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prophage-mediated dynamics of 'candidatus liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. there are at least two prophages in the chromosomes of candidatus liberibacter asiaticus' (las) floridian isolates. las is both unculturable and the most prevalent species of liberibacter pathogens that cause huanglongbing (hlb), a worldwide destructive disease of citrus. in this study, seven new prophage variants resulting from two hyper-variable regions were identified by scre ...201324349235
genomic survey of pathogenicity determinants and vntr markers in the cassava bacterial pathogen xanthomonas axonopodis pv. manihotis strain cio151.xanthomonas axonopodis pv. manihotis (xam) is the causal agent of bacterial blight of cassava, which is among the main components of human diet in africa and south america. current information about the molecular pathogenicity factors involved in the infection process of this organism is limited. previous studies in other bacteria in this genus suggest that advanced draft genome sequences are valuable resources for molecular studies on their interaction with plants and could provide valuable too ...201324278159
multilocus variable-number-tandem-repeats analysis (mlva) distinguishes a clonal complex of clavibacter michiganensis subsp. michiganensis strains isolated from recent outbreaks of bacterial wilt and canker in belgium.clavibacter michiganensis subsp. michiganensis (cmm) causes bacterial wilt and canker in tomato. cmm is present nearly in all european countries. during the last three years several local outbreaks were detected in belgium. the lack of a convenient high-resolution strain-typing method has hampered the study of the routes of transmission of cmm and epidemiology in tomato cultivation. in this study the genetic relatedness among a worldwide collection of cmm strains and their relatives was approach ...201323738754
candidatus liberibacter americanus induces significant reprogramming of the transcriptome of the susceptible citrus genotype.citrus huanglongbing (hlb) disease is caused by endogenous, phloem-restricted, gram negative, uncultured bacteria named candidatus liberibacter africanus (calaf), ca. l. asiaticus (calas), and ca. l. americanus (calam), depending on the continent where the bacteria were first detected. the asian citrus psyllid vector, diaphorina citri, transmits calas and calam and both liberibacter species are present in brazil. several studies of the transcriptional response of citrus plants manifesting hlb sy ...201323586643
insights into xanthomonas axonopodis pv. citri biofilm through proteomics.xanthomonas axonopodis pv. citri (x. a. pv. citri) causes citrus canker that can result in defoliation and premature fruit drop with significant production losses worldwide. biofilm formation is an important process in bacterial pathogens and several lines of evidence suggest that in x. a. pv. citri this process is a requirement to achieve maximal virulence since it has a major role in host interactions. in this study, proteomics was used to gain further insights into the functions of biofilms.201323924281
a novel two-component response regulator links rpf with biofilm formation and virulence of xanthomonas axonopodis pv. citri.citrus bacterial canker caused by xanthomonas axonopodis pv. citri is a serious disease that impacts citrus production worldwide, and x. axonopodis pv. citri is listed as a quarantine pest in certain countries. biofilm formation is important for the successful development of a pathogenic relationship between various bacteria and their host(s). to understand the mechanisms of biofilm formation by x. axonopodis pv. citri strain xw19, the strain was subjected to transposon mutagenesis. one mutant w ...201323626857
structural determinants for activity and specificity of the bacterial toxin llpa.lectin-like bacteriotoxic proteins, identified in several plant-associated bacteria, are able to selectively kill closely related species, including several phytopathogens, such as pseudomonas syringae and xanthomonas species, but so far their mode of action remains unrevealed. the crystal structure of llpabw, the prototype lectin-like bacteriocin from pseudomonas putida, reveals an architecture of two monocot mannose-binding lectin (mmbl) domains and a c-terminal β-hairpin extension. the c-term ...201323468636
plant-bacterium interactions analyzed by proteomics.the evolution of the plant immune response has resulted in a highly effective defense system that is able to resist potential attack by microbial pathogens. the primary immune response is referred to as pathogen associated molecular pattern (pamp) triggered immunity and has evolved to recognize common features of microbial pathogens. in response to the delivery of pathogen effector proteins, plants acquired r proteins to fight against pathogen attack. r-dependent defense response is important in ...201323424014
host immune responses accelerate pathogen evolution.pathogens face a hostile and often novel environment when infecting a new host, and adaptation is likely to be an important determinant of the success in colonization and establishment. we hypothesized that resistant hosts will impose stronger selection on pathogens than susceptible hosts, which should accelerate pathogen evolution through selection biased toward effector genes. to test this hypothesis, we conducted an experimental evolution study on xanthomonas citri subsp. citri (xcc) in a sus ...201324304673
host immune responses accelerate pathogen evolution.pathogens face a hostile and often novel environment when infecting a new host, and adaptation is likely to be an important determinant of the success in colonization and establishment. we hypothesized that resistant hosts will impose stronger selection on pathogens than susceptible hosts, which should accelerate pathogen evolution through selection biased toward effector genes. to test this hypothesis, we conducted an experimental evolution study on xanthomonas citri subsp. citri (xcc) in a sus ...201324304673
high-quality draft genome sequences of two xanthomonas citri pv. malvacearum strains.we report high-quality draft genome sequences of two strains (race 18 and 20) of xanthomonas citri pv. malvacearum, the causal agent of bacterial blight of cotton. comparative genomics will help to decipher mechanisms provoking disease and triggering defense responses and to develop new molecular tools for epidemiological surveillance.201323990578
comparative genomic and transcriptome analyses of pathotypes of xanthomonas citri subsp. citri provide insights into mechanisms of bacterial virulence and host range.citrus bacterial canker is a disease that has severe economic impact on citrus industries worldwide and is caused by a few species and pathotypes of xanthomonas. x. citri subsp. citri strain 306 (xcca306) is a type a (asiatic) strain with a wide host range, whereas its variant x. citri subsp. citri strain a(w)12879 (xcaw12879, wellington strain) is restricted to mexican lime.201323941402
citrus maf1, a repressor of rna polymerase iii, binds the xanthomonas citri canker elicitor ptha4 and suppresses citrus canker development.transcription activator-like (tal) effectors from xanthomonas species pathogens act as transcription factors in plant cells; however, how tal effectors activate host transcription is unknown. we found previously that tal effectors of the citrus canker pathogen xanthomonas citri, known as pthas, bind the carboxyl-terminal domain of the sweet orange (citrus sinensis) rna polymerase ii (pol ii) and inhibit the activity of cscyp, a cyclophilin associated with the carboxyl-terminal domain of the citr ...201323898043
