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evidence for the involvement of an oxidative stress in the initiation of infection of pear by erwinia amylovora.involvement of an oxidative burst, usually related to incompatible plant/pathogen interactions leading to hypersensitive reactions, was investigated with erwinia amylovora, the causal agent of fire blight of maloideae subfamily of rosaceae, in interaction with pear (pyrus communis; compatible situation) and tobacco (nicotiana tabacum; incompatible situation). as expected, this necrogenic bacterium induced in tobacco a sustained production of superoxide anion, lipid peroxidation, electrolyte leak ...200111299395
effects of urate, a natural inhibitor of peroxynitrite-mediated toxicity, in the response of arabidopsis thaliana to the bacterial pathogen pseudomonas syringae.urate, a natural peroxynitrite scavenger, has been used to investigate the possible role of peroxynitrite during plant-pathogen interactions. urate greatly reduced lesion formation in arabidopsis leaves treated with an abiotic peroxynitrite-generating system or with a peroxynitrite solution, indicating that it can act as an effective scavenger in planta. in the interaction with the avirulent pseudomonas syringae pv. phaseolicola (avrrpm1+), cell death in the inoculated area was strongly reduced ...200111309143
reduced expression of the tomato ethylene receptor gene leetr4 enhances the hypersensitive response to xanthomonas campestris pv. vesicatoria.the hypersensitive response (hr) involves rapid death of cells at the site of pathogen infection and is thought to limit pathogen growth through the plant. ethylene regulates senescence and developmental programmed cell death, but its role in hypersensitive cell death is less clear. expression of two ethylene receptor genes, nr and leetr4, is induced in tomato (lycopersicon esculentum cv. mill) leaves during an hr to xanthomonas campestris pv. vesicatoria, with the greatest increase observed in ...200111310736
stable transformation of the xylella fastidiosa citrus variegated chlorosis strain with oric plasmids.xylella fastidiosa is a gram-negative, xylem-limited bacterium affecting economically important crops (e.g., grapevine, citrus, and coffee). the citrus variegated chlorosis (cvc) strain of x. fastidiosa is the causal agent of this severe disease of citrus in brazil and represents the first plant-pathogenic bacterium for which the genome sequence was determined. plasmids for the cvc strain of x. fastidiosa were constructed by combining the chromosomal replication origin (oric) of x. fastidiosa wi ...200111319110
identification and characterization of a developmentally regulated protein, esha, required for sporogenic hyphal branches in streptomyces griseus.to identify sporulation-specific proteins that might serve as targets of developmental regulatory factors in streptomyces, we examined total proteins of streptomyces griseus by two-dimensional gel electrophoresis. among five proteins that were present at high levels during sporulation but absent from vegetative cells, two of the proteins, p3 and p4, were absent from developmental mutants that undergo aberrant morphogenesis. the deduced amino acid sequence of the gene that encodes p3 (esha) showe ...200111325927
roles of aconitase in growth, metabolism, and morphological differentiation of streptomyces coelicolor.the studies of aconitase presented here, along with those of citrate synthase (p. h. viollier, w. minas, g. e. dale, m. folcher, and c. j. thompson, j. bacteriol. 183:3184-3192, 2001), were undertaken to investigate the role of the tricarboxylic acid (tca) cycle in streptomyces coelicolor development. a single aconitase activity (acoa) was detected in protein extracts of cultures during column purification. the deduced amino acid sequence of the cloned acoa gene constituted the n-terminal sequen ...200111325949
xanthomonas campestris strain selection for xanthan production from olive mill wastewaters.four xanthomonas campestris strains were tested in olive mill wastewaters (omw) for xanthan production. differences among strains were found in the range of tolerance to omw concentration and xanthan amount obtained. x. campestris nrrl b-1459 s4lii was chosen by its capability for xanthan production from 50-60% omw as the sole nutrient source.200111329685
genetic mapping and functional analysis of the tomato bs4 locus governing recognition of the xanthomonas campestris pv. vesicatoria avrbs4 protein.xanthomonas campestris pv. vesicatoria is the causal agent of bacterial spot disease on pepper (capsicum spp.) and tomato (lycopersicon spp.). analysis of 17 different lycopersicon accessions with avrbs4-expressing x. campestris pv. vesicatoria strains identified 15 resistant and two susceptible tomato genotypes. genetic analysis revealed that avrbs4 recognition in tomato is governed by a single locus, designated bs4 (bacterial spot resistance locus no. 4). amplified fragment length polymorphism ...200111332727
characterization and mutational analysis of three allelic lsc genes encoding levansucrase in pseudomonas syringae.in the plant pathogen pseudomonas syringae pv. glycinea pg4180 and other bacterial species, synthesis of the exopolysaccharide levan is catalyzed by the extracellular enzyme levansucrase. the results of southern blotting and pcr analysis indicated the presence of three levansucrase-encoding genes in strain pg4180: lsca, lscb, and lscc. in this study, lscb and lscc were cloned from a genomic library of strain pg4180. sequence analysis of the two lsc genes showed that they were virtually identical ...200111344135
the effect of olive mill wastewaters variability on xanthan production.xanthan production by xanthomonas campestris from several olive mill wastewaters (omw) was investigated.200111348445
the early stages of filamentous phage philf infection require the host transcription factor, clp.xanthomonas campestris pv. campestris produces great amounts of an exopolysaccharide (eps), xanthan gum. eight eps loci involved in biosynthesis of the eps were previously located in the chromosome map of strain xc17. in this study, the eps8 region was cloned, sequenced and found to contain a crp homologue whose deduced amino acid sequence possesses similarity to that of the cyclic amp receptor protein of bacteria, with the highest identity (97%) being shared with the x. campestris pv. campestri ...200111361081
structural and functional characterization of the lexa gene of xanthomonas campestris pathovar citri.the role of the lexa protein and, specifically, its effect on reca expression were analyzed in xanthomonas campestris pathovar citri (x.c. pv. citri). overexpression of lexa from x.c. pv. citri, in the plant pathogen, as well as in escherichia coli, results in increased sensitivity to the dna-damaging agents mitomycin c and ultraviolet radiation, indicating that the recombinant x.c. pv. citri lexa protein is functional in a different bacterial species. immunoblot analysis revealed that the overe ...200111361343
