Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| new mobilizable vectors suitable for gene replacement in gram-negative bacteria and their use in mapping of the 3' end of the xanthomonas campestris pv. campestris gum operon. | we describe useful vectors to select double-crossover events directly in site-directed marker exchange mutagenesis in gram-negative bacteria. these vectors contain the gusa marker gene, providing colorimetric screens to identify bacteria harboring those sequences. the applicability of these vectors was shown by mapping the 3' end of the xanthomonas campestris gum operon, involved in biosynthesis of xanthan. | 1999 | 9872790 |
| overexpression of pto activates defense responses and confers broad resistance. | the tomato disease resistance (r) gene pto specifies race-specific resistance to the bacterial pathogen pseudomonas syringae pv tomato carrying the avrpto gene. pto encodes a serine/threonine protein kinase that is postulated to be activated by a physical interaction with the avrpto protein. here, we report that overexpression of pto in tomato activates defense responses in the absence of the pto-avrpto interaction. leaves of three transgenic tomato lines carrying the cauliflower mosaic virus 35 ... | 1999 | 9878629 |
| regulation of expression of avirulence gene avrrxv and identification of a family of host interaction factors by sequence analysis of avrbst. | resistance in tomato line hawaii 7998 as well as in several nonhost plants to xanthomonas campestris pv. vesicatoria tomato strain (xcvt) is mediated in part by the avirulence gene avrrxv. analysis of growth of wild-type and avrrxv deletion strains indicates that avrrxv plays a crucial role in the ability of xcvt 92-14 to induce resistance on hawaii 7998. we used avrrxv reporter gene fusions and northern (rna) blot analysis to test several growth environments for inductive potential. we found th ... | 1999 | 9885191 |
| identification and characterization of ptlc, an essential component of the pertussis toxin secretion system. | ptlc is a member of a set of proteins necessary for the secretion of pertussis toxin (pt) from bordetella pertussis. using polyclonal antibodies specific for ptlc, we identified ptlc as a protein with an apparent molecular weight of 85,000 that localizes to the membrane fraction of bacterial cell extracts. we found that a mutant strain of b. pertussis that contains an in-frame deletion in ptlc is unable to secrete pt and that pt secretion is fully restored by expressing ptlc in trans, indicating ... | 1999 | 9916087 |
| sequence and function of luxu: a two-component phosphorelay protein that regulates quorum sensing in vibrio harveyi. | vibrio harveyi regulates the expression of bioluminescence (lux) in response to cell density, a phenomenon known as quorum sensing. in v. harveyi, two independent quorum-sensing systems exist, and each produces, detects, and responds to a specific cell density-dependent autoinducer signal. the autoinducers are recognized by two-component hybrid sensor kinases called luxn and luxq, and sensory information from both systems is transduced by a phosphorelay mechanism to the response regulator protei ... | 1999 | 9922254 |
| noll of rhizobium sp. strain ngr234 is required for o-acetyltransferase activity. | following (iso)flavonoid induction, nodulation genes of the symbiotic nitrogen-fixing bacterium rhizobium sp. strain ngr234 elaborate a large family of lipooligosaccharidic nod factors (nodngr factors). when secreted into the rhizosphere of compatible legumes, these signal molecules initiate root hair deformation and nodule development. the nonreducing glucosamine residue of nodngr factors are n acylated, n methylated, and mono- or biscarbamoylated, while position c-6 of the reducing extremity i ... | 1999 | 9922261 |
| cell-specific production and antimicrobial activity of naphthoquinones in roots of lithospermum erythrorhizon | pigmented naphthoquinone derivatives of shikonin are produced at specific times and in specific cells of lithospermum erythrorhizon roots. normal pigment development is limited to root hairs and root border cells in hairy roots grown on "noninducing" medium, whereas induction of additional pigment production by abiotic (cuso4) or biotic (fungal elicitor) factors increases the amount of total pigment, changes the ratios of derivatives produced, and initiates production of pigment de novo in epide ... | 1999 | 9952436 |
| expression and study of recombinant exom, a beta1-4 glucosyltransferase involved in succinoglycan biosynthesis in sinorhizobium meliloti. | here we report on the overexpression and in vitro characterization of a recombinant form of exom, a putative beta1-4 glucosyltransferase involved in the assembly of the octasaccharide repeating subunit of succinoglycan from sinorhizobium meliloti. the open reading frame exom was isolated by pcr and subcloned into the expression vector pet29b, allowing inducible expression under the control of the t7 promoter. escherichia coli bl21(de3)/plyss containing exom expressed a novel 38-kda protein corre ... | 1999 | 9973339 |
| characterization of insertions of is476 and two newly identified insertion sequences, is1478 and is1479, in xanthomonas campestris pv. campestris. | thirty-two plasmid insertion mutants were independently isolated from two strains of xanthomonas campestris pv. campestris in taiwan. of the 32 mutants, 14 (44%), 8 (25%), and 4 (12%) mutants resulted from separate insertions of an is3 family member, is476, and two new insertion sequences (is), is1478 and is1479. while is1478 does not have significant sequence homology with any is elements in the embl/genbank/ddbj database, is1479 demonstrated 73% sequence homology with is1051 in x. campestris p ... | 1999 | 9973349 |
| prhj and hrpg, two new components of the plant signal-dependent regulatory cascade controlled by prha in ralstonia solanacearum. | hrp gene expression in the phytopathogenic bacterium ralstonia solanacearum gmi1000 is induced through the hrpb regulator in minimal medium and upon co-culture with plant cell suspensions. the putative outer membrane protein prha is specifically involved in hrp gene activation in the presence of plant cells and has been proposed to be a receptor of a plant-dependent signal transduction pathway. here, we report on the identification of two regulatory genes, hrpg and prhj, located at the right-han ... | 1999 | 9987125 |
| suppression of bacterial blight by a bacterial community isolated from the guttation fluids of anthuriums | growth and survival of xanthomonas campestris pv. dieffenbachiae in guttation fluids (xylem sap exuded from leaf margins) of anthuriums were suppressed by several bacterial strains indigenous to leaves of various anthurium cultivars. inhibition of growth was not observed in filter-sterilized guttation fluids and was restored to original levels only by reintroducing specific mixtures of bacteria into filter-sterilized guttation fluids. the inhibitory effect was related to the species in the bacte ... | 1999 | 10049858 |
| isolation of ethylene-insensitive soybean mutants that are altered in pathogen susceptibility and gene-for-gene disease resistance | plants commonly respond to pathogen infection by increasing ethylene production, but it is not clear if this ethylene does more to promote disease susceptibility or disease resistance. ethylene production and/or responsiveness can be altered by genetic manipulation. the present study used mutagenesis to identify soybean (glycine max l. merr.) lines with reduced sensitivity to ethylene. two new genetic loci were identified, etr1 and etr2. mutants were compared with isogenic wild-type parents for ... | 1999 | 10069832 |