antibacterial activity of extracellular compounds produced by a pseudomonas strain against methicillin-resistant staphylococcus aureus (mrsa) strains.the emergence of multidrug-resistant bacteria is a world health problem. staphylococcus aureus, including methicillin-resistant s. aureus (mrsa) strains, is one of the most important human pathogens associated with hospital and community-acquired infections. the aim of this work was to evaluate the antibacterial activity of a pseudomonas aeruginosa-derived compound against mrsa strains.201323773484
a redox 2-cys mechanism regulates the catalytic activity of divergent cyclophilins.the citrus (citrus sinensis) cyclophilin cscyp is a target of the xanthomonas citri transcription activator-like effector ptha, required to elicit cankers on citrus. cscyp binds the citrus thioredoxin cstdx and the carboxyl-terminal domain of rna polymerase ii and is a divergent cyclophilin that carries the additional loop ksgkplh, invariable cysteine (cys) residues cys-40 and cys-168, and the conserved glutamate (glu) glu-83. despite the suggested roles in atp and metal binding, the functions o ...201323709667
complete genome sequence of xanthomonas citri subsp. citri strain aw12879, a restricted-host-range citrus canker-causing bacterium.xanthomonas citri subsp. citri causes citrus canker. the asiatic strain has a broad host range, whereas the wellington variant has a restricted host range. here, we present the complete genome of x. citri subsp. citri strain a(w)12879. this study lays the foundation to further characterize the mechanisms for virulence and host range of x. citri.201323682143
antibacterial activity of alkyl gallates against xanthomonas citri subsp. citri.the plant-pathogenic bacterium xanthomonas citri subsp. citri is the causal agent of asiatic citrus canker, a serious disease that affects all the cultivars of citrus in subtropical citrus-producing areas worldwide. there is no curative treatment for citrus canker; thus, the eradication of infected plants constitutes the only effective control of the spread of x. citri subsp. citri. since the eradication program in the state of são paulo, brazil, is under threat, there is a clear risk of x. citr ...201323104804
the role of bacterial biofilms and surface components in plant-bacterial associations.the role of bacterial surface components in combination with bacterial functional signals in the process of biofilm formation has been increasingly studied in recent years. plants support a diverse array of bacteria on or in their roots, transport vessels, stems, and leaves. these plant-associated bacteria have important effects on plant health and productivity. biofilm formation on plants is associated with symbiotic and pathogenic responses, but how plants regulate such associations is unclear ...201323903045
the lov protein of xanthomonas citri subsp. citri plays a significant role in the counteraction of plant immune responses during citrus canker.pathogens interaction with a host plant starts a set of immune responses that result in complex changes in gene expression and plant physiology. light is an important modulator of plant defense response and recent studies have evidenced the novel influence of this environmental stimulus in the virulence of several bacterial pathogens. xanthomonas citri subsp. citri is the bacterium responsible for citrus canker disease, which affects most citrus cultivars. the ability of this bacterium to coloni ...201324260514
efficient talen construction for bombyx mori gene targeting.engineered nucleases are artificial enzymes able to introduce double stranded breaks at desired genomic locations. the double stranded breaks start the error-prone repair process of non-homologous end-joining (nhej), which eventually leads to the induction of mutations at target sites. we showed earlier that zfns and talens are able to induce nhej mutations in the b. mori genome. in order to optimize our mutagenesis protocol, we modified one of the reported truncated talen scaffolds and optimize ...201324058473
asymmetric chromosome segregation in xanthomonas citri ssp. citri.this study was intended to characterize the chromosome segregation process of xanthomonas citri ssp. citri (xac) by investigating the functionality of the parb factor encoded on its chromosome, and its requirement for cell viability and virulence. using tap tagging we show that parb is expressed in xac. disruption of parb increased the cell doubling time and precluded the ability of xac to colonize the host citrus. moreover, xac mutant cells expressing only truncated forms of parb exhibited the ...201324339434
asymmetric chromosome segregation in xanthomonas citri ssp. citri.this study was intended to characterize the chromosome segregation process of xanthomonas citri ssp. citri (xac) by investigating the functionality of the parb factor encoded on its chromosome, and its requirement for cell viability and virulence. using tap tagging we show that parb is expressed in xac. disruption of parb increased the cell doubling time and precluded the ability of xac to colonize the host citrus. moreover, xac mutant cells expressing only truncated forms of parb exhibited the ...201324339434
structural and physiological analyses of the alkanesulphonate-binding protein (ssua) of the citrus pathogen xanthomonas citri.the uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the xanthomonas genus, which encompasses several pathogenic species. in the present study, we characterised the alkanesulphonate uptak ...201324282519
the role of semidisorder in temperature adaptation of bacterial flgm proteins.probabilities of disorder for flgm proteins of 39 species whose optimal growth temperature ranges from 273 k (0°c) to 368 k (95°c) were predicted by a newly developed method called sequence-based prediction with integrated neural networks for disorder (spine-d). we showed that the temperature-dependent behavior of flgm proteins could be separated into two subgroups according to their sequence lengths. only shorter sequences evolved to adapt to high temperatures (>318 k or 45°c). their ability to ...201324314090
arhodomonas sp. strain seminole and its genetic potential to degrade aromatic compounds under high-salinity conditions.arhodomonas sp. strain seminole was isolated from a crude oil-impacted brine soil and shown to degrade benzene, toluene, phenol, 4-hydroxybenzoic acid (4-hba), protocatechuic acid (pca), and phenylacetic acid (paa) as the sole sources of carbon at high salinity. seminole is a member of the genus arhodomonas in the class gammaproteobacteria, sharing 96% 16s rrna gene sequence similarity with arhodomonas aquaeolei ha-1. analysis of the genome predicted a number of catabolic genes for the metabolis ...201425149520
structure determination of a sugar-binding protein from the phytopathogenic bacterium xanthomonas citri.the uptake of maltose and related sugars in gram-negative bacteria is mediated by an abc transporter encompassing a periplasmic component (the maltose-binding protein or male), a pore-forming membrane protein (malf and malg) and a membrane-associated atpase (malk). in the present study, the structure determination of the apo form of the putative maltose/trehalose-binding protein (xac-male) from the citrus pathogen xanthomonas citri in space group p6522 is described. the crystals contained two pr ...201424817711
