Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| identification of a promoter region on the halomonas elongata cryptic plasmid phe1 employing the inaz reporter gene of pseudomonas syringae. | a native promoter located on the cryptic plasmid phe1 from the moderate halophile halomonas elongata was identified employing a promoterless ice nucleation gene inaz of pseudomonas syringae by direct subcloning and assaying for ice nucleation activity. the presence of the promoter was verified by inserting the corresponding intact or deleted phe1 fragment in the promoter analysis vector pkk232-8 upstream of the promoterless cat or inaz gene. only constructs carrying the intact phe1 fragment gave ... | 1997 | 9297819 |
| expression and analysis of coronafacate ligase, a thermoregulated gene required for production of the phytotoxin coronatine in pseudomonas syringae. | coronafacic acid, the polyketide component of the phytotoxin coronatine, is activated and coupled to coronamic acid via amide bond formation, a biosynthetic step presumably catalyzed by the coronafacate ligase (cfl) gene product. in the present study, cfl was fused to the carboxy terminus of male, which encodes the maltose-binding protein (mbp), and overexpressed in escherichia coli. immunoblot analysis indicated that cfl contained an atp-binding region, a motif conserved in enzymes which activa ... | 1997 | 9297822 |
| molecular organisation of the ice nucleation protein inav from pseudomonas syringae. | a new ice nucleation gene from pseudomonas syringae was isolated and overexpressed as a fully active protein in escherichia coli in order to gain experimental data about the structure of ice nucleation proteins. no evidence of a signal sequence or secondary glycosylation was found. differences in the extent of aggregation were shown to modulate the ice nucleation activity. the circular dichroism spectrum of the purified protein indicated the presence of beta-sheet structure. this finding support ... | 1997 | 9323042 |
| avirulence gene d of pseudomonas syringae pv. tomato may have undergone horizontal gene transfer. | avirulence gene d (avrd) is carried on the b-plasmid of the plant pathogen pseudomonas syringae pv. tomato with plasmid-borne avrd homologs widely distributed among the pseudomonads. we now report sequences in the soft rot pathogen erwinia carotovora that cross-hybridize to avrd suggesting a conserved function beyond avirulence. alternatively, avrd may have been transferred horizontally among species: (i) dna linked to avrd shows evidence of class ii transpositions and contains a novel is3-relat ... | 1997 | 9326365 |
| the cpr5 mutant of arabidopsis expresses both npr1-dependent and npr1-independent resistance. | the cpr5 mutant was identified from a screen for constitutive expression of systemic acquired resistance (sar). this single recessive mutation also leads to spontaneous expression of chlorotic lesions and reduced trichome development. the cpr5 plants were found to be constitutively resistant to two virulent pathogens, pseudomonas syringae pv maculicola es4326 and peronospora parasitica noco2; to have endogenous expression of the pathogenesis-related gene 1 (pr-1); and to have an elevated level o ... | 1997 | 9338960 |
| enhanced tolerance to bacterial pathogens caused by the transgenic expression of barley lipid transfer protein ltp2. | purified lipid transfer protein ltp2 from barley applied on tobacco leaves eliminated symptoms caused by infiltration of pseudomonas syringae pv. tabaci 153. growth of the pathogen in leaves of transgenic tobacco plants was retarded when compared with non-transformed controls. the percentage of inoculation points that showed necrotic lesions was greatly reduced in transgenic tobacco (17-38% versus 78%) and the average size of these lesions was 61-81% that of control. the average total lesion are ... | 1997 | 9351251 |
| sequencing of regions downstream of adda (98 degrees) and citg (289 degrees) in bacillus subtilis. | the nucleotide sequence of 17.3 kbp downstream of adda (98 degrees) on the bacillus subtilis chromosome was determined. twenty putative orfs were identified. three of them coincided with known b. subtilis genes, adda, sbcd and wpra. the product of four other orfs showed similarity to sbcc of clostridium perfringens, coth of b. subtilis, 2-hydroxyhepta-2,4-diene-1,7-diodate isomerase of methanococcus jannaschi and a putative orf of pseudomonas syringae. in addition, a sequence of 7.6 kbp downstre ... | 1997 | 9353931 |
| the phte locus in the phaseolotoxin gene cluster has orfs with homologies to genes encoding amino acid transferases, the arac family of transcriptional factors, and fatty acid desaturases. | a cluster of genes involved in the production of phaseolotoxin, a phytotoxin produced by pseudomonas syringae pv. phaseolicola, contains eight (phta through phth) complementation groups (y. x. zhang, k. b. rowley, and s. s. patil, j. bacteriol., 175:6451-6458, 1993). in this study, sequencing of the region encompassing the phte locus revealed six putative open reading frames (orfs), each preceded by a putative ribosomal binding site, and all oriented in the same direction. reverse transcription- ... | 1997 | 9353942 |
| specific binding of the syringolide elicitors to a soluble protein fraction from soybean leaves. | syringolides are glycolipid elicitors produced by gram-negative bacteria expressing pseudomonas syringae avirulence gene d. the syringolides mediate gene-for-gene complementarity, inducing the hypersensitive response only in soybean plants carrying the rpg4 disease resistance gene. a site(s) for 125i-syringolide 1 was detected in the soluble protein fraction from soybean leaves, but no evidence for ligand-specific binding to the microsomal fraction was obtained. the kd value for syringolide 1 bi ... | 1997 | 12237390 |
| gene-expression patterns and levels of jasmonic acid in rice treated with the resistance inducer 2,6-dichloroisonicotinic acid. | acquired disease resistance can be induced in rice (oryza sativa) by a number of synthetic or natural compounds, but the molecular mechanisms behind the phenomenon are poorly understood. one of the synthetic inducers of resistance, 2,6-dichloroisonicotinic acid (ina), efficiently protected rice leaves from infection by the rice blast fungus magnaporthe grisea (hebert) barr. a comparison of gene-expression patterns in plants treated with ina versus plants inoculated with the compatible pathogen m ... | 1997 | 12223792 |
| salicylic acid is needed in hypersensitive cell death in soybean but does not act as a catalase inhibitor. | the function of salicylic acid (sa) in hypersensitive cell death was studied in a soybean (glycine max)-pseudomonas syringae pv glycinea system. the infection of cell cultures with bacteria leads to a hypersensitive reaction (hr), which is dependent on an appropriate avirulence gene and on low concentrations of sa. the requirement for sa is essential for a process shortly before the onset of the hr-caused cell death 5 to 6 h after infection with bacteria. sa given 10 to 12 h after infection or p ... | 1997 | 12223807 |
| detection of new ethylene-producing bacteria, pseudomonas syringae pvs. cannabina and sesami, by pcr amplification of genes for the ethylene-forming enzyme. | abstract strains of pseudomonas syringae (78 strains and 43 pathovars) and other strains (79) of plant and insect origin were examined for the presence of the ethylene-forming enzyme gene (efe) by polymerase chain reaction (pcr) assay. the sequence of the efe gene of p. syringae pv. phaseolicola pk2 was used to design two primer sets for amplification of the gene. in addition to p.syringae pv. phaseolicola (the "kudzu strain") and p.syringae pv. glycinea, which were efficient ethylene producers, ... | 1997 | 18945017 |
