| identification and characterization of several new members of the zip family of metal ion transporters in medicago truncatula. | to broaden our understanding of micronutrient metal transport in plants, we have identified cdnas for six new metal transporters in the model legume medicago truncatula. all of the predicted proteins have high similarity to the zip protein family, and have been designated mtzip1, mtzip3, mtzip4, mtzip5, mtzip6, and mtzip7. the six predicted proteins ranged from 350 to 372 amino acids in length; sequence analysis revealed that all proteins contained eight transmembrane domains and the highly cons ... | 2004 | 15316291 |
| the spatial expression patterns of a phosphate transporter (mtpt1) from medicago truncatula indicate a role in phosphate transport at the root/soil interface. | the movement of phosphate from the soil into plant root cells is the first of many crucial transport events required to supply phosphorous (p) to cells throughout the plant. in addition to the ability to acquire phosphate from the soil, the majority of the vascular plants are able to form arbuscular mycorrhizal associations in which phosphate may be delivered to the cortex via a fungus. previously, we cloned two phosphate transporter genes, mtpt1 and mtpt2 from medicago truncatula roots. complem ... | 2001 | 11208020 |
| nod factor-treated medicago truncatula roots and seeds show an increased number of nodules when inoculated with a limiting population of sinorhizobium meliloti. | medicago truncatula is a model legume plant that interacts symbiotically with sinorhizobium meliloti, the alfalfa symbiont. this process involves a molecular dialogue between the bacterium and the plant. legume roots exude flavonoids that induce the expression of a set of rhizobial genes, the nod genes, which are essential for nodulation and determination of the host range. in turn, nod genes control the synthesis of lipo-chito-oligosaccharides (lcos), nod factors, which are bacteria-to-plant si ... | 2004 | 15361530 |
| increased abundance of mtd1 and mtd2 mrnas in nodules of decapitated medicago truncatula. | to gain insight into the molecular processes occurring in root nodule metabolism after stress, we used a mrna differential display (ddrt-pcr) approach to identify cdnas corresponding to genes whose expression is enhanced in nodules of decapitated medicago truncatula plants. two full-length cdnas of plant origin were isolated (mtd1 and mtd2). sequence analysis revealed that mtd1 is identical to an est clone (accession number aw559774) expressed in roots of m. truncatula upon infection with phytop ... | 2000 | 11197323 |
| infection-related activation of the cg12 promoter is conserved between actinorhizal and legume-rhizobia root nodule symbiosis. | two nitrogen-fixing root nodule symbioses between soil bacteria and higher plants have been described: the symbiosis between legume and rhizobia and actinorhizal symbioses between plants belonging to eight angiosperm families and the actinomycete frankia. we have recently shown that the subtilisin-like ser protease gene cg12 (isolated from the actinorhizal plant casuarina glauca) is specifically expressed during plant cell infection by frankia. here we report on the study of c. glauca cg12 promo ... | 2004 | 15466224 |
| expression profiling in medicago truncatula identifies more than 750 genes differentially expressed during nodulation, including many potential regulators of the symbiotic program. | in this study, we describe a large-scale expression-profiling approach to identify genes differentially regulated during the symbiotic interaction between the model legume medicago truncatula and the nitrogen-fixing bacterium sinorhizobium meliloti. macro- and microarrays containing about 6,000 probes were generated on the basis of three cdna libraries dedicated to the study of root symbiotic interactions. the experiments performed on wild-type and symbiotic mutant material led us to identify a ... | 2004 | 15466239 |
| pharmacological evidence that multiple phospholipid signaling pathways link rhizobium nodulation factor perception in medicago truncatula root hairs to intracellular responses, including ca2+ spiking and specific enod gene expression. | rhizobium nodulation (nod) factors are specific lipochito-oligosaccharide signals essential for initiating in root hairs of the host legume developmental responses that are required for controlled entry of the microsymbiont. in this article, we focus on the nod factor signal transduction pathway leading to specific and cell autonomous gene activation in medicago truncatula cv jemalong in a study making use of the nod factor-inducible mtenod11 gene. first, we show that pharmacological antagonists ... | 2004 | 15489277 |
| nip, a symbiotic medicago truncatula mutant that forms root nodules with aberrant infection threads and plant defense-like response. | to investigate the legume-rhizobium symbiosis, we isolated and studied a novel symbiotic mutant of the model legume medicago truncatula, designated nip (numerous infections and polyphenolics). when grown on nitrogen-free media in the presence of the compatible bacterium sinorhizobium meliloti, the nip mutant showed nitrogen deficiency symptoms. the mutant failed to form pink nitrogen-fixing nodules that occur in the wild-type symbiosis, but instead developed small bump-like nodules on its roots ... | 2004 | 15516506 |
| genetic analysis of calcium spiking responses in nodulation mutants of medicago truncatula. | the symbiotic interaction between medicago truncatula and sinorhizobium meliloti results in the formation of nitrogen-fixing nodules on the roots of the host plant. the early stages of nodule formation are induced by bacteria via lipochitooligosaccharide signals known as nod factors (nfs). these nfs are structurally specific for bacterium-host pairs and are sufficient to cause a range of early responses involved in the host developmental program. early events in the signal transduction of nfs ar ... | 2000 | 11078514 |
| two branches of the lupeol synthase gene in the molecular evolution of plant oxidosqualene cyclases. | two new triterpene synthase cdnas, named as oew and trw, were cloned from olive leaves (olea europaea) and from dandelion roots (taraxacum officinale), respectively, by the pcr method with primers designed from the conserved sequences found in the known oxidosqualene cyclases. their orfs consisted of 2274 bp nucleotides and coded for 758 amino acid long polypeptides. they shared high sequence identity (78%) to each other, while they showed only about 60% identities to the known triterpene syntha ... | 1999 | 10542078 |
| characterization of the mt4 gene from medicago truncatula. | previously we identified mt4, a phosphate starvation inducible cdna from medicago truncatula which is down-regulated in roots in response to phosphate fertilization as well as colonization by arbuscular mycorrhizal (am) fungi (am). here we present further studies of mt4. expression was highly sensitive to exogenous applications of phosphate fertilizer; transcripts were abundant in roots fertilized with nutrient solution lacking phosphate, reduced when fertilized with 0.02 or 0.1 mm phosphate and ... | 1998 | 9714729 |