evaluation of reference genes for gene expression analysis using quantitative rt-pcr in azospirillum brasilense.azospirillum brasilense is a nitrogen fixing bacterium that has been shown to have various beneficial effects on plant growth and yield. under normal conditions a. brasilense exists in a motile flagellated form, which, under starvation or stress conditions, can undergo differentiation into an encapsulated, cyst-like form. quantitative rt-pcr can be used to analyse changes in gene expression during this differentiation process. the accuracy of quantification of mrna levels by qrt-pcr relies on th ...201424841066
characterization of bacteriophages cp1 and cp2, the strain-typing agents for xanthomonas axonopodis pv. citri.the strains of xanthomonas axonopodis pv. citri, the causative agent of citrus canker, are historically classified based on bacteriophage (phage) sensitivity. nearly all x. axonopodis pv. citri strains isolated from different regions in japan are lysed by either phage cp1 or cp2; cp1-sensitive (cp1(s)) strains have been observed to be resistant to cp2 (cp2(r)) and vice versa. in this study, genomic and molecular characterization was performed for the typing agents cp1 and cp2. morphologically, c ...201424123743
crystallization and preliminary x-ray diffraction analysis of the phosphate-binding protein phox from xanthomonas citri.xanthomonas axonopodis pv. citri (x. citri) is an important bacterium that causes citrus canker disease in plants in brazil and around the world, leading to significant economic losses. determination of the physiology and mechanisms of pathogenesis of this bacterium is an important step in the development of strategies for its containment. phosphate is an essential ion in all microrganisms owing its importance during the synthesis of macromolecules and in gene and protein regulation. interesting ...201425484207
structural and biochemical characteristics of citrus flowers associated with defence against a fungal pathogen.the constitutive characters of plants can be structural or biochemical and play an important role in their defence against pathogens. citrus postbloom fruit drop (pfd) caused by colletotrichum spp. is one of the most important fungal diseases of citrus. the pathogen infects the flowers, leading to premature fruit drop and reducing citrus production. however, flower buds smaller than 8 mm long are usually not infected by colletotrichum spp. thus, this study investigated whether there are constitu ...201425535209
structural and biochemical characteristics of citrus flowers associated with defence against a fungal pathogen.the constitutive characters of plants can be structural or biochemical and play an important role in their defence against pathogens. citrus postbloom fruit drop (pfd) caused by colletotrichum spp. is one of the most important fungal diseases of citrus. the pathogen infects the flowers, leading to premature fruit drop and reducing citrus production. however, flower buds smaller than 8 mm long are usually not infected by colletotrichum spp. thus, this study investigated whether there are constitu ...201425535209
xylella fastidiosa outer membrane vesicles modulate plant colonization by blocking attachment to surfaces.outer membrane vesicles (omvs) of gram-negative bacteria have been studied intensively in recent years, primarily in their role in delivering virulence factors and antigens during pathogenesis. however, the near ubiquity of their production suggests that they may play other roles, such as responding to envelope stress or trafficking various cargoes to prevent dilution or degradation by other bacterial species. here we show that omvs produced by xylella fastidiosa, a xylem-colonizing plant pathog ...201425197068
antibacterial activity of pseudonocardia sp. jb05, a rare salty soil actinomycete against staphylococcus aureus.staphylococcus aureus is a gram-positive bacterium that causes many harmful and life-threatening diseases. some strains of this bacterium are resistant to available antibiotics. this study was designed to evaluate the ability of indigenous actinomycetes to produce antibacterial compounds against s. aureus and characterize the structure of the resultant antibacterial compounds. therefore, a slightly modified agar well diffusion method was used to determine the antibacterial activity of actinomyce ...201425202705
annotation of gene function in citrus using gene expression information and co-expression networks.the genus citrus encompasses major cultivated plants such as sweet orange, mandarin, lemon and grapefruit, among the world's most economically important fruit crops. with increasing volumes of transcriptomics data available for these species, gene co-expression network (gcn) analysis is a viable option for predicting gene function at a genome-wide scale. gcn analysis is based on a "guilt-by-association" principle whereby genes encoding proteins involved in similar and/or related biological proce ...201425023870
targeted genome editing of sweet orange using cas9/sgrna.genetic modification, including plant breeding, has been widely used to improve crop yield and quality, as well as to increase disease resistance. targeted genome engineering is expected to contribute significantly to future varietal improvement, and genome editing technologies using zinc finger nucleases (zfns), transcription activator-like effector nucleases (talens), and clustered regularly interspaced short palindromic repeat (crispr)/cas9/single guide rna (sgrna) have already been successfu ...201424710347
identification of putative tal effector targets of the citrus canker pathogens shows functional convergence underlying disease development and defense response.transcriptional activator-like (tal) effectors, formerly known as the avrbs3/ptha protein family, are dna-binding effectors broadly found in xanthomonas spp. that transactivate host genes upon injection via the bacterial type three-secretion system. biologically relevant targets of tal effectors, i.e. host genes whose induction is vital to establish a compatible interaction, have been reported for xanthomonads that colonize rice and pepper; however, citrus genes modulated by the tal effectors pt ...201424564253
repertoire of novel sequence signatures for the detection of candidatus liberibacter asiaticus by quantitative real-time pcr.huanglongbing (hlb) or citrus greening is a devastating disease of citrus. the gram-negative bacterium candidatus liberibacter asiaticus (las) belonging to the α-proteobacteria is responsible for hlb in north america as well as in asia. currently, there is no cure for this disease. early detection and quarantine of las-infected trees are important management strategies used to prevent hlb from invading hlb-free citrus producing regions. quantitative real-time pcr (qrt-pcr) based molecular diagno ...201424533511
a comparison of rna-seq and exon arrays for whole genome transcription profiling of the l5 spinal nerve transection model of neuropathic pain in the rat.the past decade has seen an abundance of transcriptional profiling studies of preclinical models of persistent pain, predominantly employing microarray technology. in this study we directly compare exon microarrays to rna-seq and investigate the ability of both platforms to detect differentially expressed genes following nerve injury using the l5 spinal nerve transection model of neuropathic pain. we also investigate the effects of increasing rna-seq sequencing depth. finally we take advantage o ...201424472155