| expression of an engineered cecropin gene cassette in transgenic tobacco plants confers disease resistance to pseudomonas syringae pv. tabaci. | abstract a chimeric gene fusion cassette, consisting of a secretory sequence from barley alpha-amylase joined to a modified cecropin (mb39) coding sequence and placed under control of the promoter and terminator from the potato proteinase inhibitor ii (piii) gene, was introduced into tobacco by agrobacterium-mediated transformation. transgenic and control plants reacted differently when inoculated with tobacco wildfire pathogen pseudomonas syringae pv. tabaci at various cell concentrations. with ... | 1997 | 18945103 |
| effects of specific expression of iaal gene in tobacco tapetum on pollen embryogenesis. | the indoleacetic-acid-lysine synthetase (iaal) gene from pseudomonas syringae subsp. savastanoi was fused to tobacco tapetum-specific expression promoter ta29, and introduced into tobacco. the expression pattern of this chimeric gene was studied, and the endogenous indoleacetic acid (iaa) levels in different organs were assayed. the results demonstrated that ta29 promoter was only able to direct the specific expression of iaal gene in transgenic tobacco anther, and resulted in the decrease of en ... | 1997 | 18762878 |
| specificity of induced resistance in the tomato, lycopersicon esculentum. | specificity in the induced responses of tomato foliage to arthropod herbivores was investigated. we distinguished between two aspects of specificity: specificity of effect (the range of organisms affected by a given induced response), and specificity of elicitation (ability of the plant to generate distinct chemical responses to different damage types). specificity of effect was investigated by examining the effect of restricted feeding by helicoverpa zea on the resistance of tomato plants to an ... | 1997 | 28307296 |
| elicitor-stimulated ion fluxes and o2- from the oxidative burst are essential components in triggering defense gene activation and phytoalexin synthesis in parsley. | fungal elicitor stimulates a multicomponent defense response in cultured parsley cells (petroselinum crispum). early elements of this receptor-mediated response are ion fluxes across the plasma membrane and the production of reactive oxygen species (ros), sequentially followed by defense gene activation and phytoalexin accumulation. omission of ca2+ from the culture medium or inhibition of elicitor-stimulated ion fluxes by ion channel blockers prevented the latter three reactions, all of which w ... | 1997 | 9114072 |
| biosynthesis of camalexin from tryptophan pathway intermediates in cell-suspension cultures of arabidopsis. | camalexin (3-thiazol-2'-yl-indole) is the principal phytoalexin that accumulates in arabidopsis after infection by fungi or bacteria. camalexin accumulation was detectable in arabidopsis cell-suspension cultures 3 to 5 h after inoculation with cochliobolus carbonum (race 1), and then increased rapidly from 7 to 24 h after inoculation. levels of radioactivity incorporated into camalexin during a 1.5-h pulse labeling with [14c]anthranilate also increased with time after fungal inoculation. the lev ... | 1998 | 9847113 |
| ozone sensitivity in hybrid poplar is correlated with a lack of defense-gene activation | ozone is a major gaseous pollutant thought to contribute to forest decline. although the physiological and morphological responses of forest trees to ozone have been well characterized, little is known about the molecular basis for these responses. our studies compared the response to ozone of ozone-sensitive and ozone-tolerant clones of hybrid poplar (populus maximowizii x populus trichocarpa) at the physiological and molecular levels. gas-exchange analyses demonstrated clear differences betwee ... | 1998 | 9847098 |
| the molecular mechanisms responsible for resistance in plant-pathogen interactions of the gene-for-gene type function more broadly than previously imagined. | 1998 | 9707538 | |
| differential expression of a novel gene in response to coronatine, methyl jasmonate, and wounding in the coi1 mutant of arabidopsis. | coronatine is a phytotoxin produced by some plant-pathogenic bacteria. it has been shown that coronatine mimics the action of methyl jasmonate (meja) in plants. meja is a plant-signaling molecule involved in stress responses such as wounding and pathogen attack. in arabidopsis thaliana, meja is essential for pollen grain development. the coi1 (for coronatine-insensitive) mutant of arabidopsis, which is insensitive to coronatine and meja, produces sterile male flowers and shows an altered respons ... | 1998 | 9501136 |
| relationship between co2 assimilation, photosynthetic electron transport, and active o2 metabolism in leaves of maize in the field during periods of low temperature | measurements of the quantum efficiencies of photosynthetic electron transport through photosystem ii (phipsii) and co2 assimilation (phico2) were made simultaneously on leaves of maize (zea mays) crops in the united kingdom during the early growing season, when chilling conditions were experienced. the activities of a range of enzymes involved with scavenging active o2 species and the levels of key antioxidants were also measured. when leaves were exposed to low temperatures during development, ... | 1998 | 9490760 |
| changes in salicylic acid and antioxidants during induced thermotolerance in mustard seedlings | heat-acclimation or salicylic acid (sa) treatments were previously shown to induce thermotolerance in mustard (sinapis alba l.) seedlings from 1.5 to 4 h after treatment. in the present study we investigated changes in endogenous sa and antioxidants in relation to induced thermotolerance. thirty minutes into a 1-h heat-acclimation treatment glucosylated sa had increased 5.5-fold and then declined during the next 6 h. increases in free sa were smaller (2-fold) but significant. changes in antioxid ... | 1998 | 9847121 |
| rapid reorganization of resistance gene homologues in cereal genomes. | we used conserved domains in the major class (nucleotide binding site plus leucine-rich repeat) of dicot resistance (r) genes to isolate related gene fragments via pcr from the monocot species rice and barley. peptide sequence comparison of dicot r genes and monocot r-like genes revealed shared motifs but provided no evidence for a monocot-specific signature. mapping of these genes in rice and barley showed linkage to genetically characterized r genes and revealed the existence of mixed clusters ... | 1998 | 9419382 |
| the biosynthesis of salicylic acid in potato plants | spraying potato (solanum tuberosum l.) leaves with arachidonic acid (aa) at 1500 &mgr;g ml-1 led to a rapid local synthesis of salicylic acid (sa) and accumulation of a sa conjugate, which was shown to be 2-o-beta-glucopyranosylsalicylic acid. radiolabeling studies with untreated leaves showed that sa was synthesized from phenylalanine and that both cinnamic and benzoic acid were intermediates in the biosynthesis pathway. using radiolabeled phenylalanine as a precursor, the specific activity of ... | 1998 | 9662552 |
| systemin potentiates the oxidative burst in cultured tomato cells | plants that have been wounded by insects or other herbivores may be more susceptible to infection by adventitious microbes. wound-induced signal molecules, which serve to induce responses in the plant that retard further feeding, might also act to prepare a plant for possible pathogen attack. we have examined the effect of a wound-generated systemic messenger (systemin) on a pathogen-stimulated defense-response marker, the oxidative burst. we observed that neither systemin nor its inactive analo ... | 1998 | 9662546 |