generation of pcr-based dna fragments for specific detection of streptomyces saraceticus n45.streptomyces saraceticus strain n45, a saprophytic gram-positive bacteria, has been shown to harbor high chitinase activity. due to its potential use in biological control, the cloning of chitinase genes and the development of methods to quickly and precisely detect its presence have become necessary. in this study, pcr-based random amplified polymorphic dna (rapd) and pcr strategies were used to amplify random dna fragments from the genome of s. saraceticus n45. three amplified dna fragments, 4 ...200111370759
the luxm homologue vanm from vibrio anguillarum directs the synthesis of n-(3-hydroxyhexanoyl)homoserine lactone and n-hexanoylhomoserine lactone.vibrio anguillarum, which causes terminal hemorrhagic septicemia in fish, was previously shown to possess a luxri-type quorum-sensing system (vanri) and to produce n-(3-oxodecanoyl)homoserine lactone (3-oxo-c10-hsl). however, a vani null mutant still activated n-acylhomoserine lactone (ahl) biosensors, indicating the presence of an additional quorum-sensing circuit in v. anguillarum. in this study, we have characterized this second system. using high-pressure liquid chromatography in conjunction ...200111371516
requirement for phosphoglucomutase in exopolysaccharide biosynthesis in glucose- and lactose-utilizing streptococcus thermophilus.to study the influence of phosphoglucomutase (pgm) activity on exopolysaccharide (eps) synthesis in glucose- and lactose-growing streptococcus thermophilus, a knockout pgm mutant and a strain with elevated pgm activity were constructed. the pgma gene, encoding pgm in s. thermophilus ly03, was identified and cloned. the gene was functional in escherichia coli and was shown to be expressed from its own promoter. the pgma-deficient mutant was unable to grow on glucose, while the mutation did not af ...200111375188
quantitative pcr method for diagnosis of citrus bacterial canker.for diagnosis of citrus bacterial canker by pcr, an internal standard is employed to ensure the quality of the dna extraction and that proper requisites exist for the amplification reaction. the ratio of pcr products from the internal standard and bacterial target is used to estimate the initial bacterial concentration in citrus tissues with lesions.200111375206
[role of the surface and extracellular substances of the phytopathogenic bacterium xanthomonas campestris in its interactions with cabbage plants].changes in some physiological and biochemical characteristics of cabbage (cv. slava) seedling roots in response to inoculation with the phytopathogen xanthomonas campestris and its surface and extracellular substances were evaluated. seven days after the inoculation, the growth of the roots was slightly suppressed and they contained increased amounts of peroxidase. the effect of the lipopolysaccharides stripped from the cell surface or isolated from the culture liquid of x. campestris was simila ...200111386062
expression of the gum operon directing xanthan biosynthesis in xanthomonas campestris and its regulation in planta.the gum gene cluster of xanthomonas campestris pv. campestris comprises 12 genes whose products are involved in the biosynthesis of the extracellular polysaccharide xanthan. these genes are expressed primarily as an operon from a promoter upstream of the first gene, gumb. although the regulation of xanthan synthesis in vitro has been well studied, nothing is known of its regulation in planta. a reporter plasmid was constructed in which the promoter region of the gum operon was fused to gusa. in ...200111386372
induction of hydroxycinnamoyl-tyramine conjugates in pepper by xanthomonas campestris, a plant defense response activated by hrp gene-dependent and hrp gene-independent mechanisms.inoculation of pepper leaves, capsicum annuum cv. early calwonder ecw 10r, with strains of xanthomonas campestris led to an accumulation of the phenolic conjugates feruloyltyramine (ft) and p-coumaroyltyramine (ct) 24 h postinoculation in nonhost- and gene-for-gene-determined incompatible interactions with x. campestris pv. campestris and x. campestris pv. vesicatoria, respectively. in contrast, neither compound was detected in compatible interactions with x. campestris pv. vesicatoria. the accu ...200111386374
microbial origin of plant-type 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate synthases, exemplified by the chorismate- and tryptophan-regulated enzyme from xanthomonas campestris.enzymes performing the initial reaction of aromatic amino acid biosynthesis, 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate (dahp) synthases, exist as two distinct homology classes. the three classic escherichia coli paralogs are aroa(i) proteins, but many members of the bacteria possess the aroa(ii) class of enzyme, sometimes in combination with aroa(i) proteins. aroa(ii) dahp synthases until now have been shown to be specifically dedicated to secondary metabolism (e.g., formation of ansamy ...200111395471
kinetic analysis of growth and xanthan gum production with xanthomonas campestris on sucrose, using sequentially consumed nitrogen sources.a batch fermentation strategy using xanthomonas campestris atcc 13951 for xanthan gum production has been established in which all essential medium components are supplied at the onset. this has been achieved using sucrose as sole sugar feedstock. sequential consumption of nitrogen sources (soybean hydrolysates, ammonium and nitrate salts) was observed to facilitate the further optimisation of the medium. biomass accumulation was limited by phosphate availability. xanthan yields of more than 60% ...200111398920
complete dna sequence of yersinia enterocolitica serotype 0:8 low-calcium-response plasmid reveals a new virulence plasmid-associated replicon.the complete nucleotide sequence and organization of the yersinia enterocolitica serotype 0:8 low-calcium-response (lcr) plasmid, pyve8081, were determined. the 67,720-bp plasmid encoded all the genes known to be part of the lcr stimulon except for ylpa. eight of 13 intact open reading frames of unknown function identified in pyve8081 had homologues in yersinia pestis plasmid pcd1 or in y. enterocolitica serotype 0:9 plasmid pyve227. a region of approximately 17 kbp showed no dna identity to pcd ...200111402007
characterization and expression of beta-1,3-glucanase genes in peach.beta-1,3-glucanase is one of the pathogenesis-related (pr) proteins involved in plant defense responses. a peach beta-1,3-glucanase gene, designated ppgns1, has been isolated and characterized. the deduced amino acid sequence of the product of ppgns indicates that it is a basic isoform (pi 9.8), and contains a putative signal peptide of 38 amino acids but has no c-terminal extension. amino acid sequence comparisons revealed that ppgns1 is 69% and 67% identical to citrus and soybean beta-1,3-gluc ...200111405630
broad-spectrum antimicrobial activity in vitro of the synthetic peptide d4e1.broad-spectrum antimicrobial activity of a synthetic peptide, d4e1, is documented in this paper. d4e1 inhibited the growth of several fungal phytopathogens belonging to four classes-ascomycetes, basidiomycetes, deuteromycetes, and oomycetes, and two bacterial pathogens, pseudomonas syringae pv. tabaci and xanthomonas campestris pv. malvacearum race 18. the minimum inhibitory concentration (mic) of d4e1 required to completely inhibit the growth of all fungi studied ranged from 4.67 to 25 microm. ...200111409968
