Publications

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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
roles of salicylic acid, jasmonic acid, and ethylene in cpr-induced resistance in arabidopsis.	disease resistance in arabidopsis is regulated by multiple signal transduction pathways in which salicylic acid (sa), jasmonic acid (ja), and ethylene (et) function as key signaling molecules. epistasis analyses were performed between mutants that disrupt these pathways (npr1, eds5, ein2, and jar1) and mutants that constitutively activate these pathways (cpr1, cpr5, and cpr6), allowing exploration of the relationship between the sa- and ja/et-mediated resistance responses. two important findings ...	2000	11090217
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
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
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
impact of post-anoxia stress on membrane lipids of anoxia-pretreated potato cells. a re-appraisal.	the importance of lipid peroxidation and its contributing pathways (via reactive oxygen species and lipoxygenase) during post-anoxia was evaluated with respect to the biphasic behavior of membrane lipids under anoxia (a. rawyler, d. pavelic, c. gianinazzi, j. oberson, r. brändle [1999] plant physiol 120: 293-300), using potato (solanum tuberosum cv bintje) cell cultures. when anoxic cells in the pre-lytic phase were re-oxygenated for 2 h, superoxide anion was not detectable, the hydrogen peroxid ...	2000	11080304
sensing of osmotic pressure changes in tomato cells.	cells of tomato (lycopersicon esculentum) growing in suspension gradually depleted their culture medium and caused a steady decrease in its osmolality. when confronted with a sudden change in medium osmolality (a hypo-osmotic or hyperosmotic shock), respectively, these cells responded with volume changes and stress symptoms such as rapid extracellular alkalinization, efflux of k(+)-ions, and induction of 1-aminocyclopropane-1-carboxylate synthase acid, the key enzyme of ethylene biosynthesis. th ...	2000	11080294
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
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
the polymerase subunit of a dsrna virus plays a central role in the regulation of viral rna metabolism.	bacteriophage φ6 has a three-segmented double-stranded (ds) rna genome, which resides inside a polymerase complex particle throughout the entire life cycle of the virus. the polymerase subunit p2, a minor constituent of the polymerase complex, has previously been reported to replicate both φ6-specific and heterologous single-stranded (ss) rnas, giving rise to dsrna products. in this study, we show that the enzyme is also able to use dsrna templates to perform semi-conservative rna transc ...	2000	11080173
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
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
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
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
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
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
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
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
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
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
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
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
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
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
ozone-sensitive arabidopsis rcd1 mutant reveals opposite roles for ethylene and jasmonate signaling pathways in regulating superoxide-dependent cell death.	we have isolated a codominant arabidopsis mutant, radical-induced cell death1 (rcd1), in which ozone (o(3)) and extracellular superoxide (o(2)()-), but not hydrogen peroxide, induce cellular o(2)()- accumulation and transient spreading lesions. the cellular o(2)()- accumulation is ethylene dependent, occurs ahead of the expanding lesions before visible symptoms appear, and is required for lesion propagation. exogenous ethylene increased o(2)()--dependent cell death, whereas impairment of eth ...	2000	11041881
fumonisin b1-induced cell death in arabidopsis protoplasts requires jasmonate-, ethylene-, and salicylate-dependent signaling pathways.	we have established an arabidopsis protoplast model system to study plant cell death signaling. the fungal toxin fumonisin b1 (fb1) induces apoptosis-like programmed cell death (pcd) in wild-type protoplasts. fb1, however, only marginally affects the viability of protoplasts isolated from transgenic nahg plants, in which salicylic acid (sa) is metabolically degraded; from pad4-1 mutant plants, in which an sa amplification mechanism is thought to be impaired; or from jar1-1 or etr1-1 mutant plant ...	2000	11041879