the filamentous phage xacf1 causes loss of virulence in xanthomonas axonopodis pv. citri, the causative agent of citrus canker disease.in this study, filamentous phage xacf1, which can infect xanthomonas axonopodis pv. citri (xac) strains, was isolated and characterized. electron microscopy showed that xacf1 is a member of the family inoviridae and is about 600 nm long. the genome of xacf1 is 7325 nucleotides in size, containing 13 predicted open reading frames (orfs), some of which showed significant homology to ff-like phage proteins such as orf1 (pii), orf2 (pv), orf6 (piii), and orf8 (pvi). xacf1 showed a relatively wide ho ...201425071734
population typing of the causal agent of cassava bacterial blight in the eastern plains of colombia using two types of molecular markers.molecular typing of pathogen populations is an important tool for the development of effective strategies for disease control. diverse molecular markers have been used to characterize populations of xanthomonas axonopodis pv. manihotis (xam), the main bacterial pathogen of cassava. recently, diversity and population dynamics of xam in the colombian caribbean coast were estimated using aflps, where populations were found to be dynamic, diverse and with haplotypes unstable across time. aiming to e ...201424946775
a mlva genotyping scheme for global surveillance of the citrus pathogen xanthomonas citri pv. citri suggests a worldwide geographical expansion of a single genetic lineage.multilocus variable number of tandem repeat analysis (mlva) has been extensively used to examine epidemiological and evolutionary issues on monomorphic human pathogenic bacteria, but not on bacterial plant pathogens of agricultural importance albeit such tools would improve our understanding of their epidemiology, as well as of the history of epidemics on a global scale. xanthomonas citri pv. citri is a quarantine organism in several countries and a major threat for the citrus industry worldwide ...201424897119
the post-transcriptional regulator rsma/csra activates t3ss by stabilizing the 5' utr of hrpg, the master regulator of hrp/hrc genes, in xanthomonas.the rsma/csra family of the post-transcriptional regulators of bacteria is involved in the regulation of many cellular processes, including pathogenesis. in this study, we demonstrated that rsma not only is required for the full virulence of the phytopathogenic bacterium xanthomonas citri subsp. citri (xcc) but also contributes to triggering the hypersensitive response (hr) in non-host plants. deletion of rsma resulted in significantly reduced virulence in the host plant sweet orange and a delay ...201424586158
o serotype-independent susceptibility of pseudomonas aeruginosa to lectin-like pyocins.lectin-like bacteriocins of the llpa family, originally identified in plant-associated bacteria, are narrow-spectrum antibacterial proteins composed of two tandemly organized monocot mannose-binding lectin (mmbl) domains. the llpa-like bacteriocin of pseudomonas aeruginosa c1433, pyocin l1, lacks any similarity to known p. aeruginosa bacteriocins. the initial interaction of pyocin l1 with target cells is mediated by binding to d-rhamnose, present in the common polysaccharide antigen of lipopolys ...201425224846
the type iii protein secretion system contributes to xanthomonas citri subsp. citri biofilm formation.several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a type iii protein secretion system (t3ss). the role of t3ss in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. here, the phytopathogen xanthomonas citri subsp. citri (x. citri) was used as a model to gain further insights about the role of the t3ss in biofilm formation.201424742141
comparative genomics of type vi secretion systems in strains of pantoea ananatis from different environments.the type vi secretion system (t6ss) has been identified in several different bacteria, including the plant pathogenpantoea ananatis. previous in silico analyses described three different t6ss loci present in the pathogenic strain of p. ananatis lmg 20103. this initial investigation has been extended to include an additional seven sequenced strains of p. ananatis together with 39 strains from different ecological niches. comparative and phylogenetic analyses were used to investigate the distribut ...201424571088
lectin-like bacteriocins from pseudomonas spp. utilise d-rhamnose containing lipopolysaccharide as a cellular receptor.lectin-like bacteriocins consist of tandem monocot mannose-binding domains and display a genus-specific killing activity. here we show that pyocin l1, a novel member of this family from pseudomonas aeruginosa, targets susceptible strains of this species through recognition of the common polysaccharide antigen (cpa) of p. aeruginosa lipopolysaccharide that is predominantly a homopolymer of d-rhamnose. structural and biophysical analyses show that recognition of cpa occurs through the c-terminal c ...201424516380
genomic insights into the evolutionary origin of xanthomonas axonopodis pv. citri and its ecological relatives.xanthomonas axonopodis pv. citri (xac) is the causal agent of citrus bacterial canker (cbc) and is a serious problem worldwide. like cbc, several important diseases in other fruits, such as mango, pomegranate, and grape, are also caused by xanthomonas pathovars that display remarkable specificity toward their hosts. while citrus and mango diseases were documented more than 100 years ago, the pomegranate and grape diseases have been known only since the 1950s and 1970s, respectively. interestingl ...201425085494
intervention of phytohormone pathways by pathogen effectors.the constant struggle between plants and microbes has driven the evolution of multiple defense strategies in the host as well as offense strategies in the pathogen. to defend themselves from pathogen attack, plants often rely on elaborate signaling networks regulated by phytohormones. in turn, pathogens have adopted innovative strategies to manipulate phytohormone-regulated defenses. tactics frequently employed by plant pathogens involve hijacking, evading, or disrupting hormone signaling pathwa ...201424920334
rapid and sensitive detection of candidatus liberibacter asiaticus by loop mediated isothermal amplification combined with a lateral flow dipstick.citrus huanglongbing (hlb) is the most devastating bacterial citrus disease worldwide. three candidatus liberibacter species are associated with different forms of the disease: candidatus liberibacter asiaticus, candidatus liberibacter americanus and candidatus liberibacter africanus. amongst them, candidatus liberibacter asiaticus is the most widespread and economically important. these gram-negative bacterial plant pathogens are phloem-limited and vectored by citrus psyllids. the current manag ...201424708539
type iv secretion system is not involved in infection process in citrus.the type iv secretion system (t4ss) is used by gram-negative bacteria to translocate protein and dna substrates across the cell envelope and into target cells. xanthomonas citri subsp. citri contains two copies of the t4ss, one in the chromosome and the other is plasmid-encoded. to understand the conditions that induce expression of the t4ss in xcc, we analyzed, in vitro and in planta, the expression of 18 orfs from the t4ss and 7 hypothetical flanking genes by rt-qpcr. as a positive control, we ...201424707292