incipient erosion of biostabilized sediments examined using particle-field optical holography.laser holography allows images of three-dimensional space at ultra-high resolution to be recorded onto photographic plates. recorded scenes can be "replayed" with a second laser beam into free space and optically "interrogated" using either a microscope or a camera by sequentially focusing on increasing distances from the hologram in the field of view (optical sectioning). from these sections, information on the relative locations and orientation in space of suspended particles as well as the mo ...200111414032
ohrr is a repressor of ohra, a key organic hydroperoxide resistance determinant in bacillus subtilis.bacillus subtilis displays a complex adaptive response to the presence of reactive oxygen species. to date, most proteins that protect against reactive oxygen species are members of the peroxide-inducible perr and sigma(b) regulons. we investigated the function of two b. subtilis homologs of the xanthomonas campestris organic hydroperoxide resistance (ohr) gene. mutational analyses indicate that both ohra and ohrb contribute to organic peroxide resistance in b. subtilis, with the ohra protein pl ...200111418552
influence of acidic exopolysaccharide of xanthomonas campestris ibpm 124 on the kinetic parameters of extracellular bacteriolytic enzymes.interactions of a negatively charged exopolysaccharide of xanthomonas campestris ibpm 124 with its extracellular enzymes (muramidase, endopeptidase, and neutral phosphatase) and also with egg lysozyme, lysostaphin, muramidase of streptomyces globisporus, and a bacteriolytic enzyme complex of streptomyces albus were studied. all these enzymes were positively charged under the conditions of their maximal activity. it was shown that interaction of the acidic exopolysaccharide from x. campestris wit ...200111421816
bacterial ohr and osmc paralogues define two protein families with distinct functions and patterns of expression.xanthomonas campestris ohr (a protein involved in organic peroxide protection) and escherichia coli osmc (an osmotically inducible protein of unknown function) are related proteins. database searches and phylogenetic analyses reveal that ohr and osmc homologues cluster into two related subfamilies of proteins widely distributed in both gram-negative and gram-positive bacteria. to determine if these two subfamilies are functionally distinct, ohr and osmc in pseudomonas aeruginosa (a bacterium wit ...200111429455
two cinnamoyl-coa reductase (ccr) genes from arabidopsis thaliana are differentially expressed during development and in response to infection with pathogenic bacteria.cinnamoyl-coa reductase (ccr; ec 1.2.1.44) catalyses the conversion of cinnamoyl-coas into their corresponding cinnamaldehydes, i.e. the first step of the phenylpropanoid pathway specifically dedicated to the monolignol biosynthetic branch. in previous work, we described the isolation and characterisation of the first cdna encoding ccr in eucalyptus (lacombe, e., hawkins, s., van dorsselaere, j., piquemal, j., goffner, d., poeydomenge, o., boudet, a.m., grima-pettenati, j., 1997. cinnamoyl coa r ...200111430991
eukaryotic features of the xanthomonas type iii effector avrbs3: protein domains involved in transcriptional activation and the interaction with nuclear import receptors from pepper.the avrbs3 protein of the phytopathogenic bacterium xanthomonas campestris pv. vesicatoria is targeted to host-plant cells by the bacterial hrp type iii secretion system. in pepper plants containing the bs3 resistance gene, avrbs3 induces the hypersensitive response (hr). avrbs3 recognition is thought to occur in the plant cell nucleus as hr induction is dependent on nuclear localization signals (nlss) and an acidic transcription activation domain (aad). in a search for avrbs3-interacting pepper ...200111439138
complex regulation of the organic hydroperoxide resistance gene (ohr) from xanthomonas involves ohrr, a novel organic peroxide-inducible negative regulator, and posttranscriptional modifications.analysis of the sequence immediate upstream of ohr revealed an open reading frame, designated ohrr, with the potential to encode a 17-kda peptide with moderate amino acid sequence homology to the marr family of negative regulators of gene expression. ohrr was transcribed as bicistronic mrna with ohr, while ohr mrna was found to be 95% monocistronic and 5% bicistronic with ohrr. expression of both genes was induced by tert-butyl hydroperoxide (tbooh) treatment. high-level expression of ohrr negat ...200111443074
structure-function analysis of bfpb, a secretin-like protein encoded by the bundle-forming-pilus operon of enteropathogenic escherichia coli.production of type iv bundle-forming pili by enteropathogenic escherichia coli (epec) requires bfpb, an outer-membrane lipoprotein and member of the secretin protein superfamily. bfpb was found to compose a ring-shaped, high-molecular-weight outer-membrane complex that is stable in 4% sodium dodecyl sulfate at temperatures of < or = 65 degrees c. chemical cross-linking and immunoprecipitation experiments disclosed that the bfpb multimeric complex interacts with bfpg, and mutational studies showe ...200111466288
the lipopolysaccharides of the phytopathogen xanthomonas campestris pv. campestris induce an oxidative burst reaction in cell cultures of nicotiana tabacum.the lipopolysaccharides (lpsxcc) of the phytopathogenic bacteria xanthomonas campestris pv. campestris (x.c.c.) were purified from an exopolysaccharide-deficient mutant strain. the isolated lpsxcc induced an oxidative burst reaction in cell-suspension cultures of the non-host plant tobacco (nicotiana tabacum l.) sri. the oxidative burst elicited by lpsxcc differed from that induced by yeast elicitor (ye), a cell wall preparation of baker's yeast. the lpsxcc-induced oxidative burst was characteri ...200111469586
polysaccharide synthesis as a carbon dissipation mechanism in metabolically uncoupled xanthomonas campestris cells.the utilization of xanthan metabolism as an excess carbon dissipation path in xanthomonas campestris cells under sub-lethal acid stress was studied. to highlight growth limitation during metabolic uncoupling due to acid toxicity a antibiotic was added. the simultaneous addition of enoxacin and acetic acid showed that the xanthan production per unit of biomass raises with increasing concentrations of enoxacin, which seems to indicate that when the cell is prevented from growing it finds a path to ...200111472799
assessment of the genetic diversity among strains of xanthomonas cynarae by randomly amplified polymorphic dna analysis and development of specific characterized amplified regions for the rapid identification of x. cynarae.the randomly amplified polymorphic dna (rapd) method was used to investigate the genetic diversity in xanthomonas cynarae, which causes bacterial bract spot disease of artichoke. this rapd analysis was also intended to identify molecular markers characteristic of this species, in order to develop pcr-based markers which can be used to detect this pathogenic bacterium in artichoke fields. among the 340 rapd primers tested, 40 were selected on their ability to produce reproducible and reliable fin ...200111472907
