| the rpm1 plant disease resistance gene facilitates a rapid and sustained increase in cytosolic calcium that is necessary for the oxidative burst and hypersensitive cell death. | early events occurring during the hypersensitive resistance response (hr) were examined using the avrrpm1/rpm1 gene-for-gene interaction in arabidopsis challenged by pseudomonas syringae pv. tomato. increases in cytosolic ca2+ were measured in whole leaves using aequorin-mediated bioluminescence. during the hr a sustained increase in ca2+ was observed which was dependent on the presence of both a functional rpm1 gene product and delivery of the cognate avirulence gene product avrrpm1. the sequen ... | 2000 | 10972870 |
| a loss of resistance to avirulent bacterial pathogens in tobacco is associated with the attenuation of a salicylic acid-potentiated oxidative burst. | the role of salicylic acid (sa) in events occurring before cell death during the hypersensitive reaction (hr) was investigated in leaves of wild-type tobacco samsun nn and in transgenic lines expressing salicylate hydroxylase (35s-sh-l). challenge of 35s-sh-l tobacco with avirulent strains of pseudomonas syringae gave rise to symptoms resembling those normally associated with a compatible response to virulent strains in terms of visible phenotype, kinetics of bacterial multiplication, and escape ... | 2000 | 10972887 |
| bacteria in the leaf ecosystem with emphasis on pseudomonas syringae-a pathogen, ice nucleus, and epiphyte. | the extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. this review focuses on the bacterial component of leaf microbial communities, with emphasis on pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. among the diversity of bacteria that colonize leaves, none has received wider attention than p. syringae, as it gained notoriety for being the firs ... | 2000 | 10974129 |
| interactions of pseudomonas syringae pv. glycinea with host and nonhost plants in relation to temperature and phytotoxin synthesis. | pseudomonas syringae pv. glycinea pg4180 causes bacterial blight of soybean and produces the phytotoxin coronatine (cor) in a temperature-dependent manner. cor consists of a polyketide, coronafacic acid (cfa), and an amino acid derivative, coronamic acid, and is produced optimally at 18 degrees c whereas no detectable synthesis occurs at 28 degrees c. we investigated the impact of temperature on pg4180 during compatible and incompatible interactions with soybean and tobacco plants, respectively. ... | 2000 | 10975652 |
| uncoupling salicylic acid-dependent cell death and defense-related responses from disease resistance in the arabidopsis mutant acd5. | salicylic acid (sa) is required for resistance to many diseases in higher plants. sa-dependent cell death and defense-related responses have been correlated with disease resistance. the accelerated cell death 5 mutant of arabidopsis provides additional genetic evidence that sa regulates cell death and defense-related responses. however, in acd5, these events are uncoupled from disease resistance. acd5 plants are more susceptible to pseudomonas syringae early in development and show spontaneous s ... | 2000 | 10978297 |
| variation and phylogenetic utility of the arabidopsis thaliana rps2 homolog in various species of the tribe brassiceae. | our objective was to analyze the evolutionary paths of cultivated diploid brassica species and a few related wild species (tribe brassiceae) in relation to arabidopsis thaliana (tribe arabidae), using the rps2 sequence. rps2 confers resistance to pseudomonas syringae in a. thaliana. we found that similar to arabidopsis, the rps2 homolog in brassica species is present in a single copy. primers based in the rps2 sequence amplified rps2 homologs from the other species. maximum-parsimony analysis ba ... | 2000 | 10991796 |
| in vitro antimicrobial properties of recombinant asabf, an antimicrobial peptide isolated from the nematode ascaris suum. | asabf is a csalphabeta-type antimicrobial peptide that contains four intramolecular disulfide bridges (y. kato and s. komatsu, j. biol. chem. 271:30493-30498, 1996). in the present study, a recombinant asabf was produced by using a yeast expression system, and its antimicrobial activity was characterized in detail. the recombinant asabf was active against all gram-positive bacteria tested (7 of 7; minimum bactericidal concentration [mbc], 0.03 to 1 microg/ml) except leuconostoc mesenteroides, so ... | 2000 | 10991847 |
| characterization of rci-1, a chloroplastic rice lipoxygenase whose synthesis is induced by chemical plant resistance activators. | a full-length lipoxygenase cdna (rci-1) has been cloned from rice (oryza sativa) whose corresponding transcripts accumulate in response to treatment of the plants with chemical inducers of acquired resistance such as benzo(1,2,3)thiadiazole-7-carbothioic acid s-methyl ester (bth), 2,6-dichloroisonicotinic acid (ina), and probenazole. in contrast, rci-1 transcript levels did not increase after inoculation with compatible and incompatible races of the rice blast fungus magnaporthe grisea and the n ... | 2000 | 10998053 |
| leafy gall formation is controlled by fasr, an arac-type regulatory gene in rhodococcus fascians. | rhodococcus fascians can interact with many plant species and induce the formation of either leafy galls or fasciations. to provoke symptoms, r. fascians strain d188 requires pathogenicity genes that are located on a linear plasmid, pfid188. the fas genes are essential for virulence and constitute an operon that encodes, among other functions, a cytokinin synthase gene. expression of the fas genes is induced by extracts of infected plant tissue only. we have isolated an arac-type regulatory gene ... | 2000 | 11004184 |
| identification of a copper-responsive two-component system on the chromosome of escherichia coli k-12. | using a genetic screen we have identified two chromosomal genes, cusrs (ylca ybcz), from escherichia coli k-12 that encode a two-component, signal transduction system that is responsive to copper ions. this regulatory system is required for copper-induced expression of pcoe, a plasmid-borne gene from the e. coli copper resistance operon pco. the closest homologs of cusr and cuss are plasmid-borne two-component systems that are also involved in metal responsive gene regulation: pcor and pcos from ... | 2000 | 11004187 |
| genetic manipulation of isoflavone 7-o-methyltransferase enhances biosynthesis of 4'-o-methylated isoflavonoid phytoalexins and disease resistance in alfalfa. | 4'-o-methylation of an isoflavonoid intermediate is a key reaction in the biosynthesis of the phytoalexin medicarpin in legumes. however, isoflavone o-methyltransferase (iomt) from alfalfa converts the isoflavone daidzein to 7-o-methyl daidzein (isoformononetin) in vitro as well as in vivo in unchallenged leaves of transgenic alfalfa ectopically expressing iomt. in contrast, elicitation of iomt-overexpressing plants with cucl(2) or infecting these plants with phoma medicaginis leads to greater a ... | 2000 | 11006341 |
| development of genetic tools for lactobacillus sakei: disruption of the beta-galactosidase gene and use of lacz as a reporter gene to study regulation of the putative copper atpase, atkb. | downstream from the ptshi operon of lactobacillus sakei, the genes atky and atkb, organized in an operon, were observed. the two putative proteins, atkb and atky, show sequence similarity to the enterococcus hirae copper p-type atpase, responsible for copper efflux, and its negative regulator. characterization of atkb as a copper p-type atpase could not be demonstrated since an atkb mutant did not show any phenotype. thus, another strategy was followed in order to investigate the transcriptional ... | 2000 | 11010870 |