| the sinorhizobium meliloti insertion sequence (is) elements isrm102f34-1/isrm7 and isrm220-13-5 belong to a new family of insertion sequence elements. | the sinorhizobium meliloti insertion sequence (is) elements isrm102f34-1 and isrm220-13-5 are 1481 and 1550 base pairs (bp) in size, respectively. isrm102f34-1 is bordered by 15 bp imperfect terminal inverted repeat sequences (two mismatches), whereas the terminal inverted repeat of isrm220-13-5 has a length of 16 bp (two mismatches). both insertion sequence elements generate a 6-bp target duplication upon transposition. the putative transposase enzymes of isrm102f34-1 and isrm220-13-5 consist o ... | 1999 | 10079521 |
| mutational analysis of the vaca promoter provides insight into gene transcription in helicobacter pylori. | analysis of 12 helicobacter pylori promoters indicates the existence of a consensus -10 hexamer (tataat) but little conservation of -35 sequences. in this study, mutations in either the h. pylori vaca -10 region or the -35 region resulted in decreased vaca transcription and suggested that an extended -10 motif is utilized. thus, despite the lack of a -35 consensus sequence for h. pylori promoters, the -35 region plays a functional role in vaca transcription. | 1999 | 10094707 |
| cellular locations of pseudomonas syringae pv. syringae hrcc and hrcj proteins, required for harpin secretion via the type iii pathway. | the complete hrp-hrc-hrma cluster of pseudomonas syringae pv. syringae 61 encodes 28 polypeptides. a saprophytic bacterium carrying this cluster is capable of secreting hrpz-a harpin encoded by hrpz-in an hrp-dependent manner, which suggests that this cluster contains sufficient components to assemble functional type iii secretion machinery. sequence data show that hrcj and hrcc are putative outer membrane proteins, and nonpolar mutagenesis demonstrates they are all required for hrpz secretion. ... | 1999 | 10094714 |
| vibrio cholerae o1 el tor: identification of a gene cluster required for the rugose colony type, exopolysaccharide production, chlorine resistance, and biofilm formation. | the rugose colony variant of vibrio cholerae o1, biotype el tor, is shown to produce an exopolysaccharide, epsetr, that confers chlorine resistance and biofilm-forming capacity. epsetr production requires a chromosomal locus, vps, that contains sequences homologous to carbohydrate biosynthesis genes of other bacterial species. mutations within this locus yield chlorine-sensitive, smooth colony variants that are biofilm deficient. the biofilm-forming properties of epsetr may enable the survival o ... | 1999 | 10097157 |
| global gaca-steered control of cyanide and exoprotease production in pseudomonas fluorescens involves specific ribosome binding sites. | the conserved two-component regulatory system gacs/gaca determines the expression of extracellular products and virulence factors in a variety of gram-negative bacteria. in the biocontrol strain cha0 of pseudomonas fluorescens, the response regulator gaca is essential for the synthesis of extracellular protease (apra) and secondary metabolites including hydrogen cyanide. gaca was found to exert its control on the hydrogen cyanide biosynthetic genes (hcnabc) and on the apra gene indirectly via a ... | 1999 | 10570200 |
| expression of the bs2 pepper gene confers resistance to bacterial spot disease in tomato. | the bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrbs2. the involvement of avrbs2 in pathogen fitness and its prevalence in many x. campestris pathovars suggests that the bs2 gene may be durable in the field and provide resistance when introduced into other plant species. employing a positional cloning strategy, the bs2 locus was isolated and the gene wa ... | 1999 | 10570214 |
| a novel myb oncogene homologue in arabidopsis thaliana related to hypersensitive cell death. | a novel myb oncogene homologue (atmyb30) has been isolated by differential screening of a cdna library prepared from xanthomonas campestris pv. campestris (x. campestris)-inoculated arabidopsis thaliana cells cultured in the presence of cycloheximide. atmyb30 is a single-copy gene, and the encoded protein contains a myb domain highly homologous to other plant and animal myb proteins. analyses of transcript levels in a. thaliana plants, or in cultured a. thaliana cells infected with either virule ... | 1999 | 10571865 |
| genetic dissection of the outer membrane secretin puld: are there distinct domains for multimerization and secretion specificity? | linker and deletion mutagenesis and gene fusions were used to probe the possible domain structure of the dodecameric outer membrane secretin puld from the pullulanase secretion pathway of klebsiella oxytoca. insertions of 24 amino acids close to or within strongly predicted and highly conserved amphipathic beta strands in the c-terminal half of the polypeptide (the beta domain) abolished sodium dodecyl sulfate (sds)-resistant multimer formation that is characteristic of this protein, whereas ins ... | 1999 | 10572123 |
| cloning, sequencing, and characterization of genomic subtracted sequences from listeria monocytogenes. | individual sequences of a genomic subtracted, pcr-amplified, mixed-sequence probe (gs probe) were cloned and sequenced. the gs probe differentiated restriction fragment length polymorphism patterns for listeria monocytogenes but did not hybridize with members of other bacterial genera. sequence analysis identified several l. monocytogenes sequences already present in the genbank database; the putative identities of other sequences were inferred from homology data, and still other sequences did n ... | 1999 | 10583999 |
| requirement for phosphoglucose isomerase of xanthomonas campestris in pathogenesis of citrus canker. | a mutant (xt906) of xanthomonas campestris pv. citri, the causal agent of citrus canker, was induced by insertion of the transposon tn5tac1 and isolated. this mutant did not grow or elicit canker disease in citrus leaves but was still able to induce a hypersensitive response in a nonhost plant (the common bean). the mutant was also unable to grow on minimal medium containing fructose or glycerol as the sole carbon source. a 2.5-kb fragment of wild-type dna that complemented the mutant phenotype ... | 1999 | 10584018 |
| construction and characterization of regulated l-arabinose-inducible broad host range expression vectors in xanthomonas. | several versions of broad host range (bhr), l-arabinose-inducible expression vectors were constructed. these expression vectors were based on a high copy number bhr pbbr1mcs-4 replicon that could replicate in both enteric and non-enteric gram-negative bacteria. two versions of expression cassettes containing multiple cloning sites either with or without a ribosome binding site were placed under transcriptional control of the escherichia coli bad promoter and arac gene. three versions of vectors ... | 1999 | 10585541 |
| requirement of functional ethylene-insensitive 2 gene for efficient resistance of arabidopsis to infection by botrytis cinerea. | inoculation of wild-type arabidopsis plants with the fungus alternaria brassicicola results in systemic induction of genes encoding a plant defensin (pdf1.2), a basic chitinase (pr-3), and an acidic hevein-like protein (pr-4). pathogen-induced induction of these three genes is almost completely abolished in the ethylene-insensitive arabidopsis mutant ein2-1. this indicates that a functional ethylene signal transduction component (ein2) is required in this response. the ein2-1 mutants were found ... | 1999 | 10594097 |
| a gene involved in quinate metabolism is specific to one dna homology group of xanthomonas campestris. | a gene involved in quinate metabolism was cloned from xanthomonas campestris pv. juglandis strain c5. the gene, quma, located on a 4. 2-kb kpni-ecorv fragment in plasmid pqm38, conferred quinate metabolic activity to x. c. pv. celebensis. tn3-spice insertional analyses further located the quma gene on a region of about 3.0 kb within pqm38. nucleotide sequencing of this 3.0-kb fragment reveals that the coding region of quma is 2373 bp, the deduced amino acid sequence of which closely resembles a ... | 1999 | 10594704 |