brown pigments produced by yarrowia lipolytica result from extracellular accumulation of homogentisic acid.yarrowia lipolytica produces brown extracellular pigments that correlate with tyrosine catabolism. during tyrosine depletion, the yeast accumulated homogentisic acid, p-hydroxyphenylethanol, and p-hydroxyphenylacetic acid in the medium. homogentisic acid accumulated under all aeration conditions tested, but its concentration decreased as aeration decreased. with moderate aeration, equimolar concentrations of alcohol and p-hydroxyphenylacetic acid (1:1) were detected, but with lower aeration the ...200111472920
fate of the biological control agent pseudomonas aureofaciens tx-1 after application to turfgrass.the fate and impact of pseudomonas aureofaciens tx-1 following application as a biocontrol agent for fungi in turfgrass were studied. the organism was applied with a modified irrigation system by using a preparation containing 1 x 10(6) p. aureofaciens tx-1 cfu ml(-1) about 100 times between may and august. we examined the impact of this repeated introduction of p. aureofaciens tx-1 (which is known to produce the antimicrobial compound phenazine-1-carboxylic acid) on the indigenous microbial com ...200111472930
characterization of stress-responsive genes, hrca-grpe-dnak-dnaj, from phytopathogenic xanthomonas campestris.sequencing of a 6.4-kb dna fragment, cloned from the plant pathogenic bacterium xanthomonas campestris pv. campestris 17 revealed five orfs whose deduced amino acid sequences show strong similarities to the bacterial hrca, grpe, dnak, dnaj, and pdxk. the four heat shock genes are organized in the order hrca-grpe-dnak-dnaj, a genome organization found in many gram-positive bacteria, but only in one gram-negative species (xylella fastidiosa). these observations suggest that the hrca-circe system, ...200111479711
expression of 35s::pto globally activates defense-related genes in tomato plants.the tomato (lycopersicon esculentum) resistance gene pto confers resistance to the bacterial pathogen pseudomonas syringae pv tomato carrying the avirulent gene avrpto. overexpressing pto under the control of the cauliflower mosaic virus 35s promoter constitutively activates defense responses in the absence of pathogen infection and nonspecifically enhances disease resistance. to elucidate the mechanisms underlying this resistance, we isolated cdnas corresponding to transcripts that accumulated ...200111500562
involvement of the tonb system in tolerance to solvents and drugs in pseudomonas putida dot-t1e.pseudomonas putida dot-t1e is able to grow with glucose as the carbon source in liquid medium with 1% (vol/vol) toluene or 17 g of (123 mm) p-hydroxybenzoate (4hba) per liter. after random mini-tn5'phoa-km mutagenesis, we isolated the mutant dot-t1e-phoa5, which was more sensitive than the wild type to 4hba (growth was prevented at 6 g/liter) and toluene (the mutant did not withstand sudden toluene shock). susceptibility to toluene and 4hba resulted from the reduced efflux of these compounds fro ...200111514511
quorum-sensing in gram-negative bacteria.it has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions. the languages by which bacteria communicate take the form of chemical signals, excreted from the cells, which can elicit profound physiological changes. many types of signalling molecules, which regulate diverse phenotypes across distant genera, h ...200111524130
xanthomonas campestris pv. campestris secretes the endoglucanases engxca and engxcb: construction of an endoglucanase-deficient mutant for industrial xanthan production.xanthomonas campestris pv. campestris secretes at least two cellulose-degrading endoglucanases. one of these endoglucanases is encoded by the engxca gene of x. c. pv. campestris 8400 that was previously characterized by gough et al. [gene (1990) 89: 53-59]. an additional endoglucanase encoded by the engxcb gene was identified in x. c. pv. campestris 8400 and fc2. the engxcb gene product that was grouped into the endoglucanase family e contains a putative n-terminal signal peptide, suggesting a s ...200111525621
exopolysaccharides of xanthomonas pathovar strains that infect rice and wheat crops.in order to understand the mode of action of the taxonomically related pathogens xanthomonas campestris pv. translucens, xanthomonas oryzae pv. oryzae, and xanthomonas oryzae pv. oryzicola, which attack wheat and rice crops, we examined the compositional differences of their exopolysaccharides (epss). maximum production of polysaccharide in shake cultures of these pathogens was observed between 24 and 72 h. x. campestris pv. translucens, the leaf streak pathogen of wheat, produced a higher amoun ...200111525629
the viable but nonculturable state of ralstonia solanacearum may be involved in long-term survival and plant infection.the role of the dormant-like viable but nonculturable (vbnc) condition in the etiology of bacterial infection was examined using a plant system. the plant-pathogenic bacterium ralstonia solanacearum was first shown to enter into the vbnc state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. to determine if the vbnc condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plant ...200111525979
isolation of an insertion sequence from ralstonia solanacearum race 1 and its potential use for strain characterization and detection.a new insertion sequence (is), is1405, was isolated and characterized from a ralstonia solanacearum race 1 strain by the method of insertional inactivation of the sacb gene. sequence analysis indicated that the is is closely related to the members of is5 family, but the extent of nucleotide sequence identity in 5' and 3' noncoding regions between is1405 and other members of is5 family is only 23 to 31%. nucleotide sequences of these regions were used to design specific oligonucleotide primers fo ...200111525989
direct incorporation of glucosamine and n-acetylglucosamine into exopolymers by gluconacetobacter xylinus (=acetobacter xylinum) atcc 10245: production of chitosan-cellulose and chitin-cellulose exopolymers.gluconacetobacter xylinus (=acetobacter xylinum) atcc 10245 incorporated 2-amino-2-deoxy-d-glucose (glucosamine) and 2-acetamido-2-deoxy-d-glucose (n-acetylglucosamine), but not 3-o-methyl-d-glucose or 2-deoxy-d-glucose into exopolymers. incorporation was confirmed by gas chromatography with and without mass spectrometry, fourier transform infrared, and 1h nuclear magnetic resonance. the average molar percentage of glucosamine and n-acetylglucosamine in the exopolymers was about 18%.200111525993
rapid identification and differentiation of the soft rot erwinias by 16s-23s intergenic transcribed spacer-pcr and restriction fragment length polymorphism analyses.current identification methods for the soft rot erwinias are both imprecise and time-consuming. we have used the 16s-23s rrna intergenic transcribed spacer (its) to aid in their identification. analysis by its-pcr and its-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. the its was amplified from erwinia and other genera using universal pcr primers. after pcr, the banding patterns generated allow ...200111526007