| parallel changes in h2o2 and catalase during thermotolerance induced by salicylic acid or heat acclimation in mustard seedlings | spraying mustard (sinapis alba l.) seedlings with salicylic acid (sa) solutions between 10 and 500 &mgr;m significantly improved their tolerance to a subsequent heat shock at 55 degreesc for 1.5 h. the effects of sa were concentration dependent, with higher concentrations failing to induce thermotolerance. the time course of thermotolerance induced by 100 &mgr;m sa was similar to that obtained with seedlings acclimated at 45 degreesc for 1 h. we examined the hypothesis that induced thermotoleran ... | 1998 | 9536052 |
| directed changes in the number of double-stranded rna genomic segments in bacteriophage phi6. | bacteriophage phi6 has a genome of three segments of double-stranded rna. the segments are designated s, m, and l. each segment has a unique packaging site, pac, near the 5' end of the plus strand. the plus strands of the segments are normally packaged in the order s, m, l. chimeras of segment m and s in which segment m is at the 5' end of the plus strand can be stably incorporated into the virion; however, an independent segment s must be included along with normal segment l, even if it contain ... | 1998 | 9520468 |
| characterization of a 34-kda soybean binding protein for the syringolide elicitors. | syringolides are water-soluble, low-molecular-weight elicitors that trigger defense responses in soybean cultivars carrying the rpg4 disease-resistance gene but not in rpg4 cultivars. 125i-syringolide 1 previously was shown to bind to a soluble protein(s) in extracts from soybean leaves. a 34-kda protein that accounted for 125i-syringolide 1 binding activity was isolated with a syringolide affinity-gel column. partial sequences of internal peptides of the 34-kda protein were identical to p34, a ... | 1998 | 9501258 |
| organization of an arabidopsis thaliana gene cluster on chromosome 4 including the rps2 gene, in the brassica nigra genome. | genetic and physical maps, consisting of a large number of dna markers for arabidopsis thaliana chromosomes, represent excellent tools to determine the organization of related genomes such as those of brassica. in this paper we report the chromosomal localization and physical analysis by pulsed-field gel electrophoresis (pfge) of a well-defined gene complex of a. thaliana in the brassica nigra genome (b genome n=8). this complex is approximately 30 kb in length in a. thaliana and contains a clus ... | 1998 | 24710886 |
| syntheses and potato tuber-inducing activity of coronafacic acid analogues. | coronafacic acid (1) is an acid component of coronatine, and has been isolated from several pathovars of pseudomonas syringae. syntheses of c6-non- and c6-alkyl-substituted analogues of 1 were accomplished via intramolecular 1,6-conjugate addition as the key step. among them, 1 and four c6-alkyl-substituted analogues exhibited potato tuber-inducing activity, but the c6-non-substituted analogue did not. it was revealed that a certain length of the c6-alkyl group was necessary to exhibit activity. | 1998 | 27392555 |
| identification of tomato leaf factors that activate toxin gene expression in pseudomonas syringae pv. tomato dc3000. | abstract coronatine is a non-host-specific chlorosis-inducing phytotoxin produced by the tomato and crucifer pathogen pseudomonas syringae pv. tomato dc3000. how the chromosomal gene cluster controlling toxin synthesis in this strain is regulated in planta is unknown. ice nucleation-active cor:inaz marker-exchange derivatives of strain dc3000 were used to determine coronatine gene expression in various host and nonhost plants and in a minimal medium supplemented with selected tomato plant consti ... | 1998 | 18944822 |
| occurrence of indole-3-acetic acid-producing bacteria on pear trees and their association with fruit russet. | abstract a relatively high percentage of epiphytic bacteria on pear leaf and fruit surfaces had the ability to produce indole-3-acetic acid (iaa) in culture media supplemented with tryptophan. while over 50% of the strains produced at least small amounts of iaa in culture, about 25% of the strains exhibited high iaa production as evidenced by both colorimetric and high-performance liquid chromatography analysis of culture supernatants. a majority of the strains that produced high amounts of iaa ... | 1998 | 18944847 |
| mixtures of plant growth-promoting rhizobacteria enhance biological control of multiple cucumber pathogens. | abstract plant growth-promoting rhizobacteria (pgpr) strains inr7 (bacillus pumilus), gb03 (bacillus subtilis), and me1 (curtobacterium flaccumfaciens) were tested singly and in combinations for biological control against multiple cucumber pathogens. investigations under greenhouse conditions were conducted with three cucumber pathogens-colletotrichum orbiculare (causing anthracnose), pseudomonas syringae pv. lachrymans (causing angular leaf spot), and erwinia tracheiphila(causing cucurbit wilt ... | 1998 | 18944848 |
| a conjugative plasmid carrying the efe gene for the ethylene-forming enzyme isolated from pseudomonas syringae pv. glycinea. | abstract previous work suggested that the efe gene encoding the ethylene-forming enzyme was present in the plasmids of three pathovars of pseudomonas syringae including glycinea, phaseolicola (kudzu strains), and cannabina. however, no direct evidence to support this assumption had been presented. in the current study, we isolated the conjugative plasmid harboring the efe gene (ethylene plasmid) designated peth2 from p. syringae pv. glycinea maff301683. peth2 was detected by southern blot hybrid ... | 1998 | 18944855 |
| description of the bacterium causing blight of leek as pseudomonas syringae pv. porri (pv. nov.). | abstract forty bacterial strains isolated from leek blight (allium porrum) in france and other countries were studied by conventional biochemical methods, serological reactions, numerical taxonomy, dna-dna hybridization, and ice nucleation activity, as well as by pathogenicity on leek and other host plants. they were compared with reference strains of pseudomonas, mainly pathotype strains of p. syringae pathovars and strains of p. syringae pv. syringae isolated from various host plants including ... | 1998 | 18944892 |
| compost and compost water extract-induced systemic acquired resistance in cucumber and arabidopsis. | abstract a biocontrol agent-fortified compost mix, suppressive to several diseases caused by soilborne plant pathogens, induced systemic acquired resistance (sar) in cucumber against anthracnose caused by colletotrichum orbiculare and in arabidopsis against bacterial speck caused by pseudomonas syringae pv. maculicola kd4326. a peat mix conducive to soilborne diseases did not induce sar. the population size of p. syringae pv. maculicola kd4326 was significantly lower in leaves of arabidopsis pla ... | 1998 | 18944926 |
| bacterial apical necrosis of mango in southern spain: a disease caused by pseudomonas syringae pv. syringae. | abstract a necrotic bacterial disease of mango trees (mangifera indica) in spain affecting buds, leaves, and stems is described for the first time. necrosis of flower and vegetative buds on commercial trees during winter dormancy was the most destructive symptom of the disease. the apical necrosis is caused by pseudomonas syringae, which was always isolated from mango trees with disease symptoms. of 95 bacterial strains isolated from symptomatic tissues and characterized from 1992 to 1997, over ... | 1998 | 18944933 |
