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Sample records for blight pathogen erwinia

  1. Complete genome sequence of Japanese erwinia strain ejp617, a bacterial shoot blight pathogen of pear.

    Science.gov (United States)

    Park, Duck Hwan; Thapa, Shree Prasad; Choi, Beom-Soon; Kim, Won-Sik; Hur, Jang Hyun; Cho, Jun Mo; Lim, Jong-Sung; Choi, Ik-Young; Lim, Chun Keun

    2011-01-01

    The Japanese Erwinia strain Ejp617 is a plant pathogen that causes bacterial shoot blight of pear in Japan. Here, we report the complete genome sequence of strain Ejp617 isolated from Nashi pears in Japan to provide further valuable insight among related Erwinia species.

  2. [Erwinia amylovora--the fire blight pathogen of trees in Ukraine].

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    Iakovleva, L M; Moroz, S N; Shcherbina, T N; Ogorodnik, L E; Gvozdiak, R I; Patyka, V F

    2014-01-01

    Niduses of fire blight of fruit and ornamental trees have been found in the Kyiv and Vinnitsa regions of Ukraine. Pathogen Erwinia amylovora was isolated between April and October. The pathogen was often accompanied by bacteria Pseudomonas syringae pv. syringae. Artificial infection with a mixture of bacteria E. amylovora and P. syringae pv. syringae accelerates and enhances the disease process in the laboratory.

  3. The fire blight pathogen Erwinia amylovora requires the rpoN gene for pathogenicity in apple.

    Science.gov (United States)

    Ramos, Laura S; Lehman, Brian L; Sinn, Judith P; Pfeufer, Emily E; Halbrendt, Noemi O; McNellis, Timothy W

    2013-10-01

    RpoN is a σ(54) factor regulating essential virulence gene expression in several plant pathogenic bacteria, including Pseudomonas syringae and Pectobacterium carotovorum. In this study, we found that mutation of rpoN in the fire blight pathogen Erwinia amylovora caused a nonpathogenic phenotype. The E. amylovora rpoN Tn5 transposon mutant rpoN1250::Tn5 did not cause fire blight disease symptoms on shoots of mature apple trees. In detached immature apple fruits, the rpoN1250::Tn5 mutant failed to cause fire blight disease symptoms and grew to population levels 12 orders of magnitude lower than the wild-type. In addition, the rpoN1250::Tn5 mutant failed to elicit a hypersensitive response when infiltrated into nonhost tobacco plant leaves, and rpoN1250::Tn5 cells failed to express HrpN protein when grown in hrp (hypersensitive response and pathogenicity)-inducing liquid medium. A plasmid-borne copy of the wild-type rpoN gene complemented all the rpoN1250::Tn5 mutant phenotypes tested. The rpoN1250::Tn5 mutant was prototrophic on minimal solid and liquid media, indicating that the rpoN1250::Tn5 nonpathogenic phenotype was not caused by a defect in basic metabolism or growth. This study provides clear genetic evidence that rpoN is an essential virulence gene of E. amylovora, suggesting that rpoN has the same function in E. amylovora as in P. syringae and Pe. carotovorum.

  4. Complete genome sequence of the fire blight pathogen Erwinia amylovora CFBP 1430 and comparison to other Erwinia spp.

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    Smits, Theo H M; Rezzonico, Fabio; Kamber, Tim; Blom, Jochen; Goesmann, Alexander; Frey, Jürg E; Duffy, Brion

    2010-04-01

    Fire blight, caused by the enterobacterium Erwinia amylovora, is a devastating disease of rosaceous plants that has global economic importance for apple and pear production and trade. The complete genome of E. amylovora CFBP 1430 was sequenced, annotated, and compared with the genomes of other Erwinia spp. Several singleton and shared features of the E. amylovora CFBP 1430 genome were identified that offer a first view into evolutionary aspects within the genus Erwinia. Comparative genomics identified or clarified virulence and fitness determinants and secretion systems. Novel insights revealed in the genome of E. amylovora CFBP 1430 hold potential for exploitation to improve the design of more effective fire blight control strategies.

  5. Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission.

    Directory of Open Access Journals (Sweden)

    Mónica Ordax

    Full Text Available Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly Ceratitis capitata (Diptera: Tephritidae, one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

  6. Medfly Ceratitis capitata as Potential Vector for Fire Blight Pathogen Erwinia amylovora: Survival and Transmission.

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    Ordax, Mónica; Piquer-Salcedo, Jaime E; Santander, Ricardo D; Sabater-Muñoz, Beatriz; Biosca, Elena G; López, María M; Marco-Noales, Ester

    2015-01-01

    Monitoring the ability of bacterial plant pathogens to survive in insects is required for elucidating unknown aspects of their epidemiology and for designing appropriate control strategies. Erwinia amylovora is a plant pathogenic bacterium that causes fire blight, a devastating disease in apple and pear commercial orchards. Studies on fire blight spread by insects have mainly focused on pollinating agents, such as honeybees. However, the Mediterranean fruit fly (medfly) Ceratitis capitata (Diptera: Tephritidae), one of the most damaging fruit pests worldwide, is also common in pome fruit orchards. The main objective of the study was to investigate whether E. amylovora can survive and be transmitted by the medfly. Our experimental results show: i) E. amylovora can survive for at least 8 days inside the digestive tract of the medfly and until 28 days on its external surface, and ii) medflies are able to transmit the bacteria from inoculated apples to both detached shoots and pear plants, being the pathogen recovered from lesions in both cases. This is the first report on E. amylovora internalization and survival in/on C. capitata, as well as the experimental transmission of the fire blight pathogen by this insect. Our results suggest that medfly can act as a potential vector for E. amylovora, and expand our knowledge on the possible role of these and other insects in its life cycle.

  7. Pathogenicity and infection strategies of the fire blight pathogen Erwinia amylovora in Rosaceae: state of the art.

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    Vrancken, K; Holtappels, M; Schoofs, H; Deckers, T; Valcke, R

    2013-05-01

    Plants are host to a large amount of pathogenic bacteria. Fire blight, caused by the bacterium Erwinia amylovora, is an important disease in Rosaceae. Pathogenicity of E. amylovora is greatly influenced by the production of exopolysaccharides, such as amylovoran, and the use of the type III secretion system, which enables bacteria to penetrate host tissue and cause disease. When infection takes place, plants have to rely on the ability of each cell to recognize the pathogen and the signals emanating from the infection site in order to generate several defence mechanisms. These mechanisms consist of physical barriers and the production of antimicrobial components, both in a preformed and an inducible manner. Inducible defence responses are activated upon the recognition of elicitor molecules by plant cell receptors, either derived from invading micro-organisms or from pathogen-induced degradation of plant tissue. This recognition event triggers a signal transduction cascade, leading to a range of defence responses [reactive oxygen species (ROS), plant hormones, secondary metabolites, …] and redeployment of cellular energy in a fast, efficient and multiresponsive manner, which prevents further pathogen ingress. This review highlights the research that has been performed during recent years regarding this specific plant-pathogen interaction between Erwinia amylovora and Rosaceae, with a special emphasis on the pathogenicity and the infection strategy of E. amylovora and the possible defence mechanisms of the plant against this disease.

  8. Complete genome sequence of the fire blight pathogen Erwinia pyrifoliae DSM 12163T and comparative genomic insights into plant pathogenicity

    Directory of Open Access Journals (Sweden)

    Frey Jürg E

    2010-01-01

    Full Text Available Abstract Background Erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on Asian (Nashi pear and is geographically restricted to Eastern Asia. Relatively little is known about its genetics compared to the closely related main fire blight pathogen E. amylovora. Results The genome of the type strain of E. pyrifoliae strain DSM 12163T, was sequenced using both 454 and Solexa pyrosequencing and annotated. The genome contains a circular chromosome of 4.026 Mb and four small plasmids. Based on their respective role in virulence in E. amylovora or related organisms, we identified several putative virulence factors, including type III and type VI secretion systems and their effectors, flagellar genes, sorbitol metabolism, iron uptake determinants, and quorum-sensing components. A deletion in the rpoS gene covering the most conserved region of the protein was identified which may contribute to the difference in virulence/host-range compared to E. amylovora. Comparative genomics with the pome fruit epiphyte Erwinia tasmaniensis Et1/99 showed that both species are overall highly similar, although specific differences were identified, for example the presence of some phage gene-containing regions and a high number of putative genomic islands containing transposases in the E. pyrifoliae DSM 12163T genome. Conclusions The E. pyrifoliae genome is an important addition to the published genome of E. tasmaniensis and the unfinished genome of E. amylovora providing a foundation for re-sequencing additional strains that may shed light on the evolution of the host-range and virulence/pathogenicity of this important group of plant-associated bacteria.

  9. Fire blight disease reactome: RNA-seq transcriptional profile of apple host plant defense responses to Erwinia amylovora pathogen infection.

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    Kamber, Tim; Buchmann, Jan P; Pothier, Joël F; Smits, Theo H M; Wicker, Thomas; Duffy, Brion

    2016-02-17

    The molecular basis of resistance and susceptibility of host plants to fire blight, a major disease threat to pome fruit production globally, is largely unknown. RNA-sequencing data from challenged and mock-inoculated flowers were analyzed to assess the susceptible response of apple to the fire blight pathogen Erwinia amylovora. In presence of the pathogen 1,080 transcripts were differentially expressed at 48 h post inoculation. These included putative disease resistance, stress, pathogen related, general metabolic, and phytohormone related genes. Reads, mapped to regions on the apple genome where no genes were assigned, were used to identify potential novel genes and open reading frames. To identify transcripts specifically expressed in response to E. amylovora, RT-PCRs were conducted and compared to the expression patterns of the fire blight biocontrol agent Pantoea vagans strain C9-1, another apple pathogen Pseudomonas syringae pv. papulans, and mock inoculated apple flowers. This led to the identification of a peroxidase superfamily gene that was lower expressed in response to E. amylovora suggesting a potential role in the susceptibility response. Overall, this study provides the first transcriptional profile by RNA-seq of the host plant during fire blight disease and insights into the response of susceptible apple plants to E. amylovora.

  10. Conventional and real-time PCRs for detection of Erwinia piriflorinigrans allow its distinction from the fire blight pathogen, Erwinia amylovora.

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    Barbé, Silvia; Bertolini, Edson; Roselló, Montserrat; Llop, Pablo; López, María M

    2014-04-01

    Erwinia piriflorinigrans is a new pathogenic species of the bacterial genus Erwinia that has been described recently in Spain. Accurate detection and identification of E. piriflorinigrans are challenging because its symptoms on pear blossoms are similar to those caused by Erwinia amylovora, the causal agent of fire blight. Moreover, these two species share phenotypic and molecular characteristics. Two specific and sensitive conventional and real-time PCR protocols were developed to identify and detect E. piriflorinigrans and to differentiate it from E. amylovora and other species of this genus. These protocols were based on sequences from plasmid pEPIR37, which is present in all strains of E. piriflorinigrans analyzed. After the stability of the plasmid was demonstrated, the specificities of the protocols were confirmed by the amplification of all E. piriflorinigrans strains tested, whereas 304 closely related pathogenic and nonpathogenic Erwinia strains and microbiota from pear trees were not amplified. In sensitivity assays, 10(3) cells/ml extract were detected in spiked plant material by conventional or real-time PCR, and 10(2) cells/ml were detected in DNA extracted from spiked plant material by real-time PCR. The protocols developed here succeeded in detecting E. piriflorinigrans in 102 out of 564 symptomatic and asymptomatic naturally infected pear samples (flowers, cortex stem tissue, leaves, shoots, and fruitlets), in necrotic Pyracantha sp. blossoms, and in necrotic pear and apple tissues infected with both E. amylovora and E. piriflorinigrans. Therefore, these new tools can be used in epidemiological studies that will enhance our understanding of the life cycle of E. piriflorinigrans in different hosts and plant tissues and its interaction with E. amylovora.

  11. The outer membrane protein TolC is required for phytoalexin resistance and virulence of the fire blight pathogen Erwinia amylovora

    OpenAIRE

    2009-01-01

    Summary Erwinia amylovora causes fire blight on several plant species such as apple and pear, which produce diverse phytoalexins as defence mechanisms. An evolutionary successful pathogen thus must develop resistance mechanisms towards these toxic compounds. The E. amylovora outer membrane protein, TolC, might mediate phytoalexin resistance through its interaction with the multidrug efflux pump, AcrAB. To prove this, a tolC mutant and an acrB/tolC double mutant were constructed. The minimal i...

  12. Genetic characterization of the HrpL regulon of the fire blight pathogen Erwinia amylovora reveals novel virulence factors.

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    McNally, R Ryan; Toth, Ian K; Cock, Peter J A; Pritchard, Leighton; Hedley, Pete E; Morris, Jenny A; Zhao, Youfu; Sundin, George W

    2012-02-01

    The bacterial pathogen Erwinia amylovora is the causal agent of fire blight, an economically significant disease of apple and pear. Disease initiation by E. amylovora requires the translocation of effector proteins into host cells via the hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS). The alternative sigma factor HrpL positively regulates the transcription of structural and translocated components of the T3SS via hrp promoter elements. To characterize genome-wide HrpL-dependent gene expression in E. amylovora Ea1189, wild-type and Ea1189ΔhrpL strains were cultured in hrp-inducing minimal medium, and total RNA was compared using a custom microarray designed to represent the annotated genes of E. amylovora ATCC 49946. The results revealed 24 genes differentially regulated in Ea1189ΔhrpL relative to Ea1189 with fold-change expression ratios greater than 1.5; of these, 19 genes exhibited decreased transcript abundance and five genes showed increased transcript abundance relative to Ea1189. To expand our understanding of the HrpL regulon and to elucidate direct versus indirect HrpL-mediated effects on gene expression, the genome of E. amylovora ATCC 49946 was examined in silico using a hidden Markov model assembled from known Erwinia spp. hrp promoters. This technique identified 15 putative type III novel hrp promoters, seven of which were validated with quantitative polymerase chain reaction based on expression analyses. It was found that HrpL-regulated genes encode all known components of the hrp T3SS, as well as five putative type III effectors. Eight genes displayed apparent indirect HrpL regulation, suggesting that the HrpL regulon is connected to downstream signalling networks. The construction of deletion mutants of three novel HrpL-regulated genes resulted in the identification of additional virulence factors as well as mutants displaying abnormal motility and biofilm phenotypes.

  13. Autoinducer-2 of the fire blight pathogen Erwinia amylovora and other plant-associated bacteria.

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    Mohammadi, Mojtaba; Geider, Klaus

    2007-01-01

    Autoinducers are important for cellular communication of bacteria. The luxS gene has a central role in the synthesis of autoinducer-2 (AI-2). The gene was identified in a shotgun library of Erwinia amylovora and primers designed for PCR amplification from bacterial DNA. Supernatants of several Erwinia amylovora strains were assayed for AI-2 activity with a Vibrio harveyi mutant and were positive. Many other plant-associated bacteria also showed AI-2 activity such as Erwinia pyrifoliae and Erwinia tasmaniensis. The luxS genes of several bacteria were cloned, sequenced, and complemented Escherichia coli strain DH5alpha and a Salmonella typhimurium mutant, both defective in luxS, for synthesis of AI-2. Assays to detect AI-2 activity in culture supernatants of several Pseudomonas syringae pathovars failed, which may indicate the absence of AI-2 or synthesis of another type. Several reporter strains did not detect synthesis of an acyl homoserine lactone (AHL, AI-1) by Erwinia amylovora, but confirmed AHL-synthesis for Erwinia carotovora ssp. atroseptica and Pantoea stewartii.

  14. Biology of the fire blight pathogen Erwinia amylovora in oligotrophic environments: survival responses and virulence

    OpenAIRE

    Delgado Santander, Ricardo

    2016-01-01

    Erwinia amylovora es una bacteria fitopatógena de la familia Enterobacteriaceae, responsable del fuego bacteriano de las rosáceas. Los efectos destructivos de este patógeno sobre frutos, flores y prácticamente todos los órganos de las plantas hospedadoras afectadas constituyen una amenaza importante para la producción de pera y manzana, y suponen graves pérdidas económicas anuales en todo el mundo. E. amylovora está clasificada como un organismo de cuarentena en la Unión Europea y en otros pa...

  15. Structure of amylovoran, the capsular exopolysaccharide from the fire blight pathogen Erwinia amylovora.

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    Nimtz, M; Mort, A; Domke, T; Wray, V; Zhang, Y; Qiu, F; Coplin, D; Geider, K

    1996-06-01

    The acidic exopolysaccharide (EPS) of Erwinia amylovora, amylovoran, was purified from culture supernatants of bacteria in minimal medium and cleaved chemically either by treatment with trifluoracetic acid or hydrofluoric acid, and enzymatically by digestion with depolymerase from E. amylovora phage phi-Ealh. Structural characterization of the resulting oligosaccharides was performed by a combination of mass spectrometric and NMR [one- and two-dimensional (1D and 2D)] spectroscopic techniques. A branched repeating unit with five monosaccharide residues and various substituents was determined: [sequence: see text] The terminal monosaccharide of the side branch, which bears a 4,6-bound pyruvate residue in the R-configuration, was found to be modified with 2-linked (26%), 3-linked (24%), 2-,3-linked (40%) O-acetyl groups, or these were absent (10%). An additional glucose residue is linked to approximately 10% of the core alpha-galactose of the repeating unit.

  16. Molecular and physiological properties of bacteriophages from North America and Germany affecting the fire blight pathogen Erwinia amylovora.

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    Müller, Ina; Lurz, Rudi; Kube, Michael; Quedenau, Claudia; Jelkmann, Wilhelm; Geider, Klaus

    2011-11-01

    For possible control of fire blight affecting apple and pear trees, we characterized Erwinia amylovora phages from North America and Germany. The genome size determined by electron microscopy (EM) was confirmed by sequence data and major coat proteins were identified from gel bands by mass spectroscopy. By their morphology from EM data, φEa1h and φEa100 were assigned to the Podoviridae and φEa104 and φEa116 to the Myoviridae. Host ranges were essentially confined to E. amylovora, strains of the species Erwinia pyrifoliae, E. billingiae and even Pantoea stewartii were partially sensitive. The phages φEa1h and φEa100 were dependent on the amylovoran capsule of E. amylovora, φEa104 and φEa116 were not. The Myoviridae efficiently lysed their hosts and protected apple flowers significantly better than the Podoviridae against E. amylovora and should be preferred in biocontrol experiments. We have also isolated and partially characterized E. amylovora phages from apple orchards in Germany. They belong to the Podoviridae or Myoviridae with a host range similar to the phages isolated in North America. In EM measurements, the genome sizes of the Podoviridae were smaller than the genomes of the Myoviridae from North America and from Germany, which differed from each other in corresponding nucleotide sequences.

  17. Diversity, evolution, and functionality of clustered regularly interspaced short palindromic repeat (CRISPR) regions in the fire blight pathogen Erwinia amylovora.

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    Rezzonico, Fabio; Smits, Theo H M; Duffy, Brion

    2011-06-01

    The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system confers acquired heritable immunity against mobile nucleic acid elements in prokaryotes, limiting phage infection and horizontal gene transfer of plasmids. In CRISPR arrays, characteristic repeats are interspersed with similarly sized nonrepetitive spacers derived from transmissible genetic elements and acquired when the cell is challenged with foreign DNA. New spacers are added sequentially and the number and type of CRISPR units can differ among strains, providing a record of phage/plasmid exposure within a species and giving a valuable typing tool. The aim of this work was to investigate CRISPR diversity in the highly homogeneous species Erwinia amylovora, the causal agent of fire blight. A total of 18 CRISPR genotypes were defined within a collection of 37 cosmopolitan strains. Strains from Spiraeoideae plants clustered in three major groups: groups II and III were composed exclusively of bacteria originating from the United States, whereas group I generally contained strains of more recent dissemination obtained in Europe, New Zealand, and the Middle East. Strains from Rosoideae and Indian hawthorn (Rhaphiolepis indica) clustered separately and displayed a higher intrinsic diversity than that of isolates from Spiraeoideae plants. Reciprocal exclusion was generally observed between plasmid content and cognate spacer sequences, supporting the role of the CRISPR/Cas system in protecting against foreign DNA elements. However, in several group III strains, retention of plasmid pEU30 is inconsistent with a functional CRISPR/Cas system.

  18. The phytoalexin-inducible multidrug efflux pump AcrAB contributes to virulence in the fire blight pathogen, Erwinia amylovora.

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    Burse, Antje; Weingart, Helge; Ullrich, Matthias S

    2004-01-01

    The enterobacterium Erwinia amylovora causes fire blight on members of the family Rosaceae, with economic importance on apple and pear. During pathogenesis, the bacterium is exposed to a variety of plant-borne antimicrobial compounds. In plants of Rosaceae, many constitutively synthesized isoflavonoids affecting microorganisms were identified. Bacterial multidrug efflux transporters which mediate resistance toward structurally unrelated compounds might confer tolerance to these phytoalexins. To prove this hypothesis, we cloned the acrAB locus from E. amylovora encoding a resistance nodulation division-type transport system. In Escherichia coli, AcrAB of E. amylovora conferred resistance to hydrophobic and amphiphilic toxins. An acrB-deficient E. amylovora mutant was impaired in virulence on apple rootstock MM 106. Furthermore, it was susceptible toward extracts of leaves of MM 106 as well as to the apple phytoalexins phloretin, naringenin, quercetin, and (+)-catechin. The expression of acrAB was determined using the promoterless reporter gene egfp. The acrAB operon was up-regulated in vitro by the addition of phloretin and naringenin. The promoter activity of acrR, encoding a regulatory protein involved in acrAB expression, was increased by naringenin. In planta, an induction of acrAB was proved by confocal laser scanning microscopy. Our results strongly suggest that the AcrAB transport system plays an important role as a protein complex required for virulence of E. amylovora in resistance toward apple phytoalexins and that it is required for successful colonization of a host plant.

  19. Characterization of the rcsB gene from Erwinia amylovora and its influence on exoploysaccharide synthesis and virulence of the fire blight pathogen.

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    Bereswill, S; Geider, K

    1997-02-01

    RcsB belongs to a family of positive regulators of exopolysaccharide synthesis in various enterobacteria. The rcsB gene of the fire blight pathogen Erwinia amylovora was cloned by PCR amplification with consensus primers, and its role in exopolysaccharide (EPS) synthesis was investigated. Its overexpression from high-copy-number plasmids stimulated the synthesis of the acidic EPS amylovoran and suppressed expression of the levan-forming enzyme levansucrase. Inactivation of rcsB by site-directed mutagenesis created mutants that were deficient in amylovoran synthesis and avirulent on host plants. In addition, a cosmid which complemented rcsB mutants was selected from a genomic library. The spontaneous E. amylovora mutant E8 has a similar phenotype and was complemented by the cloned rcsB gene. The rcsB region of strain E8 was also amplified by PCR, and the mutation was characterized as a nine-nucleotide deletion at the start of the rcsB gene. Nucleotide sequence analysis of the E. amylovora rcsB region and the predicted amino acid sequence of RcsB revealed extensive homology to rcsB and the encoded protein of other bacteria such as Escherichia coli and Erwinia stewartii. In all three organisms, rcsB is localized adjacent to the rcsC gene, which is transcribed in the opposite direction of rcsB. The E. amylovora rcsB gene has now been shown to strongly affect the formation of disease symptoms of a plant pathogen.

  20. Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora.

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    Santander, Ricardo D; Monte-Serrano, Mercedes; Rodríguez-Herva, José J; López-Solanilla, Emilia; Rodríguez-Palenzuela, Pablo; Biosca, Elena G

    2014-12-01

    Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits.

  1. The outer membrane protein TolC is required for phytoalexin resistance and virulence of the fire blight pathogen Erwinia amylovora.

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    Al-Karablieh, Nehaya; Weingart, Helge; Ullrich, Matthias S

    2009-07-01

    Erwinia amylovora causes fire blight on several plant species such as apple and pear, which produce diverse phytoalexins as defence mechanisms. An evolutionary successful pathogen thus must develop resistance mechanisms towards these toxic compounds. The E. amylovora outer membrane protein, TolC, might mediate phytoalexin resistance through its interaction with the multidrug efflux pump, AcrAB. To prove this, a tolC mutant and an acrB/tolC double mutant were constructed. The minimal inhibitory concentrations of diverse antimicrobials and phytoalexins were determined for these mutants and compared with that of a previously generated acrB mutant. The tolC and arcB/tolC mutants were considerably more susceptible than the wild type but showed similar levels as the acrB mutant. The results clearly indicated that neither TolC nor AcrAB significantly interacted with other transport systems during the efflux of the tested toxic compounds. Survival and virulence assays on inoculated apple plants showed that pathogenicity and the ability of E. amylovora to colonize plant tissue were equally impaired by mutations of tolC and acrB/tolC. Our results allowed the conclusion that TolC plays an important role as a virulence and fitness factor of E. amylovora by mediating resistance towards phytoalexins through its exclusive interaction with AcrAB.

  2. Discovery of plant phenolic compounds that act as type III secretion system inhibitors or inducers of the fire blight pathogen, Erwinia amylovora.

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    Khokhani, Devanshi; Zhang, Chengfang; Li, Yan; Wang, Qi; Zeng, Quan; Yamazaki, Akihiro; Hutchins, William; Zhou, Shan-Shan; Chen, Xin; Yang, Ching-Hong

    2013-09-01

    Erwinia amylovora causes a devastating disease called fire blight in rosaceous plants. The type III secretion system (T3SS) is one of the important virulence factors utilized by E. amylovora in order to successfully infect its hosts. By using a green fluorescent protein (GFP) reporter construct combined with a high-throughput flow cytometry assay, a library of phenolic compounds and their derivatives was studied for their ability to alter the expression of the T3SS. Based on the effectiveness of the compounds on the expression of the T3SS pilus, the T3SS inhibitors 4-methoxy-cinnamic acid (TMCA) and benzoic acid (BA) and one T3SS inducer, trans-2-(4-hydroxyphenyl)-ethenylsulfonate (EHPES), were chosen for further study. Both the T3SS inhibitors (TMCA and BA) and the T3SS inducer (EHPES) were found to alter the expression of T3SS through the HrpS-HrpL pathway. Additionally, TMCA altered T3SS expression through the rsmBEa-RsmAEa system. Finally, we found that TMCA and BA weakened the hypersensitive response (HR) in tobacco by suppressing the T3SS of E. amylovora. In our study, we identified phenolic compounds that specifically targeted the T3SS. The T3SS inhibitor may offer an alternative approach to antimicrobial therapy by targeting virulence factors of bacterial pathogens.

  3. AraC/XylS family stress response regulators Rob, SoxS, PliA, and OpiA in the fire blight pathogen Erwinia amylovora.

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    Pletzer, Daniel; Schweizer, Gabriel; Weingart, Helge

    2014-09-01

    Transcriptional regulators of the AraC/XylS family have been associated with multidrug resistance, organic solvent tolerance, oxidative stress, and virulence in clinically relevant enterobacteria. In the present study, we identified four homologous AraC/XylS regulators, Rob, SoxS, PliA, and OpiA, from the fire blight pathogen Erwinia amylovora Ea1189. Previous studies have shown that the regulators MarA, Rob, and SoxS from Escherichia coli mediate multiple-antibiotic resistance, primarily by upregulating the AcrAB-TolC efflux system. However, none of the four AraC/XylS regulators from E. amylovora was able to induce a multidrug resistance phenotype in the plant pathogen. Overexpression of rob led to a 2-fold increased expression of the acrA gene. However, the rob-overexpressing strain showed increased resistance to only a limited number of antibiotics. Furthermore, Rob was able to induce tolerance to organic solvents in E. amylovora by mechanisms other than efflux. We demonstrated that SoxS from E. amylovora is involved in superoxide resistance. A soxS-deficient mutant of Ea1189 was not able to grow on agar plates supplemented with the superoxide-generating agent paraquat. Furthermore, expression of soxS was induced by redox cycling agents. We identified two novel members of the AraC/XylS family in E. amylovora. PliA was highly upregulated during the early infection phase in apple rootstock and immature pear fruits. Multiple compounds were able to induce the expression of pliA, including apple leaf extracts, phenolic compounds, redox cycling agents, heavy metals, and decanoate. OpiA was shown to play a role in the regulation of osmotic and alkaline pH stress responses.

  4. Hypersensitive response and acyl-homoserine lactone production of the fire blight antagonists Erwinia tasmaniensis and Erwinia billingiae.

    Science.gov (United States)

    Jakovljevic, Vladimir; Jock, Susanne; Du, Zhiqiang; Geider, Klaus

    2008-09-01

    Fire blight caused by the Gram-negative bacterium Erwinia amylovora can be controlled by antagonistic microorganisms. We characterized epiphytic bacteria isolated from healthy apple and pear trees in Australia, named Erwinia tasmaniensis, and the epiphytic bacterium Erwinia billingiae from England for physiological properties, interaction with plants and interference with growth of E. amylovora. They reduced symptom formation by the fire blight pathogen on immature pears and the colonization of apple flowers. In contrast to E. billingiae, E. tasmaniensis strains induced a hypersensitive response in tobacco leaves and synthesized levan in the presence of sucrose. With consensus primers deduced from lsc as well as hrpL, hrcC and hrcR of the hrp region of E. amylovora and of related bacteria, these genes were successfully amplified from E. tasmaniensis DNA and alignment of the encoded proteins to other Erwinia species supported a role for environmental fitness of the epiphytic bacterium. Unlike E. tasmaniensis, the epiphytic bacterium E. billingiae produced an acyl-homoserine lactone for bacterial cell-to-cell communication. Their competition with the growth of E. amylovora may be involved in controlling fire blight.

  5. Fire blight (Erwinia amylovora) of rosaceous plants. Pathogen virulence and selection and characterization of biological control agents

    OpenAIRE

    Cabrefiga Olamendi, Jordi

    2004-01-01

    El fuego bacteriano, causado por Erwinia amylovora, es una enfermedad muy importante a nivel comercial y económico porque afecta a plantas de la familia de las rosáceas y es especialmente agresiva en manzano (Pyrus malus) y peral (Pyrus communis), así como en plantas ornamentales (Crataegus, Cotoneaster o Pyracantha). Esta enfermedad está distribuida por todo el mundo en zonas climáticas templadas de Amércia del Norte, Nueva Zelanda, Japón, Israel, Turquí y Europa. En España, el fuego bacter...

  6. TRANSGENIC EXPRESSION OF THE ERWINIA AMYLOVORA (FIRE BLIGHT) EFFECTOR PROTEIN EOP1 SUPRESSES HOST BASAL DEFENSE MECHANISMS IN MALUS (APPLE)

    Science.gov (United States)

    Erwinia amylovora (Ea) is the causative agent of fire blight, a devastating disease of apple and pear. Like many other plant and animal bacterial pathogens Ea utilizes a type three secretion system (TTSS) to deliver effector proteins into plant host cells. Once inside the host cell, effector protei...

  7. Erwinia amylovora pyrC mutant causes fire blight despite pyrimidine auxotrophy.

    Science.gov (United States)

    Ramos, L S; Sinn, J P; Lehman, B L; Pfeufer, E E; Peter, K A; McNellis, T W

    2015-06-01

    Erwinia amylovora bacteria cause fire blight disease, which affects apple and pear production worldwide. The Erw. amylovora pyrC gene encodes a predicted dihydroorotase enzyme involved in pyrimidine biosynthesis. Here, we discovered that the Erw. amylovora pyrC244::Tn5 mutant was a uracil auxotroph. Unexpectedly, the Erw. amylovora pyrC244::Tn5 mutant grew as well as the wild-type in detached immature apple and pear fruits. Fire blight symptoms caused by the pyrC244::Tn5 mutant in immature apple and pear fruits were attenuated compared to those caused by the wild-type. The pyrC244::Tn5 mutant also caused severe fire blight symptoms in apple tree shoots. A plasmid-borne copy of the wild-type pyrC gene restored prototrophy and symptom induction in apple and pear fruit to the pyrC244::Tn5 mutant. These results suggest that Erw. amylovora can obtain sufficient pyrimidine from the host to support bacterial growth and fire blight disease development, although de novo pyrimidine synthesis by Erw. amylovora is required for full symptom development in fruits. Significance and impact of the study: This study provides information about the fire blight host-pathogen interaction. Although the Erwinia amylovora pyrC mutant was strictly auxotrophic for pyrimidine, it grew as well as the wild-type in immature pear and apple fruits and caused severe fire blight disease in apple trees. This suggests that Erw. amylovora can obtain sufficient pyrimidines from host tissue to support growth and fire blight disease development. This situation contrasts with findings in some human bacterial pathogens, which require de novo pyrimidine synthesis for growth in host blood, for example.

  8. Erwinia amylovora loop-mediated isothermal amplification (LAMP) assay for rapid pathogen detection and on-site diagnosis of fire blight.

    Science.gov (United States)

    Bühlmann, Andreas; Pothier, Joël F; Rezzonico, Fabio; Smits, Theo H M; Andreou, Michael; Boonham, Neil; Duffy, Brion; Frey, Jürg E

    2013-03-01

    Several molecular methods have been developed for the detection of Erwinia amylovora, the causal agent of fire blight in pear and apple, but none are truly applicable for on-site use in the field. We developed a fast, reliable and field applicable detection method using a novel target on the E. amylovora chromosome that we identified by applying a comparative genomic pipeline. The target coding sequences (CDSs) are both uniquely specific for and all-inclusive of E. amylovora genotypes. This avoids potential false negatives that can occur with most commonly used methods based on amplification of plasmid gene targets, which can vary among strains. Loop-mediated isothermal AMPlification (LAMP) with OptiGene Genie II chemistry and instrumentation proved to be an exceptionally rapid (under 15 min) and robust method for detecting E. amylovora in orchards, as well as simple to use in the plant diagnostic laboratory. Comparative validation results using plant samples from inoculated greenhouse trials and from natural field infections (of regional and temporal diverse origin) showed that our LAMP had an equivalent or greater performance regarding sensitivity, specificity, speed and simplicity than real-time PCR (TaqMan), other LAMP assays, immunoassays and plating, demonstrating its utility for routine testing.

  9. Genomics of iron acquisition in the plant pathogen Erwinia amylovora: insights in the biosynthetic pathway of the siderophore desferrioxamine E.

    Science.gov (United States)

    Smits, Theo H M; Duffy, Brion

    2011-10-01

    Genomics has clarified the biosynthetic pathway for desferrioxamine E critical for iron acquisition in the enterobacterial fire blight pathogen Erwinia amylovora. Evidence for each of the individual steps and the role of desferrioxamine E biosynthesis in pathogen virulence and cell protection from host defenses is presented. Using comparative genomics, it can be concluded that desferrioxamine biosynthesis is ancestral within the genera Erwinia and Pantoea.

  10. Genetic differences between blight-causing Erwinia species with differing host specificities, identified by suppression subtractive hybridization.

    Science.gov (United States)

    Triplett, Lindsay R; Zhao, Youfu; Sundin, George W

    2006-11-01

    PCR-based subtractive hybridization was used to isolate sequences from Erwinia amylovora strain Ea110, which is pathogenic on apples and pears, that were not present in three closely related strains with differing host specificities: E. amylovora MR1, which is pathogenic only on Rubus spp.; Erwinia pyrifoliae Ep1/96, the causal agent of shoot blight of Asian pears; and Erwinia sp. strain Ejp556, the causal agent of bacterial shoot blight of pear in Japan. In total, six subtractive libraries were constructed and analyzed. Recovered sequences included type III secretion components, hypothetical membrane proteins, and ATP-binding proteins. In addition, we identified an Ea110-specific sequence with homology to a type III secretion apparatus component of the insect endosymbiont Sodalis glossinidius, as well as an Ep1/96-specific sequence with homology to the Yersinia pestis effector protein tyrosine phosphatase YopH.

  11. The genome of Erwinia tasmaniensis strain Et1/99, a non-pathogenic bacterium in the genus Erwinia.

    Science.gov (United States)

    Kube, Michael; Migdoll, Alexander Michael; Müller, Ines; Kuhl, Heiner; Beck, Alfred; Reinhardt, Richard; Geider, Klaus

    2008-09-01

    The complete genome of the bacterium Erwinia tasmaniensis strain Et1/99 consisting of a 3.9 Mb circular chromosome and five plasmids was sequenced. Strain Et1/99 represents an epiphytic plant bacterium related to Erwinia amylovora and E. pyrifoliae, which are responsible for the important plant diseases fire blight and Asian pear shoot blight, respectively. Strain Et1/99 is a non-pathogenic bacterium and is thought to compete with these and other bacteria when occupying the same habitat during initial colonization. Genome analysis revealed tools for colonization, cellular communication and defence modulation, as well as genes coding for the synthesis of levan and a not detected capsular exopolysaccharide. Strain Et1/99 may secrete indole-3-acetic acid to increase availability of nutrients provided on plant surfaces. These nutrients are subsequently accessed and metabolized. Secretion systems include the hypersensitive response type III pathway present in many pathogens. Differences or missing parts within the virulence-related factors distinguish strain Et1/99 from pathogens such as Pectobacterium atrosepticum and the related Erwinia spp. Strain Et1/99 completely lacks the sorbitol operon, which may also affect its inability to invade fire blight host plants. Erwinia amylovora in contrast depends for virulence on utilization of sorbitol, the dominant carbohydrate in rosaceous plants. The presence of other virulence-associated factors in strain Et1/99 indicates the ancestral genomic background of many plant-associated bacteria.

  12. Using functional genomics to identify molecular markers for fire blight resistance (Erwinia amylovora) in apple (Malus)

    Science.gov (United States)

    Fire blight, caused by Erwinia amylovora (Ea), is a destructive disease of apple (Malus), pear (Pyrus) and some woody ornamentals in the rose family (Rosaceae). The goal of this project is to use a functional genomics approach to develop tools to breed fire blight resistant apples. Six hundred fifty...

  13. Evaluation of Susceptibility of Different Pear Hybrid Populations to Fire Blight (Erwinia amylovora

    Directory of Open Access Journals (Sweden)

    Yasemin EVRENOSOĞLU

    2011-05-01

    Full Text Available Fire blight disease caused by pathogenic bacterium Erwinia amylovora, is the serious disease of pear, and there is not a certain chemical management against this disease except antibiotic-type compounds such as streptomycin. It is very important to improve new fire blight resistant cultivars in case of integrated disease management. With this purpose, different crosses have been made between Pyrus communis varieties that have good fruit characteristics and resistant cultigens. Besides, self and open pollination treatments have been carried out in maternal plants. The disease resistance level of the hybrids obtained from these combinations was determined by artificial inoculations by Erwinia amylovora in greenhouse conditions. A total of 3284 hybrids were inoculated, and 2631 of them survived and were distributed to different susceptibility classes. 19.88% of the inoculated hybrids was killed by Erwinia amylovora. Total distribution of the hybrids to susceptibility classes was as 6.18% in class “A- slightly susceptible”, 3.11% in class “B- less susceptible”, 8.89% in class “C- mid-susceptible”, 20.28% in class “D- susceptible”, and 61.54% in class “E- very susceptible”. Majority of class “A- slightly susceptible” hybrids were obtained from ‘Magness’ x ‘Ankara’ combination. ‘Kieffer’ x ‘Santa Maria’, ‘Kieffer’ open pollination, ‘Magness’ x ‘Akça’, ‘Magness’ x ‘Kieffer’, ‘Magness’ x ‘Santa Maria’, ‘Mustafa Bey’ x ‘Moonglow’ treatments displayed good results with respect to “A- slightly susceptible” character. It is very important to evaluate these hybrid pear populations through different fruit and tree characteristics in the future.

  14. Control of plant defense mechanisms and fire blight pathogenesis through the regulation of 6-thioguanine biosynthesis in Erwinia amylovora.

    Science.gov (United States)

    Coyne, Sébastien; Litomska, Agnieszka; Chizzali, Cornelia; Khalil, Mohammed N A; Richter, Klaus; Beerhues, Ludger; Hertweck, Christian

    2014-02-10

    Fire blight is a devastating disease of Rosaceae plants, such as apple and pear trees. It is characterized by necrosis of plant tissue, caused by the phytopathogenic bacterium Erwinia amylovora. The plant pathogen produces the well-known antimetabolite 6-thioguanine (6TG), which plays a key role in fire blight pathogenesis. Here we report that YcfR, a member of the LTTR family, is a major regulator of 6TG biosynthesis in E. amylovora. Inactivation of the regulator gene (ycfR) led to dramatically decreased 6TG production. Infection assays with apple plants (Malus domestica cultivar Holsteiner Cox) and cell cultures of Sorbus aucuparia (mountain ash, rowan) revealed abortive fire blight pathogenesis and reduced plant response (biphenyl and dibenzofuran phytoalexin production). In the presence of the ΔycfR mutant, apple trees were capable of activating the abscission machinery to remove infected tissue. In addition to unveiling the regulation of 6TG biosynthesis in a major plant pathogen, we demonstrate for the first time that this antimetabolite plays a pivotal role in dysregulating the plant response to infection.

  15. Systems and models of fire blight (Erwinia amylovora prediction

    Directory of Open Access Journals (Sweden)

    Krzysztof Kielak

    2013-12-01

    Full Text Available The paper presents fire blight prediction models and systems, developed in Europe (system Billing - versions: BOS, BRS, BIS95 and originated from this system: Firescreen, FEUERBRA and ANLAFBRA and in United States (Californian system, model Maryblyt and system Cougarblight. Use of above models and systems in various climatic-geographic conditions and comparison of obtained prognostic data to real fire blight occurrence is reviewed. The newest trends in research on improvement of prognostic analyses parameters with their adjustment to particular conditions and consideration of infection source occurrence are also presented.

  16. Erwinia amylovora novel plasmid pEI70: complete sequence, biogeography, and role in aggressiveness in the fire blight phytopathogen.

    Directory of Open Access Journals (Sweden)

    Pablo Llop

    Full Text Available Comparative genomics of several strains of Erwinia amylovora, a plant pathogenic bacterium causal agent of fire blight disease, revealed that its diversity is primarily attributable to the flexible genome comprised of plasmids. We recently identified and sequenced in full a novel 65.8 kb plasmid, called pEI70. Annotation revealed a lack of known virulence-related genes, but found evidence for a unique integrative conjugative element related to that of other plant and human pathogens. Comparative analyses using BLASTN showed that pEI70 is almost entirely included in plasmid pEB102 from E. billingiae, an epiphytic Erwinia of pome fruits, with sequence identities superior to 98%. A duplex PCR assay was developed to survey the prevalence of plasmid pEI70 and also that of pEA29, which had previously been described in several E. amylovora strains. Plasmid pEI70 was found widely dispersed across Europe with frequencies of 5-92%, but it was absent in E. amylovora analyzed populations from outside of Europe. Restriction analysis and hybridization demonstrated that this plasmid was identical in at least 13 strains. Curing E. amylovora strains of pEI70 reduced their aggressiveness on pear, and introducing pEI70 into low-aggressiveness strains lacking this plasmid increased symptoms development in this host. Discovery of this novel plasmid offers new insights into the biogeography, evolution and virulence determinants in E. amylovora.

  17. Erwinia amylovora novel plasmid pEI70: complete sequence, biogeography, and role in aggressiveness in the fire blight phytopathogen.

    Science.gov (United States)

    Llop, Pablo; Cabrefiga, Jordi; Smits, Theo H M; Dreo, Tanja; Barbé, Silvia; Pulawska, Joanna; Bultreys, Alain; Blom, Jochen; Duffy, Brion; Montesinos, Emilio; López, María M

    2011-01-01

    Comparative genomics of several strains of Erwinia amylovora, a plant pathogenic bacterium causal agent of fire blight disease, revealed that its diversity is primarily attributable to the flexible genome comprised of plasmids. We recently identified and sequenced in full a novel 65.8 kb plasmid, called pEI70. Annotation revealed a lack of known virulence-related genes, but found evidence for a unique integrative conjugative element related to that of other plant and human pathogens. Comparative analyses using BLASTN showed that pEI70 is almost entirely included in plasmid pEB102 from E. billingiae, an epiphytic Erwinia of pome fruits, with sequence identities superior to 98%. A duplex PCR assay was developed to survey the prevalence of plasmid pEI70 and also that of pEA29, which had previously been described in several E. amylovora strains. Plasmid pEI70 was found widely dispersed across Europe with frequencies of 5-92%, but it was absent in E. amylovora analyzed populations from outside of Europe. Restriction analysis and hybridization demonstrated that this plasmid was identical in at least 13 strains. Curing E. amylovora strains of pEI70 reduced their aggressiveness on pear, and introducing pEI70 into low-aggressiveness strains lacking this plasmid increased symptoms development in this host. Discovery of this novel plasmid offers new insights into the biogeography, evolution and virulence determinants in E. amylovora.

  18. Phylogenetic position and virulence apparatus of the pear flower necrosis pathogen Erwinia piriflorinigrans CFBP 5888T as assessed by comparative genomics.

    Science.gov (United States)

    Smits, Theo H M; Rezzonico, Fabio; López, María M; Blom, Jochen; Goesmann, Alexander; Frey, Jürg E; Duffy, Brion

    2013-10-01

    Erwinia piriflorinigrans is a necrotrophic pathogen of pear reported from Spain that destroys flowers but does not progress further into the host. We sequenced the complete genome of the type strain CFBP 5888(T) clarifying its phylogenetic position within the genus Erwinia, and indicating a position between its closest relative, the epiphyte Erwinia tasmaniensis and other plant pathogenic Erwinia spp. (i.e., the fire blight pathogen E. amylovora and the Asian pear pathogen E. pyrifoliae). Common features are the type III and type VI secretion systems, amylovoran biosynthesis and desferrioxamine production. The E. piriflorinigrans genome also provided the first evidence for production of the siderophore chrysobactin within the genus Erwinia sensu stricto, which up to now was mostly associated with phytopathogenic, soft-rot Dickeya and Pectobacterium species. Plasmid pEPIR37, reported in this strain, is closely related to small plasmids found in the fire blight pathogen E. amylovora and E. pyrifoliae. The genome of E. piriflorinigrans also gives detailed insights in evolutionary genomics of pathoadapted Erwinia.

  19. Antagonistic potential of Pseudomonas graminis 49M against Erwinia amylovora, the causal agent of fire blight.

    Science.gov (United States)

    Mikiciński, Artur; Sobiczewski, Piotr; Puławska, Joanna; Malusa, Eligio

    2016-08-01

    In a previous study (Mikiciński et al. in Eur J Plant Pathol, doi: 10.1007/s10658-015-0837-y , 2015), we described the characterization of novel strain 49M of Pseudomonas graminis, isolated from the phyllosphere of apple trees in Poland showing a good protective activity against fire blight on different organs of host plants. We now report investigations to clarify the basis for this activity. Strain 49M was found to produce siderophores on a medium containing complex CAS-Fe(3+) and HDTMA, but was not able to produce N-acyl homoserine lactones (AHLs). Moreover, it formed a biofilm on polystyrene and polyvinyl chloride (PVC) surfaces. Strain 49M gave a positive reaction in PCR with primers complementary to gacA, the regulatory gene influencing the production of several secondary metabolites including antibiotics. The genes prnD (encoding pyrrolnitrin), pltC, pltB (pyoluteorin), phlD (2,4-diacetyl-phloroglucinol) and phzC as well as phzD (and their homologs phzF and phzA encoding phenazine), described for antagonistic fluorescent pseudomonads, however, were not detected. Research into the biotic relationship between strain 49M and Erwinia amylovora strain Ea659 on five microbiological media showed that this strain clearly inhibited the growth of the pathogen on King's B and nutrient agar with glycerol media, to a very small extent on nutrient agar with sucrose, and not at all on Luria-Bertani agar. On medium 925, strain 49M even stimulated E. amylovora growth. The addition of ferric chloride to King's B resulted in the loss of its inhibitory ability. Testing the survival of 49M in vitro showed its resistance to drought, greater than that of E. amylovora.

  20. Biosynthesis of the antimetabolite 6-thioguanine in Erwinia amylovora plays a key role in fire blight pathogenesis.

    Science.gov (United States)

    Coyne, Sébastien; Chizzali, Cornelia; Khalil, Mohammed N A; Litomska, Agnieszka; Richter, Klaus; Beerhues, Ludger; Hertweck, Christian

    2013-09-27

    Sulfur for fire: The molecular basis for the biosynthesis of the antimetabolite 6-thioguanine (6TG) was unveiled in Erwinia amylovora, the causative agent of fire blight. Bioinformatics, heterologous pathway reconstitution in E. coli, and mutational analyses indicate that the protein YcfA mediates guanine thionation in analogy to 2-thiouridylase. Assays in planta and in cell cultures reveal for the first time a crucial role of 6TG in fire blight pathogenesis.

  1. Fire blight: applied genomic insights of the pathogen and host

    Science.gov (United States)

    The enterobacterial phytopathogen, Erwinia amylovora, causes fire blight, an invasive disease that threatens a wide range of commercial and ornamental Rosaceae host plants. The response elicited by E. amylovora in its host during disease development is similar to the hypersensitive reaction that ty...

  2. Preliminary results on the ability of pentatomidae to transfer fire blight Erwinia amylovora under controlled conditions.

    Science.gov (United States)

    Peusens, G; Schoofs, H; Deckers, T; Belien, T

    2013-01-01

    With their piercing-sucking mouthparts stink bugs (Heteroptera: Pentatomidae), a major pest in especially organic orchards, create wounds in fruit of pear trees. As Erwinia amylovora (Burrill, Winslow et al.), a wide spread bacterial disease affecting many rosaceous plants including pome fruit trees and hawthorn, enters through openings in flowers, leaves, shoots and fruit, feeding punctures caused by these bugs might be inoculated with Erwinia bacteria. In order to investigate the ability of the bugs Pentotoma rufipes L. and Polomena prasina L. to transmit fire blight, insects were caught in an organically managed orchard without fire blight, brought into contact with artificially inoculated immature pear fruit/slices and transferred to healthy, mechanically wounded pear fruit/slices. After an incubation period potential transmission of bacteria was examined by evaluation of symptom expression (necrosis, ooze production). To assess the presence of bacteria on the exoskeleton of the tested bugs, all bugs were forced to walk on a semiselective nutrient agar medium. In another experiment the viability of Ea on the exoskeleton was tested -after previous contact with ooze- through washing and plating of the wash water. All experiments were conducted under optimal climatological conditions and according to quarantine standards. Results demonstrated the ability of stink bugs to transfer E. amylovora to fruit and the viability of bacteria on stink bugs externally - both under lab conditions.

  3. Control of fire blight (Erwinia amylovora on apple trees with trunk-injected plant resistance inducers and antibiotics and assessment of induction of pathogenesis-related protein genes

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    Srđan G. Aćimović

    2015-02-01

    Full Text Available Management of fire blight is complicated by limitations on use of antibiotics in agriculture, antibiotic resistance development, and limited efficacy of alternative control agents. Even though successful in control, preventive antibiotic sprays also affect non-target bacteria, aiding the selection for resistance which could ultimately be transferred to the pathogen Erwinia amylovora. Trunk injection is a target-precise pesticide delivery method that utilizes tree xylem to distribute injected compounds. Trunk injection could decrease antibiotic usage in the open environment and increase the effectiveness of compounds in fire blight control. In field experiments, after 1-2 apple tree injections of either streptomycin, potassium phosphites (PH or acibenzolar-S-methyl (ASM, significant reduction of blossom and shoot blight symptoms was observed compared to water- or non-injected control trees. Overall disease suppression with streptomycin was lower than typically observed following spray applications to flowers. Trunk injection of oxytetracycline resulted in excellent control of shoot blight severity, suggesting that injection is a superior delivery method for this antibiotic. Injection of both ASM and PH resulted in the significant induction of PR-1, PR-2 and PR-8 protein genes in apple leaves indicating induction of systemic acquired resistance (SAR under field conditions. The time separating SAR induction and fire blight symptom suppression indicated that various defensive compounds within the SAR response were synthesized and accumulated in the canopy. ASM and PH suppressed fire blight even after cessation of induced gene expression. With the development of injectable formulations and optimization of doses and injection schedules, the injection of protective compounds could serve as an effective option for fire blight control.

  4. Genetics of biosynthesis and structure of the capsular exopolysaccharide from the Asian pear pathogen Erwinia pyrifoliae.

    Science.gov (United States)

    Kim, Won-Sik; Schollmeyer, Martin; Nimtz, Manfred; Wray, Victor; Geider, Klaus

    2002-12-01

    Erwinia pyrifoliae is a novel bacterial pathogen, which causes Asian pear blight and is related to Erwinia amylovora, the causative agent of fire blight. E. pyrifoliae produces exopolysaccharide (EPS) related to amylovoran in its sugar composition and sugar linkages. This was shown by degradation of the EPS with a viral depolymerase, and by methylation analysis and ESI/MS. The structure of the repeating units was confirmed by (1)H-NMR spectra. The EPS of E. pyrifoliae carried side chains, which were mainly terminated by acetyl and pyruvyl residues as found previously for amylovoran. On the other hand, a second side chain with glucose found for up to 65% of the repeating units of amylovoran was completely absent. The nucleotide sequences of five genes of the cps cluster of E. pyrifoliae encoding proteins for EPS synthesis were characterized and displayed a high homology with the corresponding ams genes. Similar functions of the gene products are assumed. As for ams mutants of E. amylovora, a cpsB mutant of E. pyrifoliae did not synthesize EPS and did not produce ooze on slices of immature pears or symptoms on pear seedlings. The cps mutant was complemented for EPS synthesis and virulence on pear slices with a gene cluster of E. amylovora that included amsB.

  5. Non-conventional possibilities of protection of apple and pear against fire blight (Erwinia amylovora

    Directory of Open Access Journals (Sweden)

    Piotr Sobiczewski

    2013-12-01

    Full Text Available Standard program of plant protection against fire blight consists of use of management practices and chemical control method. Recently a new, non-conventional possibilities based on application of biocontrol agents (two biopreparations have been already introduced into practice: Bliteban A506 (Pseudomonas fluorescens and BlossomBless (Pantoea agglomerans, plant extracts active against Erwinia amylovora (AkseBio containing extracts from Thymbra spicata and Biomit Plussz with extracts from various plant species and microelements and resistance inducers (Regalis, Bion and plant extracts are of great interest. Also plant transformation with resistance genes such as: hrpN (harpin, dpo (EPS depolymerase and lytic protein genes (attacin E, cecropin SB-37, T4 lysozyme is a promising perspective.

  6. Localization of transposon insertions in pathogenicity mutants of Erwinia amylovora and their biochemical characterization.

    Science.gov (United States)

    Bellemann, P; Geider, K

    1992-05-01

    Transposon Tn5, on a mobilizable ColE1 plasmid, on a Ti plasmid derepressed for bacterial transfer, and on the bacteriophage fd genome, was used to construct pathogenicity mutants of the fire blight pathogen Erwinia amylovora. Eleven nonpathogenic mutants were isolated from 1600 independent mutants screened. These mutants were divided into three types: auxotrophs, exopolysaccharide (EPS)-deficient mutants and a mutant of the dsp phenotype. According to their insertion sites the Tn5 mutants were mapped into several classes. Some of the mutants could be complemented with cosmid clones from a genomic library of the parent strain for EPS production on minimal agar. EPS-deficient mutants and the dsp mutant could complement each other to produce virulence symptoms on pear slices.

  7. Identification of gene-specific markers for resistance to Erwinia amylovora (fire blight) in Malus (apple) by a functional genomics approach

    Science.gov (United States)

    Fire blight, caused by Erwinia amylovora (Ea), is a destructive disease of apple (Malus), pear (Pyrus) and other plants in the rose family (Rosaceae). 650 expressed sequence tags (ESTs) associated with fire blight were identified from Ea-challenged apple leaf tissue by suppression subtractive hybrid...

  8. Genome comparison of the epiphytic bacteria Erwinia billingiae and E. tasmaniensis with the pear pathogen E. pyrifoliae

    Directory of Open Access Journals (Sweden)

    Kuhl Heiner

    2010-06-01

    Full Text Available Abstract Background The genus Erwinia includes plant-associated pathogenic and non-pathogenic Enterobacteria. Important pathogens such as Erwinia amylovora, the causative agent of fire blight and E. pyrifoliae causing bacterial shoot blight of pear in Asia belong to this genus. The species E. tasmaniensis and E. billingiae are epiphytic bacteria and may represent antagonists for biocontrol of fire blight. The presence of genes that are putatively involved in virulence in E. amylovora and E. pyrifoliae is of special interest for these species in consequence. Results Here we provide the complete genome sequences of the pathogenic E. pyrifoliae strain Ep1/96 with a size of 4.1 Mb and of the non-pathogenic species E. billingiae strain Eb661 with a size of 5.4 Mb, de novo determined by conventional Sanger sequencing and next generation sequencing techniques. Genome comparison reveals large inversions resulting from homologous recombination events. Furthermore, comparison of deduced proteins highlights a relation of E. billingiae strain Eb661 to E. tasmaniensis strain Et1/99 and a distance to E. pyrifoliae for the overall gene content as well as for the presence of encoded proteins representing virulence factors for the pathogenic species. Pathogenicity of E. pyrifoliae is supposed to have evolved by accumulation of potential virulence factors. E. pyrifoliae carries factors for type III secretion and cell invasion. Other genes described as virulence factors for E. amylovora are involved in the production of exopolysaccharides, the utilization of plant metabolites such as sorbitol and sucrose. Some virulence-associated genes of the pathogenic species are present in E. tasmaniensis but mostly absent in E. billingiae. Conclusion The data of the genome analyses correspond to the pathogenic lifestyle of E. pyrifoliae and underlines the epiphytic localization of E. tasmaniensis and E. billingiae as a saprophyte.

  9. Gene-for-gene relationship in the host-pathogen system Malus × robusta 5-Erwinia amylovora.

    Science.gov (United States)

    Vogt, Isabelle; Wöhner, Thomas; Richter, Klaus; Flachowsky, Henryk; Sundin, George W; Wensing, Annette; Savory, Elizabeth A; Geider, Klaus; Day, Brad; Hanke, Magda-Viola; Peil, Andreas

    2013-03-01

    Fire blight is a destructive bacterial disease caused by Erwinia amylovora affecting plants in the family Rosaceae, including apple. Host resistance to fire blight is present mainly in accessions of Malus spp. and is thought to be quantitative in this pathosystem. In this study we analyzed the importance of the E. amylovora effector avrRpt2(EA) , a homolog of Pseudomonas syringae avrRpt2, for resistance of Malus × robusta 5 (Mr5). The deletion mutant E. amylovora Ea1189ΔavrRpt2(EA) was able to overcome the fire blight resistance of Mr5. One single nucleotide polymorphism (SNP), resulting in an exchange of cysteine to serine in the encoded protein, was detected in avrRpt2(EA) of several Erwinia strains differing in virulence to Mr5. E. amylovora strains encoding serine (S-allele) were able to overcome resistance of Mr5, whereas strains encoding cysteine (C-allele) were not. Allele specificity was also observed in a coexpression assay with Arabidopsis thaliana RIN4 in Nicotiana benthamiana. A homolog of RIN4 has been detected and isolated in Mr5. These results suggest a system similar to the interaction of RPS2 from A. thaliana and AvrRpt2 from P. syringae with RIN4 as guard. Our data are suggestive of a gene-for-gene relationship for the host-pathogen system Mr5 and E. amylovora.

  10. The Differences among Pear Genotypes to Fire Blight (Erwinia amylovora Attack, Based on Observations of Natural Infection

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    Adriana F. SESTRAS

    2008-08-01

    Full Text Available Fire blight, caused by the bacterium Erwinia amylovora, is one of the most damaging diseases of pear in the world. In Cluj-Napoca area, situated in central Transylvania, Romania, fire blight was observed first in 1994, very late comparative with the other countries from occidental Europe. The response of the pear cultivars and species from National Pear Collection from Cluj-Napoca to fire blight attack, assessed in natural conditions of infection, range on a large scale of variability, which denotes a strong influence of the genotype in expression of resistance or sensitivity to disease. From all genotypes, about 20.5% have not presented symptoms of attack, among them being the following: 'Blanquet precoce', 'Klementinka', 'Severianka', 'Beurre Bachelier', 'Kieffer Seedling', 'Er Shi Shinge', 'Beurre Amanlis', 'Bristol Cross', 'Beurre Liegel', 'Beurre Lucon', 'Grand Champion', 'Magness', 'Mericourt' etc. and several ancient autochthonous cultivars ('Pere malaiete', 'De zahar de Bihor', 'Cu miez rosu', 'Clopotele', 'Garoafa mare', 'Craiese', 'Para de apa'. Also, there were identified several species of Pyrus with no attack, as P. pollveria, P. common pear, P. lindlezi, P. malifolia, P. persica, P. ussuriensis, P. variolosa. The remarked genotypes could be potential sources for further breeding programmes and increase the number of genotypes available for breeding new pear cultivars resistant to Erwinia attack.

  11. Complete genome sequence of the plant pathogen Erwinia amylovora strain ATCC 49946

    Science.gov (United States)

    Erwinia amylovora causes the economically important disease fire blight that affects rosaceous plants, especially pear and apple. Here we report the complete genome sequence and annotation of strain ATCC 49946. The analysis of the sequence and its comparison with sequenced genomes of closely related...

  12. Genetic islands in pome fruit pathogenic and non-pathogenic Erwinia species and related plasmids.

    Science.gov (United States)

    Llop, Pablo

    2015-01-01

    New pathogenic bacteria belonging to the genus Erwinia associated with pome fruit trees (Erwinia, E. piriflorinigrans, E. uzenensis) have been increasingly described in the last years, and comparative analyses have found that all these species share several genetic characteristics. Studies at different level (whole genome comparison, virulence genes, plasmid content, etc.) show a high intraspecies homogeneity (i.e., among E. amylovora strains) and also abundant similarities appear between the different Erwinia species: presence of plasmids of similar size in the pathogenic species; high similarity in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes, in the chromosomes. Many genetic similarities have been observed also among some of the plasmids (and genomes) from the pathogenic species and E. tasmaniensis or E. billingiae, two epiphytic species on the same hosts. The amount of genetic material shared in this genus varies from individual genes to clusters, genomic islands and genetic material that even may constitute a whole plasmid. Recent research on evolution of erwinias point out the horizontal transfer acquisition of some genomic islands that were subsequently lost in some species and several pathogenic traits that are still present. How this common material has been obtained and is efficiently maintained in different species belonging to the same genus sharing a common ecological niche provides an idea of the origin and evolution of the pathogenic Erwinia and the interaction with non-pathogenic species present in the same niche, and the role of the genes that are conserved in all of them.

  13. Antimicrobial and anti-pathogenic activity of some thioureides derivatives against Erwinia amylovora phytopathogenic strains.

    Science.gov (United States)

    Măruţescu, Luminiţa; Niţulescu, Mihai-George; Bucur, Marcela; Diţu, Lia-Mara; Mihăescu, Grigore; Lazăr, Veronica; Sesan, Tatiana

    2011-01-01

    A series of N-(1-methyl-1 Hpyrazole-4-carbonyl)-thiourea derivatives were assessed for their in vitro antimicrobial and anti-pathogenic activity against twenty-two strains of Erwinia amylovora isolated from different regions in Romania. The compounds were solubilised in dimethylsulfoxide and screened for their in vitro antimicrobial activity. The qualitative screening of the susceptibility spectra of various strains to the compounds was performed by adapted diffusion techniques (distribution of the tested compound solution directly on the solid medium previously seeded with the bacterial inoculums). The quantitative assay of the minimal inhibitory concentration (MIC, microg/mL) was based on liquid medium two-fold microdilutions. The subinhibitory concentrations of the tested substances were investigated for their influence on biofilm development on inert substrata. The present study showed that six new thiourea compounds exhibited a low antibacterial activity (MIC values > 500 microg/ml), but the subinhibitory concentrations inhibited the biofilm development on inert substrata. Thus, these results could suggest the usefulness of the tested compounds as control agents for preventing the first stage (colonization) of the infection with the fire blight pathogen.

  14. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple

    Science.gov (United States)

    Background: Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple....

  15. Erwinia uzenensis sp. nov., a novel pathogen that affects European pear trees (Pyrus communis L.).

    Science.gov (United States)

    Matsuura, Takayuki; Mizuno, Akifumi; Tsukamoto, Takanori; Shimizu, Yoshiaki; Saito, Norihiko; Sato, Shigeyoshi; Kikuchi, Shigemi; Uzuki, Tsuneyasu; Azegami, Koji; Sawada, Hiroyuki

    2012-08-01

    Bacteria were isolated from black lesions on shoots of European pear trees (Pyrus communis L.) in an orchard in Japan. Previous characterization of this novel pathogen by phenotypic and genotypic methods suggested that it should belong to the genus Erwinia but might not correspond to either Erwinia amylovora or Erwinia pyrifoliae. Here, phylogenetic analyses of the 16S rRNA gene, gyrB, and rpoD gene sequences indicated that it could not be assigned to any recognized species of the genus Erwinia. DNA-DNA hybridization confirmed that the bacterial strains represented a novel species. The DNA G+C contents, the fatty acid profile and phenotypic characteristics resembled those previously reported for members of the genus Erwinia. On the basis of these and previous results, the pathogen represents a novel species of the genus Erwinia, for which the name Erwinia uzenensis sp. nov. (type strain: YPPS 951(T) = LMG 25843(T) = NCPPB 4475(T)) is proposed.

  16. Evaluation of kasugamycin for fire blight management, effect on nontarget bacteria, and assessment of kasugamycin resistance potential in Erwinia amylovora.

    Science.gov (United States)

    McGhee, Gayle C; Sundin, George W

    2011-02-01

    The emergence and spread of streptomycin-resistant strains of Erwinia amylovora in Michigan has necessitated the evaluation of new compounds effective for fire blight control. The aminoglycoside antibiotic kasugamycin (Ks) targets the bacterial ribosome and is particularly active against E. amylovora. The efficacy of Ks formulated as Kasumin 2L for control of fire blight was evaluated in six experiments conducted over four field seasons in our experimental orchards in East Lansing, MI. Blossom blight control was statistically equivalent to the industry standard streptomycin in all experiments. E. amylovora populations remained constant on apple flower stigmas pretreated with Kasumin and were ≈100-fold lower than on stigmas treated with water. Kasumin applied to apple trees in the field also resulted in a 100-fold reduced total culturable bacterial population compared with trees treated with water. We performed a prospective analysis of the potential for kasugamycin resistance (Ks(R)) development in E. amylovora which focused on spontaneous resistance development and acquisition of a transferrable Ks(R) gene. In replicated lab experiments, the development of spontaneous resistance in E. amylovora to Ks at 250 or 500 ppm was not observed when cells were directly plated on medium containing high concentrations of the antibiotic. However, exposure to increasing concentrations of Ks in media (initial concentration 25 μg ml(-1)) resulted in the selection of Ks resistance (at 150 μg ml(-1)) in the E. amylovora strains Ea110, Ea273, and Ea1189. Analysis of mutants indicated that they harbored mutations in the kasugamycin target ksgA gene and that all mutants were impacted in relative fitness observable through a reduced growth rate in vitro and decreased virulence in immature pear fruit. The possible occurrence of a reservoir of Ks(R) genes in orchard environments was also examined. Culturable gram-negative bacteria were surveyed from six experimental apple orchards

  17. QTL analysis of the genetic architecture determining resistance to fire blight in an apple progeny

    NARCIS (Netherlands)

    Calenge, F.; Drouet, D.; Weg, van de W.E.; Brisset, M.N.; Paulin, J.P.; Durel, C.E.

    2004-01-01

    Fire blight, caused by the bacterial pathogen Erwinia amylovora, is one of the most destructive diseases of apple (Malus x domestica). In order to analyse the genetic determinism of resistance to fire blight in apple, a quantitative trait analysis (QTL) approach was used. A F1 progeny of 164 individ

  18. The influence of plant extracts on growth of Erwinia amylovora - the causal agent of fire blight

    Directory of Open Access Journals (Sweden)

    Grzegorz Krupiński

    2013-12-01

    Full Text Available Ethanol and water extracts obtained on Soxhlet apparatus from various organs and parts (leaves, flowers, shoots, onion, bark, fruit of 30 herbal and woody plants species were tested for growth inhibition of Erwinia amylovora using agar diffusion method. Active extracts were found in 23 plant species but in 13 ofthem it was found for the first time. The highest diameter of growth inhibition zone of this bacterium was caused by extracts from Aloe arborescens, Juglans regia, Rhus typhina, Salvia offici nalis and Satureja hortensis. In almost all cases ethanol appeared to be a better solvent of active plant substances against E.amylovora than water.

  19. Draft genome sequence of Erwinia tracheiphila, an economically important bacterial pathogen of cucurbits

    Science.gov (United States)

    Erwinia tracheiphila is one of the most economically important pathogen of cucumbers, melons, squashes, pumpkins, and gourds, in the Northeastern and Midwestern United States, yet the molecular pathology remains uninvestigated. Here we report the first draft genome sequence of an E. tracheiphila str...