gly gene cloning and expression and purification of glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines 8ra.glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines, inhibits the growth of x. campestris pv. vesicatoria. we have cloned and expressed the genes encoding glycinecin a in escherichia coli. recombinant glycinecin a was purified from cell extracts by ammonium sulfate precipitation followed by chromatography on q-sepharose, mono q (ion exchange), and size exclusion columns. purified glycinecin a is composed of two polypeptides, is active over a wide ph range (6 to 9), and is ...200111526012
the emerging periplasm-localized subclass of aroq chorismate mutases, exemplified by those from salmonella typhimurium and pseudomonas aeruginosa.chorismate mutases of the aroq homology class are widespread in the bacteria and the archaea. many of these exist as domains that are fused with other aromatic-pathway catalytic domains. among the monofunctional aroq proteins, that from erwinia herbicola was previously shown to have a cleavable signal peptide and located in the periplasmic compartment. whether or not this might be unique to e. herbicola was unknown.200111532214
luxarray, a high-density, genomewide transcription analysis of escherichia coli using bioluminescent reporter strains.a sequenced collection of plasmid-borne random fusions of escherichia coli dna to a photorhabdus luminescens luxcdabe reporter was used as a starting point to select a set of 689 nonredundant functional gene fusions. this group, called luxarray 1.0, represented 27% of the predicted transcriptional units in e. coli. high-density printing of the luxarray 1.0 reporter strains to membranes on agar plates was used for simultaneous reporter gene assays of gene expression. the cellular response to nali ...200111544210
sequence, transcriptional analysis and chromosomal location of the xanthomonas campestris pv. campestris uvrb gene.the uvrb gene of xanthomonas campestris pv. campestris, a gram-negative plant pathogenic bacterium inhabiting soil and infected plants, was cloned and sequenced. this gene has the capacity to encode a polypeptide of 673 amino acid residues with a calculated molecular mass of 75.9 kda. its deduced amino acid sequence shows a high degree of similarity and possesses domain conservation to those of bacterial uvrb. the uvrb mutant, isolated by gene replacement, is extremely sensitive to ultraviolet i ...200111545271
salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from trichoderma longibrachiatum.infiltration of cellulase (ec 3.2.1.4) from trichoderma longibrachiatum into melon (cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. an oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (sa) signaling pathways leading to marked induction of peroxidase and chitinase activities. the treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase an ...200111553761
udp-glucose dehydrogenase gene of xanthomonas campestris is required for virulence.xanthomonas campestris pv. campestris (xc) is the casual agent of black rot in crucifers. the xc gene (udgh) coding for udp-glucose dehydrogenase, an enzyme catalyzing the conversion of udp-glucose to udp-glucuronic acid, was previously shown to be required for the biosynthesis of xanthan gum, a substance necessary for the bacterium to cause disease. in this study, the transcription start site of the udgh was determined and the promoter activity monitored by the xyle reporter system indicated th ...200111554764
novel domains of the prokaryotic two-component signal transduction systems.the archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver chey-like domain and a dna-binding domain. sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as pas, gaf, hamp, ggdef, eal, and hd-gyp. all of these domains are w ...200111557134
survival of salmonellae on and in tomato plants from the time of inoculation at flowering and early stages of fruit development through fruit ripening.the fate of salmonellae applied to tomato plants was investigated. five salmonella serotypes were used to inoculate tomato plants before and after fruits set, either by injecting stems with inoculum or brushing flowers with it. ripe tomato fruits were subjected to microbiological analysis. peptone wash water, homogenates of stem scar tissues, and homogenates of fruit pulp were serially diluted and plated on bismuth sulfite agar before and after enrichment. presumptive salmonella colonies were co ...200111571182
molecular cloning of a novel pathogen-inducible cdna encoding a putative acyl-coa synthetase from capsicum annuum l.by means of differential display, a pool of salicylic acid (sa)-induced mrnas were identified and subsequently their cdnas were isolated from a cdna library prepared from sa-induced leaf tissues of hot pepper. one of these cdna clones, designated casig4, was 1900 bp and contained an open reading frame encoding 523 amino acids with a calculated molecular mass of 56.3 kda. the predicted amino acid sequence of casig4 showed high sequence similarity to the amp-binding protein family of both prokaryo ...200111575721
cdna-aflp analysis unravels a genome-wide hrpg-regulon in the plant pathogen xanthomonas campestris pv. vesicatoria.the hrp type iii protein secretion system is essential for pathogenicity of the gram-negative plant pathogen xanthomonas campestris pv. vesicatoria. expression of the hrp gene cluster is controlled by hrpg, a two-component response regulator, and hrpx, an arac-type transcriptional activator. using the cdna-aflp technique, 30 hrpg-induced (hgi) and five hrpg-repressed (hgr) cdna fragments were identified, defining a large hrpg-regulon in x. campestris pv. vesicatoria. expression of most genes in ...200111580833
fastidian gum: the xylella fastidiosa exopolysaccharide possibly involved in bacterial pathogenicity.the gram-negative bacterium xylella fastidiosa was the first plant pathogen to be completely sequenced. this species causes several economically important plant diseases, including citrus variegated chlorosis (cvc). analysis of the genomic sequence of x. fastidiosa revealed a 12 kb dna fragment containing an operon closely related to the gum operon of xanthomonas campestris. the presence of all genes involved in the synthesis of sugar precursors, existence of exopolysaccharide (eps) production r ...200111583843
lipopolysaccharide biosynthesis in xanthomonas campestris pv. campestris: a cluster of 15 genes is involved in the biosynthesis of the lps o-antigen and the lps core.as a result of mutational and dna sequence analysis, a wxc gene cluster involved in the synthesis of the surface lipopolysaccharide (lps) was identified in xanthomonas campestris pv. campestris. this gene cluster comprises 15 genes. it was located on a cloned 35-kb fragment of chromosomal dna, close, but not directly adjacent, to previously characterized genes for lps biosynthesis. the g + c content of all but one of the wxc genes was atypically low for x. campestris pv. campestris, while the g ...200111589581
family of class 1 integrons related to in4 from tn1696.the class 1 integron in28, found in the multidrug resistance transposon tn1403, was found to be located in the res site of the backbone transposon and is flanked by a 5-bp direct duplication, indicating that it reached this position by transposition. in28 has a backbone structure related to that of in4, but has lost internal sequences, including the sul1 gene, due to an is6100-mediated deletion. in28 also lacks the partial copy of is6100 found in in4 and contains different gene cassettes, blap1, ...200111600350
