| genetic relationships among strains of xylella fastidiosa from rapd-pcr data. | genetic relationships among 11 xylella fastidiosa strains isolated from mulberry, almond, ragweed, grape, plum, elm, and citrus were determined by random amplified polymorphic dna (rapd). twenty-two 10-base primers amplified a total of 77 discrete polymorphic bands. phenetic analysis based on a similarity matrix corresponded well with previous reports on x. fastidiosa rflp-based similarity relationships, indicating that rapd-pcr amplification products can be used as a reliable indicator of genet ... | 1995 | 7606188 |
| randomly amplified polymorphic dna analysis of xylella fastidiosa pierce's disease and oak leaf scorch pathotypes. | randomly amplified polymorphic dna analysis was conducted with 14 primers to 17 strains of xylella fastidiosa. there was a high degree of similarity among the seven pierce's disease (pd) strains (sxy > 0.93) and the seven oak leaf scorch (ols) strains (sxy > 0.96). however, the two groups were different, with a similarity index of 0.67, confirming the presence of a pd dna cluster and suggesting the presence of a new ols cluster. the control plum leaf scald strains (two strains) together with the ... | 1995 | 7646005 |
| specific pcr detection and identification of xylella fastidiosa strains causing citrus variegated chlorosis. | by cloning and sequencing specific randomly amplified polymorphic dna (rapd) products, we have developed pairs of pcr primers that can be used to detect xylella fastidiosa in general, and x. fastidiosa that cause citrus variegated chlorosis (cvc) specifically. we also identified a cvc-specific region of the x. fastidiosa genome that contains a 28-nucleotide insertion, and single base changes that distinguish cvc and grape x. fastidiosa strains. when using rapd products to develop specific pcr pr ... | 1995 | 8528010 |
| detection of xylella fastidiosa in potential insect vectors by immunomagnetic separation and nested polymerase chain reaction. | a sensitive and specific assay for detecting xylella fastidiosa in potential insect vectors was developed. this assay involves immunomagnetic separation of the bacteria from the insect, followed by a two-step, nested polymerase chain reaction (pcr) amplification using previously developed oligonucleotide primers specific to x. fastidiosa. a total of 347 leafhoppers representing 16 species were captured and sampled from american elm (ulmus americana l.) trees growing in a nursery where bacterial ... | 1997 | 9281861 |
| sequence analysis of a 1296-nucleotide plasmid from xylella fastidiosa. | a cryptic plasmid from xylella fastidiosa strain atcc 35868 was cloned, sequenced, and the sequence entered into genbank (u71220). the plasmid is 1296 nucleotides in length with 55% gc content and three open reading frames. a plasmid with sequence homology was found in only one other strain of x. fastidiosa, atcc 35878. searches of the genbank reveal nucleotide sequence homology with plasmid pnkh43 from stenotrophomonas maltophilia, and amino acid sequence homology with phage pf3 from pseudomona ... | 1997 | 9351204 |
| a small-scale procedure for extracting nucleic acids from woody plants infected with various phytopathogens for pcr assay. | the complexity of most nucleic acid extraction procedures limits the number of samples that can be easily processed for analysis by polymerase chain reaction (pcr). a simple, small-scale procedure was developed which can be carried out entirely in 1.5-ml microfuge tubes whereby the container and contents are frozen with liquid nitrogen, tissue is pulverized, and targeted nucleic acids are extracted. dna of bacterial and phytoplasmal plant pathogens was extracted in hot ctab buffer followed by ch ... | 1998 | 9628220 |
| specific detection of xylella fastidiosa pierce's disease strains. | pierce's disease (pd, xylella fastidiosa) of grapevine is the primary pathogen limiting vinifera grape production in florida and other regions of the southeastern united states. quick and accurate detection of pd strains is essential for pd studies and control. a unique random amplified polymorphic dna (pd1-1-2) was isolated from a pd strain from florida. fragment pd1-1-2 was cloned, sequenced, and found to be 1005 bp in length. pcr primers were designed to utilize these sequence data for pd str ... | 1999 | 10398832 |
| a triply cloned strain of xylella fastidiosa multiplies and induces symptoms of citrus variegated chlorosis in sweet orange | xylella fastidiosa isolate 8.1.b obtained from a sweet orange tree affected by citrus variegated chlorosis in the state of sao paulo, brazil, and shown in 1993 to be the causal agent of the disease, was cloned by repeated culture in liquid and on solid pw medium, yielding triply cloned strain 9a5c. the eighth and the 16th passages of strain 9a5c were mechanically inoculated into sweet orange plants. presence of x. fastidiosa in sweet orange leaves of shoots having grown after inoculation (first- ... | 1999 | 10398837 |
| a simplified subtractive hybridization protocol used to isolate dna sequences specific to xylella fastidiosa. | a simplified protocol of subtractive hybridization based on the technique of l. m. kunkel, a. p. monaco, w. middlesworth, h. d. ochs & s. a. latt (1985, proc natl acad sci usa, 82, 4778-4782) was used to obtain dna sequences specific to xylella fastidiosa isolated from diseased citrus plants. as a driver, dna extracted from bacteria showing different degrees of relatedness was used: xy. fastidiosa 788 isolated from another host (plum), xanthomonas campestris pv. campestris and burkholderia gladi ... | 1999 | 10463163 |
| use of 16s rdna sequences as signature characters to identify xylella fastidiosa. | the nucleotide sequences of 16s rdnas (coding for the small subunit ribosomal rnas) were used to identify xylella fastidiosa, a nutritionally fastidious plant pathogenic bacterium. the near-complete 16s rdnas from nine strains of xyl. fastidiosa, including seven pathotypes and one strain of xanthomonas campestris pv. campestris, were amplified through pcr with two conserved primers (forward primer 5'-aga gtt tga tcc tgg ctc ag-3' and reverse primer 5'-aag gag gtg atc cag cc-3') and sequenced. th ... | 2000 | 10568800 |
| strains of xylella fastidiosa rapidly distinguished by arbitrarily primed-pcr. | genomic dnas isolated from strains of xylella fastidiosa that caused citrus variegated chlorosis, coffee leaf scorch, pierce's disease of grapevine, and plum leaf scorch were analyzed by arbitrarily primed polymerase chain reaction. purified dna was amplified under nonstringent conditions with single primers 21 nucleotides (nt) long. thirty-nine amplification products were observed that were useful to distinguish among the strains and to derive a similarity matrix and construct a phenogram showi ... | 2000 | 10688699 |
| nutritional requirements of xylella fastidiosa, which causes pierce's disease in grapes. | a defined medium (xf-26) containing 3 inorganic salts, 2 tricarboxylic acids, 17 amino acids, potato starch, phenol red, and agar was used as the starting point for the study. deletions of one or more ingredients were performed to prepare various media. a medium was considered able to support growth of xylella fastidiosa strains responsible for pierce's disease in grapes, only after 10 serial passages had been completed. of 3 inorganic salts, k2hpo4 and mgso4 x 7h2o were essential, and (nh4)2hpo ... | 2000 | 10749543 |