| vesicle-mediated transfer of virulence genes from escherichia coli o157:h7 to other enteric bacteria. | membrane vesicles are released from the surfaces of many gram-negative bacteria during growth. vesicles consist of proteins, lipopolysaccharide, phospholipids, rna, and dna. results of the present study demonstrate that membrane vesicles isolated from the food-borne pathogen escherichia coli o157:h7 facilitate the transfer of genes, which are then expressed by recipient salmonella enterica serovar enteritidis or e. coli jm109. electron micrographs of purified dna from e. coli o157:h7 vesicles sh ... | 2000 | 11010892 |
| pcr assays that identify the grapevine dieback fungus eutypa lata. | eutypa lata is the causal fungal agent of eutypa dieback, a serious grapevine necrotic disease. the erratic and delayed (1 to 2 months) appearance of characteristic conidia on culture media and the presence of numerous microorganisms in decaying wood make it difficult either to identify or to detect e. lata in grapevine wood samples. we designed six pairs of pcr primers for diagnosis of e. lata. three primer pairs were derived from ribosomal dna internal transcribed spacer sequences, and three p ... | 2000 | 11010901 |
| colonization strategies and conjugal gene transfer of inoculated pseudomonas syringae on the leaf surface. | survival, colonization and activity of pseudomonas syringae bacteria inoculated onto the leaf surface of the common bean (phaseolus vulgaris) was studied. inoculated ps. syringae cells shortened by half their size in 100% humidity and by an average of one fifth in 40-60% humidity. the respiring portion of the population, measured by the formation of 5-cyano-2,3-ditolyl tetrazolium chloride (ctc)-formazan crystals, decreased more in 40-60% humidity than in 100% humidity. in scanning electron micr ... | 2000 | 11021574 |
| phylogeny of the replication regions of ppt23a-like plasmids from pseudomonas syringae. | it was previously shown that most pseudomonas syringae strains contain one or more plasmids with cross-hybridizing replication regions and other areas of homology, and these plasmids were designated the ppt23a-like family. the majority of these plasmids encode genes conferring epiphytic fitness or resistance to antibacterial compounds and those investigated in this study are essential for pathogenicity or increased virulence. the phylogeny of 14 ppt23a-like plasmids from five p. syringae pathova ... | 2000 | 11021914 |
| heterogeneity of iron bioavailability on plants assessed with a whole-cell gfp-based bacterial biosensor. | ferric iron is an essential element for microbial growth but its water solubility in aerobic environments is considered to be low. thus it is a limiting resource for which microbes must compete in natural habitats. since competition for iron occurs at the level of individual cells, knowledge of the variability in iron bioavailability to such individuals is required to assess the nature of the competition in these habitats. ferric iron availability to cells of pseudomonas syringae was assessed by ... | 2000 | 11021920 |
| regulatory interactions between the hrp type iii protein secretion system and coronatine biosynthesis in pseudomonas syringae pv. tomato dc3000. | in p. syringae, the co-ordinated regulation of different systems required for pathogenicity and virulence seems logical but has not been established. this question was addressed in the present study by analysing production of the phytotoxin coronatine (cor) in defined hrp/hrc mutants of p. syringae pv. tomato dc3000. cor was produced in vitro by mutants of dc3000 defective in hrcc, which encodes an outer-membrane protein required for type iii-mediated secretion. when inoculated in plants, hrcc m ... | 2000 | 11021921 |
| temperature-responsive genetic loci in the plant pathogen pseudomonas syringae pv. glycinea. | plant-pathogenic bacteria may sense variations in environmental factors, such as temperature, to adapt to plant-associated habitats during pathogenesis or epiphytic growth. the bacterial blight pathogen of soybean, pseudomonas syringae pv. glycinea pg4180, preferentially produces the phytotoxin coronatine at 18 degrees c and infects the host plant under conditions of low temperature and high humidity. a minitn5-based promoterless glucuronidase (uida) reporter gene was used to identify genetic lo ... | 2000 | 11021922 |
| identification of genes associated with copper tolerance in an adhesion-defective mutant of aeromonas veronii biovar sobria. | tnphoa mutagenesis was used to identify adhesins of aeromonas veronii biovar sobria 3767, a strain isolated from a diarrhoeal stool specimen. six mutants, from a library of 154, exhibited significantly reduced levels of adhesion to hep-2 cells. primers to the terminal regions of tnphoa were used for inverse pcr and the product from one mutant was cloned into pbluescript and partial sequence data obtained. scanning genbank and embl data bases revealed dna sequence similarity to the copa gene of p ... | 2000 | 11024350 |
| hydrogen peroxide yields during the incompatible interaction of tobacco suspension cells inoculated with phytophthora nicotianae. | rates of h(2)o(2) production by tobacco suspension cells inoculated with zoospores from compatible or incompatible races of the pathogen phytophthora nicotianae were followed by direct measurement of oxygen evolution from culture supernatants following catalase addition. rates of ho(2)(*)/o(2)(-) production were compared by following the formation of the formazan of sodium, 3'-[1-[phenylamino-carbonyl]-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate. in the incompatible int ... | 2000 | 11027737 |
| regulation of the rulab mutagenic dna repair operon of pseudomonas syringae by uv-b (290 to 320 nanometers) radiation and analysis of rulab-mediated mutability in vitro and in planta. | the effects of the rulab operon of pseudomonas syringae on mutagenic dna repair and the transcriptional regulation of rulab following irradiation with uv-b wavelengths were determined. for a rulb::km insertional mutant constructed in p. syringae pv. syringae b86-17, sensitivity to uv-b irradiation increased and uv mutability decreased by 12- to 14-fold. rulab-induced uv mutability was also tracked in phyllosphere populations of b86-17 for up to 5 days following plant inoculation. uv mutability t ... | 2000 | 11029435 |
| pseudobactin biogenesis in the plant growth-promoting rhizobacterium pseudomonas strain b10: identification and functional analysis of the l-ornithine n(5)-oxygenase (psba) gene. | pseudobactin(b10), the fluorescent siderophore produced by the rhizobacterium pseudomonas strain b10, contains the hydroxamate ligand d-n(5)-hydroxyornithine (d-n(5)-oh-orn). we cloned the l-orn n(5)-oxygenase (psba) gene from a genomic library of pseudomonas strain b10 and demonstrated that psba is involved in the conversion of l-orn to its n(5)-oh derivative. psba shows significant similarity to microbial omega-amino acid hydroxylases containing flavin adenine dinucleotide and nadp cofactor-bi ... | 2000 | 11029447 |
| characterization of alginate lyase from pseudomonas syringae pv. syringae. | the gene encoding alginate lyase (algl) in pseudomonas syringae pv. syringae was cloned, sequenced, and overexpressed in escherichia coli. alginate lyase activity was optimal when the ph was 7.0 and when assays were conducted at 42 degrees c in the presence of 0.2 m nacl. in substrate specificity studies, algl from p. syringae showed a preference for deacetylated polymannuronic acid. sequence alignment with other alginate lyases revealed conserved regions within algl likely to be important for t ... | 2000 | 11029455 |
