The Experts below are selected from a list of 6672 Experts worldwide ranked by ideXlab platform
Patrícia B. Monteiro - One of the best experts on this subject based on the ideXlab platform.
-
Disruption of Xylella fastidiosa CVC gumB and gumF genes affects biofilm formation without a detectable influence on exopolysaccharide production.
FEMS microbiology letters, 2006Co-Authors: Leonardo C. A. Souza, Anelise Galdino Mariano, N. A. Wulff, Patrice Gaurivaud, Andrea C. D. Virgílio, João Lúcio De Azevedo, Patrícia B. MonteiroAbstract:Xylella fastidiosa causes citrus variegated chlorosis (CVC), a destructive disease of citrus. Xylella fastidiosa forms a biofilm inside plants and insect vectors. Biofilms are complex structures involving X. fastidiosa cells and an extracellular matrix which blocks water and nutrient transport in diseased plants. It is hypothesized that the matrix might be composed of an extracellular polysaccharide (EPS), coded by a cluster of nine genes closely related to the xanthan gum operon of Xanthomonas campestris pv. campestris. To understand the role of X. fastidiosa gum genes on biofilm formation and EPS biosynthesis, we produced gumB and gumF mutants. Xylella fastidiosa mutants were obtained by insertional duplication mutagenesis and recovered after triply cloning the cells. Xylella fastidiosa gumB and gumF mutants exhibited normal cell characteristics; typical colony morphology and EPS biosynthesis were not altered. It was of note that X. fastidiosa mutants showed a reduced capacity to form biofilm when BCYE was used as the sustaining medium, a difference not observed with PW medium. Unlike X. campestris pv. campestris, the expression of the X. fastidiosa gumB or gumF genes was not regulated by glucose.
-
A Suitable Xylella fastidiosa CVC Strain for Post-Genome Studies
Current microbiology, 2004Co-Authors: D. C. Teixeira, Sanvai Regina Prado Rocha, Mateus De Almeida Santos, Anelise Galdino Mariano, Wen Bin Li, Patrícia B. MonteiroAbstract:The genome sequence of the pathogen Xylella fastidiosa Citrus Variegated Chlorosis (CVC) strain 9a5c has revealed many genes related to pathogenicity mechanisms and virulence determinants.
-
Gene disruption by homologous recombination in the Xylella fastidiosa citrus variegated chlorosis strain.
Applied and environmental microbiology, 2002Co-Authors: Patrice Gaurivaud, Anelise Galdino Mariano, Leonardo C. A. Souza, Andrea C. D. Virgílio, Renê R. Palma, Patrícia B. MonteiroAbstract:Mutagenesis by homologous recombination was evaluated in Xylella fastidiosa by using the bga gene, coding for β-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 β-galactosidase mutants. A promoterless chloramphenicol acetyltransferase gene was used to monitor the expression of the target gene and to select a cvaB mutant.
Mônica A. Cotta - One of the best experts on this subject based on the ideXlab platform.
-
Stiffness signatures along early stages of Xylella fastidiosa biofilm formation.
Colloids and surfaces. B Biointerfaces, 2017Co-Authors: Moniellen P. Monteiro, Prasana Sahoo, Carlos L. Cesar, Alessandra A. De Souza, João H. Clerici, Mônica A. CottaAbstract:The pathogenicity of Xylella fastidiosa is associated with its systematic colonization of the plant xylem, forming bacterial biofilms. Mechanisms of bacterial transport among different xylem vessels, however, are not completely understood yet, but are strongly influenced by the presence of extracellular polymeric substances (EPS), which surrounds the assembly of cells forming the biofilm. In this work, we show quantitative measurements on the elastic properties of the system composed by EPS and bacterial cell. In order to investigate the mechanical properties of this system, force spectroscopy and confocal Raman measurements were carried out during Xylella fastidiosa subsp. pauca initial stages of adhesion and cluster formation. We show that stiffness progressively decreases with increasing culture growth time, from two to five days. For early adhesion samples, stiffness values are quite different at the bacterial polar and body regions. Lower stiffness values at the cell pole suggest a flexible mechanical response at this region, associated with first cell adhesion to a surface. These results correlate very well with our observations of cell motion within microchannels, under conditions simulating xylem flow. Both the oscillatory movement of vertically attached single cells, as well as the transport of cell clusters within the biofilm matrix can be explained by the presence of softer materials at the cell pole and EPS matrix. Our results may thus add to a more detailed understanding of mechanisms used by cells to migrate among vessels in plant xylem.
