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 ...200314634158
molecular and cell biology of a family of voltage-dependent anion channel porins in lotus japonicus.voltage-dependent anion channels (vdacs) are generally considered as the main pathway for metabolite transport across the mitochondrial outer membrane. recent proteomic studies on isolated symbiosome membranes from legume nodules indicated that vdacs might also be involved in transport of nutrients between plants and rhizobia. in an attempt to substantiate this, we carried out a detailed molecular and cellular characterization of vdacs in lotus japonicus and soybean (glycine max). database searc ...200414657408
the promoter of the vicia faba l. leghemoglobin gene vflb29 is specifically activated in the infected cells of root nodules and in the arbuscule-containing cells of mycorrhizal roots from different legume and nonlegume plants.the vflb29 leghemoglobin gene promoter was polymerase chain reaction-amplified from a vicia faba genomic library and was fused to the gusaint coding region. expression of the chimeric gene was analyzed in transgenic hairy roots of the legumes v. faba, v. hirsuta, and medicago truncatula as well as in transgenic nicotiana tabacum plants. the vflb29 promoter was found to be specifically active not only in the infected cells of the nitrogen-fixing zone of root nodules but also in arbuscule-containi ...200414714869
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 ...200414722770
plant and bacterial symbiotic mutants define three transcriptionally distinct stages in the development of the medicago truncatula/sinorhizobium meliloti the medicago truncatula/sinorhizobium meliloti symbiosis, the plant undergoes a series of developmental changes simultaneously, creating a root nodule and allowing bacterial entry and differentiation. our studies of plant genes reveal novel transcriptional regulation during the establishment of the symbiosis and identify molecular markers that distinguish classes of plant and bacterial symbiotic mutants. we have identified three symbiotically regulated plant genes encoding a beta,1-3 endogluc ...200414739349
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 ...200414760646
a putative ca2+ and calmodulin-dependent protein kinase required for bacterial and fungal symbioses.legumes can enter into symbiotic relationships with both nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. nodulation by rhizobia results from a signal transduction pathway induced in legume roots by rhizobial nod factors. dmi3, a medicago truncatula gene that acts immediately downstream of calcium spiking in this signaling pathway and is required for both nodulation and mycorrhizal infection, has high sequence similarity to genes encoding calcium and calmodulin-dependent protein kinase ...200414963335
molecular and biochemical analysis of two cdna clones encoding dihydroflavonol-4-reductase from medicago truncatula.dihydroflavonol-4-reductase (dfr; ec1.1.1.219) catalyzes a key step late in the biosynthesis of anthocyanins, condensed tannins (proanthocyanidins), and other flavonoids important to plant survival and human nutrition. two dfr cdna clones (mtdfr1 and mtdfr2) were isolated from the model legume medicago truncatula cv jemalong. both clones were functionally expressed in escherichia coli, confirming that both encode active dfr proteins that readily reduce taxifolin (dihydroquercetin) to leucocyanid ...200414976232
the typa gene is required for stress adaptation as well as for symbiosis of sinorhizobium meliloti 1021 with certain medicago truncatula 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. ...200415000390
isolation and characterization of the early nodule-specific protein homologue (hev b 13), an allergenic lipolytic esterase from hevea brasiliensis latex.recurring reports of a highly allergenic 42-46-kda protein in hevea brasiliensis latex appeared to have been resolved with the discovery of a 43-kda allergenic latex protein that was a homologue to patatin. however, the low to moderate prevalence of sensitization to the protein, designated hev b 7, among latex-allergic patients could not adequately explain the frequent observations of the 42-46-kda allergen. this led to the hypothesis that another, more allergenic protein of a similar molecular ...200415024009
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 ...200415031407
phytohormonal responses in enod40-overexpressing plants of medicago truncatula and rice.phytohormones are well-known regulators of the symbiotic rhizobium-legume association in the plant host. the enod40 nodulin gene is associated with the earliest phases of the nodule organogenesis programme in the legume host and modifying its expression resulted in perturbations of nodule development in medicago truncatula. therefore in our pursuit to mimic the initial signal transduction steps of legume nodulation in the alien physiological set-up of a rice plant, we have expressed the mtenod40 ...200415032885
enod40, a short open reading frame-containing mrna, induces cytoplasmic localization of a nuclear rna binding protein in medicago eukaryotes, diverse mrnas containing only short open reading frames (sorf-mrnas) are induced at specific stages of development. their mechanisms of action may involve the rna itself and/or sorf-encoded oligopeptides. enod40 genes code for highly structured plant sorf-mrnas involved in root nodule organogenesis. a novel rna binding protein interacting with the enod40 rna, mtrbp1 (for medicago truncatula rna binding protein 1), was identified using a yeast three-hybrid screening. immunolocaliza ...200415037734