| the genome sequence of the plant pathogen xylella fastidiosa. the xylella fastidiosa consortium of the organization for nucleotide sequencing and analysis. | xylella fastidiosa is a fastidious, xylem-limited bacterium that causes a range of economically important plant diseases. here we report the complete genome sequence of x. fastidiosa clone 9a5c, which causes citrus variegated chlorosis--a serious disease of orange trees. the genome comprises a 52.7% gc-rich 2,679,305-base-pair (bp) circular chromosome and two plasmids of 51,158 bp and 1,285 bp. we can assign putative functions to 47% of the 2,904 predicted coding regions. efficient metabolic fun ... | 2000 | 10910347 |
| mapping analysis of the xylella fastidiosa genome. | a cosmid library was made of the 2.7 mb genome of the gram-negative plant pathogenic bacterium xylella fastidiosa and analysed by hybridisation mapping. clones taken from the library as well as genomic restriction fragments of rarely cutting enzymes were used as probes. the latter served as a backbone for ordering the initial map contigs and thus facilitated gap closure. also, the co-linearity of the cosmid map, and thus the eventual sequence, could be confirmed by this process. a subset of the ... | 2000 | 10931925 |
| application of bootstrap techniques to physical mapping. | ordering genetic markers or clones from a genomic library into a physical map is a central problem in genetics. in the presence of errors, there is no efficient algorithm known that solves this problem. based on a standard heuristic algorithm for it, we present a method to construct a confidence neighborhood for a computed solution. we compute a confidence value for putative local solutions derived from bootstrap replicates of the original solution. in the reliable parts, the confidence neighbor ... | 2000 | 11031106 |
| a genomic approach to the understanding of xylella fastidiosa pathogenicity. | xylella fastidiosa is a fastidious, xylem-limited bacterium that causes several economically important plant diseases, including citrus variegated chlorosis (cvc). x. fastidiosa is the first plant pathogen to have its genome completely sequenced. in addition, it is probably the least previously studied of any organism for which the complete genome sequence is available. several pathogenicity-related genes have been identified in the x. fastidiosa genome by similarity with other bacterial genes i ... | 2000 | 11050442 |
| porphyromonas gingivalis dpp-7 represents a novel type of dipeptidylpeptidase. | a novel dipeptidylpeptidase (dpp-7) was purified from the membrane fraction of porphyromonas gingivalis. this enzyme, with an apparent molecular mass of 76 kda, has the specificity for both aliphatic and aromatic residues in the p1 position. although it belongs to the serine class of peptidases, it does not resemble other known dipeptidylpeptidases. interestingly, the amino acid sequence around the putative active site serine residue shows significant similarity to the c-terminal region of the s ... | 2001 | 11096098 |
| 16s rdna sequence analysis of xylella fastidiosa strains. | the 16s rdna encoding the small subunit ribosomal rna were amplified by pcr, cloned, and sequenced from 16 strains of xylella fastidiosa originating from nine different hosts. in pair-wise comparisons, x. fastidiosa strains showed a maximum variation of 1.0% or 14 nucleotide positions. when all 16 sequences were considered as a set, 54 variable positions were found. analysis of the sequence data indicated that the x. fastdiosa strains formed three rdna groups. group one includes pierce's disease ... | 2000 | 11108013 |
| contig selection in physical mapping. | in physical mapping, one orders a set of genetic landmarks or a library of cloned fragments of dna according to their position in the genome. our approach to physical mapping divides the problem into smaller and easier subproblems by partitioning the probe set into independent parts (probe contigs). for this purpose we introduce a new distance function between probes, the averaged rank distance (ard) derived from bootstrap resampling of the raw data. the ard measures the pairwise distances of pr ... | 2000 | 11108470 |
| xylella genomics and bacterial pathogenicity to plants. | xylella fastidiosa, a pathogen of citrus, is the first plant pathogenic bacterium for which the complete genome sequence has been published. inspection of the sequence reveals high relatedness to many genes of other pathogens, notably xanthomonas campestris. based on this, we suggest that xylella possesses certain easily testable properties that contribute to pathogenicity. we also present some general considerations for deriving information on pathogenicity from bacterial genomics. | 2000 | 11119303 |
| featured organism: pathogen special: vibrio cholerae, pseudomonas aeruginosa and xylella fastidiosa. | one could almost say that it is the latest fashion to sequence a bacterial genome. however, this would belittle the efforts of those working on these important organisms, whose data will greatly help those working on the prevention of disease in the fields of medicine and agriculture. in this feature we present a guided tour of the latest additions to the 'sequenced microbes' club. vibrio cholerae is the causative agent of cholera, which is still a threat in countries with poor sanitation and un ... | 2000 | 11119308 |
| evidence for conserved trna genes in the 16s-23s rdna spacer sequence and two rrn operons of xylella fastidiosa. | the 16s-23s rdna spacer of the type strain (atcc 35879) of xylella fastidiosa was amplified by pcr, cloned, and sequenced. the spacer sequence (455 bp) contains two trna (trna(ala) and trna(ile)) genes. identical trna genes were also found in the 16s-23s spacer sequences of all the 51 strains of x. fastidiosa retrieved from the genbank database. at this particular locus, the gene order of trna(ala)-trna(ile) is conserved among all the studied strains of xylella and xanthomonas, and different fro ... | 2000 | 11142410 |
| genetic diversity of pierce's disease strains and other pathotypes of xylella fastidiosa. | strains of xylella fastidiosa isolated from grape, almond, maple, and oleander were characterized by enterobacterial repetitive intergenic consensus sequence-, repetitive extragenic palindromic element (rep)-, and random amplified polymorphic dna (rapd)-pcr; contour-clamped homogeneous electric field (chef) gel electrophoresis; plasmid content; and sequencing of the 16s-23s rrna spacer region. combining methods gave greater resolution of strain groupings than any single method. strains isolated ... | 2001 | 11157260 |
| from rags to riches: insights from the first genomic sequence of a plant pathogenic bacterium. | the recently published genomic sequence of xylella fastidiosa is the first for a free-living plant pathogen and provides clues to mechanisms of pathogenesis and survival in insect vectors. the sequence data should lead to improved control of this pathogen. | 2000 | 11178244 |
| 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 ... | 2001 | 11319110 |
| phylogenetic relationships of xylella fastidiosa strains from different hosts, based on 16s rdna and 16s-23s intergenic spacer sequences. | the phylogenetic relationships of xylella fastidiosa strains isolated from different hosts, including citrus trees, coffee, grapevine, plum and pear, were inferred by sequence analysis of the 16s rdna and 16s-23s intergenic spacer region. a high level of similarity (97.1-100%) was found in the 16s rdna of the xylella fastidiosa strains. the 16s-23s region showed a higher level of variation, with similarity values ranging from 79.8 to 100%. two trnas (trna(ala) and trna(ile)) were encountered wit ... | 2001 | 11321075 |