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
novel fosfomycin resistance of pseudomonas aeruginosa clinical isolates recovered in japan in 1996.		2000	10970248
ice crystallization by pseudomonas syringae.	several bacterial species can serve as biological ice nuclei. the best characterized of these is pseudomonas syringae, a widely distributed bacterial epiphyte of plants. these biological ice nuclei find various applications in different fields, but an optimized production method was required in order to obtain the highly active cells which may be exploited as ice nucleators. the results presented here show that p. syringae cells reduce supercooling of liquid or solid media and enhance ice crysta ...	2000	10968626
purification and characterization of novel antifungal compounds from the sourdough lactobacillus plantarum strain 21b.	sourdough lactic acid bacteria were selected for antifungal activity by a conidial germination assay. the 10-fold-concentrated culture filtrate of lactobacillus plantarum 21b grown in wheat flour hydrolysate almost completely inhibited eurotium repens ibt18000, eurotium rubrum ftdc3228, penicillium corylophilum ibt6978, penicillium roqueforti ibt18687, penicillium expansum idm/fs2, endomyces fibuliger ibt605 and idm3812, aspergillus niger ftdc3227 and idm1, aspergillus flavus ftdc3226, monilia s ...	2000	10966432
genotypic characterization of bradyrhizobium strains nodulating small senegalese legumes by 16s-23s rrna intergenic gene spacers and amplified fragment length polymorphism fingerprint analyses.	we examined the genotypic diversity of 64 bradyrhizobium strains isolated from nodules from 27 native leguminous plant species in senegal (west africa) belonging to the genera abrus, alysicarpus, bryaspis, chamaecrista, cassia, crotalaria, desmodium, eriosema, indigofera, moghania, rhynchosia, sesbania, tephrosia, and zornia, which play an ecological role and have agronomic potential in arid regions. the strains were characterized by intergenic spacer (between 16s and 23s rrna genes) pcr and res ...	2000	10966419
the octadecanoid pathway is required for pathogen-induced multi-functional acetyl-coa carboxylase accumulation in common bean (phaseolus vulgaris l.).	a partial cdna clone corresponding to the multi-functional acetyl-coa carboxylase (accase, ec 6.4.1.2) was isolated using rna extracted from methyl jasmonate (meja)-induced common bean cell cultures. most of this clone corresponds to the 3' untranslated region and it showed high identity to alfalfa and soybean accase sequences. southern hybridization revealed one copy of this gene in the common bean genome. in addition to being induced by meja in cell cultures and leaves, accase mrna accumulated ...	2000	10960731
mutations in multidrug efflux homologs, sugar isomerases, and antimicrobial biosynthesis genes differentially elevate activity of the sigma(x) and sigma(w) factors in bacillus subtilis.	the sigma(x) and sigma(w) extracytoplasmic function sigma factors regulate more than 40 genes in bacillus subtilis. sigma(w) activates genes which function in detoxification and the production of antimicrobial compounds, while sigma(x) activates functions that modify the cell envelope. transposon mutagenesis was used to identify loci which negatively regulate sigma(w) or sigma(x) as judged by up-regulation from the autoregulatory promoter site p(w) or p(x). fourteen insertions that activate p(w) ...	2000	10960106
cloning and characterization of the glucooligosaccharide catabolic pathway beta-glucan glucohydrolase and cellobiose phosphorylase in the marine hyperthermophile thermotoga neapolitana.	characterization in thermotoga neapolitana of a catabolic gene cluster encoding two glycosyl hydrolases, 1,4-beta-d-glucan glucohydrolase (ggha) and cellobiose phosphorylase (cbpa), and the apparent absence of a cellobiohydrolase (cbh) suggest a nonconventional pathway for glucan utilization in thermotogales. ggha purified from t. neapolitana is a 52.5-kda family 1 glycosyl hydrolase with optimal activity at ph 6.5 and 95 degrees c. ggha releases glucose from soluble glucooligomers, with a prefe ...	2000	10960102