  20. Genetic islands in pome fruit pathogenic and nonpathogenic Erwinia species and related plasmids

    Directory of Open Access Journals (Sweden)

    Pablo eLlop

    2015-08-01

    Full Text Available New pathogenic bacteria species belonging to the genus Erwinia associated with pome fruit trees (Erwinia pyrifoliae, E. piriflorinigrans, E. uzenensis have been increasingly described in the last years, and comparative analyses have found that all these species share several genetic characteristics. Studies at different level (whole genome comparison, virulence genes, plasmid content, etc. show a high intraspecies homogeneity (i.e. among E. amylovora strains and also abundant similarities appear between the different Erwinia species: presence of plasmids of similar size in the pathogenic species; high similarity in several genes associated with exopolysaccharide production and hence, with virulence, as well as in some other genes, in the chromosomes. Many genetic similarities have been observed also among some of the plasmids (and genomes from the pathogenic species and E. tasmaniensis or E. billingiae, two epiphytic species on the same hosts. The amount of genetic material shared in this genus varies from individual genes to clusters, genomic islands and genetic material that even may constitute a whole plasmid. Recent research on evolution of erwinias point out the horizontal transfer acquisition of some genomic islands that were subsequently lost in some species and several pathogenic traits that are still present. How this common material has been obtained and is efficiently maintained in different species belonging to the same genus sharing a common ecological niche provides an idea of the origin and evolution of the pathogenic Erwinia and the interaction with nonpathogenic species present in the same niche, and the role of the genes that are conserved in all of them.

  1. Seca dos ponteiros da goiabeira causada por Erwinia psidii: níveis de incidência e aspectos epidemiológicos Guava bacterial blight due to Erwinia psidii: incidence levels and epidemiological aspects

    Directory of Open Access Journals (Sweden)

    Abi Soares Anjos Marques

    2007-01-01

    Full Text Available Um dos fatores limitantes ao cultivo da goiabeira no Brasil é a 'seca dos ponteiros', causada por Erwinia psidii, presente nas regiões Sudeste e Centro-Oeste, onde se concentram grandes áreas produtoras. Considerando a pequena disponibilidade de informações sobre a epidemiologia e níveis de incidência dessa bacteriose, este estudo teve como objetivos: confirmar a distribuição e verificar a dispersão da seca dos ponteiros da goiabeira no Distrito Federal; investigar o efeito da temperatura sobre a multiplicação in vitro de E. psidii; desenvolver um teste de patogenicidade prático e eficiente e avaliar a sobrevivência in vitro da bactéria em diferentes substratos. A doença foi identificada em 56% das propriedades produtoras avaliadas no DF, com 81,9% de correlação entre a presença de sintomas e o diagnóstico laboratorial. A melhor faixa de temperatura para multiplicação de E. psidii foi de 24 a 33 ºC, e a bactéria permaneceu viável por até 120 dias em suspensão em água. A inoculação da bactéria em folhas ou hastes destacadas levou ao aparecimento de sintomas a partir do sétimo dia e mostrou-se eficiente como um teste rápido para se avaliar a patogenicidade de isolados.A major disease that affects guava is 'bacterial blight', caused by Erwinia psidii, which has been reported in Southeastern and Central Regions of Brazil where the major producing areas are located. Considering the lack of information on epidemiology and incidence levels of this disease, the objectives of this study were to confirm the presence and to verify the spread of the disease in Distrito Federal (DF; to determine optimal temperature for in vitro multiplication of E. psidii; to develop a simple and effective method for pathogenicity testing and to evaluate in vitro bacterial survival on different substrates. The disease was detected in 56% of producing orchards evaluated in DF, with a correlation of 81, 9% between presence of symptoms and

  2. Putative resistance gene markers associated with quantitative trait loci for fire blight resistance in Malus 'Robusta 5' accessions

    Science.gov (United States)

    Breeding of fire blight resistant scions and rootstocks is a goal of several international apple breeding programs, as options are limited for management of this destructive disease caused by the bacterial pathogen Erwinia amylovora. A broad, large effect QTL for fire blight resistance has been pre...

  3. Erwinia piriflorinigrans sp. nov., a novel pathogen that causes necrosis of pear blossoms.

    Science.gov (United States)

    López, María M; Roselló, Montserrat; Llop, Pablo; Ferrer, Sergi; Christen, Richard; Gardan, Louis

    2011-03-01

    Eight Erwinia strains, isolated from necrotic pear blossoms in València, Spain, were compared with reference strains of Erwinia amylovora and Erwinia pyrifoliae, both of which are pathogenic to species of pear tree, and to other species of the family Enterobacteriaceae using a polyphasic approach. Phenotypic analyses clustered the novel isolates into one phenon, distinct from other species of the genus Erwinia, showing that the novel isolates constituted a homogeneous phenotypic group. Rep-PCR profiles, PCR products obtained with different pairs of primers and plasmid contents determined by restriction analysis showed differences between the novel strains and reference strains of E. amylovora and E. pyrifoliae. Phylogenetic analysis of 16S rRNA, gpd and recA gene sequences showed that the eight novel strains could not be assigned to any recognized species. On the basis of DNA-DNA hybridization studies, the novel isolates constituted a single group with relatedness values of 87-100  % to the designated type strain of the group, CFBP 5888(T). Depending on the method used, strain CFBP 5888(T) showed DNA-DNA relatedness values of between 22.7 and 50  % to strains of the closely related species E. amylovora and E. tasmaniensis. The DNA G+C contents of two of the novel strains, CFBP 5888(T) and CFBP 5883, were 51.1 and 50.5 mol%, respectively. On the basis of these and previous results, the novel isolates represent a novel species of the genus Erwinia, for which the name Erwinia piriflorinigrans sp. nov. is proposed. The type strain is CFBP 5888(T) (=CECT 7348(T)).

  4. The genome of the Erwinia amylovora phage PhiEaH1 reveals greater diversity and broadens the applicability of phages for the treatment of fire blight.

    Science.gov (United States)

    Meczker, Katalin; Dömötör, Dóra; Vass, János; Rákhely, Gábor; Schneider, György; Kovács, Tamás

    2014-01-01

    The enterobacterium Erwinia amylovora is the causal agent of fire blight. This study presents the analysis of the complete genome of phage PhiEaH1, isolated from the soil surrounding an E. amylovora-infected apple tree in Hungary. Its genome is 218 kb in size, containing 244 ORFs. PhiEaH1 is the second E. amylovora infecting phage from the Siphoviridae family whose complete genome sequence was determined. Beside PhiEaH2, PhiEaH1 is the other active component of Erwiphage, the first bacteriophage-based pesticide on the market against E. amylovora. Comparative genome analysis in this study has revealed that PhiEaH1 not only differs from the 10 formerly sequenced E. amylovora bacteriophages belonging to other phage families, but also from PhiEaH2. Sequencing of more Siphoviridae phage genomes might reveal further diversity, providing opportunities for the development of even more effective biological control agents, phage cocktails against Erwinia fire blight disease of commercial fruit crops.

  5. Erwinia mallotivora sp., a new pathogen of papaya (Carica papaya) in Peninsular Malaysia.

    Science.gov (United States)

    Amin, Noriha Mat; Bunawan, Hamidun; Redzuan, Rohaiza Ahmad; Jaganath, Indu Bala S

    2010-12-24

    Erwinia mallotivora was isolated from papaya infected with dieback disease showing the typical symptoms of greasy, water-soaked lesions and spots on leaves. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the genus Erwinia and was united in a monophyletic group with E. mallotivora DSM 4565 (AJ233414). Earlier studies had indicated that the causal agent for this disease was E. papayae. However, our current studies, through Koch's postulate, have confirmed that papaya dieback disease is caused by E. mallotivora. To our knowledge, this is the first new discovery of E. mallotivora as a causal agent of papaya dieback disease in Peninsular Malaysia. Previous reports have suggested that E. mallotivora causes leaf spot in Mallotus japonicus. However, this research confirms it also to be pathogenic to Carica papaya.

  6. Erwinia mallotivora sp., a New Pathogen of Papaya (Carica papaya in Peninsular Malaysia

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    Noriha Mat Amin

    2010-12-01

    Full Text Available Erwinia mallotivora was isolated from papaya infected with dieback disease showing the typical symptoms of greasy, water-soaked lesions and spots on leaves. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the genus Erwinia and was united in a monophyletic group with E. mallotivora DSM 4565 (AJ233414. Earlier studies had indicated that the causal agent for this disease was E. papayae. However, our current studies, through Koch’s postulate, have confirmed that papaya dieback disease is caused by E. mallotivora. To our knowledge, this is the first new discovery of E. mallotivora as a causal agent of papaya dieback disease in Peninsular Malaysia. Previous reports have suggested that E. mallotivora causes leaf spot in Mallotus japonicus. However, this research confirms it also to be pathogenic to Carica papaya.

  7. Characterisation of the stbD/E toxin-antitoxin system of pEP36, a plasmid of the plant pathogen Erwinia pyrifoliae.

    Science.gov (United States)

    Unterholzner, Simon J; Hailer, Barbara; Poppenberger, Brigitte; Rozhon, Wilfried

    2013-09-01

    pEP36 is a plasmid ubiquitously present in Erwinia pyrifoliae, a pathogen which causes black stem blight of Asian pear. pEP36 is highly stable in its host, even in the absence of selective pressure. The plasmid is closely related to pEA29, which is widespread in E. amylovora, the causative agent of fire blight of apple and pear trees. Here we report that pEP36 possesses a functional hybrid toxin-antitoxin module, stbD/E(pEP36), with the toxin showing homology to the RelE/ParE proteins and the antidote belonging to the Phd/YefM antitoxin family. Bacteria expressing the StbE(pEP36) toxin arrest cell growth and enter a viable but non-culturable stage. However, they maintain their typical cell length and do not show filamentation. Pulse-chase experiments revealed that StbE(pEP36) acts as a global inhibitor of protein synthesis while it does not interfere with DNA and RNA synthesis. The StbD(pEP36) antitoxin is capable of neutralising StbE(pEP36) toxicity. Additional experiments show that the stbD/E(pEP36) module can stabilise plasmids at least 20-fold. Thus the toxin-antitoxin system may contribute to the remarkable stability of pEP36.

  8. Plasmid Content of Isolates of Erwinia amylovora from Orchards in Washington and Oregon in the USA

    Science.gov (United States)

    Washington (WA) and Oregon (OR) represent a major pome fruit production region of the United States, and streptomycin-resistant isolates of the fire blight pathogen Erwinia amylovora are common in orchards in this region. We examined the plasmid content of a collection of more than 200 isolates of ...

  9. Comparative genomics of Japanese Erwinia pyrifoliae strain Ejp617 with closely related erwinias.

    Science.gov (United States)

    Thapa, Shree P; Park, Duck H; Kim, Won S; Choi, Beom S; Lim, Jong S; Choi, Ik Y; Hur, Jang H; Lim, Chun K

    2013-02-01

    Japanese Erwinia pyrifoliae strains cause bacterial shoot blight of pear (BSBP) in Japan. The genetics of Japanese Erwinia remains largely unknown relative to the abundant genomic information available for other Erwinia strains. We compared the genome of Japanese and Korean E. pyrifoliae strains along with those of E. amylovora and E. tasmaniensis. Comparisons with the Korean E. pyrifoliae strain revealed numerous gene insertions/deletions, rearrangements, and inversions in the central regions of the chromosomes. Approximately 80% (2843) of coding DNA sequences (CDSs) are shared by these two genomes which represent about three-quarters of the genome, and there are about 20% unique CDSs. Comparative analysis with closely related erwinias showed that 1942 (more than 50%) core open reading frames (ORF) are shared by all these strains. In addition to two type III secretion systems (hrp/dsp and inv/spa), the genome of Ejp617 encodes numerous virulence factors, including a type VI secretion system, an exopolysaccharide synthesis cluster, and another protein secretion system present in plant pathogenic Erwinia strains. The availability of whole genome sequence should provide a resource to further improve the understanding of pathogenesis in Japanese E. pyrifoliae Ejp617 and to facilitate evolutionary studies among the species of the genus Erwinia.

  10. Same ammo, different weapons: enzymatic extracts from two apple genotypes with contrasted susceptibilities to fire blight (Erwinia amylovora) differentially convert phloridzin and phloretin in vitro.

    Science.gov (United States)

    Gaucher, Matthieu; Dugé de Bernonville, Thomas; Guyot, Sylvain; Dat, James F; Brisset, Marie-Noëlle

    2013-11-01

    The necrogenic bacterium Erwinia amylovora responsible for the fire blight disease causes cell death in apple tissues to enrich intercellular spaces with nutrients. Apple leaves contain large amounts of dihydrochalcones (DHCs), including phloridzin and its aglycone phloretin. Previous work showed an important decrease in the constitutive DHCs stock in infected leaves, probably caused by transformation reactions during the infection process. At least two flavonoid transformation pathways have been described so far: deglucosylation and oxidation. The aim of the present study was to determine whether DHCs are differentially converted in two apple genotypes displaying contrasted susceptibilities to the disease. Different analyses were performed: i) enzymatic activity assays in infected leaves, ii) identification/quantification of end-products obtained after in vitro enzymatic reactions with DHCs, iii) evaluation of the bactericidal activity of end-products. The results of the enzymatic assays showed that deglucosylation was dominant over oxidation in the susceptible genotype MM106 while the opposite was observed in the resistant genotype Evereste. These data were confirmed by LC-UV/Vis-MS analysis of in vitro reaction mixtures, especially because higher levels of o-quinoid oxidation products of phloretin were measured by using the enzymatic extracts of Evereste infected leaves. Their presence correlated well with a strong bactericidal activity of the reaction mixtures. Thus, our results suggest that a differential transformation of DHCs occur in apple genotypes with a potential involvement in the establishment of the susceptibility or the resistance to fire blight, through the release of glucose or of highly bactericidal compounds respectively.

  11. Controlled release of Pantoea agglomerans E325 for biocontrol of fire blight

    Science.gov (United States)

    Microencapsulation and controlled release of Pantoea agglomerans strain E325 (E325), which is an antagonist to bacterial pathogen (Erwinia amylovora) of fire blight, a devastating disease of apple and pear, have been investigated. Uniform core-shell alginate microcapsules (AMCs), 60-300 µm in diamet...

  12. Using functional genomics to develop tools to breed fire blight resistant apples

    Science.gov (United States)

    Fire blight, caused by the bacterium Erwinia amylovora, is a destructive disease of apple (Malus), pear (Pyrus) and other plants in the rose family (Rosaceae). Suppression subtractive hybridization (SSH) using cDNA from pathogen and mock-inoculated samples, and cDNA-AFLP analysis were used to ident...

  13. Evolutionary insights from Erwinia amylovora genomics.

    Science.gov (United States)

    Smits, Theo H M; Rezzonico, Fabio; Duffy, Brion

    2011-08-20

    Evolutionary genomics is coming into focus with the recent availability of complete sequences for many bacterial species. A hypothesis on the evolution of virulence factors in the plant pathogen Erwinia amylovora, the causative agent of fire blight, was generated using comparative genomics with the genomes E. amylovora, Erwinia pyrifoliae and Erwinia tasmaniensis. Putative virulence factors were mapped to the proposed genealogy of the genus Erwinia that is based on phylogenetic and genomic data. Ancestral origin of several virulence factors was identified, including levan biosynthesis, sorbitol metabolism, three T3SS and two T6SS. Other factors appeared to have been acquired after divergence of pathogenic species, including a second flagellar gene and two glycosyltransferases involved in amylovoran biosynthesis. E. amylovora singletons include 3 unique T3SS effectors that may explain differential virulence/host ranges. E. amylovora also has a unique T1SS export system, and a unique third T6SS gene cluster. Genetic analysis revealed signatures of foreign DNA suggesting that horizontal gene transfer is responsible for some of these differential features between the three species.

  14. Population genomics of Fusarium graminearum head blight pathogens in North America

    Science.gov (United States)

    In this study we utilized comparative genomics to identify candidate adaptive alleles in the fungus Fusarium graminearum, the primary pathogen of Fusarium head blight (FHB) in cereal crops. Recent epidemics of FHB have been economically devastating to agriculture, as F. graminearum reduces cereal yi...

  15. Control of fire blight by Pseudomonas fluorescens A506 and Pantoea vagans C9-1 applied as single strains and mixed inocula

    Science.gov (United States)

    The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in ten field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to b...

  16. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars

    OpenAIRE

    Cornelia Chizzali; Swiddan, Asya K.; Sahar Abdelaziz; Mariam Gaid; Klaus Richter; Fischer, Thilo C.; Benye Liu; Ludger Beerhues

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regard...

  17. Low genetic diversity among pathogenic strains of Erwinia psidii from Brazil Baixa diversidade genética entre estirpes patogênicas de Erwinia psidii no Brasil

    Directory of Open Access Journals (Sweden)

    Ana C. O. Teixeira

    2009-09-01

    Full Text Available Erwinia psidii causes bacterial disease of guava in Brazil. Phenotypic and molecular characterization through rep-PCR fingerprinting of 42 strains from different geographical regions showed that E. psidii populations in Brazil have a low level of genetic diversity and suggest that contaminated plant material is the main source for pathogen dissemination in the country.Erwinia psidii é o agente causal da seca-dos-ponteiros ou bacteriose da goiabeira no Brasil. A caracterização fenotípica e molecular através de rep-PCR de 42 estirpes patogênicas de diferentes regiões mostrou que as populações de E. psidii no Brasil têm um baixo nível de diversidade genética e sugere que material de propagação infectado é a principal fonte de disseminação do patógeno para novas áreas no país.

  18. Pathogenic reaction of some introduced rice cultivars (lines) to seven pathotypes of bacterial blight in Hangzhou

    Institute of Scientific and Technical Information of China (English)

    SHENYing; ZHUPeiliang; YUANXiaoping

    1993-01-01

    Bacterial blight (BB) caused by Xanthomonas oryzae pv.oryzae (Xoo) is a major rice disease in China. 138 introduced cultivars (lines) were tested on pathogenicity with seven pathotypes of BB at CNRRI Experiment Station during Apt-Oct,1991.

  19. Molecular characterization and pathogenicity of Erwinia spp. associated with pineapple [Ananas comosus (L. Merr.] and papaya (Carica papaya L.

    Directory of Open Access Journals (Sweden)

    Ramachandran Kogeethavani

    2015-12-01

    Full Text Available The Erwinia species are well-known pathogens of economic importance in Malaysia causing serious damage to high-value fruit crops that include pineapple [Ananas comosus (L. Merr.] and papaya (Carica papaya L..The 16S rRNA sequence using eubacteria fD1 and rP2 primers, identified two bacteria species; Dickeya zeae from pineapple heart rot, and Erwinia mallotivora from papaya dieback. Phylogenetic analysis based on the neighbor-joining method indicated that all the bacterial isolates clustered in their own taxa and formed monophyletic clades. From the pathogenicity test, all isolates of D. zeae and E. mallotivora showed pathogenic reactions on their respective host plants. Genetic variability of these isolates was assessed using repetitive sequence-based PCR (rep-PCR fingerprinting. The results indicated interspecies, and intraspecies variation in both species’ isolates. There were more polymorphic bands shown by rep-PCR fingerprints than enterobacterial repetitive intergenic consensus (ERIC and BOX- PCRs, however both species’ isolates produced distinguishable banding patterns. Unweighted pair-group method with arithmetic averages (UPGMA cluster analysis indicated that all Dickeya and Erwinia isolates from the same species were grouped in the same main cluster. Similarity among the isolates ranged from 77 to 99%. Sequencing of 16S rRNA using eubacteria fD1 and rP2 primers, and rep-PCR fingerprinting revealed diversity among Dickeya and Erwinia isolates. But this method appears to be reliable for discriminating isolates from pineapple heart rot and papaya dieback.

  20. Interaction entre des mutants hrp d'Erwinia amylovora, agent du feu bactérien, le parent pathogène et la plante hôte : recherche de mécanismes modulant la compatibilité

    OpenAIRE

    Cesbron, Sophie

    2009-01-01

    Erwinia amylovora is the causal agent of fire blight, a disease that affects Maloideae. This gammaproteobacteria requires a type three secretion system (T3SS) for its pathogenicity. Previous work has shown that avirulent hrp mutant strains of E. amylovora affected in regulatory functions (hrpL and hrpS) protect apple seedlings from developping fire blight symptoms. We investigated molecular mechanisms leading to this protection. In a first part of our work, we studied molecular responses of t...

  1. Comparative Genomics of Erwinia amylovora and Related Erwinia Species—What do We Learn?

    Directory of Open Access Journals (Sweden)

    Youfu Zhao

    2011-09-01

    Full Text Available Erwinia amylovora, the causal agent of fire blight disease of apples and pears, is one of the most important plant bacterial pathogens with worldwide economic significance. Recent reports on the complete or draft genome sequences of four species in the genus Erwinia, including E. amylovora, E. pyrifoliae, E. tasmaniensis, and E. billingiae, have provided us near complete genetic information about this pathogen and its closely-related species. This review describes in silico subtractive hybridization-based comparative genomic analyses of eight genomes currently available, and highlights what we have learned from these comparative analyses, as well as genetic and functional genomic studies. Sequence analyses reinforce the assumption that E. amylovora is a relatively homogeneous species and support the current classification scheme of E. amylovora and its related species. The potential evolutionary origin of these Erwinia species is also proposed. The current understanding of the pathogen, its virulence mechanism and host specificity from genome sequencing data is summarized. Future research directions are also suggested.

  2. The luxS gene is involved in AI-2 production, pathogenicity, and some phenotypes in Erwinia amylovora.

    Science.gov (United States)

    Gao, Yan; Song, Junxian; Hu, Baishi; Zhang, Lei; Liu, Qianqian; Liu, Fengquan

    2009-01-01

    Erwinia amylovora causes fire blight of apple, pear, and other members of the Rosaceae family. The enzyme LuxS catalyzes the last step in the production of autoinducer-2 (AI-2), a molecule implicated with quorum sensing in many bacterial species. It is now well recognized that LuxS also plays a central role in sulfur metabolism and in the activated methyl cycle, which is responsible for the generation of S-adenosyl-L-methionine. A research paper has reported that luxS is not involved with quorum sensing in Er. amylovora, but in our study, Er. amylovora strain NCPPB1665 (Ea1665) produced luxS-dependent extracellular AI-2 activity. Additionally, the maximal AI-2 activity occurred during late-exponential and early-stationary growth phases and diminished during the stationary phase. The luxS mutant of Ea1665 was constructed, and the phenotypes of a defined luxS mutant have been characterized. Inactivation of luxS in Ea1665 impaired motility, extracellular polysaccharide (EPS) production, and tolerance for hydrogen peroxide, and reduced virulence on pear leaves.

  3. Studies on fire blight.

    NARCIS (Netherlands)

    Schouten, H.J.

    1991-01-01

    Part 1Effects of water potential and temperature on multiplication of and pressure by Erwinia amylovora in host plantsAnalysis of field data from Eve Billing, England, on the duration of the incubation period of fire blight revealed that temperature and rainfall wer

  4. Novel insights into the emergence of pathogens: the case of chestnut blight.

    Science.gov (United States)

    Grünwald, Niklaus J

    2012-08-01

    Exotic, invasive pathogens have emerged repeatedly and continue to emerge to threaten the world's forests. Ecosystem structure and function can be permanently changed when keystone tree species such as the American chestnut (Castanea dentata) are eliminated from a whole range by disease. The fungal ascomycete pathogen Cryphonectria parasitica is responsible for causing chestnut blight. Once the pathogen was introduced into the Eastern US, where chestnuts were predominant, chestnuts were all but eliminated. This pathogen is currently causing extensive damage in Europe. A study in this issue of Molecular Ecology sheds new light on the pattern and process of emergence of this devastating plant pathogen (Dutech et al. 2012). The authors used microsatellite markers to investigate the evolutionary history of C. parasitica populations introduced into North America and Europe. To infer sources of migrants and the migration events, the authors included putative source populations endemic to China and Japan, inferred potentially unsampled populations and conducted a multivariate population genetic and complex ABC analysis. Cryphonectria parasitica emerges as an example of an introduced pathogen with limited genotypic diversity and some admixture in the invaded ranges, yet repeated invasions into different areas of Europe and the United States. This work sheds new light on the emergence of C. parasitica providing compelling evidence that this pathogen emerged by repeated migration and occasional admixture.

  5. Research Status and Prospect ofBurkholderia glumae, the Pathogen Causing Bacterial Panicle Blight

    Institute of Scientific and Technical Information of China (English)

    CUI Zhou-qi; ZHU Bo; XIE Guan-lin; LI Bin; HUANG Shi-wen

    2016-01-01

    Bacterial panicle blight caused by Burkholderia glumae is one of the most severe seed-borne bacterial diseases of rice in the world. Currently, this disease has affected many countries of Asia, Africa, South and North America. It is a typical example of the shifting from minor plant disease to major disease due to the changes of environmental conditions. Some virulent factors of B. glumae have been identified, including toxoflavins and lipases, whose productions are dependent on the TofI/TofR quorum-sensing system, and type III effectors. In spite of its economic significance, neither effective control measure for this disease nor resistant rice variety is currently available. In recent years, genomics, transcriptomics and other molecular methods have provided useful information for better understanding the molecular mechanisms underlyingB. glumaevirulence and the rice defence mechanisms against pathogens. For the prevention of this pathogen, our laboratory has developed a rapid and sensitive multiplex PCR assay for detecting and distinguishingB. glumae from otherBurkholderia species. This improved understanding ofB. glumae will shed new light on bacterial panicle blight disease management.

  6. Apple (Malus x domestica) transcriptome in response to the compatible pathogen Erwinia amylovora and the incompatible pathogen Pseudomonas syringae

    Science.gov (United States)

    Infiltration of Erwinia amylovora (Ea) into host leaves induces an oxidative burst similar to that observed during incompatible reactions associated with Hypersensitive Response (HR). However, the subsequent progressive development of necrosis in apple and other hosts is unlike an incompatible reac...

  7. Expression of viral EPS-depolymerase reduces fire blight susceptibility in transgenic pear.

    Science.gov (United States)

    Malnoy, Mickaël; Faize, Mohamed; Venisse, Jean-Stéphane; Geider, Klaus; Chevreau, Elisabeth

    2005-02-01

    Erwinia amylovora is the causal agent of fire blight of Maloideae. One of the main pathogenicity factors of this bacterium is the exopolysaccharide (EPS) of its capsule. In this paper, we used genetic transformation tools to constitutively express an EPS-depolymerase transgene in the pear (Pyrus communis L.) cv. Passe Crassane with the aim of decreasing its high susceptibility to fire blight. Expression of the depolymerase gene in 15 independent transgenic clones led, on average, to low depolymerase activity, although relatively high expression was observed at the transcriptional and translational levels. Only two of the transgenic clones (9X and 10M) consistently showed a decrease in fire blight susceptibility in vitro and in the greenhouse. These clones were also among the highest expressers of depolymerase at the RNA and enzyme activity levels. The correlation observed among all transgenic clones between depolymerase expression and fire blight resistance suggested the potential of this strategy.

  8. Export of the HR eliciting protein, Harpin(Es), of the maize pathogen Erwinia stewartii is species-specific but is independent of the growth temperature.

    Science.gov (United States)

    Ahmad, Musharaf; Alam, Syed Sartaj; Alam, Shah; Usman, Amjad; Coplin, David L

    2007-01-01

    The extra-cellular export of the HR-eliciting protein, Harpin(Es) of the maize pathogen Erwinia stewartii was studied to find out if the protein needs any species-specific signal for its export and to determine if the export of the protein to the medium is affected in any way by the growth temperature. Based upon the experimental evidence, it was proved that the protein (i.e., Harpin(Es)) does require its own export system (species-specific) to get out of the bacterial cell and can not be exported by the export system of even the very closely related bacterium, Erwinia amylovora. It was also found that the export of Harpin(Es) is, unlike the case of Harpin(Ea) (HR-eliciting protein of Erwinia amylovora), independent of the growth temperature.

  9. Contrasting Potato Foliage and Tuber Defense Mechanisms against the Late Blight Pathogen Phytophthora infestans.

    Directory of Open Access Journals (Sweden)

    Liangliang Gao

    Full Text Available The late blight pathogen Phytophthora infestans can attack both potato foliage and tubers. When inoculated with P. infestans, foliage of nontransformed 'Russet Burbank' (WT develops late blight disease while that of transgenic 'Russet Burbank' line SP2211 (+RB does not. We compared the foliar transcriptome responses of these two lines to P. infestans inoculation using an RNA-seq approach. A total of 515 million paired end RNA-seq reads were generated, representing the transcription of 29,970 genes. We also compared the differences and similarities of defense mechanisms against P. infestans in potato foliage and tubers. Differentially expressed genes, gene groups and ontology bins were identified to show similarities and differences in foliage and tuber defense mechanisms. Our results suggest that R gene dosage and shared biochemical pathways (such as ethylene and stress bins contribute to RB-mediated incompatible potato-P. infestans interactions in both the foliage and tubers. Certain ontology bins such as cell wall and lipid metabolisms are potentially organ-specific.

  10. Action and reaction of host and pathogen during Fusarium head blight disease.

    Science.gov (United States)

    Walter, Stephanie; Nicholson, Paul; Doohan, Fiona M

    2010-01-01

    The Fusarium species Fusarium graminearum and Fusarium culmorum, which are responsible for Fusarium head blight (FHB) disease, reduce world-wide cereal crop yield and, as a consequence of their mycotoxin production in cereal grain, impact on both human and animal health. Their study is greatly promoted by the availability of the genomic sequence of F. graminearum and transcriptomic resources for both F. graminearum and its cereal hosts. Functional genomic, proteomic and metabolomic studies, in combination with targeted mutagenesis or transgenic studies, are unravelling the complex mechanisms involved in Fusarium infection, penetration and colonization of host tissues, and host avoidance thereof. This review illuminates and integrates emerging knowledge regarding the molecular crosstalk between Fusarium and its small-grain cereal hosts. An understanding of the complexity of the host-pathogen interactions will be instrumental in designing new efficient strategies for the control of FHB disease.

  11. Quantitative analysis of resistance in cotton to three new isolates of the bacterial blight pathogen.

    Science.gov (United States)

    Wallace, T P; El-Zik, K M

    1990-04-01

    Genetic variability for virulence of the bacterial blight pathogen [Xanthomonas campestris pv malvacearum (Smith) Dye] on cotton (Gossypium hirsutum L.) has been shown by the identification of 19 races of the pathogen based on disease reactions of a set of ten host differentials. This study was conducted to determine the inheritance of host resistance to three recently identified isolates of X. campestris pv malvacearum, which are virulent on the entire set of differentials. True leaves of Tamcot CAMD-E, LEBOCAS-3-80, Stoneville 825, and their f1, F2, and backcross progenies were wound-inoculated in the field with separate bacterial suspensions of the virulent HV3, HV7, and Sudan isolates of the pathogen. LEBOCAS-3-80 was replaced with S295, a new immune cultivar, for a greenhouse study in which both cotyledons and true leaves were inoculated. Disease reactions were rated on a scale of 1-10, and genetic models were proposed utilizing generation means analysis. Dominance, when significant, was in the direction of resistance in all but one cross-isolate combination. Digenic interaction components indicated a duplicate type. Narrow-sense heritability for resistance ranged from 0.59 to 0.68; therefore, primarily additive-genetic variability among the selected cutlivars was detected, indicating that breeding for improved resistance to these isolates is a practical goal.

  12. Analysis of apple (Malus) responses to bacterial pathogens using an oligo microarray

    Science.gov (United States)

    Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). When infiltrated into host leaves, Ea induces reactions similar to a hypersensitive response (HR). Type III (T3SS) associated effectors, especially DspA/E, are suspected to ha...

  13. Using an apple (Malus) microarray for expression analysis of responses to compatible and incompatible pathogens

    Science.gov (United States)

    Fire blight is a devastating disease of apple (Malus x domestica) caused by the bacterial pathogen Erwinia amylovora (Ea). Ea enters the plant through blossom nectaries or wounds, multiplies in the apoplast and spreads through the plant via vascular tissues. When infiltrated into host leaves, Ea ind...

  14. Molecular analyses of Erwinia amylovora strains isolated in Russia, Poland, Slovenia and Austria describing further spread of fire blight in Europe.

    Science.gov (United States)

    Jock, Susanne; Wensing, Annette; Pulawska, Joanna; Drenova, Nataliya; Dreo, Tanja; Geider, Klaus

    2013-08-25

    Fire blight, a bacteriosis of apple and pear, was assayed with molecular tools to associate its origin in Russia, Slovenia and south-eastern Austria with neighboring countries. The identification of all investigated strains was confirmed by MALDI-TOF mass spectroscopy except one. Independent isolation was verified by the level of amylovoran synthesis and by the number of short sequence DNA repeats in plasmid pEA29. DNA of gently lysed E. amylovora strains from Russia, Slovenia, Austria, Hungary, Italy, Spain, Croatia, Poland, Central Europe and Iran was treated with restriction enzymes XbaI and SpeI to create typical banding patterns for PFGE analysis. The pattern Pt2 indicated that most Russian E. amylovora strains were related to strains from Turkey and Iran. Strains from Slovenia exhibited patterns Pt3 and Pt2, both present in the neighboring countries. Strains were also probed for the recently described plasmid pEI70 detected in Pt1 strains from Poland and in Pt3 strains from other countries. The distribution of pattern Pt3 suggests distribution of fire blight from Belgium and the Netherlands to Central Spain and Northern Italy and then north to Carinthia. The PFGE patterns indicate that trade of plants may have introduced fire blight into southern parts of Europe proceeded by sequential spread.

  15. Structural Characterization of Core Region in Erwinia amylovora Lipopolysaccharide.

    Science.gov (United States)

    Casillo, Angela; Ziaco, Marcello; Lindner, Buko; Merino, Susana; Mendoza-Barberá, Elena; Tomás, Juan M; Corsaro, Maria Michela

    2017-03-04

    Erwinia amylovora (E. amylovora) is the first bacterial plant pathogen described and demonstrated to cause fire blight, a devastating plant disease affecting a wide range of species including a wide variety of Rosaceae. In this study, we reported the lipopolysaccharide (LPS) core structure from E. amylovora strain CFBP1430, the first one for an E. amylovora highly pathogenic strain. The chemical characterization was performed on the mutants waaL (lacking only the O-antigen LPS with a complete LPS-core), wabH and wabG (outer-LPS core mutants). The LPSs were isolated from dry cells and analyzed by means of chemical and spectroscopic methods. In particular, they were subjected to a mild acid hydrolysis and/or a hydrazinolysis and investigated in detail by one and two dimensional Nuclear Magnetic Resonance (NMR) spectroscopy and ElectroSpray Ionization Fourier Transform-Ion Cyclotron Resonance (ESI FT-ICR) mass spectrometry.

  16. Structural Characterization of Core Region in Erwinia amylovora Lipopolysaccharide

    Directory of Open Access Journals (Sweden)

    Angela Casillo

    2017-03-01

    Full Text Available Erwinia amylovora (E. amylovora is the first bacterial plant pathogen described and demonstrated to cause fire blight, a devastating plant disease affecting a wide range of species including a wide variety of Rosaceae. In this study, we reported the lipopolysaccharide (LPS core structure from E. amylovora strain CFBP1430, the first one for an E. amylovora highly pathogenic strain. The chemical characterization was performed on the mutants waaL (lacking only the O-antigen LPS with a complete LPS-core, wabH and wabG (outer-LPS core mutants. The LPSs were isolated from dry cells and analyzed by means of chemical and spectroscopic methods. In particular, they were subjected to a mild acid hydrolysis and/or a hydrazinolysis and investigated in detail by one and two dimensional Nuclear Magnetic Resonance (NMR spectroscopy and ElectroSpray Ionization Fourier Transform-Ion Cyclotron Resonance (ESI FT-ICR mass spectrometry.

  17. Structural Characterization of Core Region in Erwinia amylovora Lipopolysaccharide

    Science.gov (United States)

    Casillo, Angela; Ziaco, Marcello; Lindner, Buko; Merino, Susana; Mendoza-Barberá, Elena; Tomás, Juan M.; Corsaro, Maria Michela

    2017-01-01

    Erwinia amylovora (E. amylovora) is the first bacterial plant pathogen described and demonstrated to cause fire blight, a devastating plant disease affecting a wide range of species including a wide variety of Rosaceae. In this study, we reported the lipopolysaccharide (LPS) core structure from E. amylovora strain CFBP1430, the first one for an E. amylovora highly pathogenic strain. The chemical characterization was performed on the mutants waaL (lacking only the O-antigen LPS with a complete LPS-core), wabH and wabG (outer-LPS core mutants). The LPSs were isolated from dry cells and analyzed by means of chemical and spectroscopic methods. In particular, they were subjected to a mild acid hydrolysis and/or a hydrazinolysis and investigated in detail by one and two dimensional Nuclear Magnetic Resonance (NMR) spectroscopy and ElectroSpray Ionization Fourier Transform-Ion Cyclotron Resonance (ESI FT-ICR) mass spectrometry. PMID:28273861

  18. Iron homeostasis and fire blight susceptibility in transgenic pear plants overexpressing a pea ferritin gene.

    Science.gov (United States)

    Djennane, Samia; Cesbron, Colette; Sourice, Sophie; Cournol, Raphael; Dupuis, Fabrice; Eychenne, Magali; Loridon, Karine; Chevreau, Elisabeth

    2011-05-01

    The bacterial pathogen Erwinia amylovora causes the devastating disease known as fire blight in some rosaceous plants including apple and pear. One of the pathogenicity factors affecting fire blight development is the production of a siderophore, desferrioxamine, which overcomes the limiting conditions in plant tissues and also protects bacteria against active oxygen species. In this paper we examine the effect of an iron chelator protein encoded by the pea ferritin gene on the fire blight susceptibility of pear (Pyrus communis). Transgenic pear clones expressing this gene controlled either by the constitutive promoter CaMV 35S or by the inducible promoter sgd24 promoter were produced. The transgenic clones produced were analysed by Q-RT-PCR to determine the level of expression of the pea transgene. A pathogen-inducible pattern of expression of the pea transgene was observed in sgd24-promoter transformants. Adaptation to iron deficiency in vitro was tested in some transgenic clones and different iron metabolism parameters were measured. No strong effect on iron and chlorophyll content, root reductase activity and fire blight susceptibility was detected in the transgenic lines tested. No transformants showed a significant reduction in susceptibility to fire blight in greenhouse conditions when inoculated with E. amylovora.

  19. Species tree estimation for the late blight pathogen, Phytophthora infestans, and close relatives.

    Directory of Open Access Journals (Sweden)

    Jaime E Blair

    Full Text Available To better understand the evolutionary history of a group of organisms, an accurate estimate of the species phylogeny must be known. Traditionally, gene trees have served as a proxy for the species tree, although it was acknowledged early on that these trees represented different evolutionary processes. Discordances among gene trees and between the gene trees and the species tree are also expected in closely related species that have rapidly diverged, due to processes such as the incomplete sorting of ancestral polymorphisms. Recently, methods have been developed for the explicit estimation of species trees, using information from multilocus gene trees while accommodating heterogeneity among them. Here we have used three distinct approaches to estimate the species tree for five Phytophthora pathogens, including P. infestans, the causal agent of late blight disease in potato and tomato. Our concatenation-based "supergene" approach was unable to resolve relationships even with data from both the nuclear and mitochondrial genomes, and from multiple isolates per species. Our multispecies coalescent approach using both Bayesian and maximum likelihood methods was able to estimate a moderately supported species tree showing a close relationship among P. infestans, P. andina, and P. ipomoeae. The topology of the species tree was also identical to the dominant phylogenetic history estimated in our third approach, Bayesian concordance analysis. Our results support previous suggestions that P. andina is a hybrid species, with P. infestans representing one parental lineage. The other parental lineage is not known, but represents an independent evolutionary lineage more closely related to P. ipomoeae. While all five species likely originated in the New World, further study is needed to determine when and under what conditions this hybridization event may have occurred.

  20. Comparative analysis of the Hrp pathogenicity island of Rubus- and Spiraeoideae-infecting Erwinia amylovora strains identifies the IT region as a remnant of an integrative conjugative element.

    Science.gov (United States)

    Mann, Rachel A; Blom, Jochen; Bühlmann, Andreas; Plummer, Kim M; Beer, Steven V; Luck, Joanne E; Goesmann, Alexander; Frey, Jürg E; Rodoni, Brendan C; Duffy, Brion; Smits, Theo H M

    2012-08-01

    The Hrp pathogenicity island (hrpPAI) of Erwinia amylovora not only encodes a type III secretion system (T3SS) and other genes required for pathogenesis on host plants, but also includes the so-called island transfer (IT) region, a region that originates from an integrative conjugative element (ICE). Comparative genomic analysis of the IT regions of two Spiraeoideae- and three Rubus-infecting strains revealed that the regions in Spiraeoideae-infecting strains were syntenic and highly conserved in length and genetic information, but that the IT regions of the Rubus-infecting strains varied in gene content and length, showing a mosaic structure. None of the ICEs in E. amylovora strains were complete, as conserved ICE genes and the left border were missing, probably due to reductive genome evolution. Comparison of the hrpPAI region of E. amylovora strains to syntenic regions from other Erwinia spp. indicates that the hrpPAI and the IT regions are the result of several insertion and deletion events that have occurred within the ICE. It also suggests that the T3SS was present in a common ancestor of the pathoadapted Erwinia spp. and that insertion and deletion events in the IT region occurred during speciation.

  1. Characterization of a cfr-Carrying Plasmid from Porcine Escherichia coli That Closely Resembles Plasmid pEA3 from the Plant Pathogen Erwinia amylovora.

    Science.gov (United States)

    Zhang, Rongmin; Sun, Bin; Wang, Yang; Lei, Lei; Schwarz, Stefan; Wu, Congming

    2015-11-02

    The multiresistance gene cfr was found in two porcine Escherichia coli isolates, one harboring it on the conjugative 33,885-bp plasmid pFSEC-01, the other harboring it in the chromosomal DNA. Sequence analysis of pFSEC-01 revealed that a 6,769-bp fragment containing the cfr gene bracketed by two IS26 elements was inserted into a plasmid closely related to pEA3 from the plant pathogen Erwinia amylovora, suggesting that pFSEC-01 may be transferred between different bacterial genera of both animal and plant origin.

  2. Molecular dynamics of interactions of rice with rice blast and sheath blight pathogens

    Science.gov (United States)

    In an effort to develop the molecular strategies to control rice (Oryzae sativa) diseases, molecular interactions of rice with rice blast [Magnaporthe oryzae, formerly (Magnaporthe grisea] and sheath blight (Rhizoctonia solani) fungi were analyzed. The interaction of rice with M. oryzae follows a b...

  3. Action and reaction of host and pathogen during Fusarium head blight disease

    DEFF Research Database (Denmark)

    Walter, Stephanie; Nicholson, Paul; Doohan, Fiona M

    2010-01-01

    The Fusarium species Fusarium graminearum and Fusarium culmorum, Which are responsible for Fusarium head blight (FHB) disease, reduced world-wide cereal crop yield and, as a consequence of their mycotoxin production in cereal grain, impact on both human and animal health. Their study is greatly p...

  4. Secondary metabolites of rice sheath blight pathogenRhizoctonia solaniKühn and their biological activities

    Institute of Scientific and Technical Information of China (English)

    XU Liang; WANG Xiao-han; LUO Rui-ya; LU Shi-qiong; GUO Ze-jian; WANG Ming-an; LIU Yang; ZHOU Li-gang

    2015-01-01

    Eight compounds were isolated from the fermentation cultures of rice sheath blight pathogenRhizoctonia solaniKühn. They were identiifed as ergosterol (1), 6β-hydroxysitostenone (2), sitostenone (3),m-hydroxyphenylacetic acid (4), methylm-hydroxyphenylacetate (5),m-hydroxymethylphenyl pentanoate (6), (Z)-3-methylpent-2-en-1,5-dioic acid (7) and 3-methoxyfuran-2-carboxylic acid (8) by means of physicochemical and spectroscopic analysis. Among them,2,3,5–8 were isolated fromR. solani for the ifrst time. Al the compounds were evaluated for their biological activities.4–6 and8 showed their inhibitory activities on the radical and germ elongation of rice seeds.1,4 and7 showed moderate antibacterial activity to some bacteria.4,7 and8 exhibited weak inhibitory activities on spore germination ofMagnaporthe oryzae.8 showed moderate antioxidant activity with the 1,1-diphenyl-2-picryhydrazyl (DPPH) andβ-carotene-linoleic acid assays. This is the ifrst time to reveal compounds5,6 and8 from rice sheath blight pathogenR. solani to havein vitro phytotoxic activity.

  5. A gene cluster for amylovoran synthesis in Erwinia amylovora: characterization and relationship to cps genes in Erwinia stewartii.

    Science.gov (United States)

    Bernhard, F; Coplin, D L; Geider, K

    1993-05-01

    A large ams gene cluster required for production of the acidic extracellular polysaccharide (EPS) amylovoran by the fire blight pathogen Erwinia amylovora was cloned. Tn5 mutagenesis and gene replacement were used to construct chromosomal ams mutants. Five complementation groups, essential for amylovoran synthesis and virulence in E. amylovora, were identified and designated ams A-E. The ams gene cluster is about 7 kb in size and functionally equivalent to the cps gene cluster involved in EPS synthesis by the related pathogen Erwinia stewartii. Mucoidy and virulence were restored to E. stewartii mutants in four cps complementation groups by the cloned E. amylovora ams genes. Conversely, the E. stewartii cps gene cluster was able to complement mutations in E. amylovora ams genes. Correspondence was found between the amsA-E complementation groups and the cpsB-D region, but the arrangement of the genes appears to be different. EPS production and virulence were also restored to E. amylovora amsE and E. stewartii cpsD mutants by clones containing the Rhizobium meliloti exo A gene.

  6. Monitoring of Erwinia amylovora in Montenegro

    Directory of Open Access Journals (Sweden)

    Dragana Radunović

    2015-09-01

    Full Text Available Recent studies of Erwinia amylovora in Montenegro, conducted from 2012 to 2014, indicated that the bacterium was widespread in the northern, continental part of the country, where the most important fruit-growing regions are situated. The presence of the bacterium was confirmed on quince, pear, apple, medlar and hawthorn. Pathogenic, cultural and biochemical characteristics of E. amylovora strains sampled from pome fruit species and indigenous flora in Montenegro had been studied previously. In the present study, serological tests were used for identification of E. amylovora strains originating from pome fruit trees and indigenous plants. Monitoring of E. amylovora and collection of samples with symptoms of bacterial fire blight from different hosts and locations were performed in Montenegro from 2012 to 2014. Isolation of the bacterium on nutrient medium produced a large number of isolates, whose pathogenicity was confirmed on immature pear fruits. Twenty-seven strains of the bacterium, originating from three pome fruit species (quince, pear and apple and one indigenous species (hawthorn were selected for serological analyses. Two applied serological methods, ELISA and IF test, enabled rapid detection of the bacterium and simultaneous examination of a large number of samples over a short period of time. Serological analyses showed high homogeneity in antigenic structure of the studied E. amylovora strains sampled from quince, pear, apple and hawthorn from nine locations in Montenegro.

  7. Duplex real-time polymerase chain reaction reveals competition between Erwinia amylovora and E. pyrifoliae on pear blossoms.

    Science.gov (United States)

    Lehman, Susan M; Kim, Won-Sik; Castle, Alan J; Svircev, Antonet M

    2008-06-01

    Erwinia amylovora and E. pyrifoliae are the causative agents of fire blight and Asian pear blight, respectively. The pathogens are closely related, with overlapping host ranges. Data are unavailable on the current distribution of E. pyrifoliae and on the interaction between the two species when they are present together on the same host. In this study, a duplex real-time polymerase chain reaction (PCR) protocol was developed to monitor the population dynamics of E. amylovora and E. pyrifoliae on the surface of Bartlett pear blossoms. Bacterial cells washed from blossoms were used directly as the PCR template without DNA extraction. Primers and a probe based on the E. amylovora levansucrase gene detected all E. amylovora strains. All E. pyrifoliae strains, including the Japanese Erwinia strains previously described as E. amylovora, were detected with a primer and probe combination based on the E. pyrifoliae hrpW gene. Disease development and severity were not significantly different in blossoms inoculated with individual Erwinia species or with a mixture of the two species. However, E. amylovora grew to greater population sizes than did E. pyrifoliae in both single species inoculations and in mixtures, suggesting that E. amylovora has a greater competitive fitness on Bartlett pear blossoms than E. pyrifoliae.

  8. Sequencing of the Litchi Downy Blight Pathogen Reveals It Is a Phytophthora Species With Downy Mildew-Like Characteristics.

    Science.gov (United States)

    Ye, Wenwu; Wang, Yang; Shen, Danyu; Li, Delong; Pu, Tianhuizi; Jiang, Zide; Zhang, Zhengguang; Zheng, Xiaobo; Tyler, Brett M; Wang, Yuanchao

    2016-07-01

    On the basis of its downy mildew-like morphology, the litchi downy blight pathogen was previously named Peronophythora litchii. Recently, however, it was proposed to transfer this pathogen to Phytophthora clade 4. To better characterize this unusual oomycete species and important fruit pathogen, we obtained the genome sequence of Phytophthora litchii and compared it to those from other oomycete species. P. litchii has a small genome with tightly spaced genes. On the basis of a multilocus phylogenetic analysis, the placement of P. litchii in the genus Phytophthora is strongly supported. Effector proteins predicted included 245 RxLR, 30 necrosis-and-ethylene-inducing protein-like, and 14 crinkler proteins. The typical motifs, phylogenies, and activities of these effectors were typical for a Phytophthora species. However, like the genome features of the analyzed downy mildews, P. litchii exhibited a streamlined genome with a relatively small number of genes in both core and species-specific protein families. The low GC content and slight codon preferences of P. litchii sequences were similar to those of the analyzed downy mildews and a subset of Phytophthora species. Taken together, these observations suggest that P. litchii is a Phytophthora pathogen that is in the process of acquiring downy mildew-like genomic and morphological features. Thus P. litchii may provide a novel model for investigating morphological development and genomic adaptation in oomycete pathogens.

  9. INTEGRATED SYSTEMS IN PLANT PROTECTION MANAGEMENT: FIRE BLIGHT OF ROSACEOUS PLANTS (Erwinia amylovora (Burrill - Winslow IN AN APPLE ORCHARD IN SIBIU COUNTY

    Directory of Open Access Journals (Sweden)

    Maria TĂNASE

    2013-12-01

    Full Text Available Integrated protection represents a modern approach, denoting a protection strategy of agro-ecosystems; and it represents a complex system employing all appropriate methods in a manner as consistent and smooth as possible, in order to maintain the biocenotic balance of agrosystems and to keep pathogens at a level at which they do not cause economic damage (so-called level of eco-efficiency. A biocenotic approach to issues of agrosystem protection against disease attack requires an acknowledgement of all aspects regarding the evolution of pests in time and space, so as to be able to intervene at the right time with all possible means. And such protection measures are not supposed to restrain existing tendencies in the agrosystem. Therefore, this implies the awareness that any applied protection measures do not affect solely a certain pathogen, but the entire plant and animal community, as well as the soil and water.

  10. High levels of diversity and population structure in the potato late blight pathogen at the Mexico centre of origin.

    Science.gov (United States)

    Wang, Jianan; Fernández-Pavía, Sylvia P; Larsen, Meredith M; Garay-Serrano, Edith; Gregorio-Cipriano, Rosario; Rodríguez-Alvarado, Gerardo; Grünwald, Niklaus J; Goss, Erica M

    2017-02-01

    Globally destructive crop pathogens often emerge by migrating out of their native ranges. These pathogens are often diverse at their centre of origin and may exhibit adaptive variation in the invaded range via multiple introductions from different source populations. However, source populations are generally unidentified or poorly studied compared to invasive populations. Phytophthora infestans, the causal agent of late blight, is one of the most costly pathogens of potato and tomato worldwide. Mexico is the centre of origin and diversity of P. infestans and migration events out of Mexico have enormously impacted disease dynamics in North America and Europe. The debate over the origin of the pathogen, and population studies of P. infestans in Mexico, has focused on the Toluca Valley, whereas neighbouring regions have been little studied. We examined the population structure of P. infestans across central Mexico, including samples from Michoacán, Tlaxcala and Toluca. We found high levels of diversity consistent with sexual reproduction in Michoacán and Tlaxcala and population subdivision that was strongly associated with geographic region. We determined that population structure in central Mexico has contributed to diversity in introduced populations based on relatedness of U.S. clonal lineages to Mexican isolates from different regions. Our results suggest that P. infestans exists as a metapopulation in central Mexico, and this population structure could be contributing to the repeated re-emergence of P. infestans in the United States and elsewhere.

  11. Population Structure of the Late Blight Pathogen Phytophthora infestans in a Potato Germplasm Nursery in Two Consecutive Years.

    Science.gov (United States)

    Tian, Yuee; Yin, Junliang; Sun, Jieping; Ma, Hongmei; Ma, Yunfang; Quan, Junli; Shan, Weixing

    2015-06-01

    As the causal agent of late blight on potato, Phytophthora infestans is one of the most destructive plant pathogens worldwide and widely known as the Irish potato famine pathogen. Understanding the genetic structure of P. infestans populations is important both for breeding and deployment of resistant varieties and for development of disease control strategies. Here, we investigate the population genetic structure of P. infestans in a potato germplasm nursery in northwestern China. In total, 279 isolates were recovered from 63 potato varieties or lines in 2010 and 2011, and were genotyped by mitochondrial DNA haplotypes and a set of nine simple-sequence repeat markers. Selected isolates were further examined for virulence on a set of differential lines containing each resistance (R) gene (R1 to R11). The overall P. infestans population was characterized as having a low level of genetic diversity and resistance to metalaxyl, and containing a high percentage of individuals that virulent to all 11 R genes. Both A1 and A2 mating types as well as self-fertile P. infestans isolates were present but there was no evidence of sexual reproduction. The low level of genetic differentiation in P. infestans populations is probably due to the action of relatively high levels of migration as supported by analysis of molecular variance (P infestans population structure in the germplasm nursery. Therefore, it is important to ensure the production of pathogen-free potato seed tubers to aid sustainable production of potato in northwestern China.

  12. Reduction of lesion growth rate of late blight plant disease in transgenic potato expressing harpin protein

    Institute of Scientific and Technical Information of China (English)

    李汝刚; 范云六

    1999-01-01

    Using harpin protein gene from apple fire blight pathogen Erwinia amylavora and potato prp1-1 promoter as main DNA elements, the feasibility of using pathogen infection-induced hypersensitive response was explored as a new strategy of engineering fungal disease resistance. Three plant transformation vectors were constructed and 68 transgenic potato plants were produced through Agrobacterium mediated transformation method. Southern, Northern and Western blot analysis demonstrated the insertion, transcription and protein expression of harpin protein gene in transgenic plants. Disease resistance test using a complex race of Phytophthora infestans as challenging pathogen showed that both constitutive and pathogen infection-induced expression of harpin protein gene in transgenic potato reduced the lesion growth rate of fungus. Among plants where harpin protein gene expression was induced only by fungus infection, two plants were found to be highly resistant to P. infestans infection. Fungal hyphae were not pr

  13. [Polyvalence of bacteriophages isolated from fruit trees, affected by bacterial fire blight].

    Science.gov (United States)

    Tovkach, F I; Moroz, S N; Korol', N A; Faĭdiuk, Iu V; Kushkina, A I

    2013-01-01

    Phage populations appearing as a result of a pathogenic process caused by Erwinia amylovora have been discovered and described. They accompany bacterial fire blight development in the process of quince, pear and apple trees vegetation in Zakarpattya region of Ukraine. Phage isolates of the affected pear and quince include polyvalent virulent phages able to develop on bacterial strains associated with plants--E. amylovora. E. "horticola" and Pantoea agglomerans. E. amylovora isolated from the plant tissues affected by the fire blight and detected at the same time as phages proved to be resistant to the viral infection. It is hard to explain now this characteristic however it was noticed that resistance to phages can change drastically in case of dissociation, lysogenization and mutagenesis of erwinia in laboratory conditions. Phage population study shows that they are heterogeneous and can obviously include not only polyvalent but also specific viruses. Further studies of biology and molecular genetics of pure lines of isolated phages will help to get closer to understanding the place and role of bacteriophages in the complicated network of relations between bacterial pathogens and plants.

  14. Pantoea applied genomics to understand and improve biocontrol activity against fire blight

    Science.gov (United States)

    Pantoea agglomerans and P. vagans (ex. Erwinia herbicola) are common epiphytes of pome fruit flowers and three strains (E325, P10c, C9-1) have been commercially developed as effective biocontrol products for managing fire blight (Erwinia amylovora). Antibiotics as a standard, reliable chemical optio...

  15. Profiling the secretome and extracellular proteome of the potato late blight pathogen Phytophthora infestans.

    Science.gov (United States)

    Meijer, Harold J G; Mancuso, Francesco M; Espadas, Guadalupe; Seidl, Michael F; Chiva, Cristina; Govers, Francine; Sabidó, Eduard

    2014-08-01

    Oomycetes are filamentous organisms that cause notorious diseases, several of which have a high economic impact. Well known is Phytophthora infestans, the causal agent of potato late blight. Previously, in silico analyses of the genome and transcriptome of P. infestans resulted in the annotation of a large number of genes encoding proteins with an N-terminal signal peptide. This set is collectively referred to as the secretome and comprises proteins involved in, for example, cell wall growth and modification, proteolytic processes, and the promotion of successful invasion of plant cells. So far, proteomic profiling in oomycetes was primarily focused on subcellular, intracellular or cell wall fractions; the extracellular proteome has not been studied systematically. Here we present the first comprehensive characterization of the in vivo secretome and extracellular proteome of P. infestans. We have used mass spectrometry to analyze P. infestans proteins present in seven different growth media with mycelial cultures and this resulted in the consistent identification of over two hundred proteins. Gene ontology classification pinpointed proteins involved in cell wall modifications, pathogenesis, defense responses, and proteolytic processes. Moreover, we found members of the RXLR and CRN effector families as well as several proteins lacking an obvious signal peptide. The latter were confirmed to be bona fide extracellular proteins and this suggests that, similar to other organisms, oomycetes exploit non-conventional secretion mechanisms to transfer certain proteins to the extracellular environment.

  16. Biological Efficacy of Streptomyces sp. Strain BN1 against the Cereal Head Blight Pathogen Fusarium graminearum

    Directory of Open Access Journals (Sweden)

    Boknam Jung

    2013-03-01

    Full Text Available Fusarium head blight (FHB caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed.

  17. Fe2+ chelator proferrorosamine A: a gene cluster of Erwinia rhapontici P45 involved in its synthesis and its impact on growth of Erwinia amylovora CFBP1430.

    Science.gov (United States)

    Born, Yannick; Remus-Emsermann, Mitja N P; Bieri, Marco; Kamber, Tim; Piel, Jörn; Pelludat, Cosima

    2016-02-01

    Proferrorosamine A (proFRA) is an iron (Fe2+) chelator produced by the opportunistic plant pathogen Erwinia rhapontici P45. To identify genes involved in proFRA synthesis, transposon mutagenesis was performed. The identified 9.3 kb gene cluster, comprising seven genes, designated rosA-rosG, encodes proteins that are involved in proFRA synthesis. Based on gene homologies, a biosynthetic pathway model for proFRA is proposed. To obtain a better understanding of the effect of proFRA on non-proFRA producing bacteria, E. rhapontici P45 was co-cultured with Erwinia amylovora CFBP1430, a fire-blight-causing plant pathogen. E. rhapontici P45, but not corresponding proFRA-negative mutants, led to a pink coloration of E. amylovora CFBP1430 colonies on King's B agar, indicating accumulation of the proFRA-iron complex ferrorosamine, and growth inhibition in vitro. By saturating proFRA-containing extracts with Fe2+, the inhibitory effect was neutralized, suggesting that the iron-chelating capability of proFRA is responsible for the growth inhibition of E. amylovora CFBP1430.

  18. Effectiveness of a Peptide-rich Fraction from Xenorhabdus budapestensis Culture against Fire Blight Disease on Apple Blossoms

    Directory of Open Access Journals (Sweden)

    Dávid VOZIK

    2015-12-01

    Full Text Available Erwinia amylovora is one of the most frequently occurred plant pathogenic bacterium. It causes necrosis and blight symptoms on host plants and it lead to considerable yield losses throughout the world on apple trees. There is no effective chemical treatment is currently available against fire blight. The purpose of the present study was to search a new, alternative control method. The evaluation of the plant protection potential of an enriched fraction of Xenorhabdus budapestensis cell-free conditioned media was investigated. Purified samples were tested in vitro and in planta against the phytopathogenic bacterium. A reproducible method for isolation of a peptide-rich fraction from Xenorhabdus cell-free conditioned media was established. The process resulted in 400 mg of dry sample prepared from three litres of Xenorhabdus cell culture. Significant correlation was found between the concentration of the purified preparation and the induced inactivation zones against Erwinia amylovora Ea1 in agar diffusion test method. The minimum inhibitory concentration and minimum bactericidal concentration of the purified fraction against Ea1 strain were 8 μg/mL and 16 μg/mL, respectively. In planta experiments were tested on an apple cultivar (‘Watson Jonathan’ susceptible to fire blight. The effective range of concentration was 62-200 µg/mL, while treatment with 300 µg/mL and larger amounts caused necrotic symptoms on the petals of flowers. Current study pointed to the effectiveness of the compounds produced by X. budapestensis against fire blight. The development of a commercially applicable formulation of these compounds would allow growers to effectively control fire blight in apple and pear orchards.

  19. Identification of Pathogen Caused Western Cushaw phytoph thora blight%西洋南瓜疫霉病菌的鉴定

    Institute of Scientific and Technical Information of China (English)

    王国良; 吴华庆

    2001-01-01

    对西洋南瓜上的疫病作了分离、培养、镜检、测量了该菌的无性阶段 、有性阶段的 形态特征等多方面内容,鉴定结果为柑桔褐腐疫霉病菌Phytophthora citrophtho ra(R.E.&E.H.Smith)Leonian.%Identification results for pathogen of western cusha w Phytophthor a blight showed;the pathogen is phytophthora citrpthora(R.E.&E.S mith) Leonian.

  20. Microbiological examination of Erwinia amylovora exopolysaccharide ooze.

    Science.gov (United States)

    Slack, Suzanne; Zeng, Quan; Outwater, Cory; Sundin, George W

    2017-01-03

    Fire blight, caused by the pathogen Erwinia amylovora (Burrill) Winslow et al, is the most devastating bacterial disease of pome fruits in North America and worldwide. The primary method of dispersal for E. amylovora is through ooze, a mass of exopolysaccharides and bacterial cells that is exuded as droplets from infected host tissue. During the 2013 and 2014 field seasons, 317 ooze droplets were collected from field-inoculated apple trees. Populations of E. amylovora in ooze droplets were 108 colony forming units per microliter on average (cfu/µl). Ooze droplets harboring larger (> 108 cfu/µl) cell populations were typically smaller in total volume and had darker coloring, such as orange, red, or dark red hues. Examination of apple host tissue at the site of emergence of ooze droplets using scanning electron microscopy revealed that ooze was not exuding through natural openings; instead, it was found on erumpent mounds and small (10 µm) tears in tissue. These observations suggested that E. amylovora-induced wounds in tissue provided the exit holes for ooze extrusion from the host. Analyses of E. amylovora populations in ooze droplets and within the stems from which ooze droplets emerged indicated that approximately 9% of the total bacterial population from infected stems is diverted to ooze. Gene expression analyses indicated that E. amylovora cells in stem sections located above ooze droplets and in ooze droplets were actively expressing critical pathogenicity genes such as hrpL, dspE, and amsK. Thus, our study identified ooze as a source of large, concentrated populations of E. amylovora that emerged from the host by rupturing host tissue. As the cells in ooze droplets are expressing genes required for pathogenesis, they are already primed for infection should they be dispersed from ooze to new infection courts.

  1. Asparaginase Erwinia chrysanthemi

    Science.gov (United States)

    Asparaginase Erwinia chrysanthemi is used with other chemotherapy medications to treat acute lymphocytic leukemia (ALL; a type of cancer ... of allergic reactions to medications similar to asparaginase Erwinia chrysanthemi such as (asparaginase [Elspar] or pegaspargase [Oncaspar]). ...

  2. Effect of flumorph on F-actin dynamics in the potato late blight pathogen Phytophthora infestans

    NARCIS (Netherlands)

    Hua, C.; Kots, K.; Ketelaar, T.; Govers, F.; Meijer, H.J.G.

    2015-01-01

    Oomycetes are fungal-like pathogens that cause notorious diseases. Protecting crops against oomycetes requires regular spraying with chemicals, many of which with unknown mode of action. In the 1990’s, flumorph was identified as a novel crop protection agent. It was shown to inhibit the growth of oo

  3. Comparative population genomics of fusarium graminearum reveals adaptive divergence among cereal head blight pathogens

    Science.gov (United States)

    During the last decade, a combination of molecular surveillance and population genetic analyses have significantly altered our understanding of Fusarium graminearum, the major FHB pathogen in North America. In addition to the native NA1 population (largely 15ADON toxin type) and the invasive NA2 pop...

  4. Surface survival and internalization of salmonella through natural cracks on developing cantaloupe fruits, alone or in the presence of the melon wilt pathogen Erwinia tracheiphila.

    Directory of Open Access Journals (Sweden)

    Dhiraj Gautam

    Full Text Available Outbreaks of foodborne illness attributed to the consumption of Salmonella-tainted cantaloupe have occurred repeatedly, but understanding of the ecology of Salmonella on cantaloupe fruit surfaces is limited. We investigated the interactions between Salmonella enterica Poona, the plant pathogenic bacterium Erwinia tracheiphila, and cantaloupe fruit. Fruit surfaces were inoculated at the natural cracking stage by spreading S. enterica and E. tracheiphila, 20 µl at 107 cfu/ml, independently or together, over a 2×2 cm rind area containing a crack. Microbial and microscopic analyses were performed at 0, 9 and 24 days post inoculation (DPI. Even at 24 DPI (fruit maturity S. enterica was detected on 14% and 40% of the fruit inoculated with S. enterica alone and the two-pathogen mixture, respectively. However, the population of S. enterica declined gradually after initial inoculation. E. tracheiphila, inoculated alone or together with Salmonella, caused watersoaked lesions on cantaloupe fruit; but we could not conclude in this study that S. enterica survival on the fruit surface was enhanced by the presence of those lesions. Of fruit inoculated with E. tracheiphila alone and sampled at 24 DPI, 61% had watersoaked lesions on the surface. In nearly half of those symptomatic fruits the watersoaking extended into the sub-rind mesocarp, and E. tracheiphila was recovered from that tissue in 50% of the symptomatic fruit. In this work, E. tracheiphila internalized through natural cracks on developing fruits. S. enterica was never detected in the fruit interior (ca. 2-3 mm below rind surface under the limited conditions of our experiments, but the possibility that it, or other human pathogens that contaminate fresh produce, might also do so should be investigated under a wider range of conditions and produce types.

  5. Surface survival and internalization of salmonella through natural cracks on developing cantaloupe fruits, alone or in the presence of the melon wilt pathogen Erwinia tracheiphila.

    Science.gov (United States)

    Gautam, Dhiraj; Dobhal, Shefali; Payton, Mark E; Fletcher, Jacqueline; Ma, Li Maria

    2014-01-01

    Outbreaks of foodborne illness attributed to the consumption of Salmonella-tainted cantaloupe have occurred repeatedly, but understanding of the ecology of Salmonella on cantaloupe fruit surfaces is limited. We investigated the interactions between Salmonella enterica Poona, the plant pathogenic bacterium Erwinia tracheiphila, and cantaloupe fruit. Fruit surfaces were inoculated at the natural cracking stage by spreading S. enterica and E. tracheiphila, 20 µl at 107 cfu/ml, independently or together, over a 2×2 cm rind area containing a crack. Microbial and microscopic analyses were performed at 0, 9 and 24 days post inoculation (DPI). Even at 24 DPI (fruit maturity) S. enterica was detected on 14% and 40% of the fruit inoculated with S. enterica alone and the two-pathogen mixture, respectively. However, the population of S. enterica declined gradually after initial inoculation. E. tracheiphila, inoculated alone or together with Salmonella, caused watersoaked lesions on cantaloupe fruit; but we could not conclude in this study that S. enterica survival on the fruit surface was enhanced by the presence of those lesions. Of fruit inoculated with E. tracheiphila alone and sampled at 24 DPI, 61% had watersoaked lesions on the surface. In nearly half of those symptomatic fruits the watersoaking extended into the sub-rind mesocarp, and E. tracheiphila was recovered from that tissue in 50% of the symptomatic fruit. In this work, E. tracheiphila internalized through natural cracks on developing fruits. S. enterica was never detected in the fruit interior (ca. 2-3 mm below rind surface) under the limited conditions of our experiments, but the possibility that it, or other human pathogens that contaminate fresh produce, might also do so should be investigated under a wider range of conditions and produce types.

  6. Growth inhibition of Erwinia amylovora and related Erwinia species by neutralized short‑chain fatty acids.

    Science.gov (United States)

    Konecki, Katrin; Gernold, Marina; Wensing, Annette; Geider, Klaus

    2013-11-01

    Short-chain fatty acids (SCFAs) are used to preserve food and could be a tool for control of fire blight caused by Erwinia amylovora on apple, pear and related rosaceous plants. Neutralized acids were added to buffered growth media at 0.5–75 mM and tested at pHs ranging from 6.8 to 5.5. Particularly at low pH, SCFAs with a chain length exceeding that of acetic acid such as propionic acid were effective growth inhibitors of E. amylovora possibly due to uptake of free acid and its intracellular accumulation. We also observed high inhibition with monochloroacetic acid. An E. billingiae strain was as sensitive to the acids as E. amylovora or E. tasmaniensis. Fire blight symptoms on pear slices were reduced when the slices were pretreated with neutralized propionic acid. Propionic acid is well water soluble and could be applied in orchards as a control agent for fire blight.

