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Sicard A, Merfa MV, Voeltz M, Zeilinger AR, De La Fuente L, Almeida RPP. Discriminating between viable and membrane-damaged cells of the plant pathogen Xylella fastidiosa. PLoS One 2019; 14:e0221119. [PMID: 31442247 PMCID: PMC6707623 DOI: 10.1371/journal.pone.0221119] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 07/30/2019] [Indexed: 12/31/2022] Open
Abstract
Xylella fastidiosa is a plant pathogenic bacterium with devastating consequences to several crops of economic importance across the world. While this pathogen has been studied for over a century in the United States, several aspects of its biology remain to be investigated. Determining the physiological state of bacteria is essential to understand the effects of its interactions with different biotic and abiotic factors on cell viability. Although X. fastidiosa is culturable, its slow growing nature makes this technique cumbersome to assess the physiological state of cells present in a given environment. PMA-qPCR, i.e. the use of quantitative PCR combined with the pre-treatment of cells with the dye propidium monoazide, has been successfully used in a number of studies on human pathogens to calculate the proportion of viable cells, but has less frequently been tested on plant pathogens. We found that the use of a version of PMA, PMAxx, facilitated distinguishing between viable and non-viable cells based on cell membrane integrity in vitro and in planta. Additional experiments comparing the number of culturable, viable, and total cells in planta would help further confirm our initial results. Enhancers, intended to improve the efficacy of PMAxx, were not effective and appeared to be slightly toxic to X. fastidiosa.
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Affiliation(s)
- Anne Sicard
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Marcus V. Merfa
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Michael Voeltz
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Adam R. Zeilinger
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Rodrigo P. P. Almeida
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America
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Novelli S, Gismondi A, Di Marco G, Canuti L, Nanni V, Canini A. Plant defense factors involved in Olea europaea resistance against Xylella fastidiosa infection. JOURNAL OF PLANT RESEARCH 2019; 132:439-455. [PMID: 30993555 DOI: 10.1007/s10265-019-01108-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023]
Abstract
Olive quick decline syndrome (OQDS) is a dangerous plant disease, caused by the bacterium Xylella fastidiosa, which targets olive (Olea europaea). Since field observations suggested that some olive cultivars (i.e. Leccino) were more resistant to OQDS than others (i.e. Cellina di Nardò), the plant defense strategies adopted by olive to contrast X. fastidiosa infection were investigated. In the present study, ELISA and genetic approaches were used to confirm plant infection, while microbial colonization mechanism and distribution in host plant tissues and reactive oxygen species (ROS) levels were examined by light, scanning electron and confocal microscopy analyses. Spectrophotometric and chromatographic techniques were performed to measure secondary metabolites content and qPCR assay was carried out for monitoring plant gene expression variation. Our analysis showed that X. fastidiosa caused accumulation of ROS in Leccino samples compared to Cellina di Nardò. Moreover, the infection induced the up-regulation of defense-related genes, such as NADPH oxidase, some protein kinases, pathogen plant response factors and metabolic enzymes. We also found that Leccino plants enhanced the production of specific antioxidant and antimicrobial molecules, to fight the pathogen and avoid its spreading into xylem vessels. We provided new information on OQDS resistance mechanism applied by Leccino cultivar. In particular, we evidenced that high concentrations of ROS, switching on plant defence signalling pathways, may represent a key factor in fighting X. fastidiosa infection.
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Affiliation(s)
- Silvia Novelli
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy
| | - Angelo Gismondi
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy
| | - Gabriele Di Marco
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy
| | - Lorena Canuti
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy
| | - Valentina Nanni
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy
| | - Antonella Canini
- Department of Biology, University of Rome "Tor Vergata", via della Ricerca Scientifica 1, Rome, 00133, Italy.
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Mendes JS, Santiago AS, Toledo MAS, Horta MAC, de Souza AA, Tasic L, de Souza AP. In vitro Determination of Extracellular Proteins from Xylella fastidiosa. Front Microbiol 2016; 7:2090. [PMID: 28082960 PMCID: PMC5183587 DOI: 10.3389/fmicb.2016.02090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 12/09/2016] [Indexed: 12/20/2022] Open
Abstract
The phytopathogen Xylella fastidiosa causes economic losses in important agricultural crops. Xylem vessel occlusion caused by biofilm formation is the major mechanism underlying the pathogenicity of distinct strains of X. fastidiosa. Here, we provide a detailed in vitro characterization of the extracellular proteins of X. fastidiosa. Based on the results, we performed a comparison with a strain J1a12, which cannot induce citrus variegated chlorosis symptoms when inoculated into citrus plants. We then extend this approach to analyze the extracellular proteins of X. fastidiosa in media supplemented with calcium. We verified increases in extracellular proteins concomitant with the days of growth and, consequently, biofilm development (3-30 days). Outer membrane vesicles carrying toxins were identified beginning at 10 days of growth in the 9a5c strain. In addition, a decrease in extracellular proteins in media supplemented with calcium was observed in both strains. Using mass spectrometry, 71 different proteins were identified during 30 days of X. fastidiosa biofilm development, including proteases, quorum-sensing proteins, biofilm formation proteins, hypothetical proteins, phage-related proteins, chaperones, toxins, antitoxins, and extracellular vesicle membrane components.
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Affiliation(s)
- Juliano S. Mendes
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de CampinasCampinas, Brazil
| | - André S. Santiago
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de CampinasCampinas, Brazil
| | - Marcelo A. S. Toledo
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de CampinasCampinas, Brazil
| | - Maria A. C. Horta
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de CampinasCampinas, Brazil
| | | | - Ljubica Tasic
- Departamento de Química Orgânica, Instituto de Química, Universidade Estadual de CampinasCampinas, Brazil
| | - Anete P. de Souza
- Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de CampinasCampinas, Brazil
- Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de CampinasCampinas, Brazil
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Kim YS, Kotnala B, Kim YH, Jeon Y. Biological characteristics of Paenibacillus polymyxa GBR-1 involved in root rot of stored Korean ginseng. J Ginseng Res 2016. [DOI: 10.1016/j.jgr.2015.09.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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5
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Cursino L, Athinuwat D, Patel KR, Galvani CD, Zaini PA, Li Y, De La Fuente L, Hoch HC, Burr TJ, Mowery P. Characterization of the Xylella fastidiosa PD1671 gene encoding degenerate c-di-GMP GGDEF/EAL domains, and its role in the development of Pierce's disease. PLoS One 2015; 10:e0121851. [PMID: 25811864 PMCID: PMC4374697 DOI: 10.1371/journal.pone.0121851] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 02/16/2015] [Indexed: 01/09/2023] Open
Abstract
Xylella fastidiosa is an important phytopathogenic bacterium that causes many serious plant diseases including Pierce's disease of grapevines. X. fastidiosa is thought to induce disease by colonizing and clogging xylem vessels through the formation of cell aggregates and bacterial biofilms. Here we examine the role in X. fastidiosa virulence of an uncharacterized gene, PD1671, annotated as a two-component response regulator with potential GGDEF and EAL domains. GGDEF domains are found in c-di-GMP diguanylate cyclases while EAL domains are found in phosphodiesterases, and these domains are for c-di-GMP production and turnover, respectively. Functional analysis of the PD1671 gene revealed that it affected multiple X. fastidiosa virulence-related phenotypes. A Tn5 PD1671 mutant had a hypervirulent phenotype in grapevines presumably due to enhanced expression of gum genes leading to increased exopolysaccharide levels that resulted in elevated biofilm formation. Interestingly, the PD1671 mutant also had decreased motility in vitro but did not show a reduced distribution in grapevines following inoculation. Given these responses, the putative PD1671 protein may be a negative regulator of X. fastidiosa virulence.