plasmid-located pathogenicity determinants of serratia entomophila, the causal agent of amber disease of grass grub, show similarity to the insecticidal toxins of photorhabdus luminescens.	serratia entomophila and serratia proteamaculans cause amber disease in the grass grub costelytra zealandica (coleoptera: scarabaeidae), an important pasture pest in new zealand. larval disease symptoms include cessation of feeding, clearance of the gut, amber coloration, and eventual death. a 115-kb plasmid, padap, identified in s. entomophila is required for disease causation and, when introduced into escherichia coli, enables that organism to cause amber disease. a 23-kb fragment of padap tha ...	2000	10960097
chemoenzymatic synthesis of the microbial elicitor (-)-syringolide via a fructose 1,6-diphosphate aldolase-catalyzed condensation reaction.	syringolide 2, an elicitor of the bacterial plant pathogen pseudomonas syringae pv. tomato which triggers a hypersensitive defense response in resistant soybean plants, has been synthesized in five steps via a fructose 1,6-diphosphate aldolase reaction.	2000	10959854
constitutive expression of the defense-related rir1b gene in transgenic rice plants confers enhanced resistance to the rice blast fungus magnaporthe grisea.	the rirlb gene of rice (oryza sativa) is one of a set of putative defense genes whose transcripts accumulate upon inoculation of rice with the non-host pathogen pseudomonas syringae pv. syringae. it belongs to a family of genes encoding small extracellular proteins so far only identified in cereals. to assess the function of the rirlb gene in rice blast resistance, it was placed under the control of the camv 35s promoter and transferred into rice plants of the japonica variety taipei 309 by biol ...	2000	10949374
receptor-mediated increase in cytoplasmic free calcium required for activation of pathogen defense in parsley.	transient influx of ca(2+) constitutes an early element of signaling cascades triggering pathogen defense responses in plant cells. treatment with the phytophthora sojae-derived oligopeptide elicitor, pep-13, of parsley cells stably expressing apoaequorin revealed a rapid increase in cytoplasmic free calcium ([ca(2+)](cyt)), which peaked at approximately 1 microm and subsequently declined to sustained values of 300 nm. activation of this biphasic [ca(2+)](cyt) signature was achieved by elicitor ...	2000	10948260
local and systemic changes in squash gene expression in response to silverleaf whitefly feeding.	squash genes (slw1 and slw3) induced systemically after silverleaf whitefly feeding were identified. differences in the local and systemic expression of slw1 and slw3 after feeding by the closely related silverleaf and sweetpotato whiteflies were observed. temporal and spatial studies showed that slw1 and slw3 were induced when second, third, and fourth nymphal instars were feeding. although only barely detected after wounding and bacterial infection, slw1 and slw3 rnas were abundant during wate ...	2000	10948259
evidence for a role of the n terminus and leucine-rich repeat region of the mi gene product in regulation of localized cell death.	the tomato mi gene confers resistance against root-knot nematodes and potato aphids. chimeric constructs of the functional gene, mi-1. 2, with a homolog, mi-1.1, were produced, and their phenotypes were examined in agrobacterium rhizogenes-transformed roots. exchange of the leucine-rich repeat (lrr) region of mi-1.1 into mi-1.2 resulted in the loss of ability to confer nematode resistance, as did substitution of a 6-amino acid sequence from the mi-1.1 lrr into mi-1.2. introduction of the mi-1.2 ...	2000	10948252
induced expression of sarcotoxin ia enhanced host resistance against both bacterial and fungal pathogens in transgenic tobacco.	we demonstrate here that induced expression of sarcotoxin ia, a bactericidal peptide from sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. the peptide was produced with a modified pr1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. host resistance to infection of bacteria erwinia carotovora subsp. carotovora and pseudomonas syringae pv. tabaci was shown to be d ...	2000	10939257
characterization and expression of dna sequences encoding putative type-ii metallothioneins in the seagrass posidonia oceanica.	posidonia oceanica is a marine phanerogam, largely widespread in the mediterranean sea, representing an important food substrate for many marine organisms. a progressive reduction of p. oceanica meadows has been reported, due to anthropogenic coastal activity. studying mechanisms by which this species responds to environmental stresses, three dna sequences putatively encoding metallothioneins (mts) have been isolated, by pcr. two sequences, pomt2a (accession no. aj249603) and pomt2b (accession n ...	2000	10938373