| the symbiotic defect in a sinorhizobium meliloti lipopolysaccharide mutant can be overcome by expression of other surface polysaccharides. | in this work we have examined the extent of functional complementation in symbiosis among different sinorhizobium meliloti surface polysaccharides including lipopolysaccharide (lps). we show that a symbiotic deficiency associated with an lps defect can be reversed by appropriate expression of other surface polysaccharides such as galactoglucan (epsii) and a particular form of capsular polysaccharide (kdops). it is noteworthy that, while succinoglycan epsi and lps cannot functionally substitute f ... | 2004 | 15567281 |
| effect of salinity on root-nodule conductance to the oxygen diffusion in the medicago truncatula-sinorhizobium meliloti symbiosis. | in order to determine the effect of salinity on the nodule conductance, oxygen uptake by the nodulated roots was measured by registering the concentration of o(2) as a function of time in a tight incubator of known volume containing the nodulated roots of medicago truncatula. four lines, namely tn8.20 and tn6.18, originated from local populations, f83005.5 originated from var (france) and jemalong 6, a cultivar from australia, were hydroponically grown in 250 ml glass bottles under semi-controll ... | 2004 | 15596103 |
| an auxin-inducible gene from loblolly pine (pinus taeda l.) is differentially expressed in mature and juvenile-phase shoots and encodes a putative transmembrane protein. | we have isolated a gene from loblolly pine, 5ng4, that is highly and specifically induced by auxin in juvenile loblolly pine shoots prior to adventitious root formation, but substantially down-regulated in physiologically mature shoots that are adventitious rooting incompetent. 5ng4 was highly auxin-induced in roots, stems and hypocotyls, organs that can form either lateral or adventitious roots following an auxin treatment, but was not induced to the same level in needles and cotyledons, organs ... | 2004 | 14722770 |
| fungal elicitation of signal transduction-related plant genes precedes mycorrhiza establishment and requires the dmi3 gene in medicago truncatula. | suppressive subtractive hybridization and expressed sequence tag sequencing identified 29 plant genes which are upregulated during the appressorium stage of mycorrhiza establishment between medicago truncatula j5 (myc+) and glomus mosseae. eleven genes coding plant proteins with predicted functions in signal transduction, transcription, and translation were investigated in more detail for their relation to early events of symbiotic interactions. expression profiling showed that the genes are act ... | 2004 | 15597744 |
| proteomic approach: identification of medicago truncatula proteins induced in roots after infection with the pathogenic oomycete aphanomyces euteiches. | the legume root rot disease caused by the oomycete pathogen aphanomyces euteiches is one major yield reducing factor in legume crop production. a comparative proteomic approach was carried out in order to identify proteins of the model legume medicago truncatula which are regulated after an infection with a. euteiches . several proteins were identified by two dimensional gel electrophoresis to be differentially expressed after pathogen challenge. densitometric evaluation of expression values sho ... | 2004 | 15604668 |
| a diffusible factor from arbuscular mycorrhizal fungi induces symbiosis-specific mtenod11 expression in roots of medicago truncatula. | using dual cultures of arbuscular mycorrhizal (am) fungi and medicago truncatula separated by a physical barrier, we demonstrate that hyphae from germinating spores produce a diffusible factor that is perceived by roots in the absence of direct physical contact. this am factor elicits expression of the nod factor-inducible gene mtenod11, visualized using a pmtenod11-gusa reporter. transgene induction occurs primarily in the root cortex, with expression stretching from the zone of root hair emerg ... | 2003 | 12644648 |
| expression of a xyloglucan endotransglucosylase/hydrolase gene, mt-xth1, from medicago truncatula is induced systemically in mycorrhizal roots. | xyloglucan endotransglucosylase/hydrolases (xth) are enzymes that catalyze the hydrolysis and transglycosylation of xyloglucan polymers in plant cell walls. previously, we isolated a cdna from mycorrhizal roots of medicago truncatula that is predicted to encode an xth [van buuren, m.l., maldonado-mendoza, i.e., trieu, a.t., blaylock, l.a., harrison, m.j., 1999. novel genes induced during an arbuscular mycorrhizal (am) symbiosis between m. truncatula and g. versiforme. mol. plant-microb. interact ... | 2005 | 15716119 |
| regulation of enteric endophytic bacterial colonization by plant defenses. | bacterial endophytes reside within the interior of plants without causing disease or forming symbiotic structures. some endophytes, such as klebsiella pneumoniae 342 (kp342), enhance plant growth and nutrition. others, such as salmonella enterica serovar typhimurium (s. typhimurium), are human pathogens that contaminate raw produce. several lines of evidence are presented here to support the hypothesis that plant defense response pathways regulate colonization by endophytic bacteria. an ethylene ... | 2005 | 15720086 |
| the lipid a substructure of the sinorhizobium meliloti lipopolysaccharides is sufficient to suppress the oxidative burst in host plants. | medicago sativa (alfalfa), medicago truncatula and nicotiana tabacum cell suspension cultures, responding to elicitation with the production of reactive oxygen species (ros), were used to analyse the suppressor (and elicitor) activity of lipopolysaccharides (lps) of the symbiotic soil bacterium sinorhizobium meliloti. in order to identify the epitopes of the lps molecule recognized by the plant, s. meliloti mutants defective in lps biosynthesis and hydrolytically obtained lipid a were analysed f ... | 2005 | 15720666 |
| biochemical characterization of symbiosome membrane proteins from medicago truncatula root nodules. | the symbiosome membrane represents a specialized plant membrane that forms both a structural and a functional interface between the legume plant and its bacterial counterpart. in this study, the symbiosome membrane protein profile from the model system medicago truncatula and the corresponding bacterium sinorhizobium meliloti was examined using two-dimensional electrophoresis and microcapillary high-performance liquid chromatography (hplc) tandem mass spectrometry. the identities of 51 proteins ... | 2004 | 14760646 |
| the typa gene is required for stress adaptation as well as for symbiosis of sinorhizobium meliloti 1021 with certain medicago truncatula lines. | in this article, we describe the typa gene of sinorhizobium meliloti, the orthologue of typa/bipa genes found in a wide range of bacteria. we found that typa was required for survival of s. meliloti under certain stress conditions, such as growth at low temperature or low ph and in the presence of sodium dodecyl sulfate (sds). the cold-sensitive phenotype of both escherichia coli bipa and s. meliloti typa mutants were cross-complemented, indicating that the two genes are functionally equivalent. ... | 2004 | 15000390 |