genomic analysis of xanthomonas translucens pathogenic on wheat and barley reveals cross-kingdom gene transfer events and diverse protein delivery systems.in comparison to dicot-infecting bacteria, only limited numbers of genome sequences are available for monocot-infecting and in particular cereal-infecting bacteria. herein we report the characterisation and genome sequence of xanthomonas translucens isolate dar61454 pathogenic on wheat and barley. based on phylogenetic analysis of the atp synthase beta subunit (atpd) gene, dar61454 is most closely related to other x. translucens strains and the sugarcane- and banana- infecting xanthomonas strain ...201424416331
enzymatic strategies and biocatalysts for amide bond formation: tricks of the trade outside of the ribosome.amide bond-containing (abc) biomolecules are some of the most intriguing and functionally significant natural products with unmatched utility in medicine, agriculture and biotechnology. the enzymatic formation of an amide bond is therefore a particularly interesting platform for engineering the synthesis of structurally diverse natural and unnatural abc molecules for applications in drug discovery and molecular design. as such, efforts to unravel the mechanisms involved in carboxylate activation ...201425418915
enzymatic strategies and biocatalysts for amide bond formation: tricks of the trade outside of the ribosome.amide bond-containing (abc) biomolecules are some of the most intriguing and functionally significant natural products with unmatched utility in medicine, agriculture and biotechnology. the enzymatic formation of an amide bond is therefore a particularly interesting platform for engineering the synthesis of structurally diverse natural and unnatural abc molecules for applications in drug discovery and molecular design. as such, efforts to unravel the mechanisms involved in carboxylate activation ...201425418915
molecular mechanisms associated with xylan degradation by xanthomonas plant pathogens.xanthomonas pathogens attack a variety of economically relevant plants, and their xylan cut system (carbohydrate utilization with tonb-dependent outer membrane transporter system) contains two major xylanase-related genes, xyna and xynb, which influence biofilm formation and virulence by molecular mechanisms that are still elusive. herein, we demonstrated that xyna is a rare reducing end xylose-releasing exo-oligoxylanase and not an endo-β-1,4-xylanase as predicted. structural analysis revealed ...201425266726
lateral organ boundaries 1 is a disease susceptibility gene for citrus bacterial canker disease.citrus bacterial canker (cbc) disease occurs worldwide and incurs considerable costs both from control measures and yield losses. bacteria that cause cbc require one of six known type iii transcription activator-like (tal) effector genes for the characteristic pustule formation at the site of infection. here, we show that xanthomonas citri subspecies citri strain xcc306, with the type iii tal effector gene ptha4 or with the distinct yet biologically equivalent gene pthaw from strain xcca(w), ind ...201424474801
xanthomonas citri subsp. citri type iv pilus is required for twitching motility, biofilm development, and adherence.bacterial type iv pili (t4p) are long, flexible surface filaments that consist of helical polymers of mostly pilin subunits. cycles of polymerization, attachment, and depolymerization mediate several pilus-dependent bacterial behaviors, including twitching motility, surface adhesion, pathogenicity, natural transformation, escape from immune system defense mechanisms, and biofilm formation. the xanthomonas citri subsp. citri strain 306 genome codes for a large set of genes involved in t4p biogene ...201425180689
characterization of three linalool synthase genes from citrus unshiu marc. and analysis of linalool-mediated resistance against xanthomonas citri subsp. citri and penicilium italicum in citrus leaves and fruits.three cdna clones from satsuma mandarin (citrus unshiu marc.) were isolated and expressed in escherichia coli. custs3-1 and custs3-2 encode linalool synthases and custs4 encodes a nerolidol/linalool synthase. transcripts of custs3-1, custs3-2 and custs4 were abundant in young fruit at 60 days after flowering (daf), flowers and leaves, respectively. treatments with xanthomonas citri subsp. citri (xcc), the causal agent of citrus canker and penicillium italicum (pi), the cause of post-harvest frui ...201425443842
characterisation of a novel endo-xyloglucanase (xcxgha) from xanthomonas that accommodates a xylosyl-substituted glucose at subsite -1.a xyloglucan-specific endo-1,4β-glucanase (xcxgha) from xanthomonas citri pv. mangiferaeindicae has been cloned, expressed in escherichia coli, purified and characterised. the xcxgha enzyme belongs to cazy family gh74 and has catalytic site residues conserved with other xyloglucanases in this family. at its optimal reaction conditions, ph 7.0 and 40 °c, the enzyme has a k cat/k m value of 2.2 × 10(7) min(-1) m(-1) on a tamarind seed xyloglucan substrate. xcxgha is relatively stable within a broa ...201424898632
phosphate regulated proteins of xanthomonas citri subsp. citri: a proteomic approach.xanthomonas citri subsp. citri (x. citri) is the causative agent of the citrus canker, a disease that affects several citrus plants in brazil and across the world. although many studies have demonstrated the importance of genes for infection and pathogenesis in this bacterium, there are no data related to phosphate uptake and assimilation pathways. to identify the proteins that are involved in the phosphate response, we performed a proteomic analysis of x. citri extracts after growth in three cu ...201424846853
chimeric proteins combining phosphatase and cellulose-binding activities: proof-of-concept and application in the hydrolysis of paraoxon.phosphatases for organophosphate degradation and carbohydrate-binding domains (cbms) have potential biotechnological applications. as a proof-of-concept, a soluble chimeric protein that combines acid phosphatase (appa) from escherichia coli and a cbm from xanthomonas axonopodis pv. citri (appa-cbm) was produced in e.coli. appacbm adsorbed in microcrystalline cellulose avicel ph101 catalyzed the hydrolysis of p-nitrophenyl phosphate (pnpp). the binding to microcrystalline cellulose displayed satu ...201424555432
lactose consuming strains of xanthomonas citri subsp. citri (xcc) insight into the emergence of natural field resources for xanthan gum production.xanthomonas genus possesses a low level of β-galactosidase gene expression and is therefore unable to produce xanthan gum in lactose-based media. in this study, we report the emergence of some natural field strains of xanthomonas citri subsp. citri (xcc) capable to use lactose as a sole carbon source to produce xanthan gum. from 210 xcc strains isolated from key lime (c. aurantifolia), 27 showed the capacity to grow on lactose containing medium. xcc lactose consuming strains demonstrated a good ...201424318518
foliar application of biofilm formation-inhibiting compounds enhances control of citrus canker caused by xanthomonas citri subsp. citri.citrus canker caused by the bacterium xanthomonas citri subsp. citri is an economically important disease of citrus worldwide. biofilm formation plays an important role in early infection of x. citri subsp. citri on host leaves. in this study, we assessed the hypothesis that small molecules inhibiting biofilm formation reduce x. citri subsp. citri infection and enhance the control of citrus canker disease. d-leucine and 3-indolylacetonitrile (ian) were found to prevent biofilm formation by x. ci ...201423901828