rna interference in agrobacterium rhizogenes-transformed roots of arabidopsis and medicago truncatula.rna interference (rnai) is a powerful reverse genetic tool to study gene function. the data presented here show that agrobacterium rhizogenes-mediated rnai is a fast and effective tool to study genes involved in root biology. the arabidopsis gene kojak, involved in root hair development, was efficiently knocked down. a. rhizogenes-mediated root transformation is a fast method to generate adventitious, genetically transformed roots. in order to select for co-transformed roots a binary vector was ...200415073217
a natural variant of a host rna-dependent rna polymerase is associated with increased susceptibility to viruses by nicotiana benthamiana.nicotiana benthamiana often displays more intense symptoms after infection by rna viruses than do other nicotiana species. here, we examined the role of rna-dependent rna polymerases (rdrps) in n. benthamiana antiviral defense. cdnas representing only two genes encoding rdrps were identified in n. benthamiana. one rdrp was similar in sequence to sde1/sgs2 required for maintenance of transgene silencing, whereas the second, named nbrdrp1m, was >90% identical in sequence to the salicylic acid (sa) ...200415079073
sinorhizobium meliloti-induced chitinase gene expression in medicago truncatula ecotype r108-1: a comparison between symbiosis-specific class v and defence-related class iv chitinases.the medicago truncatula (gaertn.) ecotypes jemalong a17 and r108-1 differ in sinorhizobium meliloti-induced chitinase gene expression. the pathogen-inducible class iv chitinase gene, mtchit 4, was strongly induced during nodule formation of the ecotype jemalong a17 with the s. meliloti wild-type strain 1021. in the ecotype r108-1, the s. meliloti wild types sm1021 and sm41 did not induce mtchit 4 expression. on the other hand, expression of the putative class v chitinase gene, mtchit 5, was foun ...200415107993
construction and validation of cdna-based mt6k-rit macro- and microarrays to explore root endosymbioses in the model legume medicago 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 ...200415129719
six nonnodulating plant mutants defective for nod factor-induced transcriptional changes associated with the legume-rhizobia the legume-rhizobia symbiosis is established, the plant recognizes bacterial-signaling molecules, nod factors (nfs), and initiates transcriptional and developmental changes within the root to allow bacterial invasion and the construction of a novel organ, the nodule. plant mutants defective in nodule initiation (nod(-)) are thought to have defects in nf-signal transduction. however, it is unknown whether wt plants respond to nf-independent bacterial-derived signals or whether nod(-) plant mut ...200415220482
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 ...200415221743
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 ...200415276460
resistance of glycine species and various cultivated legumes to the soybean aphid (homoptera: aphididae).the soybean aphid, aphis glycines matsumura, is a new pest of soybean, glycine max (l.) merr., in north america. it has become widespread on soybean in north america since it was first identified in the midwest in 2000. species of rhamnus l. (buckthorn) are the primary hosts of a. glycines, and soybean is known as a secondary host. there is limited information about the secondary host range of a. glycines. aphid colonization on various legume hosts was compared in choice experiments. aphid colon ...200415279293
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 ...200415299136
cytological, genetic, and molecular analysis to characterize compatible and incompatible interactions between medicago truncatula and colletotrichum 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 ...200415305612
production of transgenic crops by the floral-dip method.the application of floral dipping toward the production of transformed plants has been rather limited. however, this procedure has enabled the successful production of transformed medicago truncatula plants (a model plant for legume genetics) at efficiencies higher than those obtained by tissue culture methods. indeed, this simple system, without requiring any knowledge of plant tissue culture, has been a breakthrough in the production of the first transgenic radish plants. this root crop is of ...200515310916
identification and characterization of several new members of the zip family of metal ion transporters in medicago 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 ...200415316291
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 ...200415347793
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 ...200415361530
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 ...200415372312
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 ...200415466224
expression profiling in medicago truncatula identifies more than 750 genes differentially expressed during nodulation, including many potential regulators of the symbiotic 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 ...200415466239