| the endosymbiosis-induced genes enod40 and ccs52a are involved in endoparasitic-nematode interactions in medicago truncatula. | plants associate with a wide range of mutualistic and parasitic biotrophic organisms. here, we investigated whether beneficial plant symbionts and biotrophic pathogens induce distinct or overlapping regulatory pathways in medicago truncatula. the symbiosis between sinorhizobium meliloti and this plant results in the formation of nitrogen-fixing root nodules requiring the activation of specific genes in the host plant. we studied expression patterns of nodule-expressed genes after infection with ... | 2002 | 12437298 |
| glutathione and homoglutathione play a critical role in the nodulation process of medicago truncatula. | legumes form a symbiotic interaction with bacteria of the rhizobiaceae family to produce nitrogen-fixing root nodules under nitrogen-limiting conditions. this process involves the recognition of the bacterial nod factors by the plant which mediates the entry of the bacteria into the root and nodule organogenesis. we have examined the importance of the low molecular weight thiols, glutathione (gsh) and homoglutathione (hgsh), during the nodulation process in the model legume medicago truncatula. ... | 2005 | 15782639 |
| grafting between model legumes demonstrates roles for roots and shoots in determining nodule type and host/rhizobia specificity. | previous grafting experiments have demonstrated that legume shoots play a critical role in symbiotic development of nitrogen-fixing root nodules by regulating nodule number. here, reciprocal grafting experiments between the model legumes lotus japonicus and medicago truncatula were carried out to investigate the role of the shoot in the host-specificity of legume-rhizobia symbiosis and nodule type. lotus japonicus is nodulated by mesorhizobium loti and makes determinate nodules, whereas m. trunc ... | 2005 | 15824071 |
| a kunitz trypsin inhibitor from chickpea (cicer arietinum l.) that exerts anti-metabolic effect on podborer (helicoverpa armigera) larvae. | chickpea (cicer arietinum l.) seeds contain bowman-birk proteinase inhibitors, which are ineffective against the digestive proteinases of larvae of the insect pest helicoverpa armigera. we have identified and purified a low expressing proteinase inhibitor (pi), distinct from the bowman-birk inhibitors and active against h. armigera gut proteinases (hgp), from chickpea seeds. n-terminal sequencing of this hgp inhibitor revealed a sequence similar to reported pea (pisum sativum) and chickpea alpha ... | 2005 | 15830127 |
| a phosphate transporter from medicago truncatula involved in the acquisition of phosphate released by arbuscular mycorrhizal fungi. | many plants have the capacity to obtain phosphate via a symbiotic association with arbuscular mycorrhizal (am) fungi. in am associations, the fungi release phosphate from differentiated hyphae called arbuscules, that develop within the cortical cells, and the plant transports the phosphate across a symbiotic membrane, called the periarbuscular membrane, into the cortical cell. in medicago truncatula, a model legume used widely for studies of root symbioses, it is apparent that the phosphate tran ... | 2002 | 12368495 |
| a nonsymbiotic root hair tip growth phenotype in nork-mutated legumes: implications for nodulation factor-induced signaling and formation of a multifaceted root hair pocket for bacteria. | the medicago truncatula does not make infections (dmi2) mutant is mutated in the nodulation receptor-like kinase, nork. here, we report that nork-mutated legumes of three species show an enhanced touch response to experimental handling, which results in a nonsymbiotic root hair phenotype. when care is taken not to induce this response, dmi2 root hairs respond morphologically like the wild type to nodulation factor (nf). global nf application results in root hair deformation, and nf spot applicat ... | 2004 | 15031407 |
| accumulation of reactive oxygen species in arbuscular mycorrhizal roots. | we investigated the accumulation of reactive oxygen species (ros) in arbuscular mycorrhizal (am) roots from medicago truncatula, zea mays and nicotiana tabacum using three independent staining techniques. colonized root cortical cells and the symbiotic fungal partner were observed to be involved in the production of ros. extraradical hyphae and spores from glomus intraradices accumulated small levels of ros within their cell wall and produced ros within the cytoplasm in response to stress. withi ... | 2005 | 15875223 |
| insertional mutagenesis: a swiss army knife for functional genomics of medicago truncatula. | legumes are second only to grasses in worldwide economic importance, and understanding their molecular genetics is vital to the breeding of important grain and forage legumes. over the past decade, medicago truncatula has been selected as a model plant in which to study biological processes that are unique and pertinent to legumes, and that cannot easily be studied in arabidopsis. here, we discuss the most common tools for introducing and analyzing genetic mutations in m. truncatula. because tra ... | 2005 | 15882655 |
| nod factor signaling genes and their function in the early stages of rhizobium infection. | a lipochitosaccharide-based signal molecule that is secreted by rhizobium, named nod factor (nf), induces root nodule formation in legumes. this molecule is also essential for the establishment of bacterial infection. genetic analyses in the legume species lotus japonicus and medicago truncatula have led to the identification of many components of the nf signaling cascade. at least three of these genes do not function exclusively in the rhizobium symbiosis but are also essential for the formatio ... | 2005 | 15955723 |
| nodulation signaling in legumes requires nsp2, a member of the gras family of transcriptional regulators. | rhizobial bacteria enter a symbiotic interaction with legumes, activating diverse responses in roots through the lipochito oligosaccharide signaling molecule nod factor. here, we show that nsp2 from medicago truncatula encodes a gras protein essential for nod-factor signaling. nsp2 functions downstream of nod-factor-induced calcium spiking and a calcium/calmodulin-dependent protein kinase. we show that nsp2-gfp expressed from a constitutive promoter is localized to the endoplasmic reticulum/nucl ... | 2005 | 15961668 |
| the latd gene of medicago truncatula is required for both nodule and root development. | the evolutionary origins of legume root nodules are largely unknown. we have identified a gene, latd, of the model legume medicago truncatula, that is required for both nodule and root development, suggesting that these two developmental processes may share a common evolutionary origin. the latd mutant plants initiate nodule formation but do not complete it, resulting in immature, non-nitrogen-fixing nodules. similarly, lateral roots initiate, but remain short stumps. the primary root, which ini ... | 2005 | 15986921 |