  7. The prevalence and impact of Fusarium head blight pathogens and mycotoxins on malting barley quality in UK.

    Science.gov (United States)

    Nielsen, L K; Cook, D J; Edwards, S G; Ray, R V

    2014-06-02

    Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium

  8. Molecular detection of Erwinia psidii in guava plants under greenhouse and field conditions

    Directory of Open Access Journals (Sweden)

    Claudênia Ferreira da Silva

    2016-09-01

    Full Text Available ABSTRACT: Erwinia psidii causes bacterial blight of guava ( Psidium guajava , an important disease of this crop in Brazil. The pathogen affects branches and twigs of guava trees, reducing yield significantly. Bacterial dissemination often occurs through contaminated but asymptomatic propagating plant material. The objectives of this research were to evaluate the use of BIO-PCR and conventional PCR to detect E. psidii in inoculated guava plants grown in a greenhouse and in symptomatic and asymptomatic trees from guava orchards. Erwinia psidii strain IBSBF 1576 was inoculated (107CFU mL-1 into young guava shoots and plant tissue was analysed at 0, 5, 10, and 15 days after inoculation. Symptoms were observed after 5 days and all inoculated shoots were PCR positive at all times, by both BIO-PCR and conventional PCR. Under natural infection conditions, 40 samples were tested by BIO-PCR from each of three guava orchards, 20 showing symptoms and 20 asymptomatic. PCR was positive for 58 out of 60 symptomatic samples (96.7% and for 6.7% of asymptomatic samples, showing that the method can be used to detect the pathogen at early stages of infection. This PCR method may be used as a diagnostic tool to assess bacterial survival, dissemination and disease outbreaks.

  9. Effect of Flumorph on F-Actin Dynamics in the Potato Late Blight Pathogen Phytophthora infestans.

    Science.gov (United States)

    Hua, Chenlei; Kots, Kiki; Ketelaar, Tijs; Govers, Francine; Meijer, Harold J G

    2015-04-01

    Oomycetes are fungal-like pathogens that cause notorious diseases. Protecting crops against oomycetes requires regular spraying with chemicals, many with an unknown mode of action. In the 1990s, flumorph was identified as a novel crop protection agent. It was shown to inhibit the growth of oomycete pathogens including Phytophthora spp., presumably by targeting actin. We recently generated transgenic Phytophthora infestans strains that express Lifeact-enhanced green fluorescent protein (eGFP), which enabled us to monitor the actin cytoskeleton during hyphal growth. For analyzing effects of oomicides on the actin cytoskeleton in vivo, the P. infestans Lifeact-eGFP strain is an excellent tool. Here, we confirm that flumorph is an oomicide with growth inhibitory activity. Microscopic analyses showed that low flumorph concentrations provoked hyphal tip swellings accompanied by accumulation of actin plaques in the apex, a feature reminiscent of tips of nongrowing hyphae. At higher concentrations, swelling was more pronounced and accompanied by an increase in hyphal bursting events. However, in hyphae that remained intact, actin filaments were indistinguishable from those in nontreated, nongrowing hyphae. In contrast, in hyphae treated with the actin depolymerizing drug latrunculin B, no hyphal bursting was observed but the actin filaments were completely disrupted. This difference demonstrates that actin is not the primary target of flumorph.

  10. Virulence Factors of Erwinia amylovora: A Review.

    Science.gov (United States)

    Piqué, Núria; Miñana-Galbis, David; Merino, Susana; Tomás, Juan M

    2015-06-05

    Erwinia amylovora, a Gram negative bacteria of the Enterobacteriaceae family, is the causal agent of fire blight, a devastating plant disease affecting a wide range of host species within Rosaceae and a major global threat to commercial apple and pear production. Among the limited number of control options currently available, prophylactic application of antibiotics during the bloom period appears the most effective. Pathogen cells enter plants through the nectarthodes of flowers and other natural openings, such as wounds, and are capable of rapid movement within plants and the establishment of systemic infections. Many virulence determinants of E. amylovora have been characterized, including the Type III secretion system (T3SS), the exopolysaccharide (EPS) amylovoran, biofilm formation, and motility. To successfully establish an infection, E. amylovora uses a complex regulatory network to sense the relevant environmental signals and coordinate the expression of early and late stage virulence factors involving two component signal transduction systems, bis-(3'-5')-cyclic di-GMP (c-di-GMP) and quorum sensing. The LPS biosynthetic gene cluster is one of the relatively few genetic differences observed between Rubus- and Spiraeoideae-infecting genotypes of E. amylovora. Other differential factors, such as the presence and composition of an integrative conjugative element associated with the Hrp T3SS (hrp genes encoding the T3SS apparatus), have been recently described. In the present review, we present the recent findings on virulence factors research, focusing on their role in bacterial pathogenesis and indicating other virulence factors that deserve future research to characterize them.

  11. Virulence Factors of Erwinia amylovora: A Review

    Directory of Open Access Journals (Sweden)

    Núria Piqué

    2015-06-01

    Full Text Available Erwinia amylovora, a Gram negative bacteria of the Enterobacteriaceae family, is the causal agent of fire blight, a devastating plant disease affecting a wide range of host species within Rosaceae and a major global threat to commercial apple and pear production. Among the limited number of control options currently available, prophylactic application of antibiotics during the bloom period appears the most effective. Pathogen cells enter plants through the nectarthodes of flowers and other natural openings, such as wounds, and are capable of rapid movement within plants and the establishment of systemic infections. Many virulence determinants of E. amylovora have been characterized, including the Type III secretion system (T3SS, the exopolysaccharide (EPS amylovoran, biofilm formation, and motility. To successfully establish an infection, E. amylovora uses a complex regulatory network to sense the relevant environmental signals and coordinate the expression of early and late stage virulence factors involving two component signal transduction systems, bis-(3′-5′-cyclic di-GMP (c-di-GMP and quorum sensing. The LPS biosynthetic gene cluster is one of the relatively few genetic differences observed between Rubus- and Spiraeoideae-infecting genotypes of E. amylovora. Other differential factors, such as the presence and composition of an integrative conjugative element associated with the Hrp T3SS (hrp genes encoding the T3SS apparatus, have been recently described. In the present review, we present the recent findings on virulence factors research, focusing on their role in bacterial pathogenesis and indicating other virulence factors that deserve future research to characterize them.

  12. Plant-mediated gene silencing restricts growth of the potato late blight pathogen Phytophthora infestans.

    Science.gov (United States)

    Jahan, Sultana N; Åsman, Anna K M; Corcoran, Pádraic; Fogelqvist, Johan; Vetukuri, Ramesh R; Dixelius, Christina

    2015-05-01

    Phytophthora infestans is an oomycete that causes severe damage to potato, and is well known for its ability to evolve rapidly in order to overcome resistant potato varieties. An RNA silencing strategy was evaluated here to clarify if small interfering RNA homologous to selected genes in P. infestans could be targeted from the plant host to reduce the magnitude of the infection. As a proof-of-concept, a hairpin RNA (hp-RNA) construct using the GFP marker gene was designed and introduced in potato. At 72 hpi, a 55-fold reduction of the signal intensity of a corresponding GFP expressing P. infestans strain on leaf samples of transgenic plants, compared with wild-type potato, was detected. This suggests that an RNA interference construct in the potato host could be processed and target a transcript of the pathogen. Three genes important in the infection process of P. infestans, PiGPB1, PiCESA2, and PiPEC, together with PiGAPDH taking part in basic cell maintenance were subsequently tested using an analogous transgenic strategy. Out of these gene candidates, the hp-PiGPB1 targeting the G protein β-subunit (PiGPB1) important for pathogenicity resulted in most restricted disease progress. Further, Illumina sequencing of inoculated transgenic potato leaves revealed sRNAs of 24/25 nt size homologous to the PiGPB1 gene in the transgenic plants indicating post-transcriptional silencing of the target gene. The work demonstrates that a host-induced gene-silencing approach is functional against P. infestans but is highly dependent on target gene for a successful outcome. This finding broadens the arsenal of control strategies to this important plant disease.

  13. Diversity of Fusarium head blight populations and trichothecene toxin types reveals regional differences in pathogen composition and temporal dynamics.

    Science.gov (United States)

    Kelly, Amy C; Clear, Randall M; O'Donnell, Kerry; McCormick, Susan; Turkington, T Kelly; Tekauz, Andy; Gilbert, Jeannie; Kistler, H Corby; Busman, Mark; Ward, Todd J

    2015-09-01

    Analyses of genetic diversity, trichothecene genotype composition, and population structure were conducted using 4086 Fusarium graminearum isolates collected from wheat in eight Canadian provinces over a three year period between 2005 and 2007. The results revealed substantial regional differences in Fusarium head blight pathogen composition and temporal population dynamics. The 3ADON trichothecene type consistently predominated in Maritime provinces (91%) over the sampled years, and increased significantly (P<0.05) between 2005 and 2007 in western Canada, accounting for 66% of the isolates in Manitoba by the end of the sampling period. In contrast, 3ADON frequency was lower (22%, P<0.001) in the eastern Canadian provinces of Ontario and Québec and did not change significantly between 2005 and 2007, resulting in two distinct longitudinal clines in 3ADON frequency across Canada. Overall, genetic structure was correlated with toxin type, as the endemic population (NA1) was dominated by 15ADON isolates (86%), whereas a second population (NA2) consisted largely of 3ADON isolates (88%). However, the percentage of isolates with trichothecene genotypes that were not predictive of their genetic population assignment (recombinant genotypes) increased from 10% in 2005 to 17% in 2007, indicating that trichothecene type became an increasingly unreliable marker of population identity over time. In addition, there were substantial regional differences in the composition of recombinant genotypes. In western and maritime provinces, NA2 isolates with 15ADON genotypes were significantly more common than NA1 isolates with 3ADON genotypes (P<0.001), and the reverse was true in the eastern provinces of Québec and Ontario. Temporal trends in recombinant genotype composition also varied regionally, as the percentage of 15ADON isolates with NA2 genetic backgrounds increased approximately three fold in western and Maritime provinces, while the opposite trends were observed in Québec and

  14. Budagovsky 9 rootstock: uncovering a novel resistance to fire blight

    Science.gov (United States)

    Budagovsky 9 (B.9) apple rootstock, displayed a high level of susceptibility (similar to M.9 rootstock) to fire blight bacteria (Erwinia amylovora) when leaves of non-grafted B.9 plants were inoculated. However, when older B.9 rootstock tissue was inoculated directly with E. amylovora, rootstock tis...

  15. Integrated Control of Fire Blight with Bacterial Antagonists and Oxytetracycline

    Science.gov (United States)

    In the Pacific Northwest of the United States, the antibiotic streptomycin provided excellent control of fire blight until resistant isolates of Erwinia amylovora were prevalent. Oxytetracycline (Mycoshield) is now sprayed as an alternative antibiotic. We found that the duration of inhibitory acti...

  16. Integrated Control of Fire Blight with Antagonists and Oxytetracycline

    Science.gov (United States)

    In the Pacific Northwest of the United States, the antibiotic streptomycin provided excellent control of fire blight until resistant isolates of Erwinia amylovora arose. Oxytetracycline (Mycoshield) is now sprayed as an alternative antibiotic. We found that the duration of inhibitory activity of o...

  17. Field Susceptibility of Quince Hybrids to Fire Blight in Bulgaria

    Science.gov (United States)

    Spread of fire blight in Bulgaria during the last 20 years has nearly eliminated commercial production of pear and quince. Damage has increased in both nurseries and orchards, yet susceptible cultivars continue to be planted. Quince is the host most frequently attacked by Erwinia amylovora in Bulgar...

  18. Multilocus Genotyping and Molecular Phylogenetics Resolve a Novel Head Blight Pathogen within the Fusarium graminearum Species Complex from Ethiopia

    Science.gov (United States)

    A survey of Fusarium head blight (FHB)-contaminated wheat in Ethiopia recovered 31 isolates resembling members of the Fusarium graminearum species complex. Results of a multilocus genotyping (MLGT) assay for FHB species and trichothecene chemotype determination suggested that 22 of these isolates m...

  19. Development of the First Cisgenic Apple with Increased Resistance to Fire Blight.

    Directory of Open Access Journals (Sweden)

    Thomas D Kost

    Full Text Available The generation and selection of novel fire blight resistant apple genotypes would greatly improve the management of this devastating disease, caused by Erwinia amylovora. Such resistant genotypes are currently developed by conventional breeding, but novel breeding technologies including cisgenesis could be an alternative approach. A cisgenic apple line C44.4.146 was regenerated using the cisgene FB_MR5 from wild apple Malus ×robusta 5 (Mr5, and the previously established method involving A. tumefaciens-mediated transformation of the fire blight susceptible cultivar 'Gala Galaxy' using the binary vector p9-Dao-FLPi. The line C44.4.146 was shown to carry only the cisgene FB_MR5, controlled by its native regulatory sequences and no transgenes were detected by PCR or Southern blot following heat induced recombinase-mediated elimination of the selectable markers. Although this line contains up to 452 bp of vector sequences, it still matches the original definition of cisgenesis. A single insertion of T-DNA into the genome of 'Gala Galaxy' in chromosome 16 was identified. Transcription of FB_MR5 in line C44.4.146 was similar to the transcription in classically bred descendants of Mr5. Three independent shoot inoculation experiments with a Mr5 avirulent strain of Erwinia amylovora were performed using scissors or syringe. Significantly lower disease symptoms were detected on shoots of the cisgenic line compared to those of untransformed 'Gala Galaxy'. Despite the fact that the pathogen can overcome this resistance by a single nucleotide mutation, this is, to our knowledge, the first prototype of a cisgenic apple with increased resistance to fire blight.

  20. Horizontal gene acquisitions, mobile element proliferation, and genome decay in the host-restricted plant pathogen erwinia tracheiphila

    Science.gov (United States)

    Modern industrial agriculture depends on high-density cultivation of genetically similar crop plants, creating favorable conditions for the emergence of novel pathogens with increased fitness in managed compared with ecologically intact settings. Here, we present the genome sequence of six strains o...

  1. Rootstock-regulated gene expression patterns associated with fire blight resistance in apple

    Directory of Open Access Journals (Sweden)

    Jensen Philip J

    2012-01-01

    Full Text Available Abstract Background Desirable apple varieties are clonally propagated by grafting vegetative scions onto rootstocks. Rootstocks influence many phenotypic traits of the scion, including resistance to pathogens such as Erwinia amylovora, which causes fire blight, the most serious bacterial disease of apple. The purpose of the present study was to quantify rootstock-mediated differences in scion fire blight susceptibility and to identify transcripts in the scion whose expression levels correlated with this response. Results Rootstock influence on scion fire blight resistance was quantified by inoculating three-year old, orchard-grown apple trees, consisting of 'Gala' scions grafted to a range of rootstocks, with E. amylovora. Disease severity was measured by the extent of shoot necrosis over time. 'Gala' scions grafted to G.30 or MM.111 rootstocks showed the lowest rates of necrosis, while 'Gala' on M.27 and B.9 showed the highest rates of necrosis. 'Gala' scions on M.7, S.4 or M.9F56 had intermediate necrosis rates. Using an apple DNA microarray representing 55,230 unique transcripts, gene expression patterns were compared in healthy, un-inoculated, greenhouse-grown 'Gala' scions on the same series of rootstocks. We identified 690 transcripts whose steady-state expression levels correlated with the degree of fire blight susceptibility of the scion/rootstock combinations. Transcripts known to be differentially expressed during E. amylovora infection were disproportionately represented among these transcripts. A second-generation apple microarray representing 26,000 transcripts was developed and was used to test these correlations in an orchard-grown population of trees segregating for fire blight resistance. Of the 690 transcripts originally identified using the first-generation array, 39 had expression levels that correlated with fire blight resistance in the breeding population. Conclusions Rootstocks had significant effects on the fire blight

  2. Separation and Identification of Erwinia caratovora ssp . caratovora Pathogen of Coriandrum sativum L%芫荽软腐病病原菌分离与鉴定

    Institute of Scientific and Technical Information of China (English)

    张立微; 张景涛; 李小梅

    2015-01-01

    为有效防治芫荽软腐病,提高其产质量,通过对引起芫荽腐烂而绝产的病害的病原菌进行分离、纯化,对19个菌株进行17项生理生化指标测定。结果表明:根据伯杰氏细菌鉴定手册(第八版)以 Ecc为对照进行鉴定,确定E1(Ames24923)、E3(Ames24927)、E4(CORI107)、E7(CORI139)、E8(CORI140)、E10(CORI147)、E12(CORI289)、E13(CORI318)、E18(PI664510)为芫荽胡萝卜欧文氏杆菌属胡萝卜软腐欧文氏杆菌胡萝卜软腐病亚种(Erw inia carotovora ssp .carotovora ,Ecc)细菌,而其余供试菌株通过测定可确定为细菌,但属何种还需进一步鉴定。%In order to control the Erwinia caratovora ssp .caratovora of Coriandrum sativum L .,and improve the quality ,through the isolating and purificating of the pathogen which causes coriander decay ,19 strains were isolated and purified .The results showed that according to Bergey's Manual of Systematic Bacteriology (eighth edition) and 17 tests of physiology and biochemistry ,9 strainss were Erwiniacarotovora ssp .carotovora ,inclu‐ding E1(Ames24923) ,E3(Ames24927) ,E4(CORI107) ,E7(CORI139) ,E8(CORI140) ,E10(CORI147) ,E12 (CORI289) ,E13(CORI318) ,E18(PI664510) .Other strains should to be identified by other tools .

  3. Antibiosis by Pantoea agglomerans biocontrol strain E325 against Erwinia amylovora on apple blossom stigmas

    Science.gov (United States)

    Pantoea agglomerans E325, the active ingredient in a commercial product for fire blight control, was previously shown in vitro to produce a unique alkaline- and phosphate-sensitive antibiotic specific to Erwinia amylovora. Antibiosis was evaluated as a mode of antagonism on blossom stigmas using two...

  4. Genome-wide identification of genes regulated by the Rcs Phosphorelay system in Erwinia amylovora

    Science.gov (United States)

    The exopolysaccharide amylovoran is one of the major pathgenicity factors in Erwinia amylovora, the causal agent of fire blight of apples and pears. We have previously demonstrated that the RcsBCD phosphorelay system is essential for virulence by controlling amylovoran biosynthesis. We have also fou...

  5. A Puf RNA-binding protein encoding gene PlM90 regulates the sexual and asexual life stages of the litchi downy blight pathogen Peronophythora litchii.

    Science.gov (United States)

    Jiang, Liqun; Ye, Wenwu; Situ, Junjian; Chen, Yubin; Yang, Xinyu; Kong, Guanghui; Liu, Yaya; Tinashe, Runyanga J; Xi, Pinggen; Wang, Yuanchao; Jiang, Zide

    2017-01-01

    Sexual and asexual reproduction are two key processes in the pathogenic cycle of many filamentous pathogens. However in Peronophythora litchii, the causal pathogen for the litchi downy blight disease, critical regulator(s) of sexual or asexual differentiation has not been elucidated. In this study, we cloned a gene named PlM90 from P. litchii, which encodes a putative Puf RNA-binding protein. We found that PlM90 was highly expressed during asexual development, and much higher than that during sexual development, while relatively lower during cyst germination and plant infection. By polyethylene glycol (PEG)-mediated protoplast transformation, we generated three PlM90-silenced transformants and found a severely impaired ability in sexual spore production and a delay in stages of zoospore release and encystment. However, the pathogenicity of P. litchii was not affected by PlM90-silencing. Therefore we conclude that PlM90 specifically regulates the sexual and asexual differentiation of P. litchii.

  6. Small-molecule inhibitors suppress the expression of both type III secretion and amylovoran biosynthesis genes in Erwinia amylovora.

    Science.gov (United States)

    Yang, Fan; Korban, Schuyler S; Pusey, P Lawrence; Elofsson, Michael; Sundin, George W; Zhao, Youfu

    2014-01-01

    The type III secretion system (T3SS) and exopolysaccharide (EPS) amylovoran are two essential pathogenicity factors in Erwinia amylovora, the causal agent of the serious bacterial disease fire blight. In this study, small molecules that inhibit T3SS gene expression in E. amylovora under hrp (hypersensitive response and pathogenicity)-inducing conditions were identified and characterized using green fluorescent protein (GFP) as a reporter. These compounds belong to salicylidene acylhydrazides and also inhibit amylovoran production. Microarray analysis of E. amylovora treated with compounds 3 and 9 identified a total of 588 significantly differentially expressed genes. Among them, 95 and 78 genes were activated and suppressed by both compounds, respectively, when compared with the dimethylsulphoxide (DMSO) control. The expression of the majority of T3SS genes in E. amylovora, including hrpL and the avrRpt2 effector gene, was suppressed by both compounds. Compound 3 also suppressed the expression of amylovoran precursor and biosynthesis genes. However, both compounds induced significantly the expression of glycogen biosynthesis genes and siderophore biosynthesis, regulatory and transport genes. Furthermore, many membrane, lipoprotein and exported protein-encoding genes were also activated by both compounds. Similar expression patterns were observed for compounds 1, 2 and 4. Using crab apple flower as a model, compound 3 was capable of reducing disease development in pistils. These results suggest a common inhibition mechanism shared by salicylidene acylhydrazides and indicate that small-molecule inhibitors that disable T3SS function could be explored to control fire blight disease.

  7. 马拉巴栗疫病病原的分离与鉴定%Isolation and Identification of the Pathogen Causing Phytophthora Blight of Pachira macrocarpa

    Institute of Scientific and Technical Information of China (English)

    李琳; 陈鸿宇; 柳凤; 何红; 余莎

    2011-01-01

    The diseased plants of Pachira macrocarpa showing symptoms of phytophthora blight were collected from Zhanjiang,Guangdong Province from 2008 to 2009.This study proved that the pathogen was a kind of fungus by test of Koch’s postulates.The pathogenic fungus was identified as Phytophthora palmivora based on pathogenicity and morphology,host range and sequence analysis of rDNA-ITS.%2008—2009年,从广东省湛江等地采集疑似疫病的马拉巴栗病株,经病原菌分离及柯赫氏法则验证,证明其病原菌是疫霉菌。通过致病性、寄主范围测定,菌体形态,培养特性及rDNA-ITS序列分析等,将该病原菌初步鉴定为棕榈疫霉(Phytophthora palmivora)。

  8. The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae.

    Science.gov (United States)

    Wang, Xing-Yu; Zhou, Lian; Yang, Jun; Ji, Guang-Hai; He, Ya-Wen

    2016-03-01

    Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.

  9. Bacterieziekte Erwinia groeiend probleem

    NARCIS (Netherlands)

    Wolf, van der J.M.

    2012-01-01

    Het grootste probleem van Nederlandse pootgoedtelers is tegenwoordig de bacterieziekte Erwinia. Het is een sluipmoordenaar waar nog geen bestrijdingsmiddelen tegen bestaan. Maar onderzoekers komen steeds meer over de bacterie te weten.

  10. Putative resistance gene markers associated with quantitative trait loci for fire blight resistance in Malus ‘Robusta 5’ accessions

    Directory of Open Access Journals (Sweden)

    Gardiner Susan E

    2012-04-01

    Full Text Available Abstract Background Breeding of fire blight resistant scions and rootstocks is a goal of several international apple breeding programs, as options are limited for management of this destructive disease caused by the bacterial pathogen Erwinia amylovora. A broad, large-effect quantitative trait locus (QTL for fire blight resistance has been reported on linkage group 3 of Malus ‘Robusta 5’. In this study we identified markers derived from putative fire blight resistance genes associated with the QTL by integrating further genetic mapping studies with bioinformatics analysis of transcript profiling data and genome sequence databases. Results When several defined E.amylovora strains were used to inoculate three progenies from international breeding programs, all with ‘Robusta 5’ as a common parent, two distinct QTLs were detected on linkage group 3, where only one had previously been mapped. In the New Zealand ‘Malling 9’ X ‘Robusta 5’ population inoculated with E. amylovora ICMP11176, the proximal QTL co-located with SNP markers derived from a leucine-rich repeat, receptor-like protein ( MxdRLP1 and a closely linked class 3 peroxidase gene. While the QTL detected in the German ‘Idared’ X ‘Robusta 5’ population inoculated with E. amylovora strains Ea222_JKI or ICMP11176 was approximately 6 cM distal to this, directly below a SNP marker derived from a heat shock 90 family protein gene ( HSP90. In the US ‘Otawa3’ X ‘Robusta5’ population inoculated with E. amylovora strains Ea273 or E2002a, the position of the LOD score peak on linkage group 3 was dependent upon the pathogen strains used for inoculation. One of the five MxdRLP1 alleles identified in fire blight resistant and susceptible cultivars was genetically associated with resistance and used to develop a high resolution melting PCR marker. A resistance QTL detected on linkage group 7 of the US population co-located with another HSP90 gene-family member and a WRKY

  11. Mutational analysis of a predicted double β-propeller domain of the DspA/E effector of Erwinia amylovora.

    Science.gov (United States)

    Siamer, Sabrina; Gaubert, Stéphane; Boureau, Tristan; Brisset, Marie-Noëlle; Barny, Marie-Anne

    2013-05-01

    The bacterium Erwinia amylovora causes fire blight, an invasive disease that threatens apple trees, pear trees and other plants of the Rosaceae family. Erwinia amylovora pathogenicity relies on a type III secretion system and on a single effector DspA/E. This effector belongs to the widespread AvrE family of effectors whose biological function is unknown. In this manuscript, we performed a bioinformatic analysis of DspA/E- and AvrE-related effectors. Motif search identified nuclear localization signals, peroxisome targeting signals, endoplasmic reticulum membrane retention signals and leucine zipper motifs, but none of these motifs were present in all the AvrE-related effectors analysed. Protein threading analysis, however, predicted a conserved double β-propeller domain in the N-terminal part of all the analysed effector sequences. We then performed a random pentapeptide mutagenesis of DspA/E, which led to the characterization of 13 new altered proteins with a five amino acids insertion. Eight harboured the insertion inside the predicted β-propeller domain and six of these eight insertions impaired DspA/E stability or function. Conversely, the two remaining insertions generated proteins that were functional and abundantly secreted in the supernatant suggesting that these two insertions stabilized the protein.

  12. Complete genome sequences of three Erwinia amylovora phages isolated in north america and a bacteriophage induced from an Erwinia tasmaniensis strain.

    Science.gov (United States)

    Müller, I; Kube, M; Reinhardt, R; Jelkmann, W; Geider, K

    2011-02-01

    Fire blight, a plant disease of economic importance caused by Erwinia amylovora, may be controlled by the application of bacteriophages. Here, we provide the complete genome sequences and the annotation of three E. amylovora-specific phages isolated in North America and genomic information about a bacteriophage induced by mitomycin C treatment of an Erwinia tasmaniensis strain that is antagonistic for E. amylovora. The American phages resemble two already-described viral genomes, whereas the E. tasmaniensis phage displays a singular genomic sequence in BLAST searches.

  13. Cellular, physiological, and molecular adaptive responses of Erwinia amylovora to starvation.

    Science.gov (United States)

    Santander, Ricardo D; Oliver, James D; Biosca, Elena G

    2014-05-01

    Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants distributed worldwide. This bacterium is a nonobligate pathogen able to survive outside the host under starvation conditions, allowing its spread by various means such as rainwater. We studied E. amylovora responses to starvation using water microcosms to mimic natural oligotrophy. Initially, survivability under optimal (28 °C) and suboptimal (20 °C) growth temperatures was compared. Starvation induced a loss of culturability much more pronounced at 28 °C than at 20 °C. Natural water microcosms at 20 °C were then used to characterize cellular, physiological, and molecular starvation responses of E. amylovora. Challenged cells developed starvation-survival and viable but nonculturable responses, reduced their size, acquired rounded shapes and developed surface vesicles. Starved cells lost motility in a few days, but a fraction retained flagella. The expression of genes related to starvation, oxidative stress, motility, pathogenicity, and virulence was detected during the entire experimental period with different regulation patterns observed during the first 24 h. Further, starved cells remained as virulent as nonstressed cells. Overall, these results provide new knowledge on the biology of E. amylovora under conditions prevailing in nature, which could contribute to a better understanding of the life cycle of this pathogen.

  14. Expression of lysozymes from Erwinia amylovora phages and Erwinia genomes and inhibition by a bacterial protein.

    Science.gov (United States)

    Müller, Ina; Gernold, Marina; Schneider, Bernd; Geider, Klaus

    2012-01-01

    Genes coding for lysozyme-inhibiting proteins (Ivy) were cloned from the chromosomes of the plant pathogens Erwinia amylovora and Erwinia pyrifoliae. The product interfered not only with activity of hen egg white lysozyme, but also with an enzyme from E. amylovora phage ΦEa1h. We have expressed lysozyme genes from the genomes of three Erwinia species in Escherichia coli. The lysozymes expressed from genes of the E. amylovora phages ΦEa104 and ΦEa116, Erwinia chromosomes and Arabidopsis thaliana were not affected by Ivy. The enzyme from bacteriophage ΦEa1h was fused at the N- or C-terminus to other peptides. Compared to the intact lysozyme, a His-tag reduced its lytic activity about 10-fold and larger fusion proteins abolished activity completely. Specific protease cleavage restored lysozyme activity of a GST-fusion. The bacteriophage-encoded lysozymes were more active than the enzymes from bacterial chromosomes. Viral lyz genes were inserted into a broad-host range vector, and transfer to E. amylovora inhibited cell growth. Inserted in the yeast Pichia pastoris, the ΦEa1h-lysozyme was secreted and also inhibited by Ivy. Here we describe expression of unrelated cloned 'silent' lyz genes from Erwinia chromosomes and a novel interference of bacterial Ivy proteins with a viral lysozyme.

  15. Gram-Positive Bacteria Associated with Rice in China and Their Antagonists Against the Pathogens of Sheath Blight and Bakanae Disease in Rice

    Institute of Scientific and Technical Information of China (English)

    LUO Jin-yan; XIE Guan-lin; LI Bin; LUO Yuan-chan; ZHAO Li-han; WANG Xiao; LIU Bo; LI Wen

    2005-01-01

    It is necessary to understand the bacterial populations associated with rice so as to provide more information and natural resources for effective management of major diseases in rice. A survey on screening and identification of gram-positive bacteria was conducted during 1998-2004. Seven hundred and fifty-six rice samples were collected from Zhejiang, Jiangsu, Fujian and Yunnan Provinces, China. Over 1000 bacterial isolates were isolated and tested for colony morphology, pathogenicity, and some characteristics of bacteriology including Gram staining, fluorescent pigment on Kings medium B and microscopic observation for endospore. Together with five standard reference strains, 74 representative gram-positive bacterial isolates were confirmed by Biolog and gas chromatographic analysis of fatty acid methyl esters. Five bacterial species of Bacillus and other three genera were identified and isolates from Bacillus sublitis and Bacillus megaterium, exhibited the most effective inhibition against the pathogens of sheath blight and bakanae disease of rice. A few isolates from Bacillus pumilus and Bacillus megaterium showed weak virulent on rice together with some virulent isolates, dsk should be considered when isolates from these species were screened for biocontrol agents.

  16. The receptor-like kinase SERK3/BAK1 is required for basal resistance against the late blight pathogen phytophthora infestans in Nicotiana benthamiana.

    Directory of Open Access Journals (Sweden)

    Angela Chaparro-Garcia

    Full Text Available BACKGROUND: The filamentous oomycete plant pathogen Phytophthora infestans causes late blight, an economically important disease, on members of the nightshade family (Solanaceae, such as the crop plants potato and tomato. The related plant Nicotiana benthamiana is a model system to study plant-pathogen interactions, and the susceptibility of N. benthamiana to Phytophthora species varies from susceptible to resistant. Little is known about the extent to which plant basal immunity, mediated by membrane receptors that recognise conserved pathogen-associated molecular patterns (PAMPs, contributes to P. infestans resistance. PRINCIPAL FINDINGS: We found that different species of Phytophthora have varying degrees of virulence on N. benthamiana ranging from avirulence (incompatible interaction to moderate virulence through to full aggressiveness. The leucine-rich repeat receptor-like kinase (LRR-RLK BAK1/SERK3 is a major modulator of PAMP-triggered immunity (PTI in Arabidopsis thaliana and N. benthamiana. We cloned two NbSerk3 homologs, NbSerk3A and NbSerk3B, from N. benthamiana based on sequence similarity to the A. thaliana gene. N. benthamiana plants silenced for NbSerk3 showed markedly enhanced susceptibility to P. infestans infection but were not altered in resistance to Phytophthora mirabilis, a sister species of P. infestans that specializes on a different host plant. Furthermore, silencing of NbSerk3 reduced the cell death response triggered by the INF1, a secreted P. infestans protein with features of PAMPs. CONCLUSIONS/SIGNIFICANCE: We demonstrated that N. benthamiana NbSERK3 significantly contributes to resistance to P. infestans and regulates the immune responses triggered by the P. infestans PAMP protein INF1. In the future, the identification of novel surface receptors that associate with NbSERK3A and/or NbSERK3B should lead to the identification of new receptors that mediate recognition of oomycete PAMPs, such as INF1.

  17. Engineering fire blight resistance into the apple cultivar 'Gala' using the FB_MR5 CC-NBS-LRR resistance gene of Malus × robusta 5.

    Science.gov (United States)

    Broggini, Giovanni A L; Wöhner, Thomas; Fahrentrapp, Johannes; Kost, Thomas D; Flachowsky, Henryk; Peil, Andreas; Hanke, Maria-Viola; Richter, Klaus; Patocchi, Andrea; Gessler, Cesare

    2014-08-01

    The fire blight susceptible apple cultivar Malus × domestica Borkh. cv. 'Gala' was transformed with the candidate fire blight resistance gene FB_MR5 originating from the crab apple accession Malus × robusta 5 (Mr5). A total of five different transgenic lines were obtained. All transgenic lines were shown to be stably transformed and originate from different transgenic events. The transgenic lines express the FB_MR5 either driven by the constitutive CaMV 35S promoter and the ocs terminator or by its native promoter and terminator sequences. Phenotyping experiments were performed with Mr5-virulent and Mr5-avirulent strains of Erwinia amylovora, the causal agent of fire blight. Significantly less disease symptoms were detected on transgenic lines after inoculation with two different Mr5-avirulent E. amylovora strains, while significantly more shoot necrosis was observed after inoculation with the Mr5-virulent mutant strain ZYRKD3_1. The results of these experiments demonstrated the ability of a single gene isolated from the native gene pool of apple to protect a susceptible cultivar from fire blight. Furthermore, this gene is confirmed to be the resistance determinant of Mr5 as the transformed lines undergo the same gene-for-gene interaction in the host-pathogen relationship Mr5-E. amylovora.

  18. Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus x domestica) with Erwinia amylovora

    Science.gov (United States)

    The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB) disease in many Rosaceae species, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-...

  19. Conductrimetric detection of Pseudomonas syringae pathovar pisi in pea seeds and soft rot Erwinia spp. on potato tubers.

    NARCIS (Netherlands)

    Fraaije, B.A.

    1996-01-01

    Pea bacterial blight and potato blackleg are diseases caused by Pseudomonas syringae pv. pisi ( Psp ) and soft rot Erwinia spp., respectively. The primary source of inoculum for these bacteria is contaminated plant propagation material, i.e. pea seeds and potato tubers. One of the best ways to contr

  20. Quantitative label-free phosphoproteomics of six different life stages of the late blight pathogen Phytophthora infestans reveals abundant phosphorylation of members of the CRN effector family.

    Science.gov (United States)

    Resjö, Svante; Ali, Ashfaq; Meijer, Harold J G; Seidl, Michael F; Snel, Berend; Sandin, Marianne; Levander, Fredrik; Govers, Francine; Andreasson, Erik

    2014-04-04

    The oomycete Phytophthora infestans is the causal agent of late blight in potato and tomato. Since the underlying processes that govern pathogenicity and development in P. infestans are largely unknown, we have performed a large-scale phosphoproteomics study of six different P. infestans life stages. We have obtained quantitative data for 2922 phosphopeptides and compared their abundance. Life-stage-specific phosphopeptides include ATP-binding cassette transporters and a kinase that only occurs in appressoria. In an extended data set, we identified 2179 phosphorylation sites and deduced 22 phosphomotifs. Several of the phosphomotifs matched consensus sequences of kinases that occur in P. infestans but not Arabidopsis. In addition, we detected tyrosine phosphopeptides that are potential targets of kinases resembling mammalian tyrosine kinases. Among the phosphorylated proteins are members of the RXLR and Crinkler effector families. The latter are phosphorylated in several life stages and at multiple positions, in sites that are conserved between different members of the Crinkler family. This indicates that proteins in the Crinkler family have functions beyond their putative role as (necrosis-inducing) effectors. This phosphoproteomics data will be instrumental for studies on oomycetes and host-oomycete interactions. The data sets have been deposited to ProteomeXchange (identifier PXD000433).

  1. HecA, a member of a class of adhesins produced by diverse pathogenic bacteria, contributes to the attachment, aggregation, epidermal cell killing, and virulence phenotypes of Erwinia chrysanthemi EC16 on Nicotiana clevelandii seedlings.

    Science.gov (United States)

    Rojas, Clemencia M; Ham, Jong Hyun; Deng, Wen-Ling; Doyle, Jeff J; Collmer, Alan

    2002-10-01

    Erwinia chrysanthemi is representative of a broad class of bacterial pathogens that are capable of inducing necrosis in plants. The E. chrysanthemi EC16 hecA gene predicts a 3,850-aa member of the Bordetella pertussis filamentous hemagglutinin family of adhesins. A hecATn7 mutant was reduced in virulence on Nicotiana clevelandii seedlings after inoculation without wounding. Epifluorescence and confocal laser-scanning microscopy observations of hecA and wild-type cells expressing the green fluorescent protein revealed that the mutant is reduced in its ability to attach and then form aggregates on leaves and to cause an aggregate-associated killing of epidermal cells. Cell killing also depended on production of the major pectate lyase isozymes and the type II, but not the type III, secretion pathway in E. chrysanthemi. HecA homologs were found in bacterial pathogens of plants and animals and appear to be unique to pathogens and universal in necrogenic plant pathogens. Phylogenetic comparison of the conserved two-partner secretion domains in the proteins and the 16S rRNA sequences in respective bacteria revealed the two datasets to be fundamentally incongruent, suggesting horizontal acquisition of these genes. Furthermore, hecA and its two homologs in Yersinia pestis had a G+C content that was 10% higher than that of their genomes and similar to that of plant pathogenic Ralstonia, Xylella, and Pseudomonas spp. Our data suggest that filamentous hemagglutinin-like adhesins are broadly important virulence factors in both plant and animal pathogens.

  2. Relative Susceptibility of Quince, Pear, and Apple Cultivars to Fire Blight Following Greenhouse Inoculation

    Science.gov (United States)

    Fire blight caused by Erwinia amylovora (EA) is one of the most serious diseases of plants in the family Rosaceae, and Quince (Cydonia oblonga Mill.) is considered one of the most susceptible host genera. Apple (Malus sp.) and pear (Pyrus sp.) cultivars ranging from most susceptible to most resistan...

  3. Development of a Duplex PCR for Identification of Erwinia amylovora%步双重PCR法检测梨火疫病原细菌(Erwinia amylovora)

    Institute of Scientific and Technical Information of China (English)

    许景升; 徐进; 冯洁

    2008-01-01

    @@ 由梨火疫病原细菌(Erwinia amylovom)导致的火疫病(fire blight)是梨、苹果及其它蔷薇科植物上的毁灭性病害,我国将其定为对外一类检疫性有害生物.该病随种苗、果实及包装材料传播.

  4. Cyclic Di-GMP modulates the disease progression of Erwinia amylovora.

    Science.gov (United States)

    Edmunds, Adam C; Castiblanco, Luisa F; Sundin, George W; Waters, Christopher M

    2013-05-01

    The second messenger cyclic di-GMP (c-di-GMP) is a nearly ubiquitous intracellular signal molecule known to regulate various cellular processes, including biofilm formation, motility, and virulence. The intracellular concentration of c-di-GMP is inversely governed by diguanylate cyclase (DGC) enzymes and phosphodiesterase (PDE) enzymes, which synthesize and degrade c-di-GMP, respectively. The role of c-di-GMP in the plant pathogen and causal agent of fire blight disease Erwinia amylovora has not been studied previously. Here we demonstrate that three of the five predicted DGC genes in E. amylovora (edc genes, for Erwinia diguanylate cyclase), edcA, edcC, and edcE, are active diguanylate cyclases. We show that c-di-GMP positively regulates the secretion of the main exopolysaccharide in E. amylovora, amylovoran, leading to increased biofilm formation, and negatively regulates flagellar swimming motility. Although amylovoran secretion and biofilm formation are important for the colonization of plant xylem tissues and the development of systemic infections, deletion of the two biofilm-promoting DGCs increased tissue necrosis in an immature-pear infection assay and an apple shoot infection model, suggesting that c-di-GMP negatively regulates virulence. In addition, c-di-GMP inhibited the expression of hrpA, a gene encoding the major structural component of the type III secretion pilus. Our results are the first to describe a role for c-di-GMP in E. amylovora and suggest that downregulation of motility and type III secretion by c-di-GMP during infection plays a key role in the coordination of pathogenesis.

  5. First report of the crucifer pathogen Pseudomonas cannabina pv. alisalensis causing bacterial blight on radish (Raphanus sativus) in Germany

    Science.gov (United States)

    Pseudomonas cannabina pv. alisalensis is a severe pathogen of crucifers across the U.S. We compared a strain isolated from diseased radish (Raphanus sativus) in Germany to pathotypes and additional strains of P. cannabina pv. alisalensis and P. syringae pv. maculicola. We demonstrated that the patho...

  6. Cloning, purification, crystallization and 1.57 Å resolution X-ray data analysis of AmsI, the tyrosine phosphatase controlling amylovoran biosynthesis in the plant pathogen Erwinia amylovora.

    Science.gov (United States)

    Benini, Stefano; Caputi, Lorenzo; Cianci, Michele

    2014-12-01

    The Gram-negative bacterium Erwinia amylovora is a destructive pathogen of plants belonging to the Rosaceae family. Amongst its pathogenicity factors, E. amylovora produces the exopolysaccharide amylovoran, which contributes to the occlusion of plant vessels, causing wilting of shoots and eventually resulting in plant death. Amylovoran biosynthesis requires the presence of 12 genes (from amsA to amsL) clustered in the ams region of the E. amylovora genome. They mostly encode glycosyl transferases (AmsG, AmsB, AmsD, AmsE, AmsJ and AmsK), proteins involved in amylovoran translocation and assembly (AmsH, AmsL and AmsC), and also a tyrosine kinase (AmsA) and a tyrosine phosphatase (AmsI), which are both involved in the regulation of amylovoran biosynthesis. The low-molecular-weight protein tyrosine phosphatase AmsI was overexpressed as a His6-tagged protein in Escherichia coli, purified and crystallized. X-ray diffraction data were collected to a maximum resolution of 1.57 Å in space group P3121.

  7. Erwinia amylovora – the Causal Agent of Root Collar Necrosis of Apple Trees

    OpenAIRE

    Veljko Gavrilović; Svetlana Milijašević; Biljana Todorović; Svetlana Živković; Nenad Trkulja

    2008-01-01

    A large-scale outbreak of fire blight symptoms caused by Erwinia amylovora was recorded in pome fruit trees during 2007. In addition to fruit necrosis and shoot blight as the typical disease symptoms, dark purple necrosis was observed in the root collar area girdling the trunk just above the ground and thus withering the whole apple tree. Since similar symptoms on apple trees could be caused by E. amylovora or one of several phytopathogenic fungi of the genera Phomopsis and Phytophthora, an i...

  8. Characterization of a new ViI-like Erwinia amylovora bacteriophage phiEa2809.

    Science.gov (United States)

    Lagonenko, Alexander L; Sadovskaya, Olga; Valentovich, Leonid N; Evtushenkov, Anatoly N

    2015-04-01

    Erwinia amylovora is a Gram-negative plant pathogenic bacteria causing fire blight disease in many Rosaceae species. A novel E. amylovora bacteriophage, phiEa2809, was isolated from symptomless apple leaf sample collected in Belarus. This phage was also able to infect Pantoea agglomerans strains. The genome of phiEa2809 is a double-stranded linear DNA 162,160 bp in length, including 145 ORFs and one tRNA gene. The phiEa2809 genomic sequence is similar to the genomes of the Serratia plymutica phage MAM1, Shigella phage AG-3, Dickeya phage vB DsoM LIMEstone1 and Salmonella phage ViI and lacks similarity to described E. amylovora phage genomes. Based on virion morphology (an icosahedral head, long contractile tail) and genome structure, phiEa2809 was classified as a member of Myoviridae, ViI-like bacteriophages group. PhiEa2809 is the firstly characterized ViI-like bacteriophage able to lyse E. amylovora.

  9. Global small RNA chaperone Hfq and regulatory small RNAs are important virulence regulators in Erwinia amylovora.

    Science.gov (United States)

    Zeng, Quan; McNally, R Ryan; Sundin, George W

    2013-04-01

    Hfq is a global small RNA (sRNA) chaperone that interacts with Hfq-regulated sRNAs and functions in the posttranscriptional regulation of gene expression. In this work, we identified Hfq to be a virulence regulator in the Gram-negative fire blight pathogen Erwinia amylovora. Deletion of hfq in E. amylovora Ea1189 significantly reduced bacterial virulence in both immature pear fruits and apple shoots. Analysis of virulence determinants in strain Ea1189Δhfq showed that Hfq exerts pleiotropic regulation of amylovoran exopolysaccharide production, biofilm formation, motility, and the type III secretion system (T3SS). Further characterization of biofilm regulation by Hfq demonstrated that Hfq limits bacterial attachment to solid surfaces while promoting biofilm maturation. Characterization of T3SS regulation by Hfq revealed that Hfq positively regulates the translocation and secretion of the major type III effector DspE and negatively controls the secretion of the putative translocator HrpK and the type III effector Eop1. Lastly, 10 Hfq-regulated sRNAs were identified using a computational method, and two of these sRNAs, RprA and RyhA, were found to be required for the full virulence of E. amylovora.

  10. Differential lysine acetylation profiles of Erwinia amylovora strains revealed by proteomics.

    Science.gov (United States)

    Wu, Xia; Vellaichamy, Adaikkalam; Wang, Dongping; Zamdborg, Leonid; Kelleher, Neil L; Huber, Steven C; Zhao, Youfu

    2013-02-21

    Protein lysine acetylation (LysAc) has recently been demonstrated to be widespread in E. coli and Salmonella, and to broadly regulate bacterial physiology and metabolism. However, LysAc in plant pathogenic bacteria is largely unknown. Here we first report the lysine acetylome of Erwinia amylovora, an enterobacterium causing serious fire blight disease of apples and pears. Immunoblots using generic anti-lysine acetylation antibodies demonstrated that growth conditions strongly affected the LysAc profiles in E. amylovora. Differential LysAc profiles were also observed for two E. amylovora strains, known to have differential virulence in plants, indicating translational modification of proteins may be important in determining virulence of bacterial strains. Proteomic analysis of LysAc in two E. amylovora strains identified 141 LysAc sites in 96 proteins that function in a wide range of biological pathways. Consistent with previous reports, 44% of the proteins are involved in metabolic processes, including central metabolism, lipopolysaccharide, nucleotide and amino acid metabolism. Interestingly, for the first time, several proteins involved in E. amylovora virulence, including exopolysaccharide amylovoran biosynthesis- and type III secretion-associated proteins, were found to be lysine acetylated, suggesting that LysAc may play a major role in bacterial virulence. Comparative analysis of LysAc sites in E. amylovora and E. coli further revealed the sequence and structural commonality for LysAc in the two organisms. Collectively, these results reinforce the notion that LysAc of proteins is widespread in bacterial metabolism and virulence.

  11. Pathogen identification and pathogenic biology of sclerotiniose blight of rice stem rot in sodium bicarbonate soils%苏打盐碱地水稻秆腐菌核病病原鉴定及其生物学特性

    Institute of Scientific and Technical Information of China (English)

    张佳环; 刘巍; 潘姣; 邵玺文; 王志春; 敖振超; 柳建; 刘畅; 马周杰

    2015-01-01

    对苏打盐碱地水稻秆腐菌核病病原进行了分离、鉴定和生物学特性的研究。结果表明,该病原菌菌核黑色圆球状,表面凸凹形态,直径164~309μm,内部褐色拟薄壁组织;分生孢子淡褐色,1~3个隔膜,大小为(32~76)μm ×(5~22)μm;无性世代为 Nakataea sigmoidea ,有性世代为 Magnaporthe salvinii 。病原菌在25~30℃时生长较好,利用鼠李糖(P <0.05)、硝酸钙(P <0.05)和硫酸锌(P <0.01)能力最强,在利用碳氮源和微量元素方面,与弱酸性和寒冷地水稻秆腐菌核病病原存在差异。%The biological characteristics of the pathogen causing sclerotiniose blight of rice stem rot was isolated,i-dentified,and studied.The results showed that the pathogenic fungus sclerotia was black,knaggy,globular out-side,1 64-309 μm in diameter,and brown inside,and the pathogenic conidia were light brown,1 -3 septates, and (32-76)μm×(5-22)μm in size.The pathogenic asexual generation was Nakataea sigmoidea ,and the sexual generation was Magnaporthe salvinii .The optimum temperature was from 25 ℃ to 30 ℃ for growth of the patho-gen.Rhamnose (P <0.05 ),calcium nitrate (P < 0.05 ),and zinc sulfate (P < 0.01 )had significant promoting effect on the growth of the mycelia.The pathogen showed difference in the utilization of carbon source,nitrogen source,and microelements from the pathogens from non-sodium bicarbonate soils.

  12. Regional and field-specific factors affect the composition of fusarium head blight pathogens in subtropical no-till wheat agroecosystem of Brazil.

    Science.gov (United States)

    Del Ponte, Emerson M; Spolti, Piérri; Ward, Todd J; Gomes, Larissa B; Nicolli, Camila P; Kuhnem, Paulo R; Silva, Cleiltan N; Tessmann, Dauri J

    2015-02-01

    A multiyear survey of >200 wheat fields in Paraná (PR) and Rio Grande do Sul (RS) states was conducted to assess the extent and distribution of Fusarium graminearum species complex (FGSC) diversity in the southern Brazilian wheat agroecosystem. Five species and three trichothecene genotypes were found among 671 FGSC isolates from Fusarium head blight (FHB)-infected wheat heads: F. graminearum (83%) of the 15-acetyldeoxynivalenol (15-ADON) genotype, F. meridionale (12.8%) and F. asiaticum (0.4%) of the nivalenol (NIV) genotype, and F. cortaderiae (2.5%) and F. austroamericanum (0.9%) with either the NIV or the 3-ADON genotype. Regional differences in FGSC composition were observed, with F. meridionale and the NIV type being significantly (P28%) than in RS (≤9%). Within RS, F. graminearum was overrepresented in fields below 600 m in elevation and in fields with higher levels of FHB incidence (Pcomposition was not significantly influenced by previous crop or the stage of grain development at sampling. Habitat-specific differences in FGSC composition were evaluated in three fields by characterizing a total of 189 isolates collected from corn stubble, air above the wheat canopy, and symptomatic wheat kernels. Significant differences in FGSC composition were observed among these habitats (P96%) of isolates from corn stubble, whereas F. graminearum with the 15-ADON genotype was dominant (>84%) among isolates from diseased wheat kernels. Potential differences in pathogenic fitness on wheat were also suggested by a greenhouse competitiveness assay in which F. graminearum was recovered at much higher frequency (>90%) than F. meridionale from four wheat varieties inoculated with an equal mixture of F. graminearum and F. meridionale isolates. Taken together, the data presented here suggest that FGSC composition and, consequently, the trichothecene contamination in wheat grown in southern Brazil is influenced by host adaptation and pathogenic fitness. Evidence that F

  13. Erwinia tracheiphila colonization of cantaloupe fruits through flower inoculation

    Science.gov (United States)

    Cantaloupe (Cucumis melo var. cantalupensis) is a nutritious fresh fruit. Bacterial wilt, caused by Erwinia tracheiphila, is the most devastating cantaloupe disease globally. The pathogen is transmitted in nature by xylem-feeding spotted and striped cucumber beetles; other modes of infection have ...

  14. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars.

    Directory of Open Access Journals (Sweden)

    Cornelia Chizzali

    Full Text Available Pear (Pyrus communis is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS. Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in 'Harrow Sweet', while only PcBIS2 transcripts were detected in 'Alexander Lucas' and 'Conference'. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight was observed in the transition zone of 'Harrow Sweet', whereas the concentrations were ten times lower in 'Conference' and not even detectable in 'Alexander Lucas'. In 'Harrow Sweet', the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of 'Alexander Lucas' and 'Conference' advanced down to the rootstock, resulting in necrosis of the entire shoots.

  15. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars.

    Science.gov (United States)

    Chizzali, Cornelia; Swiddan, Asya K; Abdelaziz, Sahar; Gaid, Mariam; Richter, Klaus; Fischer, Thilo C; Liu, Benye; Beerhues, Ludger

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in 'Harrow Sweet', while only PcBIS2 transcripts were detected in 'Alexander Lucas' and 'Conference'. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight) was observed in the transition zone of 'Harrow Sweet', whereas the concentrations were ten times lower in 'Conference' and not even detectable in 'Alexander Lucas'. In 'Harrow Sweet', the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of 'Alexander Lucas' and 'Conference' advanced down to the rootstock, resulting in necrosis of the entire shoots.

  16. Detection of soft rot Erwinia spp. on seed potatoes: conductimetry versus dilution plating, PCR and serological assays

    NARCIS (Netherlands)

    Fraaije, B.A.; Appels, M.; Boer, de S.H.; Vuurde, van J.W.L.; Bulk, van den R.W.

    1997-01-01

    Automated conductance measurements in polypectate medium were used for the detection of pathogenic soft rot Erwinia spp. in potato peel extracts. The detection threshold for Erwinia carotovora subsp. atroseptica (Eca) in inoculated peel extracts was ca. 104 colony forming units (cfu) ml-1 when sampl

  17. Potential of osmoadaptation for improving Pantoea agglomerans E325 as biocontrol agent for fire blight of apple and pear

    Science.gov (United States)

    Pantoea agglomerans biocontrol strain E325 is the active ingredient in a commercial product for fire blight, a destructive disease of apple and pear initiated by Erwinia amylovora in flowers. Osmoadaptation, involving the combination of saline osmotic stress and osmolyte amendment to growth media, w...

  18. 桃枝枯病的症状及其病原鉴定%Identification of the pathogen of peach branch blight

    Institute of Scientific and Technical Information of China (English)

    方丽; 熊彩珍; 顾立明; 景筱荣; 金建芳; 王汉荣

    2013-01-01

    Peach branch blight, a serious new fungal disease, burst out in Fengqiao town, Jiaxing city and Zhangqi town, Cixi city in Zhejiang in recent years. The symptom firstly appeared on the base of shoot twig with tan to black pit scab causing the leaves above withering sharply. The disease cause death of branch even the whole peach tree, and reduced seed setting rate about 20% - 50% per year. To understand and control the disease, Koch's postulate was used and a species of fungus was found to be the pathogenic agent. The fungus yielded white to light olivesheen colony on potato saccharose agar (PSA) medium with short tiny cotton-shaped hypha, and produced black spherical pycnidium with ostiole. There were two kinds of condium generated by pathogen,α-type, fusiform, hyaline, unicellular, (5. 2-8. 7)μm × (1. 3-2. 7) μm;P-type, linear, hyaline, unicellular, 1 -3 oil globule, ( 11.5-26.2)μm × (0. 9 -2. 1) μm. The ribosomal ITS 1-5. 8S-ITS2 region was PCR amplified from genomic DNA from mycelium and obtained a sequence of 611 bp. A blast search from the GenBank revealed highest similarity (100% ) to Pho- mopsis amygdali sequences in Europe. The pathogen was identified as Phomopsis amygdali Delacr. J. J. Tuset & M.T. Portilla (Fusicoccum amygdali Delacr. ) associated with culture characters.%近年来,在浙江省重要的水蜜桃产区嘉兴凤桥镇、慈溪掌起镇等地发生了一种新的桃树病害——桃枝枯病.该病害引起桃树新梢嫩枝的基部位置出现环状棕褐色至黑褐色病斑,致使枝条病部以上叶片快速枯萎脱落,病害蔓延扩展迅速,可造成老枝的大量枯死,造成约20%~ 50%的产量损失,严重的致使桃树整株死亡.按柯赫氏法则对桃树病枝进行分离、纯化和致病性试验,明确桃枝枯病的病原为一种真菌,该真菌在PSA培养基上生长旺盛,菌丝为白色至淡橄榄色、短、微絮状,产生黑色球形分生孢子器,有孔口,产生两型分生孢子,α型分生

  19. Formation of biphenyl and dibenzofuran phytoalexins in the transition zones of fire blight-infected stems of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference'.

    Science.gov (United States)

    Chizzali, Cornelia; Khalil, Mohammed N A; Beuerle, Till; Schuehly, Wolfgang; Richter, Klaus; Flachowsky, Henryk; Peil, Andreas; Hanke, Magda-Viola; Liu, Benye; Beerhues, Ludger

    2012-05-01

    In the rosaceous subtribe Pyrinae (formerly subfamily Maloideae), pathogen attack leads to formation of biphenyls and dibenzofurans. Accumulation of these phytoalexins was studied in greenhouse-grown grafted shoots of Malus domestica cv. 'Holsteiner Cox' and Pyrus communis cv. 'Conference' after inoculation with the fire blight bacterium, Erwinia amylovora. No phytoalexins were found in leaves. However, both classes of defence compounds were detected in the transition zone of stems. The flanking stem segments above and below this zone, which were necrotic and healthy, respectively, were devoid of detectable phytoalexins. The transition zone of apple stems contained the biphenyls 3-hydroxy-5-methoxyaucuparin, aucuparin, noraucuparin and 2'-hydroxyaucuparin and the dibenzofurans eriobofuran and noreriobofuran. In pear, aucuparin, 2'-hydroxyaucuparin, noreriobofuran and in addition 3,4,5-trimethoxybiphenyl were detected. The total phytoalexin content in the transition zone of pear was 25 times lower than that in apple. Leaves and stems of mock-inoculated apple and pear shoots lacked phytoalexins. A number of biphenyls and dibenzofurans were tested for their in vitro antibacterial activity against some Erwinia amylovora strains. The most efficient compound was 3,5-dihydroxybiphenyl (MIC=115 μg/ml), the immediate product of biphenyl synthase which initiates phytoalexin biosynthesis.

  20. 'Preventie belangrijkste troef tegen Erwinia'

    NARCIS (Netherlands)

    Doorn, van J.

    2012-01-01

    De bollenteelt en -handel ondervindt aanzienlijke schade van de bacterieziekte Erwinia. Onderzoek wijst uit dat preventie het belangrijkste wapen is. Mogelijk bieden ook stofjes die de afweer van planten verbeteren een oplossing.

  1. Examining phylogenetic relationships of Erwinia and Pantoea species using whole genome sequence data.

    Science.gov (United States)

    Zhang, Yucheng; Qiu, Sai

    2015-11-01

    The genera Erwinia and Pantoea contain species that are devastating plant pathogens, non-pathogen epiphytes, and opportunistic human pathogens. However, some controversies persist in the taxonomic classification of these two closely related genera. The phylogenomic analysis of these two genera was investigated via a comprehensive analysis of 25 Erwinia genomes and 23 Pantoea genomes. Single-copy orthologs could be extracted from the Erwinia/Pantoea core-genome to reconstruct the Erwinia/Pantoea phylogeny. This tree has strong bootstrap support for almost all branches. We also estimated the in silico DNA-DNA hybridization (isDDH) and the average nucleotide identity (ANI) values between each genome; strains from the same species showed ANI values ≥96% and isDDH values >70%. These data confirm that whole genome sequence data provides a powerful tool to resolve the complex taxonomic questions of Erwinia/Pantoea, e.g. Pantoea agglomerans 299R was not clustered into a single group with other P. agglomerans strains, and the ANI values and isDDH values between them were Erwinia/Pantoea phylogeny.

  2. Phylogenetic analysis of PR genes in some pome fruit species with the emphasis on transcriptional analysis and ROS response under Erwinia amylovora inoculation in apple.

    Science.gov (United States)

    Hassani, Maryam; Salami, Seyed Alireza; Nasiri, Jaber; Abdollahi, Hamid; Ghahremani, Zahra

    2016-02-01

    Attempts were made to identify eight pathogenesis related (PR) genes (i.e., PR-1a, PR3-ch1, PR3-Ch2, PR3-Ch3, PR3-Ch4, PR3-Ch5, PR-5 and PR-8) from 27 genotypes of apple, quince and pear, which are induced in response to inoculation with the pathogen Erwinia amylovora, the causal agent of fire blight. Totally, 32 PR genes of different families were obtained, excepting PR3-Ch2 (amplified only in apple) and PR3-Ch4 (amplified only in apple and pear), the others were successfully amplified in all the genotypes of apple, quince and pear. Evolutionary, the genes of each family exhibited significant homology with each other, as the corresponded phylogenetic neighbor-joining-based dendrograms were taken into consideration. Meanwhile, according to the expression assay, it was deduced that the pathogen activity can significantly affect the expression levels of some selected PR genes of PR3-Ch2, PR3-Ch4, PR3-Ch5 and particularly Cat I in both resistant (MM-111) and semi-susceptible (MM-106) apple rootstocks. Lastly, it was concluded that the pathogen E. amylovora is able to stimulate ROS response, particularly using generation of hydrogen peroxide (H2O2) in both aforementioned apple rootstock.

  3. Isolation and Identification of L-asparaginase producing Erwinia strains which isolated from Potato Farms

    Directory of Open Access Journals (Sweden)

    Arastoo Badoei-Dalfard

    2016-09-01

    Full Text Available Introduction: L-Asparaginase can be effectively used for the treatment of lymphoblastic leukemia. The rapid growth of cancer cells are needed for L-asparagine abundant storage. L-asparaginase catalyzes the hydrolysis of L-asparagine into L-aspartic acid and ammonia. The purpose of this study was to isolate and identify the L-asparaginase producing Erwinia strains from the potato farms of Jiroft. Materials and methods: Pectolytic Erwinia species isolated from crumbling potato in M9 medium. The desired L-asparaginase producing bacteria were isolated based on the color changes. Biochemical-microbial and the plant pathogenicity tests of these strains were also investigated with potato and geranium. The L-asparaginase production and molecular detection of these Erwinia strains were also investigated. Results: In this study, L-asparaginase producing Erwinia was isolated on the CVP and M9 mediums. The inoculation of Erwinia strains on the potato and geranium plants showed that Er8 and Er11 species have the ability to cause plant pathogenicity. Results showed that the maximum pathogenicity of Er8 and Er11 was observed after 48 and 15 h of inoculation in potato and geranium plants, respectively. 16S rDNA sequencing and phylogenetic analyses exhibited that Er8 and Er11 strains were similar to Erwinia chrysanthemi with 98% homology. Discussion and conclusion: Because of several applications of the Erwinia L-asparaginase in various fields, isolated Erwinia and their L-asparaginase can be suitable for applied utilization.

  4. Effect of a waaL mutation on lipopolysaccharide composition, oxidative stress survival, and virulence in Erwinia amylovora.

    Science.gov (United States)

    Berry, Matthew C; McGhee, Gayle C; Zhao, Youfu; Sundin, George W

    2009-02-01

    Erwinia amylovora, the causal agent of fire blight, is an enterobacterial pathogen of Rosaceous plants including apple and pear. We have been studying the response of E. amylovora to oxidative stress because, during infection, the bacterium elicits an oxidative burst response in host plants. During the screening of a transposon mutant library for hydrogen peroxide sensitivity, we identified a mutant carrying an insertion in waaL, a gene involved in lipopolysaccharide biosynthesis, that was more sensitive to hydrogen peroxide than the parental wild-type strain. We also confirmed that a waaL mutant of Pseudomonas aeruginosa exhibited an increased sensitivity to hydrogen peroxide compared with the wild-type strain. The E. amylovora waaL mutant was also reduced in virulence, showed a decrease in twitching motility, and was more sensitive to polymyxin B than the wild type. Each of these phenotypes was complemented by the cloned waaL gene. Our results highlight the importance of the lipopolysaccharide layer to virulence in E. amylovora and the unexpected finding of an additional function of lipopolysaccharide in protection from oxidative stress in E. amylovora and P. aeruginosa.

  5. Role of electron transport chain of chloroplasts in oxidative burst of interaction between Erwinia amylovora and host cells.

    Science.gov (United States)

    Abdollahi, Hamid; Ghahremani, Zahra; Erfaninia, Kobra; Mehrabi, Rahim

    2015-05-01

    Erwinia amylovora is a necrogenic bacterium, causing the fire blight disease on many rosaceous plants. Triggering oxidative burst by E. amylovora is a key response by which host plants try to restrain pathogen spread. Electron transport chain (ETC) of chloroplasts is known as an inducible source of reactive oxygen species generation in various stresses. This research was performed to assess the role of this ETC in E. amylovora-host interaction using several inhibitors of this chain in susceptible and resistant apple and pear genotypes. All ETC inhibitors delayed appearance of disease necrosis, but the effects of methyl viologen, glutaraldehyde, and DCMU were more significant. In the absence of inhibitors, resistant genotypes showed an earlier and severe H2O2 generation and early suppression of redox dependent, psbA gene. The effects of inhibitors were corresponding to the redox potential of ETC inhibitory sites. In addition, delayed necrosis appearance was associated with the decreased disease severity and delayed H2O2 generation. These results provide evidences for the involvement of this ETC in host oxidative burst and suggest that chloroplast ETC has significant role in E. amylovora-host interaction.

  6. Identification of a major QTL together with several minor additive or epistatic QTLs for resistance to fire blight in apple in two related progenies

    NARCIS (Netherlands)

    Calenge, F.; Drouet, D.; Denance, C.; Weg, van de W.E.; Brisset, M.N.; Paulin, J.P.; Durel, C.E.

    2005-01-01

    Although fire blight, caused by the bacterium Erwinia amylovora, is one of the most destructive diseases of apple (Malus x domestica) worldwide, no major, qualitative gene for resistance to this disease has been identified to date in apple. We conducted a quantitative trait locus (QTL) analysis in t

  7. General research methods on pathogen of potato late blight (Phytophthora infestans)%马铃薯晚疫病菌的常规研究方法

    Institute of Scientific and Technical Information of China (English)

    朱杰华; 张志铭; 杨志辉

    2001-01-01

    马铃薯晚疫病菌很难分离培养并得到纯菌株,本文根据作者近8年的工作经验总结出了马铃薯晚疫病菌的一般研究方法,主要内容包括马铃薯晚疫病菌的症状识别,马铃薯晚疫病标样的采集方法,马铃薯晚疫病菌的分离纯化方法,马铃薯晚疫病菌的形态鉴定,马铃薯品种对晚疫病的抗病性评价方法等.%It's known that Phytophthora infestans is very difficult to be isolated and purified. According to the working experience in the past 8 years, the general research methods of potato late blight were summerized in this paper, which includes the method of sample collection of Phytophthora infestans, the methods of isolation and purification of P. infestans, evaluation of late blight resistance in potato germplasm.

  8. Differentiation of Erwinia amylovora and Erwinia pyrifoliae strains with single nucleotide polymorphisms and by synthesis of dihydrophenylalanine.

    Science.gov (United States)

    Gehring, I; Geider, K

    2012-07-01

    Fire blight has spread from North America to New Zealand, Europe, and the Mediterranean region. We were able to differentiate strains from various origins with a novel PCR method. Three Single Nucleotide Polymorphisms (SNPs) in the Erwinia amylovora genome were characteristic of isolates from North America and could distinguish them from isolates from other parts of the world. They were derived from the galE, acrB, and hrpA genes of strains Ea273 and Ea1/79. These genes were analyzed by conventional PCR (cPCR) and quantitative PCR (qPCR) with differential primer annealing temperatures. North-American E. amylovora strains were further differentiated according to their production of L: -2,5-dihydrophenylalanine (DHP) as tested by growth inhibition of the yeast Rhodotorula glutinis. E. amylovora fruit tree (Maloideae) and raspberry (rubus) strains were also differentiated by Single Strand Conformational Polymorphism analysis. Strains from the related species Erwinia pyrifoliae isolated in Korea and Japan were all DHP positive, but were differentiated from each other by SNPs in the galE gene. Differential PCR is a rapid and simple method to distinguish E. amylovora as well as E. pyrifoliae strains according to their geographical origin.

