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Sheng Wu Gong Cheng Xue Bao = Chinese... Aug 2022(Ashby) Downson is a quarantine pest for importing plants to China that causes leaf scald bacterial disease on sugarcane. . produces a potent phytotoxin/antibiotic... (Review)
Review
(Ashby) Downson is a quarantine pest for importing plants to China that causes leaf scald bacterial disease on sugarcane. . produces a potent phytotoxin/antibiotic called albicidin. As a pathogenic factor, albicidin causes typical white leaf stripes by inhibiting plastid DNA gyrase and disturbing chloroplast differentiation. Meanwhile, the antibacterial activity of albicidin gives . a competitive advantage against rival bacteria during their colonization. Furthermore, albicidin has a rapid bactericidal activity against a variety of Gram-positive and Gram-negative pathogenic bacteria of human species at nanomolar concentrations, making it a potential antimicrobial drug for clinical application. This article reviews the advances of albicidin from the aspects of its molecular structure, traditional extraction methods, mechanism of action, biosynthetic genes and processes, chemical synthesis method and improvement, in order to provide insights into the prevention and treatment of the sugarcane leaf scald disease, and the development of new antibiotics.
Topics: Anti-Bacterial Agents; China; Humans; Organic Chemicals; Xanthomonas
PubMed: 36002407
DOI: 10.13345/j.cjb.210832 -
International Journal of Molecular... Jan 2022Executor () genes comprise a new type of plant resistance () genes, identified from host- interactions. The -secreted transcription activation-like effectors (TALEs)... (Review)
Review
Executor () genes comprise a new type of plant resistance () genes, identified from host- interactions. The -secreted transcription activation-like effectors (TALEs) usually function as major virulence factors, which activate the expression of the so-called "susceptibility" () genes for disease development. This activation is achieved via the binding of the TALEs to the effector-binding element (EBE) in the gene promoter. However, host plants have evolved EBEs in the promoters of some otherwise silent genes, whose expression directly causes a host cell death that is characterized by a hypersensitive response (HR). Such genes are called genes because they trap the pathogen TALEs in order to activate expression, and the resulting HR prevents pathogen growth and disease development. Currently, deploying gene resistance is becoming a major component in disease resistance breeding, especially for rice bacterial blight resistance. Currently, the biochemical mechanisms, or the working pathways of the E proteins, are still fuzzy. There is no significant nucleotide sequence homology among genes, although E proteins share some structural motifs that are probably associated with the signal transduction in the effector-triggered immunity. Here, we summarize the current knowledge regarding TALE-type avirulence proteins, gene activation, the E protein structural traits, and the classification of genes, in order to sharpen our understanding of the plant genes.
Topics: Bacterial Proteins; Disease Resistance; Gene Expression Regulation, Plant; Immunity, Innate; Plant Proteins; Plants; Promoter Regions, Genetic; Transcription Activator-Like Effectors; Xanthomonas
PubMed: 35163443
DOI: 10.3390/ijms23031524 -
Frontiers in Cellular and Infection... 2023
Topics: Xanthomonas; Plant Diseases; Biological Control Agents
PubMed: 37662017
DOI: 10.3389/fcimb.2023.1270750 -
Applied and Environmental Microbiology Nov 2022The physiology of plant hosts can be dramatically altered by phytopathogens. Xanthomonas hortorum pv. gardneri is one such pathogen that creates an aqueous niche within...