| a mass spectrometry method for measuring 15n incorporation into pheophytin. | the 15n content of pheophytin, the magnesium-free derivative of chlorophyll, can be measured with great accuracy and precision using positive-ion atmospheric pressure ionization electrospray mass spectroscopy following a simple solvent extraction of small amounts of plant tissue. the molecular weight of pheophytin prepared from chlamydomonas reinhardtii grown in different ratios of 14n/15n showed linear regression with the isotopic input, with a precision of 0.5-1%. using an isotope dilution str ... | 2002 | 12202237 |
| formation of organelle-like n2-fixing symbiosomes in legume root nodules is controlled by dmi2. | in most legume nodules, the n2-fixing rhizobia are present as organelle-like structures inside their host cells. these structures, named symbiosomes, contain one or a few rhizobia surrounded by a plant membrane. symbiosome formation requires the release of bacteria from cell-wall-bound infection threads. in primitive legumes, rhizobia are hosted in intracellular infection threads that, in contrast to symbiosomes, are bound by a cell wall. the formation of symbiosomes is presumed to represent a m ... | 2005 | 16006515 |
| construction and validation of cdna-based mt6k-rit macro- and microarrays to explore root endosymbioses in the model legume medicago truncatula. | to construct macro- and microarray tools suitable for expression profiling in root endosymbioses of the model legume medicago truncatula, we pcr-amplified a total of 6048 cdna probes representing genes expressed in uninfected roots, mycorrhizal roots and young root nodules [nucleic acids res. 30 (2002) 5579]. including additional probes for either tissue-specific or constitutively expressed control genes, 5651 successfully amplified gene-specific probes were used to grid macro- and to spot micro ... | 2004 | 15129719 |
| munich information center for protein sequences plant genome resources: a framework for integrative and comparative analyses 1(w). | with several plant genomes sequenced, the power of comparative genome analysis can now be applied. however, genome-scale cross-species analyses are limited by the effort for data integration. to develop an integrated cross-species plant genome resource, we maintain comprehensive databases for model plant genomes, including arabidopsis (arabidopsis thaliana), maize (zea mays), medicago truncatula, and rice (oryza sativa). integration of data and resources is emphasized, both in house as well as w ... | 2005 | 16010004 |
| sinorhizobium meliloti metabolism in the root nodule: a proteomic perspective. | the proteome of the model symbiotic bacterium, sinorhizobium meliloti was examined to determine the enzymatic reactions and cell processes that occur when s. meliloti occupies the root nodules of medicago truncatula and melilotus alba. the proteomes of the nodule bacteria were compared to that of s. meliloti grown under laboratory cultured conditions as an additional control. all the detectable protein spots on the two-dimensional (2-d) gels between ph 4-7 were analyzed. in total, the identity o ... | 2004 | 15221743 |
| soil nematodes mediate positive interactions between legume plants and rhizobium bacteria. | symbiosis between legume species and rhizobia results in the sequestration of atmospheric nitrogen into ammonium, and the early mechanisms involved in this symbiosis have become a model for plant-microbe interactions and thus highly amenable for agricultural applications. the working model for this interaction states that the symbiosis is the outcome of a chemical/molecular dialogue initiated by flavonoids produced by the roots of legumes and released into the soil as exudates, which specificall ... | 2005 | 16025342 |
| plants as bioreactors: a comparative study suggests that medicago truncatula is a promising production system. | plants are emerging as a promising alternative to conventional platforms for the large-scale production of recombinant proteins. this field of research, known as molecular farming, is developing rapidly and several plant-derived recombinant proteins are already in advanced clinical trials. however, the full potential of molecular farming can only be realized if we gain a fundamental understanding of biological processes regulating the production and accumulation of functional recombinant protein ... | 2005 | 16026877 |
| guab activity is required in rhizobium tropici during the early stages of nodulation of determinate nodules but is dispensable for the sinorhizobium meliloti-alfalfa symbiotic interaction. | the guab mutant strain rhizobium tropici ciat8999-10t is defective in symbiosis with common bean, forming nodules that lack rhizobial content. in order to investigate the timing of the guab requirement during the nodule formation on the host common bean by the strain ciat899-10.t, we constructed gene fusions in which the guab gene is expressed under the control of the symbiotic promoters noda, baca, and nifh. our data indicated that the guab is required from the early stages of nodulation becaus ... | 2005 | 16042020 |
| transcript enrichment of nod factor-elicited early nodulin genes in purified root hair fractions of the model legume medicago truncatula. | this article describes an efficient procedure to study nod factor-induced gene expression in root hairs of the model legume medicago truncatula. by developing an improved method of fracturing frozen root hairs, it has been possible to obtain a highly purified root hair fraction from m. truncatula seedlings yielding sufficient rna for real-time quantitative rt-pcr expression analysis. after nod factor treatment it was possible to detect up to 100-fold increases of mtenod11 and pmtenod11-gus trans ... | 2005 | 16043451 |
| microtubules guide root hair tip growth. | the ability to establish cell polarity is crucial to form and function of an individual cell. polarity underlies critical processes during cell development, such as cell growth, cell division, cell differentiation and cell signalling. interphase cytoplasmic microtubules in tip-growing fission yeast cells have been shown to play a particularly important role in regulating cell polarity. by placing proteins that serve as spatial cues in the cell cortex of the expanding tip, microtubules determine ... | 2005 | 16101908 |
| organization and metabolism of plastids and mitochondria in arbuscular mycorrhizal roots of medicago truncatula. | colonization of root cortical cells by arbuscular mycorrhizal fungi leads to marked cytological changes of plastids and mitochondria. plastids in particular are forming tubular extensions partially connecting individual organelles in a network-like way. these cytological changes correspond to an increased need for plastid and mitochondrial products during establishment and functioning of the symbiosis. the analysis of metabolite and transcript levels in mycorrhizal and nonmycorrhizal roots from ... | 2005 | 16126866 |
