| identification of new secreted effectors in salmonella enterica serovar typhimurium. | a common theme in bacterial pathogenesis is the secretion of bacterial products that modify cellular functions to overcome host defenses. gram-negative bacterial pathogens use type iii secretion systems (ttsss) to inject effector proteins into host cells. the genes encoding the structural components of the type iii secretion apparatus are conserved among bacterial species and can be identified by sequence homology. in contrast, the sequences of secreted effector proteins are less conserved and a ... | 2005 | 16177297 |
| role of an alginate lyase for alginate transport in mucoid pseudomonas aeruginosa. | the opportunistic pathogen pseudomonas aeruginosa secretes a capsule-like polysaccharide called alginate that is important for evasion of host defenses, especially during chronic pulmonary disease of patients with cystic fibrosis (cf). most proteins for alginate biosynthesis are encoded by the 12-gene algd operon. interestingly, this operon also encodes algl, a lyase that degrades alginate. mutants lacking algg, algk, or algx, also encoded by the operon, synthesize alginate polymers that are dig ... | 2005 | 16177314 |
| homologues of insecticidal toxin complex genes in yersinia enterocolitica biotype 1a and their contribution to virulence. | yersinia enterocolitica is an enteric pathogen that consists of six biotypes: 1a, 1b, 2, 3, 4, and 5. strains of the latter five biotypes can carry a virulence plasmid, known as pyv, and several well-characterized chromosomally encoded virulence determinants. y. enterocolitica strains of biotype 1a lack the virulence-associated markers of pyv-bearing strains and were once considered to be avirulent. there is growing epidemiological, clinical, and experimental evidence, however, to suggest that s ... | 2005 | 16177365 |
| bacterial species specificity in prou osmoinducibility and nptii and lacz expression. | reporter gene-based transcriptional fusions are increasingly being used to address questions in microbial ecology, with constitutively expressed fusions enabling microbe tracking and inducible fusions reporting the presence of environmental signals. to more readily apply this technology to a variety of bacterial species, we examined species specificity in the expression of three promoters of interest. a comparison of two potentially constitutive promoters, each fused to the reporter gene gfp, sh ... | 2004 | 16179797 |
| pseudotrienic acids a and b, two bioactive metabolites from pseudomonas sp. mf381-iods. | bioassay-guided fractionation of the liquid culture broth of pseudomonas sp. mf381-iods yielded two new antimicrobial substances, identified as (2e,4e,6e)-9-[((2s,3r)-3-hydroxy-4-{[(3e,5e,7rs)-7-hydroxy-4-methylhexadeca-3,5-dienoyl]amino}-2-methylbutanoyl)amino]nona-2,4,6-trienoic acid and the tetradeca equivalent, named pseudotrienic acids a (1) and b (2), respectively. the compounds are prone to lactone formation, and their structures suggest them to be derived from ring opening of a macrolide ... | 2005 | 16180818 |
| repressor- and activator-type ethylene response factors functioning in jasmonate signaling and disease resistance identified via a genome-wide screen of arabidopsis transcription factor gene expression. | to identify transcription factors (tfs) involved in jasmonate (ja) signaling and plant defense, we screened 1,534 arabidopsis (arabidopsis thaliana) tfs by real-time quantitative reverse transcription-pcr for their altered transcript at 6 h following either methyl ja treatment or inoculation with the incompatible pathogen alternaria brassicicola. we identified 134 tfs that showed a significant change in expression, including many apetala2/ethylene response factor (ap2/erf), myb, wrky, and nac tf ... | 2005 | 16183832 |
| pseudomonas fluorescens and glomus mosseae trigger dmi3-dependent activation of genes related to a signal transduction pathway in roots of medicago truncatula. | plant genes induced during early root colonization of medicago truncatula gaertn. j5 by a growth-promoting strain of pseudomonas fluorescens (c7r12) have been identified by suppressive subtractive hybridization. ten m. truncatula genes, coding proteins associated with a putative signal transduction pathway, showed an early and transient activation during initial interactions between m. truncatula and p. fluorescens, up to 8 d after root inoculation. gene expression was not significantly enhanced ... | 2005 | 16183836 |
| bioactive metabolites from the fungus nectria galligena, the main apple canker agent in chile. | the phytopathogenic fungus nectria galligena bres. is the most common canker disease agent of hardwood trees. the terpenoids colletochlorin b, colletorin b, ilicicolin c, e, and f, as well as the phytotoxin alpha,beta-dehydrocurvularin have been isolated from liquid cultures of n. galligena obtained from the xylem of infected apple trees in central chile. ilicicolin c and f and alpha,beta-dehydrocurvularin were active against pseudomonas syringae with ic50 values of 28.5, 28.5, and 14.2 microg/m ... | 2005 | 16190620 |
| crystal structures of delta1-piperideine-2-carboxylate/delta1-pyrroline-2-carboxylate reductase belonging to a new family of nad(p)h-dependent oxidoreductases: conformational change, substrate recognition, and stereochemistry of the reaction. | delta(1)-piperideine-2-carboxylate/delta(1)-pyrroline-2-carboxylate reductase from pseudomonas syringae pv. tomato belongs to a novel sub-class in a large family of nad(p)h-dependent oxidoreductases distinct from the conventional mdh/ldh superfamily characterized by the rossmann fold. we have determined the structures of the following three forms of the enzyme: the unliganded form, the complex with nadph, and the complex with nadph and pyrrole-2-carboxylate at 1.55-, 1.8-, and 1.7-a resolutions, ... | 2005 | 16192274 |
| biosynthesis of active bacillus subtilis urease in the absence of known urease accessory proteins. | bacillus subtilis contains urease structural genes but lacks the accessory genes typically required for gtp-dependent incorporation of nickel. nevertheless, b. subtilis was shown to possess a functional urease, and the recombinant enzyme conferred low levels of nickel-dependent activity to escherichia coli. additional investigations of the system lead to the suggestion that b. subtilis may use unidentified accessory proteins for in vivo urease activation. | 2005 | 16199586 |
| role of the ssu and seu genes of corynebacterium glutamicum atcc 13032 in utilization of sulfonates and sulfonate esters as sulfur sources. | corynebacterium glutamicum atcc 13032 was found to be able to utilize a broad range of sulfonates and sulfonate esters as sulfur sources. the two gene clusters potentially involved in sulfonate utilization, ssud1cba and ssui-seuabc-ssud2, were identified in the genome of c. glutamicum atcc 13032 by similarity searches. while the ssu genes encode proteins resembling ssu proteins from escherichia coli or bacillus subtilis, the seu gene products exhibited similarity to the dibenzothiophene-degradin ... | 2005 | 16204527 |
| trichoderma mitogen-activated protein kinase signaling is involved in induction of plant systemic resistance. | the role of a mitogen-activated protein kinase (mapk) tmka in inducing systemic resistance in cucumber against the bacterial pathogen pseudomonas syringae pv. lacrymans was investigated by using tmka loss-of-function mutants of trichoderma virens. in an assay where trichoderma spores were germinated in proximity to cucumber roots, the mutants were able to colonize the plant roots as effectively as the wild-type strain but failed to induce full systemic resistance against the leaf pathogen. inter ... | 2005 | 16204544 |