the mid-pericarp cell layer in soybean pod walls is a multicellular compartment enriched in specific lipoxygenase isoforms.	specific lipoxygenase isoforms immunolocalize to the cytosol of a single cell layer in the soybean (glycine max l.) pod wall. the cells of this layer, termed the mid-pericarp layer (mpl), are larger than adjacent cells and are highly branched. the entire mpl appears to form an elaborate interdigitated network within the pod wall. a particularly striking feature of the mpl is the presence of extensive regions of very thin, approximately 30 nm, cell wall, which connect the cells of the mpl. it was ...	2000	10938347
expression of single chain antibodies (scfvs) for c-myc oncoprotein in recombinant escherichia coli membranes by using the ice-nucleation protein of pseudomonas syringae.	the ice nucleation protein (inp) is a glycosyl phosphatidylinositol anchored outer membrane protein found in certain gram-negative bacteria. in this study, the inp from pseudomonas syringae was applied as a fusion partner with the single chain antibody fragment (scfv) against the human oncoprotein c-myc. two new plasmids pninaz-myc and pninazscfv-bsaa1 were constructed and cloned into escherichia coli jm109. the expression of the fusion protein was successfully demonstrated in the cloned cells. ...	2000	10933828
the virulence factor avrxa7 of xanthomonas oryzae pv. oryzae is a type iii secretion pathway-dependent nuclear-localized double-stranded dna-binding protein.	avrxa7 is a member of the avrbs3 avirulence gene family, which encodes proteins targeted to plant cells by a type iii secretion apparatus. avrxa7, the product of avrxa7, is also a virulence factor in strain pxo86 of xanthomonas oryzae pv. oryzae. avirulence and virulence specificities are associated with the central repeat domain, which, in avrxa7, consists of 25.5 direct repeat units. mutations in three c-terminal nuclear localization signal motifs eliminated avirulence and virulence activities ...	2000	10931960
conversion of compatible plant-pathogen interactions into incompatible interactions by expression of the pseudomonas syringae pv. syringae 61 hrma gene in transgenic tobacco plants.	the hrma gene from pseudomonas syringae pv. syringae has previously been shown to confer avirulence on the virulent bacterium p. syringae pv. tabaci in all examined tobacco cultivars. we expressed this gene in tobacco plants under the control of the tobacco delta0. 3 tobrb7 promoter, which is induced upon nematode infection in tobacco roots (opperman et al. 1994, science, 263, 221-223). a basal level of hrma expression in leaves of transgenic plants activated the expression of pathogenesis-relat ...	2000	10929114
requirement of sphingolipid alpha-hydroxylation for fungicidal action of syringomycin e.	syringomycin e is an antifungal cyclic lipodepsinonapeptide produced by pseudomonas syringae pv. syringae. to understand the mechanism of action of syringomycin e, a novel resistant saccharomyces cerevisiae strain, bw7, was isolated and characterized. lipid analyses revealed that bw7 contained only the hydrophobic subspecies of sphingolipids that are normally minor components in wild type strains. this aberrant sphingolipid composition was the result of lack of alpha-hydroxylation of the amide-l ...	2000	10922463
nitric oxide and salicylic acid signaling in plant defense.	salicylic acid (sa) plays a critical signaling role in the activation of plant defense responses after pathogen attack. we have identified several potential components of the sa signaling pathway, including (i) the h(2)o(2)-scavenging enzymes catalase and ascorbate peroxidase, (ii) a high affinity sa-binding protein (sabp2), (iii) a sa-inducible protein kinase (sipk), (iv) npr1, an ankyrin repeat-containing protein that exhibits limited homology to ikappabalpha and is required for sa signaling, ...	2000	10922045
avrpto-dependent pto-interacting proteins and avrpto-interacting proteins in tomato.	the plant-intracellular interaction of the avirulence protein avrpto of pseudomonas syringae pathovar tomato, the agent of bacterial speck disease, and the corresponding tomato resistance protein pto triggers responses leading to disease resistance. pto, a serine/threonine protein kinase, also interacts with a putative downstream kinase, pto-interactor 1, as well as with members of a family of transcription factors pto-interactors 4, 5, and 6. these proteins are likely involved, respectively, in ...	2000	10922043