| an approach to obtain specific polyclonal antisera to xanthomonas campestris pv. cyamopsidis and its potential application in indexing of infected seeds of guar. | clusterbean seed health testing is warranted since the pathogen (xanthomonas campestris pv. cyamopsidis (xccy)) is seed-borne and seed-transmitted. a polyclonal antibody was developed in rabbit via subcutaneous and intramuscular injections and characterized for sensitivity, specificity and its applicability to elisa which: (i) was sensitive in detecting as few as 102 cells ml - 1 at a titre of 1: 4000; (ii) was specific, since it reacted only with xccy and not with other xanthomonads; (iii) reac ... | 1999 | 10594712 |
| differential and independent roles of a sigma(32) homolog (rpoh) and an hrca repressor in the heat shock response of agrobacterium tumefaciens. | the heat shock response in alpha proteobacteria is unique in that a combination of two regulators is involved: a positive regulator, rpoh (sigma(32) homolog), found in the alpha, beta, and gamma proteobacteria, and a negative regulator, hrca, widely distributed in eubacteria but not in the gamma proteobacteria. to assess the differential roles of the two regulators in these bacteria, we cloned the hrca-grpe operon of agrobacterium tumefaciens, analyzed its transcription, and constructed deletion ... | 1999 | 10601208 |
| chromosome map of xanthomonas campestris pv. campestris 17 with locations of genes involved in xanthan gum synthesis and yellow pigmentation. | no plasmid was detected in xanthomonas campestris pv. campestris 17, a strain of the causative agent of black rot in cruciferous plants isolated in taiwan. its chromosome was cut by paci, pmei, and swai into five, two, and six fragments, respectively, and a size of 4.8 mb was estimated by summing the fragment lengths in these digests. based on the data obtained from partial digestion and southern hybridization using probes common to pairs of the overlapping fragments or prepared from linking fra ... | 1999 | 9864320 |
| regulation of the sol locus genes for butanol and acetone formation in clostridium acetobutylicum atcc 824 by a putative transcriptional repressor. | a gene (orf1, now designated solr) previously identified upstream of the aldehyde/alcohol dehydrogenase gene aad (r. v. nair, g. n. bennett, and e. t. papoutsakis, j. bacteriol. 176:871-885, 1994) was found to encode a repressor of the sol locus (aad, ctfa, ctfb and adc) genes for butanol and acetone formation in clostridium acetobutylicum atcc 824. primer extension analysis identified a transcriptional start site 35 bp upstream of the solr start codon. amino acid comparisons of solr identified ... | 1999 | 9864345 |
| exopolysaccharide biosynthesis in lactococcus lactis nizo b40: functional analysis of the glycosyltransferase genes involved in synthesis of the polysaccharide backbone. | we used homologous and heterologous expression of the glycosyltransferase genes of the lactococcus lactis nizo b40 eps gene cluster to determine the activity and substrate specificities of the encoded enzymes and established the order of assembly of the trisaccharide backbone of the exopolysaccharide repeating unit. epsd links glucose-1-phosphate from udp-glucose to a lipid carrier, epse and epsf link glucose from udp-glucose to lipid-linked glucose, and epsg links galactose from udp-galactose t ... | 1999 | 9864348 |
| evaluation of xanthomonas campestris survival in a soil microcosm system. | xanthomonas campestris pv. campestris is a pathogen of cruciferous plants. we studied the survival of the wild type strain and mutant derivatives which are deficient in exopolysaccharide (eps) or in extracellular protease synthesis in soil microcosms in order to test the hypothesis that, in this environment, adherence to soil particles and scavenging of nutrients are very important strategies for bacterial survival. in sterile soil microcosms, differences in survival were only observed between t ... | 1999 | 10943401 |
| [xanthan production by xanthomonas campestris in a non-conventional culture medium]. | among 3 varieties of xanthomonas campestris, the variety ocumo (x. campestris pv. ocumo), showed the greatest capacity for producing xanthan. this bacteria grows appropriately and produces this polysaccharide in a wide diversity of carbohydrate sources. however, this strain does not produce xanthan when the carbohydrate comes from lignocellulosic materials. the glucose syrup favepro was the carbon source that showed the best yield (23 g/l) with the greatest viscosity (7000 cps) of xanthan. the o ... | 1999 | 10974710 |
| [examining interaction of phages with microorganisms by fluorometry and electro-orientation spectroscopy]. | bacterial sensitivity to different various phages was examined by electro-orientation spectroscopy, fluorometry, and electron microscopy. the strains of pseudomonas aeruginosa, staphylococcus aureus, yersinia pestis, mycobacterium smegmatis, and xanthomonas campestris were used. the fluorescence intensity of a membranotropic agent in the ans-cell-phage system was shown to depend on the interaction of a bacterial virus and a microorganism. fluorometric data correlated with electro-orientation spe ... | 1999 | 10709463 |
| molecular analysis of microbial community structures in pristine and contaminated aquifers: field and laboratory microcosm experiments. | this study used phylogenetic probes in hybridization analysis to (i) determine in situ microbial community structures in regions of a shallow sand aquifer that were oxygen depleted and fuel contaminated (fc) or aerobic and noncontaminated (nc) and (ii) examine alterations in microbial community structures resulting from exposure to toluene and/or electron acceptor supplementation (nitrate). the latter objective was addressed by using the nc and fc aquifer materials for anaerobic microcosm studie ... | 1999 | 10224013 |
| effect of temperature on the incubation period and leaf colonization in bacterial blight of anthurium. | abstract effect of temperature on leaf colonization in anthurium blight was studied using a bioluminescent strain of xanthomonas campestris pv. dieffenbachiae. in a susceptible cultivar, colonization of leaf tissues (monitored by detection of bioluminescence) and symptom development (assessed visually) advanced rapidly at higher temperatures. for a susceptible cultivar, there was a linear relationship between degree-days and percent leaf area colonized by the pathogen, indicating that leaf colon ... | 1999 | 18944655 |
| development of bacterial spot on near-isogenic lines of bell pepper carrying gene pyramids composed of defeated major resistance genes. | abstract disease severity caused by races 1 through 6 of xanthomonas campestris pv. vesicatoria on eight near-isogenic lines (isolines) of early calwonder (ecw) with three major resistance genes (bs1, bs2, and bs3) in different combinations was evaluated in the greenhouse and field. strains representing races 1, 3, 4, and 6 caused similar high levels of disease severity, followed by races 2 and 5 on susceptible ecw. race 3 caused severe disease on all isolines lacking resistance gene bs2. race 4 ... | 1999 | 18944663 |
| heterogeneity of xanthomonas campestris pv. hederae strains from araliaceous hosts. | abstract xanthomonas campestris pv. hederae (synonym x. hortorum pv. hederae) strains (59 total) were collected from plants in the araliaceae family. strains were isolated from hedera helix, schefflera arboricola, brassaia actinophylla, and polyscias spp. from florida, california, hawaii, and new zealand. all strains produced yellow mucoid growth; hydrolyzed esculin, starch, casein and gelatin; were pectolytic; produced urease; and grew on minimal media containing asparagine. all bacterial strai ... | 1999 | 18944676 |