| impact of sewage sludges on medicago truncatula symbiotic proteome. | the effects of sewage sludges were investigated on the symbiotic interactions between the model plant medicago truncatula and the arbuscular mycorrhizal fungus glomus mosseae or the rhizobial bacteria sinorhizobium meliloti. by comparison to a control sludge showing positive effects on plant growth and root symbioses, sludges enriched with polycylic aromatic hydrocarbons or heavy metals were deleterious. symbiosis-related proteins were detected and identified by two-dimensional electrophoresis a ... | 2004 | 15276460 |
| phosphorylation and subsequent interaction with 14-3-3 proteins regulate plastid glutamine synthetase in medicago truncatula. | in this report we demonstrate that plastid glutamine synthetase of medicago truncatula (mtgs2) is regulated by phosphorylation and 14-3-3 interaction. to investigate regulatory aspects of gs2 phosphorylation, we have produced non-phosphorylated gs2 proteins by expressing the plant cdna in e. coli and performed in vitro phosphorylation assays. the recombinant isoenzyme was phosphorylated by calcium dependent kinase(s) present in leaves, roots and nodules. using an (his)6-tagged 14-3-3 protein col ... | 2006 | 16136328 |
| pseudomonas fluorescens and glomus mosseae trigger dmi3-dependent activation of genes related to a signal transduction pathway in roots of medicago truncatula. | plant genes induced during early root colonization of medicago truncatula gaertn. j5 by a growth-promoting strain of pseudomonas fluorescens (c7r12) have been identified by suppressive subtractive hybridization. ten m. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between m. truncatula and p. fluorescens, up to 8 d after root inoculation. gene expression was not significantly enhanced ... | 2005 | 16183836 |
| nod factors and a diffusible factor from arbuscular mycorrhizal fungi stimulate lateral root formation in medicago truncatula via the dmi1/dmi2 signalling pathway. | legumes form two different types of intracellular root symbioses, with fungi and bacteria, resulting in arbuscular mycorrhiza and nitrogen-fixing nodules, respectively. rhizobial signalling molecules, called nod factors, play a key role in establishing the rhizobium-legume association and genes have been identified in medicago truncatula that control a nod factor signalling pathway leading to nodulation. three of these genes, the so-called dmi1, dmi2 and dmi3 genes, are also required for formati ... | 2005 | 16212600 |
| differential antifungal and calcium channel-blocking activity among structurally related plant defensins. | plant defensins are a family of small cys-rich antifungal proteins that play important roles in plant defense against invading fungi. structures of several plant defensins share a cys-stabilized alpha/beta-motif. structural determinants in plant defensins that govern their antifungal activity and the mechanisms by which they inhibit fungal growth remain unclear. alfalfa (medicago sativa) seed defensin, msdef1, strongly inhibits the growth of fusarium graminearum in vitro, and its antifungal acti ... | 2004 | 15299136 |
| proteomic profiling unravels insights into the molecular background underlying increased aphanomyces euteiches-tolerance of medicago truncatula. | to investigate the molecular mechanisms underlying susceptibility of legumes to the root pathogen aphanomyces euteiches (oomycota), comparative proteomic studies have been carried out. in a first approach, we have analysed two medicago truncatula lines of the french core collection (f83.005-5 (r2002) and f83.005-9 (r2002)), which showed either increased or decreased susceptibility to a. euteiches as compared to the widely adopted line a17. several proteins were identified to be differentially in ... | 2005 | 16235107 |
| suppression of allene oxide cyclase in hairy roots of medicago truncatula reduces jasmonate levels and the degree of mycorrhization with glomus intraradices. | during the symbiotic interaction between medicago truncatula and the arbuscular mycorrhizal (am) fungus glomus intraradices, an endogenous increase in jasmonic acid (ja) occurs. two full-length cdnas coding for the ja-biosynthetic enzyme allene oxide cyclase (aoc) from m. truncatula, designated as mtaoc1 and mtaoc2, were cloned and characterized. the aoc protein was localized in plastids and found to occur constitutively in all vascular tissues of m. truncatula. in leaves and roots, mtaocs are e ... | 2005 | 16244141 |
| methylotrophic metabolism is advantageous for methylobacterium extorquens during colonization of medicago truncatula under competitive conditions. | facultative methylotrophic bacteria of the genus methylobacterium are commonly found in association with plants. inoculation experiments were performed to study the importance of methylotrophic metabolism for colonization of the model legume medicago truncatula. competition experiments with methylobacterium extorquens wild-type strain am1 and methylotrophy mutants revealed that the ability to use methanol as a carbon and energy source provides a selective advantage during colonization of m. trun ... | 2005 | 16269765 |
| arbuscular mycorrhizal fungi elicit a novel intracellular apparatus in medicago truncatula root epidermal cells before infection. | the penetration of arbuscular mycorrhizal (am) fungi through the outermost root tissues of the host plant is a critical step in root colonization, ultimately leading to the establishment of this ecologically important endosymbiotic association. to evaluate the role played by the host plant during am infection, we have studied in vivo cellular dynamics within medicago truncatula root epidermal cells using green fluorescent protein labeling of both the plant cytoskeleton and the endoplasmic reticu ... | 2005 | 16284314 |
| sini- and expr-dependent quorum sensing in sinorhizobium meliloti. | quorum sensing (qs) in sinorhizobium meliloti, the n-fixing bacterial symbiont of medicago host plants, involves at least half a dozen different n-acyl homoserine lactone (ahl) signals and perhaps an equal number of ahl receptors. the accumulation of 55 proteins was found to be dependent on sini, the ahl synthase, and/or on expr, one of the ahl receptors. gas chromatography-mass spectrometry and electrospray ionization tandem mass spectrometry identified 3-oxo-c(14)-homoserine lactone (3-oxo-c(1 ... | 2005 | 16291666 |
| competitive abilities of rhizobium meliloti strains considered to have potential as inoculants. | twenty four strains of rhizobium meliloti considered to have potential for inoculant production were grouped in pairs and tested for their ability to compete for nodulation on medicago sativa, medicago truncatula, and medicago littoralis. at the outset, each pair of strains, which consisted of a wild type and a selected streptomycin-resistant mutant of another strain, was tested in an autoclaved soil. six strain pairs, each consisting of a good and a poor competitor, reacted consistently when te ... | 1982 | 16346072 |
| nod factors alter the microtubule cytoskeleton in medicago truncatula root hairs to allow root hair reorientation. | the microtubule (mt) cytoskeleton is an important part of the tip-growth machinery in legume root hairs. here we report the effect of nod factor (nf) on mts in root hairs of medicago truncatula. in tip-growing hairs, the ones that typically curl around rhizobia, nf caused a subtle shortening of the endoplasmic mt array, which recovered within 10 min, whereas cortical mts were not visibly affected. in growth-arresting root hairs, endoplasmic mts disappeared shortly after nf application, but refor ... | 2005 | 16353554 |