xcc-facilitated agroinfiltration of citrus leaves: a tool for rapid functional analysis of transgenes in citrus leaves.xanthomonas citri subsp. citri pretreatment before agroinfiltration could significantly promote transient expression in citrus leaves which were previously recalcitrant to agroinfiltration. transient expression via agroinfiltration is widely used in biotechnology but remains problematic in many economically important plants. xanthomonas citri subsp. citri (xcc)-facilitated agroinfiltration was employed to promote transient protein expression in valencia sweet orange leaves, which are recalcitran ...201425146436
expression of xylella fastidiosa rpff in citrus disrupts signaling in xanthomonas citri subsp. citri and thereby its virulence.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 carr ...201425099341
xanthan gum removal for 1h-nmr analysis of the intracellular metabolome of the bacteria xanthomonas axonopodis pv. citri 306.xanthomonas is a genus of phytopathogenic bacteria, which produces a slimy, polysaccharide matrix known as xanthan gum, which involves, protects and helps the bacteria during host colonization. although broadly used as a stabilizer and thickener in the cosmetic and food industries, xanthan gum can be a troubling artifact in molecular investigations due to its rheological properties. in particular, a cross-reaction between reference compounds and the xanthan gum could compromise metabolic quantif ...201424957023
the role as inoculum sources of xanthomonas citri pv. citri surviving on the infected satsuma mandarin fruits.importing citrus fruits infected by asiatic citrus canker caused by xanthomonas citri pv. citri (xcc) can act as an inoculum source for the disease epidemic in citrus canker-free countries. in this study, the pathogenicity of the causal agent of asiatic citrus canker surviving on infected satsuma mandarin fruits was evaluated. the washing solution of infected satsuma mandarin fruits did not cause lesion formation on the citrus leaves. however, a typical citrus canker lesion was formed on the lea ...201424723102
comparative proteomic analysis reveals that t3ss, tfp, and xanthan gum are key factors in initial stages of citrus sinensis infection by xanthomonas citri subsp. citri.the bacteria xanthomonas citri subsp. citri (xac) is the causal agent of citrus canker. the disease symptoms are characterized by localized host cell hyperplasia followed by tissue necrosis at the infected area. an arsenal of bacterial pathogenicity- and virulence-related proteins is expressed to ensure a successful infection process. at the post-genomic stage of xac, we used a proteomic approach to analyze the proteins that are displayed differentially over time when the pathogen attacks the ho ...201424676796
surface barriers of mandarin 'okitsu' leaves make a major contribution to canker disease resistance.field evaluations have shown that satsuma mandarin (citrus unshiu) 'okitsu' is one of the mandarin cultivars that shows substantial resistance to xanthomonas citri subsp. citri (x. citri), the causal agent of citrus bacterial canker disease. however, the mechanisms underlying this resistance are not well understood. in this study, we have shown that 'okitsu' leaves are nevertheless susceptible to x. citri infection during a period of their development; however, this period is shorter than that s ...201424548213
a potential disease susceptibility gene cslob of citrus is targeted by a major virulence effector ptha of xanthomonas citri subsp. citri. 201424398629
the relationship between ptha expression and the pathogenicity of xanthomonas axonopodis pv. citri.citrus canker disease, caused by xanthomonas axonopodis pv. citri, affects almost all citrus species and cultivars and hascaused severe damage to the citrus industry worldwide. ptha is considered the main pathogenesis effector of the pathogen. this research aimed to temporally and spatially analyze the expression of the ptha protein of the bactrium during its culture, and then try to understand the relationship between the ptha expression levels and the pathogenicity. the relationship between th ...201424385299
highly polymorphic markers reveal the establishment of an invasive lineage of the citrus bacterial pathogen xanthomonas citri pv. citri in its area of origin.investigating the population biology of plant pathogens in their native areas is essential to understand the factors that shape their population structure and favour their spread. monomorphic pathogens dispatch extremely low genetic diversity in invaded areas, and native areas constitute a major reservoir for future emerging strains. one of these, the gammaproteobacterium xanthomonas citri pv. citri, causes asiatic canker and is a considerable threat to citrus worldwide. we studied its populatio ...201424373118
extracellular matrix-associated proteome changes during non-host resistance in citrus-xanthomonas interactions.non-host resistance (nhr) is a most durable broad-spectrum resistance employed by the plants to restrict majority of pathogens. plant extracellular matrix (ecm) is a critical defense barrier. understanding ecm responses during interaction with non-host pathogen will provide insights into molecular events of nhr. in this study, the ecm-associated proteome was compared during interaction of citrus with pathogen xanthomonas axonopodis pv. citri (xac) and non-host pathogen xanthomonas oryzae pv. ory ...201424117905
the efficacy and underlying mechanism of sulfone derivatives containing 1,3,4-oxadiazole on citrus canker.the objectives of the current study were to isolate and identify the pathogen responsible for citrus canker and investigate the efficacy of sulfone derivatives containing 1,3,4-oxadiazole moiety on controlling citrus canker caused by xanthomonas citri subsp. citri (xcc) under in vitro and field conditions. in an in vitro study, we tested eight sulfone derivatives against xcc and the results demonstrated that compound 3 exhibited the best antibacterial activity against xcc, with a half-maximal ef ...201526247929
accumulation of transcription factors and cell signaling-related proteins in the nucleus during citrus-xanthomonas interaction.the nucleus is the maestro of the cell and is involved in the modulation of cell signaling during stress. we performed a comprehensive nuclear proteome analysis of citrus sinensis during interaction with host (xanthomonas citri pv. citri-xcc) and non-host (xanthomonas oryzae pv. oryzae-xoo) pathogens. the nuclear proteome was obtained using a sequential method of organelle enrichment and determined by nano-lc-ms/ms analysis. a total of 243 proteins accumulated differentially during citrus-xantho ...201526202445
identification of seven novel virulence genes from xanthomonas citri subsp. citri by tn5-based random mutagenesis.to identify novel virulence genes, a mutant library of xanthomonas citri subsp. citri 29-1 was produced using ez-tn5 transposon and the mutants were inoculated into susceptible grapefruit. forty mutants with altered virulence phenotypes were identified. nine of the mutants showed a complete loss of citrus canker induction, and the other 31 mutants resulted in attenuated canker symptoms. southern blot analysis revealed that each of the mutants carried a single copy of tn5. the flanking sequence w ...201525935304
bridgehead invasion of a monomorphic plant pathogenic bacterium: xanthomonas citri pv. citri, an emerging citrus pathogen in mali and burkina faso.molecular epidemiology studies further our understanding of migrations of phytopathogenic bacteria, the major determining factor in their emergence. asiatic citrus canker, caused by xanthomonas citri pv. citri, was recently reported in mali and burkina faso, a region remote from other contaminated areas. to identify the origin and pathways of these emergences, we used two sets of markers, minisatellites and microsatellites, for investigating different evolutionary scales. minisatellite typing su ...201525866121