| active oxygen species as mediators of plant immunity: three case studies. | a burst of active oxygen species (aos) is known to be involved in local cell death as part of plant defence against pathogens. it is, however, under dispute to what extent aos can induce pathogen resistance and immunity throughout the plant. three experimental strategies that reveal a primary role for aos and a surprisingly low chemical and spatial specificity are now described for tobacco and arabidopsis thaliana plants. ozone is a gaseous aos that was applied to non-transgenic plants. hydrogen ... | 2000 | 11030422 |
| cloning and characterization of smedef, a novel multidrug efflux pump from stenotrophomonas maltophilia. | stenotrophomonas maltophilia is a nosocomial bacterial pathogen intrinsically resistant to several antibiotics. the mechanisms involved in this intrinsic multiresistance phenotype are poorly understood. a library of chromosomal dna from a spontaneous multidrug-resistant s. maltophilia d457r mutant (a. alonso and j. l. martinez, antimicrob. agents chemother. 41:1140-1142, 1997) was screened for complementation of erythromycin susceptibility on an antibiotic-hypersusceptible escherichia coli delta ... | 2000 | 11036026 |
| the pto kinase mediates a signaling pathway leading to the oxidative burst in tomato. | the pto gene encodes a serine/threonine kinase that confers resistance in tomato to pseudomonas syringae pv. tomato strains that express the avirulence gene avrpto. partial characterization of the pto signal transduction pathway and the availability of transgenic tomato lines (+/- pto) make this an ideal system for exploring the molecular basis of disease resistance. in this paper, we test two transgenic tomato cell suspension cultures (+/-pto) for production of h2o2 following independent challe ... | 1996 | 11038525 |
| arabidopsis thaliana defense-related protein eli3 is an aromatic alcohol:nadp+ oxidoreductase. | we expressed a cdna encoding the arabidopsis thaliana defense-related protein eli3-2 in escherichia coli to determine its biochemical function. based on a protein database search, this protein was recently predicted to be a mannitol dehydrogenase [williamson, j. d., stoop, j. m. h., massel, m. o., conkling, m. a. & pharr, d. m. (1995) proc. natl. acad. sci. usa 92, 7148-7152]. studies on the substrate specificity now revealed that eli3-2 is an aromatic alcohol: nadp+ oxidoreductase (benzyl alcoh ... | 1996 | 11038530 |
| simulation of fungal-mediated cell death by fumonisin b1 and selection of fumonisin b1-resistant (fbr) arabidopsis mutants. | fumonisin b1 (fb1), a programmed cell death-eliciting toxin produced by the necrotrophic fungal plant pathogen fusarium moniliforme, was used to simulate pathogen infection in arabidopsis. plants infiltrated with 10 microm fb1 and seedlings transferred to agar media containing 1 microm fb1 develop lesions reminiscent of the hypersensitive response, including generation of reactive oxygen intermediates, deposition of phenolic compounds and callose, accumulation of phytoalexin, and expression of p ... | 2000 | 11041878 |
| hrt gene function requires interaction between a nac protein and viral capsid protein to confer resistance to turnip crinkle virus. | an arabidopsis protein was found to interact specifically with the capsid protein (cp) of turnip crinkle virus (tcv) through yeast two-hybrid screening. this protein, designated tip (for tcv-interacting protein), was found to be a member of the recently recognized nac family of proteins. nac proteins have been implicated in the regulation of development of plant embryos and flowers. tip alone was able to activate expression of reporter genes in yeast if fused to a dna binding domain, suggesting ... | 2000 | 11041886 |
| molecular analysis of thermoregulation of phaseolotoxin-resistant ornithine carbamoyltransferase (argk) from pseudomonas syringae pv. phaseolicola. | the phaseolotoxin-resistant ornithine carbamoyltransferase (roct) and phaseolotoxin are produced by pseudomonas syringae pv. phaseolicola at 18 degrees c but not at 28 degrees c. at 28 degrees c, the pathogen produces a protein(s) that binds (in vitro) to a 485-bp fragment (thermoregulatory region, trr) from a heterologous clone from the pathogen genomic library, which in multiple copies overrides thermoregulation of phaseolotoxin production in wild-type cells (k. b. rowley, d. e. clements, m. m ... | 2000 | 11043468 |
| cdna cloning and characterization of a plant protein that may be associated with the harpinpss-mediated hypersensitive response. | hypersensitive response-assisting protein (hrap) is a novel plant protein that can intensify the harpinpss-mediated hypersensitive response (hr) in harpinpss-insensitive plants, such as the vegetative stage of sweet pepper. in this report, we identified a hrap cdna clone from sweet pepper (capsicum annuum cv. ecw). the sequence of this cdna clone showed no appreciable similarity to any other known sequences. however, it contained three positively charged regions, a typical signal peptide and a c ... | 2000 | 11052195 |
| escherichia coli tehb requires s-adenosylmethionine as a cofactor to mediate tellurite resistance. | the escherichia coli chromosomal determinant for tellurite resistance consists of two genes (teha and tehb) which, when expressed on a multicopy plasmid, confer resistance to k(2)teo(3) at 128 microg/ml, compared to the mic of 2 microg/ml for the wild type. tehb is a cytoplasmic protein which possesses three conserved motifs (i, ii, and iii) found in s-adenosyl-l-methionine (sam)-dependent non-nucleic acid methyltransferases. replacement of the conserved aspartate residue in motif i by asparagin ... | 2000 | 11053398 |
| potentiation of pathogen-specific defense mechanisms in arabidopsis by beta -aminobutyric acid. | the nonprotein amino acids gamma-aminobutyric acid (gaba) and beta-aminobutyric acid (baba) have known biological effects in animals and plants. their mode of action has been the object of thorough research in animals but remains unclear in plants. our objective was to study the mode of action of baba in the protection of arabidopis plants against virulent pathogens. baba protected arabidopsis against the oomycete pathogen peronospora parasitica through activation of natural defense mechanisms o ... | 2000 | 11058166 |
| regulation of hrp genes and type iii protein secretion in erwinia amylovora by hrpx/hrpy, a novel two-component system, and hrps. | two novel regulatory components, hrpx and hrpy, of the hrp system of erwinia amylovora were identified. the hrpxy operon is expressed in rich media, but its transcription is increased threefold by low ph, nutrient, and temperature levels--conditions that mimic the plant apoplast. hrpxy is autoregulated and directs the expression of hrpl; hrpl, in turn, activates transcription of other loci in the hrp gene cluster (z.-m. wei and s. v. beer, j. bacteriol. 177:6201-6210, 1995). the deduced amino -a ... | 2000 | 11059492 |
| transposon insertion in the ftsk gene impairs in planta growth and lesion-forming abilities in pseudomonas syringae pv. syringae b728a. | a tn5 insertion in the ftsk gene of pseudomonas syringae pv. syringae b728a impaired brown spot lesion formation on phaseolus vulgaris, the ability to grow within bean leaves, and swarming ability on semisolid agar. plasmids containing the ftsk gene were sufficient to complement the original tn5 mutant for lesion formation and swarming and partially restored in planta growth. | 2000 | 11059493 |