| schineria larvae gen. nov., sp. nov., isolated from the 1st and 2nd larval stages of wohlfahrtia magnifica (diptera: sarcophagidae). | four bacterial strains were isolated from the fly larvae of an obligate parasitic fly, wohlfahrtia magnifica (diptera: sarcophagidae). these isolates were characterized by a polyphasic approach and represent a new lineage of gamma-proteobacteria as their closest relative is xylella fastidiosa (87.1% 16s rdna similarity). the four strains are identical at the 16s rdna level, the level of similarity between them, based on dna-dna hybridization, is high (97.8-102.5%) and they are similar in their p ... | 2001 | 11321085 |
| directed gap closure in large-scale sequencing projects. | a problem in many sequencing projects is the final closure of gaps left in the clone libraries, which serve as templates for sequencing, because of uncloned or unclonable genomic areas. by use of the xylella fastidiosa genome as a test system, we present here an approach to generate, in a directed manner, sequence information from those gaps. we suggest using the complete clone library as a competitor against the genomic dna of interest in a subtractive hybridization procedure similar to represe ... | 2001 | 11337483 |
| transposon mutagenesis of xylella fastidiosa by electroporation of tn5 synaptic complexes. | pierce's disease, a lethal disease of grapevine, is caused by xylella fastidiosa, a gram-negative, xylem-limited bacterium that is transmitted from plant to plant by xylem-feeding insects. strains of x. fastidiosa also have been associated with diseases that cause tremendous losses in many other economically important plants, including citrus. although the complete genome sequence of x. fastidiosa has recently been determined, the inability to transform or produce transposon mutants of x. fastid ... | 2001 | 11386365 |
| assessment of the genetic diversity of xylella fastidiosa isolated from citrus in brazil by pcr-rflp of the 16s rdna and 16s-23s intergenic spacer and rep-pcr fingerprinting. | the genetic diversity among twenty three strains of xylella fastidiosa, isolated from sweet orange citrus, was assessed by rflp analysis of the 16s rdna and 16s-23s intergenic spacer and by rep-pcr fingerprinting together with strains isolated from coffee, grapevine, plum and pear. the pcr products obtained by amplification of the 16s rdna and 16s-23s spacer region were digested with restriction enzymes and a low level of polymorphism was detected. in rep-pcr fingerprinting, a relationship betwe ... | 2001 | 11392484 |
| construction of a shuttle vector and transformation of xylella fastidiosa with plasmid dna. | we have isolated, cloned, and sequenced a 5823-bp cryptic plasmid from a strain of xylella fastidiosa. this plasmid encodes five open reading frames (orf) greater than 400 nucleotides each. orf 2 encodes a protein with 37% amino acid identity to the replication initiator protein of plasmid pecb2 from pseudomonas alcaligenes. this repa protein from x. fastidiosa contains both a leucine zipper and helix turn helix motif characteristic of proteins involved in dna replication. the sequence 5' of orf ... | 2001 | 11400063 |
| genetic organization of plasmid pxf51 from the plant pathogen xylella fastidiosa. | the sequence of plasmid pxf51 from the plant pathogen xylella fastidiosa, the causal agent of citrus variegated chlorosis, has been analyzed. this plasmid codes for 65 open reading frames (orfs), organized into four main regions, containing genes related to replication, mobilization, and conjugative transfer. twenty-five orfs have no counterparts in the public sequence databases, and 7 are similar to conserved hypothetical proteins from other bacteria. a pxf51 incompatibility group has not been ... | 2001 | 11407914 |
| 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, ... | 2001 | 11479711 |
| differentiation of strains of xylella fastidiosa by a variable number of tandem repeat analysis. | short sequence repeats (ssrs) with a potential variable number of tandem repeat (vntr) loci were identified in the genome of the citrus pathogen xylella fastidiosa and used for typing studies. although mono- and dinucleotide repeats were absent, we found several intermediate-length 7-, 8-, and 9-nucleotide repeats, which we examined for allelic polymorphisms using pcr. five genuine vntr loci were highly polymorphic within a set of 27 x. fastidiosa strains from different hosts. the highest averag ... | 2001 | 11526010 |
| rapd profile and antibiotic susceptibility of xylella fastidiosa, causal agent of citrus variegated chlorosis. | the aim of this study was to evaluate the diversity of xylella fastidiosa isolated from citrus trees affected by citrus variegated chlorosis (cvc). | 2001 | 11559405 |
| 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 ... | 2001 | 11583843 |
| effect of selected insecticides on homalodisca coagulata (homoptera: cicadellidae) and transmission of oleander leaf scorch in a greenhouse study. | homalodisca coagulata (say) is a recent introduction to california. it is known to spread a strain of the bacterium xylella fastidiosa wells, raju, hung, weisberg, mandelco-paul & brenner that induces oleander leaf scorch disease in oleander, nerium oleander l. oleander leaf scorch is lethal to oleander and threatens to decimate one of the most important landscape shrubs in california. towards developing a management strategy for h. coagulata-spread oleander leaf scorch, we documented the affect ... | 2001 | 11681662 |
| citrus blight and other diseases of recalcitrant etiology. | several economically important diseases of unknown or recently determined cause are reviewed. citrus blight (cb), first described over 100 years ago, was shown in 1984 to be transmitted by root-graft inoculations; the cause remains unknown and is controversial. based on graft transmission, it is considered to be an infectious agent by some; others suggest that the cause of cb is abiotic. citrus variegated chlorosis, although probably long present in argentina, where it was considered to be a var ... | 2000 | 11701841 |
| seasonal flight activity of two homalodisca species (homoptera: cicadellidae) that spread xylella fastidiosa in southern california. | homalodisca coagulata (say) and homalodisca lacerta (fowler) are vectors of a new bacterial disease of oleander in california known as oleander leaf scorch, induced by the bacterium xylella fastidiosa. h. coagulata also has been implicated in the spread of the strain of x. fastidiosa that induces pierce's disease of grapevines in california. we monitored the flight activity of h. coagulata and h. lacerta in oleander and citrus by using yellow sticky cards at three southern california locations w ... | 2001 | 11777056 |
| the genetic organization and evolution of the broad host range mercury resistance plasmid psb102 isolated from a microbial population residing in the rhizosphere of alfalfa. | employing the biparental exogenous plasmid isolation method, conjugative plasmids conferring mercury resistance were isolated from the microbial community of the rhizosphere of field grown alfalfa plants. five different plasmids were identified, designated psb101-psb105. one of the plasmids, psb102, displayed broad host range (bhr) properties for plasmid replication and transfer unrelated to the known incompatibility (inc) groups of bhr plasmids incp-1, incw, incn and inca/c. nucleotide sequence ... | 2001 | 11812851 |