bacterial killing via a type iv secretion system.type iv secretion systems (t4sss) are multiprotein complexes that transport effector proteins and protein-dna complexes through bacterial membranes to the extracellular milieu or directly into the cytoplasm of other cells. many bacteria of the family xanthomonadaceae, which occupy diverse environmental niches, carry a t4ss with unknown function but with several characteristics that distinguishes it from other t4sss. here we show that the xanthomonas citri t4ss provides these cells the capacity t ...201525743609
cooperative substrate binding by a diguanylate cyclase.xac0610, from xanthomonas citri subsp. citri, is a large multi-domain protein containing one gaf (cgmp-specific phosphodiesterases, adenylyl cyclases and fhla) domain, four pas (per-arnt-sim) domains and one ggdef domain. this protein has a demonstrable in vivo and in vitro diguanylate cyclase (dgc) activity that leads to the production of cyclic di-gmp (c-di-gmp), a ubiquitous bacterial signaling molecule. analysis of a xacδ0610 knockout strain revealed that xac0610 plays a role in the regulati ...201525463434
chemotactic signal transduction and phosphate metabolism as adaptive strategies during citrus canker induction by xanthomonas citri.the genome of xanthomonas citri subsp. citri strain 306 pathotype a (xac) was completely sequenced more than 10 years; to date, few studies involving functional genomics xac and its host compatible have been developed, specially related to adaptive events that allow the survival of xac within the plant. proteomic analysis of xac showed that the processes of chemotactic signal transduction and phosphate metabolism are key adaptive strategies during the interaction of a pathogenic bacterium with i ...201525403594
a novel periplasmic protein, vrpa, contributes to efficient protein secretion by the type iii secretion system in xanthomonas spp.efficient secretion of type iii effector proteins from the bacterial cytoplasm to host cell cytosol via a type iii secretion system (t3ss) is crucial for virulence of plant-pathogenic bacterium. our previous study revealed a conserved hypothetical protein, virulence-related periplasm protein a (vrpa), which was identified as a critical virulence factor for xanthomonas citri subsp. citri. in this study, we demonstrate that mutation of vrpa compromises x. citri subsp. citri virulence and hypersens ...201525338144
responsiveness of different citrus genotypes to the xanthomonas citri ssp. citri-derived pathogen-associated molecular pattern (pamp) flg22 correlates with resistance to citrus canker.the bacterial agent of citrus canker disease (xanthomonas citri ssp. citri, xcc) has caused tremendous economic losses to the citrus industry around the world. pathogen-associated molecular pattern (pamp)-triggered immunity (pti) is important to plant immunity. in this study, we compared the defence responses of citrus canker-resistant and citrus canker-susceptible genotypes to the xcc-derived pamp flg22 (xflg22) by analysing the expression of 20 citrus defence-associated genes. we showed that, ...201525231217
xbmr, a new transcription factor involved in the regulation of chemotaxis, biofilm formation and virulence in xanthomonas citri subsp. citri.xanthomonas citri subsp. citri (xcc) is the causal agent of citrus canker. biofilm formation on citrus leaves plays an important role in epiphytic survival of xcc. biofilm formation is affected by transposon insertion in xac3733, which encodes a transcriptional activator of the ntrc family, not linked to a gene encoding a sensor protein, thus could be considered as an 'orphan' regulator whose function is poorly understood in xanthomonas spp. here we show that mutation of xac3733 (named xbmr) res ...201525346091
iron is a signal for stenotrophomonas maltophilia biofilm formation, oxidative stress response, omps expression, and virulence.stenotrophomonas maltophilia is an emerging nosocomial pathogen. in many bacteria iron availability regulates, through the fur system, not only iron homeostasis but also virulence. the aim of this work was to assess the role of iron on s. maltophilia biofilm formation, eps production, oxidative stress response, omps regulation, quorum sensing (qs), and virulence. studies were done on k279a and its isogenic fur mutant f60 cultured in the presence or absence of dipyridyl. this is the first report ...201526388863
the dsf family of cell-cell signals: an expanding class of bacterial virulence regulators.many pathogenic bacteria use cell-cell signaling systems involving the synthesis and perception of diffusible signal molecules to control virulence as a response to cell density or confinement to niches. bacteria produce signals of diverse structural classes. signal molecules of the diffusible signal factor (dsf) family are cis-2-unsaturated fatty acids. the paradigm is cis-11-methyl-2-dodecenoic acid from xanthomonas campestris pv. campestris (xcc), which controls virulence in this plant pathog ...201526181439
investigation of a quadruplex-forming repeat sequence highly enriched in xanthomonas and nostoc sp.in prokaryotes simple sequence repeats (ssrs) with unit sizes of 1-5 nucleotides (nt) are causative for phase and antigenic variation. although an increased abundance of heptameric repeats was noticed in bacteria, reports about ssrs of 6-9 nt are rare. in particular g-rich repeat sequences with the propensity to fold into g-quadruplex (g4) structures have received little attention. in silico analysis of prokaryotic genomes show putative g4 forming sequences to be abundant. this report focuses on ...201526695179
the draft genome sequence of xanthomonas sp. strain mitacek01 expands the pangenome of a genus of plant pathogens.we report the draft genome sequence of xanthomonas sp. strain mitacek01, isolated from an indoor environment vending machine surface with frequent human use in stillwater, oklahoma, usa, as part of the student-initiated microbial discovery project. the genome has a total size of 3,617,426 bp and a contig n50 of 1,906,967 bp.201526659686
the amino acid arginine 210 of the response regulator hrpg of xanthomonas citri subsp. citri is required for hrpg function in virulence.xanthomonas citri subsp. citri colonizes its hosts through the trafficking of effector proteins to the plant cell by the type iii protein secretion system. in x. citri subsp. citri, as in other plant pathogens, the hrp cluster encodes the type iii protein secretion system and is regulated by the transcription factors hrpg and hrpx. hrpg belongs to the ompr family's response regulator of envz/ompr two-component signal transduction system. here, we show that the arginine 210 residue is crucial for ...201525961560
what makes xanthomonas albilineans unique amongst xanthomonads?xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. compared to other species of xanthomonas, x. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy. its genome, which has experienced significant erosion, has unique genomic features. it lacks two loci required for pathogenicity in other plant pathogenic species of xanthomonas: the xanthan gum biosynthesis and the hrp-t3ss (hypersensitive response and pathogenicity-type three secretion system) gene c ...201525964795