-
Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation
Scientific Reports, 2015Co-Authors: Richard Janissen, Duber M. Murillo, Barbara Niza, Prasana Sahoo, Marcelo M. Nobrega, Carlos L. Cesar, Marcia L. A. Temperini, Hernandes F. Carvalho, Alessandra A. De Souza, Mônica A. CottaAbstract:Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation
-
Fractal analysis of Xylella fastidiosa biofilm formation
Journal of Applied Physics, 2009Co-Authors: Alberto Luís Dario Moreau, Alessandra A. De Souza, Gabriela S. Lorite, Carolina M. Rodrigues, Mônica A. CottaAbstract:We have investigated the growth process of Xylella fastidiosa biofilms inoculated on a glass. The size and the distance between biofilms were analyzed by optical images; a fractal analysis was carried out using scaling concepts and atomic force microscopy images. We observed that different biofilms show similar fractal characteristics, although morphological variations can be identified for different biofilm stages. Two types of structural patterns are suggested from the observed fractal dimensions Df. In the initial and final stages of biofilm formation, Df is 2.73±0.06 and 2.68±0.06, respectively, while in the maturation stage, Df=2.57±0.08. These values suggest that the biofilm growth can be understood as an Eden model in the former case, while diffusion-limited aggregation (DLA) seems to dominate the maturation stage. Changes in the correlation length parallel to the surface were also observed; these results were correlated with the biofilm matrix formation, which can hinder nutrient diffusion and thu...
Alessandra A. De Souza - One of the best experts on this subject based on the ideXlab platform.
-
Stiffness signatures along early stages of Xylella fastidiosa biofilm formation.
Colloids and surfaces. B Biointerfaces, 2017Co-Authors: Moniellen P. Monteiro, Prasana Sahoo, Carlos L. Cesar, Alessandra A. De Souza, João H. Clerici, Mônica A. CottaAbstract:The pathogenicity of Xylella fastidiosa is associated with its systematic colonization of the plant xylem, forming bacterial biofilms. Mechanisms of bacterial transport among different xylem vessels, however, are not completely understood yet, but are strongly influenced by the presence of extracellular polymeric substances (EPS), which surrounds the assembly of cells forming the biofilm. In this work, we show quantitative measurements on the elastic properties of the system composed by EPS and bacterial cell. In order to investigate the mechanical properties of this system, force spectroscopy and confocal Raman measurements were carried out during Xylella fastidiosa subsp. pauca initial stages of adhesion and cluster formation. We show that stiffness progressively decreases with increasing culture growth time, from two to five days. For early adhesion samples, stiffness values are quite different at the bacterial polar and body regions. Lower stiffness values at the cell pole suggest a flexible mechanical response at this region, associated with first cell adhesion to a surface. These results correlate very well with our observations of cell motion within microchannels, under conditions simulating xylem flow. Both the oscillatory movement of vertically attached single cells, as well as the transport of cell clusters within the biofilm matrix can be explained by the presence of softer materials at the cell pole and EPS matrix. Our results may thus add to a more detailed understanding of mechanisms used by cells to migrate among vessels in plant xylem.
-
Draft Genome Sequence of 11399, a Transformable Citrus-Pathogenic Strain of Xylella fastidiosa
Genome announcements, 2016Co-Authors: Barbara Niza, Marcos Antonio Machado, Marco A. Takita, Valquíria Campos Alencar, Luiz R. Nunes, Marcus V. Merfa, Fabiano Bezerra Menegidio, Alessandra A. De SouzaAbstract:ABSTRACT The draft genome of Xylella fastidiosa subsp. pauca strain 11399, a transformable citrus-pathogenic strain, is reported here. The 11399 genome size is 2,690,704 bp and has a G+C content of 52.7%. The draft genome of 11399 reveals the absence of four type I restriction-modification system genes.