| topoisomerase ii and iv quinolone resistance-determining regions in stenotrophomonas maltophilia clinical isolates with different levels of quinolone susceptibility. | the quinolone resistance-determining regions (qrdrs) of topoisomerase ii and iv genes from stenotrophomonas maltophilia atcc 13637 were sequenced and compared with the corresponding regions of 32 unrelated s. maltophilia clinical strains for which ciprofloxacin mics ranged from 0.1 to 64 microg/ml. gyra (leu-55 to gln-155, escherichia coli numbering), gyrb (met-391 to phe-513), parc (ile-34 to arg-124), and pare (leu-396 to leu-567) fragments from strain atcc 13637 showed high degrees of identit ... | 2002 | 11850246 |
| transposon tn1721 distribution among strains of xylella fastidiosa. | transposons are mobile genetic elements found within the genomes of various organisms including bacteria, fungi, plants and animals. fragments of the transposon tn1721 were found included in the genome of xylella fastidiosa strain 9a5c. regions from such fragments were pcr-amplified using specially designed primers (tnp(1) and tnp(2)). in order to detect insertions of the tn1721 element, both primers were used and one of them included a region of the transposon (tnp(1)) and the other one had the ... | 2002 | 11959431 |
| sample sequencing of a selected region of the genome of erwinia carotovora subsp. atroseptica reveals candidate phytopathogenicity genes and allows comparison with escherichia coli. | genome sequencing is making a profound impact on microbiology. currently, however, only one plant pathogen genome sequence is publicly available and no genome-sequencing project has been initiated for any species of the genus erwinia, which includes several important plant pathogens. this paper describes a targeted sample sequencing approach to study the genome of erwinia carotovora subsp. atroseptica (eca), a major soft-rot pathogen of potato. a large insert dna (approx. 115 kb) library of eca ... | 2002 | 11988510 |
| site-directed gene disruption in xylella fastidiosa. | as a first approach to generate mutations by dna insertion, we have developed a shuttle vector, called psp3, which replicates both in escherichia coli and in xylella. vector psp3 was constructed by ligating to the e. coli plasmid pbluescript, a kanamycin resistance gene under the control of the xylella 16s rrna promoter and the indigenous xylella plasmid pxf1.3. transformation experiments have shown that psp3 replicates stably in xylella. when a dna fragment encompassing part of the xylella xpsd ... | 2002 | 12023085 |
| oric region and replication termination site, dif, of the xanthomonas campestris pv. campestris 17 chromosome. | a 13-kb dna fragment containing oric and the flanking genes thdf, orf900, yidc, rnpa, rpmh, oric, dnaa, dnan, recf, and gyrb was cloned from the gram-negative plant pathogen xanthomonas campestris pv. campestris 17. these genes are conserved in order with other eubacterial oric genes and code for proteins that share high degrees of identity with their homologues, except for orf900, which has a homologue only in xylella fastidiosa. the dnaa/dnan intergenic region (273 bp) identified to be the min ... | 2002 | 12039751 |
| whole-genome analysis of transporters in the plant pathogen xylella fastidiosa. | the transport systems of the first completely sequenced genome of a plant parasite, xylella fastidiosa, were analyzed. in all, 209 proteins were classified here as constitutive members of transport families; thus, we have identified 69 new transporters in addition to the 140 previously annotated. the analysis lead to several hints on potential ways of controlling the disease it causes on citrus trees. an adp:atp translocator, previously found in intracellular parasites only, was found in x. fast ... | 2002 | 12040127 |
| genomics and x-ray microanalysis indicate that ca2+ and thiols mediate the aggregation and adhesion of xylella fastidiosa. | the availability of the genome sequence of the bacterial plant pathogen xylella fastidiosa, the causal agent of citrus variegated chlorosis, is accelerating important investigations concerning its pathogenicity. plant vessel occlusion is critical for symptom development. the objective of the present study was to search for information that would help to explain the adhesion of x. fastidiosa cells to the xylem. scanning electron microscopy revealed that adhesion may occur without the fastidium gu ... | 2002 | 12045828 |
| the complete nucleotide sequence and environmental distribution of the cryptic, conjugative, broad-host-range plasmid pipo2 isolated from bacteria of the wheat rhizosphere. | plasmid pipo2 is a cryptic, conjugative, broad-host-range plasmid isolated from the wheat rhizosphere. it efficiently self-transfers between alpha, beta and gamma proteobacteria and has a mobilizing/retromobilizing capacity for incq plasmids. the complete nucleotide sequence of pipo2 is presented on the basis of its mini-tn5::luxabtet-tagged derivative, pipo2t. the pipo2 sequence is 39815 bp long and contains at least 43 complete orfs. apart from a suite of orfs with unknown function, all of the ... | 2002 | 12055285 |
| crystal structure of a transcarbamylase-like protein from the anaerobic bacterium bacteroides fragilis at 2.0 a resolution. | a transcarbamylase-like protein essential for arginine biosynthesis in the anaerobic bacterium bacteroides fragilis has been purified and crystallized in space group p4(3)2(1)2 (a=b=153.4 a, c=94.8 a). the structure was solved using a single isomorphous replacement with anomalous scattering (siras) and was refined at 2.0 a resolution to an r-factor of 20.6% (r-free=25.2%). the molecular model is trimeric and comprises 960 amino acid residues, two phosphate groups and 422 water molecules. the mon ... | 2002 | 12095263 |
| cloning and expression of the haloalkane dehalogenase gene dhma from mycobacterium avium n85 and preliminary characterization of dhma. | haloalkane dehalogenases are microbial enzymes that catalyze cleavage of the carbon-halogen bond by a hydrolytic mechanism. until recently, these enzymes have been isolated only from bacteria living in contaminated environments. in this report we describe cloning of the dehalogenase gene dhma from mycobacterium avium subsp. avium n85 isolated from swine mesenteric lymph nodes. the dhma gene has a g+c content of 68.21% and codes for a polypeptide that is 301 amino acids long and has a calculated ... | 2002 | 12147465 |
| evaluation of the genetic structure of xylella fastidiosa populations from different citrus sinensis varieties. | xylella fastidiosa was isolated from sweet orange plants (citrus sinensis) grown in two orchards in the northwest region of the brazilian state of são paulo. one orchard was part of a germ plasm field plot used for studies of citrus variegated chlorosis resistance, while the other was an orchard of c. sinensis cv. pêra clones. these two collections of strains were genotypically characterized by using random amplified polymorphic dna (rapd) and variable number of tandem repeat (vntr) markers. the ... | 2002 | 12147466 |