| glucosylation of salicylic acid in nicotiana tabacum cv. xanthi-nc. | abstract salicylic acid (sa) is a key regulatory component of disease resistance in plants. in tobacco mosaic virus (tmv)-inoculated tobacco (nicotiana tabacum cv. xanthi-nc nn genotype), newly synthesized sa is converted primarily to sa 2-o-beta-d-glucoside (sag) and glucosyl salicylate (gs), a relatively minor metabolite. similar patterns in the formation of gs and sag were observed in tobacco inoculated with pseudomonas syringae pv. phaseolicola, suggesting the accumulation of two glucosylate ... | 1998 | 18944942 |
| insertion sequences. | insertion sequences (iss) constitute an important component of most bacterial genomes. over 500 individual iss have been described in the literature to date, and many more are being discovered in the ongoing prokaryotic and eukaryotic genome-sequencing projects. the last 10 years have also seen some striking advances in our understanding of the transposition process itself. not least of these has been the development of various in vitro transposition systems for both prokaryotic and eukaryotic e ... | 1998 | 9729608 |
| replication and control of circular bacterial plasmids. | an essential feature of bacterial plasmids is their ability to replicate as autonomous genetic elements in a controlled way within the host. therefore, they can be used to explore the mechanisms involved in dna replication and to analyze the different strategies that couple dna replication to other critical events in the cell cycle. in this review, we focus on replication and its control in circular plasmids. plasmid replication can be conveniently divided into three stages: initiation, elongati ... | 1998 | 9618448 |
| biology of moderately halophilic aerobic bacteria. | the moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. the property of halophilism is widespread within the bacterial domain. bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. complex mechanisms of ... | 1998 | 9618450 |
| superoxide dismutase in arabidopsis: an eclectic enzyme family with disparate regulation and protein localization. | a number of environmental stresses can lead to enhanced production of superoxide within plant tissues, and plants are believed to rely on the enzyme superoxide dismutase (sod) to detoxify this reactive oxygen species. we have identified seven cdnas and genes for sod in arabidopsis. these consist of three cuznsods (csd1, csd2, and csd3), three fesods (fsd1, fsd2, and fsd3), and one mnsod (msd1). the chromosomal location of these seven sod genes has been established. to study this enzyme family, a ... | 1998 | 9765550 |
| chlorosis-inducing products from pseudomonas syringae pathovars: new n-coronafacoyl compounds. | liquid cultures of pseudomonas syringae pv. tomato strains that also produced the phytotoxin coronatine, were found to have a new chlorosis-inducing activity, not previously described. bioassay-guided fractionation and hplc analysis revealed two new peaks that were chlorosis-inducing on leaves of bean plants. mass spectrometry and nmr analyses of the compounds led to the derivation of their structures as coronafacoyl-l-serine and coronafacoyl-l-threonine, respectively. the amino acid c-2 configu ... | 1998 | 11711068 |
| the two-component regulators gacs and gaca influence accumulation of the stationary-phase sigma factor sigmas and the stress response in pseudomonas fluorescens pf-5. | three global regulators are known to control antibiotic production by pseudomonas fluorescens. a two-component regulatory system comprised of the sensor kinase gacs (previously called apda or lema) and gaca, a member of the fixj family of response regulators, is required for antibiotic production. a mutation in rpos, which encodes the stationary-phase sigma factor sigmas, differentially affects antibiotic production and reduces the capacity of stationary-phase cells of p. fluorescens to survive ... | 1998 | 9852008 |
| the arabidopsis thaliana rpm1 disease resistance gene product is a peripheral plasma membrane protein that is degraded coincident with the hypersensitive response. | disease resistance in plants is often controlled by a gene-for-gene mechanism in which avirulence (avr) gene products encoded by pathogens are specifically recognized, either directly or indirectly, by plant disease resistance (r) gene products. members of the nbs-lrr class of r genes encode proteins containing a putative nucleotide binding site (nbs) and carboxyl-terminal leucine-rich repeats (lrrs). generally, nbs-lrr proteins do not contain predicted transmembrane segments or signal peptides, ... | 1998 | 9861059 |
| characterization of the rice pathogen-related protein rir1a and regulation of the corresponding gene. | in rice (oryza sativa l.), local acquired resistance against pyricularia oryzae (cav.), the causal agent of rice blast, can be induced by a preinoculation with the non-host pathogen pseudomonas syringae pv. syringae. we have cloned a cdna (rir1a) and a closely related gene (rir1b) corresponding to transcripts that accumulate in leaf tissue upon inoculation with p. syringae pv. syringae. the cdna encodes a putative 107 amino acid protein, rir1a, that exhibits a putative signal peptide cleavage si ... | 1998 | 9747803 |
| resistance to tellurite as a selection marker for genetic manipulations of pseudomonas strains. | resistance to the toxic compound potassium tellurite (telr) has been employed as a selection marker built into a set of transposon vectors and broad-host-range plasmids tailored for genetic manipulations of pseudomonas strains potentially destined for environmental release. in this study, the activated telr determinants encoded by the cryptic telab genes of plasmid rk2 were produced, along with the associated kila gene, as dna cassettes compatible with cognate vectors. in one case, the telr dete ... | 1998 | 9758838 |
| efficacy of syringomycin e in a murine model of vaginal candidiasis. | syringomycin e (sr-e), a new antifungal produced by the bacterium pseudomonas syringae pv. syringae, was evaluated in a murine vaginal candidiasis model. in one study, mice were treated intravaginally b.i.d. for 4 days with drug carrier, sr-e 2% in either peg-400 or peg-ointment, or 1% clotrimazole as a positive control. quantitative vaginal cultures were taken prior to treatment on day 1 and on days 5, 6, and 7. both formulations showed a reduction of yeast colonization in the vaginas on day 5 ... | 1998 | 9766466 |
| mutational analysis of the role of nucleoside triphosphatase p4 in the assembly of the rna polymerase complex of bacteriophage phi6. | bacteriophage phi6 is a complex enveloped double-stranded rna virus with a segmented genome and replication strategy quite similar to that of the reoviridae. an in vitro packaging and replication system using purified components is available. the positive-polarity genomic segments are translocated into a preformed polymerase complex (procapsid) particle. this particle is composed of four proteins: the shell-forming protein p1, the rna polymerase p2, and two proteins active in packaging. protein ... | 1998 | 9811745 |
| physiological diversity of the rhizosphere diazotroph assemblages of selected salt marsh grasses. | rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. this geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these o ... | 1998 | 9797277 |
| biodegradation of phosphonomycin by rhizobium huakuii pmy1. | the biodegradation by rhizobium huakuii pmy1 of up to 10 mm phosphonomycin as a carbon, energy, and phosphorus source with accompanying p(i) release is described. this biodegradation represents a further mechanism of resistance to this antibiotic and a novel, phosphate-deregulated route for organophosphonate metabolism by rhizobium spp. | 1998 | 9435089 |