| intracellular screen to identify metagenomic clones that induce or inhibit a quorum-sensing biosensor. | the goal of this study was to design and evaluate a rapid screen to identify metagenomic clones that produce biologically active small molecules. we built metagenomic libraries with dna from soil on the floodplain of the tanana river in alaska. we extracted dna directly from the soil and cloned it into fosmid and bacterial artificial chromosome vectors, constructing eight metagenomic libraries that contain 53,000 clones with inserts ranging from 1 to 190 kb. to identify clones of interest, we de ... | 2005 | 16204555 |
| production of an engineered killer peptide in nicotiana benthamiana by using a potato virus x expression system. | the decapeptide killer peptide (kp) derived from the sequence of a single-chain, anti-idiotypic antibody acting as a functional internal image of a microbicidal, broad-spectrum yeast killer toxin (kt) was shown to exert a strong microbicidal activity against human pathogens. with the aim to exploit this peptide to confer resistance to plant pathogens, we assayed its antimicrobial activity against a broad spectrum of phytopathogenic bacteria and fungi. synthetic kp exhibited antimicrobial activit ... | 2005 | 16204558 |
| [genetic diversity in pseudomonads associated with cereal cultures infected with basal bacteriosis]. | the genetic properties of 45 pseudomonad strains isolated from cereal cultures exhibiting symptoms of basal bacteriosis have been investigated. considerable genetic diversity has been demonstrated using dna fingerprints obtained by amplification with rep, eric, and box primers. restriction analysis of the 16s-23s internal transcribed spacer (its1) allowed the strains to be subdivided into two major groups. in a phylogenetic tree, the its1s of these groups fell into two clusters, which also inclu ... | 2005 | 16211859 |
| regulation of plant defense responses in arabidopsis by edr2, a ph and start domain-containing protein. | we have identified an arabidopsis mutant that displays enhanced disease resistance (edr2) to the biotrophic powdery mildew pathogen erysiphe cichoracearum. inhibition of fungal growth on edr2 mutant leaves occurred at a late stage of the infection process and coincided with formation of necrotic lesions approximately 5 days after inoculation. double-mutant analysis revealed that edr2-mediated resistance is suppressed by mutations that inhibit salicylic acid (sa)-induced defense signaling, includ ... | 2005 | 16212604 |
| a duplicated pair of arabidopsis ring-finger e3 ligases contribute to the rpm1- and rps2-mediated hypersensitive response. | the arabidopsis rpm1 protein confers resistance to disease caused by pseudomonas syringae strains delivering either the avrrpm1 or avrb type iii effector proteins into host cells. we characterized two closely related rpm1-interacting proteins, rin2 and rin3. rin2 and rin3 encode ring-finger type ubiquitin ligases with six apparent transmembrane domains and an ubiquitin-binding cue domain. rin2 and rin3 are orthologs of the mammalian autocrine motility factor receptor, a cytokine receptor localiz ... | 2005 | 16212605 |
| basal resistance against bacteria in nicotiana benthamiana leaves is accompanied by reduced vascular staining and suppressed by multiple pseudomonas syringae type iii secretion system effector proteins. | basal resistance in plants is induced by flagellin and several other common bacterial molecules and is implicated in the immunity of plants to most bacteria and other microbes. however, basal resistance can be suppressed by effector proteins that are injected by the type iii secretion system (ttss) of pathogens such as pseudomonas syringae. this study demonstrates that basal resistance in the leaves of nicotiana benthamiana is accompanied by reduced vascular flow into minor veins. reduced vascul ... | 2005 | 16212612 |
| comparative phylogenomics of the food-borne pathogen campylobacter jejuni reveals genetic markers predictive of infection source. | campylobacter jejuni is the predominant cause of bacterial gastroenteritis worldwide, but traditional typing methods are unable to discriminate strains from different sources that cause disease in humans. we report the use of genomotyping (whole-genome comparisons of microbes using dna microarrays) combined with bayesian-based algorithms to model the phylogeny of this major food-borne pathogen. in this study 111 c. jejuni strains were examined by genomotyping isolates from humans with a spectrum ... | 2005 | 16230626 |
| construction and analysis of a recombinant cyanobacterium expressing a chromosomally inserted gene for an ethylene-forming enzyme at the psbai locus. | the coding sequence of a gene for a pseudomonas syringae ethylene-forming enzyme was inserted at the psbai locus in a cyanobacterium, synechococcus elongatus pcc 7942 via rps12-mediated gene replacement. the recombinant strain photoautotrophically produced ethylene at 451 nl ml(-1) h(-1) od730(-1), but showed a depressed specific growth rate as well as a yellow-green phenotype indicating a severe metabolic stress. the rate of ethylene production in the recombinant culture decreased as a result o ... | 2003 | 16233410 |
| insights into genome plasticity and pathogenicity of the plant pathogenic bacterium xanthomonas campestris pv. vesicatoria revealed by the complete genome sequence. | the gram-negative plant-pathogenic bacterium xanthomonas campestris pv. vesicatoria is the causative agent of bacterial spot disease in pepper and tomato plants, which leads to economically important yield losses. this pathosystem has become a well-established model for studying bacterial infection strategies. here, we present the whole-genome sequence of the pepper-pathogenic xanthomonas campestris pv. vesicatoria strain 85-10, which comprises a 5.17-mb circular chromosome and four plasmids. th ... | 2005 | 16237009 |
| multiple and interconnected pathways for l-lysine catabolism in pseudomonas putida kt2440. | l-lysine catabolism in pseudomonas putida kt2440 was generally thought to occur via the aminovalerate pathway. in this study we demonstrate the operation of the alternative aminoadipate pathway with the intermediates d-lysine, l-pipecolate, and aminoadipate. the simultaneous operation of both pathways for the use of l-lysine as the sole carbon and nitrogen source was confirmed genetically. mutants with mutations in either pathway failed to use l-lysine as the sole carbon and nitrogen source, alt ... | 2005 | 16237033 |
| the incp island in the genome of brucella suis 1330 was acquired by site-specific integration. | an 18,228-bp region containing open reading frames predicted to be derived from the incp plasmid or phage ancestors is present in the genomes of brucella suis biovars 1 to 4, b. canis, b. neotomae, and strains isolated from marine mammals, but not in b. melitensis, b. abortus, b. ovis, and b. suis biovar 5. the presence of circular excision intermediates and the results of an analysis of sequenced bacterial genomes suggest that the region downstream of the guaa gene is a hotspot for site-specifi ... | 2005 | 16239585 |
| calmodulin-like proteins from arabidopsis and tomato are involved in host defense against pseudomonas syringae pv. tomato. | complex signal transduction pathways underlie the myriad plant responses to attack by pathogens. ca(2+) is a universal second messenger in eukaryotes that modulates various signal transduction pathways through stimulus-specific changes in its intracellular concentration. ca(2+)-binding proteins such as calmodulin (cam) detect ca(2+) signals and regulate downstream targets as part of a coordinated cellular response to a given stimulus. here we report the characterization of a tomato gene (apr134) ... | 2005 | 16240180 |