| comparative genomic analysis of plant-associated bacteria. | this review deals with a comparative analysis of seven genome sequences from plant-associated bacteria. these are the genomes of agrobacterium tumefaciens, mesorhizobium loti, sinorhizobium meliloti, xanthomonas campestris pv campestris, xanthomonas axonopodis pv citri, xylella fastidiosa, and ralstonia solanacearum. genome structure and the metabolism pathways available highlight the compromise between the genome size and lifestyle. despite the recognized importance of the type iii secretion sy ... | 2002 | 12147758 |
| gene disruption by homologous recombination in the xylella fastidiosa citrus variegated chlorosis strain. | mutagenesis by homologous recombination was evaluated in xylella fastidiosa by using the bga gene, coding for beta-galactosidase, as a model. integration of replicative plasmids by homologous recombination between the cloned truncated copy of bga and the endogenous gene was produced by one or two crossover events leading to beta-galactosidase mutants. a promoterless chloramphenicol acetyltransferase gene was used to monitor the expression of the target gene and to select a cvab mutant. | 2002 | 12200328 |
| whole-genome comparative analysis of three phytopathogenic xylella fastidiosa strains. | xylella fastidiosa (xf) causes wilt disease in plants and is responsible for major economic and crop losses globally. owing to the public importance of this phytopathogen we embarked on a comparative analysis of the complete genome of xf pv citrus and the partial genomes of two recently sequenced strains of this species: xf pv almond and xf pv oleander, which cause leaf scorch in almond and oleander plants, respectively. we report a reanalysis of the previously sequenced xf 9a5c (cvc, citrus) st ... | 2002 | 12205291 |
| diversity of endophytic bacterial populations and their interaction with xylella fastidiosa in citrus plants. | citrus variegated chlorosis (cvc) is caused by xylella fastidiosa, a phytopathogenic bacterium that can infect all citrus sinensis cultivars. the endophytic bacterial communities of healthy, resistant, and cvc-affected citrus plants were studied by using cultivation as well as cultivation-independent techniques. the endophytic communities were assessed in surface-disinfected citrus branches by plating and denaturing gradient gel electrophoresis (dgge). dominant isolates were characterized by fat ... | 2002 | 12324338 |
| draft sequencing and comparative genomics of xylella fastidiosa strains reveal novel biological insights. | draft sequencing is a rapid and efficient method for determining the near-complete sequence of microbial genomes. here we report a comparative analysis of one complete and two draft genome sequences of the phytopathogenic bacterium, xylella fastidiosa, which causes serious disease in plants, including citrus, almond, and oleander. we present highlights of an in silico analysis based on a comparison of reconstructions of core biological subsystems. cellular pathway reconstructions have been used ... | 2002 | 12368248 |
| an evolutionary perspective of pierce's disease of grapevine, citrus variegated chlorosis, and mulberry leaf scorch diseases. | xylella fastidiosa causes diseases on a growing list of economically important plants. an understanding of how xylellae diseases originated and evolved is important for disease prevention and management. in this study, we evaluated the phylogenetic relationships of x. fastidiosa strains from citrus, grapevine, and mulberry through the analyses of random amplified polymorphic dnas (rapds) and conserved 16s rdna genes. rapd analysis emphasized the vigorous genome-wide divergence of x. fastidiosa a ... | 2002 | 12402083 |
| competitive hybridization on spotted microarrays as a tool to conduct comparative genomic analyses of xylella fastidiosa strains. | xylella fastidiosa strains are responsible for several plant diseases and since such isolates display a broad host range and complex biological behavior, genomic comparisons employing microarray hybridizations may provide an effective method to compare them. thus, we performed a thorough validation of this type of approach using two recently sequenced strains of this phytopathogen. by matching microarray hybridization results to direct sequence comparisons, we were able to establish precise cuto ... | 2002 | 12423746 |
| a new regulatory dna motif of the gamma subclass proteobacteria: identification of the lexa protein binding site of the plant pathogen xylella fastidiosa. | escherichia coli lexa protein is the repressor of a gene network whose members are directly involved in the repair of damaged dna and in the survival of bacterial cells until dna lesions have been eliminated. the lexa gene is widely present in bacteria, although the sequences of only three lexa-binding sites are known: gram-positive, alpha proteobacteria and some members of gamma proteobacteria represented by e. coli. taking advantage of the fact that the genome sequence of the plant-pathogenic ... | 2002 | 12427949 |
| interactive effects of water stress and xylem-limited bacterial infection on the water relations of a host vine. | xylella fastidiosa, a xylem-limited bacterial pathogen that causes bacterial leaf scorch in its hosts, has a diverse and extensive host range among plant species worldwide. previous work has shown that water stress enhances leaf scorch symptom severity and progression along the stem in parthenocissus quinquefolia infected by x. fastidiosa. the objective here was to investigate the mechanisms underlying the interaction of water stress and infection by x. fastidiosa. using the eastern deciduous fo ... | 2003 | 12493870 |
| growth optimization procedures for the phytopathogen xylella fastidiosa. | for the first time, growth curves are shown for the phytopathogen xylella fastidiosa on traditional growth media such as pw (periwinkle wilt), bcye (buffered charcoal yeast extract), and on new ones such as gye (glutamate yeast extract) and pye (phosphate yeast extract) that were developed in this work. the optimal growth conditions on solid and liquid media as well as their measurements are presented, by using total protein content and turbidity determinations. the results demonstrated that yea ... | 2003 | 12520363 |
| comparative analyses of the complete genome sequences of pierce's disease and citrus variegated chlorosis strains of xylella fastidiosa. | xylella fastidiosa is a xylem-dwelling, insect-transmitted, gamma-proteobacterium that causes diseases in many plants, including grapevine, citrus, periwinkle, almond, oleander, and coffee. x. fastidiosa has an unusually broad host range, has an extensive geographical distribution throughout the american continent, and induces diverse disease phenotypes. previous molecular analyses indicated three distinct groups of x. fastidiosa isolates that were expected to be genetically divergent. here we r ... | 2003 | 12533478 |
| organic hydroperoxide resistance gene encodes a thiol-dependent peroxidase. | ohr (organic hydroperoxide resistance gene) is present in several species of bacteria, and its deletion renders cells specifically sensitive to organic peroxides. the goal of this work was to determine the biochemical function of ohr from xylella fastidiosa. all of the ohr homologues possess two cysteine residues, one of them located in a vcp motif, which is also present in all of the proteins from the peroxiredoxin family. therefore, we have investigated whether ohr possesses thiol-dependent pe ... | 2003 | 12540833 |