| homology and functional similarity of an hrp-linked pathogenicity locus, dspef, of erwinia amylovora and the avirulence locus avre of pseudomonas syringae pathovar tomato. | the "disease-specific" (dsp) region next to the hrp gene cluster of erwinia amylovora is required for pathogenicity but not for elicitation of the hypersensitive reaction. a 6.6-kb apparent operon, dspef, was found responsible for this phenotype. the operon contains genes dspe and dspf and is positively regulated by hrpl. a blast search revealed similarity in the dspe gene to a partial sequence of the avre locus of pseudomonas syringae pathovar tomato. the entire avre locus was sequenced. homolo ... | 1998 | 9448330 |
| environmental regulation of salmonella typhi invasion-defective mutants. | salmonella typhi is the etiologic agent of human typhoid. during infection, s. typhi adheres to and invades epithelial and m cells that line the distal ileum. to survive in the human host, s. typhi must overcome numerous complex extracellular and intracellular environments. since relatively little is known about s. typhi pathogenesis, studies were initiated to identify s. typhi genes involved in the early steps of interaction with the host and to evaluate the environmental regulation of these ge ... | 1998 | 9453627 |
| curli fibers are highly conserved between salmonella typhimurium and escherichia coli with respect to operon structure and regulation. | mouse-virulent salmonella typhimurium strains sr-11 and atcc 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by western blot analysis and electron microscopy. concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye congo red (called the rdar morphotype). cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgba(c) and csgdefg, from s. typhimurium sr- ... | 1998 | 9457880 |
| a cold-adapted lipase of an alaskan psychrotroph, pseudomonas sp. strain b11-1: gene cloning and enzyme purification and characterization. | a psychrotrophic bacterium producing a cold-adapted lipase upon growth at low temperatures was isolated from alaskan soil and identified as a pseudomonas strain. the lipase gene (lipp) was cloned from the strain and sequenced. the amino acid sequence deduced from the nucleotide sequence of the gene (924 bp) corresponded to a protein of 308 amino acid residues with a molecular weight of 33,714. lipp also has consensus motifs conserved in other cold-adapted lipases, i.e., lipase 2 from antarctic m ... | 1998 | 9464382 |
| identification of bacterial isolates obtained from intestinal contents associated with 12,000-year-old mastodon remains. | mastodon (mammut americanum) remains unearthed during excavation of ancient sediments usually consist only of skeletal material, due to postmortem decomposition of soft tissues by microorganisms. two recent excavations of skeletal remains in anoxic sediments in ohio and michigan, however, have uncovered organic masses which appear to be remnants of the small and large intestines, respectively. macrobotanical examinations of the composition of these masses revealed assemblages of plant material r ... | 1998 | 9464403 |
| ethylene-insensitive tobacco lacks nonhost resistance against soil-borne fungi. | enhanced ethylene production is an early response of plants to pathogen attack and has been associated with both resistance and susceptibility to disease. tobacco plants were transformed with the mutant etr1-1 gene from arabidopsis, conferring dominant ethylene insensitivity. besides lacking known ethylene responses, these transformants (tetr) did not slow growth when contacting neighboring plants, hardly expressed defense-related basic pathogenesis-related proteins, and developed spontaneous st ... | 1998 | 9465120 |
| a major outer membrane protein of rahnella aquatilis functions as a porin and root adhesin. | a 38-kda major outer membrane protein (omp) was isolated from the nitrogen-fixing enterobacterium rahnella aquatilis cf3. this protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60 degrees c. single channel experiments showed that this major omp of r. aquatilis cf3 is able to form pores in the planar lipid membrane. two oligonucleotides encoding the n-terminal portion of the 38-kda omp and c-terminal portion of ompc were used to amplify the 38-kd ... | 1998 | 9473046 |
| phosphorylation-independent activity of the response regulators algb and algr in promoting alginate biosynthesis in mucoid pseudomonas aeruginosa. | overproduction of the capsular polysaccharide alginate appears to confer a selective advantage for pseudomonas aeruginosa in the lungs of cystic fibrosis patients. the regulators algb and algr, which are both required as positive activators in alginate overproduction, have homology with the regulator class of two-component environmental responsive proteins which coordinate gene expression through signal transduction mechanisms. signal transduction in this class of proteins generally occurs via a ... | 1998 | 9473053 |
| isolation of new arabidopsis mutants with enhanced disease susceptibility to pseudomonas syringae by direct screening. | to identify plant defense components that are important in restricting the growth of virulent pathogens, we screened for arabidopsis mutants in the accession columbia (carrying the transgene bgl2-gus) that display enhanced disease susceptibility to the virulent bacterial pathogen pseudomonas syringae pv. maculicola (psm) es4326. among six (out of a total of 11 isolated) enhanced disease susceptibility (eds) mutants that were studied in detail, we identified one allele of the previously described ... | 1998 | 9611172 |
| the hrpc and hrpn operons of erwinia chrysanthemi ec16 are flanked by plca and homologs of hemolysin/adhesin genes and accompanying activator/transporter genes. | the hrpc operon of erwinia chrysanthemi ec16 encodes five genes conserved in erwinia amylovora and pseudomonas syringae. mutagenesis indicated that hrcc is required for elicitation of the hypersensitive reaction in tobacco leaves. the unexpected presence of plca and homologs of hemolysin/activator genes in the regions flanking the hrcc and hrpn operons is reported. | 1998 | 9612954 |
| the myristylation motif of pto is not required for disease resistance. | the tomato pto kinase confers resistance to bacterial speck disease caused by strains of pseudomonas syringae pv. tomato that express the avirulence gene avrpto. pto contains a putative myristylation site at its amino terminus that was hypothesized to play a role in localizing pto in the plant cell. site-directed mutagenesis was used to change the invariant glycine residue in the myristylation motif to an alanine. transgenes encoding the mutant pto(g2a) and wild-type pto were placed behind the c ... | 1998 | 9612955 |
| type iii protein secretion systems in bacterial pathogens of animals and plants. | various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. it is becoming increasingly clear that these so-called type iii secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. accordingly, some type iii secretion systems are activat ... | 1998 | 9618447 |
| surface display of zymomonas mobilis levansucrase by using the ice-nucleation protein of pseudomonas syringae. | the ice-nucleation protein (inp) is a glycosyl phosphatidylinositol-anchored outer membrane protein found in some gram-negative bacteria. using pseudomonas syringae inp as an anchoring motif, we investigated the functional display of a foreign protein, zymomonas mobilis levansucrase (levu), on the surface of escherichia coli. the cells expressing inp-levu were found to retain both the ice-nucleation and whole-cell levansucrase enzyme activities, indicating the functional expression of inp-levu h ... | 1998 | 9624691 |