| evaluation of fluorescence-based amplified fragment length polymorphism analysis for molecular typing in hospital epidemiology: comparison with pulsed-field gel electrophoresis for typing strains of vancomycin-resistant enterococcus faecium. | fluorescence-based amplified fragment length polymorphism (fbaflp) is a novel assay based on the fluorescent analysis of an amplified subset of restriction fragments. the fbaflp assay involves the selective pcr amplification of restriction fragments from a total digest of genomic dna. the ligation of adapters with primer-specific sites coupled with primers containing selective nucleotides allowed the full potential of pcr to be realized while maintaining the advantages of restriction endonucleas ... | 2000 | 11060068 |
| excision from trna genes of a large chromosomal region, carrying avrpphb, associated with race change in the bean pathogen, pseudomonas syringae pv. phaseolicola. | pseudomonas syringae pv. phaseolicola (pph) race 4 strain 1302a carries avirulence gene avrpphb. strain rj3, a sectoral variant from a 1302a culture, exhibited an extended host range in cultivars of bean and soybean resulting from the absence of avrpphb from the rj3 chromosome. complementation of rj3 with avrpphb restored the race 4 phenotype. both strains showed similar in planta growth in susceptible bean cultivars. analysis of rj3 indicated loss of > 40 kb of dna surrounding avrpphb. collinea ... | 2000 | 11069647 |
| three unique mutants of arabidopsis identify eds loci required for limiting growth of a biotrophic fungal pathogen. | to identify components of the defense response that limit growth of a biotrophic fungal pathogen, we isolated arabidopsis mutants with enhanced disease susceptibility to erysiphe orontii. our initial characterization focused on three mutants, eds14, eds15, and eds16. none of these is considerably more susceptible to a virulent strain of the bacterial pathogen pseudomonas syringae pv. maculicola (psm). all three mutants develop a hypersensitive response when infiltrated with psm expressing the av ... | 2000 | 11069695 |
| role of azotobacter vinelandii muca and mucc gene products in alginate production. | azotobacter vinelandii produces the exopolysaccharide alginate, which is essential for its differentiation to desiccation-resistant cysts. in different bacterial species, the alternative sigma factor sigma(e) regulates the expression of functions related to the extracytoplasmic compartments. in a. vinelandii and pseudomonas aeruginosa, the sigma(e) factor (algu) is essential for alginate production. in both bacteria, the activity of this sigma factor is regulated by the product of the muca, mucb ... | 2000 | 11073894 |
| multicomponent transcriptional regulation at the complex promoter of the exopolysaccharide i biosynthetic operon of ralstonia solanacearum. | high-level transcription of eps, an operon encoding biosynthesis of an exopolysaccharide virulence factor of the phytopathogen ralstonia (pseudomonas) solanacearum, requires the products of at least seven regulatory genes (phca, phcb, xpsr, vsra-vsrd, and vsrb-vsrc), which are organized in three converging signal transduction cascades. because xpsr and the vsrb-vsrc two-component system are the most downstream cascade components required for activation of eps, we explored how these components co ... | 2000 | 11073909 |
| catalase-peroxidases of legionella pneumophila: cloning of the kata gene and studies of kata function. | legionella pneumophila, the causative organism of legionnaires' pneumonia, contains two enzymes with catalatic and peroxidatic activity, kata and katb. to address the issue of redundant, overlapping, or discrete in vivo functions of highly homologous catalase-peroxidases, the gene for kata was cloned and its function was studied in l. pneumophila and escherichia coli and compared with prior studies of katb in this laboratory. kata is induced during exponential growth and is the predominant perox ... | 2000 | 11073912 |
| molecular signals required for type iii secretion and translocation of the xanthomonas campestris avrbs2 protein to pepper plants. | strains of xanthomonas campestris pv. vesicatoria (xcv) carrying avrbs2 are specifically recognized by bs2 pepper plants, resulting in localized cell death and plant resistance. agrobacterium-mediated transient expression of the xcv avrbs2 gene in plant cells results in bs2-dependent cell death, indicating that the avrbs2 protein alone is sufficient for the activation of disease resistance-mediated cell death in planta. we now provide evidence that avrbs2 is secreted from xcv and that secretion ... | 2000 | 11078519 |
| local and systemic induction of two defense-related subtilisin-like protease promoters in transgenic arabidopsis plants. luciferin induction of pr gene expression. | following a pathogenic attack, plants are able to mount a defense response with the coordinated activation of a battery of defense-related genes. in this study we have characterized the mode of expression of the p69b and p69c genes from tomato (lycopersicon esculentum mill.), which encodes two closely related subtilisin-like proteases associated with the defense response. we have compared the mode of gene regulation in heterologous transgenic arabidopsis plants harboring promoter-beta-glucuronid ... | 2000 | 11080282 |
| a leaf lipoxygenase of potato induced specifically by pathogen infection. | lipoxygenase (lox) activity has been identified consistently during pathogen-induced defense responses. here we report the involvement of a specific leaf lox gene of potato (solanum tuberosum), designated potlx-3 (genbank/embl accession no. u60202), in defense responses against pathogens. the sequence of potlx-3 does not match any other lox genes of potato and has the greatest match to a tobacco lox gene that contributes to a resistance mechanism against phytophthora parasitica var nicotianae. p ... | 2000 | 11080289 |
| identification and characterization of yersinia enterocolitica genes induced during systemic infection. | yersinia enterocolitica is one of three pathogenic yersinia species that share a tropism for lymphoid tissues. however, infection of an immunocompromised host is likely to result in a systemic infection, which is often fatal. little is known about the bacterial proteins needed to establish such an infection. the genes that encode these virulence factors are likely to be active only during systemic infection. a library of random cat fusions was used to inoculate balb/c mice. fusions expressed dur ... | 2000 | 11083775 |
| a telomeric avirulence gene determines efficacy for the rice blast resistance gene pi-ta. | genetic mapping showed that the rice blast avirulence gene avr-pita is tightly linked to a telomere on chromosome 3 in the plant pathogenic fungus magnaporthe grisea. avr-pita corresponds in gene-for-gene fashion to the disease resistance (r) gene pi-ta. analysis of spontaneous avr-pita(-) mutants indicated that the gene is located in a telomeric 6.5-kb bglii restriction fragment. cloning and dna sequencing led to the identification of a candidate gene with features typical of metalloproteases. ... | 2000 | 11090206 |
| arabidopsis dth9 mutation identifies a gene involved in regulating disease susceptibility without affecting salicylic acid-dependent responses. | to determine which components of the plant defense response make important contributions to limiting pathogen attack, an m(2) mutagenized population of a transgenic arabidopsis line was screened for mutants showing constitutive expression of beta-glucuronidase activity driven by the promoter region of the cevi-1 gene. the cevi-1 gene originally was isolated from tomato plants and has been shown to be induced in susceptible varieties of tomato plants by virus infection in a salicylic acid-indepen ... | 2000 | 11090213 |