| genetic differences between two strains of xylella fastidiosa revealed by suppression subtractive hybridization. | suppression subtractive hybridization was used to rapidly identify 18 gene differences between a citrus variegated chlorosis (cvc) strain and a pierce's disease of grape (pd) strain of xylella fastidiosa. the results were validated as being highly representative of actual differences by comparison of the completely sequenced genome of a cvc strain with that of a pd strain. | 2003 | 12571065 |
| genomics-based design of defined growth media for the plant pathogen xylella fastidiosa. | based on the genetic analysis of the phytopathogen xylella fastidiosa genome, five media with defined composition were developed and the growth abilities of this fastidious prokaryote were evaluated in liquid media and on solid plates. all media had a common salt composition and included the same amounts of glucose and vitamins but differed in their amino acid content. xdm(1) medium contained amino acids threonine, serine, glycine, alanine, aspartic acid and glutamic acid, for which complete deg ... | 2003 | 12594021 |
| proteome analysis of the plant pathogen xylella fastidiosa reveals major cellular and extracellular proteins and a peculiar codon bias distribution. | the bacteria xylella fastidiosa is the causative agent of a number of economically important crop diseases, including citrus variegated chlorosis. although its complete genome is already sequenced, x. fastidiosa is very poorly characterized by biochemical approaches at the protein level. in an initial effort to characterize protein expression in x. fastidiosa we used one- and two-dimensional gel electrophoresis and mass spectrometry to identify the products of 142 genes present in a whole cell e ... | 2003 | 12601815 |
| lateral gene transfer and ancient paralogy of operons containing redundant copies of tryptophan-pathway genes in xylella species and in heterocystous cyanobacteria. | tryptophan-pathway genes that exist within an apparent operon-like organization were evaluated as examples of multi-genic genomic regions that contain phylogenetically incongruous genes and coexist with genes outside the operon that are congruous. a seven-gene cluster in xylella fastidiosa includes genes encoding the two subunits of anthranilate synthase, an aryl-coa synthetase, and trpr. a second gene block, present in the anabaena/nostoc lineage, but not in other cyanobacteria, contains a near ... | 2003 | 12620124 |
| microarray analyses of xylella fastidiosa provide evidence of coordinated transcription control of laterally transferred elements. | genetically distinct strains of the plant bacterium xylella fastidiosa (xf) are responsible for a variety of plant diseases, accounting for severe economic damage throughout the world. using as a reference the genome of xf 9a5c strain, associated with citrus variegated chlorosis (cvc), we developed a microarray-based comparison involving 12 xf isolates, providing a thorough assessment of the variation in genomic composition across the group. our results demonstrate that xf displays one of the la ... | 2003 | 12670998 |
| expression of putative pathogenicity-related genes in xylella fastidiosa grown at low and high cell density conditions in vitro. | xylella fastidiosa is the causal agent of economically important plant diseases, including citrus variegated chlorosis and pierce's disease. hitherto, there has been no information on the molecular mechanisms controlling x. fastidiosa-plant interactions. to determine whether predicted open reading frames (orfs) encoding putative pathogenicity-related factors were expressed by x. fastidiosa 9a5c cells grown at low (lcd) and high cell density (hcd) conditions in liquid modified pw medium, reverse ... | 2003 | 12757950 |
| detection and diversity assessment of xylella fastidiosa in field-collected plant and insect samples by using 16s rrna and gyrb sequences. | the causal agent of diseases in many economically important plants is attributed to the xylem-limited bacterium xylella fastidiosa. the detection of this plant pathogen has been hampered due to its difficult isolation and slow growth on plates. nearly complete nucleotide sequences of the 16s rrna gene and partial sequences of the gyrb gene were determined for 18 strains of x. fastidiosa isolated from different plant hosts. a phylogenetic analysis, based on gyrb, grouped strains in three clusters ... | 2003 | 12839807 |
| analysis of gene expression in two growth states of xylella fastidiosa and its relationship with pathogenicity. | xylella fastidiosa is a plant pathogen responsible for diseases of economically important crops. although there is considerable disagreement about its mechanism of pathogenicity, blockage of the vessels is one of the most accepted hypotheses. loss of virulence by this bacterium was observed after serial passages in axenic culture. to confirm the loss of pathogenicity of x. fastidiosa, the causing agent of citrus variegated chlorosis (cvc), freshly-isolated bacteria (first passage [fp] condition) ... | 2003 | 14558688 |
| dispersion of homalodisca coagulata (hemiptera: cicadellidae), a vector of xylella fastidiosa, into vineyards in southern california. | recent epidemics of pierce's disease of grapevine in california vectored by homalodisca coagulata (say), an invasive vector species, have characteristics that differ from epidemics involving native vectors. among these differences are the longer distances and greater speed that the disease is spread by h. coagulata. in this investigation, we used yellow sticky traps to study the seasonal dispersion activity of h. coagulata in a southern california grape-growing area in which an epidemic of pierc ... | 2003 | 14650508 |
| the biology of xylem fluid-feeding insect vectors of xylella fastidiosa and their relation to disease epidemiology. | xylophagous leafhopppers are common and abundant insects of tropical and subtropical environments and play important ecological roles in these ecosystems. the feeding biology of these insects is unique in terms of their high feeding rates and a digestive physiology that allows them to assimilate amino acids, organic acids, and sugars at approximately 99% efficiency. for those species well studied, fluctuations in plant xylem chemistry and tension appear to determine the diurnal and seasonal use ... | 2004 | 14651464 |
| effects of temperature on the flight activity of graphocephala atropunctata (hemiptera: cicadellidae). | graphocephala atropunctata (signoret) is the principal vector of xylella fastidiosa (wells, raju, hung, weisberg, mandelco-paul and brenner), the bacterium that causes pierce's disease of grapevine in coastal california. monitoring the activity of c. atropunctata in the early spring is important for timing insecticide sprays and assessing the potential for disease spread to adjacent vineyards. trapping studies with yellow sticky traps over 3 yr in napa valley, ca, established a significant corre ... | 2000 | 14658516 |
| use of a green fluorescent strain for analysis of xylella fastidiosa colonization of vitis vinifera. | xylella fastidiosa causes pierce's disease of grapevine as well as several other major agricultural diseases but is a benign endophyte in most host plants. x. fastidiosa colonizes the xylem vessels of host plants and is transmitted by xylem sap-feeding insect vectors. to understand better the pattern of host colonization and its relationship to disease, we engineered x. fastidiosa to express a green fluorescent protein (gfp) constitutively and performed confocal laser-scanning microscopic analys ... | 2003 | 14660381 |