| changes in chloroplast dna during development in tobacco, medicago truncatula, pea, and maize. | we examined the dna from chloroplasts obtained from young and fully expanded leaves of tobacco (nicotiana tabacum l.), medicago truncatula, pea (pisum sativum l.), and maize (zea mays l.). the changes in plastid dna content and structure were monitored by four independent methods: 4',6-diamidino-2-phenylindole (dapi) staining with intact chloroplasts, in situ dapi staining of cytological sections, ethidium bromide staining at the single-molecule level after exhaustive deproteinization of lysed c ... | 2006 | 16362324 |
| transcript analysis of early nodulation events in medicago truncatula. | within the first 72 h of the interaction between rhizobia and their host plants, nodule primordium induction and infection occur. we predicted that transcription profiling of early stages of the symbiosis between medicago truncatula roots and sinorhizobium meliloti would identify regulated plant genes that likely condition key events in nodule initiation. therefore, using a microarray with about 6,000 cdnas, we compared transcripts from inoculated and uninoculated roots corresponding to defined ... | 2006 | 16377745 |
| an integrated physical, genetic and cytogenetic map around the sunn locus of medicago truncatula. | the sunn mutation of medicago truncatula is a single-gene mutation that confers a novel supernodulation phenotype in response to inoculation with sinorhizobium meliloti. we took advantage of the publicly available codominant pcr markers, the high-density genetic map, and a linked cytogenetic map to define the physical and genetic region containing sunn. we determined that sunn is located at the bottom of linkage group 4, where a fine-structure genetic map was used to place the locus within a app ... | 2003 | 12897874 |
| architecture of infection thread networks in developing root nodules induced by the symbiotic bacterium sinorhizobium meliloti on medicago truncatula. | during the course of the development of nitrogen-fixing root nodules induced by sinorhizobium meliloti on the model plant medicago truncatula, tubules called infection threads are cooperatively constructed to deliver the bacterial symbiont from the root surface to cells in the interior of the root and developing nodule. three-dimensional reconstructions of infection threads inside m. truncatula nodules showed that the threads formed relatively simple, tree-like networks. some characteristics of ... | 2006 | 16384905 |
| nitrogen fixation mutants of medicago truncatula fail to support plant and bacterial symbiotic gene expression. | the rhizobium-legume symbiosis culminates in the exchange of nutrients in the root nodule. bacteria within the nodule reduce molecular nitrogen for plant use and plants provide bacteria with carbon-containing compounds. following the initial signaling events that lead to plant infection, little is known about the plant requirements for establishment and maintenance of the symbiosis. we screened 44,000 m2 plants from fast neutron-irradiated medicago truncatula seeds and isolated eight independent ... | 2006 | 16407449 |
| mtenod11 gene activation during rhizobial infection and mycorrhizal arbuscule development requires a common at-rich-containing regulatory sequence. | the mtenod11 gene from the model legume medicago truncatula is transcriptionally activated both in response to sinorhizobium meliloti nod factors and throughout infection of root tissues by the nitrogen-fixing microsymbiont. to identify the regulatory sequences involved in symbiosis-related mtenod11 expression, a series of promoter deletions driving the beta-glucuronidase reporter gene were analyzed in transgenic m. truncatula roots. these studies have revealed that distinct regulatory regions a ... | 2005 | 16478046 |
| defective long-distance auxin transport regulation in the medicago truncatula super numeric nodules mutant. | long-distance auxin transport was examined in medicago truncatula and in its supernodulating mutant sunn (super numeric nodules) to investigate the regulation of auxin transport during autoregulation of nodulation (aon). a method was developed to monitor the transport of auxin from the shoot to the root in whole seedlings. subsequently, the transport was monitored after inoculation of roots with the nodulating symbiont sinorhizobium meliloti. the sunn mutant showed an increased amount of auxin t ... | 2006 | 16489131 |
| metabolic engineering of proanthocyanidins through co-expression of anthocyanidin reductase and the pap1 myb transcription factor. | proanthocyanidins (pas) and their monomeric building blocks, the (epi)-flavan-3-ols, are plant antioxidants that confer multiple human health benefits. the presence of pas in forage crops is an important agronomic trait, preventing pasture bloat in ruminant animals. however, many consumed plant materials lack pas, and there has been little success to date in introducing monomeric or polymeric flavan-3-ols de novo into plant tissues for disease prevention by dietary means or development of 'bloat ... | 2006 | 16507081 |
| activation of an alfalfa cyclin-dependent kinase inhibitor by calmodulin-like domain protein kinase. | kip-related proteins (krps) play a central role in the regulation of the cell cycle and differentiation through modulation of cyclin-dependent kinase (cdk) functions. we have identified a cdk inhibitor gene from medicago truncatula (mt) by a yeast two-hybrid screen. the krpmt gene was expressed in all plant organs and cultured cells, and its transcripts accumulated after abscisic acid and nacl treatment. the krpmt protein exhibits seven conserved sequence domains and a pest motif that is also de ... | 2006 | 16553899 |
| spatial effects and rare outcrossing events in medicago truncatula (fabaceae). | in order to elucidate the mechanisms underlying the large amount of rapd polymorphism found in 1990 in a population of the selfing annual medicago truncatula gaertn. (fabaceae), we have analysed most of the individuals (n = 363) from the same population 6 years later using microsatellite loci. we confirm the result of the earlier study, namely that this population is very polymorphic and highly subdivided, with approximately 37% of the variance distributed among subpopulations, only 50 m apart o ... | 2001 | 11412361 |
| transgenic medicago truncatula plants obtained from agrobacterium tumefaciens -transformed roots and agrobacterium rhizogenes-transformed hairy roots. | medicago truncatula, barrel medic, is a forage crop that has been developed into a model legume. the development of new transformation methods is important for functional genomic studies in this species. based on agrobacterium tumefaciens-mediated transformation of root explants, we developed an effective system for producing m. truncatula (genotype r108) transgenic plants. among the four a. tumefaciens strains (agl1, c58c1, eha105 and lba4404) tested, eha105 and agl1 were most effective in rege ... | 2006 | 16575594 |