| oligomerization of sulfolobus solfataricus signature amidase is promoted by acidic ph and high temperature. | the recombinant amidase from the hyperthermophylic archaeon sulfolobus solfataricus (ssam) a signature amidase, was cloned, purified and characterized. the enzyme is active on a large number of aliphatic and aromatic amides over the temperature range 60-95 degrees c and at ph values between 4.0 and 9.5, with an optimum at ph 5.0. the recombinant enzyme is in the form of a dimer of about 110 kd that reversibly associates into an octamer in a ph-dependent reaction. the ph dependence of the state o ... | 2005 | 16243781 |
| ascorbic acid deficiency activates cell death and disease resistance responses in arabidopsis. | programmed cell death, developmental senescence, and responses to pathogens are linked through complex genetic controls that are influenced by redox regulation. here we show that the arabidopsis (arabidopsis thaliana) low vitamin c mutants, vtc1 and vtc2, which have between 10% and 25% of wild-type ascorbic acid, exhibit microlesions, express pathogenesis-related (pr) proteins, and have enhanced basal resistance against infections caused by pseudomonas syringae. the mutants have a delayed senesc ... | 2005 | 16244149 |
| increased calcium levels and prolonged shelf life in tomatoes expressing arabidopsis h+/ca2+ transporters. | here we demonstrate that fruit from tomato (lycopersicon esculentum) plants expressing arabidopsis (arabidopsis thaliana) h(+)/cation exchangers (cax) have more calcium (ca2+) and prolonged shelf life when compared to controls. previously, using the prototypical cax1, it has been demonstrated that, in yeast (saccharomyces cerevisiae) cells, cax transporters are activated when the n-terminal autoinhibitory region is deleted, to give an n-terminally truncated cax (scax), or altered through specifi ... | 2005 | 16244156 |
| analysis of the cdnas of hypothetical genes on arabidopsis chromosome 2 reveals numerous transcript variants. | in the fully sequenced arabidopsis (arabidopsis thaliana) genome, many gene models are annotated as "hypothetical protein," whose gene structures are predicted solely by computer algorithms with no support from either expressed sequence matches from arabidopsis, or nucleic acid or protein homologs from other species. in order to confirm their existence and predicted gene structures, a high-throughput method of rapid amplification of cdna ends (race) was used to obtain their cdna sequences from 1 ... | 2005 | 16244158 |
| [cloning and characterization of an harpin-encoding gene from xanthomonas axonopodis pv. glycines required for hypersensitive response on nonhost plant tobacco]. | an hpa1 gene was cloned into an expression vector, pet30a(+), from the genomic dna of xanthomonas axonopodis pv. glycines (xag), the causal agent of soybean bacterial pustule, with degenerated primers by polymerase amplification reaction (pcr). the gene product was extracted from the conjugate (bhr-3) of bl21 (des) with the recombined vector phr3 after the engineering strain was induced by iptg in lb medium. the sds-page gel showed that the gene product was 15.1kd. the product was heat-stable (1 ... | 2005 | 16245857 |
| evolution of mutational robustness in an rna virus. | mutational (genetic) robustness is phenotypic constancy in the face of mutational changes to the genome. robustness is critical to the understanding of evolution because phenotypically expressed genetic variation is the fuel of natural selection. nonetheless, the evidence for adaptive evolution of mutational robustness in biological populations is controversial. robustness should be selectively favored when mutation rates are high, a common feature of rna viruses. however, selection for robustne ... | 2005 | 16248678 |
| horizontal transfer of iturin a operon, itu, to bacillus subtilis 168 and conversion into an iturin a producer. | iturin a and its derivatives are lipopeptide antibiotics produced by bacillus subtilis and several closely related bacteria. three iturin group operons (i.e., iturin a, mycosubtilin, and bacillomycin d) of those antibiotic-producing strains have been cloned and sequenced thus far, strongly implying the horizontal transfer of these operons. to examine the nature of such horizontal transfer in terms of antibiotic production, a 42-kb region of the b. subtilis rb14 genome, which contains a complete ... | 2005 | 16251307 |
| natural variation in the arabidopsis response to the avirulence gene hoppsya uncouples the hypersensitive response from disease resistance. | the plant hypersensitive response (hr) is tightly associated with gene-for-gene resistance and has been proposed to function in containing pathogens at the invasion site. this tight association has made it difficult to unequivocally evaluate the importance of hr for plant disease resistance. here, hoppsya from pseudomonas syringae pv. syringae 61 is identified as a new avirulence gene for arabidopsis that triggers resistance in the absence of macroscopic hr. resistance to p. syringae pv. tomato ... | 2005 | 16255244 |
| extracytoplasmic function sigma factors in pseudomonas syringae. | genome analyses of the plant pathogens pseudomonas syringae pv. tomato dc3000, pv. syringae b728a and pv. phaseolicola 1448a reveal fewer extracytoplasmic function (ecf) sigma factors than in related pseudomonads with different lifestyles. we highlight the presence of a p. syringae-specific ecf sigma factor that is an interesting target for future studies because of its potential role in the adaptation of p. syringae to its specialized phytopathogenic lifestyle. | 2005 | 16257528 |
| novel virulence gene of pseudomonas syringae pv. tomato strain dc3000. | previously, we conducted a mutant screen of pseudomonas syringae pv. tomato strain dc3000 to identify genes that contribute to virulence on arabidopsis thaliana plants. here we describe the characterization of one mutant strain, db4h2, which contains a single tn5 insertion in pspto3576, an open reading frame that is predicted to encode a protein belonging to the tetr family of transcriptional regulators. we demonstrate that pspto3576 is necessary for virulence in dc3000 and designate the encoded ... | 2005 | 16267304 |
| reciprocal regulation of pyoluteorin production with membrane transporter gene expression in pseudomonas fluorescens pf-5. | pyoluteorin is a chlorinated polyketide antibiotic secreted by the rhizosphere bacterium pseudomonas fluorescens pf-5. genes encoding enzymes and transcriptional regulators involved in pyoluteorin production are clustered in the genome of pf-5. sequence analysis of genes adjacent to the known pyoluteorin biosynthetic gene cluster revealed the presence of an abc transporter system. we disrupted two putative abc transporter genes by inserting transcriptional fusions to an ice nucleation reporter g ... | 2005 | 16269724 |
| evidence for horizontal transfer of 1-aminocyclopropane-1-carboxylate deaminase genes. | pcr was used to rapidly identify and isolate 1-aminocyclopropane-1-carboxylate (acc) deaminase genes from bacteria. the shimodaira-hasegawa test was used to assess whether phylogenetically anomalous gene placements suggestive of horizontal gene transfer (hgt) were significantly favored over vertical transmission. the best maximum likelihood (ml) acc deaminase tree was significantly more likely than four alternative ml trees, suggesting hgt. | 2005 | 16269802 |
| characterization of sr3 reveals abundance of non-ltr retrotransposons of the rte clade in the genome of the human blood fluke, schistosoma mansoni. | it is becoming apparent that perhaps as much as half of the genome of the human blood fluke schistosoma mansoni is constituted of mobile genetic element-related sequences. non-long terminal repeat (ltr) retrotransposons, related to the line elements of mammals, comprise much of this repetitive component of the schistosome genome. of more than 12 recognized clades of non-ltr retrotransposons, only members of the cr1, rte, and r2 clades have been reported from the schistosome genome. | 2005 | 16271150 |