| biological traits of xylella fastidiosa strains from grapes and almonds. | xylella fastidiosa is a xylem-limited bacterium that causes various diseases, among them pierce's disease of grapevine (pd) and almond leaf scorch (als). pd and als have long been considered to be caused by the same strain of this pathogen, but recent genetic studies have revealed differences among x. fastidiosa isolated from these host plants. we tested the hypothesis that als is caused by pd and als strains in the field and found that both groups of x. fastidiosa caused als and overwintered wi ... | 2003 | 14660397 |
| expression and purification of a putative h-ns nucleoid-associated protein from the phytopathogen xylella fastidiosa. | the h-ns protein is one of the major constituents of the nucleoid structure that has been implicated in the dna packaging and in the global regulation of gene expression. the study of this transcriptional regulator is an effort to fight xylella fastidiosa, a citrus pathogen responsible for a range of economically important plant diseases, including the citrus variegated chlorosis (cvc). the putative h-ns orf was cloned into a pet32-xa/lic vector in order to overexpress it coupled with fusion tag ... | 2003 | 14680940 |
| complete sequence and evolutionary genomic analysis of the pseudomonas aeruginosa transposable bacteriophage d3112. | bacteriophage d3112 represents one of two distinct groups of transposable phage found in the clinically relevant, opportunistic pathogen pseudomonas aeruginosa. to further our understanding of transposable phage in p. aeruginosa, we have sequenced the complete genome of d3112. the genome is 37,611 bp, with an overall g+c content of 65%. we have identified 53 potential open reading frames, including three genes (the c repressor gene and early genes a and b) that have been previously characterized ... | 2004 | 14702309 |
| expression and purification of a small heat shock protein from the plant pathogen xylella fastidiosa. | the small heat shock proteins (smhsps) belong to a family of proteins that function as molecular chaperones by preventing protein aggregation and are also known to contain a conserved region termed alpha-crystallin domain. here, we report the expression, purification, and partial characterization of a novel smhsp (hsp17.9) from the phytopathogen xylella fastidiosa, causal agent of the citrus variegated chlorosis (cvc). the gene was cloned into a pet32-xa/lic vector to over-express the protein co ... | 2004 | 14711518 |
| crystallization and preliminary x-ray diffraction analysis of an oxidized state of ohr from xylella fastidiosa. | xylella fastidiosa organic hydroperoxide-resistance protein (ohr) is a dithiol-dependent peroxidase that is widely conserved in several pathogenic bacteria with high affinity for organic hydroperoxides. the protein was crystallized using the hanging-drop vapour-diffusion method in the presence of peg 4000 as precipitant after treatment with organic peroxide (t-butyl hydroperoxide). x-ray diffraction data were collected to a maximum resolution of 1.8 a using a synchrotron-radiation source. the cr ... | 2004 | 14747717 |
| cell-cell signaling controls xylella fastidiosa interactions with both insects and plants. | xylella fastidiosa, which causes pierce's disease of grapevine and other important plant diseases, is a xylem-limited bacterium that depends on insect vectors for transmission. although many studies have addressed disease symptom development and transmission of the pathogen by vectors, little is known about the bacterial mechanisms driving these processes. recently available x. fastidiosa genomic sequences and molecular tools have provided new routes for investigation. here, we show that a diffu ... | 2004 | 14755059 |
| colony aggregation and biofilm formation in xylem chemistry-based media for xylella fastidiosa. | two chemically defined media based on xylem fluid chemistry were developed for xylella fastidiosa. these media were tested and compared to chemically defined media xdm2, xdm4 and xf-26. new media were evaluated for the pierce's disease (pd) strain ucla-pd. our media either was similar to the concentration of some amino acids found in the xylem fluid of the pd-susceptible vitis vinifera cv. chardonnay (medium chard2) or incorporated the tripeptide glutathione found in xylem fluid composition (med ... | 2004 | 14757251 |
| overexpression, purification, biochemical characterization, and molecular modeling of recombinant gdp-mannosyltransferase (gumh) from xylella fastidiosa. | the gumh enzyme from xylella fastidiosa catalyzes the transfer reaction of a mannose from gdp-mannose to the carrier lipid cellobiose-pyrophosphate-polyprenol (glc(2)-pp-lip), an intermediary in the reaction for the synthesis of the exopolysaccharide (eps) fastidian gum. the gumh gene was subcloned in the pmal-c2x vector, allowing the expression of the gumh-mbp fusion protein. various attempts were made to obtain protein with the necessary degree of purity for crystallographic studies but the yi ... | 2004 | 14766234 |
| a nested-pcr assay for detection of xylella fastidiosa in citrus plants and sharpshooter leafhoppers. | detection of xylella fastidiosa in citrus plants and insect vectors. | 2004 | 14962134 |
| transmission of xylella fastidiosa to grapevines by homalodisca coagulata (hemiptera: cicadellidae). | pierce's disease (pd) of grapevines is caused by a xylem-limited bacterium xylella fastidiosa (wells, raju, hung, weisburg, mandelco-paul, and brenner) that is transmitted to plants by xylem sap-feeding insects. the introduction of the sharpshooter leafhopper homalodisca coagulata (say) into california has initiated new pd epidemics in southern california. in laboratory experiments, the major characteristics of h. coagulata's transmission of x. fastidiosa to grapevines were the same as reported ... | 2003 | 14994789 |
| overexpression, purification, and biochemical characterization of gumc, an enzyme involved in the biosynthesis of exopolysaccharide by xylella fastidiosa. | gumc is one of nine enzymes involved in the biosynthesis of fastidian gum, an exopolysaccharide produced by xylella fastidiosa that may be linked directly to the pathogenicity of the microorganism. gumc may be responsible for gum polymerization or secretion through the membrane of x. fastidiosa. to perform structure and functions studies, we developed an expression system for the production of gumc as a fusion protein with maltose binding protein (mbp) using pmal-c2x vector. the gumc-mbp fusion ... | 2004 | 15003255 |
| fastidious xylem-limited bacterial plant pathogens. | numerous bacteria have been isolated from within plants, and many reported from xylem, but only three species of xylem-limited bacteria (xlb) that are fastidious in cultural requirements, are plant pathogens, and exclusively occupy xylem, have been well characterized. two xlb, xylella fastidiosa and pseudomonas syzygii, are transmitted by sucking insects that feed on xylem sap but are not transmitted mechanically from plant to plant. in contrast, clavibacter xyli is mechanically transmitted to p ... | 1996 | 15012538 |