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 ...200415489277
nip, a symbiotic medicago truncatula mutant that forms root nodules with aberrant infection threads and plant defense-like 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 ...200415516506
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 ...200415516512
a dual-genome symbiosis chip for coordinate study of signal exchange and development in a prokaryote-host interaction.the soil-dwelling alpha-proteobacterium sinorhizobium meliloti engages in a symbiosis with legumes: s. meliloti elicits the formation of plant root nodules where it converts dinitrogen to ammonia for use by the plant in exchange for plant photosynthate. to study the coordinate differentiation of s. meliloti and its legume partner during nodule development, we designed a custom affymetrix genechip with the complete s. meliloti genome and approximately 10,000 probe sets for the plant host, medicag ...200415542588
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 ...200515558330
the symbiotic defect in a sinorhizobium meliloti lipopolysaccharide mutant can be overcome by expression of other surface 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 ...200415567281
effect of salinity on root-nodule conductance to the oxygen diffusion in the medicago truncatula-sinorhizobium meliloti 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 ...200415596103
metabolic profiling of medicago truncatula cell cultures reveals the effects of biotic and abiotic elicitors on metabolism.gc-ms-based metabolite profiling was used to analyse the response of medicago truncatula cell cultures to elicitation with methyl jasmonate (meja), yeast elicitor (ye), or ultraviolet light (uv). marked changes in the levels of primary metabolites, including several amino acids, organic acids, and carbohydrates, were observed following elicitation with meja. a similar, but attenuated response was observed following ye elicitation, whereas little response was observed following uv elicitation. me ...200415596476
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 ...200415597744
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 ...200415604668
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 and chalcone synthase (chs; ec, respectively, were ...200415605242
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 ...200515716119
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 ...200515720086
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 ...200515720666
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 ...200515749991
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 ...200515749992
invasion of lotus japonicus root hairless 1 by mesorhizobium loti involves the nodulation factor-dependent induction of root 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 ...200515778455
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. ...200515782639
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 ...200515824071
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 ...200515830127
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 ...200515841357
molecular cloning and characterisation of a rab-binding gdp-dissociation inhibitor from medicago truncatula.we have isolated and sequenced the full-length cdna of a gdp-dissociation inhibitor (gdi) from the model legume medicago truncatula l. the cdna (mtgdi) contains an open reading frame of 1335 bp, coding for a protein of 444 amino acids with a calculated molecular mass of 49,785 kda. the deduced amino acid sequence shows significant homology to other plant gdis, the highest homology being found to gdi from the legume cicer arietinum (96% identity). the mtgdi was expressed as a n-terminal flag-fusi ...200515854828
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 ...200515875223
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 ...200515882655
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 ...200515955723
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 ...200515961668
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 ...200515986921
ectopic expression of the mycorrhiza-specific chitinase gene mtchit 3-3 in medicago truncatula root-organ cultures stimulates spore germination of glomalean fungi.expression of mtchit 3-3, a class iii chitinase gene, is specifically induced by arbuscular mycorrhizal (am) fungi in roots of the model legume medicago truncatula and its transcripts accumulate in cells containing arbuscules. agrobacterium rhizogenes-transformed roots and root-organ cultures of m. truncatula were used to study effects of mtchit 3-3 on am fungi. * this work provides evidence for enzymatic activity of the mtchit 3-3 gene product and shows with promoter:gus fusions that a 2 kb fra ...200515998406
formation of organelle-like n2-fixing symbiosomes in legume root nodules is controlled by 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 ...200516006515
metabolic engineering of isoflavonoid biosynthesis in alfalfa.the potential health benefits of dietary isoflavones have generated considerable interest in engineering the synthesis of these phytoestrogens into plants. genistein glucoside production (up to 50 nmol g(-1) fresh weight) was engineered in alfalfa (medicago sativa) leaves by constitutive expression of isoflavone synthase from medicago truncatula (mtifs1). glucosides of biochanin a (4'-o-methylgenistein) and pratensein (3'-hydroxybiochanin a) also accumulated. although mtifs1 was highly expressed ...200516006598