| metabolism of acyl-homoserine lactone quorum-sensing signals by variovorax paradoxus. | acyl-homoserine lactones (acyl-hsls) serve as dedicated cell-to-cell signaling molecules in many species of the class proteobacteria. we have addressed the question of whether these compounds can be degraded biologically. a motile, rod-shaped bacterium was isolated from soil based upon its ability to utilize n-(3-oxohexanoyl)-l-homoserine lactone as the sole source of energy and nitrogen. the bacterium was classified as a strain of variovorax paradoxus. the v. paradoxus isolate was capable of gr ... | 2000 | 11092851 |
| evidence for a role of rpoe in stressed and unstressed cells of marine vibrio angustum strain s14. | we report the cloning, sequencing, and characterization of the rpoe homolog in vibrio angustum s14. the rpoe gene encodes a protein with a predicted molecular mass of 19.4 kda and has been demonstrated to be present as a single-copy gene by southern blot analysis. the deduced amino acid sequence of rpoe is most similar to that of the rpoe homolog of sphingomonas aromaticivorans, sigma(24), displaying sequence similarity and identity of 63 and 43%, respectively. northern blot analysis demonstrate ... | 2000 | 11092857 |
| molecular evolution of virulence in natural field strains of xanthomonas campestris pv. vesicatoria. | the avrbs2 avirulence gene of the bacterial plant pathogen xanthomonas campestris pv. vesicatoria triggers disease resistance in pepper plants containing the bs2 resistance gene and contributes to bacterial virulence on susceptible host plants. we studied the effects of the pepper bs2 gene on the evolution of avrbs2 by characterizing the molecular basis for virulence of 20 x. campestris pv. vesicatoria field strains that were isolated from disease spots on previously resistant bs2 pepper plants. ... | 2000 | 11092868 |
| phosphorylation of cors and corr, regulatory proteins that modulate production of the phytotoxin coronatine in pseudomonas syringae. | production of the phytotoxin coronatine (cor) in pseudomonas syringae pv. glycinea pg4180 is controlled by a modified two-component regulatory system consisting of three genes, corr, corp, and cors. corr and corp show similarity to response regulators, and cors is related to histidine protein kinases that function as environmental sensors. in this study, corr, corp and the cytoplasmic portion of cors, designated corsdelta, were overproduced in p. syringae as translational fusions to the maltose- ... | 2000 | 11094272 |
| sequence diversity of rula among natural isolates of pseudomonas syringae and effect on function of rulab-mediated uv radiation tolerance. | the rulab locus confers tolerance to uv radiation and is borne on plasmids of the ppt23a family in pseudomonas syringae. we sequenced 14 rula alleles from p. syringae strains representing seven pathovars and found sequence differences of 1 to 12% within pathovar syringae, and up to 15% differences between pathovars. since the sequence variation within rula was similar to that of p. syringae chromosomal alleles, we hypothesized that rulab has evolved over a long time period in p. syringae. a phyl ... | 2000 | 11097885 |
| composition of soil microbial communities enriched on a mixture of aromatic hydrocarbons. | soil contaminated with c5+, which contained benzene (45%, wt/wt), dicyclopentadiene (dcpd) plus cyclopentadiene (together 20%), toluene (6%), styrene (3%), xylenes (2%), naphthalene (2%), and smaller quantities of other compounds, served as the source for isolation of 55 genomically distinct bacteria (standards). use of benzene as a substrate by these bacteria was most widespread (31 of 44 standards tested), followed by toluene (23 of 44), xylenes (14 of 44), styrene (10 of 44), and naphthalene ... | 2000 | 11097903 |
| biogeography and degree of endemicity of fluorescent pseudomonas strains in soil. | fluorescent pseudomonas strains were isolated from 38 undisturbed pristine soil samples from 10 sites on four continents. a total of 248 isolates were confirmed as pseudomonas sensu stricto by fluorescent pigment production and group-specific 16s ribosomal dna (rdna) primers. these isolates were analyzed by three molecular typing methods with different levels of resolution: 16s rdna restriction analysis (ardra), 16s-23s rdna intergenic spacer-restriction fragment length polymorphism (its-rflp) a ... | 2000 | 11097926 |
| functional tn5393-like transposon in the r plasmid pras2 from the fish pathogen aeromonas salmonicida subspecies salmonicida isolated in norway. | tn5393c containing stra-strb was identified as part of r plasmid pras2 from the fish pathogen aeromonas salmonicida subsp. salmonicida. this is the first time an intact and active transposon in the tn5393 family has been reported in an ecological niche other than an agricultural habitat. | 2000 | 11097945 |
| elicitor-induced defence reactions in cell suspension cultures of soybean cultivars. | suspension cultured soybean (glycine max [l.] merr.) cells of four cultivars (wilis, lumut, kalmit, doko rc) were compared for their response to different fungal and bacterial elicitors. cells were treated either with crude cell wall extracts of the fungal pathogens phytophthora sojae (pmg-elicitor) and rhizoctonia solani (riso-elicitor) or with two isolates of the bacterial pathogen pseudomonas syringae pv. glycinea (psg01/02) and a broad spectrum of antimicrobial defence reactions was measured ... | 2000 | 11098822 |
| the pseudomonas syringae avrrpt2 gene product promotes pathogen virulence from inside plant cells. | several bacterial avr genes have been shown to contribute to virulence on susceptible plants lacking the corresponding resistance (r) gene. the mechanisms by which avr genes promote parasitism and disease, however, are not well understood. we investigated the role of the pseudomonas syringae pv. tomato avrrpt2 gene in pathogenesis by studying the interaction of p. syringae pv. tomato strain pstdc3000 expressing avrrpt2 with several arabidopsis thaliana lines lacking the corresponding r gene, rps ... | 2000 | 11106023 |
| elicitation of hypersensitive cell death by extracellularly targeted hrpzpsph produced in planta. | the ability of the pseudomonas syringae pv. phaseolicola harpin (hrpzpsph) to elicit hypersensitive response was investigated in three nicotiana genotypes. the hrpzpsph gene was placed under chemical regulation (tetracycline induction) in tetr+ nicotiana tabacum cv. wisconsin 38 (w38) or was transiently expressed in n. benthamiana following infection with a pvx-derived vector and in three nicotiana genotypes by agroinfiltration. the constructs were designed to express either the canonical form o ... | 2000 | 11106029 |
| signal recognition and transduction mediated by the tomato pto kinase: a paradigm of innate immunity in plants. | plant disease resistance is the result of an innate host defense mechanism, which relies on the ability of the plant to recognize pathogen invasion and to efficiently mount defense responses. in tomato, resistance to the pathogen pseudomonas syringae is mediated by the specific interaction between the plant serine/threonine kinase pto and the bacterial protein avrpto. this article reviews molecular and biochemical properties that confer to pto the capability to function as an intracellular recep ... | 2000 | 11113378 |
| negative regulation of defense responses in plants by a conserved mapkk kinase. | the enhanced disease resistance 1 (edr1) mutation of arabidopsis confers resistance to powdery mildew disease caused by the fungus erysiphe cichoracearum. resistance mediated by the edr1 mutation is correlated with induction of several defense responses, including host cell death. double mutant analysis revealed that all edr1-associated phenotypes are suppressed by mutations that block salicylic acid (sa) perception (nim1) or reduce sa production (pad4 and eds1). the nahg transgene, which lowers ... | 2001 | 11114160 |