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Affiliation(s)
- Luciana Cursino
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
- Department of Biology, Hobart and William Smith Colleges Geneva, New York, United States of America
| | - Dusit Athinuwat
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Kelly R. Patel
- Department of Biology, Hobart and William Smith Colleges Geneva, New York, United States of America
| | - Cheryl D. Galvani
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
- Department of Biology, Hobart and William Smith Colleges Geneva, New York, United States of America
| | - Paulo A. Zaini
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Yaxin Li
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Leonardo De La Fuente
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Harvey C. Hoch
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Thomas J. Burr
- Department of Plant Pathology and Plant Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, New York, United States of America
| | - Patricia Mowery
- Department of Biology, Hobart and William Smith Colleges Geneva, New York, United States of America
- * E-mail:
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The host plant metabolite glucose is the precursor of diffusible signal factor (DSF) family signals in Xanthomonas campestris. Appl Environ Microbiol 2015; 81:2861-8. [PMID: 25681189 DOI: 10.1128/aem.03813-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Plant pathogen Xanthomonas campestris pv. campestris produces cis-11-methyl-2-dodecenoic acid (diffusible signal factor [DSF]) as a cell-cell communication signal to regulate biofilm dispersal and virulence factor production. Previous studies have demonstrated that DSF biosynthesis is dependent on the presence of RpfF, an enoyl-coenzyme A (CoA) hydratase, but the DSF synthetic mechanism and the influence of the host plant on DSF biosynthesis are still not clear. We show here that exogenous addition of host plant juice or ethanol extract to the growth medium of X. campestris pv. campestris could significantly boost DSF family signal production. It was subsequently revealed that X. campestris pv. campestris produces not only DSF but also BDSF (cis-2-dodecenoic acid) and another novel DSF family signal, which was designated DSF-II. BDSF was originally identified in Burkholderia cenocepacia to be involved in regulation of motility, biofilm formation, and virulence in B. cenocepacia. Functional analysis suggested that DSF-II plays a role equal to that of DSF in regulation of biofilm dispersion and virulence factor production in X. campestris pv. campestris. Furthermore, chromatographic separation led to identification of glucose as a specific molecule stimulating DSF family signal biosynthesis in X. campestris pv. campestris. (13)C-labeling experiments demonstrated that glucose acts as a substrate to provide a carbon element for DSF biosynthesis. The results of this study indicate that X. campestris pv. campestris could utilize a common metabolite of the host plant to enhance DSF family signal synthesis and therefore promote virulence.
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Abstract
UNLABELLED Cell-cell signaling in Xylella fastidiosa has been implicated in the coordination of traits enabling colonization in plant hosts as well as insect vectors. This cell density-dependent signaling has been attributed to a diffusible signaling factor (DSF) produced by the DSF synthase RpfF. DSF produced by related bacterial species are unsaturated fatty acids, but that of X. fastidiosa was thought to be different from those of other taxa. We describe here the isolation and characterization of an X. fastidiosa DSF (XfDSF) as 2(Z)-tetradecenoic acid. This compound was isolated both from recombinant Erwinia herbicola expressing X. fastidiosa rpfF and from an X. fastidiosa rpfC deletion mutant that overproduces DSF. Since an rpfF mutant is impaired in biofilm formation and underexpresses the hemagglutinin-like protein-encoding genes hxfA and hxfB, we demonstrate that these traits can be restored by ca. 0.5 µM XfDSF but not by myristic acid, the fully saturated tetradecenoic acid. A phoA-based X. fastidiosa biosensor that assesses DSF-dependent expression of hxfA or hxfB revealed a high level of molecular specificity of DSF signaling. IMPORTANCE X. fastidiosa causes diseases in many important plants, including grape, where it incites Pierce's disease. Virulence of X. fastidiosa for grape is coordinated by cell-cell signaling molecules, designated DSF (Diffusible Signaling Factor). Mutants blocked in DSF production are hypervirulent for grape, suggesting that virulence is suppressed upon DSF accumulation and that disease could be controlled by artificial elevation of the DSF level in plants. In this work, we describe the isolation of the DSF produced by X. fastidiosa and the verification of its biological activity as an antivirulence factor. We also have developed X. fastidiosa DSF biosensors to evaluate the specificity of cell-cell signaling to be investigated.
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Cruz LF, Cobine PA, De La Fuente L. Calcium increases Xylella fastidiosa surface attachment, biofilm formation, and twitching motility. Appl Environ Microbiol 2012; 78:1321-31. [PMID: 22194297 PMCID: PMC3294462 DOI: 10.1128/aem.06501-11] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 12/12/2011] [Indexed: 01/21/2023] Open
Abstract
Xylella fastidiosa is a plant-pathogenic bacterium that forms biofilms inside xylem vessels, a process thought to be influenced by the chemical composition of xylem sap. In this work, the effect of calcium on the production of X. fastidiosa biofilm and movement was analyzed under in vitro conditions. After a dose-response study with 96-well plates using eight metals, the strongest increase of biofilm formation was observed when medium was supplemented with at least 1.0 mM CaCl(2). The removal of Ca by extracellular (EGTA, 1.5 mM) and intracellular [1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA/AM), 75 μM] chelators reduced biofilm formation without compromising planktonic growth. The concentration of Ca influenced the force of adhesion to the substrate, biofilm thickness, cell-to-cell aggregation, and twitching motility, as shown by assays with microfluidic chambers and other assays. The effect of Ca on attachment was lost when cells were treated with tetracycline, suggesting that Ca has a metabolic or regulatory role in cell adhesion. A double mutant (fimA pilO) lacking type I and type IV pili did not improve biofilm formation or attachment when Ca was added to the medium, while single mutants of type I (fimA) or type IV (pilB) pili formed more biofilm under conditions of higher Ca concentrations. The concentration of Ca in the medium did not significantly influence the levels of exopolysaccharide produced. Our findings indicate that the role of Ca in biofilm formation may be related to the initial surface and cell-to-cell attachment and colonization stages of biofilm establishment, which rely on critical functions by fimbrial structures.
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Affiliation(s)
- Luisa F. Cruz
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
| | - Paul A. Cobine
- Department of Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, USA
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Bandara HMHN, Lam OLT, Jin LJ, Samaranayake L. Microbial chemical signaling: a current perspective. Crit Rev Microbiol 2012; 38:217-49. [PMID: 22300377 DOI: 10.3109/1040841x.2011.652065] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Communication among microorganisms is mediated through quorum sensing. The latter is defined as cell-density linked, coordinated gene expression in microbial populations as a response to threshold signal concentrations followed by induction of a synchronized population response. This phenomenon is used by a variety of microbes to optimize their survival in a constantly challenging, dynamic milieu, by correlating individual cellular functions to community-based requirements. The synthesis, secretion, and perception of quorum-sensing molecules and their target response play a pivotal role in quorum sensing and are tightly controlled by complex, multilayered and interconnected signal transduction pathways that regulate diverse cellular functions. Quorum sensing exemplifies interactive social behavior innate to the microbial world that controls features such as, virulence, biofilm maturation, antibiotic resistance, swarming motility, and conjugal plasmid transfer. Over the past two decades, studies have been performed to rationalize bacterial cell-to-cell communication mediated by structurally and functionally diverse small molecules. This review describes the theoretical aspects of cellular and quorum-sensing mechanisms that affect microbial physiology and pathobiology.