  9. Genome-wide identification of genes regulated by the Rcs phosphorelay system in Erwinia amylovora.

    Science.gov (United States)

    Wang, Dongping; Qi, Mingsheng; Calla, Bernarda; Korban, Schuyler S; Clough, Steven J; Cock, Peter J A; Sundin, George W; Toth, Ian; Zhao, Youfu

    2012-01-01

    The exopolysaccharide amylovoran is one of the major pathogenicity factors in Erwinia amylovora, the causal agent of fire blight of apples and pears. We have previously demonstrated that the RcsBCD phosphorelay system is essential for virulence by controlling amylovoran biosynthesis. We have also found that the hybrid sensor kinase RcsC differentially regulates amylovoran production in vitro and in vivo. To further understand how the Rcs system regulates E. amylovora virulence gene expression, we conducted genome-wide microarray analyses to determine the regulons of RcsB and RcsC in liquid medium and on immature pear fruit. Array analyses identified a total of 648 genes differentially regulated by RcsCB in vitro and in vivo. Consistent with our previous findings, RcsB acts as a positive regulator in both conditions, while RcsC positively controls expression of amylovoran biosynthetic genes in vivo but negatively controls expression in vitro. Besides amylovoran biosynthesis and regulatory genes, cell-wall and cell-envelope (membrane) as well as regulatory genes were identified as the major components of the RcsBC regulon, including many novel genes. We have also demonstrated that transcripts of rcsA, rcsC, and rcsD genes but not the rcsB gene were up-regulated when bacterial cells were grown in minimal medium or following infection of pear fruits compared with those grown in Luria Bertani medium. Furthermore, using the genome of E. amylovora ATCC 49946, a hidden Markov model predicted 60 genes with a candidate RcsB binding site in the intergenic region, 28 of which were identified in the microarray assay. Based on these findings as well as previous reported data, a working model has been proposed to illustrate how the Rcs phosphorelay system regulates virulence gene expression in E. amylovora.

  10. Erwinia amylovora type three-secreted proteins trigger cell death and defense responses in Arabidopsis thaliana.

    Science.gov (United States)

    Degrave, A; Fagard, M; Perino, C; Brisset, M N; Gaubert, S; Laroche, S; Patrit, O; Barny, M-A

    2008-08-01

    Erwinia amylovora is the bacterium responsible for fire blight, a necrotic disease affecting plants of the rosaceous family. E. amylovora pathogenicity requires a functional type three secretion system (T3SS). We show here that E. amylovora triggers a T3SS-dependent cell death on Arabidopsis thaliana. The plants respond by inducing T3SS-dependent defense responses, including salicylic acid (SA)-independent callose deposition, activation of the SA defense pathway, reactive oxygen species (ROS) accumulation, and part of the jasmonic acid/ethylene defense pathway. Several of these reactions are similar to what is observed in host plants. We show that the cell death triggered by E. amylovora on A. thaliana could not be simply explained by the recognition of AvrRpt2 ea by the resistance gene product RPS2. We then analyzed the role of type three-secreted proteins (T3SPs) DspA/E, HrpN, and HrpW in the induction of cell death and defense reactions in A. thaliana following infection with the corresponding E. amylovora mutant strains. HrpN and DspA/E were found to play an important role in the induction of cell death, activation of defense pathways, and ROS accumulation. None of the T3SPs tested played a major role in the induction of SA-independent callose deposition. The relative importance of T3SPs in A. thaliana is correlated with their relative importance in the disease process on host plants, indicating that A. thaliana can be used as a model to study their role.

  11. Potential Distribution of Alien Invasive Species and Risk Assessment: a Case Study of Erwinia amylovora in China

    Institute of Scientific and Technical Information of China (English)

    CHEN Chen; CHEN Juan; HU Bai-shi; JIANG Ying-hua; LIU Feng-quan

    2007-01-01

    Alien invasive species represent a severe risk to biodiversity and economy, as in the case of fire blight (Erwinia amylovora), a bacterial disease that originated in North America, which may be released into new locations by means of fruit trade. On the basis of the knowledge of Erwinia amylovora's biophysical characteristics and environmental data, the geographic information system (GIS) has been applied to determine areas where Erwinia amylovora can potentially invade China. Temperature and precipitation, during the blossoming period, are considered to be two critical factors affecting the Erwinia amylovora's suitable climatic zones. This spatial modeling approach was validated from a case study in Europe, where the occurrence of Erwinia amylovora has been proven. The model prediction agreed with the occurrence of the bacteria recorded in Europe, and the same procedure has been applied to produce a potential establishment area in China's two preferential apple cultivation regions, Bohai Bay region and Huangtu Altiplano region. It has been found that areas belonging to the high-risk category are more or less the main apple producing areas, accounting for their great economic importance in China. This methodology provides an initial baseline for assessment, prevention, and management of alien species that may become invasive under certain environmental conditions. In addition, this modeling approach provides a tool for policy makers to use, in making decisions on management practices where alien species are involved.

  12. Toetsen om Erwinia in bloembollen aan te tonen : onderzoek Erwinia

    NARCIS (Netherlands)

    Doorn, van J.; Hollinger, T.C.; Kampen, van D.; Vreeburg, P.J.M.; Leeuwen, van P.J.; Wolf, van der J.M.

    2007-01-01

    Binnen het Erwiniaproject is een aantal toetsen ontwikkeld en zijn andere nog in ontwikkeling. Deze toetsen moeten liefst ook latent aanwezige Erwiniastammen kunnen aantonen. Dit lukt door monsters in een voedingsbodem voor Erwinia te brengen en na kweek deze bacteriën aan te tonen met serologische

  13. Erwinia iniecta sp. nov., isolated from Russian wheat aphid (Diuraphis noxia).

    Science.gov (United States)

    Campillo, Tony; Luna, Emily; Portier, Perrine; Fischer-Le Saux, Marion; Lapitan, Nora; Tisserat, Ned A; Leach, Jan E

    2015-10-01

    Short, Gram-negative-staining, rod-shaped bacteria were isolated from crushed bodies of Russian wheat aphid [Diuraphis noxia (Kurdjumov)] and artificial diets after Russian wheat aphid feeding. Based on multilocus sequence analysis involving the 16S rRNA, atpD, infB, gyrB and rpoB genes, these bacterial isolates constitute a novel clade in the genus Erwinia, and were most closely related to Erwinia toletana. Representative distinct strains within this clade were used for comparisons with related species of Erwinia. Phenotypic comparisons using four distinct strains and average nucleotide identity (ANI) measurements using two distinct draft genomes revealed that these strains form a novel species within the genus Erwinia. The name Erwinia iniecta sp. nov. is proposed, and strain B120T ( = CFBP 8182T = NCCB 100485T) was designated the type strain. Erwinia iniecta sp. nov. was not pathogenic to plants. However, virulence to the Russian wheat aphid was observed.

  14. Identification and characterization of sesame southern blight pathogen%芝麻白绢病病原菌的分离鉴定及其生物学特性

    Institute of Scientific and Technical Information of China (English)

    王雅; 黄思良; 何朋朋; 牛小瑞; 黎起秦

    2013-01-01

    为了明确芝麻白绢病的病原菌,采用常规组织分离法分离病原菌,依据柯赫法则、形态特征及核糖体基因内转录间隔区(rDNA-ITS)序列进行鉴定,同时检测其部分生物学特性.结果表明:引起芝麻白绢病的病原菌为罗氏阿太菌Athelia rolfsii(无性世代:齐整小核菌Sclerotium rolfsii);该菌适宜生长温度为22 ~ 34C,最适生长温度为31℃;在pH4.0 ~ 9.0范围内均可生长,以pH6.5 ~ 7.0生长最好,表明微酸性至中性环境最有利于菌体生长;该菌虽能利用供试的13种碳源和8种氮源进行营养生长,但在以可溶性淀粉、蔗糖、葡萄糖、麦芽糖、L-阿拉伯糖和菊糖分别作为唯一碳源并配以硝酸盐为氮源的生长条件下不产生菌核,而在以葡萄糖为碳源并配以铵盐为氮源的生长条件下可产生菌核.与合成培养基相比,A.rolfsii在天然培养基上生长更好,可形成更多、更大的菌核.%To identify and characterize the pathogen causing sesame southern blight, the pathogen was isolated and its pathogenicity to sesame plants was confirmed based on Koch's postulates. Pathogen identification was carried out based on morphological characteristics and ribosomal DNA internal transcribed spacer ( rDNA - ITS) sequences. Partial biological characteristics of the pathogen were tested in vitro. The pathogen causing sesame southern blight was identified as Athelia rolfsii (anamorph: Sclerotium rolfsii). The temperatures suitable for its growth were 22 to 34℃ with the optimum temperature at 31℃. A. rolfsii grew well at a pH range of 4.0 to 9. 0 with the optimum pH at 6. 5 to 7. 0, indicating that slight acidic to neutral environment was more suitable for vegetative growth of the pathogen. The pathogen could utilize all of the 13 tested carbon sources for its vegetative growth. However, no sclerotia were developed on the media containing each of the seven substances (soluble starch, saccharose, glucose, maltose

  15. Erwinia amylovora expresses fast and simultaneously hrp/dsp virulence genes during flower infection on apple trees.

    Directory of Open Access Journals (Sweden)

    Doris Pester

    Full Text Available BACKGROUND: Pathogen entry through host blossoms is the predominant infection pathway of the gram-negative bacterium Erwinia amylovora leading to manifestation of the disease fire blight. Like in other economically important plant pathogens, E. amylovora pathogenicity depends on a type III secretion system encoded by hrp genes. However, timing and transcriptional order of hrp gene expression during flower infections are unknown. METHODOLOGY/PRINCIPAL FINDINGS: Using quantitative real-time PCR analyses, we addressed the questions of how fast, strong and uniform key hrp virulence genes and the effector dspA/E are expressed when bacteria enter flowers provided with the full defense mechanism of the apple plant. In non-invasive bacterial inoculations of apple flowers still attached to the tree, E. amylovora activated expression of key type III secretion genes in a narrow time window, mounting in a single expression peak of all investigated hrp/dspA/E genes around 24-48 h post inoculation (hpi. This single expression peak coincided with a single depression in the plant PR-1 expression at 24 hpi indicating transient manipulation of the salicylic acid pathway as one target of E. amylovora type III effectors. Expression of hrp/dspA/E genes was highly correlated to expression of the regulator hrpL and relative transcript abundances followed the ratio: hrpA>hrpN>hrpL>dspA/E. Acidic conditions (pH 4 in flower infections led to reduced virulence/effector gene expression without the typical expression peak observed under natural conditions (pH 7. CONCLUSION/SIGNIFICANCE: The simultaneous expression of hrpL, hrpA, hrpN, and the effector dspA/E during early floral infection indicates that speed and immediate effector transmission is important for successful plant invasion. When this delicate balance is disturbed, e.g., by acidic pH during infection, virulence gene expression is reduced, thus partly explaining the efficacy of acidification in fire blight

  16. Prospects for advanced late blight resistance breeding in potato

    Science.gov (United States)

    The potato late blight pathogen, Phytophthora infestans, is able to rapidly evolve to overcome resistance genes. The pathogen accomplishes this by secreting an arsenal of proteins, termed effectors, that function to modify host cells. Although hundreds of candidate effectors have been identified in ...

  17. Expression of Biphenyl Synthase Genes and Formation of Phytoalexin Compounds in Three Fire Blight-Infected Pyrus communis Cultivars

    Science.gov (United States)

    Chizzali, Cornelia; Swiddan, Asya K.; Abdelaziz, Sahar; Gaid, Mariam; Richter, Klaus; Fischer, Thilo C.; Liu, Benye; Beerhues, Ludger

    2016-01-01

    Pear (Pyrus communis) is an economically important fruit crop. Drops in yield and even losses of whole plantations are caused by diseases, most importantly fire blight which is triggered by the bacterial pathogen Erwinia amylovora. In response to the infection, biphenyls and dibenzofurans are formed as phytoalexins, biosynthesis of which is initiated by biphenyl synthase (BIS). Two PcBIS transcripts were cloned from fire blight-infected leaves and the encoded enzymes were characterized regarding substrate specificities and kinetic parameters. Expression of PcBIS1 and PcBIS2 was studied in three pear cultivars after inoculation with E. amylovora. Both PcBIS1 and PcBIS2 were expressed in ‘Harrow Sweet’, while only PcBIS2 transcripts were detected in ‘Alexander Lucas’ and ‘Conference’. Expression of the PcBIS genes was observed in both leaves and the transition zone of the stem; however, biphenyls and dibenzofurans were only detected in stems. The maximum phytoalexin level (~110 μg/g dry weight) was observed in the transition zone of ‘Harrow Sweet’, whereas the concentrations were ten times lower in ‘Conference’ and not even detectable in ‘Alexander Lucas’. In ‘Harrow Sweet’, the accumulation of the maximum phytoalexin level correlated with the halt of migration of the transition zone, whereby the residual part of the shoot survived. In contrast, the transition zones of ‘Alexander Lucas’ and ‘Conference’ advanced down to the rootstock, resulting in necrosis of the entire shoots. PMID:27410389

  18. Fire Blight Control: The Struggle Goes On. A Comparison of Different Fire Blight Control Methods in Switzerland with Respect to Biosafety, Efficacy and Durability

    Directory of Open Access Journals (Sweden)

    Michele Gusberti

    2015-09-01

    Full Text Available Fire blight (FB, caused by Erwinia amylovora, is one of the most important pome fruit pathogens worldwide. To control this devastating disease, various chemical and biological treatments are commonly applied in Switzerland, but they fail to keep the infection at an acceptable level in years of heavy disease pressure. The Swiss authorities therefore currently allow the controlled use of the antibiotic streptomycin against FB in years that are predicted to have heavy infection periods, but only one treatment per season is permitted. Another strategy for controlling Erwinia is to breed resistant/tolerant apple cultivars. One way of accelerating the breeding process is to obtain resistant cultivars by inserting one or several major resistance genes, using genetic engineering. To date, no study summarizing the impact of different FB control measures on the environment and on human health has been performed. This study consequently aims to compare different disease-control measures (biological control, chemical control, control by antibiotics and by resistant/tolerant apple cultivars obtained through conventional or molecular breeding applied against E. amylovora, considering different protection goals (protection of human health, environment, agricultural diversity and economic interest, with special emphasis on biosafety aspects. Information on each FB control measure in relation to the specified protection goal was assessed by literature searches and by interviews with experts. Based on our results it can be concluded that the FB control measures currently applied in Switzerland are safe for consumers, workers and the environment. However, there are several gaps in our knowledge of the human health and environmental impacts analyzed: data are missing (1 on long term studies on the efficacy of most of the analyzed FB control measures; (2 on the safety of operators handling streptomycin; (3 on residue analyses of Equisetum plant extract, the copper

  19. Pathogenicity and Biological Characters of Erwinia chyrsanthemi in Yunnan Province%云南水稻细菌性基腐病的致病性及病原生物学特性研究

    Institute of Scientific and Technical Information of China (English)

    周惠萍; 范静华; 徐自怀; 陈建斌

    2004-01-01

    通过对云南省水稻细菌性基腐病菌进行细菌学性状、致病性和温度测定,结果表明:该病原菌属于菊欧氏杆菌玉米致病变种(Erwinia chyrsanthemi pv.zeae),其生长适宜温度范围28~36 ℃,其中以32 ℃为最适,最低温度为10 ℃,最高温度42 ℃,致死温度53 ℃,10 min.

  20. The crystal structure of Erwinia amylovora levansucrase provides a snapshot of the products of sucrose hydrolysis trapped into the active site.

    Science.gov (United States)

    Wuerges, Jochen; Caputi, Lorenzo; Cianci, Michele; Boivin, Stephane; Meijers, Rob; Benini, Stefano

    2015-09-01

    Levansucrases are members of the glycoside hydrolase family and catalyse both the hydrolysis of the substrate sucrose and the transfer of fructosyl units to acceptor molecules. In the presence of sufficient sucrose, this may either lead to the production of fructooligosaccharides or fructose polymers. Aim of this study is to rationalise the differences in the polymerisation properties of bacterial levansucrases and in particular to identify structural features that determine different product spectrum in the levansucrase of the Gram-negative bacterium Erwinia amylovora (Ea Lsc, EC 2.4.1.10) as compared to Gram-positive bacteria such as Bacillus subtilis levansucrase. Ea is an enterobacterial pathogen responsible for the Fire Blight disease in rosaceous plants (e.g., apple and pear) with considerable interest for the agricultural industry. The crystal structure of Ea Lsc was solved at 2.77 Å resolution and compared to those of other fructosyltransferases from Gram-positive and Gram-negative bacteria. We propose the structural features, determining the different reaction products, to reside in just a few loops at the rim of the active site funnel. Moreover we propose that loop 8 may have a role in product length determination in Gluconacetobacter diazotrophicus LsdA and Microbacterium saccharophilum FFase. The Ea Lsc structure shows for the first time the products of sucrose hydrolysis still bound in the active site.

  1. HopX1 in Erwinia amylovora functions as an avirulence protein in apple and is regulated by HrpL.

    Science.gov (United States)

    Bocsanczy, A M; Schneider, D J; DeClerck, G A; Cartinhour, S; Beer, S V

    2012-02-01

    Fire blight is a devastating disease of rosaceous plants caused by the Gram-negative bacterium Erwinia amylovora. This pathogen delivers virulence proteins into host cells utilizing the type III secretion system (T3SS). Expression of the T3SS and of translocated and secreted substrates is activated by the alternative sigma factor HrpL, which recognizes hrp box promoters upstream of regulated genes. A collection of hidden Markov model (HMM) profiles was used to identify putative hrp boxes in the genome sequence of Ea273, a highly virulent strain of E. amylovora. Among potential virulence factors preceded by putative hrp boxes, two genes previously known as Eop3 and Eop2 were characterized. The presence of functionally active hrp boxes upstream of these two genes was confirmed by β-glucuronidase (GUS) assays. Deletion mutants of the latter candidate genes, renamed hopX1(Ea) and hopAK1(Ea), respectively, did not differ in virulence from the wild-type strain when assayed in pear fruit and apple shoots. The hopX1(Ea) deletion mutant of Ea273, complemented with a plasmid overexpressing hopX1(E)(a), suppressed the development of the hypersensitivity response (HR) when inoculated into Nicotiana benthamiana; however, it contributed to HR in Nicotiana tabacum and significantly reduced the progress of disease in apple shoots, suggesting that HopX1(Ea) may act as an avirulence protein in apple shoots.

  2. The tail-associated depolymerase of Erwinia amylovora phage L1 mediates host cell adsorption and enzymatic capsule removal, which can enhance infection by other phage.

    Science.gov (United States)

    Born, Yannick; Fieseler, Lars; Klumpp, Jochen; Eugster, Marcel R; Zurfluh, Katrin; Duffy, Brion; Loessner, Martin J

    2014-07-01

    The depolymerase enzyme (DpoL1) encoded by the T7-like phage L1 efficiently degrades amylovoran, an important virulence factor and major component of the extracellular polysaccharide (EPS) of its host, the plant pathogen Erwinia amylovora. Mass spectrometry analysis of hydrolysed EPS revealed that DpoL1 cleaves the galactose-containing backbone of amylovoran. The enzyme is most active at pH 6 and 50°C, and features a modular architecture. Removal of 180 N-terminal amino acids was shown not to affect enzyme activity. The C-terminus harbours the hydrolase activity, while the N-terminal domain links the enzyme to the phage particle. Electron microscopy demonstrated that DpoL1-specific antibodies cross-link phage particles at their tails, either lateral or frontal, and immunogold staining confirmed that DpoL1 is located at the tail spikes. Exposure of high-level EPS-producing Er. amylovora strain CFBP1430 to recombinant DpoL1 dramatically increased sensitivity to the Dpo-negative phage Y2, which was not the case for EPS-negative mutants or low-level EPS-producing Er. amylovora. Our findings indicate that enhanced phage susceptibility is based on enzymatic removal of the EPS capsule, normally a physical barrier to Y2 infection, and that use of DpoL1 together with the broad host range, virulent phage Y2 represents an attractive combination for biocontrol of fire blight.

  3. Morphological characterization of fungi associated with the ascochyta blight complex and pathogenic variability of Mycosphaerella pinodes on field pea crops in central Alberta

    Directory of Open Access Journals (Sweden)

    Hafiz Ahmed

    2015-02-01

    Full Text Available Field pea crops in central Alberta were surveyed for ascochyta blight from 2011 to 2012 and fungal isolates were recovered from foliar lesions on selected plants. Cultural and microscopic characterization of the 275 isolates obtained revealed that 272 were of Mycosphaerella pinodes and three were of Phoma medicaginis var. pinodella. Ascochyta pisi or Phoma koolunga were not identified. Isolates of M. pinodes were divided into two groups, GI and GII, based on visual assessment of culture characteristics. GI isolates (light to dark, mostly gray colony color; pycnidial distribution radial and concentric; conidia 10.5–14.5 × 4.2–6.2 μm most with one septum, occasionally two, constricted at the septum; spore mass light buff to flesh color were predominant (83%, while GII isolates (dark to gray colony color; pycnidia abundant; conidia 8–16 × 3.5–6.2 μm most with 1 septum, constricted at the septum; spore mass light buff to flesh color were less common (17%. The cultures of GII isolates were similar to recent descriptions of A. pisi, but they differed in spore color. In a host differential study, 13 pathotypes of M. pinodes were identified from 110 single-spore isolates. Pathotype I was predominant (88 isolates and virulent on all nine differential genotypes. The other pathotypes (pathotypes II–XIII were rare (1–6 isolates of each. Comparison of the present results with earlier studies suggests that pathotype I has been prevalent for many years, and that its aggressiveness on the host differentials has increased over time. Emphasis should be placed on breeding for resistance to M. pinodes in field pea cultivars intended for deployment in central Alberta.

  4. Erwinia amylovora effector protein Eop1 suppresses PAMP-triggered immunity in Malus

    Science.gov (United States)

    Erwinia amylovora (Ea) utilizes a type three secretion system (T3SS) to deliver effector proteins into plant host cells. Several Ea effectors have been identified based on their sequence similarity to plant and animal bacterial pathogen effectors; however, the function of the majority of Ea effecto...

  5. Differential lysine acetylation profiles of Erwinia amylovora strains revealed by proteomics

    Science.gov (United States)

    Protein lysine acetylation (LysAc) in bacteria has recently been demonstrated to be widespread in E. coli and Salmonella and to broadly regulate bacterial physiology and metabolism. However, LysAc in plant pathogenic bacteria is largely unknown. Here we report the lysine acetylome of Erwinia amylovo...

  6. Overleving van Erwinia in water : waakzaamheid geboden

    NARCIS (Netherlands)

    Doorn, van J.; Houtenbos, R.; Wolf, van der J.M.

    2008-01-01

    PPO en Plant Research International hebben al eerder de rotbacterie Erwinia onderzocht, omdat Erwinia een vochtminnende bacterie is, is besmetting via water, ook vanuit de lucht een reëel gevaar. Omdat water op veel manieren op bollenbedrijven toegepast wordt is onderzocht hoe lang deze rotveroorzak

  7. Absence of lysogeny in wild populations of Erwinia amylovora and Pantoea agglomerans.

    Science.gov (United States)

    Roach, Dwayne R; Sjaarda, David R; Sjaarda, Calvin P; Ayala, Carlos Juarez; Howcroft, Brittany; Castle, Alan J; Svircev, Antonet M

    2015-05-01

    Lytic bacteriophages are in development as biological control agents for the prevention of fire blight disease caused by Erwinia amylovora. Temperate phages should be excluded as biologicals since lysogeny produces the dual risks of host resistance to phage attack and the transduction of virulence determinants between bacteria. The extent of lysogeny was estimated in wild populations of E. amylovora and Pantoea agglomerans with real-time polymerase chain reaction primers developed to detect E. amylovora phages belonging to the Myoviridae and Podoviridae families. Pantoea agglomerans, an orchard epiphyte, is easily infected by Erwinia spp. phages, and it serves as a carrier in the development of the phage-mediated biological control agent. Screening of 161 E. amylovora isolates from 16 distinct geographical areas in North America, Europe, North Africa and New Zealand and 82 P. agglomerans isolates from southern Ontario, Canada showed that none possessed prophage. Unstable phage resistant clones or lysogens were produced under laboratory conditions. Additionally, a stable lysogen was recovered from infection of bacterial isolate Ea110R with Podoviridae phage ΦEa35-20. These laboratory observations suggested that while lysogeny is possible in E. amylovora, it is rare or absent in natural populations, and there is a minimal risk associated with lysogenic conversion and transduction by Erwinia spp. phages.

  8. Variation suggestive of horizontal gene transfer at a lipopolysaccharide (lps) biosynthetic locus in Xanthomonas oryzae pv. oryzae, the bacterial leaf blight pathogen of rice

    Science.gov (United States)

    Patil, Prabhu B; Sonti, Ramesh V

    2004-01-01

    Background In animal pathogenic bacteria, horizontal gene transfer events (HGT) have been frequently observed in genomic regions that encode functions involved in biosynthesis of the outer membrane located lipopolysaccharide (LPS). As a result, different strains of the same pathogen can have substantially different lps biosynthetic gene clusters. Since LPS is highly antigenic, the variation at lps loci is attributed to be of advantage in evading the host immune system. Although LPS has been suggested as a potentiator of plant defense responses, interstrain variation at lps biosynthetic gene clusters has not been reported for any plant pathogenic bacterium. Results We report here the complete sequence of a 12.2 kb virulence locus of Xanthomonas oryzae pv. oryzae (Xoo) encoding six genes whose products are homologous to functions involved in LPS biosynthesis and transport. All six open reading frames (ORFs) have atypical G+C content and altered codon usage, which are the hallmarks of genomic islands that are acquired by horizontal gene transfer. The lps locus is flanked by highly conserved genes, metB and etfA, respectively encoding cystathionine gamma lyase and electron transport flavoprotein. Interestingly, two different sets of lps genes are present at this locus in the plant pathogens, Xanthomonas campestris pv. campestris (Xcc) and Xanthomonas axonopodis pv. citri (Xac). The genomic island is present in a number of Xoo strains from India and other Asian countries but is not present in two strains, one from India (BXO8) and another from Nepal (Nepal624) as well as the closely related rice pathogen, Xanthomonas oryzae pv. oryzicola (Xoor). TAIL-PCR analysis indicates that sequences related to Xac are present at the lps locus in both BXO8 and Nepal624. The Xoor strain has a hybrid lps gene cluster, with sequences at the metB and etfA ends, being most closely related to sequences from Xac and the tomato pathogen, Pseudomonas syringae pv. tomato respectively

  9. Population and Pathogenicity of Fusarium spp.Causing Wheat Head Blight in Northeast of China%东北地区小麦赤霉病镰孢菌种群及其致病性测定

    Institute of Scientific and Technical Information of China (English)

    潘晓静; 陈楠; 姚远; 刘限; 高增贵

    2015-01-01

    为了明确东北地区小麦赤霉病镰孢菌的种群组成及分布,分别从辽宁省沈阳市、黑龙江省哈尔滨市和密山市、内蒙古自治区扎兰屯市、呼伦贝尔市和通辽市等地区采集小麦赤霉病病样,经单孢分离纯化共得到118株镰孢菌,传统形态学鉴定的基础上,采用基因组DNA的 EF-1α序列分析技术进行了镰孢菌种类的辅助鉴定,确定属于7个种:禾谷镰孢菌为优势种,分离频率为64.41%,藤仓镰孢菌为次优势种,分离频率为18.64%;燕麦镰孢菌、尖孢镰孢菌、木贼镰孢菌、锐顶镰孢菌和轮枝镰孢菌的分离频率分别为5.08%,3.39%,3.39%,3.39%,1.70%。同时,在玉米成株期进行了致病性测定,结果表明,小麦赤霉病镰孢菌可以侵染玉米,较玉米茎腐镰孢菌的致病力低。%To determine population structure and distribution of Fusarium species causing head blight of wheat , 60 wheat samples showing symptoms of Fusarium head blight from 15 areas 8 cities and counties were collectted in Northeast of China .A total of 118 Fusarium isolates were identified based on morphological characters and modern molecular systematics method .The results showed that 118 Fusarium isolates belong to 7 species , Fusarium gra-minearum was the most prevalent species ,representing 64.41%of the total isolates,followed by Fusarium fujikuroi, representing 18.64%,Fusarium avenaceum,Fusarium oxysporum,Fusarium equiseti,Fusarium acuminatum and Fu-sarium verticillioides representing 5.08%,3.39%,3.39%,3.39%and 1.70%.At the same time,their pathogenic-ity were determined in stem of adult-stage maize ,the results showed that Fusarium graminearum isolated from wheat can infect maize ,but the pathogenicity of Fusarium graminearum causing maize stalk rot were significantly greater than the Fusarium graminearum causing wheat head scab .

  10. Host-mediated gene silencing of a single effector gene from the potato pathogen Phytophthora infestans imparts partial resistance to late blight disease.

    Science.gov (United States)

    Sanju, Suman; Siddappa, Sundaresha; Thakur, Aditi; Shukla, Pradeep K; Srivastava, Nidhi; Pattanayak, Debasis; Sharma, Sanjeev; Singh, B P

    2015-11-01

    RNA interference (RNAi) has proved a powerful genetic tool for silencing genes in plants. Host-induced gene silencing of pathogen genes has provided a gene knockout strategy for a wide range of biotechnological applications. The RXLR effector Avr3a gene is largely responsible for virulence of oomycete plant pathogen Phytophthora infestans. In this study, we attempted to silence the Avr3a gene of P. infestans through RNAi technology. The P. infestans inoculation resulted in lower disease progression and a reduction in pathogen load, as demonstrated by disease scoring and quantification of pathogen biomass in terms of Pi08 repetitive elements, respectively. Transgenic plants induced moderate silencing of Avr3a, and the presence and/or expression of small interfering RNAs, as determined through Northern hybridization, indicated siRNA targeted against Avr3a conferred moderate resistance to P. infestans. The single effector gene did not provide complete resistance against P. infestans. Although the Avr3a effector gene could confer moderate resistance, for complete resistance, the cumulative effect of effector genes in addition to Avr3a needs to be considered. In this study, we demonstrated that host-induced RNAi is an effective strategy for functional genomics in oomycetes.

  11. Identification of Erwinia species isolated from apples and pears by differential PCR.

    Science.gov (United States)

    Gehring, I; Geider, K

    2012-04-01

    Many pathogenic and epiphytic bacteria isolated from apples and pears belong to the genus Erwinia; these include the species E. amylovora, E. pyrifoliae, E. billingiae, E. persicina, E. rhapontici and E. tasmaniensis. Identification and classification of freshly isolated bacterial species often requires tedious taxonomic procedures. To facilitate routine identification of Erwinia species, we have developed a PCR method based on species-specific oligonucleotides (SSOs) from the sequences of the housekeeping genes recA and gpd. Using species-specific primers that we report here, differentiation was done with conventional PCR (cPCR) and quantitative PCR (qPCR) applying two consecutive primer annealing temperatures. The specificity of the primers depends on terminal Single Nucleotide Polymorphisms (SNPs) that are characteristic for the target species. These PCR assays enabled us to distinguish eight Erwinia species, as well as to identify new Erwinia isolates from plant surfaces. When performed with mixed bacterial cultures, they only detected a single target species. This method is a novel approach to classify strains within the genus Erwinia by PCR and it can be used to confirm other diagnostic data, especially when specific PCR detection methods are not already available. The method may be applied to classify species within other bacterial genera.

  12. Determination of Quantities of Host Protein after Infection with Erwinia amylovora of Apple, Pear And Quince Cultivars

    Directory of Open Access Journals (Sweden)

    Şerife Çetin

    2014-10-01

    Full Text Available Fire blight disease caused by Erwinia amylovora is a destructive bacterial pathogen mainly on pears, apples and quinces from Rosaceae family. In this study, it was aimed determination of total protein amounts in different apple cultivars (Braeburn, Fuji, Gala and Golden, pear cultivars (Santa Maria and Williams and quince cultivars (Eşme and Ekmek in the infections of two virulent E. amylovora strains (Ea234-1 and Ea240-3 according as the time. It was taken leaf samples after leaf inoculation with E. amylovora (108 CFU ml-1 at 24th, 36th and 72nd hours. For verification of the infections, re-isolations were made from bacteria inoculated plants and the agent was identified as E. amylovora by biochemical, physiological and molecular tests. In determining the amounts of total protein and in the SDS-PAGE analyses were used Bradford and Laemmli methods, respectively, and absorbance values of protein extracts derived from the leaf samples taken, were obtained at 595 nm wavelength. According to the findings obtained; after infection of E. amylovora in the apple varieties comparing to controls, total protein concentrations at 24th hours increased and a decrease in the amount of 36th to 72nd hours and Braeburn has the highest protein content was determined. In the pear varieties, while total protein concentrations at 24th and 36th hours increased, a decrease in the amount of 72nd hour, and Santa Maria variety has the highest protein content was detected. In the quince varieties, total protein concentrations at 72th hour increased and Eşme variety has the highest protein content was identified. As a result of SDS-PAGE analysis, protein fractions which have different molecular weights were obtained. The protein bands were defined approximately 55-70 kDa and 35-55 kDa molecule weight on apple and quince varieties, respectively and also approx. 55-70 kDa in pear varieties.

  13. Isolation and Identification of Maize Seedling Blight Pathogen%玉米苗枯病病原菌的分离及鉴定

    Institute of Scientific and Technical Information of China (English)

    何瑞; 王建明

    2012-01-01

    Morphology and molecular biological characteristics of the pathogen for Fusarium moniliforme, and the pathogen ITS region sequences were analyzed, the isolates of PCR amplification product by agarose gel electrophoresis, have 1 about 600 bp fragments, as determined by serial, determine the fragment length is 592 bp, and the gene bank of Fusarium moniliforme gene sequence alignment, further confirmed that the pathogenic bacteria for Fusarium moniliforme.%对引起山西昔阳县玉米苗枯病的病原菌进行了形态学和分子生物学鉴定,根据分生孢子形态和萌发特性将该菌鉴定为串珠镰刀菌(F.moniliforme);并采用分子生物学方法,对该病菌rDNA-ITS的扩增与序列进行测定,测得序列与F.moniliforme同源性为100%.

  14. Pathogenicity and Biological Characters of Erwinia chrysanthemi pv. zeae in Guangdong Province%广东水稻细菌性基腐病的致病性及生物学特性研究

    Institute of Scientific and Technical Information of China (English)

    刘琼光; 曾宪铭

    1999-01-01

    通过一系列的细菌学性状和致病性试验,鉴定出广东省水稻一种新病害--水稻细菌性基腐病的病原为菊欧氏杆菌玉米致病变种Erwinia chrysanthemi pv. zeae,并对该病原菌的生物学特性进行了进一步的研究.结果表明:病菌生长的最低温度为12 ℃,适宜温度范围28~36 ℃,其中以32 ℃最适,最高温度41 ℃,致死温度53 ℃、10 min.该病菌生长的pH值范围为pH 5~11,其中pH7最适宜.

  15. Bioinformatics Analysis on a Novel T3SS Pathogenicity Islands of Erwinia amylovora Ea273 and its Homology in Erwinia%梨火疫病菌新的Ⅲ型泌出系统(T3SS)分析及在其他菌株中的分布

    Institute of Scientific and Technical Information of China (English)

    柴一秋; BOCSANCZY Ana Maria; BEER Steven; 王金生

    2010-01-01

    试验分析了梨火疫病菌(Erwinia amylovora)Ea273基因组上新的T3SS(Trpe Ⅲ Secretion System,T3SS)致病岛特征并验证它们在Erwinia属的21个菌株基因组上是否存在.生物信息学分析发现,Ea273基因组不同位点上存在两个新的T3SS致病岛,称为PAI-2和PAI-3,大小分别为32.889kb和21.792kb.经PCR和Southern blot证明Ea273、Ea246、Ea262、Ea528以及Ea644 5个菌株基因组存在PAI-2和PAI-3.PAI-3和PAI-2在基因结构和组成上相似,同源性超过70%,PAI-3包含PAI-2所有基因,两者和昆虫内生菌S. gtossinidius编码的T3SS的SSR-1致病岛非常相似.

  16. 五味子叶枯病病原菌的生物学特性及其拮抗放线菌的初筛∗%Biological Characteristics of the Pathogen of Schisandra chinensis Leaf Blight and Screening of Antagonistic Actinomycete Strain against the Pathogen

    Institute of Scientific and Technical Information of China (English)

    王壮; 张爱华; 雷锋杰; 匙坤; 张连学

    2015-01-01

    采用室内平皿培养法研究五味子叶枯病菌的生物学特性,平板对峙法筛选拮抗放线菌。结果表明:叶枯病病原菌在PDA及PDBA培养基上最有利于菌丝生长及产孢;温度对菌丝生长和产孢量影响较大,25℃为其最适温度,同样温度下,黑暗条件显著有利于产生孢子,光照更利于菌丝生长;pH 6~7为菌株生长最适pH;最佳碳、氮源分别为果糖及蛋白胨;孢子致死温度测定为54℃。筛选到2株对五味子叶枯病病原菌拮抗效果较好的放线菌A-25-8和A38,其拮抗率分别为66�26%和66�10%。%Petri dish culture method was used to study biological characteristics of Schisandra chinensis leaf blight pathogen, and plate confrontation method was used to screen antagonistic actino⁃mycetes. The results showed that mycelia grew faster and spore generated more in medium PDA and PDBA. Temperature affected mycelia growth and spore generation at 25 ℃. At the same tempera⁃ture, dark condition was significantly beneficial for spore generation and light condition was benefi⁃cial for mycelial growth. pH 6~7 was most suitable for the pathogen. Fructose and peptone were the best carbon source and nitrogen source for the pathogen. Deadly temperature for the spore was 54 ℃. Two strains ( A-25-8 and A38 ) of the 28 actinomycetes had potential antagonistic effects against leaf blight pathogen and inhibition rate was 66�26% and 66�10%, respectively.

  17. Emerging Needle Blight Diseases in Atlantic Pinus Ecosystems of Spain

    Directory of Open Access Journals (Sweden)

    Esther Ortíz de Urbina

    2016-12-01

    Full Text Available Red band needle blight caused by Dothistroma septosporum and D. pini, and brown spot needle blight caused by Lecanosticta acicola provoke severe and premature defoliation in Pinus, and subsequent reduction of photosynthetic surfaces, vitality, and growth in young and adult trees. The recurrent damage results in branch and tree death. Until recently, pine needle blight diseases have had only minor impacts on native and exotic forest trees in the North of Spain, but in the past five years, these pathogen species have spread widely and caused severe defoliation and mortality in exotic and native plantations of Pinus in locations where they were not detected before. In an attempt to understand the main causes of this outbreak and to define the effectiveness of owners’ management strategies, four research actions were implemented: a survey of the management activities implemented by the owners to reduce disease impact, the evaluation of specific symptoms and damage associated with infection, and the identification of the causative pathogenic species and their reproductive capacity. Morphological characteristics of the fungus and molecular identification were consistent with those of Lecanosticta acicola and Dothistroma spp., D. septosporum, D. Pini, and both mating types were present for the three identified pathogens. The local silvicultural management performed, mainly pruning and thinning, was not resulting in the expected improvement. The results of this study can be applied to establish guidelines for monitoring and controlling the spread of needle blight pathogens.

  18. Evidence for a reversible drought induced shift in the species composition of mycotoxin producing Fusarium head blight pathogens isolated from symptomatic wheat heads.

    Science.gov (United States)

    Beyer, Marco; Pogoda, Friederike; Pallez, Marine; Lazic, Joëlle; Hoffmann, Lucien; Pasquali, Matias

    2014-07-16

    Fusarium species are fungal plant pathogens producing toxic secondary metabolites such as deoxynivalenol (DON), 15-acetyl-deoxynivalenol (15AcDON) and nivalenol (NIV). In Luxembourg, the Fusarium species composition isolated from symptomatic winter wheat heads was dominated by Fusarium graminearum sensu stricto strains (genetic 15AcDON chemotype) between the years 2009 and 2012, except for 2011, when Fusarium culmorum strains (genetic NIV chemotype) dominated the pathogen complex. Previous reports indicated that F. graminearum sensu stricto (genetic 15AcDON chemotype) was also most frequently isolated from randomly sampled winter wheat kernels including symptomatic as well as asymptomatic kernels in 2007 and 2008. The annual precipitation (average of 10 weather stations scattered across the country) decreased continuously from 924.31mm in 2007 over 917.15mm in 2008, to 843.38mm in 2009, 736.24mm in 2010, and 575.09mm in 2011. In 2012, the annual precipitation increased again to 854.70mm. Hardly any precipitation was recorded around the time of wheat anthesis in the years 2010 and 2011, whereas precipitation levels >50mm within the week preceding anthesis plus the week post anthesis were observed in the other years. The shift to genetic NIV chemotype F. culmorum strains in 2011 was accompanied by a very minor elevation of average NIV contents (2.9ngg(-1)) in the grain. Our data suggest that high NIV levels in Luxembourgish winter wheat are at present rather unlikely, because the indigenous F. culmorum strains with the genetic NIV chemotype seem to be outcompeted under humid in vivo conditions by F. graminearum DON producing strains on the one hand and seem to be inhibited - even though to a lower extent than DON producing strains - under dry in vivo conditions on the other hand.

  19. Identification and pathogenicity assay of the pathogen of walnut blight in Beijing%北京地区核桃黑斑病病原菌的分离、致病性测定和16S rDNA序列分析

    Institute of Scientific and Technical Information of China (English)

    陈善义; 陶万强; 王合; 李金钟; 周涛

    2011-01-01

    Walnut blight is a severe disease on walnut production. In 2008, a suspected blight disease was found in walnut trees planted in rural area of Beijing. In order to confirm the taxonomic status of the pathogen, bacteria were isolated and purified from plant samples with typical symptoms. Pathogenicity was confirmed by artificial inoculation of healthy walnut branches and leaves with a suspension of an isolated bacterial strain. A 1.5 kb of 16S rDNA fragment amplified by PCR using bacterial 16S rDNA universal primers was cloned into pMD-18T vector. Sequencing analysis revealed that the fragment contains 1453 nueleotides which is highly similar to the 16S rDNA of bacterial pathogen Xanthomonas eampestris.%核桃黑斑病是危害核桃生产的重要细菌病害,造成树势衰弱,减产严重,甚至树体死亡.2008年在北京郊区栽植的幼树上发现疑似病害,且呈爆发之势.为确定其病原菌分类地位,用组织分离法分离核桃黑斑病菌,纯化培养后用针刺接种法回接到健康核桃树枝条和叶片上,14d后叶片和枝条分别出现典型病斑,接种发病组织再分离所得病菌性状、16SrDNA与初分离的一致,完成柯赫氏法则验证;以分离的核桃黑斑病菌总DNA为模板,采用细菌16SrDNA的通用引物,通过PCR扩增到约1.5kb的片段,克隆到pMD-18T载体.测序结果表明克隆的16SrDNA片段长为1 453个核苷酸,通过GenBank上BLAST分析,表明该病原细菌为Xanthomonas camperstris.

  20. Erwinia berokkent pootgoedsector vele miljoenen schade

    NARCIS (Netherlands)

    Prins, H.; Breukers, A.

    2008-01-01

    De besmetting met Erwinia ontwikkelt zich de laatste jaren tot een serieus probleem in de pootgoedsector. Voor telers ontstaat inkomensderving door lagere opbrengstprijzen en onbruikbare pootgoedvoorraden. Handelshuizen lijden schade door margedaling en reclameringen. Een aantasting van het imago va

  1. Competitive Between Phytophthora Infestans Effectors Leads to Increased Aggressiveness on Plants Containing Broad-Spectrum Late Blight Resistance

    Science.gov (United States)

    Potato late blight is a particularly destructive plant disease caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary. Late blight has remained particularly problematic despite intensive breeding efforts to integrate resistance into cultivated potato. This is due to the pathogen’s ab...

  2. Is Erwinia te beheersen? Een literatuurstudie over rotproblemen in diverse gewassen om met deze kennis Erwinia in bolgewassen beter te kunnen aanpakken

    NARCIS (Netherlands)

    Doorn, van J.; Wolf, J.

    2005-01-01

    Het meeste onderzoek aan Erwinia-bacteriën is uitgevoerd bij aardappel. In dit gewas worden drie ziekteverwekkende Erwinia-soorten gevonden: Erwinia carotovora subsp. atroseptica (Eca), Erwinia chrysanthemi (Echr) en Erwinia carotovora subsp. carotovora (Ecc). Eca speelt in gematigde klimaatsgebiede

  3. Induction of antimicrobial 3-deoxyflavonoids in pome fruit trees controls fire blight.

    Science.gov (United States)

    Halbwirth, Heidrun; Fischer, Thilo C; Roemmelt, Susanne; Spinelli, Francesco; Schlangen, Karin; Peterek, Silke; Sabatini, Emidio; Messina, Christian; Speakman, John-Bryan; Andreotti, Carlo; Rademacher, Wilhelm; Bazzi, Carlo; Costa, Guglielmo; Treutter, Dieter; Forkmann, Gert; Stich, Karl

    2003-01-01

    Fire blight, a devastating bacterial disease in pome fruits, causes severe economic losses worldwide. Hitherto, an effective control could only be achieved by using antibiotics, but this implies potential risks for human health, livestock and environment. A new approach allows transient inhibition of a step in the flavonoid pathway, thereby inducing the formation of a novel antimicrobial 3-deoxyflavonoid controlling fire blight in apple and pear leaves. This compound is closely related to natural phytoalexins in sorghum. The approach does not only provide a safe method to control fire blight: Resistance against different pathogens is also induced in other crop plants.

  4. Selection of a biocontrol agent based on a potential mechanism of action: degradation of nicotinic acid, a growth factor essential for Erwinia amylovora.

    Science.gov (United States)

    Paternoster, Thomas; Défago, Geneviève; Duffy, Brion; Gessler, Cesare; Pertot, Ilaria

    2010-12-01

    This work describes a medium-based screening method for selecting microbial biocontrol agents against Erwinia amylovora based on the degradation of a specific growth factor. Erwinia amylovora, the causal agent of the devastating fire blight disease, requires nicotinic acid or nicotinamide as an essential growth factor. Potential biocontrol agents are either selected for antimicrobial production in plate or directly on immature pears or apple blossoms. In this work, we have attempted to streamline the selection of a new potential biocontrol agent with a lower risk of non-target effects by isolation based on the ability to degrade nicotinic acid in vitro, using therefore few plant materials. A total of 735 bacteria and 1237 yeast were isolated from apple blossoms and pre-screened for nicotinic acid-degradation. Pseudomonas rhizosphaerae strain JAN was able to degrade both nicotinic acid and nicotinamide. Mutants deficient in this ability were constructed. JAN, but not the mutants, controlled E. amylovora on pear slices. On detached apple blossoms, JAN colonized apple hypanthia and strongly suppressed E. amylovora growth. Under greenhouse conditions, JAN was more effective in controlling blossom blight than P. fluorescens A506, a commercial biocontrol agent of fire blight unable to degrade nicotinic acid and nicotinamide.

  5. EFEKTIFITAS DAYA HAMBAT BAKTERI Streptomyces sp TERHADAP Erwinia sp PENYEBAB PENYAKIT BUSUK REBAH PADA TANAMAN LIDAH BUAYA (Aloe barbadensis Mill

    Directory of Open Access Journals (Sweden)

    SARMILA TASNIM

    2013-05-01

    Full Text Available Streptomyces sp was conducted from December 2010 - June 2011 at the Laboratoryof Microbiology, Biology Department, Math and Science Faculty, UdayanaUniversity Bukit Jimbaran-Bali. Implementation stages of the research consisted ofisolation and testing of the antibiotic activity Streptomyces sp to inhibit growthbacterial pathogens Erwinia sp as a cause of disease in plants fallen foul (Soft rot ofAloe barbadensis Mill.The results of this study have eight isolates of Streptomyces spwith macroscopic and microscopic characters are varied. Furthermore, all isolateswere obtained and then tested against antibiotic activity to inhibit growth the bacteriaErwinia sp. Test results obtained by Streptomyces sp that has the most effective ininhibiting the ability of the bacteria Erwinia sp isolates are Streptomyces sp2for (45%.

  6. The olive fly endosymbiont, "Candidatus Erwinia dacicola," switches from an intracellular existence to an extracellular existence during host insect development.

    Science.gov (United States)

    Estes, Anne M; Hearn, David J; Bronstein, Judith L; Pierson, Elizabeth A

    2009-11-01

    As polyphagous, holometabolous insects, tephritid fruit flies (Diptera: Tephritidae) provide a unique habitat for endosymbiotic bacteria, especially those microbes associated with the digestive system. Here we examine the endosymbiont of the olive fly [Bactrocera oleae (Rossi) (Diptera: Tephritidae)], a tephritid of great economic importance. "Candidatus Erwinia dacicola" was found in the digestive systems of all life stages of wild olive flies from the southwestern United States. PCR and microscopy demonstrated that "Ca. Erwinia dacicola" resided intracellularly in the gastric ceca of the larval midgut but extracellularly in the lumen of the foregut and ovipositor diverticulum of adult flies. "Ca. Erwinia dacicola" is one of the few nonpathogenic endosymbionts that transitions between intracellular and extracellular lifestyles during specific stages of the host's life cycle. Another unique feature of the olive fly endosymbiont is that unlike obligate endosymbionts of monophagous insects, "Ca. Erwinia dacicola" has a G+C nucleotide composition similar to those of closely related plant-pathogenic and free-living bacteria. These two characteristics of "Ca. Erwinia dacicola," the ability to transition between intracellular and extracellular lifestyles and a G+C nucleotide composition similar to those of free-living relatives, may facilitate survival in a changing environment during the development of a polyphagous, holometabolous host. We propose that insect-bacterial symbioses should be classified based on the environment that the host provides to the endosymbiont (the endosymbiont environment).

  7. 中国番茄晚疫病菌群体表型结构主要研究%Research on the phenotype structure of tomato late blight pathogen population in China

    Institute of Scientific and Technical Information of China (English)

    郑喜清; 邸娜; 李旭红

    2015-01-01

    番茄晚疫病是由致病疫霉侵染所致,是一种毁灭性的蔬菜病害,发生频繁且危害日益严重。文章从番茄晚疫病菌生理小种、交配型及其对甲霜灵敏感性几方面进行了阐述,为番茄抗病品种的选育和晚疫病的综合防治提供参考。%Tomato late blight is caused by Phytophthora infestans, a destructive disease of vegetables, frequent and serious. The physiological races, mating types and metaiaxyl sensitivity of Phytophthora infestans were reviewed in this paper, the objective of this study was to provide a reference to breed disease resistant varieties and control of tomato late blight.

  8. Cloud Activation Characteristics of Airborne Erwinia carotovora Cells.

    Science.gov (United States)

    Franc, Gary D.; Demott, Paul J.

    1998-10-01

    Several strains of plant pathogenic bacteria, Erwinia carotovora carotovora and E. carotovora atroseptica, were observed to be active as cloud condensation nuclei (CCN). The CCN supersaturation spectra of bacterial aerosols were measured in the laboratory and compared to the activity of ammonium sulfate. Approximately 25%-30% of the aerosolized bacterial cells activated droplets at 1% water supersaturation compared to 80% activation of the ammonium sulfate aerosol. Physical and numerical simulations of cloud droplet activation and growth on bacteria were also performed. Both simulations predict that aerosolized bacteria will be incorporated into cloud droplets during cloud formation. Results strongly support the hypothesis that significant numbers of the tested bacterial strains are actively involved in atmospheric cloud formation and precipitation processes following natural aerosolization and vertical transport to cloud levels.

  9. Trefkans detectie Erwinia in pootgoed toegenomen

    NARCIS (Netherlands)

    Wolf, van der J.M.

    2014-01-01

    Binnen het Deltaplan Erwinia is een methode ontwikkeld die met grotere zekerheid de aanwezigheid van de Erwinia’s, Pectobacterium en Dickeya, in pootgoed kan aantonen. De verbeterde methode maakt gebruik gemaakt van uitschotknollen die op de sorteerband uitgeselecteerd zijn en een toets waarbij de g

  10. Deltaplan Erwinia hielp piepers en bollen vooruit

    NARCIS (Netherlands)

    Dwarswaard, A.; Doorn, van J.

    2013-01-01

    Vier jaar lang werkte de bloembollensector samen met de aardappelsector aan de gezamenlijke bacterieziekte Erwinia. In beide sectoren was al het nodige voorwerk gedaan. Op 12 december 2012 werd het project afgesloten. Met de hoop op toch nog enige vorm van voortzetting.

  11. Ziek en Zeer : Erwinia chrysanthemi in Amaryllidaceae

    NARCIS (Netherlands)

    Vink, P.

    2011-01-01

    In dit artikel een verslag van het onderzoek naar de gevoeligheid van narcissen voor de bacterie Erwinia chrysanthemi (tegenwoordig Dickeya dadantii). Uit een infectieproef is gebleken dat deze bacterie tijdens een reguliere bollenteelt in Lisse niet in staat was om narcisbollen aan te tasten. Toch

  12. Carbohydrate and ethane release with Erwinia carotovora subspecies betavasculorum--induced necrosis.

    Science.gov (United States)

    Kuykendall, L David; Hunter, William J

    2008-02-01

    Erwinia carotovora subspecies betavasculorum, also known as E. betavasculorum and Pectobacterium betavasculorum, is a soil bacterium that has the capacity to cause root rot necrosis of sugarbeets. The qualitatively different pathogenicity exhibited by the virulent E. carotovora strain and two avirulent strains, a Citrobacter sp. and an Enterobacter cloacae, was examined using digital analysis of photographic evidence of necrosis as well as for carbohydrate, ethane, and ethylene release compared with uninoculated potato tuber slices. Visual scoring of necrosis was superior to digital analysis of photographs. The release of carbohydrates and ethane from potato tuber slices inoculated with the soft rot necrosis-causing Erwinia was significantly greater than that of potato tuber slices that had not been inoculated or that had been inoculated with the nonpathogenic E. cloacae and Citrobacter sp. strains. Interestingly, ethylene production from potato slices left uninoculated or inoculated with the nonpathogenic Citrobacter strain was 5- to 10-fold higher than with potato slices inoculated with the pathogenic Erwinia strain. These findings suggest that (1) carbohydrate release might be a useful measure of the degree of pathogenesis, or relative virulence; and that (2) bacterial suppression of ethylene formation may be a critical step in root rot disease formation.

  13. Erwinia tasmaniensis sp. nov., a non-phytopathogenic bacterium from apple and pear trees.

    Science.gov (United States)

    Geider, Klaus; Auling, Georg; Du, Zhiqiang; Jakovljevic, Vladimir; Jock, Susanne; Völksch, Beate

    2006-12-01

    Bacteria were isolated from flowers and bark of apple and pear trees at three places in Australia. In Victoria, Tasmania and Queensland, strains with white colonies on nutrient agar were screened for dome-shaped colony morphology on agar with sucrose and were found to be closely related by several criteria. The isolates were not pathogenic on apples or pears. They were characterized by a polyphasic approach including microbiological and API assays as well as fatty acid methyl ester analysis, DNA-DNA hybridization and DNA sequencing. For molecular classification, the 16S rRNA cistron and the conserved genes gpd and recA of these bacteria were investigated. Together with other taxonomic criteria, the results of these studies indicate that the bacteria belong to a novel separate species, which we propose to name Erwinia tasmaniensis sp. nov., with the type strain Et1/99(T) (=DSM 17950(T)=NCPPB 4357(T)). From DNA-DNA hybridization kinetics, microbiological characteristics and nucleotide sequence analyses, this species is related to pathogenic Erwinia species, but also to the epiphytic species Erwinia billingiae.

  14. New Erwinia-like organism causing cervical lymphadenitis.

    Science.gov (United States)

    Shin, Sang Yop; Lee, Mi Young; Song, Jae-Hoon; Ko, Kwan Soo

    2008-09-01

    The first case of cervical lymphadenitis due to infection by a new Erwinia-like organism is reported. The organism was identified initially as Pantoea sp. by a Vitek 2-based assessment but was finally identified as a member of the genus Erwinia by 16S rRNA gene sequence analysis. The isolate displayed 98.9% 16S rRNA gene sequence similarity to that of E. tasmaniensis and showed phenotypic characteristics that were different from other Erwinia species.

  15. The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid inhibits growth of Erwinia amylovora and acts as a seed germination-arrest factor.

    Science.gov (United States)

    Lee, Xiaoyun; Azevedo, Mark D; Armstrong, Donald J; Banowetz, Gary M; Reimmann, Cornelia

    2013-02-01

    The Pseudomonas aeruginosa antimetabolite L-2-amino-4-methoxy-trans-3-butenoic acid (AMB) shares biological activities with 4-formylaminooxyvinylglycine, a related molecule produced by Pseudomonas fluorescens WH6. We found that culture filtrates of a P. aeruginosa strain overproducing AMB weakly interfered with seed germination of the grassy weed Poa annua and strongly inhibited growth of Erwinia amylovora, the causal agent of the devastating orchard crop disease known as fire blight. AMB was active against a 4-formylaminooxyvinylglycine-resistant isolate of E. amylovora, suggesting that the molecular targets of the two oxyvinylglycines in Erwinia do not, or not entirely, overlap. The AMB biosynthesis and transport genes were shown to be organized in two separate transcriptional units, ambA and ambBCDE, which were successfully expressed from IPTG-inducible tac promoters in the heterologous host P. fluorescens CHA0. Engineered AMB production enabled this model biocontrol strain to become inhibitory against E. amylovora and to weakly interfere with the germination of several graminaceous seeds. We conclude that AMB production requires no additional genes besides ambABCDE and we speculate that their expression in marketed fire blight biocontrol strains could potentially contribute to disease control.

  16. Identification of QTLs for resistance to fire blight (Erwinia amylovora) in Malus sieversii

    Science.gov (United States)

    Malus sieversii (Ms) is the progenitor of the domestic apple. Ms PI613981 is elite scion material collected at a xerophytic site in Kazakhstan from a tree free of disease and insect damage. The F1 family GMAL4593 (‘Royal Gala’ X PI631981) is segregating for resistance to both apple scab and fire bl...

  17. Prevalence of Candidatus Erwinia dacicola in wild and laboratory olive fruit fly populations and across developmental stages.

    Science.gov (United States)

    Estes, Anne M; Hearn, David J; Burrack, Hannah J; Rempoulakis, Polychronis; Pierson, Elizabeth A

    2012-04-01

    The microbiome of the olive fruit fly, Bactrocera oleae (Gmelin), a worldwide pest of olives (Olea europaea L.), has been examined for >100 yr as part of efforts to identify bacteria that are plant pathogens vectored by the fly or are beneficial endosymbionts essential for the fly's survival and thus targets for possible biological control. Because tephritid fruit flies feed on free-living bacteria in their environment, distinguishing between the transient, acquired bacteria of their diet and persistent, resident bacteria that are vertically transmitted endosymbionts is difficult. Several culture-dependent and -independent studies have identified a diversity of species in the olive fruit fly microbiome, but they have not distinguished the roles of the microbes. Candidatus Erwinia dacicola, has been proposed to be a coevolved endosymbiont of the olive fruit fly; however, this was based on limited samples from two Italian populations. Our study shows that C. Erwinia dacicola was present in all New and Old World populations and in the majority of individuals of all life stages sampled in 2 yr. Olive fruit flies reared on olives in the laboratory had frequencies of C. Erwinia dacicola similar to that of wild populations; however, flies reared on artificial diets containing antibiotics in the laboratory rarely had the endosymbiont. The relative abundance of C. Erwinia dacicola varied across development stages, being most abundant in ovipositing females and larvae. This uniform presence of C. Erwini dacicola suggests that it is a persistent, resident endosymbiont of the olive fruit fly.

  18. Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea.

    Science.gov (United States)

    Deng, Jian Xin; Lee, Ji Hye; Paul, Narayan Chandra; Cho, Hye Sun; Lee, Hyang Burm; Yu, Seung Hun

    2015-03-01

    In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus) leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

  19. Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea

    Directory of Open Access Journals (Sweden)

    Jian Xin Deng

    2015-03-01

    Full Text Available In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

  20. Late blight and early blight resistance from Solanum hougasii introgressed into Solanum tuberosum

    Science.gov (United States)

    Late blight, caused by Phytophthora infestans, and early blight, incited by Alternaria solani,are the two most widely occurring foliar diseases of potato in the U.S. Resistance to both diseases is necessary if growers are to reduce fungicide applications. Field resistance to late blight has previous...

  1. HOPX1 Ea (Eop3) in Erwinia Amylovora functions as an avirulence gene in apple and is regulated by HRPL

    Science.gov (United States)

    Fire blight is a devastating disease of rosaceous plants caused by the Gram-negative bacterium E. amylovora. This pathogen delivers virulence proteins into host cells utilizing the Type-Three Secretion System (T3SS). Expression of the T3SS and associated substrates are activated by the alternative s...

  2. Novel species of Botryosphaeriaceae associated with shoot blight of pistachio.

    Science.gov (United States)

    Chen, ShuaiFei; Li, GuoQing; Liu, FeiFei; Michailides, Themis J

    2015-01-01

    Various species of phytopathogenic Botryosphaeriaceae were identified previously from pistachio trees worldwide. Disease symptoms caused by pathogens in Botryosphaeriaceae on pistachio include panicle and shoot blight, leaf defoliation, fruit discoloration and decay. In this study species of Botryosphaeriaceae were collected from blighted pistachio shoots in Arizona, USA, and Greece. The aims of this study were to identify these Botryosphaeriaceae isolates and to test their pathogenicity to pistachio. The fungi were identified based on comparisons of DNA sequence data of the nuclear rDNA internal transcribed spacer region (ITS), a partial translation elongation factor 1-alpha gene (TEF1), a partial β-tubulin gene (TUB2) and morphological characteristics. Results indicated that some isolates collected from pistachio represent two previously undescribed species, which we described here as Lasiodiplodia americana sp. nov. from the United States and Neofusicoccum hellenicum sp. nov. from Greece. Field inoculations of L. americana and N. hellenicum on branches of four pistachio cultivars showed that both L. americana and N. hellenicum are pathogenic on pistachio. The four pistachio cultivars differed in their susceptibility to the Botryosphaeriaceae species. Results of this study suggested that the two new species of Botryosphaeriaceae need to be monitored carefully to determine the distribution of these pathogens and the possible spread to other areas.

  3. Discovering the next generation of late blight resistance genes – can we battle Phytophthora infestans evolution

    Science.gov (United States)

    Potato late blight, caused by the oomycete pathogen Phytophthora infestans, is one of the most destructive plant diseases. RB from Solanum bulbocastanum encodes a CC-NB-LRR (CNL) protein that confers partial resistance to most P. infestans isolates through its recognition of the corresponding pathog...

  4. The role of oospores in the epidemiology of potato late blight

    NARCIS (Netherlands)

    Kessel, G.J.T.; Andersson, B.; Widmark, A.K.; Yuen, J.E.; Evenhuis, A.; Turkensteen, L.J.; Lehtinen, A.; Nielsen, B.; Ravnskov, S.; Hansen, J.G.; Hermansen, A.; Brurberg, M.B.; Nordskog, B.

    2009-01-01

    Potato late blight (Phytophthora infestans) is a plant disease feared globally by farmers and the potato industry. P. infestans is a heterothallic oomycete with two mating types. Until recently the pathogen was limited to surviving between seasons as living mycelia in its host plant in most parts of

  5. R gene stacking by trans- and cisgenesis to achieve durable late blight resistance in potato

    NARCIS (Netherlands)

    Zhu, S.

    2014-01-01

    Among the many diseases of potato (Solanum tuberosum L.), which is the third food crop in the world after wheat and rice, late blight caused by the oomycete pathogen Phytophthora infestans, is one of the most serious diseases. In the last century, major resistance (R) genes were introgressed mainly

  6. Does infection by southern root-knot nematode influence development of Phytophthora blight in pepper?

    Science.gov (United States)

    The southern root-knot nematode, Meloidogyne incognita, and Phytophthora capsici, the causal agent of Phytophthora blight, are both important pathogens of pepper (Capsicum annuum L.) in the U.S. and worldwide. Although there is significant information in the literature about the responses of pepper...

  7. Bacteria of the genus Erwinia found in the spermatheca of the laurel psyllid Trioza alacris.

    Science.gov (United States)

    Marchini, Daniela; Ciolfi, Silvia; Gottardo, Marco; Marri, Laura

    2014-12-01

    Psylloidea are economically important insects causing serious damage to plants by direct feeding and/or vectoring bacterial pathogens. Results reported here indicate the presence of extracellular bacteria in the spermatheca of egg-laying Trioza alacris females. One phylotype, sharing 99 % identity with the non-phytopathogenic bacterium Erwinia tasmaniensis, was identified regardless of methods applied or insect sampling year and location. This is the first study, achieved by ultrastructural, cultural, and 16S rRNA gene-based analysis, of an insect spermatheca microbiota.

  8. A novel plasmid pEA68 of Erwinia amylovora and the description of a new family of plasmids.

    Science.gov (United States)

    Ismail, Emadeldeen; Blom, Jochen; Bultreys, Alain; Ivanović, Milan; Obradović, Aleksa; van Doorn, Joop; Bergsma-Vlami, Maria; Maes, Martine; Willems, Anne; Duffy, Brion; Stockwell, Virginia O; Smits, Theo H M; Puławska, Joanna

    2014-12-01

    Recent genome analysis of Erwinia amylovora, the causal agent of fire blight disease on Rosaceae, has shown that the chromosome is highly conserved among strains and that plasmids are the principal source of genomic diversity. A new circular plasmid, pEA68, was found in E. amylovora strain 692 (LMG 28361), isolated in Poland from Sorbus (mountain ash) with fire blight symptoms. Annotation of the 68,763-bp IncFIIa-type plasmid revealed that it contains 79 predicted CDS, among which two operons (tra, pil) are associated with mobility. The plasmid is maintained stably in E. amylovora and does not possess genes associated with antibiotic resistance or known virulence genes. Curing E. amylovora strain 692 of pEA68 did not influence its virulence in apple shoots nor amylovoran synthesis. Of 488 strains of E. amylovora from seventeen countries, pEA68 was only found in two additional strains from Belgium. Although the spread of pEA68 is currently limited to Europe, pEA68 comprises, together with pEA72 and pEA78 both found in North America, a new plasmid family that spans two continents.

  9. Erwinia pyrifoliae, a new pathogen on strawberry in the Netherlands

    NARCIS (Netherlands)

    Wenneker, M.; Bergsma-Vlami, M.M.

    2015-01-01

    BACKGROUND: During the late spring of 2013 strawberry plants grown under protection (Fragaria x ananassa cv. Elsanta) were found at several locations in the Netherlands showing an intense brown to black discoloration of their immature fruits, their fruit calyx and the attached stems. OBJECTIVE: Iden

  10. Mutation of the Erwinia amylovora argD gene causes arginine auxotrophy, nonpathogenicity in apples, and reduced virulence in pears.

    Science.gov (United States)

    Ramos, Laura S; Lehman, Brian L; Peter, Kari A; McNellis, Timothy W

    2014-11-01

    Fire blight is caused by Erwinia amylovora and is the most destructive bacterial disease of apples and pears worldwide. In this study, we found that E. amylovora argD(1000)::Tn5, an argD Tn5 transposon mutant that has the Tn5 transposon inserted after nucleotide 999 in the argD gene-coding region, was an arginine auxotroph that did not cause fire blight in apple and had reduced virulence in immature pear fruits. The E. amylovora argD gene encodes a predicted N-acetylornithine aminotransferase enzyme, which is involved in the production of the amino acid arginine. A plasmid-borne copy of the wild-type argD gene complemented both the nonpathogenic and the arginine auxotrophic phenotypes of the argD(1000)::Tn5 mutant. However, even when mixed with virulent E. amylovora cells and inoculated onto immature apple fruit, the argD(1000)::Tn5 mutant still failed to grow, while the virulent strain grew and caused disease. Furthermore, the pCR2.1-argD complementation plasmid was stably maintained in the argD(1000)::Tn5 mutant growing in host tissues without any antibiotic selection. Therefore, the pCR2.1-argD complementation plasmid could be useful for the expression of genes, markers, and reporters in E. amylovora growing in planta, without concern about losing the plasmid over time. The ArgD protein cannot be considered an E. amylovora virulence factor because the argD(1000)::Tn5 mutant was auxotrophic and had a primary metabolism defect. Nevertheless, these results are informative about the parasitic nature of the fire blight disease interaction, since they indicate that E. amylovora cannot obtain sufficient arginine from apple and pear fruit tissues or from apple vegetative tissues, either at the beginning of the infection process or after the infection has progressed to an advanced state.

  11. EDS1 contributes to nonhost resistance of Arabidopsis thaliana against Erwinia amylovora.

    Science.gov (United States)

    Moreau, Manon; Degrave, Alexandre; Vedel, Régine; Bitton, Frédérique; Patrit, Oriane; Renou, Jean-Pierre; Barny, Marie-Anne; Fagard, Mathilde

    2012-03-01

    Erwinia amylovora causes fire blight in rosaceous plants. In nonhost Arabidopsis thaliana, E. amylovora triggers necrotic symptoms associated with transient bacterial multiplication, suggesting either that A. thaliana lacks a susceptibility factor or that it actively restricts E. amylovora growth. Inhibiting plant protein synthesis at the time of infection led to an increase in necrosis and bacterial multiplication and reduced callose deposition, indicating that A. thaliana requires active protein synthesis to restrict E. amylovora growth. Analysis of the callose synthase-deficient pmr4-1 mutant indicated that lack of callose deposition alone did not lead to increased sensitivity to E. amylovora. Transcriptome analysis revealed that approximately 20% of the genes induced following E. amylovora infection are related to defense and signaling. Analysis of mutants affected in NDR1 and EDS1, two main components of the defense-gene activation observed, revealed that E. amylovora multiplied ten times more in the eds1-2 mutant than in the wild type but not in the ndr1-1 mutant. Analysis of mutants affected in three WRKY transcription factors showing EDS1-dependent activation identified WRKY46 and WRKY54 as positive regulators and WRKY70 as a negative regulator of defense against E. amylovora. Altogether, we show that EDS1 is a positive regulator of nonhost resistance against E. amylovora in A. thaliana and hypothesize that it controls the production of several effective defenses against E. amylovora through the action of WRKY46 and WRKY54, while WRKY70 acts as a negative regulator.