| negative regulation of defense responses in plants by a conserved mapkk kinase. | the enhanced disease resistance 1 (edr1) mutation of arabidopsis confers resistance to powdery mildew disease caused by the fungus erysiphe cichoracearum. resistance mediated by the edr1 mutation is correlated with induction of several defense responses, including host cell death. double mutant analysis revealed that all edr1-associated phenotypes are suppressed by mutations that block salicylic acid (sa) perception (nim1) or reduce sa production (pad4 and eds1). the nahg transgene, which lowers ... | 2001 | 11114160 |
| phzo, a gene for biosynthesis of 2-hydroxylated phenazine compounds in pseudomonas aureofaciens 30-84. | certain strains of root-colonizing fluorescent pseudomonas spp. produce phenazines, a class of antifungal metabolites that can provide protection against various soilborne root pathogens. despite the fact that the phenazine biosynthetic locus is highly conserved among fluorescent pseudomonas spp., individual strains differ in the range of phenazine compounds they produce. this study focuses on the ability of pseudomonas aureofaciens 30-84 to produce 2-hydroxyphenazine-1-carboxylic acid (2-oh-pca ... | 2001 | 11114932 |
| fatty acid ketodienes and fatty acid ketotrienes: michael addition acceptors that accumulate in wounded and diseased arabidopsis leaves. | physical damage and disease are known to lead to changes in the oxylipin signature of plants. we searched for oxylipins produced in response to both wounding and pathogenesis in arabidopsis leaves. linoleic acid 9- and 13-ketodienes (kodes) were found to accumulate in wounded leaves as well as in leaves infected with the pathogen pseudomonas syringae pv. tomato (pst). quantification of the compounds showed that they accumulated to higher levels during the hypersensitive response to pst avrrpm1 t ... | 2000 | 11115128 |
| pathogenesis of the human opportunistic pathogen pseudomonas aeruginosa pa14 in arabidopsis. | the human opportunistic pathogen pseudomonas aeruginosa strain pa14 is a multihost pathogen that can infect arabidopsis. we found that pa14 pathogenesis in arabidopsis involves the following steps: attachment to the leaf surface, congregation of bacteria at and invasion through stomata or wounds, colonization of intercellular spaces, and concomitant disruption of plant cell wall and membrane structures, basipetal movement along the vascular parenchyma, and maceration and rotting of the petiole a ... | 2000 | 11115892 |
| defence gene expression in soybean is linked to the status of the cell death program. | soybean cell cultures (cv. williams 82) respond to pseudomonas syringae bacteria expressing the avirulence gene avra with a hypersensitive reaction, a programmed cell death (pcd) of plant cells to pathogen attack. this pcd is under control of salicylic acid (sa) via an unknown mechanism. in the presence of low concentrations of sa, the cells undergo a very rapid cell death, which needs only half of the time required for the normal hypersensitive reaction (hr). northern blot studies for defence-r ... | 2000 | 11117264 |
| stress induces peroxisome biogenesis genes. | peroxisomes are the cellular location of many antioxidants and are themselves significant producers of reactive oxygen species. in this report we demonstrate the induction of peroxisome biogenesis genes in both plant and animal cells by the universal stress signal molecule hydrogen peroxide. using pex1-luc transgenic plants, rapid local and systemic induction of pex1-luciferase could be demonstrated in vivo in response to physiological levels of hydrogen peroxide. pex1-luciferase was also induce ... | 2000 | 11118212 |
| a phaseolus vulgaris lipoxygenase gene expressed in nodules and in rhizobium tropici inoculated roots. | a genomic clone encoding a common bean lipoxygenase (pvlox5) was isolated from a phaseolus vulgaris library. reverse transcription-polymerase chain reaction analysis revealed that pvlox5 is expressed during nodule development and in rhizobium tropici inoculated roots. there was no detectable expression of pvlox5 in non-inoculated roots, healthy leaves, leaves after pseudomonas syringae pv. tabaci infection, floral buds or dry seeds. | 2000 | 11118627 |
| release of cell-free ice nuclei from halomonas elongata expressing the ice nucleation gene inaz of pseudomonas syringae. | release of ice nuclei in the growth medium of recombinant halomonas elongata cells expressing the inaz gene of pseudomonas syringae was studied in an attempt to produce cell-free active ice nuclei for biotechnological applications. cell-free ice nuclei were not retained by cellulose acetate filters of 0.2 microm pore size. highest activity of cell-free ice nuclei was obtained when cells were grown in low salinity (0.5-5% nacl, w/v). freezing temperature threshold, estimated to be below -7 degree ... | 2000 | 11119152 |
| structure-function analysis of the tobacco mosaic virus resistance gene n. | the tobacco n gene is a member of the toll-interleukin-1 receptor/nucleotide-binding site/leucine-rich repeat (tir-nbs-lrr) class of plant resistance (r) genes and confers resistance to tobacco mosaic virus (tmv). we investigated the importance of specific domains of n in inducing tmv resistance, by examining various n deletion and point mutations that introduce single amino acid substitution mutants in vivo. our deletion analysis suggests that the tir, nbs, and lrr domains play an indispensable ... | 2000 | 11121079 |
| simultaneous ethanol and bacterial ice nuclei production from sugar beet molasses by a zymomonas mobilis cp4 mutant expressing the inaz gene of pseudomonas syringae in continuous culture. | the aim of this work was to construct a zymomonas mobilis mutant capable of simultaneous ethanol and ice nuclei production from agricultural by-product such as sugar beet molasses, in steady-state continuous culture. | 2000 | 11123473 |
| oxidative burst and cognate redox signalling reported by luciferase imaging: identification of a signal network that functions independently of ethylene, sa and me-ja but is dependent on mapkk activity. | recognition of avirulent microbial pathogens activates an oxidative burst leading to the accumulation of reactive oxygen intermediates (rois), which are thought to integrate a diverse set of defence mechanisms resulting in the establishment of plant disease resistance. a novel transgenic arabidopsis line containing a gst1:luc transgene was developed and employed to report the temporal and spatial dynamics of roi accumulation and cognate redox signalling in response to attempted infection by avir ... | 2000 | 11123796 |
| membrane-permeabilizing activities of cyclic lipodepsipeptides, syringopeptin 22a and syringomycin e from pseudomonas syringae pv. syringae in human red blood cells and in bilayer lipid membranes. | the pore-forming activities of cyclic lipodepsipeptides (clps), syringopeptin 22a (sp22a) and syringomycin e (sre) were compared on the human red blood cell (rbc) membrane and on bilayer lipid membranes (blms). sp22a above a concentration of 4 x 10(5) molecules/cell significantly increased the rbc membrane permeability for 86rb. with electric current measurements on blm, it was proved that like sre, the sp22a formed two types of ion channels in the membrane, small and large, the latter having si ... | 2000 | 11129239 |