| structural basis for transcription inhibition by tagetitoxin. | tagetitoxin (tgt) inhibits transcription by an unknown mechanism. a structure at a resolution of 2.4 a of the thermus thermophilus rna polymerase (rnap)-tgt complex revealed that the tgt-binding site within the rnap secondary channel overlaps that of the stringent control effector ppgpp, which partially protects rnap from tgt inhibition. tgt binding is mediated exclusively through polar interactions with the beta and beta' residues whose substitutions confer resistance to tgt in vitro. important ... | 2005 | 16273103 |
| identification of erwinia amylovora genes induced during infection of immature pear tissue. | the enterobacterium erwinia amylovora is a devastating plant pathogen causing necrotrophic fire blight disease of apple, pear, and other rosaceous plants. in this study, we used a modified in vivo expression technology system to identify e. amylovora genes that are activated during infection of immature pear tissue, a process that requires the major pathogenicity factors of this organism. we identified 394 unique pear fruit-induced (pfi) genes on the basis of sequence similarity to known genes a ... | 2005 | 16291682 |
| genome-wide association mapping in arabidopsis identifies previously known flowering time and pathogen resistance genes. | there is currently tremendous interest in the possibility of using genome-wide association mapping to identify genes responsible for natural variation, particularly for human disease susceptibility. the model plant arabidopsis thaliana is in many ways an ideal candidate for such studies, because it is a highly selfing hermaphrodite. as a result, the species largely exists as a collection of naturally occurring inbred lines, or accessions, which can be genotyped once and phenotyped repeatedly. fu ... | 2005 | 16292355 |
| comparative characterization and expression analysis of the four old yellow enzyme homologues from shewanella oneidensis indicate differences in physiological function. | shewanella oneidensis contains four genes that encode proteins that have high sequence identity with yeast oye (old yellow enzyme, an nadph oxidoreductase), the well-studied archetype of the oye protein family. the present paper describes the first comparative study of oyes that are present in a single bacterial species, performed to gain insight into their biochemical properties and physiological importance. the four proteins [named sye1-sye4 (shewanella yellow enzyme 1-4)] were expressed as gl ... | 2006 | 16293111 |
| a pathogen-inducible patatin-like lipid acyl hydrolase facilitates fungal and bacterial host colonization in arabidopsis. | genes and proteins related to patatin, the major storage protein of potato tubers, have been identified in many plant species and shown to be induced by a variety of environmental stresses. the arabidopsis patatin-like gene family (plps) comprises nine members, two of which (plp2 and plp7) are strongly induced in leaves challenged with fungal and bacterial pathogens. here we show that accumulation of plp2 protein in response to botrytis cinerea or pseudomonas syringae pv. tomato (avrrpt2) is dep ... | 2005 | 16297072 |
| the diphenylether herbicide lactofen induces cell death and expression of defense-related genes in soybean. | lactofen belongs to the diphenylether class of herbicides, which targets protoporphyrinogen oxidase, which in turn causes singlet oxygen generation. in tolerant plants like soybean (glycine max), the chemical nonetheless causes necrotic patches called "bronzing" in contact areas. here it is shown that such bronzing is accompanied by cell death, which was quantified from digital microscopic images using assess software. cellular autofluorescence accompanied cell death, and a homolog of the cell d ... | 2005 | 16299178 |
| haemophilus ducreyi targets src family protein tyrosine kinases to inhibit phagocytic signaling. | haemophilus ducreyi, the etiologic agent of the sexually transmitted disease chancroid, has been shown to inhibit phagocytosis of both itself and secondary targets in vitro. immunodepletion of lspa proteins from h. ducreyi culture supernatant fluid abolished this inhibitory effect, indicating that the lspa proteins are necessary for the inhibition of phagocytosis by h. ducreyi. fluorescence microscopy revealed that macrophages incubated with wild-type h. ducreyi, but not with a lspa1 lspa2 mutan ... | 2005 | 16299270 |
| roles of specific amino acids in the n terminus of pseudomonas aeruginosa flagellin and of flagellin glycosylation in the innate immune response. | the toll-like receptor 5 (tlr5) binding site has been predicted to be in the n terminus of the flagellin molecule. in order to better define the interaction between the n-terminal amino acids of pseudomonas aeruginosa flagellin and tlr5, site-specific mutations were generated between residues 88 and 97 of p. aeruginosa pak flagellin as well as outside of this region. the mutant flagellins were expressed in escherichia coli bl21(plyss), purified by affinity chromatography, and passed through a po ... | 2005 | 16299320 |
| characterization of two non-locus of enterocyte effacement-encoded type iii-translocated effectors, nlec and nled, in attaching and effacing pathogens. | intestinal colonization by enteropathogenic and enterohemorrhagic escherichia coli requires the locus of enterocyte effacement-encoded type iii secretion system. we report that nlec and nled are translocated into host cells via this system. deletion mutants induced attaching and effacing lesions in vitro, while infection of calves or lambs showed that neither gene was required for colonization. | 2005 | 16299341 |
| pleiotropic costs of niche expansion in the rna bacteriophage phi 6. | natural and experimental systems have failed to universally demonstrate a trade-off between generalism and specialism. when a trade-off does occur it is difficult to attribute its cause to antagonistic pleiotropy without dissecting the genetic basis of adaptation, and few previous experiments provide these genetic data. here we investigate the evolution of expanded host range (generalism) in the rna virus phi6, an experimental model system allowing adaptive mutations to be readily identified. we ... | 2006 | 16299384 |
| novel cyclic lipodepsipeptide from pseudomonas syringae pv. lachrymans strain 508 and syringopeptin antimicrobial activities. | the syringopeptins are a group of antimicrobial cyclic lipodepsipeptides produced by several plant-associated pseudomonads. a novel syringopeptin, sp508, was shown to be produced as two homologs (a and b) by pseudomonas syringae pv. lachrymans strain 508 from apple and to structurally resemble syringopeptin sp22. sp508 differed from sp22 and other syringopeptins by having three instead of four alpha,beta-unsaturated amino acids and a longer beta-hydroxy acyl chain. both sp508 and sp22 displayed ... | 2005 | 16304170 |
| pathogen-responsive expression of glycosyltransferase genes ugt73b3 and ugt73b5 is necessary for resistance to pseudomonas syringae pv tomato in arabidopsis. | the genome sequencing of arabidopsis (arabidopsis thaliana) has revealed that secondary metabolism plant glycosyltransferases (ugts) are encoded by an unexpectedly large multigenic family of 120 members. very little is known about their actual function in planta, in particular during plant pathogen interactions. among them, members of the group d are of particular interest since they are related to ugts involved in stress-inducible responses in other plant species. we provide here a detailed ana ... | 2005 | 16306146 |