-
Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation
Scientific Reports, 2015Co-Authors: Richard Janissen, Duber M. Murillo, Barbara Niza, Prasana Sahoo, Marcelo M. Nobrega, Carlos L. Cesar, Marcia L. A. Temperini, Hernandes F. Carvalho, Alessandra A. De Souza, Mônica A. CottaAbstract:Spatiotemporal distribution of different extracellular polymeric substances and filamentation mediate Xylella fastidiosa adhesion and biofilm formation
-
Analysis of the biofilm proteome of Xylella fastidiosa
Proteome science, 2011Co-Authors: Mariana De Souza E Silva, Alessandra A. De Souza, Marco A. Takita, Carlos Alberto Labate, Marcos Antonio MachadoAbstract:Background Xylella fastidiosa is limited to the xylem of the plant host and the foregut of insect vectors (sharpshooters). The mechanism of pathogenicity of this bacterium differs from other plant pathogens, since it does not present typical genes that confer specific interactions between plant and pathogens (avr and/or hrp). The bacterium is injected directly into the xylem vessels where it adheres and colonizes. The whole process leads to the formation of biofilms, which are considered the main mechanism of pathogenicity. Cells in biofilms are metabolically and phenotypically different from their planktonic condition. The mature biofilm stage (phase of higher cell density) presents high virulence and resistance to toxic substances such as antibiotics and detergents. Here we performed proteomic analysis of proteins expressed exclusively in the mature biofilm of X. fastidiosa strain 9a5c, in comparison to planktonic growth condition.
-
Fractal analysis of Xylella fastidiosa biofilm formation
Journal of Applied Physics, 2009Co-Authors: Alberto Luís Dario Moreau, Alessandra A. De Souza, Gabriela S. Lorite, Carolina M. Rodrigues, Mônica A. CottaAbstract:We have investigated the growth process of Xylella fastidiosa biofilms inoculated on a glass. The size and the distance between biofilms were analyzed by optical images; a fractal analysis was carried out using scaling concepts and atomic force microscopy images. We observed that different biofilms show similar fractal characteristics, although morphological variations can be identified for different biofilm stages. Two types of structural patterns are suggested from the observed fractal dimensions Df. In the initial and final stages of biofilm formation, Df is 2.73±0.06 and 2.68±0.06, respectively, while in the maturation stage, Df=2.57±0.08. These values suggest that the biofilm growth can be understood as an Eden model in the former case, while diffusion-limited aggregation (DLA) seems to dominate the maturation stage. Changes in the correlation length parallel to the surface were also observed; these results were correlated with the biofilm matrix formation, which can hinder nutrient diffusion and thu...
Thomas J. Burr - One of the best experts on this subject based on the ideXlab platform.
-
Potential complications when developing gene deletion clones in Xylella fastidiosa.
BMC research notes, 2015Co-Authors: Kameka L Johnson, Thomas J. Burr, Luciana Cursino, Dusit Athinuwat, Patricia MoweryAbstract:Background The Gram-negative xylem-limited bacterium, Xylella fastidiosa, is an important plant pathogen that infects a number of high value crops. The Temecula 1 strain infects grapevines and induces Pierce′s disease, which causes symptoms such as scorching on leaves, cluster collapse, and eventual plant death. In order to understand the pathogenesis of X. fastidiosa, researchers routinely perform gene deletion studies and select mutants via antibiotic markers.
-
Twitching motility and biofilm formation are associated with tonB1 in Xylella fastidiosa
FEMS microbiology letters, 2009Co-Authors: Luciana Cursino, Paulo A. Zaini, Harvey C. Hoch, Leonardo De La Fuente, Thomas J. BurrAbstract:A mutation in the Xylella fastidiosa tonB1 gene resulted in loss of twitching motility and in significantly less biofilm formation as compared with a wild type. The altered motility and biofilm phenotypes were restored by complementation with a functional copy of the gene. The mutation affected virulence as measured by Pierce's disease symptoms on grapevines. The role of TonB1 in twitching and biofilm formation appears to be independent of the characteristic iron-uptake function of this protein. This is the first report demonstrating a functional role for a tonB homolog in X. fastidiosa.