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Affiliation(s)
- H M H N Bandara
- Oral Biosciences, Prince Philip Dental Hospital, 34, Hospital Road, Sai Ying Pun, Hong Kong
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Silva MS, De Souza AA, Takita MA, Labate CA, Machado MA. Analysis of the biofilm proteome of Xylella fastidiosa. Proteome Sci 2011; 9:58. [PMID: 21939513 PMCID: PMC3187737 DOI: 10.1186/1477-5956-9-58] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 09/22/2011] [Indexed: 12/18/2022] Open
Abstract
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. RESULTS We found a total of 456 proteins expressed in the biofilm condition, which correspond to approximately 10% of total protein in the genome. The biofilm showed 37% (or 144 proteins) different protein than we found in the planktonic growth condition. The large difference in protein pattern in the biofilm condition may be responsible for the physiological changes of the cells in the biofilm of X. fastidiosa. Mass spectrometry was used to identify these proteins, while real-time quantitative polymerase chain reaction monitored expression of genes encoding them. Most of proteins expressed in the mature biofilm growth were associated with metabolism, adhesion, pathogenicity and stress conditions. Even though the biofilm cells in this work were not submitted to any stress condition, some stress related proteins were expressed only in the biofilm condition, suggesting that the biofilm cells would constitutively express proteins in different adverse environments. CONCLUSIONS We observed overexpression of proteins related to quorum sensing, proving the existence of communication between cells, and thus the development of structuring the biofilm (mature biofilm) leading to obstruction of vessels and development of disease. This paper reports a first proteomic analysis of mature biofilm of X. fastidiosa, opening new perspectives for understanding the biochemistry of mature biofilm growth in a plant pathogen.
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Affiliation(s)
- Mariana S Silva
- Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
- Centro APTA Citros 'Sylvio Moreira'(CCSM), Cordeirópolis, SP, Brazil
| | | | - Marco A Takita
- Centro APTA Citros 'Sylvio Moreira'(CCSM), Cordeirópolis, SP, Brazil
| | - Carlos A Labate
- Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Escola Superior de Agricultura 'Luiz de Queiroz', Universidade de São Paulo (USP), Piracicaba, SP, Brazil
| | - Marcos A Machado
- Centro APTA Citros 'Sylvio Moreira'(CCSM), Cordeirópolis, SP, Brazil
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Chatelet DS, Wistrom CM, Purcell AH, Rost TL, Matthews MA. Xylem structure of four grape varieties and 12 alternative hosts to the xylem-limited bacterium Xylella fastidious. ANNALS OF BOTANY 2011; 108:73-85. [PMID: 21546428 PMCID: PMC3119617 DOI: 10.1093/aob/mcr106] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 03/21/2011] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS The bacterium Xylella fastidiosa (Xf), responsible for Pierce's disease (PD) of grapevine, colonizes the xylem conduits of vines, ultimately killing the plant. However, Vitis vinifera grapevine varieties differ in their susceptibility to Xf and numerous other plant species tolerate Xf populations without showing symptoms. The aim of this study was to examine the xylem structure of grapevines with different susceptibilities to Xf infection, as well as the xylem structure of non-grape plant species that support or limit movement of Xf to determine if anatomical differences might explain some of the differences in susceptibility to Xf. METHODS Air and paint were introduced into leaves and stems to examine the connectivity between stem and leaves and the length distribution of their vessels. Leaf petiole and stem anatomies were studied to determine the basis for the free or restricted movement of Xf into the plant. KEY RESULTS There were no obvious differences in stem or petiole vascular anatomy among the grape varieties examined, nor among the other plant species that would explain differences in resistance to Xf. Among grape varieties, the more tolerant 'Sylvaner' had smaller stem vessel diameters and 20 % more parenchyma rays than the other three varieties. Alternative hosts supporting Xf movement had slightly longer open xylem conduits within leaves, and more connection between stem and leaves, when compared with alternative hosts that limit Xf movement. CONCLUSIONS Stem--leaf connectivity via open xylem conduits and vessel length is not responsible for differences in PD tolerance among grape varieties, or for limiting bacterial movement in the tolerant plant species. However, it was found that tolerant host plants had narrower vessels and more parenchyma rays, possibly restricting bacterial movement at the level of the vessels. The implications of xylem structure and connectivity for the means and regulation of bacterial movement are discussed.
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Affiliation(s)
- David S. Chatelet
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02906, USA
| | - Christina M. Wistrom
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, USA
| | - Alexander H. Purcell
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, USA
| | - Thomas L. Rost
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Mark A. Matthews
- Department of Viticulture and Enology, University of California, Davis, CA 95616, USA
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Baccari C, Lindow SE. Assessment of the process of movement of Xylella fastidiosa within susceptible and resistant grape cultivars. PHYTOPATHOLOGY 2011; 101:77-84. [PMID: 20822432 DOI: 10.1094/phyto-04-10-0104] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
To better understand the processes contributing to symptoms and resistance to Pierce's disease of grape, we examined the movement and multiplication of a green fluorescent protein-marked strain of Xylella fastidiosa in the stems and petioles of Cabernet Sauvignon, Chenin Blanc, Roucaneuf, and Tampa grape cultivars that differ in their susceptibility to this disease. X. fastidiosa achieved much lower population sizes and colonized fewer xylem vessels in the stem of resistant cultivars compared with more susceptible cultivars. In contrast, X. fastidiosa achieved similarly high population sizes and colonized a similar proportion of the vessels in petioles of susceptible and resistant cultivars, suggesting that, compared with the stem, X. fastidiosa is relatively unrestricted in its movement and growth within the petiole. There was not a direct relationship between the population size of X. fastidiosa in the stem and the proportion of vessels colonized; a much higher population size of the pathogen was observed in susceptible cultivars than expected based on the proportion of vessels colonized. The high population sizes of X. fastidiosa in stems of susceptible genotypes were associated with both a high number of infected vessels and a much higher extent of colonization of those vessels that become infested than in more resistant cultivars. The formation of large cellular aggregates in vessels is not required for X. fastidiosa to move laterally in the stem to adjacent vessels because most vessels harbored only small assemblages, especially in resistant cultivars such as Roucaneuf, in which some intervessel movement was detected. Resistance to Pierce's disease is apparently not due to inhibitory compounds that circulate in the xylem because they might be expected to operate similarly in all tissues.
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Affiliation(s)
- C Baccari
- Department of Plant and Microbial Biology, University of California, Berkeley, USA
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13
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Deng Y, Wu J, Tao F, Zhang LH. Listening to a new language: DSF-based quorum sensing in Gram-negative bacteria. Chem Rev 2010; 111:160-73. [PMID: 21166386 DOI: 10.1021/cr100354f] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yinyue Deng
- Institute of Molecular and Cell Biology, Proteos, 61 Biopolis Drive, Singapore 138673
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14
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Jeon Y, Kim S, Hwang I, Kim Y. Effects of initial inoculation density of
Paenibacillus polymyxa
on colony formation and starch‐hydrolytic activity in relation to root rot in ginseng. J Appl Microbiol 2010; 109:461-470. [DOI: 10.1111/j.1365-2672.2010.04674.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Y.H. Jeon
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
- KT&G Central Research Institute, Daejeon, Korea
| | - S.G. Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
| | - I. Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
| | - Y.H. Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Korea
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Gong Z, Zhu J, Yu G, Zou H. Disruption of nifA gene influences multiple cellular processes in Sinorhizobium meliloti. J Genet Genomics 2009; 34:783-9. [PMID: 17884688 DOI: 10.1016/s1673-8527(07)60089-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 05/10/2007] [Indexed: 11/21/2022]
Abstract
Sinorhizobium meliloti nifA is important in fixing nitrogen during symbiosis. A nifA null mutant induces small white invalid nodules in the roots of host plant. The additional phenotypic alterations associated with the disruption of the nifA gene are reported in this study. Under a free-living state, S. meliloti nifA mutant reduces its ability to swarm on a half-solid plate. Interestingly, the AHL (Acylhomoserine lactones) contents in the nifA mutant are lower than that of the wild type during the lag phase, whereas it is reversed in the logarithmic and stationary phases. Quantitative spectrophotometric assays reveal that the total amount of extracellular proteins of the nifA mutant are lower than that of the wild type. In addition, the mutant abolishes its nodulation competitive ability during symbiosis. These findings indicate that NifA plays a regulatory role in multiple cellular processes in S. meliloti.