  12. Exopolysaccharides favor the survival of Erwinia amylovora under copper stress through different strategies.

    Science.gov (United States)

    Ordax, Mónica; Marco-Noales, Ester; López, María M; Biosca, Elena G

    2010-09-01

    Erwinia amylovora causes fire blight, a destructive disease of rosaceous plants very difficult to control. We demonstrated that copper, employed to control plant diseases, induces the "viable-but-nonculturable" (VBNC) state in E. amylovora. Moreover, it was previously reported that copper increases production of its main exopolysaccharide (EPS), amylovoran. In this work, the copper-complexing ability of amylovoran and levan, other major EPS of E. amylovora, was demonstrated. Following this, EPS-deficient mutants were used to determine the role of these EPSs in survival of this bacterium in AB mineral medium with copper, compared to their wild type strain and AB without copper. Total, viable and culturable counts of all strains were monitored for six months. With copper, a larger fraction of the viable population of EPS mutants entered into the VBNC state, and earlier than their wild type strain, showing the contribution of both EPSs to long-term survival in a culturable state. Further, we demonstrated that both EPSs can be used as carbon source by E. amylovora under deprivation conditions. Overall, these previously unreported functions of amylovoran and levan provide survival advantages for E. amylovora, which could contribute to its enhanced persistence in nature.

  13. Neofusicoccum ribis Associated with Leaf Blight on Rubber (Hevea brasiliensis in Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    A. I. C. Nyaka Ngobisa

    2013-03-01

    Full Text Available Hevea brasiliensis is a natural source of rubber and an important plantation tree species in Malaysia. Leaf blight disease caused by Fusicoccum substantially reduces the growth and performance of H. brasiliensis. The aim of this study was to use a combination of both morphological characteristics and molecular data to clarify the taxonomic position of the fungus associated with leaf blight disease. Fusicoccum species were isolated from infected leaves collected from plantations at 3 widely separated locations – Selangor, Perak, and Johor states – in Peninsular Malaysia in 2010. All the isolates were identified according to their conidial patterns and DNA sequences generated from internal transcribed spacers (ITS1 and ITS2, the 5.8S rRNA, and an unknown locus (BotF15 containing microsatellite repeats. Based on taxonomic and sequence data, Neofusicoccum ribis was identified as the main cause of leaf blight disease in H. brasiliensis in commercial plantations in Malaysia. A pathogenicity trial on detached leaves further confirmed that N. ribis causes leaf blight disease. N. ribis is an important leaf pathogen, and its detection in Malaysia has important implications for future planting of H. brasiliensis.

  14. High-throughput screening of Erwinia chrysanthemi pectin methylesterase variants using carbohydrate microarrays

    DEFF Research Database (Denmark)

    Øbro, Jens; Sørensen, Iben; Derkx, Patrick;

    2009-01-01

    Pectin methylesterases (PMEs) catalyse the removal of methyl esters from the homogalacturonan (HG) backbone domain of pectin, a ubiquitous polysaccharide in plant cell walls. The degree of methyl esterification (DE) impacts upon the functional properties of HG within cell walls and plants produce...... numerous PMEs that act upon HG in muro. Many microbial plant pathogens also produce PMEs, the activity of which renders HG more susceptible to cleavage by pectin lyase and polygalacturonase enzymes and hence aids cell wall degradation. We have developed a novel microarray-based approach to investigate...... the activity of a series of variant enzymes based on the PME from the important pathogen Erwinia chrysanthemi. A library of 99 E. chrysanthemi PME mutants was created in which seven amino acids were altered by various different substitutions. Each mutant PME was incubated with a highly methyl esterified lime...

  15. Preservation methods for isolates of ascochyta blight fungi

    Directory of Open Access Journals (Sweden)

    Joanna Marcinkowska

    2014-08-01

    Full Text Available Isolates of ascochyta blight fungi, two of Ascochyta pisi, four of Mycosphaerella pinodes and four of Phoma pinodella were stored: A - on slants under mineral oil, B - on CN's medium agar disks, and as conidial suspension: C - in glycerine, D · in water. Viability and pathogenicity of recovered cultures after each consecutive year were assesed from 1991 to 1999. The compared parameters were first of all strongly influenced by the preservation method, but fungus species and number of years had a minor importance. The best for longer storage was method "A" because after 9 years the isolates were viable, highly pathogenic, and cultures recovered from them were clean. Thc method "C'' is good for short keeping (2-3 years, as conidia in vials need only small space and gave clean cultures.

  16. Role of temperature and free moisture in onion flower blight. [Botrytis squamosa; Botrytis cinerea; and Botrytis allii

    Energy Technology Data Exchange (ETDEWEB)

    Ramsey, G.R.; Lorbeer, J.W.

    1986-06-01

    The cardinal temperatures at which onion umbels were blighted (after inoculation when two-thirds of the florets were open) with Botrytis squamosa, B. cinerea, and B. allii (isolated from blighted onion florets) were near 9, 21, and 27 C for B. squamosa, near 12, 21, and 30 C for B. cinerea, and near 9, 24, and 30 C for B. allii. The cardinal temperatures for mycelial growth (potato-dextrose agar) of B. squamosa, B. cinerea, and B. allii were near 5, 22, and 30 C for each fungus. The cardinal temperatures for conidial germination (on purified water agar) were near 6, 15, and 30 C for B. squamosa; 3, 18, and 33 C for B. cinerea; and 6, 24, and 33 C for B. allii. When the duration of free moisture on umbels after inoculation with the three pathogens was increased from 0 to 96 hr. the percentages of unopened florets, open florets, and immature seed capsules blighted at 21 C were increased significantly. Free moisture durations of 12-24, 6-12, and 6-12 hr were necessary for blighting of unopen florets, open florets, and immature seed capsules, respectively, by each pathogen at 21 C. A positive correlation between the amount of July rainfall and the natural incidence of onion flower blight was observed in Orange County, New York, from 1976 to 1981. 10 references, 2 figures, 1 table.

  17. Presence of the potato late blight resistance gene RB does not promote adaptive parasitism of phytophthora infestans

    Science.gov (United States)

    The gene RB is derived from the wild potato species S. bulbocastanum and confers partial resistance to late blight, caused by the oomycete pathogen Phytophthora infestans. In order to investigate whether a single strain of P. infestans can adapt to overcome this partial resistance source, we subject...

  18. Discovery and characterization of the major late blight resistance complex in potato: genomic structure, functional diversity, and implications

    NARCIS (Netherlands)

    Huang, S.

    2005-01-01

    Potato is the most important non-cereal crop in the world. Late blight, caused by the oomycete pathogen Phytophthora infestans, is the most devastating disease of potato. In the mid-191h century, P. infestans attacked the European potato fields and this resulted in a widespread famine in Ireland. La

  19. Bacillus velezensis RC 218 as a biocontrol agent to reduce Fusarium head blight and deoxynivalenol accumulation in wheat

    Science.gov (United States)

    Bacillus velezensis RC 218 was originally isolated for the anthers of wheat as a potential antagonist of Fusarium graminearium, the causal agent of Fusarium head blight. It was demonstrated to have antagonist activity against the plant pathogen with in vitro and greenhouse assays. The current study ...

  20. Rainfastness of Prothioconazole+Tebuconazole for Fusarium head blight and Deoxynivalenol management in soft red winter wheat

    Science.gov (United States)

    Fungicides are most warranted for control of Fusarium head blight (FHB), a disease of wheat caused by the fungal pathogen Fusarium graminearum, when wet, rainy conditions occurs during anthesis. However, it is unclear whether rainfall directly following application affects fungicide efficacy against...

  1. Competitive Interaction Between Phytophthora Infestans Effectors Leads to Increased Aggressiveness on Plants Containing Broad-spectrum Late Blight Resistance

    Science.gov (United States)

    The resistance (R) gene RB confers broad-spectrum resistance to potato late blight and belongs. The RB protein recognizes the presence of members of the Phytophthora infestans effector family IPI-O to elicit resistance. Most isolates of the pathogen contain IPI-O variants that are recognized by R...

  2. New Markers for Potato Late Blight Resistance and Susceptibility Using FTIR Spectroscopy

    OpenAIRE

    Abdelmoumen TAOUTAOU; Socaciu, Carmen; Doru PAMFIL; Florinela FETEA; Erika BALAZS; Constantin BOTEZ

    2012-01-01

    The potato (Solanum tuberosum) is the 3rd most important crop worldwide, and Phytophthora infestans is the most devastating pathogen to potato crops. In this study, it has identified markers for resistance and susceptibility to late blight using potato genotypes that differ in their resistance/susceptibility to Phytophthora infestans. Using Fourier transform infrared spectroscopy, many absorbance bands have been identified as specific to resistant potato plants, and others were specific to su...

  3. TWIG BLIGHT AND DEFOLIATION CAUSED BY Colletotrichum horii IN PERSIMMONS IN BRAZIL

    Directory of Open Access Journals (Sweden)

    LOUISE LARISSA MAY DE MIO

    2015-03-01

    Full Text Available Persimmon anthracnose has been a great concern to Brazilian producers. This study aimed to identify and characterized the causal species from Brazilian persimmons byassessing morphological and molecular characteristics and pathogenicity tests. Five fungal isolatesobtained from diseased twigs and fruits were identified as Colletotrichum horii, based on morphologicalcharacteristics and nucleotide sequences of ITS region. Inoculation tests revealed that the fungal isolates caused necrotic spots followed by defoliation of leaves, blight of twigs and buds of potted persimmon plants.

  4. Gene expression analysis during cassava defense response to bacterial blight disease

    OpenAIRE

    2006-01-01

    Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) is a destructive disease in the South América and África and yield losses range between 12 and 100%. Cytochemistry and biochemistry of defense response to CBB have been well studied. However, the response of the plant to pathogen attack at the molecular and cellular level remains uncharacterized. Identification of genes associated with defense responses is one of most critical steps leading to the elucidation ...

  5. Functional Characterization of Twin-arginine Translocation Gene (tatC) from Erwinia amylovora%梨火疫病菌(Erwinia amylovora)双精氨酸运输系统基因(tatC)的功能分析

    Institute of Scientific and Technical Information of China (English)

    于洋洋; 刘倩倩; 徐恩丽; 胡白石

    2011-01-01

    Erwinia amylovom causes fire blight on many plants of the Rosaceae family such as apple and pear. The Twin-arginine translocation (Tat) pathway plays a crucial role in transporting the proteins which are related to virulence. In this study, a tatC disruption mutant EaAtatC was successfully constructed by homologous recombination as well as the complement strain EaAtatC (pME-tatC). The results showed that the tatC mutant EaAtafC displayed the reduced virulence, extracellular polysaccharide production, chemotaxis, motility, flagella assembly and growth in vitro. However, compared to wild type strain NCPPB1665 (Eal665), the induction of hypersensitive response in nonhost tobacco, biofilm synthesis and cellulose production of the tatC mutant EaAtalC didn't show significant difference. These findings demonstrate that tatC gene in Erwinia amylovora is involved in growth, and motility and play an important role in virulence.%梨火疫病菌(Erwinia amylovora)可引起梨、苹果等蔷薇科植物的火疫病.双精氨酸运输系统(Tat)与致病相关蛋白的转运有特定的联系.本研究在梨火疫病菌全基因组中发现了同源基因,通过同源重组的方法,构建了梨火疫病菌的tatC基因突变体以及互补子.研究结果表明,tatC基因影响着梨火疫病菌的致病性、胞外多糖、鞭毛运动、游动性、趋化性、生长情况等多种生物学特性.然而,Ea△tatC仍能引起烟草过敏性反应,并且在胞外纤维素和生物膜的生成方面与野生型菌株相比没有明显差异.说明梨火疫病菌tatC基因对病菌的生长、游动性以及致病性方面具有关键作用.

  6. Potato agriculture, late blight science, and the molecularization of plant pathology.

    Science.gov (United States)

    Turner, R Steven

    2008-01-01

    By the mid-1980s nucleic-acid based methods were penetrating the farthest reaches of biological science, triggering rivalries among practitioners, altering relationships among subfields, and transforming the research front. This article delivers a "bottom up" analysis of that transformation at work in one important area of biological science, plant pathology, by tracing the "molecularization" of efforts to understand and control one notorious plant disease -- the late blight of potatoes. It mobilizes the research literature of late blight science as a tool through which to trace the changing typography of the research front from 1983 to 2003. During these years molecularization intensified the traditional fragmentation of the late blight research community, even as it dramatically integrated study of the causal organism into broader areas of biology. In these decades the pathogen responsible for late blight, the oomycete "Phytophthora infestans," was discovered to be undergoing massive, frightening, and still largely unexplained genetic diversification -- a circumstance that lends the episode examined here an urgency that reinforces its historiographical significance as a case-study in the molecularization of the biological sciences.

  7. Validation of a tuber blight (Phytophthora infestans) prediction model

    Science.gov (United States)

    Potato tuber blight caused by Phytophthora infestans accounts for significant losses in storage. There is limited published quantitative data on predicting tuber blight. We validated a tuber blight prediction model developed in New York with cultivars Allegany, NY 101, and Katahdin using independent...

  8. Molecular signature of differential virulence in natural isolates of Erwinia amylovora.

    Science.gov (United States)

    Wang, Dongping; Korban, Schuyler S; Zhao, Youfu

    2010-02-01

    ABSTRACT Erwinia amylovora, the causal agent of fire blight, is considered to be a genetically homogeneous species based on physiological, biochemical, phylogenetic, and genetic analysis. However, E. amylovora strains exhibiting differential virulence are isolated from nature. The exopolysaccharide amylovoran and type III secretion system (T3SS) are two major yet separate virulence factors in E. amylovora. The objective of this study was to investigate whether there is a correlation between E. amylovora virulence and levels of virulence gene expression. Four wild-type strains (Ea1189, Ea273, Ea110, and CFBP1430), widely used in studies of E. amylovora pathogenesis, have been analyzed and compared. E. amylovora strains Ea273 and Ea110 elicited higher severity of disease symptoms than those of Ea1189 and CFBP1430 on apple cv. Golden Delicious and G16 apple root stock plants but not on susceptible Gala plants. In addition, Ea273 and Ea110 elicited severe hypersensitive responses within shorter periods of time at lower inoculum concentrations than those of Ea1189 and CFBP1430 on tobacco plants. Further molecular analyses have revealed that amylovoran production and expression of both amylovoran (amsG) and T3SS (dspE and hrpL) genes were significantly higher in Ea273 and Ea110 than those in Ea1189 and CFBP1430. Other phenotypes such as swarming motility in these four strains also differed significantly. These results indicate that E. amylovora strains of different origin can be divided into subgroups based on molecular signatures of virulence gene expression. Therefore, these molecular signatures may be used to differentiate E. amylovora strains, which may have taxonomical and evolutionary implications.

  9. Differential expression of biphenyl synthase gene family members in fire-blight-infected apple 'Holsteiner Cox'.

    Science.gov (United States)

    Chizzali, Cornelia; Gaid, Mariam M; Belkheir, Asma K; Hänsch, Robert; Richter, Klaus; Flachowsky, Henryk; Peil, Andreas; Hanke, Magda-Viola; Liu, Benye; Beerhues, Ludger

    2012-02-01

    Fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple (Malus × domestica). The phytoalexins of apple are biphenyls and dibenzofurans, whose carbon skeleton is formed by biphenyl synthase (BIS), a type III polyketide synthase. In the recently published genome sequence of apple 'Golden Delicious', nine BIS genes and four BIS gene fragments were detected. The nine genes fall into four subfamilies, referred to as MdBIS1 to MdBIS4. In a phylogenetic tree, the BIS amino acid sequences from apple and Sorbus aucuparia formed an individual cluster within the clade of the functionally diverse type III polyketide synthases. cDNAs encoding MdBIS1 to MdBIS4 were cloned from fire-blight-infected shoots of apple 'Holsteiner Cox,' heterologously expressed in Escherichia coli, and functionally analyzed. Benzoyl-coenzyme A and salicoyl-coenzyme A were the preferred starter substrates. In response to inoculation with E. amylovora, the BIS3 gene was expressed in stems of cv Holsteiner Cox, with highest transcript levels in the transition zone between necrotic and healthy tissues. The transition zone was the accumulation site of biphenyl and dibenzofuran phytoalexins. Leaves contained transcripts for BIS2 but failed to form immunodetectable amounts of BIS protein. In cell cultures of apple 'Cox Orange,' expression of the BIS1 to BIS3 genes was observed after the addition of an autoclaved E. amylovora suspension. Using immunofluorescence localization under a confocal laser-scanning microscope, the BIS3 protein in the transition zone of stems was detected in the parenchyma of the bark. Dot-shaped immunofluorescence was confined to the junctions between neighboring cortical parenchyma cells.

  10. Development of forecasting elements for minimization of fungicide treatment in potato protection against early blight in Moscow region

    Directory of Open Access Journals (Sweden)

    Penjkin Roman V.

    2013-01-01

    Full Text Available Early blight of potato (the agent is imperfect fungus Alternaria alternata (Fr. Keissl. is a serious disease of potatoes under hot conditions. This disease is important in the regions of Eastern and Southern Europe, Asia and Africa. It is controlled with intensive application of fungicides commonly used against late blight. However, currently fungicides cause undesirable damage to humans and the environment. Elements of forecasting the early blight have been developed in order to minimize the dosage of fungicides. Primary symptoms (chloroses and necroses and the potential of pathogen natural inoculum (determination of disease severity, indexes of formation of conidia and aggressiveness; as well as the current weather conditions were registered and determined in the potato signal plots (no treatments or artificial inoculation near main potato cropping. Seed tubers of main potato cropping were preliminary treated with plant growth regulator Circon and micro-fertilizer Siliplant produced by the Russian Company NEST-M. These preparations proved to be effective in acceleration process of potato growth and in delaying the early blight onset by 5-10 days. The same potato cultivar must be planted both in signaling plots and in the fields. Well-timed determination of primary symptoms and potential of pathogen in­oculum allowed us to understand the damage that early blight can cause to potato natural inoculation, and hence to provide well-timed application of fungicides with optimum dosages in mixture with Circon or Silipant. This forecasting method can be helpful for the adequate management of early blight and decrease of the environmental damages.

  11. Hyacintentelers stemmen in met aanpak Erwinia en fonds onderzoek

    NARCIS (Netherlands)

    Dwarswaard, A.; Vreeburg, P.J.M.

    2013-01-01

    Twee stevige onderwerpen telde de agenda van de jaarvergadering van de KAVB-productgroep Hyacint. Het voorstel om werkbollen te gaan toetsen op Erwinia kreeg bijval, en ook het plan om een fonds te vormen waaruit hyacintenonderzoek wordt betaald werd met instemming begroet.

  12. Fysische, chemische en biologische bestrijding van pectinolytische Erwinia's

    NARCIS (Netherlands)

    Wolf, van der J.M.; Doorn, van J.

    2006-01-01

    Rotveroorzakende bacteriën, met name pectinolytische Erwinia spp., zijn verantwoordelijk voor veel schade in de diverse gewassen, vooral in de teelt van aardappelen en de bloembolgewassen hyacint, zantedeschia en iris. In deze literatuurstudie worden de beschikbare gegevens nog eens nader bekeken va

  13. The hexA gene of Erwinia carotovora encodes a LysR homologue and regulates motility and the expression of multiple virulence determinants.

    Science.gov (United States)

    Harris, S J; Shih, Y L; Bentley, S D; Salmond, G P

    1998-05-01

    We have identified a gene important for the regulation of exoenzyme virulence factor synthesis in the plant pathogen Erwinia carotovora ssp. carotovora (Ecc) and virulence and motility in Erwinia carotovora ssp. atroseptica (Eca). This gene, hexA (hyperproduction of exoenzymes), is a close relative of the Erwinia chrysanthemi (Echr) gene pecT and encodes a member of the LysR family of transcriptional regulators. hexA mutants in both Ecc and Eca produce abnormally high levels of the exoenzyme virulence factors pectate lyase, cellulase and protease. In addition, Eca hexA mutants show increased expression of the fliA and fliC genes and hypermotility. Consistent with a role as a global regulator, expression of hexA from even a low-copy plasmid can suppress exoenzyme production in Ecc and Eca and motility in Eca. Production of the quorum-sensing pheromone OHHL in Ecc hexA is higher throughout the growth curve compared with the wild-type strain. Overexpression of Ecc hexA also caused widespread effects in several strains of the opportunistic human pathogen, Serratia. Low-copy hexA expression resulted in repression of exoenzyme, pigment and antibiotic production and repression of the spreading phenotype. Finally, mutations in hexA were shown to increase Ecc or Eca virulence in planta.

  14. Eop1 from a Rubus strain of Erwinia amylovora functions as a host-range limiting factor.

    Science.gov (United States)

    Asselin, J E; Bonasera, J M; Kim, J F; Oh, C-S; Beer, S V

    2011-08-01

    Strains of Erwinia amylovora, the bacterium causing the disease fire blight of rosaceous plants, are separated into two groups based on host range: Spiraeoideae and Rubus strains. Spiraeoideae strains have wide host ranges, infecting plants in many rosaceous genera, including apple and pear. In the field, Rubus strains infect the genus Rubus exclusively, which includes raspberry and blackberry. Based on comparisons of limited sequence data from a Rubus and a Spiraeoideae strain, the gene eop1 was identified as unusually divergent, and it was selected as a possible host specificity factor. To test this, eop1 genes from a Rubus strain and a Spiraeoideae strain were cloned and mutated. Expression of the Rubus-strain eop1 reduced the virulence of E. amylovora in immature pear fruit and in apple shoots. Sequencing the orfA-eop1 regions of several strains of E. amylovora confirmed that forms of eop1 are conserved among strains with similar host ranges. This work provides evidence that eop1 from a Rubus-specific strain can function as a determinant of host specificity in E. amylovora.

  15. New Markers for Potato Late Blight Resistance and Susceptibility Using FTIR Spectroscopy

    Directory of Open Access Journals (Sweden)

    Abdelmoumen TAOUTAOU

    2012-05-01

    Full Text Available The potato (Solanum tuberosum is the 3rd most important crop worldwide, and Phytophthora infestans is the most devastating pathogen to potato crops. In this study, it has identified markers for resistance and susceptibility to late blight using potato genotypes that differ in their resistance/susceptibility to Phytophthora infestans. Using Fourier transform infrared spectroscopy, many absorbance bands have been identified as specific to resistant potato plants, and others were specific to susceptible potato plants. For each case (resistance/susceptibility, three bands were identified: 941-1180 cm-1, 1336-1483 cm-1, and 1483-1703 cm-1 and 1056-1294 cm-1, 1442-1585 cm-1, and 1585-1832 cm-1, respectively. As it is a simple, rapid, and inexpensive technology, FTIR (Fourier Transform Infrared spectroscopy offers an excellent opportunity for studying potato resistance/susceptibility to late blight.

  16. Tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

    Tumwine, J.; Frinking, H.D.; Jeger, M.J.

    2002-01-01

    A survey on the tomato late blight situation and current practices for disease management was carried out in Uganda using an informal structured questionnaire approach. Ten districts from different agroclimatic zones were selected for the survey. Phytophthora infestans isolates from tomatoes were ob

  17. The antimicrobial activity of chitosan on the pathogen (Erwinia chrysanthemi pv.Zeae) of bacterial stalk rot of corn determined by colorimetry%比色法测定壳聚糖对玉米细菌性茎腐病菌的抑制作用

    Institute of Scientific and Technical Information of China (English)

    彭晓江; 刘晓津; 邱道寿; 曾粮斌

    2004-01-01

    通过选择合适的波长建立了玉米细菌性茎腐病菌(Erwinia chrysanthemi pv.zeae)悬浮液浓度与吸光值间的标准曲线,在LB液体培养基中分别设置6种壳聚糖浓度(0、0.5、1.0、2.0、3.5、5.5 mg/mL),用比色分析法测定了各浓度下玉米茎腐病菌的生长状况,并建立生长曲线.通过生长曲线分析表明壳聚糖对玉米茎腐病菌具有显著的抑制作用,且作用强度随壳聚糖浓度的提高而增强.

  18. Genetic analysis of streptomycin-resistant (Sm(R)) strains of Erwinia amylovora suggests that dissemination of two genotypes is responsible for the current distribution of Sm(R) E. amylovora in Michigan.

    Science.gov (United States)

    McGhee, Gayle C; Guasco, Jesse; Bellomo, Lisa M; Blumer-Schuette, Sara E; Shane, William W; Irish-Brown, Amy; Sundin, George W

    2011-02-01

    Streptomycin-resistant (Sm(R)) strains of the fire blight pathogen Erwinia amylovora were first isolated in southwest Michigan in 1991. Since that time, resistant strains have progressed northward to other apple-producing regions in the state. A total of 98.7% of Sm(R) strains isolated between 2003 and 2009 in Michigan harbored the strA-strB genes on transposon Tn5393. strA and strB encode phosphotransferase enzymes that modify streptomycin to a nonbactericidal form. Mutational resistance to streptomycin, caused by a point mutation-mediated target-site alteration of the ribosomal S12 protein, occurred in 1.3% of E. amylovora strains from Michigan. Tn5393 was originally introduced to E. amylovora on the plasmid pEa34; thus, the first Sm(R) strains isolated contained both pEa34 and the ubiquitous nonconjugative plasmid pEA29. More recently, we have observed Sm(R) strains in which Tn5393 is present on pEA29, suggesting that the transposon has moved via transposition from pEa34 to pEA29. Almost all of the strains containing Tn5393 on pEA29 had lost pEa34. Of 210 pEA29::Tn5393 plasmids examined, the transposon was inserted at either nucleotide position 1,515 or 17,527. Both of these positions were in noncoding regions of pEA29. Comparative sequencing of the housekeeping genes groEL and potentially variable sequences on pEA29 was done in an attempt to genetically distinguish Sm(R) strains from streptomycin-sensitive (Sm(S)) strains isolated in Michigan. Only 1 nucleotide difference within the total 2,660 bp sequenced from each strain was observed in 2 of 29 strains; multiple sequence differences were observed between the Michigan strains and E. amylovora control strains isolated in the western United States or from Rubus spp. Alterations in virulence observable using an immature pear fruit assay were detected in three of eight Sm(R) strains examined. Our current genetic data indicate that only two Sm(R) strain genotypes (strains containing pEA29::Tn5393 with Tn5393

  19. Gene Cloning and Characterization of luxR Transcriptional Regulator from Erwinia amylovora%梨火疫病菌luxR转录调节因子的克隆与功能分析

    Institute of Scientific and Technical Information of China (English)

    吴惠秋; 徐恩丽; 于洋洋; 田艳丽; 钱国良; 刘凤权; 胡白石

    2013-01-01

    Erwinia amylovora is a necrogenic phytopathogenic bacterium,the causal agent of fire blight in pear(Pyrus sorotina),apple(Malus domestica) and other members of the Rosaceae family,causing serious economic losses.LuxR transcriptional regulator is a key player in quorum sensing and plays important physiological and biochemical roles.In this paper,one of luxR homologous gene was amplified by PCR from E.amylovora.The mutant Ea△luxR was successfully constucted by homologous recombination,and the function studied preliminarily.The experimental results showed that,compared to the wild-type strain,the polyene macrolide biosynthesis,anti-oxidative stress,growth,and pathogenicity of mutant Ea△luxR declined.However,Ea△luxR still caused tobacco(Nicotiana tabacum) hypersensitive response,and there was no significant difference in antibiotic tolerance level and biofilm formation comparing to wild-type strain.These findings demonstrated that luxR gene in E.amylovora is involved in polyene macrolide biosynthesis,growth,and anti-oxidative stress and plays an important role in virulence.In addition,our results provid molecular evidence for in-depth understanding of the quorum sensing system of E.amylovora.%梨火疫病菌(Erwinia amylovora)是一种具有毁灭性的植物病原细菌,能够侵染梨、苹果和其他蔷薇科植物引起火疫病,造成严重的经济损失.luxR家族调控因子具有重要的生理生化作用,是细菌群体感应机制中研究较多的一类重要的转录调节基因.本研究采用PCR技术从梨火疫病菌中扩增出一个luxR同源基因,命名为EaluxR,应用同源重组的方法构建了突变株(Ea△luxR),并对其功能进行初步研究.实验结果表明,Ea△luxR与野生型菌株相比产生的多烯大环内酯类代谢产物在抗氧化压力和生长情况方面有明显差异,对梨幼苗及幼果的致病能力下降;但是Ea△luxR仍能引起烟草过敏性反应,并且在抗生素耐受水

  20. Host-induced gene silencing of an essential chitin synthase gene confers durable resistance to Fusarium head blight and seedling blight in wheat.

    Science.gov (United States)

    Cheng, Wei; Song, Xiu-Shi; Li, He-Ping; Cao, Le-Hui; Sun, Ke; Qiu, Xiao-Li; Xu, Yu-Bin; Yang, Peng; Huang, Tao; Zhang, Jing-Bo; Qu, Bo; Liao, Yu-Cai

    2015-12-01

    Fusarium head blight (FHB) and Fusarium seedling blight (FSB) of wheat, caused by Fusarium pathogens, are devastating diseases worldwide. We report the expression of RNA interference (RNAi) sequences derived from an essential Fusarium graminearum (Fg) virulence gene, chitin synthase (Chs) 3b, as a method to enhance resistance of wheat plants to fungal pathogens. Deletion of Chs3b was lethal to Fg; disruption of the other Chs gene family members generated knockout mutants with diverse impacts on Fg. Comparative expression analyses revealed that among the Chs gene family members, Chs3b had the highest expression levels during Fg colonization of wheat. Three hairpin RNAi constructs corresponding to the different regions of Chs3b were found to silence Chs3b in transgenic Fg strains. Co-expression of these three RNAi constructs in two independent elite wheat cultivar transgenic lines conferred high levels of stable, consistent resistance (combined type I and II resistance) to both FHB and FSB throughout the T3 to T5 generations. Confocal microscopy revealed profoundly restricted mycelia in Fg-infected transgenic wheat plants. Presence of the three specific short interfering RNAs in transgenic wheat plants was confirmed by Northern blotting, and these RNAs efficiently down-regulated Chs3b in the colonizing Fusarium pathogens on wheat seedlings and spikes. Our results demonstrate that host-induced gene silencing of an essential fungal chitin synthase gene is an effective strategy for enhancing resistance in crop plants under field test conditions.

  1. Transgenic apple plants overexpressing the Lc gene of maize show an altered growth habit and increased resistance to apple scab and fire blight.

    Science.gov (United States)

    Flachowsky, Henryk; Szankowski, Iris; Fischer, Thilo C; Richter, Klaus; Peil, Andreas; Höfer, Monika; Dörschel, Claudia; Schmoock, Sylvia; Gau, Achim E; Halbwirth, Heidrun; Hanke, Magda-Viola

    2010-02-01

    Transgenic apple plants (Malus x domestica cv. 'Holsteiner Cox') overexpressing the Leaf Colour (Lc) gene from maize (Zea mays) exhibit strongly increased production of anthocyanins and flavan-3-ols (catechins, proanthocyanidins). Greenhouse plants investigated in this study exhibit altered phenotypes with regard to growth habit and resistance traits. Lc-transgenic plants show reduced size, transversal gravitropism of lateral shoots, reduced trichome development, and frequently reduced shoot diameter and abnormal leaf development with fused leaves. Such phenotypes seem to be in accordance with a direct or an indirect effect on polar-auxin-transport in the transgenic plants. Furthermore, leaves often develop necrotic lesions resembling hypersensitive response lesions. In tests, higher resistance against fire blight (caused by the bacterium Erwinia amylovora) and against scab (caused by the fungus Venturia inaequalis) is observed. These phenotypes are discussed with respect to the underlying altered physiology of the Lc-transgenic plants. The results are expected to be considered in apple breeding strategies.

  2. Sgt1, but not Rar1, is essential for the RB-mediated broad-spectrum resistance to potato late blight

    Directory of Open Access Journals (Sweden)

    Wielgus Susan M

    2008-01-01

    Full Text Available Abstract Background Late blight is the most serious potato disease world-wide. The most effective and environmentally sound way for controlling late blight is to incorporate natural resistance into potato cultivars. Several late blight resistance genes have been cloned recently. However, there is almost no information available about the resistance pathways mediated by any of those genes. Results We previously cloned a late blight resistance gene, RB, from a diploid wild potato species Solanum bulbocastanum. Transgenic potato lines containing a single RB gene showed a rate-limiting resistance against all known races of Phytophthora infestans, the late blight pathogen. To better understand the RB-mediated resistance we silenced the potato Rar1 and Sgt1 genes that have been implicated in mediating disease resistance responses against various plant pathogens and pests. The Rar1 and Sgt1 genes of a RB-containing potato clone were silenced using a RNA interference (RNAi-based approach. All of the silenced potato plants displayed phenotypically normal growth. The late blight resistance of the Rar1 and Sgt1 silenced lines were evaluated by a traditional greenhouse inoculation method and quantified using a GFP-tagged P. infestans strain. The resistance of the Rar1-silenced plants was not affected. However, silencing of the Sgt1 gene abolished the RB-mediated resistance. Conclusion Our study shows that silencing of the Sgt1 gene in potato does not result in lethality. However, the Sgt1 gene is essential for the RB-mediated late blight resistance. In contrast, the Rar1 gene is not required for RB-mediated resistance. These results provide additional evidence for the universal role of the Sgt1 gene in various R gene-mediated plant defense responses.

  3. Delphinella Shoot Blight on Abies lasiocarpa Provenances in Norway

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    Venche Talgø

    2015-12-01

    Full Text Available Delphinella shoot blight (Delphinella abietis attacks true firs (Abies spp. in Europe and North America. Especially subalpine fir (A. lasiocarpa, one of the main Christmas tree species in Norway, is prone to the disease. The fungus kills current year needles, and in severe cases entire shoots. Dead needles become covered with black fruiting bodies, both pycnidia and pseudothecia. Delphinella shoot blight has mainly been a problem in humid, coastal regions in the northwestern part of Southern Norway, but, probably due to higher precipitation in inland regions during recent years, heavy attacks were found in 2011 in a field trial with 76 provenances of subalpine fir in Southeastern Norway. However, the amount of precipitation seemed less important once the disease had established in the field. Significant differences in susceptibility between provenances were observed. In general, the more bluish the foliage was, the healthier the trees appeared. The analysis of provenance means indicated that, at least for the southern range, the disease ratings were correlated with foliage color. This study also includes isolation, identification, a pathogenicity test, a seed test and electron microscopy of the wax layer on the needles. The fungus was identified based on the morphology of spores and by sequencing the Internal Transcribed Spacer (ITS regions of the ribosomal DNA. Koch’s postulates were fulfilled. The fungus was found present on newly harvested seeds and may therefore spread via international seed trade. When comparing the wax layers on green and blue needles, those of the latter were significantly thicker, a factor that may be involved in disease resistance.

  4. Molecular determinants of pathogen recognition and defense elicitation in potato

    Science.gov (United States)

    The potato late blight pathogen, Phytophthora infestans, is able to rapidly evolve to overcome resistance genes. The pathogen accomplishes this by secreting an arsenal of proteins, termed effectors, that function to modify host cells. Although hundreds of candidate effectors have been identified in ...

  5. Molecular Weight and Aggregation of Erwinia Gum in Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Erwinia(E) gum is composed of glucose, fucose, galactose and glucuronic acid. The weight-average molecular weights Mw, number-average molecular weights Mn and intrinsic viscosities[η] of the four fractions and the unfractionated E gum in aqueous solutions at desired temperatures were studied by light scattering, membrane osmometry, size exclusion chromatography(SEC) and viscometry. The experimental results prove that E gum formed aggregates in the aqueous solution at 25 ℃ and the aggregates were broken gradually with increasing temperature. The dissociation of the aggregates of E gum in the aqueous solution started at 36 ℃, and was completed at around 90 ℃. The [η] values of E gum and its fractions are much higher than those of the conventional polymers with the similar molecular weights, and decrease with increasing NaCl concentration.

  6. Characterization of the RcsC sensor kinase from Erwinia amylovora and other Enterobacteria.

    Science.gov (United States)

    Wang, Dongping; Korban, Schuyler S; Pusey, P Lawrence; Zhao, Youfu

    2011-06-01

    RcsC is a hybrid sensor kinase which contains a sensor domain, a histidine kinase domain, and a receiver domain. We have previously demonstrated that, although the Erwinia amylovora rcsC mutant produces more amylovoran than the wild-type (WT) strain in vitro, the mutant remains nonpathogenic on both immature pear fruit and apple plants. In this study, we have comparatively characterized the Erwinia RcsC and its homologs from various enterobacteria. Results demonstrate that expression of the Erwinia rcsC gene suppresses amylovoran production in various amylovoran overproducing WT and mutant strains, thus suggesting the presence of a net phosphatase activity of Erwinia RcsC. Findings have also demonstrated that rcsC homologs from other enterobacteria could not rescue amylovoran production of the Erwinia rcsC mutant in vitro. However, virulence of the Erwinia rcsC mutant is partially restored by rcsC homologs from Pantoea stewartii, Yersinia pestis, and Salmonella enterica but not from Escherichia coli on apple shoots. Domain-swapping experiments have indicated that replacement of the E. coli RcsC sensor domain by those of Erwinia and Yersinia spp. partially restores virulence of the Erwinia rcsC mutant, whereas chimeric constructs containing the sensor domain of E. coli RcsC could not rescue virulence of the Erwinia rcsC mutant on apple. Interestingly, only chimeric constructs containing the histidine kinase and receiver domains of Erwinia RcsC are fully capable of rescuing amylovoran production. These results suggest that the sensor domain of RcsC may be important in regulating bacterial virulence, whereas the activity of the histidine kinase and receiver domains of Erwinia RcsC may be essential for amylovoran production in vitro.

  7. Efficacy of potato seeds disinfection products to control Erwinia spp.

    Science.gov (United States)

    Dupuis, B; Garcia, N; Boels, G

    2008-01-01

    Erwinia spp. provokes soft rot on potato tubers during storage. No disinfection products are available on the market in the European Union to control these bacteria. We tested 3 products presented as good candidates to cure potato tubers from bacterial diseases. First, Anthium 500 (Du Pont de Nemours) a product based on chlorine dioxyde, then Phostrol (Nufarm) with phosphoric acid as a.i. and finally Solucuivre (Proval), a copper based product. We firstly managed disinfection trials: high Erwinia contaminated potato seed samples were treated by immersion and were then incubated, we observed the percentage of tubers rotting. Secondly, we managed protection trials: protected healthy tubers were incubated during 23 days in contact with rotting tubers. We evaluated weight loss after symptoms development. No tested product was effective to control Erwinia spp. on seed tubers in our trials conditions. Furthermore, we observed more rot development after Phostrol and Solucuivre application. We suppose that the product couldn't reach the latent bacteria and weakened the tubers. No protection effect was observed.

  8. An Update on Genetic Resistance of Chickpea to Ascochyta Blight

    Directory of Open Access Journals (Sweden)

    Mamta Sharma

    2016-03-01

    Full Text Available Ascochyta blight (AB caused by Ascochyta rabiei (Pass. Labr. is an important and widespread disease of chickpea (Cicer arietinum L. worldwide. The disease is particularly severe under cool and humid weather conditions. Breeding for host resistance is an efficient means to combat this disease. In this paper, attempts have been made to summarize the progress made in identifying resistance sources, genetics and breeding for resistance, and genetic variation among the pathogen population. The search for resistance to AB in chickpea germplasm, breeding lines and land races using various screening methods has been updated. Importance of the genotype × environment (GE interaction in elucidating the aggressiveness among isolates from different locations and the identification of pathotypes and stable sources of resistance have also been discussed. Current and modern breeding programs for AB resistance based on crossing resistant/multiple resistant and high-yielding cultivars, stability of the breeding lines through multi-location testing and molecular marker-assisted selection method have been discussed. Gene pyramiding and the use of resistant genes present in wild relatives can be useful methods in the future. Identification of additional sources of resistance genes, good characterization of the host–pathogen system, and identification of molecular markers linked to resistance genes are suggested as the key areas for future study.

  9. Genetics and Improvement of Bacterial Blight Resistance of Hybrid Rice in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qi

    2009-01-01

    Since 1980s, rice breeding for resistance to bacterial blight has been rapidly progressing in China. The gene Xa4 was mainly used in three-line indica hybrid and two-line hybrid rice. The disease has been 'quiet' for 20 years in China, yet in recent years it has gradually emerged and been prevalent in fields planted with newly released rice varieties in the Changjiang River valley. Under the circumstances, scientists inevitably raised several questions: what causes the resurgence and what should we do next? And/or is resistance breeding still one of the main objectives in rice improvement? Which approach do we take on resistance breeding so that the resistance will be more durable, and the resistance gene will be used more efficiently? A combined strategy involving traditional method, molecular marker-assisted selection, and transgenic technology should bring a new era to the bacterial blight resistance hybrid rice breeding program. This review also briefly discusses and deliberates on issues related to the broadening of bacterial blight resistance, and suitable utilization of resistance genes, alternate planting of available resistance genes; and understands the virulent populations of the bacterial pathogen in China even in Asia.

  10. Draft Genome Sequence of the Bactrocera oleae Symbiont “Candidatus Erwinia dacicola”

    Science.gov (United States)

    Blow, Frances; Gioti, Anastasia; Starns, David; Ben-Yosef, Michael; Pasternak, Zohar; Jurkevitch, Edouard; Vontas, John

    2016-01-01

    “Candidatus Erwinia dacicola” is a Gammaproteobacterium that forms a symbiotic association with the agricultural pest Bactrocera oleae. Here, we present a 2.1-Mb draft hybrid genome assembly for “Ca. Erwinia dacicola” generated from single-cell and metagenomic data. PMID:27634990

  11. Goed om uitgangsmateriaal op Erwinia te testen (interview met Jan van der Wolf)

    NARCIS (Netherlands)

    Dwarswaard, A.; Bovenkamp, van den G.; Wolf, van der J.M.

    2012-01-01

    Bloembollen en aardappelen. Ze hebben in ieder geval één ziekte gemeen: bacterierot, veroorzaakt door Erwinia. In beide teelten zorgen deze bacterieziekten voor veel schade. In het Deltaplan Erwinia werken de bloembollen- en aardappelwereld samen op onderzoeksgebied. In twee artikelen staat de vraag

  12. Modified inoculation and disease assessment methods reveal host specificity in Erwinia tracheiphila-Cucurbitaceae interactions.

    Science.gov (United States)

    Nazareno, Eric S; Dumenyo, C Korsi

    2015-12-01

    We conducted a greenhouse trial to determine specific compatible interactions between Erwinia tracheiphila strains and cucurbit host species. Using a modified inoculation system, E. tracheiphila strains HCa1-5N, UnisCu1-1N, and MISpSq-N were inoculated to cucumber (Cucumis sativus) cv. 'Sweet Burpless', melon (Cucumis melo) cv. 'Athena Hybrid', and squash (Cucubita pepo) cv. 'Early Summer Crookneck'. We observed symptoms and disease progression for 30 days; recorded the number of days to wilting of the inoculated leaf (DWIL), days to wilting of the whole plant (DWWP), and days to death of the plant (DDP). We found significant interactions between host cultivar and pathogen strains, which imply host specificity. Pathogen strains HCa1-5N and UnisCu1-1N isolated from Cucumis species exhibited more virulence in cucumber and melon than in squash, while the reverse was true for strain MISpSq-N, an isolate from Cucurbita spp. Our observations confirm a previous finding that E. tracheiphila strains isolated from Cucumis species were more virulent on Cucumis hosts and those from Cucubita were more virulent on Cucubita hosts. This confirmation helps in better understanding the pathosystem and provides baseline information for the subsequent development of new disease management strategies for bacterial wilt. We also demonstrated the efficiency of our modified inoculation and disease scoring methods.

  13. Insecticidal Bacillus thuringiensis silences Erwinia carotovora virulence by a new form of microbial antagonism, signal interference.

    Science.gov (United States)

    Dong, Yi-Hu; Zhang, Xi-Fen; Xu, Jin-Ling; Zhang, Lian-Hui

    2004-02-01

    It is commonly known that bacteria may produce antibiotics to interfere with the normal biological functions of their competitors in order to gain competitive advantages. Here we report that Bacillus thuringiensis suppressed the quorum-sensing-dependent virulence of plant pathogen Erwinia carotovora through a new form of microbial antagonism, signal interference. E. carotovora produces and responds to acyl-homoserine lactone (AHL) quorum-sensing signals to regulate antibiotic production and expression of virulence genes, whereas B. thuringiensis strains possess AHL-lactonase, which is a potent AHL-degrading enzyme. B. thuringiensis did not seem to interfere with the normal growth of E. carotovora; rather, it abolished the accumulation of AHL signal when they were cocultured. In planta, B. thuringiensis significantly decreased the incidence of E. carotovora infection and symptom development of potato soft rot caused by the pathogen. The biocontrol efficiency is correlated with the ability of bacterial strains to produce AHL-lactonase. While all the seven AHL-lactonase-producing B. thuringiensis strains provided significant protection against E. carotovora infection, Bacillus fusiformis and Escherichia coli strains that do not process AHL-degradation enzyme showed little effect in biocontrol. Mutation of aiiA, the gene encoding AHL-lactonase in B. thuringiensis, resulted in a substantial decrease in biocontrol efficacy. These results suggest that signal interference mechanisms existing in natural ecosystems could be explored as a new version of antagonism for prevention of bacterial infections.

  14. 辣椒疫病的发生及防治技术%Occurrence and control of pepper phytophthora blight

    Institute of Scientific and Technical Information of China (English)

    管理和

    2012-01-01

      介绍辣椒疫病病原、不同时期及不同部位发病症状和发病规律、发病条件,总结出以预防为主、综合防治的技术措施。%  The pathogens, symptoms and rules in different period of pepper phytophthora blight disease were introduced, then the comprehensive prevention measures were concluded in this paper.

  15. Genome sequence of the necrotrophic plant pathogen Pythium ultimum reveals original pathogenicity mechanisms and effector repertoire.

    Science.gov (United States)

    The P. ultimum DAOM BR144 (=CBS 805.95 = ATCC200006) genome (42.8 Mb) encodes 15,290 genes, and has extensive sequence similarity and synteny with related Phytophthora spp., including the potato late blight pathogen Phytophthora infestans. Whole transcriptome sequencing revealed expression of 86 % o...

  16. Strategies for managing Fusarium head blight and deoxynivalenol accumulation in wheat.

    Science.gov (United States)

    Yuen, Gary Y; Schoneweis, Susan D

    2007-10-20

    Many mycotoxigenic fungi infect plant hosts and cause disease in the field. Therefore, control of field infection by these fungi is a critical step in managing mycotoxin accumulation in the harvested product. Fusarium graminearum, also known as Gibberella zeae, is the causal agent of Fusarium head blight (FHB), or scab, in cereals and is also the primary agent responsible for contamination of grain with deoxynivalenol (DON). Research efforts worldwide are devoted to the development of strategies to control field infection of wheat and barley by this pathogen. Strategies include the use of fungicides and biological control agents to protect flowering heads from infection. There is extensive effort in breeding for host resistance to infection and spread of the pathogen within the heads. Scientists are also seeking exogenous traits to introduce into cereals to enhance resistance. Cultural practices are also being examined, primarily as measures to reduce pathogen survival and inoculum production in crop residues. The successes and limitations of these strategies in the management of Fusarium head blight and deoxynivalenol are discussed.

  17. Potato late blight epidemics and population structure of Phytophthora infestans.

    NARCIS (Netherlands)

    Zwankhuizen, M.J.

    1998-01-01

    Potato late blight is caused by the fungus Phytophthora infestans . To study the relative importance of oospores in the epidemiology, and to estimate the relative impact of various infection sources, late blight epidemics in Southern Flevoland (The Netherlands) were studied using epidemiological and

  18. Strategies to control late blight in potatoes in Europe

    NARCIS (Netherlands)

    Schepers, H.T.A.M.; Evenhuis, A.; Spits, H.G.

    2009-01-01

    In Europe an aggressive genetically diverse population of potato late blight is present which regularly causes problems in all potato growing regions. It is therefore of the utmost importance that blight is managed in an integrated way by combining a range of measures. Hygiene measures can keep the

  19. Role of Solanum dulcamara L. in Potato Late Blight Epidemiology

    NARCIS (Netherlands)

    Golas, T.M.; Weerden, van der G.M.; Berg, van den R.G.; Mariani, C.; Allefs, J.J.H.M.

    2010-01-01

    Four sites with naturally growing Solanum dulcamara were surveyed during 2006 and 2007 for the presence of late blight. Despite 2 years of observations, no late blight was detected among natural populations of bittersweet. Nevertheless, repeated infections occurred on few S. dulcamara plants from a

  20. Metabolic versatility and antibacterial metabolite biosynthesis are distinguishing genomic features of the fire blight antagonist Pantoea vagans C9-1.

    Directory of Open Access Journals (Sweden)

    Theo H M Smits

    Full Text Available BACKGROUND: Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. PRINCIPAL FINDINGS: Genome analysis indicated two major factors Contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. CONCLUSIONS: Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems.

  1. Identification of genes differentially expressed during interaction of resistant and susceptible apple cultivars (Malus × domestica with Erwinia amylovora

    Directory of Open Access Journals (Sweden)

    Aldwinckle Herb S

    2010-01-01

    Full Text Available Abstract Background The necrogenic enterobacterium, Erwinia amylovora is the causal agent of the fire blight (FB disease in many Rosaceaespecies, including apple and pear. During the infection process, the bacteria induce an oxidative stress response with kinetics similar to those induced in an incompatible bacteria-plant interaction. No resistance mechanism to E. amylovora in host plants has yet been characterized, recent work has identified some molecular events which occur in resistant and/or susceptible host interaction with E. amylovora: In order to understand the mechanisms that characterize responses to FB, differentially expressed genes were identified by cDNA-AFLP analysis in resistant and susceptible apple genotypes after inoculation with E. amylovora. Results cDNA were isolated from M.26 (susceptible and G.41 (resistant apple tissues collected 2 h and 48 h after challenge with a virulent E. amylovora strain or mock (buffer inoculated. To identify differentially expressed transcripts, electrophoretic banding patterns were obtained from cDNAs. In the AFLP experiments, M.26 and G.41 showed different patterns of expression, including genes specifically induced, not induced, or repressed by E. amylovora. In total, 190 ESTs differentially expressed between M.26 and G.41 were identified using 42 pairs of AFLP primers. cDNA-AFLP analysis of global EST expression in a resistant and a susceptible apple genotype identified different major classes of genes. EST sequencing data showed that genes linked to resistance, encoding proteins involved in recognition, signaling, defense and apoptosis, were modulated by E. amylovora in its host plant. The expression time course of some of these ESTs selected via a bioinformatic analysis has been characterized. Conclusion These data are being used to develop hypotheses of resistance or susceptibility mechanisms in Malus to E. amylovora and provide an initial categorization of genes possibly involved in

  2. Identification and Characterization of Botrytis Blossom Blight of Japanese Plums Caused by Botrytis cinerea and B. prunorum sp. nov. in Chile.

    Science.gov (United States)

    Ferrada, Enrique E; Latorre, Bernardo A; Zoffoli, Juan P; Castillo, Antonio

    2016-02-01

    Blossom blight is a destructive disease of plums (Prunus salicina) when humid and temperate weather conditions occur in Chile. Disease incidence ranging from 4 to 53% has been observed. Symptoms include light brown petal necrosis, starting as light brown mottles or V-shaped necrosis at the margins of the petals, progressing to the stamen and pistils. In this study, the etiology of blossom blight of plums was determined. High- and low-sporulating isolates of Botrytis were obtained consistently from blighted blossoms and apparently healthy flowers of plums. Based on colony morphology, conidial production and molecular phylogenetic analysis, these high- and low-sporulating isolates were identified as B. cinerea and B. prunorum sp. nov., respectively. Phylogenetic analysis of the genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) grouped B. prunorum isolates in a single cluster, distantly from B. cinerea and other Botrytis species. The phylogenetic analysis of necrosis and ethylene-inducing protein (NEP1 and NEP2) genes corroborated these results. Analysis of the internal transcribed spacer region and large-subunit (26S) ribosomal DNA and detection of Boty and Flipper transposable elements, were not useful to differentiate between these Botrytis species. Both species were pathogenic on plum flowers and the fruit of plums, apples, and kiwifruits. However, B. prunorum was less virulent than B. cinerea. These pathogens were re-isolated from inoculated and diseased tissues; thus, Koch's postulates were fulfilled, confirming its role in blossom blight of plums. B. cinerea was predominant, suggesting that B. prunorum may play a secondary role in the epidemiology of blossom blight in plums in Chile. This study clearly demonstrated that the etiology of blossom blight of plums is caused by B. cinerea and B. prunorum, which constitute a species complex living in sympatry on plums and possibly

  3. Cloning, expression, purification, crystallization and preliminary X-ray analysis of EaLsc, a levansucrase from Erwinia amylovora.

    Science.gov (United States)

    Caputi, Lorenzo; Cianci, Michele; Benini, Stefano

    2013-05-01

    The Gram-negative bacterium Erwinia amylovora is a destructive pathogen of Rosaceae. During infection, E. amylovora produces the exopolysaccharide levan, which contributes to the occlusion of plant vessels, causing the wilting of shoots. Levan is a fructose polymer that is synthesized by multifunctional enzymes called levansucrases. The levansucrase from E. amylovora (EaLsc) was heterologously expressed as a GST-fusion protein in Escherichia coli, purified and crystallized after tag removal. The protein crystallized in space group P21212. X-ray diffraction data were acquired to 2.77 Å resolution. The structure of the enzyme was solved by molecular replacement. The asymmetric unit contains eight enzyme molecules, giving a solvent content of 58.74% and a Matthews coefficient of 2.98 Å(3) Da(-1).

  4. Erwinia teleogrylli sp. nov., a Bacterial Isolate Associated with a Chinese Cricket.

    Directory of Open Access Journals (Sweden)

    Bo Liu

    Full Text Available A bacterial isolate (SCU-B244T was obtained in China from crickets (Teleogryllus occipitalis living in cropland deserted for approximately 10 years. The isolated bacteria were Gram-negative, facultatively anaerobic, oxidase-negative rods. A preliminary analysis of the 16S rRNA gene sequence indicated that the strain belongs to either the genus Erwinia or Pantoea. Analysis of multilocus sequence typing based on concatenated partial atpD, gyrB and infB gene sequences and physiological and biochemical characteristics indicated that the strain belonged to the genus Erwinia, as member of a new species as it was distinct from other known Erwinia species. Further analysis of the 16S rRNA gene showed SCU-B244T to have 94.71% identity to the closest species of that genus, Erwinia oleae (DSM 23398T, which is below the threshold of 97% used to discriminate bacterial species. DNA-DNA hybridization results (5.78±2.52% between SCU-B244T and Erwinia oleae (DSM 23398T confirmed that SCU-B244T and Erwinia oleae (DSM 23398T represent different species combined with average nucleotide identity values which range from 72.42% to 74.41. The DNA G+C content of SCU-B244T was 55.32 mol%, which also differs from that of Erwinia oleae (54.7 to 54.9 mol%. The polyphasic taxonomic approach used here confirmed that the strain belongs to the Erwinia group and represents a novel species. The name Erwinia teleogrylli sp. nov. is proposed for this novel taxon, for which the type strain is SCU-B244T (= CGMCC 1.12772T = DSM 28222T = KCTC 42022T.

  5. Erwinia teleogrylli sp. nov., a Bacterial Isolate Associated with a Chinese Cricket.

    Science.gov (United States)

    Liu, Bo; Luo, Jin; Li, Wei; Long, Xiu-Feng; Zhang, Yu-Qin; Zeng, Zhi-Gang; Tian, Yong-Qiang

    2016-01-01

    A bacterial isolate (SCU-B244T) was obtained in China from crickets (Teleogryllus occipitalis) living in cropland deserted for approximately 10 years. The isolated bacteria were Gram-negative, facultatively anaerobic, oxidase-negative rods. A preliminary analysis of the 16S rRNA gene sequence indicated that the strain belongs to either the genus Erwinia or Pantoea. Analysis of multilocus sequence typing based on concatenated partial atpD, gyrB and infB gene sequences and physiological and biochemical characteristics indicated that the strain belonged to the genus Erwinia, as member of a new species as it was distinct from other known Erwinia species. Further analysis of the 16S rRNA gene showed SCU-B244T to have 94.71% identity to the closest species of that genus, Erwinia oleae (DSM 23398T), which is below the threshold of 97% used to discriminate bacterial species. DNA-DNA hybridization results (5.78±2.52%) between SCU-B244T and Erwinia oleae (DSM 23398T) confirmed that SCU-B244T and Erwinia oleae (DSM 23398T) represent different species combined with average nucleotide identity values which range from 72.42% to 74.41. The DNA G+C content of SCU-B244T was 55.32 mol%, which also differs from that of Erwinia oleae (54.7 to 54.9 mol%). The polyphasic taxonomic approach used here confirmed that the strain belongs to the Erwinia group and represents a novel species. The name Erwinia teleogrylli sp. nov. is proposed for this novel taxon, for which the type strain is SCU-B244T (= CGMCC 1.12772T = DSM 28222T = KCTC 42022T).

  6. Phylogeography and population structure of the biologically invasive phytopathogen Erwinia amylovora inferred using minisatellites.

    Science.gov (United States)

    Bühlmann, Andreas; Dreo, Tanja; Rezzonico, Fabio; Pothier, Joël F; Smits, Theo H M; Ravnikar, Maja; Frey, Jürg E; Duffy, Brion

    2014-07-01

    Erwinia amylovora causes a major disease of pome fruit trees worldwide, and is regulated as a quarantine organism in many countries. While some diversity of isolates has been observed, molecular epidemiology of this bacterium is hindered by a lack of simple molecular typing techniques with sufficiently high resolution. We report a molecular typing system of E. amylovora based on variable number of tandem repeats (VNTR) analysis. Repeats in the E. amylovora genome were identified with comparative genomic tools, and VNTR markers were developed and validated. A Multiple-Locus VNTR Analysis (MLVA) was applied to E. amylovora isolates from bacterial collections representing global and regional distribution of the pathogen. Based on six repeats, MLVA allowed the distinction of 227 haplotypes among a collection of 833 isolates of worldwide origin. Three geographically separated groups were recognized among global isolates using Bayesian clustering methods. Analysis of regional outbreaks confirmed presence of diverse haplotypes but also high representation of certain haplotypes during outbreaks. MLVA analysis is a practical method for epidemiological studies of E. amylovora, identifying previously unresolved population structure within outbreaks. Knowledge of such structure can increase our understanding on how plant diseases emerge and spread over a given geographical region.

  7. Biomolecular characterization of the levansucrase of Erwinia amylovora, a promising biocatalyst for the synthesis of fructooligosaccharides.

    Science.gov (United States)

    Caputi, Lorenzo; Nepogodiev, Sergey A; Malnoy, Mickael; Rejzek, Martin; Field, Robert A; Benini, Stefano

    2013-12-18

    Erwinia amylovora is a plant pathogen that affects Rosaceae, such as apple and pear. In E. amylovora the fructans, produced by the action of a levansucrase (EaLsc), play a role in virulence and biofilm formation. Fructans are bioactive compounds, displaying health-promoting properties in their own right. Their use as food and feed supplements is increasing. In this study, we investigated the biomolecular properties of EaLsc using HPAEC-PAD, MALDI-TOF MS, and spectrophotometric assays. The enzyme, which was heterologously expressed in Escherichia coli in high yield, was shown to produce mainly fructooligosaccharides (FOSs) with a degree of polymerization between 3 and 6. The kinetic properties of EaLsc were similar to those of other phylogenetically related Gram-negative bacteria, but the good yield of FOSs, the product spectrum, and the straightforward production of the enzyme suggest that EaLsc is an interesting biocatalyst for future studies aimed at producing tailor-made fructans.

  8. Involvement of N-acylhomoserine lactones throughout plant infection by Erwinia carotovora subsp. atroseptica (Pectobacterium atrosepticum).

    Science.gov (United States)

    Smadja, Bruno; Latour, Xavier; Faure, Denis; Chevalier, Sylvie; Dessaux, Yves; Orange, Nicole

    2004-11-01

    Erwinia carotovora subsp. atroseptica is responsible for potato blackleg disease in the field and tuber soft rot during crop storage. The process leading to the disease occurs in two phases: a primary invasion step followed by a maceration step. Bacteria-to-bacteria communication is associated with a quorum-sensing (QS) process based on the production of N-acylhomoserine lactones (HSL). The role of HSL throughout plant infection was analyzed. To this purpose, HSL produced by a specific E. carotovora subsp. atroseptica wild-type strain, which was particularly virulent on potato, were identified. A derivative of this strain that expressed an HSL lactonase gene and produced low amounts of HSL was generated. The comparison of these strains allowed the evaluation of the role of HSL and QS in disease establishment and development. Bacterial growth and motility; activity of proteins secreted by type I, II, and III systems; and hypersensitive and maceration reactions were evaluated. Results indicated that HSL production and QS regulate only those traits involved in the second stage of the host plant infection (i.e., tissue maceration) and hypersensitive response in nonhost tobacco plants. Therefore, the use of QS quenching strategies for biological control in E. carotovora subsp. atroseptica cannot prevent initial infection and multiplication of this pathogen.

  9. 梨火疫病病原菌(Erwinia amylovora)三型分泌系统的鉴别及Erwinia spp. HrpA的分析%Identification of Type Ⅲ Secration System in Erwinia amylovora and Analyse of HrpA in Erwinia spp.

    Institute of Scientific and Technical Information of China (English)

    朱勃; 金谷雷; 怀雁; 谢关林

    2009-01-01

    [目的]明确梨火疫病病原菌(Erwinia amylovora)三型分泌系统(type Ⅲ secretion system,TTSS)的所在区域、相关基因及Erwiaia spp.的HrpA(hypersensitive response and pathogenicity gene A)选择压水平.[方法]利用生物信息学方法,通过BLAST程序对梨火疫病菌基因组的核苷酸数据库进行同源比对,同时对Erwiaia spp.与宿主互作的表面蛋白HrpA进行选择压分析.[结果] TTSS分析结果显示在40 kb大小的毒力岛上有27个TTSS相关基因.通过与看家基因及毒力岛上的致病性相关的重要基因HrpN的比较、选择压分析、多序列比较,发现HrpA基因处于较强的选择压作用下,且HrpA蛋白N端主要受正向选择,C端主要受净化选择.NJ法构建的HrpA系统发育树显示Erwinia spp.形成两个明显的分支,表明HrpA基因可能在种间分化后产生了不同的选择压变化.[结论]梨火疫病病原菌基因组3.14-3.18 Mb为其TTSS分布区域.该病原菌通过TTSS侵染寄主植物,在其病原菌表面有一种类鞭毛结构的TTSS蛋白HrpA,HrpA作为传输者起着将效应分子输送到宿主内部的功能,在进化上受到了较强的选择压影响.

  10. First Report of Web Blight of Rosemary (Rosmarinus officinalis) Caused by Rhizoctonia solani AG-1-IB in Korea.

    Science.gov (United States)

    Aktaruzzaman, Md; Kim, Joon-Young; Afroz, Tania; Kim, Byung-Sup

    2015-06-01

    Herein, we report the first occurrence of web blight of rosemary caused by Rhizoctonia solani AG-1-IB in Gangneung, Gangwon Province, Korea, in August 2014. The leaf tissues of infected rosemary plants were blighted and white mycelial growth was seen on the stems. The fungus was isolated from diseased leaf tissue and cultured on potato dextrose agar for identification. The young hyphae had acute angular branching near the distal septum of the multinucleate cells and mature hyphal branches formed at an approximately 90° angle. This is morphologically identical to R. solani AG-1-IB, as per previous reports. rDNA-ITS sequences of the fungus were homologous to those of R. solani AG-1-IB isolates in the GenBank database with a similarity percentage of 99%, thereby confirming the identity of the causative agent of the disease. Pathogenicity of the fungus in rosemary plants was also confirmed by Koch's postulates.

  11. Xanthomonas oryzae pv oryzae the Causal Agent of Bacterial Leaf Blight of rice: Isolation, Characterization, and Study of Transposon Mutagenesis

    Directory of Open Access Journals (Sweden)

    Abdjad Asih Nawangsih

    2011-04-01

    Full Text Available Xanthomonas oryzae pv oryzae the Causal Agent of Bacterial Leaf Blight of rice: Isolation, Characterization, and Study of Transposon Mutagenesis. X. oryzae pv. oryzae (Xoo causes bacterial leaf blight (BLB of rice (Oryza sativa L., a major disease that constrains production of the staple crop in many countries of the world. Identification of X. oryzae pv. oryzae (Xoo was conducted based on the disease symptoms, pathogenicity, morphological, physiological, and genetic characteristics of bacterial cultures isolated from the infected plants. Fifty bacterial isolates predicted as Xoo have been successfully isolated. They are aerobic, rod shaped, and Gram negative bacteria. The isolates were evaluated for their hypersensitivity in tobacco and pathogenicity in rice plant. Fifty isolates induced hypersensitive reaction in tobacco and showed pathogenicity symptom in rice in different length. Based on physiological test, hypersensitivity and pathogenicity reactions, three bacterial isolates strongly predicted as Xoo, i.e. STG21, STG42, and STG46, were non indole formation, non pigment fluorescent, hydrolyzed casein, catalase activity positive, but negative oxidase. Partial sequencing of 16S rRNA genes of STG21 and STG42 showed 80% and 82% homology with X. oryzae, respectively, while STG46 showed 84% homology with X. campestris. Mini-Tn5 transposon mutagenesis of STG21 generated one of the mutants (M5 lossed it’s ability to induce hypersensitive reaction in tobacco plant and deficient in pathogenicity on rice. The lesion length of rice leaf caused by the mutant M5 decreased up to 80%.

  12. Three potato clones incorporating combined resistances to early blight from S. palustre and late blight from S. bulbocastanum into a S. tuberosum background

    Science.gov (United States)

    Three individuals from a segregating population derived from a cross between +297 and K41 are being released as germplasm with resistance to both early blight, caused by Alternaria solani, and late blight, caused by Phytophthora infestans. The source of resistance to early blight from +297 is the wi...

  13. The Solanum demissumR8 late blight resistance gene is an Sw-5 homologue that has been deployed worldwide in late blight resistant varieties

    NARCIS (Netherlands)

    Vossen, Jack H.; Arkel, van Gert; Bergervoet-van Deelen, Marjan; Jo, Kwang Ryong; Jacobsen, Evert; Visser, Richard G.F.

    2016-01-01

    The potato late blight resistance geneR8has been cloned.R8is found in five late blight resistant varieties deployed in three different continents. R8 recognises Avr8 and is homologous to the NB-LRR protein Sw-5 from tomato.Abstract: The broad spectrum late blight resistance gene R8 from Solanum

  14. T3SS-dependent differential modulations of the jasmonic acid pathway in susceptible and resistant genotypes of Malus spp. challenged with Erwinia amylovora.

    Science.gov (United States)

    Dugé De Bernonville, Thomas; Gaucher, Matthieu; Flors, Victor; Gaillard, Sylvain; Paulin, Jean-Pierre; Dat, James F; Brisset, Marie-Noëlle

    2012-06-01

    Fire blight is a bacterial disease of Maloideae caused by Erwinia amylovora (Ea). This necrogenic enterobacterium uses a type III secretion system (T3SS) to inject type III effectors into the plant cells to cause disease on its susceptible hosts, including economically important crops like apple and pear. The expressions of marker genes of the salicylic acid (SA) and jasmonic acid (JA) defense regulation pathways were monitored by RT-qPCR in leaves of two apple genotypes, one susceptible and one resistant, challenged with a wild type strain, a T3SS-deficient strain or water. The transcriptional data taken together with hormone level measurements indicated that the SA pathway was similarly induced in both apple genotypes during infection by Ea. On the contrary, the data clearly showed a strong T3SS-dependent down-regulation of the JA pathway in leaves of the susceptible genotype but not in those of the resistant one. Accordingly, methyl-jasmonate treated susceptible plants displayed an increased resistance to Ea. Bacterial mutant analysis indicated that JA manipulation by Ea mainly relies on the type III effector DspA/E. Taken together, our data suggest that the T3SS-dependent down-regulation of the JA pathway is a critical step in the infection process of Malus spp. by Ea.

  15. Regulatory genes and environmental regulation of amylovoran biosynthesis in Erwinia amylovora

    Science.gov (United States)

    The requirement of the exopolysaccharide amylovoran for Erwinia amylovora pathogenesis is well documented. However, regulation of amylovoran biosynthesis has not been comprehensively studied. We have previously reported that amylovoran production is strain-dependent in E. amylovora isolates. We have...