The physiology of plant hosts can be dramatically altered by phytopathogens. Xanthomonas hortorum pv. gardneri is one such pathogen that creates an aqueous niche within the leaf apoplast by manipulating the plant via the transcription activator-like effector AvrHah1. Simultaneous immigration of pv. gardneri and Salmonella enterica to healthy tomato leaves results in increased survival of S. enterica as infection progresses. However, the fate of S. enterica following arrival on actively infected leaves has not been examined. We hypothesized that the water soaking caused by pv. gardneri could facilitate the ingression of S. enterica into the apoplast and that this environment would be conducive for growth. We found that an altered apoplast, abiotically water congested or infected and water-soaked, enabled surface S. enterica to passively localize to the protective apoplast and facilitated migration of S. enterica to distal sites within the aqueous apoplast. contributed to the protection and migration of S. enterica early in pv. gardneri infection. -infected apoplasts facilitated prolonged survival and promoted S. enterica replication compared to the case with healthy apoplasts. Access to an aqueous apoplast in general protects S. enterica from immediate exposure to irradiation, whereas the altered environment created by infection provides growth-conducive conditions for S. enterica. Overall, we have characterized an ecological relationship in which host infection converts an unreachable niche to a habitable environment. Bacterial spot disease caused by species devastates tomato production worldwide. Salmonellosis outbreaks from consumption of raw produce have been linked to the arrival of Salmonella enterica on crop plants in the field via contaminated irrigation water. Considering that is difficult to eradicate, it is highly likely that S. enterica arrives on leaves precolonized by with infection under way. Our study demonstrated that infection and disease fundamentally alter the leaf, resulting in redistribution and change in abundance of a phyllosphere bacterial member. These findings contribute to our understanding of how S. enterica manages to persist on leaf tissue despite lacking the ability to liberate nutrients from plant cells. More broadly, this study reveals a mechanism by which physiochemical changes to a host environment imposed by a plant pathogen can convert an uninhabitable leaf environment into a hospitable niche for selected epiphytic microbes.
Topics: Salmonella enterica; Xanthomonas; Solanum lycopersicum; Plants; Water; Plant Diseases
PubMed: 36314834
DOI: 10.1128/aem.01330-22 -
Microbiology Spectrum Feb 2022In summer 2019, widespread occurrence of crown gall disease caused by spp. was observed on commercially grown ornamental plants in southern Iran. Beside agrobacteria,...
In summer 2019, widespread occurrence of crown gall disease caused by spp. was observed on commercially grown ornamental plants in southern Iran. Beside agrobacteria, pale yellow-pigmented Gram-negative strains resembling the members of were also associated with crown gall tissues on weeping fig (Ficus benjamina) and sp. plants. The purpose of the present study was to characterize the crown gall-associated strains using plant inoculation assays, molecular-phylogenetic analyses, and comparative genomics approaches. Pathogenicity tests showed that the strains did not induce disease symptoms on their host of isolation. However, the strains induced hypersensitive reaction on tobacco, geranium, melon, squash, and tomato leaves via leaf infiltration. Multilocus sequence analysis suggested that the strains belong to clade IA of , phylogenetically close to Xanthomonas translucens, X. theicola, and X. hyacinthi. Average nucleotide identity and digital DNA-DNA hybridization values between the whole-genome sequences of the strains isolated in this study and reference strains are far below the accepted thresholds for the definition of prokaryotic species, signifying that these strains could be defined as two new species within clade IA of . Comparative genomics showed that the strains isolated from crown gall tissues are genetically distinct from , as almost all the type III secretion system genes and type III effectors are lacking in the former group. The data obtained in this study provide novel insight into the breadth of genetic diversity of crown gall-associated bacteria and pave the way for research on gall-associated -plant interactions. Tumorigenic agrobacteria-members of the bacterial family -cause crown gall and hairy root diseases on a broad range of plant species. These bacteria are responsible for economic losses in nurseries of important fruit trees and ornamental plants. The microclimate of crown gall and their accompanying microorganisms has rarely been studied for the microbial diversity and population dynamics of gall-associated bacteria. Here, we employed a series of biochemical tests, pathogenicity assays, and molecular-phylogenetic analyses, supplemented with comparative genomics, to elucidate the biological features, taxonomic position, and genomic repertories of five crown gall-associated strains isolated from weeping fig and sp. plants in Iran. The strains investigated in this study induced hypersensitive reactions (HR) on geranium, melon, squash, tobacco, and tomato leaves, while they were nonpathogenic on their host of isolation. Phylogenetic analyses and whole-genome-sequence-based average nucleotide identity (ANI)/digital DNA-DNA hybridization (dDDH) calculations suggested that the strains isolated from crown gall tissues belong to two taxonomically unique clades closely related to the clade IA species of the genus, i.e., , , and .