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Affiliation(s)
- Ziying Gong
- National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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16
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Shi XY, Dumenyo CK, Hernandez-Martinez R, Azad H, Cooksey DA. Characterization of regulatory pathways in Xylella fastidiosa: genes and phenotypes controlled by gacA. Appl Environ Microbiol 2009; 75:2275-83. [PMID: 19218414 PMCID: PMC2675201 DOI: 10.1128/aem.01964-08] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2008] [Accepted: 02/03/2009] [Indexed: 11/20/2022] Open
Abstract
The xylem-limited, insect-transmitted bacterium Xylella fastidiosa causes Pierce's disease in grapes through cell aggregation and vascular clogging. GacA controls various physiological processes and pathogenicity factors in many gram-negative bacteria, including biofilm formation in Pseudomonas syringae pv. tomato DC3000. Cloned gacA of X. fastidiosa was found to restore the hypersensitive response and pathogenicity in gacA mutants of P. syringae pv. tomato DC3000 and Erwinia amylovora. A gacA mutant of X. fastidiosa (DAC1984) had significantly reduced abilities to adhere to a glass surface, form biofilm, and incite disease symptoms on grapevines, compared with the parent (A05). cDNA microarray analysis identified 7 genes that were positively regulated by GacA, including xadA and hsf, predicted to encode outer membrane adhesion proteins, and 20 negatively regulated genes, including gumC and an antibacterial polypeptide toxin gene, cvaC. These results suggest that GacA of X. fastidiosa regulates many factors, which contribute to attachment and biofilm formation, as well as some physiological processes that may enhance the adaptation and tolerance of X. fastidiosa to environmental stresses and the competition within the host xylem.
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Affiliation(s)
- Xiang Yang Shi
- Department of Plant Pathology and Microbiology, University of California, Riverside, California 92521, USA
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17
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Lu H, Patil P, Van Sluys MA, White FF, Ryan RP, Dow JM, Rabinowicz P, Salzberg SL, Leach JE, Sonti R, Brendel V, Bogdanove AJ. Acquisition and evolution of plant pathogenesis-associated gene clusters and candidate determinants of tissue-specificity in xanthomonas. PLoS One 2008; 3:e3828. [PMID: 19043590 PMCID: PMC2585010 DOI: 10.1371/journal.pone.0003828] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Accepted: 11/03/2008] [Indexed: 01/30/2023] Open
Abstract
Background Xanthomonas is a large genus of plant-associated and plant-pathogenic bacteria. Collectively, members cause diseases on over 392 plant species. Individually, they exhibit marked host- and tissue-specificity. The determinants of this specificity are unknown. Methodology/Principal Findings To assess potential contributions to host- and tissue-specificity, pathogenesis-associated gene clusters were compared across genomes of eight Xanthomonas strains representing vascular or non-vascular pathogens of rice, brassicas, pepper and tomato, and citrus. The gum cluster for extracellular polysaccharide is conserved except for gumN and sequences downstream. The xcs and xps clusters for type II secretion are conserved, except in the rice pathogens, in which xcs is missing. In the otherwise conserved hrp cluster, sequences flanking the core genes for type III secretion vary with respect to insertion sequence element and putative effector gene content. Variation at the rpf (regulation of pathogenicity factors) cluster is more pronounced, though genes with established functional relevance are conserved. A cluster for synthesis of lipopolysaccharide varies highly, suggesting multiple horizontal gene transfers and reassortments, but this variation does not correlate with host- or tissue-specificity. Phylogenetic trees based on amino acid alignments of gum, xps, xcs, hrp, and rpf cluster products generally reflect strain phylogeny. However, amino acid residues at four positions correlate with tissue specificity, revealing hpaA and xpsD as candidate determinants. Examination of genome sequences of xanthomonads Xylella fastidiosa and Stenotrophomonas maltophilia revealed that the hrp, gum, and xcs clusters are recent acquisitions in the Xanthomonas lineage. Conclusions/Significance Our results provide insight into the ancestral Xanthomonas genome and indicate that differentiation with respect to host- and tissue-specificity involved not major modifications or wholesale exchange of clusters, but subtle changes in a small number of genes or in non-coding sequences, and/or differences outside the clusters, potentially among regulatory targets or secretory substrates.
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Affiliation(s)
- Hong Lu
- Department of Genetics Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
| | - Prabhu Patil
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
| | - Marie-Anne Van Sluys
- Departamento de Botânica, IB-USP, Sao Paulo, Sao Paulo, Brazil
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado, United States of America
| | - Frank F. White
- Department of Plant Pathology, Kansas State University, Manhattan, Kansas, United States of America
| | - Robert P. Ryan
- BIOMERIT Research Centre, BioSciences Institute, University College Cork, Cork, Ireland
| | - J. Maxwell Dow
- BIOMERIT Research Centre, BioSciences Institute, University College Cork, Cork, Ireland
| | - Pablo Rabinowicz
- The Institute for Genomic Research, Rockville, Maryland, United States of America
| | - Steven L. Salzberg
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - Jan E. Leach
- Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ramesh Sonti
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
| | - Volker Brendel
- Department of Genetics Development and Cell Biology, Iowa State University, Ames, Iowa, United States of America
- Department of Statistics, Iowa State University, Ames, Iowa, United States of America
| | - Adam J. Bogdanove
- Department of Plant Pathology, Iowa State University, Ames, Iowa, United States of America
- * E-mail:
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Abstract
It is now clear that cell-cell communication, often referred to as quorum sensing (QS), is the norm in the prokaryotic kingdom and this community-wide genetic regulatory mechanism has been adopted for regulation of many important biological functions. Since the 1980s, several types of QS signals have been identified, which are associated commonly with different types of QS mechanisms. Among them, the diffusible signal factor (DSF)-dependent QS system, originally discovered from bacterial pathogen Xanthomonas campestris pv. campestris, is a relatively new regulatory mechanism. The rapid research progress over the last few years has identified the chemical structure of the QS signal DSF, established the DSF regulon, and unveiled the general signaling pathways and mechanisms. Particular noteworthy are that DSF biosynthesis is modulated by a novel posttranslational autoinduction mechanism involving protein-protein interaction between the DSF synthase RpfF and the sensor RpfC, and that QS signal sensing is coupled to intracellular regulatory networks through a second messenger cyclic-di-GMP and a global regulator Clp. Genomic and genetic analyses show that the DSF QS-signaling pathway regulates diverse biological functions including virulence, biofilm dispersal, and ecological competence. Moreover, evidence is emerging that the DSF QS system is conserved in a range of plant and human bacterial pathogens.
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Affiliation(s)
- Ya-Wen He
- Institute of Molecular and Cell Biology, Singapore, Singapore
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19
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Influence of Culture Medium pH on Growth, Aggregation, and Biofilm Formation of Xylella fastidiosa. Curr Microbiol 2008; 57:127-32. [DOI: 10.1007/s00284-008-9164-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Accepted: 02/21/2008] [Indexed: 10/22/2022]
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20
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The complete genome, comparative and functional analysis of Stenotrophomonas maltophilia reveals an organism heavily shielded by drug resistance determinants. Genome Biol 2008; 9:R74. [PMID: 18419807 PMCID: PMC2643945 DOI: 10.1186/gb-2008-9-4-r74] [Citation(s) in RCA: 376] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 03/13/2008] [Accepted: 04/17/2008] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Stenotrophomonas maltophilia is a nosocomial opportunistic pathogen of the Xanthomonadaceae. The organism has been isolated from both clinical and soil environments in addition to the sputum of cystic fibrosis patients and the immunocompromised. Whilst relatively distant phylogenetically, the closest sequenced relatives of S. maltophilia are the plant pathogenic xanthomonads. RESULTS The genome of the bacteremia-associated isolate S. maltophilia K279a is 4,851,126 bp and of high G+C content. The sequence reveals an organism with a remarkable capacity for drug and heavy metal resistance. In addition to a number of genes conferring resistance to antimicrobial drugs of different classes via alternative mechanisms, nine resistance-nodulation-division (RND)-type putative antimicrobial efflux systems are present. Functional genomic analysis confirms a role in drug resistance for several of the novel RND efflux pumps. S. maltophilia possesses potentially mobile regions of DNA and encodes a number of pili and fimbriae likely to be involved in adhesion and biofilm formation that may also contribute to increased antimicrobial drug resistance. CONCLUSION The panoply of antimicrobial drug resistance genes and mobile genetic elements found suggests that the organism can act as a reservoir of antimicrobial drug resistance determinants in a clinical environment, which is an issue of considerable concern.