xylan utilization regulon in xanthomonas citri pv. citri strain 306: gene expression and utilization of oligoxylosides.xanthomonas citri pv. citri strain 306 (xcc306), a causative agent of citrus canker, produces endoxylanases that catalyze the depolymerization of cell wall-associated xylans. in the sequenced genomes of all plant-pathogenic xanthomonads, genes encoding xylanolytic enzymes are clustered in three adjacent operons. in xcc306, these consecutive operons contain genes encoding the glycoside hydrolase family 10 (gh10) endoxylanases xyn10a and xyn10c, the agu67 gene, encoding a gh67 α-glucuronidase (agu ...201525595763
comparative genomics of 43 strains of xanthomonas citri pv. citri reveals the evolutionary events giving rise to pathotypes with different host ranges.the identification of factors involved in the host range definition and evolution is a pivotal challenge in the goal to predict and prevent the emergence of plant bacterial disease. to trace the evolution and find molecular differences between three pathotypes of xanthomonas citri pv. citri that may explain their distinctive host ranges, 42 strains of x. citri pv. citri and one outgroup strain, xanthomonas citri pv. bilvae were sequenced and compared.201526699528
reference gene selection for normalization of rt-qpcr gene expression data from actinidia deliciosa leaves infected with pseudomonas syringae pv. actinidiae.normalization of data, by choosing the appropriate reference genes (rgs), is fundamental for obtaining reliable results in reverse transcription-quantitative pcr (rt-qpcr). in this study, we assessed actinidia deliciosa leaves inoculated with two doses of pseudomonas syringae pv. actinidiae during a period of 13 days for the expression profile of nine candidate rgs. their expression stability was calculated using four algorithms: genorm, normfinder, bestkeeper and the deltact method. glyceraldeh ...201526581656
differential roles of two homologous cyclin-dependent kinase inhibitor genes in regulating cell cycle and innate immunity in arabidopsis.precise cell-cycle control is critical for plant development and responses to pathogen invasion. two homologous cyclin-dependent kinase inhibitor genes, siamese (sim) and sim-related 1 (smr1), were recently shown to regulate arabidopsis (arabidopsis thaliana) defense based on phenotypes conferred by a sim smr1 double mutant. however, whether these two genes play differential roles in cell-cycle and defense control is unknown. in this report, we show that while acting synergistically to promote e ...201526561564
differential roles of two homologous cyclin-dependent kinase inhibitor genes in regulating cell cycle and innate immunity in arabidopsis.precise cell-cycle control is critical for plant development and responses to pathogen invasion. two homologous cyclin-dependent kinase inhibitor genes, siamese (sim) and sim-related 1 (smr1), were recently shown to regulate arabidopsis (arabidopsis thaliana) defense based on phenotypes conferred by a sim smr1 double mutant. however, whether these two genes play differential roles in cell-cycle and defense control is unknown. in this report, we show that while acting synergistically to promote e ...201526561564
genome-wide identification and validation of reference genes in infected tomato leaves for quantitative rt-pcr analyses.the gram-negative bacterium xanthomonas campestris pv. vesicatoria (xcv) causes bacterial spot disease of pepper and tomato by direct translocation of type iii effector proteins into the plant cell cytosol. once in the plant cell the effectors interfere with host cell processes and manipulate the plant transcriptome. quantitative rt-pcr (qrt-pcr) is usually the method of choice to analyze transcriptional changes of selected plant genes. reliable results depend, however, on measuring stably expre ...201526313760
bioinformatics analysis of the complete genome sequence of the mango tree pathogen pseudomonas syringae pv. syringae umaf0158 reveals traits relevant to virulence and epiphytic lifestyle.the genome sequence of more than 100 pseudomonas syringae strains has been sequenced to date; however only few of them have been fully assembled, including p. syringae pv. syringae b728a. different strains of pv. syringae cause different diseases and have different host specificities; so, umaf0158 is a p. syringae pv. syringae strain related to b728a but instead of being a bean pathogen it causes apical necrosis of mango trees, and the two strains belong to different phylotypes of pv.syringae an ...201526313942
xanthomonas campestris cell-cell signalling molecule dsf (diffusible signal factor) elicits innate immunity in plants and is suppressed by the exopolysaccharide xanthan.several secreted and surface-associated conserved microbial molecules are recognized by the host to mount the defence response. one such evolutionarily well-conserved bacterial process is the production of cell-cell signalling molecules which regulate production of multiple virulence functions by a process known as quorum sensing. here it is shown that a bacterial fatty acid cell-cell signalling molecule, dsf (diffusible signal factor), elicits innate immunity in plants. the dsf family of signal ...201526248667
the sulfur/sulfonates transport systems in xanthomonas citri pv. citri.the xanthomonas citri pv. citri (x. citri) is a phytopathogenic bacterium that infects different species of citrus plants where it causes canker disease. the adaptation to different habitats is related to the ability of the cells to metabolize and to assimilate diverse compounds, including sulfur, an essential element for all organisms. in escherichia coli, the necessary sulfur can be obtained by a set of proteins whose genes belong to the cys regulon. although the cys regulon proteins and their ...201526169280
small rnas in plants: recent development and application for crop improvement.the phenomenon of rna interference (rnai) which involves sequence-specific gene regulation by small non-coding rnas, i.e., small interfering rna (sirna) and microrna (mirna) has emerged as one of most powerful approaches for crop improvement. rnai based on sirna is one of the widely used tools of reverse genetics which aid in revealing gene functions in many species. this technology has been extensively applied to alter the gene expression in plants with an aim to achieve desirable traits. rnai ...201525883599
ecological genomics in xanthomonas: the nature of genetic adaptation with homologous recombination and host shifts.comparative genomics provides insights into the diversification of bacterial species. bacterial speciation usually takes place with lasting homologous recombination, which not only acts as a cohering force between diverging lineages but brings advantageous alleles favored by natural selection, and results in ecologically distinct species, e.g., frequent host shift in xanthomonas pathogenic to various plants.201525879893
a tale of transposition: tn3-like transposons play a major role in the spread of pathogenicity determinants of xanthomonas citri and other xanthomonads.members of the genus xanthomonas are among the most important phytopathogens. a key feature of xanthomonas pathogenesis is the translocation of type iii secretion system (t3ss) effector proteins (t3ses) into the plant target cells via a t3ss. several t3ses and a murein lytic transglycosylase gene (mlt, required for citrus canker symptoms) are found associated with three transposition-related genes in xanthomonas citri plasmid pxac64. these are flanked by short inverted repeats (irs). the region ...201525691597
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