Topics: Amaranthus; Bacterial Proteins; Ficus; Genetic Variation; Genome, Bacterial; Genomics; Phenotype; Phylogeny; Plant Roots; Plant Tumors; Xanthomonas
PubMed: 35107322
DOI: 10.1128/spectrum.00577-21 -
FEMS Microbiology Reviews Mar 2010Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide.... (Review)
Review
Plant pathogenic bacteria of the genus Xanthomonas cause a variety of diseases in economically important monocotyledonous and dicotyledonous crop plants worldwide. Successful infection and bacterial multiplication in the host tissue often depend on the virulence factors secreted including adhesins, polysaccharides, LPS and degradative enzymes. One of the key pathogenicity factors is the type III secretion system, which injects effector proteins into the host cell cytosol to manipulate plant cellular processes such as basal defense to the benefit of the pathogen. The coordinated expression of bacterial virulence factors is orchestrated by quorum-sensing pathways, multiple two-component systems and transcriptional regulators such as Clp, Zur, FhrR, HrpX and HpaR. Furthermore, virulence gene expression is post-transcriptionally controlled by the RNA-binding protein RsmA. In this review, we summarize the current knowledge on the infection strategies and regulatory networks controlling secreted virulence factors from Xanthomonas species.
Topics: Bacterial Proteins; Gene Expression Regulation, Bacterial; Membrane Transport Proteins; Plant Diseases; Signal Transduction; Virulence Factors; Xanthomonas
PubMed: 19925633
DOI: 10.1111/j.1574-6976.2009.00192.x -
FEMS Microbiology Reviews Jan 2020Xanthomonas is a well-studied genus of bacterial plant pathogens whose members cause a variety of diseases in economically important crops worldwide. Genomic and... (Review)
Review
Xanthomonas is a well-studied genus of bacterial plant pathogens whose members cause a variety of diseases in economically important crops worldwide. Genomic and functional studies of these phytopathogens have provided significant understanding of microbial-host interactions, bacterial virulence and host adaptation mechanisms including microbial ecology and epidemiology. In addition, several strains of Xanthomonas are important as producers of the extracellular polysaccharide, xanthan, used in the food and pharmaceutical industries. This polymer has also been implicated in several phases of the bacterial disease cycle. In this review, we summarise the current knowledge on the infection strategies and regulatory networks controlling virulence and adaptation mechanisms from Xanthomonas species and discuss the novel opportunities that this body of work has provided for disease control and plant health.
Topics: Adaptation, Physiological; Genome, Bacterial; Host-Pathogen Interactions; Plant Diseases; Plants; Virulence; Xanthomonas
PubMed: 31578554
DOI: 10.1093/femsre/fuz024 -
Brazilian Journal of Microbiology :... Sep 2020Iron is a vital nutrient to bacteria, not only in the basal metabolism but also for virulent species in infection and pathogenicity at their hosts. Despite its... (Review)
Review
Iron is a vital nutrient to bacteria, not only in the basal metabolism but also for virulent species in infection and pathogenicity at their hosts. Despite its relevance, the role of iron in Xanthomonas citri infection, the etiological agent of citrus canker disease, is poorly understood in contrast to other pathogens, including other members of the Xanthomonas genus. In this review, we present iron assimilation pathways in X. citri including the ones for siderophore production and siderophore-iron assimilation, proven to be key factors to virulence in many organisms like Escherichia coli and Xanthomonas campestris. Based on classical iron-related proteins previously characterized in E. coli, Pseudomonas aeruginosa, and also Xanthomonadaceae, we identified orthologs in X. citri and evaluated their sequences, structural characteristics such as functional motifs, and residues that support their putative functions. Among the identified proteins are TonB-dependent receptors, periplasmic-binding proteins, active transporters, efflux pumps, and cytoplasmic enzymes. The role of each protein for the bacterium was analyzed and complemented with proteomics data previously reported. The global view of different aspects of iron regulation and nutrition in X. citri virulence and pathogenesis may help guide future investigations aiming the development of new drug targets against this important phytopathogen.