-
Grapevinexylemsapenhancesbio¢lmdevelopmentby Xylella fastidiosa
2009Co-Authors: Paulo A. Zaini, Harvey C. Hoch, Thomas J. BurrAbstract:Xylella fastidiosa is able to form biofilms within xylem vessels of many economically important crops. Vessel blockage is believed to be a major contributor to disease development caused by this bacterium. This report shows that Vitis riparia xylem sap increases growth rate and induces a characteristic biofilm architecture as compared with biofilms formed in PD2 and PWmedia. In addition, stable cultures could be maintained, frozen and reestablished in xylem sap. These findings are important as xylem sap provides a natural medium that facilitates the identification of virulence determinants of Pierce’s disease.
-
Grapevine xylem sap enhances biofilm development by Xylella fastidiosa.
FEMS microbiology letters, 2009Co-Authors: Paulo A. Zaini, Harvey C. Hoch, Leonardo De La Fuente, Thomas J. BurrAbstract:Xylella fastidiosa is able to form biofilms within xylem vessels of many economically important crops. Vessel blockage is believed to be a major contributor to disease development caused by this bacterium. This report shows that Vitis riparia xylem sap increases growth rate and induces a characteristic biofilm architecture as compared with biofilms formed in PD2 and PW media. In addition, stable cultures could be maintained, frozen and reestablished in xylem sap. These findings are important as xylem sap provides a natural medium that facilitates the identification of virulence determinants of Pierce's disease.
-
Autoaggregation of Xylella fastidiosa Cells Is Influenced by Type I and Type IV Pili
Applied and environmental microbiology, 2008Co-Authors: Leonardo De La Fuente, Thomas J. Burr, Harvey C. HochAbstract:Autoaggregation of widely dispersed Xylella fastidiosa cells into compact cell masses occurred over a period of hours following 7 to 11 days of growth in microfluidic chambers. Studies involving the use of mutants defective in polarly positioned type I (fimA-negative), type IV (pilB-negative), or both type I and IV (fimA- and pilO-negative) pili revealed the importance and role of pili in the autoaggregation process.
Marcos Antonio Machado - One of the best experts on this subject based on the ideXlab platform.
-
Draft Genome Sequence of 11399, a Transformable Citrus-Pathogenic Strain of Xylella fastidiosa
Genome announcements, 2016Co-Authors: Barbara Niza, Marcos Antonio Machado, Marco A. Takita, Valquíria Campos Alencar, Luiz R. Nunes, Marcus V. Merfa, Fabiano Bezerra Menegidio, Alessandra A. De SouzaAbstract:ABSTRACT The draft genome of Xylella fastidiosa subsp. pauca strain 11399, a transformable citrus-pathogenic strain, is reported here. The 11399 genome size is 2,690,704 bp and has a G+C content of 52.7%. The draft genome of 11399 reveals the absence of four type I restriction-modification system genes.
-
Expression of Xylella fastidiosa RpfF in Citrus Disrupts Signaling in Xanthomonas citri subsp. citri and Thereby Its Virulence
Molecular plant-microbe interactions : MPMI, 2014Co-Authors: Raquel Caserta, Michael Ionescu, Steven E. Lindow, Marcos Antonio Machado, Marco A. Takita, Simone Cristina Picchi, Juarez Pires Tomaz, Walter Esfrain Pereira, A. A. De SouzaAbstract:Xylella fastidiosa and Xanthomonas citri subsp. citri, that cause citrus variegated chlorosis (CVC) and citrus canker diseases, respectively, utilize diffusible signal factor (DSF) for quorum sensing. DSF, produced by RpfF, are similar fatty acids in both organisms, although a different set of genes is regulated by DSF in each species. Because of this similarity, Xylella fastidiosa DSF might be recognized and affect the biology of Xanthomonas citri. Therefore, transgenic Citrus sinensis and Carrizo citrange plants overexpressing the Xylella fastidiosa rpfF were inoculated with Xanthomonas citri and changes in symptoms of citrus canker were observed. X. citri biofilms formed only at wound sites on transgenic leaves and were thicker; however, bacteria were unable to break through the tissue and form pustules elsewhere. Although abundant growth of X. citri occurred at wound sites on inoculated transgenic leaves, little growth was observed on unwounded tissue. Genes in the DFS-responsive core in X. citri were...