| four-helix bundle: a ubiquitous sensory module in prokaryotic signal transduction. | motivation: transmembrane chemoreceptors in escherichia coli utilize ligand-binding domains for detecting various external signals. the structure of this domain in the e.coli aspartate receptor, tar, is known and its signal transduction mechanism is under investigation. current domain models for this important sensory module are inaccurate and, therefore, cannot reveal the distribution of this domain within the current genomic landscape. results: we carried out sensitive and exhaustive psi-blast ... | 2005 | 16306392 |
| role of the pseudomonas fluorescens alginate lyase (algl) in clearing the periplasm of alginates not exported to the extracellular environment. | alginate is an industrially widely used polysaccharide produced by brown seaweeds and as an exopolysaccharide by bacteria belonging to the genera pseudomonas and azotobacter. the polymer is composed of the two sugar monomers mannuronic acid and guluronic acid (g), and in all these bacteria the genes encoding 12 of the proteins essential for synthesis of the polymer are clustered in the genome. interestingly, 1 of the 12 proteins is an alginate lyase (algl), which is able to degrade the polymer d ... | 2005 | 16321942 |
| identification of a twin-arginine translocation system in pseudomonas syringae pv. tomato dc3000 and its contribution to pathogenicity and fitness. | the bacterial plant pathogen pseudomonas syringae pv. tomato dc3000 (dc3000) causes disease in arabidopsis thaliana and tomato plants, and it elicits the hypersensitive response in nonhost plants such as nicotiana tabacum and nicotiana benthamiana. while these events chiefly depend upon the type iii protein secretion system and the effector proteins that this system translocates into plant cells, additional factors have been shown to contribute to dc3000 virulence and still many others are likel ... | 2005 | 16321949 |
| genetic requirements for potassium ion-dependent colony spreading in bacillus subtilis. | undomesticated strains of bacillus subtilis exhibit extensive colony spreading on certain soft agarose media: first the formation of dendritic clusters of cells, followed by spreading (pellicle-like) growth to cover the entire surface. these phases of colonization are dependent on the level of potassium ion (k(+)) but independent of flagella, as verified with a mutant with a hag gene replacement; this latter finding highlights the importance of sliding motility in colony spreading. exploring the ... | 2005 | 16321950 |
| genetic characterization of pseudomonas fluorescens sbw25 rsp gene expression in the phytosphere and in vitro. | the plant-colonizing pseudomonas fluorescens strain sbw25 harbors a gene cluster (rsp) whose products show similarity to type iii protein secretion systems found in plant and animal pathogens. here we report a detailed analysis of the expression and regulation of the p. fluorescens rsp pathway, both in the phytosphere and in vitro. a combination of chromosomally integrated transcriptional reporter fusions, overexpressed regulatory genes, and specific mutants reveal that promoters controlling exp ... | 2005 | 16321952 |
| genetic and molecular characterization of the i locus of phaseolus vulgaris. | the i locus of the common bean, phaseolus vulgaris, controls the development of four different phenotypes in response to inoculation with bean common mosaic virus, bean common mosaic necrosis virus, several other related potyviruses, and one comovirus. we have generated a high-resolution linkage map around this locus and have aligned it with a physical map constructed with bac clones. these clones were obtained from a library of the cultivar "sprite," which carries the dominant allele at the i l ... | 2006 | 16322513 |
| accumulation of gentisic acid as associated with systemic infections but not with the hypersensitive response in plant-pathogen interactions. | in the present work we have studied the accumulation of gentisic acid (2,5-dihydroxybenzoic acid, a metabolic derivative of salicylic acid, sa) in the plant-pathogen systems, cucumis sativus and gynura aurantiaca, infected with either prunus necrotic ringspot virus (pnrsv) or the exocortis viroid (cevd), respectively. both pathogens produced systemic infections and accumulated large amounts of the intermediary signal molecule gentisic acid as ascertained by electrospray ionization mass spectrome ... | 2006 | 16331468 |
| characterization of a unique chromosomal copper resistance gene cluster from xanthomonas campestris pv. vesicatoria. | we characterized the copper resistance genes in strain xvp26 of xanthomonas campestris pv. vesicatoria, which was originally isolated from a pepper plant in taiwan. the copper resistance genes were localized to a 7,652-bp region which, based on pulsed-field gel electrophoresis and southern hybridization, was determined to be located on the chromosome. these genes hybridized only weakly, as determined by southern analysis, to other copper resistance genes in xanthomonas and pseudomonas strains. w ... | 2005 | 16332814 |
| bleeding sap and old wood are the two main sources of contamination of merging organs of vine plants by xylophilus ampelinus, the causal agent of bacterial necrosis. | the spatial distribution of vine plants contaminated by xylophilus ampelinus, the agent responsible for bacterial necrosis, was studied over a 5-year period within two vineyards in the cognac area. both vineyards were planted with vitis vinifera cv. ugni blanc but were different in age and agronomic location. the emission of x. ampelinus in contaminated bleeding sap was observed during vine sprouting. contaminated bleeding sap is an important source of inoculum for external contamination due to ... | 2005 | 16332815 |
| multilocus sequence type system for the plant pathogen xylella fastidiosa and relative contributions of recombination and point mutation to clonal diversity. | multilocus sequence typing (mlst) identifies and groups bacterial strains based on dna sequence data from (typically) seven housekeeping genes. mlst has also been employed to estimate the relative contributions of recombination and point mutation to clonal divergence. we applied mlst to the plant pathogen xylella fastidiosa using an initial set of sequences for 10 loci (9.3 kb) of 25 strains from five different host plants, grapevine (pd strains), oleander (ols strains), oak (oak strains), almon ... | 2005 | 16332839 |
| two novel bacterial biosensors for detection of nitrate availability in the rhizosphere. | the nitrate-regulated promoter of narg in escherichia coli was fused to promoterless ice nucleation (inaz) and green fluorescent protein (gfp) reporter genes to yield the nitrate-responsive gene fusions in plasmids pnice and pngfp, respectively. while the promoter of narg is normally nitrate responsive only under anaerobic conditions, the l28h-fnr gene was provided in trans to enable nitrate-dependent expression of these reporter gene fusions even under aerobic conditions in both e. coli dh5alph ... | 2005 | 16332845 |
| engineering pseudomonas fluorescens for biodegradation of 2,4-dinitrotoluene. | using the genes encoding the 2,4-dinitrotoluene degradation pathway enzymes, the nonpathogenic psychrotolerant rhizobacterium pseudomonas fluorescens atcc 17400 was genetically modified for degradation of this priority pollutant. first, a recombinant strain designated mp was constructed by conjugative transfer from burkholderia sp. strain dnt of the pjs1 megaplasmid, which contains the dnt genes for 2,4-dinitrotoluene degradation. this strain was able to grow on 2,4-dinitrotoluene as the sole so ... | 2005 | 16332883 |