| the conserved arbuscular mycorrhiza-specific transcription of the secretory lectin mtlec5 is mediated by a short upstream sequence containing specific protein binding sites. | in medicago truncatula a family of mycorrhiza-specific expressed lectins has been identified recently, but the function and regulation of these lectins during the arbuscular mycorrhiza symbiosis are still unknown. in order to characterize a first member of this protein family, mtlec5 was analyzed concerning its localization and regulation. confocal laser scanning microscopy showed that mtlec5 is a secretory protein indicating a role as a vegetative storage protein, which is specifically expresse ... | 2006 | 16596411 |
| cytological, genetic, and molecular analysis to characterize compatible and incompatible interactions between medicago truncatula and colletotrichum trifolii. | in this study, a new pathosystem was established using the model plant medicago truncatula and colletotrichum trifolii, the causal agent of anthracnose on medicago sativa. screening of a few m. truncatula lines identified jemalong and f83005.5 as resistant and susceptible to colletotrichum trifolii race 1, respectively. symptom analysis and cytological studies indicated that resistance of jemalong was associated with a hypersensitive response of the plant. the two selected lines were crossed, an ... | 2004 | 15305612 |
| microbial products trigger amino acid exudation from plant roots. | plants naturally cycle amino acids across root cell plasma membranes, and any net efflux is termed exudation. the dominant ecological view is that microorganisms and roots passively compete for amino acids in the soil solution, yet the innate capacity of roots to recover amino acids present in ecologically relevant concentrations is unknown. we find that, in the absence of culturable microorganisms, the influx rates of 16 amino acids (each supplied at 2.5 microm) exceed efflux rates by 5% to 545 ... | 2004 | 15347793 |
| comprehensive metabolite profiling of sinorhizobium meliloti using gas chromatography-mass spectrometry. | a metabolite analysis of the soil bacterium sinorhizobium meliloti was established as a first step towards a better understanding of the symbiosis with its host plant medicago truncatula. a crucial step was the development of fast harvesting and extraction methods for the bacterial metabolites because of rapid changes in their composition. s. meliloti 1021 cell cultures grown in minimal medium were harvested by centrifugation, filtration or immediate freezing in liquid nitrogen followed by a lyo ... | 2004 | 15372312 |
| silencing the flavonoid pathway in medicago truncatula inhibits root nodule formation and prevents auxin transport regulation by rhizobia. | legumes form symbioses with rhizobia, which initiate the development of a new plant organ, the nodule. flavonoids have long been hypothesized to regulate nodule development through their action as auxin transport inhibitors, but genetic proof has been missing. to test this hypothesis, we used rna interference to silence chalcone synthase (chs), the enzyme that catalyzes the first committed step of the flavonoid pathway, in medicago truncatula. agrobacterium rhizogenes transformation was used to ... | 2006 | 16751348 |
| effects of endogenous salicylic acid on nodulation in the model legumes lotus japonicus and medicago truncatula. | the exogenous addition of salicylic acid (sa) was previously shown to inhibit indeterminate but not determinate-type nodulation. we sought to extend these results by modulating endogenous levels of sa through the transgenic expression of salicylate hydroxylase (nahg) in both stably transformed lotus japonicus and composite medicago truncatula plants. nahg expression in l. japonicus resulted in a marked reduction of sa levels. this reduction correlated with an increase in the number of infections ... | 2006 | 16798946 |
| nodulation independent of rhizobia induced by a calcium-activated kinase lacking autoinhibition. | legumes, such as medicago truncatula, form mutualistic symbiotic relationships with nitrogen-fixing rhizobial bacteria. this occurs within specialized root organs--nodules--that provide the conditions required for nitrogen fixation. a rhizobium-derived signalling molecule, nod factor, is required to establish the symbiosis. perception of nod factor in the plant leads to the induction of ca2+ oscillations, and the transduction of this ca2+ signal requires dmi3 (refs 2, 3), which encodes the prote ... | 2006 | 16810256 |
| the medicago truncatula lysin [corrected] motif-receptor-like kinase gene family includes nfp and new nodule-expressed genes. | rhizobial nod factors are key symbiotic signals responsible for starting the nodulation process in host legume plants. of the six medicago truncatula genes controlling a nod factor signaling pathway, nod factor perception (nfp) was reported as a candidate nod factor receptor gene. here, we provide further evidence for this by showing that nfp is a lysin [corrected] motif (lysm)-receptor-like kinase (rlk). nfp was shown both to be expressed in association with infection thread development and to ... | 2006 | 16844829 |
| the ethylene-insensitive sickle mutant of medicago truncatula shows altered auxin transport regulation during nodulation. | we studied the ethylene-insensitive, hypernodulating mutant, sickle (skl), to investigate the interaction of ethylene with auxin transport during root nodulation in medicago truncatula. grafting experiments demonstrated that hypernodulation in skl is root controlled. long distance transport of auxin from shoot to root was reduced by rhizobia after 24 h in wild type but not in skl. similarly, the ethylene precursor 1-amino cyclopropane-1-carboxylic acid inhibited auxin transport in wild type but ... | 2006 | 16844840 |
| 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 ... | 2006 | 16854943 |
| 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 ... | 2006 | 16870293 |
| lin, a medicago truncatula gene required for nodule differentiation and persistence of rhizobial infections. | ethyl methanesulfonate mutagenesis of the model legume medicago truncatula has previously identified several genes required for early steps in nodulation. here, we describe a new mutant that is defective in intermediate steps of nodule differentiation. the lin (lumpy infections) mutant is characterized by a 4-fold reduction in the number of infections, all of which arrest in the root epidermis, and by nodule primordia that initiate normally but fail to mature. genetic analyses indicate that the ... | 2004 | 15516512 |
| a member of the germin-like protein family is a highly conserved mycorrhiza-specific induced gene. | a medicago truncatula cdna encoding a germin-like protein (glp) was isolated from a suppression subtractive hybridization cdna library enriched for arbuscular mycorrhiza (am)-induced genes. the mtglp1 amino acid sequence shows some striking differences to previously described plant glp sequences and might therefore represent a new subgroup of this multigene family. the mtglp1 mrna was strongly induced in roots and root cultures colonized by the am fungus glomus intraradices. whereas mtglp1 is st ... | 2003 | 14634158 |