concentrations of copper thought to be toxic to escherichia coli can induce the viable but nonculturable condition.we have determined that concentrations of copper considered to be toxic can induce a fraction of a population of escherichia coli to enter the viable but nonculturable (vbnc) condition. copper-induced vbnc cells could be resuscitated for up to 2 weeks after entering the vbnc state.200111679363
dimethoxyphenol oxidase activity of different microbial blue multicopper proteins.2,6-dimethoxyphenol is a versatile substrate for pyricularia oryzae laccase, ppoa from marinomonas mediterranea, phenoxazinone synthase from streptomyces antibioticus and mammalian ceruloplasmin. in addition, in cellular extracts of microorganisms expressing other blue multicopper proteins with no enzymatic activity previously described, such as escherichia coli (copper resistance cueo), pseudomonas syringae and xanthomonas campestris (copper resistance copa), bacillus subtilis (sporulation prot ...200111682198
comparative evaluation of pectolytic and proteolytic enzyme production by free and immobilized cells of some strains of the phytopathogenic erwinia chrysanthemi.whole cells of the phytopathogenic erwinia chrysanthemi strains were immobilized in k-carrageenan and grown in high-calcium xanthomonas campestris medium containing sodium polypectate as carbon source. all the strains used survived immobilization into k-carrageenan beads. immobilized e. chrysanthemi strains displayed higher pectolytic and proteolytic enzyme activities than free cells in liquid suspension. carrageenan immobilization techniques could provide a system to mimic the conditions of e. ...200111687933
controlled expression in klebsiella pneumoniae and shigella flexneri using a bacteriophage p1-derived c1-regulated promoter system.the utility of promoters regulated by the bacteriophage p1 temperature-sensitive c1 repressor was examined in shigella flexneri and klebsiella pneumoniae. promoters carrying c1 operator sites driving lacz expression had induction/repression ratios of up to 240-fold in s. flexneri and up to 50-fold in k. pneumoniae. the promoters exhibited remarkably low basal expression, demonstrated modulation by temperature, and showed rapid induction. this system will provide a new opportunity for controlled ...200111698385
the lexa protein from deinococcus radiodurans is not involved in reca induction following gamma irradiation.the involvement of lexa in induction of reca was investigated in deinococcus radiodurans. as in the wild-type strain, an increase in reca protein synthesis following gamma irradiation was detected in a lexa disruptant, indicating that lexa is not involved in the induction of reca in d. radiodurans.200111698386
brucella abortus genes identified following constitutive growth and macrophage infection.the chronicity of brucella abortus infection in humans and animals depends on the organism's ability to escape host defenses by gaining entry and surviving inside the macrophage. although no human vaccine exists for brucella, vaccine development in other bacteria has been based on deletions of selective nutritional as well as regulatory systems. our goal is to develop a vaccine for brucella. to further this aim, we have used a green fluorescent protein (gfp) reporter system to identify constitut ...200111705955
induction of a pepper cdna encoding sar8.2 protein during the resistance response to tobacco mosaic virus.a cdna library was constructed with mrna extracted from tmv resistant hot pepper plants 24 and 48 h after inoculation by tmv. the library was screened differentially with radio-labeled cdna synthesized with mrna from the leaves of either tmv-inoculated or mock-inoculated hot pepper plants. casar8.2 clone was one of the clones isolated by this differential screening. the predicted amino acid sequence of casar8.2 has a homology of 52% similarity to that of tobacco sar8.2 genes. southern blot analy ...200111710530
alkyl hydroperoxide reductase is the primary scavenger of endogenous hydrogen peroxide in escherichia coli.hydrogen peroxide is generated during aerobic metabolism and is capable of damaging critical biomolecules. however, mutants of escherichia coli that are devoid of catalase typically exhibit no adverse phenotypes during growth in aerobic media. we discovered that catalase mutants retain the ability to rapidly scavenge h(2)o(2) whether it is formed internally or provided exogenously. analysis of candidate genes revealed that the residual activity is due to alkyl hydroperoxide reductase (ahp). muta ...200111717276
regulation of the synthesis of cyclic glucan in xanthomonas campestris by a diffusible signal molecule.the rpf gene cluster of xanthomonas campestris pv. campestris is involved in the co-ordinate positive regulation of the production of extracellular enzymes and the extracellular polysaccharide xanthan. several of the rpf genes are involved in a regulatory system involving the small diffusible molecule dsf (for diffusible signal factor). synthesis of dsf requires rpff, and a two-component sensory transduction system involving rpfc has been implicated in the perception of the signal and signal tra ...200111734884
dominance relationships of bean pathogens at lake balaton.dominance relationships of different bean pathogens were examined during 1999-2000 in small plot trials at lake balaton in hungary. in 1999 the dominant pathogen species were xanthomonas campestris pv. phaseoli. the main cause of the stock decay was due to the infection of fusarium spp. bean plants were infected also by alternaria, colletotrichum, macrophomina and sclerotinia, species part from viruses. among of thirty-eight examined bean cultivars and genotypes the variety "díszbab" and the gen ...200112425043
chromosome landing at the tomato bs4 locus.the tomato (lycopersicon esculentum) bs4 gene confers resistance to strains of xanthomonas campestris pathovar vesicatoria that express the avirulence protein avrbs4. as part of a map-based cloning strategy for the isolation of bs4, we converted bs4-linked amplified fragment length polymorphism (aflp) and restriction fragment length polymorphism (rflp) markers into locus-specific sequence-tagged-site (sts) markers. the use of these markers for the analysis of 1972 meiotic events allowed high-res ...200111810236
a pathogen-induced chitin-binding protein gene from pepper: its isolation and differential expression in pepper tissues treated with pathogens, ethephon, methyl jasmonate or wounding.a chitin-binding protein (cbp) cdna (cacbp1) was isolated from a cdna library of pepper (capsicum annuum l.) leaves infected with xanthomonas campestris pv. vesicatoria. the deduced amino acid sequence of the cacbp1 gene which has chitin-binding domain and hinge region shares a high level of identity with cbp sequences from tomato, potato and tobacco. the cacbp1 gene was organ-specifically regulated in pepper plants, and differentially induced during the compatible and incompatible interactions ...200111773524