| a novel endogenous inhibitor of the secreted streptococcal nad-glycohydrolase. | the streptococcus pyogenes nad-glycohydrolase (spn) is a toxic enzyme that is introduced into infected host cells by the cytolysin-mediated translocation pathway. however, how s. pyogenes protects itself from the self-toxicity of spn had been unknown. in this report, we describe immunity factor for spn (ifs), a novel endogenous inhibitor that is essential for spn expression. a small protein of 161 amino acids, ifs is localized in the bacterial cytoplasmic compartment. ifs forms a stable complex ... | 2005 | 16333395 |
| comparative analysis of programmed cell death pathways in filamentous fungi. | fungi can undergo autophagic- or apoptotic-type programmed cell death (pcd) on exposure to antifungal agents, developmental signals, and stress factors. filamentous fungi can also exhibit a form of cell death called heterokaryon incompatibility (hi) triggered by fusion between two genetically incompatible individuals. with the availability of recently sequenced genomes of aspergillus fumigatus and several related species, we were able to define putative components of fungi-specific death pathway ... | 2005 | 16336669 |
| activation of defense responses in chinese cabbage by a nonhost pathogen, pseudomonas syringae pv. tomato. | pseudomonas syringae pv. tomato (pst) causes a bacterial speck disease in tomato and arabidopsis. in chinese cabbage, in which host-pathogen interactions are not well understood, pst does not cause disease but rather elicits a hypersensitive response. pst induces localized cell death and h2o2 accumulation, a typical hypersensitive response, in infiltrated cabbage leaves. pre-inoculation with pst was found to induce resistance to erwinia carotovora subsp. carotovora, a pathogen that causes soft r ... | 2005 | 16336791 |
| alternative sigma factors and their roles in bacterial virulence. | sigma factors provide promoter recognition specificity to rna polymerase holoenzyme, contribute to dna strand separation, and then dissociate from the core enzyme following transcription initiation. as the regulon of a single sigma factor can be composed of hundreds of genes, sigma factors can provide effective mechanisms for simultaneously regulating expression of large numbers of prokaryotic genes. one newly emerging field is identification of the specific roles of alternative sigma factors in ... | 2005 | 16339734 |
| heterotrimeric g proteins facilitate arabidopsis resistance to necrotrophic pathogens and are involved in jasmonate signaling. | heterotrimeric g proteins have been previously linked to plant defense; however a role for the gbetagamma dimer in defense signaling has not been described to date. using available arabidopsis (arabidopsis thaliana) mutants lacking functional galpha or gbeta subunits, we show that defense against the necrotrophic pathogens alternaria brassicicola and fusarium oxysporum is impaired in gbeta-deficient mutants while galpha-deficient mutants show slightly increased resistance compared to wild-type c ... | 2006 | 16339801 |
| the membrane-anchored botrytis-induced kinase1 plays distinct roles in arabidopsis resistance to necrotrophic and biotrophic pathogens. | plant resistance to disease is controlled by the combination of defense response pathways that are activated depending on the nature of the pathogen. we identified the arabidopsis thaliana botrytis-induced kinase1 (bik1) gene that is transcriptionally regulated by botrytis cinerea infection. inactivation of bik1 causes severe susceptibility to necrotrophic fungal pathogens but enhances resistance to a virulent strain of the bacterial pathogen pseudomonas syringae pv tomato. the response to an av ... | 2006 | 16339855 |
| generalized transduction in the phytopathogen pseudomonas syringae. | bacteriophages isolated from culture supernatants of pseudomonas syringae pv. syringae and from sewage transferred various chromosomal genes to p. syringae ps224. linkage between arginine and tryptophan loci was demonstrated. the number of transductants recovered per milliliter was not altered appreciably by uv irradiation of selected phage isolates. in addition, the presence of the incp2 plasmid r38 in a p. syringae ps224 arginine auxotroph did not increase the transduction frequency as it does ... | 1983 | 16346318 |
| isolation and partial characterization of bacteriophages of the phytopathogen pseudomonas syringae. | bacteriophages isolated from culture supernatants of pseudomonas syringae pv. syringae and from sewage were identified. the dna from each phage was isolated and digested with the restriction endonuclease ecori. eight isolates were determined to be different, with two phage isolates from sewage having restriction patterns identical to two phages from culture supernatants. the sizes of the phage dna ranged from 24 to49 kilobases for isolates from sewage and from 39 to 52.5 kilobases for the isolat ... | 1983 | 16346319 |
| toxicity of smoke to epiphytic ice nucleation-active bacteria. | wheat straw smoke aerosols and liquid smoke condensates reduced significantly both the viability and the ice-nucleating activity of pseudomonas syringae pv. syringae and erwinia herbicola in vitro and on leaf surfaces in vivo. highly significant reductions in numbers of bacterial ice nuclei on the surface of both corn and almond were observed after exposure to smoke aerosols. at -5 degrees c, frost injury to corn seedlings colonized by ice nucleation-active bacteria was reduced after exposure to ... | 1983 | 16346333 |
| distribution, population dynamics, and characteristics of ice nucleation-active bacteria in deciduous fruit tree orchards. | deciduous fruit tree orchards located in the pacific northwest were surveyed over a 3-year period for the presence of ice nucleation-active (ina) bacteria. in the yakima valley, only about 30% of the fruit tree orchards contained ina bacteria (median population ca. 3 x 10 cfu/g [fresh weight]) in contrast to nearly 75% of the orchards in the hood river valley (median population ca. 5 x 10 cfu/g [fresh weight]). these ina populations ranged from less than 10 to over 10 cfu/g (fresh weight) of blo ... | 1983 | 16346445 |
| differences between lipopolysaccharide compositions of plant pathogenic and saprophytic pseudomonas species. | lipopolysaccharides (lps) were obtained by washing cells of plant pathogenic and saprophytic pseudomonas species with saline (fraction 1) and then with saline-edta (fraction 2). the cells subsequently were extracted with phenol to yield a third aqueous preparation (fraction 3). each fraction type contained the lps components, lipid a, heptose, 2-keto-3-deoxy sugar, and neutral and amino sugars. the neutral sugar compositions of fractions 1, 2, and 3, although similar within a species, differed b ... | 1984 | 16346597 |
| generation and characterization of tn5 insertion mutations in pseudomonas syringae pv. tomato. | tn5-induced insertion mutations were generated in the pseudomonas syringae pv. tomato genome by mating this plant pathogen with an escherichia coli strain carrying the suicide plasmid vector for tn5, pgs9. km transconjugants occurred at frequencies ranging from 2 x 10 to 9 x 10; approximately 5.5% of these transconjugants were also cm, indicating the presence of additional pgs9 dna sequences. approximately 1% of the km cm mutants were auxotrophic. southern blot analysis revealed that the tn5 ele ... | 1986 | 16346988 |
| isolation and characterization of an fe(iii)-chelating compound produced by pseudomonas syringae. | the phytopathogenic bacterium pseudomonas syringae produces a fluorescent pigment when it is grown in iron-deficient media. this pigment forms a very stable fe(iii) complex that was purified in this form by using a novel procedure based on ultrafiltration and column chromatography. the fe(iii) complex has a molecular weight of 1,100 and contains 1 mol of fe(iii). the pigment is composed of an amino acid moiety with three threonines, three serines, one lysine, delta-n-hydroxyornithine, and a quin ... | 1986 | 16347102 |