  16. Variations in Disease Resistance of Chestnut Cultivars against Chestnut Blight Fungus, Cryphonectria parasitica

    Institute of Scientific and Technical Information of China (English)

    LEE Sanghyun; KIM Kyunghee; PIAO Chungen; MOON Byungju

    2006-01-01

    Chestnut blight caused by Cryphonectria parasitica is one of the major chestnut diseases occurred on stems and branches. Oriental chestnut has more resistance than American one. Twenty-five cultivars of chestnut tree including various cultivars such as Tsukuba, Okkwang, Rihei, Ginyose, Eunsan, etc. Were tested with a rapid, simple and reliable method. The cultivar Banseki is one of the most resistant cultivars tested and has the necrotic area of 0.40 cm2. However, the necrotic areas of the cultivars of American chestnut, Eunsan, Kwangjujoyul and Eaton, ranges from 3.35 to 2.61 cm2 and these cultivars are relatively susceptible to this pathogen. Many pycnidia of this pathogen were observed on the inner and outer bark tissues after incubating for 3 weeks.

  17. Biological control of fire blight in pear orchards with a formulation of Pantoea agglomerans strain Eh 24 Controle biológico de fire blight em pereiras empregando uma formulação de Pantoea agglomerans Eh 24

    Directory of Open Access Journals (Sweden)

    Hatice Özaktan

    2004-09-01

    Full Text Available Biological control by using epiphytic bacteria against Erwinia amylovora has been considered as an alternative method for controlling the disease. Talc-based formulation of Pantoea agglomerans strain Eh-24 was applied at 30% and 100% bloom on two pear orchards which were selected from different locations in the Aegean Region in Turkey. Pear orchard trials were replicated for two years (1999 and 2000 in each place. Talc-based formulation of P. agglomerans strain Eh-24 was sprayed on pear trees which were naturally infected with E. amylovora. In the orchard trials conducted in 1999 and 2000, talc-based formulation of P. agglomerans strain Eh-24 reduced the percentage of blighted blossoms on pear orchards by 63% to 76%, approximately. Copper oxychloride+maneb was less effective in reducing the incidence of blossom infection by E. amylovora in each pear orchard than the bioformulation treatment. P. agglomerans strain Eh-24 labelled with StrR+ was applied at 30% and 100% bloom to monitor the colonization and population dynamics of P. agglomerans on pear blossoms. The population size of P. agglomerans strain Eh-24 strR+ on pear blossoms increased from 2x10(4 to 1.3x10(6 cfu per blossom over 18 days.Controle biológico de Erwinia amylovora através do uso de bactérias epifíticas tem sido considerado um método alternativo para o controle de "fire blight". Uma formulação de Pantoea agglomerans Eh 24 em talco foi utilizada em pereiras a 30% e a 100% de floração, em duas plantações selecionadas na região Aegean da Turquia. Os experimentos foram repetidos duas vezes (1999 e 2000 em cada plantação. A formulação de P. agglomerans foi aspergida nas pereiras naturalmente infectadas com E. amylovora. Nos experimentos de 1999 e 2000, a redução da porcentagem de ocorrência de "fire blight" foi reduzida aproximadamente em 63% e em 76%, respectivamente. Oxicloreto de cobre + maneb foi menos eficiente na redução da infecção por E. amylovora do

  18. Erwinia carotovora elicitors and Botrytis cinerea activate defense responses in Physcomitrella patens

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    Bentancor Marcel

    2007-10-01

    Full Text Available Abstract Background Vascular plants respond to pathogens by activating a diverse array of defense mechanisms. Studies with these plants have provided a wealth of information on pathogen recognition, signal transduction and the activation of defense responses. However, very little is known about the infection and defense responses of the bryophyte, Physcomitrella patens, to well-studied phytopathogens. The purpose of this study was to determine: i whether two representative broad host range pathogens, Erwinia carotovora ssp. carotovora (E.c. carotovora and Botrytis cinerea (B. cinerea, could infect Physcomitrella, and ii whether B. cinerea, elicitors of a harpin (HrpN producing E.c. carotovora strain (SCC1 or a HrpN-negative strain (SCC3193, could cause disease symptoms and induce defense responses in Physcomitrella. Results B. cinerea and E.c. carotovora were found to readily infect Physcomitrella gametophytic tissues and cause disease symptoms. Treatments with B. cinerea spores or cell-free culture filtrates from E.c. carotovoraSCC1 (CF(SCC1, resulted in disease development with severe maceration of Physcomitrella tissues, while CF(SCC3193 produced only mild maceration. Although increased cell death was observed with either the CFs or B. cinerea, the occurrence of cytoplasmic shrinkage was only visible in Evans blue stained protonemal cells treated with CF(SCC1 or inoculated with B. cinerea. Most cells showing cytoplasmic shrinkage accumulated autofluorescent compounds and brown chloroplasts were evident in a high proportion of these cells. CF treatments and B. cinerea inoculation induced the expression of the defense-related genes: PR-1, PAL, CHS and LOX. Conclusion B. cinerea and E.c. carotovora elicitors induce a defense response in Physcomitrella, as evidenced by enhanced expression of conserved plant defense-related genes. Since cytoplasmic shrinkage is the most common morphological change observed in plant PCD, and that harpins and B

  19. Erwinia oleae sp. nov., isolated from olive knots caused by Pseudomonas savastanoi pv. savastanoi.

    Science.gov (United States)

    Moretti, Chiaraluce; Hosni, Taha; Vandemeulebroecke, Katrien; Brady, Carrie; De Vos, Paul; Buonaurio, Roberto; Cleenwerck, Ilse

    2011-11-01

    Three endophytic bacterial isolates were obtained in Italy from olive knots caused by Pseudomonas savastanoi pv. savastanoi. Phenotypic tests in combination with 16S rRNA gene sequence analysis indicated a phylogenetic position for these isolates in the genera Erwinia or Pantoea, and revealed two other strains with highly similar 16S rRNA gene sequences (>99 %), CECT 5262 and CECT 5264, obtained in Spain from olive knots. Rep-PCR DNA fingerprinting of the five strains from olive knots with BOX, ERIC and REP primers revealed three groups of profiles that were highly similar to each other. Multilocus sequence analysis (MLSA) based on concatenated partial atpD, gyrB, infB and rpoB gene sequences indicated that the strains constituted a single novel species in the genus Erwinia. The strains showed general phenotypic characteristics typical of the genus Erwinia and whole genome DNA-DNA hybridization data confirmed that they represented a single novel species of the genus Erwinia. The strains showed DNA G+C contents ranging from 54.7 to 54.9 mol%. They could be discriminated from phylogenetically related species of the genus Erwinia by their ability to utilize potassium gluconate, l-rhamnose and d-arabitol, but not glycerol, inositol or d-sorbitol. The name Erwinia oleae sp. nov. (type strain DAPP-PG 531(T)= LMG 25322(T) = DSM 23398(T)) is proposed for this novel taxon.

  20. Eliminação da produção de bacteriocinas em Erwinia e Pseudomonas fitopatogênicas Elimination of bacteriocin production in the phytopathogenic bacteria Erwinia and Pseudomonas

    Directory of Open Access Journals (Sweden)

    C.M.R. de Biagi

    1995-04-01

    Full Text Available Duas linhagens de bactérias fitopatogênicas do gênero Pseudomonas e duas do gênero Erwinia produtoras de bacteriocinas, foram submetidas a diferentes tratamentos visando estimar a estabilidade desse caráter. Houve eliminação da produção de bacteriocinas após tratamento com duas concentrações de brometo de etídio e a porcentagem de eliminação variou com o hospedeiro e com a concentração da droga. Não houve eliminação em temperaturas elevadas e também a preservação da linhagem por três anos em laboratório não causou perda do caráter. A eliminação da produção de bacteriocinas com brometo de etídio sugere que os genes envolvidos tenham localização plasmidiana.Four strains, two from each of the plant pathogenic bacteria Pseudomonas and Erwinia, all producing bacteriocins, were submitted to different treatments in order to evaluate the persistance of bacteriocin production. After ethidium bromide treatment elimination of the bacteriocin production was achieved and the percentage of loss varied with the host strain and drug concentration. Elimination was not detected after treatment with high temperatures, above the normal ones. Also preservation of the strains for three years, in laboratory, did not cause elimination of the character. The curing of bacteriocin production after ethidium bromide treatment suggests that the involved genes are located in plasmids.

  1. Cladosporium cladosporioides and C. tenuissimum Cause Blossom Blight in Strawberry in Korea.

    Science.gov (United States)

    Nam, Myeong Hyeon; Park, Myung Soo; Kim, Hyun Sook; Kim, Tae Il; Kim, Hong Gi

    2015-09-01

    Blossom blight in strawberry was first observed in a green house in Nonsan, Damyang, and Geochang areas of Korea, between early January to April of 2012. Disease symptoms started as a grey fungus formed on the stigma, which led to the blossom blight and eventually to black rot and necrosis of the entire flower. We isolated the fungi purely from the infected pistils and maintained them on potato dextrose agar (PDA) slants. To test Koch's postulates, we inoculated the fungi and found that all of the isolates caused disease symptoms in the flower of strawberry cultivars (Seolhyang, Maehyang, and Kumhyang). The isolates on PDA had a velvet-like appearance, and their color ranged between olivaceous-brown and smoky-grey to olive and almost black. The intercalary conidia of the isolates were elliptical to limoniform, with sizes ranging from 5.0~10.5 × 2.5~3.0 µm to 4.0~7.5 × 2.0~3.0 µm, respectively. The secondary ramoconidia of these isolates were 0- or 1-septate, with sizes ranging betweem 10.0~15.0 × 2.5~3.7 µm and 8.7~11.2 × 2.5~3.2 µm, respectively. A combined sequence analysis of the internal transcribed spacer regions, partial actin (ACT), and translation elongation factor 1-alpha (TEF) genes revealed that the strawberry isolates belonged to two groups of authentic strains, Cladosporium cladosporioides and C. tenuissimum. Based on these results, we identified the pathogens causing blossom blight in strawberries in Korea as being C. cladosporioides and C. tenuissimum.

  2. Genome analyses of an aggressive and invasive lineage of the Irish potato famine pathogen

    Science.gov (United States)

    Pest and pathogen losses pose a serious threat to global food security and ever since the 19th century Irish famine, potato late blight has exemplified this threat1,2. The causal oomycete pathogen, Phytophthora infestans, undergoes major population shifts in agricultural systems via the successive e...

  3. Reconstructing genome evolution in historic samples of the Irish potato famine pathogen

    DEFF Research Database (Denmark)

    Martin, Michael David; Cappellini, Enrico; Samaniego Castruita, Jose Alfredo;

    2013-01-01

    Responsible for the Irish potato famine of 1845-49, the oomycete pathogen Phytophthora infestans caused persistent, devastating outbreaks of potato late blight across Europe in the 19th century. Despite continued interest in the history and spread of the pathogen, the genome of the famine...

  4. Reconstructing genome evolution in historic samples of the Irish potato famine pathogen

    DEFF Research Database (Denmark)

    Martin, Michael David; Cappellini, Enrico; Samaniego Castruita, Jose Alfredo;

    2013-01-01

    Responsible for the Irish potato famine of 1845-49, the oomycete pathogen Phytophthora infestans caused persistent, devastating outbreaks of potato late blight across Europe in the 19th century. Despite continued interest in the history and spread of the pathogen, the genome of the famine-era str...

  5. Immobilization of glucosyltransferase from Erwinia sp. using two different techniques.

    Science.gov (United States)

    Contesini, Fabiano Jares; Ibarguren, Carolina; Grosso, Carlos Raimundo Ferreira; Carvalho, Patrícia de Oliveira; Sato, Hélia Harumi

    2012-04-15

    Two different techniques of glucosyltransferase immobilization were studied for the conversion of sucrose into isomaltulose. The optimum conditions for immobilization of Erwinia sp. glucosyltransferase onto Celite 545, determined using response surface methodology, was pH 4.0 and 170 U of glucosyltransferase/g of Celite 545. Using this conditions more than 60% conversion of sucrose into isomaltulose can be obtained. The immobilization of glucosyltransferase was also studied by its entrapment in microcapsules of low-methoxyl pectin and fat (butter and oleic acid). The non-lyophilized microcapsules of pectin, containing the enzyme and fat, showed higher glucosyltransferase activity, compared with lyophilized microcapsules containing enzyme plus fat, and also lyophilized microcapsules containing enzyme without fat addition. The non-lyophilized microcapsules of pectin containing the glucosyltransferase and fat, converted 30% of sucrose into isomaltulose in the first batch. However the conversion decreased to 5% at the 10th batch, indicating inactivation of the enzyme.

  6. BRS Eliza: cultivar de batata para mesa, com película lisa e resistência à pinta-preta e à requeima BRS Eliza: a fresh market potato cultivar, with smooth skin and early and late blight resistance

    Directory of Open Access Journals (Sweden)

    Arione S. Pereira

    2001-11-01

    Full Text Available BRS Eliza é uma cultivar de batata para consumo de mesa liberada em 2001, pela Embrapa Clima Temperado, Pelotas (RS. É mais adequada ao preparo de purê e salada (cremosa. O ciclo é médio. Os tubérculos têm formato oval, película lisa e amarela, pouca sensibilidade ao esverdeamento, polpa amarelo-clara e olhos superficiais. Não mostrou defeitos fisiológicos nos tubérculos. Tem boa resistência de campo à requeima (Phytophthora infestans e à pinta- preta (Alternaria solani e mediana a viroses. BRS Eliza é suscetível à canela-preta (Erwinia carotovara. Produz alta percentagem de tubérculos de tamanho comercial. Deve ser comercialisada imediatamente após a colheita, requerendo manejo cuidadoso da semente no armazenamentoBRS Eliza is a tablestock potato cultivar released in 2001, by Embrapa Clima Temperado, Pelotas, Brazil. It is adequate for purée and salad. Maturity is medium early. Tubers are oval shaped, yellow and smooth skin, low sensitivity to greening, yellow clear flesh and shallow eyes. BRS Eliza did not show physiological defects on the tubers. Has a good field resistance to late (Phytophthora infestans and early blight (Alternaria solani, and medium resistance to main viroses. BRS Eliza is susceptible to black leg (Erwinia carotovora. It produces a high percentage of commercial tubers. Must be marketed immediately after harvesting. It requires accurate seed management in storage.

  7. Effect of meteorological factors on the development of lentil stemphylium blight at different sowing dates in rampur, chitwan, Nepal

    Directory of Open Access Journals (Sweden)

    Subash Subedi

    2016-04-01

    Full Text Available Stemphylium species are pathogenic to a number of crops under broad geography and diverse environments. Stemphylium blight of lentil (Lens culinaris Medik caused by Stemphylium botryosum Walr is becoming a serious emerging threat to lentil cultivation and become widespread throughout major legume growing areas in Nepal. Lentil was sown in different dates to observed incidence and severity of stemphylium blight in Rampur, Chitwan during two consecutive years 2012-2014. Lentil seeds sown up to middle of November escaped the disease severity and also resulted higher yield compared to other dates. Disease severity increased with the advancement of sowing date from November 1 to December 21 with decreased yields. The trends of disease development were similar in both years. The maximum and minimum temperatures, total rainfall and sunshine hour ranging from 22.42-24.23°C (mean 23.32°C, 4.12-13.00°C(mean 8.56°C, 9.6-30.5mm (mean 24.85mm and 200.05-309.85 hour (mean 254.95 hour respectively were favorable for disease development. A multiple linear regression model with temperature, rainfall and sunshine hours was developed to predict stemphylium blight disease severity on lentil plants.

  8. Transgenic American chestnuts show enhanced blight resistance and transmit the trait to T1 progeny.

    Science.gov (United States)

    Newhouse, Andrew E; Polin-McGuigan, Linda D; Baier, Kathleen A; Valletta, Kristia E R; Rottmann, William H; Tschaplinski, Timothy J; Maynard, Charles A; Powell, William A

    2014-11-01

    American chestnut (Castanea dentata) is a classic example of a native keystone species that was nearly eradicated by an introduced fungal pathogen. This report describes progress made toward producing a fully American chestnut tree with enhanced resistance to the blight fungus (Cryphonectria parasitica). The transgenic American chestnut 'Darling4,' produced through an Agrobacterium co-transformation procedure to express a wheat oxalate oxidase gene driven by the VspB vascular promoter, shows enhanced blight resistance at a level intermediate between susceptible American chestnut and resistant Chinese chestnut (Castanea mollissima). Enhanced resistance was identified first with a leaf-inoculation assay using young chestnuts grown indoors, and confirmed with traditional stem inoculations on 3- and 4-year-old field-grown trees. Pollen from 'Darling4' and other events was used to produce transgenic T1 seedlings, which also expressed the enhanced resistance trait in leaf assays. Outcrossed transgenic seedlings have several advantages over tissue-cultured plantlets, including increased genetic diversity and faster initial growth. This represents a major step toward the restoration of the majestic American chestnut.

  9. Current progress on genetic interactions of rice with rice blast and sheath blight fungi

    Institute of Scientific and Technical Information of China (English)

    Yulin JIA; Guangjie LIU; Stefano COSTANZO; Seonghee LEE; Yuntao DAI

    2009-01-01

    Analysis of genetic interactions between rice and its pathogenic fungi Magnaporthe oryzae and Rhizoctonia solani should lead to a better understanding of molecular mechanisms of host resistance, and the improvement of strategies to manage rice blast and sheath blight diseases. Currently, dozens office resistance (R) genes against specific races of the blast fungus have been described. Among them, ten were molecularly characterized and some were widely used for breeding for genetic resistance. The Pi-ta gene was one of the best characterized rice R genes. Following the elucidation of its molecular structure, interaction, distribution, and evolution, user friendly DNA markers were developed from portions of the cloned genes to facilitate the incorporations of the Pi-ta mediated resistance into improved rice varieties using marker assisted selection (MAS). However, rice blast is still a major threat for stable rice production because of race change mutations occurring in rice fields, which often overcome added resistance based on single R genes, and these virulent races of M. oryzae pose a continued challenge for blast control. For sheath blight, progress has been made on the exploration of novel sources of resistance from wild rice relatives and indica rice cultivars. A major quantitative trait locus (QTL), named qSB9-2, was recently verified in several mapping populations with different phenotyping methods, including greenhouse methods. The ability to identify qSB9-2 using greenhouse methods should accelerate the efforts on the qSB9-2 fine mapping and positional cloning.

  10. AmyR is a novel negative regulator of amylovoran production in Erwinia amylovora.

    Directory of Open Access Journals (Sweden)

    Dongping Wang

    Full Text Available In this study, we attempted to understand the role of an orphan gene amyR in Erwinia amylovora, a functionally conserved ortholog of ybjN in Escherichia coli, which has recently been characterized. Amylovoran, a high molecular weight acidic heteropolymer exopolysaccharide, is a virulent factor of E. amylovora. As reported earlier, amylovoran production in an amyR knockout mutant was about eight-fold higher than that in the wild type (WT strain of E. amylovora. When a multicopy plasmid containing the amyR gene was introduced into the amyR mutant or WT strains, amylovoran production was strongly inhibited. Furthermore, amylovoran production was also suppressed in various amylovoran-over-producing mutants, such as grrSA containing multicopies of the amyR gene. Consistent with amylovoran production, an inverse correlation was observed between in vitro expression of amyR and that of amylovoran biosynthetic genes. However, both the amyR knockout mutant and over-expression strains showed reduced levan production, another exopolysaccharide produced by E. amylovora. Virulence assays demonstrated that while the amyR mutant was capable of inducing slightly greater disease severity than that of the WT strain, strains over-expressing the amyR gene did not incite disease on apple shoots or leaves, and only caused reduced disease on immature pear fruits. Microarray studies revealed that amylovoran biosynthesis and related membrane protein-encoding genes were highly expressed in the amyR mutant, but down-regulated in the amyR over-expression strains in vitro. Down-regulation of amylovoran biosynthesis genes in the amyR over-expression strain partially explained why over-expression of amyR led to non-pathogenic or reduced virulence in vivo. These results suggest that AmyR plays an important role in regulating exopolysaccharide production, and thus virulence in E. amylovora.

  11. AmyR is a novel negative regulator of amylovoran production in Erwinia amylovora.

    Science.gov (United States)

    Wang, Dongping; Korban, Schuyler S; Pusey, P Lawrence; Zhao, Youfu

    2012-01-01

    In this study, we attempted to understand the role of an orphan gene amyR in Erwinia amylovora, a functionally conserved ortholog of ybjN in Escherichia coli, which has recently been characterized. Amylovoran, a high molecular weight acidic heteropolymer exopolysaccharide, is a virulent factor of E. amylovora. As reported earlier, amylovoran production in an amyR knockout mutant was about eight-fold higher than that in the wild type (WT) strain of E. amylovora. When a multicopy plasmid containing the amyR gene was introduced into the amyR mutant or WT strains, amylovoran production was strongly inhibited. Furthermore, amylovoran production was also suppressed in various amylovoran-over-producing mutants, such as grrSA containing multicopies of the amyR gene. Consistent with amylovoran production, an inverse correlation was observed between in vitro expression of amyR and that of amylovoran biosynthetic genes. However, both the amyR knockout mutant and over-expression strains showed reduced levan production, another exopolysaccharide produced by E. amylovora. Virulence assays demonstrated that while the amyR mutant was capable of inducing slightly greater disease severity than that of the WT strain, strains over-expressing the amyR gene did not incite disease on apple shoots or leaves, and only caused reduced disease on immature pear fruits. Microarray studies revealed that amylovoran biosynthesis and related membrane protein-encoding genes were highly expressed in the amyR mutant, but down-regulated in the amyR over-expression strains in vitro. Down-regulation of amylovoran biosynthesis genes in the amyR over-expression strain partially explained why over-expression of amyR led to non-pathogenic or reduced virulence in vivo. These results suggest that AmyR plays an important role in regulating exopolysaccharide production, and thus virulence in E. amylovora.

  12. Erwinia amylovora CRISPR elements provide new tools for evaluating strain diversity and for microbial source tracking.

    Science.gov (United States)

    McGhee, Gayle C; Sundin, George W

    2012-01-01

    Clustered regularly interspaced short palindromic repeats (CRISPRs) comprise a family of short DNA repeat sequences that are separated by non repetitive spacer sequences and, in combination with a suite of Cas proteins, are thought to function as an adaptive immune system against invading DNA. The number of CRISPR arrays in a bacterial chromosome is variable, and the content of each array can differ in both repeat number and in the presence or absence of specific spacers. We utilized a comparative sequence analysis of CRISPR arrays of the plant pathogen Erwinia amylovora to uncover previously unknown genetic diversity in this species. A total of 85 E. amylovora strains varying in geographic isolation (North America, Europe, New Zealand, and the Middle East), host range, plasmid content, and streptomycin sensitivity/resistance were evaluated for CRISPR array number and spacer variability. From these strains, 588 unique spacers were identified in the three CRISPR arrays present in E. amylovora, and these arrays could be categorized into 20, 17, and 2 patterns types, respectively. Analysis of the relatedness of spacer content differentiated most apple and pear strains isolated in the eastern U.S. from western U.S. strains. In addition, we identified North American strains that shared CRISPR genotypes with strains isolated on other continents. E. amylovora strains from Rubus and Indian hawthorn contained mostly unique spacers compared to apple and pear strains, while strains from loquat shared 79% of spacers with apple and pear strains. Approximately 23% of the spacers matched known sequences, with 16% targeting plasmids and 5% targeting bacteriophage. The plasmid pEU30, isolated in E. amylovora strains from the western U.S., was targeted by 55 spacers. Lastly, we used spacer patterns and content to determine that streptomycin-resistant strains of E. amylovora from Michigan were low in diversity and matched corresponding streptomycin-sensitive strains from the

  13. Erwinia amylovora CRISPR elements provide new tools for evaluating strain diversity and for microbial source tracking.

    Directory of Open Access Journals (Sweden)

    Gayle C McGhee

    Full Text Available Clustered regularly interspaced short palindromic repeats (CRISPRs comprise a family of short DNA repeat sequences that are separated by non repetitive spacer sequences and, in combination with a suite of Cas proteins, are thought to function as an adaptive immune system against invading DNA. The number of CRISPR arrays in a bacterial chromosome is variable, and the content of each array can differ in both repeat number and in the presence or absence of specific spacers. We utilized a comparative sequence analysis of CRISPR arrays of the plant pathogen Erwinia amylovora to uncover previously unknown genetic diversity in this species. A total of 85 E. amylovora strains varying in geographic isolation (North America, Europe, New Zealand, and the Middle East, host range, plasmid content, and streptomycin sensitivity/resistance were evaluated for CRISPR array number and spacer variability. From these strains, 588 unique spacers were identified in the three CRISPR arrays present in E. amylovora, and these arrays could be categorized into 20, 17, and 2 patterns types, respectively. Analysis of the relatedness of spacer content differentiated most apple and pear strains isolated in the eastern U.S. from western U.S. strains. In addition, we identified North American strains that shared CRISPR genotypes with strains isolated on other continents. E. amylovora strains from Rubus and Indian hawthorn contained mostly unique spacers compared to apple and pear strains, while strains from loquat shared 79% of spacers with apple and pear strains. Approximately 23% of the spacers matched known sequences, with 16% targeting plasmids and 5% targeting bacteriophage. The plasmid pEU30, isolated in E. amylovora strains from the western U.S., was targeted by 55 spacers. Lastly, we used spacer patterns and content to determine that streptomycin-resistant strains of E. amylovora from Michigan were low in diversity and matched corresponding streptomycin-sensitive strains

  14. PR genes of apple: identification and expression in response to elicitors and inoculation with Erwinia amylovora

    Directory of Open Access Journals (Sweden)

    Kim Jihyun F

    2006-10-01

    Full Text Available Abstract Background In the past decade, much work has been done to dissect the molecular basis of the defence signalling pathway in plants known as Systemic Acquired Resistance (SAR. Most of the work has been carried out in model species such as Arabidopsis, with little attention paid to woody plants. However within the range of species examined, components of the pathway seem to be highly conserved. In this study, we attempted to identify downstream components of the SAR pathway in apple to serve as markers for its activation. Results We identified three pathogenesis related (PR genes from apple, PR-2, PR-5 and PR-8, which are induced in response to inoculation with the apple pathogen, Erwinia amylovora, but they are not induced in young apple shoots by treatment with known elicitors of SAR in herbaceous plants. We also identified three PR-1-like genes from apple, PR-1a, PR-1b and PR-1c, based solely on sequence similarity to known PR-1 genes of model (intensively researched herbaceous plants. The PR-1-like genes were not induced in response to inoculation with E. amylovora or by treatment with elicitors; however, each showed a distinct pattern of expression. Conclusion Four PR genes from apple were partially characterized. PR-1a, PR-2, PR-5 and PR-8 from apple are not markers for SAR in young apple shoots. Two additional PR-1-like genes were identified through in-silico analysis of apple ESTs deposited in GenBank. PR-1a, PR-1b and PR-1c are not involved in defence response or SAR in young apple shoots; this conclusion differs from that reported previously for young apple seedlings.

  15. Characteristics of Resistance to Rice Sheath Blight of Zhongda 2, a Transgenic Rice Line as Modified by Gene "RC24"

    Institute of Scientific and Technical Information of China (English)

    YUAN Hong-xu; XU Xin-ping; ZHANG Jian-zhong; GUO Jian-fu; LI Bao-jian

    2004-01-01

    The transgenic rice, Zhongda 2, which was genetically modified from an indica rice line Zhuxian B by rice chitinase gene (RC24), had high resistance to rice sheath blight (Rhizoctonia solani) in laboratory and a two-year field experiment. The pathogen could invade sheath of Zhongda 2 and induce symptoms of the disease. No difference was noted in time of penetration or incubation period between Zhongda 2 and non-transgenic rice control, Zhuxian B, but the hyphae lysate could be observed earlier five non-transgenic rice lines showed higher resistance than donor non-transgenic parents, but the resistance was different along with the different maternal parents.

  16. The acyl-homoserine lactone-type quorum-sensing system modulates cell motility and virulence of Erwinia chrysanthemi pv. zeae.

    Science.gov (United States)

    Hussain, Mumtaz B B M; Zhang, Hai-Bao; Xu, Jin-Ling; Liu, Qiongguang; Jiang, Zide; Zhang, Lian-Hui

    2008-02-01

    Erwinia chrysanthemi pv. zeae is one of the Erwinia chrysanthemi pathovars that infects on both dicotyledons and monocotyledons. However, little is known about the molecular basis and regulatory mechanisms of its virulence. By using a transposon mutagenesis approach, we cloned the genes coding for an E. chrysanthemi pv. zeae synthase of acyl-homoserine lactone (AHL) quorum-sensing signals (expI(Ecz)) and a cognate response regulator (expR(Ecz)). Chromatography analysis showed that expI(Ecz) encoded production of the AHL signal N-(3-oxo-hexanoyl)-homoserine lactone (OHHL). Null mutation of expI(Ecz) in the E. chrysanthemi pv. zeae strain EC1 abolished AHL production, increased bacterial swimming and swarming motility, disabled formation of multicell aggregates, and attenuated virulence of the pathogen on potato tubers. The mutation also marginally reduced the inhibitory activity of E. chrysanthemi pv. zeae on rice seed germination. The mutant phenotypes were rescued by either exogenous addition of AHL signal or in trans expression of expI(Ecz). These data demonstrate that the AHL-type QS signal plays an essential role in modulation of E. chrysanthemi pv. zeae cell motility and the ability to form multicell aggregates and is involved in regulation of bacterial virulence.

  17. Comparative genomics of 12 strains of Erwinia amylovora identifies a pan-genome with a large conserved core.

    Science.gov (United States)

    Mann, Rachel A; Smits, Theo H M; Bühlmann, Andreas; Blom, Jochen; Goesmann, Alexander; Frey, Jürg E; Plummer, Kim M; Beer, Steven V; Luck, Joanne; Duffy, Brion; Rodoni, Brendan

    2013-01-01

    The plant pathogen Erwinia amylovora can be divided into two host-specific groupings; strains infecting a broad range of hosts within the Rosaceae subfamily Spiraeoideae (e.g., Malus, Pyrus, Crataegus, Sorbus) and strains infecting Rubus (raspberries and blackberries). Comparative genomic analysis of 12 strains representing distinct populations (e.g., geographic, temporal, host origin) of E. amylovora was used to describe the pan-genome of this major pathogen. The pan-genome contains 5751 coding sequences and is highly conserved relative to other phytopathogenic bacteria comprising on average 89% conserved, core genes. The chromosomes of Spiraeoideae-infecting strains were highly homogeneous, while greater genetic diversity was observed between Spiraeoideae- and Rubus-infecting strains (and among individual Rubus-infecting strains), the majority of which was attributed to variable genomic islands. Based on genomic distance scores and phylogenetic analysis, the Rubus-infecting strain ATCC BAA-2158 was genetically more closely related to the Spiraeoideae-infecting strains of E. amylovora than it was to the other Rubus-infecting strains. Analysis of the accessory genomes of Spiraeoideae- and Rubus-infecting strains has identified putative host-specific determinants including variation in the effector protein HopX1(Ea) and a putative secondary metabolite pathway only present in Rubus-infecting strains.

  18. Comparative genomics of 12 strains of Erwinia amylovora identifies a pan-genome with a large conserved core.

    Directory of Open Access Journals (Sweden)

    Rachel A Mann

    Full Text Available The plant pathogen Erwinia amylovora can be divided into two host-specific groupings; strains infecting a broad range of hosts within the Rosaceae subfamily Spiraeoideae (e.g., Malus, Pyrus, Crataegus, Sorbus and strains infecting Rubus (raspberries and blackberries. Comparative genomic analysis of 12 strains representing distinct populations (e.g., geographic, temporal, host origin of E. amylovora was used to describe the pan-genome of this major pathogen. The pan-genome contains 5751 coding sequences and is highly conserved relative to other phytopathogenic bacteria comprising on average 89% conserved, core genes. The chromosomes of Spiraeoideae-infecting strains were highly homogeneous, while greater genetic diversity was observed between Spiraeoideae- and Rubus-infecting strains (and among individual Rubus-infecting strains, the majority of which was attributed to variable genomic islands. Based on genomic distance scores and phylogenetic analysis, the Rubus-infecting strain ATCC BAA-2158 was genetically more closely related to the Spiraeoideae-infecting strains of E. amylovora than it was to the other Rubus-infecting strains. Analysis of the accessory genomes of Spiraeoideae- and Rubus-infecting strains has identified putative host-specific determinants including variation in the effector protein HopX1(Ea and a putative secondary metabolite pathway only present in Rubus-infecting strains.

  19. EVALUATION OF DISEASE RESISTANCE POTENTIAL OF SEVEN POTATO GENOTYPES AGAINST EARLY BLIGHT CAUSED BY Alternaria tenuissima UNDER GREENHOUSE CONDITIONS

    Directory of Open Access Journals (Sweden)

    Hamid Reza Mirkarimi

    2013-07-01

    Full Text Available Early blight of potato was caused by various species of genus Alternaria, the disease has a prominent role in reducing crop yields in most of the countries, especially in Iran. Various studies has been conducted for the finding out the information regarding the diversity of pathogen and estimation of damage caused by genus Alternaria tenuissima in Iran, but the information regarding the resistance against this fungal pathogen in various genotype of potatoes are in scarcity. Seven isolates of potato were obtained from the National Plant Gene Bank of Iran. Amongst these seven, on the basis of mean comparison curve progress Cosmos was recognized as the most sensitive genetic samples while the samples Armida was reported as a most resistant to the disease. Other cultivars showed different levels of resistance against this pathogen.

  20. Fungicides and Application Timing for Control of Early Leafspot, Southern Blight, and Sclerotinia Blight of Peanut

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    W. James Grichar

    2016-01-01

    Full Text Available Field studies were conducted in 2013 and 2014 in south Texas near Yoakum and from 2008 to 2011 in central Texas near Stephenville to evaluate various fungicides for foliar and soilborne disease control as well as peanut yield response under irrigation. Control of Sclerotinia blight caused by Sclerotinia minor Jagger with penthiopyrad at 1.78 L/ha was comparable to fluazinam or boscalid; however, the 1.2 L/ha dose of penthiopyrad did not provide consistent control. Peanut yield was reduced with the lower penthiopyrad dose when compared with boscalid, fluazinam, or the high dose of penthiopyrad. Control of early leaf spot, caused by Cercospora arachidicola S. Hori or southern blight, caused by Sclerotium rolfsii Sacc., with penthiopyrad in a systems approach was comparable with propiconazole, prothioconazole, or pyraclostrobin systems and resulted in disease control that was higher than the nontreated control. Peanut yield was also comparable with the penthiopyrad, propiconazole, prothioconazole, or pyraclostrobin systems and reflects the ability of the newer fungicides to control multiple diseases found in Texas peanut production.

  1. Resistance to Bacterial Leaf Blight in a Somaclonal Rice Mutant HX-3 at Cellular Level

    Institute of Scientific and Technical Information of China (English)

    GAO Dong-ying; ZHOU Yi-hong; HUANG Xue-qing; SUN Li-hua; LIU Ai-min

    2004-01-01

    The interaction between rice host and its pathogen Xanthomonas oryzae pv. oryzae (Xoo) at cellular level was studied by using a resistant somaclonal mutant HX-3 and its susceptable donor Minghui 63. After inoculation with Xoo strain Zhe 173 (Chinese pathotype Ⅳ), the activity of superoxide dismutase (SOD) and peroxidase (POD) in the callus of Minghui 63 was increased dramatically, and the active oxygen(O2 - .) was produced at a higher rate; Meanwhile, the callus grew slowly with the reduction of protein content. Compared to the activity of SOD and POD, the production rate of O2-. and the fresh weight in HX-3 callus varied little after the inoculation. It could be proposed that there were great differences between the resistance of HX-3 and Mighui 63 at cellular level. There was no difference detected concerning resistance to bacterial leaf blight in HX-3 between the plant and the callus.

  2. Molecular characterization of soil bacteria antagonistic to Rhizoctonia solani, sheath blight of rice.

    Science.gov (United States)

    Padaria, Jasdeep C; Singh, Aqbal

    2009-05-01

    Bacillus pumillus MTCC7615 has been identified as a potent isolate against Rhizocotonia solani, the fungal pathogen causing sheath blight in rice. The study aimed at probing the role of a 23kb size plasmid pJCP07 of Bacillus pumillus MTCC7615 in its fungal antagonism towards Rhizocotonia solani. Plasmid pJCP07 was found to be involved in production of a fungal antagonistic compound as demonstrated by plasmid curing and conjugational transfer experiments. Tn5 insertional studies further confirmed that the plasmid pJCP07 of Bacillus pumillus MTCC7615 carries some of the gene(s) involved in production of compound antagonistic to Rhizocotonia solani. The plasmid pJCP07 is thus a mobilizable medium-sized plasmid carrying genes responsible for antagonism of Bacillus pumillus MTCC7615 towards Rhizocotonia solani.

  3. Differential Expression of Biphenyl Synthase Gene Family Members in Fire-Blight-Infected Apple ‘Holsteiner Cox’ 1[W][OA

    Science.gov (United States)

    Chizzali, Cornelia; Gaid, Mariam M.; Belkheir, Asma K.; Hänsch, Robert; Richter, Klaus; Flachowsky, Henryk; Peil, Andreas; Hanke, Magda-Viola; Liu, Benye; Beerhues, Ludger

    2012-01-01

    Fire blight, caused by the bacterium Erwinia amylovora, is a devastating disease of apple (Malus × domestica). The phytoalexins of apple are biphenyls and dibenzofurans, whose carbon skeleton is formed by biphenyl synthase (BIS), a type III polyketide synthase. In the recently published genome sequence of apple ‘Golden Delicious’, nine BIS genes and four BIS gene fragments were detected. The nine genes fall into four subfamilies, referred to as MdBIS1 to MdBIS4. In a phylogenetic tree, the BIS amino acid sequences from apple and Sorbus aucuparia formed an individual cluster within the clade of the functionally diverse type III polyketide synthases. cDNAs encoding MdBIS1 to MdBIS4 were cloned from fire-blight-infected shoots of apple ‘Holsteiner Cox,’ heterologously expressed in Escherichia coli, and functionally analyzed. Benzoyl-coenzyme A and salicoyl-coenzyme A were the preferred starter substrates. In response to inoculation with E. amylovora, the BIS3 gene was expressed in stems of cv Holsteiner Cox, with highest transcript levels in the transition zone between necrotic and healthy tissues. The transition zone was the accumulation site of biphenyl and dibenzofuran phytoalexins. Leaves contained transcripts for BIS2 but failed to form immunodetectable amounts of BIS protein. In cell cultures of apple ‘Cox Orange,’ expression of the BIS1 to BIS3 genes was observed after the addition of an autoclaved E. amylovora suspension. Using immunofluorescence localization under a confocal laser-scanning microscope, the BIS3 protein in the transition zone of stems was detected in the parenchyma of the bark. Dot-shaped immunofluorescence was confined to the junctions between neighboring cortical parenchyma cells. PMID:22158676

  4. Gene expression analysis during cassava defense response to bacterial blight disease

    Directory of Open Access Journals (Sweden)

    Soto-Suárez Mauricio

    2006-12-01

    Full Text Available Cassava bacterial blight (CBB caused by Xanthomonas axonopodis pv. manihotis (Xam is a destructive disease in the South América and África and yield losses range between 12 and 100%. Cytochemistry and biochemistry of defense response to CBB have been well studied. However, the response of the plant to pathogen attack at the molecular and cellular level remains uncharacterized. Identification of genes associated with defense responses is one of most critical steps leading to the elucidation of disease resistance mechanisms in cassava. In this study, we identified differentially expressed genes during pathogen attack by subtractive hybridization, using the Differential Subtraction Chain method (DSC. A population of cDNA obtained from infected plants was used as ";treatment"; and a population of cDNA obtained from healthy plants was used as ";control";. 1536 clones were isolated from the resistant varieties (MBRA 685 and SG 107-35. Of these, 110 randomly selected clones were sequenced and a homology search was conducted. The sequence analysis showed that 14 cDNA clones shared homology with plant genes involved in defense responses, 70 clones were either homologous to plant genes of unknown function or showed no homology, representing new genes potentially involved in cassava defense responses. A cDNA microarray was constructed by spotting the clones identified from our subtractive libraries. Other clones potentially involved in cassava defense responses were also included. The cassava defense cDNA microarray was used to confirm the differential expression of the clones. Keywords: cassava, bacterial blight, gene expression, subtractive library, microarrays.

  5. Fusarium head blight of winter rye (Secale cereale L.

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    Irena Kiecana

    2012-12-01

    Full Text Available Investigations on Fusarium head blight of rye were carried out in the years 2005-2007 on 10 production fields in the Lublin region. The percentage of heads showing the fusariosis symptoms in the years 2005-2007 ranged from 0 to 7%. Mycological analysis of kernels and chaff obtained from heads with Fusarium blight (scab symptoms showed that Fusarium avenaceum, Fusarium culmorum and Fusarium sporotrichioides were the largest threat to heads of this cereal. The species of Fusarium poae and Fusarium crookwellense were also isolated from infected rye heads. The dominance of particular species in infecting rye heads was determined by weather conditions.

  6. Host exopolysaccharide quantity and composition impact Erwinia amylovora bacteriophage pathogenesis.

    Science.gov (United States)

    Roach, Dwayne R; Sjaarda, David R; Castle, Alan J; Svircev, Antonet M

    2013-05-01

    Erwinia amylovora bacteriophages (phages) belonging to the Myoviridae and Podoviridae families demonstrated a preference for either high-exopolysaccharide-producing (HEP) or low-exopolysaccharide-producing (LEP) bacterial hosts when grown on artificial medium without or with sugar supplementation. Myoviridae phages produced clear plaques on LEP hosts and turbid plaques on HEP hosts. The reverse preference was demonstrated by most Podoviridae phages, where clear plaques were seen on HEP hosts. Efficiency of plating (EOP) was determined by comparing phage growth on the original isolation host to the that on the LEP or HEP host. Nine of 10 Myoviridae phages showed highest EOPs on LEP hosts, and 8 of 11 Podoviridae phages had highest EOPs on HEP hosts. Increasing the production of EPS on sugar-supplemented medium or decreasing production by knocking out the synthesis of amylovoran or levan, the two EPSs produced by E. amylovora, indicated that these components play crucial roles in phage infection. Amylovoran was virtually essential for proliferation of most Podoviridae phages when phage population growth was compared to the wild type. Decreased levan production resulted in a significant reduction of progeny from phages in the Myoviridae family. Thus, Podoviridae phages are adapted to hosts that produce high levels of exopolysaccharides and are dependent on host-produced amylovoran for pathogenesis. Myoviridae phages are adapted to hosts that produce lower levels of exopolysaccharides and host-produced levan.

  7. RHEOLOGICAL BEHAVIOR OF ERWINIA GUM IN AQUEOUS SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Li-na Zhang; Mei Zhang; Jing-hua Chen; Hideki Iijima; Hiromichi Tsuchiya

    1999-01-01

    Erwinia (E) gum, an extracellular polysaccharide, is composed of fucose, galatose, glucose and glucuronic acid. Its viscosity behavior was investigated by a low-shear-rate multiball viscometer and a rotational viscometer. Its weight-average molecular weight Mw and intrinsic viscosity [η] in 0.2 mol/L NaCl aqueous solution were measured by light scattering method at 35℃ and viscometry at 25℃ and found to be 1.06 × 106 g/mol and 1050 mL/g, respectively, and its aggregates in aqueous solution were proved by gel permeation chromatography (GPC). These results indicated that E gum in water has exceedingly high viscosity and exhibits Binham fluid behavior, owing to its aggregation. The viscosity of E gum decreased with increasing temperature, and the turning point appeared at 38℃ for dilute solution and 80℃ for concentrated solution suggesting that the aggregates of E gum in water started to disaggregate under these temperatures. In addition, the aggregates can be disrupted by adding either acid or base. The experimental results indicated that the E gum is a good thickening agent, and its fluid behavior is similar to xanthan.

  8. Differential Colonization Dynamics of Cucurbit Hosts by Erwinia tracheiphila.

    Science.gov (United States)

    Vrisman, Cláudio M; Deblais, Loïc; Rajashekara, Gireesh; Miller, Sally A

    2016-07-01

    Bacterial wilt is one of the most destructive diseases of cucurbits in the Midwestern and Northeastern United States. Although the disease has been studied since 1900, host colonization dynamics remain unclear. Cucumis- and Cucurbita-derived strains exhibit host preference for the cucurbit genus from which they were isolated. We constructed a bioluminescent strain of Erwinia tracheiphila (TedCu10-BL#9) and colonization of different cucurbit hosts was monitored. At the second-true-leaf stage, Cucumis melo plants were inoculated with TedCu10-BL#9 via wounded leaves, stems, and roots. Daily monitoring of colonization showed bioluminescent bacteria in the inoculated leaf and petiole beginning 1 day postinoculation (DPI). The bacteria spread to roots via the stem by 2 DPI, reached the plant extremities 4 DPI, and the plant wilted 6 DPI. However, Cucurbita plants inoculated with TedCu10-BL#9 did not wilt, even at 35 DPI. Bioluminescent bacteria were detected 6 DPI in the main stem of squash and pumpkin plants, which harbored approximately 10(4) and 10(1) CFU/g, respectively, of TedCu10-BL#9 without symptoms. Although significantly less systemic plant colonization was observed in nonpreferred host Cucurbita plants compared with preferred hosts, the mechanism of tolerance of Cucurbita plants to E. tracheiphila strains from Cucumis remains unknown.

  9. Tasmancin and lysogenic bacteriophages induced from Erwinia tasmaniensis strains.

    Science.gov (United States)

    Müller, Ina; Lurz, Rudi; Geider, Klaus

    2012-07-25

    Mitomycin C treatment of Erwinia tasmaniensis strains from Australia induced prophages and the expression of bacteriocins. The bacteriocin named tasmancin inhibited E. tasmaniensis strains from South Africa and Germany. A gene cluster with a klebicin-related operon and an immunity protein was detected on plasmid pET46 from E. tasmaniensis strain Et1/99. PCR reactions using primers directed to this region produced signals for several strains originating from Australia, but not for strains isolated in South Africa and Germany. The latter isolates lacked plasmid pET46. Bacteriophages were induced from E. tasmaniensis strains Et88 and Et14/99, both isolates from South-Eastern Australia. These phages formed plaques on several other strains from this region, as well as on E. tasmaniensis strains from South Africa and Germany. Sequencing revealed similarity of phages ϕEt88 and ϕEt14, which shared the host range on E. tasmaniensis strains. Bacteriophages and tasmancin may interfere with the viability of several related E. tasmaniensis strains in the environment of carrier strains.

  10. Novel somatic hybrids (Solanum tuberosum L.+Solanum tarnii) and their fertile BC1 progenies express extreme resistance to potato virus Y and late blight.

    Science.gov (United States)

    Thieme, Ramona; Rakosy-Tican, Elena; Gavrilenko, Tatjana; Antonova, Olga; Schubert, Jörg; Nachtigall, Marion; Heimbach, Udo; Thieme, Thomas

    2008-03-01

    Solanum tarnii, a wild diploid, tuber-bearing Mexican species belonging to the series Pinnatisecta is highly resistant to Potato virus Y (PVY) and Colorado potato beetle and shows a strong hypersensitive reaction to Phytophthora infestans. Therefore, it could be a potential source of resistance to pathogens for potato breeders. S. tarnii (2n=2x=24) is reproductively isolated from tetraploid Solanum tuberosum and hence difficult to include in potato breeding programmes. In this study, interspecific somatic hybrids were produced for the first time by protoplast electrofusion of the cells of potato cv. Delikat (Solanum tuberosum L.) and Solanum tarnii. The hybrid nature of the regenerants was confirmed by simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers and by morphological analysis and flow cytometry. Selected somatic hybrids were successfully backcrossed with cv. Delikat. Parental lines, primary somatic hybrids and BC1 progeny were assessed for resistance to PVY by mechanical inoculation, grafting and exposure to viruliferous aphid vectors in the field, and resistance to late blight (P. infestans) by detached leaflet and whole tuber tests. The somatic hybrids showed no symptoms of viral infection and most of them displayed high levels of resistance to foliage blight. The BC1 progenies were highly resistant to PVY and a few were resistant to foliage blight. Selected hybrids and BC1 clones were evaluated in the field for tuber quality and tuber yield. Some BC1 clones produced yields of good quality tubers. The results confirm that both the resistance to PVY and to late blight of S. tarnii is expressed in somatic hybrids, and PVY resistance is transferred to BC1 progeny, whereas blight resistance is harder to transfer. Somatic hybridization again proved to be a valuable tool for producing pre-breeding material with increased genetic diversity.

  11. Interaction between two invasive organisms on the European chestnut: does the chestnut blight fungus benefit from the presence of the gall wasp?

    Science.gov (United States)

    Meyer, Joana B; Gallien, Laure; Prospero, Simone

    2015-11-01

    The impact of invasive fungal pathogens and pests on trees is often studied individually, thereby omitting possible interactions. In this study the ecological interaction between the chestnut blight fungus Cryphonectria parasitica and the chestnut gall wasp Dryocosmus kuriphilus was investigated. We determined if abandoned galls could be colonized by C. parasitica and thereby act as an entry point and a source of pathogen inoculum. Moreover we assessed the identity and diversity of other gall-colonizing fungal species. A total of 1973 galls were randomly sampled from 200 chestnut trees in eight Swiss stands. In a stand C. parasitica was isolated from 0.4-19.2% of the galls. The incidence of C. parasitica on the galls and the fungal diversity significantly increased with the residence time of D. kuriphilus in a stand. All but one C. parasitica cultures were virulent. The predominant fungus isolated from galls was Gnomoniopsis castanea whose abundance influenced negatively that of C. parasitica. This study shows that D. kuriphilus galls can be colonized by virulent strains of the chestnut blight fungus C. parasitica. This can have effects on the chestnut blight incidence even in chestnut stands where the disease is successfully controlled by hypovirulence. The gall wasp presence influences also the fungal species composition on chestnut trees.

  12. Halogenated furanones from the red alga, Delisea pulchra, inhibit carbapenem antibiotic synthesis and exoenzyme virulence factor production in the phytopathogen Erwinia carotovora

    DEFF Research Database (Denmark)

    Manefield, M.; Welch, M.; Givskov, Michael Christian

    2001-01-01

    The plant pathogen Erwinia carotovora regulates expression of virulence factors and antibiotic production via an N-3- oxohexanoyl-L-homoserine lactone (3-oxo-C6-HSL) dependent quorum sensing mechanism. The marine alga Delisea pulchra produces halogenated furanones known to antagonise 3-oxo-C6-HSL...... activity. We have tested the effects of a halogenated furanone on the production of carbapenem, cellulase and protease in E. carotovora. Despite differences in the regulatory mechanisms controlling carbapenem and exoenzyme production each was inhibited by the algal metabolite. We present evidence...... to suggest that the furanone dependent inhibition of carbapenem production is a result of the disruption of the 3-oxo-C6-HSL dependent expression of the carABCDEFGH operon....

  13. 黄秋葵疫病的发生与防治%Occurrence and control of blight disease of Abelmoschus esculentus

    Institute of Scientific and Technical Information of China (English)

    李瑞美

    2015-01-01

    黄秋葵疫病是危害黄秋葵的真菌病之一,发病严重时会导致黄秋葵产量和品质降低。该文综述了黄秋葵疫病的症状、病原、发生规律,并总结了防治措施。%Blight disease is one of the fungus diseases in Abelmoschus esculentus,the occurrence of which would cause seri-ous yield and quality decrease of Abelmoschus esculentus. This paper described the symptom,pathogen and occurrence regu-larity for blight disease of Abelmoschus esculentus,and control measures was summarized.

  14. Can physiology help us to combat late blight in potato?

    NARCIS (Netherlands)

    Struik, P.C.

    2010-01-01

    Late blight is a devastating disease in potato production world-wide. Breeding for resistance is complex because of the versatile and aggressive population of Phytophthora infestans, which overcomes any new genetic source of resistance very rapidly. There are reliable fungicides available to control

  15. Exploring Fusarium head blight disease control by RNA interference

    Science.gov (United States)

    RNA interference (RNAi) technology provides a novel tool to study gene function and plant protection strategies. Fusarium graminearum is the causal agent of Fusarium head blight (FHB), which reduces crop yield and quality by producing trichothecene mycotoxins including 3-acetyl deoxynivalenol (3-ADO...

  16. Blighted Spaces and the Politics of Everyday Life

    Directory of Open Access Journals (Sweden)

    2003-11-01

    Full Text Available While a great deal is known about the demographic and historical trends that shape the built environment of American cities, much less is known about the politics of everyday life among residents who continue to live in postindustrial neighborhoods. This study seeks to compensate for the current gaps in academic research by conducting spatially informed ethnography in a North Philadelphia community. Specifically, the study will explore the issue of urban "blight" from a cultural geography perspective, primarily by looking at the ways in which "blighted" spaces shape everyday life, and everyday life in turn shapes and produces the spatial environment. In response to these concerns, my study poses the questions: What would it mean to focus on the ways in which human agency, imagination, and subjectivity are shaped by "blighted" geographical locations? What would it mean to pay ethnographic attention to how subjects in given historical conditions are shaped by "blighted" spaces, as well as how they respond to these spaces in culturally specific ways? By incorporating critical interdisciplinary approaches, this study offers a new way of looking at the various practices of daily life - including flexible, informal economic activities and post-welfare related "lifestyles" of resistance. Through the lens of spatial ethnography, the study seeks to elucidate the ways in which postindustrial space interacts with culture, poverty and addiction; as well as the ways in which users continue to appropriate postindustrial spaces in culturally meaningful ways under the aegis of the semi-welfare state.

  17. Towards Managing Stemphylium Blight of Lentil in the Pacific Northwest

    Science.gov (United States)

    Stemphylium blight of lentil, caused by the fungus Stemphylium botryosum, has recently emerged as a disease problem in the Pacific Northwest, particularly on the recently released lentil cultivar ‘Morena’. The first step toward managing the disease is to correctly identify early signs of the diseas...

  18. Identification of an emergent bacterial blight of garlic in Brazil

    Science.gov (United States)

    Outbreaks of a bacterial blight disease occurred on garlic (Allium sativum) cultivars Roxo Caxiense, Quiteria and Cacador in Southern Brazil, and threatened the main production regions of Rio Grande do Sul State. Symptoms were characterized by watersoaked reddish streaks along the leaf midrib, follo...

  19. Expression of the dspA/E gene of Erwinia amylovora in non-host plant Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Hasan Murat Aksoy

    2017-01-01

    Full Text Available In the Erwinia amylovora genome, the hrp gene cluster containing the dspA/E/EB/F operon plays a crucial role in mediating the pathogenicity and the hypersensitive response (HR in the host plant. The role of the dspA/E gene derived from E. amylovora was investigated by monitoring the expression of the β-glucuronidase (GUS reporter system in transgenic Arabidopsis thaliana cv. Pri-Gus seedlings. A mutant ΔdspA/E strain of E. amylovora was generated to contain a deletion of the dspA/E gene for the purpose of this study. Two-week-old seedlings of GUS transgenic Arabidopsis were vacuum-infiltrated with the wild-type and the mutant (ΔdspA/E E. amylovora strains. The Arabidopsis seedlings were fixed and stained for GUS activity after 3–5 days following infiltration. The appearance of dense spots with blue staining on the Arabidopsis leaves indicated the typical characteristic of GUS activity. This observation indicated that the wild-type E. amylovora strain had induced a successful and efficient infection on the A. thaliana Pri-Gus leaves. In contrast, there was no visible GUS expression on leaf tissues which were inoculated with the ΔdspA/E mutant E. amylovora strain. These results indicate that the dspA/E gene is required by the bacterial cells to induce HR in non-host plants.

  20. SecG is required for antibiotic activities of Pseudomonas sp. YL23 against Erwinia amylovora and Dickeya chrysanthemi.

    Science.gov (United States)

    Liu, Youzhou; Baird, Sonya M; Qiao, Junqing; Du, Yan; Lu, Shi-En

    2015-05-01

    Strain YL23 was isolated from soybean root tips and identified to be Pseudomonas sp. This strain showed broad-spectrum antibacterial activity against bacterial pathogens that are economically important in agriculture. To characterize the genes dedicated to antibacterial activities against microbial phytopathogens, a Tn5-mutation library of YL23 was constructed. Plate bioassays revealed that the mutant YL23-93 lost its antibacterial activities against Erwinia amylovora and Dickeya chrysanthemi as compared with its wild type strain. Genetic and sequencing analyses localized the transposon in a homolog of the secG gene in the mutant YL23-93. Constitutive expression plasmid pUCP26-secG was constructed and electroporated into the mutant YL23-93. Introduction of the plasmid pUCP26-secG restored antibacterial activities of the mutant YL23-93 to E. amylovora and D. chrysanthemi. As expected, empty plasmid pUCP26 could not complement the phenotype of the antibacterial activity in the mutant. Thus the secG gene, belonging to the Sec protein translocation system, is required for antibacterial activity of strain YL23 against E. amylovora and D. chrysanthemi.

  1. Morphological and biochemical characterization of Erwinia amylovora-induced hypersensitive cell death in apple leaves

    NARCIS (Netherlands)

    Iakimova, E.T.; Sobiczewski, P.; Michalczuk, L.; Wegrzynowicz-Lesiak, E.; Mikicinski, A.; Woltering, E.J.

    2013-01-01

    In attached apple leaves, spot-inoculated with Erwinia amylovora, the phenotypic appearance of the hypersensitive response (HR) and the participation of ethylene, reactive oxygen species (ROS) and of vacuolar processing enzyme (VPE) (a plant caspase-1-like protease) were analysed. The HR in both the

  2. Plasmid content of Erwinia amylovora in orchards in Washington and Oregon

    Science.gov (United States)

    We examined the plasmid content of a collection of 305 isolates of Erwinia amylovora from Washington and Oregon in the Pacific Northwest of the United States with PCR assays and RFLP. Nearly all isolates of E. amylovora carried plasmid pEA29, which is not found in other species of bacteria, but 4% ...

  3. Eerste jaar Erwinia-project legt topje van de ijsberg bloot

    NARCIS (Netherlands)

    Velvis, H.; Wolf, van der J.M.

    2006-01-01

    Over de herkomst van de Erwinia bacterie heerst nog altijd veel onduidelijkheid. Daarom is een onderzoek naar deze bacterie gestart. In vier jaar tijd worden diverse aardappelrassen onderzocht in de verschillende stadia van teelt en opslag. Op deze manier hoopt men te achterhalen waar de herkomst va

  4. The presence and survival of soft rot (Erwinia) in flower bulb production systems

    NARCIS (Netherlands)

    Doorn, van J.; Vreeburg, P.J.M.; Leeuwen, van P.J.; Dees, R.H.L.

    2011-01-01

    Soft rot is causing increasing damage in the flower bulb industry. Bulbous ornamentals such as Hyacinthus, Dahlia, Iris, Muscari, Freesia and Zantedeschia can be infected. Soft rot in flower bulbs is mainly caused by Dickeya spp. (Dickeya spp.) and Erwinia carotovora subsp. carotovora (Pectobacteriu

  5. L-asparaginase treatment in acute lymphoblastic leukemia: a focus on Erwinia asparaginase

    Science.gov (United States)

    Pieters, Rob; Hunger, Stephen P; Boos, Joachim; Rizzari, Carmelo; Silverman, Lewis; Baruchel, Andre; Goekbuget, Nicola; Schrappe, Martin; Pui, Ching-Hon

    2010-01-01

    Asparaginases are a cornerstone of treatment protocols for acute lymphoblastic leukemia (ALL) and are used for remission induction and intensification treatment in all pediatric regimens and in the majority of adult protocols. Extensive clinical data have shown that intensive asparaginase treatment improves clinical outcomes in childhood ALL. Three asparaginase preparations are available; the native asparaginase derived from Escherichia coli (E. coli-asparaginase), a pegylated form of this enzyme (PEG-asparaginase) and a product isolated from Erwinia chrysanthemi, i.e. Erwinia asparaginase. Clinical hypersensitivity reactions and silent inactivation due to antibodies against E.coli-asparaginase, lead to inactivation of E-Coli asparaginase in up to 60% of cases. Current treatment protocols include E. coli-asparaginase or PEG-asparaginase for first-line treatment of ALL. Typically, patients exhibiting sensitivity to one formulation of asparaginase are switched to another product to ensure they receive the most efficacious treatment regimen possible. Erwinia asparaginase is used as a second- or third-line treatment in European and US protocols. Despite the universal inclusion of asparaginase in such treatment protocols, there is much debate regarding the optimal formulation and dosage of these agents. This manuscript provides an overview of available evidence to make recommendations for optimal use of Erwinia asparaginase in the treatment of ALL. PMID:20824725

  6. Bacterial leaf rot of Aloe vera L., caused byErwinia chrysanthemi biovar 3

    NARCIS (Netherlands)

    Laat, de P.C.A.; Verhoeven, J.T.W.; Danse, J.D.

    1994-01-01

    A severe attack of the bacteriumErwinia chrysantemi biovar 3 on the succulentAloe vera on the Carribean island of Aruba is described. Biochemical and pathological characteristics of strains are presented, including results of successful inoculation experiments onAloe vera. This is the first report o

  7. Evaluation of a PCR kit for the detection of Erwinia carotovora subsp. atroseptica on potato tubers

    NARCIS (Netherlands)

    Frechon, D.; Exbrayat, P.; Helias, V.; Hyman, L.J.; Jouan, B.; Llop, P.; Lopez, M.M.; Payet, N.; Perombelon, M.C.M.; Toth, I.K.; Beckhoven, van J.R.C.M.; Wolf, van der J.M.; Bertheau, Y.

    1998-01-01

    A PCR-based kit, Probelia(TM), for the detection of Erwinia carotovora subsp. atroseptica (Eca) on potatoes was evaluated at five laboratories in four countries. The kit is based on DNA-specific PCR amplification followed by detection of amplicons by hybridization to a peroxidase-labelled DNA probe

  8. AmyR is a novel negative regulator of amylovoran production in Erwinia amylovora

    Science.gov (United States)

    We have previously reported the characterization of an orphan gene ybjN from Escherichia coli. In this study, we attempted to understand the role of amyR in Erwinia amylovora, a functionally conserved homolog of E. coli ybjN. As reported earlier, amylovoran production in the amyR knockout mutant is ...

  9. L-asparaginase treatment in acute lymphoblastic leukemia: a focus on Erwinia asparaginase.

    Science.gov (United States)

    Pieters, Rob; Hunger, Stephen P; Boos, Joachim; Rizzari, Carmelo; Silverman, Lewis; Baruchel, Andre; Goekbuget, Nicola; Schrappe, Martin; Pui, Ching-Hon

    2011-01-15

    Asparaginases are a cornerstone of treatment protocols for acute lymphoblastic leukemia (ALL) and are used for remission induction and intensification treatment in all pediatric regimens and in the majority of adult treatment protocols. Extensive clinical data have shown that intensive asparaginase treatment improves clinical outcomes in childhood ALL. Three asparaginase preparations are available: the native asparaginase derived from Escherichia coli (E. coli asparaginase), a pegylated form of this enzyme (PEG-asparaginase), and a product isolated from Erwinia chrysanthemi, ie, Erwinia asparaginase. Clinical hypersensitivity reactions and silent inactivation due to antibodies against E. coli asparaginase, lead to inactivation of E. coli asparaginase in up to 60% of cases. Current treatment protocols include E. coli asparaginase or PEG-asparaginase for first-line treatment of ALL. Typically, patients exhibiting sensitivity to one formulation of asparaginase are switched to another to ensure they receive the most efficacious treatment regimen possible. Erwinia asparaginase is used as a second- or third-line treatment in European and US protocols. Despite the universal inclusion of asparaginase in such treatment protocols, debate on the optimal formulation and dosage of these agents continues. This article provides an overview of available evidence for optimal use of Erwinia asparaginase in the treatment of ALL.

  10. Alterations in Kernel Proteome after Infection with Fusarium culmorum in Two Triticale Cultivars with Contrasting Resistance to Fusarium Head Blight

    Science.gov (United States)

    Perlikowski, Dawid; Wiśniewska, Halina; Kaczmarek, Joanna; Góral, Tomasz; Ochodzki, Piotr; Kwiatek, Michał; Majka, Maciej; Augustyniak, Adam; Kosmala, Arkadiusz

    2016-01-01

    Highlight: The level of pathogen alpha-amylase and plant beta-amylase activities could be components of plant-pathogen interaction associated with the resistance of triticale to Fusarium head blight. Triticale was used here as a model to recognize new components of molecular mechanism of resistance to Fusarium head blight (FHB) in cereals. Fusarium-damaged kernels (FDK) of two lines distinct in levels of resistance to FHB were applied into a proteome profiling using two-dimensional gel electrophoresis (2-DE) to create protein maps and mass spectrometry (MS) to identify the proteins differentially accumulated between the analyzed lines. This proteomic research was supported by a measurement of alpha- and beta-amylase activities, mycotoxin content, and fungal biomass in the analyzed kernels. The 2-DE analysis indicated a total of 23 spots with clear differences in a protein content between the more resistant and more susceptible triticale lines after infection with Fusarium culmorum. A majority of the proteins were involved in a cell carbohydrate metabolism, stressing the importance of this protein group in a plant response to Fusarium infection. The increased accumulation levels of different isoforms of plant beta-amylase were observed for a more susceptible triticale line after inoculation but these were not supported by a total level of beta-amylase activity, showing the highest value in the control conditions. The more resistant line was characterized by a higher abundance of alpha-amylase inhibitor CM2 subunit and simultaneously a lower activity of alpha-amylase after inoculation. We suggest that the level of pathogen alpha-amylase and plant beta-amylase activities could be components of plant-pathogen interaction associated with the resistance of triticale to FHB. PMID:27582751

  11. Alterations in Kernel Proteome after Infection with Fusarium culmorum in Two Triticale Cultivars with Contrasting Resistance to Fusarium Head Blight.

    Science.gov (United States)

    Perlikowski, Dawid; Wiśniewska, Halina; Kaczmarek, Joanna; Góral, Tomasz; Ochodzki, Piotr; Kwiatek, Michał; Majka, Maciej; Augustyniak, Adam; Kosmala, Arkadiusz

    2016-01-01

    Highlight: The level of pathogen alpha-amylase and plant beta-amylase activities could be components of plant-pathogen interaction associated with the resistance of triticale to Fusarium head blight. Triticale was used here as a model to recognize new components of molecular mechanism of resistance to Fusarium head blight (FHB) in cereals. Fusarium-damaged kernels (FDK) of two lines distinct in levels of resistance to FHB were applied into a proteome profiling using two-dimensional gel electrophoresis (2-DE) to create protein maps and mass spectrometry (MS) to identify the proteins differentially accumulated between the analyzed lines. This proteomic research was supported by a measurement of alpha- and beta-amylase activities, mycotoxin content, and fungal biomass in the analyzed kernels. The 2-DE analysis indicated a total of 23 spots with clear differences in a protein content between the more resistant and more susceptible triticale lines after infection with Fusarium culmorum. A majority of the proteins were involved in a cell carbohydrate metabolism, stressing the importance of this protein group in a plant response to Fusarium infection. The increased accumulation levels of different isoforms of plant beta-amylase were observed for a more susceptible triticale line after inoculation but these were not supported by a total level of beta-amylase activity, showing the highest value in the control conditions. The more resistant line was characterized by a higher abundance of alpha-amylase inhibitor CM2 subunit and simultaneously a lower activity of alpha-amylase after inoculation. We suggest that the level of pathogen alpha-amylase and plant beta-amylase activities could be components of plant-pathogen interaction associated with the resistance of triticale to FHB.

  12. Cutting propagation of azaleas using hot water treatments to control pathogens

    Science.gov (United States)

    Azalea web blight, caused by certain binucleate species of Rhizoctonia, occurs yearly on some azalea cultivars during nursery production in the southern and eastern U.S. Azalea shoots collected for cutting propagation can harbor the pathogen, thus allowing the disease to be perpetuated during the cu...

  13. Phytophthora andina sp nov., a newly identified heterothallic pathogen of solanaceous hosts in the Andean highlands

    NARCIS (Netherlands)

    Oliva, R.F.; Kroon, L.P.N.M.; Chacon, G.; Flier, W.G.; Ristaino, J.B.; Forbes, G.A.

    2010-01-01

    A blight disease on fruits and foliage of wild and cultivated Solanum spp. was found to be associated with a new species of Phytophthora. The proposed novel species is named Phytophthora andina Adler & Flier, sp. nov. based on morphological characteristics, pathogenicity assays, mitochondrial DN

  14. Occurrence of Xanthomonas axonopodis pv. phaseoli, the causal agent of common bacterial blight disease, on seeds of common bean (Phaseolus vulgaris L.) in upper Egypt.

    Science.gov (United States)

    Abd-Alla, M H; Bashandy, S R; Schnell, S

    2010-01-01

    Common bean seed lots collected from different seed dealers and Malawii agriculture station were screened for the presence of Xanthomonas axonopodis pv. phaseoli. In the laboratory the pathogen was isolated following the routine laboratory assay method, i.e. direct plating method using yeast extract-dextrose-calcium carbonate agar medium (YDC). Yellow, convex, mucoid colonies of Xanthomonas were consistently isolated on YDC from seed samples. The presumptive pathogen was confirmed by isolation on semiselective medium, such as mTBM and MD5A. Further, the pathogen was confirmed by biochemical, physiological and, finally, the pathogenicity tests. Five samples out of seven were positive for Xanthomonas. The isolates were found to cause common blight of 3-week-old common bean plants by 7 d after inoculation. Bacteria with the same characteristics as those inoculated were re-isolated from the infected plants.