detection of bacterial virulence genes by subtractive hybridization: identification of capsular polysaccharide of burkholderia pseudomallei as a major virulence determinant.burkholderia pseudomallei, the etiologic agent of melioidosis, is responsible for a broad spectrum of illnesses in humans and animals particularly in southeast asia and northern australia, where it is endemic. burkholderia thailandensis is a nonpathogenic environmental organism closely related to b. pseudomallei. subtractive hybridization was carried out between these two species to identify genes encoding virulence determinants in b. pseudomallei. screening of the subtraction library revealed a ...200111119486
the chvh locus of agrobacterium encodes a homologue of an elongation factor involved in protein synthesis.the virulence of agrobacterium tumefaciens depends on both chromosome- and ti plasmid-encoded gene products. in this study, we characterize a chromosomal locus, chvh, previously identified by tnphoa mutagenesis and shown to be required for tumor formation. through dna sequencing and comparison of the sequence with identified sequences in the database, we show that this locus encodes a protein similar in sequence to elongation factor p, a protein thought to be involved in peptide bond synthesis i ...200111114898
relationship between glycolysis and exopolysaccharide biosynthesis in lactococcus lactis.the relationships between glucose metabolism and exopolysaccharide (eps) production in a lactococcus lactis strain containing the eps gene cluster (eps(+)) and in nonproducer strain mg5267 (eps(-)) were characterized. the concentrations of relevant phosphorylated intermediates in eps and cell wall biosynthetic pathways or glycolysis were determined by (31)p nuclear magnetic resonance. the concentrations of two eps precursors, udp-glucose and udp-galactose, were significantly lower in the eps(+) ...200111133425
direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia.enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ...200111133432
pigment and virulence deficiencies associated with mutations in the aroe gene of xanthomonas oryzae pv. oryzae.xanthomonadins are yellow, membrane-bound pigments produced by members of the genus xanthomonas. we identified an ethyl methanesulfonate-induced xanthomonas oryzae pv. oryzae mutant (bxo65) that is deficient for xanthomonadin production and virulence on rice, as well as auxotrophic for aromatic amino acids (pig(-) vir(-) aro(-)). reversion analysis indicated that these multiple phenotypes are due to a single mutation. a genomic library of the wild-type strain was used to isolate a 7.0-kb clone t ...200111133452
pantoea agglomerans strain eh318 produces two antibiotics that inhibit erwinia amylovora in vitro.pantoea agglomerans (synonym: erwinia herbicola) strain eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with erwinia amylovora, the causal agent of fire blight. this zone is caused by two antibiotics, named pantocin a and b. using a genomic library of eh318, two cosmids, pcpp702 and pcpp704, were identified that conferred on escherichia coli the ability to inhibit growth of e. amylovora. the two cosmids conferred different antibiotic activities on e. col ...200111133457
involvement of the xpsn protein in formation of the xpsl-xpsm complex in xanthomonas campestris pv. campestris type ii secretion apparatus.the xps gene cluster is required for the second step of type ii protein secretion in xanthomonas campestris pv. campestris. deletion of the entire gene cluster caused accumulation of secreted proteins in the periplasm. by analyzing protein abundance in the chromosomal mutant strains, we observed mutual dependence for normal steady-state levels between the xpsl and the xpsm proteins. the xpsl protein was undetectable in total lysate prepared from the xpsm mutant strain, and vice versa. introducti ...200111133946
genetic and physiological characterization of ohr, encoding a protein involved in organic hydroperoxide resistance in pseudomonas aeruginosa.the ohr (organic hydroperoxide resistance) gene product of pseudomonas aeruginosa was essential for optimal resistance to organic hydroperoxides (ohps) but not to hydrogen peroxide or paraquat. a deltaohr mutant was hypersusceptible to ohps in disk inhibition assays and showed enhanced killing by ohps in liquid culture. the ohr gene product was demonstrated to contribute to the decomposition of ohps. transcription of ohr was induced up to 15-fold upon exposure to ohps, and this induction was ind ...200111133975
comparison of antifungal activities and 16s ribosomal dna sequences of clinical and environmental isolates of stenotrophomonas maltophilia.in recent years, the gram-negative bacterium stenotrophomonas maltophilia has become increasingly important in biotechnology and as a nosocomial pathogen, giving rise to a need for new information about its taxonomy and epidemiology. to determine intraspecies diversity and whether strains can be distinguished based on the sources of their isolation, 50 s. maltophilia isolates from clinical and environmental sources, including strains of biotechnological interest, were investigated. the isolates ...200111136762
ion channel-forming alamethicin is a potent elicitor of volatile biosynthesis and tendril coiling. cross talk between jasmonate and salicylate signaling in lima bean.alamethicin (ala), a voltage-gated, ion channel-forming peptide mixture from trichoderma viride, is a potent elicitor of the biosynthesis of volatile compounds in lima bean (phaseolus lunatus). unlike elicitation with jasmonic acid or herbivore damage, the blend of substances emitted comprises only the two homoterpenes, 4,11-dimethylnona-1,3,7-triene and 4,8,12-trimethyltrideca-1,3,7,11-tetraene, and methyl salicylate. inhibition of octadecanoid signaling by aristolochic acid and phenidone as we ...200111154344
analysis of the type iv fimbrial-subunit gene fima of xanthomonas hyacinthi: application in pcr-mediated detection of yellow disease in hyacinths.a sensitive and specific detection method was developed for xanthomonas hyacinthi; this method was based on amplification of a subsequence of the type iv fimbrial-subunit gene fima from strain s148. the fima gene was amplified by pcr with degenerate dna primers designed by using the n-terminal and c-terminal amino acid sequences of trypsin fragments of fima. the nucleotide sequence of fima was determined and compared with the nucleotide sequences coding for the fimbrial subunits in other type iv ...200111157222
polysaccharide lyase: molecular cloning, sequencing, and overexpression of the xanthan lyase gene of bacillus sp. strain gl1.when grown on xanthan as a carbon source, the bacterium bacillus sp. strain gl1 produces extracellular xanthan lyase (75 kda), catalyzing the first step of xanthan depolymerization (h. nankai, w. hashimoto, h. miki, s. kawai, and k. murata, appl. environ. microbiol. 65:2520-2526, 1999). a gene for the lyase was cloned, and its nucleotide sequence was determined. the gene contained an open reading frame consisting of 2,793 bp coding for a polypeptide with a molecular weight of 99,308. the polypep ...200111157235
initiation of biofilm formation by pseudomonas aeruginosa 57rp correlates with emergence of hyperpiliated and highly adherent phenotypic variants deficient in swimming, swarming, and twitching motilities.pseudomonas aeruginosa is a ubiquitous environmental bacterium capable of forming biofilms on surfaces as a survival strategy. it exhibits a large variety of competition/virulence factors, such as three types of motilities: flagellum-mediated swimming, flagellum-mediated swarming, and type iv pilus-mediated twitching. a strategy frequently used by bacteria to survive changing environmental conditions is to create a phenotypically heterogeneous population by a mechanism called phase variation. in ...200111157931