| identification of the gene encoding the tryptophan synthase beta-subunit from chlamydomonas reinhardtii. | we report the isolation of a chlamydomonas reinhardtii cdna that encodes the beta-subunit of tryptophan synthase (tsb). this cdna was cloned by functional complementation of a trp-operon-deleted strain of escherichia coli. hybridization analysis indicated that the gene exists in a single copy. the predicted amino acid sequence showed the greatest identity to tsb polypeptides from other photosynthetic organisms. with the goal of identifying mutations in the gene encoding this enzyme, we isolated ... | 1998 | 9625698 |
| use of a new tetrazolium-based assay to study the production of superoxide radicals by tobacco cell cultures challenged with avirulent zoospores of phytophthora parasitica var nicotianae | the relationship between the production of reactive oxygen species and the hypersensitive response (hr) of tobacco (nicotiana tabacum l. ) toward an incompatible race of the oomycete phytophthora parasitica var nicotianae has been investigated. a new assay for superoxide radical (o2-) production based on reduction of the tetrazolium dye sodium,3'-(1-[phenylamino-carbonyl]-3, 4-tetrazolium)-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (xtt) has enabled the quantitative estimation of perhy ... | 1998 | 9625702 |
| correlation between binding affinity and necrosis-inducing activity of mutant avr9 peptide elicitors. | the race-specific peptide elicitor avr9 of the fungus cladosporium fulvum induces a hypersensitive response only in tomato (lycopersicon esculentum) plants carrying the complementary resistance gene cf-9 (moneymaker-cf9). a binding site for avr9 is present on the plasma membranes of both resistant and susceptible tomato genotypes. we used mutant avr9 peptides to determine the relationship between elicitor activity of these peptides and their affinity to the binding site in the membranes of tomat ... | 1998 | 9625714 |
| a race-specific insertion of transposable element is801 in pseudomonas syringae pv. phaseolicola. | the isolation and cloning of a random amplified polymorphic dna-polymerase chain reaction (rapd-pcr) band specific for pseudomonas syringae pv. phaseolicola race 1 allowed us to design a pair of primers that amplify 1.2-kb race 1-specific and 2.7-kb race 2-specific fragments, providing a rapid method for the identification of races by standard pcr methods. restriction analysis revealed identical endonuclease sites in both fragments but the race 2 fragment contains a 1.5-kb insertion, identified ... | 1998 | 9574509 |
| defense activation and enhanced pathogen tolerance induced by h2o2 in transgenic tobacco. | transgenic tobacco deficient in the h2o2-removing enzyme catalase (cat1as) was used as an inducible and noninvasive system to study the role of h2o2 as an activator of pathogenesis-related (pr) proteins in plants. excess h2o2 in cat1as plants was generated by simply increasing light intensities. sustained exposure of cat1as plants to excess h2o2 provoked tissue damage, stimulated salicylic acid and ethylene production, and induced the expression of acidic and basic pr proteins with a timing and ... | 1998 | 9576968 |
| biosynthesis and regulation of coronatine, a non-host-specific phytotoxin produced by pseudomonas syringae. | many p. syringae pathovars are known to produce low-molecular-weight, diffusible toxins in infected host plants. these phytotoxins reproduce some of the symptoms of the relevant bacterial disease and are effective at very low concentrations. phytotoxins generally enhance the virulence of the p. syringae pathovar which produces them, but are not required for pathogenesis. genes encoding phytotoxin production have been identified and cloned from several p. syringae pathovars. with the exception of ... | 1998 | 9594652 |
| uncoupling pr gene expression from npr1 and bacterial resistance: characterization of the dominant arabidopsis cpr6-1 mutant. | in arabidopsis, npr1 mediates the salicylic acid (sa)-induced expression of pathogenesis-related (pr) genes and systemic acquired resistance (sar). here, we report the identification of another component, cpr 6, that may function with npr1 in regulating pr gene expression. the dominant cpr 6-1 mutant expresses the sa/npr1-regulated pr genes (pr-1, bgl 2, and pr-5) and displays enhanced resistance to pseudomonas syringae pv maculicola es4326 and peronospora parasitica noco2 in the absence of sar ... | 1998 | 9548982 |
| expression of carboxymethylcellulase on the surface of escherichia coli using pseudomonas syringae ice nucleation protein. | ice-nucleation protein (inp), an outer membrane protein from pseudomonas syringae, is able to catalyze the ice crystal formation of supercooled water. it was exploited for anchoring of bacillus subtilis carboxymethylcellulase (cmcase) on the surface of escherichia coli. a surface anchoring vector, pginp21m, was created that contains the multicloning sites including bamhi, smai and ecori at the end of the 3' flanking region encoding the c-terminus of inp instead of the stop codon for subcloning t ... | 1998 | 9549104 |
| salmonella typhimurium encodes an sdia homolog, a putative quorum sensor of the luxr family, that regulates genes on the virulence plasmid. | quorum sensing is a phenomenon in which bacteria sense and respond to their own population density by releasing and sensing pheromones. in gram-negative bacteria, quorum sensing is often performed by the luxr family of transcriptional regulators, which affect phenotypes as diverse as conjugation, bioluminescence, and virulence gene expression. the gene encoding one luxr family member, named sdia (suppressor of cell division inhibition), is present in the escherichia coli genome. in this report, ... | 1998 | 9495757 |
| ethylene regulates the susceptible response to pathogen infection in tomato. | ethylene evolution occurs concomitantly with the progression of disease symptoms in response to many virulent pathogen infections in plants. a tomato mutant impaired in ethylene perception-never ripe-exhibited a significant reduction in disease symptoms in comparison to the wild type after inoculations of both genotypes with virulent bacterial (xanthomonas campestris pv vesicatoria and pseudomonas syringae pv tomato) and fungal (fusarium oxysporum f sp lycopersici) pathogens. bacterial spot dise ... | 1998 | 9501111 |
| exopolysaccharide ii production is regulated by salt in the halotolerant strain rhizobium meliloti efb1. | the halotolerant strain rhizobium meliloti efb1 modifies the production of extracellular polysaccharides in response to salt. efb1 colonies grown in the presence of 0.3 m nacl show a decrease in mucoidy, and in salt-supplemented liquid medium this organism produces 40% less exopolysaccharides. we isolated transposon-induced mutant that, when grown in the absence of salt, had a colony morphology (nonmucoid) similar to the colony morphology of the wild type grown in the presence of salt. calcofluo ... | 1998 | 9501442 |
| growth phase and temperature influence promoter activity, transcript abundance, and protein stability during biosynthesis of the pseudomonas syringae phytotoxin coronatine. | the plant-pathogenic bacterium pseudomonas syringae pv. glycinea pg4180.n9 synthesizes high levels of the polyketide phytotoxin coronatine (cor) at 18 degrees c, whereas no detectable toxin is produced at 28 degrees c. previously, we reported that the temperature-sensitive activation of three promoters within the cor biosynthetic gene cluster might explain thermoregulation of cor biosynthesis. the present study was aimed at furthering our understanding of the transcriptional as well as the postt ... | 1998 | 9515901 |