| development of a new semiselective medium for isolating xanthomonas campestris pv. manihotis from plant material and soil. | abstract an effective control for bacterial blight of cassava (manihot esculenta), caused by xanthomonas campestris pv. manihotis, requires the use of non-contaminated cuttings and seeds. using classical agar plating techniques for screening planting material for contamination has not been very successful because of the lack of a reliable semiselective agar medium. the pathogen grows slowly on general plating media and is easily overgrown by saprophytic bacteria during isolation from diseased pl ... | 1999 | 18944695 |
| virtual lesion extension: a measure to quantify the effects of bacterial blight on rice leaf co(2) exchange. | abstract virtual lesion extension was proposed as a measure to summarize the effects of foliar diseases with single spreading lesions on co(2)-exchange parameters at the whole-leaf level. visible lesion plus virtual lesion extension constitute a virtual lesion, in which co(2) exchange was postulated to be nil. virtual lesion extension can be derived for each photosynthesis parameter from gas-exchange measurements. using a leaf-shape function, one-dimensional lesion length was translated into two ... | 1999 | 18944707 |
| comparisons of single versus multiple bacterial species on biological control of anthurium blight. | abstract effects of single versus multiple biological control agents (bcas) on suppression of bacterial blight of anthurium were studied using a bioluminescent strain (v108lruh1) of xanthomonas campestris pv. dieffenbachiae. when five bcas (gut3, gut4, gut5, gut6, and gut9) were coinoculated in various combinations with v108lruh1 into filter-sterilized guttation fluids of anthurium plants, a mixture of all five strains or four strains without gut9 was most inhibitory to v108lruh1. none of the in ... | 1999 | 18944748 |
| multiphasic analysis of xanthomonads causing bacterial spot disease on tomato and pepper in the caribbean and central america: evidence for common lineages within and between countries. | abstract four hundred thirty-three xanthomonad strains isolated from tomato or pepper plants from 32 different fields in four caribbean and central american countries were screened for the ability to hydrolyze starch and sodium polypectate and for resistance to copper and streptomycin. of these, 95 representative strains were further characterized by various phnetic tests, and 63 of these strains were then analyzed by genomic fingerprinting. most of the strains (>90%) were tolerant to copper. ho ... | 1999 | 18944779 |
| spider mite-induced (3s)-(e)-nerolidol synthase activity in cucumber and lima bean. the first dedicated step in acyclic c11-homoterpene biosynthesis. | many plant species respond to herbivory with de novo production of a mixture of volatiles that attracts carnivorous enemies of the herbivores. one of the major components in the blend of volatiles produced by many different plant species in response to herbivory by insects and spider mites is the homoterpene 4,8-dimethyl-1,3(e), 7-nonatriene. one study (j. donath, w. boland [1995] phytochemistry 39: 785-790) demonstrated that a number of plant species can convert the acyclic sesquiterpene alcoho ... | 1999 | 10482672 |
| an outbreak of nonflocculating catabolic populations caused the breakdown of a phenol-digesting activated-sludge process. | activated sludge was fed phenol as the sole carbon source, and the phenol-loading rate was increased stepwise from 0.5 to 1.0 g liter-1 day-1 and then to 1.5 g liter-1 day-1. after the loading rate was increased to 1.5 g liter-1 day-1, nonflocculating bacteria outgrew the sludge, and the activated-sludge process broke down within 1 week. the bacterial population structure of the activated sludge was analyzed by temperature gradient gel electrophoresis (tgge) of pcr-amplified 16s ribosomal dna (r ... | 1999 | 10388669 |
| genetic evidence for the role of gdp-mannose in plant ascorbic acid (vitamin c) biosynthesis. | vitamin c (l-ascorbic acid; asa) acts as a potent antioxidant and cellular reductant in plants and animals. asa has long been known to have many critical physiological roles in plants, yet its biosynthesis is only currently being defined. a pathway for asa biosynthesis that features gdp-mannose and l-galactose has recently been proposed for plants. we have isolated a collection of asa-deficient mutants of arabidopsis thaliana that are valuable tools for testing of an asa biosynthetic pathway. th ... | 1999 | 10097187 |
| differential induction of plant volatile biosynthesis in the lima bean by early and late intermediates of the octadecanoid-signaling pathway. | plants are able to respond to herbivore damage with de novo biosynthesis of an herbivore-characteristic blend of volatiles. the signal transduction initiating volatile biosynthesis may involve the activation of the octadecanoid pathway, as exemplified by the transient increase of endogenous jasmonic acid (ja) in leaves of lima bean (phaseolus lunatus) after treatment with the macromolecular elicitor cellulysin. within this pathway lima bean possesses at least two different biologically active si ... | 1999 | 10482670 |
| genetic complexity of pathogen perception by plants: the example of rcr3, a tomato gene required specifically by cf-2. | genetic analysis of plant-pathogen interactions has demonstrated that resistance to infection is often determined by the interaction of dominant plant resistance (r) genes and dominant pathogen-encoded avirulence (avr) genes. it was postulated that r genes encode receptors for avr determinants. a large number of r genes and their cognate avr genes have now been analyzed at the molecular level. r gene loci are extremely polymorphic, particularly in sequences encoding amino acids of the leucine-ri ... | 2000 | 10922039 |
| bacterial quorum sensing in pathogenic relationships. | 2000 | 10948095 | |
| induced plant defense responses against chewing insects. ethylene signaling reduces resistance of arabidopsis against egyptian cotton worm but not diamondback moth. | the induction of plant defenses by insect feeding is regulated via multiple signaling cascades. one of them, ethylene signaling, increases susceptibility of arabidopsis to the generalist herbivore egyptian cotton worm (spodoptera littoralis; lepidoptera: noctuidae). the hookless1 mutation, which affects a downstream component of ethylene signaling, conferred resistance to egyptian cotton worm as compared with wild-type plants. likewise, ein2, a mutant in a central component of the ethylene signa ... | 2000 | 11080278 |
| a subtilisin-like serine protease involved in the regulation of stomatal density and distribution in arabidopsis thaliana. | stomata are specialized cellular structures in the epidermis of aerial plant organs that control gas exchange (h(2)o release and co(2) uptake) between leaves and the atmosphere by modulating the aperture of a pore flanked by two guard cells. stomata are nonrandomly distributed, and their density is controlled by endogenous and environmental factors. to gain insight into the molecular mechanisms regulating stomatal distribution, arabidopsis thaliana mutants with altered stomatal characteristics w ... | 2000 | 10809670 |
| a rapid bioassay for screening rhizosphere microorganisms for their ability to induce systemic resistance. | abstract we developed a rapid and miniaturized bioassay for screening large numbers of rhizosphere microorganisms for their ability to induce systemic resistance to bacterial leaf spot of radish caused by xanthomonas campestris pv. armoraciae. in this bioassay, pantoea agglomerans strain e278ar controlled symptoms of disease as effectively as 2,6-dichloroisonicotinic acid when applied to the roots of seedlings produced in growth pouches in a soilless system. e278ar essentially did not migrate fr ... | 2000 | 18944580 |