| novel tellurite-amended media and specific chromosomal and ti plasmid probes for direct analysis of soil populations of agrobacterium biovars 1 and 2. | ecology and biodiversity studies of agrobacterium spp. require tools such as selective media and dna probes. tellurite was tested as a selective agent and a supplement of previously described media for agrobacteria. the known biodiversity within the genus was taken into account when the selectivity of k(2)teo(3) was analyzed and its potential for isolating agrobacterium spp. directly from soil was evaluated. a k(2)teo(3) concentration of 60 ppm was found to favor the growth of agrobacteria and r ... | 2001 | 11133429 |
| direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia. | enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ... | 2001 | 11133432 |
| pantoea agglomerans strain eh318 produces two antibiotics that inhibit erwinia amylovora in vitro. | pantoea agglomerans (synonym: erwinia herbicola) strain eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with erwinia amylovora, the causal agent of fire blight. this zone is caused by two antibiotics, named pantocin a and b. using a genomic library of eh318, two cosmids, pcpp702 and pcpp704, were identified that conferred on escherichia coli the ability to inhibit growth of e. amylovora. the two cosmids conferred different antibiotic activities on e. col ... | 2001 | 11133457 |
| gene cloning and functional characterization by heterologous expression of the fructosyltransferase of aspergillus sydowi iam 2544. | we have purified a fructosyltransferase from conidia of the inulin-producing fungus aspergillus sydowi iam 2544 and obtained peptide sequences from proteolytic fragments of the protein. with degenerated primers, we amplified a pcr fragment that was used to screen a cdna library. the fructosyltransferase gene from aspergillus sydowi (embl accession no. aj289046) is expressed in conidia, while no expression could be detected in mycelia by northern blot analysis of mycelial rna. the gene encodes a ... | 2001 | 11133467 |
| genetic and molecular organization of the alkylbenzene catabolism operon in the psychrotrophic strain pseudomonas putida 01g3. | the 11-kb sequence encompassing the alkylbenzene upper pathway in pseudomonas putida 01g3, a psychrotrophic strain able to degrade alkylbenzenes at low temperatures, was characterized. together with a potential regulator (ebdr), six putative enzymes (ebdaaabacadbc) were identified, and they exhibited highly significant similarities with enzymes implicated in the equivalent pathway in p. putida re204. ebd genes appeared to be preferentially induced by ethylbenzene. multiple-alignment data and gro ... | 2001 | 11133479 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro. | the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ... | 2001 | 11134504 |
| the release of alginate lyase from growing pseudomonas syringae pathovar phaseolicola. | pseudomonas syringae pathovar phaseolicola, which produces alginate during stationary growth phase, displayed elevated extracellular alginate lyase activity during both mid-exponential and late-stationary growth phases of batch growth. intracellular activity remained below 22% of the total activity during exponential growth, suggesting that alginate lyase has an extracellular function for this organism. extracellular enzyme activity in continuous cultures, grown in either nutrient broth or gluco ... | 2001 | 11136126 |
| accumulation of soluble and wall-bound indolic metabolites in arabidopsis thaliana leaves infected with virulent or avirulent pseudomonas syringae pathovar tomato strains. | the chemical structures and accumulation kinetics of several major soluble as well as wall-bound, alkali-hydrolyzable compounds induced upon infection of arabidopsis thaliana leaves with pseudomonas syringae pathovar tomato were established. all identified accumulating products were structurally related to tryptophan. most prominent among the soluble substances were tryptophan, beta-d-glucopyranosyl indole-3-carboxylic acid, 6-hydroxyindole-3-carboxylic acid 6-o-beta-d-glucopyranoside, and the i ... | 2001 | 11136235 |
| induction of ltp (lipid transfer protein) and pal (phenylalanine ammonia-lyase) gene expression in rice roots colonized by the arbuscular mycorrhizal fungus glomus mosseae. | the expression of a lipid transfer protein (ltp) gene is regulated in oryza sativa roots in response to colonization by the mycorrhizal fungus glomus mosseae. transcript levels increased when the fungus forms appressoria and penetrates the root epidermis and decreased at the onset of the intercellular colonization of the root cortex. the analysis of histochemical gus staining in transgenic rice plants carrying the ltp/gus construct confirm the induction of ltp: gene associated with fungal appres ... | 2000 | 11141171 |
| the pseudomonas avrpto protein is differentially recognized by tomato and tobacco and is localized to the plant plasma membrane. | the avrpto gene of pseudomonas syringae pv tomato triggers race-specific resistance in tomato plants carrying pto, a resistance gene encoding a protein kinase. when introduced into p. s. tabaci, avrpto triggers resistance in tobacco w38 plants that carry the corresponding r gene. the avrpto protein is believed to be secreted into host cells through the bacterial type iii secretion pathway, where it activates disease resistance in tomato by interacting with pto. we report here the identification ... | 2000 | 11148281 |
| nuclear localization of npr1 is required for activation of pr gene expression. | systemic acquired resistance (sar) is a broad-spectrum resistance in plants that involves the upregulation of a battery of pathogenesis-related (pr) genes. npr1 is a key regulator in the signal transduction pathway that leads to sar. mutations in npr1 result in a failure to induce pr genes in systemic tissues and a heightened susceptibility to pathogen infection, whereas overexpression of the npr1 protein leads to increased induction of the pr genes and enhanced disease resistance. we analyzed t ... | 2000 | 11148282 |
| mutational analysis of the arabidopsis nucleotide binding site-leucine-rich repeat resistance gene rps2. | disease resistance proteins containing a nucleotide binding site (nbs) and a leucine-rich repeat (lrr) region compose the largest class of disease resistance proteins. these so-called nbs-lrr proteins confer resistance against a wide variety of phytopathogens. to help elucidate the mechanism by which nbs-lrr proteins recognize and transmit pathogen-derived signals, we analyzed mutant versions of the arabidopsis nbs-lrr protein rps2. the rps2 gene confers resistance against pseudomonas syringae s ... | 2000 | 11148296 |
| the arabidopsis-accelerated cell death gene acd2 encodes red chlorophyll catabolite reductase and suppresses the spread of disease symptoms. | accelerated cell death 2 (acd2) mutants of arabidopsis have spontaneous spreading cell death lesions and constitutive activation of defenses in the absence of pathogen infection. lesion formation in acd2 plants can be triggered by the bacterial toxin coronatine through a light-dependent process. coronatine-triggered and spontaneous lesion spreading in acd2 plants also requires protein translation, indicating that cell death occurs by an active process. we have cloned the acd2 gene; its predicted ... | 2001 | 11149948 |
| cloning and characterization of estc from burkholderia gladioli, a novel-type esterase related to plant enzymes. | by screening a genomic library of burkholderia gladioli (formerly pseudomonas marginata) for clones exhibiting esterolytic activity, the gene for a novel-type esterase (estc) showing significant homology to plant enzymes could be isolated. high homology was found to two hydroxynitrile lyases originating from hevea brasiliensis (tropical rubber tree) and manihot esculenta (cassava), and to two proteins from oryza sativa (rice) that are specifically induced upon infection by pseudomonas syringae p ... | 2000 | 11152069 |