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Newman KL, Chatterjee S, Ho KA, Lindow SE. Virulence of plant pathogenic bacteria attenuated by degradation of fatty acid cell-to-cell signaling factors. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:326-334. [PMID: 18257682 DOI: 10.1094/mpmi-21-3-0326] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Diffusible signal factor (DSF) is a fatty acid signal molecule involved in regulation of virulence in several Xanthomonas species as well as Xylella fastidiosa. In this study, we identified a variety of bacteria that could disrupt DSF-mediated induction of virulence factors in Xanthomonas campestris pv. campestris. While many bacteria had the ability to degrade DSF, several bacterial strains belonging to genera Bacillus, Paenibacillus, Microbacterium, Staphylococcus, and Pseudomonas were identified that were capable of particularly rapid degradation of DSF. The molecular determinants for rapid degradation of DSF in Pseudomonas spp. strain G were elucidated. Random transposon mutants of strain G lacking the ability to degrade DSF were isolated. Cloning and characterization of disrupted genes in these strains revealed that carAB, required for the synthesis of carbamoylphosphate, a precursor for pyrimidine and arginine biosynthesis is required for rapid degradation of DSF in strain G. Complementation of carAB mutants restored both pyrimidine prototrophy and DSF degradation ability of the strain G mutant. An Escherichia coli strain harboring carAB of Pseudomonas spp. strain G degrades DSF more rapidly than the parental strain, and overexpression of carAB in trans increased the ability of Pseudomonas spp. strain G to degrade as compared with the parental strain. Coinoculation of X. campestris pv. campestris with DSF-degrading bacteria into mustard and cabbage leaves reduced disease severity up to twofold compared with plants inoculated only with the pathogen. Likewise, disease incidence and severity in grape stems coinoculated with Xylella fastidiosa and DSF-degrading strains were significantly reduced compared with plants inoculated with the pathogen alone. Coinoculation of grape plants with a carAB mutant of Pseudomonas spp. strain G complemented with carAB in trans reduced disease severity as well or better than the parental strain. These results indicate that overexpression of carAB in other endophytes could be a useful strategy of biocontrol for the control of diseases caused by plant pathogens that produce DSF.
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Affiliation(s)
- Karyn L Newman
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA
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22
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The iron stimulon of Xylella fastidiosa includes genes for type IV pilus and colicin V-like bacteriocins. J Bacteriol 2008; 190:2368-78. [PMID: 18223091 DOI: 10.1128/jb.01495-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Xylella fastidiosa is the etiologic agent of a wide range of plant diseases, including citrus variegated chlorosis (CVC), a major threat to citrus industry. The genomes of several strains of this phytopathogen were completely sequenced, enabling large-scale functional studies. DNA microarrays representing 2,608 (91.6%) coding sequences (CDS) of X. fastidiosa CVC strain 9a5c were used to investigate transcript levels during growth with different iron availabilities. When treated with the iron chelator 2,2'-dipyridyl, 193 CDS were considered up-regulated and 216 were considered down-regulated. Upon incubation with 100 microM ferric pyrophosphate, 218 and 256 CDS were considered up- and down-regulated, respectively. Differential expression for a subset of 44 CDS was further evaluated by reverse transcription-quantitative PCR. Several CDS involved with regulatory functions, pathogenicity, and cell structure were modulated under both conditions assayed, suggesting that major changes in cell architecture and metabolism occur when X. fastidiosa cells are exposed to extreme variations in iron concentration. Interestingly, the modulated CDS include those related to colicin V-like bacteriocin synthesis and secretion and to functions of pili/fimbriae. We also investigated the contribution of the ferric uptake regulator Fur to the iron stimulon of X. fastidiosa. The promoter regions of the strain 9a5c genome were screened for putative Fur boxes, and candidates were analyzed by electrophoretic mobility shift assays. Taken together, our data support the hypothesis that Fur is not solely responsible for the modulation of the iron stimulon of X. fastidiosa, and they present novel evidence for iron regulation of pathogenicity determinants.
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23
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Roper MC, Greve LC, Labavitch JM, Kirkpatrick BC. Detection and visualization of an exopolysaccharide produced by Xylella fastidiosa in vitro and in planta. Appl Environ Microbiol 2007; 73:7252-8. [PMID: 17827325 PMCID: PMC2168192 DOI: 10.1128/aem.00895-07] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 08/29/2007] [Indexed: 11/20/2022] Open
Abstract
Many phytopathogenic bacteria, such as Ralstonia solanacearum, Pantoea stewartii, and Xanthomonas campestris, produce exopolysaccharides (EPSs) that aid in virulence, colonization, and survival. EPS can also contribute to host xylem vessel blockage. The genome of Xylella fastidiosa, the causal agent of Pierce's disease (PD) of grapevine, contains an operon that is strikingly similar to the X. campestris gum operon, which is responsible for the production of xanthan gum. Based on this information, it has been hypothesized that X. fastidiosa is capable of producing an EPS similar in structure and composition to xanthan gum but lacking the terminal mannose residue. In this study, we raised polyclonal antibodies against a modified xanthan gum polymer similar to the predicted X. fastidiosa EPS polymer. We used enzyme-linked immunosorbent assay to quantify production of EPS from X. fastidiosa cells grown in vitro and immunolocalization microscopy to examine the distribution of X. fastidiosa EPS in biofilms formed in vitro and in planta and assessed the contribution of X. fastidiosa EPS to the vascular occlusions seen in PD-infected grapevines.
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Affiliation(s)
- M Caroline Roper
- Department of Plant Pathology, University of California, Davis, Davis, CA 95616, USA
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24
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Colnaghi Simionato AV, da Silva DS, Lambais MR, Carrilho E. Characterization of a putative Xylella fastidiosa diffusible signal factor by HRGC-EI-MS. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:1375-81. [PMID: 17902112 DOI: 10.1002/jms.1325] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Xylella fastidiosa (X.f.) is a plant pathogen with high levels of genomic similarity to Xanthomonas campestris pv. campestris (X.c.c.). It has been shown that X. fastidiosa synthesizes a putative diffusible signal factor (X.f.-DSF) that activates regulation of pathogenicity factor (rpf) genes in a X.c.c. reporter system, which might be involved in the regulation of pathogenesis associated genes as in X.c.c., as well as in quorum-sensing. The nature of the X.f.-DSF is not known, whereas the X.c.c.-DSF has been identified as cis-11-methyl-2-dodecenoic acid. In this work, the chemical nature of a putative X.f.-DSF molecule, able to restore endoglucanase activity in a X.c.c. rpfF mutant, was investigated as if it was a fatty acid derivative. Bioassays with X.c.c. reporter bacterium and X.f. culture extracts, based on endoglucanase restoration activity, were also carried out in order to confirm the DSFs molecules similarities. For this reason, a gas chromatography-mass spectrometry method was developed with standard fatty acids methyl esters mixtures. The retention time, as well as the fragmentation patterns, of each standard was used to identify the DSF molecule synthesized by X.f. in the culture medium. Typical ester fragmentation patterns (the derivatized analyte) were observed, such as: McLafferty rearrangement and migration of the Hdelta followed by 1,4-hydrogen shift and cleavage of the bond Cbeta--Cgamma, confirming the nature of this molecule. This confirmation was corroborated by the common peaks in both spectra. Besides, the observed retention time reinforces our conclusion since it corresponds to a methyl ester with 15 carbons. Since the X.f.-DSF molecule was tentatively identified as 12-methyl-tetradecanoic acid (by mass spectra library comparison), this standard compound was also analyzed, strongly suggesting that this is the identification of such a molecule. To our knowledge, this is the first time a DSF produced by X.f. has been characterized.