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 ...200516010004
defensin gene family in medicago truncatula: structure, expression and induction by signal molecules.a large gene family encoding the putative cysteine-rich defensins was discovered in medicago truncatula. sixteen members of the family were identified by screening a cloned seed defensin from m. sativa (gao et al. 2000) against the institute for genomic research's (tigr) m. truncatula gene index (mtgi version 7). based on the comparison of their amino acid sequences, m. truncatula defensins fell arbitrarily into three classes displaying extensive sequence divergence outside of the eight canonica ...200516021402
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 ...200516025342
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 ...200516026877
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 ...200516042020
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 ...200516043451
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 ...200516101908
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 ...200516126866
expression of the medicago truncatula dm12 gene suggests roles of the symbiotic nodulation receptor kinase in nodules and during early nodule development.the medicago truncatula dmi2 gene encodes a receptorlike kinase required for establishing root endosymbioses. the dmi2 gene was shown to be expressed much more highly in roots and nodules than in leaves and stems. in roots, its expression was not altered by nitrogen starvation or treatment with lipochitooligosaccharidic nod factors. moreover, the dmi2 mrna abundance in roots of the nfp, dmil, dmi3, nsp1, nsp2, and hcl symbiotic mutants was similar to the wild type, whereas lower levels in some d ...200516134899
phosphorylation and subsequent interaction with 14-3-3 proteins regulate plastid glutamine synthetase in medicago 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 ...200616136328
pseudomonas fluorescens and glomus mosseae trigger dmi3-dependent activation of genes related to a signal transduction pathway in roots of medicago truncatula.plant genes induced during early root colonization of medicago truncatula gaertn. j5 by a growth-promoting strain of pseudomonas fluorescens (c7r12) have been identified by suppressive subtractive hybridization. ten m. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between m. truncatula and p. fluorescens, up to 8 d after root inoculation. gene expression was not significantly enhanced ...200516183836
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 ...200516212600
crystal structures of a multifunctional triterpene/flavonoid glycosyltransferase from medicago truncatula.glycosylation is a ubiquitous reaction controlling the bioactivity and storage of plant natural products. glycosylation of small molecules is catalyzed by a superfamily of glycosyltransferases (gts) in most plant species studied to date. we present crystal structures of the udp flavonoid/triterpene gt ugt71g1 from medicago truncatula bound to udp or udp-glucose. the structures reveal the key residues involved in the recognition of donor substrate and, by comparison with other gt structures, sugg ...200516214900
proteomic profiling unravels insights into the molecular background underlying increased aphanomyces euteiches-tolerance of medicago 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 ...200516235107
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 ...200516244141
methylotrophic metabolism is advantageous for methylobacterium extorquens during colonization of medicago truncatula under competitive conditions.facultative methylotrophic bacteria of the genus methylobacterium are commonly found in association with plants. inoculation experiments were performed to study the importance of methylotrophic metabolism for colonization of the model legume medicago truncatula. competition experiments with methylobacterium extorquens wild-type strain am1 and methylotrophy mutants revealed that the ability to use methanol as a carbon and energy source provides a selective advantage during colonization of m. trun ...200516269765
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 ...200516284314
sini- and expr-dependent quorum sensing in sinorhizobium meliloti.quorum sensing (qs) in sinorhizobium meliloti, the n-fixing bacterial symbiont of medicago host plants, involves at least half a dozen different n-acyl homoserine lactone (ahl) signals and perhaps an equal number of ahl receptors. the accumulation of 55 proteins was found to be dependent on sini, the ahl synthase, and/or on expr, one of the ahl receptors. gas chromatography-mass spectrometry and electrospray ionization tandem mass spectrometry identified 3-oxo-c(14)-homoserine lactone (3-oxo-c(1 ...200516291666
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 ...198216346072
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 ...200516353554
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 ...200616362324
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 ...200616377745
