extending the application of the pebv vigs vector to other legumes, we examined susceptibility of 99 accessions representing 24 legume species including 21 accessions of medicago ...200818495283
microdiversity of burkholderiales associated with mycorrhizal and nonmycorrhizal roots of medicago truncatula.the genetic diversity of bacterial communities associated with mycorrhizal and nonmycorrhizal roots of medicago truncatula was characterized by two approaches. firstly, phylogenetic analysis was performed on 164 partial 16s rrna gene-intergenic spacer (igs) sequences from operational taxonomic units previously shown to be preferentially associated with mycorrhizal roots. these sequences were distributed into three branches corresponding to comamonadaceae, oxalobacteraceae and rubrivivax subgroup ...200818507681
gene expression profiling of m. truncatula transcription factors identifies putative regulators of grain legume seed filling.legume seeds represent a major source of proteins for human and livestock diets. the model legume medicago truncatula is characterized by a process of seed development very similar to that of other legumes, involving the interplay of sets of transcription factors (tfs). here, we report the first expression profiling of over 700 m. truncatula genes encoding putative tfs throughout seven stages of seed development, obtained using real-time quantitative rt-pcr. a total of 169 tfs were selected whic ...200818528765
a positive regulatory role for ljerf1 in the nodulation process is revealed by systematic analysis of nodule-associated transcription factors of lotus japonicus.we have used reverse genetics to identify genes involved in legume-rhizobium symbiosis in lotus japonicus. we obtained the sequences of 20 putative transcription factors from previously reported large-scale transcriptome data. the transcription factors were classified according to their dna binding domains and patterns of expression during the nodulation process. we identified two homologues of medicago truncatula mthap2-1, which encodes a ccaat-binding protein and has been shown to play a role ...200818567832
regioselective synthesis of plant (iso)flavone glycosides in escherichia coli.the flavonoids genistein, biochanin a, luteolin, quercetin, and kaempferol are plant natural products with potentially useful pharmacological and nutraceutical activities. these natural products usually exist in plants as glycosides, and their glycosylation has a remarkable influence on their pharmacokinetic properties. the glycosyltransferases ugt71g1 and ugt73c8 from medicago truncatula are excellent reagents for the regioselective glycosylation of (iso)flavonoids in escherichia coli grown in ...200818568307
closely related members of the medicago truncatula pht1 phosphate transporter gene family encode phosphate transporters with distinct biochemical activities.phosphorus is one of the essential mineral nutrients required by all living cells. plants assimilate phosphate (pi) from the soil, and their root systems encounter tremendous variation in pi concentration, both temporally and spatially. genome sequence data indicate that plant genomes contain large numbers of genes predicted to encode pi transporters, the functions of which are largely unexplored. here we present a comparative analysis of four very closely related pi transporters of the pht1 fam ...200818596039
a novel type of thioredoxin dedicated to symbiosis in legumes.thioredoxins (trxs) constitute a family of small proteins in plants. this family has been extensively characterized in arabidopsis (arabidopsis thaliana), which contains six different trx types: f, m, x, and y in chloroplasts, o in mitochondria, and h mainly in cytosol. a detailed study of this family in the model legume medicago truncatula, realized here, has established the existence of two isoforms that do not belong to any of the types previously described. as no possible orthologs were furt ...200818614707
evidence for the involvement in nodulation of the two small putative regulatory peptide-encoding genes mtralfl1 and mtdvl1.nod factors are key bacterial signaling molecules regulating the symbiotic interaction between bacteria known as rhizobia and leguminous plants. studying plant host genes whose expression is affected by nod factors has given insights into early symbiotic signaling and development. here, we used a double supernodulating mutant line that shows increased sensitivity to nod factors to study the nod factor-regulated transcriptome. using microarrays containing more than 16,000 70-mer oligonucleotide p ...200818616408
the rpg gene of medicago truncatula controls rhizobium-directed polar growth during infection.rhizobia can infect roots of host legume plants and induce new organs called nodules, in which they fix atmospheric nitrogen. infection generally starts with root hair curling, then proceeds inside newly formed, intracellular tubular structures called infection threads. a successful symbiotic interaction relies on infection threads advancing rapidly at their tips by polar growth through successive cell layers of the root toward developing nodule primordia. to identify a plant component that cont ...200818621693
virus-induced gene silencing (vigs) as a reverse genetic tool to study development of symbiotic root nodules.virus-induced gene silencing (vigs) can provide a shortcut to plants with altered expression of specific genes. here, we report that vigs of the nodule inception gene (nin) can alter the nodulation phenotype and nin gene expression in pisum sativum. psnin was chosen as target because of the distinct non-nodulating phenotype of nin mutants in p. sativum, lotus japonicus, and medicago truncatula. the vector based on pea early browning virus (pebv) was engineered to carry one of three nonoverlappin ...200818624636
expression of medicago truncatula genes responsive to nitric oxide in pathogenic and symbiotic conditions.nitric oxide (no) is involved in diverse physiological processes in plants, including growth, development, response to pathogens, and interactions with beneficial microorganisms. in this work, a dedicated microarray representing the widest database available of no-related transcripts in plants has been produced with 999 genes identified by a cdna amplified fragment length polymorphism analysis as modulated in medicago truncatula roots treated with two no donors. the microarray then was used to m ...200818624641
peroxisomal delta(3),delta(2)-enoyl coa isomerases and evolution of cytosolic paralogues in embryophytes.delta(3),delta(2)-enoyl coa isomerase (eci) is an enzyme that participates in the degradation of unsaturated fatty acids through the beta-oxidation cycle. three genes encoding delta(3),delta(2)-enoyl coa isomerases and named ateci1, ateci2 and ateci3 have been identified in arabidopsis thaliana. when expressed heterologously in saccharomyces cerevisiae, all three eci proteins were targeted to the peroxisomes and enabled the yeast deltaeci1 mutant to degrade 10z-heptadecenoic acid, demonstrating ...200818657232
cloning of two cdnas encoding a family of atp sulfurylase from camellia sinensis related to selenium or sulfur metabolism and functional expression in escherichia coli.atp sulfurylase, the first enzyme in the sulfate assimilation pathway of plants, catalyzes the formation of adenosine phosphosulfate from atp and sulfate. here we report the cloning of two cdnas encoding atp sulfurylase (aps1 and aps2) from camellia sinensis. they were isolated by rt-pcr and race-pcr reactions. the expression of aps1 and aps2 are correlated with the presence of atp sulfurylase enzyme activity in cell extracts. aps1 is a 1415-bp cdna with an open reading frame predicted to encode ...200818657428
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