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Affiliation(s)
- Ana Valéria Colnaghi Simionato
- Laboratório de Cromatografia, Instituto de Química de São Carlos, Universidade de São Paulo, Av. Trabalhador Sãocarlense, 400 São Carlos, SP, Brasil
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25
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Fouhy Y, Scanlon K, Schouest K, Spillane C, Crossman L, Avison MB, Ryan RP, Dow JM. Diffusible signal factor-dependent cell-cell signaling and virulence in the nosocomial pathogen Stenotrophomonas maltophilia. J Bacteriol 2007; 189:4964-8. [PMID: 17468254 PMCID: PMC1913462 DOI: 10.1128/jb.00310-07] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The genome of Stenotrophomonas maltophilia encodes a cell-cell signaling system that is highly related to the diffusible signal factor (DSF)-dependent system of the phytopathogen Xanthomonas campestris. Here we show that in S. maltophilia, DSF signaling controls factors contributing to the virulence and antibiotic resistance of this important nosocomial pathogen.
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Affiliation(s)
- Yvonne Fouhy
- BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, National University of Ireland, Cork, Ireland
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26
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Colnaghi Simionato AV, da Silva DS, Lambais MR, Carrilho E. Characterization of a putative Xylella fastidiosa diffusible signal factor by HRGC-EI-MS. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:490-6. [PMID: 17295415 DOI: 10.1002/jms.1181] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Xylella fastidiosa (X.f.) is a plant pathogen with high levels of genomic similarity to Xanthomonas campestris pv. campestris (X.c.c.). It has been shown that X. fastidiosa synthesizes a putative diffusible signal factor (X.f.-DSF) that activates regulation of pathogenicity factor (rpf) genes in a X.c.c. reporter system, which might be involved in the regulation of pathogenesis associated genes as in X.c.c., as well as in quorum-sensing. The nature of the X.f.-DSF is not known, whereas the X.c.c.-DSF has been identified as cis-11-methyl-2-dodecenoic acid. In this work, the chemical nature of a putative X.f.-DSF molecule, able to restore endoglucanase activity in a X.c.c. rpfF mutant, was investigated as if it was a fatty acid derivative. Bioassays with X.c.c. reporter bacterium and X.f. culture extracts, based on endoglucanase restoration activity, were also carried out in order to confirm the DSFs molecules similarities. For this reason, a gas chromatography-mass spectrometry method was developed with standard fatty acids methyl esters mixtures. The retention time, as well as the fragmentation patterns, of each standard was used to identify the DSF molecule synthesized by X.f. in the culture medium. Typical ester fragmentation patterns (the derivatized analyte) were observed, such as: McLafferty rearrangement and migration of the Hdelta followed by 1,4-hydrogen shift and cleavage of the bond Cbeta-Cgamma, confirming the nature of this molecule. This confirmation was corroborated by the common peaks in both spectra. Besides, the observed retention time reinforces our conclusion since it corresponds to a methyl ester with 15 carbons. Since the X.f.-DSF molecule was tentatively identified as 12-methyl-tetradecanoic acid (by mass spectra library comparison), this standard compound was also analyzed, strongly suggesting that this is the identification of such a molecule. To our knowledge, this is the first time a DSF produced by X.f. has been characterized.
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Affiliation(s)
- Ana Valéria Colnaghi Simionato
- Laboratório de Cromatografia, Instituto de Química de São Carlos, Universidade de São Paulo, Av. Trabalhador Sãocarlense, 400 São Carlos, SP, Brasil
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27
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Pérez-Donoso AG, Greve LC, Walton JH, Shackel KA, Labavitch JM. Xylella fastidiosa infection and ethylene exposure result in xylem and water movement disruption in grapevine shoots. PLANT PHYSIOLOGY 2007; 143:1024-36. [PMID: 17189331 PMCID: PMC1803717 DOI: 10.1104/pp.106.087023] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 12/01/2006] [Indexed: 05/13/2023]
Abstract
It is conventionally thought that multiplication of the xylem-limited bacterium Xylella fastidiosa (Xf) within xylem vessels is the sole factor responsible for the blockage of water movement in grapevines (Vitis vinifera) affected by Pierce's disease. However, results from our studies have provided substantial support for the idea that vessel obstructions, and likely other aspects of the Pierce's disease syndrome, result from the grapevine's active responses to the presence of Xf, rather than to the direct action of the bacterium. The use of magnetic resonance imaging (MRI) to observe the distribution of water within the xylem has allowed us to follow nondestructively the development of vascular system obstructions subsequent to inoculation of grapevines with Xf. Because we have hypothesized a role for ethylene produced in vines following infection, the impact of vine ethylene exposure on obstruction development was also followed using MRI. In both infected and ethylene-exposed plants, MRI shows that an important proportion of the xylem vessels become progressively air embolized after the treatments. The loss of xylem water-transporting function, assessed by MRI, has been also correlated with a decrease in stem-specific hydraulic conductivity (K(S)) and the presence of tyloses in the lumens of obstructed water conduits. We have observed that the ethylene production of leaves from infected grapevines is greater than that from healthy vines and, therefore, propose that ethylene may be involved in a series of cellular events that coordinates the vine's response to the pathogen.
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Affiliation(s)
- Alonso G Pérez-Donoso
- Department of Plant Sciences, University of California, Davis, California 95616, USA
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28
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Dow JM, Fouhy Y, Lucey JF, Ryan RP. The HD-GYP domain, cyclic di-GMP signaling, and bacterial virulence to plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2006; 19:1378-84. [PMID: 17153922 DOI: 10.1094/mpmi-19-1378] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Cyclic di-GMP is an almost ubiquitous second messenger in bacteria that was first described as an allosteric activator of cellulose synthase but is now known to regulate a range of functions, including virulence in human and animal pathogens. Two protein domains, GGDEF and EAL, are implicated in the synthesis and degradation, respectively, of cyclic di-GMP. These domains are widely distributed in bacteria, including plant pathogens. The majority of proteins with GGDEF and EAL domains contain additional signal input domains, suggesting that their activities are responsive to environmental cues. Recent studies have demonstrated that a third domain, HD-GYP, is also active in cyclic di-GMP degradation. In the plant pathogen Xanthomonas campestris pv. campestris, a two-component signal transduction system comprising the HD-GYP domain regulatory protein RpfG and cognate sensor RpfC positively controls virulence. The signals recognized by RpfC may include the cell-cell signal DSF, which also acts to regulate virulence in X. campestris pv. campestris. Here, we review these recent advances in our understanding of cyclic di-GMP signaling with particular reference to one or more roles in the bacterial pathogenesis of plants.
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Affiliation(s)
- J Maxwell Dow
- BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, National University of Ireland, Cork, Ireland.