  15. Partial resistance to Erwinia carotovora SUBSP. carotovora and plant vigour among F1 hybrids of Zantedeschia cultivars

    NARCIS (Netherlands)

    Snijder, R.C.; Tuyl, van J.M.

    2004-01-01

    The potential of breeding Zantedeschia cultivars for resistance to soft rot caused by Erwinia carotovora subsp. carotovora (syn. Pectobacterium carotovorum subsp. carotovorum) was determined. Hybrids of six cultivars (`Back Magic`, Galaxy`, Pink Persuasion`, Sensation`, `Treasure` and `Florex Gold`)

  16. 进境韩国兰花细菌性褐腐病菌的分离与鉴定%Isolation and Identification of Erwinia cypripedii from Imported Korea Cymbidium

    Institute of Scientific and Technical Information of China (English)

    厉艳; 王英超; 尼秀媚; 甘琴华; 封立平

    2012-01-01

    [目的]鉴定进境韩国兰花细菌性褐腐病菌.[方法]从韩国进境的大花蕙兰植株病变叶片中分离到细菌菌株,并通过形态鉴定、培养特征、生理生化及16S rDNA序列分析和致病性测定对其进行了鉴定.[结果]确认该病菌为兰花细菌性褐腐病菌(Erwinia cypripedii),这是我国首次从进境兰花中检出该病害.[结论]为我国兰花细菌性褐腐病菌的预防及控制奠定了基础.%The aim was to identify Erwinia cypripedii from imported Korea Cymbidium. [ Method] The pathogenic bacteria was i-solated from imported Korea Cymbidium leaves, and then it was identified by morphological identification, cultural characteristics, physiological and biochemical reactions, 16S rDNA gene sequences analysis and pathogenicity test. [Result] The isolated strain was identified as E. cypripedii, and it was the first interception in China. [ Conclusion ] The research result lays the foundation for the prevention and control of E. cypripedii in China.

  17. Teratogenicity studies on late blighted potatoes in nonhuman primates (Macaca mulatta and Saguinus labiatus).

    Science.gov (United States)

    Allen, J R; Marlar, R J; Chesney, C F; Helgeson, J P; Kelman, A; Weckel, G; Traisman, E; White, J W

    1977-02-01

    Female rhesus monkeys and marmosets were fed a diet containing blighted potatoes (Phytophthora infestans) at a level of 10g/kg per day for at least two weeks prior to breeding and six weeks following conception in order to gain additional information on the association of blighted potatoes and the development of anencephaly and spina bifida in primate species. There was an absence of either of these neural-tube defects in 32 rhesus and 14 marmoset infants whose mothers had received a blighted potato diet. In addition there were no cranial osseous defects. There were, however, two rhesus monkey infants with internal hydrocephalus whose mothers had consumed blighted potatoes.

  18. Changing Pattern of Crop Fraction in Late Blight Induced Potato Crops in Potato Bowl of West Bengal by using Multi-temporal Time Series AWiFs Data

    Science.gov (United States)

    Chakrabarty, Abhisek

    2016-07-01

    Crop fraction is the ratio of crop occupying a unit area in ground pixel, is very important for monitoring crop growth. One of the most important variables in crop growth monitoring is the fraction of available solar radiation intercepted by foliage. Late blight of potato (Solanum tuberosum), caused by the oomycete pathogen Phytophthora infestans, is considered to be the most destructive crop diseases of potato worldwide. Under favourable climatic conditions, and without intervention (i.e. fungicide sprays), the disease can destroy potato crop within few weeks. Therefore it is important to evaluate the crop fraction for monitoring the healthy and late blight affected potato crops. This study was conducted in potato bowl of West Bengal, which consists of districts of Hooghly, Howrah, Burdwan, Bankuara, and Paschim Medinipur. In this study different crop fraction estimation method like linear spectral un-mixing, Normalized difference vegetation index (NDVI) based DPM model (Zhang et al. 2013), Ratio vegetation index based DPM model, improved Pixel Dichotomy Model (Li et al. 2014) ware evaluated using multi-temporal IRS AWiFs data in two successive potato growing season of 2012-13 and 2013-14 over the study area and compared with measured crop fraction. The comparative study based on measured healthy and late blight affected potato crop fraction showed that improved Pixel Dichotomy Model maintain the high coefficient of determination (R2= 0.835) with low root mean square error (RMSE=0.21) whereas the correlation values of NDVI based DPM model and RVI based DPM model is 0.763 and 0.694 respectively. The changing pattern of crop fraction profile of late blight affected potato crop was studied in respect of healthy potato crop fraction which was extracted from the 269 GPS points of potato field. It showed that the healthy potato crop fraction profile maintained the normal phenological trend whereas the late blight affected potato crop fraction profile suddenly fallen

  19. Nucleotide diversity analysis of three major bacterial blight resistance genes in rice.

    Directory of Open Access Journals (Sweden)

    Waikhom Bimolata

    Full Text Available Nucleotide sequence polymorphisms among R gene alleles influence the process of co-evolutionary interaction between host and pathogen by shaping the response of host plants towards invading pathogens. Here, we present the DNA sequence polymorphisms and diversities present among natural alleles of three rice bacterial blight resistance genes, Xa21, Xa26 and xa5. The diversity was examined across different wild relatives and cultivars of Oryza species. Functional significance of selected alleles was evaluated through semi-quantitative reverse transcription polymerase chain reaction and real time PCR. The greatest nucleotide diversity and singleton variable sites (SVS were present in Xa26 (π = 0.01958; SVS = 182 followed by xa5 and Xa21 alleles. The highest frequency of single nucleotide polymorphisms were observed in Xa21 alleles and least in xa5. Transition bias was observed in all the genes and 'G' to 'A' transitions were more favored than other form of transitions. Neutrality tests failed to show the presence of selection at these loci, though negative Tajima's D values indicate the presence of a rare form of polymorphisms. At the interspecies level, O. nivara exhibited more diversity than O. sativa. We have also identified two nearly identical resistant alleles of xa5 and two sequentially identical alleles of Xa21. The alleles of xa5 showed basal levels of expression while Xa21 alleles were functionally not expressed.

  20. Reassessment of QTLs for late blight resistance in the tomato accession L3708 using a restriction site associated DNA (RAD) linkage map and highly aggressive isolates of Phytophthora infestans.

    Science.gov (United States)

    Chen, Ai-Lin; Liu, Chu-Yin; Chen, Chien-Hua; Wang, Jaw-Fen; Liao, Yu-Chen; Chang, Chia-Hui; Tsai, Mong-Hsun; Hwu, Kae-Kang; Chen, Kai-Yi

    2014-01-01

    Tomato late blight caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary is a major threat to tomato production in cool and wet environments. Intensified outbreaks of late blight have been observed globally from the 1980s, and are associated with migration of new and more aggressive populations of P. infestans in the field. The objective of this study was to reassess late blight resistance in the wild tomato accession L3708 (Solanum pimpinellifolium L.) against pathogens of different aggressiveness. An F2:3 genetic mapping population was developed using L3708 as the paternal parent. Two isolates of P. infestans, Pi39A and Pi733, were used for inoculation. Pi733 is a highly aggressive genotype that defeats three known late blight resistance genes, Ph-1, Ph-2, and Ph-5t in tomato. In contrast, Pi39A is a less aggressive genotype that defeats only Ph-1. Restriction site Associated DNA Sequencing (RAD-Seq) technology was used to massively sequence 90 bp nucleotides adjacent to both sides of PstI restriction enzyme cutting sites in the genome for all individuals in the genetic mapping population. The RAD-seq data were used to construct a genetic linkage map containing 440 single nucleotide polymorphism markers. Quantitative trait locus (QTL) analysis identified a new disease-resistant QTL specific to Pi733 on chromosome 2. The Ph-3 gene located on chromosome 9 could be detected whichever isolates were used. This study demonstrated the feasibility and efficiency of RAD-Seq technology for conducting a QTL mapping experiment using an F2:3 mapping population, which allowed the identification of a new late blight resistant QTL in tomato.

  1. Reassessment of QTLs for Late Blight Resistance in the Tomato Accession L3708 Using a Restriction Site Associated DNA (RAD) Linkage Map and Highly Aggressive Isolates of Phytophthora infestans

    Science.gov (United States)

    Chen, Ai-Lin; Liu, Chu-Yin; Chen, Chien-Hua; Wang, Jaw-Fen; Liao, Yu-Chen; Chang, Chia-Hui; Tsai, Mong-Hsun; Hwu, Kae-Kang; Chen, Kai-Yi

    2014-01-01

    Tomato late blight caused by the oomycete pathogen Phytophthora infestans (Mont.) de Bary is a major threat to tomato production in cool and wet environments. Intensified outbreaks of late blight have been observed globally from the 1980s, and are associated with migration of new and more aggressive populations of P. infestans in the field. The objective of this study was to reassess late blight resistance in the wild tomato accession L3708 (Solanum pimpinellifolium L.) against pathogens of different aggressiveness. An F2:3 genetic mapping population was developed using L3708 as the paternal parent. Two isolates of P. infestans, Pi39A and Pi733, were used for inoculation. Pi733 is a highly aggressive genotype that defeats three known late blight resistance genes, Ph-1, Ph-2, and Ph-5t in tomato. In contrast, Pi39A is a less aggressive genotype that defeats only Ph-1. Restriction site Associated DNA Sequencing (RAD-Seq) technology was used to massively sequence 90 bp nucleotides adjacent to both sides of PstI restriction enzyme cutting sites in the genome for all individuals in the genetic mapping population. The RAD-seq data were used to construct a genetic linkage map containing 440 single nucleotide polymorphism markers. Quantitative trait locus (QTL) analysis identified a new disease-resistant QTL specific to Pi733 on chromosome 2. The Ph-3 gene located on chromosome 9 could be detected whichever isolates were used. This study demonstrated the feasibility and efficiency of RAD-Seq technology for conducting a QTL mapping experiment using an F2:3 mapping population, which allowed the identification of a new late blight resistant QTL in tomato. PMID:24788810

  2. Epidemiology and integrated control of potato late blight in Europe

    DEFF Research Database (Denmark)

    Cooke, L R; Schepers, H T A M; Hermansen, A

    2011-01-01

    in NW Europe and a table of the specific attributes of the most important fungicides in Europe are presented. The development and use of decision support systems (DSSs) in NW Europe are described. In The Netherlands, it is estimated that almost 40% of potato growers use recommendations based...... 20 years. The relative importance of the different primary inoculum sources and specific measures for reducing their role, such as covering dumps with plastic and preventing seed tubers from becoming infected, is described for the different regions. In NW Europe, varieties with greater resistance...... tend not to be grown on a large scale. From the grower’s perspective, the savings in fungicide input that can be achieved with these varieties are not compensated by the higher (perceived) risk of blight. Fungicides play a crucial role in the integrated control of late blight. The spray strategies...

  3. Thiamine primed defense provides reliable alternative to systemic fungicide carbendazim against sheath blight disease in rice (Oryza sativa L.).

    Science.gov (United States)

    Bahuguna, Rajeev Nayan; Joshi, Rohit; Shukla, Alok; Pandey, Mayank; Kumar, J

    2012-08-01

    A novel pathogen defense strategy by thiamine priming was evaluated for its efficacy against sheath blight pathogen, Rhizoctonia solani AG-1A, of rice and compared with that of systemic fungicide, carbendazim (BCM). Seeds of semidwarf, high yielding, basmati rice variety Vasumati were treated with thiamine (50 mM) and BCM (4 mM). The pot cultured plants were challenge inoculated with R. solani after 40 days of sowing and effect of thiamine and BCM on rice growth and yield traits was examined. Higher hydrogen peroxide content, total phenolics accumulation, phenylalanine ammonia lyase (PAL) activity and superoxide dismutase (SOD) activity under thiamine treatment displayed elevated level of systemic resistance, which was further augmented under challenging pathogen infection. High transcript level of phenylalanine ammonia lyase (PAL) and manganese superoxide dismutase (MnSOD) validated mode of thiamine primed defense. Though minimum disease severity was observed under BCM treatment, thiamine produced comparable results, with 18.12 per cent lower efficacy. Along with fortifying defense components and minor influence on photosynthetic pigments and nitrate reductase (NR) activity, thiamine treatment significantly reduced pathogen-induced loss in photosynthesis, stomatal conductance, chlorophyll fluorescence, NR activity and NR transcript level. Physiological traits affected under pathogen infection were found signatory for characterizing plant's response under disease and were detectable at early stage of infection. These findings provide a novel paradigm for developing alternative, environmentally safe strategies to control plant diseases.

  4. The Erwinia amylovora PhoPQ system is involved in resistance to antimicrobial peptide and suppresses gene expression of two novel type III secretion systems.

    Science.gov (United States)

    Nakka, Sridevi; Qi, Mingsheng; Zhao, Youfu

    2010-10-20

    The PhoPQ system is a pleiotropic two-component signal transduction system that controls many pathogenic properties in several mammalian and plant pathogens. Three different cues have been demonstrated to activate the PhoPQ system including a mild acidic pH, antimicrobial peptides, and low Mg(2+). In this study, our results showed that phoPQ mutants were more resistant to strong acidic conditions (pH 4.5 or 5) than that of the wild-type (WT) strain, suggesting that this system in Erwinia amylovora may negatively regulate acid resistance gene expression. Furthermore, the PhoPQ system negatively regulated gene expression of two novel type III secretion systems in E. amylovora. These results are in contrast to those reported for the PhoPQ system in Salmonella and Xanthomonas, where it positively regulates type III secretion system and acid resistance. In addition, survival of phoPQ mutants was about 10-fold lower than that of WT when treated with cecropin A at pH 5.5, suggesting that the PhoPQ system renders the pathogen more resistant to cecropin A.

  5. Spatial Analysis of Phytophthora infestans Genotypes and Late Blight Severity on Tomato and Potato in the Del Fuerte Valley Using Geostatistics and Geographic Information Systems.

    Science.gov (United States)

    Jaime-Garcia, R; Orum, T V; Felix-Gastelum, R; Trinidad-Correa, R; Vanetten, H D; Nelson, M R

    2001-12-01

    ABSTRACT Genetic structure of Phytophthora infestans, the causal agent of potato and tomato late blight, was analyzed spatially in a mixed potato and tomato production area in the Del Fuerte Valley, Sinaloa, Mexico. Isolates of P. infestans were characterized by mating type, allozyme analysis at the glucose-6-phosphate isomerase and peptidase loci, restriction fragment length polymorphism with probe RG57, metalaxyl sensitivity, and aggressiveness to tomato and potato. Spatial patterns of P. infestans genotypes were analyzed by geographical information systems and geo-statistics during the seasons of 1994-95, 1995-96, and 1996-97. Spatial analysis of the genetic structure of P. infestans indicates that geographic substructuring of this pathogen occurs in this area. Maps displaying the probabilities of occurrence of mating types and genotypes of P. infestans, and of disease severity at a regional scale, were presented. Some genotypes that exhibited differences in epidemiologically important features such as metalaxyl sensitivity and aggressiveness to tomato and potato had a restricted spread and were localized in isolated areas. Analysis of late blight severity showed recurring patterns, such as the earliest onset of the disease in the area where both potato and tomato were growing, strengthening the hypothesis that infected potato tubers are the main source of primary inoculum. The information that geostatistical analysis provides might help improve management programs for late blight in the Del Fuerte Valley.

  6. Research Progress on Northern Leaf Blight in Corn

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yingnan; WANG Zhenhua

    2009-01-01

    The northern corn leaf blight is one of the most serious diseases in maize production. The research progress on etiology, generation law and control strategy, antigen identification, resistance mechanism and inheritance of this disease was discussed. And the research work which should be enhanced in China was pointed out, such as mechanism of resistance inheritance, developing function marker, gene mining, screening resistance resource and dominant physiological race in different areas.

  7. Resistance of Antimicrobial Peptide Gene Transgenic Rice to Bacterial Blight

    Institute of Scientific and Technical Information of China (English)

    WANG Wei; WU Chao; LIU Mei; LIU Xu-ri; Hu Guo-cheng; SI Hua-min; SUN Zong-xiu; LIU Wen-zhen; Fu Ya-ping

    2011-01-01

    Antimierobial peptide is a polypeptide with antimicrobial activity.Antimicrobial peptide genes Np3 and Np5 from Chinese shrimp (Fenneropenaeus Chinensis) were integrated into Oryza sativa L.subsp.japonica cv.Aichi ashahi by Agrobacterium mediated transformation system.PCR analysis showed that the positive ratios of Np3 and Np5 were 36% and 45% in T0 generation,respectively.RT-PCR analysis showed that the antimicrobial peptide genes were expressed in T1 generation,and there was no obvious difference in agronomic traits between transgenic plants and non-transgenic plants.Four Np3 and Np5 transgenic lines in T1 generation were inoculated with ×anthomonas oryzae pv.oryzae strain CR4,and all the four transgenic lines had significantly enhanced resistance to bacterial blight caused by the strain CR4.The Np5 transgenic lines also showed higher resistance to bacterial blight caused by strains JS97-2,Zhe 173 and OS-225.It is suggested that transgenic lines with Np5 gene might possess broad spectrum resistance to rice bacterial blight.

  8. Primary study on the resistance to bacterial blight (X. oryzae) in Cecropin B gene transgenic rices

    Institute of Scientific and Technical Information of China (English)

    HUAZhihua; HUANGDanian; XUERui; WANGXiaoling; GAOZhenya

    1998-01-01

    Bacterial blight (BB) is one of the major diseases to rice. Antibacterial Cecropin B gene has been cloned and transformed into rice. We studied the resistance to bacterial blight in Cecropin B gene tronsgenic rices.

  9. Systems level analysis of two-component signal transduction systems in Erwinia amylovora: Role in virulence, regulation of amylovoran biosynthesis and swarming motility

    Directory of Open Access Journals (Sweden)

    Sundin George W

    2009-05-01

    Full Text Available Abstract Background Two-component signal transduction systems (TCSTs, consisting of a histidine kinase (HK and a response regulator (RR, represent a major paradigm for signal transduction in prokaryotes. TCSTs play critical roles in sensing and responding to environmental conditions, and in bacterial pathogenesis. Most TCSTs in Erwinia amylovora have either not been identified or have not yet been studied. Results We used a systems approach to identify TCST and related signal transduction genes in the genome of E. amylovora. Comparative genomic analysis of TCSTs indicated that E. amylovora TCSTs were closely related to those of Erwinia tasmaniensis, a saprophytic enterobacterium isolated from apple flowers, and to other enterobacteria. Forty-six TCST genes in E. amylovora including 17 sensor kinases, three hybrid kinases, 20 DNA- or ligand-binding RRs, four RRs with enzymatic output domain (EAL-GGDEF proteins, and two kinases were characterized in this study. A systematic TCST gene-knockout experiment was conducted, generating a total of 59 single-, double-, and triple-mutants. Virulence assays revealed that five of these mutants were non-pathogenic on immature pear fruits. Results from phenotypic characterization and gene expression experiments indicated that several groups of TCST systems in E. amylovora control amylovoran biosynthesis, one of two major virulence factors in E. amylovora. Both negative and positive regulators of amylovoran biosynthesis were identified, indicating a complex network may control this important feature of pathogenesis. Positive (non-motile, EnvZ/OmpR, negative (hypermotile, GrrS/GrrA, and intermediate regulators for swarming motility in E. amylovora were also identified. Conclusion Our results demonstrated that TCSTs in E. amylovora played major roles in virulence on immature pear fruit and in regulating amylovoran biosynthesis and swarming motility. This suggested presence of regulatory networks governing

  10. Phenazine-1-Carboxylic Acid Production by Pseudomonas fluorescens LBUM636 Alters Phytophthora infestans Growth and Late Blight Development.

    Science.gov (United States)

    Morrison, Christopher K; Arseneault, Tanya; Novinscak, Amy; Filion, Martin

    2017-03-01

    Phytophthora infestans causes late blight of potato, one of the most devastating diseases affecting potato production. Alternative approaches for controlling late blight are being increasingly sought due to increasing environmental concerns over the use of chemical pesticides and the increasing resistance of P. infestans to fungicides. Our research group has isolated a new strain of Pseudomonas fluorescens (LBUM636) of biocontrol interest producing the antibiotic phenazine-1-carboxylic acid (PCA). Wild-type LBUM636 was shown to significantly inhibit the growth of Phytophthora infestans in in vitro confrontational assays whereas its isogenic mutant (phzC-; not producing PCA) only slightly altered the pathogen's growth. Wild-type LBUM636 but not the phzC- mutant also completely repressed disease symptom development on tubers. A pot experiment revealed that wild-type LBUM636 can significantly reduce P. infestans populations in the rhizosphere and in the roots of potato plants, as well as reduce in planta disease symptoms due to PCA production. The expression of eight common plant defense-related genes (ChtA, PR-1b, PR-2, PR-5, LOX, PIN2, PAL-2, and ERF3) was quantified in tubers, roots, and leaves by reverse-transcription quantitative polymerase chain reaction and revealed that the biocontrol observed was not associated with the induction of a plant defense response by LBUM636. Instead, a direct interaction between P. infestans and LBUM636 is required and PCA production appears to be a key factor for LBUM636's biocontrol ability.

  11. Survey for incidence and severity of bacterial blight of cotton caused by Xanthomonas axonopodis pv. malvacearum in different districts of Marathwada region

    Directory of Open Access Journals (Sweden)

    D. Utpal

    2012-07-01

    Full Text Available An extensive roving survey was conducted in different districts of Marathwada region of Maharashtra State to isolate the pathogen associated with the bacterial blight disease of cotton. In all 76 cotton fields were surveyed and average disease incidence (PI to the tune of 51.12 per cent has been observed. Highest disease incidence noticed in Parbhani district (67% followed by Hingoli (63%, Nanded (58% and Latur (54%. The lowest disease incidence noticed in Jalna district (36%. Highest disease severity noticed in Parbhani district followed by Hingoli, Latur, Nanded and Aurangabad.

  12. Erwinia endophytica sp. nov., isolated from potato (Solanum tuberosum L.) stems.

    Science.gov (United States)

    Ramírez-Bahena, Martha Helena; Salazar, Sergio; Cuesta, Maria José; Tejedor, Carmen; Igual, Jose Mariano; Fernández-Pascual, Mercedes; Peix, Alvaro

    2015-12-04

    We analysed through a polyphasic taxonomy approach two bacterial strains coded BSTT30T and BSTT40, isolated in the course of a study of endophytic bacteria occurring in stems and roots of potato growing in a soil from Salamanca, Spain. The 16S rRNA gene sequence was identical in both strains and had 98.4% identity with respect to the closest relatives Erwinia tasmaniensis Et1/99T and E. rhapontici ATCC29283T and the following closest related species with 98.2 % similarity were E. billingiae E63T and E. toletana A37T, for which the strains were classified within genus Erwinia. The analysis of housekeeping genes gpd, gyrB and rpoD confirmed their phylogenetic affiliation and showed identities lower than 90% in all cases with respect to the mentioned closest relatives. The respiratory quinone is Q8. The major fatty acids are C16:0, C16:1 7c/ 16:1 6c in summed feature 3 and C18:1 7c/ 18:2 6,9c in summed feature 8. Oxidase negative and catalase positive. Glucose is fermented without gas production. Arginine dihydrolase, urease and indole production are negative. It can grow at 35ºC and at pH 10. The DNA G+C content was 50.1 mol %. DNA-DNA hybridization results showed values lower than 29% relatedness with respect to the type strains of the four closest related species. Therefore, the combined results of genotypic, phenotypic and chemotaxonomic data support the classification of strains BSTT30T and BSTT40 into a novel species of Erwinia, for which the name Erwinia endophytica sp. nov. is proposed. The type strain is BSTT30T (=LMG 28457T, CECT 8692T).

  13. Estimation of resistance pear cultivars to Erwinia amylovora using artificial immature pear fruits method

    OpenAIRE

    Gavrilović, Veljko; Stanisavljević, Rade; Stošić, Stefan; Stevanović, Miloš; Aleksić, Goran; Stajić, Milica; Dolovac, Nenad

    2014-01-01

    Susceptibility of different pear cultivars to Erwinia amaylovora by artificial inoculated immature pear fruits are shown in this article. According obtained results significant differences among cultivars are confirmed and they could be divided in four groups. Most susceptibly cultivars were Santa Marija. Second group includes Williams, Morettini, Carmen, Hardenpont. As most resistant shown to be Magness, Turandot and two local varietyies Karamanka, as well as another unknown local cultivar. ...

  14. Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached stems

    Science.gov (United States)

    : Botryosphaeria stem blight is a destructive disease of blueberries that has not been well managed with fungicides. Field observations showed that stem blight is more severe on vigorously growing plants than on slower growing plants. Detached stem assays were used to compare the effect of fertil...

  15. Late blight-resistant tuber-bearing Solanum species in field and laboratory trials

    Science.gov (United States)

    Late blight, caused by Phytophthora infestans, is the most disastrous and widespread disease of potato. One of the most effective means of controlling late blight is through the use of resistant cultivars, but newly developed resistant cultivars often lose their resistance after a few years of comm...

  16. Late blight (Phytophthora infestans occurring on stems - a new problem in potato crops

    Directory of Open Access Journals (Sweden)

    Józef Kapsa

    2013-12-01

    Full Text Available In recent years changes in the occurrence of the first potato late blight (Phytophthora infestans symptoms have been noted. Observations of potato crops have showed that occurrence of the blight symptoms is sometimes on the stem instead on the leaves. The aim of the study carried out in 1995-2001 was to determine occurrence and harmfulness of the stem late blight infections. Survey of many potato crops (490 potato fields made in 1997-2001, around Poland enabled assessment of the incidence of stem blight. Average 69,1% of observed crops were affected with stem blight. The stem blight incidence was not connected with the rate of the leaf form of late blight developing on the foliage. Stem form of the disease has appeared more often in the years with less rainfall during June and July. Its occurrence was influenced by micro climate inside potato canopy. Glasshouse experiments confirmed the importance of stem lesions in decreasing tuber yield (11,2-42,9% and increasing tuber infections. Results have shown that tubers contaminated with spores were the least probable source of the stem form of late blight.

  17. Survival potential of Phytophthora infestans in relation to environmental factors and late blight occurrence

    Science.gov (United States)

    Potato is an important crop globally and late blight (Phytophthora infestans) often results in severe crop loss. The cost for late blight control can be in excess of $210 million in the United States. We utilized a non-parametric density distribution analysis of local temperature (Temp) and relative...

  18. Response of germinating barley seeds to Fusarium graminearum: The first molecular insight into Fusarium seedling blight

    DEFF Research Database (Denmark)

    Yang, Fen; Svensson, Birte; Finnie, Christine

    2011-01-01

    Fusarium seedling blight in cereals can result in significant reductions in plant establishment but has not received much attention. The disease often starts during seed germination due to sowing of the seeds infected by Fusarium spp. including Fusarium graminearum. In order to gain the first...... provides the first molecular insight into Fusarium seedling blight....

  19. Sustainable control of pea bacterial blight : approaches for durable genetic resistance and biocontrol by endophytic bacteria

    NARCIS (Netherlands)

    Elvira-Recuenco, M.

    2000-01-01

    Key-words: bacterial blight, biological control, biodiversity, endophytic bacteria, L-form, pea, PDRl retrotransposon, Pisum sativum, Pisum abyssinicum, Pseudomonas syringae pv. pisi, race specific resistance, race non-specific resistance, Spanish landraces.Pea bacterial blight (Pseudom

  20. Effect of nitrogen fertilization and fungicides on Botryosphaeria stem blight lesion development on detached blueberry stems

    Science.gov (United States)

    Botryosphaeria stem blight is a destructive disease of blueberries. Field observations indicate stem blight is more severe on vigorous plants than on slower growing plants. Two studies compared the effect of two types of fertilizers applied at four rates and nine fungicides on lesion development fo...

  1. Analysing potato late blight control as a social-ecological system using fuzzy cognitive mapping

    NARCIS (Netherlands)

    Pacilly, Francine C.A.; Groot, Jeroen C.J.; Hofstede, Gert Jan; Schaap, Ben F.; Lammerts van Bueren, Edith

    2016-01-01

    Potato late blight, caused by Phytophthora infestans, is one of the main diseases in potato production, causing major losses in yield. Applying environmentally harmful fungicides is the prevailing and classical method for controlling late blight, thus contaminating food and water. There is theref

  2. Candidate fire blight resistance genes in Malus identified with the use of genomic tools and approaches

    Science.gov (United States)

    The goal of this research is to utilize current advances in Rosaceae genomics to identify DNA markers for use in marker-assisted selection of durable resistance to fire blight. Candidate fire blight resistance genes were selected and ranked based upon differential expression after inoculation with ...

  3. 'Candidatus Erwinia dacicola', a coevolved symbiotic bacterium of the olive fly Bactrocera oleae (Gmelin).

    Science.gov (United States)

    Capuzzo, Caterina; Firrao, Giuseppe; Mazzon, Luca; Squartini, Andrea; Girolami, Vincenzo

    2005-07-01

    The taxonomic identity of the hereditary prokaryotic symbiont of the olive fly Bactrocera oleae (Diptera: Tephritidae) was investigated. In order to avoid superficial microbial contaminants and loosely associated saprophytic biota, flies were surface-sterilized at the larval stage and reared under aseptic conditions until adult emergence. B. oleae flies originating from different geographical locations and collected at different times of the year were tested. Bacterial isolation was undertaken from the cephalic oesophageal bulb, which is known to be a specific site of accumulation for the hosted microsymbionts in the adult insect. Despite evidence of multiplication cycles taking place within the insect, attempts at cultivation of the isolated bacteria ex situ were not productive at any stage, leading to the choice of unculturable status definition. PCR amplification and nucleotide sequencing of the entire 16S rRNA gene consistently yielded a single sequence that displayed marked similarity with enterobacterial lineages, with closest matches (97%) to Erwinia persicina and Erwinia rhapontici. The novel taxon differs from common intestinal bacterial species of fruit flies and from instances of culturable bacteria previously described in B. oleae raised without sterility precautions, which we also observed as minority occupants or occasional contaminants. The symbiont's identity is also distinct from Pseudomonas savastanoi. In all observations, the numerically dominant inhabitant of the olive fly oesophageal organ was the same unculturable organism, whose presence at later stages was also regularly observed in the midgut. A novel species is proposed, by virtue of its unique properties, under the designation 'Candidatus Erwinia dacicola'.

  4. Plant Growth Promotion and Suppression of Bacterial Leaf Blight in Rice by Inoculated Bacteria.

    Science.gov (United States)

    Yasmin, Sumera; Zaka, Abha; Imran, Asma; Zahid, Muhammad Awais; Yousaf, Sumaira; Rasul, Ghulam; Arif, Muhammad; Mirza, Muhammad Sajjad

    2016-01-01

    The present study was conducted to evaluate the potential of rice rhizosphere associated antagonistic bacteria for growth promotion and disease suppression of bacterial leaf blight (BLB). A total of 811 rhizospheric bacteria were isolated and screened against 3 prevalent strains of BLB pathogen Xanthomonas oryzae pv. oryzae (Xoo) of which five antagonistic bacteria, i.e., Pseudomonas spp. E227, E233, Rh323, Serratia sp. Rh269 and Bacillus sp. Rh219 showed antagonistic potential (zone of inhibition 1-19 mm). Production of siderophores was found to be the common biocontrol determinant and all the strains solubilized inorganic phosphate (82-116 μg mL-1) and produced indole acetic acid (0.48-1.85 mg L-1) in vitro. All antagonistic bacteria were non-pathogenic to rice, and their co-inoculation significantly improved plant health in terms of reduced diseased leaf area (80%), improved shoot length (31%), root length (41%) and plant dry weight (60%) as compared to infected control plants. Furthermore, under pathogen pressure, bacterial inoculation resulted in increased activity of defense related enzymes including phenylalanine ammonia-lyase and polyphenol oxidase, along with 86% increase in peroxidase and 53% increase in catalase enzyme activities in plants inoculated with Pseudomonas sp. Rh323 as well as co-inoculated plants. Bacterial strains showed good colonization potential in the rice rhizosphere up to 21 days after seed inoculation. Application of bacterial consortia in the field resulted in an increase of 31% in grain yield and 10% in straw yield over non-inoculated plots. Although, yield increase was statistically non-significant but was accomplished with overall saving of 20% chemical fertilizers. The study showed that Pseudomonas sp. Rh323 can be used to develop dual-purpose inoculum which can serve not only to suppress BLB but also to promote plant growth in rice.

  5. Constitutive expression of the xylanase inhibitor TAXI-III delays Fusarium head blight symptoms in durum wheat transgenic plants.

    Science.gov (United States)

    Moscetti, Ilaria; Tundo, Silvio; Janni, Michela; Sella, Luca; Gazzetti, Katia; Tauzin, Alexandra; Giardina, Thierry; Masci, Stefania; Favaron, Francesco; D'Ovidio, Renato

    2013-12-01

    Cereals contain xylanase inhibitor (XI) proteins which inhibit microbial xylanases and are considered part of the defense mechanisms to counteract microbial pathogens. Nevertheless, in planta evidence for this role has not been reported yet. Therefore, we produced a number of transgenic plants constitutively overexpressing TAXI-III, a member of the TAXI type XI that is induced by pathogen infection. Results showed that TAXI-III endows the transgenic wheat with new inhibition capacities. We also showed that TAXI-III is correctly secreted into the apoplast and possesses the expected inhibition parameters against microbial xylanases. The new inhibition properties of the transgenic plants correlate with a significant delay of Fusarium head blight disease symptoms caused by Fusarium graminearum but do not significantly influence leaf spot symptoms caused by Bipolaris sorokiniana. We showed that this contrasting result can be due to the different capacity of TAXI-III to inhibit the xylanase activity of these two fungal pathogens. These results provide, for the first time, clear evidence in planta that XI are involved in plant defense against fungal pathogens and show the potential to manipulate TAXI-III accumulation to improve wheat resistance against F. graminearum.

  6. Alternative sigma factor RpoN and its modulation protein YhbH are indispensable for Erwinia amylovora virulence.

    Science.gov (United States)

    Ancona, Veronica; Li, Wenting; Zhao, Youfu

    2014-01-01

    In Erwinia amylovora, ECF (extracytoplasmic functions) alternative sigma factor HrpL regulates the transcription of hrp (hypersensitive response and pathogenicity)-type III secretion system (T3SS) genes by binding to a consensus sequence known as the hrp box in hrp gene promoters. In turn, the expression of hrpL has been proposed to be positively controlled by alternative sigma factor 54 (σ(54)) (RpoN) and HrpS, a member of the σ(54) enhancer-binding proteins (EBPs). However, the function of RpoN has not been characterized genetically in E. amylovora. In this study, we investigated the role of RpoN, a nitrogen limitation sigma factor, and its modulation protein YhbH, a novel ribosome-associated protein, in E. amylovora virulence. Our results showed that mutations in hrpS, hrpL, rpoN and yhbH, but not yfiA and rmf3, resulted in a nonpathogenic phenotype on immature pear fruits and apple shoots. Consistently, the expression of T3SS genes, including hrpL, dspE, hrpN and hrpA, was barely detected in hrpS, hrpL, rpoN and yhbH mutants. These mutants were also not capable of eliciting a hypersensitive response (HR) on tobacco; however, the overexpression of hrpL using an inducible promoter rescued the HR-eliciting abilities of these mutants. These results suggest that a sigma factor cascade exists in the regulatory networks of E. amylovora and regulates important virulence factors. On the basis of this study and previously reported data, a model is proposed for the regulation of T3SS in E. amylovora.

  7. ANTIBACTERIAL ACTIVITY OF THREE MEDICINAL PLANTS OF KUMAUN HIMALAYA AGAINST SOME PATHOGENIC BACTERIA

    Directory of Open Access Journals (Sweden)

    S. C. SATI

    2015-11-01

    Full Text Available The antibacterial property of methanol, ethanol and hexane extracts of Berberis aristata, Chenopodium ambrosioides and Tinospora cordifolia grown in Kumaun Himalayan were investigated against some pathogenic gram positive and gram negative bacterial strains (Bacillus subtilis, Agrobacterium tumefaciens, Escherichia coli, Xanthomonas phaseoli and Erwinia chrysanthemi using disc diffusion method. Methanol extract of B. aristata was found with highest inhibitory activity against E. chrysanthemi (ZOI, 11±0.3mm. Whereas lowest inhibition was recorded in ethanolic extract of B. aristata against E. coli. The hexane extract of B. aristata and methanolic extract of C. ambrosioides were found totally inactive against all the pathogens tested.

  8. Five Reasons to Consider Phytophthora infestans a Reemerging Pathogen.

    Science.gov (United States)

    Fry, W E; Birch, P R J; Judelson, H S; Grünwald, N J; Danies, G; Everts, K L; Gevens, A J; Gugino, B K; Johnson, D A; Johnson, S B; McGrath, M T; Myers, K L; Ristaino, J B; Roberts, P D; Secor, G; Smart, C D

    2015-07-01

    Phytophthora infestans has been a named pathogen for well over 150 years and yet it continues to "emerge", with thousands of articles published each year on it and the late blight disease that it causes. This review explores five attributes of this oomycete pathogen that maintain this constant attention. First, the historical tragedy associated with this disease (Irish potato famine) causes many people to be fascinated with the pathogen. Current technology now enables investigators to answer some questions of historical significance. Second, the devastation caused by the pathogen continues to appear in surprising new locations or with surprising new intensity. Third, populations of P. infestans worldwide are in flux, with changes that have major implications to disease management. Fourth, the genomics revolution has enabled investigators to make tremendous progress in terms of understanding the molecular biology (especially the pathogenicity) of P. infestans. Fifth, there remain many compelling unanswered questions.

  9. Epidemiological study of hazelnut bacterial blight in central Italy by using laboratory analysis and geostatistics.

    Directory of Open Access Journals (Sweden)

    Jay Ram Lamichhane

    Full Text Available Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012. The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1% to very high (almost 75% across the orchards. Young plants (4-year old were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.

  10. A Phytophthora infestans RXLR effector targets plant PP1c isoforms that promote late blight disease.

    Science.gov (United States)

    Boevink, Petra C; Wang, Xiaodan; McLellan, Hazel; He, Qin; Naqvi, Shaista; Armstrong, Miles R; Zhang, Wei; Hein, Ingo; Gilroy, Eleanor M; Tian, Zhendong; Birch, Paul R J

    2016-01-29

    Plant pathogens deliver effectors to alter host processes. Knowledge of how effectors target and manipulate host proteins is critical to understand crop disease. Here, we show that in planta expression of the RXLR effector Pi04314 enhances leaf colonization by Phytophthora infestans via activity in the host nucleus and attenuates induction of jasmonic and salicylic acid-responsive genes. Pi04314 interacts with three host protein phosphatase 1 catalytic (PP1c) isoforms, causing their re-localization from the nucleolus to the nucleoplasm. Re-localization of PP1c-1 also occurs during infection and is dependent on an R/KVxF motif in the effector. Silencing the PP1c isoforms or overexpression of a phosphatase-dead PP1c-1 mutant attenuates infection, demonstrating that host PP1c activity is required for disease. Moreover, expression of PP1c-1mut abolishes enhanced leaf colonization mediated by in planta Pi04314 expression. We argue that PP1c isoforms are susceptibility factors forming holoenzymes with Pi04314 to promote late blight disease.

  11. Altered Gene Expression Profiles of Wheat Genotypes against Fusarium Head Blight

    Directory of Open Access Journals (Sweden)

    Ayumi Kosaka

    2015-02-01

    Full Text Available Fusarium graminearum is responsible for Fusarium head blight (FHB, which is a destructive disease of wheat that makes its quality unsuitable for end use. To understand the temporal molecular response against this pathogen, microarray gene expression analysis was carried out at two time points on three wheat genotypes, the spikes of which were infected by Fusarium graminearum. The greatest number of genes was upregulated in Nobeokabouzu-komugi followed by Sumai 3, whereas the minimum expression in Gamenya was at three days after inoculation (dai. In Nobeokabouzu-komugi, high expression of detoxification genes, such as multidrug-resistant protein, multidrug resistance-associated protein, UDP-glycosyltransferase and ABC transporters, in addition to systemic defense-related genes, were identified at the early stage of infection. This early response of the highly-resistant genotype implies a different resistance response from the other resistant genotype, Sumai 3, primarily containing local defense-related genes, such as cell wall defense genes. In Gamenya, the expression of all three functional groups was minimal. The differences in these molecular responses with respect to the time points confirmed the variation in the genotypes. For the first time, we report the nature of gene expression in the FHB-highly resistant cv. Nobeokabouzu-komugi during the disease establishment stage and the possible underlying molecular response.

  12. Epidemiological study of hazelnut bacterial blight in central Italy by using laboratory analysis and geostatistics.

    Science.gov (United States)

    Lamichhane, Jay Ram; Fabi, Alfredo; Ridolfi, Roberto; Varvaro, Leonardo

    2013-01-01

    Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.

  13. Functional analysis of a wheat pleiotropic drug resistance gene involved in Fusarium head blight resistance

    Institute of Scientific and Technical Information of China (English)

    WANG Gui-ping; KONG Ling-rang; HOU Wen-qian; ZHANG Lei; WU Hong-yan; ZHAO Lan-fei; DU Xu-ye; MA Xin; LI An-fei; WANG Hong-wei

    2016-01-01

    The pleiotropic drug resistance (PDR) sub-family of adenosine triphosphate (ATP)-binding cassette (ABC) transporter had been reported to participate in diverse biological processes of plant. In this study, we cloned three novelPDR genes in Fusarium head blight (FHB) resistant wheat cultivar Ning 7840, which were located on wheat chromosomes 6A, 6B and 6D. In phylogeny, these genes were members of cluster I together with AePDR7 andBdPDR7. Subcelular localization analysis showed thatTaPDR7 was expressed on the plasmalemma. The quantitative real time PCR (RT-PCR) analysis showed that this gene and its probable orthologues in chromosomes 6B and 6D were both up-regulated sharply at 48 h after infected byFusarium graminearum and trichothecene deoxynivalenol (DON) in spike. When knocking down the transcripts of alTaPDR7 members by barely stripe mosaic virus-induced gene silencing (BSMV-VIGS) system, it could promote the F. graminearum hyphae growth and made larger pathogen inoculation points in Ning 7840, which suggested that TaPDR7 might play an important role in response toF. graminearum. Although salicylic acid (SA), methyl jasmonate (MeJA) and abscisic acid (ABA) had been reported to possibly regulate wheat FHB resistance, here, we found that the three members ofTaPDR7 were negatively regulated by these three hormones but positively regulated by indoleacetic acid (IAA).

  14. Resistance Evaluation to Sheath Blight in Transgenic Rice Lines

    Institute of Scientific and Technical Information of China (English)

    LI Ai-hong; XU Xin-ping; DAI Zheng-yuan; CHEN Zong-xiang; LI Bao-jian; ZHANG Hong-xi; PAN Xue-biao

    2004-01-01

    Resistance of forty-one homozygous rice lines transformed with chitinase gene (RC24) and β-1,3 -glucanse gene (β-1,3-Glu) to sheath blight was analyzed by inoculation. Among different lines, the resistance had significant differences according to the result by cluster analysis. The lines could be categorized into resistant, moderately resistant, moderately susceptible and susceptible types, while 92.1% of which belonging to moderately resistant or moderately susceptible type. For different resistant or susceptible lines, the resistance to rice sheath blight was remarkable correlated with the chitinase activity of transgenic lines except resistant type lines, in which enzyme activity coded by target gene was lower than moderately resistant type. The chitinase activity of transgenic lines tested at different time after inoculation or different organs of the same plant was uniform, which suggested that the expression of chitinase gene was constitutive in nature. Check varieties' chitinase activity would change at different time after inoculation and reach a peak at sometime, but it had no difference at various parts of the same plant.

  15. Resistance Evaluation to Sheath Blight in Transgenic Rice Lines

    Institute of Scientific and Technical Information of China (English)

    LIAi-hong; XuXin-ping; DAIZheng-yuan; CHENZong-xiang; LIBao-jian; ZHANGHong-xi; PANXue-biao

    2004-01-01

    Resistance of forty one homozygous rice lines transformed with chitinase gene (RC24) and β-1,3-glucanse gene (β-1,3-Glu) to sheath blight was analyzed by inoculation. Among different lines, the resistance had significant differences according to the result by cluster analysis. The lines could be categorized into resistant, moderately resistant, moderately susceptible and susceptible typcs, while 92.1% of which belonging to moderately resistant or moderately susceptible type. For different resistant or susceptible lines, the resistance to rice sheath blight was remarkable correlated with the chitinase activity of transgenic lines except resistant type lines, in which enzyme activity coded by target gene was lower than moderately resistant type. The chitinase activity of transgenic lines tested at different time after inoculation or different organs of the same plant was uniform, which suggested that the expression of chitinase gene was constitutive in nature. Check varieties' chitinase acdvity would change at different time after inoculation and reach a peak at sometime, but it had no difference at various parts of the same plant.

  16. Rapid and sensitive detection of Phytophthora colocasiae responsible for the taro leaf blight using conventional and real-time PCR assay.

    Science.gov (United States)

    Nath, Vishnu S; Hegde, Vinayaka M; Jeeva, Muthulekshmi L; Misra, Raj S; Veena, Syamala S; Raj, Mithun; Unnikrishnan, Suresh K; Darveekaran, Sree S

    2014-03-01

    Conventional and real-time PCR assays were developed for sensitive and specific detection of Phytophthora colocasiae, an oomycete pathogen that causes leaf blight and corm rot of taro. A set of three primer pairs was designed from regions of the RAS-related protein (Ypt1), G protein alpha-subunit (GPA1) and phospho-ribosylanthranilate isomerase (TRP1) genes. In conventional PCR, the lower limit of detection was 50 pg DNA, whereas in real-time PCR, the detection limit was 12.5 fg for the primer based on Ypt1 gene. The cycle threshold values were linearly correlated with the concentration of the target DNA (range of R(2) = 0.911-0.999). All the primer sets were successful in detecting P. colocasie from naturally infected leaves and tubers of taro. Phytophthora colocasiae was detected from artificially infested samples after 18 and 15 h of postinoculation in conventional and real-time PCR assay, respectively. The developed PCR assay proved to be a robust and reliable technique to detect P. colocasiae in taro planting material and for assessing the distribution of pathogen within fields, thus aid in mitigating taro leaf blight.

  17. Arabidopsis late blight: infection of a nonhost plant by Albugo laibachii enables full colonization by Phytophthora infestans.

    Science.gov (United States)

    Belhaj, Khaoula; Cano, Liliana M; Prince, David C; Kemen, Ariane; Yoshida, Kentaro; Dagdas, Yasin F; Etherington, Graham J; Schoonbeek, Henk-Jan; van Esse, H Peter; Jones, Jonathan D G; Kamoun, Sophien; Schornack, Sebastian

    2017-01-01

    The oomycete pathogen Phytophthora infestans causes potato late blight, and as a potato and tomato specialist pathogen, is seemingly poorly adapted to infect plants outside the Solanaceae. Here, we report the unexpected finding that P. infestans can infect Arabidopsis thaliana when another oomycete pathogen, Albugo laibachii, has colonized the host plant. The behaviour and speed of P. infestans infection in Arabidopsis pre-infected with A. laibachii resemble P. infestans infection of susceptible potato plants. Transcriptional profiling of P. infestans genes during infection revealed a significant overlap in the sets of secreted-protein genes that are induced in P. infestans upon colonization of potato and susceptible Arabidopsis, suggesting major similarities in P. infestans gene expression dynamics on the two plant species. Furthermore, we found haustoria of A. laibachii and P. infestans within the same Arabidopsis cells. This Arabidopsis-A. laibachii-P. infestans tripartite interaction opens up various possibilities to dissect the molecular mechanisms of P. infestans infection and the processes occurring in co-infected Arabidopsis cells.

  18. Physiology and biochemistry of a lignin degrading bacterium Erwinia sp. Cu 3614

    Energy Technology Data Exchange (ETDEWEB)

    Rajan, J.S.

    1992-01-01

    Previous researchers have reported the isolation of a diphenylether cleaving organism, Erwinia sp., using an enrichment medium containing lignin. A copper and dinitrophenol resistant mutant of this organism, Erwinia sp. Cu3614, has also been reported. To assess the effect of copper on the growth and biochemistry of this organism, continuous cultivation was used employing an apparently optimized medium containing ethanol as carbon source. Upon increasing the concentration of copper sulfate in the medium from 5 [mu]g/ml to 10 [mu]g/ml increases in maximum specific growth rate and growth yield were seen. Also decrease in the values for doubling time and the coefficient for maintenance energy were seen. At higher levels of copper sulfate a [open quotes]non competitive[close quotes] inhibition of growth was seen as indicated by the values calculated for substrate affinity constant, and inhibition constant. To assess this organism's ligninolytic ability, an assay for residual lignin was developed. The assay measured a reaction between diazotized sulfanilic acid and lignin in alkaline solution by spectrophotometric monitoring of the resulting adduct. Use of this technique indicated that Erwinia sp. Cu3614 could degrade up to 80% of lignin in batch cultures. Further evidence about the ligninolytic ability of this organism was provided by examination of electron micrographs of lignocellulosic substrates incubated with cell suspensions. An assay for monitoring diphenylether cleaving abilities was also developed using resazurin, a redox dye. In vivo assays with cells obtained from continuous culture studies indicated a linear relationship between the rates of reaction with resazurin and the amount of copper associated with cells. In vitro assays, employing cell free extracts and resazurin, were used to obtain a fraction enriched in diphenylether cleaving activity by a heat treatment procedure.

  19. Erwinia asparaginase achieves therapeutic activity after pegaspargase allergy: a report from the Children's Oncology Group.

    Science.gov (United States)

    Salzer, Wanda L; Asselin, Barbara; Supko, Jeffrey G; Devidas, Meenakshi; Kaiser, Nicole A; Plourde, Paul; Winick, Naomi J; Reaman, Gregory H; Raetz, Elizabeth; Carroll, William L; Hunger, Stephen P

    2013-07-25

    AALL07P2 evaluated whether substitution of Erwinia asparaginase 25000 IU/m(2) for 6 doses given intramuscularly Monday/Wednesday/Friday (M/W/F) to children and young adults with acute lymphoblastic leukemia and clinical allergy to pegaspargase would provide a 48-hour nadir serum asparaginase activity (NSAA) ≥ 0.10 IU/mL. AALL07P2 enrolled 55 eligible/evaluable patients. NSAA ≥ 0.1 IU/mL was achieved in 38 of 41 patients (92.7%) with acceptable samples 48 hours and in 38 of 43 patients (88.4%) 72 hours after dosing during course 1. Among samples obtained during all courses, 95.8% (252 of 263) of 48-hour samples and 84.5% (125 of 148) of 72-hour samples had NSAA ≥ 0.10-IU/mL. Pharmacokinetic parameters were estimated by fitting the serum asparaginase activity-time course for all 6 doses given during course 1 to a 1-compartment open model with first order absorption. Erwinia asparaginase administered with this schedule achieved therapeutic NSAA at both 48 and 72 hours and was well tolerated with no reports of hemorrhage, thrombosis, or death, and few cases of grade 2 to 3 allergic reaction (n = 6), grade 1 to 3 hyperglycemia (n = 6), or grade 1 pancreatitis (n = 1). Following allergy to pegaspargase, Erwinia asparaginase 25000 IU/m(2) × 6 intramuscularly M/W/F can be substituted for a single dose of pegaspargase.

  20. Comparison of the transcriptomes of American chestnut (Castanea dentata and Chinese chestnut (Castanea mollissima in response to the chestnut blight infection

    Directory of Open Access Journals (Sweden)

    Wheeler Nicholas

    2009-05-01

    Full Text Available Abstract Background1471-2229-9-51 American chestnut (Castanea dentata was devastated by an exotic pathogen in the beginning of the twentieth century. This chestnut blight is caused by Cryphonectria parasitica, a fungus that infects stem tissues and kills the trees by girdling them. Because of the great economic and ecological value of this species, significant efforts have been made over the century to combat this disease, but it wasn't until recently that a focused genomics approach was initiated. Prior to the Genomic Tool Development for the Fagaceae project, genomic resources available in public databases for this species were limited to a few hundred ESTs. To identify genes involved in resistance to C. parasitica, we have sequenced the transcriptome from fungal infected and healthy stem tissues collected from blight-sensitive American chestnut and blight-resistant Chinese chestnut (Castanea mollissima trees using ultra high throughput pyrosequencing. Results We produced over a million 454 reads, totaling over 250 million bp, from which we generated 40,039 and 28,890 unigenes in total from C. mollissima and C. dentata respectively. The functions of the unigenes, from GO annotation, cover a diverse set of molecular functions and biological processes, among which we identified a large number of genes associated with resistance to stresses and response to biotic stimuli. In silico expression analyses showed that many of the stress response unigenes were expressed more in canker tissues versus healthy stem tissues in both American and Chinese chestnut. Comparative analysis also identified genes belonging to different pathways of plant defense against biotic stresses that are differentially expressed in either American or Chinese chestnut canker tissues. Conclusion Our study resulted in the identification of a large set of cDNA unigenes from American chestnut and Chinese chestnut. The ESTs and unigenes from this study constitute an important

  1. Homology-based modeling of the Erwinia amylovora type III secretion chaperone DspF used to identify amino acids required for virulence and interaction with the effector DspE.

    Science.gov (United States)

    Triplett, Lindsay R; Wedemeyer, William J; Sundin, George W

    2010-09-01

    The structure of DspF, a type III secretion system (T3SS) chaperone required for virulence of the fruit tree pathogen Erwinia amylovora, was modeled based on predicted structural homology to characterized T3SS chaperones. This model guided the selection of 11 amino acid residues that were individually mutated to alanine via site-directed mutagenesis. Each mutant was assessed for its effect on virulence complementation, dimerization and interaction with the N-terminal chaperone-binding site of DspE. Four amino acid residues were identified that did not complement the virulence defect of a dspF knockout mutant, and three of these residues were required for interaction with the N-terminus of DspE. This study supports the significance of the predicted beta-sheet helix-binding groove in DspF chaperone function.

  2. Evaluation of the BlightPro Decision Support System for Management of Potato Late Blight Using Computer Simulation and Field Validation.

    Science.gov (United States)

    Small, Ian M; Joseph, Laura; Fry, William E

    2015-12-01

    The objective of this study was to evaluate the utility of the BlightPro decision support system (DSS) for late blight management using computer simulation and field tests. Three fungicide schedules were evaluated: (i) calendar-based (weekly) applications, (ii) applications according to the DSS, or (iii) no fungicide. Simulation experiments utilized 14 years of weather data from 59 locations in potato-producing states. In situations with unfavorable weather for late blight, the DSS recommended fewer fungicide applications with no loss of disease suppression; and, in situations of very favorable weather for late blight, the DSS recommended more fungicide applications but with improved disease suppression. Field evaluation was conducted in 2010, 2011, 2012, and 2013. All experiments involved at least two cultivars with different levels of resistance. DSS-guided and weekly scheduled fungicide treatments were successful at protecting against late blight in all field experiments. As expected, DSS-guided schedules were influenced by prevailing weather (observed and forecast) and host resistance and resulted in schedules that maintained or improved disease suppression and average fungicide use efficiency relative to calendar-based applications. The DSS provides an interactive system that helps users maximize the efficiency of their crop protection strategy by enabling well-informed decisions.

  3. First Report of Foliar Blight on Dendropanax morbifera Caused by Alternaria panax.

    Science.gov (United States)

    Deng, Jian Xin; Kim, Chang Sun; Oh, Eun Sung; Yu, Seung Hun

    2010-12-01

    Leaf spot and blight disease was observed on two-year-old seedlings of Dendropanax morbifera (Korean name: Hwangchil tree) during July of 2008 in Jindo Island, Korea. Symptoms included yellow-brown to dark brown irregularly enlarged spots frequently located along the veins of leaves. The lesions were often surrounded by chlorotic haloes. Severe leaf blight and subsequent defoliation occurred when conditions favored disease outbreak. The causal organism of the disease was identified as Alternaria panax based on morphological characteristics and sequence analysis of the internal transcribed spacer region of rDNA. A. panax isolates induced leaf spots and blight symptoms not only on D. morbifera but also on the other members of Araliaceae tested. This is the first report of foliar blight caused by A. panax on D. morbifera.

  4. Performance of resistance gene pyramids to races of rice bacterial blight in Zhejiang Province

    Institute of Scientific and Technical Information of China (English)

    ZHENGKangle; ZHUANGJieyun; WANGHanrong

    1998-01-01

    The effect of gene pyramiding on resistance to bacterial blight (BB) in rice was evahlated among the IR24-based near isogenic lines conraining single resistance gene and gene pyramids containing two, three or lour resistancegenes (see table).

  5. Characterization of Novel Bacteriophages for Biocontrol of Bacterial Blight in Leek Caused by Pseudomonas syringae pv. porri.

    Science.gov (United States)

    Rombouts, Sofie; Volckaert, Anneleen; Venneman, Sofie; Declercq, Bart; Vandenheuvel, Dieter; Allonsius, Camille N; Van Malderghem, Cinzia; Jang, Ho B; Briers, Yves; Noben, Jean P; Klumpp, Jochen; Van Vaerenbergh, Johan; Maes, Martine; Lavigne, Rob

    2016-01-01

    Pseudomonas syringae pv. porri, the causative agent of bacterial blight in leek (Allium porrum), is increasingly frequent causing problems in leek cultivation. Because of the current lack of control measures, novel bacteriophages were isolated to control this pathogen using phage therapy. Five novel phages were isolated from infected fields in Flanders (vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, vB_PsyM_KIL4, and vB_PsyM_KIL5), and were complemented with one selected host range mutant phage (vB_PsyM_KIL3b). Genome analysis of the phages revealed genome sizes between 90 and 94 kb and an average GC-content of 44.8%. Phylogenomic networking classified them into a novel clade, named the "KIL-like viruses," related to the Felixounalikevirus genus, together with phage phiPsa374 from P. syringae pv. actinidiae. In vitro characterization demonstrated the stability and lytic potential of these phages. Host range analysis confirmed heterogeneity within P. syringae pv. porri, leading to the development of a phage cocktail with a range that covers the entire set of 41 strains tested. Specific bio-assays demonstrated the in planta efficacy of phages vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, and vB_PsyM_KIL3b. In addition, two parallel field trial experiments on three locations using a phage cocktail of the six phages showed variable results. In one trial, symptom development was attenuated. These data suggest some potential for phage therapy in controlling bacterial blight of leek, pending optimization of formulation and application methods.

  6. Characterization of novel bacteriophages for biocontrol of bacterial blight in leek caused by Pseudomonas syringae pv. porri

    Directory of Open Access Journals (Sweden)

    Sofie eRombouts

    2016-03-01

    Full Text Available Pseudomonas syringae pv. porri, the causative agent of bacterial blight in leek (Allium porrum, is increasingly frequent causing problems in leek cultivation. Because of the current lack of control measures, novel bacteriophages were isolated to control this pathogen using phage therapy. Five novel phages were isolated from infected fields in Flanders (vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3, vB_PsyM_KIL4 and vB_PsyM_KIL5, and were complemented with one selected host range mutant phage (vB_PsyM_KIL3b. Genome analysis of the phages revealed genome sizes between 90 and 94 kb and an average GC-content of 44.8%. Phylogenomic networking classified them into a novel clade, named the ‘KIL-like viruses’, related to the Felixounalikevirus genus, together with phage phiPsa374 from Pseudomonas syringae pv. actinidiae. In vitro characterization demonstrated the stability and lytic potential of these phages. Host range analysis confirmed heterogeneity within P. syringae pv. porri, leading to the development of a phage cocktail with a range that covers the entire set of 41 strains tested. Specific bio-assays demonstrated the in planta efficacy of phages vB_PsyM_KIL1, vB_PsyM_KIL2, vB_PsyM_KIL3 and vB_PsyM_KIL3b. In addition, two parallel field trial experiments on three locations using a phage cocktail of the six phages showed variable results. In one trial, symptom development was attenuated. These data suggest some potential for phage therapy in controlling bacterial blight of leek, pending optimization of formulation and application methods.

  7. Species tree estimation for the late blight pathogen, Phytophthora infestans, and close relatives

    Science.gov (United States)

    To better understand the evolutionary history of a group of organisms, an accurate estimate of the species phylogeny must be known. Traditionally, gene trees have served as a proxy for the species tree, although it was acknowledged early on that these trees represented different evolutionary process...

  8. A Population Genetics Framework for Understanding Aggressiveness and Toxigenicity of Fusarium Head Blight Pathogens

    Science.gov (United States)

    A 14-fold increase in the frequency of 3ADON-producing F. graminearum occured between 1998 and 2004 in western Canada. Significant population structure associated with trichothecene chemotype differences was observed, and isolates from the 3ADON populations were found to accumulate significantly mo...

  9. Inheritance Analysis and Identification of SSR Markers Linked to Late Blight Resistant Gene in Tomato

    Institute of Scientific and Technical Information of China (English)

    ZHU Hai-shan; WU Tao; ZHANG Zhen-xian

    2006-01-01

    Late blight caused by Phytophthora infestans is the most serious disease of tomato production in China. Studies on the genetics of resistance and identification of molecular markers are very useful for breeding late blight resistant varieties.The objective of this paper was to study the inheritance of late blight resistance and identify simple sequence repeat (SSR)markers associated with resistance allele in tomato (Lycopersicon esculentum Mill). The results came from an F2 progeny of 241 plants derived from a cross between 5# inbred line that is susceptible to late blight and a resistant accession CLN2037E. The late blight responses of F2 plants were tested by artificially inoculation of detached-leaflets in plate and natural infection assayed under greenhouse conditions. Both methods showed that the resistance is dominant and inherited as monogenic trait. Genetic mapping and linkage analysis showed that the late blight resistance gene Ph-ROL was located on chromosome 9 with a genetic distance of 5.7 cM to the SSR marker TOM236.

  10. Cultural Heritage in the Gulf: Blight or Blessing?

    Directory of Open Access Journals (Sweden)

    Djamel Boussaa

    2014-12-01

    Full Text Available In the Gulf and after gaining independence in the 1960s and 1970s many cities witnessed a staggering rapid urban growth. The urban centers, which formed the central parts of these cities, underwent continuous pressures of destruction and redevelopment. A large number of these centers have been often demolished and replaced by alien imported high-rise buildings. The urban cores which escaped complete demolition have survived as isolated pockets in the middle of hybrid environments. This dilemma raises important questions; is this surviving cultural heritage blight or blessing? Is it "blight" and obstacle that stifles our cities from moving forward to aspire for a bright and prosperous future, or is it "blessing" an asset that can form a major catalyst to promote our cities while maintaining strong roots with their past? Accordingly, what should be the future of these surviving historic centers? Will they be demolished to pave way for more ambitious growth or can they be conserved and sustained for present and future generations? Will the historic city, the heart of urban life and the main protector of our cities identities, survive and continue to be places for living within the emerging global cities of today and tomorrow? This paper attempts to highlight the importance of dealing with the conservation and development issue, by raising and discussing the following question: How can our cultural heritage be a setting of appropriate conservation and development in the emerging global environments? In order to discuss this issue, three historic cities from the Gulf; Old Dubai in UAE, Old Jeddah in Saudi Arabia and Old Doha in Qatar will form the setting of this research.

  11. Development of forecasting elements for minimization of fungicide treatment in potato protection against early blight in Moscow region

    OpenAIRE

    Penjkin Roman V.; Doroškina Ljudmila A.; Smirnov Aleksej N.

    2013-01-01

    Early blight of potato (the agent is imperfect fungus Alternaria alternata (Fr.) Keissl.) is a serious disease of potatoes under hot conditions. This disease is important in the regions of Eastern and Southern Europe, Asia and Africa. It is controlled with intensive application of fungicides commonly used against late blight. However, currently fungicides cause undesirable damage to humans and the environment. Elements of forecasting the early blight have been developed in order to mini...

  12. A prospective study on drug monitoring of PEGasparaginase and Erwinia asparaginase and asparaginase antibodies in pediatric acute lymphoblastic leukemia.

    Science.gov (United States)

    Tong, Wing H; Pieters, Rob; Kaspers, Gertjan J L; te Loo, D Maroeska W M; Bierings, Marc B; van den Bos, Cor; Kollen, Wouter J W; Hop, Wim C J; Lanvers-Kaminsky, Claudia; Relling, Mary V; Tissing, Wim J E; van der Sluis, Inge M

    2014-03-27

    This study prospectively analyzed the efficacy of very prolonged courses of pegylated Escherichia coli asparaginase (PEGasparaginase) and Erwinia asparaginase in pediatric acute lymphoblastic leukemia (ALL) patients. Patients received 15 PEGasparaginase infusions (2500 IU/m(2) every 2 weeks) in intensification after receiving native E coli asparaginase in induction. In case of allergy to or silent inactivation of PEGasparaginase, Erwinia asparaginase (20 000 IU/m(2) 2-3 times weekly) was given. Eighty-nine patients were enrolled in the PEGasparaginase study. Twenty (22%) of the PEGasparaginase-treated patients developed an allergy; 7 (8%) showed silent inactivation. The PEGasparaginase level was 0 in all allergic patients (grade 1-4). Patients without hypersensitivity to PEGasparaginase had serum mean trough levels of 899 U/L. Fifty-nine patients were included in the Erwinia asparaginase study; 2 (3%) developed an allergy and none silent inactivation. Ninety-six percent had at least 1 trough level ≥100 U/L. The serum asparagine level was not always completely depleted with Erwinia asparaginase in contrast to PEGasparaginase. The presence of asparaginase antibodies was related to allergies and silent inactivation, but with low specificity (64%). Use of native E coli asparaginase in induction leads to high hypersensitivity rates to PEGasparaginase in intensification. Therefore, PEGasparaginase should be used upfront in induction, and we suggest that the dose could be lowered. Switching to Erwinia asparaginase leads to effective asparaginase levels in most patients. Therapeutic drug monitoring has been added to our ALL-11 protocol to individualize asparaginase therapy.

  13. Biocontrol of Late Blight (Phytophthora capsici Disease and Growth Promotion of Pepper by Burkholderia cepacia MPC-7

    Directory of Open Access Journals (Sweden)

    Mao Sopheareth

    2013-03-01

    Full Text Available A chitinolytic bacterial strain having strong antifungal activity was isolated and identified as Burkholderia cepacia MPC-7 based on 16S rRNA gene analysis. MPC-7 solubilized insoluble phosphorous in hydroxyapatite agar media. It produced gluconic acid and 2-ketogluconic acid related to the decrease in pH of broth culture. The antagonist produced benzoic acid (BA and phenylacetic acid (PA. The authentic compounds, BA and PA, showed a broad spectrum of antimicrobial activity against yeast, several bacterial and fungal pathogens in vitro. To demonstrate the biocontrol efficiency of MPC-7 on late blight disease caused by Phytophthora capsici, pepper plants in pot trials were treated with modified medium only (M, M plus zoospore inoculation (MP, MPC-7 cultured broth (B and B plus zoospore inoculation (BP. With the sudden increase in root mortality, plants in MP wilted as early as five days after pathogen inoculation. However, plant in BP did not show any symptom of wilting until five days. Root mortality in BP was markedly reduced for as much as 50%. Plants in B had higher dry weight, P concentration in root, and larger leaf area compared to those in M and MP. These results suggested that B. cepacia MPC-7 should be considered as a candidate for the biological fertilizer as well as antimicrobial agent for pepper plants.

  14. Historic Late Blight Outbreaks Caused by a Widespread Dominant Lineage of Phytophthora infestans (Mont.) de Bary

    Science.gov (United States)

    Martin, Michael D.

    2016-01-01

    Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, was responsible for the Irish potato famine of the 1840s. Initial disease outbreaks occurred in the US in 1843, two years prior to European outbreaks. We examined the evolutionary relationships and source of the 19th-century outbreaks using herbarium specimens of P. infestans from historic (1846–1970) and more recent isolates (1992–2014) of the pathogen. The same unique SSR multilocus genotype, named here as FAM-1, caused widespread outbreaks in both US and Europe. The FAM-1 lineage shared allelic diversity and grouped with the oldest specimens collected in Colombia and Central America. The FAM-1 lineage of P. infestans formed a genetic group that was distinct from more recent aggressive lineages found in the US. The US-1 lineage formed a second, mid-20th century group. Recent modern US lineages and the oldest Mexican lineages formed a genetic group with recent Mexican lineages, suggesting a Mexican origin of recent US lineages. A survey of mitochondrial haplotypes in a larger set of global herbarium specimens documented the more frequent occurrence of the HERB-1 (type Ia) mitochondrial haplotype in archival collections from 1866–75 and 1906–1915 and the rise of the Ib mitochondrial lineage (US-1) between 1946–1955. The FAM-1 SSR lineage survived for almost 100 years in the US, was geographically widespread, and was displaced first in the mid-20th century by the US-1 lineage and then by distinct new aggressive lineages that migrated from Mexico. PMID:28030580

  15. Reduced susceptibility to Fusarium head blight in Brachypodium distachyon through priming with the Fusarium mycotoxin deoxynivalenol.