| comparative biochemistry of the oxidative burst produced by rose and french bean cells reveals two distinct mechanisms | cultured cells of rose (rosa damascena) treated with an elicitor derived from phytophthora spp. and suspension-cultured cells of french bean (phaseolus vulgaris) treated with an elicitor derived from the cell walls of colletotrichum lindemuthianum both produced h2o2. it has been hypothesized that in rose cells h2o2 is produced by a plasma membrane nad(p)h oxidase (superoxide synthase), whereas in bean cells h2o2 is derived directly from cell wall peroxidases following extracellular alkalinizatio ... | 1998 | 9536055 |
| identification of a novel salmonella invasion locus homologous to shigella ipgde. | genes essential for salmonella typhimurium invasion have been localized to salmonella pathogenicity island 1 (spi1) on the chromosome. however, it is clear that other genes are required for the invasion process. mutations that abolish the spi1 invasion type iii secretion system do not significantly reduce invasion into chinese hamster ovary tissue culture cells. two invasion defective mutants were isolated by screening 2,500 tn10dtc insertion mutants of s. typhimurium in the tissue culture invas ... | 1998 | 9537377 |
| occurrence of thermoregulation of genes involved in coronatine biosynthesis among various pseudomonas syringae strains. | several pathovars of pseudomonas syringae produce the polyketide phytotoxin coronatine (cor). in the bacterial blight pathogen of soybean, p. syringae pv. glycinea pg4180, cor is produced at high levels at 18 degrees c whereas no toxin is synthesized at 28 degrees c. previously, activation of three promoters inside the cor biosynthetic gene cluster by a modified two-component regulatory system was shown to influence thermoregulation of cor biosynthesis. using phenotypic determination of cor synt ... | 1998 | 9542107 |
| antibiotic production by erwinia herbicola eh1087: its role in inhibition of erwinia amylovora and partial characterization of antibiotic biosynthesis genes. | mutants of erwinia herbicola eh1087 (ant-), which did not produce antibiotic activity against erwinia amylovora, the fire blight pathogen, were selected after tnphoa mutagenesis. in immature pear fruit ant- mutants grew at the same rate as wild-type strain eh1087 but did not suppress development of the disease caused by e. amylovora. these results indicated that antibiosis plays an important role in the suppression of disease by strain eh1087. all of the ant- mutations obtained were located in a ... | 1998 | 9572960 |
| ecophysiological and phylogenetic studies of nevskia ramosa in pure culture. | during the last 100 years, the neuston bacterium nevskia ramosa has been described several times. this bacterium forms conspicuous rosette-like microcolonies at the air-water interface. in this study, pure cultures of nevskia ramosa were obtained for the first time, from a bog lake (strain soe1, dsmz 11499t) and a freshwater ditch (strain ol1, dsmz 11500). the isolates showed special adaptations to life in the epineuston. they formed hydrophobic surface films with a dull appearance. n. ramosa is ... | 1998 | 9572968 |
| effect of bacterial distribution and activity on conjugal gene transfer on the phylloplane of the bush bean (phaseolus vulgaris). | conjugal plasmid transfer was examined on the phylloplane of bean (phaseolus vulgaris) and related to the spatial distribution pattern and metabolic activity of the bacteria. the donor (pseudomonas putida kt2442) harbored a derivative of the tol plasmid, which conferred kanamycin resistance and had the gfp gene inserted downstream of a lac promoter. a chromosomal insertion of laciq prevented expression of the gfp gene. the recipient (p. putida kt2440) had a chromosomal tetracycline resistance ma ... | 1998 | 9572970 |
| structures of homologous composite transposons carrying cbaabc genes from europe and north america. | is1071 is a class ii transposable element carrying a tnpa gene related to the transposase genes of the tn3 family. copies of is1071 that are conserved with more than 99% nucleotide sequence identity have been found as direct repeats flanking a remarkable variety of catabolic gene sequences worldwide. the sequences of chlorobenzoate catabolic transposons found on pbrc60 (tn5271) in niagara falls, n.y., and on pcpe3 in bologna, italy, show that these transposons were formed from highly homologous ... | 1998 | 9572977 |
| burkholderia cepacia produces a hemolysin that is capable of inducing apoptosis and degranulation of mammalian phagocytes. | burkholderia cepacia is an opportunistic pathogen that has become a major threat to individuals with cystic fibrosis (cf). in approximately 20% of patients, pulmonary colonization with b. cepacia leads to cepacia syndrome, a fatal fulminating pneumonia sometimes associated with septicemia. it has been reported that culture filtrates of clinically derived strains of b. cepacia are hemolytic. in this study, we have characterized a factor which contributes to this hemolytic activity and is secreted ... | 1998 | 9573086 |
| (methyl)ammonium transport in the nitrogen-fixing bacterium azospirillum brasilense. | an ammonium transporter of azospirillum brasilense was characterized. in contrast to most previously reported putative prokaryotic nh4+ transporter genes, a. brasilense amtb is not part of an operon with glnb or glnz which, in a. brasilense, encode nitrogen regulatory proteins pii and pz, respectively. sequence analysis predicts the presence of 12 transmembrane domains in the deduced amtb protein and classifies amtb as an integral membrane protein. nitrogen regulates the transcription of the amt ... | 1998 | 9573149 |
| different requirements for eds1 and ndr1 by disease resistance genes define at least two r gene-mediated signaling pathways in arabidopsis. | the arabidopsis genes eds1 and ndr1 were shown previously by mutational analysis to encode essential components of race-specific disease resistance. here, we examined the relative requirements for eds1 and ndr1 by a broad spectrum of resistance (r) genes present in three arabidopsis accessions (columbia, landsberg-erecta, and wassilewskija). we show that there is a strong requirement for eds1 by a subset of r loci (rpp2, rpp4, rpp5, rpp21, and rps4), conferring resistance to the biotrophic oomyc ... | 1998 | 9707643 |
| evidence for growth of strains of the plant epiphytic bacterium erwinia herbicola and transconjugation among the bacterial strains in guts of the silkworm bombyx mori. | growth of plant epiphytic bacteria erwinia herbicola and pseudomonas syringae in guts of the silkworm, bombyx mori, was studied. fifth instar silkworm larvae were fed artificial diets supplemented with these bacteria for 6 to 12 h followed by uncontaminated diets. at 1, 3, and 6 days after feeding, bacteria were isolated from insect guts and feces. a much larger population of e. herbicola was detected in the samples collected 3 and 6 days after the inoculation than in samples collected after 1 d ... | 1998 | 9709009 |
| pas, a novel protein required for protein secretion and attaching and effacing activities of enterohemorrhagic escherichia coli. | enterohemorrhagic escherichia coli (ehec) exhibits a pattern of localized adherence to host cells, with the formation of microcolonies, and induces a specific histopathological phenotype collectively known as the attaching and effacing lesion. the genes encoding the products responsible for this phenotype are located on a 35-kb pathogenicity island designated the locus of enterocyte effacement, which is also shared by enteropathogenic e. coli. we have identified an open reading frame (orf) which ... | 1998 | 9721271 |