| evaluation of proposed amended names of several pseudomonads and xanthomonads and recommendations. | abstract in 1980, over 90% of all plant-pathogenic pseudomonads and xanthomonads were lumped into pseudomonas syringae and xanthomonas campestris, respectively, as pathovars. the term "pathovar" was created to preserve the name of plant pathogens, but has no official standing in nomenclature. proposals to elevate and rename several pathovars of the genera pseudomonas and xanthomonas to the rank of species has caused great confusion in the literature. we believe the following changes have merit a ... | 2000 | 18944610 |
| lipopolysaccharides and plant responses to phytopathogenic bacteria. | abstract treatment of the leaves of pepper (capsicum annuum) cv. ecw10r with lipopolysaccharides (lps) from both plant pathogenic and enteric bacteria alters several aspects of the plant response to subsequent inoculation with phytopathogenic xanthomonads. lps pre-treatment prevents the hypersensitive reaction caused by strains of xanthomonas campestris pv. vesicatoria carrying the avirulence gene avrbs1 (a gene-for-gene interaction) and by x. campestris pv. campestris (a non-host interaction). ... | 2000 | 20572947 |
| how the bacterial plant pathogen xanthomonas campestris pv. vesicatoria conquers the host. | abstract xanthomonas campestris pv. vesicatoria (xcv) is the causal agent of bacterial spot disease on pepper and tomato. pathogenicity on susceptible plants and the induction of the hypersensitive reaction (hr) on resistant plants requires a number of genes, designated hrp, most of which are clustered in a 23-kb chromosomal region. nine hrp genes encode components of a type iii protein secretion apparatus that is conserved in gram-negative plant and animal pathogenic bacteria. we have recently ... | 2000 | 20572953 |
| salicylic acid mediated by the oxidative burst is a key molecule in local and systemic responses of cotton challenged by an avirulent race of xanthomonas campestris pv malvacearum. | we analyzed the production of reactive oxygen species, the accumulation of salicylic acid (sa), and peroxidase activity during the incompatible interaction between cotyledons of the cotton (gossypium hirsutum) cv reba b50/xanthomonas campestris pv malvacearum (xcm) race 18. sa was detected in petioles of cotyledons 6 h after infection and 24 h post inoculation in cotyledons and untreated leaves. the first peak of sa occurred 3 h after generation of superoxide (o(2)(.-)), and was inhibited by inf ... | 2000 | 10712539 |
| identification of two novel hrp-associated genes in the hrp gene cluster of xanthomonas oryzae pv. oryzae. | we have cloned a hrp gene cluster from xanthomonas oryzae pv. oryzae. bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (hr) on the appropriate resistant cultivars of rice and the nonhost plant tomato. a 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpb operon was determined. the region was most similar to hrp genes from xanthomonas campestris pv. vesicatoria and r ... | 2000 | 10714988 |
| secreted enzymatic activities of wild-type and pild-deficient legionella pneumophila. | legionella pneumophila, the agent of legionnaires' disease, is an intracellular pathogen of protozoa and macrophages. previously, we had determined that the legionella pild gene is involved in type iv pilus biogenesis, type ii protein secretion, intracellular infection, and virulence. since the loss of pili and a protease do not account for the infection defect exhibited by a pild-deficient strain, we sought to define other secreted proteins absent in the mutant. based upon the release of p-nitr ... | 2000 | 10722574 |
| bordetella pertussis tonb, a bvg-independent virulence determinant. | in gram-negative bacteria, high-affinity iron uptake requires the tonb/exbb/exbd envelope complex to release iron chelates from their specific outer membrane receptors into the periplasm. based on sequence similarities, the bordetella pertussis tonb exbb exbd locus was identified on a cloned dna fragment. the tight organization of the three genes suggests that they are cotranscribed. a putative fur-binding sequence located upstream from tonb was detected in a fur titration assay, indicating that ... | 2000 | 10722583 |
| type iv pilus genes pila and pilc of pseudomonas stutzeri are required for natural genetic transformation, and pila can be replaced by corresponding genes from nontransformable species. | pseudomonas stutzeri lives in terrestrial and aquatic habitats and is capable of natural genetic transformation. after transposon mutagenesis, transformation-deficient mutants were isolated from a p. stutzeri jm300 strain. in one of them a gene which coded for a protein with 75% amino acid sequence identity to pilc of pseudomonas aeruginosa, an accessory protein for type iv pilus biogenesis, was inactivated. the presence of type iv pili was demonstrated by susceptibility to the type iv pilus-dep ... | 2000 | 10735861 |
| functional analysis of gapped microbial genomes: amino acid metabolism of thiobacillus ferrooxidans. | a gapped genome sequence of the biomining bacterium thiobacillus ferrooxidans strain atcc23270 was assembled from sheared dna fragments (3.2-times coverage) into 1,912 contigs. a total of 2,712 potential genes (orfs) were identified in 2.6 mbp (megabase pairs) of thiobacillus genomic sequence. of these genes, 2,159 could be assigned functions by using the wit-pro/emp genome analysis system, most with a high degree of certainty. nine hundred of the genes have been assigned roles in metabolic path ... | 2000 | 10737802 |
| superoxide dismutase activity in pseudomonas putida affects utilization of sugars and growth on root surfaces. | to investigate the role of superoxide dismutases (sod) in root colonization and oxidative stress, mutants of pseudomonas putida lacking manganese-superoxide dismutase (mnsod) (soda), iron-superoxide dismutase (fesod) (sodb), or both were generated. the soda sodb mutant did not grow on components washed from bean root surfaces or glucose in minimal medium. the sodb and soda sodb mutants were more sensitive than wild type to oxidative stress generated within the cell by paraquat treatment. in sing ... | 2000 | 10742227 |
| mutants of xanthomonas oryzae pv. oryzae deficient in general secretory pathway are virulence deficient and unable to secrete xylanase. | xanthomonas oryzae pv. oryzae (xoo) causes bacterial leaf blight, a serious disease of rice. a virulence- and xylanase-deficient mutant of xoo was isolated following ethyl methane sulfonate (ems) mutagenesis. a cosmid clone that restored virulence and xylanase secretion was obtained from a genomic library by functional complementation. transposon mutagenesis and marker exchange studies revealed genes on the cloned dna that were required for xylanase production and virulence. sequence analysis wi ... | 2000 | 10755302 |
| genotypic characterization of xanthomonad strains isolated from passion fruit plants (passiflora spp.) and their relatedness to different xanthomonas species. | the genetic diversity of 55 xanthomonad strains isolated from passion fruit plants (passiflora spp.) and identified as xanthomonas campestris pv. passiflorae was initially assessed by randomly amplified polymorphic dna (rapd) analysis. the strains showed a high level of polymorphism with almost unique fingerprints. fifteen clusters with a similarity of approximately 70% were identified, three of which were prevalent. there was a correlation between the clusters and the geographic origin of the s ... | 2000 | 10758892 |
| [rapd-markers linked to the locus for resistance to the race 4 pathogen for black rot, xanthomonas campestris pv. campestris (pamm.) dow., in brassica rapa l]. | association between the rapd markers and the resistance to race 4 of the black rot causative agent was studied in brassica rapa l. experiments were carried out using doubled haploid lines, obtained via crosses between the race 4-susceptible fodder turnip and resistant pak-choi, and the f2 progeny of the crosses between the doubled haploid lines with contrasting resistance. the we(22)980 rapd marker inherited from the pak-choi and associated with the clubroot susceptibility was also linked to the ... | 2000 | 10779910 |