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29
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Fouhy Y, Lucey JF, Ryan RP, Dow JM. Cell-cell signaling, cyclic di-GMP turnover and regulation of virulence in Xanthomonas campestris. Res Microbiol 2006; 157:899-904. [PMID: 17008065 DOI: 10.1016/j.resmic.2006.08.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Revised: 08/17/2006] [Accepted: 08/21/2006] [Indexed: 01/23/2023]
Abstract
The synthesis of virulence factors in the plant pathogen Xanthomonas campestris pathovar campestris is regulated by cell-cell signaling mediated by a diffusible signal factor (DSF), and by the RpfC/RpfG two-component regulatory system. Recent findings have indicated that the perception of the DSF signal requires the RpfC sensor and is linked to the degradation of the intracellular second messenger cyclic di-GMP by the HD-GYP domain regulator RpfG.
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Affiliation(s)
- Yvonne Fouhy
- BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, National University of Ireland, Cork, Ireland
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30
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Maria Fedatto L, Silva-Stenico ME, Etchegaray A, Pacheco FTH, Rodrigues JLM, Tsai SM. Detection and characterization of protease secreted by the plant pathogen Xylella fastidiosa. Microbiol Res 2006; 161:263-72. [PMID: 16765843 DOI: 10.1016/j.micres.2005.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2005] [Indexed: 11/26/2022]
Abstract
Xylella fastidiosa is a pathogenic bacterium found in several plants. These bacteria secrete extracellular proteases into the culture broth as visualized in sodium-dodecyl-sulfate polyacrylamide activity gels containing gelatin as a copolymerized substrate. Three major protein bands were produced by the citrus strain with molar masses (MM) of 122, 84 and 65 kDa. Grape strain 9,713 produced two bands of approximately 84 and 64 kDa. These organisms produced zones of hydrolysis in agar plates amended with gelatin, casein and hemoglobin. Gelatin was the best substrate for these proteases. Sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE) activity gel indicated that the protease of Xylella fastidiosa from citrus and grape were completely inhibited by PMSF and partially inhibited by EDTA. The optimal temperature for protease activity was 30 degrees C with an optimal pH of 7.0. Among the proteolytic enzymes secreted by the phytopathogen, chitinase and beta-1,3-glucanase activities were also detected in cultures of Xylella fastidiosa (citrus). From these results, it is suggested that proteases produced by strains of Xylella fastidiosa from citrus and grape, belong to the serine- and metallo-protease group, respectively.
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Affiliation(s)
- Luciana Maria Fedatto
- Laboratório de Biologia Celular e Molecular, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo-CP 96, 13400-970 Piracicaba, SP, Brazil
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Pashalidis S, Moreira LM, Zaini PA, Campanharo JC, Alves LMC, Ciapina LP, Vêncio RZN, Lemos EGM, Da Silva AM, Da Silva ACR. Whole-genome expression profiling of Xylella fastidiosa in response to growth on glucose. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2005; 9:77-90. [PMID: 15805779 DOI: 10.1089/omi.2005.9.77] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Xylella fastidiosa is the etiologic agent of diseases in a wide range of economically important crops including citrus variegated chlorosis, a major threat to the Brazilian citrus industry. The genomes of several strains of this phytopathogen have been completely sequenced enabling large-scale functional studies. In this work we used whole-genome DNA microarrays to investigate the transcription profile of X. fastidiosa grown in defined media with different glucose concentrations. Our analysis revealed that while transcripts related to fastidian gum production were unaffected, colicin-V-like and fimbria precursors were induced in high glucose medium. Based on these results, we suggest a model for colicin-defense mechanism in X. fastidiosa.
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Affiliation(s)
- Stefano Pashalidis
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
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Moreira LM, De Souza RF, Digiampietri LA, Da Silva ACR, Setubal JC. Comparative analyses of Xanthomonas and Xylella complete genomes. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2005; 9:43-76. [PMID: 15805778 DOI: 10.1089/omi.2005.9.43] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Computational analyses of four bacterial genomes of the Xanthomonadaceae family reveal new unique genes that may be involved in adaptation, pathogenicity, and host specificity. The Xanthomonas genus presents 3636 unique genes distributed in 1470 families, while Xylella genus presents 1026 unique genes distributed in 375 families. Among Xanthomonas-specific genes, we highlight a large number of cell wall degrading enzymes, proteases, and iron receptors, a set of energy metabolism genes, second copy of the type II secretion system, type III secretion system, flagella and chemotactic machinery, and the xanthomonadin synthesis gene cluster. Important genes unique to the Xylella genus are an additional copy of a type IV pili gene cluster and the complete machinery of colicin V synthesis and secretion. Intersections of gene sets from both genera reveal a cluster of genes homologous to Salmonella's SPI-7 island in Xanthomonas axonopodis pv citri and Xylella fastidiosa 9a5c, which might be involved in host specificity. Each genome also presents important unique genes, such as an HMS cluster, the kdgT gene, and O-antigen in Xanthomonas axonopodis pv citri; a number of avrBS genes and a distinct O-antigen in Xanthomonas campestris pv campestris, a type I restriction-modification system and a nickase gene in Xylella fastidiosa 9a5c, and a type II restriction-modification system and two genes related to peptidoglycan biosynthesis in Xylella fastidiosa temecula 1. All these differences imply a considerable number of gene gains and losses during the divergence of the four lineages, and are associated with structural genome modifications that may have a direct relation with the mode of transmission, adaptation to specific environments and pathogenicity of each organism.
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Affiliation(s)
- Leandro M Moreira
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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33
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Catani CF, Azzoni AR, Paula DP, Tada SFS, Rosselli LK, de Souza AP, Yano T. Cloning, expression, and purification of the virulence-associated protein D from Xylella fastidiosa. Protein Expr Purif 2005; 37:320-6. [PMID: 15358353 DOI: 10.1016/j.pep.2004.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2004] [Revised: 06/30/2004] [Indexed: 11/16/2022]
Abstract
In this study, an efficient expression system, based on the pET32Xa/LIC vector, for producing a Xylella fastidiosa virulence-associated protein D, found to have a strong similarity to Riemerella anatipestifer and Actinobacillus actinomycetencomitans VapD protein, is presented. The protein has a molecular mass of 17.637 Da and a calculated pI of 5.49. The selected XFa0052 gene was cloned in the pET32Xa/LIC vector and the plasmid was transformed into Escherichia coli BL21 (DE3) strain at 37 degrees C, with an induction time of 2 h and 1 mM IPTG concentration. The protein present in the soluble fraction was purified by immobilized metal affinity chromatography (IMAC), and had its identity determined by mass spectrometry (MALDI-TOF) and N-terminal sequencing. The purified protein was found as a single band on SDS-PAGE and its correct folding was verified by circular dichroism spectroscopy.
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Affiliation(s)
- Cleide Ferreira Catani
- Department of Microbiology and Immunology, Institute of Biology, The State University of Campinas, CP 6010, Campinas, SP, Brazil.