| antagonism of lactic acid bacteria against phytopathogenic bacteria. | a variety of lactic acid bacteria, isolated from plant surfaces and plant-associated products, were found to be antagonistic to test strains of the phytopathogens xanthomonas campestris, erwinia carotovora, and pseudomonas syringae. effective "in vitro" inhibition was found both on agar plates and in broth cultures. in pot trials, treatment of bean plants with a lactobacillus plantarum strain before inoculation with p. syringae caused a significant reduction of the disease incidence. | 1986 | 16347150 |
| characterization of a copper resistance plasmid conserved in copper-resistant strains of pseudomonas syringae pv. tomato. | a 35-kilobase plasmid was conserved among 12 copper-resistant strains of pseudomonas syringae pv. tomato. restriction patterns of this plasmid from each strain were identical, and a cloned copper resistance gene from 1 strain hybridized to the same location on the 35-kilobase plasmid of all 12 strains. | 1987 | 16347294 |
| characterization of pyoverdin(pss), the fluorescent siderophore produced by pseudomonas syringae pv. syringae. | pseudomonas syringae pv. syringae b301d produces a yellow-green, fluorescent siderophore, pyoverdin(pss), in large quantities under iron-limited growth conditions. maximum yields of pyoverdin(pss) of approximately 50 mug/ml occurred after 24 h of incubation in a deferrated synthetic medium. increasing increments of fe(iii) coordinately repressed siderophore production until repression was complete at concentrations of >/= 10 mum. pyoverdin(pss) was isolated, chemically characterized, and found t ... | 1987 | 16347352 |
| auxin production by plant-pathogenic pseudomonads and xanthomonads. | pathogenic strains of xanthomonas campestris pv. glycines which cause hypertrophy of leaf cells of susceptible soybean cultivars and nonpathogenic strains which do not cause hypertrophy were compared for their ability to produce indole compounds, including the plant hormone indole-3-acetic acid (iaa) in liquid media with or without supplementation with l-tryptophan. several additional strains of plant-pathogenic xanthomonads and pseudomonads were also tested for iaa production to determine wheth ... | 1987 | 16347409 |
| competitive exclusion of epiphytic bacteria by icepseudomonas syringae mutants. | the growth of ice nucleation-active and near-isogenic ice nucleation-deficient (ice) pseudomonas syringae strains coexisting on leaf surfaces was examined to determine whether competition was sufficient to account for antagonism of phylloplane bacteria. the ice nucleation frequency spectra of 46 icep. syringae mutants, obtained after mutagenesis with ethyl methanesulfonate, differed both quantitatively and qualitatively, but the mutants could be grouped into four distinct phenotypic classes. the ... | 1987 | 16347468 |
| flagellar motility confers epiphytic fitness advantages upon pseudomonas syringae. | the role of flagellar motility in determining the epiphytic fitness of an ice-nucleation-active strain of pseudomonas syringae was examined. the loss of flagellar motility reduced the epiphytic fitness of a normally motile p. syringae strain as measured by its growth, survival, and competitive ability on bean leaf surfaces. equal population sizes of motile parental or nonmotile mutant p. syringae strains were maintained on bean plants for at least 5 days following the inoculation of fully expand ... | 1987 | 16347469 |
| chemotaxis by pseudomonas syringae pv. tomato. | optimal laboratory conditions for studying chemotaxis by pseudomonas syringae pv. tomato were determined by using the adler capillary tube assay. although they are not an absolute requirement for chemotaxis, the presence of 0.1 mm edta and 1 mm mgcl(2) in the chemotaxis buffer (10 mm potassium phosphate [ph 7.2]) significantly enhanced the response to attractant. the addition of mannitol as an energy source had little effect. the optimal temperature for chemotaxis was 23 degrees c, which is 5 de ... | 1988 | 16347574 |
| evaluation of the role of syringomycin in plant pathogenesis by using tn5 mutants of pseudomonas syringae pv. syringae defective in syringomycin production. | syringomycin is a necrosis-inducing phytotoxin produced by pseudomonas syringae pv. syringae. to determine whether syringomycin production is a determinant in virulence or pathogenicity, we isolated nontoxigenic (tox) tn5-containing mutants and then quantitatively evaluated them for the ability to multiply and cause disease in immature sweet-cherry fruits. transposon tn5 was delivered to tox strain b301d-r by using the suicide vector, pgs9, and the resultant kanamycin-resistant (km) colonies wer ... | 1988 | 16347644 |
| aerial dispersal and epiphytic survival of pseudomonas syringae during a pretest for the release of genetically engineered strains into the environment. | prospective experimental field evaluation of genetically engineered microorganisms, such as microbial pest control agents, raises issues of how to properly ascertain their fate and survival in the environment. field trials with recombinant organisms must reflect requirements for sampling and monitoring. field trials were conducted at tulelake, calif., to monitor the numbers of viable cells of a nonrecombinant strain of pseudomonas syringae that entered the atmosphere and landed on plants and soi ... | 1988 | 16347666 |
| effect of plant species and environmental conditions on ice nucleation activity of pseudomonas syringae on leaves. | selected plant species and environmental conditions were investigated for their influences on expression of ice nucleation activity by 15 pseudomonas syringae strains grown on plants in constant-temperature growth chamber studies. ice nucleation frequencies (infs), the fraction of cells that expressed ice nucleation at -5 or -9 degrees c, of individual strains varied greatly, both on plants and in culture. this suggests that the probability of frost injury, which is proportional to the number of ... | 1988 | 16347741 |
| scanning electron microscopy of invasion of apple leaves and blossoms by pseudomonas syringae pv. syringae. | scanning electron microscopy indicated that pseudomonas syringae pv. syringae l795 entered leaves through stomata and multiplied in the substomatal chambers. strain l195 applied to blossoms colonized stigmas and also occurred in intercellular spaces of styles. nonpathogenic strain l796 failed to colonize blossoms. this study suggests that inoculum of pathogenic p. syringae pv. syringae builds up on apple leaves and blossoms. | 1989 | 16347862 |
| diel variation in population size and ice nucleation activity of pseudomonas syringae on snap bean leaflets. | the extent to which diel changes in the physical environment affect changes in population size and ice nucleation activity of pseudomonas syringae on snap bean leaflets was determined under field conditions. to estimate bacterial population size and ice nucleation activity, bean leaflets were harvested at 2-h intervals during each of three 26-h periods. a tube nucleation test was used to assay individual leaflets for ice nuclei. population sizes of p. syringae were determined by dilution plating ... | 1989 | 16347871 |
| survival of ice nucleation-active and genetically engineered non-ice-nucleating pseudomonas syringae strains after freezing. | the survival after freezing of ice nucleation-active (ina) and genetically engineered non-ina strains of pseudomonas syringae was compared. each strain was applied to oat seedlings and allowed to colonize for 3 days, and the plants were subjected to various freezing temperatures. plant leaves were harvested before and after freezing on two consecutive days, and bacterial populations were determined. populations of the ina wild-type strain increased 15-fold in the 18 h after the oat plants incurr ... | 1989 | 16347963 |