| characterisation of new symbiotic medicago truncatula (gaertn.) mutants, and phenotypic or genotypic complementary information on previously described mutants. | from a pool of medicago truncatula mutants--obtained by gamma-irradiation or ethyl methanesulfonate mutagenesis--impaired in symbiosis with the n-fixing bacterium sinorhizobium meliloti, new mutants are described and genetically analysed, and for already reported mutants, complementary data are given on their phenotypic and genetic analysis. phenotypic data relate to nodulation and mycorrhizal phenotypes. among the five new mutants, three were classified as [nod+ fix- myc+] and the mutations wer ... | 2005 | 15558330 |
| 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 ... | 2006 | 16988338 |
| 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 ... | 2006 | 16988339 |
| 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 ... | 2006 | 16988340 |
| 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 ... | 2007 | 17019605 |
| endoreduplication mediated by the anaphase-promoting complex activator ccs52a is required for symbiotic cell differentiation in medicago truncatula nodules. | in medicago nodules, endoreduplication cycles and ploidy-dependent cell enlargement occur during the differentiation of bacteroid-containing nitrogen-fixing symbiotic cells. these events are accompanied by the expression of ccs52a, a plant ortholog of the yeast and animal cdh1/srw1/fzr genes, acting as a substrate-specific activator of the anaphase-promoting complex (apc) ubiquitin ligase. because ccs52a is involved in the transition of mitotic cycles to endoreduplication cycles, we investigated ... | 2003 | 12953113 |
| transcript profiling coupled with spatial expression analyses reveals genes involved in distinct developmental stages of an arbuscular mycorrhizal symbiosis. | the formation of symbiotic associations with arbuscular mycorrhizal (am) fungi is a phenomenon common to the majority of vascular flowering plants. here, we used cdna arrays to examine transcript profiles in medicago truncatula roots during the development of an am symbiosis with glomus versiforme and during growth under differing phosphorus nutrient regimes. three percent of the genes examined showed significant changes in transcript levels during the development of the symbiosis. most genes sh ... | 2003 | 12953114 |
| characterization of four lectin-like receptor kinases expressed in roots of medicago truncatula. structure, location, regulation of expression, and potential role in the symbiosis with sinorhizobium meliloti. | to study the role of lecrk (lectin-like receptor kinase) genes in the legumerhizobia symbiosis, we have characterized the four medicago truncatula gaernt. lecrk genes that are most highly expressed in roots. three of these genes, mtlecrk7;1, mtlecrk7;2, and mtlecrk7;3, encode proteins most closely related to the class a lecrks of arabidopsis, whereas the protein encoded by the fourth gene, mtlecrk1;1, is most similar to a class b arabidopsis lecrk. all four genes show a strongly enhanced root ex ... | 2003 | 14630957 |
| methyl jasmonate and yeast elicitor induce differential transcriptional and metabolic re-programming in cell suspension cultures of the model legume medicago truncatula. | exposure of cell suspension cultures of medicago truncatula gaerth. to methyl jasmonate (meja) resulted in up to 50-fold induction of transcripts encoding the key triterpene biosynthetic enzyme beta-amyrin synthase (betaas; ec 5.4.99.-). transcripts reached maximum levels at 24 h post-elicitation with 0.5 mm meja. the entry point enzymes into the phenylpropanoid and flavonoid pathways, l: -phenylalanine ammonia-lyase (pal; ec 4.3.1.5) and chalcone synthase (chs; ec 2.3.1.74), respectively, were ... | 2004 | 15605242 |
| lotus japonicus metabolic profiling. development of gas chromatography-mass spectrometry resources for the study of plant-microbe interactions. | symbiotic nitrogen fixation (snf) in legume root nodules requires differentiation and integration of both plant and bacterial metabolism. classical approaches of biochemistry, molecular biology, and genetics have revealed many aspects of primary metabolism in legume nodules that underpin snf. functional genomics approaches, especially transcriptomics and proteomics, are beginning to provide a more holistic picture of the metabolic potential of nodules in model legumes like medicago truncatula an ... | 2005 | 15749991 |
| the mycorrhizal fungus gigaspora margarita possesses a cuzn superoxide dismutase that is up-regulated during symbiosis with legume hosts. | a full-length cdna showing high similarity to previously described cuzn superoxide dismutases (sods) was identified in an expressed sequence tag collection from germinated spores of the arbuscular mycorrhizal fungus gigaspora margarita (beg 34). the corresponding gene sequence, named gmarcuznsod, is composed of four exons. as revealed by heterologous complementation assays in a yeast mutant, gmarcuznsod encodes a functional polypeptide able to confer increased tolerance to oxidative stress. the ... | 2005 | 15749992 |
| 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 ... | 2006 | 17132148 |
| 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 ... | 2007 | 17141285 |
| 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 ... | 2007 | 17173544 |
| invasion of lotus japonicus root hairless 1 by mesorhizobium loti involves the nodulation factor-dependent induction of root hairs. | in many legumes, including lotus japonicus and medicago truncatula, susceptible root hairs are the primary sites for the initial signal perception and physical contact between the host plant and the compatible nitrogen-fixing bacteria that leads to the initiation of root invasion and nodule organogenesis. however, diverse mechanisms of nodulation have been described in a variety of legume species that do not rely on root hairs. to clarify the significance of root hairs during the l. japonicus-me ... | 2005 | 15778455 |
| 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 ... | 2007 | 17218039 |
| 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, ... | 2007 | 17220366 |
| 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 ... | 2006 | 17227545 |
| 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 ... | 2007 | 17237187 |
| identification of a large cluster of coiled coil-nucleotide binding site--leucine rich repeat-type genes from the rps1 region containing phytophthora resistance genes in soybean. | fifteen rps genes confer resistance against the oomycete pathogen phytophthora sojae, which causes root and stem rot disease in soybean. we have isolated a disease resistance gene-like sequence from the genomic region containing rps1-k. four classes of cdna of the sequence were isolated from etiolated hypocotyl tissues that express the rps1-k-encoded phytophthora resistance. sequence analyses of a cdna clone showed that the sequence is a member of the coiled coil-nucleotide binding site-leucine ... | 2005 | 15841357 |