    Science.gov (United States)

    Blümke, Antje; Sode, Björn; Ellinger, Dorothea; Voigt, Christian A

    2015-06-01

    The fungal cereal pathogen Fusarium graminearum produces deoxynivalenol (DON) during infection. The mycotoxin DON is associated with Fusarium head blight (FHB), a disease that can cause vast grain losses. Whilst investigating the suitability of Brachypodium distachyon as a model for spreading resistance to F. graminearum, we unexpectedly discovered that DON pretreatment of spikelets could reduce susceptibility to FHB in this model grass. We started to analyse the cell wall changes in spikelets after infection with F. graminearum wild-type and defined mutants: the DON-deficient Δtri5 mutant and the DON-producing lipase disruption mutant Δfgl1, both infecting only directly inoculated florets, and the mitogen-activated protein (MAP) kinase disruption mutant Δgpmk1, with strongly decreased virulence but intact DON production. At 14 days post-inoculation, the glucose amounts in the non-cellulosic cell wall fraction were only increased in spikelets infected with the DON-producing strains wild-type, Δfgl1 and Δgpmk1. Hence, we tested for DON-induced cell wall changes in B. distachyon, which were most prominent at DON concentrations ranging from 1 to 100 ppb. To test the involvement of DON in defence priming, we pretreated spikelets with DON at a concentration of 1 ppm prior to F. graminearum wild-type infection, which significantly reduced FHB disease symptoms. The analysis of cell wall composition and plant defence-related gene expression after DON pretreatment and fungal infection suggested that DON-induced priming of the spikelet tissue contributed to the reduced susceptibility to FHB.

  16. Occurrence Regularity of Tea Guignardia Leaf Blight and Control Mea-sures%茶云纹叶枯病的发生规律及防治

    Institute of Scientific and Technical Information of China (English)

    韩必新

    2015-01-01

    Tea Guignardia leaf blight favors high humidity and temperature. The pathogen and its characteristics,in-fection cycle, occurrence regularity,dam-age symptom of tea Guignardia leaf blight were introduced at first,then agri-cultural control measures were put for-ward, such as choosing suitable terrains and soil, using disease-resistant vari-eties, cleaning tea farm, enhancing tea farm management. And suitable pesti-cides could be sprayed as soon as possi-ble.This study provided scientific support for controlling the disease.%茶云纹叶枯病是一种高湿高湿型病害。该文介绍了该病害的病原及特征、侵染循环、发生规律、危害症状,指出农业防治可选择适宜的地形、地势和土壤,利用抗病品种,注意茶园卫生,加强茶园管理;化学防治可选择适宜的药剂尽早喷防。为尽快控制茶云纹叶枯病危害提供了科学依据。

  17. Identification and gene prediction of a 24 kb region containing xa5, a recessive bacterial blight resistance gene in rice (Oryza sativa L.)

    Institute of Scientific and Technical Information of China (English)

    ZHONG Yiming; JIANG Guanghuai; CHEN Xuewei; XIA Zhihui; LI Xiaobing; ZHU Lihuang; ZHAI Wenxue

    2003-01-01

    Rice xa5 gene provides recessive, race-specific resistance to bacterial blight disease caused by the pathogen Xanthomonas oryzae pv. oryzae and has great value for research and breeding. In an effort to clone xa5, an F2 population of 4892 individuals was developed from the xa5 near isogenic lines, IR24 and IRBB5. A fine mapping procedure was conducted and tightly linked RFLP markers were used to screen a BAC library of IRBB56, a resistant rice line containing the xa5 gene. A 213 kb contig covering the xa5 locus was constructed. According to the sequences from the International Rice Genome Sequening Project (IRGSP), the Chinese Superhybrid Rice Genome Project (SRGP) and some sub-clones of the contig, twelve SSLP and CAPS markers were developed for fine mapping. The xa5 gene was mapped to a 0.3 cM interval between markers K5 and T4, which spanned an interval of approximately 24 kb, co-segregating with marker T2. Sequence analysis of the 24 kb region revealed that an ABC transporter and a basal transcription factor (TFIIa) were potential candidates for the xa5 resistance gene product. The molecular mechanism by which the xa5 gene provides recessive, race-specific resistance to bacterial blight will be elucidated by the functional tests of the 24 kb DNA and the candidate genes.

  18. Analyses of the Temporal Development and Yield Losses due to Sheath Blight of Rice (Rhizoctonia solani AG1.1a)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Sheath blight of rice, caused by Rhizoctonia solani AG1.1a, has become the most important disease and caused serious yield losses in some major rice-growing regions in China in recent years. In the present study, field plot experiment was conducted to examine the relationships between disease intensity and inoculum density (ID), the seasonal disease epidemic dynamics, and yield reductions due to disease damages. Results from the experiment demonstrated that the areas under progress curves of disease severity and those of percent rice tillers diseased were positively and closely related to the relative initial ID of the pathogen. The inoculum density-disease (IDD) relationships were simulated and the impractical linear models were obtained. Both logistic and Gompertz functions could be used to simulate the disease progress dynamics in time, but the progress curves of the disease severity were modeled better by the Gompertz than by logistic function. However, the Richards function was found to be the best in simulating the disease progress curves when a most appropriate value was chosen for the shape parameter m by using the computer software Epitimulator(R).Sheath blight infection decreased rice yield very significantly and a yield reduction of 40% was recorded in rice crop with the highest inoculum density. Rice yield was linearly and negatively correlated with the disease severity and the percent tillers affected. The simulated models for all these relationships were computed through executing Epitimulator(R) software and were presented in this paper.

  19. Control of postharvest soft rot caused by Erwinia carotovora of vegetables by a strain of Bacillus amyloliquefaciens and its potential modes of action.

    Science.gov (United States)

    Zhao, Yancun; Li, Pengxia; Huang, Kaihong; Wang, Yuning; Hu, Huali; Sun, Ya

    2013-03-01

    Erwinia carotovora subsp. carotovora (Ecc), the causal agent of bacterial soft rot, is one of the destructive pathogens of postharvest vegetables. In this study, a bacterial isolate (BGP20) from the vegetable farm soil showed strong antagonistic activity against Ecc in vitro, and its twofold cell-free culture filtrate showed excellent biocontrol effect in controlling the postharvest bacterial soft rot of potatoes at 25 °C. The anti-Ecc metabolites produced by the isolate BGP20 had a high resistance to high temperature, UV-light and protease K. Based on the colonial morphology, cellular morphology, sporulation, and partial nucleotide sequences of 16S rRNA and gyrB gene, the isolate BGP20 was identified as Bacillus amyloliquefaciens subsp. plantarum. Further in vivo assays showed that the BGP20 cell culture was more effective in controlling the postharvest bacterial soft rot of green peppers and Chinese cabbages than its twofold cell-free culture filtrate. In contrast, the biocontrol effect and safety of the BGP20 cell culture were very poor on potatoes. In the wounds of potatoes treated with both the antagonist BGP20 and the pathogen Ecc, the viable count of Ecc was 31,746 times that of BGP20 at 48 h of incubation at 25 °C. But in the wounds of green peppers, the viable count of BGP20 increased 182.3 times within 48 h, and that of Ecc increased only 51.3 %. In addition, the treatment with both BGP20 and Ecc induced higher activity of phenylalanine ammonia-lyase (PAL) than others in potatoes. But the same treatment did not induce an increase of PAL activity in green peppers. In conclusion, the present study demonstrated that the isolate BGP20 is a promising candidate in biological control of postharvest bacterial soft rot of vegetables, but its main mode of action is different among various vegetables.

  20. Stating the Epidemic and Controll of Banana Blight According to Principle of Disease Tetra-angle%根据病害四角原理阐述香蕉枯萎病流行与防控

    Institute of Scientific and Technical Information of China (English)

    文衍堂; 谢昌平; 贺春萍; 胡美姣; 杨波

    2012-01-01

    According to principle of disease tetra-angle, relationship between human, host, pathogen and environment condition, stale the epidemic and control engineering of Banana blight caused by Fusarium oxysporum f. sp. cubense.%根据病害四角原理,即人、寄主植物、病原物和环境条件四方面的关系,阐述由尖镰孢古巴专化型弓致香蕉枯萎病流行与防控工程。

  1. Simplification of vacuole structure during plant cell death triggered by culture filtrates of Erwinia carotovora

    Institute of Scientific and Technical Information of China (English)

    Yumi Hirakawa; Toshihisa Nomura; Seiichiro Hasezawa; Takumi Higaki

    2015-01-01

    Vacuoles are suggested to play crucial roles in plant defense-related cel death. During programmed cel death, previous live cel imaging studies have observed vacuoles to become simpler in structure and have implicated this simplification as a prelude to the vacuole’s rupture and consequent lysis of the plasma membrane. Here, we examined dynamics of the vacuole in cel cycle-synchronized tobacco BY-2 (Nicotiana tabacum L. cv. Bright Yel ow 2) cel s during cel death induced by application of culture filtrates of Erwinia carotovora. The filtrate induced death in about 90%of the cel s by 24 h. Prior to cel death, vacuole shape simplified and endoplasmic actin filaments disassembled;however, the vacuoles did not rupture until after plasma membrane integrity was lost. Instead of facilitating rupture, the simplification of vacuole structure might play a role in the retrieval of membrane components needed for defense-related cel death.

  2. Reactive oxygen species activity in the interaction of rice with Erwinia chrysanthemi pv. zeae

    Institute of Scientific and Technical Information of China (English)

    Qiongguang LIU; Landi HE; Jingyi ZHANG; Yutao WANG; Zhenzhong WANG

    2008-01-01

    Activities of reactive oxygen species (ROS) were investigated in the interaction between rice and Erwinia chrysanthemi pv. zeae. Results showed that variety (128) had higher increases in activity compared to those in the susceptible variety (Texian 13) 24 hours after bacteria inoculation. The activities of superoxide dismutase (SOD) increased in 128 and Texian 13 twenty-four hours after inoculation and then decreased, but the SOD activity in 128 was found to be usually lower than that in Texian 13. The CAT activity in Texian 13 had two peaks at 24 h and 96 h after inoculation, while little change was seen in 128. In conclusion, ROS and its related enzymes could be correlated to rice resistance against E. chrysanthemi pv. zeae.

  3. Quantitative Effects of Early and Late Blights on Tomato Yields in Cameroon

    Directory of Open Access Journals (Sweden)

    Fontem, DA.

    2003-01-01

    Full Text Available Early blight caused by Alternaria solani and late blight caused by Phytophthora infestans are the major diseases of tomato (Lycopersicon esculentum in Cameroon. The effect of both diseases on fruit yield was evaluated during the 1995 growing season in Dschang, Cameroon.Ten varieties were planted in the first trial (March-July and nine in the second (July- November. In both trials, plots were sprayed weekly with Ridomil Plus (2.0 kg/ha before flowering and with maneb (1.6 kg/ha after flowering. Early blight was more severe in the early part of the first trial, while late blight caused most damage during the second. Marketable yields varied according to variety. High yields in sprayed plots were obtained in Dona F1 (61.63 t/ha and Heinz 1370 (68.24 t/ha during the first trial, and in Fline (58.35 t/ha, Mecline (64.25 t/ha, and Moboline (55.16 t/ha during the second trial. Percent fruit infection in sprayed plots caused by both diseases varied according to variety from 12 to 65% in the first season and from 14 to 52% in the second, while losses in marketable yields for both blights were as high as 100% in unsprayed plots.

  4. Erwinia typographi sp. nov., isolated from bark beetle (Ips typographus) gut.

    Science.gov (United States)

    Skrodenyte-Arbaciauskiene, V; Radziute, S; Stunzenas, V; Būda, V

    2012-04-01

    Gram-negative-staining bacteria that were resistant to monoterpene myrcene (7-methyl-3-methylene-1.6-octadiene, C10H16, at concentrations of up to 10 µl ml(-1) in TSB) were isolated from the gut contents of adult bark beetles Ips typographus (Coleoptera, Scolytidae). The beetles were collected from the bark of Norway spruce (Picea abies) in Lithuania. Bark beetles feed on conifers, which produce myrcene among many other defensive compounds. It has been suggested that the micro-organisms present within the beetles' guts could be involved in their resistance towards this plant defensive compound. The most resistant bacterial strains were isolated and characterized by phenotypic assays as well as fatty acid analysis, 16S rRNA gene sequencing, multilocus sequence analyses (MLSA) based on the rpoB, atpD and infB genes and DNA-DNA hybridization. Biochemical characterization indicated that the bacteria belonged to the family Enterobacteriaceae. Phylogenetic analyses of the 16S rRNA gene sequences and MLSA of the novel strains revealed that they belonged to the genus Erwinia, but represented a novel species. The dominant cellular fatty acids were C16:0 and C17:0 cyclo. The DNA G+C content was 49.1 mol%. The results obtained in this study indicated that these bacteria from the bark beetle gut represented a novel species, for which the name Erwinia typographi sp. nov. is proposed, with the type strain DSM 22678T (=Y1T=LMG 25347T).

  5. Competition between Phytophthora infestans effectors leads to increased aggressiveness on plants containing broad-spectrum late blight resistance.

    Directory of Open Access Journals (Sweden)

    Dennis A Halterman

    Full Text Available BACKGROUND: The destructive plant disease potato late blight is caused by the oomycete pathogen Phytophthora infestans (Mont. de Bary. This disease has remained particularly problematic despite intensive breeding efforts to integrate resistance into cultivated potato, largely because of the pathogen's ability to quickly evolve to overcome major resistance genes. The RB gene, identified in the wild potato species S. bulbocastanum, encodes a protein that confers broad-spectrum resistance to most P. infestans isolates through its recognition of highly conserved members of the corresponding pathogen effector family IPI-O. IpiO is a multigene family of effectors and while the majority of IPI-O proteins are recognized by RB to elicit host resistance, some variants exist that are able to elude detection (e.g. IPI-O4. METHODS AND FINDINGS: In the present study, analysis of ipiO variants among 40 different P. infestans isolates collected from Guatemala, Thailand, and the United States revealed a high degree of complexity within this gene family. Isolate aggressiveness was correlated with increased ipiO diversity and especially the presence of the ipiO4 variant. Furthermore, isolates expressing IPI-O4 overcame RB-mediated resistance in transgenic potato plants even when the resistance-eliciting IPI-O1 variant was present. In support of this finding, we observed that expression of IPI-O4 via Agrobacterium blocked recognition of IPI-O1, leading to inactivation of RB-mediated programmed cell death in Nicotiana benthamiana. CONCLUSIONS: In this study we definitively demonstrate and provide the first evidence that P. infestans can defeat an R protein through inhibition of recognition of the corresponding effector protein.

  6. Dynamics of Cryphonectria hypovirus infection in chestnut blight cankers.

    Science.gov (United States)

    Bryner, Sarah Franziska; Prospero, Simone; Rigling, Daniel

    2014-09-01

    Virulent strains of the chestnut blight fungus Cryphonectria parasitica cause lethal bark cankers on chestnut trees. Infection of C. parasitica with Cryphonectria hypovirus 1 in Europe biologically controls this disease, leading to nonlethal and inactive cankers. Unexpectedly, virus-free C. parasitica strains have been isolated from inactive cankers. In this study, we compared the virulence of virus-infected and virus-free C. parasitica strains isolated from either inactive or active cankers on chestnut seedlings and sprouts. In the seedling experiment, we assessed canker growth and seedling mortality. In the sprout experiment, we also assessed canker growth and made fungal reisolations to determine virus infection and immigration of foreign vegetative compatibility (vc) types over a period of 13 years in a coppice forest. Overall, the virulence of virus-free C. parasitica strains isolated from inactive versus active cankers did not differ. Significant differences were only attributed to virus infection. Virus infection and fungal strain composition in cankers changed over time. Foreign vc types immigrated into cankers and virus-free cankers became virus-infected within a few years. Most of the cankers were callused over time and became inactive. However, we observed that the virus did not always persist in these cankers. This study demonstrates that virus spread occurs effectively in European chestnut forests and that this biocontrol system is highly dynamic.

  7. Effects of hydrogen fluoride on plant-pathogen interactions. [Lycopersicon esculentum; Phaseolus vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    McCune, D.C.; Weinstein, L.H.; Mancini, J.F.; van Lueken, P.

    1973-01-01

    Experiments in fumigation chambers with tomato (Lycopersicon esculentum) and pinto bean (Phaseolus vulgaris) plants were performed to assess the effects of hydrogen fluoride on plant-pathogen (fungal and bacterial) interactions. Hydrogen fluoride was found to alter the plant-pathogen interaction, although the kind and consistency of effect caused by HF depended upon the host, pathogen, and several other factors. A reduction in powdery mildew probably indicates that HF was affecting the infectivity of the pathogen itself because reduction in disease was proportional to the length of the exposure period, infection was continuous during the exposure period, and the pathogen itself was epiphytic. The effect of fluoride on bean rust may have been due to accumulated fluoride in the leaf having a direct or indirect effect on the pathogen because both pre- and post-inoculation exposures to HF were effective and additive. Other evidence for an indirect effect of fluoride was found in halo-blight where stem collapse was affected but foliar symptoms were not, and the site affected was spatially removed from the site of fluoride accumulation. Effects on early blight of tomato also indicated an effect of fluoride in the leaf.

  8. The chestnut blight fungus for studies on virus/host and virus/virus interactions: from a natural to a model host.

    Science.gov (United States)

    Eusebio-Cope, Ana; Sun, Liying; Tanaka, Toru; Chiba, Sotaro; Kasahara, Shin; Suzuki, Nobuhiro

    2015-03-01

    The chestnut blight fungus, Cryphonectria parasitica, is an important plant pathogenic ascomycete. The fungus hosts a wide range of viruses and now has been established as a model filamentous fungus for studying virus/host and virus/virus interactions. This is based on the development of methods for artificial virus introduction and elimination, host genome manipulability, available host genome sequence with annotations, host mutant strains, and molecular tools. Molecular tools include sub-cellular distribution markers, gene expression reporters, and vectors with regulatable promoters that have been long available for unicellular organisms, cultured cells, individuals of animals and plants, and certain filamentous fungi. A comparison with other filamentous fungi such as Neurospora crassa has been made to establish clear advantages and disadvantages of C. parasitica as a virus host. In addition, a few recent studies on RNA silencing vs. viruses in this fungus are introduced.

  9. Tagging RAPD markers to a bacterial blight resistance gene in rice

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@The somaclonal mutant HX_3 has shown a broad spectrum resistance to bacterial blight. To study the inheritance of the bacterial blight resistance in HX_3, a cross was made between HX_3 and a susceptible cultivar Longtefu A. The F2 population of 418 plants was inoculated with Chinese bacterial blight strain Zhe 173 (pathotype Ⅳ ). Results showed that the F2 progenies segregated in a ratio of 3R∶ 1S (324 resistant plants and 94 susceptible plants). From the plants tested, 114 individuals (86 resistant and 28 susceptible) were chosen randomly for RAPD analysis. Twelve highly resistant and 12 highly susceptible plants were selected to form a resistant pool and a susceptible pool, respectively.

  10. 菊欧文氏菌分子检测技术的研究%Molecular detection of Erwinia chrysanthemi

    Institute of Scientific and Technical Information of China (English)

    刘鹏; 黄国明; 刘勇; 崔铁军

    2007-01-01

    蝴蝶兰细菌性软腐病对蝴蝶兰的生长危害严重,Erwinia chrysanthemi(菊欧文氏菌)、Erwinia carotovora subsp.carotovora(胡萝卜软腐欧文氏菌胡萝卜软腐亚种)是引起蝴蝶兰软腐病的主要病原细菌,其中E. chrysanthemi被列入我国三类检疫性有害生物.本文对菊欧文氏菌分子检测技术进行了研究,设计出针对该病原细菌的特异性引物,应用实时荧光PCR方法检测样品中存在的菊欧文氏菌,检测灵敏度达到102 cfu/mL.

  11. Characterization of pathogenic Pantoea agglomerans from rice seed%稻谷病原细菌Pantoea agglomerans的特征化研究

    Institute of Scientific and Technical Information of China (English)

    谢关林; 徐传雨; 任小平

    2001-01-01

    Twelve bacterial isolates were isolated from discolored palea of rice grains in Jiaxing and Yuhang of Zhejiang, China. They were identified as Pantoea agglomeras (Erwinia herbicola) after bacteriology, Biolog, pathogenicity test and compared with 6 standard reference strains of Japan. It has been confirmed that the causal organism of the palea browning is same as that reported in Japan in 1983.%从浙江嘉兴和余杭的内颖变褐稻谷上分离出12个细菌菌株,经细菌学、Biolog和致病性测定,并与6个日本标准菌株比较。证实了这种内颖褐变病是由Pantoea agglomerans (Erwinia herbicola)引起,与日本1983年报道的内颖褐变病症状及病原基本相似

  12. Prevalence of Erwinia soft rot affecting cut foliage, Dracaena sanderiana ornamental industry and solution towards its management.

    Science.gov (United States)

    Kayalvily, Thio Desiya; Jegathambigai, V; Karunarathne, M D S D; Svinningen, Arne; Mikunthan, G

    2012-01-01

    The study was carried out under net house conditions at Green Farms Ltd, Marawila to determine the occurrence and severity of Erwinia soft rot disease in Dracaena sanderiana plants and to formulate the possible control measures. Field experiment was carried out to manage the soft rot disease in D. sanderiana plants. Three different soil treatments with vermicompost, cow dung and poultry manure were tested to manage the disease and plots without application were kept as control. Percent disease incidence, disease reduction and growth parameters were recorded and data were statistically analyzed. Higher percentage of disease reduction was observed in vermicompost (80%) treated plots than those with cow dung (60%) and poultry manure treated. Sprinkler application of water was found favorable to spread soft rot disease and watering through horse pope had lessened the disease incidence significantly. Moreover plant height, shoot and root biomass, number of leaves per plant, leaf length and leaf width were significantly high in vermicompost media. Weeding, removal of diseased leaves and plants, and avoiding sprinkler irrigation were helpful to reduce the disease spread from plant to plant. Vermicompost is the best substrate for suppression of the disease and promoting the growth of plant. Among the different water management practices tested to reduce the disease severity of Erwinia soft rot disease in D. sanderiana plants, water irrigated through the horse pipe was effective compare to sprinkler application. In-vitro experiment conducted to manage the Erwinia soft rot disease by using bio-agent, Pseudomonas fluorescens was found effective to reduce the growth of Erwinia under in-vitro conditions.

  13. Identification and genetics of 6-thioguanine secreted by Erwinia species and its interference with the growth of other bacteria.

    Science.gov (United States)

    Wensing, A; Gernold, M; Jock, S; Jansen, R; Geider, K

    2014-04-01

    We identified a compound in culture supernatants of Erwinia species, such as Erwinia amylovora, E. pyrifoliae, E. billingiae, E. tasmaniensis, E. persicina and E. rhapontici absorbing at 340 nm, which was associated before with the yellow pigment produced by E. amylovora on media containing copper ions. The compound was purified from E. tasmaniensis strain Et1/99 supernatants by chromatography on Dowex-1 and Dowex-50 columns and identified by HPLC/MS and NMR analysis as 6-thioguanine (6TG). Its signal at 167 Da matched with the expected molecular mass. By random mutagenesis with miniTn5, we obtained mutants defective in the genes for pyrimidine and purine metabolism. A specific gene cluster with ycf genes described by us before, absent in the corresponding region of Escherichia coli, was identified in the genome sequence of three Erwinia species and named tgs region for thioguanine synthesis. Clones of the tgs gene cluster promoted 6TG synthesis and secretion in E. coli, when the bacteria were grown in minimal medium supplemented with amino acids. 6TG was bacteriostatic for E. coli and Salmonella typhimurium strains, with cell growth resumed after prolonged incubation. Similar results were obtained with P. agglomerans strains. Bacteria from the genus Pectobacterium were barely and Rahnella or Gibbsiella species were not inhibited by 6TG. Adenine and guanine relieved the toxic effect of 6TG on E. coli. Non-producing strains were fully virulent on host plants. 6TG synthesis may help erwinias to interfere with growth of some microorganisms in the environment.

  14. Pathogen intelligence

    Science.gov (United States)

    Steinert, Michael

    2014-01-01

    Different species inhabit different sensory worlds and thus have evolved diverse means of processing information, learning and memory. In the escalated arms race with host defense, each pathogenic bacterium not only has evolved its individual cellular sensing and behavior, but also collective sensing, interbacterial communication, distributed information processing, joint decision making, dissociative behavior, and the phenotypic and genotypic heterogeneity necessary for epidemiologic success. Moreover, pathogenic populations take advantage of dormancy strategies and rapid evolutionary speed, which allow them to save co-generated intelligent traits in a collective genomic memory. This review discusses how these mechanisms add further levels of complexity to bacterial pathogenicity and transmission, and how mining for these mechanisms could help to develop new anti-infective strategies. PMID:24551600

  15. Development of bioformulation and delivery system of Pseudomonas fluorescens against bacterial leaf blight of rice (Xanthomonas oryzae pv. oryzae).

    Science.gov (United States)

    Jambhulkar, P P; Sharma, P

    2014-09-01

    Antagonistic potential of Pseudomonas fluorescens isolate RRb-11 has been evaluated against bacterial leaf blight (BLB) pathogen of rice in vitro, in vivo, microplot and field tests. RRb-11 isolate mass multiplied in substrates like talc and kaolinite powder and bran of barley, soybean and wheat to prepare suitable bioformulation. The maximum shelf life of P. fluorescens was recorded in talc based bioformulation up to 150 days after storage. In rhizosphere competence study, the root rhizosphere of talc, kaolinite and barley based bioformulation treated plants showed good survivability and competence even up to 90 days after treatment. In field study, the talc based bioformulation was applied and the best results were obtained when talc based bioformulation of P. fluorescens RRb-11 was applied as seed treatment, seedling root dip and soil application in combination which reduced the disease by 92.3 and 88.5% over control in the year 2009 and 2010, respectively. This treatment also produced maximum yield of 3.88 t ha(-1) i.e., 61% greater than control.

  16. Vegetative Compatibility Groups in Cercospora kikuchii, the Causal Agent of Cercospora Leaf Blight and Purple Seed Stain in Soybean.

    Science.gov (United States)

    Cai, G; Schneider, R W

    2005-03-01

    ABSTRACT Nitrogen nonutilizing (Nit) mutants were used to assess vegetative compatibility of 58 isolates of Cercospora kikuchii, 55 of which were isolated from soybean plants in Louisiana. Two isolates were vegetatively self-incompatible. Of 56 self-compatible isolates, 16 were assigned to six multimember vegetative compatibility groups (VCGs), 01 to 06, with 2 or 3 isolates in each VCG. The other 40 isolates each belonged to a distinct VCG. All six multimember VCGs contained isolates from different soy bean cultivars, and three included isolates from different locations. Only one of six multimember VCGs included isolates both from soybean leaves and seed, while the other five included isolates from only leaves or seed. The likelihood of tissue specificity or preference was discussed. All isolates and tested Nit mutants produced cercosporin on potato dextrose agar under light. Significantly different amounts of cercosporin were produced among wild-type isolates, and two Nit mutants produced significantly more cercosporin than their wild-type counterparts. All isolates produced typical Cercospora leaf blight symptoms on soybean plants in greenhouse pathogenicity tests.

  17. Pathogen surveillance in wild bottlenose dolphins Tursiops truncatus.

    Science.gov (United States)

    Jaing, Crystal; Thissen, James B; Gardner, Shea; McLoughlin, Kevin; Slezak, Tom; Bossart, Gregory D; Fair, Patricia A

    2015-10-16

    The number and prevalence of diseases is rapidly increasing in the marine ecosystem. Although there is an increase in the number of marine diseases observed world-wide, current understanding of the pathogens associated with marine mammals is limited. An important need exists to develop and apply platforms for rapid detection and characterization of pathogenic agents to assess, prevent and respond to disease outbreaks. In this study, a broad-spectrum molecular detection technology capable of detecting all sequenced microbial organisms, the Lawrence Livermore Microbial Detection Array, was used to assess the microbial agents that could be associated with wild Atlantic dolphins. Blowhole, gastric, and fecal samples from 8 bottlenose dolphins were collected in Charleston, SC, as part of the dolphin assessment effort. The array detected various microbial agents from the dolphin samples. Clostridium perfringens was most prevalent in the samples surveyed using the microarray. This pathogen was also detected using microbiological culture techniques. Additionally, Campylobacter sp., Staphylococcus sp., Erwinia amylovora, Helicobacter pylori, and Frankia sp. were also detected in more than one dolphin using the microarray, but not in culture. This study provides the first survey of pathogens associated with 3 tissue types in dolphins using a broad-spectrum microbial detection microarray and expands insight on the microbial community profile in dolphins.

  18. Bipolaris sorokiniana, a cereal pathogen of global concern: cytological and molecular approaches towards better controldouble dagger.

    Science.gov (United States)

    Kumar, Jagdish; Schäfer, Patrick; Hückelhoven, Ralph; Langen, Gregor; Baltruschat, Helmut; Stein, Elke; Nagarajan, Subramaniam; Kogel, Karl-Heinz

    2002-07-01

    Summary Bipolaris sorokiniana (teleomorph Cochliobolus sativus) is the causal agent of common root rot, leaf spot disease, seedling blight, head blight, and black point of wheat and barley. The fungus is one of the most serious foliar disease constraints for both crops in warmer growing areas and causes significant yield losses. High temperature and high relative humidity favour the outbreak of the disease, in particular in South Asia's intensive 'irrigated wheat-rice' production systems. In this article, we review the taxonomy and worldwide distribution, as well as strategies to counteract the disease as an emerging threat to cereal production systems. We also review the current understanding of the cytological and molecular aspects of the interaction of the fungus with its cereal hosts, which makes B. sorokiniana a model organism for studying plant defence responses to hemibiotrophic pathogens. The contrasting roles of cell death and H(2)O(2) generation in plant defence during biotrophic and necrotrophic fungal growth phases are discussed.

  19. Conserved aspartate and lysine residues of RcsB are required for amylovoran biosynthesis, virulence, and DNA binding in Erwinia amylovora.

    Science.gov (United States)

    Ancona, Veronica; Chatnaparat, Tiyakhon; Zhao, Youfu

    2015-08-01

    In Erwinia amylovora, the Rcs phosphorelay system is essential for amylovoran production and virulence. To further understand the role of conserved aspartate residue (D56) in the phosphor receiver (PR) domain and lysine (K180) residue in the function domain of RcsB, amino acid substitutions of RcsB mutant alleles were generated by site-directed mutagenesis and complementation of various rcs mutants were performed. A D56E substitution of RcsB, which mimics the phosphorylation state of RcsB, complemented the rcsB mutant, resulting in increased amylovoran production and gene expression, reduced swarming motility, and restored pathogenicity. In contrast, D56N and K180A or K180Q substitutions of RcsB did not complement the rcsB mutant. Electrophoresis mobility shift assays showed that D56E, but not D56N, K180Q and K180A substitutions of RcsB bound to promoters of amsG and flhD, indicating that both D56 and K180 are required for DNA binding. Interestingly, the RcsBD56E allele could also complement rcsAB, rcsBC and rcsABCD mutants with restored virulence and increased amylovoran production, indicating that RcsB phosphorylation is essential for virulence of E. amylovora. In addition, mutations of T904 and A905, but not phosphorylation mimic mutation of D876 in the PR domain of RcsC, constitutively activate the Rcs system, suggesting that phosphor transfer is required for activating the Rcs system and indicating both A905 and T904 are required for the phosphatase activity of RcsC. Our results demonstrated that RcsB phosphorylation and dephosphorylation, phosphor transfer from RcsC are essential for the function of the Rcs system, and also suggested that constitutive activation of the Rcs system could reduce the fitness of E. amylovora.

  20. Erwinia carotovora ssp. carotovora Infection Induced "Defense Lignin" Accumulation and Lignin Biosynthetic Gene Expression in Chinese Cabbage (Brassica rapa L. ssp. pekinensis)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Erwinia carotovora subsp. carotovora (Ecc) infects and causes soft rot disease in hundreds of crop species including vegetables, flowers and fruits. Lignin biosynthesis has been implicated in defensive reactions to injury and pathogen Infection in plants. In this work, variations of lignin content and gene expression in the molecular interaction between Chinese cabbage and Ecc were investigated. H2O2 accumulation and peroxidase activity were detected by 3, 3'-Dimethoxybenzidine staining at mocked and Ecc-inoculated sites of Chinese cabbage leafstalks. Klason lignin content in inoculated plants increased by about 7.84%, 40.37%, and 43.13% more than that of the mocked site at 12, 24 and 72 h after inoculation, respectively. Gas chromatography detected more p-coumaryl (H) and less coniferyl (G) and sinapyl (S)monolignins in leafstalks of Chinese cabbage. All three monomers increased in Ecc-infected leafstalks, and the Ecc-induced "defense lignin" were composed of more G and H monolignins, and less S monolignin. After searching the expressed sequence tags (EST) data of Chinese cabbage, 12 genes putatively encoding enzymes involved in lignin biosynthesis were selected to study their expression. All of these genes could be Induced by mock inoculation and Ecc infection, while the gene expression lasted for several more hours in the infected samples than in mocked and untreated plants. Our results indicated that "defense lignin" was different from the developmental lignin in composition; G and S monolignins were significantly induced in plants in response to the soft rot Ecc; thus, lignin biosynthesis was differentially regulated and played a role in plant response to the soft rot Ecc.

  1. Evidence that antibiotic of Pantoea agglomerans E325 is produced and active against Erwinia amylovora on stigmas of pomaceous blossoms

    Science.gov (United States)

    Pantoea agglomerans strain E325, the active ingredient in a commercial product for fire blight, previously was shown to produce a unique pH-sensitive inhibitor in vitro that is specific to E. amylovora. To evaluate antibiosis as a mode of antagonism of E325, Tn5 mutagenesis was used to generate...

  2. Limitations of Cassava Bacterial Blight: New Advances Limitaciones de la bacteriosis vascular de yuca: Nuevos avances

    Directory of Open Access Journals (Sweden)

    Verdier Valérie

    2006-12-01

    Full Text Available Cassava (Manihot esculenta, a starchy root crop, constitutes the source of alimentation for over 600 million people worldwide. Cassava Bacterial Blight (CBB is caused bythe bacterium Xanthomonas axonopodis pv. manihotis (Xam. This review will focus on the current knowledge on the molecular cassava-Xam interaction. We will present the different molecular techniques developed to assess the genetic diversity and dynamics of Xam populations. We will also present different methods developed for detecting the pathogen in vegetative planting materials and true seeds and their contribution to reduce the impact of the disease. We will review different studies conducted to gain a better understanding on the molecular mechanisms and the genes involved in the cassava bacterial resistance, including the recent advances obtained using functional
    genomics. The acquired knowledge in the last years for this pathosystem will help to establish better disease control strategies and generate, in a short term, resistant cassava varieties contributing to solve one of the main problems of poor cassava farmers and this effort will open a new horizon to the cassava crop in the world.La yuca (Manihot esculenta constituye la base de la alimentación de más de 600 millones de personas en el mundo. Una de las principales limitaciones de este cultivo es la bacteriosis vascular, ocasionada por la bacteria Xanthomonas axonopodis pv. manihotis (Xam. Este artículo revisa el conocimiento actual acerca de la interacción Xanthomonas-yuca. Se presentan estudios recientes llevados a cabo sobre la diversidad y dinámica de las poblaciones de Xam empleando diferentes estrategias moleculares. Se describen los diferentes métodos desarrollados para la detección y diagnóstico de la bacteria en plantas y semillas de yuca y su contribución para reducir el impacto de la enfermedad. Se presentan los estudios encaminados a comprender los mecanismos moleculares y los genes

  3. LIMITACIONES DE LA BACTERIOSIS VASCULAR DE YUCA: NUEVOS AVANCES Limitations of Cassava Bacterial Blight: New Advances

    Directory of Open Access Journals (Sweden)

    CAMILO LÓPEZ

    Full Text Available La yuca (Manihot esculenta constituye la base de la alimentación de más de 600 millones de personas en el mundo. Una de las principales limitaciones de este cultivo es la bacteriosis vascular, ocasionada por la bacteria Xanthomonas axonopodis pv. manihotis (Xam. Este artículo revisa el conocimiento actual acerca de la interacción Xanthomonasyuca. Se presentan estudios recientes llevados a cabo sobre la diversidad y dinámica de las poblaciones de Xam empleando diferentes estrategias moleculares. Se describen los diferentes métodos desarrollados para la detección y diagnóstico de la bacteria en plantas y semillas de yuca y su contribución para reducir el impacto de la enfermedad. Se presentan los estudios encaminados a comprender los mecanismos moleculares y los genes responsables en la resistencia de la yuca a la bacteriosis vascular incluyendo los últimos avances obtenidos gracias a la aplicación de estrategias de genómica funcional. El conocimiento adquirido en los últimos años en este patosistema permitirá desarrollar mejores estrategias para el manejo de la enfermedad así como desarrollar a corto plazo variedades de yuca resistentes a la bacteriosis lo que contribuiría a resolver uno de los principales problemas de los productores pobres de yuca y le abriría un horizonte promisorio al cultivo de la yuca en el mundo.Cassava (Manihot esculenta, a starchy root crop, constitutes the source of alimentation for over 600 million people worldwide. Cassava Bacterial Blight (CBB is caused the bacterium Xanthomonas axonopodis pv. manihotis (Xam. This review will focus on the current knowledge on the molecular cassava-Xam interaction. We will present the different molecular techniques developed to assess the genetic diversity and dynamics of Xam populations. We will also present different methods developed for detecting the pathogen in vegetative planting materials and true seeds and their contribution to reduce the impact of the

  4. Tuber blight development in potato cultivars in response to different genotypes of Phytophthora infestans

    Science.gov (United States)

    Potato late blight, caused by Phytophthora infestans, is one of the most devastating diseases in potatoes, causing significant loses under disease-conducive conditions. Migrations or introduction of new genotypes to a specific region impose a different set of criteria for consideration for potato gr...

  5. Differential responses to pea bacterial blight in stems, leaves and pods under glasshouse and field conditions

    NARCIS (Netherlands)

    Elvira-Recuenco, M.; Bevan, J.R.; Taylor, J.D.

    2003-01-01

    Resistance to pea bacterial blight (Pseudomonas syringae pv. pisi) in different plant parts was assessed in 19 Pisum sativum cultivars and landraces, carrying race-specific resistance genes (R-genes) and two Pisum abyssinicum accessions carrying race-nonspecific resistance. Stems, leaves and pods we

  6. Inheritance of resistance to bacterial streak and hacterial blight in rice

    Institute of Scientific and Technical Information of China (English)

    XUJianlong; WANGHanrong; LINYi; XIYongan

    1998-01-01

    Bacterial streak(BS) caused by Xanthomonas campesiris pv. oryzicola bas become one of the major diseases in southbern rice areas.Up to date, tbere are few reports on the inheritance of resistance to BS and its relationsbip with the resistance to bacterial blight(BB).

  7. Towards Sustainable Potato Late Blight Resistance by Cisgenic R Gene Pyramiding

    NARCIS (Netherlands)

    Kwang-Ryong Jo,; Zhu, S.; Bai, Y.; Hutten, R.C.B.; Kessel, G.J.T.; Vleeshouwers, V.G.A.A.; Jacobsen, E.; Visser, R.G.F.; Vossen, J.H.

    2016-01-01

    This chapter provides an overview of the possibilities of genetic modification (GM) potato breeding in general and specifically to combat the most important disease, late blight. Potato plants are vulnerable to a number of pests and diseases. An enigmatic question concerns whether individual Rpi gen

  8. Elevated [CO2] compromises both Type I and Type II wheat resistance to Fusarium head blight

    Science.gov (United States)

    Fusarium head blight (FHB) is one of the world’s most devastating wheat diseases, and results in significant yield loss and contamination of grain with harmful mycotoxins called trichothecenes. Despite emerging risks of increased mycotoxin contamination in food and feed associated with climate chang...

  9. Identification of potato breeding clones that confer high levels of late blight resistance to their progeny

    Science.gov (United States)

    Since 1996, potato seedling minitubers derived from greenhouse crosses have been grown out under heavy late blight pressure in Toluca, Mexico. A total of 2500 individuals were planted each year along with cv. Alpha as a susceptible control. Percent defoliation readings were taken on a weekly basis u...

  10. Genetic diversity of rice sheath blight isolates (Rhizoctonia solani AG-1 IA) from different rice cultivars

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Rhizoctonia solani AG 1 IA, the non specific, soil borne, and plant casual agent of rice sheath blight, occurring world widely in rice fields, has become a major disease to rice. In this study,relationships among R. solani AG 1 IA isolates, collected from different rice cultivars were reported.

  11. Ranking cultivated blueberry for Mummy Berry Blight and Fruit Infection Incidence

    Science.gov (United States)

    Mummy berry is an important disease of cultivated blueberry. The disease has two distinct phases; a blighting phase initiated by ascospores and a fruit infection stage initiated by conidia. In this study we investigated the resistance of more than 100 blueberry cultivar to both phases of the disease...

  12. Fusarium head blight resistance loci in a stratified population of wheat landraces and varieties

    Science.gov (United States)

    To determine if Chinese and Japanese wheat landraces and varieties have unique sources of Fusarium head blight (FHB) resistance, an association mapping panel of 195 wheat accessions including both commercial varieties and landraces was genotyped with 364 genome-wide simple sequence repeat (SSR) and ...

  13. Investigation of the effect of nitrogen on severity of Fusarium Head Blight in barley

    DEFF Research Database (Denmark)

    Yang, Fen; Jensen, J.D.; Spliid, N.H.;

    2010-01-01

    The effect of nitrogen on Fusarium Head Blight (FHB) in a susceptible barley cultivar was investigated using gel-based proteomics. Barley grown with either 15 or 100 kg ha(-1)N fertilizer was inoculated with Fusarium graminearum (Fg). The storage protein fraction did not change significantly...

  14. Impact of new populations of Phytophthora infestans on integrated late blight management

    NARCIS (Netherlands)

    Flier, W.G.; Kessel, G.J.T.; Bosch, van den G.B.M.; Turkensteen, L.J.

    2002-01-01

    A recent migration of a variable population of P. infestans has largely displaced the clonal A1 population in Western Europe. Sexual reproduction in European late blight populations is now possible and has been reported. The increased levels of aggressiveness form an important epidemiological featur

  15. Multiple minor QTLs are responsible for Fusarium head blight resistance in Chinese wheat landrace Haiyanzhong

    Science.gov (United States)

    Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is a devastatingve disease in wheat (Triticum aestivum L.). Use of host resistance is one of the most effective strategies to minimize the disease damage. Haiyanzhong (HYZ) is a Chinese wheat landrace that shows a high level of resi...

  16. Metabolomics analysis of the effect of elevated co2 on wheat resistance to Fusarium head blight

    Science.gov (United States)

    Climate change is expected to intensify Fusarium head blight (FHB) contamination of wheat and increase the associated risk of mycotoxin contamination in food and feed. Rising CO2 levels are part of climate change with still unknown effects on natural wheat resistance mechanisms against Fusarium gram...

  17. Towards the development of integrated cultural control of tomato late blight (Phytophthora infestans) in Uganda

    NARCIS (Netherlands)

    Tumwine, J.

    1999-01-01

    Tomato ( Lycopersicon esculentum ) is a major vegetable crop in Uganda. Moneymaker, Marglobe, Heinz and Roma are the major commercial varieties grown in the country, the first two being the most popular. Late blight ( Phytophthora infestans ) is the most important disease of Ugandan tomatoes. Tomato

  18. First report of Ascochyta blight of Spotted Locoweed (Astragalus lentiginosus) caused by Ascochyta sp. in Idaho

    Science.gov (United States)

    Characteristic Ascochyta blight lesions were observed on leaves and pods of spotted locoweed (Astragalus lentiginosus) growing at two sites in Twin Falls and Owyhee County, Idaho, USA in June 2005. Lesions appeared similar to those induced by Ascochyta spp. on other wild and cultivated legumes, i.e....

  19. A real-time PCR assay for early detection of eastern filbert blight

    Science.gov (United States)

    Eastern filbert blight (EFB) is a devastating disease of European hazelnut, Corylus avellana, which causes economic losses in Oregon where 99% of the U.S. crop is produced. The causal fungus, Anisogramma anomala, is native to eastern North America, where it is found associated with the American haz...

  20. IDENTIFICATION AND QUANTIFICATION OF DIFFERENTIALLY EXPRESSED GENES ASSOCIATED WITH CITRUS BLIGHT (Citrus spp.

    Directory of Open Access Journals (Sweden)

    José Renato de Abreu

    2015-02-01

    Full Text Available Brazil is the largest citrus producer in the world, being responsible for more than 20% of its production, which is, however still low due to phytosanitary issues such as citrus blight. Citrus blight is an anomaly whose causes still have not yet been determined, therefore there are no efficient control measures to minimize the production losses with the use of resistant varieties being considered the most appropriate method. However, little is known about the genes involved in the defense response of the plants to this anomaly. Considering that many physiological alterations associated with plant stress responses are controlled at a transcriptional level, in this study we sought the identification and characterization of the gene expression products differentially expressed in the response to the citrus blight. Through the suppressive subtractive hybridization technique, expressed cDNA libraries were built using mRNAs isolated from "Cravo" lemon tree roots (Citrus limonia L. Osbeck under "Pera" orange (Citrus sinensis L. Osbeck of healthy and sick plants. 129 clones were obtained by subtraction and their sequences were compared in databases. 34 of them linked to proteins associated to stress processes, while the others were similar to sequences of unknown functions or did not present similarity with sequences deposited in the databases. 3 genes were selected and their expressions were studied by RT - qPCR in real-time. Plants with citrus blight presented an increase of the expression level in two of those genes, suggesting that these can be directly involved with this anomaly.

  1. Fusarium head blight resistance in wheat using the in vitro androgenic approach.

    NARCIS (Netherlands)

    Bruins, M.B.M.

    1998-01-01

    Wheat ( Triticum aestivum L.) belongs to the three most important food crops in the world. In certain years, the crop can suffer considerable damage as a result of Fusarium Head Blight (FHB), especially as no chemical control is effective against this disease. This disease is mainly caused by the fu

  2. Introduction of Several Methods to Control Fusarium Head Blight(FHB)

    Institute of Scientific and Technical Information of China (English)

    张荣; 张敏

    2008-01-01

    Abstract:Fusariam head blight(FHB)is a worldwide destructive disease of wheat in the warm,semi-humid or humid regions,especially serious in China.The disease not only causes significant losses in yield and re duces grain quanlity,but also induces toxin to contaminated seeds,which is harmful to the healthy of human and livestocks,So it is important to control it.There are several methods to control Fusarium head blight (FHB).Such as using Crop rotation,Soil cultivation and Fertiliser,biological control,Fungicides control, transgenes,resistance to control Fusarium head blight(FHB).All of these methods gain some effect,but also exist their deficiency.Sometimes crop rotation had no significant effect on DON contamination of wheat grain,subsequent reductions in DON contamination were inconsistent when using Soil cultivation and Fer tiliser,Unfortunately,under field conditions,the biological control achieved has been shown to be variable and in some tests has failed to give any control,The use of fungicides,however,have not been consistently effective in controlling FHB and in reducing DON formation,transgene-silencing at different generations is a problem to use transgenes,Information on location of QTL for FHB resistance should improve dramatically in the near future on resistance to control Fusarium head blight(FHB).Therefore,it is pressing to improve control methods,especially to DON.

  3. Weather-Based forecasting of Rhizoctonia web blight development on container-grown azalea

    Science.gov (United States)

    Fungicides are the only approach currently used to control Rhizoctonia web blight on container-grown azalea. The most reliable criterion for timing fungicides has been a fixed calendar date with adjustment for year-to-year differences in disease progression made by monitoring early-season increase o...

  4. Unveiling and deploying durability of late blight resistance in potato : from natural stacking to cisgenic stacking

    NARCIS (Netherlands)

    Kwang-Ryong Jo,

    2013-01-01

    The potato, which receives an increased attention as a food crop, has long been in threats from the oomycete Phytophthora infestans, the causal agent of late blight. This disease still remains the most important constraint in potato producing regions of the world. It might cause the complete destruc

  5. Bringing Benefits and Warding off Blights in Due Commandment (Analytic Study Compared with the Jordanian Law)

    Science.gov (United States)

    Al Etoum, Niebal Mohd Ibrahim; Mowafi, Hanan Sami Mohammad; Al Zubaidi, Faraj Hamad Salem

    2016-01-01

    The study aims to highlight the benefits and blights of the due commandment (intestate law) under Jordanian law for the year (2010) in the article (279). The study came in two sections, the first one dealt with the concept of due commandment, its legitimacy, verdict and terms; in the second section, I've dealt with the persons entitled to due…

  6. Southern Blight (Sclerotium rolfsii Sacc.) of Cowpea: Genetic Characterization of Two Sources of Resistance

    Science.gov (United States)

    Field studies were conducted to determine the inheritance of resistance to southern blight (caused by Sclerotium rolfsii Sacc.) exhibited by the cowpea [Vigna unguiculta (L.) Walp.] cultivars Carolina Cream and Brown Crowder, and to determine if a genetic relationship exists for this resistance betw...

  7. Comparative Genomics of Pathogenic and Nonpathogenic Strains of Xanthomonas arboricola Unveil Molecular and Evolutionary Events Linked to Pathoadaptation.

    Science.gov (United States)

    Cesbron, Sophie; Briand, Martial; Essakhi, Salwa; Gironde, Sophie; Boureau, Tristan; Manceau, Charles; Fischer-Le Saux, Marion; Jacques, Marie-Agnès

    2015-01-01

    The bacterial species Xanthomonas arboricola contains plant pathogenic and nonpathogenic strains. It includes the pathogen X. arboricola pv. juglandis, causing the bacterial blight of Juglans regia. The emergence of a new bacterial disease of J. regia in France called vertical oozing canker (VOC) was previously described and the causal agent was identified as a distinct genetic lineage within the pathovar juglandis. Symptoms on walnut leaves and fruits are similar to those of a bacterial blight but VOC includes also cankers on trunk and branches. In this work, we used comparative genomics and physiological tests to detect differences between four X. arboricola strains isolated from walnut tree: strain CFBP 2528 causing walnut blight (WB), strain CFBP 7179 causing VOC and two nonpathogenic strains, CFBP 7634 and CFBP 7651, isolated from healthy walnut buds. Whole genome sequence comparisons revealed that pathogenic strains possess a larger and wider range of mobile genetic elements than nonpathogenic strains. One pathogenic strain, CFBP 7179, possessed a specific integrative and conjugative element (ICE) of 95 kb encoding genes involved in copper resistance, transport and regulation. The type three effector repertoire was larger in pathogenic strains than in nonpathogenic strains. Moreover, CFBP 7634 strain lacked the type three secretion system encoding genes. The flagellar system appeared incomplete and nonfunctional in the pathogenic strain CFBP 2528. Differential sets of chemoreceptor and different repertoires of genes coding adhesins were identified between pathogenic and nonpathogenic strains. Besides these differences, some strain-specific differences were also observed. Altogether, this study provides valuable insights to highlight the mechanisms involved in ecology, environment perception, plant adhesion and interaction, leading to the emergence of new strains in a dynamic environment.

  8. Comparative genomics of pathogenic and nonpathogenic strains of Xanthomonas arboricola unveil molecular and evolutionary events linked to pathoadaptation

    Directory of Open Access Journals (Sweden)

    Sophie eCesbron

    2015-12-01

    Full Text Available The bacterial species Xanthomonas arboricola contains plant pathogenic and nonpathogenic strains. It includes the pathogen X. arboricola pv. juglandis, causing the bacterial blight of Juglans regia. The emergence of a new bacterial disease of Juglans regia in France called vertical oozing canker (VOC was previously described and the causal agent was identified as a distinct genetic lineage within the pathovar juglandis. Symptoms on walnut leaves and fruits are similar to those of a bacterial blight but VOC includes also cankers on trunk and branches. In this work, we used comparative genomics and physiological tests to detect differences between four X. arboricola strains isolated from walnut tree: strain CFBP 2528 causing walnut blight, strain CFBP 7179 causing VOC and two nonpathogenic strains, CFBP 7634 and CFBP 7651, isolated from healthy walnut buds. Whole genome sequence comparisons revealed that pathogenic strains possess a larger and wider range of mobile genetic elements than nonpathogenic strains. One pathogenic strain, CFBP 7179, possessed a specific integrative and conjugative element of 95 kb encoding genes involved in copper resistance, transport and regulation. The type three effector repertoire was larger in pathogenic strains than in nonpathogenic strains. Moreover, CFBP 7634 strain lacked the type three secretion system encoding genes. The flagellar system appeared incomplete and nonfunctional in the pathogenic strain CFBP 2528. Differential sets of chemoreceptor and different repertoires of genes coding adhesins were identified between pathogenic and nonpathogenic strains. Besides these differences, some strain-specific differences were also observed. Altogether, this study provides valuable insights to highlight the mechanisms involved in ecology, environment perception, plant adhesion and interaction, leading to the emergence of new strains in a dynamic environment.

  9. Pathogen Sensors

    Directory of Open Access Journals (Sweden)

    Joseph Irudayaraj

    2009-10-01

    Full Text Available The development of sensors for detecting foodborne pathogens has been motivated by the need to produce safe foods and to provide better healthcare. However, in the more recent times, these needs have been expanded to encompass issues relating to biosecurity, detection of plant and soil pathogens, microbial communities, and the environment. The range of technologies that currently flood the sensor market encompass PCR and microarray-based methods, an assortment of optical sensors (including bioluminescence and fluorescence, in addition to biosensor-based approaches that include piezoelectric, potentiometric, amperometric, and conductometric sensors to name a few. More recently, nanosensors have come into limelight, as a more sensitive and portable alternative, with some commercial success. However, key issues affecting the sensor community is the lack of standardization of the testing protocols and portability, among other desirable elements, which include timeliness, cost-effectiveness, user-friendliness, sensitivity and specificity. [...

  10. Cell surface attachment structures contribute to biofilm formation and xylem colonization by Erwinia amylovora.

    Science.gov (United States)

    Koczan, Jessica M; Lenneman, Bryan R; McGrath, Molly J; Sundin, George W

    2011-10-01

    Biofilm formation plays a critical role in the pathogenesis of Erwinia amylovora and the systemic invasion of plant hosts. The functional role of the exopolysaccharides amylovoran and levan in pathogenesis and biofilm formation has been evaluated. However, the role of biofilm formation, independent of exopolysaccharide production, in pathogenesis and movement within plants has not been studied previously. Evaluation of the role of attachment in E. amylovora biofilm formation and virulence was examined through the analysis of deletion mutants lacking genes encoding structures postulated to function in attachment to surfaces or in cellular aggregation. The genes and gene clusters studied were selected based on in silico analyses. Microscopic analyses and quantitative assays demonstrated that attachment structures such as fimbriae and pili are involved in the attachment of E. amylovora to surfaces and are necessary for the production of mature biofilms. A time course assay indicated that type I fimbriae function earlier in attachment, while type IV pilus structures appear to function later in attachment. Our results indicate that multiple attachment structures are needed for mature biofilm formation and full virulence and that biofilm formation facilitates entry and is necessary for the buildup of large populations of E. amylovora cells in xylem tissue.

  11. Lipopolysaccharide biosynthesis genes discriminate between Rubus- and Spiraeoideae-infective genotypes of Erwinia amylovora.

    Science.gov (United States)

    Rezzonico, Fabio; Braun-Kiewnick, Andrea; Mann, Rachel A; Rodoni, Brendan; Goesmann, Alexander; Duffy, Brion; Smits, Theo H M

    2012-10-01

    Comparative genomic analysis revealed differences in the lipopolysaccharide (LPS) biosynthesis gene cluster between the Rubus-infecting strain ATCC BAA-2158 and the Spiraeoideae-infecting strain CFBP 1430 of Erwinia amylovora. These differences corroborate rpoB-based phylogenetic clustering of E. amylovora into four different groups and enable the discrimination of Spiraeoideae- and Rubus-infecting strains. The structure of the differences between the two groups supports the hypothesis that adaptation to Rubus spp. took place after species separation of E. amylovora and E. pyrifoliae that contrasts with a recently proposed scenario, based on CRISPR data, in which the shift to domesticated apple would have caused an evolutionary bottleneck in the Spiraeoideae-infecting strains of E. amylovora which would be a much earlier event. In the core region of the LPS biosynthetic gene cluster, Spiraeoideae-infecting strains encode three glycosyltransferases and an LPS ligase (Spiraeoideae-type waaL), whereas Rubus-infecting strains encode two glycosyltransferases and a different LPS ligase (Rubus-type waaL). These coding domains share little to no homology at the amino acid level between Rubus- and Spiraeoideae-infecting strains, and this genotypic difference was confirmed by polymerase chain reaction analysis of the associated DNA region in 31 Rubus- and Spiraeoideae-infecting strains. The LPS biosynthesis gene cluster may thus be used as a molecular marker to distinguish between Rubus- and Spiraeoideae-infecting strains of E. amylovora using primers designed in this study.

  12. Characterization of Erwinia amylovora strains from Bulgaria by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Atanasova, Iliana; Urshev, Zoltan; Hristova, Petya; Bogatzevska, Nevena; Moncheva, Penka

    2012-01-01

    The aim of this study was to characterize genetically Bulgarian Erwinia amylovora strains using pulsed-field gel electrophoresis (PFGE) analysis. Fifty E. amylovora strains isolated from different hosts, locations, as well as in different years were analysed by PFGE after XbaI, SpeI, and XhoI digestion of the genomic DNA. The strains were distributed into four groups according to their XbaI-generated profile. About 82% of the strains displayed a PFGE profile identical to that of type Pt2. Three strains belonged to the Central Europe Pt1 type. Two new PFGE profiles, not reported so far, were established--one for a strain isolated from Malus domestica and another for all Fragaria spp. strains. The same grouping of the strains was obtained after analysis of the SpeI digestion patterns. On the basis of PFGE profiles, after XbaI and SpeI digestion, a genetic differentiation between the strains associated with subfamily Maloideae and subfamily Rosoideae was revealed. The presence of more than one PFGE profile in the population of E. amylovora in Bulgaria suggests a multiple source of inoculum.

  13. Identification and characterization of Nip, necrosis-inducing virulence protein of Erwinia carotovora subsp. carotovora.

    Science.gov (United States)

    Mattinen, Laura; Tshuikina, Marina; Mäe, Andres; Pirhonen, Minna

    2004-12-01

    Erwinia carotovora subsp. carotovora is a gram-negative bacterium that causes soft rot disease of many cultivated crops. When a collection of E. carotovora subsp. carotovora isolates was analyzed on a Southern blot using the harpin-encoding gene hrpN as probe, several harpinless isolates were found. Regulation of virulence determinants in one of these, strain SCC3193, has been characterized extensively. It is fully virulent on potato and in Arabidopsis thaliana. An RpoS (SigmaS) mutant of SCC3193, producing elevated levels of secreted proteins, was found to cause lesions resembling the hypersensitive response when infiltrated into tobacco leaf tissue. This phenotype was evident only when bacterial cells had been cultivated on solid minimal medium at low pH and temperature. The protein causing'the cell death was purified and sequenced, and the corresponding gene was cloned. The deduced sequence of the necrosis-inducing protein (Nip) showed homology to necrosis- and ethylene-inducing elicitors of fungi and oomycetes. A mutant strain of E. carotovora subsp. carotovora lacking the nip gene showed reduced virulence in potato tuber assay but was unaffected in virulence in potato stem or on other tested host plants.

  14. Cloning and characterization of a sucrose isomerase from Erwinia rhapontici NX-5 for isomaltulose hyperproduction.

    Science.gov (United States)

    Li, Sha; Cai, Heng; Qing, Yujia; Ren, Ben; Xu, Hong; Zhu, Hongyang; Yao, Jun

    2011-01-01

    The sucrose isomerase (SIase) gene from an efficient strain of Erwinia rhapontici NX-5 for isomaltulose hyperproduction was cloned and overexpressed in Escherichia coli. Protein sequence alignment revealed that SIase was a member of the glycoside hydrolase 13 family. The molecular mass of the purified recombinant protein was estimated at 66 kDa by SDS-PAGE. The SIase had an optimal pH and temperature of 5.0 and 30 °C, respectively, with a K (m) of 257 mmol/l and V (max) of 48.09 μmol/l/s for sucrose. To the best of our knowledge, the recombinant SIase has the most acidic optimum pH for isomaltulose synthesis. When the recombinant E. coli (pET22b- palI) cells were used for isomaltulose synthesis, almost complete conversion of sucrose (550 g/l solution) to isomaltulose was achieved in 1.5 h with high isomaltulose yields (87%). The immobilized E. coli cells remained stable for more than 30 days in a "batch"-type enzyme reactor. This indicated that the recombinant SIase could continuously and efficiently produce isomaltulose.

  15. Isolation and characterization of aniline degradation slightly halophilic bacterium, Erwinia sp. Strain HSA 6.

    Science.gov (United States)

    Li, Junmin; Jin, Zexin; Yu, Binbin

    2010-07-20

    The isolated strain HSA6 is classified as Erwinia amylovora based on 16S rDNA sequence and the morphological and physiological properties. Strain HSA6 is the first reported E. amylovora in pure culture growing with aniline as sole electron donor and carbon source. The suitable pH for strain HSA6 is wide (from 5 to 11). Strain HSA6 is slightly halophilic with growth occurring at 0-10% (v/v) NaCl, and the suitable NaCl concentration for strain HSA6 is from 0% to 6%. The number of bacteria appeared to decrease with an increase in aniline concentration. The number of bacteria appeared to be constant as the wastewater concentration increased from 0% to 20%. However, the number of cells decreased with an increase in wastewater concentration from 30% to 50% and grew very slowly at 50%. The degradation rate of aniline was 100% at 0.5% aniline concentration after 24 h culture. The degradation rate of aniline was found to descend as the concentration of aniline increased from 0.5% to 3% and rose as the culture time increased. Strain HSA6 contains a plasmid with molecular weight higher than 42 kDA. Plasmid curing test and quantitative degradation test showed that strain requires the plasmid for aniline degradation. The gene cluster degrading aniline was determined in the plasmid by PCR amplification.

  16. Purification and characterization of a highly selective sucrose isomerase from Erwinia rhapontici NX-5.

    Science.gov (United States)

    Ren, Ben; Li, Sha; Xu, Hong; Feng, Xiao-Hai; Cai, Heng; Ye, Qi

    2011-06-01

    A highly selective sucrose isomerase (SIase) was purified to homogeneity from the cell-free extract of Erwinia rhapontici NX-5 with a recovery of 27.7% and a fold purification of 213.6. The purified SIase showed a high specific activity of 427.1 U mg(-1) with molecular weight of 65.6 kDa. The K (m) for sucrose was 222 mM while V (max) was 546 U mg(-1). The optimum pH and temperature for SIase activity were 6.0 and 30 °C, respectively. The purified SIase was stable in the temperature range of 10-40 °C and retained 65% of the enzyme activity after 2 weeks' storage at 30 °C. The SIase activity was enhanced by Mg(2+) and Mn(2+), inhibited by Ca(2+), Cu(2+), Zn(2+), and Co(2+), completely inhibited by Hg(2+) and Ag(2+). The purified SIase was strongly inhibited by SDS, while partially inhibited by dimethylformamide, tetrahydrofuran, and PMSF. Additionally, glucose and fructose acted as competitive inhibitors for purified SIase.

  17. Sucrose isomerase and its mutants from Erwinia rhapontici can synthesise α-arbutin.

    Science.gov (United States)

    Zhou, Xing; Zheng, Yuantao; Wei, Xingming; Yang, Kedi; Yang, Xiangkai; Wang, Yuting; Xu, Liming; Du, Liqin; Huang, Ribo

    2011-10-01

    Sucrose isomerase (SI) from Erwinia rhapontici is an intramolecular isomerase that is normally used to synthesise isomaltulose from sucrose by a mechanism of intramolecular transglycosylation. In this study, it was found that SI could synthesise α-arbutin using hydroquinone and sucrose as substrates, via an intermolecular transglycosylation reaction. Five phenylalanine residues (F185, F186, F205, F297, and F321) in the catalytic pocket of SI were chosen for sitedirected mutagenesis. Mutants F185I, F321I, and F321W, whose hydrolytic activities were enhanced after the mutation, could synthesise α-arbutin through intermolecular transglycosylation with a more than two-fold increase in the molar transfer ratio compared with wild type SI. The F297A mutant showed a strong ability to synthesise a novel α-arbutin derivative and a four-fold increase in its specific activity for intermolecular transglycosylation over the wild type. Our findings may lead to a new way to synthesise novel glucoside products such as α-arbutin derivatives by simply manipulating the Phe residues in the catalytic pocket. From the structure superposition, our strategy of manipulating these Phe residues may be applicable to other similar transglycosylating enzymes.

  18. Morphological and biochemical characterization of Erwinia amylovora-induced hypersensitive cell death in apple leaves.

    Science.gov (United States)

    Iakimova, Elena T; Sobiczewski, Piotr; Michalczuk, Lech; Węgrzynowicz-Lesiak, Elżbieta; Mikiciński, Artur; Woltering, Ernst J

    2013-02-01

    In attached apple leaves, spot-inoculated with Erwinia amylovora, the phenotypic appearance of the hypersensitive response (HR) and the participation of ethylene, reactive oxygen species (ROS) and of vacuolar processing enzyme (VPE) (a plant caspase-1-like protease) were analysed. The HR in both the resistant and susceptible genotypes expressed a similar pattern of distinguishable micro HR lesions that progressed into confined macro HR lesions. The HR symptoms in apple were compared to those in non-host tobacco. The morphology of dead cells (protoplast shrinkage and retraction from cell wall) in apple leaves resembled necrotic programmed cell death (PCD). Lesion formation in both cv. Free Redstar (resistant) and cv. Idared (highly susceptible) was preceded by ROS accumulation and elevation of ethylene levels. Treatment of infected leaves with an inhibitor of ethylene synthesis led to a decrease of ethylene emission and suppression of lesion development in both cultivars. In the resistant but not in the susceptible apple cultivar an early and late increase in VPE gene expression was detected. This suggests that VPE might be an underlying component of the response to E. amylovora in resistant apple cultivars. The findings show that in the studied pathosystem the cell death during the HR proceeds through a signal transduction cascade in which ROS, ethylene and VPE pathways play a role.

  19. Incorporating climate change into pest risk models for forest pathogens: a role for cold stress in an era of global warming?

    Directory of Open Access Journals (Sweden)

    Robert Venette

    2013-09-01

    Full Text Available Climate change may alter the distribution and activity of native and alien pathogens that infect trees and, in severe cases, cause tree death. In this study, potential future changes in climate suitability are investigated for three forest pathogens that occur in western North America: the native Arceuthobium tsugense subsp tsugense, hemlock dwarf mistletoe, and two alien invasive species, Dothistroma septosporum, the cause of red band needle blight or Dothistroma needle blight, and Phytophthora ramorum, the cause of sudden oak death or ramorum blight. Specifically, the software CLIMEX is used to calculate Cold-Stress, Heat-Stress, and Dry-Stress indices for each pathogen in 98,224 grid cells in North America. Downscaled climate projections from the general circulation models CGCM1, CSIROMk2, and HadCM3 drive forecasts for 2020, 2050 and 2080. These climate projections are then analyzed to forecast shifts in the geographic extent of abiotic stresses that are severe enough to directly kill pathogen propagules and prevent year-round establishment of these pathogens. Cold stress currently has a major impact on climate suitability for all three pathogens; heat stress is likely to become more significant in the future. I forecast that the geographic extent of cold stress will decline from its current levels by a constant 5% (± 1% of all grid cells in each 30-yr projection horizon for all three pathogens. Forecasts suggest the extent of heat stress will increase concurrently by 4% (± 1% in each 30-yr projection horizon. Drought stress shows no consistent trend over time. No disproportionate effect of climate change on the two alien invasive pathogens over the native is forecasted. These results suggest that forecasts of future climate suitability for pathogens based on historical climate normals are accurate for less than 30 yrs. Adaptive management strategies in forestry will be needed to respond as these changes unfold.

  20. Improvement of Resistance to Bacterial Blight by Marker-Assisted Selection in a Wide Compatibility Restorer Line of Hybrid Rice

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiu-hua; LUO Yan-chang; LIU Qiao-quan; WANG Shou-hai; WU Hsin-kan; LI Cheng-quan; WANG Zong-yang; WU Shuang; GU Ming-hong; WANG De-zheng; DU Shi-yun

    2004-01-01

    4183 is a promising wide compatibility restorer line with good grain quality. Its hybrid rice Shuangyou 4183 (Shuangjiu A/4183) was registered in Anhui Province in 2003. However, the line and its hybrid rice are susceptible to bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo). R4183 carrying Xa21 was developed to improve bacterial blight resistance of 4183 through introducing the broad-spectrum resistance gene Xa21 by marker-aided selection. R4183 had similar level of bacterial blight resistance to IRBB21, the resistant donor, while maintained the wide compatibility, restoring ability and other good economic traits of the recurrent parent 4183. Critical issues on improvement of bacterial blight resistance of hybrid rice and breeding strategies were also discussed.