| response of plant-colonizing pseudomonads to hydrogen peroxide. | colonization of plant root surfaces by pseudomonas putida may require mechanisms that protect this bacterium against superoxide anion and hydrogen peroxide produced by the root. catalase and superoxide dismutase may be important in this bacterial defense system. stationary-phase cells of p. putida were not killed by hydrogen peroxide (h(2)o(2)) at concentrations up to 10 mm, and extracts from these cells possessed three isozymic bands (a, b, and c) of catalase activity in native polyacrylamide g ... | 1989 | 16348058 |
| plasmid-determined copper resistance in pseudomonas syringae from impatiens. | a strain of pseudomonas syringae was recently identified as the cause of a new foliar blight of impatiens. the bacterium was resistant to copper compounds, which are used on a variety of crops for bacterial and fungal disease control. the bacterium contained a single 47-kilobase plasmid (ppsi1) that showed homology to a copper resistance operon previously cloned and characterized from p. syringae pv. tomato plasmid ppt23d (d. cooksey, appl. environ. microbiol. 53:454-456, 1987). ppsi1 was transf ... | 1990 | 16348085 |
| copper resistance gene homologs in pathogenic and saprophytic bacterial species from tomato. | copper-resistant strains of xanthomonas campestris pv. vesicatoria, pseudomonas cichorii, pseudomonas putida, pseudomonas fluorescens, and a yellow pseudomonas sp. were isolated from tomato plants or seeds. in southern hybridizations, dna from each strain showed homology with the copper resistance (cop) operon previously cloned from pseudomonas syringae pv. tomato pt23. homology was associated with plasmid and chromosomal dna in x. compestris pv. vesicatoria, p. putida, and the yellow pseudomona ... | 1990 | 16348118 |
| construction and use of a nonradioactive dna hybridization probe for detection of pseudomonas syringae pv. tomato on tomato plants. | pseudomonas syringae pv. tomato, the causal agent for bacterial speck of tomato, produces the phytotoxin coronatine. a 5.3-kilobase xhoi fragment from the chromosomal region controlling toxin production was cloned into the plasmid pgb2, and the resulting recombinant plasmid, ptpr1, was tested for its ability to serve as a diagnostic probe for p. syringae pv. tomato. in a survey of 75 plant-associated bacteria, ptpr1 hybridized exclusively to those strains that produced coronatine. the detection ... | 1990 | 16348215 |
| fate of ice nucleation-active pseudomonas syringae strains in alpine soils and waters and in synthetic snow samples. | the stability of the ice nucleation activity (ina) and viability of ina pseudomonas syringae 31a, used as an ice nucleator in the manufacture of synthetic snow, was determined in snow. the viability of p. syringae 1-2b, a rifampin-resistant mutant selected from strain 31a to improve recovery from test samples, was determined in laboratory tests of three alpine soil and water samples from three different sources. snow samples were exposed to environmental conditions or held in darkness at -20 deg ... | 1990 | 16348241 |
| homologous streptomycin resistance gene present among diverse gram-negative bacteria in new york state apple orchards. | the streptomycin resistance gene of pseudomonas syringae pv. papulans psp36 was cloned into escherichia coli and used to develop a 500-bp dna probe that is specific for streptomycin resistance in p. syringae pv. papulans. the probe is a portion of a 1-kb region shared by three different dna clones of the resistance gene. in southern hybridizations, the probe hybridized only with dna isolated from streptomycin-resistant strains of p. syringae pv. papulans and not with the dna of streptomycin-sens ... | 1991 | 16348415 |
| rapid in situ assay for indoleacetic acid production by bacteria immobilized on a nitrocellulose membrane. | we have developed a new assay that differentiates between indoleacetic acid (iaa)-producing and -nonproducing bacteria on a colony plate lift. medium supplemented with 5 mm l-tryptophan is inoculated with isolates of interest, overlaid with a nitrocellulose membrane, and then incubated until bacterial colonies reach 1 to 2 mm in diameter. the membrane is removed to a filter paper saturated with salkowski reagent and incubated until distinct red haloes form around the colonies. the colorimetric r ... | 1991 | 16348419 |
| evaluation of four aerobiological sampling methods for the retrieval of aerosolized pseudomonas syringae. | the andersen six-stage impactor, the sas (surface air system) impactor, the agi-30 impinger, and gravity plates were evaluated for the retrieval of aerosol-released pseudomonas syringae. the upper limits of the impactor samplers were exceeded at a spray concentration of 10 cfu/ml, indicating that these samplers are not appropriate for monitoring high airborne concentrations. decreased cell concentrations were retrieved with increased sampling time for the andersen and agi samplers, indicating th ... | 1991 | 16348468 |
| conservation of plasmid dna sequences in coronatine-producing pathovars of pseudomonas syringae. | in pseudomonas syringae pv. tomato pt23.2, plasmid ppt23a (101 kb) is involved in synthesis of the phytotoxin coronatine (c. l. bender, d. k. malvick, and r. e. mitchell, j. bacteriol. 171:807-812, 1989). the physical characterization of mutations that abolished coronatine production indicated that at least 30 kb of ppt23a dna are required for toxin synthesis. in the present study, p-labeled dna fragments from the 30-kb region of ppt23a hybridized to plasmid dnas from several coronatine-producin ... | 1991 | 16348476 |
| evaluation of four aerobiological sampling methods for the retrieval of aerosolized pseudomonas syringae. | [this corrects the article on p. 1268 in vol. 57.]. | 1991 | 16348546 |
| chemotaxis of pseudomonas syringae subsp. savastanoi virulence mutants. | several mutants of pseudomonas syringae subsp. savastanoi were tested for their ability to sense and respond to a chemotactic gradient in low concentrations of yeast extract. the mutants were deficient in one or both of the genes coding for the synthesis of the plant hormones indole-3-acetic acid (iaa) and isopentenyl adenosine. mutations which resulted in the loss of iaa production were due to the loss of the entire plasmid containing the iaa operon or to an 18-kb deletion of the iaa region. ad ... | 1991 | 16348565 |
| accumulation of copper and other metals by copper-resistant plant-pathogenic and saprophytic pseudomonads. | copper-resistant strains of pseudomonas syringae carrying the cop operon produce periplasmic copper-binding proteins, and this sequestration outside the cytoplasm has been proposed as a resistance mechanism. in this study, strain ps61 of p. syringae carrying the cloned cop operon accumulated more total cellular copper than without the operon. several other copper-resistant pseudomonads with homology to cop were isolated from plants, and these bacteria also accumulated copper. two highly resistan ... | 1992 | 16348627 |
| detection of a single genetically modified bacterial cell in soil by using charge coupled device-enhanced microscopy. | genes encoding bioluminescence from vibrio harveyi were cloned into pseudomonas syringae pv. phaseoli-cola, resulting in high levels of bioluminescence. after inoculation of sterile and nonsterile soil slurries with bioluminescent p. syringae, cells could not be identified by conventional light microscopy. however, when we used charge coupled device-enhanced microscopy, bioluminescent single cells were detected easily in dark fields despite masking by soil particulate matter, and in addition, th ... | 1992 | 16348749 |