| auxin production is a common feature of most pathovars of pseudomonas syringae. | we investigated indole-3-acetic acid (iaa) production by 57 pathovars of pseudomonas syringae and related species. most of those analyzed produced iaa, especially in the presence of tryptophan. eight strains produced high iaa concentrations in the absence of trp. the iaam and iaah genes of p. savastanoi pv. savastanoi were detected in a limited number of strains only, including the eight above-mentioned strains. thus, iaa synthesis in most assayed strains of p. syringae and related species does ... | 1998 | 9450337 |
| reactive oxygen intermediates mediate a systemic signal network in the establishment of plant immunity. | recognition of an avirulent pathogen stimulates an oxidative burst generating o2- and h2o2, and these reactive oxygen intermediates (rois) cue the induction of defense genes and cell death in the development of a restricted lesion. this localized hypersensitive response (hr) is accompanied by the development of systemic acquired resistance to virulent pathogens. here we show that inoculation of arabidopsis leaves with avirulent pseudomonas syringae induces secondary oxidative bursts in discrete ... | 1998 | 9529253 |
| characterization of the hrpc and hrprs operons of pseudomonas syringae pathovars syringae, tomato, and glycinea and analysis of the ability of hrpf, hrpg, hrcc, hrpt, and hrpv mutants to elicit the hypersensitive response and disease in plants. | the species pseudomonas syringae encompasses plant pathogens with differing host specificities and corresponding pathovar designations. p. syringae requires the hrp (type iii protein secretion) system, encoded by a 25-kb cluster of hrp and hrc genes, in order to elicit the hypersensitive response (hr) in nonhosts or to be pathogenic in hosts. dna sequence analysis of the hrpc and hrprs operons of p. syringae pv. syringae 61 (brown spot of beans), p. syringae pv. glycinea u1 (bacterial blight of ... | 1998 | 9721291 |
| negative regulation of hrp genes in pseudomonas syringae by hrpv. | mutations in the five hrp and hrc genes in the hrpc operon of the phytopathogen pseudomonas syringae pv. syringae 61 have different effects on bacterial interactions with host and nonhost plants. the hrcc gene within the hrpc operon encodes an outer membrane component of the hrp secretion system that is conserved in all type iii protein secretion systems and is required for most pathogenic phenotypes and for secretion of the hrpz harpin to the bacterial milieu. the other four genes (in order), h ... | 1998 | 9721292 |
| novel escherichia coli umud' mutants: structure-function insights into sos mutagenesis. | although it has been 10 years since the discovery that the escherichia coli umud protein undergoes a reca-mediated cleavage reaction to generate mutagenically active umud', the function of umud' has yet to be determined. in an attempt to elucidate the role of umud' in sos mutagenesis, we have utilized a colorimetric papillation assay to screen for mutants of a hydroxylamine-treated, low-copy-number umud' plasmid that are unable to promote sos-dependent spontaneous mutagenesis. using such an appr ... | 1998 | 9721309 |
| a response regulator of cyanobacteria integrates diverse environmental signals and is critical for survival under extreme conditions. | microorganisms must sense their environment and rapidly tune their metabolism to ambient conditions to efficiently use available resources. we have identified a gene encoding a response regulator, nblr, that complements a cyanobacterial mutant unable to degrade its light-harvesting complex (phycobilisome), in response to nutrient deprivation. cells of the nblr mutant (i) have more phycobilisomes than wild-type cells during nutrient-replete growth, (ii) do not degrade phycobilisomes during sulfur ... | 1998 | 9724820 |
| cloning, nucleotide sequence, and expression in escherichia coli of levansucrase genes from the plant pathogens pseudomonas syringae pv. glycinea and p. syringae pv. phaseolicola. | plant-pathogenic bacteria produce various extracellular polysaccharides (epss) which may function as virulence factors in diseases caused by these bacteria. the eps levan is synthesized by the extracellular enzyme levansucrase in pseudomonas syringae, erwinia amylovora, and other bacterial species. the lsc genes encoding levansucrase from p. syringae pv. glycinea pg4180 and p. syringae pv. phaseolicola ncppb 1321 were cloned, and their nucleotide sequences were determined. heterologous expressio ... | 1998 | 9726857 |
| contribution of indole-3-acetic acid production to the epiphytic fitness of erwinia herbicola | erwinia herbicola 299r produces large quantities of indole-3-acetic acid (iaa) in culture media supplemented with l-tryptophan. to assess the contribution of iaa production to epiphytic fitness, the population dynamics of the wild-type strain and an iaa-deficient mutant of this strain on leaves were studied. strain 299xyle, an isogenic iaa-deficient mutant of strain 299r, was constructed by insertional interruption of the indolepyruvate decarboxylase gene of strain 299r with the xyle gene, which ... | 1998 | 9726868 |
| linkage map of escherichia coli k-12, edition 10: the traditional map. | this map is an update of the edition 9 map by berlyn et al. (m. k. b. berlyn, k. b. low, and k. e. rudd, p. 1715-1902, in f. c. neidhardt et al., ed., escherichia coli and salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). it uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. the latter are included as ... | 1998 | 9729611 |
| yscb of yersinia pestis functions as a specific chaperone for yopn. | following contact with a eucaryotic cell, yersinia species pathogenic for humans (y. pestis, y. pseudotuberculosis, and y. enterocolitica) export and translocate a distinct set of virulence proteins (yope, yoph, yopj, yopm, and ypka) from the bacterium into the eucaryotic cell. during in vitro growth at 37 degrees c in the presence of calcium, yop secretion is blocked; however, in the absence of calcium, yop secretion is triggered. yop secretion occurs via a plasmid-encoded type iii, or "contact ... | 1998 | 9733695 |
| characterization of the dominant and rare members of a young hawaiian soil bacterial community with small-subunit ribosomal dna amplified from dna fractionated on the basis of its guanine and cytosine composition. | the small-subunit ribosomal dna (rdna) diversity was found to be very high in a hawaiian soil community that might be expected to have lower diversity than the communities in continental soils because the hawaiian soil is geographically isolated and only 200 years old, is subjected to a constant climate, and harbors low plant diversity. since an underlying community structure could not be revealed by analyzing the total eubacterial rdna, we first fractionated the dna on the basis of guanine-plus ... | 1998 | 9546163 |
| dna sequencing and analysis of the low-ca2+-response plasmid pcd1 of yersinia pestis kim5. | the low-ca2+-response (lcr) plasmid pcd1 of the plague agent yersinia pestis kim5 was sequenced and analyzed for its genetic structure. pcd1 (70,509 bp) has an incfiia-like replicon and a sopabc-like partition region. we have assigned 60 apparently intact open reading frames (orfs) that are not contained within transposable elements. of these, 47 are proven or possible members of the lcr, a major virulence property of human-pathogenic yersinia spp., that had been identified previously in one or ... | 1998 | 9746557 |