| pseudomonas frederiksbergensis sp. nov., isolated from soil at a coal gasification site. | phenotypic and genotypic characterization indicated that a group of 29 closely related phenanthrene-degrading bacteria from a coal gasification site in frederiksberg, copenhagen, denmark, belonged to the genus pseudomonas. the strains were isolated at two sampling occasions 2 years apart. the isolates were phenotypically different from any known species of the genus pseudomonas and were therefore subject to further identification. colonies were smooth and pale yellowish and did not produce pigme ... | 2000 | 11155968 |
| analysis of the type iv fimbrial-subunit gene fima of xanthomonas hyacinthi: application in pcr-mediated detection of yellow disease in hyacinths. | a sensitive and specific detection method was developed for xanthomonas hyacinthi; this method was based on amplification of a subsequence of the type iv fimbrial-subunit gene fima from strain s148. the fima gene was amplified by pcr with degenerate dna primers designed by using the n-terminal and c-terminal amino acid sequences of trypsin fragments of fima. the nucleotide sequence of fima was determined and compared with the nucleotide sequences coding for the fimbrial subunits in other type iv ... | 2001 | 11157222 |
| iron-binding compounds from agrobacterium spp.: biological control strain agrobacterium rhizogenes k84 produces a hydroxamate siderophore. | iron-binding compounds were produced in various amounts in response to iron starvation by a collection of agrobacterium strains belonging to the species a. tumefaciens, a. rhizogenes, and a. vitis. the crown gall biocontrol agent a. rhizogenes strain k84 produced a hydroxamate iron chelator in large amounts. production of this compound, and also of a previously described antibiotic-like substance called als84, occurred only in cultures of strain k84 grown in iron-deficient medium. similarly, sen ... | 2001 | 11157228 |
| the adna transcriptional factor affects persistence and spread of pseudomonas fluorescens under natural field conditions. | a soil plot was inoculated with a mixture of pseudomonas fluorescens pf0-2, the wild type, and pf0-5a, a tn5 insertion mutant in adna, at 7.84 log cfu/g of soil. over a period of 231 days, culturable populations of both strains were measured at selected times below and away from the point of inoculation. pf0-5a did not spread as fast and attained significantly lower populations than pf0-2. at sample depths below the inoculation site, the adna mutant showed a significant decrease in cfu/g of soil ... | 2001 | 11157254 |
| potential symbiosis-specific genes uncovered by sequencing a 410-kilobase dna region of the bradyrhizobium japonicum chromosome. | the physical and genetic map of the bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. therefore, we determined the nucleotide sequence of a 410-kb region. the overall g+c nucleotide content was 59.1%. using a minimum gene length of 150 nucleotid ... | 2001 | 11157954 |
| syringolin reprograms wheat to undergo hypersensitive cell death in a compatible interaction with powdery mildew. | we had previously isolated and characterized syringolin a, one of the molecular determinants secreted by pseudomonas syringae pv syringae that is perceived by nonhost plant species such as rice. here, we show that syringolin a is recognized by wheat and that it induces the accumulation of gene transcripts and increases protection against powdery mildew when applied before inoculation. moreover, syringolin a essentially eradicates powdery mildew from infected wheat if applied after inoculation. t ... | 2001 | 11158536 |
| six amino acid changes confined to the leucine-rich repeat beta-strand/beta-turn motif determine the difference between the p and p2 rust resistance specificities in flax. | at least six rust resistance specificities (p and p1 to p5) map to the complex p locus in flax. the p2 resistance gene was identified by transposon tagging and transgenic expression. p2 is a member of a small multigene family and encodes a protein with nucleotide binding site (nbs) and leucine-rich repeat (lrr) domains and an n-terminal toll/interleukin-1 receptor (tir) homology domain, as well as a c-terminal non-lrr (cnl) domain of approximately 150 amino acids. a related cnl domain was detect ... | 2001 | 11158537 |
| the arabidopsis isr1 locus controlling rhizobacteria-mediated induced systemic resistance is involved in ethylene signaling. | in arabidopsis, the rhizobacterial strain pseudomonas fluorescens wcs417r triggers an induced systemic resistance (isr) response that is effective against different types of pathogens. the isr signaling pathway functions independent of salicylic acid, but requires responsiveness to jasmonate (ja) and ethylene. using the genetic variability of isr inducibility between arabidopsis accessions, we recently identified a locus (isr1) on chromosome iii that is involved in isr signaling. accessions rld ... | 2001 | 11161023 |
| a comparison of the effects of dna-damaging agents and biotic elicitors on the induction of plant defense genes, nuclear distortion, and cell death. | pea (pisum sativum l. cv alcan) endocarp tissue challenged with an incompatible fungal pathogen, fusarium solani f. sp. phaseoli or fungal elicitors results in the induction of pathogenesis-related (pr) genes and the accumulation of pisatin, a phytoalexin. essentially the same response occurs in pea tissue exposed to dna-specific agents that crosslink or intercalate dna. in this study, the effects of dna-damaging agents were assessed relative to the inducible expression of several pea pr genes: ... | 2001 | 11161032 |
| the use of 16s and 16s-23s rdna to easily detect and differentiate common gram-negative orchard epiphytes. | the identification of gram-negative pathogenic and non-pathogenic bacteria commonly isolated from an orchard phylloplane may result in a time consuming and tedious process for the plant pathologist. the paper provides a simple "one-step" protocol that uses the polymerase chain reaction (pcr) to amplify intergenic spacer regions between 16s and 23s genes and a portion of 16s gene in the prokaryotic rrna genetic loci. amplified 16s rdna, and restriction fragment length polymorphisms (rflp) followi ... | 2001 | 11166101 |
| cell surface display of salmobin, a thrombin-like enzyme from agkistrodon halys venom on escherichia coli using ice nucleation protein. | cell surface display on escherichia coli using ice nucleation protein was performed in order to develop a new expression system for recombinant eukaryotic proteins. salmobin, the thrombin-like enzyme obtained from korean snake (agkistrodon halys) venom was displayed on the surface of escherichia coli fused to the c-terminus of the ice nucleation protein (inp), an outer membrane protein of pseudomonas syringae. the thrombin cleavage site was inserted between salmobin and inp. the presence of salm ... | 2001 | 11166806 |
| probenazole induces systemic acquired resistance in arabidopsis with a novel type of action. | probenazole (pbz; 3-allyloxy-1,2-benzisothiazole-1,1-dioxide), which is the active ingredient in oryzemate, has been used widely in asia to protect rice plants against the rice blast fungus magnaporthe grisea. to study pbz's mode of action, we analyzed its ability, as well as that of its active metabolite 1, 2-benzisothiazol-3 (2h)-one 1,1-dioxide (bit) to induce defense gene expression and resistance in arabidopsis mutants that are defective in various defense signaling pathways. wild-type arab ... | 2001 | 11169191 |