| the pseudomonas syringae hrp pathogenicity island has a tripartite mosaic structure composed of a cluster of type iii secretion genes bounded by exchangeable effector and conserved effector loci that contribute to parasitic fitness and pathogenicity in plants. | the plant pathogenic bacterium pseudomonas syringae is divided into pathovars differing in host specificity, with p. syringae pv. syringae (psy) and p. syringae pv. tomato (pto) representing particularly divergent pathovars. p. syringae hrp/hrc genes encode a type iii protein secretion system that appears to translocate avr and hop effector proteins into plant cells. dna sequence analysis of the hrp/hrc regions in psy 61, psy b728a, and pto dc3000 has revealed a hrp pathogenicity island (pai) wi ... | 2000 | 10781092 |
| prephenate dehydratase from the aphid endosymbiont (buchnera) displays changes in the regulatory domain that suggest its desensitization to inhibition by phenylalanine. | buchnera aphidicola, the prokaryotic endosymbiont of aphids, complements dietary deficiencies with the synthesis and provision of several essential amino acids. we have cloned and sequenced a region of the genome of b. aphidicola isolated from acyrthosiphon pisum which includes the two-domain aroq/phea gene. this gene encodes the bifunctional chorismate mutase-prephenate dehydratase protein, which plays a central role in l-phenylalanine biosynthesis. two changes involved in the overproduction of ... | 2000 | 10781569 |
| structure of the o-chain polysaccharide of the lipopolysaccharide of xanthomonas campestris pv. manihotis gspb 2755 and gspb 2364. | the o-chain polysaccharide of the lipopolysaccharide of xanthomonas campestris pv. manihotis strains gspb 2755 and gspb 2364 was studied by sugar and methylation analyses and 1h and 13c nmr spectroscopy, including 2d cosy, tocsy, noesy, and h-detected 1h, 13c heteronuclear multiple-quantum coherence (hmqc) experiments. the polysaccharide was found to contain l-rhamnose and l-xylose in the ratio 3:1, and the following structure of the tetrasaccharide repeating unit was established: [formula: see ... | 2000 | 10782308 |
| novel genes involved in the regulation of pathogenicity factor production within the rpf gene cluster of xanthomonas campestris. | the synthesis of extracellular enzymes and extracellular polysaccharide (eps) in xanthomonas campestris pathovar campestris (xcc) is subject to co-ordinate regulation by a cluster of genes called rpf (for regulation of pathogenicity factors). these genes are located within a 21.9 kb region of the chromosome isolated as the cosmid clone pij3020. the genes in the left-hand section of this region of the chromosome have previously been characterized. this paper reports on the genes in the right-hand ... | 2000 | 10784047 |
| design and evaluation of a lactobacillus manihotivorans species-specific rrna-targeted hybridization probe and its application to the study of sour cassava fermentation. | based on 16s rrna sequence comparison, we have designed a 20-mer oligonucleotide that targets a region specific to the species lactobacillus manihotivorans recently isolated from sour cassava fermentation. the probe recognized the rrna obtained from all the l. manihotivorans strains tested but did not recognize 56 strains of microorganisms from culture collections or directly isolated from sour cassava, including 29 species of lactic acid bacteria. this probe was then successfully used in quanti ... | 2000 | 10788405 |
| identification of the pgmg gene, encoding a bifunctional protein with phosphoglucomutase and phosphomannomutase activities, in the gellan gum-producing strain sphingomonas paucimobilis atcc 31461. | the pgmg gene of sphingomonas paucimobilis atcc 31461, the industrial gellan gum-producing strain, was cloned and sequenced. it encodes a 50,059-da polypeptide that has phosphoglucomutase (pgm) and phosphomannomutase (pmm) activities and is 37 to 59% identical to other bifunctional proteins with pgm and pmm activities from gram-negative species, including pseudomonas aeruginosa algc. purified pgmg protein showed a marked preference for glucose-1-phosphate (g1p); the catalytic efficiency was abou ... | 2000 | 10788412 |
| the tomato ethylene receptors nr and leetr4 are negative regulators of ethylene response and exhibit functional compensation within a multigene family. | the plant hormone ethylene is involved in many developmental processes, including fruit ripening, abscission, senescence, and leaf epinasty. tomato contains a family of ethylene receptors, designated leetr1, leetr2, nr, leetr4, and leetr5, with homology to the arabidopsis etr1 ethylene receptor. transgenic plants with reduced leetr4 gene expression display multiple symptoms of extreme ethylene sensitivity, including severe epinasty, enhanced flower senescence, and accelerated fruit ripening. the ... | 2000 | 10792050 |
| genetic polymorphism in xanthomonas albilineans strains originating from 11 geographical locations, revealed by two dna probes. | two dna fragments from xanthomonas albilineans were used as probes to study the molecular diversity among strains of this pathogen. two serologically distinct groups, serovars i and ii, could be differentiated by hybridization to the probes. these probes, designated 830 and 838, were cloned after subtractive dna hybridization of common sequences of xanthomonas campestris pv. vasculorum from a serovar i strain of x. albilineans. they did not hybridize to the dna of several other xanthomonads or t ... | 2000 | 10792648 |
| structure elucidation of the o-chain from the major lipopolysaccharide of the xanthomonas campestris strain 642. | a novel o-polysaccharide consisting of d-xylp and l-rhap in the molar ratio of 1:2.5 was identified as the major component in the lipopolysaccharide fraction of xanthomonas campestris strain 642, which is responsible for a new bacterial disease of the strawberry plant. its structure was mainly determined using chemical analysis, smith degradation and 1d and 2d nmr spectroscopy experiments as: carbohydrate sequence [see text]. | 2000 | 10795814 |
| response to xanthomonas campestris pv. vesicatoria in tomato involves regulation of ethylene receptor gene expression. | although ethylene regulates a wide range of defense-related genes, its role in plant defense varies greatly among different plant-microbe interactions. we compared ethylene's role in plant response to virulent and avirulent strains of xanthomonas campestris pv. vesicatoria in tomato (lycopersicon esculentum mill.). the ethylene-insensitive never ripe (nr) mutant displays increased tolerance to the virulent strain, while maintaining resistance to the avirulent strain. expression of the ethylene r ... | 2000 | 10806227 |
| cloning and expression of ntnd, encoding a novel nad(p)(+)-independent 4-nitrobenzyl alcohol dehydrogenase from pseudomonas sp. strain tw3. | pseudomonas sp. strain tw3 is able to metabolize 4-nitrotoluene to 4-nitrobenzoate and toluene to benzoate aerobically via a route analogous to the upper pathway of the tol plasmids. we report the cloning and characterization of a benzyl alcohol dehydrogenase gene (ntnd) which encodes the enzyme for the catabolism of 4-nitrobenzyl alcohol and benzyl alcohol to 4-nitrobenzaldehyde and benzaldehyde, respectively. the gene is located downstream of the previously reported ntn gene cluster. ntnd bear ... | 2000 | 10809692 |
| prey range characterization, ribotyping, and diversity of soil and rhizosphere bdellovibrio spp. isolated on phytopathogenic bacteria. | thirty new bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. thirteen soil and seven common bean rhizosphere bdellovibrio strains were isolated when pseudomonas corrugata was used as prey; seven and two soil strains were isolated when erwinia carotovora subsp ... | 2000 | 10831412 |