plants and animals share functionally common bacterial virulence factors.	by exploiting the ability of pseudomonas aeruginosa to infect a variety of vertebrate and nonvertebrate hosts, we have developed model systems that use plants and nematodes as adjuncts to mammalian models to help elucidate the molecular basis of p. aeruginosa pathogenesis. our studies reveal a remarkable degree of conservation in the virulence mechanisms used by p. aeruginosa to infect hosts of divergent evolutionary origins.	2000	10922040
genetic complexity of pathogen perception by plants: the example of rcr3, a tomato gene required specifically by cf-2.	genetic analysis of plant-pathogen interactions has demonstrated that resistance to infection is often determined by the interaction of dominant plant resistance (r) genes and dominant pathogen-encoded avirulence (avr) genes. it was postulated that r genes encode receptors for avr determinants. a large number of r genes and their cognate avr genes have now been analyzed at the molecular level. r gene loci are extremely polymorphic, particularly in sequences encoding amino acids of the leucine-ri ...	2000	10922039
molecular and cell biology aspects of plague.	a 70-kb virulence plasmid (sometimes called pyv) enables yersinia spp. to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, a system consisting of secreted proteins called yops and their dedicated type iii secretion apparatus called ysc. the ysc apparatus forms a channel composed of 29 proteins. of these, 10 have counterparts in almost every type iii system. secretion of some yops requires the assistance, in the bacterial cytosol, of small individual chapero ...	2000	10922034
pseudomonas syringae hrp type iii secretion system and effector proteins.	pseudomonas syringae is a member of an important group of gram-negative bacterial pathogens of plants and animals that depend on a type iii secretion system to inject virulence effector proteins into host cells. in p. syringae, hrp/hrc genes encode the hrp (type iii secretion) system, and avirulence (avr) and hrp-dependent outer protein (hop) genes encode effector proteins. the hrp/hrc genes of p. syringae pv syringae 61, p. syringae pv syringae b728a, and p. syringae pv tomato dc3000 are flanke ...	2000	10922033
direct interaction of resistance gene and avirulence gene products confers rice blast resistance.	rice expressing the pi-ta gene is resistant to strains of the rice blast fungus, magnaporthe grisea, expressing avr-pita in a gene-for-gene relationship. pi-ta encodes a putative cytoplasmic receptor with a centrally localized nucleotide-binding site and leucine-rich domain (lrd) at the c-terminus. avr-pita is predicted to encode a metalloprotease with an n-terminal secretory signal and pro-protein sequences. avr-pita(176) lacks the secretory and pro-protein sequences. we report here that transi ...	2000	10921881
expression of a functional antizearalenone single-chain fv antibody in transgenic arabidopsis plants.	the efficacy of cloning a recombinant mycotoxin antibody in plants was tested using arabidopsis as a model. an antizearalenone single-chain fv (scfv) dna fragment was first cloned in the newly constructed phage display vector (pey.5) and then recloned in the plant transformation vector pkylx71::35s(2). after transformation, constructs of antizearalenone scfv were introduced into immature arabidopsis seeds via agrobacterium tumefaciens mediation by vacuum infiltration. only plants transformed wit ...	2000	10919813
rapid methods for testing the efficacy of sterilization-grade filter membranes.	the validation of sterilization-grade membranes is integral to ensuring the efficient and safe use of microfiltration systems. here validation refers to the production of sterile filtrate for sterilizing-grade membranes under challenge test conditions. current validation methods require 48 h of culture for results to become available, which creates time delays within the manufacturing process and quality control (qc) backlogs. this work compares four methods for the production of filter challeng ...	2000	10919803
a genomic sample sequence of the entomopathogenic bacterium photorhabdus luminescens w14: potential implications for virulence.	photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. after invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. however, the bacterial virulence factors associated with this "symbiosis of pathogens" remain largely obscure. in order to identify genes encoding potential virulence factors, we performed approximately 2,00 ...	2000	10919786