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Reimmann C, Valverde C, Kay E, Haas D. Posttranscriptional repression of GacS/GacA-controlled genes by the RNA-binding protein RsmE acting together with RsmA in the biocontrol strain Pseudomonas fluorescens CHA0. J Bacteriol 2005; 187:276-85. [PMID: 15601712 PMCID: PMC538806 DOI: 10.1128/jb.187.1.276-285.2005] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 09/29/2004] [Indexed: 11/20/2022] Open
Abstract
In the plant-beneficial soil bacterium Pseudomonas fluorescens CHA0, the production of biocontrol factors (antifungal secondary metabolites and exoenzymes) is controlled at a posttranscriptional level by the GacS/GacA signal transduction pathway involving RNA-binding protein RsmA as a key regulatory element. This protein is assumed to bind to the ribosome-binding site of target mRNAs and to block their translation. RsmA-mediated repression is relieved at the end of exponential growth by two GacS/GacA-controlled regulatory RNAs RsmY and RsmZ, which bind and sequester the RsmA protein. A gene (rsmE) encoding a 64-amino-acid RsmA homolog was identified and characterized in strain CHA0. Overexpression of rsmE strongly reduced the expression of target genes (hcnA, for a hydrogen cyanide synthase subunit; aprA, for the main exoprotease; and phlA, for a component of 2,4-diacetylphloroglucinol biosynthesis). Single null mutations in either rsmA or rsmE resulted in a slight increase in the expression of hcnA, aprA, and phlA. By contrast, an rsmA rsmE double mutation led to strongly increased and advanced expression of these target genes and completely suppressed a gacS mutation. Both the RsmE and RsmA levels increased with increasing cell population densities in strain CHA0; however, the amount of RsmA showed less variability during growth. Expression of rsmE was controlled positively by GacA and negatively by RsmA and RsmE. Mobility shift assays demonstrated specific binding of RsmE to RsmY and RsmZ RNAs. The transcription and stability of both regulatory RNAs were strongly reduced in the rsmA rsmE double mutant. In conclusion, RsmA and RsmE together account for maximal repression in the GacS/GacA cascade of strain CHA0.
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Affiliation(s)
- Cornelia Reimmann
- Département de Microbiologie Fondamentale, Bâtiment de Biologie, Université de Lausanne, CH-1015 Lausanne Dorigny, Switzerland.
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Souza AA, Takita MA, Coletta-Filho HD, Caldana C, Yanai GM, Muto NH, Oliveira RC, Nunes LR, Machado MA. Gene expression profile of the plant pathogen Xylella fastidiosa during biofilm formation in vitro. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09716.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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36
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Osiro D, Colnago LA, Otoboni AMMB, Lemos EGM, Souza AA, Filho HDC, Machado MA. A kinetic model for Xylella fastidiosa adhesion, biofilm formation, and virulence. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09663.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Pühler A, Arlat M, Becker A, Göttfert M, Morrissey JP, O'Gara F. What can bacterial genome research teach us about bacteria-plant interactions? CURRENT OPINION IN PLANT BIOLOGY 2004; 7:137-147. [PMID: 15003213 DOI: 10.1016/j.pbi.2004.01.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Biological research is changing dramatically. Genomic and post-genomic research is responsible for the accumulation of enormous datasets, which allow the formation of holistic views of the organisms under investigation. In the field of microbiology, bacteria represent ideal candidates for this new development. It is relatively easy to sequence the genomes of bacteria, to analyse their transcriptomes and to collect information at the proteomic level. Genome research on symbiotic, pathogenic and associative bacteria is providing important information on bacteria-plant interactions, especially on type-III secretion systems (TTSS) and their role in the interaction of bacteria with plants.
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Affiliation(s)
- Alfred Pühler
- Lehrstuhl für Genetik, Universität Bielefeld, 33594 Bielefeld, Germany.
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Muniz JRC, Alves CA, de Pieri C, Beltramini LM, Selistre-de-Araújo HS, Vettore AL, da Silva FR, Arruda P, Garratt RC, Oliva G, Souza DHF. Overexpression, purification, biochemical characterization, and molecular modeling of recombinant GDP-mannosyltransferase (GumH) from Xylella fastidiosa. Biochem Biophys Res Commun 2004; 315:485-92. [PMID: 14766234 DOI: 10.1016/j.bbrc.2004.01.077] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2004] [Indexed: 11/25/2022]
Abstract
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 yield was very low. The gumH gene was then subcloned in the pET28a vector allowing the expression of the GumH enzyme in fusion with a histidine-rich peptide. The protein was purified and characterized. The three-dimensional structure of the X. fastidiosa GumH enzyme was modeled by threading studies. The model consists of N- and C-terminal domains similar in size and topology and separated by a deep cleft, which includes the EX(7)E motif that can be involved in the catalysis of GumH.
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Affiliation(s)
- João Renato C Muniz
- Departamento de Física e Informática, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, SP, Brazil
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Newman KL, Almeida RPP, Purcell AH, Lindow SE. Cell-cell signaling controls Xylella fastidiosa interactions with both insects and plants. Proc Natl Acad Sci U S A 2004; 101:1737-42. [PMID: 14755059 PMCID: PMC341844 DOI: 10.1073/pnas.0308399100] [Citation(s) in RCA: 192] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
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 diffusible signal molecule is required for biofilm formation in the vector and for vector transmission to plants. We constructed strains of X. fastidiosa mutated in the rpfF gene and determined that they are unable to produce the signal activity. In addition, rpfF mutants are more virulent than the wild type when mechanically inoculated into plants. This signal therefore directs interaction of X. fastidiosa with both its insect vector and plant host. Interestingly, rpfF mutants can still form in planta biofilms, which differ architecturally from biofilms in insects, suggesting that biofilm architecture, rather than a passive response to the environment, is actively determined by X. fastidiosa gene expression. This article reports a cell-cell signaling requirement for vector transmission. Identification of the genes regulated by rpfF should elucidate bacterial factors involved in transmission and biofilm formation in the insect.
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Affiliation(s)
- Karyn L Newman
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720
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40
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Moreira LM, de Souza RF, Almeida NF, Setubal JC, Oliveira JCF, Furlan LR, Ferro JA, da Silva ACR. Comparative genomics analyses of citrus-associated bacteria. ANNUAL REVIEW OF PHYTOPATHOLOGY 2004; 42:163-184. [PMID: 15283664 DOI: 10.1146/annurev.phyto.42.040803.140310] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Xylella fastidiosa 9a5c (XF-9a5c) and Xanthomonas axonopodis pv. citri (XAC) are bacteria that infect citrus plants. Sequencing of the genomes of these strains is complete and comparative analyses are now under way with the genomes of other bacteria of the same genera. In this review, we present an overview of this comparative genomic work. We also present a detailed genomic comparison between XF-9a5a and XAC. Based on this analysis, genes and operons were identified that might be relevant for adaptation to citrus. XAC has two copies of a type II secretion system, a large number of cell wall-degrading enzymes and sugar transporters, a complete energy metabolism, a whole set of avirulence genes associated with a type III secretion system, and a complete flagellar and chemotatic system. By contrast, XF-9a5c possesses more genes involved with type IV pili biosynthesis than does XAC, contains genes encoding for production of colicins, and has 4 copies of Type I restriction/modification system while XAC has only one.
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Affiliation(s)
- Leandro M Moreira
- Departamento de Bioquimica, Instituto de Quimica, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
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41
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Newman KL, Almeida RPP, Purcell AH, Lindow SE. Use of a green fluorescent strain for analysis of Xylella fastidiosa colonization of Vitis vinifera. Appl Environ Microbiol 2003; 69:7319-27. [PMID: 14660381 PMCID: PMC310014 DOI: 10.1128/aem.69.12.7319-7327.2003] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2003] [Accepted: 09/04/2003] [Indexed: 11/20/2022] Open
Abstract
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 analysis of colonization in a susceptible host, Vitis vinifera. In symptomatic leaves, the fraction of vessels colonized by X. fastidiosa was fivefold higher than in nearby asymptomatic leaves. The fraction of vessels completely blocked by X. fastidiosa colonies increased 40-fold in symptomatic leaves and was the feature of colonization most dramatically linked to symptoms. Therefore, the extent of vessel blockage by bacterial colonization is highly likely to be a crucial variable in symptom expression. Intriguingly, a high proportion (>80%) of colonized vessels were not blocked in infected leaves and instead had small colonies or solitary cells, suggesting that vessel blockage is not a colonization strategy employed by the pathogen but, rather, a by-product of endophytic colonization. We present evidence for X. fastidiosa movement through bordered pits to neighboring vessels and propose that vessel-to-vessel movement is a key colonization strategy whose failure results in vessel plugging and disease.
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Affiliation(s)
- Karyn L Newman
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
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