| isolation and phylogenetic analysis of xylella fastidiosa from its invasive alternative host, porcelain berry. | a strain of xylella fastidiosa was isolated from an invasive alternative host species, porcelain berry. its genetic relationship with strains isolated from a native alternative host, wild grape; a nonnative alternative host, mulberry; and other economically important hosts including cultivated grape, peach, plum, oak, maple and oleander was determined by using sequence analysis of the 16s-23s rrna intergenic spacer region. our phylogenetic analysis revealed that the porcelain berry strain is mos ... | 2004 | 15018107 |
| insertional transposon mutagenesis in the xylella fastidiosa citrus variegated chlorosis strain with transposome. | to overcome the difficulty in obtaining mutants of the citrus strains of xylella fastidiosa, we evaluated mutagenesis using the transposome system as a tool for the isolation of a large number of mutants. electroporation of a commercial transposome system in x. fastidiosa cvc (citrus variegated chlorosis) strain j1a12 yielded an efficiency of 1.2 x 10(3) kanamycin (km)-resistant clones per microg of dna. southern blot analysis demonstrated that the transposon was randomly inserted, and nucleotid ... | 2004 | 15057448 |
| delivery of a genetically marked alcaligenes sp. to the glassy-winged sharpshooter for use in a paratransgenic control strategy. | an artificial feeding system was designed for the glassy-winged sharpshooter (gwss), homalodisca coagulata say (hemiptera: cicadellidae). the system, unlike previous systems, provided enough nutrients to gwss to survive for 48 h. a system like this is a prerequisite to examining the potential use of paratransgenesis to interrupt transmission of xylella fastidiosa, the bacterial pathogen causing pierce's disease of grape, by insect vectors. we developed a system for short-term feeding of gwss tha ... | 2004 | 15060727 |
| xylella fastidiosa cultivation on a minimal solid defined medium. | a simple defined solid medium containing citrate and succinate, three amino acids (l-glutamine, l-asparagine, and l-cysteine), hemin chloride, potato starch, gellan gum (gelrite), and mineral salts supported the growth of grape strains of xylella fastidiosa, the bacterial pathogen that causes pierce's disease of grape. isolation efficiency from infected grape plant samples, determined by the number of colony forming units recovered, on the defined medium was slightly less ( approximately 10-fold ... | 2004 | 15060734 |
| bacterial variations on the methionine salvage pathway. | the thiomethyl group of s-adenosylmethionine is often recycled as methionine from methylthioadenosine. the corresponding pathway has been unravelled in bacillus subtilis. however methylthioadenosine is subjected to alternative degradative pathways depending on the organism. | 2004 | 15102328 |
| regulation of the htpx gene of xylella fastidiosa and its expression in e. coli. | xylella fastidiosa was the first phytopathogen to be completely sequenced, and its genome revealed several interesting features to be used in functional studies. in the present work, the htpx gene, which encodes a protein involved in the heat shock response in other bacteria, was analyzed by rt-pcr by using cells derived from different cultural conditions. this gene was induced after a temperature upshift to 37 degrees c after growth in minimal medium, xdm, but showed constitutive expression in ... | 2004 | 15170231 |
| quantifying intrachromosomal gc heterogeneity in prokaryotic genomes. | the sequencing of prokaryotic genomes covering a wide taxonomic range has sparked renewed interest in intrachromosomal compositional (gc) heterogeneity, largely in view of lateral transfers. we present here a brief overview of some methods for visualizing and quantifying gc variation in prokaryotes. we used these methods to examine heterogeneity levels in sequenced prokaryotes, for a range of scales or stringencies. some species are consistently homogeneous, whereas others are markedly heterogen ... | 2004 | 15177687 |
| interaction between endophytic bacteria from citrus plants and the phytopathogenic bacteria xylella fastidiosa, causal agent of citrus-variegated chlorosis. | to isolate endophytic bacteria and xylella fastidiosa and also to evaluate whether the bacterial endophyte community contributes to citrus-variegated chlorosis (cvc) status in sweet orange (citrus sinensis [l.] osbeck cv. pera). | 2004 | 15189288 |
| xylella fastidiosa subspecies: x. fastidiosa subsp. [correction] fastidiosa [correction] subsp. nov., x. fastidiosa subsp. multiplex subsp. nov., and x. fastidiosa subsp. pauca subsp. nov. | xylella fastidiosa, a fastidious bacterium causing disease in over 100 plant species, is classified as a single species, although genetic studies support multiple taxons. to determine the taxonomic relatedness among strains of x. fastidiosa, we conducted dna-dna relatedness assays and sequenced the 16s-23s intergenic spacer (its) region using 26 strains from 10 hosts. under stringent conditions (tm -15 degrees c), the dna relatedness for most x. fastidiosa strains was *70%. however, at high stri ... | 2004 | 15214634 |
| global features of sequences of bacterial chromosomes, plasmids and phages revealed by analysis of oligonucleotide usage patterns. | oligonucleotide frequencies were shown to be conserved signatures for bacterial genomes, however, the underlying constraints have yet not been resolved in detail. in this paper we analyzed oligonucleotide usage (ou) biases in a comprehensive collection of 155 completely sequenced bacterial chromosomes, 316 plasmids and 104 phages. | 2004 | 15239845 |
| molecular models for shikimate pathway enzymes of xylella fastidiosa. | the xylella fastidiosa is a bacterium that is the cause of citrus variegated chlorosis (cvc). the shikimate pathway is of pivotal importance for production of a plethora of aromatic compounds in plants, bacteria, and fungi. putative structural differences in the enzymes from the shikimate pathway, between the proteins of bacterial origin and those of plants, could be used for the development of a drug for the control of cvc. however, inhibitors for shikimate pathway enzymes should have high spec ... | 2004 | 15240145 |
| a kinetic model for xylella fastidiosa adhesion, biofilm formation, and virulence. | xylella fastidiosa is the causal agent of citrus variegated chlorosis and pierce's disease which are the major threat to the citrus and wine industries. the most accepted hypothesis for xf diseases affirms that it is a vascular occlusion caused by bacterial biofilm, embedded in an extracellular translucent matrix that was deduced to be the exopolysaccharide fastidian. fourier transform infrared spectroscopy analysis demonstrated that virulent cells which form biofilm on glass have low fastidian ... | 2004 | 15251213 |
| evaluation of methods for extracting xylella fastidiosa dna from the glassy-winged sharpshooter. | the recent spread of the plant pathogenic bacterium xylclla fastidiosa wells et al. by an invasive vector species, homalodisca coagulata say, in southern california has resulted in new epidemics of pierce's disease of grapevine. our goal is to develop an efficient method to detect low titers of x. fastidiosa in h. coagulata that is amenable to large sample sizes for epidemiological studies. detection of the plant pathogenic bacterium x. fastidiosa in its insect vector is complicated by low titer ... | 2004 | 15279249 |