| the exbd2 gene as well as the iron-uptake genes tonb, exbb and exbd1 of xanthomonas campestris pv. campestris are essential for the induction of a hypersensitive response on pepper (capsicum annuum). | the tonb, exbb and exbd1 genes of xanthomonas campestris pv. campestris are essential for ferric iron uptake. in contrast, the exbd2 gene located in the same gene cluster is not essential. mutational analysis revealed that the ferric-iron-uptake genes tonb, exbb and exbd1 are necessary for the induction of a hypersensitive response (hr) on the nonhost plant pepper (capsicum annuum) and the induction of typical black rot symptoms on the host plant cauliflower (brassica oleracea). again, the exbd2 ... | 2000 | 10832632 |
| identification of sinorhizobium meliloti genes regulated during symbiosis. | rna fingerprinting by arbitrarily primed pcr was used to isolate sinorhizobium meliloti genes regulated during the symbiotic interaction with alfalfa (medicago sativa). sixteen partial cdnas were isolated whose corresponding genes were differentially expressed between symbiotic and free-living conditions. thirteen sequences corresponded to genes up-regulated during symbiosis, whereas three were instead repressed during establishment of the symbiotic interaction. seven cdnas corresponded to known ... | 2000 | 10850975 |
| role of the dpr product in oxygen tolerance in streptococcus mutans. | we have previously identified and characterized the alkyl hydroperoxide reductase of streptococcus mutans, which consists of two components, nox-1 and ahpc. deletion of both nox-1 and ahpc had no effect on the sensitivity of s. mutans to cumene hydroperoxide or h(2)o(2), implying that the existence of another antioxidant system(s) independent of the nox-1-ahpc system compensates for the deficiency. here, a new antioxidant gene (dpr for dps-like peroxide resistance gene) was isolated from the s. ... | 2000 | 10850989 |
| marinomonas mediterranea mmb-1 transposon mutagenesis: isolation of a multipotent polyphenol oxidase mutant. | marinomonas mediterranea is a melanogenic marine bacterium expressing a multifunctional polyphenol oxidase (ppo) able to oxidize substrates characteristic for laccases and tyrosinases, as well as produce a classical tyrosinase. a new and quick method has been developed for screening laccase activity in culture plates to detect mutants differentially affected in this ppo activity. transposon mutagenesis has been applied for the first time to m. mediterranea by using different minitransposons load ... | 2000 | 10850991 |
| mutations in oxyr resulting in peroxide resistance in xanthomonas campestris. | a spontaneous xanthomonas campestris pv. phaseoli h(2)o(2)-resistant mutant emerged upon selection with 1 mm h(2)o(2). in this report, we show that growth of this mutant under noninducing conditions gave high levels of catalase, alkyl hydroperoxide reductase (ahpc and ahpf), and oxyr. the h(2)o(2) resistance phenotype was abolished in oxyr-minus derivatives of the mutant, suggesting that elevated levels and mutations in oxyr were responsible for the phenotype. nucleotide sequence analysis of the ... | 2000 | 10851004 |
| virulence of the phytopathogen pseudomonas syringae pv. maculicola is rpon dependent. | we cloned the rpon (ntra and glnf) gene encoding sigma(54) from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. the p. syringae es4326 rpon gene complemented pseudomonas aeruginosa, escherichia coli, and klebsiella aerogenes rpon mutants for a variety of rpon mutant phenotypes, including the inability to utilize nitrate as sole nitrogen source. dna sequence analysis of the p. syringae es4326 rpon gene revealed that the deduced amino acid sequence was most similar (86% identi ... | 2000 | 10852883 |
| the alternative sigma factor rpon is required for hrp activity in pseudomonas syringae pv. maculicola and acts at the level of hrpl transcription. | beta-glucuronidase (uida) reporter gene fusions were constructed for the hrpz, hrpl, and hrps genes from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. these reporters, as well as an avrrpt2-uida fusion, were used to measure transcriptional activity in es4326 and a es4326 rpon mutant. rpon was required for the expression of avrrpt2, hrpz, and hrpl in vitro in minimal media and in vivo when infiltrated into arabidopsis thaliana leaves. in contrast, the expression of hrps was ... | 2000 | 10852884 |
| importance of holotoxin assembly in ptl-mediated secretion of pertussis toxin from bordetella pertussis. | we examined the structural components of pertussis toxin that are required for efficient export from bordetella pertussis via the ptl system, a member of the type iv family of macromolecular transporters. first, we constructed a strain of b. pertussis that contains a functional ptl system but does not produce pertussis toxin. plasmids which express either the s1 subunit or the b oligomer were then introduced into this strain. we found that the b oligomer of the toxin is not secreted in the absen ... | 2000 | 10858221 |
| influence of deletions within domain ii of exotoxin a on its extracellular secretion from pseudomonas aeruginosa. | pseudomonas aeruginosa is a gram-negative bacterium that secretes many proteins into the extracellular medium via the xcp machinery. this pathway, conserved in gram-negative bacteria, is called the type ii pathway. the exoproteins contain information in their amino acid sequence to allow targeting to their secretion machinery. this information may be present within a conformational motif. the nature of this signal has been examined for p. aeruginosa exotoxin a (pe). previous studies failed to id ... | 2000 | 10869085 |
| bioaugmentation of activated sludge by an indigenous 3-chloroaniline-degrading comamonas testosteroni strain, i2gfp. | a strain identified as comamonas testosteroni i2 was isolated from activated sludge and found to be able to mineralize 3-chloroaniline (3-ca). during the mineralization, a yellow intermediate accumulated temporarily, due to the distal meta-cleavage of chlorocatechol. this strain was tested for its ability to clean wastewater containing 3-ca upon inoculation into activated sludge. to monitor its survival, the strain was chromosomally marked with the gfp gene and designated i2gfp. after inoculatio ... | 2000 | 10877785 |
| molecular analysis of surfactant-driven microbial population shifts in hydrocarbon-contaminated soil. | we analyzed the impact of surfactant addition on hydrocarbon mineralization kinetics and the associated population shifts of hydrocarbon-degrading microorganisms in soil. a mixture of radiolabeled hexadecane and phenanthrene was added to batch soil vessels. witconol sn70 (a nonionic, alcohol ethoxylate) was added in concentrations that bracketed the critical micelle concentration (cmc) in soil (cmc') (determined to be 13 mg g(-1)). addition of the surfactant at a concentration below the cmc' (2 ... | 2000 | 10877792 |
| variation among strains of xanthomonas campestris pv. vasculorum from mauritius and other countries based on fatty acid analysis. | fatty acid profiling was used to study variation amongst strains of xanthomonas campestris pv. vasculorum (xcv). they could be divided into five groups using cellular fatty acid profiles. group a strains represent a new and little known taxon and all came from plants of broom bamboo (thysanolaena maxima) from mauritius. group b strains included the xcv pathotype reference strain and were from palms, broom bamboo and sugarcane from mauritius, reunion and australia. group c contained southern afri ... | 2000 | 10879989 |
| cultivar-specific avirulence and virulence functions assigned to avrpphf in pseudomonas syringae pv. phaseolicola, the cause of bean halo-blight disease. | the avrpphf gene was cloned from pseudomonas syringae pathovar phaseolicola (pph:) races 5 and 7, based on its ability to confer avirulence towards bean cultivars carrying the r1 gene for halo-blight resistance, such as red mexican. avrpphf comprised two open reading frames, which were both required for function, and was located on a 154 kb plasmid (pav511) in pph: strain rw60 of pph:, lacking pav511, displayed a loss in virulence to a range of previously susceptible cultivars such as tendergree ... | 2000 | 10880434 |