-
Analysis of the biofilm proteome of Xylella fastidiosa
Proteome science, 2011Co-Authors: Mariana De Souza E Silva, Alessandra A. De Souza, Marco A. Takita, Carlos Alberto Labate, Marcos Antonio MachadoAbstract:Background Xylella fastidiosa is limited to the xylem of the plant host and the foregut of insect vectors (sharpshooters). The mechanism of pathogenicity of this bacterium differs from other plant pathogens, since it does not present typical genes that confer specific interactions between plant and pathogens (avr and/or hrp). The bacterium is injected directly into the xylem vessels where it adheres and colonizes. The whole process leads to the formation of biofilms, which are considered the main mechanism of pathogenicity. Cells in biofilms are metabolically and phenotypically different from their planktonic condition. The mature biofilm stage (phase of higher cell density) presents high virulence and resistance to toxic substances such as antibiotics and detergents. Here we performed proteomic analysis of proteins expressed exclusively in the mature biofilm of X. fastidiosa strain 9a5c, in comparison to planktonic growth condition.
-
analysis of resistance to Xylella fastidiosa within a hybrid population of pera sweet orange murcott tangor
Plant Pathology, 2007Co-Authors: Helvecio D Colettafilho, Alessandra A. De Souza, Marco A. Takita, E O Pereira, M Cristofaniyale, Marcos Antonio MachadoAbstract:Resistance to Xylella fastidiosa was evaluated within a population of 20 interspecific hybrids of Pera sweet orange and Murcott tangor under greenhouse conditions. Efficiency of inoculation, multiplication of bacteria within the plants, xylem vessel morphology, and symptom expression were analysed. The rate of infection ranged from 40 to 100% (average 70%) for all genotypes analysed. Xylella fastidiosa populations ranged from log 0·59 to log 2·13 cells mg−1 tissue for the resistant hybrids. These values were significantly different (P = 0·05) from those obtained for the tolerant (no symptoms but bacteria recovered) or susceptible (symptoms and bacteria recovered) hybrids (log 3·02 to log 4·06 cells mg−1). Xylella fastidiosa was recovered from all hybrids (log 2·31 to 5·03 CFU mg−1 tissue) except the resistant ones. The first foliar symptoms appeared at least 90 days post-inoculation, the time varying according to genotype. No correlation between xylem vessel morphology and disease expression was observed, indicating that the resistance was the result of a genetic response of the host. According to this hypothesis, a high broad-based heritability index for resistance was obtained (0·96) at 210 days from X. fastidiosa inoculations, using bacterial quantification by real-time PCR, which indicated that the influence of the number of bacteria was the result of genetic rather than environmental variations.
-
Analysis of resistance to Xylella fastidiosa within a hybrid population of Pera sweet orange × Murcott tangor
Plant Pathology, 2007Co-Authors: Helvécio D. Coletta-filho, Alessandra A. De Souza, Marco A. Takita, E O Pereira, M. Cristofani-yale, Marcos Antonio MachadoAbstract:Resistance to Xylella fastidiosa was evaluated within a population of 20 interspecific hybrids of Pera sweet orange and Murcott tangor under greenhouse conditions. Efficiency of inoculation, multiplication of bacteria within the plants, xylem vessel morphology, and symptom expression were analysed. The rate of infection ranged from 40 to 100% (average 70%) for all genotypes analysed. Xylella fastidiosa populations ranged from log 0·59 to log 2·13 cells mg−1 tissue for the resistant hybrids. These values were significantly different (P = 0·05) from those obtained for the tolerant (no symptoms but bacteria recovered) or susceptible (symptoms and bacteria recovered) hybrids (log 3·02 to log 4·06 cells mg−1). Xylella fastidiosa was recovered from all hybrids (log 2·31 to 5·03 CFU mg−1 tissue) except the resistant ones. The first foliar symptoms appeared at least 90 days post-inoculation, the time varying according to genotype. No correlation between xylem vessel morphology and disease expression was observed, indicating that the resistance was the result of a genetic response of the host. According to this hypothesis, a high broad-based heritability index for resistance was obtained (0·96) at 210 days from X. fastidiosa inoculations, using bacterial quantification by real-time PCR, which indicated that the influence of the number of bacteria was the result of genetic rather than environmental variations.