identification and characterization of gsp65, an organic hydroperoxide resistance (ohr) gene encoding a general stress protein in enterococcus faecalis.the enterococcus faecalis general stress protein gsp65 has been purified from two-dimensional gel electrophoresis. determination of its n-terminal sequence and characterization of the corresponding gene revealed that the gsp65 product is a 133-amino-acid protein sharing homologies with organic hydroperoxide resistance (ohr) proteins. transcriptional analysis of gsp65 gave evidence for a monocistronic mrna initiated 52 nucleotides upstream of the atg start codon and for an induction in response t ...200111157966
catalase has a novel protective role against electrophile killing of xanthomonas.the ability of xanthomonas: campestris pv. phaseoli to protect itself against lethal concentrations of man-made (n:-ethylmaleimide, nem) and endogenously produced (methylglyoxal, mg) electrophiles was investigated. pretreatment of x. c. pv. phaseoli with a low concentration of nem induced protection against lethal concentrations of nem and mg. mg pretreatment weakly induced protection against nem but not against mg itself. nem-induced protection against electrophile killing required new protein ...200111158366
the insect endosymbiont sodalis glossinidius utilizes a type iii secretion system for cell invasion.sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, glossina spp. in this study, we have used tn5 mutagenesis and a negative selection procedure to derive a s. glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse. this mutant strain harbors tn5 integrated into a chromosomal gene sharing high sequence identity with a type iii secretion system invasion ...200111172045
improvement in bioreactor productivities using free radicals: hocl-induced overproduction of xanthan gum from xanthomonas campestris and its mechanism.free-radical induction has been employed as a novel strategy to improve bioreactor productivity and, more specifically, the quality and productivity of xanthan gum from xanthomonas campestris cultures. a 210% increase in xanthan yield and a 20% increase in viscosity (quality) resulted from hocl (oxidant) treatment. the acetate mass fraction in xanthan gum decreased by 42% and its pyruvate mass fraction increased by 63% as a result of hocl treatment. the growth rate was almost unaffected by hocl ...200111084595
the tasty locus on chromosome 1 of arabidopsis affects feeding of the insect herbivore trichoplusia ni.the generalist insect herbivore trichoplusia ni (cabbage looper) readily consumes arabidopsis and can complete its entire life cycle on this plant. natural isolates (ecotypes) of arabidopsis are not equally susceptible to t. ni feeding. while some are hardly touched by t. ni, others are eaten completely to the ground. comparison of two commonly studied arabidopsis ecotypes in choice experiments showed that columbia is considerably more resistant than landsberg erecta. in no-choice experiments, w ...200111402216
oligoguluronates elicit an oxidative burst in the brown algal kelp laminaria digitata.oligomeric degradation products of alginate elicited a respiratory and oxidative burst in the sporophytes of the kelp laminaria digitata. the generation of activated oxygen species (aos), o(2)(-), and h(2)o(2) was detected at the single cell level, using nitroblue tetrazolium precipitation and a redox-sensitive fluorescent probe, respectively. the oxidative burst involved diphenyleneiodonium-sensitive aos-generating machinery and its amplitude depended on the type of tissue. after a first elicit ...200111154336
agricultural microbes genome 2: first glimpses into the genomes of plant-associated microbes. 200111251088
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 ...200010922039
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 ...200011080278
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 ...200010809670
a telomeric avirulence gene determines efficacy for the rice blast resistance gene pi-ta.genetic mapping showed that the rice blast avirulence gene avr-pita is tightly linked to a telomere on chromosome 3 in the plant pathogenic fungus magnaporthe grisea. avr-pita corresponds in gene-for-gene fashion to the disease resistance (r) gene pi-ta. analysis of spontaneous avr-pita(-) mutants indicated that the gene is located in a telomeric 6.5-kb bglii restriction fragment. cloning and dna sequencing led to the identification of a candidate gene with features typical of metalloproteases. ...200011090206
molecular evolution of virulence in natural field strains of xanthomonas campestris pv. vesicatoria.the avrbs2 avirulence gene of the bacterial plant pathogen xanthomonas campestris pv. vesicatoria triggers disease resistance in pepper plants containing the bs2 resistance gene and contributes to bacterial virulence on susceptible host plants. we studied the effects of the pepper bs2 gene on the evolution of avrbs2 by characterizing the molecular basis for virulence of 20 x. campestris pv. vesicatoria field strains that were isolated from disease spots on previously resistant bs2 pepper plants. ...200011092868
characterization of a major cluster of nif, fix, and associated genes in a sugarcane endophyte, acetobacter diazotrophicus.a major 30.5-kb cluster of nif and associated genes of acetobacter diazotrophicus (syn. gluconacetobacter diazotrophicus), a nitrogen-fixing endophyte of sugarcane, was sequenced and analyzed. this cluster represents the largest assembly of contiguous nif-fix and associated genes so far characterized in any diazotrophic bacterial species. northern blots and promoter sequence analysis indicated that the genes are organized into eight transcriptional units. the overall arrangement of genes is most ...200011092875
biological role of xanthomonadin pigments in xanthomonas campestris pv. campestris.previous studies have indicated that the yellow pigments (xanthomonadins) produced by phytopathogenic xanthomonas bacteria are unimportant during pathogenesis but may be important for protection against photobiological damage. we used a xanthomonas campestris pv. campestris parent strain, single-site transposon insertion mutant strains, and chromosomally restored mutant strains to define the biological role of xanthomonadins. although xanthomonadin mutant strains were comparable to the parent st ...200011097878
bacterial biodegradation of extractives and patterns of bordered pit membrane attack in pine wood.wood extractives, commonly referred to as pitch, cause major problems in the manufacturing of pulp and paper. treatment of nonsterile southern yellow pine chips for 14 days with pseudomonas fluorescens, pseudomonas sp., xanthomonas campestris, and serratia marcescens reduced wood extractives by as much as 40%. control treatments receiving only water lost 11% of extractives due to the growth of naturally occurring microorganisms. control treatments were visually discolored after the 14-day incuba ...200011097890
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