| [major-polygene effect analysis of resistance to bacterial blight (xanthomonas campestris pv. oryzae) in rice]. | five crosses between resistance and susceptible were analyzed to study major-polygene effect using major-polygene mixed mode. the result showed that 3 of 5 crosses were controlled by both major gene and polygene. in addition, there were large variation of additive effect, variance as well as heredity of major gene polygene in 3 crosses. major gene was predominant in resistant variation, but durability should be considered. we suggested that construct major-polygene system be constructed in the l ... | 2000 | 10883537 |
| enhancement of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in arabidopsis thaliana. | the plant-signaling molecules salicylic acid (sa) and jasmonic acid (ja) play an important role in induced disease resistance pathways. cross-talk between sa- and ja-dependent pathways can result in inhibition of ja-mediated defense responses. we investigated possible antagonistic interactions between the sa-dependent systemic acquired resistance (sar) pathway, which is induced upon pathogen infection, and the ja-dependent induced systemic resistance (isr) pathway, which is triggered by nonpatho ... | 2000 | 10890883 |
| sequence and molecular analysis of the rpoa cluster genes from xanthomonas campestris pv. campestris. | the xanthomonas campestris rpsm (s13)-rpsk (s11)-rpsd (s4)-rpoa (alpha)-rplq (l17) cluster, encoding rna polymerase alpha-subunit and four ribosomal proteins, reside in a 3164-bp dna region. the n-terminal sequence of the authentic alpha-protein determined chemically matches that predicted from the nucleotide sequence. rplq is monocistronic, instead of being co-transcribed with the other genes as in escherichia coli. antiserum against the his-tagged alpha-protein cross-reacted with the e. coli a ... | 2000 | 10899600 |
| requirement of the pseudomonas aeruginosa tonb gene for high-affinity iron acquisition and infection. | to investigate the contribution of the tonb protein to high-affinity iron acquisition in pseudomonas aeruginosa, we constructed tonb-inactivated mutants from strain pao1 and its derivative deficient in producing the siderophores pyoverdin and pyochelin. the tonb mutants could not grow in a free-iron-restricted medium prepared by apotransferrin addition, even though the medium was supplemented with each purified siderophore or with a heme source (hemoglobin or hemin). the tonb inactivation was sh ... | 2000 | 10899848 |
| role of phosphoglucomutase of bordetella bronchiseptica in lipopolysaccharide biosynthesis and virulence. | the phosphoglucomutase (pgm)-encoding gene of bordetella bronchiseptica is required for lipopolysaccharide (lps) biosynthesis. an insertion mutant of the wild-type b. bronchiseptica strain bb7865 which disrupted lps biosynthesis was created and characterized (bb7865pgm). genetic analysis of the mutated gene showed it shares high identity with pgm genes of various bacterial species and forms part of an operon which also encompasses the gene encoding phosphoglucose isomerase. functional assays for ... | 2000 | 10899872 |
| a protease-resistant catalase, kata, released upon cell lysis during stationary phase is essential for aerobic survival of a pseudomonas aeruginosa oxyr mutant at low cell densities. | a pseudomonas aeruginosa oxyr mutant was dramatically sensitive to h(2)o(2), despite possessing wild-type catalase activity. oxygen-dependent oxyr phenotypes also included an inability to survive aerobic serial dilution in luria broth and to resist aminoglycosides. plating the oxyr mutant after serial dilution in its own spent culture supernatant, which contained the major catalase kata, or under anaerobic conditions allowed for survival. kata was resistant to sodium dodecyl sulfate, proteinase ... | 2000 | 10913089 |
| novel insertion sequence elements associated with genetic heterogeneity and phenotype conversion in ralstonia solanacearum. | three insertion sequences (is) elements were isolated from the phytopathogen ralstonia solanacearum. southern hybridization using these is elements as probes revealed hybridization profiles that varied greatly between different strains of the pathogen. during a spontaneous phenotype conversion event, the promoter of the phca gene was interrupted by one of these is elements. | 2000 | 10913109 |
| effect of field inoculation with sinorhizobium meliloti l33 on the composition of bacterial communities in rhizospheres of a target plant (medicago sativa) and a non-target plant (chenopodium album)-linking of 16s rrna gene-based single-strand conformation polymorphism community profiles to the diversity of cultivated bacteria. | fourteen weeks after field release of luciferase gene-tagged sinorhizobium meliloti l33 in field plots seeded with medicago sativa, we found that the inoculant also occurred in bulk soil from noninoculated control plots. in rhizospheres of m. sativa plants, s. meliloti l33 could be detected in noninoculated plots 12 weeks after inoculation, indicating that growth in the rhizosphere preceded spread into bulk soil. to determine whether inoculation affected bacterial diversity, 1,119 bacteria were ... | 2000 | 10919821 |
| pseudomonas syringae hrp type iii secretion system and effector proteins. | pseudomonas syringae is a member of an important group of gram-negative bacterial pathogens of plants and animals that depend on a type iii secretion system to inject virulence effector proteins into host cells. in p. syringae, hrp/hrc genes encode the hrp (type iii secretion) system, and avirulence (avr) and hrp-dependent outer protein (hop) genes encode effector proteins. the hrp/hrc genes of p. syringae pv syringae 61, p. syringae pv syringae b728a, and p. syringae pv tomato dc3000 are flanke ... | 2000 | 10922033 |
| molecular and cell biology aspects of plague. | a 70-kb virulence plasmid (sometimes called pyv) enables yersinia spp. to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, a system consisting of secreted proteins called yops and their dedicated type iii secretion apparatus called ysc. the ysc apparatus forms a channel composed of 29 proteins. of these, 10 have counterparts in almost every type iii system. secretion of some yops requires the assistance, in the bacterial cytosol, of small individual chapero ... | 2000 | 10922034 |
| parameters affecting gene expression from the pm promoter in gram-negative bacteria. | the pm promoter inserted chromosomally or in broad-host-range replicons based on plasmid rsf1010 or rk2 are useful systems for both high- and low-level expression of cloned genes in several gram-negative bacterial species. the positive pm regulator xyls is activated by certain substituted benzoic acid derivatives, and here we show that these effectors induce expression of pm at similar relative ranking levels in both escherichia coli and pseudomonas aeruginosa however, the kinetics of expression ... | 2000 | 10935724 |
| genomic and phenotypic characterization of xanthomonas cynarae sp. nov., a new species that causes bacterial bract spot of artichoke (cynara scolymus l.). | a bacterial disease of artichoke (cynara scolymus l.) was first observed in 1954 in brittany and the loire valley, france. this disease causes water-soaked spots on bracts and depreciates marketability of the harvest. ten strains of the pathogen causing bacterial spot of artichoke, previously identified as a member of the genus xanthomonas, were characterized and compared with type and pathotype strains of the 20 xanthomonas species using a polyphasic study including both phenotypic and genomic ... | 2000 | 10939652 |