Topics: Bacterial Proteins; Citrus; Iron; Plant Diseases; Virulence; Xanthomonas
PubMed: 31848911
DOI: 10.1007/s42770-019-00207-x -
Molecular Plant Pathology Nov 2009A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence... (Review)
Review
A review of type III effectors (T3 effectors) from strains of Xanthomonas reveals a growing list of candidate and known effectors based on functional assays and sequence and structural similarity searches of genomic data. We propose that the effectors and suspected effectors should be distributed into 39 so-called Xop groups reflecting sequence similarity. Some groups have structural motifs for putative enzymatic functions, and recent studies have provided considerable insight into the interaction with host factors in their function as mediators of virulence and elicitors of resistance for a few specific T3 effectors. Many groups are related to T3 effectors of plant and animal pathogenic bacteria, and several groups appear to have been exploited primarily by Xanthomonas species based on available data. At the same time, a relatively large number of candidate effectors remain to be examined in more detail with regard to their function within host cells.
Topics: Bacterial Proteins; Gene Expression Regulation, Bacterial; Host-Pathogen Interactions; Plant Diseases; Xanthomonas
PubMed: 19849782
DOI: 10.1111/j.1364-3703.2009.00590.x -
Applied and Environmental Microbiology May 2017Citrus canker, caused by pv. citri, is a serious disease of citrus plants worldwide. Earlier phylogenetic studies using housekeeping genes revealed that pv. citri is...
Citrus canker, caused by pv. citri, is a serious disease of citrus plants worldwide. Earlier phylogenetic studies using housekeeping genes revealed that pv. citri is related to many other pathovars, which can be collectively referred as pathovars (XCPs). From the present study, we report the genome sequences of 18 XCPs and compared them with four XCPs available in the public domain. In a tree based on phylogenomic marker genes, all the XCPs form a monophyletic cluster, suggesting their origin from a common ancestor. Phylogenomic analysis using the type strain further established that all the XCPs belong to one species. Clonal analysis of the core genome revealed the presence of two major lineages within this monophyletic cluster consisting of some clonal variants. Incidentally, the majority of these XCPs were first noticed in India, corroborating their clonal relationship and their common origin. Comparative analysis revealed an open pan-genome and the role of interstrain genomic flux of these XCPs since their diversification from a common ancestor. Even though there are wide variations in type III gene effectomes, we identified three core effectors which can be valuable in resistance-breeding programs. Overall, genomic examination of ecological relatives allowed us to dissect the tremendous genomic potential of species to rapidly evolve into specialized strains infecting diverse crop plants. Host specialization is one of the characteristic features of highly evolved pathogens such as the group of phytopathogenic bacteria. Since the hosts involve staple crops and economically important fruits such as citrus, detailed understanding of the diversity and evolution of such strains infecting diverse plants is important for quarantine purposes. In the present study, we carried out genomic investigation of members of a phylogenetically and ecologically defined group of strains pathogenic to diverse plants, including citrus. This group includes the oldest pathovars and also recently emerged pathovars in a particular country where they are endemic. Our high-throughput genomic study has provided novel insights into the evolution of a unique lineage consisting of serious pathogens and their ecological relatives, suggesting the nature, scope, and pattern of rapid and recent diversification. Further, from the level of species to that of clonal variants, the study revealed interesting genomic patterns in diversification of a lineage and perhaps will inspire careful study of the host range of the included pathovars.
Topics: Citrus; Cluster Analysis; DNA, Bacterial; Genetic Variation; Genome, Bacterial; Genotype; India; Phylogeny; Plant Diseases; Sequence Analysis, DNA; Sequence Homology; Xanthomonas
PubMed: 28258140
DOI: 10.1128/AEM.02993-16