the dmi1 and dmi2 early symbiotic genes of medicago truncatula are required for a high-affinity nodulation factor-binding site associated to a particulate fraction of roots.the establishment of the legume-rhizobia symbiosis between medicago spp. and sinorhizobium meliloti is dependent on the production of sulfated lipo-chitooligosaccharidic nodulation (nod) factors by the bacterial partner. in this article, using a biochemical approach to characterize putative nod factor receptors in the plant host, we describe a high-affinity binding site (kd = 0.45 nm) for the major nod factor produced by s. meliloti. this site is termed nod factor-binding site 3 (nfbs3). nfbs3 i ...200616377749
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 ...200616384905
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 ...200616407449
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 ...200516478046
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 ...200616489131
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 ...200616507081
activation of an alfalfa cyclin-dependent kinase inhibitor by calmodulin-like domain protein kinase.kip-related proteins (krps) play a central role in the regulation of the cell cycle and differentiation through modulation of cyclin-dependent kinase (cdk) functions. we have identified a cdk inhibitor gene from medicago truncatula (mt) by a yeast two-hybrid screen. the krpmt gene was expressed in all plant organs and cultured cells, and its transcripts accumulated after abscisic acid and nacl treatment. the krpmt protein exhibits seven conserved sequence domains and a pest motif that is also de ...200616553899
insights into symbiotic nitrogen fixation in medicago silico analysis of the medicago truncatula gene index release 8.0 at the institute for genomic research identified approximately 530 tentative consensus sequences (tc) clustered from 2,700 expressed sequence tags (est) derived solely from sinorhizobium meliloti-inoculated root and nodule tissues. a great majority (76%) of these tc were derived exclusively from nitrogen-fixing and senescent nodules. a cdna filter array was constructed using approximately 58% of the in silico-identified tc as w ...200616570662
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 ...200616575594
the conserved arbuscular mycorrhiza-specific transcription of the secretory lectin mtlec5 is mediated by a short upstream sequence containing specific protein binding 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 ...200616596411
plant fatty acid (ethanol) amide hydrolases.fatty acid amide hydrolase (faah) plays a central role in modulating endogenous n-acylethanolamine (nae) levels in vertebrates, and, in part, constitutes an "endocannabinoid" signaling pathway that regulates diverse physiological and behavioral processes in animals. recently, an arabidopsis faah homologue was identified which catalyzed the hydrolysis of naes in vitro suggesting a faah-mediated pathway exists in plants for the metabolism of endogenous naes. here, we provide evidence to support th ...200616624618
a rice calcium- and calmodulin-dependent protein kinase restores nodulation to a legume mutant.the medicago truncatula dmi3 gene encodes a calcium- and calmodulin-dependent protein kinase (ccamk) that is necessary for the establishment of both rhizobial and mycorrhizal symbioses. the two symbiotic signaling pathways diverge downstream of dmi3; therefore, it has been proposed that legumes have evolved a particular form of ccamk, acting like a switch able both to discriminate between rhizobial and mycorrhizal calcium signatures and to trigger the appropriate downstream signaling pathway. to ...200616673936
lysm domains of medicago truncatula nfp protein involved in nod factor perception. glycosylation state, molecular modeling and docking of chitooligosaccharides and nod factors.the establishment of the symbiosis between legume plants and rhizobial bacteria depends on the production of rhizobial lipo-chitooligosaccharidic signals (the nod factors) that are specifically recognized by roots of the host plant. in medicago truncatula, specific recognition of sinorhizobium meliloti and its nod factors requires the nfp (nod factor perception) gene, which encodes a putative serine/threonine receptor-like kinase (rlk). the extracellular region of this protein contains three tan ...200616723404
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 ...200616751348
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 ...200616798946
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 ...200616810256
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 ...200616844829
the ethylene-insensitive sickle mutant of medicago truncatula shows altered auxin transport regulation during nodulation.we studied the ethylene-insensitive, hypernodulating mutant, sickle (skl), to investigate the interaction of ethylene with auxin transport during root nodulation in medicago truncatula. grafting experiments demonstrated that hypernodulation in skl is root controlled. long distance transport of auxin from shoot to root was reduced by rhizobia after 24 h in wild type but not in skl. similarly, the ethylene precursor 1-amino cyclopropane-1-carboxylic acid inhibited auxin transport in wild type but ...200616844840
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